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The main advantages for SRCD over lab-based cCD machines arise from the use of the synchrotron light emission as the source. A number of biologically interesting absorption bands are found in the region between ~170 nm and ~350 nm. For proteins these come from their secondary and tertiary structures, while structural bands for nucleic acids, (DNA and RNA), and saccharides are also located in this region. However, for cCD machines the photon flux from the source reduces by around two orders of magnitude in the wavelength range from 250 nm down to 180 nm, exactly in the region of most significance for these biological molecules. By contrast, typically, the photon flux for an SRCD beamline in this region is at least three orders of magnitude higher than a cCD machine, retaining that level down to ~150 nm. The increased flux means the measured signals from the sample will be increased relative to the background noise, so there is a significant improvement in the signal-to-noise ratio of the sample. This will improve the accuracy of the data recorded meaning interpretation can be undertaken with more confidence in the results. A further advantage of the increased flux is that the concentration of the sample can be reduced while still retaining a significant increase in signal strength, so samples that are difficult to produce in quantity have more chance of producing usable CD data from SRCD rather than a cCD machine. Increasing the lower wavelength range provides more spectral data for analysis which means there is more information content available in that data, meaning that more parameters, here secondary structure features in the protein structure, can be accurately determined. | 0 | Theoretical and Fundamental Chemistry |
In wire and fiber, all crystals tend to have nearly identical orientation in the axial direction, but nearly random radial orientation. The most familiar exceptions to this rule are fiberglass, which has no crystal structure, and carbon fiber, in which the crystalline anisotropy is so great that a good-quality filament will be a distorted single crystal with approximately cylindrical symmetry (often compared to a jelly roll). Single-crystal fibers are also not uncommon.
The making of metal sheet often involves compression in one direction and, in efficient rolling operations, tension in another, which can orient crystallites in both axes by a process known as grain flow. However, cold work destroys much of the crystalline order, and the new crystallites that arise with annealing usually have a different texture. Control of texture is extremely important in the making of silicon steel sheet for transformer cores (to reduce magnetic hysteresis) and of aluminium cans (since deep drawing requires extreme and relatively uniform plasticity).
Texture in ceramics usually arises because the crystallites in a slurry have shapes that depend on crystalline orientation, often needle- or plate-shaped. These particles align themselves as water leaves the slurry, or as clay is formed.
Casting or other fluid-to-solid transitions (i.e., thin-film deposition) produce textured solids when there is enough time and activation energy for atoms to find places in existing crystals, rather than condensing as an amorphous solid or starting new crystals of random orientation. Some facets of a crystal (often the close-packed planes) grow more rapidly than others, and the crystallites for which one of these planes faces in the direction of growth will usually out-compete crystals in other orientations. In the extreme, only one crystal will survive after a certain length: this is exploited in the Czochralski process (unless a seed crystal is used) and in the casting of turbine blades and other creep-sensitive parts. | 1 | Applied and Interdisciplinary Chemistry |
In 1994, the IUPAC Commission on Nomenclature of Inorganic Chemistry proposed the following names:
This attempted to resolve the dispute by sharing the namings of the disputed elements between Russians and Americans, replacing the name for 104 with one honoring the Dubna research center, and not naming 106 after Seaborg. | 1 | Applied and Interdisciplinary Chemistry |
The principle of Law of Similarity is used extensively for theoretical and experimental fluid machines. With respect to calibration of flowmeters, the Law of Similarity is the foundation for flow measurement standards. To satisfy the Law of Similarity, the central facility concept requires geometric and dynamic similarity between the laboratory meter and the installed conditions of this same meter over the entire custody transfer period. This approach assumes that the selected technology does not exhibit any significant sensitivity to operating or mechanical variations between calibrations. The meter factor determined at the time of calibration is valid if both dynamic and geometric similarity exists between the field installation and the laboratory installation of the artifact.
A proper manufacturers experimental pattern locates sensitive regions to explore, measure and empirically adjust. The manufacturers recommended correlation method is a rational basis for performance prediction provided the physics do not change. For instance, the physics are different between subsonic and sonic flow. To satisfy the Law of Similarity the in situ calibration concept requires geometric and dynamic similarity between the calibrated meter and the installed conditions of this same meter over the entire custody transfer period. This approach assumes that the selected technology does not exhibit any significant sensitivity to operating or mechanical variations between calibrations. The meter factor determined at the time of calibration is valid if both dynamic and geometric similarity exists in the "field meter installation" over the entire custody transfer period. | 1 | Applied and Interdisciplinary Chemistry |
Unlike other aerial photographic and satellite image interpretation work, these multispectral images do not make it easy to identify directly the feature type by visual inspection. Hence the remote sensing data has to be classified first, followed by processing by various data enhancement techniques so as to help the user to understand the features that are present in the image.
Such classification is a complex task which involves rigorous validation of the training samples depending on the classification algorithm used. The techniques can be grouped mainly into two types.
* Supervised classification techniques
* Unsupervised classification techniques
Supervised classification makes use of training samples. Training samples are areas on the ground for which there is ground truth, that is, what is there is known. The spectral signatures of the training areas are used to search for similar signatures in the remaining pixels of the image, and we will classify accordingly. This use of training samples for classification is called supervised classification. Expert knowledge is very important in this method since the selection of the training samples and a biased selection can badly affect the accuracy of classification. Popular techniques include the maximum likelihood principle and convolutional neural network. The Maximum likelihood principle calculates the probability of a pixel belonging to a class (i.e. feature) and allots the pixel to its most probable class. Newer convolutional neural network based methods account for both spatial proximity and entire spectra to determine the most likely class.
In case of unsupervised classification no prior knowledge is required for classifying the features of the image. The natural clustering or grouping of the pixel values, i.e. the gray levels of the pixels, are observed. Then a threshold is defined for adopting the number of classes in the image. The finer the threshold value, the more classes there will be. However, beyond a certain limit the same class will be represented in different classes in the sense that variation in the class is represented. After forming the clusters, ground truth validation is done to identify the class the image pixel belongs to. Thus in this unsupervised classification apriori information about the classes is not required. One of the popular methods in unsupervised classification is k-means clustering. | 0 | Theoretical and Fundamental Chemistry |
The process starts when light is absorbed by two BChl molecules that lie near the periplasmic side of the membrane. This pair of chlorophyll molecules, often called the "special pair", absorbs photons at 870 nm or 960 nm, depending on the species and, thus, is called P870 (for Rhodobacter sphaeroides) or P960 (for Blastochloris viridis), with P standing for "pigment"). Once P absorbs a photon, it ejects an electron, which is transferred through another molecule of Bchl to the BPh in the L subunit. This initial charge separation yields a positive charge on P and a negative charge on the BPh. This process takes place in 10 picoseconds (10 seconds).
The charges on the P and the BPh could undergo charge recombination in this state, which would waste the energy and convert it into heat. Several factors of the reaction center structure serve to prevent this. First, the transfer of an electron from BPh to P960 is relatively slow compared to two other redox reactions in the reaction center. The faster reactions involve the transfer of an electron from BPh (BPh is oxidized to BPh) to the electron acceptor quinone (Q), and the transfer of an electron to P960 (P960 is reduced to P960) from a heme in the cytochrome subunit above the reaction center.
The high-energy electron that resides on the tightly bound quinone molecule Q is transferred to an exchangeable quinone molecule Q. This molecule is loosely associated with the protein and is fairly easy to detach. Two electrons are required to fully reduce Q to QH, taking up two protons from the cytoplasm in the process. The reduced quinone QH diffuses through the membrane to another protein complex (cytochrome bc-complex) where it is oxidized. In the process the reducing power of the QH is used to pump protons across the membrane to the periplasmic space. The electrons from the cytochrome bc-complex are then transferred through a soluble cytochrome c intermediate, called cytochrome c, in the periplasm to the cytochrome subunit. | 0 | Theoretical and Fundamental Chemistry |
mTOR signaling intersects with Alzheimer's disease (AD) pathology in several aspects, suggesting its potential role as a contributor to disease progression. In general, findings demonstrate mTOR signaling hyperactivity in AD brains. For example, postmortem studies of human AD brain reveal dysregulation in PTEN, Akt, S6K, and mTOR. mTOR signaling appears to be closely related to the presence of soluble amyloid beta (Aβ) and tau proteins, which aggregate and form two hallmarks of the disease, Aβ plaques and neurofibrillary tangles, respectively. In vitro studies have shown Aβ to be an activator of the PI3K/AKT pathway, which in turn activates mTOR. In addition, applying Aβ to N2K cells increases the expression of p70S6K, a downstream target of mTOR known to have higher expression in neurons that eventually develop neurofibrillary tangles. Chinese hamster ovary cells transfected with the 7PA2 familial AD mutation also exhibit increased mTOR activity compared to controls, and the hyperactivity is blocked using a gamma-secretase inhibitor. These in vitro studies suggest that increasing Aβ concentrations increases mTOR signaling; however, significantly large, cytotoxic Aβ concentrations are thought to decrease mTOR signaling.
Consistent with data observed in vitro, mTOR activity and activated p70S6K have been shown to be significantly increased in the cortex and hippocampus of animal models of AD compared to controls. Pharmacologic or genetic removal of the Aβ in animal models of AD eliminates the disruption in normal mTOR activity, pointing to the direct involvement of Aβ in mTOR signaling. In addition, by injecting Aβ oligomers into the hippocampi of normal mice, mTOR hyperactivity is observed. Cognitive impairments characteristic of AD appear to be mediated by the phosphorylation of PRAS-40, which detaches from and allows for the mTOR hyperactivity when it is phosphorylated; inhibiting PRAS-40 phosphorylation prevents Aβ-induced mTOR hyperactivity. Given these findings, the mTOR signaling pathway appears to be one mechanism of Aβ-induced toxicity in AD.
The hyperphosphorylation of tau proteins into neurofibrillary tangles is one hallmark of AD. p70S6K activation has been shown to promote tangle formation as well as mTOR hyperactivity through increased phosphorylation and reduced dephosphorylation. It has also been proposed that mTOR contributes to tau pathology by increasing the translation of tau and other proteins.
Synaptic plasticity is a key contributor to learning and memory, two processes that are severely impaired in AD patients. Translational control, or the maintenance of protein homeostasis, has been shown to be essential for neural plasticity and is regulated by mTOR. Both protein over- and under-production via mTOR activity seem to contribute to impaired learning and memory. Furthermore, given that deficits resulting from mTOR overactivity can be alleviated through treatment with rapamycin, it is possible that mTOR plays an important role in affecting cognitive functioning through synaptic plasticity. Further evidence for mTOR activity in neurodegeneration comes from recent findings demonstrating that eIF2α-P, an upstream target of the mTOR pathway, mediates cell death in prion diseases through sustained translational inhibition.
Some evidence points to mTORs role in reduced Aβ clearance as well. mTOR is a negative regulator of autophagy; therefore, hyperactivity in mTOR signaling should reduce Aβ clearance in the AD brain. Disruptions in autophagy may be a potential source of pathogenesis in protein misfolding diseases, including AD. Studies using mouse models of Huntingtons disease demonstrate that treatment with rapamycin facilitates the clearance of huntingtin aggregates. Perhaps the same treatment may be useful in clearing Aβ deposits as well. | 1 | Applied and Interdisciplinary Chemistry |
Internal waves are gravity waves that oscillate within a fluid medium, rather than on its surface. To exist, the fluid must be stratified: the density must change (continuously or discontinuously) with depth/height due to changes, for example, in temperature and/or salinity. If the density changes over a small vertical distance (as in the case of the thermocline in lakes and oceans or an atmospheric inversion), the waves propagate horizontally like surface waves, but do so at slower speeds as determined by the density difference of the fluid below and above the interface. If the density changes continuously, the waves can propagate vertically as well as horizontally through the fluid.
Internal waves, also called internal gravity waves, go by many other names depending upon the fluid stratification, generation mechanism, amplitude, and influence of external forces. If propagating horizontally along an interface where the density rapidly decreases with height, they are specifically called interfacial (internal) waves. If the interfacial waves are large amplitude they are called internal solitary waves or internal solitons. If moving vertically through the atmosphere where substantial changes in air density influences their dynamics, they are called anelastic (internal) waves. If generated by flow over topography, they are called Lee waves or mountain waves. If the mountain waves break aloft, they can result in strong warm winds at the ground known as Chinook winds (in North America) or Foehn winds (in Europe). If generated in the ocean by tidal flow over submarine ridges or the continental shelf, they are called internal tides. If they evolve slowly compared to the Earth's rotational frequency so that their dynamics are influenced by the Coriolis effect, they are called inertia gravity waves or, simply, inertial waves. Internal waves are usually distinguished from Rossby waves, which are influenced by the change of Coriolis frequency with latitude. | 1 | Applied and Interdisciplinary Chemistry |
Two solutions are prepared separately:
* Solution A: 0.02 g of thymol blue, 0.01 g cresol red and 2 mL of ethanol
* Solution B: 0.8 g of sodium bicarbonate, 7.48 g of potassium chloride and 90 mL of water
* Mix Solution A and B and mix 9 mL of the mixed solution to 1000 mL of distilled water.
* This method to determinate the concentration of bicarbonates and carbonates is also called "Magni's method." | 0 | Theoretical and Fundamental Chemistry |
Throughout his career, he rejected offers made to him by foreign laboratories and other parties. After returning to Morocco, Idrissi gained an interest in politics and was an ardent trade unionist and adopted Third-Worldism. He became a community activist and a politician under the banner of the Socialist Union of Popular Forces.
He became a professor at the Mohammadia School of Engineering and moved to Safi, where he conducted research in a number of laboratories in the late 1960s. Idrissis field of research focused on the recovery of uranium from phosphates, which was Moroccos biggest export. During his research, he mapped the Ganntour basin and its uranium repartition.
In 1968, he discovered a significant amount of uranium in Moroccan phosphates, which he announced to local press. Idrissi had estimated that about 72 thousand tons of uranium could be extracted annually as a low-cost byproduct from Moroccan phosphates. The media praised his discovery, and he supplied data regarding his findings to the IAEA. | 0 | Theoretical and Fundamental Chemistry |
An isotope of an element contains the same number of protons, but a different number of neutrons, giving it a different mass number than the element found on the periodic table. Isotopes with a large variation in nucleon number will decay into more stable nuclei, and are known as radionuclides or radioisotopes.
The field of nuclear medicine uses radioisotopes to diagnose and treat patients. The radiation and particles emitted by these radioisotopes can be used to weaken or destroy target cells, for example in the case of cancer. For diagnosis, a radioactive dose is given to a patient and its activity can be tracked to study the functionality of a target organ. The tracers used within this process are generally short-lived isotopes.
Diagnostic radiopharmaceuticals are used to examine organ functionality, blood flow, bone growth and other diagnostic procedures. Radioisotopes needed for this procedure must emit gamma radiation with a high energy and short half-life, in order for it to escape the body and decay quickly. There is currently a trend to use cyclotron-produced isotopes as they are becoming more widely available.
Positron emission tomography (PET) is an imaging technique, using radioisotopes also most often produced with a cyclotron. They are injected into the patient, accumulating in the target tissue, and decays through positron emission. The positron annihilates with an electron nearby which results in the emission to two gamma rays (photons) in opposite directions. A PET camera detects these rays and can determine quantitative information about the target tissue.
Therapeutic radiopharmaceuticals are used to destroy or weaken malfunctioning cells, using a radioisotope localised to a specific organ. This process is called radionuclide therapy (RNT), and uses heavy proton radioisotopes (located on the North-West area of the nuclide chart) that decay through beta or alpha emission. | 0 | Theoretical and Fundamental Chemistry |
Zero-point energy has many observed physical consequences. It is important to note that zero-point energy is not merely an artifact of mathematical formalism that can, for instance, be dropped from a Hamiltonian by redefining the zero of energy, or by arguing that it is a constant and therefore has no effect on Heisenberg equations of motion without latter consequence. Indeed, such treatment could create a problem at a deeper, as of yet undiscovered, theory. For instance, in general relativity the zero of energy (i.e. the energy density of the vacuum) contributes to a cosmological constant of the type introduced by Einstein in order to obtain static solutions to his field equations. The zero-point energy density of the vacuum, due to all quantum fields, is extremely large, even when we cut off the largest allowable frequencies based on plausible physical arguments. It implies a cosmological constant larger than the limits imposed by observation by about 120 orders of magnitude. This "cosmological constant problem" remains one of the greatest unsolved mysteries of physics. | 0 | Theoretical and Fundamental Chemistry |
In real molecules protons are surrounded by a cloud of charge due to adjacent bonds and atoms. In an applied magnetic field () electrons circulate and produce an induced field () which opposes the applied field. The effective field at the nucleus will be . The nucleus is said to be experiencing a diamagnetic shielding. | 0 | Theoretical and Fundamental Chemistry |
At standard temperature and pressure (100 kPa and 273.15 K), we can use Avogadro's law to find the molar volume of an ideal gas: | 0 | Theoretical and Fundamental Chemistry |
Methemoglobinemia is a disorder where a large fraction of hemoglobin in one's blood has converted to inactive forms, generically called methemoglobin. Since methemoglobin is not an oxygen-carrier, methemoglobinemia is a serious disorder, sometimes fatal. Exposure to nitrobenzene, aniline, and their derivatives cause this disorder, which is attributed to their conversion to nitrosobenzene (and derivatives), which inactivate hemoglobin by forming a complex with the Fe center, precluding binding of O. | 0 | Theoretical and Fundamental Chemistry |
Active esters are mainly used as acylating agents. They undergo the same reactions as their unactivated analogues but do so more rapidly. They are prone to hydrolysis, for example. Of great interest is the enhanced reactivity of active esters toward amines to give amides. | 0 | Theoretical and Fundamental Chemistry |
P. aeruginosa is an opportunistic human pathogen associated with cystic fibrosis. In P. aeruginosa infections, quorum sensing is critical for biofilm formation and pathogenicity. P. aeruginosa contains two pairs of LuxI/LuxR homologs, LasI/LasR and RhlI, RhlR. LasI and RhlI are synthase enzymes that catalyze the synthesis of N-(3-oxododecanoyl)-homoserine lactone and N-(butyryl)-homoserine lactone, respectively. The LasI/LasR and the RhlI/RhlR circuits function in tandem to regulate the expression of a number of virulence genes. At a threshold concentration, LasR binds N-(3-oxododecanoyl)-homoserine lactone. Together this bound complex promotes the expression of virulence factors that are responsible for early stages of the infection process.
LasR bound by its autoinducer also activates the expression of the RhlI/RhlR system in P. aeruginosa. This causes the expression of RhlR which then binds its autoinducer, N-(butryl)-homoserine lactone. In turn, autoinducer-bound RhlR activates a second class of genes involved in later stages of infection, including genes needed for antibiotic production. Presumably, antibiotic production by P. aeruginosa is used to prevent opportunistic infections by other bacterial species. N-(3-oxododecanoyl)-homoserine lactone prevents binding between N-(butryl)-homoserine lactone and its cognate regulator, RhlR. It is believed that this control mechanism allows P. aeruginosa to initiate the quorum-sensing cascades sequentially and in the appropriate order so that a proper infection cycle can ensue. | 1 | Applied and Interdisciplinary Chemistry |
Work done on, and work done by, a thermodynamic system need to be distinguished, through consideration of their precise mechanisms. Work done on a thermodynamic system, by devices or systems in the surroundings, is performed by actions such as compression, and includes shaft work, stirring, and rubbing. Such work done by compression is thermodynamic work as here defined. But shaft work, stirring, and rubbing are not thermodynamic work as here defined, in that they do not change the volume of the system against its resisting pressure. Work without change of volume is known as isochoric work, for example when an agency, in the surroundings of the system, drives a frictional action on the surface or in the interior of the system.
In a process of transfer of energy from or to a thermodynamic system, the change of internal energy of the system is defined in theory by the amount of adiabatic work that would have been necessary to reach the final from the initial state, such adiabatic work being measurable only through the externally measurable mechanical or deformation variables of the system, that provide full information about the forces exerted by the surroundings on the system during the process. In the case of some of Joule's measurements, the process was so arranged that some heating that occurred outside the system (in the substance of the paddles) by the frictional process also led to heat transfer from the paddles into the system during the process, so that the quantity of work done by the surrounds on the system could be calculated as shaft work, an external mechanical variable.
The amount of energy transferred as work is measured through quantities defined externally to the system of interest, and thus belonging to its surroundings. In an important sign convention, preferred in chemistry, work that adds to the internal energy of the system is counted as positive. On the other hand, for historical reasons, an oft-encountered sign convention, preferred in physics, is to consider work done by the system on its surroundings as positive. | 0 | Theoretical and Fundamental Chemistry |
Jerome Vinograd (February 9, 1913 – July 7, 1976) was an American biochemist who developed density gradient ultracentrifugation and analytical band centrifugation, and contributed to the understanding of DNA supercoiling. | 0 | Theoretical and Fundamental Chemistry |
Rotation of light's plane of polarization may also occur through the Faraday effect which involves a static magnetic field. However, this is a distinct phenomenon that is not classified as "optical activity." Optical activity is reciprocal, i.e. it is the same for opposite directions of wave propagation through an optically active medium, for example clockwise polarization rotation from the point of view of an observer. In case of optically active isotropic media, the rotation is the same for any direction of wave propagation. In contrast, the Faraday effect is non-reciprocal, i.e opposite directions of wave propagation through a Faraday medium will result in clockwise and anti-clockwise polarization rotation from the point of view of an observer. Faraday rotation depends on the propagation direction relative to that of the applied magnetic field. All compounds can exhibit polarization rotation in the presence of an applied magnetic field, provided that (a component of) the magnetic field is oriented in the direction of light propagation. The Faraday effect is one of the first discoveries of the relationship between light and electromagnetic effects. | 0 | Theoretical and Fundamental Chemistry |
In molecular biology, quantitation of nucleic acids is commonly performed to determine the average concentrations of DNA or RNA present in a mixture, as well as their purity. Reactions that use nucleic acids often require particular amounts and purity for optimum performance. To date, there are two main approaches used by scientists to quantitate, or establish the concentration, of nucleic acids (such as DNA or RNA) in a solution. These are spectrophotometric quantification and UV fluorescence tagging in presence of a DNA dye. | 0 | Theoretical and Fundamental Chemistry |
Pheromone traps are very sensitive, meaning they attract insects present at very low densities. They are often used to detect presence of exotic pests, or for sampling, monitoring, or to determine the first appearance of a pest in an area. They can be used for legal control, and are used to monitor the success of the Boll Weevil Eradication Program and the spread of the spongy moth. The high species-specificity of pheromone traps can also be an advantage, and they tend to be inexpensive and easy to implement. This sensitivity is especially suited to some investigations of invasive species: Flying males are easily blown off course by winds. Rather than introducing noise, Frank et al 2013 find this can actually help detect isolated nests or populations and determine the length of time necessary between introduction and establishment. (Although any trap can answer the same questions, high sensitivity such as provided by pheromone traps does so more accurately.)
However, it is impractical in most cases to completely remove or "trap out" pests using a pheromone trap. Some pheromone-based pest control methods have been successful, usually those designed to protect enclosed areas such as households or storage facilities. There has also been some success in mating disruption. In one form of mating disruption, males are attracted to a powder containing female attractant pheromones. The pheromones stick to the males' bodies, and when they fly off, the pheromones make them attractive to other males. It is hoped that if enough males chase other males instead of females, egg-laying will be severely impeded.
Some difficulties surrounding pheromone traps include sensitivity to bad weather, their ability to attract pests from neighboring areas, and that they generally only attract adults, although it is the juveniles in many species that are pests. They are also generally limited to one sex. | 1 | Applied and Interdisciplinary Chemistry |
When in biotic conditions, anaerobic corrosion can be facilitated by the metabolic activity of microorganisms in the surrounding environment. This process is known as microbiologically-influenced corrosion or bacterial anaerobic corrosion. Most notably, the production of dissolved sulfides by sulfate-reducing bacteria (SRB) react with solid metals and hydrogen ions to form metal sulfides in a redox reaction. | 1 | Applied and Interdisciplinary Chemistry |
Increasingly, people use treated or even untreated sewage for irrigation to produce crops. Cities provide lucrative markets for fresh produce, so are attractive to farmers. Because agriculture has to compete for increasingly scarce water resources with industry and municipal users, there is often no alternative for farmers but to use water polluted with sewage directly to water their crops. There can be significant health hazards related to using water loaded with pathogens in this way. The World Health Organization developed guidelines for safe use of wastewater in 2006. They advocate a multiple-barrier approach to wastewater use, where farmers are encouraged to adopt various risk-reducing behaviors. These include ceasing irrigation a few days before harvesting to allow pathogens to die off in the sunlight, applying water carefully so it does not contaminate leaves likely to be eaten raw, cleaning vegetables with disinfectant or allowing fecal sludge used in farming to dry before being used as a human manure. | 1 | Applied and Interdisciplinary Chemistry |
Some miRNAs target the messenger RNAs for DNA methyltransferase genes DNMT1, DNMT3A and DNMT3B, whose gene products are needed for initiating and stabilizing promoter methylations. As summarized in three reviews, miRNAs miR-29a, miR-29b and miR-29c target DNMT3A and DNMT3B; miR-148a and miR-148b target DNMT3B; and miR-152 and miR-301 target DNMT1. In addition, miR-34b targets DNMT1 and the promoter of miR-34b itself is hypermethylated and under-expressed in the majority of prostate cancers. When expression of these microRNAs is altered, they may also be a source of the hyper/hypo-methylation of the promoters of protein-coding genes in cancers. | 1 | Applied and Interdisciplinary Chemistry |
Wood flour is finely pulverized wood that has a consistency fairly equal to sand or sawdust, but can vary considerably, with particles ranging in dimensions from a fine powder to roughly that of a grain of rice. Most wood flour manufacturers are able to create batches of wood flour that have the same consistency throughout. All high quality wood flour is made from hardwoods because of its durability and strength. Very low grade wood flour is occasionally made from sapless softwoods such as pine or fir. | 1 | Applied and Interdisciplinary Chemistry |
During the first two weeks after fertilization, radiation therapy is lethal but not teratogenic. High doses of radiation during pregnancy induce anomalies, impaired growth and intellectual disability, and there may be an increased risk of childhood leukemia and other tumors in the offspring.
In males previously having undergone radiotherapy, there appears to be no increase in genetic defects or congenital malformations in their children conceived after therapy. However, the use of assisted reproductive technologies and micromanipulation techniques might increase this risk. | 0 | Theoretical and Fundamental Chemistry |
Darcys law was first determined experimentally by Darcy, but has since been derived from the Navier–Stokes equations via homogenization methods. It is analogous to Fouriers law in the field of heat conduction, Ohms law in the field of electrical networks, and Ficks law in diffusion theory.
One application of Darcys law is in the analysis of water flow through an aquifer; Darcys law along with the equation of conservation of mass simplifies to the groundwater flow equation, one of the basic relationships of hydrogeology.
Morris Muskat first refined Darcys equation for a single-phase flow by including viscosity in the single (fluid) phase equation of Darcy. It can be understood that viscous fluids have more difficulty permeating through a porous medium than less viscous fluids. This change made it suitable for researchers in the petroleum industry. Based on experimental results by his colleagues Wyckoff and Botset, Muskat and Meres also generalized Darcys law to cover a multiphase flow of water, oil and gas in the porous medium of a petroleum reservoir. The generalized multiphase flow equations by Muskat and others provide the analytical foundation for reservoir engineering that exists to this day. | 1 | Applied and Interdisciplinary Chemistry |
Nucleic acid analogues are compounds which are analogous (structurally similar) to naturally occurring RNA and DNA, used in medicine and in molecular biology research.
Nucleic acids are chains of nucleotides, which are composed of three parts: a phosphate backbone, a pentose sugar, either ribose or deoxyribose, and one of four nucleobases. An analogue may have any of these altered. Typically the analogue nucleobases confer, among other things, different base pairing and base stacking properties. Examples include universal bases, which can pair with all four canonical bases, and phosphate-sugar backbone analogues such as PNA, which affect the properties of the chain (PNA can even form a triple helix).
Nucleic acid analogues are also called xeno nucleic acids and represent one of the main pillars of xenobiology, the design of new-to-nature forms of life based on alternative biochemistries.
Artificial nucleic acids include peptide nucleic acids (PNA), Morpholino and locked nucleic acids (LNA), as well as glycol nucleic acids (GNA), threose nucleic acids (TNA) and hexitol nucleic acids (HNA). Each of these is distinguished from naturally occurring DNA or RNA by changes to the backbone of the molecule. However, the polyelectrolyte theory of the gene proposes that a genetic molecule require a charged backbone to function.
In May 2014, researchers announced that they had successfully introduced two new artificial nucleotides into bacterial DNA, and by including individual artificial nucleotides in the culture media, were able to passage the bacteria 24 times; they did not create mRNA or proteins able to use the artificial nucleotides. The artificial nucleotides featured 2 fused aromatic rings. | 1 | Applied and Interdisciplinary Chemistry |
-Formylkynurenine is an intermediate in the catabolism of tryptophan. It is a formylated derivative of kynurenine. The formation of -formylkynurenine is catalyzed by heme dioxygenases. | 1 | Applied and Interdisciplinary Chemistry |
Subject to various assumptions and corrections, values of apparent porosity can be derived from any neutron log. One can not underestimate the slow down of neutrons by other elements even if they are less effective. Certain effects, such as lithology, clay content, and amount and type of hydrocarbons, can be recognized and corrected for only if additional porosity information is available, for example from sonic and/or density log. Any interpretation of a neutron log alone should be undertaken with a realization of the uncertainties involved. | 0 | Theoretical and Fundamental Chemistry |
Nanoclusters are atomically precise, crystalline materials most often existing on the 0-2 nanometer scale. They are often considered kinetically stable intermediates that form during the synthesis of comparatively larger materials such as semiconductor and metallic nanocrystals. The majority of research conducted to study nanoclusters has focused on characterizing their crystal structures and understanding their role in the nucleation and growth mechanisms of larger materials.
Materials can be categorized into three different regimes, namely bulk, nanoparticles and nanoclusters. Bulk metals are electrical conductors and good optical reflectors and metal nanoparticles display intense colors due to surface plasmon resonance. However, when the size of metal nanoclusters is further reduced to form a nanocluster, the band structure becomes discontinuous and breaks down into discrete energy levels, somewhat similar to the energy levels of molecules. This gives nanoclusters similar qualities as a singular molecule and does not exhibit plasmonic behavior; nanoclusters are known as the bridging link between atoms and nanoparticles. Nanoclusters may also be referred to as molecular nanoparticles. | 0 | Theoretical and Fundamental Chemistry |
The Growth Arrest and DNA Damage or gadd45 genes, including GADD45A (originally termed gadd45) GADD45B (originally termed MyD118), and GADD45G (originally termed CR6), are implicated as stress sensors that modulate the response of mammalian cells to genotoxic/physiological stress, and modulate tumor formation. Gadd45 proteins interact with other proteins implicated in stress responses, including PCNA, p21, Cdc2/CyclinB1, MEKK4, and p38 kinase.
GADD45 proteins regulate differentiation at the two cell stage of embryogenesis, a key stage of zygotic genome activation. GADD45 likely acts by promoting TET-mediated DNA demethylation leading to the induction of expression of genes necessary for zygote activation.
Overexpression of the GADD45 gene in the Drosophila melanogaster nervous system significantly increases longevity. This longevity increase can be attributed to more efficient recognition and repair of spontaneous DNA damages generated by physiological processes and environmental factors. | 1 | Applied and Interdisciplinary Chemistry |
The terms nucleophile and electrophile were introduced by Christopher Kelk Ingold in 1933, replacing the terms anionoid and cationoid proposed earlier by A. J. Lapworth in 1925. The word nucleophile is derived from nucleus and the Greek word φιλος, philos, meaning friend. | 0 | Theoretical and Fundamental Chemistry |
In the English speaking world, the term "clarke" was not even used in Wells(1937) which introduced Fersmans proposal, nor in later USGS articles such as Fleischer(1953). They used the term "relative abundance of the elements". Brian Mason also mentioned the term "clarke" in Mason(1952)(mistakenly attributing it to Vladimir Vernadsky, later corrected to Fersman in Mason(1958)), but the definition slightly differed from Fersmans, limiting it only to the average percentage in Earth's crust, but allowed to exclude hydrosphere and atmosphere. Besides for explaining the term, Mason himself did not use the term "clarke".
A variant term "clarke value" is occasionally used (examples:). However, "clarke value" can have a different meaning, the clarke of concentration (example:).
Terms "clarke number" and "Clarke number" are found in articles written by Japanese authors (example:). | 0 | Theoretical and Fundamental Chemistry |
The leuco dye variant is typically composed of leuco dyes with additional chemicals to add different desired effects. It is the most commonly used type because it is easier to manufacture. They can be designed to react to changes in temperature that range from -15 °C to 60 °C. Most common applications of the ink have activation temperatures at -10 °C (cold), 31 °C (body temperature), or 43 °C (warm). At lower temperatures, the ink appears to be a certain color, and once the temperature increases, the ink becomes either translucent or lightly colored, allowing hidden patterns to be seen. This gives the effect of a change in color, and the process can also be reversed by lowering the temperature again. | 0 | Theoretical and Fundamental Chemistry |
One of the first groups of atomists in England was a cadre of amateur scientists known as the Northumberland circle, led by Henry Percy, 9th Earl of Northumberland (1564–1632). Although they published little of account, they helped to disseminate atomistic ideas among the burgeoning scientific culture of England, and may have been particularly influential to Francis Bacon, who became an atomist around 1605, though he later rejected some of the claims of atomism. Though they revived the classical form of atomism, this group was among the scientific avant-garde: the Northumberland circle contained nearly half of the confirmed Copernicans prior to 1610 (the year of Galileos The Starry Messenger'). Other influential atomists of late 16th and early 17th centuries include Giordano Bruno, Thomas Hobbes (who also changed his stance on atomism late in his career), and Thomas Hariot. A number of different atomistic theories were blossoming in France at this time, as well (Clericuzio 2000). | 1 | Applied and Interdisciplinary Chemistry |
A compressed gas accumulator consists of a cylinder with two chambers that are separated by an elastic diaphragm, a totally enclosed bladder, or a floating piston. One chamber contains the fluid and is connected to the hydraulic line. The other chamber contains an inert gas (typically nitrogen), usually under pressure, that provides the compressive force on the hydraulic fluid. Inert gas is used because oxygen and oil can form an explosive mixture when combined under high pressure. As the volume of the compressed gas changes, the pressure of the gas (and the pressure on the fluid) changes inversely.
For low pressure water system use the water usually fills a rubber bladder within the tank (pictured), preventing contact with the tank which would otherwise need to be corrosion resistant. Units designed for high-pressure applications such as hydraulic systems are usually pre-charged to a very high pressure (approaching the system operating pressure) and are designed to prevent the bladder or membrane being damaged by this internal pressure when the system pressure is low. For bladder types this generally requires the bladder to be filled with the gas so that when system pressure is zero the bladder is fully expanded rather than being crushed by the gas charge. To prevent the bladder being forced out of the device when the system pressure is low there is typically either an anti-extrusion plate attached to the bladder that presses against and seals the entrance, or a spring-loaded plate on the entrance that closes when the bladder presses against it.
It is possible to increase the gas volume of the accumulator by coupling a gas bottle to the gas side of the accumulator. For the same swing in system pressure this will result in a larger portion of the accumulator volume being used. If the pressure does not vary over a very wide range this can be a cost effective way to reduce the size of the accumulator needed. If the accumulator is not of the piston type care must be taken that the bladder or membrane will not be damaged in any expected over-pressure situation, many bladder-type accumulators cannot tolerate the bladder being crushed under pressure.
A compressed gas accumulator was invented by Jean Mercier for use in variable-pitch propellers. | 1 | Applied and Interdisciplinary Chemistry |
In pharmacology, Schild regression analysis, based upon the Schild equation, both named for Heinz Otto Schild, are tools for studying the effects of agonists and antagonists on the response caused by the receptor or on ligand-receptor binding. | 1 | Applied and Interdisciplinary Chemistry |
IVF success rates are the percentage of all IVF procedures that result in favourable outcomes. Depending on the type of calculation used, this outcome may represent the number of confirmed pregnancies, called the pregnancy rate, or the number of live births, called the live birth rate. Due to advances in reproductive technology, live birth rates by cycle five of IVF have increased from 76% in 2005 to 80% in 2010, despite a reduction in the number of embryos being transferred (which decreased the multiple birth rate from 25% to 8%).
The success rate depends on variable factors such as age of the birthing person, cause of infertility, embryo status, reproductive history, and lifestyle factors. Younger candidates of IVF are more likely to get pregnant. People older than 41 are more likely to get pregnant with a donor egg. People who have been previously pregnant are in many cases more successful with IVF treatments than those who have never been pregnant. | 1 | Applied and Interdisciplinary Chemistry |
Some nuclei can undergo double beta decay (ββ decay) where the charge of the nucleus changes by two units. Double beta decay is difficult to study, as the process has an extremely long half-life. In nuclei for which both β decay and ββ decay are possible, the rarer ββ decay process is effectively impossible to observe. However, in nuclei where β decay is forbidden but ββ decay is allowed, the process can be seen and a half-life measured. Thus, ββ decay is usually studied only for beta stable nuclei. Like single beta decay, double beta decay does not change ; thus, at least one of the nuclides with some given has to be stable with regard to both single and double beta decay.
"Ordinary" double beta decay results in the emission of two electrons and two antineutrinos. If neutrinos are Majorana particles (i.e., they are their own antiparticles), then a decay known as neutrinoless double beta decay will occur. Most neutrino physicists believe that neutrinoless double beta decay has never been observed. | 0 | Theoretical and Fundamental Chemistry |
Plasma osmolarity can be calculated from plasma osmolality by the following equation:
where:
* is the density of the solution in g/ml, which is 1.025 g/ml for blood plasma.
* is the (anhydrous) solute concentration in g/ml – not to be confused with the density of dried plasma
According to IUPAC, osmolality is the quotient of the negative natural logarithm of the rational activity of water and the molar mass of water, whereas osmolarity is the product of the osmolality and the mass density of water (also known as osmotic concentration).
In simpler terms, osmolality is an expression of solute osmotic concentration per mass of solvent, whereas osmolarity is per volume of solution (thus the conversion by multiplying with the mass density of solvent in solution (kg solvent/litre solution).
where is the molality of component .
Plasma osmolarity/osmolality is important for keeping proper electrolytic balance in the blood stream. Improper balance can lead to dehydration, alkalosis, acidosis or other life-threatening changes. Antidiuretic hormone (vasopressin) is partly responsible for this process by controlling the amount of water the body retains from the kidney when filtering the blood stream. | 0 | Theoretical and Fundamental Chemistry |
A fibrin scaffold is a network of protein that holds together and supports a variety of living tissues. It is produced naturally by the body after injury, but also can be engineered as a tissue substitute to speed healing. The scaffold consists of naturally occurring biomaterials composed of a cross-linked fibrin network and has a broad use in biomedical applications.
Fibrin consists of the blood proteins fibrinogen and thrombin which participate in blood clotting. Fibrin glue or fibrin sealant is also referred to as a fibrin based scaffold and used to control surgical bleeding, speed wound healing, seal off hollow body organs or cover holes made by standard sutures, and provide slow-release delivery of medications like antibiotics to tissues exposed.
Fibrin scaffold use is helpful in repairing injuries to the urinary tract, liver lung, spleen, kidney, and heart. In biomedical research, fibrin scaffolds have been used to fill bone cavities, repair neurons, heart valves, vascular grafts and the surface of the eye.
The complexity of biological systems requires customized care to sustain their function. When they are no longer able to perform their purpose, interference of new cells and biological cues is provided by a scaffold material. Fibrin scaffold has many aspects like being biocompatible, biodegradable and easily processable. Furthermore, it has an autologous nature and it can be manipulated in various size and shape. Inherent role in wound healing is helpful in surgical applications. Many factors can be bound to fibrin scaffold and those can be released in a cell-controlled manner. Its stiffness can be managed by changing the concentration according to needs of surrounding or encapsulated cells. Additional mechanical properties can be obtained by combining fibrin with other suitable scaffolds. Each biomedical application has its own characteristic requirement for different kinds of tissues and recent studies with fibrin scaffold are promising towards faster recovery, less complications and long-lasting solutions. | 1 | Applied and Interdisciplinary Chemistry |
LSAT has a Mohs hardness of 6.5, placing it between quartz and the mineral feldspar. Its relative dielectric constant is ~22 and it has a thermal expansion coefficient of 8~10×10/K. The thermal conductivity of LSAT is 5.1 WmK. LSAT's (cubic) lattice parameter of 3.868 Å makes it compatible for the growth of a wide range of perovskite oxides with a relatively low strain.
LSAT's melting temperature of 1,840C is lower compared to similar alternative substrates, such as LaAlO. This property enables the growth of LSAT single crystals using the Czochralski process (CZ), which has commercial advantages. | 0 | Theoretical and Fundamental Chemistry |
Samarium iodide is easily prepared in nearly quantitative yields from samarium metal and either diiodomethane or 1,2-diiodoethane. When prepared in this way, its solutions is most often used without purification of the inorganic reagent.
Solid, solvent-free SmI forms by high temperature decomposition of samarium(III) iodide (SmI). | 0 | Theoretical and Fundamental Chemistry |
Drug checking has been shown to be an effective way to reduce the harm from drug use through informing safer use, limiting use, and helping users avoid the most dangerous substances. The services also provide monitoring and detection of new psychoactive substances to inform public health interventions. The Loop have stated that 20% of samples are handed in for disposal and 40% of service users reduce intake. KnowYourStuffNZ have found that, when substances are not as expected, half of service users state they will not take that substance and a quarter say they will take a smaller quantity. Drug checking services also reach drug users who are not reached by existing services. Evidence from research conducted by Austrian pill testing service CheckIt! found 58% of people who use the service would not otherwise seek out harm reduction information, and about 75% are more likely to access harm reduction services if pill testing is included.
Academic research from the UK has found that one in five substances were not what they were expected to be and two-thirds of misrepresented samples were disposed of. Such on-site testing accesses otherwise hard-to-reach user groups to reduce the harms associated with drug use.
Research that followed-up people who had used drug checking services in the UK revealed that those people acted upon the harm reduction advice that they received from the service. Those people disposed of unwanted substances, reduced their dosage of wanted substances, and reduced their risk of overdose. People also followed those risk management practices after attending festivals, alterted friends to the risks of drug use, and continued to follow that advice.
In a peer-reviewed study published in Journal of Psychopharmacology, researchers at Johns Hopkins found that people were about half as likely (relative risk = 0.56) to report intent to use a product if testing did not identify the substance as MDMA, and this was a statistically significant reduction. | 0 | Theoretical and Fundamental Chemistry |
Bridged μ-nitrido di-iron phthalocyanine compounds such as iron(II) phthalocyanine catalyze the oxidation of methane to methanol, formaldehyde, and formic acid using hydrogen peroxide as sacrificial oxidant. | 0 | Theoretical and Fundamental Chemistry |
Most materials of interest currently being investigated for photothermal therapy are on the nanoscale. One of the key reasons behind this is the enhanced permeability and retention effect observed with particles in a certain size range (typically 20 - 300 nm). Molecules in this range have been observed to preferentially accumulate in tumor tissue. When a tumor forms, it requires new blood vessels in order to fuel its growth; these new blood vessels in/near tumors have different properties as compared to regular blood vessels, such as poor lymphatic drainage and a disorganized, leaky vasculature. These factors lead to a significantly higher concentration of certain particles in a tumor as compared to the rest of the body. | 0 | Theoretical and Fundamental Chemistry |
Hydrophobic concrete has been produced since the mid-20th century.
Active recent research on superhydrophobic materials might eventually lead to more industrial applications.
A simple routine of coating cotton fabric with silica or titania particles by sol-gel technique has been reported, which protects the fabric from UV light and makes it superhydrophobic.
An efficient routine has been reported for making polyethylene superhydrophobic and thus self-cleaning. 99% of dirt on such a surface is easily washed away.
Patterned superhydrophobic surfaces also have promise for lab-on-a-chip microfluidic devices and can drastically improve surface-based bioanalysis.
In pharmaceuticals, hydrophobicity of pharmaceutical blends affects important quality attributes of final products, such as drug dissolution and hardness. Methods have been developed to measure the hydrophobicity of pharmaceutical materials.
The development of hydrophobic passive daytime radiative cooling (PDRC) surfaces, whose effectiveness at solar reflectance and thermal emittance is predicated on their cleanliness, has improved the "self-cleaning" of these surfaces. Scalable and sustainable hydrophobic PDRCs that avoid VOCs have further been developed. | 0 | Theoretical and Fundamental Chemistry |
The immune system uses the lethal effects of oxidants by making the production of oxidizing species a central part of its mechanism of killing pathogens; with activated phagocytes producing both reactive oxygen and nitrogen species. These include superoxide , nitric oxide (•NO) and their particularly reactive product, peroxynitrite (ONOO-). Although the use of these highly reactive compounds in the cytotoxic response of phagocytes causes damage to host tissues, the non-specificity of these oxidants is an advantage since they will damage almost every part of their target cell. This prevents a pathogen from escaping this part of immune response by mutation of a single molecular target. | 1 | Applied and Interdisciplinary Chemistry |
Liquid fluorocarbons have a very high capacity for holding gas in solution. They can hold more oxygen or carbon dioxide than blood does. For that reason, they have attracted ongoing interest related to the possibility of artificial blood or of liquid breathing.
Blood substitutes are the subject of research because the demand for blood transfusions grows faster than donations. In some scenarios, artificial blood may be more convenient or safe. Because fluorocarbons do not normally mix with water, they must be mixed into emulsions (small droplets of perfluorocarbon suspended in water) in order to be used as blood. One such product, Oxycyte, has been through initial clinical trials.
Possible medical uses of liquid breathing (which uses pure perfluorocarbon liquid, not a water emulsion) involve assistance for premature babies or for burn patients (if normal lung function is compromised). Both partial and complete filling of the lungs have been considered, although only the former has undergone any significant tests in humans. Several animal tests have been performed and there have been some human partial liquid ventilation trials. One effort, by Alliance Pharmaceuticals, reached clinical trials but was abandoned because of insufficient advantage compared to other therapies.
Nanocrystals represent a possible method of delivering water- or fat-soluble drugs within a perfluorochemical fluid. The use of these particles is being developed to help treat babies with damaged lungs.
Perfluorocarbons are banned from sports, where they may be used to increase oxygen use for endurance athletes. One cyclist, Mauro Gianetti, was investigated after a near-fatality where PFC use was suspected. Other posited applications include deep-sea diving and space travel, applications that both require total, not partial, liquid ventilation. The 1989 film The Abyss depicted a fictional use of perfluorocarbon for human diving but also filmed a real rat surviving while cooled and immersed in perfluorocarbon. (See also list of fictional treatments of perfluorocarbon breathing.) | 1 | Applied and Interdisciplinary Chemistry |
In thermodynamics, a partial molar property is a quantity which describes the variation of an extensive property of a solution or mixture with changes in the molar composition of the mixture at constant temperature and pressure. It is the partial derivative of the extensive property with respect to the amount (number of moles) of the component of interest. Every extensive property of a mixture has a corresponding partial molar property. | 0 | Theoretical and Fundamental Chemistry |
William Klyne (March 23, 1913, in Enfield, Middlesex – November 13, 1977) was an organic chemist known for his work in steroids and stereochemistry — a field in which he was a "pioneer", and in which Ernest Eliel and Norman Allinger described him as "one of the world's experts".
In 1946, he gained a PhD from the University of Edinburgh with a thesis entitled “The steroid sulphates: studies on the conjugated sulphates of mare’s pregnancy urine".
Klyne taught at Westfield College, University of London, where he served as dean of science from 1971 to 1973, and as vice-principal from 1973 to 1976. He also served on the editorial board of the Biochemical Society from 1950 to 1955, and on IUPACs nomenclature committee from 1971 until his death. As well, he established and maintained the Medical Research Councils Steroid Reference Collection, and wrote several textbooks, including The Chemistry of Steroids (1957) and Atlas of Stereochemical Correlations (1974). | 0 | Theoretical and Fundamental Chemistry |
Staying dry and wearing proper clothing help to prevent hypothermia. Synthetic and wool fabrics are superior to cotton as they provide better insulation when wet and dry. Some synthetic fabrics, such as polypropylene and polyester, are used in clothing designed to wick perspiration away from the body, such as liner socks and moisture-wicking undergarments. Clothing should be loose fitting, as tight clothing reduces the circulation of warm blood. In planning outdoor activity, prepare appropriately for possible cold weather. Those who drink alcohol before or during outdoor activity should ensure at least one sober person is present responsible for safety.
Covering the head is effective, but no more effective than covering any other part of the body. While common folklore says that people lose most of their heat through their heads, heat loss from the head is no more significant than that from other uncovered parts of the body. However, heat loss from the head is significant in infants, whose head is larger relative to the rest of the body than in adults. Several studies have shown that for uncovered infants, lined hats significantly reduce heat loss and thermal stress. Children have a larger surface area per unit mass, and other things being equal should have one more layer of clothing than adults in similar conditions, and the time they spend in cold environments should be limited. However children are often more active than adults, and may generate more heat. In both adults and children, overexertion causes sweating and thus increases heat loss.
Building a shelter can aid survival where there is danger of death from exposure. Shelters can be constructed out of a variety of materials. Metal can conduct heat away from the occupants and is sometimes best avoided. The shelter should not be too big so body warmth stays near the occupants. Good ventilation is essential especially if a fire will be lit in the shelter. Fires should be put out before the occupants sleep to prevent carbon monoxide poisoning. People caught in very cold, snowy conditions can build an igloo or snow cave to shelter.
The United States Coast Guard promotes using life vests to protect against hypothermia through the 50/50/50 rule: If someone is in water for 50 minutes, they have a 50 percent better chance of survival if they are wearing a life jacket. A heat escape lessening position can be used to increase survival in cold water.
Babies should sleep at 16–20 °C (61–68 °F) and housebound people should be checked regularly to make sure the temperature of the home is at least 18 °C (64 °F). | 1 | Applied and Interdisciplinary Chemistry |
A vortex breaker is a device used in engineering to stop the formation of a vortex when a fluid (liquid or gas) is drained from a vessel such as a tank or vapor–liquid separator. The formation of vortices can entrain vapor in the liquid stream, leading to poor separation in process steps such as distillation or excessive pressure drop,
or causing cavitation of downstream pumps.
Vortices can also re-entrain solid particles previously separated from a gas stream in a solid-gas separation device such as a cyclone. | 1 | Applied and Interdisciplinary Chemistry |
Redox gradients form in water columns and their sediments. Varying levels of oxygen (oxic, suboxic, hypoxic) within the water column alter redox chemistry and which redox reactions can occur. Development of oxygen minimum zones also contributes to formation of redox gradients.
Benthic sediments exhibit redox gradients produced by variations in mineral composition, organic matter availability, structure, and sorption dynamics. Limited transport of dissolved electrons through subsurface sediments, combined with varying pore sizes of sediments creates significant heterogeneity in benthic sediments. Oxygen availability in sediments determines which microbial respiration pathways can occur, resulting in a vertical stratification of redox processes as oxygen availability decreases with depth. | 0 | Theoretical and Fundamental Chemistry |
Cylindrospermopsin (abbreviated to CYN, or CYL) is a cyanotoxin produced by a variety of freshwater cyanobacteria. CYN is a polycyclic uracil derivative containing guanidino and sulfate groups. It is also zwitterionic, making it highly water soluble. CYN is toxic to liver and kidney tissue and is thought to inhibit protein synthesis and to covalently modify DNA and/or RNA. It is not known whether cylindrospermopsin is a carcinogen, but it appears to have no tumour initiating activity in mice.
CYN was first discovered after an outbreak of a mystery disease on Palm Island, Queensland, Australia. The outbreak was traced back to a bloom of Cylindrospermopsis raciborskii in the local drinking water supply, and the toxin was subsequently identified. Analysis of the toxin led to a proposed chemical structure in 1992, which was revised after synthesis was achieved in 2000. Several analogues of CYN, both toxic and non-toxic, have been isolated or synthesised.
C. raciborskii has been observed mainly in tropical areas, however has also recently been discovered in temperate regions of Australia, North, South America, New Zealand and Europe. However, CYN-producing strain of C. raciborskii has not been identified in Europe, several other cyanobacteria species occurring across the continent are able to synthesize it. | 0 | Theoretical and Fundamental Chemistry |
Upon identifying the target subunit and its encoding gene, the gene will be isolated and transferred to a second, non-pathogenic organism, and cultured for mass production. The process is also known as heterologous expression.
A suitable expression system is selected based on the requirement of post-translational modifications, costs, ease of product extraction and production efficiency. Commonly used systems for both licensed and developing recombinant subunit vaccines include bacteria, yeast, mammalian cells, insect cells. | 1 | Applied and Interdisciplinary Chemistry |
* 2021, Forbes 30 Under 30 on its Energy list
* 2020, MIT Technology Review award for Top Innovator under 35 in Latin America
* 2019, Global Champion at Global Student Entrepreneur Awards
* 2019, named Brightest AI-CI Mind by the MIT Center for Collective Intelligence | 1 | Applied and Interdisciplinary Chemistry |
Carbon tetrachloride was discovered along with chloromethane and chloroform in oceans, marine algae and volcanoes. The natural emissions of carbon tetrachloride are too little compared to those from anthropogenic sources; for example, the Momotombo Volcano in Nicaragua emits carbon tetrachloride at a flux of 82 grams per year while the global industrial emissions were at 2 × 10 grams per year.
Carbon tetrachloride was found in Red algae Asparagopsis taxiformis and Asparagopsis armata. It was detected in Southern California ecosystems, salt lakes of Kalmykian Steppe and a common liverwort in Czechia. | 1 | Applied and Interdisciplinary Chemistry |
His lectures frequently lasted for three or four hours. His longest known lecture defined the unit of time known as the "Woodward", after which his other lectures were deemed to be so many "milli-Woodwards" long. In many of these, he eschewed the use of slides and drew structures by using multicolored chalk. Typically, to begin a lecture, Woodward would arrive and lay out two large white handkerchiefs on the countertop. Upon one would be four or five colors of chalk (new pieces), neatly sorted by color, in a long row. Upon the other handkerchief would be placed an equally impressive row of cigarettes. The previous cigarette would be used to light the next one. His Thursday seminars at Harvard often lasted well into the night. He had a fixation with blue, and many of his suits, his car, and even his parking space were coloured in blue.
In one of his laboratories, his students hung a large black and white photograph of the master from the ceiling, complete with a large blue "tie" appended. There it hung for some years (early 1970s), until scorched in a minor laboratory fire. He detested exercise, could get along with only a few hours of sleep every night, was a heavy smoker, and enjoyed Scotch whisky and martinis. | 0 | Theoretical and Fundamental Chemistry |
Since the late 1990s product analysis via SYBR Green, other double-strand specific dyes, or probe-based melting curve analysis has become nearly ubiquitous. The probe-based technique is sensitive enough to detect single-nucleotide polymorphisms (SNP) and can distinguish between homozygous wildtype, heterozygous and homozygous mutant alleles by virtue of the dissociation patterns produced. Without probes, amplicon melting (melting and analysis of the entire PCR product) was not generally successful at finding single base variants through melting profiles. With higher resolution instruments and advanced dyes, amplicon melting analysis of one base variants is now possible with several commercially available instruments. For example: Applied Biosystems 7500 Fast System and the 7900HT Fast Real-Time PCR System, Idaho Technologys LightScanner (the first plate-based high resolution melting device), Qiagens Rotor-Gene instruments, and Roche's LightCycler 480 instruments.
Many research and clinical examples exist in the literature that show the use of melting curve analysis to obviate or complement sequencing efforts, and thus reduce costs.
While most quantitative PCR machines have the option of melting curve generation and analysis, the level of analysis and software support varies. High Resolution Melt (known as either Hi-Res Melting, or HRM) is the advancement of this general technology and has begun to offer higher sensitivity for SNP detection within an entire dye-stained amplicon. It is less expensive and simpler in design to develop probeless melting curve systems. However, for genotyping applications, where large volumes of samples must be processed, the cost of development may be less important than the total throughput and ease of interpretation, thus favoring probe-based genotyping methods.
Digital High Resolution Melting (dHRM) is also used in conjunction with digital PCR (dPCR) to improve quantitative power by providing additional information on the melting behavior of the amplified DNA, which can help in distinguishing between different genetic variants and in ensuring the accuracy of the quantification. dHRM is enabled by the use of sensitive DNA-binding dyes and digital PCR instrumentation, which allows for the collection of high-density data points to generate detailed melt profiles. These profiles can be used to identify even subtle differences in nucleic acid sequences, making dHRM a powerful tool for genotyping, mutation scanning, and methylation analysis
dHRM is an advanced molecular technique used for the analysis of genetic variations, such as single nucleotide polymorphisms (SNPs), mutations, and methylations, by monitoring the melting behavior of double-stranded DNA. It is a post-PCR method that involves the gradual heating of PCR-amplified DNA in the presence of intercalating dyes that fluoresce when bound to double-stranded DNA. As the DNA melts, the fluorescence decreases, and the changes in fluorescence are monitored in real-time with digital PCR system. The resulting melting curves are then analyzed to detect genetic differences based on the melting temperatures of the DNA fragments.
The technique has been further advanced by its application on digital microfluidics platforms, which can facilitate the analysis of single-nucleotide polymorphisms (SNPs) with high accuracy and sensitivity. Additionally, massively parallel dHRM has been developed to enable rapid and absolutely quantitative sequence profiling, which can be particularly useful in clinical and industrial settings where accurate quantification of nucleic acids is critical. | 1 | Applied and Interdisciplinary Chemistry |
In October 2003, Dr. Daniel Kwok, Dr. Larry Kostiuk and two graduate students from the University of Alberta discussed a method of hydrodynamic to electrical energy conversion by exploiting the natural electrokinetic properties of a liquid such as ordinary tap water, by pumping fluids through tiny micro-channels with a pressure difference. This technology could some day provide a practical and clean energy storage device, replacing today's batteries, for devices such as mobile phones or calculators which would be charged up by simply pumping water to high pressure. Pressure would then be released on demand, for fluid flow to take place over the micro-channels. When water travels, or streams over a surface, the ions of which water is made "rub" against the solid, leaving the surface slightly charged. Kinetic energy from the moving ions would thus be converted to electrical energy. Although the power generated from a single channel is extremely small, millions of parallel micro-channels can be used to increase the power output.
This streaming potential, water-flow phenomenon was discovered in 1859 by German physicist Georg Hermann Quincke. | 1 | Applied and Interdisciplinary Chemistry |
Thermal spraying techniques are another popular finishing option, and often have better high temperature properties than electroplated coatings due to the thicker coating. The four main thermal spray processes include electric wire arc spray, flame (oxy acetylene combustion) spray, plasma spray and high velocity oxy fuel (HVOF) spray. | 1 | Applied and Interdisciplinary Chemistry |
Concentration-, concentratio, action or an act of coming together at a single place, bringing to a common center, was used in post-classical Latin in 1550 or earlier, similar terms attested in Italian (1589), Spanish (1589), English (1606), French (1632). | 0 | Theoretical and Fundamental Chemistry |
Forensic science, also known as criminalistics, is the application of science principles and methods to support legal decision-making in matters of criminal and civil law.
During criminal investigation in particular, it is governed by the legal standards of admissible evidence and criminal procedure. It is a broad field utilizing numerous practices such as the analysis of DNA, fingerprints, bloodstain patterns, firearms, ballistics, toxicology, and fire debris analysis.
Forensic scientists collect, preserve, and analyze evidence during the course of an investigation. While some forensic scientists travel to the scene of the crime to collect the evidence themselves, others occupy a laboratory role, performing analysis on objects brought to them by other individuals. Others are involved in analysis of financial, banking, or other numerical data for use in financial crime investigation, and can be employed as consultants from private firms, academia, or as government employees.
In addition to their laboratory role, forensic scientists testify as expert witnesses in both criminal and civil cases and can work for either the prosecution or the defense. While any field could technically be forensic, certain sections have developed over time to encompass the majority of forensically related cases. | 0 | Theoretical and Fundamental Chemistry |
All vegetation contains some fluoride, which is absorbed from soil and water. Some plants concentrate fluoride from their environment more than others. All tea leaves contain fluoride; however, mature leaves contain as much as 10 to 20 times the fluoride levels of young leaves from the same plant. | 1 | Applied and Interdisciplinary Chemistry |
Hydrogen-bond catalysis is a type of organocatalysis that relies on use of hydrogen bonding interactions to accelerate and control organic reactions. In biological systems, hydrogen bonding plays a key role in many enzymatic reactions, both in orienting the substrate molecules and lowering barriers to reaction. However, chemists have only recently attempted to harness the power of using hydrogen bonds to perform catalysis, and the field is relatively undeveloped compared to research in Lewis acid catalysis.
Catalytic amounts of hydrogen-bond donors can promote reactions through a variety of different mechanisms. During the course of a reaction, hydrogen bonding can be used to stabilize anionic intermediates and transition states. Alternatively, some catalysts can bind small anions, enabling the formation of reactive electrophilic cations. More acidic donors can act as general or specific acids, which activate electrophiles by protonation. A powerful approach is the simultaneous activation of both partners in a reaction, e.g. nucleophile and electrophile, termed "bifunctional catalysis". In all cases, the close association of the catalyst molecule to substrate also makes hydrogen-bond catalysis a powerful method of inducing enantioselectivity.
Hydrogen-bonding catalysts are often simple to make, relatively robust, and can be synthesized in high enantiomeric purity. New reactions catalyzed by hydrogen-bond donors are being discovered at an increasing pace, including asymmetric variants of common organic reactions useful for synthesis, such as aldol additions, Diels-Alder cycloadditions and Mannich reactions.
However, there are several challenges that must be overcome before hydrogen-bond catalysis can achieve its full potential in terms of synthetic utility. Current known reactions are very substrate specific and generally exhibit low rate acceleration and turnover, thus requiring high catalyst loading. Catalysts are often discovered and optimized by trial and error, and chemists have a poor understanding of the relationship between catalyst structure and reactivity. Additionally, the field suffers from a lack of general mechanistic understanding, which has been greatly outpaced by the discovery of new reactions. With more detailed studies of structure and mechanism in the future, hydrogen-bond catalysis has great potential for enabling new, efficient, selective reactions and promising applications in asymmetric synthesis. | 0 | Theoretical and Fundamental Chemistry |
The most popular COF synthesis route is a boron condensation reaction which is a molecular dehydration reaction between boronic acids. In case of COF-1, three boronic acid molecules converge to form a planar six-membered BO (boroxine) ring with the elimination of three water molecules. | 0 | Theoretical and Fundamental Chemistry |
In the investigation of the infrared spectrum of the Galactic Center of the Milky Way, monoxide vibrations of iron carbonyls in interstellar dust clouds were detected. Iron carbonyl clusters were also observed in Jiange H5 chondrites identified by infrared spectroscopy. Four infrared stretching frequencies were found for the terminal and bridging carbon monoxide ligands.
In the oxygen-rich atmosphere of the Earth, metal carbonyls are subject to oxidation to the metal oxides. It is discussed whether in the reducing hydrothermal environments of the prebiotic prehistory such complexes were formed and could have been available as catalysts for the synthesis of critical biochemical compounds such as pyruvic acid. Traces of the carbonyls of iron, nickel, and tungsten were found in the gaseous emanations from the sewage sludge of municipal treatment plants.
The hydrogenase enzymes contain CO bound to iron. It is thought that the CO stabilizes low oxidation states, which facilitates the binding of hydrogen. The enzymes carbon monoxide dehydrogenase and acetyl-CoA synthase also are involved in bioprocessing of CO. Carbon monoxide containing complexes are invoked for the toxicity of CO and signaling. | 0 | Theoretical and Fundamental Chemistry |
After obtaining his PhD, Kowalski worked briefly for Shell Development. He left Shell in 1971 for Lawrence Livermore Laboratory where he and C. F. Bender worked together to help develop Livermore's proprietary PATTRN data analysis system. | 0 | Theoretical and Fundamental Chemistry |
In boardsports (e.g., surfing, skateboarding and snowboarding), one stands erect on a single, lightweight board that slides along the ground or on water. The need for balance causes one to position the body perpendicular to the direction of motion, with one foot leading the other. As with handedness, when this task is repetitively performed, one tends to naturally choose a particular foot for the leading position. | 0 | Theoretical and Fundamental Chemistry |
Each instrument used in analytical chemistry has a useful working range. This is the range of concentration (or mass) that can be adequately determined by the instrument, where the instrument provides a useful signal that can be related to the concentration of the analyte.
All instruments have an upper and a lower working limit. Concentrations below the working limit do not provide enough signal to be useful, and concentrations above the working limit provide too much signal to be useful. When calibrating an instrument for use, the experimenter must be familiar with both the lower and upper working range of the chosen instrument; results obtained from a sample of concentration outside the working range are often statistically uncertain. | 0 | Theoretical and Fundamental Chemistry |
CCL7 is a multipotent chemokine involved in anti-bacterial, anti-viral and anti-fungal immune responses. For example, CCL7-mediated stimulation of CCR2 chemokine receptors on monocytes is participating in the elimination of Listeria monocytogenes infections by the recruitment of monocytes and TNF/iNOS-producing dendritic cells (TipDCs). Next, the role of the CCL7 was also observed in the mouse infected by West Nile Virus. The genetically deficient mice in CCL7 have increased mortality because of decrease in monocytes and neutrophils. Early induction of CCL7 downstream of TLR9 signaling also promotes the development of robust immunity to cryptococcal infections.
Diseases associated with CCL7 dysregulation are observed. For example, an abnormal increase of CCL7 worsens many disorders, like HIV or lesional psoriasis. Furthermore, CCL7 is implicated in various immunological diseases, as ulcerative colitis, multiple sclerosis or nonatopic and atopic asthma.
It seems, that the expression of CCL7 can activate an antitumor immune response. | 1 | Applied and Interdisciplinary Chemistry |
Bioactivity databases correlate structures or other chemical information to bioactivity results taken from bioassays in literature, patents, and screening programs. | 1 | Applied and Interdisciplinary Chemistry |
Sulfuric acid is the most widely used solution to produce an anodized coating. Coatings of moderate thickness 1.8 μm to 25 μm (0.00007" to 0.001") are known as Type II in North America, as named by MIL-A-8625, while coatings thicker than 25 μm (0.001") are known as Type III, hard-coat, hard anodizing, or engineered anodizing. Very thin coatings similar to those produced by chromic anodizing are known as Type IIB. Thick coatings require more process control, and are produced in a refrigerated tank near the freezing point of water with higher voltages than the thinner coatings. Hard anodizing can be made between 13 and 150 μm (0.0005" to 0.006") thick. Anodizing thickness increases wear resistance, corrosion resistance, ability to retain lubricants and PTFE coatings, and electrical and thermal insulation. Sealing Type III will improve corrosion resistance at the cost of reducing abrasion resistance. Sealing will reduce this greatly. Standards for thin (Soft/Standard) sulfuric anodizing are given by MIL-A-8625 Types II and IIB, AMS 2471 (undyed), and AMS 2472 (dyed), BS EN ISO 12373/1 (decorative), BS 3987 (Architectural). Standards for thick sulphuric anodizing are given by MIL-A-8625 Type III, AMS 2469, BS ISO 10074, BS EN 2536 and the obsolete AMS 2468 and DEF STAN 03-26/1. | 1 | Applied and Interdisciplinary Chemistry |
For almost 50 years molecular biology was based on two dogmas: (i) equating biological function of the protein with a unique three-dimensional structure and (ii) assuming exquisite specificity in protein complexes. Specificity/selectivity is ensured by unambiguous set of interactions formed between the protein and its ligand (another protein, DNA, RNA or small molecule). Many protein complexes however, contain functionally important/critical regions, which remain highly dynamic in the complex or adopt different conformations. This phenomenon is defined fuzziness. The most pertinent example is the cyclin-dependent kinase inhibitor Sic1, which binds to the SCF subunit of Cdc4 in a phosphorylation dependent manner. No regular secondary structures are gained upon phosphorylation and the different phosphorylation sites interchange in the complex. | 0 | Theoretical and Fundamental Chemistry |
In many cases, different cultures leave their materials as the only records; which anthropologists can use to define the existence of such cultures. The progressive use of more sophisticated materials allows archeologists to characterize and distinguish between peoples. This is partially due to the major material of use in a culture and to its associated benefits and drawbacks. Stone-Age cultures were limited by which rocks they could find locally and by which they could acquire by trading. The use of flint around 300,000 BCE is sometimes considered the beginning of the use of ceramics. The use of polished stone axes marks a significant advance, because a much wider variety of rocks could serve as tools.
The innovation of smelting and casting metals in the Bronze Age started to change the way that cultures developed and interacted with each other. Starting around 5,500 BCE, early smiths began to re-shape native metals of copper and gold, without the use of fire and by using tools and weapons. The heating of copper and its shaping with hammers began around 5,000 BCE. Melting and casting started around 4,000 BCE. Metallurgy had its dawn with the reduction of copper from its ore around 3,500 BCE. The first alloy, bronze came into use around 3,000 BCE. | 1 | Applied and Interdisciplinary Chemistry |
Special types of tube cleaning are all such types which are partly in experimental stage only and do not come under the process types mentioned before, such as, for example:
* induction of water hammers, so that the layer or deposit comes off through short-term material elongation
* use of vibration generators, partly at the tubes through vibration exciters, partly by means of piezoelectric crystals in the conveying medium, in order to transform the conveying medium into a cleaning medium through reduction of the surface tension
* magnetic fields to avoid tube calcification
* nanotechnical treatment of tube surfaces to avoid layers and deposits | 1 | Applied and Interdisciplinary Chemistry |
Joseph Needham, the eminent historian of science and technology, divided Chinese alchemy into the "golden age" (400-800) from the end of the Jin to late Tang dynasty and the "silver age" (800-1300) from late Tang to the end of the Song dynasty. Furthermore, Fabrizio Pregadio uses "golden age" in specific reference to the Tang period.
The extant Chinese alchemical literature comprises about 100 sources preserved in the Daoist Canon. These texts show that while early was mainly concerned with the performance of ceremonies and other ritual actions addressed to gods and demons, a shift occurred around the 6th or 7th century to the later tradition that used alchemical symbolism to represent the origins and functioning of the cosmos, which played a crucial role in the development of . | 1 | Applied and Interdisciplinary Chemistry |
Various PPGs, often featuring the 2-nitrobenzyl motif, have been used to generate numerous gels. In one example, researchers incorporated PPGs into a silica-based sol-gel. In a second example, a hydrogel was synthesized to include protected Ca ions. Finally, PPGs have been utilized to cross-link numerous photodegradable polymers, which have featured linear, multi-dimensional network, dendrimer, and branched structures. | 0 | Theoretical and Fundamental Chemistry |
Chlorprothixene may increase the plasma-level of concomitantly given lithium. In order to avoid lithium intoxication, lithium plasma levels should be monitored closely.
If chlorprothixene is given concomitantly with opioids, the opioid dose should be reduced (by approx. 50%), because chlorprothixene amplifies the therapeutic actions and side effects of opioids considerably.
Avoid the concomitant use of chlorprothixene and tramadol (Ultram). Seizures may be encountered with this combination.
Consider additive sedative effects and confusional states to emerge, if chlorprothixene is given with benzodiazepines or barbiturates. Choose particular low doses of these drugs.
Exert particular caution in combining chlorprothixene with other anticholinergic drugs (tricyclic antidepressants and antiparkinsonian agents): Particularly the elderly may develop delirium, high fever, severe obstipation, even ileus and glaucoma . | 0 | Theoretical and Fundamental Chemistry |
* An array or slide is a collection of features spatially arranged in a two dimensional grid, arranged in columns and rows.
* Block or subarray: a group of spots, typically made in one print round; several subarrays/ blocks form an array.
* Case/control: an experimental design paradigm especially suited to the two-colour array system, in which a condition chosen as control (such as healthy tissue or state) is compared to an altered condition (such as a diseased tissue or state).
* Channel: the fluorescence output recorded in the scanner for an individual fluorophore and can even be ultraviolet.
* Dye flip or dye swap or fluor reversal: reciprocal labelling of DNA targets with the two dyes to account for dye bias in experiments.
* Scanner: an instrument used to detect and quantify the intensity of fluorescence of spots on a microarray slide, by selectively exciting fluorophores with a laser and measuring the fluorescence with a filter (optics) photomultiplier system.
* Spot or feature: a small area on an array slide that contains picomoles of specific DNA samples.
* For other relevant terms see:
** Glossary of gene expression terms
** Protocol (natural sciences) | 1 | Applied and Interdisciplinary Chemistry |
Glass ionomer sealants are thought to prevent caries through a steady fluoride release over a prolonged period and the fissures are more resistant to demineralization, even after the visible loss of sealant material, however, a systemic review found no difference in caries development when GICs was used as a fissure sealing material compared to the conventional resin based sealants, in addition, it has less retention to the tooth structure than the resin based sealants.
These sealants have hydrophilic properties, allowing them to be an alternative of the hydrophobic resin in the generally wet oral cavity. Resin-based sealants are easily destroyed by saliva contamination.
They chemically bond with both enamel and dentin and do not necessarily require preparation/mechanical retention and can therefore be applied without harming existing tooth structure. This makes them ideal in many situations when tooth preservation is foremost and with minimally invasive techniques, particularly Class V fillings where there is a larger area of exposed dentin with only a thin ring of enamel. This often results in longer retention and service life than resin Class V fillings.
They chemically bond to enamel and dentin leaving a smaller gap for bacteria to enter. Particularly when paired with silver diamine fluoride this can arrest caries and harden active caries and prevent further damage.
They can be placed and cured outside of clinical settings and do not require a curing light.
Chemically curable glass ionomer cements are considered safe from allergic reactions but a few have been reported with resin-based materials. Nevertheless, allergic reactions are very rarely associated with both sealants. | 0 | Theoretical and Fundamental Chemistry |
Esketamine, sold under the brand names Spravato (for depression) and Ketanest (for anesthesia) among others, is the S(+) enantiomer of ketamine. It is a dissociative hallucinogen drug used as a general anesthetic and as an antidepressant for treatment of depression. Esketamine is the active enantiomer of ketamine in terms of NMDA receptor antagonism and is more potent than racemic ketamine.
It is specifically used as a therapy for treatment-resistant depression (TRD) and for major depressive disorder (MDD) with co-occurring suicidal ideation or behavior. Its efficacy for depression is modest and similar to that of other antidepressants. Esketamine is not used by infusion into a vein for anesthesia as it is only FDA approved for depression in the form of an intranasal spray (the parent compound Ketamine is most often administered intravenously) and under direct medical supervision as a nasal spray.
Adverse effects of esketamine include dissociation, dizziness, sedation, nausea, vomiting, vertigo, numbness, anxiety, lethargy, increased blood pressure, and feelings of drunkenness. Less often, esketamine can cause bladder problems. Esketamine acts primarily as a N-methyl--aspartate (NMDA) receptor antagonist but also has other actions.
In the form of racemic ketamine, esketamine was first synthesized in 1962 and introduced for medical use as an anesthetic in 1970. Enantiopure esketamine was introduced for medical use as an anesthetic in 1997 and as an antidepressant in 2019. It is used as an anesthetic in the European Union and as an antidepressant in the United States and Canada. Due to misuse liability as a dissociative hallucinogen, esketamine is a controlled substance. | 0 | Theoretical and Fundamental Chemistry |
hnRNP C is a key regulator of the BRCA1 and BRCA2 genes. In response to ionizing radiation, hnRNP C partially localizes to the site of DNA damage, and when depleted, S-phase progression of the cell is impaired. Additionally, BRCA1 and BRCA2 levels fall when hnRNP C is lost. BRCA1 and BRCA2 are crucial tumor-suppressor genes which are strongly implicated in breast cancers when mutated. BRCA1 in particular causes G2/M cell cycle arrest in response to DNA damage via the CHEK1 signaling cascade. hnRNP C is important for the proper expression of other tumor suppressor genes including RAD51 and BRIP1 as well. Through these genes, hnRNP is necessary to induce cell-cycle arrest in response to DNA damage by ionizing radiation. | 1 | Applied and Interdisciplinary Chemistry |
The fundamental idea behind spontaneous protein adsorption is that adsorption occurs when more energy is released than gained according to Gibbs law of free energy.
This is seen in the equation:
::</big>
where:
* ∆ is net change of the parameters
* G is Gibbs free energy
* T is the temperature (SI unit: kelvin)
* S is the entropy (SI unit: joule per kelvin)
* H is the enthalpy (SI unit: joule)
In order for the protein adsorption to occur spontaneously, ∆G must be a negative number. | 1 | Applied and Interdisciplinary Chemistry |
3-Methylfentanyl (3-MF, mefentanyl) is an opioid analgesic that is an analog of fentanyl. 3-Methylfentanyl is one of the most potent opioids, estimated to be between 400 and 6000 times stronger than morphine, depending on which isomer is used (with the cis isomers being the more potent ones). | 1 | Applied and Interdisciplinary Chemistry |
HO masers, a type of astrophysical maser, were the first masers to be discovered in space and have been observed in more environments than any other type of maser.
In the Milky Way, HO masers are found in stellar masers (evolved stars), interstellar masers (regions of massive star formation), or in the interface between supernova remnants and molecular material. Interstellar HO masers are often observed from molecular material surrounding ultracompact H II regions (UC H II). But there are masers associated with very young stars that have yet to create UC H II regions. This class of HO masers appears to form near the edges of very dense material, places where HO masers form, and where total densities drop rapidly, and UV radiation from young stars can dissociate the HO molecules. So, observations of HO masers in these regions, can be an important way to probe the distribution of the important HO molecule in interstellar shocks at high spatial resolutions.
Application in water purification
Hydroxyl radicals also play a key role in the oxidative destruction of organic pollutants. | 1 | Applied and Interdisciplinary Chemistry |
A novel method, Nm-REP-seq, was developed for the transcriptome-wide identification of 2-O-methylation sites at single-base resolution by using RNA exoribonuclease (Mycoplasma genitalium RNase R, MgR) and periodate oxidation reactivity to eliminate 2-hydroxylated (2-OH) nucleosides. Nm-REP-seq discovered telomerase RNA component (TERC) RNA, scaRNAs and snoRNAs as new classes of Nm-containing ncRNAs as well as identified many 2-O-methylation sites in various ncRNAs and mRNAs. Furthermore, Nm-REP-seq revealed 2'-O-Methylation located at the 3’-end of snoRNAs, snRNAs, tRNAs and fragments derived from them, as well as piRNAs and miRNAs. | 1 | Applied and Interdisciplinary Chemistry |
Aspirin (acetylsalicylic acid), an organic compound that does not occur in nature, was first synthesised in 1899.
In 1897, scientists at the drug and dye firm Bayer began investigating acetylated organic compounds as possible new medicines, following the success of acetanilide ten years earlier. Two years later, Bayer created acetylsalicylic acid, which they marketed around the world under the brand name "Aspirin". The drug was sold widely in the first half of the twentieth century, both by Bayer and by competing drug manufacturers. The name "aspirin" was so widely used that Bayer lost (or sold) the rights to the trademark in many countries.
Aspirins popularity declined after the development of acetaminophen/paracetamol in 1956 and ibuprofen in 1962. In the 1960s and 1970s, John Vane and others discovered the basic mechanism of aspirins effects, while clinical trials and other studies from the 1960s to the 1980s established aspirin's efficacy as an anti-clotting agent that reduces the risk of clotting diseases. Aspirin sales revived considerably in the last decades of the twentieth century, and remain strong in the twenty-first with widespread use as a preventive treatment for heart attacks and strokes. | 1 | Applied and Interdisciplinary Chemistry |
The essential structural components of all statins are a dihydroxyheptanoic acid unit and a ring system with different substituents. The statin pharmacophore is modified hydroxyglutaric acid component, which is structurally similar to the endogenous substrate HMG CoA and the mevaldyl CoA transition state intermediate (Figure 1). The statin pharmacophore binds to the same active site as the substrate HMG-CoA and inhibits the HMGR enzyme. It has also been shown that the HMGR is stereoselective and as a result all statins need to have the required 3R,5R stereochemistry. | 1 | Applied and Interdisciplinary Chemistry |
The axisymmetric stagnation point flow corresponds to . The flow field can be simply described in cylindrical coordinate system with velocity components as follows
where we let . | 1 | Applied and Interdisciplinary Chemistry |
Alloy broadening is a spectral-line broadening mechanism caused by random distribution of the atoms in an alloy.
The alloy broadening is one of the line broadening mechanisms. The random distribution of atoms in an alloy causes a different material composition at different positions. In semiconductors and insulators the different material composition leads to different band gap energies. This gives different exciton recombination energies. Therefore, depending on the position where an exciton recombines the emitted light has a different energy. The alloy broadening is an inhomogeneous line broadening, meaning that its shape is Gaussian. | 0 | Theoretical and Fundamental Chemistry |
The most important gas which leads to acidification is sulfur dioxide. Emissions of nitrogen oxides which are oxidized to form nitric acid are of increasing importance due to stricter controls on emissions of sulfur compounds. 70 Tg(S) per year in the form of SO comes from fossil fuel combustion and industry, 2.8 Tg(S) from wildfires, and 7–8 Tg(S) per year from volcanoes. | 1 | Applied and Interdisciplinary Chemistry |
A DNA adduct is a segment of DNA that binds to a chemical carcinogen. Some adducts that cause lesions to DNA included oxidatively modified bases, propano-, etheno-, and MDA-induced adducts. 5‐Hydroxymethyluracil is an example of an oxidatively modified base where oxidation of the methyl group of thymine occurs. This adduct interferes with the binding of transcription factors to DNA which can trigger apoptosis or result in deletion mutations. Propano adducts are derived by species generated by lipid peroxidation. For example, HNE is a major toxic product of the process. It regulates the expression of genes that are involved in cell cycle regulation and apoptosis. Some of the aldehydes from lipid peroxidation can be converted to epoxy aldehydes by oxidation reactions. These epoxy aldehydes can damage DNA by producing etheno adducts. An increase in this type of DNA lesion exhibits conditions resulting in oxidative stress which is known to be associated with an increased risk of cancer. Malondialdehyde (MDA) is another highly toxic product from lipid peroxidation and also in the synthesis of prostaglandin. MDA reacts with DNA to form the M1dG adduct which causes DNA lesions. | 1 | Applied and Interdisciplinary Chemistry |
The Stark–Einstein law is named after German-born physicists Johannes Stark and Albert Einstein, who independently formulated the law between 1908 and 1913. It is also known as the photochemical equivalence law or photoequivalence law. In essence it says that every photon that is absorbed will cause a (primary) chemical or physical reaction.
The photon is a quantum of radiation, or one unit of radiation. Therefore, this is a single unit of EM radiation that is equal to the Planck constant (h) times the frequency of light. This quantity is symbolized by γ, hν, or ħω.
The photochemical equivalence law is also restated as follows: for every mole of a substance that reacts, an equivalent mole of quanta of light are absorbed. The formula is:
where N is the Avogadro constant.
The photochemical equivalence law applies to the part of a light-induced reaction that is referred to as the primary process (i.e. absorption or fluorescence).
In most photochemical reactions the primary process is usually followed by so-called secondary photochemical processes that are normal interactions between reactants not requiring absorption of light. As a result, such reactions do not appear to obey the one quantum–one molecule reactant relationship.
The law is further restricted to conventional photochemical processes using light sources with moderate intensities; high-intensity light sources such as those used in flash photolysis and in laser experiments are known to cause so-called biphotonic processes; i.e., the absorption by a molecule of a substance of two photons of light. | 0 | Theoretical and Fundamental Chemistry |
Copper goes through a natural oxidation process that forms a unique protective patina on the metal. The surface of the metal undergoes a series of color changes: from iridescent/salmon pinks to oranges and reds interspersed with brassy yellows, blues, greens and purples. As the oxide thickens, these colors are replaced by russet and chocolate browns, dull slate grays or blacks, and finally to a light-green or blue-green.
Copper's patination process is complex. It starts immediately on exposure to the environment with the initial formation of copper oxide conversion films that are noticeable within six months. Weathering may be uneven at first but the film becomes even after about nine months. Within the first few years, cuprous and cupric sulfide conversion films darken the surface to browns and then dull slate gray or dull black. Continued weathering transforms the sulfide films to sulfates, which are the notable blue-green or gray-green patinas.
The rate of patination conversion is dependent upon copper's exposure to moisture, salt, and acidity from acid-forming pollutants. In marine climates, the entire patination process can take seven to nine years. In industrial environments, patina formation reaches its final stage in about fifteen to twenty-five years. In clean rural atmospheres with low concentrations of airborne sulfur dioxide, the final stage may take ten to thirty years to develop. In arid environments, a patina may not form at all if the moisture is insufficient. Where patination does take place in arid environments, it may mature to an ebony or nut brown. In all environments except the coastal areas, patination takes longer for vertical surfaces due to more rapid water runoff.
The copper patinas are very thin: just in thickness. Yet, they are highly adherent to the underlying copper metal. The initial and intermediate oxide and sulfide patina films are not particularly corrosion resistant. The final sulfate patina is a particularly durable layer that is highly resistant to all forms of atmospheric corrosion and protects the underlying metal against further weathering. As patination progresses and the durable sulfate layer forms, the rate of corrosion decreases, averaging between per year. For a sheet, this equates to less than 5% corrosion over a period of 100 years. Further information is available on copper patination. | 1 | Applied and Interdisciplinary Chemistry |
Environmental impact is in general hard to validate. To be able to trust the models is very important that the models are transparent and provide multiple levels of verification. The strategy here is to not calculate everything in the simulation model and instead provide results, which can be verified, to calculate the used resources from. E.g. from the amount of processing time for a machine it is possible to calculate the used energy. From the used resources upstream processes required to produce the resources can be included to get a total emission for the production, e.g. if the emissions to produce one kWh electricity is 0.1 kgCO then the 4 kWh electricity used in a machine give an emission of 0.4 kgCO. The concept is called Level of Equation. The basis is to divide the calculations of environmental impact into 4 levels
* Process times, lead times, idle times, setup times, etc.
* Consumption of resources e.g. Electricity, steal, oil, etc.
* Emissions
* Environmental impact, e.g. [GWP] | 1 | Applied and Interdisciplinary Chemistry |
Of the various methods of labeling biomolecules, fluorescent labels are advantageous in that they are highly sensitive even at low concentration and non-destructive to the target molecule folding and function.
Green fluorescent protein is a naturally occurring fluorescent protein from the jellyfish Aequorea victoria that is widely
used to tag proteins of interest. GFP emits a photon in the green region of the light spectrum when excited by the absorption of light. The chromophore consists of an oxidized tripeptide -Ser^65-Tyr^66-Gly^67 located within a β barrel. GFP catalyzes the oxidation and
only requires molecular oxygen. GFP has been modified by changing the wavelength of light absorbed to include other colors of fluorescence. YFP or yellow fluorescent protein, BFP or blue fluorescent protein, and CFP or cyan fluorescent protein are examples of GFP variants. These variants are produced by the genetic engineering of the GFP gene.
Synthetic fluorescent probes can also be used as fluorescent labels. Advantages of these labels include a smaller size with more variety in color. They can be used to tag proteins of interest more selectively by various methods including chemical recognition-based labeling, such as utilizing metal-chelating peptide tags, and biological recognition-based labeling utilizing enzymatic reactions. However, despite their wide array of excitation and emission wavelengths as well as better stability, synthetic probes tend to be toxic to the cell and so are not generally used in cell imaging studies.
Fluorescent labels can be hybridized to mRNA to help visualize interaction and activity, such as mRNA localization. An antisense strand labeled with the fluorescent probe is attached to a single mRNA strand, and can then be viewed during cell development to see the movement of mRNA within the cell. | 1 | Applied and Interdisciplinary Chemistry |
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