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In polar solvents such as acetonitrile, PhPCl adopts an ionic phosphonium salt structure, [PhPCl]Cl, whereas in non-polar solvents like diethyl ether it exists as a non-solvated trigonal bipyramidal molecule. Two [PhPCl] species can also adopt an unusual dinuclear ionic structure—both interacting with a Cl via long Cl–Cl contacts. | 0 | Theoretical and Fundamental Chemistry |
In elementary arithmetic geometry, stereographic projection from the unit circle provides a means to describe all primitive Pythagorean triples. Specifically, stereographic projection from the north pole (0,1) onto the -axis gives a one-to-one correspondence between the rational number points on the unit circle (with ) and the rational points of the -axis. If is a rational point on the -axis, then its inverse stereographic projection is the point
which gives Euclid's formula for a Pythagorean triple. | 0 | Theoretical and Fundamental Chemistry |
The microprocess design philosophy has been largely envisioned by historical analysis of the role that component miniaturization has played in the information technology industry. It is the evolution of the miniaturization of computer hardware that has enabled the thinking about process miniaturization, in the chemical engineering design context. Rather than the traditional design objective as “scale-up” of processing to one centralized large processing plant (e.g. the mainframe), one can envision achieving the economic objectives using a “scale-out” philosophy (e.g. multiple microcomputers).
Electrical and electronic devices have always played an important role in chemical process plant automation. However, initially, simple thermometers such as those containing mercury, and pressure gauges which were completely mechanical in nature were used to monitor process conditions (such as the temperature, pressure and level in a chemical reactor). Process conditions were adjusted based largely on a human operator's heuristic knowledge of the process behavior. Even with electronic automation installed, many process still require substantial operator interaction, particularly during the start-up phase of the process, or during deployment of a new technology.
Process control of the future will involve the widespread utilization of intelligent sensors, and mass-produced intelligent miniaturized devices such as programmable logic controllers that communicate wirelessly to process actuators. Since these devices will be miniaturized to reduce manufacturing cost, this enables the devices to be embedded in structures so that they become invisible to the casual observer. The cost of such sensors will likely be reduced to a point where they either "function or don't function". When that cost threshold has been reached, the repair procedure will be to disable the sensor, and to actuate a redundant working sensor. In otherwords, entire complex control systems will become so low cost, that repair will not be economically viable.
The intelligence of the process will be developed using process simulation models based on scientific fundamentals. Heuristic rules will be programmed into the micro-controllers, which will largely eliminate the need for constant monitoring by human heuristic knowledge of the process behavior. Process which can automatically self-optimize through advanced algorithms developed by microprocess engineers will be embedded, and only accessible to the knowledge-owner. This will enable the construction of large networks of autonomous microprocesses. | 1 | Applied and Interdisciplinary Chemistry |
In omission libraries a certain amino acid is missing from all peptides of the mixture. The figure shows the full library and the three omission libraries. At the top the omitted amino acids are shown. If the omission library gives a negative test the omitted amino acid is present in the active component. | 1 | Applied and Interdisciplinary Chemistry |
The proper utilization of pervious concrete is a recognized Best Management Practice by the U.S. Environmental Protection Agency (EPA) for providing first flush pollution control and stormwater management. As regulations further limit stormwater runoff, it is becoming more expensive for property owners to develop real estate, due to the size and expense of the necessary drainage systems. Pervious concrete lowers the NRCS Runoff Curve Number or CN by retaining stormwater on site. This allows the planner/designer to achieve pre-development stormwater goals for pavement intense projects. Pervious concrete reduces the runoff from paved areas, which reduces the need for separate stormwater retention ponds and allows the use of smaller capacity storm sewers. This allows property owners to develop a larger area of available property at a lower cost. Pervious concrete also naturally filters storm water and can reduce pollutant loads entering into streams, ponds, and rivers.
Pervious concrete functions like a storm water infiltration basin and allows the storm water to infiltrate the soil over a large area, thus facilitating recharge of precious groundwater supplies locally. All of these benefits lead to more effective land use. Pervious concrete can also reduce the impact of development on trees. A pervious concrete pavement allows the transfer of both water and air to root systems to help trees flourish even in highly developed areas. | 1 | Applied and Interdisciplinary Chemistry |
EMFIT sensor film has a diverse range of applications due to it being flexible, durable, and sensitive to a wide range of frequencies. These properties are attributed to its base material: cellular voided Ferro-electret film. Due to these properties, in conjunction with the two modes of operation, it has already seen use in vandalism-proof keyboards, guitar pickups, flat speakers, and vital signs ballistocardiography sensors. esmicrophones.
* In active noise cancellation, a part of a sensor product can be used in the sensor mode to identify sound signals, and a part can be used as an actuator and then be used to produce sound signals that cancel out the first.
* EMFIT sensors has been implemented in physiological bio-signal sensors where no direct contact with the skin is required, such as a BCG, as its application is non-invasive. | 1 | Applied and Interdisciplinary Chemistry |
Radiocarbon dating is a radiometric dating method that uses () to determine the age of carbonaceous materials up to about 60,000 years old. The technique was developed by Willard Libby and his colleagues in 1949 during his tenure as a professor at the University of Chicago. Libby estimated that the radioactivity of exchangeable carbon-14 would be about 14 disintegrations per minute (dpm) per gram of pure carbon, and this is still used as the activity of the modern radiocarbon standard. In 1960, Libby was awarded the Nobel Prize in chemistry for this work.
One of the frequent uses of the technique is to date organic remains from archaeological sites. Plants fix atmospheric carbon during photosynthesis, so the level of in plants and animals when they die approximately equals the level of in the atmosphere at that time. However, it decreases thereafter from radioactive decay, allowing the date of death or fixation to be estimated. The initial level for the calculation can either be estimated, or else directly compared with known year-by-year data from tree-ring data (dendrochronology) up to 10,000 years ago (using overlapping data from live and dead trees in a given area), or else from cave deposits (speleothems), back to about 45,000 years before the present. A calculation or (more accurately) a direct comparison of carbon-14 levels in a sample, with tree ring or cave-deposit carbon-14 levels of a known age, then gives the wood or animal sample age-since-formation. Radiocarbon is also used to detect disturbance in natural ecosystems; for example, in peatland landscapes, radiocarbon can indicate that carbon which was previously stored in organic soils is being released due to land clearance or climate change.
Cosmogenic nuclides are also used as proxy data to characterize cosmic particle and solar activity of the distant past. | 0 | Theoretical and Fundamental Chemistry |
COOLFluiD is a component based scientific computing environment that handles high-performance computing problems with focus on complex computational fluid dynamics (CFD) involving multiphysics phenomena.
It features a Collaborative Simulation Environment where multiple physical models and multiple discretization methods are implemented as components within the environment. These components form a component-based architecture where they serve as building blocks of customized applications. | 1 | Applied and Interdisciplinary Chemistry |
MVR is thought to affect signal strength in postsynaptic neurons that typically have low receptor occupancy; this number can vary widely throughout the nervous system. This means that for however many receptors are found on a postsynaptic cell in the area of presynaptic cell vesicle release, only a small number of them would typically be occupied by neurotransmitter released from one vesicle (each vesicle can contain up to approximately 10,000 molecules of neurotransmitter). MVR increases the likelihood that an action potential in a presynaptic cell will result in a postsynaptic cell chance in action potential likelihood. This could be either more or fewer action potentials, depending upon if the neurotransmitter / receptor combo is excitatory or inhibitory. | 1 | Applied and Interdisciplinary Chemistry |
Avogadro's law states that:
This statement gives rise to the molar volume of a gas, which at STP (273.15 K, 1 atm) is about 22.4 L. The relation is given by:
:, orwhere n is equal to the number of molecules of gas (or the number of moles of gas). | 0 | Theoretical and Fundamental Chemistry |
Solid-state physics is the study of rigid matter, or solids, through methods such as solid-state chemistry, quantum mechanics, crystallography, electromagnetism, and metallurgy. It is the largest branch of condensed matter physics. Solid-state physics studies how the large-scale properties of solid materials result from their atomic-scale properties. Thus, solid-state physics forms a theoretical basis of materials science. Along with solid-state chemistry, it also has direct applications in the technology of transistors and semiconductors. | 1 | Applied and Interdisciplinary Chemistry |
The classic example of targeted development is imatinib mesylate (Gleevec), a small molecule which inhibits a signaling molecule kinase. The genetic abnormality causing chronic myelogenous leukemia (CML) has been known for a long time to be a chromosomal translocation creating an abnormal fusion protein, kinase BCR-ABL, which signals aberrantly, leading to uncontrolled proliferation of the leukemia cells. Imatinib precisely inhibits this kinase. Unlike so many other anti-cancer agents, this pharmaceutical was no accident. Brian Druker, working in Oregon Health & Science University, had extensively researched the abnormal enzyme kinase in CML. He reasoned that precisely inhibiting this kinase with a drug would control the disease and have little effect on normal cells. Druker collaborated with Novartis chemist Nicholas Lydon, who developed several candidate inhibitors. From these, imatinib was found to have the most promise in laboratory experiments. First Druker and then other groups worldwide demonstrated that when this small molecule is used to treat patients with chronic-phase CML, 90% achieve complete haematological remission. It is hoped that molecular targeting of similar defects in other cancers will have the same effect. | 1 | Applied and Interdisciplinary Chemistry |
The absorption of levetiracetam tablets and oral solution is rapid and essentially complete. The bioavailability of levetiracetam is close to 100 percent, and the effect of food on absorption is minor. | 0 | Theoretical and Fundamental Chemistry |
Transition-metal allyl complexes are coordination complexes with allyl and its derivatives as ligands. Allyl is the radical with the connectivity CHCHCH, although as a ligand it is usually viewed as an allyl anion CH=CH−CH, which is usually described as two equivalent resonance structures. | 0 | Theoretical and Fundamental Chemistry |
Casting is a solidification process, which means the solidification phenomenon controls most of the properties of the casting. Moreover, most of the casting defects occur during solidification, such as gas porosity and solidification shrinkage.
Solidification occurs in two steps: nucleation and crystal growth. In the nucleation stage, solid particles form within the liquid. When these particles form, their internal energy is lower than the surrounded liquid, which creates an energy interface between the two. The formation of the surface at this interface requires energy, so as nucleation occurs, the material actually undercools (i.e. cools below its solidification temperature) because of the extra energy required to form the interface surfaces. It then recalescences, or heats back up to its solidification temperature, for the crystal growth stage. Nucleation occurs on a pre-existing solid surface because not as much energy is required for a partial interface surface as for a complete spherical interface surface. This can be advantageous because fine-grained castings possess better properties than coarse-grained castings. A fine grain structure can be induced by grain refinement or inoculation, which is the process of adding impurities to induce nucleation.
All of the nucleations represent a crystal, which grows as the heat of fusion is extracted from the liquid until there is no liquid left. The direction, rate, and type of growth can be controlled to maximize the properties of the casting. Directional solidification is when the material solidifies at one end and proceeds to solidify to the other end; this is the most ideal type of grain growth because it allows liquid material to compensate for shrinkage. | 1 | Applied and Interdisciplinary Chemistry |
Protein names are generally the same as the gene names, but the protein names are not italicized, and the first letter is upper-case. E.g. the name of RNA polymerase is RpoB, and this protein is encoded by rpoB gene. | 1 | Applied and Interdisciplinary Chemistry |
Radioactive sources are used for logging formation parameters. Radioactive tracers, along with the other substances in hydraulic-fracturing fluid, are sometimes used to determine the injection profile and location of fractures created by hydraulic fracturing. | 0 | Theoretical and Fundamental Chemistry |
AFM operation is usually described as one of three modes, according to the nature of the tip motion: contact mode, also called static mode (as opposed to the other two modes, which are called dynamic modes); tapping mode, also called intermittent contact, AC mode, or vibrating mode, or, after the detection mechanism, amplitude modulation AFM; and non-contact mode, or, again after the detection mechanism, frequency modulation AFM.
Despite the nomenclature, repulsive contact can occur or be avoided both in amplitude modulation AFM and frequency modulation AFM, depending on the settings. | 0 | Theoretical and Fundamental Chemistry |
In 1948, Nicolaas Bloembergen, Edward Mills Purcell, and Robert Pound proposed the so-called Bloembergen-Purcell-Pound theory (BPP theory) to explain the relaxation constant of a pure substance in correspondence with its state, taking into account the effect of tumbling motion of molecules on the local magnetic field disturbance. The theory agrees well with experiments on pure substances, but not for complicated environments such as the human body.
This theory makes the assumption that the autocorrelation function of the microscopic fluctuations causing the relaxation is proportional to , where is called the correlation time. From this theory, one can get T > T for magnetic dipolar relaxation:
where is the Larmor frequency in correspondence with the strength of the main magnetic field . is the correlation time of the molecular tumbling motion. is defined for spin-1/2 nuclei and is a constant with being the magnetic permeability of free space of the the reduced Planck constant, γ the gyromagnetic ratio of such species of nuclei, and r the distance between the two nuclei carrying magnetic dipole moment.
Taking for example the HO molecules in liquid phase without the contamination of oxygen-17, the value of K is 1.02×10 s and the correlation time is on the order of picoseconds = s, while hydrogen nuclei H (protons) at 1.5 tesla precess at a Larmor frequency of approximately 64 MHz (Simplified. BPP theory uses angular frequency indeed). We can then estimate using τ = 5×10 s:
:(dimensionless)
:= 3.92 s
:= 3.92 s,
which is close to the experimental value, 3.6 s. Meanwhile, we can see that at this extreme case, T equals T.
As follows from the BPP theory, measuring the T times leads to internuclear distances r. One of the examples is accurate determinations of the metal – hydride (M-H) bond lengths in solutions by measurements of H selective and non-selective T times in variable-temperature relaxation experiments via the equation:
:, with
where r, frequency and T are measured in Å, MHz and s, respectively, and I is the spin of M. | 0 | Theoretical and Fundamental Chemistry |
Cyclic adenosine monophosphate (cAMP, cyclic AMP, or 3,5-cyclic adenosine monophosphate) is a second messenger, or cellular signal occurring within cells, that is important in many biological processes. cAMP is a derivative of adenosine triphosphate (ATP) and used for intracellular signal transduction in many different organisms, conveying the cAMP-dependent pathway. | 1 | Applied and Interdisciplinary Chemistry |
Validation of analytical procedures is imperative in demonstrating that a drug substance is suitable for a particular purpose. Common validation characteristics include: accuracy, precision (repeatability and intermediate precision), specificity, detection limit, quantitation limit, linearity, range, and robustness. In cases such as changes in synthesis of the drug substance, changes in composition of the finished product, and changes in the analytical procedure, revalidation is necessary to ensure quality control.
All analytical procedures should be validated. Identification tests are conducted to ensure the identity of an analyte in a sample through comparison of the sample to a reference standard through methods such as spectrum, chromatographic behavior, and chemical reactivity. Impurity testing can either be a quantitative test or a limit test. Both tests should accurately measure the purity of the sample. Quantitative tests of either the active moiety or other components of a sample can be conducted through assay procedures. Other analytical procedures such as dissolution testing or particle size determination may also need to be validated and are equally important. | 1 | Applied and Interdisciplinary Chemistry |
Minerals produced through hydrothermal alteration and weathering of primary basaltic minerals are also present on Mars. Secondary minerals include hematite, phyllosilicates (clay minerals), goethite, jarosite, iron sulfate minerals, opaline silica, and gypsum. Many of these secondary minerals require liquid water to form (aqueous minerals).
Opaline silica and iron sulphate minerals form in acidic (low pH) solutions. Sulphates have been found in a variety of locations, including near Juventae Chasma, Ius Chasma, Melas Chasma, Candor Chasma, and Ganges Chasma. These sites all contain fluvial landforms indicating that abundant water was once present. Spirit rover discovered sulfates and goethite in the Columbia Hills.
Some of the mineral classes detected may have formed in environments suitable (i.e., enough water and the proper pH) for life. The mineral smectite (a phyllosilicate) forms in near-neutral waters. Phyllosilicates and carbonates are good for preserving organic matter, so they may contain evidence of past life. Sulfate deposits preserve chemical and morphological fossils, and fossils of microorganisms form in iron oxides like hematite. The presence of opaline silica points toward a hydrothermal environment that could support life. Silica is also excellent for preserving evidence of microbes. | 0 | Theoretical and Fundamental Chemistry |
Historically this equation arose as a variant on the Prony equation; this variant was developed by Henry Darcy of France, and further refined into the form used today by Julius Weisbach of Saxony in 1845. Initially, data on the variation of with velocity was lacking, so the Darcy–Weisbach equation was outperformed at first by the empirical Prony equation in many cases. In later years it was eschewed in many special-case situations in favor of a variety of empirical equations valid only for certain flow regimes, notably the Hazen–Williams equation or the Manning equation, most of which were significantly easier to use in calculations. However, since the advent of the calculator, ease of calculation is no longer a major issue, and so the Darcy–Weisbach equation's generality has made it the preferred one. | 1 | Applied and Interdisciplinary Chemistry |
In a photobiological process, the hydrogen is produced using photosynthetic microorganisms (green microalgae and cyanobacteria) in photobioreactors. Some of these organisms produce hydrogen upon switching culture conditions; for example, Chlamydomonas reinhardtii produces hydrogen anaerobically under sulfur deprivation, that is, when cells are moved from one growth medium to another that does not contain sulfur, and are grown without access to atmospheric oxygen. Another approach was to abolish activity of the hydrogen-oxidizing (uptake) hydrogenase enzyme in the diazotrophic cyanobacterium Nostoc punctiforme, so that it would not consume hydrogen that is naturally produced by the nitrogenase enzyme in nitrogen-fixing conditions. This N. punctiforme mutant could then produce hydrogen when illuminated with visible light.
Another mutant Cyanobacteria, Synechocystis, is using genes of the bacteria Rubrivivax gelatinosus CBS to produce hydrogen. The CBS bacteria produce hydrogen through the oxidation of carbon monoxide. Researchers are working to implement these genes into the Synechocystis. If these genes can be applied, it will take some effort to overcome the problems of oxygen inhibition in the production of hydrogen, but it is estimated that this process can potentially yield as much as 10% solar energy capture. This makes photobiological research a very exciting and promising branch of the hydrogen production explorations. Still the problems of overcoming the short-term nature of algal hydrogen production are many and research is in the early stages. However, this research provides a viable way to industrialize these renewable and environmental friendly processes. | 0 | Theoretical and Fundamental Chemistry |
Cyanobacteria are variable in morphology, ranging from unicellular and filamentous to colonial forms. Filamentous forms exhibit functional cell differentiation such as heterocysts (for nitrogen fixation), akinetes (resting stage cells), and hormogonia (reproductive, motile filaments). These, together with the intercellular connections they possess, are considered the first signs of multicellularity.
Many cyanobacteria form motile filaments of cells, called hormogonia, that travel away from the main biomass to bud and form new colonies elsewhere. The cells in a hormogonium are often thinner than in the vegetative state, and the cells on either end of the motile chain may be tapered. To break away from the parent colony, a hormogonium often must tear apart a weaker cell in a filament, called a necridium.
Some filamentous species can differentiate into several different cell types:
* Vegetative cells – the normal, photosynthetic cells that are formed under favorable growing conditions
* Akinetes – climate-resistant spores that may form when environmental conditions become harsh
* Thick-walled heterocysts – which contain the enzyme nitrogenase vital for nitrogen fixation in an anaerobic environment due to its sensitivity to oxygen.
Each individual cell (each single cyanobacterium) typically has a thick, gelatinous cell wall. They lack flagella, but hormogonia of some species can move about by gliding along surfaces. Many of the multicellular filamentous forms of Oscillatoria are capable of a waving motion; the filament oscillates back and forth. In water columns, some cyanobacteria float by forming gas vesicles, as in archaea. These vesicles are not organelles as such. They are not bounded by lipid membranes, but by a protein sheath. | 0 | Theoretical and Fundamental Chemistry |
In chemistry there is a practice known as synthesis. This process is used to form complex chemical compounds from simpler ones. These complex compounds are desirable for their ranging abilities and properties. In order to produce the complex compounds, the simpler ones must “cooperate” in a specific way. This can be very difficult and requires patience, because of the time required to make the bonds so their uses and properties can be tested. There was a need for optimization of this process in order to speed up the development and testing of new compounds. Catellani and her team in 1997 found such a method to optimize this process. Catellani discovered a chain reaction process that simplified and increased yield for desirable complex compounds. One bond the Catellani Reaction is heavily used to create is Carbon-Carbon bonds. These bonds are desirable for their stability and strength. These qualities make the bonds very useful in the makeup of more complex compounds.
Since its discovery, the Catellani Reaction has opened the door to other discoveries or improvements in chemistry. Specifically in the world of pharmaceuticals, the Catellani Reaction has been a useful tool for synthesizing drugs in a more efficient way to aid in their development. Lenoxipen is an example of one of the complex compounds now much easier to achieve with the discovery of Catellani Reactions. This compound belongs to a group of compounds known as Lignans that are useful for relieving pain and may provide benefits to cancer patients. These examples of the uses for Catellani Reactions show the vast and indirect benefits to its discovery. To chemists, the Catellani Reaction is a tool that acts to optimize the process for making new compounds. These new compounds are pivotal for advancing what is possible through chemistry. As new scientists study and try to build upon the Catellani Reaction, it is important to remember who provided the first understanding as it would open up a new world of opportunity. | 0 | Theoretical and Fundamental Chemistry |
A well-known thioamide is thioacetamide, which is used as a source of the sulfide ion and is a building block in heterocyclic chemistry.
Thioamides or anti-thyroid drugs are also a class of drugs that are used to control thyrotoxicosis. | 0 | Theoretical and Fundamental Chemistry |
The database contains ca 3,500 Raman spectra. The spectra were recorded in the region of 4,000 – 0 cm with an excitation wavelength of 4,800 nm and a slit width of 100 – 200 micrometers. This collection is not being updated. | 0 | Theoretical and Fundamental Chemistry |
Old high-precision frequency standards, i.e. hyperfine structure transition-based atomic clocks, may require periodic fine-tuning due to exposure to magnetic fields. This is carried out by measuring the Zeeman effect on specific hyperfine structure transition levels of the source element (cesium) and applying a uniformly precise, low-strength magnetic field to said source, in a process known as degaussing.
The Zeeman effect may also be utilized to improve accuracy in atomic absorption spectroscopy. | 0 | Theoretical and Fundamental Chemistry |
Ketones are pervasive in nature. The formation of organic compounds in photosynthesis occurs via the ketone ribulose-1,5-bisphosphate. Many sugars are ketones, known collectively as ketoses. The best known ketose is fructose; it mostly exists as a cyclic hemiketal, which masks the ketone functional group. Fatty acid synthesis proceeds via ketones. Acetoacetate is an intermediate in the Krebs cycle which releases energy from sugars and carbohydrates.
In medicine, acetone, acetoacetate, and beta-hydroxybutyrate are collectively called ketone bodies, generated from carbohydrates, fatty acids, and amino acids in most vertebrates, including humans. Ketone bodies are elevated in the blood (ketosis) after fasting, including a night of sleep; in both blood and urine in starvation; in hypoglycemia, due to causes other than hyperinsulinism; in various inborn errors of metabolism, and intentionally induced via a ketogenic diet, and in ketoacidosis (usually due to diabetes mellitus). Although ketoacidosis is characteristic of decompensated or untreated type 1 diabetes, ketosis or even ketoacidosis can occur in type 2 diabetes in some circumstances as well. | 0 | Theoretical and Fundamental Chemistry |
Diebold holds dual citizenship of both Austria and the US. She is married to Gerhard Piringer with whom she has two sons, Thomas (born 1996) and Niklas (born 1999). | 0 | Theoretical and Fundamental Chemistry |
Most of the iron in the body is hoarded and recycled by the reticuloendothelial system, which breaks down aged red blood cells. In contrast to iron uptake and recycling, there is no physiologic regulatory mechanism for excreting iron. People lose a small but steady amount by gastrointestinal blood loss, sweating and by shedding cells of the skin and the mucosal lining of the gastrointestinal tract. The total amount of loss for healthy people in the developed world amounts to an estimated average of a day for men, and 1.5–2 mg a day for women with regular menstrual periods. People with gastrointestinal parasitic infections, more commonly found in developing countries, often lose more. Those who cannot regulate absorption well enough get disorders of iron overload. In these diseases, the toxicity of iron starts overwhelming the body's ability to bind and store it. | 1 | Applied and Interdisciplinary Chemistry |
Since BioCyc Database family comprises a long list of organism specific databases and also data at different systems level in a living system, the usage in research has been in a wide variety of context. Here, two studies are highlighted which show two different varieties of uses, one on a genome scale and other on identifying specific SNPs (Single Nucleotide Polymorphisms) within a genome.
AlgaGEM
AlgaGEM is a genome scale metabolic network model for a compartmentalized algae cell developed by Gomes de Oliveira Dal’Molin et al. based on the Chlamydomonas reinhardtii genome. It has 866 unique ORFs, 1862 metabolites, 2499 gene-enzyme-reaction-association entries, and 1725 unique reactions. One of the Pathway databases used for reconstruction is MetaCyc.
SNPs
The study by Shimul Chowdhury et al. showed association differed between maternal SNPs and metabolites involved in homocysteine, folate, and transsulfuration pathways in cases with Congenital Heart Defects (CHDs) as opposed to controls. The study used HumanCyc to select candidate genes and SNPs. | 1 | Applied and Interdisciplinary Chemistry |
Taxadienone ((+)-taxa-4(5),11(12)-dien-2-one) is an organic compound and a taxane. The compound is of some academic interest as a potential precursor to Taxol, in important anti-cancer drug, in a commercially viable process. A total synthesis of taxadienone was reported in 2012 together with its conversion to the next Taxol precursor taxadiene. A multigram synthetic method was reported in 2015. | 0 | Theoretical and Fundamental Chemistry |
UVGI can be used to disinfect air with prolonged exposure. In the 1930s and 40s, an experiment in public schools in Philadelphia showed that upper-room ultraviolet fixtures could significantly reduce the transmission of measles among students. In 2020, UVGI is again being researched as a possible countermeasure against COVID-19.
UV and violet light are able to neutralize the infectivity of SARS-CoV-2. Viral titers usually found in the sputum of COVID-19 patients are completely inactivated by levels of UV-A and UV-B irradiation that are similar to those levels experienced from natural sun exposure. This finding suggests that the reduced incidence of SARS-COV-2 in the summer may be, in part, due to the neutralizing activity of solar UV irradiation.
Various UV-emitting devices can be used for SARS-CoV-2 disinfection, and these devices may help in reducing the spread of infection. SARS-CoV-2 can be inactivated by a wide range of UVC wavelengths, and the wavelength of 222 nm provides the most effective disinfection performance.
Disinfection is a function of UV intensity and time. For this reason, it is in theory not as effective on moving air, or when the lamp is perpendicular to the flow, as exposure times are dramatically reduced. However, numerous professional and scientific publications have indicated that the overall effectiveness of UVGI actually increases when used in conjunction with fans and HVAC ventilation, which facilitate whole-room circulation that exposes more air to the UV source. Air purification UVGI systems can be free-standing units with shielded UV lamps that use a fan to force air past the UV light. Other systems are installed in forced air systems so that the circulation for the premises moves microorganisms past the lamps. Key to this form of sterilization is placement of the UV lamps and a good filtration system to remove the dead microorganisms. For example, forced air systems by design impede line-of-sight, thus creating areas of the environment that will be shaded from the UV light. However, a UV lamp placed at the coils and drain pans of cooling systems will keep microorganisms from forming in these naturally damp places. | 0 | Theoretical and Fundamental Chemistry |
The roast gas is conveyed through the system by means of an exhaust gas fan (VI). Fans in plants provide pressure increases of approx. 200 mbar and are feedback-controlled to maintain a relative pressure of -3 mbar between reactor and atmosphere to avoid any overpressure-related leakage of acid gas.
To rinse the impeller and cool the gas as well as to remove remaining traces of HCl from the roast gas, the exhaust gas fan is commonly supplied with quenching water, which is separated from the exhaust gas stream by means of a mist eliminator (VII) at the pressure side of the fan.
In a final scrubber, commonly consisting of a combination of wet scrubbers such as venturi scrubbers (IX) and scrubber columns (X), remaining traces of HCl and dust are removed.
In some plant, absorption chemicals such as NaOH and NaSO are used to bind HCl and Cl (which is created under certain circumstances in several, but not all spray roasting reactors). | 0 | Theoretical and Fundamental Chemistry |
In organic synthesis, compounds containing the carbodiimide functionality are used as dehydration agents. Specifically they are often used to convert carboxylic acids to amides or esters. Additives, such as N-hydroxybenzotriazole or N-hydroxysuccinimide, are often added to increase yields and decrease side reactions.
Polycarbodiimides can also be used as crosslinkers for aqueous resins, such as polyurethane dispersions or acrylic dispersion. Here the polycarbodiimide reacts with carboxylic acids, whose functional groups are often present in such aqueous resins, to form N-acyl urea. The result is the formation of covalent bonds between the polymer chains, making them crosslinked. | 0 | Theoretical and Fundamental Chemistry |
Airborne Real-time Cueing Hyperspectral Enhanced Reconnaissance, also known by the acronym ARCHER, is an aerial imaging system that produces ground images far more detailed than plain sight or ordinary aerial photography can.
It is the most sophisticated unclassified hyperspectral imaging system available, according to U.S. Government officials.
ARCHER can automatically scan detailed imaging for a given signature of the object being sought (such as a missing aircraft), for abnormalities in the surrounding area, or for changes from previous recorded spectral signatures.
It has direct applications for search and rescue, counterdrug, disaster relief and impact assessment, and homeland security, and has been deployed by the Civil Air Patrol (CAP) in the US on the Australian-built Gippsland GA8 Airvan fixed-wing aircraft. CAP, the civilian auxiliary of the United States Air Force, is a volunteer education and public-service non-profit organization that conducts aircraft search and rescue in the US. | 0 | Theoretical and Fundamental Chemistry |
Evaporative cooling is an atomic physics technique to achieve high phase space densities which optical cooling techniques alone typically can not reach.
Atoms trapped in optical or magnetic traps can be evaporatively cooled via two primary mechanisms, usually specific to the type of trap in question: in magnetic traps, radiofrequency (RF) fields are used to selectively drive warm atoms from the trap by inducing transitions between trapping and non-trapping spin states; or, in optical traps, the depth of the trap itself is gradually decreased, allowing the most energetic atoms in the trap to escape over the edges of the optical barrier. In the case of a Maxwell-Boltzmann distribution for the velocities of the atoms in the trap, these atoms which escape/are driven out of the trap lie in the highest velocity tail of the distribution, meaning that their kinetic energy (and therefore temperature) is much higher than the average for the trap. The net result is that while the total trap population decreases, so does the mean energy of the remaining population. This decrease in the mean kinetic energy of the atom cloud translates into a progressive decrease in the trap temperature, cooling the trap.
The process is analogous to blowing on a cup of coffee to cool it: those molecules at the highest end of the energy distribution for the coffee form a vapor above the surface and are then removed from the system by blowing them away, decreasing the average energy, and therefore temperature, of the remaining coffee molecules. | 0 | Theoretical and Fundamental Chemistry |
Realtime spectrum analyzers are able to see signals hidden behind other signals. This is possible because no information is missed and the display to the user is the output of FFT calculations. An example of this can be seen on the right. | 0 | Theoretical and Fundamental Chemistry |
Hydrant flushing is the scheduled release of water from fire hydrants or special flushing hydrants to purge iron and other mineral deposits from a water main. Another benefit of using fire hydrants for water main flushing is to test whether water is supplied to fire hydrants at adequate pressure for fire fighting. During hydrant flushing, consumers may notice rust color in their water as iron and mineral deposits are stirred up in the process. | 1 | Applied and Interdisciplinary Chemistry |
Tablet formulations are designed and tested using a laboratory machine called a Tablet Compaction Simulator or Powder Compaction Simulator. This is a computer controlled device that can measure the punch positions, punch pressures, friction forces, die wall pressures, and sometimes the tablet internal temperature during the compaction event. Numerous experiments with small quantities of different mixtures can be performed to optimise a formulation.
Mathematically corrected punch motions can be programmed to simulate any type and model of production tablet press. Initial quantities of active pharmaceutical ingredients are very expensive to produce, and using a Compaction Simulator reduces the amount of powder required for product development. | 1 | Applied and Interdisciplinary Chemistry |
The formyl group can be readily reduced to a primary alcohol (). Typically this conversion is accomplished by catalytic hydrogenation either directly or by transfer hydrogenation. Stoichiometric reductions are also popular, as can be effected with sodium borohydride. | 0 | Theoretical and Fundamental Chemistry |
She finished her Abitur in 1999. She then studied chemistry at the Humboldt University of Berlin from 1999 to 2004. From 2004 to 2009 she worked on her doctorate in the group of Christian Limberg at the Humboldt University of Berlin. The topic of her dissertation was "Activation of dioxygen at novel first row transition metal complexes for biomimetic oxidation reactions". From 2009 to 2010, she was a postdoctoral research fellow at the University of Oxford in the group of Simon Aldridge. From 2011 to 2013, she was a research fellow at the University of Göttingen in the group of Franc Meyer. From 2013 to 2016, she was an Emmy Noether group leader at the same university. Since 2017, she is a professor in Inorganic Chemistry at the University of Göttingen. | 0 | Theoretical and Fundamental Chemistry |
The laws of gravity seem to be time reversal invariant in classical mechanics; however, specific solutions need not be.
An object can cross through the event horizon of a black hole from the outside, and then fall rapidly to the central region where our understanding of physics breaks down. Since within a black hole the forward light-cone is directed towards the center and the backward light-cone is directed outward, it is not even possible to define time-reversal in the usual manner. The only way anything can escape from a black hole is as Hawking radiation.
The time reversal of a black hole would be a hypothetical object known as a white hole. From the outside they appear similar. While a black hole has a beginning and is inescapable, a white hole has an ending and cannot be entered. The forward light-cones of a white hole are directed outward; and its backward light-cones are directed towards the center.
The event horizon of a black hole may be thought of as a surface moving outward at the local speed of light and is just on the edge between escaping and falling back. The event horizon of a white hole is a surface moving inward at the local speed of light and is just on the edge between being swept outward and succeeding in reaching the center. They are two different kinds of horizons—the horizon of a white hole is like the horizon of a black hole turned inside-out.
The modern view of black hole irreversibility is to relate it to the second law of thermodynamics, since black holes are viewed as thermodynamic objects. For example, according to the gauge–gravity duality conjecture, all microscopic processes in a black hole are reversible, and only the collective behavior is irreversible, as in any other macroscopic, thermal system. | 0 | Theoretical and Fundamental Chemistry |
Electron microscopy: The sample is not exposed to a beam of electrons but detectors picks up the expelled electrons from the radionuclei.
Micro-autoradiography: A tissue section, typically cryosectioned, is placed against a phosphor screen as above.
Quantitative Whole Body Autoradiography (QWBA): Larger than micro-autoradiography, whole animals, typically rodents, can be analyzed for biodistribution studies. | 0 | Theoretical and Fundamental Chemistry |
The mass average molar mass (often loosely termed weight average molar mass) is another way of describing the molar mass of a polymer. Some properties are dependent on molecular size, so a larger molecule will have a larger contribution than a smaller molecule. The mass average molar mass is calculated by
where is the number of molecules of molecular mass .
The mass average molecular mass can be determined by static light scattering, small angle neutron scattering, X-ray scattering, and sedimentation velocity.
The ratio of the mass average to the number average is called the dispersity or the polydispersity index.
The mass-average molecular mass, , is also related to the fractional monomer conversion, , in step-growth polymerization (for the simplest case of linear polymers formed from two monomers in equimolar quantities) as per Carothers' equation:
where is the molecular mass of the repeating unit. | 0 | Theoretical and Fundamental Chemistry |
Immunoturbidimetry is an important tool in the broad diagnostic field of clinical chemistry. It is used to determine serum proteins not detectable with classical clinical chemistry methods. Immunoturbidimetry uses the classical antigen-antibody reaction. The antigen-antibody complexes aggregate to form particles that can be optically detected by a photometer. | 0 | Theoretical and Fundamental Chemistry |
Diborane can be produced in situ by reduction BF with NaBH (see for Flavopiridol). Usually however, borane dimethylsulfide complex BHS(CH) (BMS) is used as a source of BH. It can be obtained in highly concentrated forms.
The adduct BH(THF) is also commercially available as THF solutions wherein it exists as the 1:1 adduct. It degrades with time.
Borane adducts with phosphines and amines are also available, but are not widely used. Borane makes a strong adduct with triethylamine; using this adduct requires harsher conditions in hydroboration. This can be advantageous for cases such as hydroborating trienes to avoid polymerization. More sterically hindered tertiary and silyl amines can deliver borane to alkenes at room temperature. | 0 | Theoretical and Fundamental Chemistry |
After 1.5 years in space, samples were retrieved, rehydrated and spread on different culture media. The only two organisms able to grow were isolated from a sample exposed to simulated Mars conditions beneath a 0.1% T Suprasil neutral density filter and from a sample exposed to space vacuum without solar radiation exposure, respectively. The two surviving organisms were identified as Stichococcus sp. (green algae) and Acarospora sp. (lichenized fungal genus). Among other fungal spores tested were Cryomyces antarcticus and Cryomyces minteri, and although 60% of the cells' DNA studied remained intact after the Mars-like conditions, less than 10% of the fungi were able to proliferate and form colonies after their return to Earth. According to the researchers, the studies provide experimental information on the possibility of eukaryotic life transfer from one planet to another by means of rocks and of survival in Mars environment.
Cryptoendolithic microbial communities and epilithic lichens have been considered as appropriate candidates for the scenario of lithopanspermia, which proposes a natural interplanetary exchange of organisms by means of rocks that have been impact ejected from their planet of origin. A 1.5 years exposure experiment in space was performed with a variety of rock-colonizing eukaryotic organisms. Selected organisms are known to cope with the environmental extremes of their natural habitats. It was found that some — but not all — of those most robust microbial communities from extremely hostile regions on Earth are also partially resistant to the even more hostile environment of outer space, including high vacuum, temperature fluctuation, the full spectrum of extraterrestrial solar electromagnetic radiation, and cosmic ionizing radiation. Although the reported experimental period of 1.5 years in space is not comparable with the time spans of thousands or millions of years believed to be required for lithopanspermia, the data provide first evidence of the differential hardiness of cryptoendolithic communities in space. | 1 | Applied and Interdisciplinary Chemistry |
Pertactin adheres to only ciliated epithelial cells of B. bronchiseptica in vivo. However, in vitro, PRN does not adhere to either. PRN does however help provide resistance towards a hyperinflammatory response of innate immunity for B. bronchiseptica. With respect to the adaptive immunity, studies show that PRN plays a role in combating neutrophil-mediated clearance of B. bronchiseptica. | 1 | Applied and Interdisciplinary Chemistry |
Most of the solvents employed vaporize quickly and are flammable, making the extraction process dangerous. Several explosion and fire incidents related to hash oil manufacturing attempts in homes have been reported.
Solvents used to extract THC are flammable or combustible and have resulted in explosions, fires, severe injuries, and deaths. | 0 | Theoretical and Fundamental Chemistry |
In creating the Flory–Stockmayer Theory, Flory made three assumptions that affect the accuracy of this model. These assumptions were:
# All functional groups on a branch unit are equally reactive
# All reactions occur between A and B
# There are no intramolecular reactions
As a result of these assumptions, a conversion slightly higher than that predicted by the Flory–Stockmayer Theory is commonly needed to actually create a polymer gel. Since steric hindrance effects prevent each functional group from being equally reactive and intramolecular reactions do occur, the gel forms at slightly higher conversion.
Flory postulated that his treatment can also be applied to chain-growth polymerization mechanisms, as the three criteria stated above are satisfied under the assumptions that (1) the probability of chain termination is independent of chain length, and (2) multifunctional co-monomers react randomly with growing polymer chains. | 0 | Theoretical and Fundamental Chemistry |
*1997 – Faculty Career Award, National Science Foundation
*2002 – Fulbright Senior Scholar
*2022 – Fellow of the American Institute of Chemical Engineers | 1 | Applied and Interdisciplinary Chemistry |
The state postulate is a term used in thermodynamics that defines the given number of properties to a thermodynamic system in a state of equilibrium. It is also sometimes referred to as the state principle. The state postulate allows a finite number of properties to be specified in order to fully describe a state of thermodynamic equilibrium. Once the state postulate is given the other unspecified properties must assume certain values.
The state postulate says:
A more general statement of the state postulate says:
the state of a simple system is completely specified by r+1 independent, intensive properties where r is the number of significant work interactions.
A system is considered to be a simple compressible one in the absence of certain effects which are uncommon in many engineering applications. These are electromagnetic and gravitational fields, surface tension, and motion. For such a system, only two independent intensive variables are sufficient to derive all the others by use of an equation of state. In the case of a more complex system, additional variables must be measured in order to solve for the complete state. For example, if gravitation is significant then an elevation may be required.
Two properties are considered independent if one can be varied while the other is held constant. For example, temperature and specific volume are always independent. However, temperature and pressure are independent only for a single-phase system; for a multiphase system (such as a mixture of gas and liquid) this is not the case. (e.g., boiling point (temperature) depends on elevation (ambient pressure)). | 0 | Theoretical and Fundamental Chemistry |
An interesting alternative synthesis of azlocillin involves activation of the substituted phenylglycine analogue 1 with 1,3-dimethyl-2-chloro-1-imidazolinium chloride (2) and then condensation with 6-APA. | 0 | Theoretical and Fundamental Chemistry |
To determine the optimal length of the stem, researchers modified its length and observed how quickly termination occurred. When the length of the stem was lengthened or shortened from the standard 8-9 base pair length, termination was less efficient, and if the changes were great enough, termination ceased completely.
Experiments determined that if an oligonucleotide sequence that is identical to the downstream portion of the stem is present, it will base pair with the upstream portion. This creates a structure that is analogous to the native stem-loop structure but is missing the loop at the end. Without the presence of the loop, intrinsic termination is still able to occur. This indicates that the loop is not inherently necessary for intrinsic termination.
Generally, the absence of the uracil-rich sequence following the stem-loop will result in a delay or pause in transcription, but termination will not cease completely. | 1 | Applied and Interdisciplinary Chemistry |
The field of radioanalytical chemistry was originally developed by Marie Curie with contributions by Ernest Rutherford and Frederick Soddy. They developed chemical separation and radiation measurement techniques on terrestrial radioactive substances. During the twenty years that followed 1897 the concepts of radionuclides was born. Since Curie's time, applications of radioanalytical chemistry have proliferated. Modern advances in nuclear and radiochemistry research have allowed practitioners to apply chemistry and nuclear procedures to elucidate nuclear properties and reactions, used radioactive substances as tracers, and measure radionuclides in many different types of samples.
The importance of radioanalytical chemistry spans many fields including chemistry, physics, medicine, pharmacology, biology, ecology, hydrology, geology, forensics, atmospheric sciences, health protection, archeology, and engineering. Applications include: forming and characterizing new elements, determining the age of materials, and creating radioactive reagents for specific tracer use in tissues and organs. The ongoing goal of radioanalytical researchers is to develop more radionuclides and lower concentrations in people and the environment. | 0 | Theoretical and Fundamental Chemistry |
In the domain , the solution is given by
where , being the kinematic viscosity of the fluid. Following the analysis of Taylor and Green for the two-dimensional situation, and for , gives agreement with this exact solution, if the exponential is expanded as a Taylor series, i.e. .
The pressure field can be obtained by substituting the velocity solution in the momentum equations and is given by
The stream function of the Taylor–Green vortex solution, i.e. which satisfies for flow velocity , is
Similarly, the vorticity, which satisfies , is given by
The Taylor–Green vortex solution may be used for testing and validation of temporal accuracy of Navier–Stokes algorithms.
A generalization of the Taylor–Green vortex solution in three dimensions in described in. | 1 | Applied and Interdisciplinary Chemistry |
Many ordinary liquids, like alcohol or petroleum, creep up solid walls, driven by their surface tension. Liquid helium also has this property, but, in the case of He-IV, the flow of the liquid in the layer is not restricted by its viscosity but by a critical velocity which is about 20 cm/s. This is a fairly high velocity so superfluid helium can flow relatively easily up the wall of containers, over the top, and down to the same level as the surface of the liquid inside the container, in a siphon effect. It was, however, observed, that the flow through nanoporous membrane becomes restricted if the pore diameter is less than 0.7 nm (i.e. roughly three times the classical diameter of helium atom), suggesting the unusual hydrodynamic properties of He arise at larger scale than in the classical liquid helium. | 1 | Applied and Interdisciplinary Chemistry |
In June 2015, the Post-Event Environmental Impact Assessments Report was published as part of the second phase of the strategy. The report was submitted by Golder Associates to the Mount Polley Mining Corporation to determine the physical, biological, and chemical implications 6–8 months after the dam breach. The report detailed steps taken by the MPMC to stabilize the tailings storage facility by creating two rock berms inside the facility, to provide safe access to Hazeltine creek by reducing the elevation of Polley Lake behind the point of the blockage caused by the discharge of tailings effluent, and to stop inputs from the tailings storage facility. Specialists and environmental scientists and engineers were hired to study the impact of the spill from the tailings dam. This team studied where tailings effluent was deposited on land and in surrounding water environments, in particular how the bottom of Quesnel Lake was affected and how the structures of Hazeltine and Edney creeks had changed. Chemical studies studied soil, water and sediment changes, while biological studies were focused on the effect of aquatic plant and animal life, in particular those at the sediment layer. Biological assessment also studied soil-dependent biota in the areas surrounding Quesnel Lake and Polley Lake.
The Assessments Report determined nine areas requiring ongoing monitoring to determine localized strategies for remediation efforts in each location. These areas included the tailings storage facility, the Polley plug (a blockage area between the tailings effluent and Polley Lake), Polley Lake, upper Hazeltine creek, Hazeltine Canyon, lower Hazeltine creek, the mouth of Edney creek, Quesnel Lake, and Quesnel River.
The report concluded that Polley Lake, Hazeltine Creek and a small portion of Quesnel Lake were physically affected by the tailings dam breach. The chemical testing on the tailings mixture was determined to be relatively inert though it was found that a higher concentration of copper was contained in the effluent compared to before the breach. Biological testing found copper contained within lake sediment and within the water was not toxic to aquatic life. Soil testing of copper levels determined a level higher than provincial standards for the protection of invertebrates and plants but at far lower levels than the provincial standards for the protection of human health. Deep water analysis found copper to be at levels below the Provincial Water Quality Guideline. Despite the levels of copper present due to presence in the tailings, the report determined it was unlikely to be released from the tailings and therefore adverse effects were deemed unlikely.
The restoration of the shoreline of Hazeltine creek began to create a stable water flow and to begin the restoration of fish and associated wildlife habitats. This was preceded by floodplain grading and the determination of the physical land characteristics of the areas surrounding the shoreline. A flow study to determine an ideal range and the annual mean for natural habitats was completed before construction of rock weirs and habitat features. Planting on the floodplain, to continue over subsequent years had also begun. Repairs to the mouth of lower Edney Creek was completed connecting the waterway to Quesnel Lake. By the spring of 2015, remediation work had installed a new fish habitat at lower Edney Creek. Successful spawning of interior Coho, Kokanee and Sockeye Salmon was accomplished. By May, a new channel for Hazeltine Creek was completed.
On 13 July 2015, Interior Health, the regional public health authority, declared all water restrictions lifted and determined water sourced from Polley Lake and Hazeltine Creek safe for consumption and recreation from a health perspective. A review of the water, sediment and fish toxicology samples from the Ministry of the Environment determined no known risks to human health. | 1 | Applied and Interdisciplinary Chemistry |
The phenolic biosynthetic and metabolic pathways and enzymes can be studied by means of transgenesis of genes. The Arabidopsis regulatory gene for production of Anthocyanin Pigment 1 (AtPAP1) can be expressed in other plant species. | 0 | Theoretical and Fundamental Chemistry |
A matrix metalloproteinase inhibitor (MMPI, INN stem ) inhibits matrix metalloproteinases. Because they inhibit cell migration, they have antiangiogenic effects. They may be both endogenous and exogenous.
The most notorious endogenous metalloproteinases are tissue inhibitors of metalloproteinases (TIMPs). There are also cartilage-derived angiogenesis inhibitors.
Exogenous matrix metalloproteinase inhibitors were developed as anticancer drugs. Examples include:
* Batimastat
* Cipemastat
* Ilomastat
* Marimastat
* MMI270
* Prinomastat
* Rebimastat
* Ro 28-2653
* Tanomastat
Metalloproteinase inhibitors are found in numerous marine organisms, including fish, cephalopods, mollusks, algae, and bacteria. | 1 | Applied and Interdisciplinary Chemistry |
Bicycle Day is an informal celebration on April 19th of the anniversary of the first LSD trip, and the psychedelic revolution in general. It is sometimes celebrated by riding a bike on psychedelics and/or in a parade, and often with psychedelic-themed festivities.
On April 19, 1943, Hofmann ingested 0.25 milligrams (250 micrograms) of the substance. Between one and two hours later, Hofmann experienced slow and gradual changes in his perception. He asked his laboratory assistant to escort him home. As was customary in Basel, they made the journey by bicycle. On the way, Hofmann's condition rapidly deteriorated as he struggled with feelings of anxiety, alternating in his beliefs that the next-door neighbor was a malevolent witch, that he was going insane, and that the LSD had poisoned him. When the house doctor arrived, however, he could detect no physical abnormalities, save for a pair of widely dilated pupils. Hofmann was reassured, and soon his terror began to give way to a sense of good fortune and enjoyment, as he later wrote:
The events of this first LSD trip, now known as "Bicycle Day", after the bicycle ride home, proved to Hofmann that he had indeed made a significant discovery: a psychoactive substance with extraordinary potency, capable of causing significant shifts of consciousness in incredibly low doses. (The term trip was first coined by US Army scientists during the 1950s when they were experimenting with LSD.) Hofmann foresaw the drug as a powerful psychiatric tool; because of its intense and introspective nature, he could not imagine anyone using it recreationally. Bicycle Day is increasingly observed in psychedelic communities as a day to celebrate the discovery of LSD.
The celebration of Bicycle Day originated in DeKalb, Illinois, in 1985, when Thomas B. Roberts, then a professor at Northern Illinois University, invented the name "Bicycle Day" when he founded the first celebration at his home. Several years later, he sent an announcement made by one of his students to friends and Internet lists, thus propagating the idea and the celebration. His original intent was to commemorate Hofmanns original, accidental exposure on April 16, but that date fell midweek and was not a good time for the party, so he chose the 19th to honor Hofmanns first intentional exposure. | 1 | Applied and Interdisciplinary Chemistry |
All chemical elements except for hydrogen and helium derive from stellar nucleosynthesis. The basic chemical ingredients of life – the carbon-hydrogen molecule (CH), the carbon-hydrogen positive ion (CH+) and the carbon ion (C+) – were produced by ultraviolet light from stars. Complex molecules, including organic molecules, form naturally both in space and on planets. Organic molecules on the early Earth could have had either terrestrial origins, with organic molecule synthesis driven by impact shocks or by other energy sources, such as ultraviolet light, redox coupling, or electrical discharges; or extraterrestrial origins (pseudo-panspermia), with organic molecules formed in interstellar dust clouds raining down on to the planet. | 0 | Theoretical and Fundamental Chemistry |
The Dittus–Boelter equation (for turbulent flow) as introduced by W.H. McAdams is an explicit function for calculating the Nusselt number. It is easy to solve but is less accurate when there is a large temperature difference across the fluid. It is tailored to smooth tubes, so use for rough tubes (most commercial applications) is cautioned. The Dittus–Boelter equation is:
where:
: is the inside diameter of the circular duct
: is the Prandtl number
: for the fluid being heated, and for the fluid being cooled.
The Dittus–Boelter equation is valid for
The Dittus–Boelter equation is a good approximation where temperature differences between bulk fluid and heat transfer surface are minimal, avoiding equation complexity and iterative solving. Taking water with a bulk fluid average temperature of , viscosity and a heat transfer surface temperature of (viscosity , a viscosity correction factor for can be obtained as 1.45. This increases to 3.57 with a heat transfer surface temperature of (viscosity ), making a significant difference to the Nusselt number and the heat transfer coefficient. | 1 | Applied and Interdisciplinary Chemistry |
In a crossed molecular beam apparatus, two collimated beams of gas-phase atoms or molecules, each dilute enough to ignore collisions within each beam, intersect in a vacuum chamber. The direction and velocity of the resulting product molecules are then measured, and are frequently coupled with mass spectrometric data. These data yield information about the partitioning of energy among translational, rotational, and vibrational modes of the product molecules. | 0 | Theoretical and Fundamental Chemistry |
With a degree in natural resources engineering, there are various different industries that one could pursue a career in. Some of these industries include federal, state, and local government agencies(such as the Natural Resource Conservation Service), environmental consulting firms, agricultural and food processing industries, and various other industries and companies that focus on solving environmental issues. In the government sector, natural resource engineers usually find themselves working on projects that work to manage government owned and operated natural resources and help solve environmental issues that impact these resources. Within an environmental consulting firm, a natural resource engineer may find themselves running calculations and making predictions about different ways to utilize natural resources to maximize their efficiency. Within different processing industries, natural resource engineers may find themselves working on waste management efficiency and natural resource processing design.
Currently, the demand for natural resources engineers is greater than the supply of graduates and ranges locally to globally. | 1 | Applied and Interdisciplinary Chemistry |
Formate dehydrogenase consists of two transmembrane domains; three α-helices of the β-subunit and four transmembrane helices from the gamma-subunit.
The β-subunit of formate dehydrogenase is present in the periplasm with a single transmembrane α-helix spanning the membrane by anchoring the β-subunit to the inner-membrane surface. The β-subunit has two subdomains, where each subdomain has two [[Ferredoxin|[4Fe-4S] ferredoxin clusters]]. The judicious alignment of the [4Fe-4S] clusters in a chain through the subunit have low separation distances, which allow rapid electron flow through [4Fe-4S]-1, [4Fe-4S]-4, [4Fe-4S]-2, and [4Fe-4S]-3 to the periplasmic heme b in the γ-subunit. The electron flow is then directed across the membrane to a cytoplasmic heme b in the γ-subunit .
The γ-subunit of formate dehydrogenase is a membrane-bound cytochrome b consisting of four transmembrane helices and two heme b groups which produce a four-helix bundle which aids in heme binding. The heme b cofactors bound to the gamma subunit allow for the hopping of electrons through the subunit. The transmembrane helices maintain both heme b groups, while only three provide the heme ligands thereby anchoring Fe-heme. The periplasmic heme b group accepts electrons from [4Fe-4S]-3 clusters of the β-subunit’s periplasmic domain. The cytoplasmic heme b group accepts electrons from the periplasmic heme b group, where electron flow is then directed towards the menaquinone (vitamin K) reduction site, present in the transmembrane domain of the gamma subunit. The menaquinone reduction site in the γ-subunit, accepts electrons through the binding of a histidine ligand of the cytoplasmic heme b. | 1 | Applied and Interdisciplinary Chemistry |
Though retaining the interpretation of the phrase in terms of Swedenborgs doctrine of correspondence, it was somewhat more closely associated with the philosophical mentalism (the primacy of mind as the active cause of things) of the ancient Greek Hermetica by the anonymous author of the Kybalion (1908, Three Initiates', perhaps William W. Atkinson, 1862–1932). What follows are some literal quotes from the book: | 1 | Applied and Interdisciplinary Chemistry |
The term "first flush effect" refers to rapid changes in water quality (pollutant concentration or load) that occur after early season rains. Soil and vegetation particles wash into streams; sediments and other accumulated organic particles on the river bed are re-suspended, and dissolved substances from soil and shallow groundwater can be flushed into streams. Recent research has shown that this effect has not been observed in relatively pervious areas.
The term is often also used to address the first flood after a dry period, which is supposed to contain higher concentrations than a subsequent one. This is referred to as "first flush flood." There are various definitions of the first flush phenomenon. | 1 | Applied and Interdisciplinary Chemistry |
Back-of-house testing is more restrictive. The substances tested do not come directly from event participants. Instead, they may come from samples confiscated by police or event security or samples that are disposed of via drug amnesty bins. The results may not be available to event attendees. | 0 | Theoretical and Fundamental Chemistry |
The names for the chemical elements 104 to 106 were the subject of a major controversy starting in the 1960s, described by some nuclear chemists as the Transfermium Wars because it concerned the elements following fermium (element 100) on the periodic table.
This controversy arose from disputes between American scientists and Soviet scientists as to which had first isolated these elements. The final resolution of this controversy in 1997 also decided the names of elements 107 to 109. | 1 | Applied and Interdisciplinary Chemistry |
Smelting or the reduction of an ore to its metallic state is the primary source of experimentation in archaeometallurgy. In its simplest form smelting can be accomplished by placing an ore sample between two pieces of combusting charcoal in an oxygen reducing atmosphere with a compressed air source to feed the combustion and result in temperatures high enough to smelt metal. But to reach this final metallic state several things need to be done first including the processing of the ore to remove waste or gangue material, the possible roasting of the ore, the smelting of the ore, and then there is the possibility of refining the metal through a series of remelts. Then, through chemical or microscopic analysis, the products of the smelt are analyzed and compared with the findings of archaeological excavation in order to examine the likelihood of various manufacturing processes. | 1 | Applied and Interdisciplinary Chemistry |
The Division of Reproductive Biology was established in the School of Public Health in 1972. With its emphasis on biochemistry, molecular biology, cell biology, physiology and genetics of reproductive processes. Prior to the Division becoming part of BMB in 1998, it was part of the Department of Population Dynamics, also at the School of Public Health. The research of the Division's faculty is both basic and applied, often extending from the molecule to the individual patient to the population. The current head of the Division is William W. Wright. | 1 | Applied and Interdisciplinary Chemistry |
Members of the chemokine family are divided into four groups depending on the spacing of their first two cysteine residues. Thus the nomenclature for chemokines is, e.g.: CCL1 for the ligand 1 of the CC-family of chemokines, and CCR1 for its respective receptor. | 1 | Applied and Interdisciplinary Chemistry |
The snRNPs are very long-lived, but are assumed to be eventually disassembled and degraded. Little is known about the degradation process. | 1 | Applied and Interdisciplinary Chemistry |
Steady-states can be stable or unstable. A steady-state is unstable if a small perturbation in one or more of the concentrations results in the system diverging from its state. In contrast, if a steady-state is stable, any perturbation will relax back to the original steady state. Further details can be found on the page Stability theory. | 0 | Theoretical and Fundamental Chemistry |
Since the 1920s, beryllium has been used in electronics, ceramics, research and development labs, aircraft, and the atomic energy and defense industry. Cases of bronchitis and pneumonia-like symptoms were reported in Germany and Russia in the 1930s among workers mining and refining beryllium. By 1946, a cluster of cases associated with fluorescent lamp manufacturers were apparent in the United States, and the lamp industry stopped using beryllium in 1949. At that time, most construction trades and industries were unaware of the potential risks associated with beryllium exposure.
It occasionally killed early workers in nuclear weapons design, such as Herbert L. Anderson.
Beryllium sensitivity testing was first performed as a cutaneous beryllium patch test in the early 1950s, but was discontinued due to the test stimulating sensitization or aggravating existing chronic beryllium disease.
In the 1990s, the DOE began screening employees using the BeLPT test in facilities where beryllium was used, to take preventive measures against beryllium exposure. Somewhat alarmingly, clerical staff who were never involved in handling the material had developed asymptomatic sensitivities. | 1 | Applied and Interdisciplinary Chemistry |
Once an interactome has been created, there are numerous ways to analyze its properties. However, there are two important goals of such analyses. First, scientists try to elucidate the systems properties of interactomes, e.g. the topology of its interactions. Second, studies may focus on individual proteins and their role in the network. Such analyses are mainly carried out using bioinformatics methods and include the following, among many others: | 1 | Applied and Interdisciplinary Chemistry |
Indirect calorimetry measures O consumption and CO production. On the assumption that all the oxygen is used to oxidize degradable fuels and all the CO thereby evolved is recovered, it is possible to estimate the total amount of energy produced from the chemical energy of nutrients and converted into the chemical energy of ATP, with some loss of energy during the oxidation process.
Respiratory indirect calorimetry (IC) is a noninvasive and highly accurate method of metabolic rate, which has an error of less than 1%. It has high reproducibility and has been considered a gold standard method. This method allows estimating BEE and REE as well as identification of energy substrates that are predominantly metabolized by the body at a specific moment. It is based on the indirect measurement of the heat produced by oxidation of macronutrients, which is estimated by monitoring O consumption and CO production for a certain period of time.
The calorimeter has a gas collector that adapts to the subject and through a unidirectional valve minute by minute collects and quantifies the volume and concentration of O inspired and CO expired by the subject. After a volume is met, Resting Energy Expenditure is calculated by the Weir formula and results are displayed in software attached to the system. Another formula used is:
where RQ is the respiratory quotient (ratio of volume CO produced to volume of O consumed), is , the heat released per litre of oxygen by the oxidation of carbohydrate, and is , the value for fat. This gives the same result as the Weir formula at RQ = 1 (burning only carbohydrates), and almost the same value at RQ = 0.7 (burning only fat). | 1 | Applied and Interdisciplinary Chemistry |
Recent excavations in Middle Ganga Valley done by archaeologist Rakesh Tewari show iron working in India may have begun as early as 1800 BCE. Archaeological sites in India, such as Malhar, Dadupur, Raja Nala Ka Tila and Lahuradewa in the state of Uttar Pradesh show iron implements in the period between 1800 BCE – 1200 BCE. Sahi (1979: 366) concluded that by the early 13th century BCE, iron smelting was definitely practiced on a bigger scale in India, suggesting that the date the technology's inception may well be placed as early as the 16th century BCE.
The Black and Red Ware culture was another early Iron Age archaeological culture of the northern Indian subcontinent. It is dated to roughly the 12th – 9th centuries BCE, and associated with the post-Rigvedic Vedic civilization. It extended from the upper Gangetic plain in Uttar Pradesh to the eastern Vindhya range and West Bengal.
Perhaps as early as 500 BCE, although certainly by 200 CE, high quality steel was being produced in southern India by what Europeans would later call the crucible technique. In this system, high-purity wrought iron, charcoal, and glass were mixed in crucibles and heated until the iron melted and absorbed the carbon. The resulting high-carbon steel, called fūlāḏ by the Arabs () and wootz by later Europeans, was exported throughout much of Asia and Europe.
Will Durant wrote in The Story of Civilization I: Our Oriental Heritage: | 1 | Applied and Interdisciplinary Chemistry |
The Harbor Branch Oceanographic Institution licensed (+)-discodermolide to Novartis, which began a phase 1 clinical trial in 2004. The trial concluded that the drug resulted in minimal toxicities and represents a novel mechanism of action. Amos B. Smith's research group, in collaboration with Kosan Biosciences, has a preclinical drug development program ongoing. | 0 | Theoretical and Fundamental Chemistry |
There are a large number of different types of jet engines, all of which achieve forward thrust from the principle of jet propulsion. | 1 | Applied and Interdisciplinary Chemistry |
* Definition of the K or P-value
: The K or P-value always only refers to a single species or substance:
: with:
:* concentration of species i of a substance in the octanol-rich phase
:* concentration of species i of a substance in the water-rich phase
: If different species occur in the octanol-water system by dissociation or association, several P-values and one D-value exist for the system. If, on the other hand, the substance is only present in a single species, the P and D values are identical.
: P is usually expressed as a common logarithm, i.e. Log P (also Log P or, less frequently, Log pOW):
: Log P is positive for lipophilic and negative for hydrophilic substances or species.
* Definition of the D-value
: The P-value only correctly refers to the concentration ratio of a single substance distributed between the octanol and water phases. In the case of a substance that occurs as multiple species, it can therefore be calculated by summing the concentrations of all n species in the octanol phase and the concentrations of all n species in the aqueous phase:
: with:
:* concentration of the substance in the octanol-rich phase
:* concentration of the substance in the water-rich phase
: D values are also usually given in the form of the common logarithm as Log D:
: Like Log P, Log D is positive for lipophilic and negative for hydrophilic substances. While P values are largely independent of the pH value of the aqueous phase due to their restriction to only one species, D values are often strongly dependent on the pH value of the aqueous phase. | 0 | Theoretical and Fundamental Chemistry |
An iniferter is a chemical compound that simultaneously acts as initiator, transfer agent, and terminator (hence the name ini-fer-ter) in controlled free radical iniferter polymerizations, the most common is the dithiocarbamate type. | 0 | Theoretical and Fundamental Chemistry |
For macro PIV setups, lasers are predominant due to their ability to produce high-power light beams with short pulse durations. This yields short exposure times for each frame. Nd:YAG lasers, commonly used in PIV setups, emit primarily at 1064 nm wavelength and its harmonics (532, 266, etc.) For safety reasons, the laser emission is typically bandpass filtered to isolate the 532 nm harmonics (this is green light, the only harmonic able to be seen by the naked eye). A fiber-optic cable or liquid light guide might be used to direct the laser light to the experimental setup.
The optics consist of a spherical lens and cylindrical lens combination. The cylindrical lens expands the laser into a plane while the spherical lens compresses the plane into a thin sheet. This is critical as the PIV technique cannot generally measure motion normal to the laser sheet and so ideally this is eliminated by maintaining an entirely 2-dimensional laser sheet. The spherical lens cannot compress the laser sheet into an actual 2-dimensional plane. The minimum thickness is on the order of the wavelength of the laser light and occurs at a finite distance from the optics setup (the focal point of the spherical lens). This is the ideal location to place the analysis area of the experiment.
The correct lens for the camera should also be selected to properly focus on and visualize the particles within the investigation area. | 1 | Applied and Interdisciplinary Chemistry |
On the diagram, lines of constant pressure, constant temperature and volume are plotted, so in a two-phase region, the lines of constant pressure and temperature coincide.
Thus, coordinates on the diagram represent entropy and heat.
The work done in a process on vapor cycles is represented by length of , so it can be measured directly, whereas in a T–s diagram it has to be computed using thermodynamic relationship between thermodynamic properties.
In an isobaric process, the pressure remains constant, so the heat interaction is the change in enthalpy.
In an isenthalpic process, the enthalpy is constant. A horizontal line in the diagram represents an isenthalpic process.
A vertical line in the h–s chart represents an isentropic process. The process 3–4 in a Rankine cycle is isentropic when the steam turbine is said to be an ideal one. So the expansion process in a turbine can be easily calculated using the h–s chart when the process is considered to be ideal (which is the case normally when calculating enthalpies, entropies, etc. Later the deviations from the ideal values and they can be calculated considering the isentropic efficiency of the steam turbine used.)
Lines of constant dryness fraction (x), sometimes called the quality, are drawn in the wet region and lines of constant temperature are drawn in the superheated region. X gives the fraction (by mass) of gaseous substance in the wet region, the remainder being colloidal liquid droplets. Above the heavy line, the temperature is above the boiling point, and the dry (superheated) substance is gas only.
In general such charts do not show the values of specific volumes, nor do they show the enthalpies of saturated water at pressures which are of the order of those experienced in condensers in a thermal power station. Hence the chart is only useful for enthalpy changes in the expansion process of the steam cycle. | 0 | Theoretical and Fundamental Chemistry |
The plasticity region is at the top of deformation map (at the highest normalized stresses), and is below the boundary set by the ideal strength. In this region the strain rate involves an exponential term. This equation is shown below, where is the applied shear stress, is the shear modulus, is the energy barrier to dislocation glide, k is the Boltzmann constant, and is the "athermal flow strength" which is a function of the obstacles to dislocation glide. | 1 | Applied and Interdisciplinary Chemistry |
Espín served as a member of the Central Committee of the Cuban Communist Party from 1965 to 1989. She also held many other roles in the Cuban government, including chair of the Commission for Social Prevention from 1967 to 1971, director of Industrial Development in the Ministry of Food in 1969, president of the Institute of Childcare in 1971, and member of the Cuban Council of State in 1976. In addition to her roles within Cuba, Espín also served as Cuba's representative at the United Nations General Assembly.
Espín took on the role of Cuba's First Lady for 45 years, initially taking on the role as the sister-in-law to Fidel Castro, who was divorced at the time he came to power. She officially became the First Lady in 2006 when her husband, Raúl Castro, became president. Additionally, she was granted the title of "Secretary of State" in the Government of Cuba.
Espín headed the Cuban Delegation to the Congress of the International Federation of Democratic Women in Chile in September 1959. She also headed the Cuban delegations to subsequent Conferences on Women, praising them as "invaluable to women in developing countries." | 1 | Applied and Interdisciplinary Chemistry |
Some of the drugs that frequently interact with modafinil include aripiprazole (an antipsychotic), amphetamine (including its enantiomers and salts; stimulants), aspirin, diphenhydramine (an antihistamine), and others.
Modafinil is a weak to moderate inducer of CYP3A4 and a weak inhibitor of CYP2C19, enzymes of the cytochrome P450 group of enzymes. Modafinil also induces or inhibits other cytochrome P450 enzymes. One in vitro study predicts that modafinil may induce the cytochrome P450 enzymes CYP1A2, CYP3A4, and CYP2B6, as well as may inhibit CYP2C9 and CYP2C19. However, other in-vitro studies find no significant inhibition of CYP2C9. Modafinil may induce P-glycoprotein, which may affect drugs transported by P-glycoprotein, such as digoxin.
It was clinically found that modafinil affects pharmacodynamics of drugs which are metabolized by CYP3A4 and other enzymes of the cytochrome P450 family, so that interactions of modafinil with these drugs were observed in real people, rather than being predicted in a lab setting. For instance, it was observed that induction of CYP3A4 by modafinil affects metabolism of the following medications and endogenous substances:
* opioids, such as methadone, hydrocodone, oxycodone, or fentanyl – modafinil may result in a drop in opioid plasma concentrations because of faster clearance of opioids by CYP3A4. If the patient is not monitored closely, reduced efficacy or withdrawal symptoms can occur.
* steroid hormones, such as estradiol, progesterone or cortisol. Modafinil may have an adverse effect on hormonal contraceptives (such as birth control pills, patches, etc.) for up to a month after discontinuation. Both modafinil and armodafinil in the United States and the United Kingdom come with package inserts that highlight the interaction between these medications and hormonal birth control. Modafinil may induce cytochrome P450 enzymes that are involved in the clearance of steroid hormones taken as hormonal contraceptives, reducing their effectiveness, which may lead to pregnancy despite taking the birth control medication. Besides steroid hormones, modafinil may affect pituitary gland hormones. In a 2006 study, a single dose of modafinil caused a decrease in blood prolactin levels, although it did not affect human growth hormone or thyroid-stimulating hormone. Since modafinil induces the activity of the CYP3A4 enzyme involved in cortisol clearance, modafinil may reduce the bioavailability of hydrocortisone. Therefore, it may be necessary to adjust the steroid substitution dose in people receiving modafinil, which is a CYP3A4-metabolism-inducing drug. | 0 | Theoretical and Fundamental Chemistry |
:V10XA01 Sodium iodide (I)
:V10XA02 Iobenguane (I)
:V10XA03 Iodine (I) omburtamab
:V10XA53 Tositumomab/iodine (I) tositumomab | 1 | Applied and Interdisciplinary Chemistry |
There are two main approaches to definition of the spectral flux density at a measuring point in an electromagnetic radiative field. One may be conveniently here labelled the vector approach, the other the scalar approach. The vector definition refers to the full spherical integral of the spectral radiance (also known as the specific radiative intensity or specific intensity) at the point, while the scalar definition refers to the many possible hemispheric integrals of the spectral radiance (or specific intensity) at the point. The vector definition seems to be preferred for theoretical investigations of the physics of the radiative field. The scalar definition seems to be preferred for practical applications. | 0 | Theoretical and Fundamental Chemistry |
Reid vapor pressure (RVP) is a common measure of the volatility of gasoline and other petroleum products. It is defined as the
absolute vapor pressure exerted by the vapor of the liquid and any dissolved gases/moisture at 37.8 °C (100 °F) as determined by the test method ASTM-D-323, which was first developed in 1930 and has been revised several times (the latest version is ASTM D323-15a). The test method measures the vapor pressure of gasoline, volatile crude oil, jet fuels, naphtha, and other volatile petroleum products but is not applicable for liquefied petroleum gases. ASTM D323-15a requires that the sample be chilled to 0 to 1 degrees Celsius and then poured into the apparatus; for any material that solidifies at this temperature, this step cannot be performed. RVP is commonly reported in kilopascals (kPa) or pounds per square inch (psi) and represents volatization at atmospheric pressure because ASTM-D-323 measures the gauge pressure of the sample in a non-evacuated chamber.
The matter of vapor pressure is important relating to the function and operation of gasoline-powered, especially carbureted, vehicles and is also important for many other reasons. High levels of vaporization are desirable for winter starting and operation and lower levels are desirable in avoiding vapor lock during summer heat. Fuel cannot be pumped when there is vapor in the fuel line (summer) and winter starting will be more difficult when liquid gasoline in the combustion chambers has not vaporized. Thus, oil refineries manipulate the Reid vapor pressure seasonally specifically to maintain gasoline engine reliability.
The Reid vapor pressure (RVP) can differ substantially from the true vapor pressure (TVP) of a liquid mixture, since (1) RVP is the vapor pressure measured at 37.8 °C (100 °F) and the TVP is a function of the temperature; (2) RVP is defined as being measured at a vapor-to-liquid ratio of 4:1, whereas the TVP of mixtures can depend on the actual vapor-to-liquid ratio; (3) RVP will include the pressure associated with the presence of dissolved water and air in the sample (which is excluded by some but not all definitions of TVP); and (4) the RVP method is applied to a sample which has had the opportunity to volatilize somewhat prior to measurement: i.e., the sample container is required to be only 70-80% full of liquid (so that whatever volatilizes into the container headspace is lost prior to analysis); the sample then again volatilizes into the headspace of the D323 test chamber before it is heated to 37.8 degrees Celsius. | 0 | Theoretical and Fundamental Chemistry |
C photosynthesis (also called glycine shuttle and photorespiratory CO pump) is a CCM that works by making use of – as opposed to avoiding – photorespiration. It performs carbon refixation by delaying the breakdown of photorespired glycine, so that the molecule is shuttled from the mesophyll into the bundle sheath. Once there, the glycine is decarboxylated in mitochondria as usual, releasing CO and concentrating it to triple the usual concentration.
Although C photosynthesis is traditionally understood as an intermediate step between C and C, a wide variety of plant lineages do end up in the C stage without further evolving, showing that it is an evolutionary steady state of its own. C may be easier to engineer into crops, as the phenotype requires fewer anatomical changes to produce. | 0 | Theoretical and Fundamental Chemistry |
Based on preclinical trials, no-observed-adverse-effect levels (NOAELs) on drugs are established, which are used to determine initial phase 1 clinical trial dosage levels on a mass API per mass patient basis. Generally a 1/100 uncertainty factor or "safety margin" is included to account for interspecies (1/10) and inter-individual (1/10) differences. | 1 | Applied and Interdisciplinary Chemistry |
Among several solid electrolytes described in the 19th and early 20th century, α-AgI, the high-temperature crystalline form of silver iodide, is widely regarded as the most important one. Its electrical conduction was characterized by Carl Tubandt and E. Lorenz in 1914. Their comparative study of AgI, AgCl and AgBr demonstrated that α-AgI, is thermally stable and highly conductive between 147 and 555 °C; the conductivity weakly increased with temperature in this range and then dropped upon melting. This behavior was fully reversible and excluded non-equilibrium effects. Tubandt and Lorenz described other materials with a similar behavior, such as α-CuI, α-CuBr, β-CuBr, and high-temperature phases of AgS, AgSe and AgTe. They associated the conductivity with cations in silver and cuprous halides and with ions and electrons in silver chalcogenides. | 0 | Theoretical and Fundamental Chemistry |
For the simple reaction, the change in Gibbs energy is:
where a and a are the activities at equilibrium. The activities a are related to the concentrations c by a=γc where γ is the activity coefficient. The equilibrium potential is given by the Nernst equation:
where is the standard potential
Defining the formal potential:
the equilibrium potential is then:
Substituting this equilibrium potential into the Butler–Volmer equation yields:
which may also be written in terms of the standard rate constant k as:
The standard rate constant is an important descriptor of electrode behavior, independent of concentrations. It is a measure of the rate at which the system will approach equilibrium. In the limit as , the electrode becomes an ideal polarizable electrode and will behave electrically as an open circuit (neglecting capacitance). For nearly ideal electrodes with small k, large changes in the overpotential are required to generate a significant current. In the limit as , the electrode becomes an ideal non-polarizable electrode and will behave as an electrical short. For a nearly ideal electrodes with large k, small changes in the overpotential will generate large changes in current. | 0 | Theoretical and Fundamental Chemistry |
Isotopic tracers are used to examine processes in natural systems, especially terrestrial and aquatic environments. In soil science N tracers are used extensively to study nitrogen cycling, whereas C and C, stable and radioisotopes of carbon respectively, are used for studying turnover of organic compounds and fixation of by autotrophs. For example, Marsh et al. (2005) used dual labeled (N- and C) urea to demonstrate utilization of the compound by ammonia oxidizers as both an energy source (ammonia oxidation) and carbon source (chemoautotrophic carbon fixation). Deuterated water is also used for tracing the fate and ages of water in a tree or in an ecosystem. | 0 | Theoretical and Fundamental Chemistry |
The favored azaenolate is the dominant starting molecule for the subsequent alkylation reaction. There are two possible faces of accessing for any electrophile to react with. The steric interaction between the pyrrolidine ring and the electrophilic reagent hinders the attack of the electrophile from the top face. On the contrary, when the electrophile attacks from the bottom face, such unfavorable interaction does not exist. Therefore, the electrophilic attack proceeds from the sterically more accessible face. | 0 | Theoretical and Fundamental Chemistry |
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