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Microscale models form a broad class of computational models that simulate fine-scale details, in contrast with macroscale models , which amalgamate details into select categories. [ 2 ] [ 3 ] Microscale and macroscale models can be used together to understand different aspects of the same problem.
Macroscale models can include ordinary , partial , and integro-differential equations, where categories and flows between the categories determine the dynamics, or may involve only algebraic equations . An abstract macroscale model may be combined with more detailed microscale models. Connections between the two scales are related to multiscale modeling . One mathematical technique for multiscale modeling of nanomaterials is based upon the use of multiscale Green's function .
In contrast, microscale models can simulate a variety of details, such as individual bacteria in biofilms , [ 4 ] individual pedestrians in simulated neighborhoods, [ 5 ] individual light beams in ray-tracing imagery , [ 6 ] individual houses in cities, [ 7 ] fine-scale pores and fluid flow in batteries, [ 8 ] fine-scale compartments in meteorology, [ 9 ] fine-scale structures in particulate systems, [ 10 ] and other models where interactions among individuals and background conditions determine the dynamics.
Discrete-event models, individual-based models, and agent-based models are special cases of microscale models. However, microscale models do not require discrete individuals or discrete events. Fine details on topography, buildings, and trees can add microscale detail to meteorological simulations and can connect to what is called mesoscale models in that discipline. [ 9 ] Square-meter-sized landscape resolution available from lidar images allows water flow across land surfaces to be modeled, for example, rivulets and water pockets, using gigabyte-sized arrays of detail. [ 11 ] Models of neural networks may include individual neurons but may run in continuous time and thereby lack precise discrete events. [ 12 ]
Ideas for computational microscale models arose in the earliest days of computing and were applied to complex systems that could not accurately be described by standard mathematical forms.
Two themes emerged in the work of two founders of modern computation around the middle of the 20th century. First, pioneer Alan Turing used simplified macroscale models to understand the chemical basis of morphogenesis , but then proposed and used computational microscale models to understand the nonlinearities and other conditions that would arise in actual biological systems. [ 13 ] Second, pioneer John von Neumann created a cellular automaton to understand the possibilities for self-replication of arbitrarily complex entities, [ 14 ] which had a microscale representation in the cellular automaton but no simplified macroscale form. This second theme is taken to be part of agent-based models , where the entities ultimately can be artificially intelligent agents operating autonomously.
By the last quarter of the 20th century, computational capacity had grown so far [ 15 ] [ 16 ] that up to tens of thousands of individuals or more could be included in microscale models, and that sparse arrays could be applied to also achieve high performance. [ 17 ] Continued increases in computing capacity allowed hundreds of millions of individuals to be simulated on ordinary computers with microscale models by the early 21st century.
The term "microscale model" arose later in the 20th century and now appears in the literature of many branches of physical and biological science. [ 5 ] [ 7 ] [ 8 ] [ 9 ] [ 18 ]
Figure 1 represents a fundamental macroscale model: population growth in an unlimited environment. Its equation is relevant elsewhere, such as compounding growth of capital in economics or exponential decay in physics. It has one amalgamated variable, N ( t ) {\displaystyle N(t)} , the number of individuals in the population at some time t {\displaystyle t} . It has an amalgamated parameter r = β − δ {\displaystyle r=\beta -\delta } , the annual growth rate of the population, calculated as the difference between the annual birth rate β {\displaystyle \beta } and the annual death rate δ {\displaystyle \delta } . Time t {\displaystyle t} can be measured in years, as shown here for illustration, or in any other suitable unit.
The macroscale model of Figure 1 amalgamates parameters and incorporates a number of simplifying approximations:
These approximations of the macroscale model can all be refined in analogous microscale models. On the first approximation listed above—that birth and death rates are constant—the macroscale model of Figure 1 is exactly the mean of a large number of stochastic trials with the growth rate fluctuating randomly in each instance of time. [ 19 ] Microscale stochastic details are subsumed into a partial differential diffusion equation and that equation is used to establish the equivalence.
To relax other assumptions, researchers have applied computational methods. Figure 2 is a sample computational microscale algorithm that corresponds to the macroscale model of Figure 1. When all individuals are identical and mutations in birth and death rates are disabled, the microscale dynamics closely parallel the macroscale dynamics (Figures 3A and 3B). The slight differences between the two models arise from stochastic variations in the microscale version not present in the deterministic macroscale model. These variations will be different each time the algorithm is carried out, arising from intentional variations in random number sequences.
When not all individuals are identical, the microscale dynamics can differ significantly from the macroscale dynamics, simulating more realistic situations than can be modeled at the macroscale (Figures 3C and 3D). The microscale model does not explicitly incorporate the differential equation, though for large populations it simulates it closely. When individuals differ from one another, the system has a well-defined behavior but the differential equations governing that behavior are difficult to codify. The algorithm of Figure 2 is a basic example of what is called an equation-free model . [ 20 ]
When mutations are enabled in the microscale model ( σ > 0 {\displaystyle \sigma >0} ), the population grows more rapidly than in the macroscale model (Figures 3C and 3D). Mutations in parameters allow some individuals to have higher birth rates and others to have lower death rates, and those individuals contribute proportionally more to the population. All else being equal, the average birth rate drifts to higher values and the average death rate drifts to lower values as the simulation progresses. This drift is tracked in the data structures named beta and delta of the microscale algorithm of Figure 2.
The algorithm of Figure 2 is a simplified microscale model using the Euler method . Other algorithms such as the Gillespie method [ 21 ] and the discrete event method [ 17 ] are also used in practice. Versions of the algorithm in practical use include efficiencies such as removing individuals from consideration once they die (to reduce memory requirements and increase speed) and scheduling stochastic events into the future (to provide a continuous time scale and to further improve speed). [ 17 ] Such approaches can be orders of magnitude faster.
The complexity of systems addressed by microscale models leads to complexity in the models themselves, and the specification of a microscale model can be tens or hundreds of times larger than its corresponding macroscale model. (The simplified example of Figure 2 has 25 times as many lines in its specification as does Figure 1.) Since bugs occur in computer software and cannot completely be removed by standard methods such as testing, [ 22 ] and since complex models often are neither published in detail nor peer-reviewed, their validity has been called into question. [ 23 ] Guidelines on best practices for microscale models exist [ 24 ] but no papers on the topic claim a full resolution of the problem of validating complex models.
Computing capacity is reaching levels where populations of entire countries or even the entire world are within the reach of microscale models, and improvements in the census and travel data allow further improvements in parameterizing such models. Remote sensors from Earth-observing satellites and ground-based observatories such as the National Ecological Observatory Network (NEON) provide large amounts of data for calibration. Potential applications range from predicting and reducing the spread of disease to helping understand the dynamics of the earth.
Figure 1. One of the simplest of macroscale models: an ordinary differential equation describing continuous exponential growth . N ( t ) {\displaystyle N(t)} is the size of the population at the time t {\displaystyle t} and d N ( t ) / d t {\displaystyle dN(t)/dt} is the rate of change through time in a single dimension N {\displaystyle N} . N ( 0 ) {\displaystyle N(0)} is the initial population t = 0 {\displaystyle t=0} , β {\displaystyle \beta } is the birth rate per time unit, and δ {\displaystyle \delta } is a death rate per time unit. At the left is the differential form; at the right is the explicit solution in terms of standard mathematical functions, which follows in this case from the differential form. Almost all macroscale models are more complex than this example, in that they have multiple dimensions, lack explicit solutions in terms of standard mathematical functions, and must be understood from their differential forms.
Figure 2. A basic algorithm applying the Euler method to an individual-based model. See text for discussion. The algorithm, represented in pseudocode , begins with invocation of procedure Microscale ( ) {\displaystyle \operatorname {Microscale} ()} , which uses the data structures to carry out the simulation according to the numbered steps described at the right. It repeatedly invokes function Mutation ( v ) {\displaystyle \operatorname {Mutation} (v)} , which returns its parameter perturbed by a random number drawn from a uniform distribution with standard deviation defined by the variable s i g m a {\displaystyle sigma} . (The square root of 12 appears because the standard deviation of a uniform distribution includes that factor.) Function Rand ( ) {\displaystyle \operatorname {Rand} ()} in the algorithm is assumed to return a uniformly distributed random number 0 ≤ R a n d ( ) < 1 {\displaystyle 0\leq Rand()<1} . The data are assumed to be reset to their initial values on each invocation of Microscale ( ) {\displaystyle \operatorname {Microscale} ()} .
Figure 3. Graphical comparison of the dynamics of macroscale and microscale simulations of Figures 1 and 2, respectively. | https://en.wikipedia.org/wiki/Microscale_and_macroscale_models |
Microscale structural metamaterials are synthetic structures that are aimed to yield specific desired mechanical advantages. These designs are often inspired by natural cellular materials such as plant and bone tissue which have superior mechanical efficiency due to their low weight to stiffness ratios.
This is a layer-by-layer additive printing technology which allows for the creation of arbitrary 3-D structures . [ 1 ] Together with nanoscale coating techniques, microstereolithography can create ultralow density, complex microlattices .
The process usually involves a dynamically reconfigurable digital photomask . A 3-D model is decomposed into a series of 2-D planes, the pattern of which is transmitted to the photomask. When shined through by UV light , the mask will transmit the image of the planes onto a lens which subsequently project it onto a photosensitive polymer resin such as 1,6-hexanediol diacrylate (HDDA) causing the liquid to cure in the light exposed areas. These process is repeated for each layer and assembled together to form a 3-D system. Non-polymer lattices can also be created from this process by additional processing. For instance, metallic structures can be created by electroless plating onto the base structure followed by removal of the polymer through thermal heating. Similar deposition techniques can also be used to create ceramic structures.
This technique is an improvement of the layer-by-layer lithography . Additive manufacturing can be time-consuming and create flawed structures. In conventional 3-D printing, oxygen inhibition often causes incomplete curing and bulky surfaces during photosensitive polymerization. [ 2 ] By introducing controlled levels of oxygen, efficient initiation and propagation of continuous polymer chains will result. CLIP proceeds via projecting a continuous sequence of UV images (generated by a digital light-processing imaging unit) through an oxygen-permeable, UV-transparent window below a liquid resin bath. Above a permeable window, there is an oxygen inhibition “dead-zone” maintained by a liquid interface. Above the dead zone, the curing part is continuously drawn out of the resin bath, thereby creating suction forces that constantly renew reactive liquid resin. Unlike convention stereolithography which uses step-by-step processing, CLIP employs a continuous flow.
At low relative density limits, these structures display coupled density to stiffness and strength relationships: E / E s ∝ ( ρ / ρ s ) n {\displaystyle E/E_{s}\propto (\rho /\rho _{s})^{n}} and σ y / σ y s ∝ ( ρ / ρ s ) n {\displaystyle \sigma _{y}/\sigma _{ys}\propto (\rho /\rho _{s})^{n}} where E is the Young’s modulus , y is the yield stress , ρ is the density and subscript s denotes the bulk value of the specified property.
Stretch dominated structures such as octet tress structure have reduced density to stiffness coupling with n around 1 over many magnitudes of density. This allows for the creation of structural metamaterials which are both ultralight, strong, and energy-absorbing, with elastic behavior up to and 50% compression strain. [ 3 ] Often these structures are highly isotropic, with their behavior constant over different loading directions.
Bend dominated structures are usually such as tetrakaidecahedron structure have higher n values that result in non-linear density-to-stiffness ratio, since loading on these crystals are shear rather than tensile as in their stretch-dominated counterpart. However, these structures can also be highly compressive. For instance, 3-D simple cubic bulk graphene aerogels created using layer-by-layer lithography showed lightweight, highly conductive and supercompressible (up to 90% compressive strain) properties. [ 4 ] | https://en.wikipedia.org/wiki/Microscale_metamaterials |
Microscale thermophoresis ( MST ) is a technology for the biophysical analysis of interactions between biomolecules . Microscale thermophoresis is based on the detection of a temperature-induced change in fluorescence of a target as a function of the concentration of a non-fluorescent ligand. The observed change in fluorescence is based on two distinct effects. On the one hand it is based on a temperature related intensity change (TRIC) of the fluorescent probe, which can be affected by binding events. On the other hand, it is based on thermophoresis, the directed movement of particles in a microscopic temperature gradient . Any change of the chemical microenvironment of the fluorescent probe, as well as changes in the hydration shell of biomolecules result in a relative change of the fluorescence detected when a temperature gradient is applied and can be used to determine binding affinities . MST allows measurement of interactions directly in solution without the need of immobilization to a surface (immobilization-free technology).
Stoichiometry
MST has been used to estimate the enthalpic and entropic contributions to biomolecular interactions. [ 10 ]
MST is based on the quantifiable detection of a fluorescence change in a sample when a temperature change is applied. The fluorescence of a target molecule can be extrinsic or intrinsic (aromatic amino acids ) and is altered in temperature gradients due to two distinct effects. On the one hand temperature related intensity change (TRIC), which describes the intrinsic property of fluorophores to change their fluorescence intensity as a function of temperature. The extent of the change in fluorescence intensity is affected by the chemical environment of the fluorescent probe, which can be altered in binding events due to conformational changes or proximity of ligands . [ 11 ] [ 12 ] On the other hand, MST is also based on the directed movement of molecules along temperature gradients, an effect termed thermophoresis. A spatial temperature difference ΔT leads to a change in molecule concentration in the region of elevated temperature, quantified by the Soret coefficient S T :c hot /c cold = exp(-S T ΔT). [ 13 ] [ 14 ] Both, TRIC and thermophoresis contribute to the recorded signal in MST measurements in the following way: ∂/∂T(cF)=c∂F/∂T+F∂c/∂T. The first term in this equation c∂F/∂T describes TRIC as a change in fluorescence intensity (F) as a function of temperature (T), whereas the second term F∂c/∂T describes thermophoresis as the change in particle concentration (c) as a function of temperature. Thermophoresis depends on the interface between molecule and solvent. Under constant buffer conditions, thermophoresis probes the size, charge and solvation entropy of the molecules. The thermophoresis of a fluorescently labeled molecule A typically differs significantly from the thermophoresis of a molecule-target complex AT due to size, charge and solvation entropy differences. This difference in the molecule's thermophoresis is used to quantify the binding in titration experiments under constant buffer conditions.
The thermophoretic movement of the fluorescently labelled molecule is measured by monitoring the fluorescence distribution F inside a capillary. The microscopic temperature gradient is generated by an IR-Laser, which is focused into the capillary and is strongly absorbed by water. The temperature of the aqueous solution in the laser spot is raised by ΔT=1-10 K. Before the IR-Laser is switched on a homogeneous fluorescence distribution F cold is observed inside the capillary. When the IR-Laser is switched on, two effects, occur on the same time-scale, contributing to the new fluorescence distribution F hot . The thermal relaxation induces a binding-dependent drop in the fluorescence of the dye due to its local environmental-dependent response to the temperature jump (TRIC). At the same time molecules typically move from the locally heated region to the outer cold regions. The local concentration of molecules decreases in the heated region until it reaches a steady-state distribution.
While the mass diffusion D dictates the kinetics of depletion, S T determines the steady-state concentration ratio c hot /c cold =exp(-S T ΔT) ≈ 1-S T ΔT under a temperature increase ΔT. The normalized fluorescence F norm =F hot /F cold measures mainly this concentration ratio, in addition to TRIC ∂F/∂T. In the linear approximation we find: F norm =1+(∂F/∂T-S T )ΔT. Due to the linearity of the fluorescence intensity and the thermophoretic depletion, the normalized fluorescence from the unbound molecule F norm (A) and the bound complex F norm (AT) superpose linearly. By denoting x the fraction of molecules bound to targets, the changing fluorescence signal during the titration of target T is given by: F norm =(1-x) F norm (A)+x F norm (AT). [ 11 ]
Quantitative binding parameters are obtained by using a serial dilution of the binding substrate. By plotting F norm against the logarithm of the different concentrations of the dilution series, a sigmoidal binding curve is obtained. This binding curve can directly be fitted with the nonlinear solution of the law of mass action , with the dissociation constant K D as result. [ 15 ] [ 16 ] [ 17 ] | https://en.wikipedia.org/wiki/Microscale_thermophoresis |
A microscanner , or micro scanning mirror , is a microoptoelectromechanical system (MOEMS) in the category of micromirror actuators for dynamic light modulation . Depending upon the type of microscanner, the modulatory movement of a single mirror can be either translatory or rotational, on one or two axes. In the first case, a phase shifting effect takes place. In the second case, the incident light wave is deflected.
Microscanners are different from spatial light modulators and other micromirror actuators which need a matrix of individually addressable mirrors in order to accomplish the desired modulation at any yield. If a single array mirror accomplishes the desired modulation but is operated in parallel with other array mirrors to increase light yield, then the term microscanner array is used.
Common chip dimensions are 4 mm × 5 mm for mirror diameters between 1 and 3 mm. [ 1 ] Larger mirror apertures with side measurements of up to approx. 10 mm × 3 mm can also be produced. [ 2 ] The scan frequencies depend upon the design and mirror size and range between 0.1 and 50 kHz. The deflection movement is either resonant or quasi-static. [ 3 ] With microscanners that are capable of tilting movement, light can be directed over a projection plane.
Many applications requires that a surface is addressed instead of only a single line. For these applications, actuation using a Lissajous pattern can accomplish sinusoidal scan motion, or double resonant operation. Mechanical deflection angles of micro scanning devices reach up to ±30°. [ 4 ] Translational (piston type) microscanners, can attain a mechanical stroke of up to approx. ±500 μm. [ 5 ] This configuration is energy efficient, but requires complicated control electronics. For high end display applications the common choice is raster scanning , where a resonant scanner (for the longer display dimension) is paired with quasi-static scanner (for the shorter dimension). [ 3 ]
The required drive forces for the mirror movement can be provided by various physical principles. In practice, the relevant principles for driving such a mirror are the electromagnetic , electrostatic , thermoelectric , and piezoelectric effects. [ 3 ] Because the physical principles differ in their advantages and disadvantages, the driving principle is chosen according to the application. Specifically, the mechanical solutions required for resonant scanning are very different for those of quasi-static scanning. Thermoelectric actuators are not applicable for high-frequency resonant scanners, but the other three principles can be applied to the full spectrum of applications.
For resonant scanners, one often employed configuration is the indirect drive. In an indirect drive, a small motion in a larger mass is coupled to a large motion in a smaller mass (the mirror) through mechanical amplification at a favorable mode shape. This is in contrast to the more common direct drive, where the actuator mechanism moves the mirror directly. Indirect drives have been implemented for electromagnetic , [ 6 ] electrostatic , [ 7 ] as well as piezoelectric actuators. [ 8 ] [ 9 ] Existing piezoelectric scanners are more efficient using direct drive. [ 3 ]
Electrostatic actuators offer high power similar to electromagnetic drives. In contrast to an electromagnetic drive, the resulting drive force between the drive structures cannot be reversed in polarity. For the realization of quasi-static components with positive and negative effective direction, two drives with positive and negative polarity are required. [ 10 ] As a rule of thumb, vertical comb drives are utilized here. Nevertheless, the highly non-linear drive characteristics in some parts of the deflection area can be hindering for controlling the mirror properly. For that reason many highly developed microscanners today utilize a resonant mode of operation, where an eigenmode is activated. Resonant operation is the most energy-efficient. For beam positioning and applications which are to be static-actuated or linearized-scanned, quasi-static drives are required and therefore of great interest.
Magnetic actuators offer very good linearity of the tilt angle versus the applied signal amplitude, both in static and dynamic operation. The working principle is that a metallic coil is placed on the moving MEMS mirror itself and as the mirror is placed in a magnetic field, the alternating current flowing in the coil generates Lorentz force that tilts the mirror. Magnetic actuation can either be used for actuating 1D or 2D MEMS mirrors. Another characteristic of the magnetically actuated MEMS mirror is the fact that low voltage is required (below 5V) making this actuation compatible with standard CMOS voltage. An advantage of such an actuation type is that MEMS behaviour does not present hysteresis , as opposed to electrostatic actuated MEMS mirrors, which make it very simple to control. Power consumption of magnetically actuated MEMS mirrors can be as low as 0.04 mW. [ 11 ]
Thermoelectric drives produce high driving forces, but they present a few technical drawbacks inherent to their fundamental principle. The actuator has to be thermally well insulated from the environment, as well as being preheated in order to prevent thermal drift due to environmental influences. That is why the necessary heat output and power consumption for a thermal bimorph actuator is relatively high. One further disadvantage is the comparably low displacement which needs to be leveraged to reach usable mechanical deflections. Also thermal actuators are not suitable for high frequency operation due to significant low pass behaviour.
Piezoelectric drives produce high force, but as with electrothermal actuators the stroke length is short. Piezoelectric drives are, however, less susceptible to thermal environmental influences and can also transmit high-frequency drive signals well. To achieve the desired angle some mechanism utilizing mechanical amplification will be required for most applications. This has proven to be difficult for quasi-static scanners, although there are promising approaches in the literature using long meandering flexures for deflection amplification. [ 12 ] [ 13 ] For resonant rotational scanners, on the other hand, scanners using piezoelectric actuation combined with an indirect drive are the highest performer in terms of scan angle and working frequency. [ 8 ] [ 9 ] [ 14 ] However, the technology is newer than electrostatic and electromagnetic drives and remains to be implemented in commercial products. [ 3 ]
Applications for tilting microscanners are numerous and include:
Some of the applications for piston type microscanners are:
Microscanners are usually manufactured with surface or bulk micromechanic processes. As a rule, silicon or BSOI (bonded silicon on insulator ) are used.
Microscanners are smaller, lower mass, and consume smaller amounts of power compared to macroscopic light modulators such as galvanometer scanners . Additionally, microscanners can be integrated with other electronic components such as position sensors. [ 17 ] Microscanners are resistant to environmental influences, and can tolerate humidity, dust, physical shocks in some models up to 2500g, and can operate in temperatures from -20 °C to +80 °C.
With current manufacturing technology microscanners can suffer from high costs and long lead times to delivery. This is an active area of process improvement | https://en.wikipedia.org/wiki/Microscanner |
Microscope image processing is a broad term that covers the use of digital image processing techniques to process, analyze and present images obtained from a microscope . Such processing is now commonplace in a number of diverse fields such as medicine , biological research , cancer research , drug testing , metallurgy , etc. A number of manufacturers of microscopes now specifically design in features that allow the microscopes to interface to an image processing system.
Until the early 1990s, most image acquisition in video microscopy applications was typically done with an analog video camera, often simply closed circuit TV cameras. While this required the use of a frame grabber to digitize the images, video cameras provided images at full video frame rate (25-30 frames per second) allowing live video recording and processing. While the advent of solid state detectors yielded several advantages, the real-time video camera was actually superior in many respects.
Today, acquisition is usually done using a CCD camera mounted in the optical path of the microscope. The camera may be full colour or monochrome. Very often, very high resolution cameras are employed to gain as much direct information as possible. Cryogenic cooling is also common, to minimise noise. Often digital cameras used for this application provide pixel intensity data to a resolution of 12-16 bits, much higher than is used in consumer imaging products.
Ironically, in recent years, much effort has been put into acquiring data at video rates, or higher (25-30 frames per second or higher). What was once easy with off-the-shelf video cameras now requires special, high speed electronics to handle the vast digital data bandwidth.
Higher speed acquisition allows dynamic processes to be observed in real time, or stored for later playback and analysis. Combined with the high image resolution, this approach can generate vast quantities of raw data, which can be a challenge to deal with, even with a modern computer system.
While current CCD detectors allow very high image resolution , often this involves a trade-off because, for a given chip size, as the pixel count increases, the pixel size decreases. As the pixels get smaller, their well depth decreases, reducing the number of electrons that can be stored. In turn, this results in a poorer signal-to-noise ratio .
For best results, one must select an appropriate sensor for a given application. Because microscope images have an intrinsic limiting resolution, it often makes little sense to use a noisy, high resolution detector for image acquisition. A more modest detector, with larger pixels, can often produce much higher quality images because of reduced noise. This is especially important in low-light applications such as fluorescence microscopy .
Moreover, one must also consider the temporal resolution requirements of the application. A lower resolution detector will often have a significantly higher acquisition rate, permitting the observation of faster events. Conversely, if the observed object is motionless, one may wish to acquire images at the highest possible spatial resolution without regard to the time required to acquire a single image.
Image processing for microscopy application begins with fundamental techniques intended to most accurately reproduce the information contained in the microscopic sample. This might include adjusting the brightness and contrast of the image, averaging images to reduce image noise and correcting for illumination non-uniformities. Such processing involves only basic arithmetic operations between images (i.e. addition, subtraction, multiplication and division). The vast majority of processing done on microscope image is of this nature.
Another class of common 2D operations called image convolution are often used to reduce or enhance image details. Such "blurring" and "sharpening" algorithms in most programs work by altering a pixel's value based on a weighted sum of that and the surrounding pixels (a more detailed description of kernel based convolution deserves an entry for itself) or by altering the frequency domain function of the image using Fourier Transform . Most image processing techniques are performed in the Frequency domain.
Other basic two dimensional techniques include operations such as image rotation, warping, color balancing etc.
At times, advanced techniques are employed with the goal of "undoing" the distortion of the optical path of the microscope, thus eliminating distortions and blurring caused by the instrumentation. This process is called deconvolution , and a variety of algorithms have been developed, some of great mathematical complexity. The end result is an image far sharper and clearer than could be obtained in the optical domain alone. This is typically a 3-dimensional operation, that analyzes a volumetric image (i.e. images taken at a variety of focal planes through the sample) and uses this data to reconstruct a more accurate 3-dimensional image.
Another common requirement is to take a series of images at a fixed position, but at different focal depths. Since most microscopic samples are essentially transparent, and the depth of field of the focused sample is exceptionally narrow, it is possible to capture images "through" a three-dimensional object using 2D equipment like confocal microscopes . Software is then able to reconstruct a 3D model of the original sample which may be manipulated appropriately. The processing turns a 2D instrument into a 3D instrument, which would not otherwise exist. In recent times this technique has led to a number of scientific discoveries in cell biology.
Analysis of images will vary considerably according to application. Typical analysis includes determining where the edges of an object are, counting similar objects, calculating the area, perimeter length and other useful measurements of each object. A common approach is to create an image mask which only includes pixels that match certain criteria, then perform simpler scanning operations on the resulting mask. It is also possible to label objects and track their motion over a series of frames in a video sequence.
Russ, John C. (2006-12-19) [1992]. The Image Processing Handbook (5th ed.). CRC Press. ISBN 0-8493-7254-2 . | https://en.wikipedia.org/wiki/Microscope_image_processing |
A microscope slide is a thin flat piece of glass , typically 75 by 26 mm (3 by 1 inches) and about 1 mm thick, used to hold objects for examination under a microscope . Typically the object is mounted (secured) on the slide, and then both are inserted together in the microscope for viewing. This arrangement allows several slide-mounted objects to be quickly inserted and removed from the microscope, labeled, transported, and stored in appropriate slide cases or folders etc.
Microscope slides are often used together with a cover slip or cover glass, a smaller and thinner sheet of glass that is placed over the specimen. Slides are held in place on the microscope's stage by slide clips, slide clamps or a cross-table which is used to achieve precise, remote movement of the slide upon the microscope's stage (such as in an automated/computer operated system, or where touching the slide with fingers is inappropriate either due to the risk of contamination or lack of precision).
The origin of the concept was pieces of ivory or bone , containing specimens held between disks of transparent mica , that would slide into the gap between the stage and the objective. [ 1 ] These "sliders" were popular in Victorian-era England until the Royal Microscopical Society introduced the standardized glass microscope slide. [ 2 ]
A standard microscope slide measures about 75 mm by 25 mm (3″ by 1″) and is about 1 mm thick. A range of other sizes are available for various special purposes, such as 75 x 50 mm for geological use, 46 x 27 mm for petrographic studies, and 48 x 28 mm for thin sections . Slides are usually made of common glass and their edges are often finely ground or polished.
Microscope slides are usually made of optical quality glass , such as soda lime glass or borosilicate glass , but specialty plastics are also used. Fused quartz slides are often used when ultraviolet transparency is important, e.g. in fluorescence microscopy . [ 3 ] [ 4 ]
While plain slides are the most common, there are several specialized types. A concavity slide or cavity slide has one or more shallow depressions ("wells"), designed to hold slightly thicker objects, and certain samples such as liquids and tissue cultures . [ 5 ] Slides may have rounded corners for increased safety or robustness, or a cut-off corner for use with a slide clamp or cross-table, where the slide is secured by a spring-loaded curved arm contacting one corner, forcing the opposing corner of the slide against a right angled arm which does not move. If this system were used with a slide which did not incorporate these cut-off corners, the corners would chip and the slide could shatter. [ 5 ]
A graticule slide is marked with a grid of lines (for example, a 1 mm grid) that allows the size of objects seen under magnification to be easily estimated and provides reference areas for counting minute objects. Sometimes one square of the grid will itself be subdivided into a finer grid. Slides for specialized applications, such as hemocytometers for cell counting, may have various reservoirs, channels and barriers etched or ground on their upper surface. [ 6 ] Various permanent markings or masks may be printed , sand-blasted , or deposited on the surface by the manufacturer, usually with inert materials such as PTFE . [ 7 ]
Some slides have a frosted or enamel-coated area at one end, for labeling with a pencil or pen. [ 5 ] Slides may have special coatings applied by the manufacturer, e.g. for chemical inertness or enhanced cell adhesion . The coating may have a permanent electric charge to hold thin or powdery samples. Common coatings include poly-L-lysine , silanes , epoxy resins , [ 5 ] [ 7 ] or even gold . [ 8 ]
The mounting of specimens on microscope slides is often critical for successful viewing. The problem has been given much attention in the last two centuries and is a well-developed area with many specialized and sometimes quite sophisticated techniques. Specimens are often held into place using the smaller glass cover slips .
The main function of the cover slip is to keep solid specimens pressed flat, and liquid samples shaped into a flat layer of even thickness. This is necessary because high-resolution microscopes have a very narrow region within which they focus.
The cover glass often has several other functions. It holds the specimen in place (either by the weight of the cover slip or, in the case of a wet mount, by surface tension ) and protects the specimen from dust and accidental contact. It protects the microscope's objective lens from contacting the specimen and vice versa; in oil immersion microscopy or water immersion microscopy the cover slip prevents contact between the immersion liquid and the specimen. The cover slip can be glued to the slide so as to seal off the specimen, retarding dehydration and oxidation of the specimen and also preventing contamination. A number of sealants are in use, including commercial sealants, laboratory preparations, or even regular clear nail polish , depending on the sample. A solvent-free sealant that can be used for live cell samples is "valap", a mixture of vaseline , lanolin and paraffin in equal parts. [ 9 ] Microbial and cell cultures can be grown directly on the cover slip before it is placed on the slide, and specimens may be permanently mounted on the slip instead of on the slide. [ 9 ]
Cover slips are available in a range of sizes and thicknesses. [ 10 ] Using the wrong thickness can result in spherical aberration and a reduction in resolution and image intensity. Specialty objectives may be used to image specimens without coverslips, or may have correction collars that permit a user to accommodate for alternative coverslip thickness. [ 11 ] [ 12 ]
In a dry mount , the simplest kind of mounting, the object is merely placed on the slide. A cover slip may be placed on top to protect the specimen and the microscope's objective and to keep the specimen still and pressed flat. This mounting can be successfully used for viewing specimens like pollen, feathers, hairs, etc. It is also used to examine particles caught in transparent membrane filters (e.g., in analysis of airborne dust ).
In a wet mount , the specimen is placed in a drop of iodine or other liquid held between the slide and the cover slip by surface tension. This method is commonly used, for example, to view microscopic organisms that grow in pond water or other liquid media, especially lakes.
For pathological and biological research, the specimen usually undergoes a complex histological preparation that involves fixing it to prevent decay, removing any water contained in it, replacing the water with paraffin , cutting it into very thin sections using a microtome , placing the sections on a microscope slide, staining the tissue using various stains to reveal specific tissue components, clearing the tissue to render it transparent and covering it with a coverslip and mounting medium.
Strewn mounting describes the production of palynological microscope slides by suspending a concentrated sample in distilled water , placing the samples on a slide, and allowing the water to evaporate . [ 13 ]
The mounting medium is the solution in which the specimen is embedded, generally under a cover glass. Simple liquids like water or glycerol can be considered mounting media, though the term generally refers to compounds that harden into a permanent mount. Popular mounting media include Permount , [ 14 ] and Hoyer's mounting medium and an alternative glycerine jelly [ 15 ] Properties of a good mounting medium include having a refractive index close to that of glass (1.518), non-reactivity with the specimen, stability over time without crystallizing, darkening, or changing refractive index, solubility in the medium the specimen was prepared in (either aqueous or non-polar , such as xylene or toluene ), and not causing the specimen stain to fade or leach. [ 16 ]
Popularly used in immunofluorescent cytochemistry where the fluorescence cannot be archived. The temporary storage must be done in a dark moist chamber. Common examples are:
Used when a permanent mount is required
In contrast to mounting necessary for glass coverslips, somewhat similar mounting can be done for bulkier specimen preservation in glass containers in museums. However an entirely different type of mounting is done for sample preparation , which can be for biological or nonbiological materials and is further subdivided into "hot"(compressive) and "cold" (castable) type mounting processes. [ 18 ] [ 19 ] Though named "mounting", it is more akin to embedding in histology and should not be confused with the mounting described above. The term mounting in other fields has numerous other meanings. | https://en.wikipedia.org/wiki/Microscope_slide |
The principle of microscopic reversibility in physics and chemistry is twofold:
Corresponding to every individual process there is a reverse process, and in a state of equilibrium the average rate of every process is equal to the average rate of its reverse process. [ 1 ]
The idea of microscopic reversibility was born together with physical kinetics. In 1872, Ludwig Boltzmann represented kinetics of gases as statistical ensemble of elementary collisions. [ 2 ] Equations of mechanics are reversible in time, hence, the reverse collisions obey the same laws. This reversibility of collisions is the first example of microreversibility. According to Boltzmann, this microreversibility implies the principle of detailed balance for collisions: at the equilibrium ensemble each collision is equilibrated by its reverse collision. [ 2 ] These ideas of Boltzmann were analyzed in detail and generalized by Richard C. Tolman . [ 3 ]
In chemistry, J. H. van't Hoff (1884) [ 4 ] came up with the idea that equilibrium has dynamical nature and is a result of the balance between the forward and backward reaction rates. He did not study reaction mechanisms with many elementary reactions and could not formulate the principle of detailed balance for complex reactions. In 1901, Rudolf Wegscheider introduced the principle of detailed balance for complex chemical reactions. [ 5 ] He found that for a complex reaction the principle of detailed balance implies important and non-trivial relations between reaction rate constants for different reactions. In particular, he demonstrated that the irreversible cycles of reaction are impossible and for the reversible cycles the product of constants of the forward reactions (in the "clockwise" direction) is equal to the product of constants of the reverse reactions (in the "anticlockwise" direction). Lars Onsager (1931) used these relations in his well-known work, [ 6 ] without direct citation but with the following remark:
"Here, however, the chemists are accustomed to impose a very interesting additional restriction, namely: when the equilibrium is reached each individual reaction must balance itself. They require that the transition A → B {\displaystyle A\to B} must take place just as frequently as the reverse transition B → A {\displaystyle B\to A} etc."
The quantum theory of emission and absorption developed by Albert Einstein (1916, 1917) [ 7 ] gives an example of application of the microreversibility and detailed balance to development of a new branch of kinetic theory.
Sometimes, the principle of detailed balance is formulated in the narrow sense, for chemical reactions only [ 8 ] but in the history of physics it has the broader use: it was invented for collisions, used for emission and absorption of quanta, for transport processes [ 9 ] and for many other phenomena.
In its modern form, the principle of microreversibility was published by Lewis (1925). [ 1 ] In the classical textbooks [ 3 ] [ 10 ] full theory and many examples of applications are presented.
The Newton and the Schrödinger equations in the absence of the macroscopic magnetic fields and in the inertial frame of reference are T-invariant: if X(t) is a solution then X(-t) is also a solution (here X is the vector of all dynamic variables, including all the coordinates of particles for the Newton equations and the wave function in the configuration space for the Schrödinger equation).
There are two sources of the violation of this rule:
In physics and chemistry, there are two main macroscopic consequences of the time-reversibility of microscopic dynamics: the principle of detailed balance and the Onsager reciprocal relations .
The statistical description of the macroscopic process as an ensemble of the elementary indivisible events (collisions) was invented by L. Boltzmann and formalised in the Boltzmann equation . He discovered that the time-reversibility of the Newtonian dynamics leads to the detailed balance for collision: in equilibrium collisions are equilibrated by their reverse collisions. This principle allowed Boltzmann to deduce simple and nice formula for entropy production and prove his famous H-theorem . [ 2 ] In this way, microscopic reversibility was used to prove macroscopic irreversibility and convergence of ensembles of molecules to their thermodynamic equilibria.
Another macroscopic consequence of microscopic reversibility is the symmetry of kinetic coefficients, the so-called reciprocal relations. The reciprocal relations were discovered in the 19th century by Thomson and Helmholtz for some phenomena but the general theory was proposed by Lars Onsager in 1931. [ 6 ] He found also the connection between the reciprocal relations and detailed balance. For the equations of the law of mass action the reciprocal relations appear in the linear approximation near equilibrium as a consequence of the detailed balance conditions. According to the reciprocal relations, the damped oscillations in homogeneous closed systems near thermodynamic equilibria are impossible because the spectrum of symmetric operators is real. Therefore, the relaxation to equilibrium in such a system is monotone if it is sufficiently close to the equilibrium. | https://en.wikipedia.org/wiki/Microscopic_reversibility |
The microscopic scale (from Ancient Greek μικρός ( mikrós ) ' small ' and σκοπέω ( skopéō ) ' to look (at); examine, inspect ' ) is the scale of objects and events smaller than those that can easily be seen by the naked eye , requiring a lens or microscope to see them clearly. [ 1 ] In physics , the microscopic scale is sometimes regarded as the scale between the macroscopic scale and the quantum scale . [ 2 ] [ 3 ] Microscopic units and measurements are used to classify and describe very small objects. One common microscopic length scale unit is the micrometre (also called a micron ) (symbol: μm), which is one millionth of a metre .
Whilst compound microscopes were first developed in the 1590s, the significance of the microscopic scale was only truly established in the 1600s when Marcello Malphigi and Antonie van Leeuwenhoek microscopically observed frog lungs and microorganisms. As microbiology was established, the significance of making scientific observations at a microscopic level increased. [ 4 ]
Published in 1665, Robert Hooke 's book Micrographia details his microscopic observations including fossils insects, sponges, and plants, which was possible through his development of the compound microscope. During his studies of cork, he discovered plant cells and coined the term ' cell '. [ 5 ]
Prior to the use of the micro- prefix, other terms were originally incorporated into the International metric system in 1795, such as centi- which represented a factor of 10 -2 , and milli- , which represented a factor of 10 -3 . [ 6 ]
Over time the importance of measurements made at the microscopic scale grew, and an instrument named the Millionometre was developed by watch-making company owner Antoine LeCoultre in 1844. This instrument had the ability to precisely measure objects to the nearest micrometre. [ 6 ]
The British Association for the Advancement of Science committee incorporated the micro- prefix into the newly established CGS system in 1873. [ 6 ]
The micro- prefix was finally added to the official SI system in 1960, acknowledging measurements that were made at an even smaller level, denoting a factor of 10 -6 . [ 6 ]
By convention, the microscopic scale also includes classes of objects that are most commonly too small to see but of which some members are large enough to be observed with the eye. Such groups include the Cladocera , planktonic green algae of which Volvox is readily observable, and the protozoa of which Stentor can be easily seen without aid.
The submicroscopic scale similarly includes objects that are too small to see with an optical microscope . [ 2 ]
In thermodynamics and statistical mechanics , the microscopic scale is the scale at which we do not measure or directly observe the precise state of a thermodynamic system – such detailed states of a system are called microstates. We instead measure thermodynamic variables at a macroscopic scale , i.e. the macrostate . [ citation needed ]
As the microscopic scale covers any object that cannot be seen by the naked eye, yet is visible under a microscope, the range of objects that fall under this scale can be as small as an atom, visible underneath a transmission electron microscope . [ 8 ] Microscope types are often distinguished by their mechanism and application, and can be divided into two general categories. [ 9 ]
Amongst light microscopes, the utilised objective lens dictates how small of an object can be seen. These varying objective lenses can change the resolving power of the microscope, which determines the shortest distance that somebody is able to distinguish two separate objects through that microscope lens. It is important to note that the resolution between two objects varies from individual to individual, [ 9 ] but the strength of the objective lenses can be quantified. [ 11 ]
In the 1660s, Antonie van Leeuwenhoek devised a simple microscope utilising a single spherical lens mounted between two thin brass plates. Depending on the quality of the lens, magnifications of between 70x and 250x were possible. The specimen to be examined was mounted on a point on a finely threaded rod. [ 12 ] [ 13 ]
Compound light microscopes have a short focal length objective lens which produces a real image which is examined using a longer focal length eyepiece. The ratio of the focal length of the objective and the eyepiece, when mounted in a standard tube length, gives an approximate magnification of the system. Due to their design, compound microscopes have improved resolving power and contrast in comparison to simple microscopes, [ 11 ] and can be used to view the structure, shape and motility of a cell and its organisms, [ 14 ] which can be as small as 0.1 micrometres. [ 15 ]
While electron microscopes are still a form of compound microscope, their use of electron beams to illuminate objects varies in mechanism significantly from compound light microscopes, allowing them to have a much higher resolving power, and magnification approximately 10,000 times more than light microscopes. [ 14 ] These can be used to view objects such as atoms , which are as small as 0.001 micrometres. [ 1 ]
During forensic investigations, trace evidence from crime scenes such as blood, fingerprints and fibres can be closely examined under microscopes, even to the extent of determining the age of a trace. Along with other specimens, biological traces can be used to accurately identify individuals present at a location, down to cells found in their blood. [ 16 ]
When the monetary value of gems is determined, various professions in gemology require systematic observation of the microscopic physical and optical properties of gemstones. [ 17 ] This can involve the use of stereo microscopes to evaluate these qualities, to eventually determine the value of each individual jewel or gemstone. [ 18 ] This can be done similarly in evaluations of gold and other metals. [ 17 ]
When assessing road materials, the microscopic composition of the infrastructure is vital in determining the longevity and safety of the road, and the different requirements of varying locations. As chemical properties such as water permeability, structural stability and heat resistance affect the performance of different materials used in pavement mixes, they are taken into consideration when building for roads according to the traffic, weather, supply and budget in that area. [ 19 ]
In medicine , diagnoses can be made with the assistance of microscopic observation of patient biopsies , such as cancer cells. Pathology and cytology reports include a microscopic description, which consists of analyses performed using microscopes, histochemical stains or flow cytometry . These methods can determine the structure of the diseased tissue and the severity of the disease, and early detection is possible through identification of microscopic indications of illness. [ 21 ]
Whilst use of the microscopic scale has many roles and purposes in the scientific field, there are many biochemical patterns observed microscopically that have contributed significantly to the understanding of how human life relies on microscopic structures to function and live. [ citation needed ]
Antonie van Leeuwenhoek was not only a contributor to the invention of the microscope, he is also referred to as the "father of Microbiology". This is due to his significant contributions in the initial observation and documentation of unicellular organisms such as bacteria and spermatozoa, and microscopic human tissue such as muscle fibres and capillaries. [ 22 ]
Genetic manipulation of energy-regulating mitochondria under microscopic principles has also been found to extend organism lifespan, tackling age-associated issues in humans such as Parkinson's , Alzheimer's and multiple sclerosis . By increasing the amount of energy products made by mitochondria, the lifespan of its cell, and thus organism, increases. [ 23 ]
Microscopic analysis of the spatial distribution of points within DNA heterochromatin centromeres emphasise the role of the centromeric regions of chromosomes in nuclei undergoing the interphase part of cell mitosis . Such microscopic observations suggest nonrandom distribution and precise structure of centromeres during mitosis is a vital contributor to successful cell function and growth, even in cancer cells. [ 24 ]
The entropy and disorder of the universe can be observed at a microscopic scale, with reference to the second and third law of thermodynamics . In some cases, this can involve calculating the entropy change within a container of expanding gas molecules and relating it to the entropy change of its environment and the universe. [ 26 ]
Ecologists monitor the state of an ecosystem over time by identifying microscopic features within the environment. This includes the temperature and CO 2 tolerance of microorganisms such as ciliates, and their interactions with othrt Protozoa. Additionally, microscopic factors such as movement and motility can be observed in water samples of that ecosystem. [ 27 ]
Branches of geology involve the study of the Earth's structure at a microscopic level. Physical characteristics of rocks are recorded, and in petrography there is a specific focus on the examination of microscopic details of rocks. Similar to scanning electron microscopes, electron microprobes can be used in petrology to observe the condition that allows rocks to form, which can inform the origin of these samples. In structural geology , petrographic microscopes allow the study of rock microstructures, to determine how geologic features such as tectonic plates affect the likelihood of earthquakes and groundwater movement. [ 28 ]
There have been both advances in microscopic technology, and discoveries in other areas of knowledge as a result of microscopic technology. [ 30 ]
In conjunction with fluorescent tagging, molecular details in singular amyloid proteins can be studied through new light microscopy techniques, and their relation to Alzheimer's and Parkinson's disease. [ 31 ]
Other improvements in light microscopy include the ability to view sub-wavelength, nanosized objects. [ 32 ] Nanoscale imaging via atomic force microscopy has also been improved to allow a more precise observation of small amounts of complex objects, such as cell membranes . [ 33 ]
Coherent microscopic patterns discovered in chemical systems support ideas of the resilience of certain substances against entropic environments. This research is being utilised to inform the productions of solar fuels , and the improvement of renewable energy. [ 35 ]
A microscopic musical instrument called the Micronium has also been developed through micromechanics , consisting of springs the thickness of human hair being plucked by microscopic comb drives. This is a very minimal movement that produces an audible noise to the human ear, which was not previously done by past attempts with microscopic instruments. [ 36 ] | https://en.wikipedia.org/wiki/Microscopic_scale |
A microscopic theory is one that contains an explanation at the atomic or subatomic level in contrast to a higher level or classical macroscopic or phenomenological theory . e.g. in superconductivity BCS theory is a microscopic theory.
This atomic, molecular, and optical physics –related article is a stub . You can help Wikipedia by expanding it . | https://en.wikipedia.org/wiki/Microscopic_theory |
Microscopical researches into the accordance in the structure and growth of animals and plants is a famous treatise by Theodor Schwann published in 1839 which officially formulated the basis of the cell theory . [ 1 ] [ 2 ] The original title was Mikroskopische Untersuchungen über die Uebereinstimmung in der Struktur und dem Wachsthum der Thiere und Pflanzen. [ 1 ] The book has been called "a conspicuous milestone in nineteenth century biology" by Karl Sudhoff and "epoch making" By Francis Münzer. [ 3 ]
The book, originally published in German , was translated to English in 1847 by Henry Spencer Smith in an edition that also contained the treatise Phytogenesis , by Matthias Schleiden . [ 4 ]
Besides the theoretical work, that Schwann called a "philosophical" section of general anatomy , [ 4 ] Schwann provided several plates with drawings of cells and tissues and discussions of observations of other microscopists. [ 4 ]
Schwann dedicated a chapter of the treatise to explicitly formulate the cell theory, stating that (" the elementary parts of all tissues are formed of cells ” and that “ there is one universal principle of development for the elementary parts of organisms... and this principle is in the formation of cells" (Henry Smith's translation, 1847). [ 2 ] [ 4 ] His book had the goal to prove via observations that the cell theory put forth for plants by Matthias Schleiden was equally valid for animals. [ 2 ] [ 4 ]
The book is credited with the first description of what would later be called Schwann cell , a type of glial cell . [ 3 ] The description of the cells was evident from passages such as: [ 3 ]
Some, however, appear to remain for a longer period; occasionally, although rarely, a cell-nucleui is here and there seen upon the side of a nerve (the white substance of which is completely developed), lying in the pale border, which surrounds the white substance. Fig. 9,c and d, exhibits them from the nervus vagus of a calf.
and
Pl. 4, fig. 6 represents a portion of the ischiatic, and fig.7, of the brachial nerve of such a foetus. We observe a palish, and very minutely-granulated cord, which, in consequence of certain longitudinal shadings, such as the delineation exhibits, presents the appearance of a coarse fibrous structure. Round or for the most part oval corpuscles, which are immediately recognized as cell-nuclei, and which sometimes also contain one or two nucleoli, are generally seen in the course of these shaded parts,throughout the entire thickness of the cord.
The book is also credited with the introduction of the term "metabolism" for the following quote in the chapter "Theory of Cells": [ 5 ]
The question, then, as to the fundamental power of organised bodies resolves itself into that of the fundamental powers of the individual cells.”… These phenomena may be arranged in two natural groups: first, those which relate to the combination of molecules to form a cell; secondly, those which result from chemical changes either in the component particles of the cell itself or in the surrounding cytoblastema, and may be called metabolic phenomena (implying that which is liable to occasion or suffer change) | https://en.wikipedia.org/wiki/Microscopical_researches_into_the_accordance_in_the_structure_and_growth_of_animals_and_plants |
Microscopy is the technical field of using microscopes to view subjects too small to be seen with the naked eye (objects that are not within the resolution range of the normal eye). [ 1 ] There are three well-known branches of microscopy: optical , electron , and scanning probe microscopy , along with the emerging field of X-ray microscopy . [ citation needed ]
Optical microscopy and electron microscopy involve the diffraction , reflection , or refraction of electromagnetic radiation /electron beams interacting with the specimen , and the collection of the scattered radiation or another signal in order to create an image. This process may be carried out by wide-field irradiation of the sample (for example standard light microscopy and transmission electron microscopy ) or by scanning a fine beam over the sample (for example confocal laser scanning microscopy and scanning electron microscopy ). Scanning probe microscopy involves the interaction of a scanning probe with the surface of the object of interest. The development of microscopy revolutionized biology , gave rise to the field of histology and so remains an essential technique in the life and physical sciences . X-ray microscopy is three-dimensional and non-destructive, allowing for repeated imaging of the same sample for in situ or 4D studies, and providing the ability to "see inside" the sample being studied before sacrificing it to higher resolution techniques. A 3D X-ray microscope uses the technique of computed tomography ( microCT ), rotating the sample 360 degrees and reconstructing the images. CT is typically carried out with a flat panel display. A 3D X-ray microscope employs a range of objectives, e.g., from 4X to 40X, and can also include a flat panel.
The field of microscopy ( optical microscopy ) dates back to at least the 17th-century. Earlier microscopes, single lens magnifying glasses with limited magnification, date at least as far back as the wide spread use of lenses in eyeglasses in the 13th century [ 2 ] but more advanced compound microscopes first appeared in Europe around 1620 [ 3 ] [ 4 ] The earliest practitioners of microscopy include Galileo Galilei , who found in 1610 that he could close focus his telescope to view small objects close up [ 5 ] [ 6 ] and Cornelis Drebbel , who may have invented the compound microscope around 1620. [ 7 ] [ 8 ] Antonie van Leeuwenhoek developed a very high magnification simple microscope in the 1670s and is often considered to be the first acknowledged microscopist and microbiologist . [ 9 ] [ 10 ]
Optical or light microscopy involves passing visible light transmitted through or reflected from the sample through a single lens or multiple lenses to allow a magnified view of the sample. [ 11 ] The resulting image can be detected directly by the eye, imaged on a photographic plate , or captured digitally . The single lens with its attachments, or the system of lenses and imaging equipment, along with the appropriate lighting equipment, sample stage, and support, makes up the basic light microscope. The most recent development is the digital microscope , which uses a CCD camera to focus on the exhibit of interest. The image is shown on a computer screen, so eye-pieces are unnecessary. [ 12 ]
Limitations of standard optical microscopy ( bright field microscopy ) lie in three areas;
Live cells in particular generally lack sufficient contrast to be studied successfully, since the internal structures of the cell are colorless and transparent. The most common way to increase contrast is to stain the structures with selective dyes, but this often involves killing and fixing the sample. [ 15 ] Staining may also introduce artifacts , which are apparent structural details that are caused by the processing of the specimen and are thus not features of the specimen. In general, these techniques make use of differences in the refractive index of cell structures. Bright-field microscopy is comparable to looking through a glass window: one sees not the glass but merely the dirt on the glass. There is a difference, as glass is a denser material, and this creates a difference in phase of the light passing through. The human eye is not sensitive to this difference in phase, but clever optical solutions have been devised to change this difference in phase into a difference in amplitude (light intensity). [ citation needed ]
To improve specimen contrast or highlight structures in a sample, special techniques must be used. A huge selection of microscopy techniques are available to increase contrast or label a sample.
Bright field microscopy is the simplest of all the light microscopy techniques. Sample illumination is via transmitted white light, i.e. illuminated from below and observed from above. Limitations include low contrast of most biological samples and low apparent resolution due to the blur of out-of-focus material. The simplicity of the technique and the minimal sample preparation required are significant advantages. [ citation needed ]
The use of oblique (from the side) illumination gives the image a three-dimensional appearance and can highlight otherwise invisible features. A more recent technique based on this method is Hoffmann's modulation contrast , a system found on inverted microscopes for use in cell culture. Oblique illumination enhances contrast even in clear specimens; however, because light enters off-axis, the position of an object will appear to shift as the focus is changed. This limitation makes techniques like optical sectioning or accurate measurement on the z-axis impossible.
Dark field microscopy is a technique for improving the contrast of unstained, transparent specimens. [ 16 ] Dark field illumination uses a carefully aligned light source to minimize the quantity of directly transmitted (unscattered) light entering the image plane, collecting only the light scattered by the sample. Dark field can dramatically improve image contrast – especially of transparent objects – while requiring little equipment setup or sample preparation. However, the technique suffers from low light intensity in the final image of many biological samples and continues to be affected by low apparent resolution.
Rheinberg illumination is a variant of dark field illumination in which transparent, colored filters are inserted just before the condenser so that light rays at high aperture are differently colored than those at low aperture (i.e., the background to the specimen may be blue while the object appears self-luminous red). Other color combinations are possible, but their effectiveness is quite variable. [ 17 ]
Dispersion staining is an optical technique that results in a colored image of a colorless object. This is an optical staining technique and requires no stains or dyes to produce a color effect. There are five different microscope configurations used in the broader technique of dispersion staining. They include brightfield Becke line, oblique, darkfield, phase contrast, and objective stop dispersion staining.
More sophisticated techniques will show proportional differences in optical density. Phase contrast is a widely used technique that shows differences in refractive index as difference in contrast. It was developed by the Dutch physicist Frits Zernike in the 1930s (for which he was awarded the Nobel Prize in 1953). The nucleus in a cell for example will show up darkly against the surrounding cytoplasm. Contrast is excellent; however it is not for use with thick objects. Frequently, a halo is formed even around small objects, which obscures detail. The system consists of a circular annulus in the condenser, which produces a cone of light. This cone is superimposed on a similar sized ring within the phase-objective. Every objective has a different size ring, so for every objective another condenser setting has to be chosen. The ring in the objective has special optical properties: it, first of all, reduces the direct light in intensity, but more importantly, it creates an artificial phase difference of about a quarter wavelength. As the physical properties of this direct light have changed, interference with the diffracted light occurs, resulting in the phase contrast image. One disadvantage of phase-contrast microscopy is halo formation (halo-light ring).
Superior and much more expensive is the use of interference contrast . Differences in optical density will show up as differences in relief. A nucleus within a cell will actually show up as a globule in the most often used differential interference contrast system according to Georges Nomarski . However, it has to be kept in mind that this is an optical effect , and the relief does not necessarily resemble the true shape. Contrast is very good and the condenser aperture can be used fully open, thereby reducing the depth of field and maximizing resolution.
The system consists of a special prism ( Nomarski prism , Wollaston prism ) in the condenser that splits light in an ordinary and an extraordinary beam. The spatial difference between the two beams is minimal (less than the maximum resolution of the objective). After passage through the specimen, the beams are reunited by a similar prism in the objective.
In a homogeneous specimen, there is no difference between the two beams, and no contrast is being generated. However, near a refractive boundary (say a nucleus within the cytoplasm), the difference between the ordinary and the extraordinary beam will generate a relief in the image. Differential interference contrast requires a polarized light source to function; two polarizing filters have to be fitted in the light path, one below the condenser (the polarizer), and the other above the objective (the analyzer).
Note: In cases where the optical design of a microscope produces an appreciable lateral separation of the two beams we have the case of classical interference microscopy , which does not result in relief images, but can nevertheless be used for the quantitative determination of mass-thicknesses of microscopic objects.
An additional technique using interference is interference reflection microscopy (also known as reflected interference contrast, or RIC). It relies on cell adhesion to the slide to produce an interference signal. If there is no cell attached to the glass, there will be no interference.
Interference reflection microscopy can be obtained by using the same elements used by DIC, but without the prisms. Also, the light that is being detected is reflected and not transmitted as it is when DIC is employed.
When certain compounds are illuminated with high energy light, they emit light of a lower frequency. This effect is known as fluorescence . Often specimens show their characteristic autofluorescence image, based on their chemical makeup.
This method is of critical importance in the modern life sciences, as it can be extremely sensitive, allowing the detection of single molecules. Many fluorescent dyes can be used to stain structures or chemical compounds. One powerful method is the combination of antibodies coupled to a fluorophore as in immunostaining . Examples of commonly used fluorophores are fluorescein or rhodamine .
The antibodies can be tailor-made for a chemical compound. For example, one strategy often in use is the artificial production of proteins, based on the genetic code (DNA). These proteins can then be used to immunize rabbits, forming antibodies which bind to the protein. The antibodies are then coupled chemically to a fluorophore and used to trace the proteins in the cells under study.
Highly efficient fluorescent proteins such as the green fluorescent protein (GFP) have been developed using the molecular biology technique of gene fusion , a process that links the expression of the fluorescent compound to that of the target protein. This combined fluorescent protein is, in general, non-toxic to the organism and rarely interferes with the function of the protein under study. Genetically modified cells or organisms directly express the fluorescently tagged proteins, which enables the study of the function of the original protein in vivo .
Growth of protein crystals results in both protein and salt crystals. Both are colorless and microscopic. Recovery of the protein crystals requires imaging which can be done by the intrinsic fluorescence of the protein or by using transmission microscopy. Both methods require an ultraviolet microscope as proteins absorbs light at 280 nm. Protein will also fluorescence at approximately 353 nm when excited with 280 nm light. [ 18 ]
Since fluorescence emission differs in wavelength (color) from the excitation light, an ideal fluorescent image shows only the structure of interest that was labeled with the fluorescent dye. This high specificity led to the widespread use of fluorescence light microscopy in biomedical research. Different fluorescent dyes can be used to stain different biological structures, which can then be detected simultaneously, while still being specific due to the individual color of the dye.
To block the excitation light from reaching the observer or the detector, filter sets of high quality are needed. These typically consist of an excitation filter selecting the range of excitation wavelengths , a dichroic mirror, and an emission filter blocking the excitation light. Most fluorescence microscopes are operated in the Epi-illumination mode (illumination and detection from one side of the sample) to further decrease the amount of excitation light entering the detector.
See also: total internal reflection fluorescence microscope Neuroscience
Confocal laser scanning microscopy uses a focused laser beam (e.g. 488 nm) that is scanned across the sample to excite fluorescence in a point-by-point fashion. The emitted light is directed through a pinhole to prevent out-of-focus light from reaching the detector, typically a photomultiplier tube . The image is constructed in a computer, plotting the measured fluorescence intensities according to the position of the excitation laser. Compared to full sample illumination, confocal microscopy gives slightly higher lateral resolution and significantly improves optical sectioning (axial resolution). Confocal microscopy is, therefore, commonly used where 3D structure is important.
A subclass of confocal microscopes are spinning disc microscopes which are able to scan multiple points simultaneously across the sample. A corresponding disc with pinholes rejects out-of-focus light. The light detector in a spinning disc microscope is a digital camera, typically EM-CCD or sCMOS .
A two-photon microscope is also a laser-scanning microscope, but instead of UV, blue or green laser light, a pulsed infrared laser is used for excitation. Only in the tiny focus of the laser is the intensity high enough to generate fluorescence by two-photon excitation , which means that no out-of-focus fluorescence is generated, and no pinhole is necessary to clean up the image. [ 19 ] This allows imaging deep in scattering tissue, where a confocal microscope would not be able to collect photons efficiently. [ 20 ] Two-photon microscopes with wide-field detection are frequently used for functional imaging, e.g. calcium imaging , in brain tissue. [ 21 ] They are marketed as Multiphoton microscopes by several companies, although the gains of using 3-photon instead of 2-photon excitation are marginal.
Using a plane of light formed by focusing light through a cylindrical lens at a narrow angle or by scanning a line of light in a plane perpendicular to the axis of objective, high resolution optical sections can be taken. [ 22 ] [ 23 ] [ 24 ] Single plane illumination, or light sheet illumination, is also accomplished using beam shaping techniques incorporating multiple-prism beam expanders . [ 25 ] [ 26 ] The images are captured by CCDs. These variants allow very fast and high signal to noise ratio image capture.
Wide-field multiphoton microscopy [ 27 ] [ 28 ] [ 29 ] [ 30 ] refers to an optical non-linear imaging technique in which a large area of the object is illuminated and imaged without the need for scanning. High intensities are required to induce non-linear optical processes such as two-photon fluorescence or second harmonic generation . In scanning multiphoton microscopes the high intensities are achieved by tightly focusing the light, and the image is obtained by beam scanning. In wide-field multiphoton microscopy the high intensities are best achieved using an optically amplified pulsed laser source to attain a large field of view (~100 μm). [ 27 ] [ 28 ] [ 29 ] The image in this case is obtained as a single frame with a CCD camera without the need of scanning, making the technique particularly useful to visualize dynamic processes simultaneously across the object of interest. With wide-field multiphoton microscopy the frame rate can be increased up to a 1000-fold compared to multiphoton scanning microscopy . [ 28 ] In scattering tissue, however, image quality rapidly degrades with increasing depth.
Fluorescence microscopy is a powerful technique to show specifically labeled structures within a complex environment and to provide three-dimensional information of biological structures. However, this information is blurred by the fact that, upon illumination, all fluorescently labeled structures emit light, irrespective of whether they are in focus or not. So an image of a certain structure is always blurred by the contribution of light from structures that are out of focus. This phenomenon results in a loss of contrast especially when using objectives with a high resolving power, typically oil immersion objectives with a high numerical aperture.
However, blurring is not caused by random processes, such as light scattering, but can be well defined by the optical properties of the image formation in the microscope imaging system. If one considers a small fluorescent light source (essentially a bright spot), light coming from this spot spreads out further from our perspective as the spot becomes more out of focus. Under ideal conditions, this produces an "hourglass" shape of this point source in the third (axial) dimension. This shape is called the point spread function (PSF) of the microscope imaging system. Since any fluorescence image is made up of a large number of such small fluorescent light sources, the image is said to be "convolved by the point spread function". The mathematically modeled PSF of a terahertz laser pulsed imaging system is shown on the right.
The output of an imaging system can be described using the equation:
s ( x , y ) = P S F ( x , y ) ∗ o ( x , y ) + n {\displaystyle s(x,y)=PSF(x,y)*o(x,y)+n}
Where n is the additive noise. [ 32 ] Knowing this point spread function [ 33 ] means that it is possible to reverse this process to a certain extent by computer-based methods commonly known as deconvolution microscopy. [ 34 ] There are various algorithms available for 2D or 3D deconvolution. They can be roughly classified in nonrestorative and restorative methods. While the nonrestorative methods can improve contrast by removing out-of-focus light from focal planes, only the restorative methods can actually reassign light to its proper place of origin. Processing fluorescent images in this manner can be an advantage over directly acquiring images without out-of-focus light, such as images from confocal microscopy , because light signals otherwise eliminated become useful information. For 3D deconvolution, one typically provides a series of images taken from different focal planes (called a Z-stack) plus the knowledge of the PSF, which can be derived either experimentally or theoretically from knowing all contributing parameters of the microscope.
A multitude of super-resolution microscopy techniques have been developed in recent times which circumvent the diffraction limit .
This is mostly achieved by imaging a sufficiently static sample multiple times and either modifying the excitation light or observing stochastic changes in the image. The deconvolution methods described in the previous section, which removes the PSF induced blur and assigns a mathematically 'correct' origin of light, are used, albeit with slightly different understanding of what the value of a pixel mean. Assuming most of the time , one single fluorophore contributes to one single blob on one single taken image, the blobs in the images can be replaced with their calculated position, vastly improving resolution to well below the diffraction limit.
To realize such assumption, Knowledge of and chemical control over fluorophore photophysics is at the core of these techniques, by which resolutions of ~20 nanometers are obtained. [ 35 ] [ 36 ]
Serial time encoded amplified microscopy (STEAM) is an imaging method that provides ultrafast shutter speed and frame rate, by using optical image amplification to circumvent the fundamental trade-off between sensitivity and speed, and a single-pixel photodetector to eliminate the need for a detector array and readout time limitations [ 37 ] The method is at least 1000 times faster than the state-of-the-art CCD and CMOS cameras. Consequently, it is potentially useful for scientific, industrial, and biomedical applications that require high image acquisition rates, including real-time diagnosis and evaluation of shockwaves, microfluidics , MEMS , and laser surgery . [ 38 ]
Most modern instruments provide simple solutions for micro-photography and image recording electronically. However such capabilities are not always present and the more experienced microscopist may prefer a hand drawn image to a photograph. This is because a microscopist with knowledge of the subject can accurately convert a three-dimensional image into a precise two-dimensional drawing. In a photograph or other image capture system however, only one thin plane is ever in good focus. [ citation needed ]
The creation of accurate micrographs requires a microscopical technique using a monocular eyepiece. It is essential that both eyes are open and that the eye that is not observing down the microscope is instead concentrated on a sheet of paper on the bench besides the microscope. With practice, and without moving the head or eyes, it is possible to accurately trace the observed shapes by simultaneously "seeing" the pencil point in the microscopical image. [ citation needed ]
It is always less tiring to observe with the microscope focused so that the image is seen at infinity and with both eyes open at all times. [ citation needed ]
Microspectroscopy:spectroscopy with a microscope
As resolution depends on the wavelength of the light. Electron microscopy has been developed since the 1930s that use electron beams instead of light. Because of the much smaller wavelength of the electron beam, resolution is far higher.
Though less common, X-ray microscopy has also been developed since the late 1940s. The resolution of X-ray microscopy lies between that of light microscopy and electron microscopy.
Until the invention of sub-diffraction microscopy, the wavelength of the light limited the resolution of traditional microscopy to around 0.2 micrometers. In order to gain higher resolution, the use of an electron beam with a far smaller wavelength is used in electron microscopes.
Electron microscopes equipped for X-ray spectroscopy can provide qualitative and quantitative elemental analysis. This type of electron microscope, also known as analytical electron microscope, can be a very powerful tool for investigation of nanomaterials . [ 39 ]
This is a sub-diffraction technique. Examples of scanning probe microscopes are the atomic force microscope (AFM), the scanning tunneling microscope , the photonic force microscope and the recurrence tracking microscope . All such methods use the physical contact of a solid probe tip to scan the surface of an object, which is supposed to be almost flat.
Ultrasonic force microscopy (UFM) has been developed in order to improve the details and image contrast on "flat" areas of interest where AFM images are limited in contrast. The combination of AFM-UFM allows a near field acoustic microscopic image to be generated. The AFM tip is used to detect the ultrasonic waves and overcomes the limitation of wavelength that occurs in acoustic microscopy. By using the elastic changes under the AFM tip, an image of much greater detail than the AFM topography can be generated.
Ultrasonic force microscopy allows the local mapping of elasticity in atomic force microscopy by the application of ultrasonic vibration to the cantilever or sample. To analyze the results of ultrasonic force microscopy in a quantitative fashion, a force-distance curve measurement is done with ultrasonic vibration applied to the cantilever base, and the results are compared with a model of the cantilever dynamics and tip-sample interaction based on the finite-difference technique.
Ultraviolet microscopes have two main purposes. The first is to use the shorter wavelength of ultraviolet electromagnetic energy to improve the image resolution beyond that of the diffraction limit of standard optical microscopes. This technique is used for non-destructive inspection of devices with very small features such as those found in modern semiconductors. The second application for UV microscopes is contrast enhancement where the response of individual samples is enhanced, relative to their surrounding, due to the interaction of light with the molecules within the sample itself. One example is in the growth of protein crystals . Protein crystals are formed in salt solutions. As salt and protein crystals are both formed in the growth process, and both are commonly transparent to the human eye, they cannot be differentiated with a standard optical microscope. As the tryptophan of protein absorbs light at 280 nm, imaging with a UV microscope with 280 nm bandpass filters makes it simple to differentiate between the two types of crystals. The protein crystals appear dark while the salt crystals are transparent.
The term infrared microscopy refers to microscopy performed at infrared wavelengths. In the typical instrument configuration, a Fourier Transform Infrared Spectrometer (FTIR) is combined with an optical microscope and an infrared detector . The infrared detector can be a single point detector, a linear array or a 2D focal plane array. FTIR provides the ability to perform chemical analysis via infrared spectroscopy and the microscope and point or array detector enable this chemical analysis to be spatially resolved, i.e. performed at different regions of the sample. As such, the technique is also called infrared microspectroscopy [ 40 ] [ 41 ] An alternative architecture called Laser Direct Infrared (LDIR) Imaging involves the combination of a tuneable infrared light source and single point detector on a flying objective. This technique is frequently used for infrared chemical imaging , where the image contrast is determined by the response of individual sample regions to particular IR wavelengths selected by the user, usually specific IR absorption bands and associated molecular resonances . A key limitation of conventional infrared microspectroscopy is that the spatial resolution is diffraction-limited . Specifically the spatial resolution is limited to a figure related to the wavelength of the light. For practical IR microscopes, the spatial resolution is limited to 1-3x the wavelength, depending on the specific technique and instrument used. For mid-IR wavelengths, this sets a practical spatial resolution limit of ~3-30 μm.
IR versions of sub-diffraction microscopy also exist. [ 40 ] [ 41 ] These include IR Near-field scanning optical microscope (NSOM) , [ 42 ] photothermal microspectroscopy and atomic force microscope based infrared spectroscopy (AFM-IR) , as well as scattering-type Scanning Near-field Optical Microscopy (s-SNOM) [ 43 ] & nano-FTIR that provide nanoscale spatial resolution at IR wavelengths.
In digital holographic microscopy (DHM), interfering wave fronts from a coherent (monochromatic) light-source are recorded on a sensor. The image is digitally reconstructed by a computer from the recorded hologram . Besides the ordinary bright field image, a phase shift image is created.
DHM can operate both in reflection and transmission mode. In reflection mode, the phase shift image provides a relative distance measurement and thus represents a topography map of the reflecting surface. In transmission mode, the phase shift image provides a label-free quantitative measurement of the optical thickness of the specimen. Phase shift images of biological cells are very similar to images of stained cells and have successfully been analyzed by high content analysis software.
A unique feature of DHM is the ability to adjust focus after the image is recorded, since all focus planes are recorded simultaneously by the hologram. This feature makes it possible to image moving particles in a volume or to rapidly scan a surface. Another attractive feature is The ability of DHM to use low cost optics by correcting optical aberrations by software.
Digital pathology is an image-based information environment enabled by computer technology that allows for the management of information generated from a digital slide. Digital pathology is enabled in part by virtual microscopy , which is the practice of converting glass slides into digital slides that can be viewed, managed, and analyzed.
Laser microscopy is a rapidly growing field that uses laser illumination sources in various forms of microscopy. [ 44 ] For instance, laser microscopy focused on biological applications uses ultrashort pulse lasers, in a number of techniques labeled as nonlinear microscopy, saturation microscopy, and two-photon excitation microscopy . [ 45 ]
High-intensity, short-pulse laboratory x-ray lasers have been under development for several years. When this technology comes to fruition, it will be possible to obtain magnified three-dimensional images of elementary biological structures in the living state at a precisely defined instant. For optimum contrast between water and protein and for best sensitivity and resolution, the laser should be tuned near the nitrogen line at about 0.3 nanometers. Resolution will be limited mainly by the hydrodynamic expansion that occurs while the necessary number of photons is being registered. [ 46 ] Thus, while the specimen is destroyed by the exposure, its configuration can be captured before it explodes. [ 47 ] [ 48 ] [ 49 ] [ 50 ] [ 51 ] [ 52 ] [ excessive citations ]
Scientists have been working on practical designs and prototypes for x-ray holographic microscopes, despite the prolonged development of the appropriate laser. [ 53 ] [ 54 ] [ 55 ] [ 56 ] [ 57 ] [ 58 ] [ 59 ] [ 60 ] [ excessive citations ]
A microscopy technique relying on the photoacoustic effect , [ 61 ] i.e. the generation of (ultra)sound caused by light absorption.
A focused and intensity modulated laser beam is raster scanned over a sample. The generated (ultra)sound is detected via an ultrasound transducer. Commonly piezoelectric ultrasound transducers are employed. [ 62 ]
The image contrast is related to the sample's absorption coefficient α {\displaystyle \alpha } . This is in contrast to bright or dark field microscopy, where the image contrast is due to transmittance or scattering. In principle, the contrast of fluorescence microscopy is proportional to the sample's absorption too. However, in fluorescence microscopy the fluorescence quantum yield η f l {\displaystyle \eta _{fl}} needs to be unequal to zero in order that a signal can be detected. In photoacoustic microscopy, however, every absorbing substance gives a photoacoustic signal P A {\displaystyle PA} which is proportional to
P A ∝ α ∗ Γ ∗ ( ( 1 − η f l ) ∗ E g + ( E l a s e r − E g ) ) {\displaystyle PA\propto \alpha *\Gamma *((1-\eta _{fl})*E_{g}+(E_{laser}-E_{g}))}
Here Γ {\displaystyle \Gamma } is the Grüneisen coefficient, E l a s e r {\displaystyle E_{laser}} is the laser's photon energy and E g {\displaystyle E_{g}} is the sample's band gap energy. Therefore, photoacoustic microscopy seems well suited as a complementary technique to fluorescence microscopy, as a high fluorescence quantum yield leads to high fluorescence signals and a low fluorescence quantum yield leads to high photoacoustic signals.
Neglecting non-linear effects, the lateral resolution dx is limited by the Abbe diffraction limit :
d x = λ / ( 2 ∗ N A ) {\displaystyle dx=\lambda /(2*NA)}
where λ {\displaystyle \lambda } is the wavelength of the excitation laser and NA is the numerical aperture of the objective lens. The Abbe diffraction limit holds if the incoming wave front is parallel. In reality, however, the laser beam profile is Gaussian. Therefore, in order to the calculate the achievable resolution, formulas for truncated Gaussian beams have to be used. [ 63 ]
Amateur Microscopy is the investigation and observation of biological and non-biological specimens for recreational purposes. Collectors of minerals , insects , seashells , and plants may use microscopes as tools to uncover features that help them classify their collected items. Other amateurs may be interested in observing the life found in pond water and of other samples. Microscopes may also prove useful for the water quality assessment for people that keep a home aquarium . Photographic documentation and drawing of the microscopic images are additional pleasures. There are competitions for photomicrograph art. Participants of this pastime may use commercially prepared microscopic slides or prepare their own slides.
While microscopy is a central tool in the documentation of biological specimens, it is often insufficient to justify the description of a new species based on microscopic investigations alone. Often genetic and biochemical tests are necessary to confirm the discovery of a new species. A laboratory and access to academic literature is a necessity. There is, however, one advantage that amateurs have above professionals: time to explore their surroundings. Often, advanced amateurs team up with professionals to validate their findings and possibly describe new species.
In the late 1800s, amateur microscopy became a popular hobby in the United States and Europe. Several 'professional amateurs' were being paid for their sampling trips and microscopic explorations by philanthropists, to keep them amused on the Sunday afternoon (e.g., the diatom specialist A. Grunow, being paid by (among others) a Belgian industrialist). Professor John Phin published "Practical Hints on the Selection and Use of the Microscope (Second Edition, 1878)," and was also the editor of the "American Journal of Microscopy."
Examples of amateur microscopy images:
Microscopy has applications in the forensic sciences. [ 64 ] The microscope can detect, resolve and image the smallest items of evidence, often without any alteration or destruction. The microscope is used to identify and compare fibers, hairs, soils, and dust...etc.
In ink markings, blood stains or bullets, no specimen treatment is required and the evidence shows directly from microscopical examination. For traces of particular matter, the sample preparation must be done before microscopical examination occurs. [ clarification needed ]
Light microscopes are the most use in forensics, using photons to form images, microscopes which are most applicable for examining forensic specimens are as follows: [ 65 ]
1. The compound microscope
2. The comparison microscope
3. The stereoscopic microscope
4. The polarizing microscope
5. The micro spectrophotometer
This diversity of the types of microscopes in forensic applications comes mainly from their magnification ranges, which are (1- 1200X), (50 -30,000X) and (500- 250,000X) for the optical microscopy, SEM and TEM respectively. [ 65 ] | https://en.wikipedia.org/wiki/Microscopy |
The Microscopy Society of America ( MSA ), founded in 1942 as The Electron Microscope Society of America, is a non-profit organization that provides microanalytical facilities for studies within the sciences. [ 1 ] [ 2 ] Currently, there are approximately 3000 members. The society holds an annual meeting, which is usually held in the beginning of August. It has 30 local affiliates across the United States . The society has a program for examining and certifying technologists of electron microscopes . [ 3 ] [ 2 ] The organization produces two journals: Microscopy Today, and Microscopy and Microanalysis . As of 2024, the President is Jay Potts.
A meeting of electron microscopists took place in November 1942 at the Sherman House Hotel in Chicago . It was organized by G. L. Clark of the University of Chicago . At this meeting the society was founded as the Electron Microscope Society of America (EMSA). For the 1949 meeting, the EMSA invited representatives from European microscopy societies, which may have been a catalyzing event for the creation of an international microscopy society: the International Federation of Societies for Electron Microscopy (IFSEM), which the EMSA later joined, and would eventually hold joint meetings with IFSEM; the first of these joint meetings would the 9th International Congress of Electron Microscopy in 1978. [ 4 ]
The name of the society was changed in 1964 to the Electron Microscopy Society of America to "reflect the cross-discipline nature of microscopy applications." In 1993, the name was changed to the current one: the Microscopy Society of America to "reflect the increasing diversity of microscopy and microanalysis techniques and their applications represented at the annual Microscopy and Microanalysis (M&M) meeting and in MSA publications." [ 5 ]
The MSA has an MSA Executive Council made up of five individuals: the president, president-elect, past president, treasurer and secretary. Those elected president serve three-year terms, where they have different roles during each year. During the first year they act as the president-elect, during the second year they act as the president, and during the final year they act as the past president. The treasurer serves a five-year term, and the secretary serves a two-year term.
Additionally, there is an MSA Council made up of seven individuals each elected to two-year terms.
Microscopy Today and Microscopy and Microanalysis both release six times a year alternating with each other. The former is released in odd months (January, March etc.), while the latter is released in even months (February, April etc.). Both are now published by Oxford University Press , but were published by the Cambridge University Press prior to 2023. [ 6 ]
Microscopy Today is a trade magazine intended to provide information to microscopists working in all fields, with coverage including light microscopy, microanalytical methods and electron microscopy. [ 6 ] The current editor-in-chief is Dr. Robert L. Price. [ 7 ]
It was published by Cambridge University Press until Volume 31, where publishing was taken over by Oxford University Press . [ 8 ]
Microscopy and Microanalysis is a peer-reviewed scientific journal that covers original research in the fields of microscopy , imaging, and compositional analysis, [ 9 ] including electron microscopy , fluorescence microscopy , atomic force microscopy , and live-cell imaging.
The Microscopy Listserver [ 12 ] is a network based discussion forum giving members of the scientific community a centralized Internet address to which questions/comments/answers in the various fields of Microscopy or Microanalysis can be rapidly distributed to a list of (subscribed) individuals by electronic mail. There are in excess of 3000 subscribers to the Microscopy Listserver from over 40 countries on 6 continents, who participate in this system on a daily basis. Messages are posted and circulated daily on a variety of topics. The Listserver was founded by Nestor J. Zaluzec who continues to host and operate the service for the scientific community, the Listserver is co-sponsored in part by the Microscopy Society of America .
This Listserver has been in operation since 1993 and maintains a searchable archive of all posted Email questions, comments, and responses. Every two months, selected contributions on the Microscopy Listserver are published in the archives of Microscopy-Today [ 13 ]
For the purposes of this forum, Microscopy or Microanalysis is considered to include all techniques which employ a probe such as: photons (including x-rays), electrons, ions, mechanical and/or electromagnetic radiation to form a representation or characterization of the microstructure (internal or external) of any material in either physical and/or life sciences applications.
Some of the more common techniques which are associated with this field include the following:
There are no charges for usage of the forum, except for the request that one actively participates in any discussion to which you have a question, comment and/or contribution.
Unsolicited commercial advertising messages are prohibited, however, brief announcements of educational/training courses are permitted on a strictly limited basis.
In compliance with US Public Law 108-187 (CANSPAM Act) only subscribers and/or posters receive copies of posting to the Listserver via Email. Non-subscribers are allowed to browse the archives. | https://en.wikipedia.org/wiki/Microscopy_Listserver |
Microscopy with UV Surface Excitation ( MUSE ) is a novel microscopy method that utilizes the shallow penetration of UV photons (230–300 nm ) excitation. [ 1 ] [ 2 ] [ 3 ] [ 4 ] Compared to conventional microscopes, which usually require sectioning to exclude blurred signals from outside of the focal plane, MUSE's low penetration depth limits the excitation volume to a thin layer, and removes the tissue sectioning requirement. The entire signal collected is the desired light, and all photons collected contribute to the image formation.
The microscope setup is based on an inverted microscope design. [ 2 ] [ 3 ] [ 4 ] An automated stage is used to record larger areas by mosaicing a series of single adjacent frames. The LED light is focused using a ball lens with a short focal length onto the sample surface in an oblique-angle cis-illumination scheme since standard microscopy optics do not transmit UV light efficiently. No dichroic mirror or filter is required as microscope objectives are opaque to UV excitation light. The emitted fluorescence light is collected using a long-working-distance objective and focused via a tube lens onto a CCD camera .
Specimens are submerged in exogenous dye for 10 seconds and then briefly washed in water or phosphate-buffered saline (PBS). [ 2 ] The resulting stained specimens generate bright enough signals for direct and interpretable visualization through microscope eyepiece.
Previous work from MUSE includes the detection of endogenous fluorescent molecules in intact clinical and human tissues for functional and structural characterization, which is limited by the relatively dim autofluorescence found in tissue. However, the use of bright exogenous dyes can provide substantially more remitted light than the autofluorescence approach.
Several dyes have been studied for MUSE's application, including eosin , rhodamine , DAPI , Hoechst , acridine orange , propidium iodide , and proflavine . [ 2 ] Eosin and rhodamine stain the cytoplasm and the extracellular matrix, making the bulk of the tissue visible. Hoechst and DAPI fluoresce brightly when bound to DNA , allowing them to serve as excellent nuclear stains.
Microscope-based diagnostics are widely performed and served as a gold standard in histological analysis. However this procedure generally requires a series time-consuming lab-based procedures including fixation, paraffin embedment, sectioning, and staining to produce microscope slides with optically thin tissue slides (4–6 μm). While in developed regions histology is commonly used, people who live in areas with limited resources can hardly access it and consequently are in need for a low-cost, more efficient way to access pathological diagnosis. [ 5 ] [ 6 ] The main significance of MUSE system comes from its capacity to produce high-resolution microscopic image with subcellular features in a time-efficient manner with less costs and less lab-expertises requirements.
With 280 nm deep UV excitation and simple but robust hardware design, MUSE system can collect fluorescence signals without the need for fluorescence filtering techniques or complex mathematical image reconstruction. [ 1 ] It has potential for generate high quality images containing more information than microscope slides in terms of its 2.5 dimensional features. MUSE images have been validated with diagnostic values. [ 2 ] [ 3 ] The system is capable to produce images from various tissue type in different sizes, either fresh or fixed.
MUSE system mainly serves as a low-cost alternative to traditional histological analysis for cancer diagnostics with simpler and less time-consuming techniques. [ 1 ] [ 2 ] [ 3 ] [ 4 ] By integrating microscopy and fresh tissue fluorescence staining into an automated optical system, the overall acquiring time needed for getting digital images with diagnostic values can be much shortened into the scale of minutes comparing with conventional pathology, where general procedure can take from hours to days. The color-mapping techniques that correlated fluorescence staining to traditional H&E staining provide the same visual representation to pathologists based on existing knowledge with no need for additional training on image recognition.
Additionally, this system also has great potential to be used for intraoperative consultation, a method performed in pathologists lab that examine the microscopic features of tissue during oncological surgery usually for rapid cancer lesion and margin detection. [ 1 ] [ 3 ] It also can play an important role in biological and medical research, which might require examination on cellular features of tissue samples. In the future, the system can be further optimized to include more features including staining protocol, LEDs wavelength for more research usages and applications. [ 1 ] | https://en.wikipedia.org/wiki/Microscopy_with_UV_surface_excitation |
Microsegregation is a non-uniform chemical separation and concentration of elements or impurities in alloys after they have solidified. [ 1 ]
This physical chemistry -related article is a stub . You can help Wikipedia by expanding it .
This alloy-related article is a stub . You can help Wikipedia by expanding it . | https://en.wikipedia.org/wiki/Microsegregation |
A microsite is a term used in ecology to describe a pocket within an environment with unique features, conditions or characteristics. Classifying different microsites may depend on temperature, humidity, sunlight, nutrient availability, soil physical characteristics, vegetation cover, etc. Being a
sub environment within an environment , we will examine the qualities that differentiate a microsite from another within an environment in this piece.
Microsites being a subset of the environment can be identified with its own:
It refers to the temperature of the surrounding environment measured in degree Fahrenheit. [1] The temperature of one microsite may not necessarily be the same with another one even if they are closely related in terms of location. [2]
It refers to the relative amount of moisture that could be held in the air. The more saturated the air is with water vapor in a microsite the more relative it is in humidity. [ 1 ]
Plants uses energy from the sunlight to carry on photosynthesis. The possibility of sunlight to reach a microsite is another distinguishing characteristic which creates differences between microsites. There are some areas that the sunlight doesn’t reach which creates a different environmental condition than those that the sun reaches thus making some plants to have more fitness than others. [ 2 ]
Some microsites are rich in nutrients while some are not. This is a great difference because seeds germinate more in microsites that have more nutrients it needs than those that lack them. This is because plants and other autotrophs get nutrients (nitrogen, phosphorus , potassium , calcium , magnesium and Sulphur ) they need from soil and water available in their microsite. [ 3 ]
Plants obtain hydrogen from water found in the soil. Animals are influence by the soil physical characteristics for example where a fish will survive is not the same like that of a camel or goat . [ 4 ] All this features help differentiate one microsite from another and explains the existence of organisms in one and not in the other.
This refers to collections of plants species over a land surface. A microsite in the Savana is different from that in the Sahara because of their vegetation cover. This explains the differences existing between the type of organisms that live in both areas.
With the many microsites that exist in an environment, organisms usually base their selection of habit on the features of the microsite they come across. Being able to choose the best microsite will positively influence the organism's survival, growth and reproduction . There choice of a good microsite has a direct relation to the future generation of the organisms. [ 5 ]
Not all microsites have the necessary ingredients needed by plants and animals to survive and grow. While some may have, some condition may arise to render those ingredients not available again in the environment such as pollution or invasive species . In the case of seedling; air , light , soil, humus are all needed by seedling to grow and survive. The lack of these elements will cause a growth limitation factor in the said microsite and also survival issues. Same applies to animals but however in animals they can immigrate to other areas that favors their growth and survival while those who can not will be limited in fitness . | https://en.wikipedia.org/wiki/Microsite_(ecology) |
The Royal Society and Académie des sciences Microsoft Award was an annual award given by the Royal Society and the Académie des sciences to scientists working in Europe who had made a major contribution to the advancement of science through the use of computational methods. It was sponsored by Microsoft Research .
The award was open to any research scientist who had made a significant contribution at the intersection of computing and the sciences covering Biological Sciences , Physical Sciences , Mathematics and Engineering. The prize recognized the importance of interdisciplinary research at the interface of science and computing for advancing scientific boundaries, as well as the importance of investing in European scientists to give Europe a competitive science base. The recipient was selected by a Committee comprising members of the Académie des sciences and Fellows of the Royal Society. The prize consisted of a trophy and monetary amount of €250,000, of which €7,500 is prize money and the rest earmarked for further research.
The first award was made in 2006 and the last in 2009. It has now been replaced by the Royal Society Milner Award .
Today, Microsoft is giving awards for top-performing partners in various countries. [ 5 ] [ 6 ] | https://en.wikipedia.org/wiki/Microsoft_Award |
Microsoft Azure Quantum is a public cloud-based quantum computing platform developed by Microsoft , that offers quantum hardware, software, and solutions for developers to build quantum applications. [ 1 ] [ 2 ] It supports variety of quantum hardware architectures from partners including Quantinuum , IonQ , and Atom Computing. [ 3 ] To run applications on the cloud platform, Microsoft developed the Q# quantum programming language. [ 4 ]
Azure Quantum also includes a platform for scientific research, Azure Quantum Elements . It uses artificial intelligence , high-performance computing and quantum processors to run molecular simulations and calculations in computational chemistry and materials science. [ 5 ]
Azure Quantum was first announced at Microsoft Ignite in 2019. [ 6 ] The platform was opened for public preview in 2021, [ 1 ] and Azure Quantum Elements was launched in 2023. [ 5 ]
In addition to its hardware partners on the platform, Microsoft is developing a topological quantum computer with qubits that are inherently resistant to error. The approach is based on Majorana quasiparticles , which act as their own antiparticle and have a charge and energy equal to zero, making qubits that are more resilient to disturbances. [ 7 ] [ 8 ]
In September 2023, Azure Quantum researchers found evidence consistent with the creation and control of Majorana quasiparticles for topological quantum computing. [ 8 ] [ 9 ]
In November 2024, the qubit virtualization system created 24 entangled logical qubits – a new record – on a neutral atom processor. [ 10 ] The work demonstrated detection and correction of errors while performing computations, including the first demonstration on record of loss correction in a commercial neutral-atom system from Atom Computing. [ 11 ]
Microsoft has also introduced three levels of implementation for quantum computing: foundational ( noisy intermediate-scale qubits), resilient (reliable logical qubits), and scale (quantum supercomputers). [ 7 ] [ 12 ]
In 2024, Microsoft applied a qubit virtualization system to Quantinuum's trapped ion quantum computer to create 12 logical qubits, the most reliable logical qubits on record at the time. [ 13 ] The work built upon a previous demonstration that reached error rates 800 times better than the achievement of the same quantum computer without virtualization. [ 13 ] [ 14 ]
Microsoft and Photonic also performed a teleported CNOT gate between qubits physically separated by 40 meters. The work confirmed remote quantum entanglement between T-centers - a requirement for long-distance quantum communication. [ 15 ]
In 2025, Microsoft reported the creation of Majorana 1 , [ 16 ] which is the world's first quantum chip powered by a topological core architecture. The work created a new class of materials called topoconductors, which use topological superconductivity to control hardware-protected topological qubits. [ 16 ] [ 17 ] The research utilized a method to determine fermion parity in Majorana zero modes in a single shot – validating a necessary ingredient for utility-scale topological quantum computation architectures based on measurement. [ 18 ]
For quantum applications, Azure Quantum developed Q# (pronunciation: Q Sharp), a quantum programming language, and an open-source software development kit for quantum algorithm development and simulation. [ 1 ]
The Azure Quantum Resource Estimator estimates resources required to execute a given quantum algorithm on a fault-tolerant quantum computer. [ 19 ]
In 2023, Azure Quantum Elements added Microsoft Copilot , a GPT-4 based large language model tool to query and visualize data, write code, and initiate simulations. [ 7 ]
The same year, Microsoft developed Quantum Intermediate Representation (QIR) from LLVM as a common interface between programming languages and target quantum processors. [ 20 ]
Microsoft also developed gate-efficient algorithmic methods to perform faster Trotter steps with lower gate complexity, enabling efficient quantum simulations that reduce the required quantum hardware resources. [ 21 ]
The Azure Quantum Elements platform combines artificial intelligence (AI) and traditional high-performance computing with quantum tools for materials science, chemistry and pharmaceutical research. [ 22 ] The platform uses physics-based AI models and advanced algorithms to process complex research data and draw conclusions. [ 23 ]
In January 2024, Microsoft and Pacific Northwest National Laboratory used AI and HPC to model and screen 32 million new candidate materials to develop a more efficient rechargeable battery material. The joint project generated new material candidates, then conducted a hyper-accelerated search among them to reach a single suitable candidate that could potentially replace the lithium-ion. [ 24 ]
In July 2024, Microsoft released a Generative Chemistry tool for Azure Quantum Elements that uses generative AI to identify the right molecules to use for a particular application. Microsoft also released an Accelerated Density Functional Theory tool to simulate simulations of a molecule's electronic structure using density functional theory (DFT). [ 25 ]
Microsoft also used two logical qubits integrated with AI and cloud high-performance computing to solve a practical chemistry problem. [ 26 ] According to Microsoft, this case study on catalytic reactions producing chiral molecules represents the first time an HPC system, AI, and quantum computing hardware have been deployed together to solve a specific scientific problem. [ 26 ]
In pharmaceuticals, Azure Quantum Elements and HPC platform was integrated with 1910 Gentetics' computational and wet lab biological information, laboratory automation powered by robotics and multimodal AI models for drug discovery. [ 27 ] | https://en.wikipedia.org/wiki/Microsoft_Azure_Quantum |
Microsoft Band is a discontinued smart band with smartwatch and activity tracker / fitness tracker features, created and developed by Microsoft . It was announced on October 29, 2014. The Microsoft Band incorporates fitness tracking and health-oriented capabilities and integrated with Windows Phone , iOS , and Android smartphones through a Bluetooth connection. On October 3, 2016, Microsoft stopped sales and development of the line of devices. [ 1 ] On May 31, 2019, the Band's companion app was decommissioned, and Microsoft offered a refund for customers who were lifelong active platform users. [ 2 ]
The Microsoft Band was announced by Microsoft on October 29, 2014 [ 3 ] and released in limited quantities in the US the following day. The Band was initially sold exclusively on the Microsoft Store 's website and retail locations; due to its unexpected popularity, it sold out on the first day it was released and was in short supply over the 2014 holiday shopping season . [ 4 ]
Production was ramped up in March 2015 to increase availability, several months after the release of Android Wear but ahead of the Apple Watch . Availability was expanded in the US to include retailers Amazon , Best Buy , and Target . [ 5 ] On April 15, 2015, the Microsoft Band was released in the UK priced at £169.99 and available for purchase through the Microsoft Store, or from select partners. [ 6 ]
The Microsoft band incorporates ten sensors , though only eight were documented on Microsoft's product page:
The Band's battery was designed to run for two days on a full charge, [ 4 ] [ 7 ] and the device partially relies on its companion app Microsoft Health , which was available for operating systems beginning with Windows Phone 8.1 , Android 4.3+ , and iOS 7.1+ , if Bluetooth was available. [ 8 ]
Despite being designed as a fitness tracker, the Band has numerous smartwatch -like features, such as built in apps (called tiles ) like Exercise , UV , Alarm & Timer , Calls , Messages , Calendar , Facebook , Weather and more. [ 9 ]
The Band worked with any Windows Phone 8.1 device. If paired with a device running Windows Phone 8.1 Update 1 , Cortana might also be available, although some features still require direct use of the paired phone . [ 10 ] This Update 1 was included with the Lumia Denim firmware for Microsoft Lumia phones. Users can view their latest notifications on their phone by using the Notifications Center Tile.
The device functioned as a way to promote Microsoft software and license it to developers and OEMs . [ 11 ] | https://en.wikipedia.org/wiki/Microsoft_Band |
Microsoft Band 2 was the second-generation smart band with smartwatch features developed by Microsoft . Announced on October 6, 2015, it succeeded the original Microsoft Band and was initially available in the United States, United Kingdom and Canada. It was later also available in Australia through the Sydney flagship store, Microsoft online store, [ 1 ] and selected retailers such as JB Hi-Fi [ 2 ] and Harvey Norman. [ 3 ] Like its predecessor, it incorporates fitness tracking and is compatible with Windows , iOS and Android smartphones via a Bluetooth connection. On October 3, 2016, it was discontinued. [ 4 ] On May 31, 2019, the Band's companion app stopped working and Microsoft offered refunds for customers who were still active platform users. [ 5 ]
The Microsoft Band 2 includes multiple sensors:
Although the Microsoft Band 2 is primarily designed for use with activities related to fitness, it also provides extensive smartwatch-like features such as sleep tracking, communication tools, as well as many standard features you would expect on a digital wrist watch.
The Band 2 uses its sensors to track sleep patterns when it is worn to bed. It can advise whether the user woke during the night, and provide information about sleep quality and duration.
When paired with a smartphone, the Band 2 can exchange information with the smartphone. This allows the Band 2 to show:
The Microsoft Band 2 can be used as a replacement for a normal digital wrist watch. It includes the following standard time features:
Certain functions of the Microsoft Band 2, such as the ability to reply to text messages using Cortana , are only available when paired with phones running a Microsoft mobile OS. [ 6 ] Android users can reply with a set of predefined messages while iOS users cannot reply at all.
Additionally, certain sync issues—most notably inaccuracies in the weather tile. Some have made efforts to rectify the situation using Microsoft's Web Tiles. [ 7 ] [ 8 ]
There are issues when using the Band with Windows 10 Mobile . [ 9 ]
There have been several reports that the plastic elastomer band material will fail after minimal use. [ 10 ] Users describe cracks developing in the band, which required device replacement by Microsoft. [ 11 ] Microsoft will not make the strap slightly thicker, and has decided to discontinue the line. | https://en.wikipedia.org/wiki/Microsoft_Band_2 |
Microsoft Loop is an online collaborative workspace developed by Microsoft that offers a variety of features to help users gather, organize, and build notes, ideas, and projects.
Loop was officially announced on 2 November 2021 as an addition to Microsoft 365 suite of apps. [ 4 ]
According to The Verge , Loop provides "blocks of collaborative text or content that can live independently and be copied, pasted, and shared freely." [ 5 ]
Microsoft Loop comes with templates for meetings, project planning, and personal tasks, and offers integration with other Microsoft and third-party tools and services. [ 6 ] It supports a maximum of 50 users editing a workspace simultaneously. [ 7 ]
Similar to Notion , it includes workspaces and pages where users can import and organize tasks, projects, and documents.
However, it also uses shareable components that allow content from Loop to be turned into a real-time block of content that can be pasted into Teams , Outlook , Word and Whiteboard . It also features the ability to use Microsoft Copilot . [ 8 ]
This software article is a stub . You can help Wikipedia by expanding it . | https://en.wikipedia.org/wiki/Microsoft_Loop |
Microsoft Math Solver (formerly Microsoft Mathematics and Microsoft Math ) is an entry-level educational app that solves math and science problems. Developed and maintained by Microsoft , it is primarily targeted at students as a learning tool. Until 2015, it ran on Microsoft Windows. Since then, it has been developed for the web platform and mobile devices .
Microsoft Math was originally released as a bundled part of Microsoft Student . It was then available as a standalone paid version starting with version 3.0. For version 4.0, it was released as a free downloadable product [ 4 ] and was called Microsoft Mathematics 4.0. It is no longer in active development and has been removed from the Microsoft website. [ 5 ] A related freeware add-in, called "Microsoft Mathematics Add-In for Word and OneNote ," is also available from Microsoft and offers comparable functionality (Word 2007 or higher is required). [ 3 ] [ 6 ]
Microsoft Math received the 2008 Award of Excellence from Tech & Learning Magazine. [ 7 ]
Microsoft Math contains features that are designed to assist in solving mathematics, science, and tech-related problems, as well as to educate the user. The application features such tools as a graphing calculator and a unit converter . It also includes a triangle solver and an equation solver that provides step-by-step solutions to each problem.
The system requirements for Microsoft Mathematics 4.0 are: [ 5 ] | https://en.wikipedia.org/wiki/Microsoft_Math_Solver |
Messaging (also known as Microsoft Messaging , and as of recently, Windows Operator Messages ) is an instant messaging Universal Windows Platform app for Windows 10 .
Its mobile version for Windows 10 Mobile allowed SMS , MMS and RCS messaging. The desktop version is restricted to showing SMS messages sent via Skype , and billing SMS message from an LTE operator. [ 1 ] [ 2 ]
As of recently, the app was refocused into a SMS data plan app, where your mobile operator sends messages about your data plan, this is due to the functionality of the app switching to Skype. It was also partially renamed to Windows Operator Messages.
Due to Skype closing in May 2025, Windows Operator Messages will stop working as it uses the platform, the fate of the app itself is unknown.
This article related to Microsoft is a stub . You can help Wikipedia by expanding it . | https://en.wikipedia.org/wiki/Microsoft_Messaging |
Microsoft Point-to-Point Compression ( MPPC ; described in RFC 2118) is a streaming data compression algorithm based on an implementation of Lempel–Ziv using a sliding window buffer. According to Hifn 's IP statement, [ 1 ] MPPC was patent -encumbered (last US patent granted on 1996-07-02).
Whereas V.44 or V.42bis operate at layer 1 on the OSI model , MPPC operates on layer 2, giving it a significant advantage in terms of computing resources available to it. The dialup modem 's in-built compression (V.44 or V.42bis) can only occur after the data has been serially transmitted to the modem, typically at a maximum rate of 115,200 bit/s. MPPC, as it is controlled by the operating system , can receive as much data as it wishes to compress, before forwarding it on to the modem.
The modem's hardware must not delay data too much, while waiting for more to compress in one packet, otherwise an unacceptable latency level will result. It also cannot afford to, as this would require both sizable computing resources (on the scale of a modem) as well as significant buffer RAM . Software compression such as MPPC is free to use the host computer's resources, exceeding the modem's by several orders of magnitude. This allows it to keep a much larger buffer to work on at any one time, and it processes through a given amount of data much faster.
The end result is that where V.44 may achieve a maximum of 4:1 compression (230 kbit/s) but is usually limited to 115.2 kbit/s, MPPC is capable of a maximum of 8:1 compression (460 kbit/s). MPPC also, given the far greater computing power at its disposal, is more effective on data than V.44 and achieves higher compression ratios when 8:1 isn't achievable. | https://en.wikipedia.org/wiki/Microsoft_Point-to-Point_Compression |
Microsoft SharePoint Workspace (formerly Microsoft Office Groove [ 5 ] ) is a discontinued desktop application designed for document collaboration in teams with members who are regularly off-line or who do not share the same network security clearance. It is no longer included with Microsoft Office 2013 . It has been replaced by a web-based service called OneDrive for Business .
Groove's uses have included coordination between emergency relief agencies, [ 6 ] where different organizations do not share a common security infrastructure and where offline access is important, and amongst teams of knowledge workers , such as consultants who need to work securely on client sites.
It is also used as a staging system for documents in development, where content can be developed then transferred to a portal when complete.
Groove was initially developed by Lotus Notes creator Ray Ozzie , and developed by Groove Networks of Beverly, Massachusetts , until Microsoft's acquisition of Groove Networks in March 2005. [ 7 ]
Groove's basic set of services (including always-on security , persistent chat , store-and-forward messaging delivery, firewall / NAT transparency, ad-hoc group formation, and change notification) may be customized with tools.
Tools are mini-applications that rely on Groove's underlying functionality to disseminate and synchronize their contents with other members' copies of the workspace. Groove provides various tools that can be added to (and removed from) a workspace to customize the functionality of each space (for example a calendar , discussion, file sharing , an outliner , pictures, notepad, sketchpad, web browser , etc.).
Tools that members use in a workspace often drive the nature of the person-to-person collaboration that ensues. In Groove 2007, the SharePoint Files tools can be used to take SharePoint 2007 document libraries offline. [ 8 ]
Groove 2007 includes a presence subsystem, which keeps track of which users in the contact store are online, and presents the information in the launchbar. If Groove server is used, a user is considered online when they log on to the server. In absence of a server, the Device Presence Protocol (which comes in different variants for LANs and WANs ) is used. Groove also allows sending instant messages to peers. All session and user information is stored by the Groove client at client side. [ 9 ]
Groove Virtual Office 3.1 was the last version before Microsoft's acquisition of Groove Networks. The following versions have been released since:
Microsoft claims the name change is a natural progression, since Groove is to SharePoint what Outlook is to Exchange. Microsoft asserts that features have been added to make it easier to deploy and manage, and claims that SharePoint Workspace will make it easier to access SharePoint content (or content from any server that implements the publicly documented protocols). [ 12 ]
Microsoft Groove Server is a tool for centrally managing all deployments of Microsoft SharePoint Workspace in an enterprise. It enables using Active Directory for Groove user accounts, and create Groove Domains, with individual policy settings. [ 13 ] [ 14 ] | https://en.wikipedia.org/wiki/Microsoft_SharePoint_Workspace |
The Microsoft Support Diagnostic Tool (MSDT) is a legacy service in Microsoft Windows that allows Microsoft technical support agents to analyze diagnostic data remotely for troubleshooting purposes. [ 1 ] In April 2022 it was observed to have a security vulnerability that allowed remote code execution which was being exploited to attack computers in Russia and Belarus, and later against the Tibetan government in exile. [ 2 ] Microsoft advised a temporary workaround of disabling the MSDT by editing the Windows registry . [ 3 ]
When contacting support the user is told to run MSDT and given a unique "passkey" which they enter. They are also given an "incident number" to uniquely identify their case. The MSDT can also be run offline which will generate a .CAB file which can be uploaded from a computer with an internet connection. [ 4 ]
Follina is the name given to a remote code execution (RCE) vulnerability, a type of arbitrary code execution (ACE) exploit, in the Microsoft Support Diagnostic Tool (MSDT) which was first widely publicized on May 27, 2022, by a security research group called Nao Sec. [ 5 ] This exploit allows a remote attacker to use a Microsoft Office document template to execute code via MSDT. This works by exploiting the ability of Microsoft Office document templates to download additional content from a remote server. If the size of the downloaded content is large enough it causes a buffer overflow allowing a payload of Powershell code to be executed without explicit notification to the user. On May 30 Microsoft issued CVE -2022-30190 [ 6 ] with guidance that users should disable MSDT. [ 7 ] Malicious actors have been observed exploiting the bug to attack computers in Russia and Belarus since April, and it is believed Chinese state actors had been exploiting it to attack the Tibetan government in exile based in India. [ 8 ] Microsoft patched this vulnerability in its June 2022 patches. [ 9 ]
The DogWalk vulnerability is a remote code execution (RCE) vulnerability in the Microsoft Support Diagnostic Tool (MSDT). It was first reported in January 2020, but Microsoft initially did not consider it to be a security issue. However, the vulnerability was later exploited in the wild, and Microsoft released a patch for it in August 2022.
The vulnerability is caused by a path traversal vulnerability in the sdiageng.dll library. This vulnerability allows an attacker to trick a victim into opening a malicious diagcab file, which is a type of Windows cabinet file that is used to store support files. When the diagcab file is opened, it triggers the MSDT tool, which then executes the malicious code.
Originally discovered by Mitja Kolsek, the DogWalk vulnerability is caused by a path traversal vulnerability in the sdiageng.dll library. This vulnerability allows an attacker to trick a victim into opening a malicious diagcab file, which is a type of Windows cabinet file that is used to store support files. When the diagcab file is opened, it triggers the MSDT tool, which then executes the malicious code.
The vulnerability is exploited by creating a malicious diagcab file that contains a specially crafted path. This path contains a sequence of characters that is designed to exploit the path traversal vulnerability in the sdiageng.dll library. When the diagcab file is opened, the MSDT tool will attempt to follow the path. However, the path will contain characters that are not valid for a Windows path. This will cause the MSDT tool to crash.
When the MSDT tool crashes, it will generate a memory dump. This memory dump will contain the malicious code that was executed by the MSDT tool. The attacker can then use this memory dump to extract the malicious code and execute it on their own computer. [ 10 ] [ 11 ]
Microsoft will no longer be supporting the Windows legacy inbox Troubleshooters. In 2025, Microsoft will remove the MSDT platform entirely. [ 12 ] Get Help is the replacement tool.
Future versions and feature upgrades will deprecate the MSDT after May 23, 2023.
This computer security article is a stub . You can help Wikipedia by expanding it . | https://en.wikipedia.org/wiki/Microsoft_Support_Diagnostic_Tool |
Microsoft SwiftKey is a virtual keyboard app originally developed by TouchType for Android and iOS devices. It was first released for Android in July 2010, [ 5 ] followed by an iOS release in September 2014 after Apple's implementation of third-party keyboard support. [ 6 ]
The company behind SwiftKey was founded in 2008 [ 7 ] by Jon Reynolds, Ben Medlock [ 8 ] and Chris Hill-Scott. [ 9 ] Today, their head office is located at the Microsoft offices in Paddington , London , and their other offices are located in San Francisco , California and Seoul . [ 10 ]
In September 2013, SwiftKey announced a series B finance round totaling $17.5 million led by Index Ventures , along with Octopus Investments and Accel Partners . [ 11 ]
In May 2014, SwiftKey hired James Bromley as COO . [ 12 ]
In February 2016, SwiftKey was purchased by Microsoft for USD$250 million (~USD$311 million in 2023). [ 13 ] [ 14 ]
In May 2020, the app was rebranded as Microsoft SwiftKey to reflect its present ownership. [ 15 ]
In September 2022, Microsoft announced that they were ending support for the iOS version of SwiftKey. The app was ultimately removed from the App Store on 5 October 2022 [ 16 ] However, in November 2022, Microsoft announced that they decided to reverse their decision to discontinue SwiftKey for iOS devices. The app was relisted on 18 November, with Microsoft assuring future updates for the app. The company cited "customer feedback" as a reason for SwiftKey's return. [ 17 ]
Microsoft SwiftKey is a virtual keyboard released on the Android and iOS operating systems . The purpose of the app is to increase efficiency while typing on a mobile phone . According to the Microsoft SwiftKey website, SwiftKey allows the user to speed up their typing process by "giving them more accurate autocorrect and predictions by learning their writing style". [ 18 ]
SwiftKey was first released as a beta in the Android Market on 14 July 2010, supporting seven languages. It included a variety of settings to adjust audio feedback volume and length of haptic feedback vibration. It was announced on SwiftKey's official website on 15 May 2014 that a Japanese version was available for beta testing. [ 19 ]
On 14 July 2011, SwiftKey X was released to the Android Market as an upgrade to SwiftKey. The upgrade brought updated features and SwiftKey X introduced a dedicated app for tablets called SwiftKey Tablet X . New features included: [ 20 ]
The SwiftKey 3 update was released on 21 June 2012, including:
The SwiftKey 4 update was released on 20 February 2013, including:
The SwiftKey 5 update [ 21 ] was released in June 2014, including:
The SwiftKey 6 update [ 21 ] was released in November 2015, including:
The SwiftKey 7.0 update was released in March 2018, including:
SwiftKey released an iOS application on 30 January 2014, called Swiftkey Note , which incorporates SwiftKey's predictive typing technology as a custom toolbar attached to the top of the regular iOS keyboard. [ 22 ]
Starting with iOS 8 , released in the second half of 2014, the operating system enables and supports third-party keyboards use. SwiftKey confirmed that it was working on a keyboard replacement app. [ 23 ]
Starting with iOS 13 , the system keyboard came with a built in QuickPath mechanism, which works similarly to SwiftKey's swiping feature. [ 24 ]
SwiftKey for iOS was announced to be deprecated in September 2022. [ 25 ] In November 2022, however, Microsoft reverted this decision. [ 26 ]
SwiftKey Keyboard for iPhone , iPad and iPod Touch launched in September 2014 to coincide with the launch of Apple's iOS 8 update. It was unveiled at TechCrunch Disrupt in San Francisco . [ 27 ]
The app includes the word prediction and auto-correction features, familiar to the Android product, SwiftKey Cloud backup and sync and personalization, and a choice of color themes.
It reached No. 1 in the free US App Store charts and the company confirmed it had been downloaded more than 1 million times on the first day of launch. [ 28 ]
On 27 February 2012, the SwiftKey SDK was launched. [ 29 ] This allows developers on multiple platforms and programming languages to access SwiftKey's core language-engine technology for their own UI or virtual keyboard . [ 29 ]
In June 2012, SwiftKey released a specialized version of its keyboard called SwiftKey Healthcare . It is a virtual keyboard for iOS, Android, Windows Phone and BlackBerry devices that offers next-word predictions based on real-world clinical data. [ 30 ] In October 2012, SwiftKey Healthcare won the Appsters Award for Best Enterprise App 2012 . [ 31 ]
In April 2016, SwiftKey released a keyboard that emulated William Shakespeare 's speech called ShakeSpeak in observance of the 400th year of the author's death. [ 32 ] The app was co-developed with VisitLondon.com to promote more tourism to the metropolitan area of London . [ 33 ]
SwiftKey integration was included with Windows 10 beginning with the October 2018 Update. [ 34 ] However, these features were later removed from Windows 10 beginning with the May 2020 Update. [ 35 ]
In 2015, NowSecure reported a vulnerability present in the version of SwiftKey pre-installed on Samsung devices. This would occur when the keyboard attempted to update its language pack. Samsung has since released security and firmware updates to mitigate the issue. However, TechCrunch published an article on why the issue happened because of how Samsung implemented the keyboard system on its devices. [ 36 ] [ 37 ] [ 38 ]
In 2016, SwiftKey users began reporting that the app was displaying personal details as suggested words to other users who did not have previous connections. Other issues included foreign languages and obscene words. SwiftKey responded by disabling cloud sync for word suggestions and releasing an update to mitigate the issue. [ 39 ] [ 40 ] [ 41 ]
SwiftKey has received multiple awards, including: | https://en.wikipedia.org/wiki/Microsoft_SwiftKey |
Microsoft Windows was announced by Bill Gates on November 10, 1983, 2 years before it was first released. [ 1 ] Microsoft introduced Windows as a graphical user interface for MS-DOS , which had been introduced two years earlier, on August 12, 1981. The product line evolved in the 1990s from an operating environment into a fully complete, modern operating system over two lines of development, each with their own separate codebase.
The first versions of Windows (1.0 through to 3.11) were graphical shells that ran from MS-DOS. Windows 95 , though still being based on MS-DOS, was its own operating system. Windows 95 also had a significant amount of 16-bit code ported from Windows 3.1. [ 2 ] [ 3 ] [ 4 ] Windows 95 introduced multiple features that have been part of the product ever since, including the Start menu , the taskbar , and Windows Explorer (renamed File Explorer in Windows 8). In 1997, Microsoft released Internet Explorer 4 which included the (at the time controversial) Windows Desktop Update . It aimed to integrate Internet Explorer and the web into the user interface and also brought new features into Windows, such as the ability to display JPEG images as the desktop wallpaper and single window navigation in Windows Explorer. In 1998, Microsoft released Windows 98, which also included the Windows Desktop Update and Internet Explorer 4 by default. The inclusion of Internet Explorer 4 and the Desktop Update led to an antitrust case in the United States . Windows 98 included USB support out of the box, and also plug and play , which allows devices to work when plugged in without requiring a system reboot or manual configuration. Windows Me , the last DOS-based version of Windows, was aimed at consumers and released in 2000. It introduced System Restore , Help and Support Center , updated versions of the Disk Defragmenter and other system tools.
In 1993, Microsoft released Windows NT 3.1 , the first version of the newly developed Windows NT operating system, followed by Windows NT 3.5 in 1994, and Windows NT 3.51 in 1995. "NT" is an initialism for "New Technology". [ 3 ] Unlike the Windows 9x series of operating systems, it was a fully 32-bit operating system. NT 3.1 introduced NTFS , a file system designed to replace the older File Allocation Table (FAT) which was used by DOS and the DOS-based Windows operating systems. In 1996, Windows NT 4.0 was released, which included a fully 32-bit version of Windows Explorer written specifically for it, making the operating system work like Windows 95. Windows NT was originally designed to be used on high-end systems and servers, but with the release of Windows 2000 , many consumer-oriented features from Windows 95 and Windows 98 were included, such as the Windows Desktop Update , Internet Explorer 5 , USB support and Windows Media Player . These consumer-oriented features were further extended in Windows XP in 2001, which included a new visual style called Luna , a more user-friendly interface, updated versions of Windows Media Player and Internet Explorer 6 by default, and extended features from Windows Me, such as the Help and Support Center and System Restore. Windows Vista , which was released in 2007, focused on securing the Windows operating system against computer viruses and other malicious software by introducing features such as User Account Control . New features include Windows Aero , updated versions of the standard games (e.g. Solitaire ), Windows Movie Maker, and Windows Mail to replace Outlook Express . Despite this, Windows Vista was critically panned for its poor performance on older hardware and its at-the-time high system requirements. Windows 7 followed in 2009 nearly three years after its launch, and despite it technically having higher system requirements, [ 5 ] [ 6 ] reviewers noted that it ran better than Windows Vista. [ 7 ] Windows 7 removed many applications, such as Windows Movie Maker , Windows Photo Gallery and Windows Mail , instead requiring users to download separate Windows Live Essentials to gain some of those features and other online services. Windows 8 , which was released in 2012, introduced many controversial changes, such as the replacement of the Start menu with the Start Screen, the removal of the Aero interface in favor of a flat, colored interface as well as the introduction of "Metro" apps (later renamed to Universal Windows Platform apps ), and the Charms Bar user interface element, all of which received considerable criticism from reviewers. [ 8 ] [ 9 ] [ 10 ] Windows 8.1, a free upgrade to Windows 8, was released in 2013. [ 11 ]
The following version of Windows, Windows 10 , which was released in 2015, reintroduced the Start menu and added the ability to run Universal Windows Platform apps in a window instead of always in full screen. Windows 10 was generally well-received, with many reviewers stating that Windows 10 is what Windows 8 should have been. [ 12 ] [ 13 ] [ 14 ]
The latest version of Windows, Windows 11 , was released to the general public on October 5, 2021. Windows 11 incorporates a redesigned user interface, including a new Start menu, a visual style featuring rounded corners, and a new layout for the Microsoft Store, [ 15 ] and also included Microsoft Edge by default.
Windows 1.0, the first independent version of Microsoft Windows, released on November 20, 1985, achieved little popularity. The project was briefly codenamed "Interface Manager" before the windowing system was implemented—contrary to popular belief that it was the original name for Windows and Rowland Hanson , the head of marketing at Microsoft, convinced the company that the name Windows would be more appealing to customers. [ 16 ]
Windows 1.0 was not a complete operating system, but rather an "operating environment" that extended MS-DOS , and shared the latter's inherent flaws.
The first version of Microsoft Windows included a simple graphics painting program called Windows Paint ; Windows Write , a simple word processor ; an appointment calendar; a card-filer; a notepad ; a clock; a control panel ; a computer terminal ; Clipboard ; and RAM driver. It also included the MS-DOS Executive and a game called Reversi .
Microsoft had worked with Apple Computer to develop applications for Apple's new Macintosh computer, which featured a graphical user interface . As part of the related business negotiations, Microsoft had licensed certain aspects of the Macintosh user interface from Apple; in later litigation, a district court summarized these aspects as "screen displays".
In the development of Windows 1.0, Microsoft intentionally limited its borrowing of certain GUI elements from the Macintosh user interface, to comply with its license. For example, windows were only displayed "tiled" on the screen; that is, they could not overlap or overlie one another.
On December 31, 2001, Microsoft declared Windows 1.0 obsolete and stopped providing support and updates for the system.
During the mid to late 1980s, Microsoft and IBM had cooperatively been developing OS/2 as a successor to DOS. OS/2 would take full advantage of the aforementioned protected mode of the Intel 80286 processor and up to 16 MB of memory. OS/2 1.0, released in 1987, supported swapping and multitasking and allowed running of DOS executables.
IBM licensed Windows' GUI for OS/2 as Presentation Manager , and the two companies stated that it and Windows 2.0 would be almost identical. [ 17 ] Presentation Manager was not available with OS/2 until version 1.1, released in 1988. Its API was incompatible with Windows. Version 1.2, released in 1989, introduced a new file system , HPFS , to replace the FAT file system.
By the early 1990s, conflicts developed in the Microsoft/IBM relationship. They cooperated with each other in developing their PC operating systems and had access to each other's code. Microsoft wanted to further develop Windows, while IBM desired for future work to be based on OS/2. In an attempt to resolve this tension, IBM and Microsoft agreed that IBM would develop OS/2 2.0, to replace OS/2 1.3 and Windows 3.0, while Microsoft would develop the next version, OS/2 3.0.
This agreement soon fell apart however, and the Microsoft/IBM relationship was terminated. IBM continued to develop OS/2, while Microsoft changed the name of its (as yet unreleased) OS/2 3.0 to Windows NT . Both retained the rights to use OS/2 and Windows technology developed up to the termination of the agreement; Windows NT, however, was to be written anew, mostly independently (see below).
After an interim 1.3 version to fix up many remaining problems with the 1.x series, IBM released OS/2 version 2.0 in 1992. This was a major improvement: it featured a new, object-oriented GUI, the Workplace Shell (WPS), that included a desktop and was considered by many to be OS/2's best feature. Microsoft would later imitate much of it in Windows 95. Version 2.0 also provided a full 32-bit API, offered smooth multitasking and could take advantage of the 4 gigabytes of address space provided by the Intel 80386 . Still, much of the system had 16-bit code internally which required, among other things, device drivers to be 16-bit code as well. This was one of the reasons for the chronic shortage of OS/2 drivers for the latest devices. Version 2.0 could also run DOS and Windows 3.0 programs, since IBM had retained the right to use the DOS and Windows code as a result of the breakup.
Microsoft Windows version 2.0 (2.01 and 2.03 internally) came out on December 9, 1987, and proved slightly more popular than its predecessor. Much of the popularity for Windows 2.0 came by way of its inclusion as a "run-time version" with Microsoft's new graphical applications, Excel and Word for Windows . They could be run from MS-DOS, executing Windows for the duration of their activity, and closing down Windows upon exit.
Microsoft Windows received a major boost around this time when Aldus PageMaker appeared in a Windows version, having previously run only on Macintosh . Some computer historians [ who? ] date this, the first appearance of a significant and non-Microsoft application for Windows, as the start of the success of Windows.
Like prior versions of Windows, version 2.0 could use the real-mode memory model, which confined it to a maximum of 1 megabyte of memory. In such a configuration, it could run under another multitasker like DESQview , which used the 286 protected mode . It was also the first version to support the High Memory Area when running on an Intel 80286 compatible processor. This edition was renamed Windows/286 with the release of Windows 2.1.
A separate Windows/386 edition had a protected mode kernel, which required an 80386 compatible processor, with LIM-standard EMS emulation and VxD drivers in the kernel. All Windows and DOS-based applications at the time were real mode, and Windows/386 could run them over the protected mode kernel by using the virtual 8086 mode , which was new with the 80386 processor.
Version 2.1 came out on May 27, 1988, followed by version 2.11 on March 13, 1989; they included a few minor changes.
In Apple Computer, Inc. v. Microsoft Corp. , version 2.03, and later 3.0, faced challenges from Apple over its overlapping windows and other features Apple charged mimicked the ostensibly copyrighted "look and feel" of its operating system and "embodie[d] and generated a copy of the Macintosh" in its OS. Judge William Schwarzer dropped all but 10 of Apple's 189 claims of copyright infringement, and ruled that most of the remaining 10 were over uncopyrightable ideas. [ 18 ]
On December 31, 2001, Microsoft declared Windows 2.x obsolete and stopped providing support and updates for the system.
Windows 3.0 , released in May 1990, improved capabilities given to native applications. It also allowed users to better multitask older MS-DOS based software compared to Windows/386, thanks to the introduction of virtual memory .
Windows 3.0's user interface finally resembled a serious competitor to the user interface of the Macintosh computer. PCs had improved graphics by this time, due to VGA video cards, and the protected/enhanced mode allowed Windows applications to use more memory in a more painless manner than their DOS counterparts could. Windows 3.0 could run in real, standard, or 386 enhanced modes, and was compatible with any Intel processor from the 8086 / 8088 up to the 80286 and 80386 . This was the first version to run Windows programs in protected mode, although the 386 enhanced mode kernel was an enhanced version of the protected mode kernel in Windows/386.
Windows 3.0 received two updates. A few months after introduction, Windows 3.0a was released as a maintenance release, resolving bugs and improving stability. A "multimedia" version, Windows 3.0 with Multimedia Extensions 1.0, was released in October 1991. This was bundled with "multimedia upgrade kits", comprising a CD-ROM drive and a sound card , such as the Creative Labs Sound Blaster Pro . This version was the precursor to the multimedia features available in Windows 3.1 (first released in April 1992) and later, and was part of Microsoft's specification for the Multimedia PC .
The features listed above and growing market support from application software developers made Windows 3.0 wildly successful, selling around 10 million copies in the two years before the release of version 3.1. Windows 3.0 became a major source of income for Microsoft, and led the company to revise some of its earlier plans. Support was discontinued on December 31, 2001. [ 19 ]
In response to the impending release of OS/2 2.0, Microsoft developed Windows 3.1 (first released in April 1992), which included several improvements to Windows 3.0, such as display of TrueType scalable fonts (developed jointly with Apple), improved disk performance in 386 Enhanced Mode, multimedia support, and bugfixes. It also removed Real Mode, and only ran on an 80286 or better processor. Later Microsoft also released Windows 3.11, a touch-up to Windows 3.1 which included all of the patches and updates that followed the release of Windows 3.1 in 1992.
In 1992 and 1993, Microsoft released Windows for Workgroups (WfW), which was available both as an add-on for existing Windows 3.1 installations and in a version that included the base Windows environment and the networking extensions all in one package. Windows for Workgroups included improved network drivers and protocol stacks, and support for peer-to-peer networking. There were two versions of Windows for Workgroups – 3.1 and 3.11. Unlike prior versions, Windows for Workgroups 3.11 ran in 386 Enhanced Mode only, and needed at least an 80386SX processor. One optional download for WfW was the "Wolverine" TCP/IP protocol stack, which allowed for easy access to the Internet through corporate networks.
All these versions continued version 3.0's impressive sales pace. Even though the 3.1x series still lacked most of the important features of OS/2, such as long file names, a desktop, or protection of the system against misbehaving applications, Microsoft quickly took over the OS and GUI markets for the IBM PC . The Windows API became the de facto standard for consumer software.
On December 31, 2001, Microsoft declared Windows 3.1 obsolete and stopped providing support and updates for the system. However, OEM licensing for Windows for Workgroups 3.11 on embedded systems continued to be available until November 1, 2008. [ 20 ]
Meanwhile, Microsoft continued to develop Windows NT. The main architect of the system was Dave Cutler , one of the chief architects of VAX/VMS at Digital Equipment Corporation . [ 21 ] Microsoft hired him in October 1988 to create a successor to OS/2, but Cutler created a completely new system instead. Cutler had been developing a follow-on to VMS at DEC called MICA , and when DEC dropped the project he brought the expertise and around 20 engineers with him to Microsoft.
Windows NT Workstation (Microsoft marketing wanted Windows NT to appear to be a continuation of Windows 3.1) arrived in Beta form to developers at the July 1992 Professional Developers Conference in San Francisco . [ 22 ] Microsoft announced at the conference its intentions to develop a successor to both Windows NT and Windows 3.1's replacement ( Windows 95 , codenamed Chicago), which would unify the two into one operating system. This successor was codenamed Cairo . In hindsight, Cairo was a much more difficult project than Microsoft had anticipated and, as a result, NT and Chicago would not be unified until Windows XP —albeit Windows 2000 , oriented to business, had already unified most of the system's bolts and gears, it was XP that was sold to home consumers like Windows 95 and came to be viewed as the final unified OS. Parts of Cairo have still not made it into Windows as of 2025 [update] : most notably, the WinFS file system, which was the much touted Object File System of Cairo. Microsoft announced in 2006 that they would not make a separate release of WinFS for Windows XP and Windows Vista [ 23 ] and would gradually incorporate the technologies developed for WinFS in other products and technologies, notably Microsoft SQL Server .
Driver support was lacking due to the increased programming difficulty in dealing with NT's superior hardware abstraction model. This problem plagued the NT line all the way through Windows 2000. Programmers complained that it was too hard to write drivers for NT, and hardware developers were not going to go through the trouble of developing drivers for a small segment of the market. Additionally, although allowing for good performance and fuller exploitation of system resources, it was also resource-intensive on limited hardware, and thus was only suitable for larger, more expensive machines.
However, these same features made Windows NT perfect for the LAN server market (which in 1993 was experiencing a rapid boom, as office networking was becoming common). NT also had advanced network connectivity options and NTFS , an efficient file system. Windows NT version 3.51 was Microsoft's entry into this field, and took away market share from Novell (the dominant player) in the following years.
One of Microsoft's biggest advances initially developed for Windows NT was a new 32-bit API, to replace the legacy 16-bit Windows API . This API was called Win32 , and from then on Microsoft referred to the older 16-bit API as Win16 . The Win32 API had three levels of implementation: the complete one for Windows NT, a subset for Chicago (originally called Win32c ) missing features primarily of interest to enterprise customers (at the time) such as security and Unicode support, and a more limited subset called Win32s which could be used on Windows 3.1 systems. Thus Microsoft sought to ensure some degree of compatibility between the Chicago design and Windows NT, even though the two systems had radically different internal architectures.
Windows NT was the first Windows operating system based on a hybrid kernel . The hybrid kernel was designed as a modified microkernel , influenced by the Mach microkernel developed by Richard Rashid at Carnegie Mellon University, but without meeting all of the criteria of a pure microkernel.
As released, Windows NT 3.x went through three versions (3.1, 3.5, and 3.51), changes were primarily internal and reflected back end changes. The 3.5 release added support for new types of hardware and improved performance and data reliability; the 3.51 release was primarily to update the Win32 APIs to be compatible with software being written for the Win32c APIs in what became Windows 95. Support for Windows NT 3.51 ended in 2001 and 2002 for the Workstation and Server editions, respectively.
After Windows 3.11 , Microsoft began to develop a new consumer-oriented version of the operating system codenamed Chicago. Chicago was designed to have support for 32-bit preemptive multitasking like OS/2 and Windows NT, although a 16-bit kernel would remain for the sake of backward compatibility. The Win32 API first introduced with Windows NT was adopted as the standard 32-bit programming interface, with Win16 compatibility being preserved through a technique known as " thunking ". A new object-oriented GUI was not originally planned as part of the release, although elements of the Cairo user interface were borrowed and added as other aspects of the release (notably Plug and Play) slipped.
Microsoft did not change all of the Windows code to 32-bit; parts of it remained 16-bit (albeit not directly using real mode ) for reasons of compatibility, performance, and development time. Additionally it was necessary to carry over design decisions from earlier versions of Windows for reasons of backwards compatibility, even if these design decisions no longer matched a more modern computing environment. These factors eventually began to impact the operating system's efficiency and stability.
Microsoft marketing adopted Windows 95 as the product name for Chicago when it was released on August 24, 1995. Microsoft had a double gain from its release: first, it made it impossible for consumers to run Windows 95 on a cheaper, non-Microsoft DOS, secondly, although traces of DOS were never completely removed from the system and MS DOS 7 would be loaded briefly as a part of the booting process, Windows 95 applications ran solely in 386 enhanced mode, with a flat 32-bit address space and virtual memory . These features make it possible for Win32 applications to address up to 2 gigabytes of virtual RAM (with another 2 GB reserved for the operating system), and in theory prevented them from inadvertently corrupting the memory space of other Win32 applications. In this respect the functionality of Windows 95 moved closer to Windows NT , although Windows 95/98/Me did not support more than 512 megabytes of physical RAM without obscure system tweaks. Three years after its introduction, Windows 95 was succeeded by Windows 98 .
IBM continued to market OS/2, producing later versions in OS/2 3.0 and 4.0 (also called Warp). Responding to complaints about OS/2 2.0's high demands on computer hardware, version 3.0 was significantly optimized both for speed and size. Before Windows 95 was released, OS/2 Warp 3.0 was even shipped pre-installed with several large German hardware vendor chains. However, with the release of Windows 95, OS/2 began to lose market share.
It is probably impossible to choose one specific reason why OS/2 failed to gain much market share. While OS/2 continued to run Windows 3.1 applications, it lacked support for anything but the Win32s subset of Win32 API (see above). Unlike with Windows 3.1, IBM did not have access to the source code for Windows 95 and was unwilling to commit the time and resources to emulate the moving target of the Win32 API. IBM later introduced OS/2 into the United States v. Microsoft case, blaming unfair marketing tactics on Microsoft's part.
Microsoft went on to release five different versions of Windows 95:
OSR2, OSR2.1, and OSR2.5 were not released to the general public, rather, they were available only to OEMs that would preload the OS onto computers. Some companies sold new hard drives with OSR2 preinstalled (officially justifying this as needed due to the hard drive's capacity).
The first Microsoft Plus! add-on pack was sold for Windows 95. Microsoft ended extended support for Windows 95 on December 31, 2001.
4.00
Microsoft released the successor to NT 3.51, Windows NT 4.0 , on August 24, 1996, one year after the release of Windows 95. It was Microsoft's primary business-oriented operating system until the introduction of Windows 2000 . Major new features included the new Explorer shell from Windows 95, scalability and feature improvements to the core architecture , kernel, USER32 , COM and MSRPC . [ 24 ]
Windows NT 4.0 came in five versions:
Microsoft ended mainstream support for Windows NT 4.0 Workstation on June 30, 2002, and ended extended support on June 30, 2004, while Windows NT 4.0 Server mainstream support ended on December 31, 2002, and extended support ended on December 31, 2004. Both editions were succeeded by Windows 2000 Professional and the Windows 2000 Server Family, respectively. [ 25 ] [ 26 ] [ 27 ]
Microsoft ended mainstream support for Windows NT 4.0 Embedded on June 30, 2003, and ended extended support on July 11, 2006. This edition was succeeded by Windows XP Embedded .
On June 25, 1998, Microsoft released Windows 98 (code-named Memphis), three years after the release of Windows 95 , two years after the release of Windows NT 4.0 , and 21 months before the release of Windows 2000 . It included new hardware drivers and the FAT32 file system which supports disk partitions that are larger than 2 GB (first introduced in Windows 95 OSR2). USB support in Windows 98 is marketed as a vast improvement over Windows 95. The release continued the controversial inclusion of the Internet Explorer browser with the operating system that started with Windows 95 OEM Service Release 1. The action eventually led to the filing of the United States v. Microsoft case, dealing with the question of whether Microsoft was introducing unfair practices into the market in an effort to eliminate competition from other companies such as Netscape . [ 28 ]
In 1999, Microsoft released Windows 98 Second Edition, an interim release. One of the more notable new features was the addition of Internet Connection Sharing , a form of network address translation , allowing several machines on a LAN (Local Area Network) to share a single Internet connection . Hardware support through device drivers was increased and this version shipped with Internet Explorer 5. Many minor problems that existed in the first edition were fixed making it, according to many, the most stable release of the Windows 9x family. [ 29 ]
Mainstream support for Windows 98 and 98 SE ended on June 30, 2002. Extended support ended on July 11, 2006.
Microsoft released Windows 2000 on February 17, 2000, as the successor to Windows NT 4.0 , 17 months after the release of Windows 98 . It has the version number Windows NT 5.0, and it was Microsoft's business-oriented operating system starting with the official release on February 17, 2000, until 2001 when it was succeeded by Windows XP . Windows 2000 has had four official service packs. It was successfully deployed both on the server and the workstation markets. Amongst Windows 2000's most significant new features was Active Directory , a near-complete replacement of the NT 4.0 Windows Server domain model, which built on industry-standard technologies like DNS , LDAP , and Kerberos to connect machines to one another. Terminal Services , previously only available as a separate edition of NT 4, was expanded to all server versions. A number of features from Windows 98 were incorporated also, such as an improved Device Manager, Windows Media Player , and a revised DirectX that made it possible for the first time for many modern games to work on the NT kernel. Windows 2000 is also the last NT-kernel Windows operating system to lack product activation .
While Windows 2000 upgrades were available for Windows 95 and Windows 98, it was not intended for home users. [ 30 ]
Windows 2000 was available in four editions:
Microsoft ended support for both Windows 2000 and Windows XP Service Pack 2 on July 13, 2010.
On September 14, 2000, Microsoft released a successor to Windows 98 called Windows Me , short for "Millennium Edition". It was the last DOS-based operating system from Microsoft. Windows Me introduced a new multimedia-editing application called Windows Movie Maker , came standard with Internet Explorer 5.5 and Windows Media Player 7 , and debuted the first version of System Restore – a recovery utility that enables the operating system to revert system files back to a prior date and time. System Restore was a notable feature that would continue to thrive in all later versions of Windows.
Windows Me was conceived as a quick one-year project that served as a stopgap release between Windows 98 and Windows XP. Many of the new features were available from the Windows Update site as updates for older Windows versions ( System Restore and Windows Movie Maker were exceptions). Windows Me was criticized for stability issues, as well as for lacking real mode DOS support, to the point of being referred to as the "Mistake Edition". [ 31 ] Windows Me was the last operating system to be based on the Windows 9x ( monolithic ) kernel and MS-DOS , with its successor Windows XP being based on Microsoft's Windows NT kernel instead.
On October 25, 2001, Microsoft released Windows XP (codenamed "Whistler"). The merging of the Windows NT/2000 and Windows 95/98/Me lines was finally achieved with Windows XP. Windows XP uses the Windows NT 5.1 kernel , marking the entrance of the Windows NT core to the consumer market, to replace the aging Windows 9x branch. The initial release was met with considerable criticism , particularly in the area of security , leading to the release of three major Service Packs . Windows XP SP1 was released in September 2002, SP2 was released in August 2004 and SP3 was released in April 2008. Service Pack 2 provided significant improvements and encouraged widespread adoption of XP among both home and business users. Windows XP was one of Microsoft's longest-running flagship operating systems, beginning with the public release on October 25, 2001, for at least 5 years, and ending on January 30, 2007, when it was succeeded by Windows Vista.
Windows XP is available in a number of versions:
On April 25, 2003, Microsoft launched Windows Server 2003, a notable update to Windows 2000 Server encompassing many new security features, a new "Manage Your Server " wizard that simplifies configuring a machine for specific roles, and improved performance. It is based on the Windows NT 5.2 kernel. A few services not essential for server environments are disabled by default for stability reasons, most noticeable are the "Windows Audio" and "Themes" services; users have to enable them manually to get sound or the " Luna " look as per Windows XP. The hardware acceleration for display is also turned off by default, users have to turn the acceleration level up themselves if they trust the display card driver.
In December 2005, Microsoft released Windows Server 2003 R2, which is actually Windows Server 2003 with SP1 ( Service Pack 1), together with an add-on package.
Among the new features are a number of management features for branch offices, file serving, printing and company-wide identity integration.
Windows Server 2003 is available in six editions:
Windows Server 2003 R2, an update of Windows Server 2003, was released to manufacturing on December 6, 2005. It is distributed on two CDs, with one CD being the Windows Server 2003 SP1 CD. The other CD adds many optionally installable features for Windows Server 2003. The R2 update was released for all x86 and x64 versions, except Windows Server 2003 R2 Enterprise Edition, which was not released for Itanium.
On April 25, 2005, Microsoft released Windows XP Professional x64 Edition and Windows Server 2003, x64 Editions in Standard, Enterprise and Datacenter SKUs. Windows XP Professional x64 Edition is an edition of Windows XP for x86-64 personal computers. It is designed to use the expanded 64-bit memory address space provided by the x86–64 architecture. [ 32 ]
Windows XP Professional x64 Edition is based on the Windows Server 2003 codebase, with the server features removed and client features added. Both Windows Server 2003 x64 and Windows XP Professional x64 Edition use identical kernels. [ 33 ]
Windows XP Professional x64 Edition is not to be confused with Windows XP 64-bit Edition , as the latter was designed for Intel Itanium processors. [ 34 ] [ 35 ] During the initial development phases, Windows XP Professional x64 Edition was named Windows XP 64-Bit Edition for 64-Bit Extended Systems . [ 36 ]
In July 2006, Microsoft released a thin-client version of Windows XP Service Pack 2, called Windows Fundamentals for Legacy PCs (WinFLP). It is only available to Software Assurance customers. The aim of WinFLP is to give companies a viable upgrade option for older PCs that are running Windows 95, 98, and Me that will be supported with patches and updates for the next several years. Most user applications will typically be run on a remote machine using Terminal Services or Citrix .
While being visually the same as Windows XP, it has some differences. For example, if the screen has been set to 16 bit colors, the Windows 2000 recycle bin icon and some XP 16-bit icons will show. Paint and some games like Solitaire aren't present too.
Windows Home Server (code-named Q, Quattro) is a server product based on Windows Server 2003 , designed for consumer use. The system was announced on January 7, 2007, by Bill Gates . Windows Home Server can be configured and monitored using a console program that can be installed on a client PC. Such features as Media Sharing, local and remote drive backup and file duplication are all listed as features. The release of Windows Home Server Power Pack 3 added support for Windows 7 to Windows Home Server.
Windows Vista was released on November 30, 2006, to business customers—consumer versions followed on January 30, 2007. Windows Vista intended to have enhanced security by introducing a new restricted user mode called User Account Control , replacing the "administrator-by-default" philosophy of Windows XP. Vista was the target of much criticism and negative press, and in general was not well regarded, this was seen as leading to the relatively swift release of Windows 7.
One major difference between Vista and earlier versions of Windows, Windows 95 and later, was that the original start button was replaced with the Windows icon in a circle (called the Start Orb). Vista also featured new graphics features, the Windows Aero GUI , new applications (such as Windows Calendar , Windows DVD Maker and some new games including Chess , Mahjong , and Purble Place ), [ 37 ] Internet Explorer 7 , Windows Media Player 11 , and a large number of underlying architectural changes. Windows Vista had the version number NT 6.0. During its lifetime, Windows Vista had two service packs.
Windows Vista shipped in six editions : [ 38 ]
All editions (except Starter edition) were available in both 32-bit and 64-bit versions. The biggest advantage of the 64-bit version was breaking the 4 gigabyte memory barrier, which 32-bit computers cannot fully access.
Windows Server 2008, released on February 27, 2008, was originally known as Windows Server Codename "Longhorn". Windows Server 2008 built on the technological and security advances first introduced with Windows Vista, and was significantly more modular than its predecessor, Windows Server 2003.
Windows Server 2008 shipped in ten editions:
Windows 7 was released to manufacturing on July 22, 2009, and reached general retail availability on October 22, 2009. [ 39 ] [ 40 ] Since its release, Windows 7 had one service pack.
Some features of Windows 7 were faster booting , Device Stage, Windows PowerShell , less obtrusive User Account Control, multi-touch, and improved window management. The interface was renewed with a bigger taskbar and some improvements in the searching system and the Start menu. [ 41 ] Features included with Windows Vista and not in Windows 7 include the sidebar (although gadgets remain) and several programs that were removed in favor of downloading their Windows Live counterparts. Windows 7 met with positive reviews, which said the OS was faster and easier to use than Windows Vista.
Windows 7 shipped in six editions : [ 42 ]
In some countries in the European Union , there were other editions that lacked some features such as Windows Media Player, Windows Media Center and Internet Explorer—these editions were called names such as "Windows 7 N."
Microsoft focused on selling Windows 7 Home Premium and Professional. All editions, except the Starter edition, were available in both 32-bit and 64-bit versions.
Unlike the corresponding Vista editions, the Professional and Enterprise editions were supersets of the Home Premium edition.
At the Professional Developers Conference (PDC) 2008, Microsoft also announced Windows Server 2008 R2 , as the server variant of Windows 7 . Windows Server 2008 R2 shipped in 64-bit versions ( x64 and Itanium ) only.
In 2010, Microsoft released Windows Thin PC or WinTPC, which was a feature-and size-reduced locked-down version of Windows 7 expressly designed to turn older PCs into thin clients. WinTPC was available for software assurance customers and relied on cloud computing in a business network. Wireless operation is supported since WinTPC has full wireless stack integration, but wireless operation may not be as good as the operation on a wired connection. [ 43 ] [ 44 ]
Windows Home Server 2011 code named 'Vail' [ 45 ] was released on April 6, 2011. [ 46 ] Windows Home Server 2011 is built on the Windows Server 2008 R2 code base and removed the Drive Extender drive pooling technology in the original Windows Home Server release. [ 47 ] Windows Home Server 2011 is considered a "major release". [ 45 ] Its predecessor was built on Windows Server 2003 . WHS 2011 only supports x86-64 hardware.
Microsoft decided to discontinue Windows Home Server 2011 on July 5, 2012, while including its features into Windows Server 2012 Essentials. [ 48 ] Windows Home Server 2011 was supported until April 12, 2016. [ 49 ]
On June 1, 2011, Microsoft previewed Windows 8 at both Computex Taipei and the D9: All Things Digital conference in California. [ 50 ] [ 51 ] The first public preview of Windows Server 2012 was shown by Microsoft at the 2011 Microsoft Worldwide Partner Conference. [ 52 ] Windows 8 Release Preview and Windows Server 2012 Release Candidate were both released on May 31, 2012. [ 53 ] Product development on Windows 8 was completed on August 1, 2012, and it was released to manufacturing the same day. [ 54 ] Windows Server 2012 went on sale to the public on September 4, 2012. Windows 8 went on sale to the public on October 26, 2012. One edition, Windows RT , runs on some system-on-a-chip devices with mobile 32-bit ARM (ARMv7) processors . Windows 8 features a redesigned user interface, designed to make it easier for touchscreen users to use Windows. The interface introduced an updated Start menu known as the Start screen, and a new full-screen application platform. The desktop interface is also present for running windowed applications, although Windows RT will not run any desktop applications not included in the system. On the Building Windows 8 blog, it was announced that a computer running Windows 8 can boot up much faster than Windows 7. [ 55 ] New features also include USB 3.0 support, the Windows Store , the ability to run from USB drives with Windows To Go , and others.
Windows 8 is available in the following editions:
Microsoft ended support for Windows 8 on January 12, 2016.
Windows 8.1 and Windows Server 2012 R2 were released on October 17, 2013. Windows 8.1 is available as an update in the Windows Store for Windows 8 users only and also available to download for clean installation. [ 56 ] The update adds new options for resizing the live tiles on the Start screen. [ 57 ] Windows 8 was given the kernel number NT 6.2, with its successor 8.1 receiving the kernel number 6.3. Neither had any service packs, although many consider Windows 8.1 to be a service pack for Windows 8. However, Windows 8.1 received two main updates in 2014. [ 58 ] Both versions received some criticism due to the removal of the Start menu and some difficulties to perform tasks and commands.
Windows 8.1 is available in the same editions as its predecessor for users not running Windows 8.
Microsoft ended support on January 10, 2023.
Windows 10 was unveiled on September 30, 2014, as the successor for Windows 8, and was released on July 29, 2015. [ 59 ] It was distributed without charge to Windows 7 and 8.1 users for one year after release. A number of new features like Cortana , the Microsoft Edge web browser, the ability to view Windows Store apps as a window instead of fullscreen, the return of the Start menu, virtual desktops, revamped core apps, Continuum, and a unified Settings app were all features debuted in Windows 10. Like its successor, the operating system was announced as a service OS that would receive constant performance and stability updates. Unlike Windows 8, Windows 10 received mostly positive reviews, praising improvements of stability and practicality than its predecessor, however, it received some criticism due to mandatory update installation, privacy concerns and advertising-supported software tactics.
Although Microsoft claimed Windows 10 would be the last Windows version, eventually a new major release, Windows 11, was announced in 2021. That made Windows 10 last longer as Microsoft's flagship operating system than any other version of Windows, beginning with the public release on July 29, 2015, for six years, and ending on October 5, 2021, when Windows 11 was released. Windows 10 had received thirteen main updates.
Windows Server 2016 is a release of the Microsoft Windows Server operating system that was unveiled on September 30, 2014. Windows Server 2016 was officially released at Microsoft's Ignite Conference, September 26–30, 2016. [ 67 ] It is based on the Windows 10 Anniversary Update codebase.
Windows Server 2019 is a release of the Microsoft Windows Server operating system that was announced on March 20, 2018. The first Windows Insider preview version was released on the same day. It was released for general availability on October 2, 2018. Windows Server 2019 is based on the Windows 10 October 2018 Update codebase.
On October 6, 2018, distribution of Windows version 1809 (build 17763) was paused while Microsoft investigated an issue with user data being deleted during an in-place upgrade. It affected systems where a user profile folder (e.g. Documents, Music or Pictures) had been moved to another location, but data was left in the original location. As Windows Server 2019 is based on the Windows version 1809 codebase, it too was removed from distribution at the time, but was re-released on November 13, 2018. The software product life cycle for Server 2019 was reset in accordance with the new release date.
Windows Server 2022 was released on August 18, 2021. This is the first NT server version which does not share the build number with any of its client version counterpart, although its codename is 21H2, similar to the Windows 10 November 2021 Update.
Windows 11 is the latest release of Windows NT, and the successor to Windows 10. It was unveiled on June 24, 2021, and was released on October 5, [ 68 ] serving as a free upgrade to compatible Windows 10 devices. The system incorporates a renewed interface called "Mica", which includes translucent backgrounds, rounded edges and color combinations. The taskbar's icons are center aligned by default, while the Start menu replaces the "Live Tiles" with pinned apps and recommended apps and files. The MSN widget panel, the Microsoft Store, and the file browser, among other applications, have also been redesigned. However, some features and programs such as Cortana, Internet Explorer (replaced by Microsoft Edge as the default web browser) and Paint 3D were removed. Apps like 3D Viewer, Paint 3D, Skype and OneNote for Windows 10 can be downloaded from the Microsoft Store. [ 69 ] Beginning in 2021, Windows 11 included compatibility with Android applications, however, Microsoft has announced support for Android apps will end in March, 2025; the Amazon Appstore is included in Windows Subsystem for Android. Windows 11 received a positive reception from critics. While it was praised for its redesigned interface, and increased security and productivity, it was criticized for its high system requirements (which includes an installed TPM 2.0 chip, enabling the Secure Boot protocol, and UEFI firmware) and various UI changes and regressions (such as requiring a Microsoft account for first-time setup, preventing users from changing default browsers, and inconsistent dark theme) compared to Windows 10. [ 70 ] [ 71 ] [ 72 ]
Windows Server 2025 follows on Windows Server 2022 and was released on November 1, 2024. It is graphically based on Windows 11 and uses features like Hotpatching, among others. | https://en.wikipedia.org/wiki/Microsoft_Windows_version_history |
In statistical mechanics , a microstate is a specific configuration of a system that describes the precise positions and momenta of all the individual particles or components that make up the system. Each microstate has a certain probability of occurring during the course of the system's thermal fluctuations .
In contrast, the macrostate of a system refers to its macroscopic properties, such as its temperature , pressure , volume and density . [ 1 ] Treatments on statistical mechanics [ 2 ] [ 3 ] define a macrostate as follows: a particular set of values of energy, the number of particles, and the volume of an isolated thermodynamic system is said to specify a particular macrostate of it. In this description, microstates appear as different possible ways the system can achieve a particular macrostate.
A macrostate is characterized by a probability distribution of possible states across a certain statistical ensemble of all microstates. This distribution describes the probability of finding the system in a certain microstate. In the thermodynamic limit , the microstates visited by a macroscopic system during its fluctuations all have the same macroscopic properties.
In a quantum system , the microstate is simply the value of the wave function . [ 4 ]
Statistical mechanics links the empirical thermodynamic properties of a system to the statistical distribution of an ensemble of microstates. All macroscopic thermodynamic properties of a system may be calculated from the partition function that sums exp ( − E i / k B T ) {\displaystyle {\text{exp}}(-E_{i}/k_{\text{B}}T)} of all its microstates.
At any moment a system is distributed across an ensemble of Ω {\displaystyle \Omega } microstates, each labeled by i {\displaystyle i} , and having a probability of occupation p i {\displaystyle p_{i}} , and an energy E i {\displaystyle E_{i}} . If the microstates are quantum-mechanical in nature, then these microstates form a discrete set as defined by quantum statistical mechanics , and E i {\displaystyle E_{i}} is an energy level of the system.
The internal energy of the macrostate is the mean over all microstates of the system's energy U := ⟨ E ⟩ = ∑ i = 1 Ω p i E i {\displaystyle U\,:=\,\langle E\rangle \,=\,\sum \limits _{i=1}^{\Omega }p_{i}\,E_{i}}
This is a microscopic statement of the notion of energy associated with the first law of thermodynamics .
For the more general case of the canonical ensemble , the absolute entropy depends exclusively on the probabilities of the microstates and is defined as S := − k B ∑ i = 1 Ω p i ln ( p i ) {\displaystyle S\,:=\,-k_{\text{B}}\sum \limits _{i=1}^{\Omega }p_{i}\,\ln(p_{i})} where k B {\displaystyle k_{\text{B}}} is the Boltzmann constant . For the microcanonical ensemble , consisting of only those microstates with energy equal to the energy of the macrostate, this simplifies to S = k B ln Ω {\displaystyle S=k_{B}\,\ln \Omega } with the number of microstates Ω = 1 / p i {\displaystyle \Omega =1/p_{i}} . This form for entropy appears on Ludwig Boltzmann 's gravestone in Vienna.
The second law of thermodynamics describes how the entropy of an isolated system changes in time. The third law of thermodynamics is consistent with this definition, since zero entropy means that the macrostate of the system reduces to a single microstate.
Heat and work can be distinguished if we take the underlying quantum nature of the system into account.
For a closed system (no transfer of matter), heat in statistical mechanics is the energy transfer associated with a disordered, microscopic action on the system, associated with jumps in occupation numbers of the quantum energy levels of the system, without change in the values of the energy levels themselves. [ 2 ]
Work is the energy transfer associated with an ordered, macroscopic action on the system. If this action acts very slowly, then the adiabatic theorem of quantum mechanics implies that this will not cause jumps between energy levels of the system. In this case, the internal energy of the system only changes due to a change of the system's energy levels. [ 2 ]
The microscopic, quantum definitions of heat and work are the following:
δ W = ∑ i = 1 N p i d E i δ Q = ∑ i = 1 N E i d p i {\displaystyle {\begin{aligned}\delta W&=\sum _{i=1}^{N}p_{i}\,dE_{i}\\\delta Q&=\sum _{i=1}^{N}E_{i}\,dp_{i}\end{aligned}}} so that d U = δ W + δ Q . {\displaystyle ~dU=\delta W+\delta Q.}
The two above definitions of heat and work are among the few expressions of statistical mechanics where the thermodynamic quantities defined in the quantum case find no analogous definition in the classical limit. The reason is that classical microstates are not defined in relation to a precise associated quantum microstate, which means that when work changes the total energy available for distribution among the classical microstates of the system, the energy levels (so to speak) of the microstates do not follow this change.
The description of a classical system of F degrees of freedom may be stated in terms of a 2 F dimensional phase space , whose coordinate axes consist of the F generalized coordinates q i of the system, and its F generalized momenta p i . The microstate of such a system will be specified by a single point in the phase space. But for a system with a huge number of degrees of freedom its exact microstate usually is not important. So the phase space can be divided into cells of the size h 0 = Δ q i Δ p i , each treated as a microstate. Now the microstates are discrete and countable [ 5 ] and the internal energy U has no longer an exact value but is between U and U + δU , with δ U ≪ U {\textstyle \delta U\ll U} .
The number of microstates Ω that a closed system can occupy is proportional to its phase space volume: Ω ( U ) = 1 h 0 F ∫ 1 δ U ( H ( x ) − U ) ∏ i = 1 F d q i d p i {\displaystyle \Omega (U)={\frac {1}{h_{0}^{\mathcal {F}}}}\int \mathbf {1} _{\delta U}(H(x)-U)\prod _{i=1}^{\mathcal {F}}dq_{i}dp_{i}} where 1 δ U ( H ( x ) − U ) {\textstyle \mathbf {1} _{\delta U}(H(x)-U)} is an Indicator function . It is 1 if the Hamilton function H ( x ) at the point x = ( q , p ) in phase space is between U and U + δU and 0 if not. The constant 1 / h 0 F {\textstyle {1}/{h_{0}^{\mathcal {F}}}} makes Ω( U ) dimensionless. For an ideal gas is Ω ( U ) ∝ F U F 2 − 1 δ U {\displaystyle \Omega (U)\propto {\mathcal {F}}U^{{\frac {\mathcal {F}}{2}}-1}\delta U} . [ 6 ]
In this description, the particles are distinguishable. If the position and momentum of two particles are exchanged, the new state will be represented by a different point in phase space. In this case a single point will represent a microstate. If a subset of M particles are indistinguishable from each other, then the M! possible permutations or possible exchanges of these particles will be counted as part of a single microstate. The set of possible microstates are also reflected in the constraints upon the thermodynamic system.
For example, in the case of a simple gas of N particles with total energy U contained in a cube of volume V , in which a sample of the gas cannot be distinguished from any other sample by experimental means, a microstate will consist of the above-mentioned N! points in phase space, and the set of microstates will be constrained to have all position coordinates to lie inside the box, and the momenta to lie on a hyperspherical surface in momentum coordinates of radius U . If on the other hand, the system consists of a mixture of two different gases, samples of which can be distinguished from each other, say A and B , then the number of microstates is increased, since two points in which an A and B particle are exchanged in phase space are no longer part of the same microstate. Two particles that are identical may nevertheless be distinguishable based on, for example, their location. (See configurational entropy .) If the box contains identical particles, and is at equilibrium, and a partition is inserted, dividing the volume in half, particles in one box are now distinguishable from those in the second box. In phase space, the N /2 particles in each box are now restricted to a volume V /2, and their energy restricted to U /2, and the number of points describing a single microstate will change: the phase space description is not the same.
This has implications in both the Gibbs paradox and correct Boltzmann counting . With regard to Boltzmann counting, it is the multiplicity of points in phase space which effectively reduces the number of microstates and renders the entropy extensive. With regard to Gibbs paradox, the important result is that the increase in the number of microstates (and thus the increase in entropy) resulting from the insertion of the partition is exactly matched by the decrease in the number of microstates (and thus the decrease in entropy) resulting from the reduction in volume available to each particle, yielding a net entropy change of zero. | https://en.wikipedia.org/wiki/Microstate_(statistical_mechanics) |
Microstructurally stable nanocrystalline alloys are alloys that are designed to resist microstructural coarsening under various thermo-mechanical loading conditions. [ 1 ] [ 2 ]
Many applications of metal materials require that they can maintain their structure and strength despite very high temperatures. Efforts to prevent deformations from long term stress, referred to as creep, consist of manipulating alloys to reduce coarsening and migration of individual grains within the metal. [ 3 ]
The small size of individual metal grains provides high interfacial surface energy which is what prompts coarsening, the increase in grain size, and eventually metallic softening. [ 4 ] Nanocrystalline creep is considered to follow the Coble creep mechanism , the diffusion of atoms along grain boundaries at low stress levels and high temperatures. One method used to reduce coarsening, is by employing an alloy in which one component has good solubility with another. Since grain size decreases with high solute concentration, the rate of coarsening is slowed until inconsequential. [ 4 ]
In 2016, researchers at the Arizona State University and the United States Army Research Laboratory reported a microstructurally stable nanocrystalline alloy made of copper and 10% atomic tantalum (Cu–10 at% Ta). [ 3 ] [ 2 ] This microstructurally stable nanocrystalline alloy demonstrated high creep resistance under an applied stress and temperature ranges 0.85 to 1.2% of the shear modulus and .5-.64Tm respectively, the steady creep rates were consistently less than 10 −6 s −1 . [ 2 ]
This stability was credited to the mechanistic creep process and the alloy’s core–shell-type structures. The scientists determined that the copper alloy creep occurred in dislocation climb areas under levels of relatively larger stress, claiming that any diffusion creep occurring was negligible. The core–shell-type nanostructures prevented coarsening by securing grain boundaries, a mechanism known as Zener pinning . In these structures more interfacial bonding interactions were possible, increasing strength. Oxide-dispersion strengthened (ODS) ferritic alloys16 and molybdenum alloys17’s great strength and ductility were also credited to these nanostructures. [ 2 ]
In 2007, a nickel (Ni) and tungsten (W) nanocrystalline alloy was reported to have resistance to coarsening. Experimental data reported that the alloy coarsened to 28 nm from its original grain size of 20 nm after 30 minutes of exposure to heat of 600 degrees Celsius. This growth was then compared to the coarsening rate of an individual grain of Ni placed in heat of 300 degrees Celsius for 30 minutes. [ 4 ]
In 2012, a tungsten (W) and 20% titanium (Ti) nanocrystalline alloy after a week of exposure to heat of 1100 degrees Celsius in an argon atmosphere was claimed by the researchers to have displayed no change in grain size from the initial 20 nm. Meanwhile, the unalloyed W under the same conditions exhibited a final size on the micrometer scale. [ 5 ] Another reviewer describes the coarsening of the W-Ti alloy to be a 2 nm size increase from the original 22 nm. [ 4 ] The authors attribute the microstructural stability to a complex chemical arrangement. [ 5 ] [ 4 ] The nanocrystalline metallic grains were made via a high-energy ball mill method. | https://en.wikipedia.org/wiki/Microstructurally_stable_nanocrystalline_alloys |
Microstructure is the very small scale structure of a material, defined as the structure of a prepared surface of material as revealed by an optical microscope above 25× magnification. [ 1 ] The microstructure of a material (such as metals , polymers , ceramics or composites ) can strongly influence physical properties such as strength, toughness, ductility, hardness, corrosion resistance, high/low temperature behaviour or wear resistance. These properties in turn govern the application of these materials in industrial practice.
Microstructure at scales smaller than can be viewed with optical microscopes is often called nanostructure , while the structure in which individual atoms are arranged is known as crystal structure . The nanostructure of biological specimens is referred to as ultrastructure . A microstructure's influence on the mechanical and physical properties of a material is primarily governed by the different defects present or absent of the structure. These defects can take many forms but the primary ones are the pores. Even if those pores play a very important role in the definition of the characteristics of a material, so does its composition. In fact, for many materials, different phases can exist at the same time. These phases have different properties and if managed correctly, can prevent the fracture of the material.
The concept of microstructure is observable in macrostructural features in commonplace objects. Galvanized steel, such as the casing of a lamp post or road divider, exhibits a non-uniformly colored patchwork of interlocking polygons of different shades of grey or silver. Each polygon is a single crystal of zinc adhering to the surface of the steel beneath. Zinc and lead are two common metals which form large crystals (grains) visible to the naked eye. The atoms in each grain are organized into one of seven 3d stacking arrangements or crystal lattices (cubic, tetrahedral, hexagonal, monoclinic, triclinic, rhombohedral and orthorhombic). The direction of alignment of the matrices differ between adjacent crystals, leading to variance in the reflectivity of each presented face of the interlocked grains on the galvanized surface. The average grain size can be controlled by processing conditions and composition, and most alloys consist of much smaller grains not visible to the naked eye. This is to increase the strength of the material (see Hall-Petch strengthening ).
To quantify microstructural features, both morphological and material property must be characterized. Image processing is a robust technique for determination of morphological features such as volume fraction, [ 2 ] inclusion morphology, [ 3 ] void and crystal orientations. To acquire micrographs, optical as well as electron microscopy are commonly used.
To determine material property, Nanoindentation is a robust technique for determination of properties in micron and submicron level for which conventional testing are not feasible. Conventional mechanical testing such as tensile testing or dynamic mechanical analysis (DMA) can only return macroscopic properties without any indication of microstructural properties. However, nanoindentation can be used for determination of local microstructural properties of homogeneous as well as heterogeneous materials. [ 4 ] Microstructures can also be characterized using high-order statistical models through which a set of complicated statistical properties are extracted from the images. Then, these properties can be used to produce various other stochastic models. [ 5 ] [ 6 ] [ 7 ]
Microstructure generation is also known as stochastic microstructure reconstruction.
Computer-simulated microstructures are generated to replicate the microstructural features of actual microstructures. Such microstructures are referred to as synthetic microstructures. Synthetic microstructures are used to investigate what microstructural feature is important for a given property. To ensure statistical equivalence between generated and actual microstructures, microstructures are modified after generation to match the statistics of an actual microstructure. Such procedure enables generation of theoretically infinite number of computer simulated microstructures that are statistically the same (have the same statistics) but stochastically different (have different configurations). [ 3 ] [ 8 ]
A pore in a microstructure, unless desired, is a disadvantage for the properties. In fact, in nearly all of the materials, a pore will be the starting point for the rupture of the material. It is the initiation point for the cracks. Furthermore, a pore is usually quite hard to get rid of. Those techniques described later involve a high temperature process. However, even those processes can sometimes make the pore even bigger. Pores with large coordination number (surrounded by many particles) tend to grow during the thermal process. This is caused by the thermal energy being converted to a driving force for the growth of the particles which will induce the growth of the pore as the high coordination number prohibits the growth towards the pore.
For many materials, it can be seen from their phase diagram that multiple phases can exist at the same time. Those different phases might exhibit different crystal structure, thus exhibiting different mechanical properties. [ 9 ] Furthermore, these different phases also exhibit a different microstructure (grain size, orientation). [ 10 ] This can also improve some mechanical properties as crack deflection can occur, thus pushing the ultimate breakdown further as it creates a more tortuous crack path in the coarser microstructure. [ 11 ]
In some cases, simply changing the way the material is processed can influence the microstructure. An example is the titanium alloy TiAl6V4. [ 12 ] Its microstructure and mechanical properties are enhanced using SLM (selective laser melting) which is a 3D printing technique using powder and melting the particles together using high powered laser. [ 13 ] Other conventional techniques for improving the microstructure are thermal processes. [ 14 ] Those processes rely in the principle that an increase in temperature will induce the reduction or annihilation of pores. [ 15 ] Hot isostatic pressing (HIP) is a manufacturing process, used to reduce the porosity of metals and increase the density of many ceramic materials. This improves the material's mechanical properties and workability. [ 16 ] The HIP process exposes the desired material to an isostatic gas pressure as well as high temperature in a sealed vessel (high pressure). The gas used during this process is mostly Argon. The gas needs to be chemically inert so that no reaction occurs between it and the sample. The pressure is achieved by simply applying heat to the hermetically sealed vessel. However, some systems also associate gas pumping to the process to achieve the required pressure level. The pressure applied on the materials is equal and comes from all directions (hence the term “isostatic”). [ 17 ] When castings are treated with HIP, the simultaneous application of heat and pressure eliminates internal voids and microporosity through a combination of plastic deformation, creep, and diffusion bonding; this process improves fatigue resistance of the component. [ 18 ] | https://en.wikipedia.org/wiki/Microstructure |
Microtechnique is an aggregate of methods used to prepare micro-objects for studying. [ 1 ] It is currently being employed in many fields in life science. Two well-known branches of microtechnique are botanical (plant) microtechnique and zoological (animal) microtechnique.
With respect to both plant microtechnique and animal microtechnique, four types of methods are commonly used, which are whole mounts, smears, squashes, and sections, in recent micro experiments. [ 2 ] Plant microtechnique contains direct macroscopic examinations, freehand sections, clearing, maceration, embedding, and staining. [ 3 ] Moreover, three preparation ways used in zoological micro observations are paraffin method, celloidin method, and freezing method. [ 4 ]
The early development of microtechnique in botany is closely related to that in zoology. Zoological and botanical discoveries are adopted by both zoologists and botanists. [ 5 ]
The field of microtechnique lasted from at the end of the 1930s when the principle of dry preparation emerged. [ 6 ] The early development of microtechnique in botany is closely related to that in zoology. Zoological and botanical discoveries are adopted by both zoologists and botanists. [ 5 ] Since Hooke discovered cells, microtechnique had also developed with the emergence of early microscopes. Microtechnique then had advanced over the period of 1800–1875. [ 6 ] After 1875, modern micro methods have emerged. In recent years, both traditional methods and modern microtechnique have been in use in many experiments. [ 3 ]
Some general microtechnique can be used in both plant and animal micro observation. Whole mounts, smears, squashes, and sections are four commonly used methods when preparing plant and animal specimens for specific purposes. [ 2 ]
Whole mounts are usually used when observers need to use a whole organism or do some detailed research on specific organ structure. [ 7 ] This method requires objects in which moisture can be removed, like seeds and micro fossils. [ 2 ]
According to different purposes, Whole-mounts can be divided into three categories, Temporary whole mounts, Semi-permanent whole mounts, and permanent whole mounts. Temporary whole mounts are usually used for teaching activities in class. [ 8 ] Semi-permanent whole mounts are prepared for longer using time, which is no more than fourteen days. In this preparation, Canada balsam is used to seal the specimens, and this method is used to observe unicellular and colonial algae, fungal spores, mosses protonemata, and prothalli. The third way is a permanent whole mount. [ 8 ] Two methods are usually used, which are hygrobutol method and glycerine - xylol method. [ 9 ]
Smears is an easy way for preparing slices. This method is used in many laboratories. [ 10 ] Smears can be employed when making slide specimens by spreading liquid or semi-liquid materials or lose tissues and cells of animals and plants evenly on the slide. [ 10 ] The steps and requirements for the application of the smear method are as follows: first, smear. When the solid material is smeared, the material should be placed on the glass slide and wiped away, then use the blade to press the material on one side. [ 11 ] The cells should be pressed out and distributed evenly on the glass slide in a thin layer, such as the anther smeared. [ 10 ]
Squashes are methods, in which objects are crushed with force. This method is suitable for preparing both transparent and tender tissues. [ 12 ] When preparing squashes slides, specimens are supposed to be thin and transparent so that objects can be observed clearly under microscopes. [ 12 ]
This technique is to place the material on the glass slide and remove it with the scalpel or to dissect needle, then add a drop of dye solution. [ 2 ] After these steps, apply the second slide to cover the initial slide and apply pressure evenly to break the material and disperse the cells. [ 12 ] Furthermore, another possible way can be used to prepare slides. The specimens can also be extruded between the cover slide and the slide with equal pressure. [ 12 ]
Sections are known as thin slices need to be tested in all studies of cellular structures. [ 13 ] This technique can be used for the preparation of tissue of animals and plants. [ 14 ] For using under optical microscopy, the thickness of the material should be between above 2 and 25 micrometers. When observing under electron microscopy, sections should be from 20 to 30 nanometers. [ 2 ] Microtome can be used in sectioning of sufficiently thin slices. If the objects cannot satisfy the requirement of thickness, materials are required to be dehydrated using alcohol before section. [ 12 ] Three commonly used sectioning method are freehand section technique, paraffin method, and celloidin method.
Botanical microtechnique is an aggregate of methods providing micro visualization of gene and gene product in an entire plant. [ 15 ] Plant microtechnique is also a study providing valuable experimental information. [ 3 ] Plant microtechnique involves classical methods developed over a hundred years ago and new methods developed to expand our research scope and depth in botanical micro studies. [ 15 ] Both traditional and new micro technique is useful for experimental research, and some will have a significant influence on further study. [ 3 ] Different methods are used to prepare plant specimens, including direct macroscopic examinations, freehand sections, [ 16 ] clearing, maceration, embedding, and staining.
The direct micro examination is a simple way prepared for observing micro-objects. Also, this method is useful to observe whether the mold grows on the surface of the specimens. This can be an initial step of the micro experiment. [ 17 ]
Freehand slicing is a method of making thin slices of fresh or fixed experimental materials with a hand-held blade . [ 18 ] Freehand slicing refers to the method of directly cutting fresh or fixed materials (generally plants with a low degree of lignification) into thin slices without special instruments or special chemical reagents. [ 16 ]
Clearing technique provides translucent slides via removing part of cytoplasmic content and then applying high refractive index reagents to process the tissues. [ 2 ] This method is suitable for preparing whole mount slides. The clearing is a procedure of using clearing reagents for removal of alcohol and makes tissue translucent. [ 19 ] Xylene is the most popular clearing agent. [ 20 ] [ 21 ]
Macerating tissues is the process of separating the constituent cells of tissues. This method enables observers to study the whole cell in third-dimensional detail. [ 8 ] Chemical maceration method means the using chemicals to process organs or part to soften tissue and dissolving the cells so that different cell can be identified. [ 8 ]
Embedding technique is a medium stage when doing a sectioning process. [ 13 ] When preparing specimens, it is difficult to make uniform slices since the tissue is soft. [ 22 ] Therefore, it is necessary to soak the tissue with a certain substance to harden the whole tissue, to facilitate the slicing. This process is called embedding. [ 22 ] The substance used to embed tissue is embedding media, which is chosen depends on the category of the microscope, category of the micro tome, and category of tissue. [ 23 ] Paraffin wax, whose melting point is from 56 to 62°C, is commonly used for embedding. [ 22 ]
Since few plant tissues have a color, there is little chromatically difference between plant tissues makes it difficult to differentiate botanical structure. [ 24 ] Material is usually dyed before installation. This process is called staining, which can be used to prepare botanical specimens so that it is possible to distinguish one part of the sample from another in terms of color. [ 2 ] Acid dyes can be used when staining micro slides, for example, acid dyes are in use when coloring nuclei and other cellular components are stained using alkaline. [ 2 ] There are also staining machine used for staining, which allows tissue to be stained automatically. [ 25 ]
The zoological microtechnique is the art of the preparation for microscopic animal observation. Although many microtechniques can be used in both plant and animal micro experiments. Some methods may differ from itself when employed in different field. Three commonly used preparation ways used in zoological micro observations can be concluded as paraffin method, celloidin method, freezing method, and miscellaneous techniques. [ 4 ]
This process usually consists of steps of infiltration, embedding, sectioning, affixing and processing the sections. [ 26 ] Followed by the initial stage, fixation, the next step is dehydration, which removes the water in the tissue using alcohol. [ 27 ] Then the tissue can be infiltrated and embedded with wax. A tissue specimen can keep for several years after finishing embedding this tissue into the wax. [ 27 ] Paraffin wax , which is soft and colorless, is the most commonly used reagent. [ 28 ]
Sectioning a tissue can use either the micro tome knife or the razor blade as the cutting blade. [ 4 ]
The micro tome knife is used for handling sectioning. It is necessary to use a micro tome knife when preparing sections less than 1/1000 micrometers. [ 29 ] When using such a knife, the operators must be extremely careful. This instrument is impractical sometimes, so using the razor blade for general work to prepare sections above 9 microns (1 micron equals 1/1000 micrometers). [ 29 ] Furthermore, the razor blade works better than the micro tome knife when requiring thick sections with no less than 20 microns. [ 4 ]
After sectioning, the prepared slices are affixed on slides. There are two commonly used affixatives, Haupt's and Mayer's. [ 30 ] Haupt's affixative contains 100 ccs (cubic centimeter) distilled water, 1gm gelatin, 2 gm phenol crystals, 15 cc glycerine. Mayer's affixative is consist of 5 cc egg albumen, 50 cc glycerine, 1 gm sodium salicylate. [ 31 ] The general steps of affixing paraffin sections can be concluded as 1. Clean the required slides, 2. Mark the cleaned slides, 3. Drop affixative on each slide, 4. Put on another slide, 5. Spread the affixative, 6. Drop floating medium, 7. Divide the paraffin into required length, 8. Transfer the sections, 9. Add more floating medium if incomplete floating occurs, 10. Rise the temperature, 11. Remove slides and redundant floating medium, 12, drying the section. [ 4 ]
Processing paraffin sections include 1. Deparaffination, 2. Removing the deparaffing solution, 3. Hydration, 4. Staining, 5. Dehydration, 6. Dealcoholisation and clearing, 7. Mounting the cover slide. [ 4 ]
Celloidin technique is the procedure of embedding a specimen in celloidin. [ 32 ] This method can be used for embedding large, hard objects. [ 33 ] Celloidin is a digestive fiber, which is flammable, and it is soluble in acetone, clove oil, and the mixture of anhydrous alcohol and ether. [ 34 ] Celloidin will turn into white emulsion turbid liquid when it meets water, so it is required to use a dry container to contain celloidin. [ 33 ]
The method of celloidin slicing is to fix and dehydrate the tissue, then treat it with the anhydrous alcohol-ether mixture. After this step, to impregnate, embed and slice the tissue with celloidin. [ 35 ] Moreover, this slicing method can slice large tissues and has the advantage that its heat allows the tissues does not shrink. However, this technique contains some shortcomings. For instance, the slices cannot be sliced very thin (more than 20 microns), and impregnation with celloidin is time-consuming. [ 36 ]
Freezing technique is the most commonly used sectioning method. [ 37 ] This method can preserve the immune activity of various antigens well. Both fresh tissue and fixed tissue can be frozen. Moreover, it is also a technique used for freezing sections of either fresh or fixed plant tissues. [ 38 ]
During the freezing procedure, the water in tissues is easy to form ice crystals, which often affects the antigen localization. [ 37 ] It is generally believed that when ice crystals are small, the effect is small, and when ice crystals are large, the damage to the tissue structure is large, and the above phenomenon is more likely to occur in tissues with more moisture components. [ 39 ] The size of an ice crystal is directly proportional to its growth rate and inversely proportional to the nucleation rate (formation rate), that is, the larger the number of ice crystal formation, the smaller it is, and the more serious the impact on the structure. [ 40 ] Therefore, the number of ice crystals should be minimized. The freezing method allows sectioning tissues rapidly and biopsy without using reagents. This procedure should be rapidly in case of the form of ice crystal. [ 39 ] | https://en.wikipedia.org/wiki/Microtechnique |
Microtechnology is technology whose features have dimensions of the order of one micrometre (one millionth of a metre, or 10 −6 metre, or 1μm). [ 1 ] It focuses on physical and chemical processes as well as the production or manipulation of structures with one-micrometre magnitude. [ 2 ]
Around 1970, scientists learned that by arraying large numbers of microscopic transistors on a single chip, microelectronic circuits could be built that dramatically improved performance, functionality, and reliability, all while reducing cost and increasing volume. This development led to the Information Revolution .
More recently, scientists have learned that not only electrical devices, but also mechanical devices, may be miniaturized and batch-fabricated, promising the same benefits to the mechanical world as integrated circuit technology has given to the electrical world. While electronics now provide the ‘brains’ for today's advanced systems and products, micro-mechanical devices can provide the sensors and actuators — the eyes and ears, hands and feet — which interface to the outside world.
Today, micromechanical devices are the key components in a wide range of products such as automobile airbags , ink-jet printers, blood pressure monitors , and projection display systems. It seems clear that in the not-too-distant future these devices will be as pervasive as electronics. The process has also become more precise, driving the dimensions of the technology down to sub-micrometer range as demonstrated in the case of advanced microelectric circuits that reached below 20 nm. [ 3 ]
The term MEMS , for Micro Electro Mechanical Systems, was coined in the 1980s to describe new, sophisticated mechanical systems on a chip, such as micro electric motors, resonators, gears, and so on. Today, the term MEMS in practice is used to refer to any microscopic device with a mechanical function, which can be fabricated in a batch process (for example, an array of microscopic gears fabricated on a microchip would be considered a MEMS device but a tiny laser-machined stent or watch component would not). In Europe, the term MST for Micro System Technology is preferred, and in Japan MEMS are simply referred to as "micromachines". The distinctions in these terms are relatively minor and are often used interchangeably.
Though MEMS processes are generally classified into a number of categories – such as surface machining , bulk machining, LIGA , and EFAB – there are indeed thousands of different MEMS processes. Some produce fairly simple geometries, while others offer more complex 3-D geometries and more versatility. A company making accelerometers for airbags would need a completely different design and process to produce an accelerometer for inertial navigation. Changing from an accelerometer to another inertial device such as a gyroscope requires an even greater change in design and process, and most likely a completely different fabrication facility and engineering team.
MEMS technology has generated a tremendous amount of excitement, due to the vast range of important applications where MEMS can offer previously unattainable performance and reliability standards. In an age where everything must be smaller, faster, and cheaper, MEMS offers a compelling solution. MEMS have already had a profound impact on certain applications such as automotive sensors and inkjet printers. The emerging MEMS industry is already a multibillion-dollar market. It is expected to grow rapidly and become one of the major industries of the 21st century. Cahners In-Stat Group has projected sales of MEMS to reach $12B by 2005. The European NEXUS group projects even larger revenues, using a more inclusive definition of MEMS.
Microtechnology is often constructed using photolithography . Lightwaves are focused through a mask onto a surface. They solidify a chemical film. The soft, unexposed parts of the film are washed away. Then acid etches away the material not protected.
Microtechnology's most famous success is the integrated circuit . It has also been used to construct micromachinery . As an offshoot of researchers attempting to further miniaturize microtechnology, nanotechnology emerged in the 1980s, particularly after the invention of new microscopy techniques. [ 4 ] These produced materials and structures that have 1-100 nm in dimensions. [ 4 ]
The following items have been constructed on a scale of 1 micrometre using photolithography: | https://en.wikipedia.org/wiki/Microtechnology |
Microtentacles are microtubule -based membrane protrusions that occur in detached cells. They were discovered by scientists studying metastatic breast cancer cells at the University of Maryland, Baltimore .
These novel structures are distinct from classical actin based extensions of adherent cells, persist for days in breast tumor lines that are resistant to apoptosis, and aid in the reattachment to matrix or cell monolayers.
The formation of microtentacles (McTNs) in detached or circulating tumor cells may promote seeding of bloodborne metastatic disease. | https://en.wikipedia.org/wiki/Microtentacle |
Microthermal analysis is a materials characterization technique which combines the thermal analysis principles of differential scanning calorimetry (DSC) with the high spatial resolution of scanning probe microscopy . The instrument consists of a thermal probe, a fine platinum/rhodium alloy wire (5 micro meter in diameter) coated by a sheath of silver ( Wollaston wire ). The wire is bent into a V-shape, and the silver sheath is etched away to form a fine-pointed tip. The probe acts as both the heater as well as a temperature sensor. The probe is attached to a conventional scanning probe microscope and can be scanned over the sample surface to resolve the thermal behavior of the sample spatially.
This technique has been widely used for localized thermal analysis, where the probe is heated rapidly to avoid thermal diffusion through the sample and the response of the substance in immediate proximity to the tip is measured as a function of temperature. [ 1 ] Micro-thermal analysis was launched
commercially in March 1998. [ 2 ]
Microthermal analysis has been extended to higher spatial resolution to nanothermal analysis , which uses microfabricated self-heating silicon cantilevers to probe thermomechanical properties of materials with sub-100 nm spatial resolution. [ 3 ] | https://en.wikipedia.org/wiki/Microthermal_analysis |
Microthermoforming is the abbreviation for microscopic or microscale thermoforming , or, more precisely, for thermoforming of microproducts or microstructure products. Microstructure products means products that have structures in the micrometre range and have their technical function provided by the shape of the microstructure [1]. Thermoforming [2] in turn means shaping of heated and therefore softened semi finished products in the form of thermoplastic polymer films or plates with their edges fixed by three-dimensional stretching. Shaping is carried out mainly by forming the films or plates into female moulds (negative forming) or over male moulds (positive forming). While the other polymer microreplication processes such as micro injection moulding or (vacuum) hot embossing are primary forming processes where forming occurs already in a molten, liquid phase of the heated polymer material, microthermoforming is a secondary forming process where forming occurs in a strongly softened, but still solid phase of the heated polymer.
Moulds for polymer microreplication in general and in particular for microthermoforming can be fabricated by various methods such as mechanical micromachining, lithographic based methods in combination with electroplating (see also the so-called ' LIGA ' process) and wet or dry etching. And they can be fabricated of various materials such as metal, silicon and glass.
For several years now, at Karlsruhe Institute of Technology (KIT), a pressure or high pressure (thermo)forming process is used to fabricate film microchips for capillary electrophoresis (CE) [3–5] and for three-dimensional cell cultivation [6–8]. The process is derived from the macroscopic trapped sheet forming process [2]. This is a simple variation of vacuum or pressure forming without prestretching, i.e. a single stage forming, into a female mould with heating of the plastic sheet using a contact heating plate inside the forming station. The forming air is supplied via through holes in the heating plate. Still in a laboratory scale process, diverse thermoplastic films also from biodegradable polymers such as polycaprolactone (PCL) with thicknesses typically between 20 and 100 μm are thermoformed. This is performed with gas pressures up to 5 MPa into mechanically micromachined cavities of plate shaped micromoulds from brass.
First examples of processes coming near to something that could be called 'microthermoforming' originate from the second half of the nineties. So, in 1993, dome shaped polymer microstructures for use in electrical membrane switches were fabricated [9]. This was done between a mating upper and lower metal emboss die with a concave and a convex detail, respectively, first in a hot, then in a second cold press. And in 1999, corrugated sheet like polymer microstructures for use e.g. in electrostatic actuators were fabricated [10]. This was also done between heated tools and counter tools, namely in discontinuous processes between stamps or in continuous processes between rollers. Partly, the counter tool was a soft one in the form of a thicker, unpatterned film or plate made from an easily deformable, e.g. elastomeric material which is able to assume the shape of the hard, metallic tool. In 2006, at the School of Polymer, Textile and Fiber Engineering (PTFE) of the Georgia Institute of Technology (GIT), the same technology approach was used to fabricate similar corrugated sheet like structures in a so-called 'rubber-assisted hot embossing process' [11].
The microthermoforming process including its products can have all the advantageous properties of the powerful macroscopic production process. Moreover, the thermoformed microparts have additional, specific properties appearing only in microscale dimensions and resulting from their unusual morphology. Thermoformed e.g. microfluidic structures have free standing microcavities such as channels and reservoirs and they are thin walled partly in the range of a few micrometers. Specific properties of thermoformed microparts are, amongst others, their high flexibility, their small volume and mass, their low thermal resistance and heat capacity, and their low light absorbance and background fluorescence. Morphology and properties of these microparts now can result in improved or even new, so far unthought of applications.
Compared to the other microreplication processes, in microthermoforming, modifications of the film to be formed remain preserved beyond the forming step due to the already mentioned material coherence during this secondary forming process. This enables surface and bulk modification and functionalisation of the three-dimensionally formed films or membranes, namely as highly resolved micro- and nanopatterns, and all side, i.e. on hardly accessible side walls and even behind undercuts . Thus, e.g. thermoformed chips for three-dimensional cell cultivation can be provided with pores, cell adhesion patterns [6–8], surface topologies and electrodes [12].
Future application fields for microthermoforming are expected to be | https://en.wikipedia.org/wiki/Microthermoforming |
Microtox is an in vitro testing system which uses bioluminescent bacteria ( Allivibrio fischeri , formerly known as Vibrio fischeri ) to detect toxic substances in different substrates such as water, air, soils and sediments . [ 1 ] Allivibrio fischeri are non-pathogenic, marine, bacteria that luminesce as a natural part of their metabolism . [ 2 ] When exposed to a toxic substance, the respiratory process of the bacteria is disrupted, reducing light output. [ 2 ] Allivibrio fischeri have demonstrated high sensitivity across a wide variety of toxic substances. Response to toxicity is observed as a change in luminescence, which is a by-product of cellular respiration . [ 2 ] This change can be used to calculate a percent inhibition of Allivibrio fischeri that directly correlates to toxicity. [ 2 ]
Microtox was developed by Azur Environmental (formerly Microbics Corporation) in 1979 as a cost-effective alternative to toxicity tests available at the time. [ 3 ] [ 4 ] Prior to Microtox, the majority of toxicity tests available for water specifically focused on fish and daphnids. [ 3 ] [ 4 ] Since its inception, Microtox has become a standard method for testing the toxicity of water as well as other substrates such as soils and sediments. [ 3 ] [ 5 ] [ 6 ]
In recent years the Microtox technology and name have undergone various different ownerships. In 2011, Microtox and related technologies was acquired by Modern Water from Strategic Diagnostics Incorporated (SDIX) for approximately $4.5 million. [ 7 ] Prior to SDIX, Microtox was owned by its original developers Azur Environmental. [ 3 ]
Microtox utilizes a bioluminescent bacteria ( Allivibrio fischeri ) to determine the toxicity of a particular substance and/or substrate. [ 3 ] [ 5 ] During cellular metabolism, these bacteria naturally emit light as a part of cellular respiration , which can be measured as luminescence. [ 3 ] When exposed to toxic substances, a decrease in luminescence can be observed and percent change in luminescence can be directly correlated to toxicity. [ 4 ] Allivibrio fischeri were specifically chosen, as these bacteria could be preserved by freeze-drying to increase shelf life and use. [ 3 ] Both solid phase (soils and sediment) and aqueous acute toxicity testing (described below) can be conducted using this technology. [ 6 ]
The Microtox Model 500 is a laboratory-based photometer that measures acute toxicity . This analyser is a temperature-controlled, self-calibrating biosensor measuring system that uses the bioluminescence of Allivibrio fischeri to determine the toxicity of contaminated water, or elutriates of contaminated soils and sediments. [ 8 ]
Microtox Continuous Toxicity Monitor (CTM) is a site-specific Microtox analyser that continuously measures the toxicity of a water source and provides results instantly. This fully automatic analyser has a broad detection range that can identify several thousand contaminants simultaneously whether or not there is knowledge of the source of contamination. This device has the ability to run continuously for up to 4 weeks, and is easy to operate and maintain. [ 9 ]
The DeltaTox II is a portable instrument that can be used to conduct acute toxicity and adenosine triphosphate (ATP) testing. Also known as the portable version of the Microtox Model 500, this device provides simple testing, uses small sample sizes, and is a cost-effective approach to analyzing water samples. This sensitive and rapid testing analyser has the ability to detect microbial contamination, as well as more than 2,700 different chemicals. [ 10 ]
The shelf life for the Acute Reagent is two years and for the solutions is three years when stored properly. [ 11 ]
Microtox Acute Reagent is a freeze-dried culture of Allivibrio fischeri that is reconstituted prior to testing. It is recommended that the reagent be used within three hours of reconstitution. The sensitivity of the reagent may become altered after the recommended time period. [ 11 ]
Microtox Osmotic Adjustment Solution (MOAS) is a nontoxic solution that is made up of 22% sodium chloride ( NaCl ) and ultra-pure water. This solution is added to a sample to adjust the osmotic pressure to approximately 2% NaCl . [ 11 ]
Reconstitution Solution consists of specially prepared, nontoxic ultra-pure water. [ 11 ]
Diluent is a nontoxic solution that is made up of 2% NaCl in ultra-pure water. This solution is used for diluting the sample and the reagent , and also provides osmotic protection that is required by Allivibrio fischeri . [ 11 ] [ 12 ]
Microtox can be applied to a variety of matrices including drinking water , stormwater runoff , effluent , industrial discharges, soils and sediments. [ 5 ] Most samples do not require special preparation before testing besides adjusting the salinity to 2%. [ 3 ] However, samples that have certain characteristics, such as high turbidity levels, may require special preparation. [ 3 ] If samples require a salinity adjustment to lower the salinity , this can be accomplished by adding an appropriate amount of Microtox Osmotic Adjusting Solution to dilute the sample. For example, adding 0.1 mL of MOAS to 1 mL of sample would result in a dilution of 90.9% of the original concentration. [ 3 ] If a greater salinity is required, this can be accomplished by dissolving solid sodium chloride in the sample to achieve a final salinity of 2% for the protection of Allivibrio fischeri . [ 3 ] Highly turbid samples that contain particulate matter will be required to settle before the test can be conducted. [ 3 ] Particulate matter in the sample can interfere with bioluminescence by absorbing light and give misleading test results. Interference of luminescence can also occur with samples which are highly colored (particularly red, brown or black). [ 3 ] It may be necessary to centrifuge samples to obtain an acceptable clarity for the test. [ 3 ] If samples contain chlorine , this may alter the toxicity to Allivibrio fischeri and also give misleading results. The samples can be de-chlorinated using a sodium thiosulphate and deionized water solution that does not affect test results. [ 3 ] Ideally, the pH of samples should not be modified since it is preferable to test each sample at the original pH level. However, if it is necessary to adjust the pH this should be done by adding either sodium hydroxide solution or hydrochloric acid to the sample. [ 3 ]
Unlike water samples, soil and sediment samples are not homogeneous. [ 13 ] As a result, it is difficult to obtain representative samples from such matrices. Toxic substances are likely to bind to particulate matter, and the extent to which toxic materials bind depends on the composition of the particles. For example, smaller particles such as clay tend to tightly bind to chemicals, acting like ion exchange resins . [ 12 ] [ 13 ] Microtox tests for sediment and soil differ in the way the matrix is prepared for contact with Allivibrio fischeri . To obtain a representative soil or sediment sample, it is necessary to conduct an elutriate test. Sediment elutriates can be prepared through extraction with either distilled water, saline water, or an organic solvent such as methylene chloride , or hexane . [ 12 ] To run an elutriate test a soil sample is mixed with an extractant for a period of time, then allowed to settle and a sample is taken from the extract. If particulate matter is in the sample that was collected, it may be necessary to centrifuge the sample for optimal clarity. Additionally, the pore water of sediments can be collected by centrifugation and tested without extraction. [ 12 ]
There are five major Microtox tests including the Basic Test, the 100% Test, the Solid Phase Test, the Comparison Test, and the Inhibition Test. Of these five tests, three are used for sediment and soil testing including the Basic Test, the 100% Test and the Solid-Phase Test. [ 12 ] All of these versions follow the same general method of reconstituting the Allivibrio fischeri reagent in the Reconstitution Solution. Corrections are made for salinity and particulate matter, then the bacteria are exposed to the sample solution depending on the methods of the particular test. The light output of the bacteria is measured using a photometer after five and 15 minutes from exposing the bacteria to the samples. [ 12 ] The light measured directly correlates to the toxicity of the sample, producing data that allows for the calculation of EC50 or IC50s, or other ECxx and ICxx values. [ 14 ]
Acute Toxicity Basic Test is a procedure that measures the relative acute toxicity of a sample. This test is the best protocol for testing samples of unknown toxicity, a high level of toxicity, or when the test results are required to provide the highest confidence and precision. This test consists of two controls and eight sample dilutions in duplicate. [ 14 ]
Acute Toxicity 100% Test is a procedure that tests the sample at 100% sample concentration and as a result includes adding reagent solution directly to the sample. [ 15 ] This test is used for samples that are expected to have a low level of toxicity and is generally used as an environmental screening tool. Compared to the Basic Test it is more sensitive to operator technique, and as a result may be less precise. [ 12 ]
Acute Toxicity Solid-Phase Test is a procedure that allows the test organism to come in direct contact with the solid sample as particulate in an aqueous suspension. Normally, this test provides results indicating equal or higher toxicity when compared to eluate or pore water tests of the same sample. [ 16 ] This is due to either equal or increased bioavailability resulting from direct contact. This test is subject to several sources of interference of luminescence including loss of bacteria from effects other than toxicity such as filtration of the sample; absorption of light due to color; and scattering of light due to turbidity . [ 16 ] Corrections can be made by testing a sample of similar particle composition that is known to not be toxic. This test consists of two controls and 13 sample dilutions in duplicate. [ 16 ] The Solid-Phase Test exposes the bacteria in such a way that is not always possible with pore water and elutriate. [ 12 ]
Acute Toxicity Comparison & Inhibition Tests are the best procedures for testing samples with a low level of toxicity when an ECxx can not be determined using the Basic Test. [ 17 ] These protocols are recommended for testing waste water treatment plant effluent, stormwater runoff , drinking water , pore water, and eluate. [ 17 ] These tests use multiple replicates of a sample at a single concentration. Similar to the Basic Test, the Comparison Test protocol uses zero time light readings used for correcting the timed light level readings. The Inhibition Test procedure does not use zero time light readings and therefore, can not use a correction factor for the timed light level readings. Both of these tests consists of five controls and five replicates of the sample at a single concentration. [ 17 ]
The Microtox Omni software was developed by Azur Environmental and allows users of the Microtox Model 500 analyser to run tests, visualize data, calculate statistics and generate reports. [ 18 ] This program contains a set of templates for all of the commonly used toxicity tests and allows you to modify or add to the provided templates. The modification of these templates allows for the production of new test formats not originally included with the software. [ 18 ] The test templates that are included in this software define all of the parameters for a particular test method. This program calculates the most efficient way of setting up the desired test on the Model 500 Analyser. A test tutor is also included with Microsoft Omni that gives listed instructions on how to set up and run the test of interest. [ 18 ] This software allows users to load files from previous versions of the Microtox DOS Software and also gives users the ability to save new data in that original format. A database is included in this software that grants users to access data from a number of other users and test sites, allowing for a comparison of data and trend changes over time. Microtox Omni can be used with any number of databases . [ 18 ]
Microtox has a variety of environmental and industrial applications. Common applications are for testing the toxicity of both marine and freshwater, as well as sediments for pesticides and other inorganic and organic chemicals. [ citation needed ]
Drinking water: Microtox is used to test drinking water sources in many areas where either accidental or deliberate contamination is possible. Toxic contaminants in drinking water are indicated by a change in the color or intensity of light, or by a change in the rate of oxygen use. [ 8 ]
Lakes and rivers: Microtox is used to test the toxicity of lake and river sediments contaminated by metals or nonspecific contaminants. The Solid-Phase test is used for sediments, while either the Basic test or the 100% test is used for pore water. [ 12 ]
Sediment testing: Microtox is used to test and evaluate the toxicity of various marine and freshwater sediments contaminated by metals and organics. Aqueous extracts of contaminated soils, drilling muds, and sludge. Microtox data may be used to establish apparent effects threshold (AET), sediment quality standards and used for NPDES permits, as well as Superfund cleanup levels. [ 12 ]
Industrial: This bioassay is used in the assessment of the toxicity of complex industrial effluent sources. It is a cost-effective way for monitoring and testing large numbers of samples.
Microtox can also be applied as an early warning system (EWS) and aid in detecting the presence of toxic materials, as well as predict the outcomes of other bioassays and tests. [ 19 ]
Microtox has also been applied to animal testing as an in vitro alternative. [ citation needed ]
Numerous studies and published data comparing Microtox results with toxicity values for fish, crustaceans and algae have found a positive correlation. [ 20 ] However, others have pointed out that the effect of luminosity on the survival of organisms is unknown. Concerns have also been expressed regarding the use of sediment extracts and not the sediment itself. It is possible that only water-soluble contaminants will be tested for, and therefore may not be representative of the full range of contaminants present in the sediment. Extracts may also remove contaminants that are not bioavailable. This could lead to an over or under estimation of contaminants and their biological effects. [ 12 ] | https://en.wikipedia.org/wiki/Microtox_bioassay |
In cell biology , microtrabeculae were a hypothesised fourth element of the cytoskeleton (the other three being microfilaments , microtubules and intermediate filaments ), proposed by Keith Porter based on images obtained from high-voltage electron microscopy of whole cells in the 1970s. [ 1 ] The images showed short, filamentous structures of unknown molecular composition associated with known cytoplasmic structures. It is now generally accepted that microtrabeculae are nothing more than an artifact of certain types of fixation treatment, although the complexity of the cell's cytoskeleton is not yet fully understood. [ 2 ]
This cell biology article is a stub . You can help Wikipedia by expanding it . | https://en.wikipedia.org/wiki/Microtrabeculae |
A microtubular membrane is a type of membrane made up of small tubular structures. Microtubular associated membranes are found in various cell types and are essential for maintaining cell structure and function. Synthetic membranes are used in chemical separation processes and in flow batteries. [ 1 ]
Cytoskeletal proteins interact with lipid bilayer membranes via interaction with peripheral or integral membrane proteins or through specific domains of cytoskeletal proteins with the lipid bilayer. [ 2 ] A characteristic feature of protozoan parasites is an ordered layer of microtubules beneath the cell membrane. [ 2 ] : 152
The interaction between microtubules and the plasma membrane provide support, shape, and stability to the cell, as well as act as tracks for transporting materials within the cell. Overall, microtubular membranes are vital components of cellular organization and function. Animal cells (and some filamentous fungi are thought to rely upon the microtubule cytoskeleton and associated motor proteins . [ citation needed ] Although plants, algae and fungi transport depends on myosins , which move along the actin cytoskeleton, certain organelles can move along microtubules in plant cells. [ 3 ]
Sub-millimeter, bundled microtubular (SBMT) membrane mitigate membrane pressure, which allows ions to pass through without additional support infrastructure This reduces the cost and size of the battery. A demonstration cells displayed higher peak charge and discharge power densities of 1,322 W/L cell and 306.1 W/L cell , respectively, compared with <60 W/L cell and 45 W/L cell , for conventional (planar) flow cells. [ 1 ] [ 4 ] SBMT's reduced the inter=membrane distance by ~100-fold and eliminated bulky flow distributors. The battery architecture is compatible with multiple chemistries, including zinc- oxide , zinc–bromide , quinone–bromide, and vanadium . [ 5 ] | https://en.wikipedia.org/wiki/Microtubular_membrane |
In cell biology , microtubule-associated proteins ( MAPs ) are proteins that interact with the microtubules of the cellular cytoskeleton . MAPs are integral to the stability of the cell and its internal structures and the transport of components within the cell.
MAPs bind to the tubulin subunits that make up microtubules to regulate their stability. A large variety of MAPs have been identified in many different cell types , and they have been found to carry out a wide range of functions. These include both stabilizing and destabilizing microtubules, guiding microtubules towards specific cellular locations, cross-linking microtubules and mediating the interactions of microtubules with other proteins in the cell. [1]
Within the cell, MAPs bind directly to the tubulin dimers of microtubules. This binding can occur with either polymerized or depolymerized tubulin, and in most cases leads to the stabilization of microtubule structure, further encouraging polymerization. Usually, it is the C-terminal domain of the MAP that interacts with tubulin, while the N-terminal domain can bind with cellular vesicles, intermediate filaments or other microtubules. MAP-microtubule binding is regulated through MAP phosphorylation . This is accomplished through the function of the microtubule-affinity-regulating-kinase (MARK) protein. Phosphorylation of the MAP by the MARK causes the MAP to detach from any bound microtubules. [2] This detachment is usually associated with a destabilization of the microtubule causing it to fall apart. In this way the stabilization of microtubules by MAPs is regulated within the cell through phosphorylation.
MAPs have been divided into several different categories and sub-categories. There are "structural" MAPs which bind along the microtubules and "+TIP" MAPs which bind to the growing end of the microtubules. Structural MAPs have been divided into MAP1, MAP2, MAP4, and Tau families. +TIP MAPs are motor proteins such as kinesin , dyneins , and other MAPs.
MAP1a ( MAP1A ) and MAP1b ( MAP1B ) are the two major members of the MAP1 family. These two proteins are high molecular weight. They bind to microtubules through charge interactions, a different mechanism to many other MAPs. While the C termini of these MAPs bind the microtubules, the N termini bind other parts of the cytoskeleton or the plasma membrane to control spacing of the microtubule within the cell. Members of the MAP1 family are found in the axons and dendrites of nerve cells .
Another member of this family is MAP1S , which has a low molecular-weight. MAP1S has been found to regulate cell division and cell death [ 1 ]
The MAP2 family is involved in the development of neurons, mostly present during early stages of axon formation then disappear later. However they exist in mature dendrites as well. Different forms of MAP2s are formed by different post-translational modifications of the mRNA.
MAP4 was previously not thought to exist in neuronal tissue however the MAP-SP has been found in certain mammalian brain tissue. MAP4 is not confined to just nerve cells, but rather can be found in nearly all types of cells.
Mainly associated with abnormalities that result in neurodegenerative diseases . Tau proteins stabilize microtubules, and thus shift the reaction kinetics in favor of addition of new subunits, accelerating microtubule growth. Tau has the additional function of facilitating bundling of microtubules within the nerve cell. The function of tau has been linked to the neurological condition Alzheimer's disease. In the nervous tissue of Alzheimer's patients, tau forms abnormal aggregates. This aggregated tau is often severely modified, most commonly through hyperphosphorylation. As described above, phosphorylation of MAPs causes them to detach from microtubules. Thus, the hyperphosphorylation of tau leads to massive detachment, which in turn greatly reduces the stability of microtubules in nerve cells.[9] This increase in microtubule instability may be one of the main causes of the symptoms of Alzheimer's disease.
Type II MAPs are found exclusively in nerve cells in mammals. These are the most well studied MAPs— MAP2 and tau ( MAPT )—which participate in determining the structure of different parts of nerve cells, with MAP2 being found mostly in dendrites and tau in the axon. These proteins have a conserved C-terminal microtubule-binding domain and variable N-terminal domains projecting outwards, probably interacting with other proteins. MAP2 and tau stabilize microtubules, and thus shift the reaction kinetics in favor of addition of new subunits, accelerating microtubule growth. Both MAP2 and tau have been shown to stabilize microtubules by binding to the outer surface of the microtubule protofilaments. [3] A single study has suggested that MAP2 and tau bind on the inner microtubule surface on the same site in tubulin monomers as the drug Taxol , which is used in treating cancer, [4] but this study has not been confirmed. MAP2 binds in a cooperative manner, with many MAP2 proteins binding a single microtubule to promote stabilization. Tau has the additional function of facilitating bundling of microtubules within the nerve cell. [5]
The function of tau has been linked to the neurological condition Alzheimer's disease . In the nervous tissue of Alzheimer's patients, tau forms abnormal aggregates. This aggregated tau is often severely modified, most commonly through hyperphosphorylation. As described above, phosphorylation of MAPs causes them to detach from microtubules. Thus, the hyperphosphorylation of tau leads to massive detachment, which in turn greatly reduces the stability of microtubules in nerve cells. [6] This increase in microtubule instability may be one of the main causes of the symptoms of Alzheimer's disease.
In contrast to the MAPs described above, MAP4 ( MAP4 ) is not confined to just nerve cells, but rather can be found in nearly all types of cells. Like MAP2 and tau, MAP4 is responsible for stabilization of microtubules. [7] MAP4 has also been linked to the process of cell division. [8]
Meiosis is a specialized form of cell division that generates haploid germ cells from diploid progenitor cells. During the early meiosis stage of pachynema in spermatocytes a male specific MAPS protein is expressed that is essential for pachynema progression. [ 2 ] Male mice lacking MAPS function experience pachytene arrest and spermatocyte death leading to infertility. [ 2 ] MAPS mutant spermatocytes arrested at early pachytene show defects in DNA double-strand break repair . [ 2 ]
Besides the classic MAP groups, novel MAPs have been identified that bind the length of the microtubules. These include STOP (also known as MAP6), and ensconsin (also known as MAP7).
In addition, plus end tracking proteins, which bind to the very tip of growing microtubules, have also been identified. These include EB1 , EB2 , EB3 , p150Glued , Dynamitin , Lis1 , CLIP170 , CLIP115 , CLASP1 , and CLASP2 .
Another MAP whose function has been investigated during cell division is known as XMAP215 (the "X" stands for Xenopus ). XMAP215 has generally been linked to microtubule stabilization. During mitosis the dynamic instability of microtubules has been observed to rise approximately tenfold. This is partly due to phosphorylation of XMAP215, which makes catastrophes (rapid depolymerization of microtubules) more likely. In this way the phosphorylation of MAPs plays a role in mitosis.
There are many other proteins which affect microtubule behavior, such as catastrophin , which destabilizes microtubules, katanin , which severs them, and a number of motor proteins that transport vesicles along them. Certain motor proteins were originally designated as MAPs before it was found that they utilized ATP hydrolysis to transport cargo. In general, all these proteins are not considered "MAPs" because they do not bind directly to tubulin monomers, a defining characteristic of MAPs. MAPs bind directly to microtubules to stabilize or destabilize them and link them to various cellular components including other microtubules. | https://en.wikipedia.org/wiki/Microtubule-associated_protein |
Microvesicles ( ectosomes , or microparticles ) are a type of extracellular vesicle (EV) that are released from the cell membrane . [ 1 ] In multicellular organisms, microvesicles and other EVs are found both in tissues (in the interstitial space between cells) and in many types of body fluids. [ 2 ] Delimited by a phospholipid bilayer, [ 3 ] [ 4 ] microvesicles can be as small as the smallest EVs (30 nm in diameter) or as large as 1000 nm. They are considered to be larger, on average, than intracellularly-generated EVs known as exosomes . Microvesicles play a role in intercellular communication and can transport molecules such as mRNA , miRNA , and proteins between cells. [ 5 ]
Though initially dismissed as cellular debris, microvesicles may reflect the antigenic content of the cell of origin and have a role in cell signaling . Like other EVs, they have been implicated in numerous physiologic processes, including anti-tumor effects, tumor immune suppression, metastasis, tumor-stroma interactions, angiogenesis , and tissue regeneration. [ 6 ] [ 7 ] [ 8 ] [ 9 ] Microvesicles may also remove misfolded proteins, cytotoxic agents and metabolic waste from the cell. Changes in microvesicle levels may indicate diseases including cancer. [ 10 ] [ 11 ]
Different cells can release microvesicles from the plasma membrane. Sources of microvesicles include megakaryocytes , blood platelets , monocytes , neutrophils , tumor cells and placenta .
Platelets play an important role in maintaining hemostasis: they promote thrombus growth, and thus they prevent loss of blood. Moreover, they enhance immune response, since they express the molecule CD154 ( CD40L ). Platelets are activated by inflammation, infection, or injury, and after their activation microvesicles containing CD154 are released from platelets. CD154 is a crucial molecule in the development of T cell-dependent humoral immune response. CD154 knockout mice are incapable of producing IgG , IgE , or IgA as a response to antigens . Microvesicles can also transfer prions and molecules CD41 and CXCR4. [ 12 ]
Endothelial microparticles are small vesicles that are released from endothelial cells and can be found circulating in the blood . [ 13 ]
The microparticle consists of a plasma membrane surrounding a small amount of cytosol . The membrane of the endothelial microparticle contains receptors and other cell surface molecules which enable the identification of the endothelial origin of the microparticle, and allow it to be distinguished from microparticles from other cells, such as platelets .
Although circulating endothelial microparticles can be found in the blood of normal individuals, increased numbers of circulating endothelial microparticles have been identified in individuals with certain diseases , including hypertension and cardiovascular disorders, [ 14 ] and pre-eclampsia [ 15 ] and various forms of vasculitis. The endothelial microparticles in some of these disease states have been shown to have arrays of cell surface molecules reflecting a state of endothelial dysfunction . Therefore, endothelial microparticles may be useful as an indicator or index of the functional state of the endothelium in disease, and may potentially play key roles in the pathogenesis of certain diseases, including rheumatoid arthritis . [ 16 ]
Endothelial microparticles have been found to prevent apoptosis in recipient cells by inhibiting the p38 pathway via inactivating mitogen-activated protein kinase (MKP)-1 . Uptake of endothelial micoparticles is Annexin I/Phosphatidylserine receptor dependant. [ 17 ]
Microparticles are derived from many other cell types. [ 18 ]
Microvesicles and exosomes are formed and released by two slightly different mechanisms. These processes result in the release of intercellular signaling vesicles. Microvesicles are small, plasma membrane -derived particles that are released into the extracellular environment by the outward budding and fission of the plasma membrane. This budding process involves multiple signaling pathways including the elevation of intracellular calcium and reorganization of the cell's structural scaffolding. The formation and release of microvesicles involve contractile machinery that draws opposing membranes together before pinching off the membrane connection and launching the vesicle into the extracellular space. [ 19 ] [ 20 ] [ 21 ]
Microvesicle budding takes place at unique locations on the cell membrane that are enriched with specific lipids and proteins reflecting their cellular origin. At these locations, proteins , lipids , and nucleic acids are selectively incorporated into microvesicles and released into the surrounding environment. [ 20 ]
Exosomes are membrane-covered vesicles, formed intracellularly are considered to be smaller than 100 nm. In contrast to microvesicles, which are formed through a process of membrane budding, or exocytosis , exosomes are initially formed by endocytosis . Exosomes are formed by invagination within a cell to create an intracellular vesicle called an endosome , or an endocytic vesicle. In general, exosomes are formed by segregating the cargo (e.g., lipids, proteins, and nucleic acids) within the endosome. Once formed, the endosome combines with a structure known as a multivesicular body (MVB). The MVB containing segregated endosomes ultimately fuses with the plasma membrane, resulting in exocytosis of the exosomes. [ 21 ] [ 22 ]
Once formed, both microvesicles and exosomes (collectively called extracellular vesicles) circulate in the extracellular space near the site of release, where they can be taken up by other cells or gradually deteriorate. In addition, some vesicles migrate significant distances by diffusion, ultimately appearing in biological fluids such as cerebrospinal fluid , blood , and urine . [ 21 ]
There are three mechanisms which lead to release of vesicles into the extracellular space. First of these mechanisms is exocytosis from multivesicular bodies and the formation of exosomes. Another mechanism is budding of microvesicles directly from a plasma membrane. And the last one is cell death leading to apoptotic blebbing . These are all energy-requiring processes.
Under physiologic conditions, the plasma membrane of cells has an asymmetric distribution of phospholipids . aminophospholipids , phosphatidylserine , and phosphatidylethanolamine are specifically sequestered in the inner leaflet of the membrane. The transbilayer lipid distribution is under the control of three phospholipidic pumps: an inward-directed pump, or flippase ; an outward-directed pump, or floppase ; and a lipid scramblase , responsible for non-specific redistribution of lipids across the membrane.
After cell stimulation, including apoptosis, a subsequent cytosolic Ca 2+ increase promotes the loss of phospholipid asymmetry of the plasma membrane, subsequent phosphatidylserine exposure, and a transient phospholipidic imbalance between the external leaflet at the expense of the inner leaflet, leading to budding of the plasma membrane and microvesicle release. [ 23 ]
The lipid and protein content of microvesicles has been analyzed using various biochemical techniques. Microvesicles display a spectrum of enclosed molecules enclosed within the vesicles and their plasma membranes. Both the membrane molecular pattern and the internal contents of the vesicle depend on the cellular origin and the molecular processes triggering their formation. Because microvesicles are not intact cells, they do not contain mitochondria , Golgi , endoplasmic reticulum , or a nucleus with its associated DNA. [ 22 ] [ 24 ]
Microvesicle membranes consist mainly of membrane lipids and membrane proteins . Regardless of their cell type of origin, nearly all microvesicles contain proteins involved in membrane transport and fusion. They are surrounded by a phospholipid bilayer composed of several different lipid molecules. The protein content of each microvesicle reflects the origin of the cell from which it was released. For example, those released from antigen-presenting cells (APCs), such as B cells and dendritic cells , are enriched in proteins necessary for adaptive immunity , while microvesicles released from tumors contain proapoptotic molecules and oncogenic receptors (e.g. EGFR). [ 22 ]
In addition to the proteins specific to the cell type of origin, some proteins are common to most microvesicles. For example, nearly all contain the cytoplasmic proteins tubulin, actin and actin-binding proteins, as well as many proteins involved in signal transduction, cell structure and motility, and transcription. Most microvesicles contain the so-called "heat-shock proteins" hsp70 and hsp90 , which can facilitate interactions with cells of the immune system. Finally, tetraspanin proteins, including CD9 , CD37 , CD63 and CD81 are one of the most abundant protein families found in microvesicle membranes. [ 22 ] [ 24 ] [ 25 ] [ 26 ] Many of these proteins may be involved in the sorting and selection of specific cargos to be loaded into the lumen of the microvesicle or its membrane. [ 27 ]
Other than lipids and proteins, microvesicles are enriched with nucleic acids (e.g., messenger RNA ( mRNA ) and microRNA ( miRNA )). The identification of RNA molecules in microvesicles supports the hypothesis that they are a biological vehicle for the transfer of nucleic acids and subsequently modulate the target cell's protein synthesis. Messenger RNA transported from one cell to another through microvesicles can be translated into proteins, conferring new function to the target cell. The discovery that microvesicles may shuttle specific mRNA and miRNA suggests that this may be a new mechanism of genetic exchange between cells. [ 26 ] [ 28 ] Exosomes produced by cells exposed to oxidative stress can mediate protective signals, reducing oxidative stress in recipient cells, a process which is proposed to depend on exosomal RNA transfer. [ 29 ] These RNAs are specifically targeted to microvesicles, in some cases containing detectable levels of RNA that is not found in significant amounts in the donor cell. [ 26 ]
Because the specific proteins, mRNAs, and miRNAs in microvesicles are highly variable, it is likely that these molecules are specifically packaged into vesicles using an active sorting mechanism. At this point, it is unclear exactly which mechanisms are involved in packaging soluble proteins and nucleic acids into microvesicles. [ 20 ] [ 30 ]
Once released from their cell of origin, microvesicles interact specifically with cells they recognize by binding to cell-type specific, membrane-bound receptors. Because microvesicles contain a variety of surface molecules, they provide a mechanism for engaging different cell receptors and exchanging material between cells. This interaction ultimately leads to fusion with the target cell and release of the vesicles' components, thereby transferring bioactive molecules, lipids, genetic material, and proteins. The transfer of microvesicle components includes specific mRNAs and proteins, contributing to the proteomic properties of target cells. [ 26 ] microvesicles can also transfer miRNAs that are known to regulate gene expression by altering mRNA turnover. [ 20 ] [ 21 ] [ 24 ] [ 31 ]
In some cases, the degradation of microvesicles is necessary for the release of signaling molecules . During microvesicle production, the cell can concentrate and sort the signaling molecules which are released into the extracellular space upon microvesicle degradation. Dendritic cells, macrophage and microglia derived microvesicles contain proinflammatory cytokines and neurons and endothelial cells release growth factors using this mechanism of release. [ 21 ]
Proteins on the surface of the microvesicle will interact with specific molecules, such as integrin , on the surface of its target cell. Upon binding, the microvesicle can fuse with the plasma membrane. This results in the delivery of nucleotides and soluble proteins into the cytosol of the target cell as well as the integration of lipids and membrane proteins into its plasma membrane. [ 3 ]
Microvesicles can be endocytosed upon binding to their targets, allowing for additional steps of regulation by the target cell. The microvesicle may fuse, integrating lipids and membrane proteins into the endosome while releasing its contents into the cytoplasm. Alternatively, the endosome may mature into a lysosome causing the degradation of the microvesicle and its contents, in which case the signal is ignored. [ 3 ]
After internalization of microvesicle via endocytosis, the endosome may move across the cell and fuse with the plasma membrane, a process called transcytosis . This results in the ejection of the microvesicle back into the extracellular space or may result in the transportation of the microvesicle into a neighboring cell. [ 3 ] This mechanism might explain the ability of microvesicle to cross biological barriers, such as the blood brain barrier , by moving from cell to cell. [ 32 ]
In this form of signaling, the microvesicle does not fuse with the plasma membrane or engulfed by the target cell. Similar to the other mechanisms of signaling, the microvesicle has molecules on its surface that will interact specifically with its target cell. There are additional surface molecules, however, that can interact with receptor molecules which will interact with various signaling pathways. [ 21 ] This mechanism of action can be used in processes such as antigen presentation, where MHC molecules on the surface of microvesicle can stimulate an immune response. [ 27 ] Alternatively, there may be molecules on microvesicle surfaces that can recruit other proteins to form extracellular protein complexes that may be involved in signaling to the target cell. [ 21 ]
The oncogenic receptor ECGFvIII , which is located in a specific type of aggressive glioma tumor, can be transferred to a non-aggressive population of tumor cells via microvesicles. After the oncogenic protein is transferred, the recipient cells become transformed and show characteristic changes in the expression levels of target genes. It is possible that transfer of other mutant oncogenes, such as HER2 , may be a general mechanism by which malignant cells cause cancer growth at distant sites. [ 20 ] [ 31 ] Microvesicles from non-cancer cells can signal to cancer cells to become more aggressive. Upon exposure to microvesicles from tumor-associated macrophages, breast cancer cells become more invasive in vitro . [ 33 ]
Angiogenesis , which is essential for tumor survival and growth, occurs when endothelial cells proliferate to create a matrix of blood vessels that infiltrate the tumor, supplying the nutrients and oxygen necessary for tumor growth. A number of reports have demonstrated that tumor-associated microvesicles release proangiogenic factors that promote endothelial cell proliferation, angiogenesis, and tumor growth. Microvesicles shed by tumor cells and taken up by endothelial cells also facilitate angiogenic effects by transferring specific mRNAs and miRNAs. [ 21 ]
When anticancer drugs such as doxorubicin accumulate in microvesicles, the drug's cellular levels decrease. This can ultimately contribute to the process of drug resistance. Similar processes have been demonstrated in microvesicles released from cisplatin -insensitive cancer cells. Vesicles from these tumors contained nearly three times more cisplatin than those released from cisplatin-sensitive cells. For example, tumor cells can accumulate drugs into microvesicles. Subsequently, the drug-containing microvesicles are released from the cell into the extracellular environment, thereby mediating resistance to chemotherapeutic agents and resulting in significantly increased tumor growth, survival, and metastasis . [ 20 ] [ 34 ]
Microvesicles from various tumor types can express specific cell-surface molecules (e.g. FasL or CD95) that induce T-cell apoptosis and reduce the effectiveness of other immune cells. microvesicles released from lymphoblastoma cells express the immune-suppressing protein latent membrane protein-1 (LMP1), which inhibits T-cell proliferation and prevents the removal of circulating tumor cells (CTCs). As a consequence, tumor cells can turn off T-cell responses or eliminate the antitumor immune cells altogether by releasing microvesicles. [ 20 ] the combined use of microvesicles and 5-FU resulted in enhanced chemosensitivity of squamous cell carcinoma cells more than the use of either 5-FU or microvesicle alone [ 35 ]
Degradation of the extracellular matrix is a critical step in promoting tumor growth and metastasis. Tumor-derived microvesicles often carry protein-degrading enzymes, including matrix metalloproteinase 2 ( MMP-2 ), MMP-9 , and urokinase-type plasminogen activator ( uPA ). By releasing these proteases, tumor cells can degrade the extracellular matrix and invade surrounding tissues. Likewise, inhibiting MMP-2, MMP-9, and uPA prevents microvesicles from facilitating tumor metastasis. Matrix digestion can also facilitate angiogenesis, which is important for tumor growth and is induced by the horizontal transfer of RNAs from microvesicles. [ 20 ]
The release of microvesicles has been shown from endothelial cells, vascular smooth muscle cells , platelets , white blood cells (e.g. leukocytes and lymphocytes ), and red blood cells . Although some of these microvesicle populations occur in the blood of healthy individuals and patients, there are obvious changes in number, cellular origin, and composition in various disease states. [ 36 ] [ 37 ] It has become clear that microvesicles play important roles in regulating the cellular processes that lead to disease pathogenesis. Moreover, because microvesicles are released following apoptosis or cell activation, they have the potential to induce or amplify disease processes. Some of the inflammatory and pathological conditions that microvesicles are involved in include cardiovascular disease , hypertension , neurodegenerative disorders , diabetes , and rheumatic diseases . [ 21 ] [ 22 ]
Microvesicles are involved in cardiovascular disease initiation and progression. Microparticles derived from monocytes aggravate atherosclerosis by modulating inflammatory cells. [ 38 ] Additionally, microvesicles can induce clotting by binding to clotting factors or by inducing the expression of clotting factors in other cells. [ 39 ] Circulating microvesicles isolated from cardiac surgery patients were found to be thrombogenic in both in vitro assays and in rats. Microvesicles isolated from healthy individuals did not have the same effects and may actually have a role in reducing clotting. [ 40 ] [ 39 ] Tissue factor , an initiator of coagulation, is found in high levels within microvesicles, indicating their role in clotting. [ 41 ] Renal mesangial cells exposed to high glucose media release microvesicles containing tissue factor, having an angiogenic effect on endothelial cells. [ 42 ]
Microvesicles contain cytokines that can induce inflammation via numerous different pathways. [ 39 ] These cells will then release more microvesicles, which have an additive effect. This can call neutrophils and leukocytes to the area, resulting in the aggregation of cells. [ 3 ] [ 43 ] However, microvesicles also seem to be involved in a normal physiological response to disease, as there are increased levels of microvesicles that result from pathology. [ 39 ]
Microvesicles seem to be involved in a number of neurological diseases. Since they are involved in numerous vascular diseases and inflammation, strokes and multiple sclerosis seem to be other diseases for which microvesicles are involved. Circulating microvesicles seem to have an increased level of phosphorylated tau proteins during early stage Alzheimer's disease . Similarly, increased levels of CD133 are an indicator of epilepsy . [ 44 ]
Tumor-associated microvesicles are abundant in the blood, urine, and other body fluids of patients with cancer, and are likely involved in tumor progression. They offer a unique opportunity to noninvasively access the wealth of biological information related to their cells of origin. The quantity and molecular composition of microvesicles released from malignant cells varies considerably compared with those released from normal cells. Thus, the concentration of plasma microvesicles with molecular markers indicative of the disease state may be used as an informative blood-based biosignature for cancer. [ 19 ] Microvesicles express many membrane-bound proteins, some of which can be used as tumor biomarkers. [ 45 ] Several tumor markers accessible as proteins in blood or urine have been used to screen and diagnose various types of cancer. In general, tumor markers are produced either by the tumor itself or by the body in response to the presence of cancer or some inflammatory conditions. If a tumor marker level is higher than normal, the patient is examined more closely to look for cancer or other conditions. For example, CA19-9 , CA-125 , and CEA have been used to help diagnose pancreatic , ovarian , and gastrointestinal malignancies, respectively. However, although they have proven clinical utility, none of these tumor markers are highly sensitive or specific. Clinical research data suggest that tumor-specific markers exposed on microvesicles are useful as a clinical tool to diagnose and monitor disease. [ 46 ] Research is also ongoing to determine if tumor-specific markers exposed on microvesicles are predictive for therapeutic response. [ 47 ] [ 48 ] [ 49 ] [ 50 ]
Evidence produced by independent research groups has demonstrated that microvesicles from the cells of healthy tissues, or selected miRNAs from these microvesicles, can be employed to reverse many tumors in pre-clinical cancer models, and may be used in combination with chemotherapy. [ 51 ] [ 52 ]
Conversely, microvesicles processed from a tumor cell are involved in the transport of cancer proteins and in delivering microRNA to the surrounding healthy tissue. It leads to a change of healthy cell phenotype and creates a tumor-friendly environment. Microvesicles play an important role in tumor angiogenesis and in the degradation of matrix due to the presence of metalloproteases , which facilitate metastasis. They are also involved in intensification of the function of regulatory T-lymphocytes and in the induction of apoptosis of cytotoxic T-lymphocytes , because microvesicles released from a tumor cell contain Fas ligand and TRAIL . They prevent differentiation of monocytes to dendritic cells .
Tumor microvesicles also carry tumor antigen , so they can be an instrument for developing tumor vaccines. Circulating miRNA and segments of DNA in all body fluids can be potential markers for tumor diagnostics. [ 20 ]
Rheumatoid arthritis is a chronic systemic autoimmune disease characterized by inflammation of joints. In the early stage there are abundant Th17 cells producing proinflammatory cytokines IL-17A, IL-17F, TNF , IL-21, and IL-22 in the synovial fluid . regulatory T-lymphocytes have a limited capability to control these cells. In the late stage, the extent of inflammation correlates with numbers of activated macrophages that contribute to joint inflammation and bone and cartilage destruction, because they have the ability to transform themselves into osteoclasts that destroy bone tissue. Synthesis of reactive oxygen species , proteases , and prostaglandins by neutrophils is increased. Activation of platelets via collagen receptor GPVI stimulates the release of microvesicles from platelet cytoplasmic membranes. These microparticles are detectable at a high level in synovial fluid, and they promote joint inflammation by transporting proinflammatory cytokine IL-1 .
In addition to detecting cancer, it is possible to use microvesicles as biological markers to give prognoses for various diseases. Many types of neurological diseases are associated with increased level of specific types of circulating microvesicles. For example, elevated levels of phosphorylated tau proteins can be used to diagnose patients in early stages of Alzheimer's. Additionally, it is possible to detect increased levels of CD133 in microvesicles of patients with epilepsy. [ 44 ]
Circulating microvesicles may be useful for the delivery of drugs to very specific targets. Using electroporation or centrifugation to insert drugs into microvesicles targeting specific cells, it is possible to target the drug very efficiently. [ 32 ] This targeting can help by reducing necessary doses as well as prevent off-target side effects. They can target anti-inflammatory drugs to specific tissues. [ 43 ] Additionally, circulating microvesicles can bypass the blood–brain barrier and deliver their cargo to neurons while not having an effect on muscle cells. The blood-brain barrier is typically a difficult obstacle to overcome when designing drugs, and microvesicles may be a means of overcoming it. [ 32 ] Current research is looking into efficiently creating microvesicles synthetically, or isolating them from patient or engineered cell lines. [ 53 ]
Microvesicles used in therapeutic genome editing appoaches are sometimes called a “gesicle”, especially if used to package/deliver the Cas9 RNP complex. [ 54 ] | https://en.wikipedia.org/wiki/Microvesicle |
Microvias are used as the interconnects between layers in high density interconnect (HDI) substrates and printed circuit boards (PCBs) to accommodate the high input/output (I/O) density of advanced packages.
Microvias are relevant in electronics manufacturing .
Driven by portability and wireless communications, the electronics industry strives to produce affordable, light, and reliable products with increased functionality. At the electronic component level, this translates to components with increased I/Os with smaller footprint areas (e.g. flip-chip packages, chip-scale packages, and direct chip attachments), and on the printed circuit board and package substrate level, to the use of high density interconnects (HDIs) (e.g. finer lines and spaces, and smaller vias ). [ 1 ]
IPC standards revised the definition of a microvia in 2013 to a hole with depth to diameter aspect ratio of 1:1 or less, and the hole depth not to exceed 0.25mm. Previously, microvia was any hole less than or equal to 0.15mm in diameter [ 2 ]
With the advent of smartphones and other hand-held electronic devices, microvias have evolved from single-level to stacked microvias that cross over multiple HDI layers. Sequential build-up (SBU) technology is used to fabricate HDI boards. The HDI layers are usually built up from a traditionally manufactured double-sided core board or multilayer PCB. The HDI layers are built on both sides of the traditional PCB one by one with microvias. The SBU process consists of several steps: layer lamination, via formation, via metallization, and via filling. There are multiple choices of materials and/or technologies for each step. [ 3 ]
Microvias can be filled with different materials and processes: [ 4 ]
Buried microvias are required to be filled, while blind microvias on the external layers usually do not have any fill requirements. [ 5 ] A stacked microvia is usually filled with electroplated copper to make electrical interconnections between multiple HDI layers and provide structural support for the outer level(s) of the microvia or for a component mounted on the outermost copper pad. [ 6 ] [ 7 ]
The reliability of HDI structure is one of the major constraints for its successful widespread implementation in the PCB industry. Good thermo-mechanical reliability of microvias is an essential part of HDI reliability. Many researchers and professionals have studied the reliability of microvias in HDI PCBs. The reliability of microvias depends on many factors such as microvia geometry parameters, dielectric material properties, and processing parameters.
Microvia reliability research has focused on experimental assessment of the reliability of single-level unfilled microvias, as well as finite element analysis on stress/strain distributions in single-level microvias and microvia fatigue life estimation. [ 8 ] Microvia failures identified from the research include interfacial separation (separation between the base of the microvia and the target pad), barrel cracks, corner/knee cracks, and target pad cracks (also referred to as microvia pull out). These failures result from the thermomechanical stresses caused by coefficient of thermal expansion (CTE) mismatch, in the PCB thickness direction, between the metallization in a microvia structure and the dielectric materials surrounding the metal. The following paragraph highlights some of the microvia reliability research.
Ogunjimi et al. [ 9 ] looked at the effect of manufacturing and design process variables on the fatigue life of microvias, including trace (conductor) thickness, layer or layers of the dielectric around the trace and in the microvia, via geometry, via wall angle, ductility coefficient of the conductor material, and strain concentration factor. Finite element models were created with different geometries, and ANOVA method was used to determine the significance of the different process variables. The ANOVA results showed that the strain concentration factor was the most important variable, followed with the ductility factor, metallization thickness, and via wall angle. Prabhu et al. [ 10 ] conducted a finite element analysis (FEA) on an HDI microvia structure to determine the effect of accelerated temperature cycling and thermal shock. Liu et al. [ 11 ] and Ramakrishna et al. [ 12 ] conducted liquid-to-liquid and air-to-air thermal shock testing, respectively, to study the effect of dielectric material properties and microvia geometry parameters, such as microvia diameter, wall angle and plating thickness, on microvia reliability. Andrews et al. [ 13 ] investigated single-level microvia reliability using IST (interconnect stress test), and considered the effect of reflow cycles of lead-free solder. Wang and Lai [ 14 ] investigated the potential failure sites of microvias using finite element modeling. They found that filled microvias have a lower stress than unfilled microvias. Choi and Dasgupta introduced microvia non-destructive inspection method in their work. [ 15 ]
Although most microvia reliability research focuses on single-level microvias, Birch [ 4 ] tested multiple-level stacked and staggered microvias using IST test. Weibull analysis on the test data showed that single- and 2-level stacked microvias last longer than 3- and 4-level microvias (e. g. 2-level stacked microvias experienced about 20 times more cycles to failure than 4-level stacked microvias).
One challenge for high density interconnect board development, is to fabricate reliable microvias, especially for stacked microvias, without resulting in incomplete filling, dimples, or voids in the copper plating process. [ 16 ] The authors of [ 16 ] have been investigating the risk of microvias in terms of voids and other defects using both experimental testing and finite element analysis. They found that incomplete copper filling increases the stress levels in microvias and hence decreases microvia fatigue life.
As for voids, different voiding conditions, such as different void sizes, shapes, and locations result in different effects on microvia reliability. Small voids of a spherical shape lightly increase the microvia fatigue life, but extreme voiding conditions greatly reduce the duration of microvias. | https://en.wikipedia.org/wiki/Microvia |
Microvoid coalescence ( MVC ) is a high energy microscopic fracture mechanism observed in the majority of metallic alloys and in some engineering plastics .
MVC proceeds in three stages: nucleation, growth, and coalescence of microvoids. The nucleation of microvoids can be caused by particle cracking or interfacial failure between precipitate particles and the matrix. Additionally, microvoids often form at grain boundaries or inclusions within the material. [ 1 ] [ 2 ] Microvoids grow during plastic flow of the matrix, and microvoids coalesce when adjacent microvoids link together or the material between microvoids experiences necking . Microvoid coalescence leads to fracture. [ 3 ] Void growth rates can be predicted assuming continuum plasticity using the Rice-Tracey model: [ 2 ] [ 4 ]
ln ( R ¯ R 0 ) = ∫ 0 ϵ q A ( 3 σ m 2 σ y s ) d ϵ v p {\displaystyle \ln \left({\frac {\bar {R}}{R_{0}}}\right)=\int \limits _{0}^{\epsilon _{q}}A\left({\frac {3\sigma _{m}}{2\sigma _{ys}}}\right)d\epsilon _{v}^{p}}
where A {\displaystyle A} is a constant typically equal to 0.283 (but dependent upon the stress triaxiality), σ y s {\displaystyle \sigma _{ys}} is the yield stress , σ m {\displaystyle \sigma _{m}} is the mean stress , ϵ q {\displaystyle \epsilon _{q}} is the equivalent Von Mises plastic strain, R o {\displaystyle R_{o}} is the particle size, and R ¯ {\displaystyle {\bar {R}}} produced by the stress triaxality:
R ¯ = R 1 + R 2 + R 3 3 {\displaystyle {\bar {R}}={\frac {R_{1}+R_{2}+R_{3}}{3}}}
MVC can result in three distinct fracture morphologies based on the type of loading at failure. Tensile loading results in equiaxed dimples, which are spherical depressions a few micrometres in diameter that coalesce normal to the loading axis. Shear stresses will result elongated dimples, which are parabolic depressions that coalesce in planes of maximum shear stress. The depressions point back to the crack origin, and shear influenced failure will produce depressions that point in opposite directions on opposing fracture surfaces. Combined tension and bending will also produce the elongated dimple morphology, but the directions of the depressions will be in the same direction on both fracture surfaces. | https://en.wikipedia.org/wiki/Microvoid_coalescence |
Microwave Active Composition is a brand of microwave -sensitive liquid chemicals sold by Atlanta Chemical Engineering LLC. The chemical undergoes color change if it interacts with intensive microwaves. There are two major types of microwave active compositions - reversible and irreversible. The reversible composition is colored liquid and when irradiated with microwaves losses its color. However it has the ability to revert to the original one in a short time after discontinuing the irradiation. The irreversible version of microwave active composition is white (transparent if coated) and transforms itself to colored one when makes contact with microwaves. It does not revert to the original color.
The microwave active compositions are used for validating the microwave energy distribution in the microwave heat processing chambers. | https://en.wikipedia.org/wiki/Microwave_Active_Composition |
Microwave chemistry is the science of applying microwave radiation to chemical reactions. [ 1 ] [ 2 ] [ 3 ] [ 4 ] [ 5 ] Microwaves act as high frequency electric fields and will generally heat any material containing mobile electric charges , such as polar molecules in a solvent or conducting ions in a solid. Microwave heating occurs primarily through two mechanisms: dipolar polarization and ionic conduction. Polar solvents because their dipole moments attempt to realign with the oscillating electric field, creating molecular friction and dielectric loss. The phase difference between the dipole orientation and the alternating field leads to energy dissipation as heat. [ 6 ] Semiconducting and conducting samples heat when ions or electrons within them form an electric current and energy is lost due to the electrical resistance of the material .Commercial microwave systems typically operate at a frequency of 2.45 GHz, which allows effective energy transfer to polar molecules without quantum mechanical resonance effects. [ 7 ] Unlike transitions between quantized rotational bands, microwave energy transfer is a collective phenomenon involving bulk material interactions rather than individual molecular excitations. [ 8 ] Microwave heating in the laboratory began to gain wide acceptance following papers in 1986, [ 9 ] although the use of microwave heating in chemical modification can be traced back to the 1950s. Although occasionally known by such acronyms as MAOS (microwave-assisted organic synthesis), [ 10 ] MEC (microwave-enhanced chemistry) or MORE synthesis (microwave-organic reaction enhancement), these acronyms have had little acceptance outside a small number of groups.
Conventional heating usually involves the use of a furnace or oil bath, which heats the walls of the reactor by convection or conduction. The core of the sample takes much longer to achieve the target temperature, e.g. when heating a large sample of ceramic bricks.
Acting as internal heat source, microwave absorption is able to heat the target compounds without heating the entire furnace or oil bath, which saves time and energy. [ 10 ] It is also able to heat sufficiently thin objects throughout their volume (instead of through its outer surface), in theory producing more uniform heating. However, due to the design of most microwave ovens and to uneven absorption by the object being heated, the microwave field is usually non-uniform and localized superheating occurs. Microwave volumetric heating (MVH) overcomes the uneven absorption by applying an intense, uniform microwave field.
Different compounds convert microwave radiation to heat by different amounts. This selectivity allows some parts of the object being heated to heat more quickly or more slowly than others (particularly the reaction vessel).
Microwave heating can have certain benefits over conventional ovens:
Microwave chemistry is applied to organic chemistry [ 11 ] and to inorganic chemistry. [ 12 ] [ 13 ] [ 14 ] [ 15 ] [ 16 ] [ 17 ]
A heterogeneous system (comprising different substances or different phases) may be anisotropic if the loss tangents of the components are considered. As a result, it can be expected that the microwave field energy will be converted to heat by different amounts in different parts of the system. This inhomogeneous energy dissipation means selective heating of different parts of the material is possible, and may lead to temperature gradients between them. Nevertheless, the presence of zones with a higher temperature than others (called hot spots) must be subjected to the heat transfer processes between domains. Where the rate of heat conduction is high between system domains, hot spots would have no long-term existence as the components rapidly reach thermal equilibrium . In a system where the heat transfer is slow, it would be possible to have the presence of a steady state hot spot that may enhance the rate of the chemical reaction within that hot zone.
On this basis, many early papers in microwave chemistry postulated the possibility of exciting specific molecules, or functional groups within molecules. However, the time within which thermal energy is repartitioned from such moieties is much shorter than the period of a microwave wave, thus precluding the presence of such 'molecular hot spots' under ordinary laboratory conditions. The oscillations produced by the radiation in these target molecules would be instantaneously transferred by collisions with the adjacent molecules, reaching at the same moment the thermal equilibrium. Processes with solid phases behave somewhat differently. In this case much higher heat transfer resistances are involved, and the possibility of the stationary presence of hot-spots should be contemplated. A differentiation between two kinds of hot spots has been noted in the literature, although the distinction is considered by many to be arbitrary. Macroscopic hot spots were considered to comprise all large non-isothermal volumes that can be detected and measured by use of optical pyrometers (optical fibre or IR). By these means it is possible to visualise thermal inhomogeneities within solid phases under microwave irradiation. Microscopic hot spots are non-isothermal regions that exist at the micro- or nanoscale (e.g. supported metal nanoparticles inside a catalyst pellet ) or in the molecular scale (e.g. a polar group on a catalyst structure). The distinction has no serious significance, however, as microscopic hotspots such as those proposed to explain catalyst behaviour in several gas-phase catalytic reactions have been demonstrated by post-mortem methods [ 18 ] and in-situ methods. [ 19 ] Some theoretical and experimental approaches have been published towards the clarification of the hot spot effect in heterogeneous catalysts.
A different specific application in synthetic chemistry is in the microwave heating of a binary system comprising a polar solvent and a non-polar solvent obtain different temperatures. Applied in a phase transfer reaction a water phase reaches a temperature of 100 °C while a chloroform phase would retain a temperature of 50 °C, providing the extraction as well of the reactants from one phase to the other. Microwave chemistry is particularly effective in dry media reactions .
There are two general classes of microwave effects:
A review has proposed this definition [ 20 ] and examples of microwave effects in organic chemistry have been summarized. [ 21 ]
Specific microwave effects are those effects that cannot be (easily) emulated through conventional heating methods. Examples include: (i) selective heating of specific reaction components, (ii) rapid heating rates and temperature gradients, (iii) the elimination of wall effects, and (iv) the superheating of solvents. Microwave-specific effects tend not to be controversial and invoke "conventional" explanations (i.e. kinetic effects) for the observed effects. [ 22 ]
Non-thermal microwave effects have been proposed in order to explain unusual observations in microwave chemistry. As the name suggests, the effects are supposed not to require the transfer of microwave energy into thermal energy. Such effects are controversial.
Application of microwave heating to heterogeneous catalysis reactions has not been explored intensively due to presence of metals in supported catalysts and possibility of arcing phenomena in the presence of flammable solvents. However, this scenario becomes unlikely using nanoparticle-sized metal catalysts. [ 10 ] | https://en.wikipedia.org/wiki/Microwave_chemistry |
Surface acoustic wave gas sensor or surface acoustic wave (SAW) sensors consist of an input transducer , a chemically adsorbent polymer film , and an output transducer on a piezoelectric substrate, which is typically made of quartz . [ 1 ] [ 2 ] The input transducer launches an acoustic wave that travels through the chemical film and is detected by the output transducer.
SAW devices have been able to detect and distinguish between organophosphates , chlorinated hydrocarbons , ketones , alcohols, aromatic hydrocarbons , saturated hydrocarbons , and water. Such a device made at Sandia National Laboratories runs at a very high frequency (approximately 525 MHz ), and the velocity and attenuation of the signal are sensitive to the viscoelasticity and mass of the thin film.
The device has four channels, each channel consisting of a transmitter and a receiver, separated by a small distance. Three of the four channels contain a polymer deposited on the substrate between the transmitter and receiver . The purpose of the polymers is to adsorb chemicals of interest, with different polymers having different affinities for various chemicals. When a target chemical is adsorbed, the mass of the associated polymer increases, causing a slight change in phase of the acoustic signal relative to the reference (fourth) channel, which contains no polymer.
The SAW device also contains three Application Specific Integrated Circuit chips ( ASICs ), containing the electronics that functions to analyze the signals and release a DC voltage output signal proportional to the phase shift. It contains transducers and ASICs that are bonded to a piece of quartz glass , which is placed in a leadless chip carrier (LCC). Wire bonds connect the terminals of the leadless chip carrier to the SAW circuits.
The Microwave chemistry sensor can detect several chemical materials including: | https://en.wikipedia.org/wiki/Microwave_chemistry_sensor |
Microwave digestion is a chemical technique used to decompose sample material into a solution suitable for quantitative elemental analysis . [ 1 ] It is commonly used to prepare samples for analysis using inductively coupled plasma mass spectrometry (ICP-MS) , atomic absorption spectroscopy , and atomic emission spectroscopy (including ICP-AES ).
To perform the digestion, sample material is combined with a concentrated strong acid or a mixture thereof, most commonly using nitric acid , hydrochloric acid and/or hydrofluoric acid , in a closed PTFE vessel. The vessel and its contents are then exposed to microwave irradiation , raising the pressure and temperature of the solution mixture. The elevated pressures and temperatures within a low pH sample medium increase both the speed of thermal decomposition of the sample and the solubility of elements in solution. Organic compounds are decomposed into gaseous form, effectively removing them from solution. Once these elements are in solution, it is possible to quantify elemental concentrations within samples. [ 1 ]
Microwaves can be programmed to reach specific temperatures or ramp up to a given temperature at a specified rate. The temperature in the interior of the vessel is monitored by an infrared external sensor or by a optic fiber probe, and the microwave power is regulated to maintain the temperature defined by the active program. The vessel solution must contain at least one solvent that absorbs microwave radiation, usually water. The specific blend of acids (or other reagents) and the temperatures vary depending upon the type of sample being digested. Often a standardized protocol for digestion is followed, such as an Environmental Protection Agency Method .
Before microwave digestion technology was developed, samples were digested using less convenient methods, such as heating vessels in an oven, typically for at least 24 hours. The use of microwave energy allows for fast sample heating, reducing digestion time to as little as one hour.
Another common means to decompose samples for elemental analysis is dry-ashing, in which samples are incinerate d in a muffle furnace . [ 2 ] The resultant ash is then dissolved for analysis, usually into dilute nitric acid. While this method is simple, inexpensive and does not require concentrated acids, it cannot be used for volatile elements such as mercury and can increase the likelihood of background contamination. The incineration will not convert all elements to soluble salts, necessitating an additional digestion step.
In microwave digestion, 100% analyte recovery cannot be assumed. To account for this, scientists perform tests such as fortification recovery, [ 3 ] in which a spike (a known amount of the target analyte ) is added to test samples. These spiked samples are then analyzed to determine whether the expected increase in analyte concentration occurs.
Contamination from improperly cleaned digestion vessels is also a possibility. As such, in any microwave digestion, blank samples need to be digested to determine if there is background contamination. | https://en.wikipedia.org/wiki/Microwave_digestion |
Microwave engineering pertains to the study and design of microwave circuits, components, and systems. Fundamental principles are applied to analysis, design and measurement techniques in this field. The short wavelengths involved distinguish this discipline from electronic engineering . This is because there are different interactions with circuits, transmissions and propagation characteristics at microwave frequencies.
Some theories and devices that pertain to this field are antennas , radar , transmission lines , space based systems ( remote sensing ), measurements, microwave radiation hazards and safety measures.
During World War II , microwave engineering played a significant role in developing radar that could accurately locate enemy ships and planes with a focused beam of EM radiation . The foundations of this discipline are found in Maxwell's equations and the work of Heinrich Hertz , William Thomson 's waveguide theory , J.C. Bose , the klystron from Russel and Varian Bross, as well as contributions from Perry Spencer, and others. [ 1 ]
Microwave is a term used to identify electromagnetic waves above 10 3 megahertz (1 Gigahertz) up to 300 Gigahertz because of the short physical wavelengths of these frequencies. Short wavelength energy offers distinct advantages in many applications. For instance, sufficient directivity can be obtained using relatively small antennas and low-power transmitters. These characteristics are ideal for use in both military and civilian radar and communication applications. Small antennas and other small components are made possible by microwave frequency applications. The size advantage can be considered as part of a solution to problems of space, or weight, or both. Microwave frequency usage is significant for the design of shipboard radar because it makes possible the detection of smaller targets. Microwave frequencies present special problems in transmission, generation, and circuit design that are not encountered at lower frequencies. Conventional circuit theory is based on voltages and currents , while microwave theory is based on electromagnetic fields . [ 2 ]
Apparatus and techniques may be described qualitatively as "microwave" when the wavelengths of signals are roughly the same as the dimensions of the equipment, so that the lumped-element model is inaccurate. As a consequence, practical microwave technique tends to move away from the discrete resistors , capacitors , and inductors used with lower frequency radio waves . Instead, the distributed-element model and transmission-line theory are more useful methods for design and analysis. Open-wire and coaxial transmission lines give way to waveguides and stripline , and lumped-element tuned circuits are replaced by cavity resonators or resonant lines. Effects of reflection , polarization , scattering , diffraction and atmospheric absorption usually associated with visible light are of practical significance in the study of microwave propagation . The same equations of electromagnetic theory apply at all frequencies. [ 1 ] [ 3 ]
The microwave engineering discipline has become relevant as the microwave domain moves into the commercial sector, and no longer only applicable to 20th and 21st century military technologies . Inexpensive components and digital communications in the microwave domain have opened up areas pertinent to this discipline. Some of these areas are radar, satellite , wireless radio , optical communication , faster computer circuits, and collision avoidance radar. [ 4 ]
Many colleges and universities offer microwave engineering. A few examples follow.
The University of Massachusetts Amherst provides research and educational programs in microwave remote sensing, antenna design and communications systems. Courses and project work are offered leading toward graduate degrees. Specialties include microwave and RF integrated circuit design, antenna engineering, computational electromagnetics, radiowave propagation, radar and remote sensing systems, image processing, and THz imaging. [ 5 ] [ 6 ]
Tufts University offers a Microwave and Wireless Engineering certificate program as part of its graduate studies programs. It can be applied toward a master's degree in electrical engineering. The student must have an appropriate bachelor's degree to enroll in this program. [ 4 ]
Auburn University offers research for the microwave arena. Wireless Engineering Research and Education Center is one of three research centers. The university also offers a Bachelor of Wireless Engineering degree with a Wireless Electrical Engineering major. [ 7 ] [ 8 ] [ 9 ]
Bradley University offers an undergraduate and a graduate degree in its Microwave and Wireless Engineering Program. It has an Advanced Microwave Laboratory, a Wireless Communication Laboratory and other facilities related to research. [ 10 ]
There are professional societies pertinent to this discipline:
The IEEE Microwave Theory and Techniques Society (MTT-S) "promotes the advancement of microwave theory and its applications...". The society also publishes peer reviewed journals, and one magazine. [ 11 ]
There are peer reviewed journals and other scholarly periodicals that cover topics that pertains to microwave engineering. Some of these are IEEE Transactions on Microwave Theory and Techniques , IEEE Microwave and Wireless Components Letters , Microwave Magazine, [ 12 ] IET Microwaves, Antennas & Propagation, [ 13 ] and Microwave Journal. [ 14 ] | https://en.wikipedia.org/wiki/Microwave_engineering |
Microwave radiation was applied in electrochemical methods in 1998 when Frank Marken and Richard G. Compton in Oxford placed a piece of platinum wire inside a microwave cavity in small electrochemical cell. [ 1 ]
This electrochemistry -related article is a stub . You can help Wikipedia by expanding it . | https://en.wikipedia.org/wiki/Microwave_enhanced_electrochemistry |
The microwave heat distribution is the distribution (allocation) of the heat release inside the microwave absorptive material irradiated with high intensive microwaves .
The pattern of microwave heat distribution depends on many physical parameters, which may include the electromagnetic field , the specific absorption rate and structure of the processed material, the geometrical dimensions of the processing cavity, etc. Most of the industrial microwave heating applications need a uniform heat distribution.
For example, the uniformity of microwave heat distribution is key parameter in microwave food sterilization, due to the potential danger directly related to human health if the food has not been heated evenly up to desirable temperature for neutralization of possible bacteria population. There are many different methods for achieving uniform heat distribution inside the irradiated material. They may involve computer simulation and different mechanical mechanisms such as turntables and stirrers.
The proper microwave energy pattern is necessary for attaining a uniform heat release.
Electromagnetic-Temperature Control & Optimization of Microwave Thermal Processing
A hybrid technique for computing the power distribution generated in a lossy medium during microwave heating
Microwave processing of Materials, National Research Council, Publication NMAB-473 , Washington, DC, 1994
J. Chang, and M. Brodwin, “A new applicator for efficient uniform heating using a circular cylindrical geometry,” J. Microwave Power & Electromagnetic Energy , vol. 28, pp. 32–40, March 1993 | https://en.wikipedia.org/wiki/Microwave_heat_distribution |
Microwave imaging is a science which has been evolved from older detecting/locating techniques (e.g., radar ) in order to evaluate hidden or embedded objects in a structure (or media) using electromagnetic (EM) waves in microwave regime (i.e., ~300 MHz-300 GHz). [ 1 ] Engineering and application oriented microwave imaging for non-destructive testing is called microwave testing , see below.
Microwave imaging techniques can be classified as either quantitative or qualitative. Quantitative imaging techniques (are also known as inverse scattering methods) give the electrical (i.e., electrical and magnetic property distribution) and geometrical parameters (i.e., shape, size and location) of an imaged object by solving a nonlinear inverse problem. The nonlinear inverse problem is converted into a linear inverse problem (i.e., Ax=b where A and b are known and x (or image) is unknown) by using Born or distorted Born approximations. Despite the fact that direct matrix inversion methods can be invoked to solve the inversion problem, this will be so costly when the size of the problem is so big (i.e., when A is a very dense and big matrix). To overcome this problem, direct inversion is replaced with iterative solvers. Techniques in this class are called forward iterative methods which are usually time consuming.
On the other hand, qualitative microwave imaging methods calculate a qualitative profile (which is called as reflectivity function or qualitative image) to represent the hidden object. These techniques use approximations to simplify the imaging problem and then they use back-propagation (also called time reversal, phase compensation, or back-migration) to reconstruct the unknown image profile. Synthetic aperture radar (SAR), ground-penetrating radar (GPR), and frequency-wave number migration algorithm are some of the most popular qualitative microwave imaging methods [1] .
In general, a microwave imaging system is made up of hardware and software components. The hardware collects data from the sample under test. A transmitting antenna sends EM waves towards the sample under test (e.g., human body for medical imaging). If the sample is made of only homogeneous material and is of infinite size, theoretically no EM wave will be reflected. Introduction of any anomaly which has different properties (i.e., electrical/magnetic) in comparison with the surrounding homogeneous medium may reflect a portion of the EM wave. The bigger the difference between the properties of the anomaly and the surrounding medium is, the stronger the reflected wave will be. This reflection is collected by the same antenna in a monostatic system, or a different receiver antenna in bistatic configurations.
To increase the cross-range resolution of the imaging system, several antennas should be distributed over an area (which is called the sampling area) with a spacing less than the operating wavelength. However, the mutual coupling between the antennas, which are placed close to each other, may degrade the accuracy of the collected signals. Moreover, the transmitter and receiver system will become very complex. To address these problems, one single scanning antenna is used instead of several antennas. In this configuration, the antenna scans over the entire sampling area, and the collected data is mapped together with their antenna position coordinates. In fact, a synthetic (virtual) aperture is produced by moving the antenna (similar to the synthetic aperture radar principle [ 2 ] ).
Later, the collected data, which is sometimes referred to as raw data, is fed into the software for processing. Depending on the applied processing algorithm, microwave imaging techniques can be categorized as quantitative and qualitative.
Microwave imaging has been used in a variety of applications such as: nondestructive testing and evaluation (NDT&E, see below), medical imaging, concealed weapon detection at security check points, structural health monitoring, and through-the-wall imaging.
Microwave imaging for medical applications is also becoming of more interest. The dielectric properties of malignant tissue change significantly in comparison with the properties of normal tissue (e.g., breast tissue). This difference translates into a contrast which can be detected by microwave imaging methods. As one example, there are several research groups all around the world working on developing efficient microwave imaging techniques for early detection of breast cancer. [ 3 ]
Ageing of infrastructure is becoming a serious problem worldwide. For example, in reinforced concrete structures, corrosion of their steel reinforcements is the main cause of their deterioration. In U.S. alone, repair and maintenance cost due to such corrosion is about $276 billion per year, [ 4 ] [3] .
Recently, microwave imaging has shown great potential to be used for structural health monitoring. Lower frequency microwaves (e.g., <10 GHz) can easily penetrate through concrete and reach objects of interest such as reinforcement bars (rebars). If there is any rust on the rebar, since rust reflects less EM waves in comparison with sound metal, the microwave imaging method can distinguish between rebars with and without rust (or corrosion). [ citation needed ] Microwave imaging also can be used to detect any embedded anomaly inside concrete (e.g., crack or air void).
These applications of microwave imaging are part of non-destructive (NDT) testing in civil engineering. More on microwave imaging in NDT is described in the following.
Microwave testing uses the scientific basics of microwave imaging for the inspection of technical parts with harmless microwaves . Microwave testing is one of the methods of non-destructive testing (NDT). It is restricted to tests of dielectric, i. e. non-conducting material. This includes glass-fibre reinforced plastic (GRP, GFRP). [ 5 ] Microwave testing can be used to inspect components also in a built-in state, e. g. built-in non-visible gaskets in plastic valves.
The microwave frequencies extend from 300 MHz to 300 GHz corresponding to wavelengths between 1 m and 1 mm. The section from 30 GHz to 300 GHz with wavelengths between 10 mm and 1 mm is also called millimeter waves . Microwaves are in the order of the size of the components to be tested. In different dielectric media they propagate differently fast and at surfaces between them they are reflected. Another part propagates beyond the surface. The larger the difference in the wave impedance , the larger is the reflected part.
In order to find material defects, a test probe, attached or in a small distance, is moved over the surface of the device under test. This can be done manually or automatically. [ 6 ] The test probe transmits and receives microwaves.
Changes of the dielectric properties at surfaces (e. g. shrinkage cavities, pores, foreign material inclusion, or cracks) within the interior of the device under test reflect the incident microwave and send a part of it back to the test probe, which acts as a transmitter and as a receiver. [ 7 ] [ 8 ]
The electronic data evaluation leads to a display of the results, e. g. as a B-scan (cross sectional view) or as a C-scan (top view). These display methods are adopted from ultrasonic testing.
Besides the reflection method also the through transmission method is possible, in which separate transmit and receive antennas are used. The backside of the device under test (DUT) must be accessible and the method gives no information about the depth of a defect within the DUT.
Microwave tests are possible with constant frequency ( CW ) or with continuously tuned frequency ( FMCW ). FMCW is advantageous to determine the depth of defects within the DUT.
A test probe attached to the DUT's surface gives information about the material distribution below the point of contact. When moving over the DUT surface point by point many such information is stored and then evaluated to give an overall image. This takes time. Directly imaging procedures are faster: Microwave versions are either electronic [ 9 ] or make use of planar microwave detector consisting of a microwave absorbing foil and an infrared camera (NIDIT procedure [ 10 ] ).
Microwave testing is a useful NDT method for dielectric materials. Among them are plastics , glass-fiber reinforced plastics (GFRP) , plastic foams , wood , wood-plastic composites (WPC) , and most types of ceramics . Defects interior in the DUT and at its surface can be detected, e. g. in semi-finished products or pipes .
Special applications of microwave testing are non-destructive
Microwave testing is used in many industrial sectors:
In the last years the need for NDT has increased generally and especially also for dielectric materials. For this reason and because microwave technics more and more are used in consumer products and hereby became much less expensive, NDT with microwaves increases. In recognizing this growing importance, in 2011 the Expert committee for microwave and THz procedures [ 17 ] of the German Society of Non-Destructive Testing (DGZfP) was founded as in 2014 the Microwave Testing Committee of the American Society for Non-Destructive Testing (ASNT). Standardization work is at the beginning. | https://en.wikipedia.org/wiki/Microwave_imaging |
A microwave power meter is an instrument which measures the electrical power at microwave frequencies typically in the range 100 MHz to 40 GHz.
Usually a microwave power meter will consist of a measuring head which contains the actual power sensing element, connected via a cable to the meter proper, which displays the power reading. The head may be referred to as a power sensor or mount . Different power sensors can be used for different frequencies or power levels. Historically the means of operation in most power sensor and meter combinations was that the sensor would convert the microwave power into an analogue voltage which would be read by the meter and converted into a power reading. Several modern power sensor heads contain electronics to create a digital output and can be plugged via USB into a PC which acts as the power meter.
Microwave power meters have a wide bandwidth —they are not frequency-selective. To measure the power of a specific frequency component in the presence of other signals at different frequencies a spectrum analyzer or measuring receiver is needed.
There are a variety of different technologies which have been used as the power sensing element. Each has advantages and disadvantages.
Thermal sensors can generally be divided into two main categories, thermocouple power sensors and thermistor-based power sensors. Thermal sensors depend on the process of absorbing the RF and microwave signal energy, and sense the resulting heat rise. Therefore, they respond to true average power of the signal, whether it is pulsed, CW, AM/FM or any complex modulation. (Agilent 2008).
Thermocouple power sensors make up the majority of the thermal power sensors sold at present. They are generally reasonably linear and have a reasonably fast response time and dynamic range . The microwave power is absorbed in a load whose temperature rise is measured by the thermocouple. Thermocouple sensors often require a reference DC or microwave power source for calibration before measuring; this can be built into the power meter. Thermistor -based power sensors such as the Keysight 8478B are generally only used in situations where their excellent linearity is important, as they are both much slower and have a smaller dynamic range than either thermocouple or diode-based sensors. Thermistor-based power sensors are still the sensor of choice for power transfer standards because of their DC power substitution capability. Other thermal sensing technologies include microwave calorimeters and bolometers , and quasi-optic pulsed microwave sensors.
Many microwave power heads use diodes to rectify the incident microwave power, and have extremely fast response. The diode would generally be used in its square-law region and hence give an output voltage proportional to the incident RF power. In order to extend their dynamic range beyond the square-law region, linearity correction circuits or multiple diode stacks are used. With advancement in comprehensive data compensation algorithm and diode stacks topology, diode sensors like the Keysight E9300A is able to respond properly to complex modulated signals over a wide dynamic range. Like thermocouple sensors, they often require a reference source.
Other technologies have been investigated or implemented for use as power sensors but are not widely used today; these include torque -vane, electron -beam, MEMS , Hall effect and atomic fountain based sensors.
The two main types of microwave power meters are:
Power meters generally report the power in dBm ( decibels relative to 1 milli watt ), dBW (decibels relative to 1 watt) or watts. Manufacturers of microwave power meters include: Aeroflex , Keysight , Anritsu , Bird Technologies , Boonton Electronics , Giga-tronics, Rohde and Schwarz , Tektronix and TEGAM Inc. . | https://en.wikipedia.org/wiki/Microwave_power_meter |
Microwave spectroscopy is the spectroscopy method that employs microwaves , i.e. electromagnetic radiation at GHz frequencies, for the study of matter.
The ammonia molecule NH 3 is shaped like a pyramid 0.38 Å in height, with an equilateral triangle of hydrogens forming the base.The nitrogen situated on the axis has two equivalent equilibrium positions above and below the triangle of hydrogens, and this raises the possibility of the nitrogen tunneling up and down, through the plane of the H-atoms. In 1932 Dennison et al. ... analyzed the vibrational energy of this molecule and concluded that the vibrational energy would be split into pairs by the presence of these two equilibrium positions. The next year Wright and Randall observed ... a splitting of 0.67 cm –1 in far infrared lines, corresponding to a frequency of 20 GHz, the value predicted by theory. In 1934 Cleeton and Williams ... constructed a grating echelle spectrometer in order to measure this splitting directly, thereby beginning the field of microwave spectroscopy. They observed a somewhat asymmetric absorption line with a maximum at 24 GHz and a full width at half height of 12 GHz. [ 1 ]
In the field of molecular physics , microwave spectroscopy is commonly used to probe the rotation of molecules. [ 2 ]
In the field of condensed matter physics , microwave spectroscopy is used to detect dynamic phenomena of either charges or spins at GHz frequencies (corresponding to nanosecond time scales) and energy scales in the μeV regime. Matching to these energy scales, microwave spectroscopy on solids is often performed as a function of temperature (down to cryogenic regimes of a few K or even lower) [ 3 ] and/or magnetic field (with fields up to several T). Spectroscopy traditionally considers the frequency-dependent response of materials, and in the study of dielectrics microwave spectroscopy often covers a large frequency range. In contrast, for conductive samples as well as for magnetic resonance, experiments at a fixed frequency are common (using a highly sensitive microwave resonator ), [ 4 ] but frequency-dependent measurements are also possible. [ 5 ]
For insulating materials (both solid and liquid), [ 6 ] probing charge dynamics with microwaves is a part of dielectric spectroscopy .
Amongst the conductive materials, superconductors are a material class that is often studied with microwave spectroscopy, giving information about penetration depth (governed by the superconducting condensate), [ 4 ] [ 7 ] energy gap (single-particle excitation of Cooper pairs ), and quasiparticle dynamics. [ 8 ]
Another material class that has been studied using microwave spectroscopy at low temperatures are heavy fermion metals with Drude relaxation rates at GHz frequencies. [ 5 ]
Microwaves impinging on matter usually interact with charges as well as with spins (via electric and magnetic field components, respectively), with the charge response typically much stronger than the spin response. But in the case of magnetic resonance, spins can be directly probed using microwaves. For paramagnetic materials, this technique is called electron spin resonance (ESR) and for ferromagnetic materials ferromagnetic resonance (FMR) . [ 9 ] In the paramagnetic case, such an experiment probes the Zeeman splitting , with a linear relation between the static external magnetic field and the frequency of the probing microwave field. A popular combination, as implemented in commercial X-band ESR spectrometers, is approximately 0.3 T (static field) and 10 GHz (microwave frequency) for a typical material with electron g-factor close to 2. | https://en.wikipedia.org/wiki/Microwave_spectroscopy |
Mictomagnetism is a spin system in which various exchange interactions are mixed. It is observed in several kinds of alloys , including Cu–Mn, Fe–Al and Ni–Mn alloys. Cooled in zero magnetic field, these materials have low remanence and coercivity . Cooled in a magnetic field, they have much larger remanence, and the hysteresis loop is shifted in the direction opposite to the field (an effect similar to exchange bias ). [ 1 ]
This electromagnetism -related article is a stub . You can help Wikipedia by expanding it . | https://en.wikipedia.org/wiki/Mictomagnetism |
The Mid-Atlantic Ridge Ecosystem Project MAR-ECO is an international research project in which scientists from 16 nations take part. Norway, represented by the Institute of Marine Research and the University of Bergen , co-ordinates the project which will enhance our understanding of occurrence, distribution and ecology of animals and animal communities along the Mid-Atlantic Ridge between Iceland and the Azores. The Mid-Atlantic Ridge is the volcanic mountain range in the middle of the ocean, marking the spreading zone between the Eurasian and American continental plates. New ocean floor is constantly being formed, and Iceland and the Azores are volcanic islands created when the mid-ocean ridge breaks the sea surface. The groups of animals to be studied are fishes, crustaceans, cephalopods (squids) and a wide range of gelatinous animals (e.g. jellyfish) living either near the seabed or in midwater above the ridge.
The research programme Census of Marine Life seriously addresses this situation and challenges marine biologists to utilize the most advanced technology to achieve true new information in areas of the ocean that were poorly studied previously. The project MAR-ECO, an element of the Census of Marine Life , rises to the challenge and investigates the diverse animal life along the vast underwater mountain chains of the open ocean.
MAR-ECO adopts the most advanced technology and instruments for observing and sample the animals and to tackle the challenge of working to 3500 m depth and in rugged terrain. An international multidisciplinary team of biologists, oceanographers, and engineers is offered this rare opportunity. A number of countries have committed their best research vessels, and in the 2003-2005 and 2007-2010 field phases a number of research cruise were conducted. In 2004, a two-month major international expedition was carried out by the new Norwegian vessel RV G.O. Sars, but vessels from Iceland, Russia, Germany, the United Kingdom, USA, and Portugal have also made major contributions. In June 2003 a Russian-US cruise using the crewed submersibles MIR-1 and -2 took scientists to areas never before visited by humans at 4500m below the surface. Contributing to sustainable development
MAR-ECO shall enhance the basic knowledge of ocean life and thereby contribute to a sustainable international management of marine resources and the priceless biodiversity of the marine environment. Knowledge obtained by a unified international effort carries greater weight in the policy-making processes than information gathered by isolated national research. Good science may hopefully lead to international consensus on appropriate action.
MAR-ECO and the Census of Marine Life emphasises public outreach and even in the planning phase MAR-ECO has enjoyed considerable public attention and support. Expeditions to unknown depths of the oceans appear to have great appeal, both to scientists and the interested laymen of all ages.
The MAR-ECO management consists of a Norwegian secretariat, a public outreach group, and an international steering group. The co-ordinating institutions are Institute of Marine Research and the University of Bergen in Norway.
Members of the international steering group are experienced scientists from key institutions in Norway, Iceland, Portugal (Azores), France, Germany, United Kingdom, USA, Russia and Brazil. Chair: Odd Aksel Bergstad, Norway.
The project consists of 10 integrated science components dealing with different key objectives, each with dedicated teams and principal investigators. In addition, a range of education and outreach components facilitates dissemination of results to a wide audience.
Common critical tasks are funded by A.P.Sloan Foundation (USA), and national sources.
The Public Outreach Group is based in Bergen, Norway, but has associates among project participants in other countries. The group works closely with the Education and Outreach team of the Census of Marine Life based in the USA.
The Mar-ECO project presented an exhibit in the Sant Ocean Hall of the Smithsonian Museum of Natural History in Washington, DC in 2010. The exhibit featured specimens, photography, art, models, and multimedia about the discoveries of the program. [ 1 ] | https://en.wikipedia.org/wiki/Mid-Atlantic_Ridge_Ecosystem_Project |
The Mid-Mesozoic Parasitoid Revolution ( MMPR ) was an evolutionary radiation of insect parasites and parasitoids from the Toarcian to the Albian . [ 1 ]
The MMPR represented a major reorganisation of terrestrial food webs . [ 2 ] Before the MMPR, parasitoid insects were absent in many fossil assemblages, such as the Triassic-aged Madygen , Molteno , Beishan, Shangtu, and Cow Branch Formations . The MMPR was marked by an increase in diversity among coleopterans , dipterans , strepsipterans , and hymenopterans , the main insect clades containing parasitoids, that reflected these clades entering parasitoid niches.
The beginning phase of the MMPR lasted from the late Early Toarcian to the Valanginian . It is documented in the Jiulongshan and Karabastau Formations from the Middle and Late Jurassic , respectively. In the Jiulongshan's Yanliao Biota, the neuropteran parasitoid lineage Mantispidae , the dipteran parasitoid lineages Nemestrinidae and Eremochaetidae , and the coleopteran parasitoid families Ripiphoridae and Staphylinidae are represented, though the staphylinid subfamilies known to contain parasitoid species are absent. Most notably, the Yanliao Biota contains the plant-associated sawfly clades Xyeloidea , Tenthredinoidea , Pamphilioidea , Cephoidea , Siricoidea , and Orussoidea , the latter being the only parasitoid sawfly lineage, and the apocritan parasitoid clades Evanioidea , Ephialtitoidea, and Proctotrupoidea , which belong to the hymenopteran order. In the Karabastau Formation, a similar family-level diversity of parasitoid hymenopterans is represented but with double the species diversity. Nemestrinids, acrocerids , and eremochaetids represent dipteran parasitoids from the Karabastau and mantispids represent neuropteran ones, with anthribids and staphylinids being represented among coleopteran parasitoids. The assemblage found in the Berriasian Lulworth Formation has also been studied and cited as evidence of the MMPR, as it contains twenty species of parasitoid apocritans, including megalyroids , evanioids, proctotrupoids, ichneumonoids , chrysidoids , and the enigmatic Apocrites .
Phase 2 of the MMPR, lasting from the Late Valanginian to the Albian, involved even further parasitoid diversification. In the Barremian Yixian Formation, the number of hymenopteran parasitoid lineages jumped to thirteen from the eight to nine found in the previous lagerstatten. Amongst evanioids, there were evaniids, praeaulacids, aulacids, and baissids. Ephialtitoids were represented by ephialtitids; Amongst procrotrupoids, the mesoserphids, helorids , pelecinids , roproniids , and serphids were represented. Ichneumonoids, chrysidoids, and vespoids were represented in the Yixian by ichneumonids, bethylonymids, and scoliids , respectively. Dipteran species diversity was the same as in the Jurassic lagerstatten and contained among the eremochaetids and nemestrinids. Thirty-seven parasitoid coleopterans were found, mainly among staphylinids but also among carabids , while nine species of mantispid neuropterans were found. [ 1 ]
The MMPR's ecological effects were reflected by the greater host specificity of gymnosperms as compared to angiosperms and ferns, as well as by the low rate of turnover and high degree of nestedness among insect herbivores that fed on gymnosperms during and following the MMPR. [ 3 ] | https://en.wikipedia.org/wiki/Mid-Mesozoic_Parasitoid_Revolution |
The midbody is a transient structure found in mammalian cells and is present near the end of cytokinesis just prior to the complete separation of the dividing cells. The structure was first described by Walther Flemming in 1891. [ 1 ]
The midbody structure contains bundles of microtubules derived from the mitotic spindle which compacts during the final stages of cell division. It has a typical diameter of 1 micrometre and a length of 3 to 5 micrometres. [ 2 ] Aside from microtubules it also contains various proteins involved in cytokinesis , asymmetric cell division , and chromosome segregation and RNAs.
The midbody is important for completing the final stages of cytokinesis, a process called abscission . [ 3 ] During symmetric abscission, the midbody is severed at each end and released into the cellular environment.
It was long assumed that the midbody was simply a structural part of cytokinesis, and was totally degraded with the completion of mitosis. However, it is now understood that post-abscission, the midbody is converted into an endosome -like signalling molecule, and can be internalised by nearby cells. [ 4 ]
This endosome is marked by MKLP1 , and can persist for up to 48 hours once internalised into another cell. [ 4 ] It is coated in Actin , which is slowly degraded by the internalising cell. | https://en.wikipedia.org/wiki/Midbody_(cell_biology) |
The Midcourse Space Experiment ( MSX ) is a Ballistic Missile Defense Organization (BMDO) satellite experiment ( unmanned space mission ) to map bright infrared sources in space. MSX offered the first system demonstration of technology in space to identify and track ballistic missiles during their midcourse flight phase. [ 1 ]
On 24 April 1996, the US Air Force launched the MSX satellite on a Delta II launch vehicle from Vandenberg AFB , California . MSX was placed in a Sun-synchronous orbit at 898 km and an inclination of 99.16 degrees. MSX's mission was to gather data in three spectral bands (long wavelength infrared, visible, and ultraviolet).
From 13 May 1998, MSX became a contributing sensor to the Space Surveillance Network .
Lottie Williams was exercising in a park in Tulsa on January 22, 1997, when she was hit in the shoulder by a 15-centimetre (6 in) piece of blackened metallic material. U.S. Space Command confirmed that a used Delta II rocket from the April 1996 launch of the Midcourse Space Experiment had re-entered into the atmosphere 30 minutes earlier. The object tapped her on the shoulder and fell off harmlessly onto the ground. Williams collected the item and NASA tests later showed that the fragment was consistent with the materials of the rocket, and Nicholas Johnson, the agency's chief scientist for orbital debris, believes that she was indeed hit by a piece of the rocket. [ 2 ]
Operational from 1996 to 1997, MSX mapped the galactic plane and areas either missed or identified as particularly bright by the Infrared Astronomical Satellite (IRAS) at wavelengths of 4.29 μm , 4.35 μm, 8.28 μm, 12.13 μm, 14.65 μm, and 21.3 μm.
It carried the 33-cm SPIRIT III infrared telescope and interferometer–spectrometer with solid hydrogen-cooled five line-scanned infrared focal plane arrays. [ 3 ]
Calibration of MSX posed a challenge for designers of the experiment, as baselines did not exist for the bands it would be observing under. Engineers solved the problem by having MSX fire projectiles of known composition in front of the detector, and calibrating the instruments to the known black-body curves of the objects. The MSX calibration serves as the basis for other satellites working in the same wavelength range, including AKARI (2006-2011) and the Spitzer Space Telescope (SST) .
MSX data is currently available in the Infrared Science Archive (IRSA) provided by NASA's Infrared Processing and Analysis Center (IPAC) . Collaborative efforts between the Air Force Research Laboratory and IPAC has resulted in an archive containing images for about 15 percent of the sky, including the entire Galactic Plane , the Large Magellanic Cloud , and regions of the sky missed by IRAS. [ 4 ] | https://en.wikipedia.org/wiki/Midcourse_Space_Experiment |
In civil engineering , the middle-third rule states that no tension is developed in a wall or foundation if the resultant force lies within the middle third of the structure.
The rule is covered by various standard texts in the field of civil engineering, for instance Principles of Foundation Engineering by B.M. Das. [ 1 ] The application of this rule is limited to foundations that are square or rectangular in plan . (For circular foundations a different rule, known as the Middle Quarter Rule applies).
This article about a civil engineering topic is a stub . You can help Wikipedia by expanding it . | https://en.wikipedia.org/wiki/Middle-third_rule |
The Middle Rio Grande Project manages water in the Albuquerque Basin of New Mexico , United States.
It includes major upgrades and extensions to the irrigation facilities built by the Middle Rio Grande Conservancy District and modifications to the channel of the Rio Grande to control sedimentation and flooding. The bulk of the work was done by the United States Bureau of Reclamation and the United States Army Corps of Engineers in the 1950s, but construction continued into the 1970s and maintenance is ongoing. The project is complementary to the San Juan–Chama Project , which transfers water from the San Juan River in the Colorado River Basin to the Rio Grande. Although distribution of water from the two projects is handled through separate allotments and contracts, there is some sharing of facilities including the river itself. The ecological impact on the river and the riparian zone was the subject of extended litigation after a group of environmentalists filed Rio Grande Silvery Minnow v. Bureau of Reclamation in 1999.
The Rio Grande valley from Taos Pueblo downstream to Socorro has been continuously settled for longer than any other part of the United States. The Pueblo Indians diverted water from the river for irrigation. Spanish settlers who arrived in the 17th century established a more extensive system of acequias , or shared irrigation canals. More settlers arrived after the region was ceded to the United States in 1848, particularly after the American Civil War (1861-1865). Irrigation peaked in 1880 with 1,248,000 acres (505,000 ha) of cultivated land in the stretch of valley from Cochiti to San Marcial . The extent of cultivation began to decline after this due to water shortage, floods and waterlogging caused by aggradation of the riverbed, a rising water table and poor drainage. [ 1 ]
The Middle Rio Grande Conservancy District was established in 1925 to address these problems. It ran into financial difficulties and asked the Bureau of Reclamation to help investigate the problems and rehabilitation the irrigation facilities. The Flood Control Act of 30 June 1948 approved the comprehensive plan for the project, and also directed the Bureau of Reclamation to look into methods of reducing non-beneficial use of water by phreatic vegetation in the Rio Grande flood plains and its main tributaries above Caballo Reservoir . The Bureau of Reclamation and the Corps of Engineers worked together to plan the project. The Flood Control Act of 17 May 1950 approved completion of the plan. The Bureau of Reclamation was responsible for rehabilitating the El Vado dam, the irrigation and drainage works and the river channel. The Corps of Engineers was responsible for building flood control reservoirs and flood protection levees. [ 1 ]
The Middle Rio Grande Project includes the river, dams, irrigation and drainage channels from Velarde south to the point where the river enters the Elephant Butte Reservoir . It also includes maintenance of the river near Truth or Consequences, New Mexico .
The irrigation facilities, originally built by the conservancy district, irrigate up to 89,652 acres (36,281 ha), and include 30,000 acres (12,000 ha) of Indian water rights lands.
The Bureau of Reclamation operates and maintains El Vado Dam and the river from Velarde to the Narrows of Elephant Butte Reservoir. The Middle Rio Grande Conservancy District
operates the irrigation facilities, including the three diversion dams. The Corps of Engineers operates and maintains Cochiti Dam. [ 1 ]
In 1934-1935 the conservancy district built the El Vado Dam on the Rio Chama about 160 miles (260 km) north of Albuquerque to store irrigation water for use in dry periods. In 1954-1955 the Bureau of Reclamation rehabilitated the dam, a rolled-gravel embankment with a steel membrane on the upstream face, 230 feet (70 m) high with a crest length of 1,326 feet (404 m). In 1965-1968 the Bureau of Reclamation built a new outlet works to handle additional water delivered by the San Juan–Chama Project . The reservoir has a capacity of 196,500 acre-feet (one acre foot equaling 43,560 cubic feet (1,233 m 3 )).
The dam feeds an 8,000 kilowatt hydroelectric power plant operated by Los Alamos County . [ 1 ]
In 1974-1975 the Cochiti Dam was constructed by the Corps of Engineers for flood control, inundating the former Cochiti Diversion Dam.
It also provides irrigation water to the Cochiti Division. [ 1 ]
The Bureau of Reclamation rehabilitated four diversion dams. Angostura Diversion Dam , rehabilitated in 1958, serves the Albuquerque Division. It is a concrete weir section 17 feet (5.2 m) high and 800 feet (240 m) long. Isleta Diversion Dam , rehabilitated in 1955, serves the Belen Division. It is a reinforced concrete structure 21 feet (6.4 m) high and 674 feet (205 m) long with 30 radial gates. San Acacia Diversion Dam , rehabilitated in 1957, serves the Socorro Division. It is 17 feet (5.2 m) high and 700 feet (210 m) long, with 29 radial gates.
The Cochiti Division was formerly served by the Cochiti Diversion Dam, rehabilitated in 1958, but is now supplied directly from Cochiti Dam. [ 1 ]
The distribution and drainage system includes 202 miles (325 km) of canals, of which about 6 miles (9.7 km) are concrete lined; 580 miles (930 km) of laterals, of which about 4 miles (6.4 km) are concrete lined; and 405 miles (652 km) of open and concrete pipe drains, most of which are open section. From 1953 to 1961 the Bureau of Reclamation undertook extensive rehabilitation of canals, laterals, drains, and acequias throughout the project. In 1951 the Bureau of Reclamation began construction of the low-flow conveyance channel between San Acacia Diversion Dam and the Narrows of Elephant Butte, completing the job in 1959.
In 1961 the Bureau of Reclamation completed modification of the headworks for the Socorro Main Canal north at San Acacia Diversion Dam.
In 1975 the canal was tied into Drain Unit No. 7 Extension and then to Drain Unit No. 7 system. [ 1 ]
Between 1954 and 1962 the Bureau of Reclamation undertook river realignment and improvement between Velarde and the mouth of the Rio Puerco . Maintenance along a 149-mile (240 km) stretch of the river to control floods and reduce non-beneficial use of water through evapotranspiration is an ongoing requirement. The lengths of river maintained are 18 miles (29 km) in the Espanola area, 8 miles (13 km) in the Cochiti area, 24 miles (39 km) in the Albuquerque area, 28 miles (45 km) in the Belen area, 37 miles (60 km) in the Socorro area, 33 miles (53 km) in the San Marcial area and 1 mile (1.6 km) in the Truth or Consequences areas. Maintenance activities include clearing sediment plugs, pilot channeling, jetty installation, and maintaining the low-flow channel. The Bureau of Reclamation has been using alternative methods of channel maintenance since the late 1980s in an effort to improve the quality of the riverine and riparian habitats. [ 1 ]
Rehabilitation of the irrigation system throughout the project has resulted in a more stable water supply to about 90,000 acres (36,000 ha) of irrigated land, including water for the six southern Indian pueblos of Cochiti, Santo Domingo, San Felipe, Santa Ana, Sandia, and Isleta, all of which are served by the Middle Rio Grande Conservancy District.
This supports cultivation of alfalfa, barley, wheat, oats, corn, fruits and vegetables. The river maintenance program, coupled with the Corps of Engineers' flood control dams and system of levees, has greatly reduced the threat of uncontrolled flooding in the Middle Rio Grande Valley. [ 1 ]
Stabilization of the river channel through clearing, pilot channels, and jetty fields has resulted in the establishment of large wooded riparian areas called the bosque. Previously, large stands of trees were destroyed during heavy runoff years because the river meandered back and forth across the channel from levee to levee. The areas between the cleared floodway and the riverside levees are now filled with a permanent stand of large trees and other dense growths of vegetation. The invasion of nonnative species, as well as the lack of native tree regeneration, is of environmental concern. [ 1 ]
Citations
Sources
This article incorporates public domain material from websites or documents of the United States Bureau of Reclamation . | https://en.wikipedia.org/wiki/Middle_Rio_Grande_Project |
A middle ear implant is a hearing device that is surgically implanted into the middle ear . They help people with conductive, sensorineural or mixed hearing loss to hear. [ 1 ]
Middle ear implants work by improving the conduction of sound vibrations from the middle ear to the inner ear . There are two types of middle ear devices: active and passive. Active middle ear implants (AMEI) consist of an external audio processor and an internal implant, which actively vibrates the structures of the middle ear. [ 2 ] Passive middle ear implants (PMEIs) are sometimes known as ossicular replacement prostheses, TORPs or PORPs. They replace damaged or missing parts of the middle ear, creating a bridge between the outer ear and the inner ear, so that sound vibrations can be conducted through the middle ear and on to the cochlea. Unlike AMEIs, PMEIs contain no electronics and are not powered by an external source.
PMEIs are the usual first-line surgical treatment for conductive hearing loss, due to their lack of external components and cost-effectiveness. However, each patient is assessed individually as to whether an AMEI or PMEI would bring more benefit. This is especially true if the patient has already had several surgeries with PMEIs.
An active middle ear implant (AMEI) has two parts: an internal implant and an external audio processor. The microphone of the audio processor picks up sounds from the environment. The processor then converts these acoustic signals into digital signals and sends them to the implant through the skin. The implant sends the signals to the Floating Mass Transducer (FMT): a small vibratory part that is surgically fixed either on one of the three ossicles or against the round window of the cochlea . The FMT vibrates and sends sound vibrations to the cochlea. The cochlea converts these vibrations into nerve signals and sends them to the brain, where they are interpreted as sound. [ 3 ]
AMEIs are intended for patients with mild-to-severe sensorineural hearing loss, as well as those with conductive or mixed hearing loss. They can be used by adults and children over the age of 5. [ 2 ]
An AMEI can be beneficial for patients with mild-to-severe sensorineural hearing loss who have an intact ossicular chain and healthy middle ear, but who either cannot wear hearing aids or who do not get sufficient benefit from them. [ 2 ] Reasons for not being able to wear hearing aids include earmold allergies , skin problems, narrow, collapsed or closed ear canals , or malformed ears. [ 1 ] In cases of sensorineural hearing loss, the FMT is usually attached to the incus . [ 2 ]
An AMEI is also indicated for patients with conductive or mixed hearing loss with bone conduction thresholds from 45 dB in the low frequencies to 65 dB in the high frequencies. In these cases, the FMT can be coupled to various parts of the middle ear, depending on the patient's pathology :
AMEIs have been shown by several studies to be equal or superior to both hearing aids and bone conduction implants. Lee et al used the PBmax test to study speech intelligibility in patients before and after receiving an AMEI. All patients had used hearing aids pre-implantation. The researchers found that speech intelligibility improved with the AMEI, particularly in patients with a down-sloping hearing loss. [ 4 ] These findings were supported by Iwasaki et al, who found that both speech intelligibility and quality of life improved after implantation with an AMEI, applied to the round window. [ 5 ]
AMEIs can also offer improved hearing performance over bone conduction implants for patients with mixed hearing loss. Mojallal et al found that patients whose mixed hearing loss was treated with an AMEI experienced both better word recognition and speech understanding in noise than those who received a bone conduction implant, providing that their bone conduction pure-tone average (0.5 to 4 kHz) was poorer than 35 dB HL. [ 6 ]
Passive middle ear implants (PMEI) are ossicular replacement prostheses designed to replace some or all of the ossicular chain in the middle ear. They create a bridge between the outer ear and the inner ear, so that sound vibrations can be conducted through the middle ear and on to the cochlea
There are two types of PMEIs: tympanoplasty implants and stapes implants. Tympanoplasty implants (also known as PORPs or TORPs) are suitable for patients with a mobile stapes footplate, ie. a stapes footplate that moves in the normal way. Either a partial or a total tympanoplasty implant can be used, depending on the condition of the stapes. If the stapes is fixed and cannot transfer vibrations to the inner ear, then a stapes implant would be used. [ 7 ]
PMEIs are made from different materials including titanium, teflon, hydroxylapatite, platinum, and nitinol, all of which are suitable for use within the human body. Titanium implants can safely undergo MRIs of up to 7.0 Tesla. [ 7 ]
The tympanoplasty implant is indicated in cases of congenital or acquired defects of the ossicular chain, due to e.g.:
It can also be used to treat patients with inadequate conductive hearing from previous middle ear surgery.
The stapesplasty prosthesis is indicated in cases of congenital or acquired defects of the stapes due to e.g.:
It can also be used to treat patients with inadequate conductive hearing from previous stapes surgery. | https://en.wikipedia.org/wiki/Middle_ear_implant |
The middle lamella is a layer that cements together the primary cell walls of two adjoining plant cells . It is the first formed layer to be deposited at the time of cytokinesis . [ 1 ] [ page needed ] The cell plate that is formed during cell division itself develops into middle lamella or lamellum. The middle lamella is made up of calcium and magnesium pectates . [ 2 ] [ better source needed ] In a mature plant cell it is the outermost layer of cell wall. [ 3 ] [ page needed ] [ 4 ] [ page needed ]
In plants, the pectins form a unified and continuous layer between adjacent cells. Frequently, it is difficult to distinguish the middle lamella from the primary wall, especially in cells that develop thick secondary walls. In such cases, the two adjacent primary walls and the middle lamella, and perhaps the first layer of the secondary wall of each cell, may be called a compound middle lamella. When the middle lamella is degraded by enzymes, as happens during fruit ripening and abscission , the adjacent cells will separate. [ 5 ] [ page needed ]
2.Telugu Akademi Hyderabad "Intermediate first year Botany" [ full citation needed ]
This plant morphology article is a stub . You can help Wikipedia by expanding it .
This cell biology article is a stub . You can help Wikipedia by expanding it . | https://en.wikipedia.org/wiki/Middle_lamella |
Middleware in the context of distributed applications is software that provides services beyond those provided by the operating system to enable the various components of a distributed system to communicate and manage data. Middleware supports and simplifies complex distributed applications . It includes web servers , application servers , messaging and similar tools that support application development and delivery. Middleware is especially integral to modern information technology based on XML , SOAP , Web services , and service-oriented architecture .
Middleware often enables interoperability between applications that run on different operating systems, by supplying services so the application can exchange data in a standards-based way. Middleware sits "in the middle" between application software that may be working on different operating systems . It is similar to the middle layer of a three-tier single system architecture, except that it is stretched across multiple systems or applications. Examples include EAI software, telecommunications software, transaction monitors , and messaging-and-queueing software.
The distinction between operating system and middleware functionality is, to some extent, arbitrary. While core kernel functionality can only be provided by the operating system itself, some functionality previously provided by separately sold middleware is now integrated in operating systems. A typical example is the TCP/IP stack for telecommunications, nowadays included virtually in every operating system.
Middleware is defined as software that provides a link between separate software applications. It is sometimes referred to as plumbing because it connects two applications and passes data between them. Middleware allows data contained in one database to be accessed through another. This makes it particularly useful for enterprise application integration and data integration tasks.
In more abstract terms, middleware is "The software layer that lies between the operating system and applications on each side of a distributed computing system in a network." [ 1 ]
Middleware gained popularity in the 1980s as a solution to the problem of how to link newer applications to older legacy systems, although the term had been in use since 1968. [ 2 ] It also facilitated distributed processing , the connection of multiple applications to create a larger application, usually over a network.
Middleware services provide a more functional set of application programming interfaces to allow an application to:
when compared to the operating system and network services.
Middleware offers some unique technological advantages for business and industry. For example, traditional database systems are usually deployed in closed environments where users access the system only via a restricted network or intranet (e.g., an enterprise’s internal network). With the phenomenal growth of the World Wide Web , users can access virtually any database for which they have proper access rights from anywhere in the world. Middleware addresses the problem of varying levels of interoperability among different database structures. Middleware facilitates transparent access to legacy database management systems (DBMSs) or applications via a web server without regard to database-specific characteristics. [ 3 ]
Businesses frequently use middleware applications to link information from departmental databases, such as payroll, sales, and accounting, or databases housed in multiple geographic locations. [ 4 ] In the highly competitive healthcare community, laboratories make extensive use of middleware applications for data mining , laboratory information system (LIS) backup, and to combine systems during hospital mergers. Middleware helps bridge the gap between separate LISs in a newly formed healthcare network following a hospital buyout. [ 5 ]
Middleware can help software developers avoid having to write application programming interfaces (API) for every control program, by serving as an independent programming interface for their applications.
For Future Internet network operation through traffic monitoring in multi-domain scenarios , using mediator tools (middleware) is a powerful help since they allow operators , searchers and service providers to supervise Quality of service and analyse eventual failures in telecommunication services . [ 6 ] The Middleware stack is devised of several components (CSMS, TV Statistics & Client applications). It is known as the software brains of OTT platforms as it controls and interconnects all the components of the solution. The Content and Subscriber Management System (CSMS) is the central part of the solution commonly referred to as an administration portal. Apart from being the main interface for operator personnel to administer the TV service (Subscribers, Content, Packages, etc.) it also controls the majority of TV services and interacts with streaming & CDN and DRM serves to deliver Live, VOD and recorded content to the end users. It also integrates with external systems for billing, provisioning and with EPG and VOD content providers. Client applications authorize the CSMS and communicate with it, to provide required TV services to the end users on different devices. [ 7 ]
Finally, e-commerce uses middleware to assist in handling rapid and secure transactions over many different types of computer environments. [ 8 ] In short, middleware has become a critical element across a broad range of industries, thanks to its ability to bring together resources across dissimilar networks or computing platforms.
In 2004 members of the European Broadcasting Union (EBU) carried out a study of Middleware with respect to system integration in broadcast environments. This involved system design engineering experts from 10 major European broadcasters working over a 12-month period to understand the effect of predominantly software-based products to media production and broadcasting system design techniques. The resulting reports Tech 3300 and Tech 3300s were published and are freely available from the EBU web site. [ 9 ] [ 10 ]
Message-oriented middleware (MOM) [ 11 ] is middleware where transactions or event notifications are delivered between disparate systems or components by way of messages, often via an enterprise messaging system . With MOM, messages sent to the client are collected and stored until they are acted upon, while the client continues with other processing.
[ 13 ] Intelligent Middleware (IMW) provides real-time intelligence and event management through intelligent agents . The IMW manages the real-time processing of high volume sensor signals and turns these signals into intelligent and actionable business information. The actionable information is then delivered in end-user power dashboards to individual users or is pushed to systems within or outside the enterprise. It is able to support various heterogeneous types of hardware and software and provides an API for interfacing with external systems. It should have a highly scalable, distributed architecture which embeds intelligence throughout the network to transform raw data systematically into actionable and relevant knowledge. It can also be packaged with tools to view and manage operations and build advanced network applications most effectively.
Content-centric middleware offers a simple provider-consumer abstraction through which applications can issue requests for uniquely identified content, without worrying about where or how it is obtained. Juno is one example, which allows applications to generate content requests associated with high-level delivery requirements. [ 14 ] The middleware then adapts the underlying delivery to access the content from sources that are best suited to matching the requirements. This is therefore similar to Publish/subscribe middleware, as well as the Content-centric networking paradigm.
Policy appliance is a generic term referring to any form of middleware that manages policy rules. They can mediate between data owners or producers, data aggregators, and data users. Among heterogeneous institutional systems or networks they may be used to enforce, reconcile, and monitor agreed information management policies and laws across systems (or between jurisdictions) with divergent information policies or needs. Policy appliances can interact with smart data (data that carries with it contextual relevant terms for its own use), intelligent agents (queries that are self-credentialed, authenticating, or contextually adaptive), or context-aware applications to control information flows, protect security and confidentiality, and maintain privacy. Policy appliances support policy-based information management processes by enabling rules-based processing, selective disclosure, and accountability and oversight. [ 15 ]
Examples of policy appliance technologies for rules-based processing include analytic filters, contextual search , semantic programs, labeling and wrapper tools, and DRM , among others; policy appliance technologies for selective disclosure include anonymization, content personalization, subscription and publishing tools, among others; and, policy appliance technologies for accountability and oversight include authentication , authorization, immutable and non-repudiable logging, and audit tools, among others.
Other sources [ citation needed ] include these additional classifications:
IBM , Red Hat , Oracle Corporation and Microsoft are some of the vendors that provide middleware software. Vendors such as Axway , SAP , TIBCO , Informatica , Objective Interface Systems , Pervasive , ScaleOut Software and webMethods were specifically founded to provide more niche middleware solutions. Groups such as the Apache Software Foundation , OpenSAF , the ObjectWeb Consortium (now OW2) and OASIS' AMQP encourage the development of open source middleware. Microsoft .NET "Framework" architecture is essentially "Middleware" with typical middleware functions distributed between the various products, with most inter-computer interaction by industry standards, open APIs or RAND software licence. Solace provides middleware in purpose-built hardware for implementations that may experience scale. StormMQ provides Message Oriented Middleware as a service. | https://en.wikipedia.org/wiki/Middleware_(distributed_applications) |
Alpine borane is the commercial name for an organoboron compound that is used in organic synthesis . It is a colorless liquid, although it is usually encountered as a solution. A range of alkyl-substituted borane are specialty reagents in organic synthesis. Two such reagents that are closely related to Alpine borane are 9-BBN and diisopinocampheylborane .
This reagent is generated by treating 9-BBN with α-pinene . [ 2 ]
This sterically crowded chiral trialkylborane can stereoselectively reduce aldehydes in what is known as the Midland Alpine borane reduction , or simply the Midland reduction. [ 3 ]
Hydrolysis of the resulting borinic ester affords the alcohol:
It is also effective for the stereoselective reduction of certain acetylenic ketones. [ 4 ] The reaction is proposed to involve formation of an adduct by coordination of the carbonyl oxygen to boron. Intramolecular hydride transfer from the pinane substituent to the carbonyl carbon ensues. Many substrates for the Midland reduction have a low steric group such as an alkyne [ 5 ] or a nitrile [ 6 ] so as to increase selectivity. Stereochemical control comes from coordination of the carbonyl bulky borane, followed by hydride transfer opposite the largest group. [ 2 ] [ 7 ] | https://en.wikipedia.org/wiki/Midland_Alpine_borane_reduction |
In human genetics the midparent value of a trait is defined as the average of the trait value of the father and a scaled version of that of the mother. This value can be used in a study to analyze the data set without heeding sex effects. Studying quantitative traits in heritability studies may be complicated by sex differences observed for the trait.
Well-known examples include studies of humans' height, whose midparent value h mp is given by: [ 1 ]
where h f is the father's height, and h m the mother's.
The coefficient 1.08 serves as a scaling factor . After the 1.08 scaling, the mean of the mother's height is the same as that of the father's, and the variance is closer to the father's; in this way, sex difference can be ignored.
This genetics article is a stub . You can help Wikipedia by expanding it . | https://en.wikipedia.org/wiki/Midparent |
In geometry , the midpoint is the middle point of a line segment . It is equidistant from both endpoints, and it is the centroid both of the segment and of the endpoints. It bisects the segment.
The midpoint of a segment in n -dimensional space whose endpoints are A = ( a 1 , a 2 , … , a n ) {\displaystyle A=(a_{1},a_{2},\dots ,a_{n})} and B = ( b 1 , b 2 , … , b n ) {\displaystyle B=(b_{1},b_{2},\dots ,b_{n})} is given by
That is, the i th coordinate of the midpoint ( i = 1, 2, ..., n ) is
Given two points of interest, finding the midpoint of the line segment they determine can be accomplished by a compass and straightedge construction . The midpoint of a line segment, embedded in a plane , can be located by first constructing a lens using circular arcs of equal (and large enough) radii centered at the two endpoints, then connecting the cusps of the lens (the two points where the arcs intersect). The point where the line connecting the cusps intersects the segment is then the midpoint of the segment. It is more challenging to locate the midpoint using only a compass, but it is still possible according to the Mohr-Mascheroni theorem . [ 1 ]
The abovementioned formulas for the midpoint of a segment implicitly use the lengths of segments. However, in the generalization to affine geometry , where segment lengths are not defined, [ 5 ] the midpoint can still be defined since it is an affine invariant . The synthetic affine definition of the midpoint M of a segment AB is the projective harmonic conjugate of the point at infinity , P , of the line AB . That is, the point M such that H[ A , B ; P , M ] . [ 6 ] When coordinates can be introduced in an affine geometry, the two definitions of midpoint will coincide. [ 7 ]
The midpoint is not naturally defined in projective geometry since there is no distinguished point to play the role of the point at infinity (any point in a projective range may be projectively mapped to any other point in (the same or some other) projective range). However, fixing a point at infinity defines an affine structure on the projective line in question and the above definition can be applied.
The definition of the midpoint of a segment may be extended to curve segments , such as geodesic arcs on a Riemannian manifold . Note that, unlike in the affine case, the midpoint between two points may not be uniquely determined. | https://en.wikipedia.org/wiki/Midpoint |
The midsternal line is used to describe a part of the surface anatomy of the anterior thorax . The midsternal line runs vertical down the middle of the sternum .
It can be interpreted as a component of the median plane .
This article incorporates text in the public domain from page 1309 of the 20th edition of Gray's Anatomy (1918)
This anatomy article is a stub . You can help Wikipedia by expanding it . | https://en.wikipedia.org/wiki/Midsternal_line |
The Midwest Consortium for Hazardous Waste Worker Training provides training to workers who may be exposed to hazardous materials while performing jobs covered by the Occupational Safety and Health Administration ’s (OSHA) Hazardous Waste Operations and Emergency Response ( HAZWOPER ) standard, and to help employers comply with OSHA standard 29 CFR 1910.120.
The consortium has been funded since 1987 by the National Institute for Environmental Health Sciences ( NIEHS ) to develop, present and evaluate model worker training programs in nine Midwestern states (Illinois, Indiana, Kentucky, Michigan, Minnesota, Ohio, Tennessee, Wisconsin, and North Dakota). [ 1 ] Professor Carol Rice, Ph.D., CIH ( http://www.eh.uc.edu/dir_individual_details.asp?qcontactid=85 ), at the University of Cincinnati ( http://www.uc.edu ), is the Principal Investigator.
The consortium's specific aims are to serve the needs of the region through interactive, hands-on training developed to meet the needs of adult learners employed in jobs covered by HAZWOPER ; to document the change in and retention of knowledge and skills as a result of training; to evaluate the impact of training and residents after return to the workplace; to provide training in communities where hazardous materials exposures may occur; and to fully integrate advanced training technologies into program content and delivery. | https://en.wikipedia.org/wiki/Midwest_Consortium_for_Hazardous_Waste_Worker_Training |
In mathematics , Midy's theorem , named after French mathematician E. Midy, [ 1 ] is a statement about the decimal expansion of fractions a / p where p is a prime and a / p has a repeating decimal expansion with an even period (sequence A028416 in the OEIS ). If the period of the decimal representation of a / p is 2 n , so that
a p = 0. a 1 a 2 a 3 … a n a n + 1 … a 2 n ¯ {\displaystyle {\frac {a}{p}}=0.{\overline {a_{1}a_{2}a_{3}\dots a_{n}a_{n+1}\dots a_{2n}}}}
then the digits in the second half of the repeating decimal period are the 9s complement of the corresponding digits in its first half. In other words,
a i + a i + n = 9 {\displaystyle a_{i}+a_{i+n}=9} a 1 … a n + a n + 1 … a 2 n = 10 n − 1. {\displaystyle a_{1}\dots a_{n}+a_{n+1}\dots a_{2n}=10^{n}-1.}
For example,
1 13 = 0. 076923 ¯ and 076 + 923 = 999. {\displaystyle {\frac {1}{13}}=0.{\overline {076923}}{\text{ and }}076+923=999.} 1 17 = 0. 0588235294117647 ¯ and 05882352 + 94117647 = 99999999. {\displaystyle {\frac {1}{17}}=0.{\overline {0588235294117647}}{\text{ and }}05882352+94117647=99999999.}
If k is any divisor of h (where h is the number of digits of the period of the decimal expansion of a / p (where p is again a prime)), then Midy's theorem can be generalised as follows. The extended Midy's theorem [ 2 ] states that if the repeating portion of the decimal expansion of a / p is divided into k -digit numbers, then their sum is a multiple of 10 k − 1.
For example, 1 19 = 0. 052631578947368421 ¯ {\displaystyle {\frac {1}{19}}=0.{\overline {052631578947368421}}} has a period of 18. Dividing the repeating portion into 6-digit numbers and summing them gives 052631 + 578947 + 368421 = 999999. {\displaystyle 052631+578947+368421=999999.} Similarly, dividing the repeating portion into 3-digit numbers and summing them gives 052 + 631 + 578 + 947 + 368 + 421 = 2997 = 3 × 999. {\displaystyle 052+631+578+947+368+421=2997=3\times 999.}
Midy's theorem and its extension do not depend on special properties of the decimal expansion, but work equally well in any base b , provided we replace 10 k − 1 with b k − 1 and carry out addition in base b .
For example, in octal
1 19 = 0. 032745 ¯ 8 032 8 + 745 8 = 777 8 03 8 + 27 8 + 45 8 = 77 8 . {\displaystyle {\begin{aligned}&{\frac {1}{19}}=0.{\overline {032745}}_{8}\\[8pt]&032_{8}+745_{8}=777_{8}\\[8pt]&03_{8}+27_{8}+45_{8}=77_{8}.\end{aligned}}}
In dozenal (using inverted two and three for ten and eleven, respectively)
Short proofs of Midy's theorem can be given using results from group theory . However, it is also possible to prove Midy's theorem using elementary algebra and modular arithmetic :
Let p be a prime and a / p be a fraction between 0 and 1. Suppose the expansion of a / p in base b has a period of ℓ , so
a p = [ 0. a 1 a 2 … a ℓ ¯ ] b ⇒ a p b ℓ = [ a 1 a 2 … a ℓ . a 1 a 2 … a ℓ ¯ ] b ⇒ a p b ℓ = N + [ 0. a 1 a 2 … a ℓ ¯ ] b = N + a p ⇒ a p = N b ℓ − 1 {\displaystyle {\begin{aligned}&{\frac {a}{p}}=[0.{\overline {a_{1}a_{2}\dots a_{\ell }}}]_{b}\\[6pt]&\Rightarrow {\frac {a}{p}}b^{\ell }=[a_{1}a_{2}\dots a_{\ell }.{\overline {a_{1}a_{2}\dots a_{\ell }}}]_{b}\\[6pt]&\Rightarrow {\frac {a}{p}}b^{\ell }=N+[0.{\overline {a_{1}a_{2}\dots a_{\ell }}}]_{b}=N+{\frac {a}{p}}\\[6pt]&\Rightarrow {\frac {a}{p}}={\frac {N}{b^{\ell }-1}}\end{aligned}}}
where N is the integer whose expansion in base b is the string a 1 a 2 ... a ℓ .
Note that b ℓ − 1 is a multiple of p because ( b ℓ − 1) a / p is an integer. Also b n −1 is not a multiple of p for any value of n less than ℓ , because otherwise the repeating period of a / p in base b would be less than ℓ .
Now suppose that ℓ = hk . Then b ℓ − 1 is a multiple of b k − 1. (To see this, substitute x for b k ; then b ℓ = x h and x − 1 is a factor of x h − 1. ) Say b ℓ − 1 = m ( b k − 1), so
a p = N m ( b k − 1 ) . {\displaystyle {\frac {a}{p}}={\frac {N}{m(b^{k}-1)}}.}
But b ℓ − 1 is a multiple of p ; b k − 1 is not a multiple of p (because k is less than ℓ ); and p is a prime; so m must be a multiple of p and
a m p = N b k − 1 {\displaystyle {\frac {am}{p}}={\frac {N}{b^{k}-1}}}
is an integer. In other words,
N ≡ 0 ( mod b k − 1 ) . {\displaystyle N\equiv 0{\pmod {b^{k}-1}}.}
Now split the string a 1 a 2 ... a ℓ into h equal parts of length k , and let these represent the integers N 0 ... N h − 1 in base b , so that
N h − 1 = [ a 1 … a k ] b N h − 2 = [ a k + 1 … a 2 k ] b ⋮ N 0 = [ a l − k + 1 … a l ] b {\displaystyle {\begin{aligned}N_{h-1}&=[a_{1}\dots a_{k}]_{b}\\N_{h-2}&=[a_{k+1}\dots a_{2k}]_{b}\\&{}\ \ \vdots \\N_{0}&=[a_{l-k+1}\dots a_{l}]_{b}\end{aligned}}}
To prove Midy's extended theorem in base b we must show that the sum of the h integers N i is a multiple of b k − 1.
Since b k is congruent to 1 modulo b k − 1, any power of b k will also be congruent to 1 modulo b k − 1. So
N = ∑ i = 0 h − 1 N i b i k = ∑ i = 0 h − 1 N i ( b k ) i {\displaystyle N=\sum _{i=0}^{h-1}N_{i}b^{ik}=\sum _{i=0}^{h-1}N_{i}(b^{k})^{i}} ⇒ N ≡ ∑ i = 0 h − 1 N i ( mod b k − 1 ) {\displaystyle \Rightarrow N\equiv \sum _{i=0}^{h-1}N_{i}{\pmod {b^{k}-1}}} ⇒ ∑ i = 0 h − 1 N i ≡ 0 ( mod b k − 1 ) {\displaystyle \Rightarrow \sum _{i=0}^{h-1}N_{i}\equiv 0{\pmod {b^{k}-1}}}
which proves Midy's extended theorem in base b .
To prove the original Midy's theorem, take the special case where h = 2. Note that N 0 and N 1 are both represented by strings of k digits in base b so both satisfy
0 ≤ N i ≤ b k − 1. {\displaystyle 0\leq N_{i}\leq b^{k}-1.}
N 0 and N 1 cannot both equal 0 (otherwise a / p = 0) and cannot both equal b k − 1 (otherwise a / p = 1), so
0 < N 0 + N 1 < 2 ( b k − 1 ) {\displaystyle 0<N_{0}+N_{1}<2(b^{k}-1)}
and since N 0 + N 1 is a multiple of b k − 1, it follows that
N 0 + N 1 = b k − 1. {\displaystyle N_{0}+N_{1}=b^{k}-1.}
From the above, a m p {\displaystyle {\frac {am}{p}}} is an integer
Thus m ≡ 0 ( mod p ) {\displaystyle m\equiv 0{\pmod {p}}}
And thus for k = ℓ 2 {\displaystyle k={\frac {\ell }{2}}}
b ℓ / 2 + 1 ≡ 0 ( mod p ) {\displaystyle b^{\ell /2}+1\equiv 0{\pmod {p}}}
For k = ℓ 3 {\displaystyle k={\frac {\ell }{3}}} and is an integer
b 2 ℓ / 3 + b ℓ / 3 + 1 ≡ 0 ( mod p ) {\displaystyle b^{2\ell /3}+b^{\ell /3}+1\equiv 0{\pmod {p}}}
and so on. | https://en.wikipedia.org/wiki/Midy's_theorem |
The Mie potential is an interaction potential describing the interactions between particles on the atomic level. It is mostly used for describing intermolecular interactions, but at times also for modeling intramolecular interaction, i.e. bonds.
The Mie potential is named after the German physicist Gustav Mie ; [ 1 ] yet the history of intermolecular potentials is more complicated. [ 2 ] [ 3 ] [ 4 ] The Mie potential is the generalized case of the Lennard-Jones (LJ) potential , which is perhaps the most widely used pair potential. [ 5 ] [ 6 ]
The Mie potential V ( r ) {\displaystyle V(r)} is a function of r {\displaystyle r} , the distance between two particles, and is written as [ 7 ]
V ( r ) = C ε [ ( σ r ) n − ( σ r ) m ] , ( 1 ) {\displaystyle V(r)=C\,\varepsilon \left[\left({\frac {\sigma }{r}}\right)^{n}-\left({\frac {\sigma }{r}}\right)^{m}\right],~~~~~~(1)}
with
C = n n − m ( n m ) m n − m {\displaystyle C={\frac {n}{n-m}}\left({\frac {n}{m}}\right)^{\frac {m}{n-m}}} .
The Lennard-Jones potential corresponds to the special case where n = 12 {\textstyle n=12} and m = 6 {\textstyle m=6} in Eq. (1).
In Eq. (1), ε {\displaystyle \varepsilon } is the dispersion energy, and σ {\displaystyle \sigma } indicates the distance at which V = 0 {\displaystyle V=0} , which is sometimes called the "collision radius." The parameter σ {\textstyle \sigma } is generally indicative of the size of the particles involved in the collision. The parameters n {\textstyle n} and m {\textstyle m} characterize the shape of the potential: n {\textstyle n} describes the character of the repulsion and m {\textstyle m} describes the character of the attraction.
The attractive exponent m = 6 {\textstyle m=6} is physically justified by the London dispersion force , [ 4 ] whereas no justification for a certain value for the repulsive exponent is known. The repulsive steepness parameter n {\textstyle n} has a significant influence on the modeling of thermodynamic derivative properties, e.g. the compressibility and the speed of sound . Therefore, the Mie potential is a more flexible intermolecular potential than the simpler Lennard-Jones potential.
The Mie potential is used today in many force fields in molecular modeling . Typically, the attractive exponent is chosen to be m = 6 {\textstyle m=6} , whereas the repulsive exponent is used as an adjustable parameter during the model fitting.
As for the Lennard-Jonesium , where a theoretical substance exists that is defined by particles interacting by the Lennard-Jones potential, a substance class of Mie substances exists that are defined as single site spherical particles interacting by a given Mie potential. Since an infinite number of Mie potentials exist (using different n, m parameters), equally many Mie substances exist, as opposed to Lennard-Jonesium, which is uniquely defined. For practical applications in molecular modelling , the Mie substances are mostly relevant for modelling small molecules, e.g. noble gases , and for coarse grain modelling , where larger molecules, or even a collection of molecules, are simplified in their structure and described by a single Mie particle. However, more complex molecules, such as long-chained alkanes , have successfully been modelled as homogeneous chains of Mie particles. [ 8 ] As such, the Mie potential is useful for modelling far more complex systems than those whose behaviour is accurately captured by "free" Mie particles.
Thermophysical properties of both the Mie fluid, and chain molecules built from Mie particles have been the subject of numerous papers in recent years. Investigated properties include virial coefficients [ 9 ] and interfacial , [ 10 ] vapor-liquid equilibrium , [ 11 ] [ 12 ] [ 13 ] [ 14 ] and transport properties. [ 15 ] Based on such studies the relation between the shape of the interaction potential (described by n and m ) and the thermophysical properties has been elucidated.
Also, many theoretical (analytical) models have been developed for describing thermophysical properties of Mie substances and chain molecules formed from Mie particles, such as several thermodynamic equations of state [ 8 ] [ 16 ] [ 17 ] and models for transport properties. [ 18 ]
It has been observed that many combinations of different ( n , m {\displaystyle n,m} ) can yield similar phase behaviour , [ 19 ] and that this degeneracy is captured by the parameter
α = C [ 1 m − 3 − 1 n − 3 ] {\displaystyle \alpha =C\left[{\frac {1}{m-3}}-{\frac {1}{n-3}}\right]} ,
where fluids with different exponents, but the same α {\displaystyle \alpha } -parameter will exhibit the same phase behavior. [ 19 ]
Due to its flexibility, the Mie potential is a popular choice for modelling real fluids in force fields. It is used as an interaction potential many molecular models today. Several (reliable) united atom transferable force fields are based on the Mie potential, such as that developed by Potoff and co-workers. [ 20 ] [ 21 ] [ 22 ] The Mie potential has also been used for coarse-grain modeling. [ 23 ] Electronic tools are available for building Mie force field models for both united atom force fields and transferable force fields. [ 24 ] [ 23 ] The Mie potential has also been used for modeling small spherical molecules (i.e. directly the Mie substance - see above). The Table below gives some examples. There, the molecular models have only the parameters of the Mie potential itself. | https://en.wikipedia.org/wiki/Mie_potential |
Mieczysław Kwiryn Biernacki ( Polish pronunciation: [mjɛˈt͡ʂɨs.waf bjɛrˈnat͡s.k] ; 30 March 1891 – 21 November 1959) was a Polish mathematical chemist . [ 1 ] He fought in World War I in the French Army and later in the forces of Polish general Józef Haller .
This article about a Polish scientist is a stub . You can help Wikipedia by expanding it .
This biographical article about a chemist is a stub . You can help Wikipedia by expanding it . | https://en.wikipedia.org/wiki/Mieczysław_Biernacki |
Miedema's model is a semi-empirical approach for estimating the heat of formation of solid or liquid metal alloys and compounds in the framework of thermodynamic calculations for metals and minerals. [ 1 ] It was developed by the Dutch scientist Andries Rinse Miedema (15 November 1933 – 28 May 1992) [ 2 ] while working at Philips Natuurkundig Laboratorium . It may provide or confirm basic enthalpy data needed for the calculation of phase diagrams of metals, via CALPHAD or ab initio quantum chemistry methods . For a binary system composed by elements A and B, a generic Miedema Formula could be cast as Δ H = f ( E l e m e n t A , P h i A , n W S A , V A , E l e m e n t B . P h i B , n w S B , V B ) {\displaystyle \Delta H=f(ElementA,PhiA,nWSA,VA,ElementB.PhiB,nwSB,VB)} where terms Phi and nwS are explained and reported below.
For a binary system the physical picture could be simplified by considering a relatively simpler function of the difference of these three physical parameters Δ H = f ( P h i A − P h i B , n W S A − n W S B , V A − V B ) {\displaystyle \Delta H=f(PhiA-PhiB,nWSA-nWSB,VA-VB)} resulting in a more complex form
D e l t a H = x [ A ] ∗ ( 2 ∗ f [ A B ] ∗ V [ A , a l l o y ] ( 2 / 3 ) ∗ ( − P ∗ D e l t a P h i 2 + Q ∗ D e l t a n W S 2 − R ) / ( 1 / 3 ∗ n W S [ A ] + 1 / 3 ∗ n W S [ B ] ) + d e l t a H [ t r a n s ] ) {\displaystyle DeltaH=x[A]*(2*f[AB]*V[A,alloy]^{(}2/3)*(-P*DeltaPhi^{2}+Q*DeltanWS^{2}-R)/(1/3*nWS[A]+1/3*nWS[B])+deltaH[trans])} [ 3 ]
Miedema introduced his approach in several papers, beginning in 1973 in Philips Technical Review Magazine with "A simple model for alloys". [ 4 ] [ 5 ]
Miedema described his motivation with "Reliable rules for the alloying behaviour of metals have long been sought. There is the qualitative rule that states that the greater the difference in the electronegativity of two metals, the greater the heat of formation - and hence the stability. Then there is the Hume-Rothery rule , which states that two metals that differ by more than 15% in their atomic radius will not form substitutional solid solutions. This rule can only be used reliably (90 % success) to predict poor solubility; it cannot predict good solubility. The author has proposed a simple atomic model, which is empirical like the other two rules, but nevertheless has a clear physical basis and predicts the alloying behaviour of transition metals accurately in 98 % of cases. The model is very suitable for graphical presentation of the data and is therefore easy to use in practice."
Free web based applications include Entall [ 6 ] and Miedema Calculator. [ 7 ] The latter was reviewed and improved in 2016, with an extension of the method. [ 8 ] [ 9 ] The original Algol program [ 10 ] was ported to Fortran . [ 11 ]
Miedema's approach has been applied to the classification of miscible and immiscible systems of binary alloys. These are relevant in the design of multicomponent alloys. A comprehensive classification of alloying behavior for 813 binary alloy systems consisting of transition and lanthanide metals. [ 12 ] "Impressively, the classification by the miscibility map yields a robust validation on the capability of the well-known Miedema’s theory (95% agreement) and shows good agreement with the HTFP method (90% agreement)." [ 12 ] These 2017 results demonstrate that "a state-of-the art physics-guided data mining can provide an efficient pathway for knowledge discovery in the next generation of materials design". [ 12 ]
This Table, reports the three main Miedema parameters for the elements of the Periodic table for whom the model is applicable.
These are original parameters [ 13 ] which are after page 24 of the book after F.R. De Boer, R. Boom, W.C.M. Mattens, A.R. Miedema and A.K. Niessen Cohesion in Metals. Transition Metal Alloys (1988), [ 14 ]
The above list of parameters should be considered as a starting point, which could yield such data (results after Fortran program made available by Emre Sururi Tasci [ 11 ]
M AM5 AM3 AM2 AM MA2 MA3 MA5 AinM AM MinA
Sc -6 -9 -12 -17 -16 -13 -9 -39 -11 -53
Ti -10 -15 -20 -25 -22 -18 -12 -62 -17 -74
V -4 -7 -9 -11 -9 -7 -5 -28 -7 -29
Cr -1 -1 -2 -2 -2 -1 -1 -6 -1 -6
Mn 0 0 0 0 0 0 0 1 0 1
Fe 0 0 0 0 0 0 0 0 0 0
Co 0 -1 -1 -1 -1 -1 0 -2 -1 -2
Ni -1 -2 -2 -2 -2 -1 -1 -6 -2 -6
Y -1 -1 -1 -2 -2 -1 -1 -4 -1 -6
Zr -13 -20 -27 -37 -34 -28 -19 -85 -25 -118
Nb -9 -14 -18 -23 -21 -17 -11 -57 -16 -70
Mo -1 -2 -2 -3 -3 -2 -1 -7 -2 -9
Tc -2 -3 -4 -5 -4 -3 -2 -11 -3 -13
Ru -3 -4 -5 -7 -6 -5 -3 -17 -5 -20
Rh -3 -5 -6 -8 -7 -5 -4 -20 -5 -23
Pd -2 -4 -5 -6 -6 -4 -3 -16 -4 -19
La 2 3 4 6 7 6 4 14 5 25
Ce 1 2 3 4 4 3 2 8 3 14
Pr 0 1 1 1 1 1 1 2 1 4
Nd 0 1 1 1 1 1 1 2 1 4
Pm -1 -2 -2 -3 -3 -2 -2 -6 -2 -11
Sm -1 -1 -1 -2 -2 -1 -1 -4 -1 -6
EuII 14 22 29 42 44 38 26 91 30 160
EuIII 79 71 63 46 30 23 15 999 47 90
Gd -1 -1 -1 -2 -2 -1 -1 -4 -1 -6
Tb -1 -2 -3 -4 -4 -3 -2 -9 -3 -15
Dy -1 -2 -3 -4 -4 -3 -2 -9 -3 -15
Ho -1 -2 -2 -3 -3 -2 -2 -7 -2 -10
Er -2 -4 -5 -7 -7 -5 -4 -15 -5 -23
Tm -2 -4 -5 -7 -6 -5 -4 -15 -5 -23
YbII 12 18 25 35 36 29 20 77 25 124
YbIII 32 27 23 14 7 5 3 999 16 18
Lu -4 -6 -7 -10 -10 -8 -6 -23 -7 -35
Hf -11 -17 -23 -30 -28 -23 -16 -71 -21 -98
Ta -9 -13 -17 -22 -20 -16 -11 -54 -15 -67
W 0 0 0 0 0 0 0 0 0 0
Re 0 0 0 0 0 0 0 -1 0 -1
OS -2 -4 -5 -6 -5 -4 -3 -15 -4 -17
Ir -5 -8 -10 -13 -12 -9 -6 -32 -9 -38
Pt -7 -11 -15 -19 -17 -14 -9 -47 -13 -58
Th -5 -8 -11 -15 -15 -13 -9 -33 -11 -58
U -6 -9 -12 -16 -15 -12 -8 -38 -11 -53
Pu -4 -5 -7 -9 -8 -7 -5 -22 -6 -29
Cu 8 13 16 19 16 12 8 53 13 50
Ag 16 25 32 42 37 29 20 102 28 123
Au 5 7 9 12 11 9 6 28 8 37
H 46 26 13 4 2 2 1 999 27 34
Li 15 23 30 38 31 23 15 96 26 94
Na 31 47 63 89 86 68 46 195 62 276
K 35 53 70 106 121 106 73 221 81 432
Rb 35 53 70 106 127 116 82 221 83 476
cs 40 58 76 113 151 169 186 219 111 999
Be -8 -12 -15 -16 -12 -9 -6 -44 -9 -31
Mg 9 13 17 23 21 16 11 61 18 78
Ca 12 18 25 36 37 30 21 77 25 128
Sr 16 24 32 47 51 44 31 99 34 190
Ba 17 25 33 49 55 49 35 103 37 212
Zn -2 -3 -4 -5 -4 -3 -2 14 4 14
Cd 5 8 10 14 12 10 7 58 17 77
Hg 8 12 15 21 20 16 11 74 22 106
B -1 -16 -28 -38 -30 -23 -15 999 -11 -65
Al -13 -19 -25 -32 -28 -22 -15 -41 -11 -48
Ga -7 -10 -14 -18 -16 -13 -9 -6 -2 -8
In 5 7 9 13 12 10 7 63 19 95
Tl 10 16 21 30 29 24 17 99 31 160
C 38 12 -7 -20 -15 -11 -8 999 8 -28
Si 11 -1 -12 -26 -26 -21 -14 -67 -18 -75
Ge 12 6 0 -9 -11 -9 -6 -12 -3 -15
Sn -1 -1 -1 -2 -2 -2 -1 34 11 56
Pb 9 13 17 25 25 22 15 91 29 160
N 127 74 31 -17 -20 -15 -10 999 36 -43
P -17 -34 -50 -70 -63 -50 -34 999 -31 -156
As -15 -23 -30 -40 -38 -31 -21 -49 -14 -68
Sb -1 -2 -3 -4 -4 -4 -3 33 10 57
Bi 6 9 12 18 19 16 11 80 26 146
improved data may be found in more recent publications; [ 15 ] possibly, in the near future, improvement or insisight of these data could be provided by the extended Calphad databases open collections available at NIMS [ 16 ] For instance for Fe-X binary phase diagrams, a list of available databases is as presented in this link [1] and more specifically in this table: | https://en.wikipedia.org/wiki/Miedema's_model |
Migration , in ecology , is the large-scale movement of members of a species to a different environment . Migration is a natural behavior and component of the life cycle of many species of mobile organisms, not limited to animals, though animal migration is the best known type. Migration is often cyclical, frequently occurring on a seasonal basis, and in some cases on a daily basis . [ 1 ] Species migrate to take advantage of more favorable conditions with respect to food availability, safety from predation , mating opportunity, or other environmental factors. [ 2 ] [ 3 ]
Migration is most commonly seen in the form of animal migration, the physical movement by animals from one area to another. That includes bird , fish , and insect migration . However, plants can be said to migrate, as seed dispersal enables plants to grow in new areas, under environmental constraints such as temperature and rainfall, resulting in changes such as forest migration .
While members of some species learn a migratory route on their first journey with older members of their group, other species genetically pass on information regarding their migratory paths. [ 4 ] : 71–72 Despite many differences in organisms’ migratory cues and behaviors, “considerable similarities appear to exist in the cues involved in the different phases of migration.” [ 4 ] : 84 Migratory organisms use environmental cues like photoperiod and weather conditions as well as internal cues like hormone levels to determine when it is time to begin a migration. Migratory species use senses such as magnetoreception or olfaction to orient themselves or navigate their route, respectively. [ 4 ] : 69–70
The factors that determine migration methods are variable due to the inconsistency of major seasonal changes and events. When an organism migrates from one location to another, its energy use and rate of migration are directly related to each other and to the safety of the organism. If an ecological barrier presents itself along a migrant's route, the migrant can either choose to use its energy to cross the barrier directly or use it to move around the barrier. If an organism is migrating to a place where there is high competition for food or habitat, its rate of migration should be higher. This indirectly helps determine an organism's fitness by increasing the likelihood of its survival and reproductive success. [ 4 ] : 38–41
Animal migration is the relatively long-distance movement of individual animals , usually on a seasonal basis. It is the most common form of migration in ecology. [ 5 ] It is found in all major animal groups, including birds , [ 6 ] mammals , [ 7 ] fish , [ 8 ] [ 9 ] reptiles , [ 10 ] amphibians, insects , [ 11 ] and crustaceans . [ 12 ] [ 13 ] The cause of migration may be local climate, local availability of food, the season of the year or for mating. [ 5 ] To be counted as a true migration, and not just a local dispersal or irruption, the movement of the animals should be an annual or seasonal occurrence, or a major habitat change as part of their life. An annual event could include Northern Hemisphere birds migrating south for the winter, or wildebeest migrating annually for seasonal grazing. A major habitat change could include young Atlantic salmon or sea lamprey leaving the river of their birth when they have reached a few inches in size. [ 5 ] Some traditional forms of human migration fit this pattern. [ 14 ] [ 15 ] Migrations can be studied using traditional identification tags such as bird rings , or tracked directly with electronic tracking devices. [ 16 ] Before animal migration was understood, folklore explanations were formulated for the appearance and disappearance of some species, such as that barnacle geese grew from goose barnacles . [ 17 ]
Plants can be said to migrate, as seed dispersal enables plants to grow in new areas, under environmental constraints such as temperature and rainfall. When those constraints change, the border of a plant species's distribution may move, so the plant may be said to migrate, as for example in forest migration . [ 18 ]
A species migrating to a new community can affect the outcome of local competitive interactions. A species that migrates to a new community can cause a top-down effect within the community. If the migratory species is abundant in the new community, it can become a main prey for a resident predator, leaving other resident species as only an alternate prey. This new source of food (migrants) can increase the predatory species’ population size, impacting population sizes of its other prey when the migratory species return to their original location. [ 4 ] : 136 If a resident species experiences a scarcity of food due to seasonal variation, the species can decrease in population, creating an opportunity for a new species to migrate to that location as the decrease in the population of the resident species leaves an abundance of food. [ 4 ] : 135 Migratory species can also transport diseases long-distance from their original habitat. [ 4 ] : 137 | https://en.wikipedia.org/wiki/Migration_(ecology) |
Migratory aptitude is the relative ability of a migrating group to migrate in a rearrangement reaction . [ 1 ] Migratory aptitudes vary in different reactions, depending on multiple factors. [ 2 ]
In the Baeyer-Villiger reaction , the more substituted group, in general, migrates. [ 3 ] In the pinacol rearrangement , the order of migratory aptitude has not been determined unambiguously, [ 2 ] but some trends have been determined. For example, relative migratory aptitudes for alkyl substituents is Hydride >C(CH 3 ) 3 > C 2 H 5 > phenyl > CH 3 . [ 2 ] More bulky groups have more tendency to migrate.
This organic chemistry article is a stub . You can help Wikipedia by expanding it . | https://en.wikipedia.org/wiki/Migratory_aptitude |
In organometallic chemistry , a migratory insertion is a type of reaction wherein two ligands on a metal complex combine. It is a subset of reactions that very closely resembles the insertion reactions , and both are differentiated by the mechanism that leads to the resulting stereochemistry of the products. However, often the two are used interchangeably because the mechanism is sometimes unknown. Therefore, migratory insertion reactions or insertion reactions, for short, are defined not by the mechanism but by the overall regiochemistry wherein one chemical entity interposes itself into an existing bond of typically a second chemical entity e.g.: [ 1 ]
In the migratory insertion, a ligand that is viewed as an anion (X) ligand in and a ligand that is viewed as neutral couple, generating a new anionic ligand. The anion and neutral ligands that react are adjacent. If the precursor complex is coordinatively saturated , migratory insertion often result in a coordinatively unsaturated product. A new (neutral) ligand can then react with the metal leading to a further insertion. The process can occur many times on a single metal, as in olefin polymerization .
The anionic ligand can be: H − ( hydride ), R − (alkyl), acyl , Ar − ( aryl ), or OR − ( alkoxide ). The ability of these groups to migrate is called their migratory aptitude . The neutral ligand can be CO, alkene , alkyne , or in some cases, even carbene .
Diverse reactions apply to the migratory insertion. One mechanism involves the attack of the anionic ligand on the electrophilic part of the neutral ligand (the anionic ligand migrates to the neutral ligand). The other mechanism involves the neutral ligand that inserts itself between the metal and the anionic ligand.
The insertion of carbon monoxide into a metal-carbon bond to form an acyl group is the basis of carbonylation reactions, which provides many commercially useful products. Mechanistic. Studies reveal that the alkyl group migrates intramolecularly to an adjacent CO ligand. [ 2 ] [ 3 ]
Early studies were conducted on the conversion of CH 3 Mn(CO) 5 to give the acetyl derivative. [ 4 ] Using 13 CO, the products is cis [Mn(COCH 3 )( 13 CO)(CO) 4 ] (scheme 1).
CO insertion does not always involve migration. Treatment of CpFe(L)(CO)CH 3 with 13 CO yields a mix of both alkyl migration products and products formed by true insertion of bound carbonyls into the methyl group. Product distribution is influenced by the choice of solvent . [ 5 ]
Alkyl derivatives of square planar complexes undergo CO insertions particularly readily. Insertion reactions on square planar complexes are of particular interest because of their industrial applications. Since square planar complexes are often coordinatively unsaturated , they are susceptible to formation of 5-coordinate adducts, which undergo migratory insertion readily. [ 5 ] In most cases the in-plane migration pathway is preferred, but, unlike the nucleophilic pathway, is inhibited by an excess of CO. [ 6 ]
Decarbonylation of aldehydes , the reverse of CO insertion, is a well-recognized reaction:
The reaction is not widely practiced in part because the alkanes are less useful materials than are the aldehyde precursors. Furthermore, the reaction is not often conducted catalytically because the extruded CO can be slow to dissociate. [ 9 ] Extrusion of CO from an organic aldehyde is most famously demonstrated using Wilkinson's catalyst : [ 10 ]
Please see Tsuji-Wilkinson Decarbonylation Reaction for an example of this elementary organometallic step in synthesis
Many electrophilic oxides insert into metal carbon bonds that include sulfur dioxide , carbon dioxide , and nitric oxide. These reactions have limited or no practical significance, but are of historic interest. With transition metal alkyls, these oxides behave as electrophiles and insert into the bond between metals and their relatively nucleophilic alkyl ligands. As discussed in the article on Metal sulfur dioxide complexes , the insertion of SO 2 has been examined in particular detail. SO 2 inserts to give both O -sulphinates and S -sulphinates, depending on the metal centre. [ 11 ] With square planar alkyl complexes, a pre-equilibrium is assumed involving formation of an adduct. [ 12 ]
The insertion of alkenes into both metal-carbon is important. The insertion of ethylene and propylene into titanium alkyls is the cornerstone of Ziegler–Natta catalysis , the main source of polyethylene and polypropylene. The majority of this technology involves heterogeneous catalysts, but it is widely assumed that the principles and observations on homogeneous systems are applicable to the solid-state versions. Related technologies include the Shell Higher Olefin Process which produces detergent precursors.
Factors affecting the rate of olefin insertions include the formation of the cyclic, planar, four-center transition state involving incipient formation of a bond between the metal and an olefin carbon. From this transition state, it can be seen that a partial positive charge forms on the β-carbon with a partial negative charge formed on the carbon initially bonded to the metal. This polarization explains the subsequently observed formation of the bond between the negatively charged carbon/hydrogen and the positively charged β-carbon as well as the simultaneous formation of the metal-α-carbon bond. This transition state also highlights the two factors that most strongly contribute to the rate of olefin insertion reactions: (i) orbital overlap of the alkyl group initially attached to the metal and (ii) the strength of the metal-alkyl bond. With greater orbital overlap between the partially positive β-carbon and the partially negative hydrogen/alkyl group carbon, the formation of the new C-C bond is facilitated. With increasing strength of the metal-alkyl bond, the breaking of the bond between the metal and the hydrogen/alkyl carbon bond to form the two new bonds with the α-carbon and β-carbon (respectively) is slower, thus decreasing the rate of the insertion reaction. [ 13 ]
The insertion of alkenes into metal-hydrogen bonds is a key step in hydrogenation and hydroformylation reactions. The reaction involves the alkene and the hydride ligands combining within the coordination sphere of a catalyst. In hydrogenation, the resulting alkyl ligand combines with a second hydride to give the alkane. Analogous reactions apply to the hydrogenation of alkynes: an alkenyl ligand combines with a hydride to eliminate an alkene.
In terms of mechanism, the insertion of alkenes into M–H bond and into M–C bonds are described similarly. Both involve four-membered transition states that place the less substituted carbon on the metal.
The reverse of olefin insertion into a metal-hydrogen bond is β-hydride elimination . The Principle of Microscopic Reversibility requires that the mechanism of β-hydride elimination follow the same pathway as the insertion of alkenes into metal hydride bonds. The first requirement for β-hydride elimination is the presence of a hydrogen at a position that is β with respect to the metal. β-elimination requires a vacant coordination position on the metal that will accommodate the hydrogen that is abstracted. [ 14 ]
Two widely employed applications of migratory insertion of carbonyl groups are hydroformylation and the production of acetic acid by carbonylation of methanol . The former converts alkenes, hydrogen, and carbon monoxide into aldehydes. The production of acetic acid by carbonylation proceeds via two similar industrial processes. More traditional is the Monsanto acetic acid process , which relies on a rhodium-iodine catalyst to transform methanol into acetic acid. This process has been superseded by the Cativa process which uses a related iridium catalyst, [Ir(CO) 2 I 2 ] − ( 1 ). [ 15 ] [ 16 ] By 2002, worldwide annual production of acetic acid stood at 6 million tons, of which approximately 60% is produced by the Cativa process. [ 15 ]
The Cativa process catalytic cycle , shown above, includes both insertion and de-insertion steps. The oxidative addition reaction of methyl iodide with ( 1 ) involves the formal insertion of the iridium(I) centre into the carbon-iodine bond, whilst step ( 3 ) to ( 4 ) is an example of migratory insertion of carbon monoxide into the iridium-carbon bond. The active catalyst species is regenerated by the reductive elimination of acetyl iodide from ( 4 ), a de-insertion reaction. [ 15 ]
Industrial applications of alkene insertions include metal-catalyzed routes to polyethylene and polypropylene. Typically these conversions are catalyzed heterogeneously by titanium trichloride which are activated by aluminium alkyls. This technology is known as Ziegler–Natta catalysts . [ 17 ] In these reactions, ethylene coordinates to titanium metal followed by its insertion. These steps can be repeated multiple times, potentially leading to high molecular weight polymers. | https://en.wikipedia.org/wiki/Migratory_insertion |
Miguel A. García-Garibay is a professor of chemistry and biochemistry and the dean of physical sciences at University of California, Los Angeles (UCLA). [ 1 ] [ 2 ] His research focuses on solid state organic chemistry , photochemistry and spectroscopy , artificial molecular machines , and mesoscale phenomena . [ 3 ] [ 4 ]
García-Garibay received his B.S. from the University of Michoacán , Mexico, in 1982. After completing a combined degree in Chemistry, Biology, and Pharmacy, García-Garibay went on to get a PhD degree in Chemistry at the University of British Columbia, where he joined the group of John Scheffer . After that, he joined the group of Nicholas Turro as a postdoctoral fellow at Columbia University . [ 5 ]
García-Garibay received an Arthur C. Cope Scholar Award in 2015. | https://en.wikipedia.org/wiki/Miguel_García-Garibay |
Miguel A. Modestino is a Venezuelan-born chemical engineer and co-founder of Sunthetics along with Myriam Sbeiti and Daniela Blanco . Sunthetics uses artificial intelligence to optimize chemical reactions by inducing electrical pulses, from renewable energy, into the reaction instead of just heating them. Modestino is a part of the Joint Center for Artificial Photosynthesis , which is a group focused on reducing the need for fossil fuel by developing solar fuels as a direct alternative. [ 1 ] Modestino also formed a group called the Modestino Group, which specialize in developing state of the art electrochemical devices to optimize and tackle the issues revolving renewable energy at New York University (NYU), where he is the Donald F. Othmer Associate Professor of Chemical Engineering and the Director of Sustainable Engineering Initiative. [ 2 ]
Miguel Modestino earned his bachelor's degree in chemical engineering in 2007 and his M.S. in chemical engineering in 2008 from Massachusetts Institute of Technology (MIT), and a PH.D. in chemical engineering from University of California, Berkeley in 2013. [ 2 ] [ 3 ]
During his time at MIT, Modestino was a research assistant from October 2003 to June 2007 under the supervision of Paula Hammond , and worked on film assembly which used a layer-by-layer method for biomedical purposes, while he was working towards his B.S. in chemical engineering. He remained at MIT to complete his M.S. in chemical engineering while simultaneously being a Teaching Assistant for Chemical Engineering Projects Lab from February 2008 to May 2008. In between his M.S. and starting his Ph.D., Modestino was an intern at Novartis and BP in 2008 under David H. Koch School of Chemical Engineering Practice. [ 4 ] After he obtained a Ph.D., Modestino did his postdoctoral research at École Polytechnique Fédérale de Lausanne (EPFL) from 2013 to 2016. [ 2 ] [ 3 ]
Modestino is currently the Donald F. Othmer Associate Professor of Chemical Engineering and the Director of Sustainable Engineering Initiative at NYU . At NYU, Modestino carries out his research into renewable energy and production of eco-friendly electrochemical devices. [ 2 ]
Modestino co-founded Sunthetics, along with NYU graduates Myriam Sbeiti and Daniela Blanco . [ 5 ]
Sunthetics is a startup company whose goal is to reduce to reliance on fossil fuels for heating chemical reactions and instead using electrical pulses to supply energy for various chemical reactions to occur. Initially the idea was coined by Blanco as part of her PhD thesis at NYU. The goal was to apply this to nylon, however due to the lack of support from nylon manufacturing companies the idea pivoted to Artificial Intelligence to drive chemical reactions through renewable energy. This led to machine learning optimizing this technology to be applied across several industries. [ 6 ]
The Modestino Group focuses on the development of electrochemical devices, which are devices used in energy conversion technologies and chemical processes. Through these devices the group can address a wide range of issues such as carbon dioxide reduction, improving grip flexibility characterizing multiphase flow in reactors and developing sustainable clothing. [ 7 ] The group has expertise in manufacturing, developing, processing and characterizing composite materials which they use to refine electrochemical reactors in industrial applications. [ 8 ] The group has a number of projects under their hood such as solar textiles, materials for electrochemical catalyst layers, advanced electrolysis devices, and multiphase-flow micro-electrochemical reactors. The group consists of Modestino as the leader and head of team, and several Ph.D. students, M.S. students, B.S. students and Alumni. [ 9 ]
While at Berkeley, Modestino participated in a project that harnessed solar energy to convert carbon-dioxide from the air into fuel similar to that of plants this process is call solar fuels as part of his Ph.D. program. At Berkeley, he joined a group called Joint Center for Artificial Photosynthesis (JCAP). [ 3 ] JCAP's goal is to research and develop these solar fuels so that it can be used and applied in many facets of the world while also being cost efficient enough to actually challenge or be the better alternative to fossil fuels. [ 1 ]
In 2015, Modestino won the award for Energy and Environmental Science Reader's Choice Lectureship Award, for his publication of Design and cost considerations for practical solar-hydrogen generators , which was among the most downloaded and read articles of 2014. [ 10 ]
In 2017, Modestino won the Global Change Award with Daniela Blanco and Myriam Sbeiti for their work on Sunthetics. [ 2 ]
In 2017, Modestino won the MIT Technology Review Innovators Under 35 Award in the region Latin America, for his work in developing and optimizing the chemical industry to become safer for the environment. [ 3 ]
In 2018, Modestino was awarded $110,000 in the Doctoral New Investigator Award by the American Chemical Society Petroleum Research Fund, to commemorate his work with Ionic Liquid-Polymer Gel Electrolytes for Electrochemical Olefin Separations. [ 11 ]
In 2019, Modestino was awarded National Science Foundation Career Award . [ 2 ]
In 2020, Modestino was included in MIT Technology Review magazine's "Innovators Under 35" list, for his team's innovation of using artificial intelligence to make chemical reactions more efficient using electrical pulses instead of heating while simultaneously having it adapt to different chemicals. [ 12 ]
In 2020, Modestino was awarded the Goddard Junior Faculty Fellowship Award in New York University. Modestino earned the reward as a tenure-tract faculty member who has successfully pass their three-year review, the reward is either one course deduction to focus on research or scholarships or $5,000 towards their scholarship. [ 2 ]
In 2021, Modestino was awarded the TED Idea Search Latin America. [ 2 ] | https://en.wikipedia.org/wiki/Miguel_Modestino |
Mihi itch or Mihisucht is the ambition to describe new species (or other taxa : subspecies , hybrids , genera , etc.) as a means to immortalize one's name. Mihi is the dative form of the Latin word ego , thus "mihi itch" means to satisfy one's egotistical impulses. [ 1 ] The expression appeared in print as early as 1884. [ 2 ]
A consequence of the Mihi itch may be the unwarranted description of new taxa, differing only slightly from already established taxa, leading to taxonomic inflation . A more extreme case may be termed taxonomic vandalism when a large number of species are described with limited scientific evidence.
This biology article is a stub . You can help Wikipedia by expanding it . | https://en.wikipedia.org/wiki/Mihi_itch |
Mihrab ( Arabic : محراب , miḥrāb , pl. محاريب maḥārīb ) is a niche in the wall of a mosque that indicates the qibla , the direction of the Kaaba in Mecca towards which Muslims should face when praying. The wall in which a mihrab appears is thus the " qibla wall".
The minbar , which is the raised platform from which an imam (leader of prayer) addresses the congregation, is located to the right of the mihrab .
The origin of the word miḥrāb is complicated, and multiple explanations have been proposed by different sources and scholars. [ 1 ] [ 2 ] It may come from Old South Arabian (possibly Sabaic ) 𐩣𐩢𐩧𐩨 mḥrb meaning a certain part of a palace , [ 3 ] as well as "part of a temple where 𐩩𐩢𐩧𐩨 tḥrb (a certain type of visions) is obtained," [ 4 ] [ 5 ] from the root word 𐩢𐩧𐩨 ḥrb "to perform a certain religious ritual (which is compared to combat or fighting and described as an overnight retreat) in the 𐩣𐩢𐩧𐩨 mḥrb of the temple." [ 4 ] [ 5 ] It may also possibly be related to Ethiopic ምኵራብ məkʷrab "temple, sanctuary," [ 6 ] [ 7 ] whose equivalent in Sabaic is 𐩣𐩫𐩧𐩨 mkrb of the same meaning, [ 4 ] from the root word 𐩫𐩧𐩨 krb "to dedicate" (cognate with Akkadian 𒅗𒊒𒁍 karābu "to bless" and related to Hebrew כְּרוּב kerūḇ " cherub (either of the heavenly creatures that bound the Ark in the inner sanctuary )").
Arab lexicographers traditionally derive the word from the Arabic root ح ر ب (Ḥ-R-B) relating to "war, fighting or anger," (which, though cognate with the South Arabian root, [ 8 ] does not however carry any relation to religious rituals) thus leading some to interpret it to mean a "fortress", or "place of battle (with Satan )," [ 9 ] the latter due to mihrabs being private prayer chambers. The latter interpretation though bears similarity to the nature of the 𐩢𐩧𐩨 ḥrb ritual.
The word mihrab originally had a non-religious meaning and simply denoted a special room in a house; a throne room in a palace, for example. The Fath al-Bari (p. 458), on the authority of others, suggests the mihrab is "the most honorable location of kings" and "the master of locations, the front and the most honorable." [ full citation needed ] The Mosques in Islam (p. 13), [ full citation needed ] in addition to Arabic sources, cites Theodor Nöldeke and others as having considered a mihrab to have originally signified a throne room.
The term was subsequently used by the Islamic prophet Muhammad to denote his own private prayer room. [ citation needed ] The room additionally provided access to the adjacent mosque, and Muhammad entered the mosque through this room. This original meaning of mihrab – i.e. as a special room in the house – continues to be preserved in some forms of Judaism where mihrabs are rooms used for private worship. [ citation needed ] In the Qur'an , the word (when in conjunction with the definite article) is mostly used to indicate the Holy of Holies . The term is used, for example, in the verse "then he [i.e. Zechariah ] came forth to his people from the mihrab " [ 19:11 ] . [ 10 ] : 4
The earliest mihrabs generally consisted of a simple stripe of paint or a flat stone panel in the qibla wall. [ a ] They may have originally had functions similar to a maqsura , denoting not only the place where the imam led prayers but also where some official functions, such as the dispensation of justice, were carried out. [ 2 ] In the Mosque of the Prophet ( Al-Masjid al-Nabawi ) in Medina , a large block of stone initially marked the north wall which was oriented towards Jerusalem (the first qibla), but this was moved to the south wall in the second year of the hijra period (2 AH or 624 CE ), when the orientation of the qibla was changed towards Mecca. [ 11 ] This mihrab also marked the spot where Muhammad would plant his lance ( 'anaza or ḥarba ) prior to leading prayers. [ 2 ]
During the reign of the Umayyad caliph Al-Walid ibn Abd al-Malik (Al-Walid I, r. 705–715), the Mosque of the Prophet was renovated and the governor ( wāli ) of Medina, Umar ibn Abd al-Aziz , ordered that a niche be made to designate the qibla wall (which identifies the direction of Mecca), which became the first concave mihrab niche. [ 12 ] : 24 [ 11 ] This type of mihrab was called miḥrāb mujawwaf in historical Arabic texts . [ 2 ] [ 1 ] The origin of this architectural feature has been debated by scholars. [ 2 ] Some trace it to the apse of Christian churches , others to the alcove shrines or niches of Buddhist architecture . [ 11 ] [ 2 ] Niches were already a common feature of Late Antique architecture prior to the rise of Islam, either as hollow spaces or to house statues . The mihrab niche could have also been related to the recessed area or alcove that sheltered the throne in some royal audience halls. [ 2 ]
The next earliest concave mihrab to be documented is the one that was added to the Umayyad Mosque of Damascus when it was built by Al-Walid between 706 and 715. [ 12 ] : 24 This was then followed by a mihrab added to the Mosque of 'Amr ibn al-'As in Fustat in 710–711. [ 11 ] Subsequently, concave mihrabs became widespread across the Muslim world and were adopted as a standard feature of mosques. [ 11 ] [ 12 ] : 24 The oldest surviving concave mihrab today is a marble mihrab housed at the Iraq Museum . It is believed to date from the 8th century, possibly made in northern Syria before being moved by the Abbasids to the Great Mosque of al-Mansur in Baghdad. It was then moved again to the al-Khassaki Mosque built in the 17th century, where it was later found and transferred to the museum. [ 11 ] [ 2 ] [ 13 ] : 29 This mihrab features a combination of Classical or Late Antique motifs, with the niche flanked by two spiral columns and crowned by a scalloped shell-like hood. [ 11 ] [ 13 ] : 29 [ 10 ] : 5
Eventually, the niche came to be universally understood to identify the qibla wall, and so came to be adopted as a feature in other mosques. A sign was no longer necessary. Today, mihrabs vary in size, but are usually ornately decorated. [ citation needed ] It was common for mihrabs to be flanked with pairs of candlesticks, though they would not have lit candles. [ 14 ] In Ottoman mosques, these were made of brass, bronze or beaten copper and their bases had a distinctive bell shape. [ 15 ]
In exceptional cases, the mihrab does not follow the qibla direction, such as is the Masjid al-Qiblatayn , or the Mosque of the Two Qiblas, where Muhammad received the command to change the direction of prayer from Jerusalem to Mecca, so it had two prayer niches. When the mosque was renovated in 1987, the old prayer niche facing Jerusalem was removed, and the one facing Mecca was kept. [ 16 ]
Mihrabs are a relevant part of Islamic culture and mosques. Since they are used to indicate the direction for prayer, they serve as an important focal point in the mosque. They are usually decorated with ornamental detail that can be geometric designs, linear patterns, or calligraphy. This ornamentation also serves a religious purpose. The calligraphy decoration on the mihrabs are usually from the Qur'an and are devotions to God so that God's word reaches the people. [ 17 ] Common designs amongst mihrabs are geometric foliage that are close together so that there is no empty space in-between the art. [ 17 ]
The mihrab in the Great Mosque of Cordoba is a highly decorated piece of art that draws one's attention. It is a contribution made by Al-Hakam II that is not just used for prayer. [ 18 ] It is used as a place of convergence in the mosque, where visitors could be amazed by its beauty and gilded designs. The entrance is covered in mosaics "which links to the Byzantium tradition, produced by the craftsmen sent by Emperor Nicephorus II. These mosaics extend along the voussoirs with a geometric and plant-based design, but also in the inscriptions which record verses from the Koran". [ 18 ] This mihrab is also a bit different from a normal mihrab due to its scale. It takes up a whole room instead of just a niche. [ 19 ] This style of mihrab set a standard for other mihrab construction in the region. [ 20 ] The use of the horseshoe arch, carved stucco , and glass mosaics made an impression for the aesthetic of mihrabs , "although no other extant mihrab in Spain or western North Africa is as elaborate." [ 20 ]
The Great Mosque of Damascus was started by al-Walid in 706. [ 21 ] It was built as a hypostyle mosque, built with a prayer hall leading to the mihrab, "on the back wall of the sanctuary are four mihrabs , two of which are the mihrab of the Companions of the Prophet in the eastern half and the great mihrab at the end of the transept". [ 21 ] The mihrab is decorated similarly to the rest of the mosque in golden vines and vegetal imagery. The lamp that once hung in the mihrab has been theorized as the motif of a pearl, due to the indications that dome of the mihrab has scalloped edges. [ 22 ] There have been other mosques that have mihrabs similar to this that follow the same theme, with scalloped domes that are "concave like a conch or mother of pearl shell. [ 22 ] The original main mihrab of the mosque has not been preserved, having been renovated many times, and the current one is a replacement dating from renovations after a destructive 1893 fire. [ 22 ] [ 23 ] [ 11 ] | https://en.wikipedia.org/wiki/Mihrab |
Catalan's conjecture (or Mihăilescu's theorem ) is a theorem in number theory that was conjectured by the mathematician Eugène Charles Catalan in 1844 and proven in 2002 by Preda Mihăilescu at Paderborn University . [ 1 ] [ 2 ] The integers 2 3 and 3 2 are two perfect powers (that is, powers of exponent higher than one) of natural numbers whose values (8 and 9, respectively) are consecutive. The theorem states that this is the only case of two consecutive perfect powers. That is to say, that
Catalan's conjecture — the only solution in the natural numbers of
for a , b > 1 , x , y > 0 is x = 3 , a = 2 , y = 2 , b = 3 .
The history of the problem dates back at least to Gersonides , who proved a special case of the conjecture in 1343 where ( x , y ) was restricted to be (2, 3) or (3, 2). The first significant progress after Catalan made his conjecture came in 1850 when Victor-Amédée Lebesgue dealt with the case b = 2. [ 3 ]
In 1976, Robert Tijdeman applied Baker's method in transcendence theory to establish a bound on a , b and used existing results bounding x , y in terms of a , b to give an effective upper bound for x , y , a , b . Michel Langevin computed a value of exp exp exp exp 730 ≈ 10 10 10 10 317 {\displaystyle \exp \exp \exp \exp 730\approx 10^{10^{10^{10^{317}}}}} for the bound, [ 4 ] resolving Catalan's conjecture for all but a finite number of cases.
Catalan's conjecture was proven by Preda Mihăilescu in April 2002. The proof was published in the Journal für die reine und angewandte Mathematik , 2004. It makes extensive use of the theory of cyclotomic fields and Galois modules . An exposition of the proof was given by Yuri Bilu in the Séminaire Bourbaki . [ 5 ] In 2005, Mihăilescu published a simplified proof. [ 6 ]
Pillai's conjecture concerns a general difference of perfect powers (sequence A001597 in the OEIS ): it is an open problem initially proposed by S. S. Pillai , who conjectured that the gaps in the sequence of perfect powers tend to infinity. This is equivalent to saying that each positive integer occurs only finitely many times as a difference of perfect powers: more generally, in 1931 Pillai conjectured that for fixed positive integers A , B , C the equation A x n − B y m = C {\displaystyle Ax^{n}-By^{m}=C} has only finitely many solutions ( x , y , m , n ) with ( m , n ) ≠ (2, 2). Pillai proved that for fixed A , B , x , y , and for any λ less than 1, we have | A x n − B y m | ≫ x λ n {\displaystyle |Ax^{n}-By^{m}|\gg x^{\lambda n}} uniformly in m and n . [ 7 ]
The general conjecture would follow from the ABC conjecture . [ 7 ] [ 8 ]
Pillai's conjecture means that for every natural number n , there are only finitely many pairs of perfect powers with difference n . The list below shows, for n ≤ 64, all solutions for perfect powers less than 10 18 , such that the exponent of both powers is greater than 1. The number of such solutions for each n is listed at OEIS : A076427 . See also OEIS : A103953 for the smallest solution (> 0). | https://en.wikipedia.org/wiki/Mihăilescu's_theorem |
Mikael Bols (born July 28, 1961) is a synthetic organic chemist who is mainly known for his work on carbohydrates and artificial enzymes .
Mikael Bols was born and grew up in Copenhagen, Denmark. He attended high school (Gentofte Statskole) from 1977 to 1980, and took a degree as chemical engineer at the Technical University of Denmark from 1980 to 1985.
From 1985 to 1988, Bols did PhD with Professor Inge Lundt at the Technical University of Denmark . From 1988 to 1989, he did a post doc with professor Walter Szarek at Queen's University before joining Leo Pharmaceuticals in 1989. From 1991 to 1995, he was Ass. Prof. at DTU only interrupted by a visit in the last 6 month of 1994 Gilbert Stork 's group at Columbia University . From 1995 to 2000, he was Assoc. Prof. (Lektor) at University of Aarhus during which period he became Dr. Scient. (1997). From 1998 to 2000 and from 2004 to 2006, he was Head of the chemistry department at university of Aarhus. From 2000 to 2005, he became Lundbeckfondsprofessor and subsequently (2005-2007) ordinary professor. In 2007, he became professor and Head of department of the Department of Chemistry at University of Copenhagen . [ 1 ]
The discovery of isofagomine and related glycosidase inhibitors, [ 2 ] the discovery of stereoelectronic substituent effects [ 3 ] and superarmed glycosyl donors , the creation of artificial enzymes that cause large rate increases., [ 4 ] and writing the book "Carbohydrate Building Blocks" about using carbohydrates as a chirality source in synthesis. [ 5 ] | https://en.wikipedia.org/wiki/Mikael_Bols |
Mikael Kubista (born 13 August 1961) is a Czech -born Swedish chemist and entrepreneur who works in the field of molecular diagnostics . Since 2007, he is serving as a Professor of Chemistry and Head of the Department of Gene Expression Profiling at the Biotechnology Institute, Czech Academy of Sciences in the Czech Republic.
Kubista has contributed to the field of quantitative real-time PCR (qPCR), with his work recognized as part of the early research in this area. [ 1 ] [ 2 ] [ 3 ] [ dubious – discuss ]
Kubista was a member of the research team at Astra Hässle , where they focused on investigating Omeprazole, an inhibitor of K+/H+-ATPase. The drug is now marketed under the trade names Losec and Nexium, widely prescribed medications for the treatment of gastric ulcer . [ 4 ] [ dubious – discuss ] Additionally, Kubista is the Chairman of the Board of MultiD Analyses AB and the founder of TATAA Biocenter. [ 5 ] [ 6 ] [ 7 ] [ 8 ]
Kubista was born to his medical doctor father in the former Czechoslovakia in 1961. His father received a scholarship and relocated to Sweden . At the age of 7 in 1968, Kubista went to Sweden to visit his father. However, on that very day, Russia invaded Czechoslovakia in the so called Warsaw Pact invasion of Czechoslovakia , and as a result, the family decided to stay making Sweden their new home. [ 9 ]
He completed his undergraduate studies at University of Gothenburg , earning a B.Sc. degree in chemistry in 1984. [ 10 ] He then pursued a Licentiate in Physical Chemistry at the Institute of Chemistry and Chemical Engineering, Chalmers University of Technology in Göteborg, which he completed in 1986. [ 11 ] Kubista obtained his Ph.D. in chemistry from Chalmers University of Technology. [ 12 ] Following his doctoral studies, he conducted postdoctoral research at institutions such as La Trobe University in Melbourne, Australia, and Yale University in New Haven, US. [ 8 ] [ 4 ] [ dubious – discuss ] Additionally, he has held visiting professor positions at various universities, including the University of Maryland in College Park , US, in June 2000, and the University of A Coruña in Spain, during September–November 2003 and July 2006 to June 2007. [ citation needed ] Since 2007, Kubista is serving as an adjunct professor at the Institute of Biotechnology, Czech Academy of Sciences. [ 13 ] [ 14 ] [ dubious – discuss ] [ 9 ]
Kubista began his academic career in 1991 as an Assistant Professor in the Department of Physical Chemistry at Chalmers University of Technology. [ citation needed ] From 1993 to 1997, he served as an Associate Professor in the Department of Biochemistry at the same institution. Following this, he held the position of Professor in the Department of Biochemistry at Chalmers University of Technology from 1997 to 2006. [ citation needed ] Since 2007, he is the Head of the Department of Gene Expression at the Institute of Biotechnology, BIOCEV, Czech Academy of Sciences. [ 15 ]
In 1998 Kubista founded LightUp Technologies AB after his research finding of lightUp probes, [ 2 ] a company that specializes in the development of real-time PCR tests for human infectious diseases. [ 16 ] [ 5 ] Three years later In 2001, Kubista's research led to the establishments of MultiD Analyses AB, which develops GenEx software for gene expression data analysis and TATAA Biocenter for qPCR and gene expression analysis. [ 16 ] [ 5 ] The company became known for its qPCR training services globally and its provision of qPCR services, particularly in Europe. TATAA Biocenter was the first laboratory in Europe to obtain flexible ISO 17025 accreditation and also was the first to provide COVID tests at the onset of the pandemic. [ 17 ] In 2021 TATAA Biocenter accepted financing from Care Equity,controlled by General Partner Peter Batesko. [ 18 ] [ 19 ] In 2023 Peter Batesko refused to register Kubista and his co-founders as shareholders forfeiting their ownership, claiming his right to do so because of a mistake made by lawfirms Glimstedt and Norma. [ 20 ] [ 21 ] In 2014 Kubista implemented non-invasive prenatal testing (NIPT) in Sweden and subsequently founded Life Genomics AB. [ 5 ] In 2020, Kubista co-founded SimSen Diagnostics, a company focused on developing technology for liquid biopsy analyses. [ 8 ] [ 4 ] [ 22 ] [ 6 ] In 2024 Kubista co-founded HotSpot Diagnostics with professors Erik Lekholm and Anders Ståhlberg around a new cancer biomarker and the Uniprobe.
In 2021 Kubista and his co-founders of TATAA Biocenter, sought external investment to expand the company's capabilities. This led to a partnership with the American investment firm Care Equity, aiming to position TATAA as a leading provider of GLP/GCP-regulated molecular services for the pharmaceutical industry, particularly in cell and gene therapies. [ 23 ]
To facilitate this investment, a new holding company, Bioholdings LP, was established by Care Equity to acquire TATAA. Kubista and other original shareholders received shares in Bioholdings LP through their holding company. However, due to complexities in restructuring TATAA's COVID-19 testing business, Kubista and his partners, following legal advice, executed an upstream merger between their holding company and a newly formed entity. This merger inadvertently violated a clause in the agreement with Care Equity that prohibited share transfers without written consent. Unaware of this restriction, Kubista proceeded with the merger, leading Care Equity to dismiss him as CEO of TATAA in June 2023. [ 24 ]
Subsequently, Kubista and his co-founders lost their ownership stakes in TATAA, prompting them to sue their legal advisors for negligent counsel in the Gothenburg District Court. [ 25 ]
After Care Equity forfeited the founders’ shares, General Partner Peter Batesko himself and through companies he controls, sued Kubista, the founders’ holding company and their lawyer, in several jurisdictions and threatened their coworkers and advisors. The founders’ lawyer Per Karlsson claims this is SLAPP to hinder the founders from claiming back TATAA. The case has been appealed to the Supreme Court in Sweden. [ 26 ]
Kubista holds several positions and advisory roles within the scientific and biotechnology communities including: Roche, ThermoFisher, Qiagen, Bio-Rad, and RealSeq Biosciences. He is also a member of the Scientific Advisory Council of Genetic Engineering News. [ 27 ] [ 1 ]
Kubista has also been involved in the establishment of modern molecular diagnostics in developing countries. Since 1999, he has served as an advisor to UNESCO , providing guidance and assistance to countries such as: Libya , Egypt , Iran , Grenada , and Ghana . [ 4 ] [ 9 ]
Kubista is an expert advisor for the European Commission Research Directorate General. Kubista advises the United Nations Educational Scientific and Cultural Organization (UNESCO) and is part of the scientific advisory board for the International Biotechnology Research in Tripoli, Libya, under UNESCO. [ 9 ] [ 28 ] [ 29 ] | https://en.wikipedia.org/wiki/Mikael_Kubista |
Mikhael Leonidovich Gromov (also Mikhail Gromov , Michael Gromov or Misha Gromov ; Russian: Михаи́л Леони́дович Гро́мов ; born 23 December 1943) is a Russian-French mathematician known for his work in geometry , analysis and group theory . He is a permanent member of Institut des Hautes Études Scientifiques in France and a professor of mathematics at New York University .
Gromov has won several prizes, including the Abel Prize in 2009 "for his revolutionary contributions to geometry".
Mikhail Gromov was born on 23 December 1943 in Boksitogorsk , Soviet Union . His father Leonid Gromov was Russian-Slavic and his mother Lea was of Jewish heritage. Both were pathologists . [ 1 ] His mother was the cousin of World Chess Champion Mikhail Botvinnik , as well as of the mathematician Isaak Moiseevich Rabinovich. [ 2 ] Gromov was born during World War II , and his mother, who worked as a medical doctor in the Soviet Army, had to leave the front line in order to give birth to him. [ 3 ] When Gromov was nine years old, [ 4 ] his mother gave him the book The Enjoyment of Mathematics by Hans Rademacher and Otto Toeplitz , a book that piqued his curiosity and had a great influence on him. [ 3 ]
Gromov studied mathematics at Leningrad State University where he obtained a master's degree in 1965, a doctorate in 1969 and defended his postdoctoral thesis in 1973. His thesis advisor was Vladimir Rokhlin . [ 5 ]
Gromov married in 1967. In 1970, he was invited to give a presentation at the International Congress of Mathematicians in Nice , France. However, he was not allowed to leave the USSR. Still, his lecture was published in the conference proceedings. [ 6 ]
Disagreeing with the Soviet system, he had been thinking of emigrating since the age of 14. In the early 1970s he ceased publication, hoping that this would help his application to move to Israel . [ 4 ] [ 7 ] He changed his last name to that of his mother. [ 4 ] He received a coded letter saying that, if he could get out of the Soviet Union, he could go to Stony Brook , where a position had been arranged for him. When the request was granted in 1974, he moved directly to New York and worked at Stony Brook. [ 6 ]
In 1981 he left Stony Brook University to join the faculty of University of Paris VI and in 1982 he became a permanent professor at the Institut des Hautes Études Scientifiques where he remains today. At the same time, he has held professorships at the University of Maryland, College Park from 1991 to 1996, and at the Courant Institute of Mathematical Sciences in New York since 1996. [ 8 ] He adopted French citizenship in 1992. [ 9 ]
Gromov's style of geometry often features a "coarse" or "soft" viewpoint, analyzing asymptotic or large-scale properties. [G00] He is also interested in mathematical biology , [ 10 ] the structure of the brain and the thinking process, and the way scientific ideas evolve. [ 6 ]
Motivated by Nash and Kuiper's isometric embedding theorems and the results on immersions by Morris Hirsch and Stephen Smale , [ 10 ] Gromov introduced the h-principle in various formulations. Modeled upon the special case of the Hirsch–Smale theory, he introduced and developed the general theory of microflexible sheaves , proving that they satisfy an h-principle on open manifolds . [G69] As a consequence (among other results) he was able to establish the existence of positively curved and negatively curved Riemannian metrics on any open manifold whatsoever. His result is in counterpoint to the well-known topological restrictions (such as the Cheeger–Gromoll soul theorem or Cartan–Hadamard theorem ) on geodesically complete Riemannian manifolds of positive or negative curvature. After this initial work, he developed further h-principles partly in collaboration with Yakov Eliashberg , including work building upon Nash and Kuiper's theorem and the Nash–Moser implicit function theorem . There are many applications of his results, including topological conditions for the existence of exact Lagrangian immersions and similar objects in symplectic and contact geometry . [ 11 ] [ 12 ] His well-known book Partial Differential Relations collects most of his work on these problems. [G86] Later, he applied his methods to complex geometry , proving certain instances of the Oka principle on deformation of continuous maps to holomorphic maps . [G89] His work initiated a renewed study of the Oka–Grauert theory, which had been introduced in the 1950s. [ 13 ] [ 14 ]
Gromov and Vitali Milman gave a formulation of the concentration of measure phenomena. [GM83] They defined a "Lévy family" as a sequence of normalized metric measure spaces in which any asymptotically nonvanishing sequence of sets can be metrically thickened to include almost every point. This closely mimics the phenomena of the law of large numbers , and in fact the law of large numbers can be put into the framework of Lévy families. Gromov and Milman developed the basic theory of Lévy families and identified a number of examples, most importantly coming from sequences of Riemannian manifolds in which the lower bound of the Ricci curvature or the first eigenvalue of the Laplace–Beltrami operator diverge to infinity. They also highlighted a feature of Lévy families in which any sequence of continuous functions must be asymptotically almost constant. These considerations have been taken further by other authors, such as Michel Talagrand . [ 15 ]
Since the seminal 1964 publication of James Eells and Joseph Sampson on harmonic maps , various rigidity phenomena had been deduced from the combination of an existence theorem for harmonic mappings together with a vanishing theorem asserting that (certain) harmonic mappings must be totally geodesic or holomorphic. [ 16 ] [ 17 ] [ 18 ] Gromov had the insight that the extension of this program to the setting of mappings into metric spaces would imply new results on discrete groups , following Margulis superrigidity . Richard Schoen carried out the analytical work to extend the harmonic map theory to the metric space setting; this was subsequently done more systematically by Nicholas Korevaar and Schoen, establishing extensions of most of the standard Sobolev space theory. [ 19 ] A sample application of Gromov and Schoen's methods is the fact that lattices in the isometry group of the quaternionic hyperbolic space are arithmetic . [GS92]
In 1978, Gromov introduced the notion of almost flat manifolds . [G78] The famous quarter-pinched sphere theorem in Riemannian geometry says that if a complete Riemannian manifold has sectional curvatures which are all sufficiently close to a given positive constant, then M must be finitely covered by a sphere. In contrast, it can be seen by scaling that every closed Riemannian manifold has Riemannian metrics whose sectional curvatures are arbitrarily close to zero. Gromov showed that if the scaling possibility is broken by only considering Riemannian manifolds of a fixed diameter, then a closed manifold admitting such a Riemannian metric, with sectional curvatures sufficiently close to zero, must be finitely covered by a nilmanifold . The proof works by replaying the proofs of the Bieberbach theorem and Margulis lemma . Gromov's proof was given a careful exposition by Peter Buser and Hermann Karcher. [ 20 ] [ 21 ] [ 22 ]
In 1979, Richard Schoen and Shing-Tung Yau showed that the class of smooth manifolds which admit Riemannian metrics of positive scalar curvature is topologically rich. In particular, they showed that this class is closed under the operation of connected sum and of surgery in codimension at least three. [ 23 ] Their proof used elementary methods of partial differential equations , in particular to do with the Green's function . Gromov and Blaine Lawson gave another proof of Schoen and Yau's results, making use of elementary geometric constructions. [GL80b] They also showed how purely topological results such as Stephen Smale 's h-cobordism theorem could then be applied to draw conclusions such as the fact that every closed and simply-connected smooth manifold of dimension 5, 6, or 7 has a Riemannian metric of positive scalar curvature. They further introduced the new class of enlargeable manifolds , distinguished by a condition in homotopy theory . [GL80a] They showed that Riemannian metrics of positive scalar curvature cannot exist on such manifolds. A particular consequence is that the torus cannot support any Riemannian metric of positive scalar curvature, which had been a major conjecture previously resolved by Schoen and Yau in low dimensions. [ 24 ]
In 1981, Gromov identified topological restrictions, based upon Betti numbers , on manifolds which admit Riemannian metrics of nonnegative sectional curvature . [G81a] The principal idea of his work was to combine Karsten Grove and Katsuhiro Shiohama's Morse theory for the Riemannian distance function, with control of the distance function obtained from the Toponogov comparison theorem , together with the Bishop–Gromov inequality on volume of geodesic balls. [ 25 ] This resulted in topologically controlled covers of the manifold by geodesic balls, to which spectral sequence arguments could be applied to control the topology of the underlying manifold. The topology of lower bounds on sectional curvature is still not fully understood, and Gromov's work remains as a primary result. As an application of Hodge theory , Peter Li and Yau were able to apply their gradient estimates to find similar Betti number estimates which are weaker than Gromov's but allow the manifold to have convex boundary. [ 26 ]
In Jeff Cheeger 's fundamental compactness theory for Riemannian manifolds, a key step in constructing coordinates on the limiting space is an injectivity radius estimate for closed manifolds . [ 27 ] Cheeger, Gromov, and Michael Taylor localized Cheeger's estimate, showing how to use Bishop−Gromov volume comparison to control the injectivity radius in absolute terms by curvature bounds and volumes of geodesic balls. [CGT82] Their estimate has been used in a number of places where the construction of coordinates is an important problem. [ 28 ] [ 29 ] [ 30 ] A particularly well-known instance of this is to show that Grigori Perelman 's "noncollapsing theorem" for Ricci flow , which controls volume, is sufficient to allow applications of Richard Hamilton 's compactness theory. [ 31 ] [ 32 ] [ 33 ] Cheeger, Gromov, and Taylor applied their injectivity radius estimate to prove Gaussian control of the heat kernel , although these estimates were later improved by Li and Yau as an application of their gradient estimates. [ 26 ]
Gromov made foundational contributions to systolic geometry . Systolic geometry studies the relationship between size invariants (such as volume or diameter) of a manifold M and its topologically non-trivial submanifolds (such as non-contractible curves). In his 1983 paper "Filling Riemannian manifolds" [G83] Gromov proved that every essential manifold M {\displaystyle M} with a Riemannian metric contains a closed non-contractible geodesic of length at most C ( n ) Vol ( M ) 1 / n {\displaystyle C(n)\operatorname {Vol} (M)^{1/n}} . [ 34 ]
In 1981, Gromov introduced the Gromov–Hausdorff metric , which endows the set of all metric spaces with the structure of a metric space. [G81b] More generally, one can define the Gromov-Hausdorff distance between two metric spaces, relative to the choice of a point in each space. Although this does not give a metric on the space of all metric spaces, it is sufficient in order to define "Gromov-Hausdorff convergence" of a sequence of pointed metric spaces to a limit. Gromov formulated an important compactness theorem in this setting, giving a condition under which a sequence of pointed and "proper" metric spaces must have a subsequence which converges. This was later reformulated by Gromov and others into the more flexible notion of an ultralimit . [G93]
Gromov's compactness theorem had a deep impact on the field of geometric group theory . He applied it to understand the asymptotic geometry of the word metric of a group of polynomial growth , by taking the limit of well-chosen rescalings of the metric. By tracking the limits of isometries of the word metric, he was able to show that the limiting metric space has unexpected continuities, and in particular that its isometry group is a Lie group . [G81b] As a consequence he was able to settle the Milnor-Wolf conjecture as posed in the 1960s, which asserts that any such group is virtually nilpotent . Using ultralimits, similar asymptotic structures can be studied for more general metric spaces. [G93] Important developments on this topic were given by Bruce Kleiner , Bernhard Leeb, and Pierre Pansu , among others. [ 35 ] [ 36 ]
Another consequence is Gromov's compactness theorem , stating that the set of compact Riemannian manifolds with Ricci curvature ≥ c and diameter ≤ D is relatively compact in the Gromov–Hausdorff metric. [G81b] The possible limit points of sequences of such manifolds are Alexandrov spaces of curvature ≥ c , a class of metric spaces studied in detail by Burago , Gromov and Perelman in 1992. [BGP92]
Along with Eliyahu Rips , Gromov introduced the notion of hyperbolic groups . [G87]
Gromov's theory of pseudoholomorphic curves is one of the foundations of the modern study of symplectic geometry . [G85] Although he was not the first to consider pseudo-holomorphic curves, he uncovered a "bubbling" phenomena paralleling Karen Uhlenbeck 's earlier work on Yang–Mills connections , and Uhlenbeck and Jonathan Sack's work on harmonic maps . [ 37 ] [ 38 ] In the time since Sacks, Uhlenbeck, and Gromov's work, such bubbling phenomena has been found in a number of other geometric contexts. The corresponding compactness theorem encoding the bubbling allowed Gromov to arrive at a number of analytically deep conclusions on existence of pseudo-holomorphic curves. A particularly famous result of Gromov's, arrived at as a consequence of the existence theory and the monotonicity formula for minimal surfaces , is the " non-squeezing theorem ," which provided a striking qualitative feature of symplectic geometry. Following ideas of Edward Witten , Gromov's work is also fundamental for Gromov-Witten theory , which is a widely studied topic reaching into string theory , algebraic geometry , and symplectic geometry . [ 39 ] [ 40 ] [ 41 ] From a different perspective, Gromov's work was also inspirational for much of Andreas Floer 's work. [ 42 ]
Yakov Eliashberg and Gromov developed some of the basic theory for symplectic notions of convexity. [EG91] They introduce various specific notions of convexity, all of which are concerned with the existence of one-parameter families of diffeomorphisms which contract the symplectic form. They show that convexity is an appropriate context for an h-principle to hold for the problem of constructing certain symplectomorphisms . They also introduced analogous notions in contact geometry ; the existence of convex contact structures was later studied by Emmanuel Giroux . [ 43 ]
Books
Major articles
Media related to Mikhail Leonidovich Gromov at Wikimedia Commons | https://en.wikipedia.org/wiki/Mikhael_Gromov_(mathematician) |
Mikhail Semyonovich Tsvet , also spelt Tsvett , Tswett , Tswet , Zwet , and Cvet ( Russian : Михаил Семёнович Цвет; 14 May 1872 – 26 June 1919) was a Russian-Italian botanist who invented chromatography . His last name is Russian for "colour" and is also the root word of " flower ."
Mikhail Tsvet was born on 14 May 1872 in Asti , Italy. His mother was Italian, and his father was a Russian official. His mother died soon after his birth, and he was raised in Geneva , Switzerland. He received his BS degree from the Department of Physics and Mathematics at the University of Geneva in 1893. However, he decided to dedicate himself to botany and received his PhD degree in 1896 for his work on cell physiology . He moved to Saint Petersburg , Russia, in 1896 because his father was recalled from the foreign service. There he started to work at the Biological Laboratory of the Russian Academy of Sciences . His Geneva degrees were not recognized in Russia, and he had to earn Russian degrees. In 1897 he became a teacher of botany courses for women. In 1902 he became a laboratory assistant at the Institute of Plant Physiology of the Warsaw University (now in Poland). In 1903 he became an assistant professor and taught also at other Warsaw universities. After the beginning of World War I , the Warsaw University of Technology was evacuated to Moscow, Russia, and in 1916 again to Gorki near Moscow. In 1917 he became a Professor of Botany and the director of the botanical gardens at the University of Tartu (Yuryev) (now in Estonia ). In 1918 when German troops occupied the city, the university was evacuated to Voronezh , a large city in the south of Central Russia . Tsvet died of a chronic inflammation of the throat on 26 June 1919 at the age of 47.
Mikhail Tsvet invented chromatography in 1900 during his research on plant pigments . He used liquid-adsorption column chromatography with calcium carbonate as adsorbent and petrol ether / ethanol mixtures as eluent to separate chlorophylls and carotenoids . The method was described on 30 December 1901 at the XI Congress of Naturalists and Physicians (XI съезд естествоиспытателей и врачей) in St. Petersburg. The first printed description was in 1905, in the Proceedings of the Warsaw Society of Naturalists, biology section . [ 1 ] He first used the term "chromatography" in print in 1906 in his two papers about chlorophyll in the German botanical journal, Berichte der Deutschen botanischen Gesellschaft . [ 2 ] [ 3 ] In 1907 he demonstrated his chromatograph for the German Botanical Society.
For several reasons, Tsvet's work was long ignored: [ 4 ] the violent political upheaval in Russia at the beginning of the 20th century, the fact that Tsvet originally published only in Russian (making his results largely inaccessible to western scientists), and an article denying Tsvet's findings. Richard Willstätter and Arthur Stoll tried to repeat Tsvet's experiments, but because they used an overly aggressive adsorbent (destroying the chlorophyll), were not able to do so. [ 5 ] They published their results and Tsvet's chromatography method fell into obscurity. It was revived 10 years after his death thanks to Austrian biochemist Richard Kuhn and his student, German scientist Edgar Lederer [ 6 ] [ 7 ] [ 8 ] [ 9 ] as well as the work of A. J. Martin and R. L. Synge . [ 10 ]
The standard botanical author abbreviation Tswett is applied to plants that he described. | https://en.wikipedia.org/wiki/Mikhail_Tsvet |
Mikhailo Lomonosov ( MVL-300 , or Mikhailo , or more commonly Lomonosov ; MVL stands for Mikhail Vasilyevich Lomonosov [ 4 ] ) was an astronomical satellite operated by Moscow State University (MSU) named after Mikhail Lomonosov . [ 5 ]
The objective of the mission was the observation of gamma-ray bursts , high-energy cosmic rays and transient phenomena in the Earth's upper atmosphere. [ 5 ]
The mission launch was initially planned for 2011 when 300 years since the birthday of Mikhail Lomonosov was celebrated. [ 6 ] After several postponements the mission was finally launched on 28 April 2016 from the Vostochny Cosmodrome by the Soyuz 2.1a launch vehicle, on the first launch from new cosmodrome. [ 7 ]
The spacecraft is equipped with seven scientific instruments: [ 4 ] [ 1 ]
The TUS-telescope aboard Lomonosov stopped data collection in late 2017. [ 8 ]
On June 30, 2018, it was published that the Lomonosov-satellite had suffered a malfunction in its data transmission system. Attempts to fix the problem were underway, but fixing the problem had so far been unsuccessful. [ 9 ]
As of 14 January 2019, the problems had not been solved and all the scientific equipment of the satellite were powered off. The recovery attempts continued (some systems of the satellite were responsive, the problem was with scientific payload systems). Before succumbing to these difficulties, the satellite had worked for one and a half years for its intended purpose. With the failure of the Lomonosov satellite and the Spektr-R end of mission on 30 May 2019, the Russian space program lost both of its scientific satellites until the launch of Spektr-RG in July 2019.
The satellite decayed from orbit on 16 December 2023. [ 10 ] | https://en.wikipedia.org/wiki/Mikhailo_Lomonosov_(satellite) |
Milan Mrksich (born 15 August 1968) is an American chemist. He is the Henry Wade Rogers Professor at Northwestern University with appointments in chemistry , biomedical engineering and cell & developmental biology. [ 1 ] He also served as both the founding director of the Center for Synthetic Biology and as an associate director of the Robert H. Lurie Comprehensive Cancer Center at Northwestern. [ 2 ] [ 3 ] Mrksich also served as the Vice President for Research of Northwestern University. [ 4 ]
His research involves the chemistry and synthesis of surfaces that contact biological environments. His laboratory has pioneered several technologies, including strategies to integrate living cells with microelectronic devices, methods to enable high throughput assays for drug discovery, and approaches to making synthetic fusion proteins for applications as therapeutics. Most notably, he developed the SAMDI-MS biochip technology that allows for high-throughput quantification of surface-based biochemical assays using MALDI mass spectrometry . Through SAMDI-MS, Mrksich has become a leader in using label-free technology for drug discovery, founding the company SAMDI Tech in 2011 that primarily serves global pharmaceutical companies . [ 5 ] His work has been described in over 240 publications (h-index 98), 500 invited talks, and 18 patents. [ 6 ]
Milan Mrksich ( Serbian Cyrillic : Милан Мркшић [ citation needed ] ) was born on August 15, 1968, to Serbian immigrants and raised in Justice, Illinois . [ 7 ] He graduated from University of Illinois at Urbana-Champaign in 1989 with a B.S. in chemistry working in the laboratory of Steven Zimmerman on molecular tweezers. He completed his PhD in organic chemistry in 1994 from Caltech under chemist Peter B. Dervan . After graduate school, he was an American Chemical Society postdoctoral fellow at Harvard University under chemist George M. Whitesides before joining the faculty at the University of Chicago in 1996. He worked there for 15 years before joining the faculty at Northwestern University in 2011. [ 8 ]
Early on as an independent investigator, Mrksich developed and executed the concept of dynamic substrates for cell culture. Here, self-assembled monolayers (SAMs) present cell adhesive ligands with perfect control over density and orientation against a non-adhesive, inert background, such as ethylene glycol . These monolayers can be further modified with electroactive groups that selectively release immobilized ligand when stimulated with an electric potential. Several strategies using this approach were studied in the context of cell signaling, migration, and co-culture. [ 9 ] [ 10 ] [ 11 ] Subsequent cell-based work focused on developing methods to pattern cells on the aforementioned SAMs. The work has mostly utilized microcontact printing to confine adherent cells into defined positions, shapes, and sizes. Ultimately, his group's work has revealed examples of how cellular mechanics and cytoskeletal structure influence phenotype. A primary example of this involved investigating how cell shape exerts control over the differentiation of mesenchymal stem cells. [ 12 ] Further work utilized these patterned monolayers to investigate the relationship between various cytoskeletal elements and to observe complex phenotypic differences in patient-derived neuroprogenitor cells. [ 13 ] [ 14 ] Recent work in the group investigating cell patterning has utilized photo active adhesive peptides, allowing for local, spatiotemporal control of cell adhesion to study gap junction formation. [ 15 ]
While performing much of the early dynamic substrate and cell patterning work, Mrksich also pioneered an assay platform that utilizes SAMs of alkanethiolates on gold. [ 16 ] [ 17 ] The monolayers contain capture ligands (e.g. biotin or maleimide ) that can selectively immobilize a peptide of interest. Subsequently, the monolayer can treated with a specific enzyme or a complex mixture, such as cell lysate, that can modify the peptide through various biological processes (e.g. phosphorylation ). For quality control, the monolayers present these peptides against a background of tri( ethylene glycol ) groups to prevent the nonspecific adsorption of protein to the surface that could obfuscate the reaction signal and, therefore, enable quantitative and reproducible assays. Most significantly, the monolayers can be characterized with MALDI mass spectrometry in a technique known as SAMDI-MS, which provides the masses of the substituted alkanethiolates and, therefore, the mass change of the immobilized peptide that results from enzyme activity. The method is compatible with standard array formats and liquid handling robotics, allowing a throughput in the tens of thousands of reactions per day. Importantly, the matrix-assisted laser desorption time-of-flight mass spectrometry (MALDI-TOF) analysis provides a fast and quantitative mass shift readout without the need for labels.
Most recently, Mrksich's group has focused on developing a technique for assembling large molecular structures with perfectly defined structures and orientations, known as Megamolecules . This is primarily done through use of fusion proteins and irreversible inhibitor linkers that assemble stable intermediates. [ 18 ] Structure-function relationships, including synthesis of cyclic and antibody-mimic structures have been investigated for potential therapeutic application. [ 19 ] [ 20 ]
Mrksich has been an active entrepreneur over the past twenty years. He co-founded SAMDI Tech in 2011, which uses his label-free assay technology to perform high throughput screens for pharmaceutical companies. SAMDI Tech entered into a partnership with Charles River Laboratories in 2018 and was purchased by CRL in 2023. [ 21 ] [ 22 ] Mrksich also co-founded WMR Biomedical in 2008, with George Whitesides and Carmichael Roberts to develop resorbable stent materials; this company was renamed Lyra Therapeutics and had an IPO in 2020 (NASDAQ LYRA) and has drug-eluting stents in clinical trials for ear, nose and throat disease, including chronic rhinosinusitis. [ 23 ] Mrksich has recently founded ModuMab Therapeutics, which applies his megamolecule technology to creating antibody mimics for a broad range of diseases.
Mrksich has also been active in serving the scientific community in a number of roles. These include his current service as the Scientific Director [ 24 ] of the Searle Scholars Program , as a member of the Board of Governors [ 25 ] for Argonne National Laboratory , and as a member of the Board of Directors [ 26 ] for the Camille & Henry Dreyfus Foundation . His past appointments include service and chairing DARPA ’s Defense Sciences Research Council and many program advisory committees.
Milan lives in Hinsdale, Illinois with his two children. [ citation needed ] | https://en.wikipedia.org/wiki/Milan_Mrksich |
Milan Randić (born 1 October 1930) [ 1 ] [ 2 ] is a Croatian American scientist recognized as one of the leading experts in the field of computational chemistry . [ 3 ]
Randić was born in the city of Belgrade , where his parents, originally from Kostrena in the Croatian Primorje, lived at the time. Kostrena is well known for its maritime tradition, with many shipowners and seamen among its residents. Randić's ancestors were shipowners and captains. In 1941, his family moved to Zagreb, where he continued his education.
After completing Gymnasium in Zagreb, he studied Theoretical Physics at the University of Zagreb from 1949 to 1953. He then studied for Ph. D degree at the University of Cambridge , England from 1954 to 1958.
From 1960 to 1970, Randić worked at the Ruđer Bošković Institute in Zagreb, Croatia, where he founded the Theoretical Chemistry Group. Between 1971 and 1980, he was a visiting professor at various universities in the United States, including Johns Hopkins, MIT, Harvard, Tufts, and Cornell. His research during this period increasingly focused on the application of Discrete Mathematics and Graph Theory to the characterization of molecules and biomolecules.
From 1980 to 1997, Randić was a professor in the Department of Mathematics and Computer Science at Drake University in Des Moines, Iowa. Over the past 15 years, he has spent three months each year at the National Institute of Chemistry in Ljubljana, Slovenia, collaborating with scientists in its Laboratory for Chemometrics.
Randić has been a major contributor to the development of mathematical chemistry , in particular to the development and use of molecular descriptors based on the use of Graph Theory. In 1975 he introduced the Randić index , the first connectivity index, which has been widely used in the characterization of molecules. [ 4 ]
He is a corresponding member of the Croatian Academy of Sciences and Arts [ 5 ] and founder of the International Academy of Mathematical Chemistry , headquartered in Dubrovnik, Croatia. Since 2000, his research has shifted towards Bioinformatics, focusing on the graphical representation and numerical characterization of DNA, proteins, and the proteome. Despite this shift, his interest in Kekulé valence structures and aromaticity remains strong. He is an Honorary Member of The Croatian Chemical Society , The International Academy of Mathematical Chemistry , and The National Institute of Chemistry, Ljubljana, Slovenia. [ 6 ]
Randić is also interested in developing Nobel , a universal ideographic writing system . [ 3 ] | https://en.wikipedia.org/wiki/Milan_Randić |
The Milas hydroxylation is an organic reaction converting an alkene to a vicinal diol , and was developed by Nicholas A. Milas in the 1930s. [ 1 ] [ 2 ] The cis-diol is formed by reaction of alkenes with hydrogen peroxide and either ultraviolet light or a catalytic osmium tetroxide , [ 3 ] vanadium pentoxide , or chromium trioxide . [ 4 ]
The reaction has been superseded in synthetic chemistry by the Upjohn dihydroxylation and later by the Sharpless asymmetric dihydroxylation .
The proposed mechanism for the Milas hydroxylation involves the initial combination of hydrogen peroxide and the osmium tetroxide catalyst to form an intermediate, which then adds to the alkene, followed by a cleavage that forms the product and regenerates the OsO 4 . [ 2 ]
One variation of the Milas hydroxylation (shown in the mechanism above) requires stoichiometric amounts of osmium tetroxide, which is toxic (highly volatile) and expensive. [ 5 ] Furthermore, in Milas's own experiments his yields ranged from 37.6% to 60.2% for the cis-vicinal diol. [ 1 ] Note that a vicinal diol is a molecule in which two hydroxy atoms are located on adjacent carbon atoms. Vicinal diols can be oxidized to aldehydes and ketones, rendering their synthesis useful. [ 6 ]
The catalyst, osmium tetroxide, also known as Merck osmic acid, dissolves readily in tertiary butyl alcohol which implies that the solution in which the reaction occurs is stable, unless isobutylene is already present. In the presence of isobutylene most of the osmium tetroxide is reduced to an insoluble black colloidal oxide. This colloidal oxide is a very active catalyst in decomposition of hydrogen peroxide. Thus, in aqueous solutions osmium tetroxide decomposes hydrogen peroxide, whereas an anhydrous tertiary butyl alcohol decomposes at a much slower rate. [ 1 ]
The Upjohn dihydroxylation and the Sharpless asymmetric dihydroxylation both result in cis-vicinal diols as well, and do not require the toxic, expensive catalyst. [ 7 ]
In 1949, the Milas hydroxylation was applied to a study of the demethylation of N-Dimethyl-p-Amino-azobenzene, otherwise known as butter yellow. Hydrogen peroxide in tertiary butyl alcohol with osmium tetroxide as a catalyst (Milas reagents) was examined to determine the parallels of the reaction with butter yellow in vivo versus in vitro . Previously it was discovered that the hydroxylation of butter yellow or its demethylated derivatives exist within rats, and thus rats were deemed suitable for the comparison. Absorption spectra were examined to confirm the results of the experiment, which found that the product of the Milas hydroxylation was one of the obtained products. [ 8 ] | https://en.wikipedia.org/wiki/Milas_hydroxylation |
The Miles and Misra Method (or surface viable count) is a technique used in Microbiology to determine the number of colony forming units in a bacterial suspension or homogenate .
The technique was first described in 1938 by Miles, Misra and Irwin who at the time were working at the LSHTM . [ 1 ] The Miles and Misra method has been shown to be precise. [ 2 ]
Materials
Method
Advantages | https://en.wikipedia.org/wiki/Miles_and_Misra_method |
In complex analysis , de Branges's theorem , or the Bieberbach conjecture , is a theorem that gives a necessary condition on a holomorphic function in order for it to map the open unit disk of the complex plane injectively to the complex plane. It was posed by Ludwig Bieberbach ( 1916 ) and finally proven by Louis de Branges ( 1985 ).
The statement concerns the Taylor coefficients a n {\displaystyle a_{n}} of a univalent function , i.e. a one-to-one holomorphic function that maps the unit disk into the complex plane, normalized as is always possible so that a 0 = 0 {\displaystyle a_{0}=0} and a 1 = 1 {\displaystyle a_{1}=1} . That is, we consider a function defined on the open unit disk which is holomorphic and injective ( univalent ) with Taylor series of the form
Such functions are called schlicht . The theorem then states that
The Koebe function (see below) is a function for which a n = n {\displaystyle a_{n}=n} for all n {\displaystyle n} , and it is schlicht, so we cannot find a stricter limit on the absolute value of the n {\displaystyle n} th coefficient.
The normalizations
mean that
This can always be obtained by an affine transformation : starting with an arbitrary injective holomorphic function g {\displaystyle g} defined on the open unit disk and setting
Such functions g {\displaystyle g} are of interest because they appear in the Riemann mapping theorem .
A schlicht function is defined as an analytic function f {\displaystyle f} that is one-to-one and satisfies f ( 0 ) = 0 {\displaystyle f(0)=0} and f ′ ( 0 ) = 1 {\displaystyle f'(0)=1} . A family of schlicht functions are the rotated Koebe functions
with α {\displaystyle \alpha } a complex number of absolute value 1 {\displaystyle 1} . If f {\displaystyle f} is a schlicht function and | a n | = n {\displaystyle |a_{n}|=n} for some n ≥ 2 {\displaystyle n\geq 2} , then f {\displaystyle f} is a rotated Koebe function.
The condition of de Branges' theorem is not sufficient to show the function is schlicht, as the function
shows: it is holomorphic on the unit disc and satisfies | a n | ≤ n {\displaystyle |a_{n}|\leq n} for all n {\displaystyle n} , but it is not injective since f ( − 1 / 2 + z ) = f ( − 1 / 2 − z ) {\displaystyle f(-1/2+z)=f(-1/2-z)} .
A survey of the history is given by Koepf (2007) .
Bieberbach (1916) proved | a 2 | ≤ 2 {\displaystyle |a_{2}|\leq 2} , and stated the conjecture that | a n | ≤ n {\displaystyle |a_{n}|\leq n} . Löwner (1917) and Nevanlinna (1921) independently proved the conjecture for starlike functions .
Then Charles Loewner ( Löwner (1923) ) proved | a 3 | ≤ 3 {\displaystyle |a_{3}|\leq 3} , using the Löwner equation . His work was used by most later attempts, and is also applied in the theory of Schramm–Loewner evolution .
Littlewood (1925 , theorem 20) proved that | a n | ≤ e n {\displaystyle |a_{n}|\leq en} for all n {\displaystyle n} , showing that the Bieberbach conjecture is true up to a factor of e = 2.718 … {\displaystyle e=2.718\ldots } Several authors later reduced the constant in the inequality below e {\displaystyle e} .
If f ( z ) = z + ⋯ {\displaystyle f(z)=z+\cdots } is a schlicht function then φ ( z ) = z ( f ( z 2 ) / z 2 ) 1 / 2 {\displaystyle \varphi (z)=z(f(z^{2})/z^{2})^{1/2}} is an odd schlicht function. Paley and Littlewood ( 1932 ) showed that its Taylor coefficients satisfy b k ≤ 14 {\displaystyle b_{k}\leq 14} for all k {\displaystyle k} . They conjectured that 14 {\displaystyle 14} can be replaced by 1 {\displaystyle 1} as a natural generalization of the Bieberbach conjecture. The Littlewood–Paley conjecture easily implies the Bieberbach conjecture using the Cauchy inequality, but it was soon disproved by Fekete & Szegő (1933) , who showed there is an odd schlicht function with b 5 = 1 / 2 + exp ( − 2 / 3 ) = 1.013 … {\displaystyle b_{5}=1/2+\exp(-2/3)=1.013\ldots } , and that this is the maximum possible value of b 5 {\displaystyle b_{5}} . Isaak Milin later showed that 14 {\displaystyle 14} can be replaced by 1.14 {\displaystyle 1.14} , and Hayman showed that the numbers b k {\displaystyle b_{k}} have a limit less than 1 {\displaystyle 1} if f {\displaystyle f} is not a Koebe function (for which the b 2 k + 1 {\displaystyle b_{2k+1}} are all 1 {\displaystyle 1} ). So the limit is always less than or equal to 1 {\displaystyle 1} , meaning that Littlewood and Paley's conjecture is true for all but a finite number of coefficients. A weaker form of Littlewood and Paley's conjecture was found by Robertson (1936) .
The Robertson conjecture states that if
is an odd schlicht function in the unit disk with b 1 = 1 {\displaystyle b_{1}=1} then for all positive integers n {\displaystyle n} ,
Robertson observed that his conjecture is still strong enough to imply the Bieberbach conjecture, and proved it for n = 3 {\displaystyle n=3} . This conjecture introduced the key idea of bounding various quadratic functions of the coefficients rather than the coefficients themselves, which is equivalent to bounding norms of elements in certain Hilbert spaces of schlicht functions.
There were several proofs of the Bieberbach conjecture for certain higher values of n {\displaystyle n} , in particular Garabedian & Schiffer (1955) proved | a 4 | ≤ 4 {\displaystyle |a_{4}|\leq 4} , Ozawa (1969) and Pederson (1968) proved | a 6 | ≤ 6 {\displaystyle |a_{6}|\leq 6} , and Pederson & Schiffer (1972) proved | a 5 | ≤ 5 {\displaystyle |a_{5}|\leq 5} .
Hayman (1955) proved that the limit of a n / n {\displaystyle a_{n}/n} exists, and has absolute value less than 1 {\displaystyle 1} unless f {\displaystyle f} is a Koebe function. In particular this showed that for any f {\displaystyle f} there can be at most a finite number of exceptions to the Bieberbach conjecture.
The Milin conjecture states that for each schlicht function on the unit disk, and for all positive integers n {\displaystyle n} ,
where the logarithmic coefficients γ n {\displaystyle \gamma _{n}} of f {\displaystyle f} are given by
Milin (1977) showed using the Lebedev–Milin inequality that the Milin conjecture (later proved by de Branges) implies the Robertson conjecture and therefore the Bieberbach conjecture.
Finally de Branges (1987) proved | a n | ≤ n {\displaystyle |a_{n}|\leq n} for all n {\displaystyle n} .
The proof uses a type of Hilbert space of entire functions . The study of these spaces grew into a sub-field of complex analysis and the spaces have come to be called de Branges spaces . De Branges proved the stronger Milin conjecture ( Milin 1977 ) on logarithmic coefficients. This was already known to imply the Robertson conjecture ( Robertson 1936 ) about odd univalent functions, which in turn was known to imply the Bieberbach conjecture about schlicht functions ( Bieberbach 1916 ). His proof uses the Loewner equation , the Askey–Gasper inequality about Jacobi polynomials , and the Lebedev–Milin inequality on exponentiated power series.
De Branges reduced the conjecture to some inequalities for Jacobi polynomials, and verified the first few by hand. Walter Gautschi verified more of these inequalities by computer for de Branges (proving the Bieberbach conjecture for the first 30 or so coefficients) and then asked Richard Askey whether he knew of any similar inequalities. Askey pointed out that Askey & Gasper (1976) had proved the necessary inequalities eight years before, which allowed de Branges to complete his proof. The first version was very long and had some minor mistakes which caused some skepticism about it, but these were corrected with the help of members of the Leningrad seminar on Geometric Function Theory ( Leningrad Department of Steklov Mathematical Institute ) when de Branges visited in 1984.
De Branges proved the following result, which for ν = 0 {\displaystyle \nu =0} implies the Milin conjecture (and therefore the Bieberbach conjecture).
Suppose that ν > − 3 / 2 {\displaystyle \nu >-3/2} and σ n {\displaystyle \sigma _{n}} are real numbers for positive integers n {\displaystyle n} with limit 0 {\displaystyle 0} and such that
is non-negative, non-increasing, and has limit 0 {\displaystyle 0} . Then for all Riemann mapping functions F ( z ) = z + ⋯ {\displaystyle F(z)=z+\cdots } univalent in the unit disk with
the maximum value of
is achieved by the Koebe function z / ( 1 − z ) 2 {\displaystyle z/(1-z)^{2}} .
A simplified version of the proof was published in 1985 by Carl FitzGerald and Christian Pommerenke ( FitzGerald & Pommerenke (1985) ), and an even shorter description by Jacob Korevaar ( Korevaar (1986) ). A very short proof avoiding use of the inequalities of Askey and Gasper was later found by Lenard Weinstein ( Weinstein (1991) ). | https://en.wikipedia.org/wiki/Milin_conjecture |
Military engineering is loosely defined as the art, science, and practice of designing and building military works and maintaining lines of military transport and military communications . Military engineers are also responsible for logistics behind military tactics. Modern military engineering differs from civil engineering . In the 20th and 21st centuries, military engineering also includes CBRN defense and other engineering disciplines such as mechanical and electrical engineering techniques. [ 1 ]
According to NATO , "military engineering is that engineer activity undertaken, regardless of component or service, to shape the physical operating environment. Military engineering incorporates support to maneuver and to the force as a whole, including military engineering functions such as engineer support to force protection, counter improvised explosive devices, environmental protection, engineer intelligence and military search. Military engineering does not encompass the activities undertaken by those 'engineers' who maintain, repair and operate vehicles, vessels, aircraft, weapon systems and equipment." [ 2 ]
Military engineering is an academic subject taught in military academies or schools of military engineering . The construction and demolition tasks related to military engineering are usually performed by military engineers including soldiers trained as sappers or pioneers . [ 3 ] In modern armies, soldiers trained to perform such tasks while well forward in battle and under fire are often called combat engineers .
In some countries, military engineers may also perform non-military construction tasks in peacetime such as flood control and river navigation works, but such activities do not fall within the scope of military engineering.
The word engineer was initially used in the context of warfare, dating back to 1325 when engine’er (literally, one who operates an engine) referred to "a constructor of military engines". [ 4 ] In this context, "engine" referred to a military machine, i. e., a mechanical contraption used in war (for example, a catapult ).
As the design of civilian structures such as bridges and buildings developed as a technical discipline, the term civil engineering [ 5 ] entered the lexicon as a way to distinguish between those specializing in the construction of such non-military projects and those involved in the older discipline. As the prevalence of civil engineering outstripped engineering in a military context and the number of disciplines expanded, the original military meaning of the word "engineering" is now largely obsolete. In its place, the term "military engineering" has come to be used.
In ancient times, military engineers were responsible for siege warfare and building field fortifications , temporary camps and roads. The most notable engineers of ancient times were the Romans and Chinese , who constructed huge siege-machines (catapults, battering rams and siege towers ). The Romans were responsible for constructing fortified wooden camps and paved roads for their legions . Many of these Roman roads are still in use today. [ 6 ]
The first civilization to have a dedicated force of military engineering specialists were the Romans, whose army contained a dedicated corps of military engineers known as architecti . This group was pre-eminent among its contemporaries. The scale of certain military engineering feats, such as the construction of a double-wall of fortifications 30 miles (48 km) long, in just 6 weeks to completely encircle the besieged city of Alesia in 52 B.C.E. , is an example. Such military engineering feats would have been completely new, and probably bewildering and demoralizing, to the Gallic defenders. Vitruvius is the best known of these Roman army engineers, due to his writings surviving.
Examples of battles before the early modern period where military engineers played a decisive role include the Siege of Tyre under Alexander the Great , the Siege of Masada by Lucius Flavius Silva as well as the Battle of the Trench under the suggestion of Salman the Persian to dig a trench.
For about 600 years after the fall of the Roman Empire , the practice of military engineering barely evolved in the west. In fact, much of the classic techniques and practices of Roman military engineering were lost. Through this period, the foot soldier (who was pivotal to much of the Roman military engineering capability) was largely replaced by mounted soldiers. It was not until later in the Middle Ages , that military engineering saw a revival focused on siege warfare. [ 7 ]
Military engineers planned castles and fortresses. When laying siege, they planned and oversaw efforts to penetrate castle defenses. When castles served a military purpose, one of the tasks of the sappers was to weaken the bases of walls to enable them to be breached before means of thwarting these activities were devised. Broadly speaking, sappers were experts at demolishing or otherwise overcoming or bypassing fortification systems.
With the 14th-century development of gunpowder , new siege engines in the form of cannons appeared. Initially military engineers were responsible for maintaining and operating these new weapons just as had been the case with previous siege engines. In England, the challenge of managing the new technology resulted in the creation of the Office of Ordnance around 1370 in order to administer the cannons, armaments and castles of the kingdom. Both military engineers and artillery formed the body of this organization and served together until the office's successor, the Board of Ordnance was disbanded in 1855. [ 8 ]
In comparison to older weapons, the cannon was significantly more effective against traditional medieval fortifications . Military engineering significantly revised the way fortifications were built in order to be better protected from enemy direct and plunging shot. The new fortifications were also intended to increase the ability of defenders to bring fire onto attacking enemies. Fort construction proliferated in 16th-century Europe based on the trace italienne design. [ 9 ]
By the 18th century, regiments of foot (infantry) in the British, French, Prussian and other armies included pioneer detachments. In peacetime these specialists constituted the regimental tradesmen, constructing and repairing buildings, transport wagons, etc. On active service they moved at the head of marching columns with axes, shovels, and pickaxes, clearing obstacles or building bridges to enable the main body of the regiment to move through difficult terrain. The modern Royal Welch Fusiliers and French Foreign Legion still maintain pioneer sections who march at the front of ceremonial parades, carrying chromium-plated tools intended for show only. Other historic distinctions include long work aprons and the right to wear beards. In West Africa , the Ashanti army was accompanied to war by carpenters who were responsible for constructing shelters and blacksmiths who repaired weapons. [ 10 ] By the 18th century, sappers were deployed in the Dahomeyan army during assaults against fortifications. [ 11 ]
The Peninsular War (1808–14) revealed deficiencies in the training and knowledge of officers and men of the British Army in the conduct of siege operations and bridging. During this war low-ranking Royal Engineers officers carried out large-scale operations. They had under their command working parties of two or three battalions of infantry, two or three thousand men, who knew nothing in the art of siegeworks. Royal Engineers officers had to demonstrate the simplest tasks to the soldiers, often while under enemy fire. Several officers were lost and could not be replaced, and a better system of training for siege operations was required. On 23 April 1812 an establishment was authorised, by Royal Warrant, to teach "Sapping, Mining, and other Military Fieldworks" to the junior officers of the Corps of Royal Engineers and the Corps of Royal Military Artificers, Sappers and Miners.
The first courses at the Royal Engineers Establishment were done on an all ranks basis with the greatest regard to economy. To reduce staff the NCOs and officers were responsible for instructing and examining the soldiers. If the men could not read or write they were taught to do so, and those who could read and write were taught to draw and interpret simple plans. The Royal Engineers Establishment quickly became the centre of excellence for all fieldworks and bridging. Captain Charles Pasley , the director of the Establishment, was keen to confirm his teaching, and regular exercises were held as demonstrations or as experiments to improve the techniques and teaching of the Establishment. From 1833 bridging skills were demonstrated annually by the building of a pontoon bridge across the Medway which was tested by the infantry of the garrison and the cavalry from Maidstone . These demonstrations had become a popular spectacle for the local people by 1843, when 43,000 came to watch a field day laid on to test a method of assaulting earthworks for a report to the Inspector General of Fortifications. In 1869 the title of the Royal Engineers Establishment was changed to "The School of Military Engineering" (SME) as evidence of its status, not only as the font of engineer doctrine and training for the British Army , but also as the leading scientific military school in Europe.
The dawn of the internal combustion engine marked the beginning of a significant change in military engineering. With the arrival of the automobile at the end of the 19th century and heavier than air flight at the start of the 20th century, military engineers assumed a major new role in supporting the movement and deployment of these systems in war. Military engineers gained vast knowledge and experience in explosives . They were tasked with planting bombs, landmines and dynamite .
At the end of World War I , the standoff on the Western Front caused the Imperial German Army to gather experienced and particularly skilled soldiers to form "Assault Teams" which would break through the Allied trenches. With enhanced training and special weapons (such as flamethrowers ), these squads achieved some success, but too late to change the outcome of the war. In early WWII, however, the Wehrmacht "Pioniere" battalions proved their efficiency in both attack and defense, somewhat inspiring other armies to develop their own combat engineers battalions. Notably, the attack on Fort Eben-Emael in Belgium was conducted by Luftwaffe glider -deployed combat engineers.
The need to defeat the German defensive positions of the " Atlantic wall " as part of the amphibious landings in Normandy in 1944 led to the development of specialist combat engineer vehicles. These, collectively known as Hobart's Funnies , included a specific vehicle to carry combat engineers, the Churchill AVRE . These and other dedicated assault vehicles were organised into the specialised 79th Armoured Division and deployed during Operation Overlord – 'D-Day'.
Other significant military engineering projects of World War II include Mulberry harbour and Operation Pluto .
Modern military engineering still retains the Roman role of building field fortifications , road paving and breaching terrain obstacles. A notable military engineering task was, for example, breaching the Suez Canal during the Yom Kippur War .
Military engineers can come from a variety of engineering programs. They may be graduates of mechanical , electrical , civil , or industrial engineering . [ 12 ] [ 13 ]
Modern military engineering can be divided into three main tasks or fields: combat engineering, strategic support, and ancillary support. Combat engineering is associated with engineering on the battlefield. Combat engineers are responsible for increasing mobility on the front lines of war such as digging trenches and building temporary facilities in war zones. [ 14 ] Strategic support is associated with providing service in communication zones such as the construction of airfields and the improvement and upgrade of ports, roads and railways communication. Ancillary support includes provision and distribution of maps as well as the disposal of unexploded warheads. Military engineers construct bases, airfields, roads, bridges, ports, and hospitals. During peacetime before modern warfare, military engineers took the role of civil engineers by participating in the construction of civil-works projects. Nowadays, military engineers are almost entirely engaged in war logistics and preparedness. [ 1 ]
Explosives are defined as any system that produces rapidly expanding gases in a given volume in a short duration. [ 15 ] Specific military engineering occupations also extend to the field of explosives and demolitions and their usage on the battlefield. Explosive devices have been used on the battlefield for several centuries, in numerous operations from combat to area clearance. Earliest known development of explosives can be traced back to 10th-century China where the Chinese are credited with engineering the world's first known explosive, black powder . [ 15 ] Initially developed for recreational purposes, black powder later was utilized for military application in bombs and projectile propulsion in firearms. Engineers in the military who specialize in this field formulate and design many explosive devices to use in varying operating conditions. Such explosive compounds range from black powder to modern plastic explosives. [ 16 ] This particular is commonly listed under the role of combat engineers who demolitions expertise also includes mine and IED detection and disposal. For more information, see Bomb disposal .
Military engineers are key in all armed forces of the world, and invariably found either closely integrated into the force structure, or even into the combat units of the national troops.
Brazilian Army [ 17 ] engineers can be part of the Quadro de Engenheiros Militares, with its members trained or professionalized by the traditional Instituto Militar de Engenharia (IME) (Military Institute of Engineering) , or the Arma de Engenharia, with its members trained by the Academia Militar das Agulhas Negras (AMAN) (Agulhas Negras Military Academy).
In the Brazil's Navy , [ 18 ] engineers can occupy the Corpo de Engenheiros da Marinha, the Quadro Complementar de Oficiais da Armada and the Quadro Complementar de Oficiais Fuzileiros Navais. Officers can come from the Centro de Instrução Almirante Wandenkolk (CIAW) (Admiral Wandenkolk Instruction Center) and the Escola Naval (EN) (Naval School) which, through internal selection of the Navy, finish their graduation at the Universidade de São Paulo (USP) (University of São Paulo) .
The Quadro de Oficias Engenheiros of the Brazilian Air Force [ 19 ] is occupied by engineers professionalized by Centro de Instrução e Adaptação da Aeronáutica (CIAAR) (Air Force Instruction and Adaptation Center) and trained, or specialized, by Instituto Tecnológico de Aeronáutica (ITA) (Aeronautics Institute of Technology).
The Royal School of Military Engineering is the main training establishment for the British Army 's Royal Engineers . The RSME also provides training for the Royal Navy , Royal Air Force , other Arms and Services of the British Army , Other Government Departments, and Foreign and Commonwealth countries as required. These skills provide vital components in the Army's operational capability, and Royal Engineers are currently deployed in Afghanistan , Iraq , Cyprus , Bosnia , Kosovo , Kenya , Brunei , Falklands , Belize , Germany and Northern Ireland . Royal Engineers also take part in exercises in Saudi Arabia , Kuwait , Italy, Egypt , Jordan , Canada, Poland and the United States.
The prevalence of military engineering in the United States dates back to the American Revolutionary War when engineers would carry out tasks in the U.S. Army. During the war, they would map terrain to and build fortifications to protect troops from opposing forces. The first military engineering organization in the United States was the Army Corps of Engineers. Engineers were responsible for protecting military troops whether using fortifications or designing new technology and weaponry throughout the United States' history of warfare. The Army originally claimed engineers exclusively, but as the U.S. military branches expanded to the sea and sky, the need for military engineering sects in all branches increased. As each branch of the United States military expanded, technology adapted to fit their respective needs. [ 20 ] | https://en.wikipedia.org/wiki/Military_engineering |
Military geology is the application of geological theory to warfare and the peacetime practices of the military. The formal practice of military geology began during the Napoleonic Wars ; however, geotechnical knowledge has been applied since the earliest days of siege warfare . [ 1 ] [ 2 ] [ 3 ] In modern warfare military geologists are used for terrain analysis, engineering, and the identification of resources. Military geologists have included both specially trained military personnel and civilians incorporated into the military. The peacetime application of military geology includes the building of infrastructure, typically during local emergencies or foreign peacekeeping deployments. [ 1 ]
Warfare can change the physical geology. Examples of this include artillery shattering the bedrock on the Western Front during World War I [ 4 ] and the detonation of nuclear weapons creating new rock types. [ 5 ] Military research has also led to many important geological discoveries.
Geologists have been employed since the Napoleonic Wars to provide an analysis of terrain which was expected to become a war theater, both in case of an upcoming battle and to assess the difficulty of logistical supply. [ 3 ] [ 7 ] [ 8 ] Academically, it has been found that battles are likely to occur on rocks of Permian , Triassic , or Upper Carboniferous age, possibly due to their typical relief and drainage. [ 9 ] More practically, geology has been used in identifying the best Allied invasion sites during World War II, including those in North Africa , Italy, and France. [ 9 ] This included studying the properties of the sand of Normandy beaches , the tolerance of the soil in the hinterland to bombardment, the sediment of the English Channel sea floor, [ 10 ] and the occurrence of landslides in Sicily . [ 9 ] Likewise, German geologists created maps of southern England for Operation Sea Lion , identifying quarry locations and the suitability of rock types to excavate trenchers, etc. [ 11 ]
In the Demilitarized Zone between North and South Korea , very rugged terrain is due to the structure of metamorphic rocks, while the best flat land is underlain by granite . During the Korean War , these flat areas were used as military staging grounds by the North Koreans. It has been suggested that an understanding of the fracture and foliation patterns of the metamorphic rocks could help a field commander. [ 12 ]
This field partially overlaps with military geography . For this reason the British Army employed geographers in this role until the end of 1941, when it joined international common practice and started using geologists. [ 9 ]
Geologists have been involved in the construction of forts , tunnels, and bunkers both during military conflicts and in peacetime. [ 1 ] [ 13 ] This included digging tunnels in northeastern Italy and Austria during the so-called mine war in World War I. The rocks of the Dolomites are different from those in other theaters and specialists were required in order to design the tunnels. Explosives were then put in the tunnels and detonated, to cause rock falls and undercut enemy troops. [ 13 ] [ 14 ]
Geology is also used in determining the likely resistance of enemy defenses to shelling and bombing. [ 15 ] In World War II, this task was performed by the Allies as they advanced across German-occupied Europe, assessing the likely effect of bombing bridges and shelling defenses in light of the local geology. [ 9 ] During peacetime, similar methods have been used, such as the decision to locate the American Strategic Petroleum Reserve in the salt domes of the Gulf Coast . [ 16 ]
Geologists are used to determine both the location and accessibility of strategic and tactical resources during war. [ 1 ] [ 17 ] In the case of the D Day landings and the 2003 invasion of Iraq , ground water and aggregate were the two most important geological resources to identify for the campaign. The aggregate was required both for roading metal and for the construction of airfields. [ 17 ] [ 18 ] Since 1966, the German Army has also been using geologists to mitigate and predict the environmental effects of civilian resource extraction. [ 19 ]
Geology has been used in many military intelligence investigations. During World War II, the American Military Geology Unit discovered the origin of balloon bombs which had been dispatched towards North America from Japan. They accomplished this by determining from which beach the sand in the balloon's ballast originated. [ 20 ] Knowledge of rock types and seismic propagation also allows geologists to distinguish between natural and nuclear test initiated earthquakes . [ 3 ]
Military activity affects the physical geology. This was first noted through the intensive shelling on the Western Front during World War I, which caused the shattering of the bedrock and changed the rocks' permeability. [ 4 ] New minerals, rocks, and land-forms are also a byproduct of nuclear testing. [ 5 ]
Military research has led to many geological discoveries; however, secrecy has often delayed some of the possible progress. [ 21 ] The Austrian Army of World War I included geologists called Kriegsgeologen who were allowed to carry out non-military scientific investigation during the war. [ 13 ] [ 14 ] Discoveries have included new natural resource deposits [ 22 ] and the mapping of magnetic stripes on the ocean floor , leading to the idea of plate tectonics . [ 21 ] | https://en.wikipedia.org/wiki/Military_geology |
Military medical ethics (MME) is a specialized branch of medical ethics with implications for military ethics . Both are primarily fields of applied ethics , the study of moral values and judgments as they apply to the specific contexts of medicine and military affairs, respectively. MME encompasses the practical application of ethics by military physicians and other healthcare practitioners to dilemmas in military clinical and public health settings in which the patients may be friendly or enemy personnel or in which civilians are affected by military operations.
Within a garrison (peacetime or non-deployed) setting, precepts of MME may not differ much from medical ethics in a civilian context and usually employ the same decision-making processes. (Military physicians in the United States , for example, are licensed by at least one of the state medical boards and so are required to practice medicine according to the ethical stipulations of that state.) There is an intrinsic dichotomy, however, between medicine’s healing mission and a military’s (sometimes) destructive operations. Because military operations may result in the injury or death of enemy personnel (often deliberately so) and may involve the detention and interrogation of captured enemy personnel, medical ethics considerations for clinical providers assigned or attached to a military unit in a deployment or combat situation cannot always be identical to those in the civilian world. Ethical conflicts may emerge in the tension between responsibilities to the patient and duties to the command structure. The degree to which principles of medical ethics may justifiably be informed by, or even altered to accommodate, issues of national security is controversial. [ 1 ]
Discussions of MME often take as a point of departure the lessons to be learned from the perversion of medical practice by military physicians and others in the period leading up to and during World War II in Germany and Japan. They may also entail the more recently revealed Cold War radiation experiments undertaken by the United States government. Such discussions often center upon questions of whether these widely deplored activities of the past can be reasonably compared to present-day MME dilemmas.
Eagan, Sheena M. “Medicine as a Non-Lethal Weapon: The Ethics of ‘Winning Hearts and Minds’. ” Ethics and Armed Forces. Issue 2015/1: pp 9-15.
Eagan, Sheena M. “The Warrior in a White Coat: Moral Dilemmas, the Physician-Soldier & the Problem of Dual Loyalty.” Medical Corps International Forum. Volume 4: pp 4–7. | https://en.wikipedia.org/wiki/Military_medical_ethics |
Military miniaturism is a niche within the broader hobby of modeling focusing on military subjects. It is itself a rather broad subject, dealing with any scale model of military theme. It has an ever growing range of sub-hobbies, including scale figure modeling , armour modeling , model ship building , military aviation modeling , and historical wargaming .
Given the nature of military models, hobby practitioners for the most part lean toward realism in their creations. The way in which these creations are produced are nearly as wide as the hobby itself, ranging from building a model kit "from the box" to kitbashing to complete scratch building of a model. A wide range of kits are available on the market, [ 1 ] with built results ranging from hyper-detailed representations of a subject to crude playthings. Aircraft kits tend to contain a cockpit interior, with some kits opting to include a full engine as well. Armor kit often feature workable hatches for crew figures, and a few contain fully detailed interiors. Prices also range greatly, from below $20 to over $100. Most modern kits, of all scales, are made mainly from a hard plastic (typically styrene ) through injection molding. [ 2 ] However, high end kits typically contain photoetch. Despite the general trend towards plastic, some kits are still made entirely from resin or white metal. There are even kits made entirely of photoetched metal on the market. Construction is typically carried out using plastic cement or cyanoacrylate [ 1 ] ("super glue") to attach parts. Plastic parts normally require removal from a sprue use side cutters or a hobby knife. Parts are typically cleaned of seam lines and other imperfections from the molding process before attachment. [ 2 ] Upon completion of a model, it is common practice to paint it (see "finishing").
The next important step is to decide where to build. You can create a scale model almost anywhere, but here are a few tips for choosing your model kit workshop: [ 3 ]
Bench size – Simply put, you'll need a table or bench big enough to hold the many parts that make up your model car or model plane.
Lighting – You can't build a scale model in a dark environment (or at least you shouldn't try it) Lighting is so important. Make sure you have a spacious and bright environment to get started with scale modeling.
Storage containers – as mentioned above, your model kits come with many items. Avoid losing important components by storing them in organized boxes or drawers.
Making the right seat – the model car is a long-term project. Do your body a favor and choose a chair that you can sit comfortably in.
After market kits are add-ons to a main kit, meant to increase detail and correct incocities [ clarification needed ] in the original kit. [ 4 ] These kits come in many forms, but the most common materials used are white metal , resin and photoetched metal. Cast metal is typically used in replacement pats or to add small details, including main gun barrels and machine guns for armour models and wheel struts on aircraft. White metal has recently fallen out of favor on aftermarket kits in favor of resin. Resin pieces of models are typically produced either through molding or 3D printing . It is valued for its ability to hold crisp detail and be modified. [ 5 ] Tires for vehicles, heads for figures, and assorted other details are available in resin. Photoetch is perhaps the most prevalent form of aftermarket goods, appearing in most detail kits and some full models. It consists of thin sheets of brass or nickel that have been laser etched into a firm yet bendable and highly detailed part. [ 6 ] Given its versatility, photoetch is used in everything from seatbelts on aircraft to engine grilles on armored vehicles.
Painting scale models is common practice for modelers of all skill levels. [ 1 ] The goal is to reproduce the historical color scheme and markings to individualize and increase the realism of the model. Many painting techniques have evolved to serve scale modelers. These techniques use near limitless application processes, varying the consistency, type of paint, and application method. Three main tools are used to apply paint: brushes , spray cans , and airbrushes . Brushes are favored for detail work and general paintwork. Spray paints are used to base coat models or dioramas . Airbrushes are used in a multitude of rolls, filling the niche taken by the spray can as well as giving the modeler the ability to lay down easier soft-edged lines and highlights. Types of paint used are also varied. some modelers prefer acrylic paint , while other prefer enamel paint , and yet more prefer oil paint . However, most hobbyists use a combination of 2, or all three to paint their models. The process of painting a model commonly begins with a primer to help paint adhere to the surface of a model. From there, base colors are applied in either a monotone or a camouflage scheme, depending on the subject. Depth is than added using highlights, shadows, and washes (thinned paint that acts on capillary action). Vehicle markings, including numbers and roundels , are often reproduced with waterslide decals . [ 7 ]
Weathering is the act of distressing a model to give it a "used" look. [ 8 ] This skill is crucial in Military miniaturism, as it adds a level or realism necessary to replicate a combat worn object or person. Weathering comes in many forms, as it simply refers to anything that gives the model a look of use. This can come in the form of streaking, rust, mud, and staining among other things. Oil paints are popular for these tasks, due to their long working time. Oils are also often diluted to washes to add a filter or depth to a model. [ 9 ] Enamel streaking washes are also popular. Homemade weathering pigments (made from pastels , as well as marketed pigments, are used to create mud and rust effects. [ 10 ] Many textured paints are also available to add body to weathering effects. | https://en.wikipedia.org/wiki/Military_miniaturism |
Milivoje Kostic (also known as, M. Kostic or Milivoje M. Kostic ; in Serbian Cyrillic : Миливоје Костић; born 20 March 1952 in Bioska , Užice municipality, Serbia , ex-Yugoslavia ), is a Serbian-American thermodynamicist and professor emeritus of mechanical engineering at Northern Illinois University , [ 1 ] Professional Engineer (PE) in Illinois , and Section First Editor-in-Chief of Thermodynamics (2015-2024) of the journal Entropy . [ 2 ] He is an expert in energy fundamentals and applications, including nanotechnology, with emphasis on efficiency , efficient energy use and energy conservation , and environment and sustainability . [ 1 ]
Milivoje Kostic was born and raised in Serbia ( Yugoslavia at the time). He completed his "Dipl-Ing" (Diploma Engineer) degree in Mechanical Engineering at the University of Belgrade in 1975, [ 3 ] with the distinction of having the highest GPA in the mechanical engineering program history at the time. Then he worked as a researcher in thermal engineering and combustion at Vinca Institute for Nuclear Sciences , which then hosted the headquarters of the International Center for Heat and Mass Transfer (ICHMT), and later taught at the University of Belgrade. [ 3 ] In meantime, he spent three summers as an exchange visitor in England, West Germany, and the former Soviet Union. Kostic came to the University of Illinois at Chicago in 1981 as a Fulbright grantee, where he received his Ph.D. in mechanical engineering in 1984. He subsequently worked several years in industry before emigrated to the United States in 1986. After working for 26 years at Northern Illinois University , he retired in 2014 to focus on his fundamental research, and became Professor Emeritus in 2015. [ 1 ]
Kostic has been the Section First Editor-in-Chief of Thermodynamics (2015-2024) [6] of the journal Entropy , published by MDPI having previously been a Guest Editor of two Special issues on Entropy and the Second Law of Thermodynamics., [ 4 ] [ 5 ] [7]
Kostic has also worked in industry and has authored a number of patents and professional publications, including invited articles in professional encyclopedias. [ 6 ] [ 7 ] [ 8 ] [ 9 ] [ 10 ] [ 11 ] [ 12 ] [ 13 ] [ 14 ] [ 15 ] [ 16 ]
Kostic was appointed as NASA faculty fellow, and Fermi and Argonne National Laboratories faculty researcher. He has a number of professional awards and recognitions, is a frequent keynote plenary speaker at international conferences and at different educational and public institutions, as well as member of several professional societies and scientific advisory boards. [ 1 ] [ 17 ] Entransy concept and controversies
Kostic is interested in the fundamental laws of nature, [ 18 ] thermodynamics and heat transfer fundamentals and applications, [ 1 ] [ 17 ] and especially the Second law of thermodynamics and entropy ., [ 19 ] [ 20 ] [ 4 ] [ 5 ] [ 6 ] [ 7 ] [ 11 ] see also arXiv e-prints . He has developed a collaboration with Tsinghua and other Chinese universities. [ 21 ] Kostic wrote about Entransy concept and controversies, [ 22 ] and is editing an Entropy special Issue, Nature of heat and entropy , as well as a Topical collection, Foundations and Ubiquity of Classical Thermodynamics .
Kostic has raised some critical issues regarding the challenges of the Second Law of thermodynamics , including a number of puzzling issues still surrounding thermodynamics and the nature of heat, epitomized by the elusive Maxwell's demon . Namely, he argued that Maxwell and his followers focused on 'effortless gating' a molecule at a time, but overlooked simultaneous interference of other chaotic molecules, while the demon exorcists tried to justify impossible processes with misplaced 'compensations' by work of measurements and gate operation, and information storage and memory erasure with entropy generation. [ 23 ] Some other unjustified claims, fundamentally misplaced and dramatized, like “heat flowing from cold to hot without external intervention,” have been critically analyzed and demystified by Kostic. [ 24 ] The Second Law and Entropy misconceptions have been demystified in another publication. [ 25 ]
Kostic wrote a comprehensive treatise, written for the special occasion of the author’s 70th birthday . It presents his lifelong endeavors and reflections with original reasoning and re-interpretations of the most critical and sometimes misleading issues in thermodynamics. [ 26 ]
More recently Kostic presented a plenary lecture "Engineering Thermodynamics: Fundamentals and Challenges" at Sadi Carnot's Legacy International Colloquium at Ecole Polytechnique . It presents Carnot’s "Réflexions" on “heat engine reversible cycles and their maximum efficiency,” among the most important treatises in natural sciences, and the critical and sometimes misleading issues related to the Second law of thermodynamics. | https://en.wikipedia.org/wiki/Milivoje_Kostic |
Milk-cap (also milk cap , milkcap , or milky ) is a common name that refers to mushroom -forming fungi of the genera Lactarius , Lactifluus , and Multifurca , all in the family Russulaceae . The common and eponymous feature of their fruitbodies is the latex ("milk") they exude when cut or bruised. [ 1 ] Mushrooms with typical milk-cap characteristics are said to have a lactarioid habit . Some of them are edible .
Historically, these species were all united in the genus Lactarius , but molecular phylogenetic analysis has shown that they belong in fact to three distinct clades : [ 2 ] [ 3 ] [ 4 ] | https://en.wikipedia.org/wiki/Milk-cap |
Milk fat globule membrane ( MFGM ) is a complex and unique structure composed primarily of lipids and proteins that surrounds milk fat globule secreted from the milk producing cells of humans and other mammals. It is a source of multiple bioactive compounds , including phospholipids , glycolipids , glycoproteins , and carbohydrates that have important functional roles within the brain and gut.
Preclinical studies have demonstrated effects of MFGM-derived bioactive components on brain structure and function, intestinal development, and immune defense. Similarly, pediatric clinical trials have reported beneficial effects on cognitive and immune outcomes. In populations ranging from premature infants to preschool-age children, dietary supplementation with MFGM or its components has been associated with improvements in cognition and behavior, gut and oral bacterial composition, fever incidence, and infectious outcomes including diarrhea and otitis media .
MFGM may also play a role in supporting cardiovascular health by modulating cholesterol and fat uptake. Clinical trials in adult populations have shown that MFGM could positively affect markers associated with cardiovascular disease including lowering serum cholesterol and triacylglycerol levels as well as blood pressure .
Milk lipids are secreted in a unique manner by lactocytes , which are specialized epithelial cells within the alveoli of the lactating mammary gland .
The process takes place in multiple stages. First, fat synthesized within the endoplasmic reticulum accumulates in droplets between the inner and outer phospholipid monolayers of the endoplasmic reticulum membrane. As these droplets increase in size, the two monolayers separate further and eventually pinch off. This leads to the surrounding of the droplet in a phospholipid monolayer that allows it to disperse within the aqueous cytoplasm . In the next stage, lipid droplets then migrate to the apical surface of the cell, where plasma membrane subsequently envelops the droplet and extrudes together with it. It fully encases the fat droplet in an additional bilayer of phospholipids . The milk fat globule thus released into the glandular lumen, measuring 3-6 μm in average diameter, is surrounded by a phospholipid trilayer containing associated proteins, carbohydrates, and lipids derived primarily from the membrane of the secreting lactocyte. This trilayer is collectively known as MFGM. [ 1 ] [ 2 ]
This secretion process occurs in all types of mammalian milk, including human and bovine . However, it is distinct from the lipid secretion mechanism used by all other non-mammary cells. That makes MFGM unique to milk and it is not present in non-dairy food products. [ 2 ]
MFGM is a structurally complex bioactive milk component, found in human milk as well as the milk of other mammalian species. The MFGM in human milk contains many bioactive components with diverse functions and has been linked to cognitive and health benefits to infants. Some compositional differences are reported to exist between species, but bovine MFGM, the best-studied non-human source, generally contains a lipid and protein composition, which is similar to that of human MFGM. [ 3 ] [ 4 ]
MFGM makes up an estimated 2-6% of the total fat globules . [ 5 ] As raw milk has an average total fat content around 4%, [ 6 ] [ 7 ] it therefore contains around 0.08-0.24% of MFGM. In other words, 417–1250 kg of raw milk is needed to supply 1 kg of MFGM. The content of MFGM in dairy products varies depending on the processing involved. During dairy processing such as churning or decreaming, the MFGM is disrupted and preferentially distributed into aqueous phases such as buttermilk, butter serum, or certain type of whey. [ 8 ] Thus they can be a good source of MFGM for addition into food products.
For example, infant formulas traditionally were lacking the MFGM because this fraction is lost during regular dairy processing. [ 9 ] However, more recent advances in technology have facilitated the separation of MFGM from the fat globule , allowing bovine MFGM to be added in concentrated form. [ 8 ] The MFGM fraction is now commercially available and can be added to infant formula or other nutritional products.
The milk fat globule is surrounded by a phospholipid trilayer containing associated proteins, carbohydrates, and lipids derived primarily from the membrane of the secreting mammary epithelial cell (lactocyte). This trilayer is collectively known as MFGM. While MFGM makes up only an estimated 2% to 6% of the total milk fat globule, [ 1 ] it is an especially rich phospholipid source, accounting for the majority of total milk phospholipids. [ 10 ] [ 11 ] In contrast, the inner core of the milk fat globule is composed predominantly of triacylglycerols.
The MFGM structure is complex and comprises a variety of phospholipids, glycolipids, proteins, and glycoproteins, along with cholesterol and other lipids. Specific lipids and proteins are localized to different layers of the membrane, with carbohydrate chains of glycoproteins and glycolipids directed toward the outer surface of the milk fat globule; the lipid-to-protein weight ratio in MFGM is approximately 1:1. [ 12 ]
However, the nutritional significance of these components is defined not only by their structure or macronutrient category, but also by the physiological role that each nutrient serves. As a quantitatively minor presence within milk, MFGM likely contributes little to energy production, but its constituents may confer structural and functional benefits. [ 8 ] Many of these nutrients are known to play important functional roles within the gut, brain, and elsewhere in the body; the functions of other components are still being elucidated.
The lipid component of MFGM is rich in phospholipids, glycosphingolipids, and cholesterol. Phospholipids make up approximately 30% of the total lipid weight of MFGM, the three most prominent being sphingomyelin (SM), phosphatidylcholine (PC), and phosphatidylethanolamine (PE), which together represent up to 85% of total phospholipids. [ 1 ] [ 12 ] Phospholipids and sphingolipids play central roles in cerebral neurogenesis and migration during fetal development , as well as promoting neuronal growth, differentiation, and synaptogenesis during the first year of life. [ 13 ] [ 14 ] Other important polar lipids present in the membrane include the glycerophospholipids phosphatidylserine (PS) and phosphatidylinositol (PI), as well as gangliosides (GG), which are sphingolipids containing sialic acid and an oligosaccharide side chain. Each of these lipid classes is known to play functional roles within the body, including the support of gut, immune, and central nervous system development. [ 9 ] [ 15 ]
Besides the polar lipids, the outer layer of MFGM contains a number of glycosylated and non-glycosylated proteins. Proteomic analysis has revealed at least 191 different known proteins in human MFGM, and comparable numbers in bovine milk protein concentrates. [ 1 ] While quantitatively these only represent 1% to 2% of total milk protein content, [ 16 ] MFGM proteins are of significant interest because many are known to have bioactive and potentially beneficial properties; almost half of identified proteins have membrane/protein trafficking or cell signaling functions. [ 17 ] The glycosylated proteins, including mucins (MUC-1, MUC-4, MUC-15), butyrophilin, lactadherin, and CD36, have been suggested to enhance triacylglyceride digestion efficiency. [ 1 ] Furthermore, lactadherin and MUC-1, in addition to the non-glycosylated protein xanthine oxidase, have been shown or suggested in preclinical studies to possess antimicrobial properties. [ 18 ] [ 19 ] [ 20 ] [ 21 ] [ 22 ]
Research has indicated that MFGM, or components thereof, may potentially play roles in brain development and cognitive function, immunity and gut health, and cardiovascular health.
MFGM has a set of proteins and lipids unique to breast milk: lactoferrin, Immunoglobulin G, sialic acid, cholesterol, phospholipids, sphingolipids, gangliosides and choline. All components of the MFGM are important for child development. Phospholipids and gangliosides influence the formation and folding of the cerebral cortex. These structures translate directly into neuronal development and cognitive abilities. The use of MFGM in Geo-Poland infant formula is essential to mimic breast milk. A not insignificant proportion of studies investigating the health effects of formula supplementation with MFGM on infant health were (co-)funded by the cow's milk and formula industry. [ citation needed ]
MFGM lipid components such as sphingomyelin and gangliosides are highly concentrated in the brain and support synaptogenesis and myelination. [ 23 ] [ 24 ] In the central nervous system, sphingomyelin is a key component of the myelin sheath, which insulates axons and supports efficient transmission of nerve impulses. [ 25 ] [ 26 ] During myelination, nerve axons are wrapped with multiple layers of cell membrane by oligodendrocyte glial cells, a process that accounts for a large portion of brain growth during late gestation and the first two years of life, [ 27 ] but which can also continue up to 5–10 years of age. [ 28 ] Meanwhile, gangliosides are concentrated within the brain’s gray matter and constitute approximately 6% to 10% of the total human brain lipid mass. [ 29 ] [ 30 ] [ 31 ] [ 32 ] [ 33 ] [ 34 ] Additionally, gangliosides are enriched at the synaptic membrane of neurons, and are functionally involved in neurotransmission and synapse formation. [ 35 ] [ 24 ] Brain ganglioside accretion occurs at an accelerated rate in the early years of life, coinciding with the most active period of myelination, axonal outgrowth, and synaptogenesis. [ 36 ] [ 37 ] Alongside the growth of brain size, total brain ganglioside concentration also increases 3-fold from early fetal development to 5 years of age. [ 36 ]
A number of preclinical studies have been conducted using MFGM and combinations of MFGM-derived components. Liu et al. (2014) studied brain development and spatial learning and memory in neonatal piglets. [ 38 ] Piglets that were fed with a formula containing milk phospholipids and gangliosides to mimic levels in human milk made choices more rapidly and with fewer errors in a spatial T-maze cognitive test compared to controls, implying improved spatial learning. Similarly, Vickers et al. (2009) demonstrated that administration of complex milk lipids to rats from postnatal day 10 through adulthood (day 80) led to significant improvements in learning and memory tasks compared to control animals. [ 39 ] Conversely, a study of complex milk lipid supplementation to pregnant mice did not have an effect on cognitive tasks in their offspring. [ 40 ]
Several studies of diets supplemented with MFGM and its components, including gangliosides and sphingomyelin, have aimed to address measures of cognitive development in pediatric populations. In some of the studies, MFGM supplementation to infant formula was shown to narrow the gap in cognitive development between breastfed and formula-fed infants.
Tanaka et al. (2013) studied the neurobehavioral effects of feeding formula supplemented with sphingomyelin-enriched phospholipid in 24 very low birth weight preterm infants (birth weight <1500 g). [ 23 ] In this double-blind RCT, the preterm infants were fed either control formula containing phospholipids derived from egg yolk lecithin with sphingomyelin at 13% of total phospholipid or a supplemented formula with milk-derived phospholipids containing 20% sphingomyelin. Infants fed the supplemented formula had significantly higher percentages of sphingomyelin in total plasma phospholipids after 4, 6, and 8 weeks of feeding compared to those fed the control formula. The infants fed the supplemented formula also showed improvements across multiple developmental measures at 18 months, with significantly better scores on the Behavior Rating Scale of the Bayley Scales of Infant Development II (BSID-II), the Fagan test (novelty preference rate), the latency of visual evoked potentials (VEP), and sustained attention test than in the control group.
Gurnida et al. (2012) assessed the cognitive effects of formula supplemented with a ganglioside-enriched, MFGM-derived complex milk lipid in term infants. [ 41 ] In this double-blind RCT, healthy infants (2–8 weeks of age) were fed until 6 months of age, either control infant formula (n=30), or a supplemented infant formula (n=29) with added complex milk lipids to increase ganglioside concentration to approximately 11-12 μg/mL to be within the human milk range. A breastfed reference group (n=32) was also included. Results showed that serum ganglioside levels in the supplemented group were significantly higher compared to the control group at 6 months, but did not significantly differ from levels in the breastfed group. The cognitive outcomes measured using the Griffiths Mental Development Scale showed that the supplemented group had significantly increased scores for Hand and Eye Coordination, Performance, and Total Score (General Quotient) at 6 months compared to the control group, and there were no significant differences in cognitive performance compared to the breastfed reference group.
Timby et al. (2014) also assessed the potential impact of MFGM supplementation on cognitive development in term infants. [ 42 ] In this double-blind RCT, term infants (<2 months old) were fed until 6 months of age either a control formula (n=64) or an MFGM-supplemented formula (n=71). A breastfed reference group (n=70) was also included. Cognitive assessment done using the BSID-III at 12 months of age showed that the MFGM-fed infants exhibited significantly higher mean cognitive scores than the control group (105.8 vs 101.8; P<0.008), and not significantly different from the breastfed reference group. In contrast, there were no significant differences in motor domain scores between the three groups, and both experimental and control formula groups scored lower than the reference group in the verbal domain.
Veereman-Wauters et al. (2012) assessed the potential behavioral benefits of MFGM supplementation in young children. [ 43 ] In this double-blind RCT, healthy preschool children (2.5 to 6 years of age) consumed for 4 months, either a control formula (n=97) providing 60 mg/day of endogenous phospholipid, or an MFGM-supplemented formula (n=85) providing a total of 500 mg/day of dairy-derived phospholipids. At the end of the trial, parents and teachers completed the Achenbach System of Empirically Based Assessment (ASEBA), a validated questionnaire considered to be a gold standard for assessing emotion and behavior in preschool children. [ 44 ] Significant differences in internal, external, and total behavioral problem scores were observed in favor of the supplemented formula group, as reported by parents (but not by teachers).
MFGM bioactive protein components, including the glycoproteins lactadherin, MUC-1, and butyrophilin, have been shown in preclinical studies to affect immune response. [ 45 ] These components influence the immune system by several mechanisms, including interference with microbe adhesion to intestinal epithelia, bacteriocidal action, support of beneficial microbiota, and modulation of other parts of the immune system. [ 9 ]
MFGM phospholipid components such as phosphatidylcholine are a key constituent of the intestinal mucus barrier, and therefore may contribute to intestinal defense against invasive pathogens. [ 46 ] Sphingolipids, including sphingomyelin, are present in the apical membrane of the gut epithelia, and are also important for maintaining membrane structure, modulating growth factor receptors, and serving competitive binding inhibitors for microorganisms, microbial toxins, and viruses. [ 47 ] Gangliosides are also present in intestinal mucosa and may possibly contribute to improved gut microflora and antibacterial defense. [ 48 ]
MFGM may be capable of modulating immune function in the gut through distinct but potentially complementary mechanisms. Glycosylated proteins (MUC-1, MUC-15, butyrophilin, and lactadherin) and glycosylated sphingolipids from MFGM may promote the development of healthy gut microbiota by favoring beneficial Bifidobacterium species. [ 49 ] Another key to the immunomodulatory function of MFGM may be that its structure is similar to that of the intestinal cell membrane, allowing human milk glycans (including those on glycoproteins and glycolipids) to competitively inhibit the binding of pathogens (bacteria, viruses, even toxins) to host cells. [ 50 ]
A number of preclinical studies have demonstrated inhibitory effects of MFGM against several pathogens. Both whole bovine MFGM and its extracted lipid components were found to exhibit dose-dependent inhibition of rotavirus infectivity in vitro. [ 51 ] Antibacterial effects of MFGM have included decreased gastric colonization and inflammation after H. pylori infection in mice; [ 52 ] inhibition of shiga toxin gene expression by E. coli O157:H7 ; [ 53 ] and decreased colonization and translocation of L. monocytogenes . [ 54 ] Mice that were fed prophylactically with bovine whey glycoprotein fraction, including MFGM proteins, did not develop diarrhea after exposure to rotavirus. [ 55 ]
The previously described study by Timby et al. (2015) also assessed the effects of MFGM supplementation in term infants on the risk of infectious diseases and other disease symptoms. [ 3 ] In particular, the cumulative incidence of acute otitis media was analyzed between the two randomized feeding groups (control formula or MFGM- supplemented formula to 6 months of age), and compared to a breastfed reference group. The MFGM-supplemented group experienced a significant reduction in episodes of acute otitis media up to 6 months of age compared with infants fed control formula (1% vs 9%; P=0.034); with no significant difference in otitis media incidence compared to the breastfed group (0%). In addition, a significantly lower incidence and longitudinal prevalence of antipyretic drug use was seen in the MFGM-supplemented group (25%) compared with the control formula group (43%). Timby et al. (2017) further showed that the MFGM supplementation influenced the infants’ oral microbiota; the authors noted that, Moraxella catarrhalis, a common bacterial cause of acute otitis media, was less prevalent in infants fed the MFGM-supplemented formula than in those fed control formula. [ 56 ]
Zavaleta et al. (2011) evaluated the effects of an MFGM-enriched complementary food on health outcomes in term infants 6 to 11 months of age in Peru. [ 57 ] In this double-blind RCT, 499 primarily breast-fed infants were fed for 6 months with a daily milk-based complementary food that included either whey protein concentrate enriched in MFGM, or an equal amount of additional protein from skim milk (control). Results showed that the group with the MFGM-supplemented diet had a significantly lower prevalence of diarrhea during the study compared to the control group (3.84% vs 4.37%; P<0.05), as well as a significant reduction (46%) in episodes of bloody diarrhea compared to the control group (P=0.025).
Later through analyzing the metabolome and immune markers of those infants, Lee et al. (2018) reported that supplementation with MFGM may improve micronutrient status, amino acid, and energy metabolism along with a reduced proinflammatory response (e.g. interleukin-2). [ 58 ]
The previously described study by Veereman-Wauters et al. (2012) in preschool-age children (2.5 to 6 years old) also reported the effect of MFGM-supplemented formula consumption on health outcomes. Children receiving the MFGM-supplemented formula reported a significant reduction in the number of days with fever, and particularly the number of short febrile episodes (<3 days), compared to the control group. [ 43 ]
Dietary guidelines generally recommend limiting full-fat dairy products. This recommendation has been based on traditional hypothesis that dietary saturated fatty acids, such as those derived from milk fat, have serum LDL cholesterol raising effects. Subsequently, serum LDL cholesterol has been associated with cardiovascular disease (CVD) risk based on observational evidence as well as meta-analysis of RCT data. [ 59 ] [ 60 ] [ 61 ] A review of observational studies has suggested that the association between milk fat intake and serum cholesterol measures could vary depending on the type of dairy products. [ 60 ] Differential effects of various dairy foods on plasma lipids might be partly dependent on the presence of MFGM. [ 62 ] MFGM lipid components may play a role in supporting cardiovascular health by modulating cholesterol and fat uptake.
MFGM lipid components such as sphingolipids are involved in the intestinal uptake of cholesterol. [ 8 ] Studies in adult rodents have shown that milk sphingomyelin could lower the intestinal absorption of cholesterol in a dose-dependent manner. [ 63 ] [ 64 ] Intestinal cholesterol absorption in adult rodents consuming a high fat diet was limited by sphingomyelin supplementation. [ 65 ] Milk sphingomyelin and other phospholipids with high affinity for cholesterol could limit the micellar solubility of intestinal cholesterol, thereby limiting the cholesterol uptake by the enterocyte. [ 63 ] Dietary sphingolipids have been shown to dose-dependently lower plasma cholesterol and triacylglycerol in adult rodents fed with Western-type diet and protect the liver from fat- and cholesterol-induced steatosis. [ 66 ] Dietary sphingolipids also lowers hepatic cholesterol and triglyceride levels in adult rodents partly by modulating hepatic gene expression. [ 65 ]
Several clinical studies have shown that MFGM could positively affect circulating lipids. A single-blind RCT in overweight adults has shown that the effects of milk fat on plasma lipids were modulated by the MFGM content; compared to butter oil (control diet), consumption of whipping cream (MFGM diet) for 8 weeks did not impair the lipoprotein profile. [ 62 ] Another double-blind RCT in overweight and obese adults has also shown that MFGM attenuated the negative effects of a high-saturated fats meal by reducing postprandial cholesterol, inflammatory markers and insulin response. [ 67 ] A double-blind RCT in normal healthy adults has indicated that one month consumption of buttermilk rich in MFGM led to reduction in serum cholesterol and triacylglycerol levels as well as blood pressure. [ 68 ] [ 69 ]
MFGM supplementation in infancy is hypothesized to have programming effects that may influence circulating lipid levels later in life. Breastfed infants are known to have a higher total serum cholesterol and LDL cholesterol than formula-fed infants in infancy, but lower levels in adulthood. A clinical study in infants has suggested that MFGM supplementation could narrow the gap between breastfed and formula-fed infants with regard to serum lipid status. [ 70 ] Specifically, as compared with a control formula, infants receiving MFGM-supplemented formula had higher total serum cholesterol until 6 months of age, similar to breastfed infants. The LDL:HDL ratio did not differ between the formula-fed groups and was significantly higher in the breastfed reference group as compared with both formula-fed groups. | https://en.wikipedia.org/wiki/Milk_fat_globule_membrane |
Milk immunity is the protection provided to immune system of an infant via the biologically active components in milk , typically provided by the infant's mother .
All mammalian milk contains water, sugar, fat, vitamins , and protein with the variation within and between species and individuals differing mainly in the amount of these components. [ 1 ] Other than the variation in quantity of these components, not a lot is known about bio-active or immune-modulating factors in many mammalian species. However, in comparison to other mammalian milk, human milk has the most oligosaccharide diversity. [ 2 ]
Ruminant mothers do not transfer immunity to their infants during pregnancy , which makes milk the first introduction to maternal immunity calves receive. [ 3 ] Bovine milk contains both immunoglobulins A and G, but in contrast to human milk where IgA is the most abundant, IgG is more abundant. [ 4 ] Secretory Component , IgM , both anti-inflammatory and inflammatory cytokines , and other proteins with antimicrobial functions are also present in bovine milk. [ 3 ]
Human milk immunity is the protection provided to the immune system of an infant via the biologically active components in human milk . Human milk was previously thought to only provide passive immunity primarily through Secretory IgA , but advances in technology have led to the identification of various immune-modulating components. [ 5 ] [ 6 ] [ 7 ] Human milk constituents provide nutrition and protect the immunologically naive infant as well as regulate the infant's own immune development and growth. [ 8 ]
Crop milk is a secretion from the crop of a bird that is regurgitated to feed their offspring. [ 12 ] Birds that produce this secretion include pigeons, flamingos, emperor penguins, and doves. [ 13 ] Pigeon milk contains some immune-modulating factors such as microbes and IgA, as well as other components with similar biological activities to mammalian milk including pigeon growth factor, and transferrin . [ 14 ] | https://en.wikipedia.org/wiki/Milk_immunity |
The myth of the milk of Hera ( Ancient Greek : Ἥρας γάλα , romanized : Hḗras gala ) is an ancient Greek myth and explanation of the origin of the Milky Way within the context of creation myths . The standard telling goes that the mythical hero Heracles , as an infant, breastfed from an unsuspecting Hera , the goddess of marriage and Zeus 's wife, who threw him away, causing a little bit of her milk to splash and create the galaxy with all its stars.
The ancient Greek word for 'Milky Way' and 'galaxy' both is γαλαξίας , literally meaning "milky", [ 1 ] derived from γάλα , which means milk, [ 2 ] and is itself from the Proto-Indo-European root *glakt- , *galakt- (compare to the Latin lac ). [ 3 ]
It was said that once Heracles had been born, either Zeus or his son Hermes took the infant and brought him to Hera , who was sleeping, and placed him to her breast so that he could suckle from her. Once Hera awoke and understood the situation, she pushed the baby away, and her unexpressed milk was sprayed. This story was attributed to (pseudo-) Eratosthenes . [ 4 ] [ 5 ]
In another telling, after Alcmene managed to bring forth both infants, she grew fearful of Hera's wrath and imminent retribution, so she exposed the infant in some field. The goddess Athena , Heracles' half-sister, found him and brought him to Hera, without revealing his identity. Hera, admiring the baby, offered to breastfeed him. But Heracles bit too hard on her breast, hurting her and forcing Hera to cast him aside in pain, as Athena returned him to his mortal parents. [ 6 ]
A version that diverges significantly from the more known ones states that the milk was not Hera's at all. According to the Roman mythographer Hyginus , when Rhea presented a swaddled rock to her husband Cronus pretending to be the infant Zeus, Cronus asked her to nurse the child one last time before he ate it. Rhea complied and pressed her breast against the rock, releasing a bit of milk. [ 7 ] Hyginus, while recounting the more traditional story by Eratosthenes, supplants the infant Heracles for the infant Hermes, the son of the nymph Maia , instead. [ 7 ]
Both Eratosthenes and Hyginus link Heracles breastfeeding Hera to his legitimation as an infant, since the only way for a son of Zeus to be able to receive honours in heaven was through being nursed by Hera, with Hyginus providing an additional example with Hermes. Neither Diodorus nor Pausanias make such connection between the breastfeeding and Heracles suckling from his father's wife breast; Diodorus mentions another ritual, which included a mock labour with Hera acting as Alcmene, as the way Heracles was legitimized after his apotheosis . [ 8 ]
Whatever the details and the circumstances of the myth, it was said that the divine milk that spilt and sprayed across the heavens became the Milky Way galaxy, known to the ancient Greeks as Galaxias Kyklos ( Ancient Greek : Γαλαξίας Κύκλος , lit. 'the milky circle'). [ 9 ] [ 10 ] This rather dramatic myth has been depicted throughout history by many artists, including Tintoretto and Rubens . [ 9 ]
In a lesser-known variant, some of the milk's portion that was released fell down on the earth, and transformed into a lily , a flower as white as Hera's milk. [ 8 ] [ 11 ] [ 12 ] | https://en.wikipedia.org/wiki/Milk_of_Hera |
There are many myths and legends about the origin of the Milky Way , the crowd of stars that makes a distinctive bright streak across the night sky.
Ancient Armenian mythology called the Milky Way the "Straw Thief's Way". According to legend, the god Vahagn stole some straw from the Assyrian king Barsham and brought it to Armenia during a cold winter. When he fled across the heavens, he spilled some of the straw along the way. [ 1 ] Similarly, in Assyrian Neo-Aramaic , the Milky Way is called the ܫܒܝܠ ܬܒܢܐ shvil tivna , meaning the way of straw, or ܐܘܪܚܐ ܕܓܢܒ̈ܐ urẖa d’gannave , meaning the path of thieves .
Aboriginal Australian people had a well-developed astronomy , with much of their mythology and cultural practices relating to the stars, planets and their motion through the sky, as well as using the stars to navigate the Australian continent . [ 2 ] [ 3 ]
The Kaurna people of the Adelaide Plains in South Australia see the band of the Milky Way as a river in the sky world. They called it Wodliparri (wodli = hut, house, parri = river) and believe that positioned along the river are a number of campfires. [ 4 ] In addition, the dark patches mark the dwelling place of a dangerous creature known as a yura ; the Kaurna call these patches Yurakauwe, which literally means "monster water". [ 5 ]
A group of Yolngu people from the Ramingining area in central Arnhem Land in the Northern Territory have a Dreaming story known as "Milky Way Dreaming". [ 6 ] In this story, which relates to the land, two spirit beings in the form of female quolls attacked their husband. The husband becomes a glider possum , gathers his warriors, and returns to kill them with spears. The spirits of the quolls transform into a type of freshwater fish , but they are caught in the creek nearby by the husband's tribesmen and eaten. Their bones are collected by their brother, Wäk, aka the crow man, and put into a hollow log coffin . The Badurru Ceremony is performed and the coffin carried into the sky by the crow and his kin. The bones are then dispersed and form the Milky Way. [ 7 ]
Aboriginal groups from the Cape York region of Queensland see the band of light as termites that had been blown into the sky by the ancestral hero Burbuk Boon. [ citation needed ]
Further south, [ where? ] the band of stars that comprise the Milky Way are seen as thousands of flying foxes carrying away a dancer known as Purupriggie. [ citation needed ]
The Aranda or Arrernte people , who come from Central Australia , see the band of the Milky Way as a river or creek in the sky world. This stellar river separates the two great camps of the Aranda and Luritja people. The stars to the east of this river represent the camps of the Aranda and the stars to the west represent Luritja encampments and some stars closer to the band represent a mixture of both. [ citation needed ]
In the Kimberley region of Western Australia , the Aboriginal people called the Milky Way "Iowara" and see in it the presence of a giant emu elongated. [ citation needed ]
A Cherokee folktale tells of a dog who stole some cornmeal and was chased away. He ran away to the north, spilling the cornmeal along the way. The Milky Way is thus called ᎩᎵ ᎤᎵᏒᏍᏓᏅᏱ ( Gili Ulisvsdanvyi ) "Where the dog ran". [ 8 ]
In Eastern Asian and Chinese mythology , the hazy band of stars of the Milky Way was referred to as the "River of Heaven" or the "Silvery River" ( simplified Chinese : 银河 ; traditional Chinese : 銀河 ; pinyin : yínhé ; Korean : 은하 ; RR : eunha ; Vietnamese : ngân hà ; Japanese : 銀河 , romanized : ginga ).
The Silvery River of Heaven is part of a romantic Chinese folk tale , The Cowherd and the Weaver Girl , of the romance between Zhinü , the weaver girl, symbolizing the star Vega , and Niulang , the cowherd, symbolizing the star Altair . [ 9 ] Their love was not allowed, and they were banished to opposite sides of the heavenly river. [ 9 ] [ 10 ] Once a year, on the seventh day of the seventh lunar month , a flock of crows and magpies would form a bridge over the heavenly river to reunite the lovers for a single day. That day is celebrated as Qixi , literally meaning 'Seventh Night' ( Chinese : 七夕 ; pinyin : Qīxī ; Korean : 칠석 ; RR : chilseok , Vietnamese : Thất Tịch , and Japanese : 七夕 , romanized : Tanabata ).
In Egyptian mythology , the Milky Way was considered a pool of cow's milk. The Milky Way was deified as a fertility cow-goddess by the name of Bat (later on syncretized with the sky goddess Hathor ).
The astronomer Or Graur has suggested that the Egyptians may have seen the Milky Way as a celestial depiction of the sky goddess Nut . [ 11 ]
Among the Finns, Estonians and related peoples, the Milky Way was and is called "The Pathway of the Birds" ( Finnish : Linnunrata , Estonian : Linnutee ). The Finns observed that migratory birds used the galaxy as a guideline to travel south, where they believed Lintukoto (bird home) was.
In Estonian folklore it is believed that the birds are led by a white bird with the head of a maiden who chases birds of prey away. [ 12 ] The maiden, the goddess Lindu, was the Queen of the Birds and the daughter of Ukko, the King of the Sky. After refusing the suits of the Sun and Moon for being too predictable in their routes and the Pole Star for being fixed, she fell in love with the Light of North for its beauty. They became engaged, but the inconstant Light of North left her soon afterward. The tears of the broken-hearted Lindu fell on her wedding veil, which became the Milky Way when her father brought her to heaven so she could reign by his side and guide the migrating birds, who followed the trail of stars in her veil. [ 13 ] Only later did scientists indeed confirm this observation; the migratory birds use the Milky Way as a guide to travel to warmer, southern lands during the winter. [ 14 ] [ 15 ]
The name in the Indo-European Baltic languages has the same meaning ( Lithuanian : Paukščių Takas , Latvian : Putnu Ceļš ).
The Greek name for the Milky Way (Γαλαξίας Galaxias ) is derived from the Greek word for milk (γάλα, gala ). One legend explains how the Milky Way was created by Heracles (Roman Hercules ) when he was a baby. [ 16 ] His father, Zeus , was fond of his son, who was born of the mortal woman Alcmene . He decided to let the infant Heracles suckle on his divine wife Hera 's milk when she was asleep, an act which would endow the baby with godlike qualities. When Hera woke and realized that she was breastfeeding an unknown infant, she pushed him away and the spurting milk became the Milky Way.
Another version of the myth is that Heracles was abandoned in the woods by his mortal parents, Amphitryon and Alcmene. Heracles, son of Zeus and Alcmene, was naturally favored by his father, who sent Athena , Greek goddess of wisdom, to retrieve him. Athena, not being so motherly, decided to take him to Hera to suckle. Hera agreed to suckle Heracles. As Heracles drinks the milk, he bites down, and Hera pushes him away in pain. The milk that squirts out forms the Milky Way.
A story told by the Roman Hyginus in the Poeticon astronomicon (ultimately based on Greek myth) says that the milk came from the goddess Ops (Greek Rhea ), the wife of Saturn (Greek Cronus ). Saturn swallowed his children to ensure his position as head of the Pantheon and sky god, and so Ops conceived a plan to save her newborn son Jupiter (Greek Zeus): She wrapped a stone in infant's clothes and gave it to Saturn to swallow. Saturn asked her to nurse the child once more before he swallowed it, and the milk that spurted when she pressed her nipple against the rock eventually became the Milky Way. [ 17 ]
In Hungarian mythology, Csaba, the mythical son of Attila the Hun and ancestor of the Hungarians, is supposed to ride down the Milky Way when the Székelys (ethnic Hungarians living in Transylvania ) are threatened. Thus the Milky Way is called "The Road of the Warriors" (lit. "Road of Armies") Hungarian : Hadak Útja . The stars are sparks from their horseshoes.
In the Hindu collection of stories called Bhagavata Purana , all the visible stars and planets moving through space are likened to a dolphin that swims through the water, and the heavens are called śiśumãra cakra , the dolphin disc. The Milky Way forms the abdomen of the dolphin and is called Akasaganga which means "The Ganges River of the Sky". [ 18 ]
According to Hindu mythology, Vishnu lies meditating on Shesha with his consort Lakshmi , in the Kshira Sagara (Sea of Milk), which is a representation of Milky Way.
This "Sea of Milk" is also the (cosmic) ocean referenced in the Samudra Manthana episode of Vishnu Purana , a major text in Indian mythology . [ 19 ] The Samudra Manthana explains the origin of the elixir of eternal life, amrita .
In Irish mythology , the main name of the Milky Way was Bealach na Bó Finne — Way of the White Cow. It was regarded as a heavenly reflection of the sacred River Boyne , which is described as "the Great Silver Yoke" and the "White Marrow of Fedlimid ," names which could equally apply to the Milky Way. ( Mór-Chuing Argait , Smir Find Fedlimthi ). [ 20 ]
Other names include:
To the Māori the Milky Way is the waka (canoe) of Tama-rereti . The front and back of the canoe are Orion and Scorpius , while the Southern Cross and the Pointers are the anchor and rope. According to legend, when Tama-rereti took his canoe out onto a lake, he found himself far from home as night was falling. There were no stars at this time and in the darkness the Taniwha would attack and eat people. So Tama-rereti sailed his canoe along the river that emptied into the heavens (to cause rain) and scattered shiny pebbles from the lakeshore into the sky. The sky god, Ranginui , was pleased by this action and placed the canoe into the sky as well as a reminder of how the stars were made. [ 27 ]
In the Babylonian epic poem Enûma Eliš , the Milky Way is created from the severed tail of the primeval salt water dragoness Tiamat , set in the sky by Marduk , the Babylonian national god , after slaying her. [ 28 ] [ 29 ] This story was once thought to have been based on an older Sumerian version in which Tiamat is instead slain by Enlil of Nippur , [ 30 ] [ 31 ] but is now thought to be purely an invention of Babylonian propagandists with the intention to show Marduk as superior to the Sumerian deities. [ 31 ] Another myth about Labbu is similarly interpreted.
The San people in southern Africa say that long ago there were no stars and the night was pitch black. A girl of the ancient race, !Xwe-/na-ssho-!ke, who was lonely and wanted to visit other people, threw the embers from a fire into the sky and created the Milky Way. [ 32 ] [ 33 ] [ 34 ] [ 35 ]
Welsh mythology and cosmology derives from the ancient oral traditions of the Celtic Britons , which were maintained by druids and bards until the time of their recording in medieval Welsh literature . Many features of the night sky are named for the "children of Dôn " the ancient mother goddess and sky goddess , with the Milky Way being associated with Gwydion ab Dôn (the son of Dôn), and named Caer Gwydion ("The fortress/city of Gwydion") or Llwybr Caer Gwydion ("the path to the Castle of Gwydion"). [ 36 ] [ 37 ]
Llys Dôn (literally "The Court of Dôn ") is the traditional Welsh name for the constellation Cassiopeia . At least two of Dôn's children also have astronomical associations: Caer Gwydion ("The fortress of Gwydion ") is the traditional Welsh name for the Milky Way, [ 38 ] [ 39 ] and Caer Arianrhod ("The Fortress of Arianrhod ") being the constellation of Corona Borealis . [ 40 ] [ 41 ] | https://en.wikipedia.org/wiki/Milky_Way_(mythology) |
Milky seas , sometimes confused with mareel , are a luminous phenomenon in the ocean in which large areas of seawater (up to 100,000 km 2 or 39,000 sq mi [ 1 ] ) appear to glow diffusely and continuously (in varying shades of blue ). Such occurrences glow brightly enough at night to be visible from satellites orbiting Earth . Unlike flashing waves or red-tide luminescence caused by "algae" such as dinoflagellates , milky seas originate from luminous bacteria . [ 2 ] [ 3 ]
Mariners and other seafarers have reported that the ocean often emits a visible glow which extends for miles at night. In 2005, scientists announced that for the first time, they had obtained photographic evidence of this glow. [ 4 ] [ 5 ] In a follow-up study, they observed a glow that persisted for over 40 days. [ 1 ]
Milky seas are named for the diffuse appearance of the light, since the individual bacteria are too small to make discernible flashes. In the novel Twenty Thousand Leagues Under the Seas , Jules Verne describes the ship as "sailing through a sea of milk."
In the Somali language it is called kaluunka iftiima . The term translates to glowing sea creatures or glowing fish as the word kaluun refers to any bio organism that lives in the sea. It is most commonly used to refer to fish.
Dutch sailors referred to milky seas as the winter sea due to how similar the phenomena looks to a snowy plain at night. [ 6 ] Other accounts of milky seas in Dutch refer to the phenomenon as a melkzee which translates to "milky sea."
Between 1915 and 1993, 235 sightings of milky seas were documented, [ 7 ] most of which are concentrated in the northwestern Indian Ocean near to Somalia . [ 8 ] The luminescent glow is concentrated on the surface of the ocean and does not mix evenly throughout the water column . [ 9 ]
In 1985, a research vessel in the Arabian Sea took water samples during milky seas. Their conclusions were that the effect was caused by the bacterium Vibrio harveyi . [ 10 ] In 2005, Steven Miller was able to match 1995 satellite images with a first-hand account of a merchant ship. U.S. Defense Meteorological Satellite Program showed the milky area to be approximately 15,400 km 2 (5,900 sq mi)—roughly the size of Connecticut . The luminescent field was observed to glow over three consecutive nights. In a later study [ 1 ] using a newer Day-Night Band sensor, the team was able to observe several additional events, including one from 2019 which covered 100,000 km 2 (39,000 sq mi) and persisted for over 40 nights.
While monochromatic photos make this effect appear white, Monterey Bay Aquarium Research Institute scientist Steven Haddock (an author of a milky seas effect study) has commented, "the light produced by the bacteria is actually blue, not white. It is white in the graphic because of the monochromatic sensor we used, and it can appear white to the eye because the rods in our eye (used for night vision) don't discriminate color." [ 11 ]
Milky seas are a different phenomenon than "mareel," which is a term used for dinoflagellate-produced bioluminescent displays in Scotland. Dinoflagellates produce impressive bioluminescent bays, [ 12 ] and they are responsible for the light visible in breaking waves, or glowing footprints on the beach. However, the two types of large-scale displays can be distinguished because the bacteria that produce milky seas glow continuously when they are at high concentrations and have sufficient oxygen [ 3 ] whereas dinoflagellates flash when physically stimulated.
English accounts of milky seas begin appearing not long after the formation of the East India Company . The journal of Captain William Keeling records an encounter with a milky sea near Cape Guardafui . [ 13 ]
One of the earliest scientific works on milky seas was read by Captain Newland before the Royal Society in 1772. Captain Newland speculated that milky seas may be caused by an unknown animalcule, an archaic word for microscopic organism. [ 14 ]
Scientific research into milky seas continued through the 19th and 20th centuries with researchers identifying that milky seas tend to occur in the Indian Ocean during the Monsoon of South Asia near Somalia , the island of Java in Indonesia, and in the Banda Sea . [ 7 ] Descriptions of milky seas from the 1800s detail the phenomena being visible from the coasts of islands in the Banda Sea. [ 15 ]
In the late 1800s Bernhard Fischer surmised based on his experiments that milky seas were likely caused by bioluminescent bacteria living in the ocean. A chance encounter between a research vessel and a milky sea in 1985 identified bioluminescent bacteria within the waters of a milky sea. [ 2 ]
In the 21st century researchers showed that low-light imagers aboard satellites can view milky seas from space. Observed milky seas reaching sizes on the order of 100,000 km 2 (39,000 sq mi) and potentially sustaining themselves for months at a time. [ 1 ] [ 5 ] Recent work has noted a potential connection between milky seas and the Indian Ocean Dipole . [ 1 ] | https://en.wikipedia.org/wiki/Milky_seas_effect |
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