text stringlengths 105 4.57k | label int64 0 1 | label_text stringclasses 2 values |
|---|---|---|
An oil formulation consists of the base or stock oil and oil additives. Most oil formulations contain basic additives and detergents, designed to react with and neutralise acids, preventing damage to engine parts, including corrosion of metal surfaces. | 0 | Theoretical and Fundamental Chemistry |
Karen K. Hsiao Ashe is a professor at the Department of Neurology and Neuroscience at the University of Minnesota (UMN) Medical School, where she holds the Edmund Wallace and Anne Marie Tulloch Chairs in Neurology and Neuroscience. She is the founding director of the N. Bud Grossman Center for Memory Research and Care, and her specific research interest is memory loss resulting from Alzheimers disease and related dementias. Her research has included the development of an animal model of Alzheimers.
In July 2022, concerns were raised that certain images in a 2006 Nature paper co-authored by Ashes postdoctoral student Sylvain Lesné were manipulated. In May of 2023, the Star Tribune reported that Ashe was using new techniques to re-do the work reported in the 2006 Nature study, and that she stated "its my responsibility to establish the truth of what we've published". | 1 | Applied and Interdisciplinary Chemistry |
Tissue samples are lysed in buffer supplemented with leupeptin to maintain enzymatic activity. The samples are standardized for protein concentration and then loaded into a polyacrylamide gel for SDS-PAGE. After separation of proteins by molecular weight is complete, the gel is incubated in a renaturing buffer to restore enzymatic activity. During loading, a non-reducing buffer was used to preserve protein disulfide bonds. After the renaturing period, the gel is then incubated in assay buffer to allow the now active cathepsins to proteolyze the gelatin impregnated in the gel. This process takes place overnight. The next day, the gel is analyzed for regions of gelatin degradation by coomassie blue staining. Patches of gel that are no longer blue following a destain wash are noted. These bands are then correlated to their respective molecular weights in order to identify which cathepsins were active in the sample.
Cathepsin K detection by zymography | 1 | Applied and Interdisciplinary Chemistry |
In the past, biologists have used lux or energy meters to quantify light intensity. They switched to using PPFD when it was realized that the flux of photons in the 400-700 nm range is the important factor in driving the photosynthetic process. However, PPFD is usually expressed as the photon flux per second. This is a convenient time scale when measuring short-term changes in photosynthesis in gas exchange systems, but falls short when the light climate for plant growth has to be characterized. First because it does not take into account the length of the day light period, but foremost because light intensity in the field or in glasshouses changes so much diurnally and from day to day. Scientists have tried to solve this by reporting light intensity measured for one or more sunny days at noon, but this is grasping the light level for only a very short period of the day. Daily light integral includes both the diurnal variation and day length, and can also be reported as a mean value per month or over an entire experiment. It has been shown to be better related to plant growth and morphology than PPFD at any moment or day length alone. Some energy meters are able to capture PPFD during an interval period such as 24-hours. | 0 | Theoretical and Fundamental Chemistry |
Pyridine is readily degraded by bacteria to ammonia and carbon dioxide. The unsubstituted pyridine ring degrades more rapidly than picoline, lutidine, chloropyridine, or aminopyridines, and a number of pyridine degraders have been shown to overproduce riboflavin in the presence of pyridine. Ionizable N-heterocyclic compounds, including pyridine, interact with environmental surfaces (such as soils and sediments) via multiple pH-dependent mechanisms, including partitioning to soil organic matter, cation exchange, and surface complexation. Such adsorption to surfaces reduces bioavailability of pyridines for microbial degraders and other organisms, thus slowing degradation rates and reducing ecotoxicity. | 0 | Theoretical and Fundamental Chemistry |
According to Arrhenius's original molecular definition, an acid is a substance that dissociates in aqueous solution, releasing the hydrogen ion (a proton):
The equilibrium constant for this dissociation reaction is known as a dissociation constant. The liberated proton combines with a water molecule to give a hydronium (or oxonium) ion (naked protons do not exist in solution), and so Arrhenius later proposed that the dissociation should be written as an acid–base reaction:
Brønsted and Lowry generalised this further to a proton exchange reaction:
The acid loses a proton, leaving a conjugate base; the proton is transferred to the base, creating a conjugate acid. For aqueous solutions of an acid HA, the base is water; the conjugate base is and the conjugate acid is the hydronium ion. The Brønsted–Lowry definition applies to other solvents, such as dimethyl sulfoxide: the solvent S acts as a base, accepting a proton and forming the conjugate acid .
In solution chemistry, it is common to use as an abbreviation for the solvated hydrogen ion, regardless of the solvent. In aqueous solution denotes a solvated hydronium ion rather than a proton.
The designation of an acid or base as "conjugate" depends on the context. The conjugate acid of a base B dissociates according to
which is the reverse of the equilibrium
The hydroxide ion , a well known base, is here acting as the conjugate base of the acid water. Acids and bases are thus regarded simply as donors and acceptors of protons respectively.
A broader definition of acid dissociation includes hydrolysis, in which protons are produced by the splitting of water molecules. For example, boric acid () produces as if it were a proton donor, but it has been confirmed by Raman spectroscopy that this is due to the hydrolysis equilibrium:
Similarly, metal ion hydrolysis causes ions such as to behave as weak acids:
According to Lewis's original definition, an acid is a substance that accepts an electron pair to form a coordinate covalent bond. | 0 | Theoretical and Fundamental Chemistry |
N-Oleoylsarcosine (Sarkosyl O) is an amphiphilic oleic acid derivative having a sarcosine head group (N-methylglycine) which is used as a water-in-oil emulsifier and corrosion inhibitor. | 0 | Theoretical and Fundamental Chemistry |
Atomism (from Greek , atomon, i.e. "uncuttable, indivisible") is a natural philosophy proposing that the physical universe is composed of fundamental indivisible components known as atoms.
References to the concept of atomism and its atoms appeared in both ancient Greek and ancient Indian philosophical traditions. Leucippus is the earliest figure whose commitment to atomism is well attested and he is usually credited with inventing atomism. He and other ancient Greek atomists theorized that nature consists of two fundamental principles: atom and void. Clusters of different shapes, arrangements, and positions give rise to the various macroscopic substances in the world.
Indian Buddhists, such as Dharmakirti ( 6th or 7th century) and others, developed distinctive theories of atomism, for example, involving momentary (instantaneous) atoms (kalapas) that flash in and out of existence.
The particles of chemical matter for which chemists and other natural philosophers of the early 19th century found experimental evidence were thought to be indivisible, and therefore were given by John Dalton the name "atom", long used by the atomist philosophy. Although the connection to historical atomism is at best tenuous, elementary particles have become a modern analogue of philosophical atoms. | 1 | Applied and Interdisciplinary Chemistry |
A piping and instrumentation diagram (P&ID or PID) is a detailed diagram in the process industry which shows the piping and process equipment together with the instrumentation and control devices. It is also called as mechanical flow diagram (MFD).
Superordinate to the P&ID is the process flow diagram (PFD) which indicates the more general flow of plant processes and the relationship between major equipment of a plant facility. | 1 | Applied and Interdisciplinary Chemistry |
*CCP4i – CCP4 Graphical User Interface
*CCP4MG – CCP4 Molecular Graphics Project
*Coot – Graphical Model Building
*HAPPy – automated experimental phasing
*MrBUMP – automated Molecular Replacement
*PISA – Protein Interfaces, Surfaces and Assemblies
*MOSFLM GUI – building a modern interface to MOSFLM | 0 | Theoretical and Fundamental Chemistry |
The BOD is used in measuring waste loadings to treatment plants and in evaluating the BOD-removal efficiency of such treatment systems. | 0 | Theoretical and Fundamental Chemistry |
A hand boiler or (less commonly) love meter is a glass sculpture used as an experimental tool to demonstrate vapour-liquid equilibrium, or as a collector's item to whimsically "measure love." It consists of a lower bulb containing a volatile liquid and a mixture of gases that is connected usually by a twisting glass tube that connects to an upper or "receiving" glass bulb. | 0 | Theoretical and Fundamental Chemistry |
Gene guns have also been used to deliver DNA vaccines.
The delivery of plasmids into rat neurons through the use of a gene gun, specifically DRG neurons, is also used as a pharmacological precursor in studying the effects of neurodegenerative diseases such as Alzheimer's disease.
The gene gun has become a common tool for labeling subsets of cells in cultured tissue. In addition to being able to transfect cells with DNA plasmids coding for fluorescent proteins, the gene gun can be adapted to deliver a wide variety of vital dyes to cells.
Gene gun bombardment has also been used to transform Caenorhabditis elegans, as an alternative to microinjection. | 1 | Applied and Interdisciplinary Chemistry |
Catalysis --
Catalytic cracking --
Catalytic reforming --
Catalytic reaction engineering --
Ceramics --
Certified Chartered Chemical Engineers --
Chartered Chemical Engineers --
Chemical engineering --
Chemical kinetics --
Chemical reaction --
Chemical synthesis --
Chemical vapor deposition (CVD) --
Chemical solution deposition --
Chemistry --
Chromatographic separation --
Circulating fluidized bed --
Combustion --
Computational fluid dynamics (CFD) --
Conservation of energy --
Conservation of mass --
Conservation of momentum --
Crystallization processes -- | 1 | Applied and Interdisciplinary Chemistry |
In chemistry, a steady state is a situation in which all state variables are constant in spite of ongoing processes that strive to change them. For an entire system to be at steady state, i.e. for all state variables of a system to be constant, there must be a flow through the system (compare mass balance). A simple example of such a system is the case of a bathtub with the tap running but with the drain unplugged: after a certain time, the water flows in and out at the same rate, so the water level (the state variable Volume) stabilizes and the system is in a steady state.
The steady state concept is different from chemical equilibrium. Although both may create a situation where a concentration does not change, in a system at chemical equilibrium, the net reaction rate is zero (products transform into reactants at the same rate as reactants transform into products), while no such limitation exists in the steady state concept. Indeed, there does not have to be a reaction at all for a steady state to develop.
The term steady state is also used to describe a situation where some, but not all, of the state variables of a system are constant. For such a steady state to develop, the system does not have to be a flow system. Therefore, such a steady state can develop in a closed system where a series of chemical reactions take place. Literature in chemical kinetics usually refers to this case, calling it steady state approximation.
In simple systems the steady state is approached by state variables gradually decreasing or increasing until they reach their steady state value. In more complex systems state variables might fluctuate around the theoretical steady state either forever (a limit cycle) or gradually coming closer and closer. It theoretically takes an infinite time to reach steady state, just as it takes an infinite time to reach chemical equilibrium.
Both concepts are, however, frequently used approximations because of the substantial mathematical simplifications these concepts offer. Whether or not these concepts can be used depends on the error the underlying assumptions introduce. So, even though a steady state, from a theoretical point of view, requires constant drivers (e.g. constant inflow rate and constant concentrations in the inflow), the error introduced by assuming steady state for a system with non-constant drivers may be negligible if the steady state is approached fast enough (relatively speaking). | 0 | Theoretical and Fundamental Chemistry |
Heating polymers to a sufficiently high temperature can cause damaging chemical changes, even in the absence of oxygen. This usually starts with chain scission, generating free radicals, which primarily engage in disproportionation and crosslinking.
PVC is the most thermally sensitive common polymer, with major degradation occurring from ~ onwards; other polymers degrade at higher temperatures. | 0 | Theoretical and Fundamental Chemistry |
This Fluid dynamics problem can be solved by different Numerical Methods. However, to solve it with Numerical Methods several assumptions have to be considered. And as a result shock layer properties and shock location is determined. Results vary with one or more than one of viscosity of the fluid, Mach number and angle of incidence changes. Generally for large angles of incidences, the variation of Reynold's Number has significant effects on the change of the flow variables, whereas the viscous effects are dominant on the upper surface of the plate as well as behind the trailing edge of the plate.
Different experimenters get different result as per the assumptions they have made to solve the problem.
The primary method which is generally used to this problem: | 1 | Applied and Interdisciplinary Chemistry |
These oxidize the hydrogen to water. Examples include:
* Nitric acid, used in the Grove cell and Bunsen cell
* Chromic acid, used in the Chromic acid cell
* Manganese dioxide, used in the Leclanché cell and Dry cell
Nitric and chromic acids are powerful oxidizing agents, and effective depolarizers, but their hazardous nature makes them unsuitable for general use. Manganese dioxide is, therefore, the most widely used depolarizer. | 0 | Theoretical and Fundamental Chemistry |
When a light isotope is replaced with a heavy isotope (e.g., C for C), the bond between the two atoms will vibrate more slowly, thereby lowering the zero-point energy of the bond and acting to stabilize the molecule. An isotopologue with a doubly substituted bond is therefore slightly more thermodynamically stable, which will tend to produce a higher abundance of the doubly substituted (or “clumped”) species than predicted by the statistical abundance of each heavy isotope (known as a stochastic distribution of isotopes). This effect increases in magnitude with decreasing temperature, so the abundance of the clumped species is related to the temperature at which the gas was formed or equilibrated. By measuring the abundance of the clumped species in standard gases formed in equilibrium at known temperatures, the thermometer can be calibrated and applied to samples with unknown abundances. | 0 | Theoretical and Fundamental Chemistry |
The path or series of states through which a system passes from an initial equilibrium state to a final equilibrium state and can be viewed graphically on a pressure-volume (P-V), pressure-temperature (P-T), and temperature-entropy (T-s) diagrams.
There are an infinite number of possible paths from an initial point to an end point in a process. In many cases the path matters, however, changes in the thermodynamic properties depend only on the initial and final states and not upon the path.
Consider a gas in cylinder with a free floating piston resting on top of a volume of gas at a temperature . If the gas is heated so that the temperature of the gas goes up to while the piston is allowed to rise to as in Figure 1, then the pressure is kept the same in this process due to the free floating piston being allowed to rise making the process an isobaric process or constant pressure process. This Process Path is a straight horizontal line from state one to state two on a P-V diagram.
It is often valuable to calculate the work done in a process. The work done in a process is the area beneath the process path on a P-V diagram. Figure 2 If the process is isobaric, then the work done on the piston is easily calculated. For example, if the gas expands slowly against the piston, the work done by the gas to raise the piston is the force F times the distance d. But the force is just the pressure P of the gas times the area A of the piston, F = PA. Thus
*W = Fd
*W = PAd
*W = P(V − V)
Now let’s say that the piston was not able to move smoothly within the cylinder due to static friction with the walls of the cylinder. Assuming that the temperature was increased slowly, you would find that the process path is not straight and no longer isobaric, but would instead undergo an isometric process till the force exceeded that of the frictional force and then would undergo an isothermal process back to an equilibrium state. This process would be repeated till the end state is reached. See figure 3. The work done on the piston in this case would be different due to the additional work required for the resistance of the friction. The work done due to friction would be the difference between the work done on these two process paths.
Many engineers neglect friction at first in order to generate a simplified model. For more accurate information, the height of the highest point, or the max pressure, to surpass the static friction would be proportional to the frictional coefficient and the slope going back down to the normal pressure would be the same as an isothermal process if the temperature was increased at a slow enough rate.
Another path in this process is an isometric process. This is a process where volume is held constant which shows as a vertical line on a P-V diagram. Figure 3 Since the piston is not moving during this process, there is not any work being done. | 0 | Theoretical and Fundamental Chemistry |
Butyrate is essential to host immune homeostasis. Although the role and importance of butyrate in the gut is not fully understood, many researchers argue that a depletion of butyrate-producing bacteria in patients with several vasculitic conditions is essential to the pathogenesis of these disorders. A depletion of butyrate in the gut is typically caused by an absence or depletion of butyrate-producing-bacteria (BPB). This depletion in BPB leads to microbial dysbiosis. This is characterized by an overall low biodiversity and a depletion of key butyrate-producing members. Butyrate is an essential microbial metabolite with a vital role as a modulator of proper immune function in the host. It has been shown that children lacking in BPB are more susceptible to allergic disease and Type 1 Diabetes. Butyrate is also reduced in a diet low in dietary fiber, which can induce inflammation and have other adverse affects insofar as these short-chain fatty acids activate PPAR-γ.
Butyrate exerts a key role for the maintenance of immune homeostasis both locally (in the gut) and systemically (via circulating butyrate). It has been shown to promote the differentiation of regulatory T cells. In particular, circulating butyrate prompts the generation of extrathymic regulatory T cells. The low-levels of butyrate in human subjects could favor reduced regulatory T cell-mediated control, thus promoting a powerful immuno-pathological T-cell response. On the other hand, gut butyrate has been reported to inhibit local pro-inflammatory cytokines. The absence or depletion of these BPB in the gut could therefore be a possible aide in the overly-active inflammatory response. Butyrate in the gut also protects the integrity of the intestinal epithelial barrier. Decreased butyrate levels therefore lead to a damaged or dysfunctional intestinal epithelial barrier.
In a 2013 research study conducted by Furusawa et al., microbe-derived butyrate was found to be essential in inducing the differentiation of colonic regulatory T cells in mice. This is of great importance and possibly relevant to the pathogenesis and vasculitis associated with many inflammatory diseases because regulatory T cells have a central role in the suppression of inflammatory and allergic responses. In several research studies, it has been demonstrated that butyrate induced the differentiation of regulatory T cells in vitro and in vivo. The anti-inflammatory capacity of butyrate has been extensively analyzed and supported by many studies. It has been found that microorganism-produced butyrate expedites the production of regulatory T cells, although the specific mechanism by which it does so unclear. More recently, it has been shown that butyrate plays an essential and direct role in modulating gene expression of cytotoxic T-cells. Butyrate also has an anti-inflammatory effect on neutrophils, reducing their migration to wounds. This effect is mediated via the receptor Hydroxycarboxylic acid receptor 1|
In the gut microbiomes found in the class Mammalia, omnivores and herbivores have butyrate-producing bacterial communities dominated by the butyryl-CoA:acetate CoA-transferase pathway, whereas carnivores have butyrate-producing bacterial communities dominated by the butyrate kinase pathway.
The odor of butyric acid, which emanates from the sebaceous follicles of all mammals, works on the tick as a signal. | 1 | Applied and Interdisciplinary Chemistry |
The spray head is one of the three new technologies that make "nano" spray drying possible.
A piezoelectric system precisely vibrates a fine mesh. Vibration produces fine droplets with a narrow size distribution. | 0 | Theoretical and Fundamental Chemistry |
Lichens are eaten by many different cultures across the world. Although some lichens are only eaten in times of famine, others are a staple food or even a delicacy. Two obstacles are often encountered when eating lichens: lichen polysaccharides are generally indigestible to humans, and lichens usually contain mildly toxic secondary compounds that should be removed before eating. Very few lichens are poisonous, but those high in vulpinic acid or usnic acid are toxic. Most poisonous lichens are yellow.
In the past, Iceland moss (Cetraria islandica) was an important source of food for humans in northern Europe, and was cooked as a bread, porridge, pudding, soup, or salad. Bryoria fremontii (edible horsehair lichen) was an important food in parts of North America, where it was usually pitcooked. Northern peoples in North America and Siberia traditionally eat the partially digested reindeer lichen (Cladina spp.) after they remove it from the rumen of caribou or reindeer that have been killed. Rock tripe (Umbilicaria spp. and Lasalia spp.) is a lichen that has frequently been used as an emergency food in North America, and one species, Umbilicaria esculenta, (iwatake in Japanese) is used in a variety of traditional Korean and Japanese foods. | 1 | Applied and Interdisciplinary Chemistry |
Herbivores have evolved cecums (or an abomasum in the case of ruminants). Ruminants have a fore-stomach with four chambers. These are the rumen, reticulum, omasum, and abomasum. In the first two chambers, the rumen and the reticulum, the food is mixed with saliva and separates into layers of solid and liquid material. Solids clump together to form the cud (or bolus). The cud is then regurgitated, chewed slowly to completely mix it with saliva and to break down the particle size.
Fibre, especially cellulose and hemi-cellulose, is primarily broken down into the volatile fatty acids, acetic acid, propionic acid and butyric acid in these chambers (the reticulo-rumen) by microbes: (bacteria, protozoa, and fungi). In the omasum, water and many of the inorganic mineral elements are absorbed into the blood stream.
The abomasum is the fourth and final stomach compartment in ruminants. It is a close equivalent of a monogastric stomach (e.g., those in humans or pigs), and digesta is processed here in much the same way. It serves primarily as a site for acid hydrolysis of microbial and dietary protein, preparing these protein sources for further digestion and absorption in the small intestine. Digesta is finally moved into the small intestine, where the digestion and absorption of nutrients occurs. Microbes produced in the reticulo-rumen are also digested in the small intestine. | 1 | Applied and Interdisciplinary Chemistry |
Characterization techniques for copolymers are similar to those for other polymeric materials. These techniques can be used to determine the average molecular weight, molecular size, chemical composition, molecular homogeneity, and physiochemical properties of the material. However, given that copolymers are made of base polymer components with heterogeneous properties, this may require multiple characterization techniques to accurately characterize these copolymers.
Spectroscopic techniques, such as nuclear magnetic resonance spectroscopy, infrared spectroscopy, and UV spectroscopy, are often used to identify the molecular structure and chemical composition of copolymers. In particular, NMR can indicate the tacticity and configuration of polymeric chains while IR can identify functional groups attached to the copolymer.
Scattering techniques, such as static light scattering, dynamic light scattering, and small-angle neutron scattering, can determine the molecular size and weight of the synthesized copolymer. Static light scattering and dynamic light scattering use light to determine the average molecular weight and behavior of the copolymer in solution whereas small-angle neutron scattering uses neutrons to determine the molecular weight and chain length. Additionally, x-ray scattering techniques, such as small-angle X-ray scattering (SAXS) can help determine the nanometer morphology and characteristic feature size of a microphase-separated block-copolymer or suspended micelles.
Differential scanning calorimetry is a thermoanalytical technique used to determine the thermal events of the copolymer as a function of temperature. It can indicate when the copolymer is undergoing a phase transition, such as crystallization or melting, by measuring the heat flow required to maintain the material and a reference at a constantly increasing temperature.
Thermogravimetric analysis is another thermoanalytical technique used to access the thermal stability of the copolymer as a function of temperature. This provides information on any changes to the physicochemical properties, such as phase transitions, thermal decompositions, and redox reactions.
Size-exclusion chromatography can separate copolymers with different molecular weights based on their hydrodynamic volume. From there, the molecular weight can be determined by deriving the relationship from its hydrodynamic volume. Larger copolymers tend to elute first as they do not interact with the column as much. The collected material is commonly detected by light scattering methods, a refractometer, or a viscometer to determine the concentration of the eluted copolymer. | 0 | Theoretical and Fundamental Chemistry |
Yeast fermentation of various carbohydrate products is also used to produce the ethanol that is added to gasoline.
The dominant ethanol feedstock in warmer regions is sugarcane. In temperate regions, corn or sugar beets are used.
In the United States, the main feedstock for the production of ethanol is currently corn. Approximately 2.8 gallons of ethanol are produced from one bushel of corn (0.42 liter per kilogram). While much of the corn turns into ethanol, some of the corn also yields by-products such as DDGS (distillers dried grains with solubles) that can be used as feed for livestock. A bushel of corn produces about 18 pounds of DDGS (320 kilograms of DDGS per metric ton of maize). Although most of the fermentation plants have been built in corn-producing regions, sorghum is also an important feedstock for ethanol production in the Plains states. Pearl millet is showing promise as an ethanol feedstock for the southeastern U.S. and the potential of duckweed is being studied.
In some parts of Europe, particularly France and Italy, grapes have become a de facto feedstock for fuel ethanol by the distillation of surplus wine. Surplus sugary drinks may also be used. In Japan, it has been proposed to use rice normally made into sake as an ethanol source. | 1 | Applied and Interdisciplinary Chemistry |
* [http://www.eanet.asia/ Acid Deposition Monitoring Program in East Asia (EANET)]
* [https://www.canada.ca/en/environment-climate-change/services/air-pollution/monitoring-networks-data/canadian-air-precipitation.html Canadian Air and Precipitation Monitoring Network (CAPMoN)]
* [https://www.epa.gov/castnet Clean Air Status and Trends Network (CASTNET)]
* [https://www.epa.gov/great-lakes-monitoring Great Lakes National Program Office (GLNPO)]
* [http://apmmn.org/About/ Asia-Pacific Mercury Monitoring Network (APMMN)] | 1 | Applied and Interdisciplinary Chemistry |
The primary mechanism of virokine interference with immune signaling is thought to be competitive inhibition of the binding of host signaling molecules to their target receptors. Virokines occupy binding sites on host receptors, thereby inhibiting access by signaling molecules. Viroceptors mimic host receptors and thus divert signaling molecules from finding their targets. Cytokine-binding proteins bind to and sequester cytokines, occluding the binding surface through which they interact with receptors. The effect is to attenuate and subvert host immune response. | 1 | Applied and Interdisciplinary Chemistry |
Irrotational flow occurs where the curl of the velocity of the fluid is zero everywhere. That is when
Similarly, if it is assumed that the fluid is incompressible:
Then, starting with the continuity equation:
The condition of incompressibility means that the time derivative of the density is 0, and that the density can be pulled out of the divergence, and divided out, thus leaving the continuity equation for an incompressible system:
Now, the Helmholtz decomposition can be used to write the velocity as the sum of the gradient of a scalar potential and as the curl of a vector potential. That is:
Note that imposing the condition that implies that
The curl of the gradient is always 0. Note that the curl of the curl of a function is only uniformly 0 for the vector potential being 0 itself. So, by the condition of irrotational flow:
And then using the continuity equation , the scalar potential can be substituted back in to find Laplace's Equation for irrotational flow:
Note that the Laplace equation is a well-studied linear partial differential equation. Its solutions are infinite; however, most solutions can be discarded when considering physical systems, as boundary conditions completely determine the velocity potential.
Examples of common boundary conditions include the velocity of the fluid, determined by , being 0 on the boundaries of the system.
There is a great amount of overlap with electromagnetism when solving this equation in general, as the Laplace equation also models the electrostatic potential in a vacuum.
There are many reasons to study irrotational flow, among them;
*Many real-world problems contain large regions of irrotational flow.
*It can be studied analytically.
*It shows us the importance of boundary layers and viscous forces.
*It provides us tools for studying concepts of lift and drag. | 1 | Applied and Interdisciplinary Chemistry |
Since it is accepted that ion suppression has the potential to affect the other analytical parameters of any assay, a prudent approach to any LC-MS method development should include an evaluation of ion-suppression. There are two accepted protocols by which this may be achieved, described as follows. | 0 | Theoretical and Fundamental Chemistry |
* Guttmann, Y.M. (1999). The Concept of Probability in Statistical Physics, Cambridge University Press, Cambridge UK, . | 0 | Theoretical and Fundamental Chemistry |
While photosystem II photolyzes water to obtain and energize new electrons, photosystem I simply reenergizes depleted electrons at the end of an electron transport chain. Normally, the reenergized electrons are taken by NADP, though sometimes they can flow back down more H-pumping electron transport chains to transport more hydrogen ions into the thylakoid space to generate more ATP. This is termed cyclic photophosphorylation because the electrons are recycled. Cyclic photophosphorylation is common in plants, which need more ATP than NADPH. | 0 | Theoretical and Fundamental Chemistry |
Grating-coupled interferometry (GCI) is a biophysical characterization method mainly used in biochemistry and drug discovery for label-free analysis of molecular interactions. Similar to other optical methods such as surface plasmon resonance (SPR) or bio-layer interferometry (BLI), it is based on measuring refractive index changes within an evanescent field near a sensor surface. After immobilizing a target to the sensor surface, analyte molecules in solution which bind to that target cause a small increase in local refractive index. By monitoring these refractive changes over time characteristics such as kinetic rates and affinity constants of the analyte-target binding, or analyte concentrations, can be determined. | 0 | Theoretical and Fundamental Chemistry |
Ninhydrin (2,2-dihydroxyindane-1,3-dione) is an organic compound with the formula CH(CO)C(OH). It is used to detect ammonia and amines. Upon reaction with these amines, ninhydrin gets converted into deep blue or purple derivatives, which are called Ruhemann's purple. Ninhydrin is most commonly used to detect fingerprints in forensic cases, as the terminal amines of lysine residues in peptides and proteins sloughed off in fingerprints react with ninhydrin.
Ninhydrin is a white solid that is soluble in ethanol and acetone. Ninhydrin can be considered as the hydrate of indane-1,2,3-trione. | 0 | Theoretical and Fundamental Chemistry |
Monoclonal antibodies are more expensive to manufacture than small molecules due to the complex processes involved and the general size of the molecules, all in addition to the enormous research and development costs involved in bringing a new chemical entity to patients. They are priced to enable manufacturers to recoup the typically large investment costs, and where there are no price controls, such as the United States, prices can be higher if they provide great value. Seven University of Pittsburgh researchers concluded, "The annual price of mAb therapies is about $100,000 higher in oncology and hematology than in other disease states", comparing them on a per patient basis, to those for cardiovascular or metabolic disorders, immunology, infectious diseases, allergy, and ophthalmology. | 1 | Applied and Interdisciplinary Chemistry |
A turbojet engine is a gas turbine engine that works by compressing air with an inlet and a compressor (axial, centrifugal, or both), mixing fuel with the compressed air, burning the mixture in the combustor, and then passing the hot, high pressure air through a turbine and a nozzle. The compressor is powered by the turbine, which extracts energy from the expanding gas passing through it. The engine converts internal energy in the fuel to increased momentum of the gas flowing through the engine, producing thrust. All the air entering the compressor is passed through the combustor, and turbine, unlike the turbofan engine described below. | 1 | Applied and Interdisciplinary Chemistry |
Hiyama received his Bachelor of Engineering (1969) and Master of Engineering (1971) from Kyoto University. He dropped out of the doctorate track in 1972, and subsequently started working as an assistant for Hitoshi Nozaki at Kyoto University. In 1975, he obtained his doctoral degree, and during 1975-1976 conducted postdoctoral research with Yoshito Kishi at Harvard University. In 1981, he started working at the Sagami Chemical Research Center, and became a principal investigator in 1983, and then chief laboratory manager in 1988.
In 1992, he re-entered the world of academia at the Tokyo Institute of Technology as a professor of the Research Laboratory of Resources Utilization. He then returned to Kyoto University in 1997 as a professor of engineering, until 2010 when he transferred to Chuo University, where he currently holds tenure.
His current research focuses on C-H activation and cross-coupling reactions. In particular, he is interested in ortho and benzylic C-H activation, and C-C, C-N, and C-Si bond formation via cross-coupling with organosilicon reagents.
In his spare time, he enjoys listening to classical music. His favorite way of spending a holiday is “cleaning [his] small garden by picking out weeds one by one”, which is “good psychological training for a Buddhist priest”. | 0 | Theoretical and Fundamental Chemistry |
Although biological filters have simple superficial structures, their internal hydrodynamics and the microorganisms' biology and ecology are complex and variable. These characteristics confer robustness to the process. In other words, the process has the capacity to maintain its performance or rapidly return to initial levels following a period of no flow, of intense use, toxic shocks, media backwash (high rate biofiltration processes), etc.
The structure of the biofilm protects microorganisms from difficult environmental conditions and retains the biomass inside the process, even when conditions are not optimal for its growth. Biofiltration processes offer the following advantages: (Rittmann et al., 1988):
* Since microorganisms are retained within the biofilm, biofiltration allows the development of microorganisms with relatively low specific growth rates;
* Biofilters are less subject to variable or intermittent loading and to hydraulic shock;
* Operational costs are usually lower than for activated sludge;
* The final treatment result is less influenced by biomass separation since the biomass concentration at the effluent is much lower than for suspended biomass processes;
* The attached biomass becomes more specialized (higher concentration of relevant organisms) at a given point in the process train because there is no biomass return. | 1 | Applied and Interdisciplinary Chemistry |
A receptor modulator, or receptor ligand, is a general term for a substance, endogenous or exogenous, that binds to and regulates the activity of chemical receptors. They are ligands that can act on different parts of receptors and regulate activity in a positive, negative, or neutral direction with varying degrees of efficacy. Categories of these modulators include receptor agonists and receptor antagonists, as well as receptor partial agonists, inverse agonists, orthosteric modulators, and allosteric modulators, Examples of receptor modulators in modern medicine include CFTR modulators, selective androgen receptor modulators (SARMs), and muscarinic ACh receptor modulators. | 1 | Applied and Interdisciplinary Chemistry |
), functioning as a hexadentate [[ligand]] -->
18-Crown-6 has a high affinity for the hydronium ion HO, as it can fit inside the crown ether. Thus, reaction of 18-crown-6 with strong acids gives the cation . For example, interaction of 18-crown-6 with HCl gas in toluene with a little moisture gives an ionic liquid layer with the composition , from which the solid can be isolated on standing. Reaction of the ionic liquid layer with two molar equivalents of water gives the crystalline product . | 0 | Theoretical and Fundamental Chemistry |
* Beiträge Zur Chemischen Kenntniss Der Mineralkörper . Vol. 1–5 . Rottmann, Berlin 1795–1810 [http://nbn-resolving.de/urn:nbn:de:hbz:061:2-11600 Digital edition] by the University and State Library Düsseldorf
* Chemisches Wörterbuch . Vol. 1–9 . Voss, Berlin 1807–1819 [http://nbn-resolving.de/urn:nbn:de:hbz:061:2-28821 Digital edition] by the University and State Library Düsseldorf
* Chemische Abhandlungen gemischten Inhalts . Nicolai, Berlin [u. a.] 1815 [http://nbn-resolving.de/urn:nbn:de:hbz:061:2-9305 Digital edition] by the University and State Library Düsseldorf | 1 | Applied and Interdisciplinary Chemistry |
The March 11, 2011, Tōhoku earthquake and tsunami caused various nuclear accidents, the worst of which was the Fukushima Daiichi nuclear disaster. At an estimated eighty minutes after the tsunami strike, the temperatures inside Unit 1 of the Fukushima Daiichi Nuclear Power Plant reached over 2,300 ˚C, causing the fuel assembly structures, control rods and nuclear fuel to melt and form corium. (The physical nature of the damaged fuel has not been fully determined but it is assumed to have become molten.) The reactor core isolation cooling system (RCIC) was successfully activated for Unit 3; the Unit 3 RCIC subsequently failed, however, and at about 09:00 on March 13, the nuclear fuel had melted into corium. Unit 2 retained RCIC functions slightly longer and corium is not believed to have started to pool on the reactor floor until around 18:00 on March 14. TEPCO believes the fuel assembly fell out of the pressure vessel to the floor of the primary containment vessel, and that it has found fuel debris on the floor of the primary containment vessel. | 0 | Theoretical and Fundamental Chemistry |
HABs occur naturally off coasts all over the world. Marine dinoflagellates produce ichthyotoxins. Where HABs occur, dead fish wash up on shore for up to two weeks after a HAB has been through the area. In addition to killing fish, the toxic algae contaminate shellfish. Some mollusks are not susceptible to the toxin, and store it in their fatty tissues. By consuming the organisms responsible for HABs, shellfish can accumulate and retain saxitoxin produced by these organisms. Saxitoxin blocks sodium channels and ingestion can cause paralysis within 30 minutes.
In addition to directly harming marine animals and vegetation loss, harmful algal blooms can also lead to ocean acidification, which occurs when the amount of carbon dioxide in the water is increased to unnatural levels. Ocean acidification slows the growth of certain species of fish and shellfish, and even prevents shell formation in certain species of mollusks. These subtle, small changes can add up over time to cause chain reactions and devastating effects on whole marine ecosystems.
Other animals that eat exposed shellfish are susceptible to the neurotoxin, which may lead to neurotoxic shellfish poisoning and sometimes even death. Most mollusks and clams filter feed, which results in higher concentrations of the toxin than just drinking the water. Scaup, for example, are diving ducks whose diet mainly consists of mollusks. When scaup eat the filter-feeding shellfish that have accumulated high levels of the HAB toxin, their population becomes a prime target for poisoning. However, even birds that do not eat mollusks can be affected by simply eating dead fish on the beach or drinking the water.
The toxins released by the blooms can kill marine animals including dolphins, sea turtles, birds, and manatees. The Florida Manatee, a subspecies of the West Indian Manatee, is a species often impacted by red tide blooms. Florida manatees are often exposed to the poisonous red-tide toxins either by consumption or inhalation. There are many small barnacles, crustaceans, and other [https://edis.ifas.ufl.edu/publication/SG188 epiphytes] that grow on the blades of seagrass. These tiny creatures filter particles from the water around them and use these particles as their main food source. During red tide blooms, they also filter the toxic red tide cells from the water, which then becomes concentrated inside them. Although these toxins do not harm epiphytes, they are extremely poisonous to marine creatures who consume (or accidentally consume) the exposed epiphytes, such as manatees. When manatees unknowingly consume exposed epiphytes while grazing on sea grass, the toxins are subsequently released from the epiphytes and ingested by the manatees. In addition to consumption, manatees may also become exposed to air-borne Brevetoxins released from harmful red-tide cells when passing through algal blooms.
Manatees also have an immunoresponse to HABs and their toxins that can make them even more susceptible to other stressors. Due to this susceptibility, manatees can die from either the immediate, or the after effects of the HAB. In addition to causing manatee mortalities, red-tide exposure also causes severe [https://www.researchgate.net/publication/271274562_Sublethal_red_tide_toxin_exposure_in_free-ranging_manatees_Trichechus_manatus_affects_the_immune_system_through_reduced_lymphocyte_proliferation_responses_inflammation_and_oxidative_stress sublethal health problems among Florida manatee populations]. Studies have shown that red-tide exposure among free-ranging Florida manatees has been shown to negatively impact immune functioning by causing increased inflammation, a reduction in lymphocyte proliferation responses, and oxidative stress.
Fish such as Atlantic herring, American pollock, winter flounder, Atlantic salmon, and cod were dosed orally with these toxins in an experiment, and within minutes the subjects started to exhibit a loss of equilibrium and began to swim in an irregular, jerking pattern, followed by paralysis and shallow, arrhythmic breathing and eventually death, after about an hour. HABs have been shown to have a negative effect also in the memory functions of sea lions. | 0 | Theoretical and Fundamental Chemistry |
RNA therapeutics are a new class of medications based on ribonucleic acid (RNA). Research has been working on clinical use since the 1990s, with significant success in cancer therapy in the early 2010s. In 2020 and 2021, mRNA vaccines have been developed globally for use in combating the coronavirus disease (COVID-19 pandemic). The Pfizer–BioNTech COVID-19 vaccine was the first mRNA vaccine approved by a medicines regulator, followed by the Moderna COVID-19 vaccine, and others.
The main types of RNA therapeutics are those based on messenger RNA (mRNA), antisense RNA (asRNA), RNA interference (RNAi), and RNA aptamers. Of the four types, mRNA-based therapy is the only type which is based on triggering synthesis of proteins within cells, making it particularly useful in vaccine development. Antisense RNA is complementary to coding mRNA and is used to trigger mRNA inactivation to prevent the mRNA from being used in protein translation. RNAi-based systems use a similar mechanism, and involve the use of both small interfering RNA (siRNA) and micro RNA (miRNA) to prevent mRNA translation and/or degrade mRNA. However, RNA aptamers are short, single stranded RNA molecules produced by directed evolution to bind to a variety of biomolecular targets with high affinity thereby affecting their normal in vivo activity.
RNA is synthesized from template DNA by RNA polymerase with messenger RNA (mRNA) serving as the intermediary biomolecule between DNA expression and protein translation. Because of its unique properties (such as its typically single-stranded nature and its 2' OH group) and its ability to adopt many different secondary/tertiary structures, both coding and noncoding RNAs have attracted attention in medicine. Research has begun to explore RNAs potential to be used for therapeutic benefit, and unique challenges have occurred during drug discovery and implementation of RNA therapeutics. | 1 | Applied and Interdisciplinary Chemistry |
In 2011, global spending on prescription drugs topped $954 billion, even as growth slowed somewhat in Europe and North America. The United States accounts for more than a third of the global pharmaceutical market, with $340 billion in annual sales followed by the EU and Japan. Emerging markets such as China, Russia, South Korea and Mexico outpaced that market, growing a huge 81 percent.
The top ten best-selling drugs of 2013 totaled $75.6 billion in sales, with the anti-inflammatory drug Humira being the best-selling drug worldwide at $10.7 billion in sales. The second and third best selling were Enbrel and Remicade, respectively. The top three best-selling drugs in the United States in 2013 were Abilify ($6.3 billion,) Nexium ($6 billion) and Humira ($5.4 billion). The best-selling drug ever, Lipitor, averaged $13 billion annually and netted $141 billion total over its lifetime before Pfizer's patent expired in November 2011.
IMS Health publishes an analysis of trends expected in the pharmaceutical industry in 2007, including increasing profits in most sectors despite loss of some patents, and new blockbuster drugs on the horizon. | 1 | Applied and Interdisciplinary Chemistry |
To apply the strategy, a high-molecular-weight DNA strand is sheared into random fragments, size-selected (usually 2, 10, 50, and 150 kb), and cloned into an appropriate vector. The clones are then sequenced from both ends using the chain termination method yielding two short sequences. Each sequence is called an end-read or read 1 and read 2 and two reads from the same clone are referred to as mate pairs. Since the chain termination method usually can only produce reads between 500 and 1000 bases long, in all but the smallest clones, mate pairs will rarely overlap. | 1 | Applied and Interdisciplinary Chemistry |
Macro-scale biological processes, such as the spread of virus infections, can be followed using GFP labeling. In the past, mutagenic ultra violet light (UV) has been used to illuminate living organisms (e.g., see) to detect and photograph the GFP expression. Recently, a technique using non-mutagenic LED lights have been developed for macro-photography. The technique uses an epifluorescence camera attachment based on the same principle used in the construction of epifluorescence microscopes. | 1 | Applied and Interdisciplinary Chemistry |
The rudder consists of a pair of slightly conical (usually but not always - designs vary), semi-cones mounted on a pivot either side of the propeller with the long axis of the cone running fore and aft when the helm is midships. They are pivoted about a vertical axis such that the cone may close off the propeller thrust aft of the propeller, directing the thrust forwards and thus creating motion astern.
In addition to the "jaws" of the cone being controlled the direction of thrust is also controlled by rudder direction. In this way, it is unlike the azimuth thrusters used on many medium and large vessels, or the outboard motors or stern drives used by some small boats, since these all use the directed thrust to avoid the need of a rudder altogether.
Modern equivalent include certain types of pump jets or Kort nozzle.
While not strictly Kitchen rudder technology, the "bucket" on some aircraft jet engines is an aeronautical derivative of the device. When the deflectors are deployed, directing thrust forwards, they are equivalent to the Kitchen rudder in the "full astern" position. | 1 | Applied and Interdisciplinary Chemistry |
In coal-fired processes, part of the fuel is first burnt to heat the charge. The product of this combustion is CO. When the temperature reaches 1,000 °C, the CO reacts with the unburned carbon to create CO:
The production of H cannot be achieved by the thermal decomposition of water, as the temperatures involved are too low. Hydrogen is in fact produced along with carbon monoxide by the reaction:
These two reducing gas production reactions, which consume 172.45 and 131.4 kJ/mol respectively, are highly endothermic and operate by limiting charge heating. | 1 | Applied and Interdisciplinary Chemistry |
In the synthesis of spirotryprostatin B, an azomethine ylide is formed from condensation of an amine with an aldehyde. The ylide then reacts with an electron-deficient alkene on an indolinone, resulting in formation of a spirocyclic pyrrolidine and four contiguous stereocenters. | 0 | Theoretical and Fundamental Chemistry |
Neurofurans are 22-carbon compounds formed nonenzymatically by free radical mediated peroxidation of docosahexaenoic acid (DHA), an ω-3 essential fatty acid. The neurofurans are similar to the isofurans and are formed under similar conditions of oxidative stress, containing a substituted tetrahydrofuran ring. Measurement of the neurofurans may ultimately prove useful in diagnosis, timing, and selection of dosages in the treatment and chemoprevention of neurodegenerative disease. | 1 | Applied and Interdisciplinary Chemistry |
Scheele achieved astonishingly prolific and important results without the expensive laboratory equipment to which his Parisian contemporary Antoine Lavoisier was accustomed. Through the studies of Lavoisier, Priestley, Scheele, and others, chemistry was made a standardized field with consistent procedures. Although Scheele was unable to grasp the significance of his discovery of the substance that Lavoisier later named oxygen, his work was essential for the abandonment of the long-held theory of phlogiston.
Scheeles study of the gas not yet named oxygen was prompted by a complaint by Torbern Olof Bergman, a professor at Uppsala University who would eventually become Scheeles friend. Bergman informed Scheele that the saltpeter he had purchased from Scheeles employer, after long heating, produced red vapors (now known to be nitrogen dioxide) when it came into contact with acetic acid. Scheeles quick explanation was that the saltpeter had absorbed phlogiston with the heat (had been reduced to nitrite, in modern terms) and gave off a new phlogisticated gas as an active principle when combined with an acid (even a weak acid).
Bergman next suggested that Scheele analyze the properties of manganese(IV) oxide. It was through his studies of manganese(IV) oxide that Scheele developed his concept of "fire air" (his name for oxygen). He ultimately obtained oxygen by heating mercuric oxide, silver carbonate, magnesium nitrate, and other nitrate salts. Scheele wrote about his findings to Lavoisier who was able to see the significance of the results. His discovery of oxygen (ca. 1771) was chronologically earlier than the corresponding work of Priestley and Lavoisier, but he did not publish this discovery until 1777, after both of his rivals had published.
Although Scheele would always believe in some form of the phlogiston theory, his work reduced phlogiston to an unusually simple form, complicated only by the fact that chemists of Scheele's day still believed that light and heat were elements and were to be found in combination with them. Thus, Scheele assumed that hydrogen was composed of phlogiston (a reducing principle lost when objects were burned) plus heat. Scheele speculated that his fire air or oxygen (which he found the active part of air, estimating it to compose one quarter of air) combined with the phlogiston in objects to produce either light or heat (light and heat were presumed to be composed of differing proportions of phlogiston and oxygen).
When other chemists later showed water is produced when burning hydrogen and that rusting of metals added weight to them and that passing water over hot iron gave hydrogen, Scheele modified his theory to suggest that oxygen was the salt (or "saline principle" of water), and that when added to iron, water was reproduced, which added weight to the iron as rust. | 1 | Applied and Interdisciplinary Chemistry |
Lubricity is the measure of the reduction in friction and/or wear by a lubricant. The study of lubrication and wear mechanisms is called tribology. | 1 | Applied and Interdisciplinary Chemistry |
When dealing with gases, fugacity, f, is used rather than activity. However, whereas activity is dimensionless, fugacity has the dimension of pressure. A consequence is that chemical potential has to be defined in terms of a standard pressure, p</sup>:
By convention p</sup> is usually taken to be 1 bar.
Fugacity can be expressed as the product of partial pressure, p, and a fugacity coefficient, Φ:
Fugacity coefficients are dimensionless and can be obtained experimentally at specific temperature and pressure, from measurements of deviations from ideal gas behaviour. Equilibrium constants are defined in terms of fugacity. If the gases are at sufficiently low pressure that they behave as ideal gases, the equilibrium constant can be defined as a quotient of partial pressures.
An example of gas-phase equilibrium is provided by the Haber–Bosch process of ammonia synthesis.
:N + 3 H 2 NH;
This reaction is strongly exothermic, so the equilibrium constant decreases with temperature. However, a temperature of around 400 °C is required in order to achieve a reasonable rate of reaction with currently available catalysts. Formation of ammonia is also favoured by high pressure, as the volume decreases when the reaction takes place. The same reaction, nitrogen fixation, occurs at ambient temperatures in nature, when the catalyst is an enzyme such as nitrogenase. Much energy is needed initially to break the nitrogen–nitrogen triple bond even though the overall reaction is exothermic.
Gas-phase equilibria occur during combustion and were studied as early as 1943 in connection with the development of the V2 rocket engine.
The calculation of composition for a gaseous equilibrium at constant pressure is often carried out using ΔG values, rather than equilibrium constants. | 0 | Theoretical and Fundamental Chemistry |
Luciferins are a class of small-molecule substrates that react with oxygen in the presence of a luciferase (an enzyme) to release energy in the form of light. It is not known just how many types of luciferins there are, but some of the better-studied compounds are listed below.
Because of the chemical diversity of luciferins, there is no clear unifying mechanism of action, except that all require molecular oxygen, The variety of luciferins and luciferases, their diverse reaction mechanisms and the scattered phylogenetic distribution indicate that many of them have arisen independently in the course of evolution. | 1 | Applied and Interdisciplinary Chemistry |
Viscosity, a physical property, is a measure of how well adjacent molecules stick to one another. A solid can withstand a shearing force due to the strength of these sticky intermolecular forces. A fluid will continuously deform when subjected to a similar load. While a gas has a lower value of viscosity than a liquid, it is still an observable property. If gases had no viscosity, then they would not stick to the surface of a wing and form a boundary layer. A study of the delta wing in the Schlieren image reveals that the gas particles stick to one another (see Boundary layer section). | 0 | Theoretical and Fundamental Chemistry |
* Effects of Pyrazinamide on Fatty Acid Synthesis by Whole Mycobacterial Cells and Purified Fatty Acid Synthase I. Helena I. Boshoff, Valerie Mizrahi, Clifton E. Barry. Journal of Bacteriology, 2002
* The impact of drug resistance on Mycobacterium tuberculosis physiology: what can we learn from rifampicin?. Anastasia Koch, Valerie Mizrahi, Digby F Warner. Emerging Microbes & Infections, 2014 | 1 | Applied and Interdisciplinary Chemistry |
A stationary normal shock wave is classified as going in the normal direction of the flow direction. For example, when a piston moves at a constant rate inside a tube, sound waves that travel down the tube are produced. As the piston continues to move, the wave begins to come together and compresses the gas inside the tube. The various calculations that come alongside of normal shock waves can vary due to the size of the tubes in which they are contained. Abnormalities such as converging-diverging nozzles and tubes with changing areas can affect such calculations as volume, pressure, and Mach number. | 1 | Applied and Interdisciplinary Chemistry |
The study of beta decay provided the first physical evidence for the existence of the neutrino. In both alpha and gamma decay, the resulting alpha or gamma particle has a narrow energy distribution, since the particle carries the energy from the difference between the initial and final nuclear states. However, the kinetic energy distribution, or spectrum, of beta particles measured by Lise Meitner and Otto Hahn in 1911 and by Jean Danysz in 1913 showed multiple lines on a diffuse background. These measurements offered the first hint that beta particles have a continuous spectrum. In 1914, James Chadwick used a magnetic spectrometer with one of Hans Geiger's new counters to make more accurate measurements which showed that the spectrum was continuous. The distribution of beta particle energies was in apparent contradiction to the law of conservation of energy. If beta decay were simply electron emission as assumed at the time, then the energy of the emitted electron should have a particular, well-defined value. For beta decay, however, the observed broad distribution of energies suggested that energy is lost in the beta decay process. This spectrum was puzzling for many years.
A second problem is related to the conservation of angular momentum. Molecular band spectra showed that the nuclear spin of nitrogen-14 is 1 (i.e., equal to the reduced Planck constant) and more generally that the spin is integral for nuclei of even mass number and half-integral for nuclei of odd mass number. This was later explained by the proton-neutron model of the nucleus. Beta decay leaves the mass number unchanged, so the change of nuclear spin must be an integer. However, the electron spin is 1/2, hence angular momentum would not be conserved if beta decay were simply electron emission.
From 1920 to 1927, Charles Drummond Ellis (along with Chadwick and colleagues) further established that the beta decay spectrum is continuous. In 1933, Ellis and Nevill Mott obtained strong evidence that the beta spectrum has an effective upper bound in energy. Niels Bohr had suggested that the beta spectrum could be explained if conservation of energy was true only in a statistical sense, thus this principle might be violated in any given decay. However, the upper bound in beta energies determined by Ellis and Mott ruled out that notion. Now, the problem of how to account for the variability of energy in known beta decay products, as well as for conservation of momentum and angular momentum in the process, became acute.
In a famous letter written in 1930, Wolfgang Pauli attempted to resolve the beta-particle energy conundrum by suggesting that, in addition to electrons and protons, atomic nuclei also contained an extremely light neutral particle, which he called the neutron. He suggested that this "neutron" was also emitted during beta decay (thus accounting for the known missing energy, momentum, and angular momentum), but it had simply not yet been observed. In 1931, Enrico Fermi renamed Paulis "neutron" the "neutrino" (little neutral one' in Italian). In 1933, Fermi published his landmark theory for beta decay, where he applied the principles of quantum mechanics to matter particles, supposing that they can be created and annihilated, just as the light quanta in atomic transitions. Thus, according to Fermi, neutrinos are created in the beta-decay process, rather than contained in the nucleus; the same happens to electrons. The neutrino interaction with matter was so weak that detecting it proved a severe experimental challenge. Further indirect evidence of the existence of the neutrino was obtained by observing the recoil of nuclei that emitted such a particle after absorbing an electron. Neutrinos were finally detected directly in 1956 by the American physicists Clyde Cowan and Frederick Reines in the Cowan–Reines neutrino experiment. The properties of neutrinos were (with a few minor modifications) as predicted by Pauli and Fermi. | 0 | Theoretical and Fundamental Chemistry |
While the AnMBR has not been applied at anindustrial scale yet, there are a few companies that produce the technology and are marketing it as a viable alternative to current wastewater treatment technologies. Two prominent companies who are marketing the AnMBR system are Aquatech and Evoqua. Currently, Aquatech produces the external AnMBR configuration while Evoqua produces the submerged AnMBR configuration. | 1 | Applied and Interdisciplinary Chemistry |
When foods with a high glycemic index are consumed, the carbohydrates in the food are more easily digested than low glycemic index foods. Hence, more glucose is available for absorption. It should not be misunderstood that glucose is absorbed more rapidly because, once formed, glucose is absorbed at the same rate. It is only available in higher amounts due to the ease of digestion of high glycemic index foods. In individuals with normal carbohydrate metabolism, insulin levels rise concordantly to drive glucose into the body's tissues and maintain blood glucose levels in the normal range. Insulin stimulates the uptake of valine, leucine, and isoleucine into skeletal muscle, but not uptake of tryptophan. This lowers the ratio of these branched-chain amino acids in the bloodstream relative to tryptophan (an aromatic amino acid), making tryptophan preferentially available to the large neutral amino acid transporter at the blood–brain barrier. Uptake of tryptophan by the brain thus increases. In the brain, tryptophan is converted to serotonin, which is then converted to melatonin. Increased brain serotonin and melatonin levels result in sleepiness. | 1 | Applied and Interdisciplinary Chemistry |
Vienna Standard Mean Ocean Water (VSMOW) is an isotopic standard for water, that is, a particular sample of water whose proportions of different isotopes of hydrogen and oxygen are accurately known. VSMOW is distilled from ocean water and does not contain salt or other impurities. Published and distributed by the Vienna-based International Atomic Energy Agency in 1968, the standard and its essentially identical successor, VSMOW2, continue to be used as a reference material.
Water samples made up of different isotopes of hydrogen and oxygen have slightly different physical properties. As an extreme example, heavy water, which contains two deuterium (H) atoms instead of the usual, lighter hydrogen-1 (H), has a melting point of and boiling point of . Different rates of evaporation cause water samples from different places in the water cycle to contain slightly different ratios of isotopes. Ocean water (richer in heavy isotopes) and rain water (poorer in heavy isotopes) roughly represent the two extremes found on Earth. With VSMOW, the IAEA simultaneously published an analogous standard for rain water, Standard Light Antarctic Precipitation (SLAP), and eventually its successor SLAP2. SLAP contains about 5% less oxygen-18 and 42.8% less deuterium than VSMOW.
A scale based on VSMOW and SLAP is used to report oxygen-18 and deuterium concentrations. From 2005 until its redefinition in 2019, the kelvin was specified to be of the temperature of specifically VSMOW at its triple point. | 0 | Theoretical and Fundamental Chemistry |
Abortive initiation, also known as abortive transcription, is an early process of genetic transcription in which RNA polymerase binds to a DNA promoter and enters into cycles of synthesis of short mRNA transcripts which are released before the transcription complex leaves the promoter. This process occurs in both eukaryotes and prokaryotes. Abortive initiation is typically studied in the T3 and T7 RNA polymerases in bacteriophages and in E. coli. | 1 | Applied and Interdisciplinary Chemistry |
Sequencing depth inconsistencies on open chromatin regions and signals derived from up/downstream orientation-sensitive sequencing read densities, this method infers the tissue of origin of the cfDNA fragments obtained from bisulfite sequencing. The method uses a mathematical formulation to generate signals for orientation-aware cfDNA fragmentation based on the empirical peak periods and positions of up/downstream ends of the reads. The method shown to be useful for inferring the tissue-of-origin, pregnancy identification, cancer detection, and transplant monitoring. This method also provides information on which tissue-of-origin contributes how much to cfDNA reads. | 1 | Applied and Interdisciplinary Chemistry |
Plantations typically consisted of a nearly self-sufficient community, including the head iron master, workers and their families, and other shopkeepers, blacksmiths, and agricultural workers needed to sustain mining and smelting operations as well as life on the plantation. Plantations were foremost land-intensive operations, commonly comprising thousands of acres. The grounds were typically defined by a conspicuous mansion, belonging to the iron master, which looked out on the charcoal furnace or iron forge from atop a geographically higher location.
The iron master was also in charge of hiring skilled labor and investing capital in construction and maintenance of charcoal furnaces and forges for the refining and working of iron. Workers on the plantation were often not paid directly in wages. Rather, the master tallied an employee’s earnings on a balance sheet, which he then offset with purchases of merchandise from the community’s stores. While an iron master lived a rather luxurious life with the opportunity to afford travel, tutors for his children, and expensive home furnishings, workers had few material possessions of their own. Workers were not well traveled outside of the plantations, and little news outside of the confines of the plantation concerned their daily lives. Notably, however, poverty was not well known on the plantations, even in times of economic depression, and workers’ wages in the United States greatly surpassed comparable wages in the European iron industry.
Work forces on iron plantations consisted of a wide array of labor and included indentured servants, slaves, and free laborers. Indentured servants composed the largest group. Indentured servants and slaves typically performed the least skilled tasks on plantations, serving as woodcutters to supply the charcoal furnaces or as miners to dig iron ore. Few opportunities were afforded to laborers for upwards mobility on plantations.
More efficient fossil fuels eventually substituted for wood-based charcoal, and “the semi-feudal iron plantation was replaced by the urban establishment and the company town” typically possessing a coke furnace.
The lack of nearby ore deposits additionally limited many plantations from being able to economically transport large quantities of ore over long distances to be smelted on the plantations themselves. Wagon transport of bar and pig iron to cities further added to costs and could run as high as forty percent of the market price per ton of pig iron in 1728, according to John Potts, a member of an iron plantation in Pennsylvania.
Iron plantations in Alabama, Tennessee, Georgia, Michigan, Wisconsin, and Missouri in particular better survived the evolving technological landscape by adopting practices that increased charcoal energy efficiency, that is, the amount of charcoal consumed per ton of iron smelted. One such technique was to raise the heights of furnaces to create a longer and more uniform reaction chamber to produce more homogeneous pig iron. Whereas antebellum furnaces were built with brick and mortar and reached only 30-35 feet in height, new furnaces remodeled in the 1840s reached as high as 65 feet. Continued demand for pig iron to be transported westward provided an additional competitive advantage to plantations in these states.
The iron industry shifted to one largely determined by the production of steel during the British Industrial Revolution and in the later half of the 19th and early 20th centuries. As such, blast furnaces, steam and electric power, and coke fuel replaced the largely land- and labor-intensive practices of iron making on plantations dependent on large tracts of land to produce charcoal and additional labor to sustain both the iron making operations and the community at large. Though iron produced on plantations remained practically useful for Westward Expansion, the eastern United States and Europe increasingly demanded more pliable and resistant steel for use in buildings, ships, engines, and railroads. Though demand still remained for pig iron as an ingredient in steel production, most iron plantations were no longer economically competitive with coke-powered smelters which located themselves increasingly closer to the major cities requiring their products. | 1 | Applied and Interdisciplinary Chemistry |
In organofluorine chemistry, many perfluorinated compounds are prepared by electrochemical synthesis, which is conducted in liquid HF at voltages near 5–6 V using Ni anodes. The method was invented in the 1930s. Amines, alcohols, carboxylic acids, and sulfonic acids are converted to perfluorinated derivatives using this technology. A solution or suspension of the hydrocarbon in hydrogen fluoride is electrolyzed at 5–6 V to produce high yields of the perfluorinated product. | 0 | Theoretical and Fundamental Chemistry |
Most importantly, with the sequential order rules, also referred to as Nodas rules', the sequence of the intensity changes can be determined. By carefully interpreting the signs of the 2D synchronous and asynchronous cross peaks with the following rules, the sequence of spectral events during the experiment can be determined:
#if the intensities of the bands at x and y in the dataset are changing in the same direction, the synchronous 2D cross peak at (x,y) is positive
#if the intensities of the bands at x and y in the dataset are changing in the opposite direction, the synchronous 2D cross peak at (x,y) is negative
#if the change at x mainly precedes the change in the band at y, the asynchronous 2D cross peak at (x,y) is positive
#if the change at x mainly follows the change in the band at y, the asynchronous 2D cross peak at (x,y) is negative
#if the synchronous 2D cross peak at (x,y) is negative, the interpretation of rule 3 and 4 for the asynchronous 2D peak at (x,y) has to be reversed
:where x and y are the positions on the x-xaxis of two bands in the original data that are subject to intensity changes.
Following the rules above. It can be derived that the changes at 10 and 30 occur simultaneously and the changes in intensity at 20 and 40 occur simultaneously as well. Because of the positive asynchronous cross-peak at (10, 20), the changes at 10 and 30 (predominantly) occur before the intensity changes at 20 and 40.
In some cases the Noda rules cannot be so readily implied, predominately when spectral features are not caused by simple intensity variations. This may occur when band shifts occur, or when a very erratic intensity variation is present in a given frequency range. | 0 | Theoretical and Fundamental Chemistry |
Class B foams are designed for class B fires—flammable liquids. The use of class A foam on a class B fire may yield unexpected results, as class A foams are not designed to contain the explosive vapours produced by flammable liquids. Class B foams have two major subtypes. | 0 | Theoretical and Fundamental Chemistry |
This table (Figure 2) lists the correlation coefficients between the experimentally observed backbone chemical shifts and the calculated/predicted backbone shifts for different chemical shift predictors using an identical test set of 61 test proteins. | 0 | Theoretical and Fundamental Chemistry |
The Bancroft rule in colloidal chemistry states: "The phase in which an emulsifier is more soluble constitutes the continuous phase." This means that water-soluble surfactants tend to give oil-in-water emulsions and oil-soluble surfactants give water-in-oil emulsions. It is a general rule of thumb, still used, but regarded as inferior to HLD theory (Hydrophilic Lipophilic Difference), which takes many more factors into consideration.
It was named after Wilder Dwight Bancroft, an American physical chemist, who proposed the rule in the 1910s. | 0 | Theoretical and Fundamental Chemistry |
RNase cleavage of the last six nucleotides is the next step following the ligation, ultimately extending the primer strand by a single base. Such cleavage allows rezipping of 6 nucleotides of the hairpin, signaled by a decrease in hairpin length of ~4 nm. Therefore, an incorporation of a complementary nucleotide is indicated by an increase in 7 nucleotides (+5 nm) followed by a decrease in 6 nucleotides (-4 nm). | 1 | Applied and Interdisciplinary Chemistry |
Phenols undergo esterification. Phenol esters are active esters, being prone to hydrolysis. Phenols are reactive species toward oxidation. Oxidative cleavage, for instance cleavage of 1,2-dihydroxybenzene to the monomethylester of 2,4 hexadienedioic acid with oxygen, copper chloride in pyridine Oxidative de-aromatization to quinones also known as the Teuber reaction. and oxone. In reaction depicted below 3,4,5-trimethylphenol reacts with singlet oxygen generated from oxone/sodium carbonate in an acetonitrile/water mixture to a para-peroxyquinole. This hydroperoxide is reduced to the quinole with sodium thiosulfate.
Phenols are oxidized to hydroquinones in the Elbs persulfate oxidation.
Reaction of naphtols and hydrazines and sodium bisulfite in the Bucherer carbazole synthesis. | 0 | Theoretical and Fundamental Chemistry |
In Kenya, a number of cases have been reported in the 2010s of thieves selling transformer oil, stolen from electric transformers, to the operators of roadside food stalls for use in deep frying. When used for frying, it is reported that transformer oil lasts much longer than regular cooking oil. The downside of this misuse of the transformer oil is the threat to the health of the consumers, due to the presence of PCBs. | 1 | Applied and Interdisciplinary Chemistry |
Roasting is a process of oxidizing zinc sulfide concentrates at high temperatures into an impure zinc oxide, called "Zinc Calcine". The chemical reactions that take place are as follows:
Approximately 90% of zinc in concentrates are oxidized to zinc oxide. However, at the roasting temperatures around 10% of the zinc reacts with the iron impurities of the zinc sulfide concentrates to form zinc ferrite. A byproduct of roasting is sulfur dioxide, which is further processed into sulfuric acid, a commodity. The linked refinery flow sheet shows a schematic of Noranda's eastern Canadian zinc roasting operation
The process of roasting varies based on the type of roaster used. There are three types of roasters: multiple-hearth, suspension, and fluidized-bed. | 1 | Applied and Interdisciplinary Chemistry |
Neuroepithelial cells (NEC) are thought to be neuron-like chemoreceptor cells because they rely on membrane potential changes for the release of neurotransmitters and signal transmission onto nearby cells. Once NEC of the zebrafish gills come in contact with either environmental or aortic hypoxia, an outward K "leak" channel is inhibited. It remains unclear how these K channels are inhibited by a shortage of oxygen because there are yet to be any known direct binding sites for "a lack of oxygen", only whole cell and ion channel responses to hypoxia. K "leak" channels are two-pore-domain ion channels that are open at the resting membrane potential of the cell and play a major role in setting the equilibrium resting membrane potential of the cell. Once this "leak" channel is closed, the K is no longer able to freely flow out of the cell, and the membrane potential of the NEC increases; the cell becomes depolarized. This depolarization causes voltage-gated Ca channels to open, and for extracellular Ca to flow down its concentration gradient into the cell causing the intracellular Ca concentration to greatly increase. Once the Ca is inside the cell, it binds to the vesicle release machinery and facilitates binding of the t-snare complex on the vesicle to the s-snare complex on the NEC cell membrane which initiates the release of neurotransmitters into the synaptic cleft. | 0 | Theoretical and Fundamental Chemistry |
Glycans and glycan-based molecules have been used as drugs themselves. The two main functions of these drugs are to either bind protein or inhibit glycosyl degradation. For example, engineered glycans, such as Zanamivir and Oseltamivir have been designed to bind to viral sialidases, which are enzymes that play key roles in viral replication cycles, such as for influenza. With these sialidases inhibited, viral budding and entry into host cells is inhibited. Other drugs, such as Miglitol and Acarbose, serve as therapeutic drugs to people with Type 2 diabetes, as these engineered glycan derivatives bind to glucosidases and amylases to help control patient's blood sugar level. | 1 | Applied and Interdisciplinary Chemistry |
The advantages are:
*Decrease in yield strength, therefore it is easier to work and uses less energy or force
*Increase in ductility
*Elevated temperatures increase diffusion which can remove or reduce chemical inhomogeneities
*Pores may reduce in size or close completely during deformation
*In steel, the weak, ductile, face-centered-cubic austenite microstructure is deformed instead of the strong body-centered-cubic ferrite microstructure found at lower temperatures
Usually the initial workpiece that is hot worked was originally cast. The microstructure of cast items does not optimize the engineering properties, from a microstructure standpoint. Hot working improves the engineering properties of the workpiece because it replaces the microstructure with one that has fine spherical shaped grains. These grains increase the strength, ductility, and toughness of the material.
The engineering properties can also be improved by reorienting the inclusions (impurities). In the cast state the inclusions are randomly oriented, which, when intersecting the surface, can be a propagation point for cracks. When the material is hot worked the inclusions tend to flow with the contour of the surface, creating stringers. As a whole the strings create a flow structure, where the properties are anisotropic (different based on direction). With the stringers oriented parallel to the surface it strengthens the workpiece, especially with respect to fracturing. The stringers act as "crack-arrestors" because the crack will want to propagate through the stringer and not along it.
The disadvantages are:
*Undesirable reactions between the metal and the surrounding atmosphere (scaling or rapid oxidation of the workpiece)
*Less precise tolerances due to thermal contraction and warping from uneven cooling
*Grain structure may vary throughout the metal for various reasons
*Requires a heating unit of some kind such as a gas or diesel furnace or an induction heater, which can be very expensive | 1 | Applied and Interdisciplinary Chemistry |
Omni processor is a term coined in 2012 by staff of the Water, Sanitation, Hygiene Program of the Bill & Melinda Gates Foundation to describe a range of physical, biological or chemical treatments to remove pathogens from human-generated fecal sludge, while simultaneously creating commercially valuable byproducts (e.g., energy). An omni processor mitigates unsafe methods in developing countries of capturing and treating human waste, which annually result in the spread of disease and the deaths of more than 1.5 million children.
Rather than a trademark, or a reference to a specific technology, the term omni processor is a general term for a range of self-sustaining, independently developed systems designed with the same end in mind, to transform and extract value from human waste — using various technological approaches, including combustion, supercritical water oxidation and pyrolysis.
In the term, omni refers to the ability of an omni processor to treat a wide variety of waste streams or fuel sources. | 1 | Applied and Interdisciplinary Chemistry |
The preparation of closo-dicarbadodecaboranes was reported independently by groups at Olin Corporation and the Reaction Motors Division of Thiokol Chemical Corporation working under the U.S. Air Force and published in 1963. These groups demonstrated the high stability in air of 1,2-closo-dodecaborane and related compounds, presented a general synthesis, described the transformation of substituents without destroying the carborane cluster, and demonstrated the ortho to meta isomerization. | 0 | Theoretical and Fundamental Chemistry |
Survivin, also called baculoviral inhibitor of apoptosis repeat-containing 5 or BIRC5, is a protein that, in humans, is encoded by the BIRC5 gene.
Survivin is a member of the inhibitor of apoptosis (IAP) family. The survivin protein functions to inhibit caspase activation, thereby leading to negative regulation of apoptosis or programmed cell death. This has been shown by disruption of survivin induction pathways leading to increase in apoptosis and decrease in tumour growth. The survivin protein is expressed highly in most human tumours and fetal tissue, but is completely absent in terminally differentiated cells. These data suggest survivin might provide a new target for cancer therapy that would discriminate between transformed and normal cells. Survivin expression is also highly regulated by the cell cycle and is only expressed in the G2-M phase. It is known that Survivin localizes to the mitotic spindle by interaction with tubulin during mitosis and may play a contributing role in regulating mitosis. The molecular mechanisms of survivin regulation are still not well understood, but regulation of survivin seems to be linked to the p53 protein. It also is a direct target gene of the Wnt pathway and is upregulated by beta-catenin. | 1 | Applied and Interdisciplinary Chemistry |
Sustainable Development Goal 6 has a Target 6.3 which is formulated as follows: "By 2030, improve water quality by reducing pollution, eliminating dumping and minimizing release of hazardous chemicals and materials, halving the proportion of untreated wastewater and substantially increasing recycling and safe reuse globally." The corresponding Indicator 6.3.1 is the "proportion of wastewater safely treated". It is anticipated that wastewater production would rise by 24% by 2030 and by 51% by 2050.
Data in 2020 showed that there is still too much uncollected household wastewater: Only 66% of all household wastewater flows were collected at treatment facilities in 2020 (this is determined from data from 128 countries). Based on data from 42 countries in 2015, the report stated that "32 per cent of all wastewater flows generated from point sources received at least some treatment". For sewage that has indeed been collected at centralized sewage treatment plants, about 79% went on to be safely treated in 2020. | 1 | Applied and Interdisciplinary Chemistry |
Vapor diffusion is the most commonly employed method of protein crystallization. In this method, droplets containing purified protein, buffer, and precipitant are allowed to equilibrate with a larger reservoir containing similar buffers and precipitants in higher concentrations. Initially, the droplet of protein solution contains comparatively low precipitant and protein concentrations, but as the drop and reservoir equilibrate, the precipitant and protein concentrations increase in the drop. If the appropriate crystallization solutions are used for a given protein, crystal growth occurs in the drop. This method is used because it allows for gentle and gradual changes in concentration of protein and precipitant concentration, which aid in the growth of large and well-ordered crystals.
Vapor diffusion can be performed in either hanging-drop or sitting-drop format. Hanging-drop apparatus involve a drop of protein solution placed on an inverted cover slip, which is then suspended above the reservoir. Sitting-drop crystallization apparatus place the drop on a pedestal that is separated from the reservoir. Both of these methods require sealing of the environment so that equilibration between the drop and reservoir can occur. | 0 | Theoretical and Fundamental Chemistry |
Genetic regulatory circuits (also referred to as transcriptional regulatory circuits) is a concept that evolved from the Operon Model discovered by François Jacob and Jacques Monod. They are functional clusters of genes that impact each other's expression through inducible transcription factors and cis-regulatory elements.
Genetic regulatory circuits are analogous in many ways to electronic circuits in how they use signal inputs and outputs to determine gene regulation. Like electronic circuits, their organization determines their efficiency, and this has been demonstrated in circuits working in series to have a greater sensitivity of gene regulation. They also use inputs such as trans and cis sequence regulators of genes, and outputs such as gene expression level. Depending on the type of circuit, they respond constantly to outside signals, such as sugars and hormone levels, that determine how the circuit will return to its fixed point or periodic equilibrium state. Genetic regulatory circuits also have an ability to be evolutionarily rewired without the loss of the original transcriptional output level. This rewiring is defined by the change in regulatory-target gene interactions, while there is still conservation of regulatory factors and target genes. | 1 | Applied and Interdisciplinary Chemistry |
In the iron and steel industry, direct reduction is a set of processes for obtaining iron from iron ore, by reducing iron oxides without melting the metal. The resulting product is pre-reduced iron ore.
Historically, direct reduction was used to obtain a burr in a low furnace. At the beginning of the 20th century, this process was abandoned in favor of the blast furnace, which produces iron in two stages (reduction-melting to produce cast iron, followed by refining in a converter).
However, various processes were developed in the course of the 20th century and, since the 1970s, the production of pre-reduced iron ore has undergone remarkable industrial development, notably with the rise of the Midrex process. Designed to replace the blast furnace, these processes have so far only proved profitable in certain economic contexts, which still limits this sector to less than 5% of world steel production. | 1 | Applied and Interdisciplinary Chemistry |
Ablation doses are usually administered on an inpatient basis, and IAEA International Basic Safety Standards recommend that patients are not discharged until the activity falls below 1100 MBq. ICRP advice states that "comforters and carers" of patients undergoing radionuclide therapy should be treated as members of the public for dose constraint purposes and any restrictions on the patient should be designed based on this principle.
Patients receiving I-131 radioiodine treatment may be warned not to have sexual intercourse for one month (or shorter, depending on dose given), and women told not to become pregnant for six months afterwards. "This is because a theoretical risk to a developing fetus exists, even though the amount of radioactivity retained may be small and there is no medical proof of an actual risk from radioiodine treatment. Such a precaution would essentially eliminate direct fetal exposure to radioactivity and markedly reduce the possibility of conception with sperm that might theoretically have been damaged by exposure to radioiodine." These guidelines vary from hospital to hospital and will depend on national legislation and guidance, as well as the dose of radiation given. Some also advise not to hug or hold children when the radiation is still high, and a one- or two- metre distance to others may be recommended.
I-131 will be eliminated from the body over the next several weeks after it is given. The majority of I-131 will be eliminated from the human body in 3–5 days, through natural decay, and through excretion in sweat and urine. Smaller amounts will continue to be released over the next several weeks, as the body processes thyroid hormones created with the I-131. For this reason, it is advised to regularly clean toilets, sinks, bed sheets and clothing used by the person who received the treatment. Patients may also be advised to wear slippers or socks at all times, and avoid prolonged close contact with others. This minimizes accidental exposure by family members, especially children. Use of a decontaminant specially made for radioactive iodine removal may be advised. The use of chlorine bleach solutions, or cleaners that contain chlorine bleach for cleanup, are not advised, since radioactive elemental iodine gas may be released. Airborne I-131 may cause a greater risk of second-hand exposure, spreading contamination over a wide area. Patient is advised if possible to stay in a room with a bathroom connected to it to limit unintended exposure to family members.
Many airports have radiation detectors to detect the smuggling of radioactive materials. Patients should be warned that if they travel by air, they may trigger radiation detectors at airports up to 95 days after their treatment with I. | 0 | Theoretical and Fundamental Chemistry |
Exemestane is known chemically as 6-methylideneandrosta-1,4-diene-3,17-dione. Like the aromatase inhibitors formestane and atamestane, exemestane is a steroid that is structurally similar to 4-androstenedione, the natural substrate of aromatase. It is distinguished from the natural substance only by the methylidene group in position 6 and an additional double bond in position 1.
Pure exemestane is a white to off-white powder that is soluble in DMSO to at least 20 mg/mL. Optical rotation [α] is +250 to 300° (per g/100 cm and decimetre at 589 nm wavelength). | 0 | Theoretical and Fundamental Chemistry |
Adverse effects at targets other than those desired for pharmaceutical treatments often occur with drugs that are nonspecific. If a drug can bind to unexpected proteins, receptors, or enzymes that can alter different pathways other than those desired for treatment, severe downstream effects can develop. An example of this is the drug eplerenone (aldosterone receptor antagonist), which should increase aldosterone levels, but has shown to produce atrophy of the prostate. | 1 | Applied and Interdisciplinary Chemistry |
One of the largest and most diverse uses of the intercalation process by the early 2020s is in lithium-ion electrochemical energy storage, in the batteries used in many handheld electronic devices, mobility devices, electric vehicles, and utility-scale battery electric storage stations.
By 2023, all commercial Li-ion cells use intercalation compounds as active materials, and most use them in both the cathode and anode within the battery physical structure.
In 2012 three researchers, Goodenough, Yazami and Yoshino, received the 2012 IEEE Medal for Environmental and Safety Technologies for developing the intercalated lithium-ion battery and subsequently Goodenough, Whittingham, and Yoshino were awarded the 2019 Nobel Prize in Chemistry "for the development of lithium-ion batteries". | 0 | Theoretical and Fundamental Chemistry |
Endre Qvie Berner (24 September 1893 – 30 January 1983) was a Norwegian organic chemist, author and educator. | 0 | Theoretical and Fundamental Chemistry |
Thermal radiation plays a crucial role in human comfort, influencing perceived temperature sensation. Various technologies have been developed to enhance thermal comfort, including personal heating and cooling devices.
The mean radiant temperature is a metric used to quantify the exchange of radiant heat between a human and their surrounding environment. | 0 | Theoretical and Fundamental Chemistry |
The physical and societal aspects of the Curies' work contributed to shaping the world of the twentieth and twenty-first centuries. Cornell University professor L. Pearce Williams observes:
In addition to helping to overturn established ideas in physics and chemistry, Curie's work has had a profound effect in the societal sphere. To attain her scientific achievements, she had to overcome barriers, in both her native and her adoptive country, that were placed in her way because she was a woman.
She was known for her honesty and moderate lifestyle. Having received a small scholarship in 1893, she returned it in 1897 as soon as she began earning her keep. She gave much of her first Nobel Prize money to friends, family, students, and research associates. In an unusual decision, Curie intentionally refrained from patenting the radium-isolation process so that the scientific community could do research unhindered. She insisted that monetary gifts and awards be given to the scientific institutions she was affiliated with rather than to her. She and her husband often refused awards and medals. Albert Einstein reportedly remarked that she was probably the only person who could not be corrupted by fame. | 0 | Theoretical and Fundamental Chemistry |
Cyclooxygenase (COX) catalyzes the conversion of the free essential fatty acids to prostanoids by a two-step process.
In the first step, two molecules of O are added as two peroxide linkages and a 5-member carbon ring is forged near the middle of the fatty acid chain. This forms the short-lived, unstable intermediate Prostaglandin G (PGG).
One of the peroxide linkages sheds a single oxygen, forming PGH. (See diagrams and more detail at Cyclooxygenase).
All other prostanoids originate from PGH (as PGH, PGH, or PGH).
The image at right shows how PGH (derived from Arachidonic acid) is converted:
* By PGE synthetase into PGE2 (which in turn is converted into PGF2)
* By PGD synthetase into PGD2
* By Prostacyclin synthase into prostacyclin (PGI2)
* By Thromboxane synthase into thromboxanes TXA
Arachidonic acid is made up of a 20-Carbon unnatural poly unsaturated Omega-fatty acid. Arachidonic acid presents within the phospholipid bi-layer as well as in the plasma membrane of a cell. With Arachidonic acid prostaglandins are formed through synthesis and oxygenation of enzymes. Active lipids in the oxylipin family derive from the synthesis of Cyclooxygenase or Prostaglandins.
The three classes of prostanoids have distinctive rings in the center of the molecule. They differ in their structures and do not share common structure as Thromboxane. The PGH compounds (parents to all the rest) have a 5-carbon ring, bridged by two oxygens (a peroxide.) The derived prostaglandins contain a single, unsaturated 5-carbon ring. In prostacyclins, this ring is conjoined to another oxygen-containing ring. In thromboxanes the ring becomes a 6-member ring with one oxygen.
Production of PGE in bacterial and viral infections appear to be stimulated by certain cytokines, e.g., interleukin-1. | 1 | Applied and Interdisciplinary Chemistry |
The Taylor microscale falls in between the large-scale eddies and the small-scale eddies, which can be seen by calculating the ratios between and the Kolmogorov microscale . Given the length scale of the larger eddies , and the turbulence Reynolds number referred to these eddies, the following relations can be obtained: | 1 | Applied and Interdisciplinary Chemistry |
A commercially important family of metal carboxylates are derived from aminopolycarboxylates, e.g., EDTA. Related to these synthetic chelating agents are the amino acids, which form large families of amino acid complexes. Two amino acids, glutamate and aspartate, have carboxylate side chains, which function as ligands for iron in nonheme iron proteins, such as hemerythrin. | 0 | Theoretical and Fundamental Chemistry |
Polypeptides have an N-terminus and a C-terminus, which refer to the ends of the polymer in a way that reflects the direction in which the polymer was synthesized. The chronological sequence of each amino acid sub-unit is the basis for directionality notation in polypeptides; a given protein can be represented as its set of unique amino acid abbreviations within an N-terminus and a C-terminus. | 1 | Applied and Interdisciplinary Chemistry |
In aeronautics and fluid dynamics the "International Standard Atmosphere" (ISA) is a specification of pressure, temperature, density, and speed of sound at each altitude. The International Standard Atmosphere is representative of atmospheric conditions at mid latitudes. In the US this information is specified the U.S. Standard Atmosphere which is identical to the "International Standard Atmosphere" at all altitudes up to 65,000 feet above sea level. | 0 | Theoretical and Fundamental Chemistry |
The chief reaction of imines, often undesirable, is their hydrolysis back to the amine and the carbonyl precursor.
:RC=NR + HO RC=O + RNH | 0 | Theoretical and Fundamental Chemistry |
* Sumgait Aluminum Plant
* Ganja Aluminum Plant
* Bakı Poladtökmə
* Bakusteelcompany
* Sumgait Pipe Plant
* AzerGold
* CJSC Global Construction
* CJSC Atahan Dirmir Sənaye
* Daşkəsən Filizsaflaşdırma
* Azərboru
* Azərqızıl
* Azertexnolayn LLC
http://www.azertexnolayn.com/en/ | 1 | Applied and Interdisciplinary Chemistry |
Organic acid anhydrides are prepared in industry by diverse means. Acetic anhydride is mainly produced by the carbonylation of methyl acetate. Maleic anhydride is produced by the oxidation of benzene or butane. Laboratory routes emphasize the dehydration of the corresponding acids. The conditions vary from acid to acid, but phosphorus pentoxide is a common dehydrating agent:
:2 CHCOOH + PO → CHC(O)OC(O)CH + "PO(OH)"
Acid chlorides are also effective precursors:
:CHC(O)Cl + HCONa → HCOCOCH + NaCl
Mixed anhydrides containing the acetyl group are prepared from ketene:
:RCOH + HC=C=O → RCOC(O)CH | 0 | Theoretical and Fundamental Chemistry |
5-methylcytidine, m5C, is abundantly found in mRNA and ncRNAs, especially tRNA and rRNAs. In tRNAs, this modification stabilizes the secondary structure and influences anticodon stem-loop conformation. In rRNAs, m5C affects translational fidelity.
Two principles have been used to develop m5C sequencing methods. The first one is antibody-based approach (bisuphite sequencing and m5C-RIP), similar to m6C sequencing. The second is detecting targets of m5C RNA methyltransferases by covalently linking the enzyme to its target, and then using IP specific to the target enzyme to enrich for RNA molecules containing the mark (Aza-IP and miCLIP). | 1 | Applied and Interdisciplinary Chemistry |
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.