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The following reactions describe the methanation of carbon monoxide and carbon dioxide respectively:
: -206 kJ/mol
: -164 kJ/mol
The methanation reactions are classified as exothermic and their energy of formations are listed.
There is disagreement on whether the CO methanation occurs by first associatively adsorbing an adatom hydrogen and forming oxygen intermediates before hydrogenation or dissociating and forming a carbonyl before being hydrogenated. CO is believed to be methanated through a dissociative mechanism where the carbon-oxygen bond is broken before hydrogenation with an associative mechanism only being observed at high H concentrations.
Methanation reaction over different carried metal catalysts including Ni, Ru and Rh has been widely investigated for the production of CH from syngas and other power to gas initiatives. Nickel is the most widely used catalyst due to its high selectivity and low cost. | 0 | Theoretical and Fundamental Chemistry |
Some filters, notably welding glass, are rated by shade number (SN), which is 7/3 times the absorbance plus one:
For example, if the filter has 0.1% transmittance (0.001 transmittance, which is 3 absorbance units), its shade number would be 8. | 0 | Theoretical and Fundamental Chemistry |
In chemistry, peroxycarbonate (sometimes peroxocarbonate, IUPAC name: oxocarbonate or oxidocarbonate) or percarbonate is a divalent anion with formula . It is an oxocarbon anion that consists solely of carbon and oxygen. It would be the anion of a hypothetical peroxycarbonic acid HO–CO–O–OH (sometimes peroxocarbonic acid). or the real hydroperoxyformic acid, HO-O-CO-OH (a.k.a. percarbonic acid, carbonoperoxoic acid, hydroxycarbonic acid).
The peroxycarbonate anion is formed, together with peroxydicarbonate , at the negative electrode during electrolysis of molten lithium carbonate. Lithium peroxycarbonate can be produced also by combining carbon dioxide with lithium hydroxide in concentrated hydrogen peroxide HO at −10 °C.
Electrolysis of a solution of lithium carbonate at -30° to -40 °C yields a solution of the Lithium percarbonate, which can liberate iodine from potassium iodide instantaneously. The crystalline salt has not been isolated.
The peroxycarbonate anion has been proposed as an intermediate to explain the catalytic effect of CO on the oxidation of organic compounds by O.
The potassium and rubidium salts of the monovalent hydrogenperoxycarbonate anion (aka. hydroxycarbonate, biperoxycarbonate) have also been obtained. | 0 | Theoretical and Fundamental Chemistry |
Flash joule heating (transient high-temperature electrothermal heating) has been used to synthesize allotropes of carbon, including graphene and diamond. Heating various solid carbon feedstocks (carbon black, coal, coffee grounds, etc.) to temperatures of ~3000 K for 10-150 milliseconds produces turbostratic graphene flakes. FJH has also been used to recover rare-earth elements used in modern electronics from industrial wastes. Beginning from a fluorinated carbon source, fluorinated activated carbon, fluorinated nanodiamond, concentric carbon (carbon shell around a nanodiamond core), and fluorinated flash graphene can be synthesized. | 0 | Theoretical and Fundamental Chemistry |
Biochemical detection is the science and technology of detecting biochemicals and their concentration where trace analysis is concerned this is usually done by using a quartz crystal microbalance, which measures a mass per unit area by measuring the change in frequency of a quartz crystal resonator. Another method is with nanoparticles. | 1 | Applied and Interdisciplinary Chemistry |
Agents that transiently block MPT include the immune suppressant cyclosporin A (CsA); N-methyl-Val-4-cyclosporin A (MeValCsA), a non-immunosuppressant derivative of CsA; another non-immunosuppressive agent, NIM811, 2-aminoethoxydiphenyl borate (2-APB), bongkrekic acid and alisporivir (also known as Debio-025). TRO40303 is a newly synthetitised MPT blocker developed by Trophos company and currently is in Phase I clinical trial. | 1 | Applied and Interdisciplinary Chemistry |
In the context of pharmacodynamics (how the drug affects the body), the hydrophobic effect is the major driving force for the binding of drugs to their receptor targets. On the other hand, hydrophobic drugs tend to be more toxic because they, in general, are retained longer, have a wider distribution within the body (e.g., intracellular), are somewhat less selective in their binding to proteins, and finally are often extensively metabolized. In some cases the metabolites may be chemically reactive. Hence it is advisable to make the drug as hydrophilic as possible while it still retains adequate binding affinity to the therapeutic protein target. For cases where a drug reaches its target locations through passive mechanisms (i.e., diffusion through membranes), the ideal distribution coefficient for the drug is typically intermediate in value (neither too lipophilic, nor too hydrophilic); in cases where molecules reach their targets otherwise, no such generalization applies. | 0 | Theoretical and Fundamental Chemistry |
The equation relating thermal energy to thermal mass is:
where Q is the thermal energy transferred, C is the thermal mass of the body, and ΔT is the change in temperature.
For example, if 250 J of heat energy is added to a copper gear with a thermal mass of 38.46 J/°C, its temperature will rise by 6.50 °C.
If the body consists of a homogeneous material with sufficiently known physical properties, the thermal mass is simply the mass of material present times the specific heat capacity of that material. For bodies made of many materials, the sum of heat capacities for their pure components may be used in the calculation, or in some cases (as for a whole animal, for example) the number may simply be measured for the entire body in question, directly.
As an extensive property, heat capacity is characteristic of an object; its corresponding intensive property is specific heat capacity, expressed in terms of a measure of the amount of material such as mass or number of moles, which must be multiplied by similar units to give the heat capacity of the entire body of material. Thus the heat capacity can be equivalently calculated as the product of the mass m of the body and the specific heat capacity c for the material, or the product of the number of moles of molecules present n and the molar specific heat capacity . For discussion of why the thermal energy storage abilities of pure substances vary, see factors that affect specific heat capacity.
For a body of uniform composition, can be approximated by
where is the mass of the body and is the isobaric specific heat capacity of the material averaged over temperature range in question. For bodies composed of numerous different materials, the thermal masses for the different components can just be added together. | 0 | Theoretical and Fundamental Chemistry |
The role that plastoquinone plays in photosynthesis, more specifically in the light-dependent reactions of photosynthesis, is that of a mobile electron carrier through the membrane of the thylakoid.
Plastoquinone is reduced when it accepts two electrons from photosystem II and two hydrogen cations (H) from the stroma of the chloroplast, thereby forming plastoquinol (PQH). It transfers the electrons further down the electron transport chain to plastocyanin, a mobile, water-soluble electron carrier, through the cytochrome bf protein complex. The cytochrome bf protein complex catalyzes the electron transfer between plastoquinone and plastocyanin, but also transports the two protons into the lumen of thylakoid discs. This proton transfer forms an electrochemical gradient, which is used by ATP synthase at the end of the light dependent reactions in order to form ATP from ADP and P. | 0 | Theoretical and Fundamental Chemistry |
In electrochemistry, partial current is defined as the electric current associated with (anodic or cathodic) half of the electrode reaction.
Depending on the electrode half-reaction, one can distinguish two types of partial current:
* cathodic partial current I (called also cathodic current): is the flow of electrons from the electrode surface to a species in solution;
* anodic partial current I (called also anodic current): is the flow of electrons into the electrode from a species in solution.
The cathodic and anodic partial currents are defined by IUPAC.
The partial current densities (i and i) are the ratios of partial currents respect to the electrode areas (A and A):
:i = I/A
:i = I/A
The sum of the cathodic partial current density i (positive) and the anodic partial current density i (negative) gives the net current density i:
:i = i + i
In the case of the cathodic partial current density being equal to the anodic partial current density (for example, in a corrosion process), the net current density on the electrode is zero:
:i = i + i = 0
When more than one reaction occur on an electrode simultaneously, then the total electrode current can be expressed as:
where the index refers to the particular reactions. | 0 | Theoretical and Fundamental Chemistry |
The empirical Monod equation is
where:
: μ is the growth rate of a considered microorganism,
: μ is the maximum growth rate of this microorganism,
: [S] is the concentration of the limiting substrate S for growth,
: K is the "half-velocity constant"—the value of [S] when μ/μ = 0.5.
μ and K are empirical (experimental) coefficients to the Monod equation. They will differ between microorganism species and will also depend on the ambient environmental conditions, e.g., on the temperature, on the pH of the solution, and on the composition of the culture medium. | 0 | Theoretical and Fundamental Chemistry |
The hydrophobic effect represents the tendency of water to exclude non-polar molecules. The effect originates from the disruption of highly dynamic hydrogen bonds between molecules of liquid water. Polar chemical groups, such as OH group in methanol do not cause the hydrophobic effect. However, a pure hydrocarbon molecule, for example hexane, cannot accept or donate hydrogen bonds to water. Introduction of hexane into water causes disruption of the hydrogen bonding network between water molecules. The hydrogen bonds are partially reconstructed by building a water "cage" around the hexane molecule, similar to that in clathrate hydrates formed at lower temperatures. The mobility of water molecules in the "cage" (or solvation shell) is strongly restricted. This leads to significant losses in translational and rotational entropy of water molecules and makes the process unfavorable in terms of free energy of the system. In terms of thermodynamics, the hydrophobic effect is the free energy change of water surrounding a solute. A positive free energy change of the surrounding solvent indicates hydrophobicity, whereas a negative free energy change implies hydrophilicity. In this way, the hydrophobic effect not only can be localized but also decomposed into enthalpic and entropic contributions. | 0 | Theoretical and Fundamental Chemistry |
Drag-reducing agents (DRA), or drag-reducing polymers (DRP's), are additives in pipelines that reduce turbulence in a pipe. Usually used in petroleum pipelines, they increase the pipeline capacity by reducing turbulency and increasing laminar flow. | 1 | Applied and Interdisciplinary Chemistry |
Pyrimidine (; ) is an aromatic, heterocyclic, organic compound similar to pyridine (). One of the three diazines (six-membered heterocyclics with two nitrogen atoms in the ring), it has nitrogen atoms at positions 1 and 3 in the ring. The other diazines are pyrazine (nitrogen atoms at the 1 and 4 positions) and pyridazine (nitrogen atoms at the 1 and 2 positions).
In nucleic acids, three types of nucleobases are pyrimidine derivatives: cytosine (C), thymine (T), and uracil (U). | 1 | Applied and Interdisciplinary Chemistry |
Given that DNA and RNA polymerases both carry out template-dependent nucleotide polymerization, it might be expected that the two types of enzymes would be structurally related. However, x-ray crystallographic studies of both types of enzymes reveal that, other than containing a critical Mg ion at the catalytic site, they are virtually unrelated to each other; indeed template-dependent nucleotide polymerizing enzymes seem to have arisen independently twice during the early evolution of cells. One lineage led to the modern DNA polymerases and reverse transcriptases, as well as to a few single-subunit RNA polymerases (ssRNAP) from phages and organelles. The other multi-subunit RNAP lineage formed all of the modern cellular RNA polymerases. | 1 | Applied and Interdisciplinary Chemistry |
Kármán–Moore theory is a linearized theory for supersonic flows over a slender body, named after Theodore von Kármán and Norton B. Moore, who developed the theory in 1932. The theory in particular, provides an explicit formula for the wave drag, which converts the kinetic energy of the moving body into outgoing sound waves behind the body. | 1 | Applied and Interdisciplinary Chemistry |
The Warburg hypothesis (), sometimes known as the Warburg theory of cancer, postulates that the driver of tumorigenesis is an insufficient cellular respiration caused by insult to mitochondria. The term Warburg effect in oncology describes the observation that cancer cells, and many cells grown in vitro, exhibit glucose fermentation even when enough oxygen is present to properly respire. In other words, instead of fully respiring in the presence of adequate oxygen, cancer cells ferment. The Warburg hypothesis was that the Warburg effect was the root cause of cancer. The current popular opinion is that cancer cells ferment glucose while keeping up the same level of respiration that was present before the process of carcinogenesis, and thus the Warburg effect would be defined as the observation that cancer cells exhibit glycolysis with lactate production and mitochondrial respiration even in the presence of oxygen. | 1 | Applied and Interdisciplinary Chemistry |
Some may use the terms biogeochemical cycle and geochemical cycle interchangeably because both cycles deal with Earth's reservoirs. However, a biogeochemical cycle refers to the chemical interactions in surface reservoirs such as the atmosphere, hydrosphere, lithosphere, and biosphere whereas a geochemical cycle refers to the chemical interactions that exist in crustal and sub crustal reservoirs such as the deep earth and lithosphere. | 0 | Theoretical and Fundamental Chemistry |
* Waste Framework Directive (2008/98/EC) establishes specific targets for the re-use and recycling of building waste, including glass. Defines high levels of recycling as key for Europe's resource efficiency.
* A ban on landfill disposal of single clear glass panes and insulating glass units should be introduced in the revised version of Directive 1999/31/EC. | 0 | Theoretical and Fundamental Chemistry |
AFM-IR has been used to study hydrated Nafion membranes used as separators in fuel cells. The measurements revealed the distribution of free and ionically bound water on the Nafion surface. | 0 | Theoretical and Fundamental Chemistry |
The two N-terminal cysteines of CXC chemokines (or α-chemokines) are separated by one amino acid, represented in this name with an "X". There have been 17 different CXC chemokines described in mammals, that are subdivided into two categories, those with a specific amino acid sequence (or motif) of glutamic acid-leucine-arginine (or ELR for short) immediately before the first cysteine of the CXC motif (ELR-positive), and those without an ELR motif (ELR-negative). ELR-positive CXC chemokines specifically induce the migration of neutrophils, and interact with chemokine receptors CXCR1 and CXCR2. An example of an ELR-positive CXC chemokine is interleukin-8 (IL-8), which induces neutrophils to leave the bloodstream and enter into the surrounding tissue. Other CXC chemokines that lack the ELR motif, such as CXCL13, tend to be chemoattractant for lymphocytes. CXC chemokines bind to CXC chemokine receptors, of which seven have been discovered to date, designated CXCR1-7. | 1 | Applied and Interdisciplinary Chemistry |
Microfluidics-assisted FISH ([http://www.nature.com/labinvest/journal/v97/n1/abs/labinvest2016121a.html MA-FISH]) uses a microfluidic flow to increase DNA hybridization efficiency, decreasing expensive FISH probe consumption and reduce the hybridization time. MA-FISH is applied for detecting the HER2 gene in breast cancer tissues. | 1 | Applied and Interdisciplinary Chemistry |
Tissue engineering done in vivo is capable of recruiting local cellular populations into a bioreactor space. Indeed a range of neotissue growth has been shown: bone, cartilage, fat, and muscle. In theory, any tissue type could be grown in this manner if all necessary components (growth factors, environmental and physical ques) are met. Recruitment of stem cells require a complex process of mobilization from their niche, though research suggests that mature cells transplanted upon the bioreactor scaffold can improve stem cell recruitment. These cells secrete growth factors that promote repair and can be co-cultured with stem cells to improve tissue formation. | 1 | Applied and Interdisciplinary Chemistry |
If a clone library is constructed in parallel to the T-RFLP analysis then the clones can be used to assess and interpret the T-RFLP profile. In this method the TRF of each clone is determined either directly (i.e. performing T-RFLP analysis on each single clone) or by in silico analysis of that clone’s sequence. By comparing the T-RFLP profile to a clone library it is possible to validate each of the peaks as genuine as well as to assess the relative abundance of each variant in the library. | 1 | Applied and Interdisciplinary Chemistry |
Chemical reactions in biological processes are controlled by enzymes that catalyze the conversion of substrate to product. Since enzymes can alter the transition state structure for reactions, they also change kinetic and equilibrium isotope effects. Placed in the context of a metabolism, the expression of isotope effects on biomolecules is further controlled by branch points. Different pathways of biosynthesis will use different enzymes, yielding a range of position specific isotope enrichments. This variability allows position-specific isotope measurements to discern multiple biosynthetic pathways from the same metabolic product. Biogeochemists use position specific isotope enrichments from amino acids, lipids, and sugars in nature to interpret the relative importance of different metabolisms. | 0 | Theoretical and Fundamental Chemistry |
An improper rotation involves two operation steps: a proper rotation followed by reflection through a plane perpendicular to the rotation axis. The improper rotation is represented by the symbol where is the order. Since the improper rotation is the combination of a proper rotation and a reflection, will always exist whenever and a perpendicular plane exist separately. is usually denoted as , a reflection operation about a mirror plane. is usually denoted as , an inversion operation about an inversion center. When is an even number but when is odd
Rotation axes, mirror planes and inversion centres are symmetry elements, not symmetry operations. The rotation axis of the highest order is known as the principal rotation axis. It is conventional to set the Cartesian -axis of the molecule to contain the principal rotation axis. | 0 | Theoretical and Fundamental Chemistry |
The generator, typically about long and in diameter, contains a stationary stator and a spinning rotor, each containing miles of heavy copper conductor. There is generally no permanent magnet, thus preventing black starts. In operation it generates up to 21,000 amperes at 24,000 volts AC (504 MWe) as it spins at either 3,000 or 3,600 rpm, synchronized to the power grid. The rotor spins in a sealed chamber cooled with hydrogen gas, selected because it has the highest known heat transfer coefficient of any gas and for its low viscosity, which reduces windage losses. This system requires special handling during startup, with air in the chamber first displaced by carbon dioxide before filling with hydrogen. This ensures that a highly explosive hydrogen–oxygen environment is not created.
The power grid frequency is 60 Hz across North America and 50 Hz in Europe, Oceania, Asia (Korea and parts of Japan are notable exceptions), and parts of Africa. The desired frequency affects the design of large turbines, since they are highly optimized for one particular speed.
The electricity flows to a distribution yard where transformers increase the voltage for transmission to its destination.
The steam turbine-driven generators have auxiliary systems enabling them to work satisfactorily and safely. The steam turbine generator, being rotating equipment, generally has a heavy, large-diameter shaft. The shaft therefore requires not only supports but also has to be kept in position while running. To minimize the frictional resistance to the rotation, the shaft has a number of bearings. The bearing shells, in which the shaft rotates, are lined with a low-friction material like Babbitt metal. Oil lubrication is provided to further reduce the friction between shaft and bearing surface and to limit the heat generated. | 1 | Applied and Interdisciplinary Chemistry |
5β-Coprostanol (5β-cholestan-3β-ol) is a 27-carbon stanol formed from the net reductive metabolism of cholesterol (cholest-5en-3β-ol) in the gut of most higher animals and birds. This compound has frequently been used as a biomarker for the presence of human faecal matter in the environment. 5β-coprostanol is thought to be exclusively bacterial in origin. | 1 | Applied and Interdisciplinary Chemistry |
The hardness of a material can be measured in many ways. The Knoop hardness test, a method of microindentation hardness, is the most reproducible for dense ceramics. The Vickers hardness test and superficial Rockwell scales (e.g., 45N) can also be used, but tend to cause more surface damage than Knoop. The Brinell test is suitable for ductile metals, but not ceramics. In the Knoop test, a diamond indenter in the shape of an elongated pyramid is forced into a polished (but not etched) surface under a predetermined load, typically 500 or 1000 g. The load is held for some amount of time, say 10 s, and the indenter is retracted. The indention long diagonal (d, μm, in Fig. 4) is measured under a microscope, and the Knoop hardness (HK) is calculated from the load (P, g) and the square of the diagonal length in the equations below. The constants account for the projected area of the indenter and unit conversion factors. Most oxide ceramics have a Knoop hardness in the range of 1000–1500 kg/mm (10 – 15 GPa), and many carbides are over 2000 (20 GPa). The method is specified in ASTM C849, C1326 & E384. Microindentation hardness is also called microindentation hardness or simply microhardness. The hardness of very small particles and thin films of ceramics, on the order of 100 nm, can be measured by nanoindentation methods that use a Berkovich indenter.
: (kg/mm) and (GPa)
The toughness of ceramics can be determined from a Vickers test under a load of 10 – 20 kg. Toughness is the ability of a material to resist crack propagation. Several calculations have been formulated from the load (P), elastic modulus (E), microindentation hardness (H), crack length (c in Fig. 5) and flexural strength (σ). Modulus of rupture (MOR) bars with a rectangular cross-section are indented in three places on a polished surface. The bars are loaded in 4-point bending with the polished, indented surface in tension, until fracture. The fracture normally originates at one of the indentions. The crack lengths are measured under a microscope. The toughness of most ceramics is 2–4 MPa, but toughened zirconia is as much as 13, and cemented carbides are often over 20. The toughness-by-indention methods have been discredited recently and are being replaced by more rigorous methods that measure crack growth in a notched beam in bending.
: initial crack length
: indention strength in bending | 1 | Applied and Interdisciplinary Chemistry |
Wet deposition of acids occurs when any form of precipitation (rain, snow, and so on) removes acids from the atmosphere and delivers it to the Earth's surface. This can result from the deposition of acids produced in the raindrops (see aqueous phase chemistry above) or by the precipitation removing the acids either in clouds or below clouds. Wet removal of both gases and aerosols are both of importance for wet deposition.
CAM plants are predominantly found in arid environments, where water availability is limited. | 1 | Applied and Interdisciplinary Chemistry |
A tidal bore is a hydraulic jump which occurs when the incoming tide forms a wave (or waves) of water that travel up a river or narrow bay against the direction of the current. As is true for hydraulic jumps in general, bores take on various forms depending upon the difference in the waterlevel upstream and down, ranging from an undular wavefront to a shock-wave-like wall of water. Figure 3 shows a tidal bore with the characteristics common to shallow upstream water – a large elevation difference is observed. Figure 4 shows a tidal bore with the characteristics common to deep upstream water – a small elevation difference is observed and the wavefront undulates. In both cases the tidal wave moves at the speed characteristic of waves in water of the depth found immediately behind the wave front. A key feature of tidal bores and positive surges is the intense turbulent mixing induced by the passage of the bore front and by the following wave motion.
Another variation of the moving hydraulic jump is the cascade. In the cascade, a series of roll waves or undulating waves of water moves downstream overtaking a shallower downstream flow of water.
A moving hydraulic jump is called a surge. The travel of wave is faster in the upper portion than in the lower portion in case of positive surges | 1 | Applied and Interdisciplinary Chemistry |
Electrochemical kinetics is the field of electrochemistry that studies the rate of electrochemical processes. This includes the study of how process conditions, such as concentration and electric potential, influence the rate of oxidation and reduction (redox) reactions that occur at the surface of an electrode, as well as an investigation into electrochemical reaction mechanisms. Two accompanying processes are involved in the electrochemical reaction and influence the overall reaction rate:
* electron transfer at the interface between the electrode and the electrolyte
* transport of the redox species from the interior of the solution to the surface of the electrode; the transport can occur by diffusion, convection and migration.
Contributors to this field include Alexander Frumkin, John Alfred Valentine Butler, Max Volmer, and Julius Tafel. | 0 | Theoretical and Fundamental Chemistry |
A parallel relationship can easily be drawn between halogen bonding and hydrogen bonding. Both interactions revolve around an electron donor/electron acceptor relationship, between a halogen-like atom and an electron-dense one. But halogen bonding is both much stronger and more sensitive to direction than hydrogen bonding. A typical hydrogen bond has energy of formation ; known halogen bond energies range from 10–200 kJ/mol.
The σ-hole concept readily extends to pnictogen, chalcogen and aerogen bonds, corresponding to atoms of Groups 15, 16 and 18 (respectively). | 0 | Theoretical and Fundamental Chemistry |
MALDI-TOF spectra have been used for the detection and identification of various parasites such as trypanosomatids, Leishmania and Plasmodium. In addition to these unicellular parasites, MALDI/TOF can be used for the identification of parasitic insects such as lice or cercariae, the free-swimming stage of trematodes. | 1 | Applied and Interdisciplinary Chemistry |
The incompressible Navier–Stokes equations are the partial differential equations given by
where is the velocity of the fluid, the pressure, the viscosity and the external volumetric force.
By applying the Leray projection to the first equation, we may rewrite the Navier-Stokes equations as an abstract differential equation on an infinite dimensional phase space, such as , the space of continuous functions from to where and is the space of square-integrable functions on the physical domain :
where we have defined the Stokes operator and the bilinear form by
The pressure and the divergence free condition are "projected away". In general, we assume for simplicity that is divergence free, so that ; this can always be done, by adding the term to the pressure. | 1 | Applied and Interdisciplinary Chemistry |
ITC is a quantitative technique that can determine the binding affinity (), reaction enthalpy (), and binding stoichiometry () of the interaction between two or more molecules in solution. This is achieved by measuring the enthalpies of a series of binding reactions caused by injections of a solution of one molecule to a reaction cell containing a solution of another molecule. The enthalpy values are plotted over the molar ratios resulting from the injections. From the plot, the molar reaction enthalpy , the affinity constant () and the stochiometry are determined by curve fitting. The reaction's Gibbs free energy change () and entropy change () can be determined using the relationship:
(where is the gas constant and is the absolute temperature).
For accurate measurements of binding affinity, the curve of the thermogram must be sigmoidal. The profile of the curve is determined by the c-value, which is calculated using the equation:
where is the stoichiometry of the binding, is the association constant and is the concentration of the molecule in the cell. The c-value must fall between 1 and 1000, ideally between 10 and 100. In terms of binding affinity, it would be approximately from ~ within the limit range. | 0 | Theoretical and Fundamental Chemistry |
Iron technology was further advanced by several inventions in medieval Islam, during the Islamic Golden Age. These included a variety of water-powered and wind-powered industrial mills for metal production, including geared gristmills and forges. By the 11th century, every province throughout the Muslim world had these industrial mills in operation, from Islamic Spain and North Africa in the west to the Middle East and Central Asia in the east. There are also 10th-century references to cast iron, as well as archeological evidence of blast furnaces being used in the Ayyubid and Mamluk empires from the 11th century, thus suggesting a diffusion of Chinese metal technology to the Islamic world.
Geared gristmills were invented by Muslim engineers, and were used for crushing metallic ores before extraction. Gristmills in the Islamic world were often made from both watermills and windmills. In order to adapt water wheels for gristmilling purposes, cams were used for raising and releasing trip hammers. The first forge driven by a hydropowered water mill rather than manual labour was invented in the 12th century Islamic Spain.
One of the most famous steels produced in the medieval Near East was Damascus steel used for swordmaking, and mostly produced in Damascus, Syria, in the period from 900 to 1750. This was produced using the crucible steel method, based on the earlier Indian wootz steel. This process was adopted in the Middle East using locally produced steels. The exact process remains unknown, but it allowed carbides to precipitate out as micro particles arranged in sheets or bands within the body of a blade. Carbides are far harder than the surrounding low carbon steel, so swordsmiths could produce an edge that cut hard materials with the precipitated carbides, while the bands of softer steel let the sword as a whole remain tough and flexible. A team of researchers based at the Technical University of Dresden that uses X-rays and electron microscopy to examine Damascus steel discovered the presence of cementite nanowires and carbon nanotubes. Peter Paufler, a member of the Dresden team, says that these nanostructures give Damascus steel its distinctive properties and are a result of the forging process. | 1 | Applied and Interdisciplinary Chemistry |
Blood serum amylase may be measured for purposes of medical diagnosis. A higher than normal concentration may reflect any of several medical conditions, including acute inflammation of the pancreas (which may be measured concurrently with the more specific lipase), perforated peptic ulcer, torsion of an ovarian cyst, strangulation, ileus, mesenteric ischemia, macroamylasemia and mumps. Amylase may be measured in other body fluids, including urine and peritoneal fluid.
A January 2007 study from Washington University in St. Louis suggests that saliva tests of the enzyme could be used to indicate sleep deficits, as the enzyme increases its activity in correlation with the length of time a subject has been deprived of sleep. | 1 | Applied and Interdisciplinary Chemistry |
Partial agonists are any chemical that can bind to a receptor without eliciting the maximum downstream response as compared to the response from a full agonist. A given partial agonist's affinity for a given receptor is also irrelevant to the consequent effect. An example is buprenorphine, a partial opioid receptor agonist used to treat opioid addictions by directly substituting for them without the same strength of effect. | 1 | Applied and Interdisciplinary Chemistry |
Inert solids are produced in all montane rivers as the energy of the water helps grind away rocks into gravel, sand and finer material. Much of this settles very quickly and provides an important substrate for many aquatic organisms. Many salmonid fish require beds of gravel and sand in which to lay their eggs. Many other types of solids from agriculture, mining, quarrying, urban run-off and sewage may block-out sunlight from the river and may block interstices in gravel beds making them useless for spawning and supporting insect life. | 1 | Applied and Interdisciplinary Chemistry |
An application of dendritic growth in directional solidification is gas turbine engine blades which are used at high temperatures and must handle high stresses along the major axes. At high temperatures, grain boundaries are weaker than grains. In order to minimize the effect on properties, grain boundaries are aligned parallel to the dendrites. The first alloy used in this application was a nickel-based alloy (MAR M-200) with 12.5% tungsten, which accumulated in the dendrites during solidification. This resulted in blades with high strength and creep resistance extending along the length of the casting, giving improved properties compared to the traditionally-cast equivalent. | 1 | Applied and Interdisciplinary Chemistry |
Based on the results of , the IAEA defined the delta scale with SLAP at −55.5‰ for O and −428‰ for H. That is, SLAP was measured to contain approximately 5.55% less oxygen-18 and 42.8% less deuterium than does VSMOW, and these figures were used to anchor the scale at two points. Experimental figures are given below.
* H / H – , , about 1 in 11230 atoms
* H / H – = , measured on 16 September 1976, about 1 in 2.6710 atoms
* O / O – , , about 1 in 528 atoms
* O / O – , about 1 in 3700 atoms | 0 | Theoretical and Fundamental Chemistry |
In stereochemistry, the Klyne–Prelog system (named for William Klyne and Vladimir Prelog) for describing conformations about a single bond offers a more systematic means to unambiguously name complex structures, where the torsional or dihedral angles are not found to occur in 60° increments. Klyne notation views the placement of the substituent on the front atom as being in regions of space called anti/syn and clinal/periplanar relative to a reference group on the rear atom. A plus (+) or minus (−) sign is placed at the front to indicate the sign of the dihedral angle. Anti or syn indicates the substituents are on opposite sides or the same side, respectively. Clinal substituents are found within 30° of either side of a dihedral angle of 60° (from 30° to 90°), 120° (90°–150°), 240° (210°–270°), or 300° (270°–330°). Periplanar substituents are found within 30° of either 0° (330°–30°) or 180° (150°–210°). Juxtaposing the designations produces the following terms for the conformers of butane (see Alkane stereochemistry for an explanation of conformation nomenclature): gauche butane is syn-clinal (+sc or −sc, depending on the enantiomer), anti butane is anti-periplanar, and eclipsed butane is syn-periplanar. | 0 | Theoretical and Fundamental Chemistry |
E. coli - Ecotin - EIF-W2 protein domain - electrophoresis - electroporation - ELFV dehydrogenase - Ellis–van Creveld syndrome - end labeling - endonuclease - enhancer - enterobacter ribonuclease - enzyme - epitope - ethidium bromide - evolutionary clock - evolutionary footprinting - exon - exonuclease - exosome complex - expression - expression clone - expression vector - extended ELM2 domain - | 1 | Applied and Interdisciplinary Chemistry |
The reducing atmosphere, rich in CO and H, can be created from the high-temperature cracking of natural gas at around 1100-1150 °C, in the presence of oxidized gases (HO and CO) from ore reduction reactors.
+ CO → 2 CO + H</small>
+ HO → CO + 3 H</small>
The system that generates the reducing gases is called a "reformer". In the Midrex process, it consists of tubes heated by the combustion of a portion (around a third) of the gas from the reactor. | 1 | Applied and Interdisciplinary Chemistry |
Without any loss of generality, we shall consider the study of the effective conductivity (which can be either dc or ac) for a system made up of spherical multicomponent inclusions with different arbitrary conductivities. Then the Bruggeman formula takes the form: | 0 | Theoretical and Fundamental Chemistry |
A typical solid phase extraction involves five basic steps. First, the cartridge is equilibrated with a non-polar or slightly polar solvent, which wets the surface and penetrates the bonded phase. Then water, or buffer of the same composition as the sample, is typically washed through the column to wet the silica surface. The sample is then added to the cartridge. As the sample passes through the stationary phase, the polar analytes in the sample will interact and retain on the polar sorbent while the solvent, and other non-polar impurities pass through the cartridge. After the sample is loaded, the cartridge is washed with a non-polar solvent to remove further impurities. Then, the analyte is eluted with a polar solvent or a buffer of the appropriate pH.
A stationary phase of polar functionally bonded silicas with short carbons chains frequently makes up the solid phase. This stationary phase will adsorb polar molecules which can be collected with a more polar solvent. | 0 | Theoretical and Fundamental Chemistry |
When stored in the presence of air or oxygen, ethers tend to form explosive peroxides, such as diethyl ether hydroperoxide. The reaction is accelerated by light, metal catalysts, and aldehydes. In addition to avoiding storage conditions likely to form peroxides, it is recommended, when an ether is used as a solvent, not to distill it to dryness, as any peroxides that may have formed, being less volatile than the original ether, will become concentrated in the last few drops of liquid. The presence of peroxide in old samples of ethers may be detected by shaking them with freshly prepared solution of a ferrous sulfate followed by addition of KSCN. Appearance of blood red color indicates presence of peroxides. The dangerous properties of ether peroxides are the reason that diethyl ether and other peroxide forming ethers like tetrahydrofuran (THF) or ethylene glycol dimethyl ether (1,2-dimethoxyethane) are avoided in industrial processes. | 0 | Theoretical and Fundamental Chemistry |
The moving-belt interface (MBI) was developed by McFadden et al. in 1977 and commercialized by Finnigan. This interface consisted of an endless moving belt onto which the LC column effluent was deposited in a band. On the belt, the solvent was evaporated by gently heating and efficiently exhausting the solvent vapours under reduced pressure in two vacuum chambers. After the liquid phase was removed, the belt passed over a heater which flash desorbed the analytes into the MS ion source. One of the significant advantages of the MBI was its compatibility with a wide range of chromatographic conditions. MBI was successfully used for LC–MS applications between 1978 and 1990 because it allowed coupling of LC to MS devices using EI, CI, and fast-atom bombardment (FAB) ion sources. The most common MS systems connected by MBI interfaces to LC columns were magnetic sector and quadrupole instruments. MBI interfaces for LC–MS allowed MS to be widely applied in the analysis of drugs, pesticides, steroids, alkaloids, and polycyclic aromatic hydrocarbons. This interface is no longer used because of its mechanical complexity and the difficulties associated with belt renewal (or cleaning) as well as its inability to handle very labile biomolecules. | 0 | Theoretical and Fundamental Chemistry |
Nutrients are important to the growth and survival of living organisms, and hence, are essential for development and maintenance of healthy ecosystems. Humans have greatly influenced the phosphorus cycle by mining phosphate rock. For millennia, phosphorus was primarily brought into the environment through the weathering of phosphate containing rocks, which would replenish the phosphorus normally lost to the environment through processes such as runoff, albeit on a very slow and gradual time-scale. Since the 1840s, when the technology to mine and extract phosphorus became more prevalent, approximately 110 Tg of phosphorus has been added to the environment. This trend doesn't appear to be slowing down as from 1900-2022, the amount of phosphorus mined globally has increased 72-fold, with an expected annual increase of 4%. Most of this mining is done in order to produce fertilizers which can be used on a global scale. However, at the rate humans are mining, the geological system can not restore what is lost quickly enough. Thus, researchers are examining ways to better recycle phosphorus in the environment, with one promising application including the use of microorganisms. Regardless, humans have had a powerful impact on the phosphorus cycle with wide-reaching implications about food security, eutrophication, and the overall availability of the nutrient.
Repeated application of liquid hog manure in excess to crop needs can have detrimental effects on soil phosphorus status. Also, application of biosolids may increase available phosphorus in soil. In poorly drained soils or in areas where snowmelt can cause periodic waterlogging, reducing conditions can be attained in 7–10 days. This causes a sharp increase in phosphorus concentration in solution and phosphorus can be leached. In addition, reduction of the soil causes a shift in phosphorus from resilient to more labile forms. This could eventually increase the potential for phosphorus loss. This is of particular concern for the environmentally sound management of such areas, where disposal of agricultural wastes has already become a problem. It is suggested that the water regime of soils that are to be used for organic wastes disposal is taken into account in the preparation of waste management regulations. | 0 | Theoretical and Fundamental Chemistry |
Part One aired on 23 April 2006, and focuses on the immediate aftermath of the incident and the implications which may arise for the Irish population. The plot is released in the style of "breaking news" (from both RTÉ News and BBC News 24) and as footage captured by a documentary crew and various camera phone video clips from eyewitnesses. | 0 | Theoretical and Fundamental Chemistry |
This fjord was born as a glacial lake that was separated from the open ocean (the North Sea) when it was lifted during glacial rebound. A shallow channel (2m deep) was dug in 1850, providing a marginal connection to the North Sea. A strong pycnocline separates fresh surface water from dense, saline bottom water, and this pycnocline reduces mixing between the layers. Anoxic conditions persist below the chemocline at 20m, and the fjord has the highest levels of hydrogen sulfide in the anoxic marine world. Like the Black Sea, vertical overlap of oxygen and sulfur is limited, but the decline of HS approaching the chemocline from below is indicative of oxidation of HS, which has been attributed to manganese and iron oxides, photo-autotrophic bacteria, and entrainment of oxygen horizontally from the boundaries of the fjord. These oxidation processes are similar to those present in the Black Sea.
Two strong seawater intrusion events have occurred through the channel in recent history (1902 and 1942). Seawater intrusions to fjords force dense, salty, oxygen-rich water into the typically anoxic, sulfidic bottom waters of euxinic fjords. These events result in a temporary disturbance to the chemocline, raising the depth at which HS is detected. The breakdown of the chemocline causes HS to react with dissolved oxygen in a redox reaction. This decreases the concentration of dissolved oxygen in the biologically active photic zone which can result in basin-scale fish die-offs. The 1942 event, in particular, was strong enough to chemically reduce the vast majority of oxygen and elevate the chemocline to the air-water interface. This caused a temporary state of total anoxia in the fjord, and resulted in dramatic fish mortality. | 0 | Theoretical and Fundamental Chemistry |
ViroCap is a test announced in 2015 by researchers at Washington University in St. Louis which can detect most of the infectious viruses which affect both humans and animals. It was demonstrated to be as sensitive as the various Polymerase chain reaction assays for the viruses. It will not be available for clinical use until validation studies are done, which may take years. The test examines two million sequences of genetic data from viruses. The research was published in September 2015 in the online journal Genome Research. | 1 | Applied and Interdisciplinary Chemistry |
Diazonium salts can be converted to thiols in a two-step procedure. Treatment of benzenediazonium chloride with potassium ethylxanthate followed by hydrolysis of the intermediate xanthate ester gives thiophenol: | 0 | Theoretical and Fundamental Chemistry |
The history of metallurgy in the Indian subcontinent began prior to the 3rd millennium BCE. Metals and related concepts were mentioned in various early Vedic age texts. The Rigveda already uses the Sanskrit term ayas (). The Indian cultural and commercial contacts with the Near East and the Greco-Roman world enabled an exchange of metallurgic sciences. The advent of the Mughals (established: April 21, 1526—ended: September 21, 1857) further improved the established tradition of metallurgy and metal working in India. During the period of British rule in India (first by the East India Company and then by the Crown), the metalworking industry in India stagnated due to various colonial policies, though efforts by industrialists led to the industry's revival during the 19th century. | 1 | Applied and Interdisciplinary Chemistry |
Amagat's law or the law of partial volumes describes the behaviour and properties of mixtures of ideal (as well as some cases of non-ideal) gases. It is of use in chemistry and thermodynamics. It is named after Emile Amagat. | 0 | Theoretical and Fundamental Chemistry |
Before delving into the mathematical model, it is important to understand that pycnonuclear fusion, in its essence, occurs due to two main events:
* A phenomenon of quantum nature called quantum diffusion.
* Overlap of the wave functions of zero-point oscillations of the nuclei.
Both of these effects are heavily affected by screening. The term screening is generally used by nuclear physicists when referring to plasmas of particularly high density. In order for the pycnonuclear fusion to occur, the two particles must overcome the electrostatic repulsion between them - the energy required for this is called the Coulomb barrier. Due to the presence of other charged particles (mainly electrons) next to the reacting pair, they exert the effect of shielding - as the electrons create an electron cloud around the positively charged ions - effectively reducing the electrostatic repulsion between them, lowering the Coulomb barrier. This phenomenon of shielding is referred to as "screening", and in cases where it is particularly strong, it is called "strong screening". Consequently, in cases where the plasma has a strong screening effect, the rate of pycnonuclear fusion is substantially enhanced.
Quantum tunnelling is the foundation of the quantum physical approach to pycnonuclear fusion. It is closely intertwined with the screening effect, as the transmission coefficient depends on the height of the potential barrier, the mass of the particles, and their relative velocity (since the total energy of the system depends on the kinetic energy). From this follows that the transmission coefficient is very sensitive to the effects of screening. Thus, the effect of screening not only contributes to the reduction of the potential barrier that allows for "classical" fusion to occur via the overlap of the wave functions of the zero-point oscillations of the particles, but also to the increase of the transmission coefficient, both of which increase the rate of pycnonuclear fusion.
On top of the other various jargon related to pycnonuclear fusion, the papers also introduce various regimes, that define the rate of pycnonuclear fusion. Specifically, they identify the zero-temperature, intermediate, and thermally-enhanced regimes as their main ones. | 0 | Theoretical and Fundamental Chemistry |
Chirilă was born and educated in Romania, where he obtained a BEng in polymer technology (1972) and a PhD in organic chemistry (1981) from the Polytechnic University of Timișoara.
After ten years of research in polymers and organic chemistry, he relocated to Australia. During 1984 he was a research fellow at the Curtin School of Applied Chemistry. In 1986 he joined Lions Eye Institute in Perth as a senior scientist with the task of establishing a department for research and development of polymeric biomaterials for ophthalmology. In 2005, he joined the newly founded Queensland Eye Institute in Brisbane, where he was offered a position of senior scientist to continue his research and to establish a department of ophthalmic bioengineering. He was made a fellow of Royal Australian Chemical Institute (RACI) in 1992. Currently, he holds three adjunct professorships at the School of Physical and Chemical Sciences of Queensland University of Technology, Australian Institute for Bioengineering and Nanotechnology of University of Queensland, and Faculty of Health Sciences of University of Queensland. | 0 | Theoretical and Fundamental Chemistry |
Several systems have been proposed which combine MRI capability with lanthanides probes in dual assays. The luminescent probe may for instance serve to localize the MRI contrast agent. This has helped to visualize the delivery of nucleic acids into cultured cells. Lanthanides are not used for their fluorescence but their magnetic qualities. | 1 | Applied and Interdisciplinary Chemistry |
Book chapters are cited in short form above and long form below. All other sources are cited above only.
*Coups, Elliot J. and Phillips, L. Alison (2012). "Prevalence and Correlates of Indoor Tanning", in Carolyn J. Heckman, Sharon L. Manne (eds.), Shedding Light on Indoor Tanning. Dordrecht: Springer Science & Business Media, 5–32.
*Hay, Jennifer and Lipsky, Samara (2012), "International Perspectives on Indoor Tanning", in Heckman and Manne (eds)., 179–193.
*Hunt, Yvonne; Augustson, Erik; Rutten, Lila; Moser, Richard; and Yaroch, Amy (2012). "History and Culture of Tanning in the United States", in Heckman and Manne (eds.), 33–68.
*Lessin, Stuart R; Perlis, Clifford S.; Zook, and Matthew B. Zook (2012). "How Ultraviolet Radiation Tans Skin" in Heckman and Manne (eds.), 87–94.
*Lluria-Prevatt, Maria; Dickinson, Sally E.; and Alberts, David S. (2013). "Skin Cancer Prevention", in David Alberts, Lisa M. Hess (eds.). Fundamentals of Cancer Prevention. Heidelberg and Berlin: Springer Verlag, 321–376. | 0 | Theoretical and Fundamental Chemistry |
In organic chemistry, thiocarbamates (thiourethanes) are a family of organosulfur compounds. As the prefix thio- suggests, they are sulfur analogues of carbamates. There are two isomeric forms of thiocarbamates: O-thiocarbamates, (esters), and S-thiocarbamates, (thioesters). | 0 | Theoretical and Fundamental Chemistry |
A major improvement to the product imaging technique was achieved by Eppink and Parker. A difficulty that limits the resolution in the position-sensing version is that the spot on the detector is no smaller than the cross-sectional area of the ions excited. For example, if the volume of interaction of the molecular beam, photolysis laser, and ionization laser is, say 1 mm x 1 mm x 1 mm, then the spot for an ion moving with a single velocity would still span 1mm x 1mm at the detector. This dimension is much larger than the limit of a channel width (10 μm) and is substantial compared to the radius of a typical detector (25 mm). Without some further improvement, the velocity resolution for a position-sensing apparatus would be limited to about one part in twenty-five. Eppink and Parker found a way around this limit. Their version of the product imaging technique is called velocity map imaging.
Velocity map imaging is based on the use of an electrostatic lens to accelerate the ions toward the detector. When the voltages are properly adjusted, this lens has the advantage that it focuses ions with the same velocity to a single spot on the detector regardless where the ion was created. This technique thus overcomes the blurring caused by the finite overlap of the laser and molecular beams.
In addition to ion imaging, velocity map imaging is also used for electron kinetic energy analysis in photoelectron photoion coincidence spectroscopy. | 0 | Theoretical and Fundamental Chemistry |
Nebulized meropenem (inhaled route) is researched, but is not approved, for prevention of bronchiectasis exacerbation. | 0 | Theoretical and Fundamental Chemistry |
The fugacity is most useful in mixtures. It does not add any new information compared to the chemical potential, but it has computational advantages. As the molar fraction of a component goes to zero, the chemical potential diverges but the fugacity goes to zero. In addition, there are natural reference states for fugacity (for example, an ideal gas makes a natural reference state for gas mixtures since the fugacity and pressure converge at low pressure). | 0 | Theoretical and Fundamental Chemistry |
The first flush from urban runoff can be extremely dirty. Storm water may become contaminated while running down the road or other impervious surface, or from lawn chemical run-off, before entering the drain.
Water running off these impervious surfaces tends to pick up gasoline, motor oil, heavy metals, trash and other pollutants from roadways and parking lots, as well as fertilizers and pesticides from lawns. Roads and parking lots are major sources of nickel, copper, zinc, cadmium, lead and polycyclic aromatic hydrocarbons (PAHs), which are created as combustion byproducts of gasoline and other fossil fuels. Roof runoff contributes high levels of synthetic organic compounds and zinc (from galvanized gutters). Fertilizer use on residential lawns, parks and golf courses is a significant source of nitrates and phosphorus.
Separation of undesired runoff can be achieved by installing devices within the storm sewer system. These devices are relatively new and can only be installed with new development or during major upgrades. They are referred to as oil-grit separators (OGS) or oil-sediment separators (OSS). They consist of a specialized manhole chamber, and use the water flow and/or gravity to separate oil and grit. | 1 | Applied and Interdisciplinary Chemistry |
* Respiratory sensitizers cause breathing hypersensitivity when the substance is inhaled.
* A substance which is a skin sensitizer causes an allergic response from a dermal application.
* Carcinogens induce cancer, or increase the likelihood of cancer occurring.
*Neurotoxicity is a form of toxicity in which a biological, chemical, or physical agent produces an adverse effect on the structure or function of the central and/or peripheral nervous system. It occurs when exposure to a substance – specifically, a neurotoxin or neurotoxicant– alters the normal activity of the nervous system in such a way as to cause permanent or reversible damage to nervous tissue.
* Reproductively toxic substances cause adverse effects in either sexual function or fertility to either a parent or the offspring.
* Specific-target organ toxins damage only specific organs.
* Aspiration hazards are solids or liquids which can cause damage through inhalation. | 1 | Applied and Interdisciplinary Chemistry |
Reversibly assembled cellular composite materials (RCCM) are three-dimensional lattices of modular structures that can be partially disassembled to enable repairs or other modifications. Each cell incorporates structural material and a reversible interlock, allowing lattices of arbitrary size and shape. RCCM display three-dimensional symmetry derived from the geometry as linked.
The discrete construction of reversibly assembled cellular composites introduces a new degree of freedom that determines global functional properties from the local placement of heterogeneous components. Because the individual parts are literally finite elements, a hierarchical decomposition describes the part types and their combination in a structure.
RCCM can be viewed as a "digital" material in which discrete parts link with a discrete set of relative positions and orientations. An assembler can place them using only local information. Placement errors can be detected and corrected by assembly reversal. These materials combine the size and strength of composites with the low density of cellular materials and the convenience of additive manufacturing. | 0 | Theoretical and Fundamental Chemistry |
Professor Oladipo is active in various civic roles, including serving as a Nominee Director for Odu’a Investment Company Ltd in 1992, a Part-time Member of the Osun State Sports Council from 1998 to 1999, and a Part-time Member of the Osun State Local Govt. Service Commission from Feb. 2000 to 2002. He also served as a Member of the Ife Development Board for three years.
In 2008, he was appointed as the Chairman of the Osun State Universal Basic Education Board (SUBEB). Additionally, he served as the Chairman of the Governing Board of the Federal Neuropsychiatric Hospital, Yaba, from 2009 to 2011.
In July 2013, he was nominated as the National Secretary of the Peoples Democratic Party (PDP) and was subsequently elected for a substantive four-year tenure in December 2014 at the Party's Special National Convention held in Abuja. | 0 | Theoretical and Fundamental Chemistry |
Margules expressed the intensive excess Gibbs free energy of a binary liquid mixture as a power series of the mole fractions x:
In here the A, B are constants, which are derived from regressing experimental phase equilibria data.
Frequently the B and higher order parameters are set to zero. The leading term assures that the excess Gibbs energy becomes zero at x=0 and x=1. | 0 | Theoretical and Fundamental Chemistry |
Survival of pathogens in waste materials, soil, or water, depends on many environmental factors including temperature, pH, organic matter content, moisture, exposure to light, and the presence of other organisms. Fecal material can be directly deposited, washed into waters by overland runoff, transported through the ground, or discharged to surface waters via sewer lines, pipes, or drainage tiles. Risk of exposure to humans requires:
# Pathogens to survive and be present;
# Pathogens to recreate in surface waters;
# Individuals to come in contact with water for sufficient time, or ingest sufficient volumes of water to receive an infectious dose.
Die-off rates of bacteria in the environment are often exponential, therefore, direct deposition of fecal material into waters generally contribute higher concentrations of pathogens than material that must be transported overland or through the subsurface. | 0 | Theoretical and Fundamental Chemistry |
He was awarded a PhD is in physical chemistry from Battersea College of Technology. During his study he married a German in London in October 1963; their common language is English. Mrs al-Saadi raised their children in Hamburg.
He retired a lieutenant general in 1994 and was made a presidential scientific advisor. | 0 | Theoretical and Fundamental Chemistry |
Targeted temperature management (TTM) previously known as therapeutic hypothermia or protective hypothermia is an active treatment that tries to achieve and maintain a specific body temperature in a person for a specific duration of time in an effort to improve health outcomes during recovery after a period of stopped blood flow to the brain. This is done in an attempt to reduce the risk of tissue injury following lack of blood flow. Periods of poor blood flow may be due to cardiac arrest or the blockage of an artery by a clot as in the case of a stroke.
Targeted temperature management improves survival and brain function following resuscitation from cardiac arrest. Evidence supports its use following certain types of cardiac arrest in which an individual does not regain consciousness. The target temperature is often between 32–34 °C. Targeted temperature management following traumatic brain injury is of unclear benefit. While associated with some complications, these are generally mild.
Targeted temperature management is thought to prevent brain injury by several methods, including decreasing the brain's oxygen demand, reducing the production of neurotransmitters like glutamate, as well as reducing free radicals that might damage the brain. Body temperature may be lowered by many means, including cooling blankets, cooling helmets, cooling catheters, ice packs and ice water lavage. | 1 | Applied and Interdisciplinary Chemistry |
The modern X-ray fluorescence (XRF) is also a non-destructive technique that is suitable for normal assaying requirements. It typically has an accuracy of 2 to 5 parts per thousand and is well-suited to relatively flat and large surfaces. It is a quick technique taking about three minutes, and the results can be automatically printed out by computer.
One process for X-ray fluorescence assay involves melting the material in a furnace and stirring to make a homogeneous mix. Following this, a sample is taken from the centre of the molten sample. Samples are typically taken using a vacuum pin tube. The sample is then tested by X-ray fluorescence spectroscopy. Metallurgical assay is typically completed in this way to ensure that an accurate assay is performed. | 1 | Applied and Interdisciplinary Chemistry |
Introducing the transformation transforms the equation to
The equation has a singular solution given by
Therefore, a new variable can be introduced as , where the equation for can be derived,
This equation can be reduced to first order by introducing
then we have | 1 | Applied and Interdisciplinary Chemistry |
Testing conducted by the Virginia Department of Transportation and university researchers from 2011 to 2013 showed that some CIPP installations can cause aquatic toxicity. A list of environmental, public health, and infrastructure incidents caused by CIPP installations as of 2013 was published by the Journal of Environmental Engineering. In 2014, university researchers published a more detailed study in Environmental Science & Technology that examined CIPP condensate chemical and aquatic toxicity as well as chemical leaching from stormwater culvert CIPP installations in Alabama. In this new report additional water and air environmental contamination incidents were reported not previously described elsewhere.
In 2017, CALTRANS backed university researchers examined water impacts caused by CIPPs used for stormwater culvert repairs.
In April 2018, a study funded by six state transportation agencies (1) compiled and reviewed CIPP-related surface water contamination incidents from publicly reported data; (2) analyzed CIPP water quality impacts; (3) evaluated current construction practices for CIPP installations as reported by US state transportation agencies; and (4) reviewed current standards, textbooks, and guideline documents. In 2019, another study funded by these agencies identified actions to reduce chemical release from ultraviolet light (UV) CIPP manufacturing sites.
With proper engineering design specifications, contractor installation procedures, and construction oversight many of these problems can likely be prevented. | 1 | Applied and Interdisciplinary Chemistry |
In catalytic kinetics, two basic approximations are useful (in different circumstances) to describe the behavior of many systems. The situations in which the pre-equilibrium and steady-state approximations are valid can often be distinguished by reaction progress kinetic analysis, and the two situations are closely related to the resting state of the catalyst. | 0 | Theoretical and Fundamental Chemistry |
The art of cutting a gem is an exacting procedure performed on a faceting machine. The ideal product of facet cutting is a gemstone that displays a pleasing balance of internal reflections of light known as brilliance, strong and colorful dispersion which is commonly referred to as "fire", and brightly colored flashes of reflected light known as scintillation. Typically transparent to translucent stones are faceted, although opaque materials may occasionally be faceted as the luster of the gem will produce appealing reflections. Pleonaste (black spinel) and black diamond are examples of opaque faceted gemstones. | 0 | Theoretical and Fundamental Chemistry |
Freezing is almost always an exothermic process, meaning that as liquid changes into solid, heat and pressure are released. This is often seen as counter-intuitive, since the temperature of the material does not rise during freezing, except if the liquid were supercooled. But this can be understood since heat must be continually removed from the freezing liquid or the freezing process will stop. The energy released upon freezing is a latent heat, and is known as the enthalpy of fusion and is exactly the same as the energy required to melt the same amount of the solid.
Low-temperature helium is the only known exception to the general rule. Helium-3 has a negative enthalpy of fusion at temperatures below 0.3 K. Helium-4 also has a very slightly negative enthalpy of fusion below 0.8 K. This means that, at appropriate constant pressures, heat must be added to these substances in order to freeze them. | 1 | Applied and Interdisciplinary Chemistry |
In alkali lakes (also called soda lakes), evaporation concentrates the naturally occurring carbonate salts, giving rise to an alkalic and often saline lake.
Examples of alkali lakes:
*Alkali Lake, Lake County, Oregon
*Baldwin Lake, San Bernardino County, California
* Bear Lake on the Utah–Idaho border
*Lake Magadi in Kenya
*Lake Turkana in Kenya
*Mono Lake, near Owens Valley in California
*Redberry Lake, Saskatchewan
*Summer Lake, Lake County, Oregon
*Tramping Lake, Saskatchewan | 0 | Theoretical and Fundamental Chemistry |
The release of compressed air in the water adds oxygen to the local environment. This may be particularly useful in areas that have become a dead zone due to eutrophication.
Air curtains may have another application. Dolphin and whale beaching has increased with the rise in ocean temperatures. On Thursday February 12th, 2017, a group of nearly 400 whales beached near Golden Bay on the tip of New Zealand’s South Island, following a similar incident earlier that week. The simplicity of an air curtain system, requiring only air compressors and perforated hoses, could allow for rapid deployment and create aerated zones of oxygenated seawater during a marine emergency.
Air curtains are also used to control the release of smoke particles into the environment. After a natural disaster, or during brush clearing activities, debris is disposed of by incineration in either a ceramic or earth pit containment. Similar to an air curtain to separate indoor air from outdoor air, for instance in restaurants and walk-in refrigerators, a powerful air curtain can defeat the chimney effect of the incineration process to eliminate any smoke from a brush incinerator. The air curtain acts as a lid on the process, and forces the smoke back into the fuel bed for a cleaner burn. | 1 | Applied and Interdisciplinary Chemistry |
The source material was pig iron produced by a blast furnace using charcoal and the manganese rich iron ore from the Dannemora mine. A V-shaped hearth using charcoal was used to heat up the pig iron bar that was presented to a tuyere that decarbonized it and made it melt and fall in drops that solidified in a pool of slag where the decarburization continued. The iron drops were picked up with an iron bar and presented again in front of the tuyere and one by one agglomerated into a ball. That heterogeneous iron was full of slag and the carbon content ranged from pure iron to nearly pig iron. It was therefore reheated in a chafery and hammered and folded using a waterwheel powered trip hammer.
The ore from Dannemora was very low in sulphur and high in manganese. It is possible the manganese bonded with the impurities during the oxidation, creating a pretty pure wrought iron. The use of charcoal prevented the contamination with impurities usually associated with the usage of coal or coke, of which Sweden has none. In England, the chafery might use coal or coke, as in this stage the iron is solidified and the contamination remain low.
The iron was sold to England, where it was recarbonized into blister steel using the cementation process. This steel still contain some slag, and if the carbon was around 1% at the surface, it was lower in the center. The blister steel was than purchased by Benjamin Huntsman who melted it in a crucible heated using coke and poured it. This modern crucible steel was different from the medieval wootz, but was homogeneous and without slag. | 1 | Applied and Interdisciplinary Chemistry |
Pyrophosphites (diphosphites) can be produced by gently heating acid phosphites under reduced pressure. They contain the ion , which can be formulated [HP(O)O−P(O)H]. | 0 | Theoretical and Fundamental Chemistry |
Pavel Jungwirth (born 20 May 1966 in Prague, Czech Republic) is a Czech physical chemist. Since 2004, he has been the head of the Senior Research Group at the Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences. He has also been a professor in the Faculty of Mathematics and Physics at Charles University since 2000. He has also been a senior editor of the Journal of Physical Chemistry since 2009. He is popularly known for studying the explosive reaction between alkali metals, such as sodium and potassium, and water; his research on this subject indicates that these reactions result from a Coulomb explosion. He and his colleagues have also discovered a way to slow down this reaction, which they used to determine the source of a blue flash that is briefly produced during the reaction.
Pavel Jungwirth is a coordinator of an international science competition Dream Chemistry Award. | 0 | Theoretical and Fundamental Chemistry |
Lattice scattering is the scattering of ions by interaction with atoms in a lattice. This effect can be qualitatively understood as phonons colliding with charge carriers.
In the current quantum mechanical picture of conductivity the ease with which electrons traverse a crystal lattice is dependent on the near perfectly regular spacing of ions in that lattice. Only when a lattice contains perfectly regular spacing can the ion-lattice interaction (scattering) lead to almost transparent behavior of the lattice.
In the quantum understanding, an electron is viewed as a wave traveling through a medium. When the wavelength of the electrons is larger than the crystal spacing, the electrons will propagate freely throughout the metal without collision. | 0 | Theoretical and Fundamental Chemistry |
The Betts electrolytic process is an industrial process for purification of lead from bullion. Lead obtained from its ores is impure because lead is a good solvent for many metals. Often these impurities are tolerated, but the Betts electrolytic process is used when high purity lead is required, especially for bismuth-free lead. | 1 | Applied and Interdisciplinary Chemistry |
Tidal bores can be dangerous. Certain rivers such as the Seine in France, the Petitcodiac River in Canada, and the Colorado River in Mexico to name a few, have had a sinister reputation in association with tidal bores. In China, despite warning signs erected along the banks of the Qiantang River, a number of fatalities occur each year by people who take too much risk with the bore. The tidal bores affect the shipping and navigation in the estuarine zone, for example, in Papua New Guinea (in the Fly and Bamu Rivers), Malaysia (the Benak in the Batang Lupar), and India (the Hooghly River bore).
On the other hand, tidal bore-affected estuaries are rich feeding zones and breeding grounds of several forms of wildlife. The estuarine zones are the spawning and breeding grounds of several native fish species, while the aeration induced by the tidal bore contributes to the abundant growth of many species of fish and shrimp (for example in the Rokan River, Indonesia). The tidal bores also provide opportunity for recreational inland surfing, such as the Seven Ghosts bore on the Kampar River, Indonesia. | 1 | Applied and Interdisciplinary Chemistry |
Ligand-gated ion channels (LICs, LGIC), also commonly referred to as ionotropic receptors, are a group of transmembrane ion-channel proteins which open to allow ions such as Na, K, Ca, and/or Cl to pass through the membrane in response to the binding of a chemical messenger (i.e. a ligand), such as a neurotransmitter.
When a presynaptic neuron is excited, it releases a neurotransmitter from vesicles into the synaptic cleft. The neurotransmitter then binds to receptors located on the postsynaptic neuron. If these receptors are ligand-gated ion channels, a resulting conformational change opens the ion channels, which leads to a flow of ions across the cell membrane. This, in turn, results in either a depolarization, for an excitatory receptor response, or a hyperpolarization, for an inhibitory response.
These receptor proteins are typically composed of at least two different domains: a transmembrane domain which includes the ion pore, and an extracellular domain which includes the ligand binding location (an allosteric binding site). This modularity has enabled a divide and conquer approach to finding the structure of the proteins (crystallising each domain separately). The function of such receptors located at synapses is to convert the chemical signal of presynaptically released neurotransmitter directly and very quickly into a postsynaptic electrical signal. Many LICs are additionally modulated by allosteric ligands, by channel blockers, ions, or the membrane potential. LICs are classified into three superfamilies which lack evolutionary relationship: cys-loop receptors, ionotropic glutamate receptors and ATP-gated channels. | 1 | Applied and Interdisciplinary Chemistry |
Miller indices form a notation system in crystallography for lattice planes in crystal (Bravais) lattices.
In particular, a family of lattice planes of a given (direct) Bravais lattice is determined by three integers h, k, and ℓ, the Miller indices. They are written (hkℓ), and denote the family of (parallel) lattice planes (of the given Bravais lattice) orthogonal to , where are the basis or primitive translation vectors of the reciprocal lattice for the given Bravais lattice. (Note that the plane is not always orthogonal to the linear combination of direct or original lattice vectors because the direct lattice vectors need not be mutually orthogonal.) This is based on the fact that a reciprocal lattice vector (the vector indicating a reciprocal lattice point from the reciprocal lattice origin) is the wavevector of a plane wave in the Fourier series of a spatial function (e.g., electronic density function) which periodicity follows the original Bravais lattice, so wavefronts of the plane wave are coincident with parallel lattice planes of the original lattice. Since a measured scattering vector in X-ray crystallography, with as the outgoing (scattered from a crystal lattice) X-ray wavevector and as the incoming (toward the crystal lattice) X-ray wavevector, is equal to a reciprocal lattice vector as stated by the Laue equations, the measured scattered X-ray peak at each measured scattering vector is marked by Miller indices. By convention, negative integers are written with a bar, as in for −3. The integers are usually written in lowest terms, i.e. their greatest common divisor should be 1. Miller indices are also used to designate reflections in X-ray crystallography. In this case the integers are not necessarily in lowest terms, and can be thought of as corresponding to planes spaced such that the reflections from adjacent planes would have a phase difference of exactly one wavelength (2), regardless of whether there are atoms on all these planes or not.
There are also several related notations:
*the notation denotes the set of all planes that are equivalent to by the symmetry of the lattice.
In the context of crystal directions (not planes), the corresponding notations are:
* with square instead of round brackets, denotes a direction in the basis of the direct lattice vectors instead of the reciprocal lattice; and
*similarly, the notation denotes the set of all directions that are equivalent to by symmetry.
Note, for Laue–Bragg interferences
* lacks any bracketing when designating a reflection
Miller indices were introduced in 1839 by the British mineralogist William Hallowes Miller, although an almost identical system (Weiss parameters) had already been used by German mineralogist Christian Samuel Weiss since 1817. The method was also historically known as the Millerian system, and the indices as Millerian, although this is now rare.
The Miller indices are defined with respect to any choice of unit cell and not only with respect to primitive basis vectors, as is sometimes stated. | 0 | Theoretical and Fundamental Chemistry |
Isotopic reference materials are compounds (solids, liquids, gasses) with well-defined isotopic compositions and are the ultimate sources of accuracy in mass spectrometric measurements of isotope ratios. Isotopic references are used because mass spectrometers are highly fractionating. As a result, the isotopic ratio that the instrument measures can be very different from that in the samples measurement. Moreover, the degree of instrument fractionation changes during measurement, often on a timescale shorter than the measurements duration, and can depend on the characteristics of the sample itself. By measuring a material of known isotopic composition, fractionation within the mass spectrometer can be removed during post-measurement data processing. Without isotope references, measurements by mass spectrometry would be much less accurate and could not be used in comparisons across different analytical facilities. Due to their critical role in measuring isotope ratios, and in part, due to historical legacy, isotopic reference materials define the scales on which isotope ratios are reported in the peer-reviewed scientific literature.
Isotope reference materials are generated, maintained, and sold by the International Atomic Energy Agency (IAEA), the National Institute of Standards and Technology (NIST), the United States Geologic Survey (USGS), the Institute for Reference Materials and Measurements (IRMM), and a variety of universities and scientific supply companies. Each of the major stable isotope systems (hydrogen, carbon, oxygen, nitrogen, and sulfur) has a wide variety of references encompassing distinct molecular structures. For example, nitrogen isotope reference materials include N-bearing molecules such ammonia (NH), atmospheric dinitrogen (N), and nitrate (NO). Isotopic abundances are commonly reported using the δ notation, which is the ratio of two isotopes (R) in a sample relative to the same ratio in a reference material, often reported in per mille (‰) (equation below). Reference material span a wide range of isotopic compositions, including enrichments (positive δ) and depletions (negative δ). While the δ values of references are widely available, estimates of the absolute isotope ratios (R) in these materials are seldom reported. This article aggregates the δ and R values of common and non-traditional stable isotope reference materials. | 0 | Theoretical and Fundamental Chemistry |
1-Chloro-1,1-difluoroethane is a highly flammable, colorless gas under most atmospheric conditions. It has a boiling point of -10 °C. Its critical temperature is near 137 °C. | 1 | Applied and Interdisciplinary Chemistry |
In collaboration with Hopkins Marine Station and the Center for Ocean Solutions, Monterey Bay Aquarium Research Institute is developing a swFOCE system to examine the effects of ocean acidification on shallow subtidal communities in central California. swFOCE will use a shore side station for the control system and production of CO enriched seawater, and will also use and will use an existing cabled observational and research platform to connect the swFOCE node. Two swFOCE chambers will be installed initially at a depth of 15 m, approximately 250 m offshore. The nearby node of the cabled observatorynode, has instruments to monitor local currents, temperature, pH, and O2 in real-time, as a cabled observatory platform for scientific research. | 0 | Theoretical and Fundamental Chemistry |
The first metal carbonyl clusters, Fe(CO), Ir(CO), and Rh(CO), were reported starting in the 1930s, often by Walter Hieber. The structures were subsequently established by X-ray crystallography.
Paolo Chini (1928–1980) was a pioneer for the synthesis and characterization of high-nuclearity metal carbonyl clusters. His first studies started in 1958, in the attempt to repeat a patent that claimed an improved selectivity in hydroformylation. From a mixture of iron and cobalt carbonyls the first bimetallic carbonyl cluster HFeCo(CO) was obtained. | 0 | Theoretical and Fundamental Chemistry |
In organic chemistry, a sulfone is a organosulfur compound containing a sulfonyl () functional group attached to two carbon atoms. The central hexavalent sulfur atom is double-bonded to each of two oxygen atoms and has a single bond to each of two carbon atoms, usually in two separate hydrocarbon substituents. | 0 | Theoretical and Fundamental Chemistry |
In studies of enzymes, the current results from the catalytic oxydation or reduction of the enzyme's substrate.
The electroactive coverage of large redox enzymes (such as laccase, hydrogenase etc.) is often too low to detect any signal in the absence of substrate, but the electrochemical signal is amplified by catalysis: indeed, the catalytic current is proportional to turnover rate times electroactive coverage. The effect of varying the electrode potential, the pH or the concentration of substrates and inhibitors etc. can be examined to learn about various steps in the catalytic mechanism. | 0 | Theoretical and Fundamental Chemistry |
Iodic acid can be produced by oxidizing iodine with strong oxidizers such as nitric acid , chlorine , chloric acid or hydrogen peroxide , for example:
Iodic acid is also produced by the reaction of iodine monochloride with water: | 0 | Theoretical and Fundamental Chemistry |
It has been suggested certain microbial dark matter genetic material could belong to a new (i.e., fourth) domain of life, although other explanations (e.g., viral origin) are also possible, which has ties with the issue of a hypothetical shadow biosphere. | 1 | Applied and Interdisciplinary Chemistry |
A streaming current and streaming potential are two interrelated electrokinetic phenomena studied in the areas of surface chemistry and electrochemistry. They are an electric current or potential which originates when an electrolyte is driven by a pressure gradient through a channel or porous plug with charged walls.
The first observation of the streaming potential is generally attributed to the German physicist Georg Hermann Quincke in 1859. | 0 | Theoretical and Fundamental Chemistry |
Emeléus served as president of the inorganic chemistry division of the International Union of Pure and Applied Chemistry (1955–60). He was also president of the Chemical Society (1958–60) and of the Royal Institute of Chemistry (1963–5). | 0 | Theoretical and Fundamental Chemistry |
[https://nadp.slh.wisc.edu/pubs/brochures/ Brochures]
[https://nadp.slh.wisc.edu/pubs/Annual-Data-Summaries/ Annual Data Summaries]
[https://nadp.slh.wisc.edu/quality-assurance/#QAreports Quality Assurance Reports]
[https://nadp.slh.wisc.edu/committees/clad/ CLAD Science Committee Reports]
[https://nadp.slh.wisc.edu/committees/tdep/ TDep Science Committee Reports]
[https://nadp.slh.wisc.edu/committees/amsc/ AMSC Study Plan]
[https://nadp.slh.wisc.edu/committees/meld/ MELD Science Committee Reports] | 1 | Applied and Interdisciplinary Chemistry |
In the presence of an oxidizing agent, the cyclized intermediate can be oxidized to aromatize the rings. For example, dihydrophenanthrene becomes phenanthrene. Oxygen and iodine are the most commonly employed oxidants. | 0 | Theoretical and Fundamental Chemistry |
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