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Observational longitudinal studies have further evaluated REMS T-score performance in the identification of patients at risk for fragility fracture. Specifically, in Adami et al., a group of more than 1.500 patients has undergone both DXA and REMS scans. Afterwards, these patients have been monitored for a period up to 5 years in order to estimate the incidence of fragility fractures in relationship with the T-score values previously obtained with both technologies. The study has demonstrated that REMS T-score is an effective parameter for the prediction of the occurrence of fragility fractures, leading the authors to positive conclusions about the effectiveness of REMS technology in the identification of patients at risk for osteoporotic fracture. | 0 | Theoretical and Fundamental Chemistry |
Although some of the steps in photosynthesis are still not completely understood, the overall photosynthetic equation has been known since the 19th century.
Jan van Helmont began the research of the process in the mid-17th century when he carefully measured the mass of the soil a plant was using and the mass of the plant as it grew. After noticing that the soil mass changed very little, he hypothesized that the mass of the growing plant must come from the water, the only substance he added to the potted plant. His hypothesis was partially accurate – much of the gained mass comes from carbon dioxide as well as water. However, this was a signaling point to the idea that the bulk of a plant's biomass comes from the inputs of photosynthesis, not the soil itself.
Joseph Priestley, a chemist and minister, discovered that when he isolated a volume of air under an inverted jar and burned a candle in it (which gave off CO), the candle would burn out very quickly, much before it ran out of wax. He further discovered that a mouse could similarly "injure" air. He then showed that a plant could restore the air the candle and the mouse had "injured."
In 1779, Jan Ingenhousz repeated Priestley's experiments. He discovered that it was the influence of sunlight on the plant that could cause it to revive a mouse in a matter of hours.
In 1796, Jean Senebier, a Swiss pastor, botanist, and naturalist, demonstrated that green plants consume carbon dioxide and release oxygen under the influence of light. Soon afterward, Nicolas-Théodore de Saussure showed that the increase in mass of the plant as it grows could not be due only to uptake of CO but also to the incorporation of water. Thus, the basic reaction by which organisms use photosynthesis to produce food (such as glucose) was outlined. | 0 | Theoretical and Fundamental Chemistry |
Prior to, and during the 1920s, refrigerators used toxic gases as refrigerants, including ammonia, sulphur dioxide, and chloromethane. Later in the 1920s after a series of fatal accidents involving the leaking of chloromethane from refrigerators, a major collaborative effort began between American corporations Frigidaire, General Motors, and DuPont to develop a safer, non-toxic alternative. Thomas Midgley Jr. of General Motors is credited for synthesizing the first chlorofluorocarbons. The Frigidaire corporation was issued the first patent, number 1,886,339, for the formula for CFCs on December 31, 1928. In a demonstration for the American Chemical Society, Midgley flamboyantly demonstrated all these properties by inhaling a breath of the gas and using it to blow out a candle in 1930.
By 1930, General Motors and Du Pont formed the Kinetic Chemical Company to produce Freon, and by 1935, over 8 million refrigerators utilizing R-12 were sold by Frigidaire and its competitors. In 1932, Carrier began using R-11 in the worlds first self-contained home air conditioning unit known as the "atmospheric cabinet". As a result of CFCs being largely non-toxic, they quickly became the coolant of choice in large air-conditioning systems. Public health codes in cities were revised to designate chlorofluorocarbons as the only gases that could be used as refrigerants in public buildings.
Growth in CFCs continued over the following decades leading to peak annual sales of over 1 billion USD with greater than 1 million metric tonnes being produced annually. It wasn't until 1974 that it was first discovered by two University of California chemists, Professor F. Sherwood Rowland and Dr. Mario Molina, that the use of chlorofluorocarbons were causing a significant depletion in atmospheric ozone concentrations. This initiated the environmental effort which eventually resulted in the enactment of the Montreal Protocol. | 1 | Applied and Interdisciplinary Chemistry |
This could happen in two different ways: ammonia itself might simply diffuse (as NH3) or be transported (as NH4+) across the cell membranes in and out of the extracellular space, or a shuttle system involving carrier molecules (amino acids) might be employed. Certainly, ammonia can diffuse across lipid membranes, and it has been shown that ammonia can be transported by K+/Cl− co-transporters. | 1 | Applied and Interdisciplinary Chemistry |
In thiol–disulfide exchange, a thiolate group displaces one sulfur atom in a disulfide bond . The original disulfide bond is broken, and its other sulfur atom is released as a new thiolate, carrying away the negative charge. Meanwhile, a new disulfide bond forms between the attacking thiolate and the original sulfur atom.
Thiolates, not thiols, attack disulfide bonds. Hence, thiol–disulfide exchange is inhibited at low pH (typically, below 8) where the protonated thiol form is favored relative to the deprotonated thiolate form. (The pK of a typical thiol group is roughly 8.3, but can vary due to its environment.)
Thiol–disulfide exchange is the principal reaction by which disulfide bonds are formed and rearranged in a protein. The rearrangement of disulfide bonds within a protein generally occurs via intra-protein thiol–disulfide exchange reactions; a thiolate group of a cysteine residue attacks one of the proteins own disulfide bonds. This process of disulfide rearrangement (known as disulfide shuffling) does not change the number of disulfide bonds within a protein, merely their location (i.e., which cysteines are bonded). Disulfide reshuffling is generally much faster than oxidation/reduction reactions, which change the number of disulfide bonds within a protein. The oxidation and reduction of protein disulfide bonds in vitro also generally occurs via thiol–disulfide exchange reactions. Typically, the thiolate of a redox reagent such as glutathione, dithiothreitol attacks the disulfide bond on a protein forming a mixed disulfide bond' between the protein and the reagent. This mixed disulfide bond when attacked by another thiolate from the reagent, leaves the cysteine oxidized. In effect, the disulfide bond is transferred from the protein to the reagent in two steps, both thiol–disulfide exchange reactions.
The in vivo oxidation and reduction of protein disulfide bonds by thiol–disulfide exchange is facilitated by a protein called thioredoxin. This small protein, essential in all known organisms, contains two cysteine amino acid residues in a vicinal arrangement (i.e., next to each other), which allows it to form an internal disulfide bond, or disulfide bonds with other proteins. As such, it can be used as a repository of reduced or oxidized disulfide bond moieties. | 0 | Theoretical and Fundamental Chemistry |
Adding a monolayer to the surface reduces the surface tension, and the surface pressure, is given by the following equation:
where is equal to the surface tension of the water and is the surface tension due to the monolayer. But the concentration-dependence of surface tension (similar to Langmuir isotherm) is as follows:
Thus,
or
The last equation indicates a relationship similar to ideal gas law. However, the concentration-dependence of surface tension is valid only when the solutions are dilute and concentrations are low. Hence, at very low concentrations of the surfactant, the molecules behave like ideal gas molecules.
Experimentally, the surface pressure is usually measured using the Wilhelmy plate. A pressure sensor/electrobalance arrangement detects the pressure exerted by the monolayer. Also monitored is the area to the side of the barrier which the monolayer resides.
A simple force balance on the plate leads to the following equation for the surface pressure:
only when . Here, and are the dimensions of the plate, and is the difference in forces. The Wilhelmy plate measurements give pressure – area isotherms that show phase transition-like behaviour of the LM films, as mentioned before (see figure below). In the gaseous phase, there is minimal pressure increase for a decrease in area. This continues until the first transition occurs and there is a proportional increase in pressure with decreasing area. Moving into the solid region is accompanied by another sharp transition to a more severe area dependent pressure. This trend continues up to a point where the molecules are relatively close packed and have very little room to move. Applying an increasing pressure at this point causes the monolayer to become unstable and destroy the monolayer forming polylayer structures towards the air phase. The surface pressure during the monolayer collapse may remain approximately constant (in a process near the equilibrium) or may decay abruptly (out of equilibrium - when the surface pressure was over-increased because lateral compression was too fast for monomolecular rearrangements). | 0 | Theoretical and Fundamental Chemistry |
Along with other aggregates, a hollow, spherical structure self-assembles from approximately 1,165 Mo wheels. This was termed a vesicle by analogy with lipid vesicles. Unlike lipid vesicles that are stabilised by hydrophobic interactions it is believed that the vesicle is stabilised by an interplay of van der Waals attraction, long-range electrostatic repulsion with further stabilization arising from hydrogen bonding involving water molecules encapsulated between the wheel-shaped clusters and in the vesicles' interior. The radius of the vesicle is 45 nm. | 0 | Theoretical and Fundamental Chemistry |
*If are the solutions for a particular value of , then solutions for other values of are obtained from the following integro-differential equations
* For conservative case, this integral property reduces to
*If the abbreviations for brevity are introduced, then we have a relation stating In the conservative, this reduces to
*If the characteristic function is , where are two constants, then we have .
*For conservative case, the solutions are not unique. If are solutions of the original equation, then so are these two functions , where is an arbitrary constant. | 0 | Theoretical and Fundamental Chemistry |
The transition state of a structure can best be described in regards to statistical mechanics where the energies of bonds breaking and forming have an equal probability of moving from the transition state backwards to the reactants or forward to the products. In enzyme-catalyzed reactions, the overall activation energy of the reaction is lowered when an enzyme stabilizes a high energy transition state intermediate. Transition state analogs mimic this high energy intermediate but do not undergo a catalyzed chemical reaction and can therefore bind much stronger to an enzyme than simple substrate or product analogs. | 1 | Applied and Interdisciplinary Chemistry |
In 2018, RT001 was given to a patient with amyotrophic lateral sclerosis (ALS) under a "compassionate use scheme". | 1 | Applied and Interdisciplinary Chemistry |
Bioretention controls the stormwater quantity through interception, infiltration, evaporation, and transpiration. First, rainfall is captured by plant tissue (leaves and stems) and in the soil micropores. Then, water performs infiltration - the downward movement of water through soil - and is stored in the soil until the substrate reaches its moisture capacity, when it begins to pool at the top of the bioretention feature. The pooled water and water from plant and soil surfaces is then evaporated into the atmosphere. Optimal design of bioretention sites aim for shallow pooled water to reach a higher rate of evaporation. Water also evaporates through the leaves of the plants in the feature and back to the atmosphere, which is a process known as evapotranspiration.
Stormwater quality can be controlled by bioretention through settling, filtration, assimilation, adsorption, degradation, and decomposition. When water pools on top of a bioretention feature, suspended solids and large particles will settle out. Dust particles, soil particles, and other small debris are filtered out of the water as it moves downward through the soil and interspersed plant roots. Plants take up some of the nutrients for use in their growth processes, or for mineral storage. Dissolved chemical substances from the water also bind to the surfaces of plant roots, soil particles, and other organic matter in the substrate and are rendered ineffective. Soil microorganisms break down remaining chemicals and small organic matter and effectively decompose the pollutants into a saturated soil matter.
Even though natural water purification is based on the design of planted areas, the key components of bioremediation are the soil quality and microorganism activity. These features are supported by plants, which create secondary pore space to increase soil permeability, prevent soil compaction through complex root structure growth, provide habitats for the microorganisms on the surfaces of their roots, and transport oxygen to the soil. | 1 | Applied and Interdisciplinary Chemistry |
Rouging is a form of corrosion found in stainless steel. It can be due to iron contamination of the stainless steel surface due to welding of non-stainless steel for support columns, or other temporary means, which when welded off leaves a low chromium area.
There are three classes of rouging: Class I, Class II, and Class III.
Class I – stainless steel surface and the Cr/Fe ratio of the metal surface beneath such deposits usually remain unaltered.
<br />Class II – Iron particles originating in-situ on unpassivated or improperly passivated stainless steel surfaces. By their formation the Cr/Fe ratio of the metal surface is altered.
<br />Class III – Iron oxide (or scale) which forms on surfaces in high temperature steam systems. The Cr/Fe ratio of the protective film is usually altered. | 1 | Applied and Interdisciplinary Chemistry |
The relation between mass concentration and density of a pure component (mass concentration of single component mixtures) is:
where is the density of the pure component, the volume of the pure component before mixing. | 0 | Theoretical and Fundamental Chemistry |
PG5 is the largest stable synthetic molecule ever made. PG5 was designed by the organic chemistry research group working at the Federal Institute of Technology in Zürich. | 0 | Theoretical and Fundamental Chemistry |
Embryonic biomarkers are very important to fetuses, as each cell's role is decided through the use of biomarkers. Research has been conducted concerning the use of embryonic stem cells (ESCs) in regenerative medicine. This is because certain biomarkers within a cell could be altered (most likely in the tertiary stage of their formation) to change the future role of the cell, thereby creating new ones. One example of an embryonic biomarker is the protein Oct-4. | 1 | Applied and Interdisciplinary Chemistry |
Tosyl phenylalanyl chloromethyl ketone (TPCK) is a protease inhibitor. Its structural formula is 1-chloro-3-tosylamido-4-phenyl-2-butanone. | 1 | Applied and Interdisciplinary Chemistry |
The first information about the atomic nucleus was obtained at the beginning of the 20th century by studying radioactivity. For a long period of time only three kinds of nuclear decay modes (alpha, beta, and gamma) were known. They illustrate three of the fundamental interactions in nature: strong, weak, and electromagnetic. Spontaneous fission became better studied soon after its discovery in 1940 by Konstantin Petrzhak and Georgy Flyorov because of both the military and the peaceful applications of induced fission. This was discovered circa 1939 by Otto Hahn, Lise Meitner, and Fritz Strassmann.
There are many other kinds of radioactivity, e.g. cluster decay, proton emission, various beta-delayed decay modes (p, 2p, 3p, n, 2n, 3n, 4n, d, t, alpha, f), fission isomers, particle accompanied (ternary) fission, etc. The height of the potential barrier, mainly of Coulomb nature, for emission of the charged particles is much higher than the observed kinetic energy of the emitted particles. The spontaneous decay can only be explained by quantum tunneling in a similar way to the first application of the Quantum Mechanics to Nuclei given by G. Gamow for alpha decay.
Usually the theory explains an already experimentally observed phenomenon. Cluster decay is one of the rare examples of phenomena predicted before experimental discovery. Theoretical predictions were made in 1980,
four years before experimental discovery.
Four theoretical approaches were used: fragmentation theory by solving a Schrödinger equation with mass asymmetry as a variable to obtain the mass distributions of fragments; penetrability calculations similar to those used in traditional theory of alpha decay, and superasymmetric fission models, numerical (NuSAF) and analytical (ASAF). Superasymmetric fission models are based on the macroscopic-microscopic approach
using the asymmetrical two-center shell model
level energies as input data for the shell and pairing corrections. Either the liquid drop model
or the Yukawa-plus-exponential model
extended to different charge-to-mass ratios
have been used to calculate the macroscopic deformation energy.
Penetrability theory predicted eight decay modes: C, Ne, Mg, Si, Ar, and Ca from the following parent nuclei: Ra, Th, U, Pu, Cm, Cf, Fm, and No.
The first experimental report was published in 1984, when physicists at Oxford University discovered that Ra emits one C nucleus among every billion (10) decays by alpha emission. | 0 | Theoretical and Fundamental Chemistry |
As you can see above, SFP can be expressed in units of pressure, since pressure is a measure of energy per m³ air. The relationship between SFP, fan pressure rise, and fan system efficiency is simply:
where:
* is the overall efficiency of the driven fan system [-]
* is the rise in total pressure though the fan [kPa]
In the case of an ideal lossless fan system (i.e. ) the SFP is exactly equal to the fan pressure rise (i.e. total pressure loss in the ventilation system). In reality the fan system efficiency is often in the range 0 to 60% (i.e. ); it is lowest for small fans or inefficient operating points (e.g. throttled flow or free-flow). The efficiency is a function of the total losses in the fan system, including aerodynamic losses in the fan, friction losses in the drive (e.g. belt), losses in the electric motor, and variable speed drive power electronics. For more insight into how to maximise energy efficiency and minimize noise in fan systems, see ref.1 | 1 | Applied and Interdisciplinary Chemistry |
Wades rules are successful in describing the geometry of the anionic sublattice of Zintl phases and of Zintl ions but not the electronic structure. Other spherical shell models with spherical harmonic wave functions for molecular orbitals—analogous to atomic orbitals—that describe the clusters as pseduo elements. The Jellium model uses a spherical potential from the nuclei to give orbitals with global nodal properties. Again, this formulates the cluster as a super atom' with an electron configuration comparable to a single atom. The model is best applied to spherically symmetric systems, and two examples for which it works well are the icosahedral Al and [Sn@Cu@Sn] clusters. DFT or ab initio molecular orbital calculations similarly treat the clusters with atomic, and correspondingly label them S, P, D etc. These closed shell configurations have prompted some investigation of 3D aromaticity. This concept was first suggested for fullerenes and corresponds to a 2(N+1) rule in the spherical shell model. An indicator of this phenomenon is a negative Nucleus Independent Chemical Shift (NICS) values of the center of the cluster or of certain additional high symmetry points. | 0 | Theoretical and Fundamental Chemistry |
An alternative approach to the identification and quantification of patient samples is through the use of mass spectrometry. This approach offers excellent precision and sensitivity in the identification, characterization and quantification of metabolites in multiple patient sample types, such as blood and urine. The mass spectrometry (MS) approach is typically coupled to gas chromatography (GC), in GC-MS or liquid chromatography (LC), in LC-MS, which aid in initially separating out the metabolite components within complex sample mixtures, and can allow for the isolation of particular metabolite subsets for analysis. GC-MS can provide relatively precise quantification of metabolites, as well as chemical structural information that can be compared to pre-existing chemical libraries. GC-MS can be conducted in a relatively high-throughput manner (greater than 100 samples per day) with greater detection sensitivity than NMR analysis. A limitation of GC-MS for this application, however, is that processed metabolite components must be readily volatilized for sample processing.
LC-MS initially separates out the components of a sample mixture based on properties such as hydrophobicity, before processing them for identification and quantification by mass spectrometry (MS). Overall, LC-MS is an extremely flexible method for processing most compound types in a somewhat high-throughput manner (20-100 samples a day), also with greater sensitivity than NMR analysis. For both GC-MS and LC-MS there are limitations in the reproducibility of metabolite quantification. Furthermore, sample processing for downstream mass spectrometry (MS) analysis is much more intensive than in NMR application, and results in the destruction of the original sample (via trypsin digestion).
Following identification and quantification of metabolites in individual patient samples, NMR and mass spectrometry (MS) output is compiled into a dataset. These datasets include information on the identity and levels of individual metabolites detected within processed samples, as well as characteristics of each metabolite during the detection process (e.g. mass-to-charge ratios for mass spectrometry (MS)-based analysis). Multiple datasets can be created and compiled into large databases for individual patients in order to monitor varying metabolic profiles over a treatment course (i.e. pre- and post-treatment profiles). Each database is then processed through a type of informatics platform with software designed to characterize and analyze the data to generate an overall metabolic profile for the patient. To generate this overall profile, computational programs are designed to:
* identify metabolic disease signatures
* assess treatment class (pre- or post-treatment)
* identify compounds present in a patient sample that may alter drug response, or be caused by a therapy
* identify metabolite variables and interactions among these variables
* map identified variables to known metabolic and biochemical pathways | 1 | Applied and Interdisciplinary Chemistry |
Sulfolene is formed by the cheletropic reaction between butadiene and sulfur dioxide. The reaction is typically conducted in an autoclave. Small amounts of hydroquinone or pyrogallol are added to inhibit polymerization of the diene. The reaction proceeds at room temperature over the course of days. At 130 °C, only 30 minutes are required. An analogous procedure gives the isoprene-derived sulfone. | 0 | Theoretical and Fundamental Chemistry |
The computation method Saltmod is based on seasonal water balances of agricultural lands. Four seasons in one year can be distinguished, e.g. dry, wet, cold, hot, irrigation or fallow seasons. The number of seasons (Ns) can be chosen between a minimum of one and a maximum of four. The larger the number of seasons becomes, the larger is the number of input data required. The duration of each season (Ts) is given in number of months (0 < Ts < 12). Day to day water balances are not considered for several reasons:
#daily inputs would require much information, which may not be readily available;
#the method is especially developed to predict long term, not day-to-day, trends and predictions for the future are more reliably made on a seasonal (long term) than on a daily (short term) basis, due to the high variability of short-term data;
#even though the precision of the predictions for the future may still not be very high, a lot is gained when the trend is sufficiently clear; for example, it need not be a major constraint to design appropriate soil salinity control measures when a certain salinity level, predicted by Saltmod to occur after 20 years, will in reality occur after 15 or 25 years. | 0 | Theoretical and Fundamental Chemistry |
Cerebrospinal fluid is found in the brain and spinal cord. It is a clear fluid that provides a barrier to absorb shock and prevent injury to the brain. It is useful for diagnosing neuro-degenerative diseases such as Alzheimers. There are various substances in the cerebrospinal fluid that can be measured including urea, glucose, potassium, chloride, sodium, protein, creatinine, calcium, alkaline phosphatase, and cortisol. Different things can be learned about the person or how the died by looking at the concentrations of some of these substances. For example, high levels of urea can indicate kidney damage. High levels of cortisol, the hormone released under stress, could indicate a violent death. Creatinine is stable post-mortem, so the concentration at death is preserved. This is also helpful to determine the kidney function of an individual. Sodium and Potassium can also be measured in the cerebrospinal fluid to predict the time since death, but it is not as accurate as it would be if the vitreous humor was used, since it has a lower correlation. | 1 | Applied and Interdisciplinary Chemistry |
The modification of the self-HLA, of TCR, or of the TCR-peptide-HLA complex by non-covalent, bindings of drugs is a reversible, transient process, whose effect is highly dependent on the affinity of drug-protein interactions. The drug can bind first to the HLA-peptide complex (p-i HLA) or the TCR complex (p-i TCR). Sometimes the drug may be trapped in between TCR and HLA.
P-i HLA is often linked with a striking HLA-association of the DHR (shown for abacavir, carbamazepine, allopurinol, dapson, vancomycin etc.), since the drug binds to a certain HLA-allele with higher affinity than to other HLA-molecules. P-i TCR is less investigated. Drug binding to certain parts of the TCR Vβ chains may be sufficient for full activation, if interaction with HLA-peptide complexes is possible; other p-i TCR bindings may require additional T cell activation (e.g. by viral infection) to lead to clinical symptoms.
The in vitro analysis of p-i using drug specific T cell clones (TCC) or TCR-transfected cell lines generated from patients with DH revealed a strong stimulation: A high level of T cell mediated cytotoxicity, a broad spectrum of secreted cytokines and polyclonality was observed; The p-i stimulation was unorthodox: some CD4+ T cells were uncharacteristically reacting to HLA-class I or CD8+ T cells to HLA-class II drug presentation or did not show strict HLA restriction, and some TCC were polyspecific (the reactive T cell clones reacted with various peptides): Altogether, the picture emerged that p-i induced T cell stimulations have features of allo-like immune stimulations (allo-stimulation). | 1 | Applied and Interdisciplinary Chemistry |
Social insect colonies are an excellent example of a decentralized system, because no individual is in charge of directing or making decisions for the colony. Several groups of social insects have been shown to use quorum sensing in a process that resembles collective decision-making. | 1 | Applied and Interdisciplinary Chemistry |
Zinc has five stable isotopes, tabulated along with their natural abundances below:
The isotopic composition of Zn is reported in delta notation (in ‰):
where Zn is a Zn isotope other than Zn (commonly either Zn or Zn). Standard reference materials used for Zn isotope measurements are JMC 3-0749C, NIST-SRM 683 or NIST-SRM 682. | 0 | Theoretical and Fundamental Chemistry |
In vertebrates, the majority of gene promoters contain a CpG island with numerous CpG sites. When many of a gene's promoter CpG sites are methylated the gene becomes inhibited (silenced). Colorectal cancers typically have 3 to 6 driver mutations and 33 to 66 hitchhiker or passenger mutations. However, transcriptional inhibition (silencing) may be of more importance than mutation in causing progression to cancer. For example, in colorectal cancers about 600 to 800 genes are transcriptionally inhibited by CpG island methylation (see regulation of transcription in cancer). Transcriptional repression in cancer can also occur by other epigenetic mechanisms, such as altered production of microRNAs. In breast cancer, transcriptional repression of BRCA1 may occur more frequently by over-produced microRNA-182 than by hypermethylation of the BRCA1 promoter (see Low expression of BRCA1 in breast and ovarian cancers). | 1 | Applied and Interdisciplinary Chemistry |
These reaction rates R can be calculated by following models:
# Laminar finite rate model
# Eddy dissipation model
# Eddy dissipation concept | 1 | Applied and Interdisciplinary Chemistry |
Improper maintenance would cause potential sources of fracture to go untreated and lead to premature failure of a component in the future. The reason for improper maintenance could be either intentional, such as skipping a yearly maintenance to avoid the cost, or unintentional, such as using the wrong engine oil. | 1 | Applied and Interdisciplinary Chemistry |
Alkaline phosphatase from E. coli can be purified using a DEAE-Cellulose matrix. A. phosphatase has a slight negative charge, allowing it to weakly bind to the positively charged amine groups in the matrix. The enzyme can then be eluted out by adding buffer with higher salt concentrations. | 0 | Theoretical and Fundamental Chemistry |
The practical uses of an instrument that uses a single probe are that it allows for the developing of a high throughput device. A high throughput surface tension device can be used for formulation in real time for understanding the penetration of drugs in the blood–brain barrier (BBB), understanding the solubility of drugs, development of a screen to test a drugs toxicity, determining the physicochemical properties of oxidized phospholipids, and development of new surfactant/polymers. | 0 | Theoretical and Fundamental Chemistry |
Cavitation has been applied to vegetable oil degumming and refining since 2011 and is considered a proven and standard technology in this application. The implementation of hydrodynamic cavitation in the degumming and refining process allows for a significant reduction in process aid, such as chemicals, water and bleaching clay, use. | 1 | Applied and Interdisciplinary Chemistry |
The substance loosely called selenium sulfide (with the approximate formula SeS) is the active ingredient in some anti-dandruff shampoos. The selenium compound kills the scalp fungus Malassezia, which causes shedding of dry skin fragments. The ingredient is also used in body lotions to treat Tinea versicolor due to infection by a different species of Malassezia fungus.
Several clinical trials have assessed the use of selenium supplements in critically ill adults; however, the effectiveness and potential benefits of selenium supplementation in this context is not well understood. | 1 | Applied and Interdisciplinary Chemistry |
Euglenophytes are a group of common flagellated protists that contain chloroplasts derived from a green alga. Euglenophyte chloroplasts have three membranes—it is thought that the membrane of the primary endosymbiont was lost, leaving the cyanobacterial membranes, and the secondary host's phagosomal membrane. Euglenophyte chloroplasts have a pyrenoid and thylakoids stacked in groups of three. Photosynthetic product is stored in the form of paramylon, which is contained in membrane-bound granules in the cytoplasm of the euglenophyte. | 0 | Theoretical and Fundamental Chemistry |
Silent antagonists are competitive receptor antagonists that have zero intrinsic activity for activating a receptor. They are true antagonists, so to speak. The term was created to distinguish fully inactive antagonists from weak partial agonists or inverse agonists. | 1 | Applied and Interdisciplinary Chemistry |
Hyperspectral imaging is part of a class of techniques commonly referred to as spectral imaging or spectral analysis. The term “hyperspectral imaging” derives from the development of NASA's Airborne Imaging Spectrometer (AIS) and AVIRIS in the mid-1980s. Although NASA prefers the earlier term “imaging spectroscopy” over “hyperspectral imaging,” use of the latter term has become more prevalent in scientific and non-scientific language. In a peer reviewed letter, experts recommend using the terms “imaging spectroscopy” or “spectral imaging” and avoiding exaggerated prefixes such as “hyper-,” “super-” and "ultra-,” to prevent misnomers in discussion.
Hyperspectral imaging is related to multispectral imaging. The distinction between hyper- and multi-band is sometimes based incorrectly on an arbitrary "number of bands" or on the type of measurement. Hyperspectral imaging (HSI) uses continuous and contiguous ranges of wavelengths (e.g. 400 - 1100 nm in steps of 1 nm) whilst multiband imaging (MSI) uses a subset of targeted wavelengths at chosen locations (e.g. 400 - 1100 nm in steps of 20 nm).
Multiband imaging deals with several images at discrete and somewhat narrow bands. Being "discrete and somewhat narrow" is what distinguishes multispectral imaging in the visible wavelength from color photography. A multispectral sensor may have many bands covering the spectrum from the visible to the longwave infrared. Multispectral images do not produce the "spectrum" of an object. Landsat is an excellent example of multispectral imaging.
Hyperspectral deals with imaging narrow spectral bands over a continuous spectral range, producing the spectra of all pixels in the scene. A sensor with only 20 bands can also be hyperspectral when it covers the range from 500 to 700 nm with 20 bands each 10 nm wide. (While a sensor with 20 discrete bands covering the visible, near, short wave, medium wave and long wave infrared would be considered multispectral.)
Ultraspectral could be reserved for interferometer type imaging sensors with a very fine spectral resolution. These sensors often have (but not necessarily) a low spatial resolution of several pixels only, a restriction imposed by the high data rate. | 0 | Theoretical and Fundamental Chemistry |
All metals can be classified into a galvanic series representing the electrical potential they develop in a given electrolyte against a standard reference electrode. The relative position of two metals on such a series gives a good indication of which metal is more likely to corrode more quickly. However, other factors such as water aeration and flow rate can influence the rate of the process markedly. | 1 | Applied and Interdisciplinary Chemistry |
The Avrami equation describes how solids transform from one phase to another at constant temperature. It can specifically describe the kinetics of crystallisation, can be applied generally to other changes of phase in materials, like chemical reaction rates, and can even be meaningful in analyses of ecological systems.
The equation is also known as the Johnson–Mehl–Avrami–Kolmogorov (JMAK) equation. The equation was first derived by Johnson, Mehl, Avrami and Kolmogorov (in Russian) in a series of articles published in the Journal of Chemical Physics between 1939 and 1941. Moreover, Kolmogorov treated statistically the crystallization of a solid in 1937 (in Russian, Kolmogorov, A. N., Izv. Akad. Nauk. SSSR., 1937, 3, 355). | 0 | Theoretical and Fundamental Chemistry |
Antonio de Ulloa (12 January 1716 – 3 July 1795) was a Spanish naval officer, scientist, and administrator. At the age of nineteen, he joined the French Geodesic Mission to what is now the country of Ecuador. That mission took more than eight years to complete its work, during which time Ulloa made many astronomical, natural, and social observations in South America. The reports of Ulloa's findings earned him an international reputation as a leading savant. Those reports include the first published observations of the metal platinum, later identified as a new chemical element. Ulloa was elected as a Fellow of the Royal Society of London in 1746, and as a foreign member of the Royal Swedish Academy of Sciences in 1751.
Ulloa served the Spanish Crown as governor of Huancavelica (1758–64), in Perú, and superintendent of the quicksilver mines in the region. Following the defeat of France in the Seven Years' War, Ulloa was appointed as the first Spanish governor of Louisiana in 1766. His rule was strongly resisted by the French Creole colonists in New Orleans, who expelled him from the city in the Louisiana Rebellion of 1768. Ulloa continued to serve in the Spanish Navy, achieving the rank of vice-admiral and becoming its chief of operations. | 1 | Applied and Interdisciplinary Chemistry |
Lanthanum aluminate is an inorganic compound with the formula LaAlO, often abbreviated as LAO. It is an optically transparent ceramic oxide with a distorted perovskite structure. | 0 | Theoretical and Fundamental Chemistry |
*amp = ampicillin resistance
*azi = azide resistance
*bla = beta-lactam resistance
*cat = chloramphenicol resistance
*kan = kanamycin resistance
*rif = rifampicin resistance
*tonA = phage T1 resistance | 1 | Applied and Interdisciplinary Chemistry |
It is an iron meteorite (medium octahedrite) and belongs to the chemical group IIIAB.
There are abundant elongated troilite nodules. The troilite nodules contain inclusions of chromite, sulfides, phosphates, silica and copper. The rare nitride mineral carlsbergite (CrN) occurs within the matrix of the metal phase. Graphite was not observed and the nitrogen isotopes are in disequilibrium. The meteoric iron is identifiable by a very high nickel content. | 1 | Applied and Interdisciplinary Chemistry |
* adenylosuccinate synthase converts IMP to adenylosuccinate
* adenylosuccinate lyase converts adenylosuccinate into AMP
* AMP deaminase converts AMP back into IMP | 1 | Applied and Interdisciplinary Chemistry |
Polytetrafluoroethylene (PTFE) is a synthetic fluoropolymer used in various applications including non-stick coatings. Teflon is a brand of PTFE, often used as a generic term for PTFE. The metallic substrate is roughened by abrasive blasting, then sometimes electric-arc sprayed with stainless steel. The irregular surface promotes adhesion of the PTFE and also resists abrasion of the PTFE. Then one to seven layers of PTFE are sprayed or rolled on, with a larger number of layers and spraying being better. The number and thickness of the layers and quality of the material determine the quality of the non-stick coating. Better-quality coatings are more durable, and less likely to peel and flake, and keep their non-stick properties for longer. Any PTFE-based coating will rapidly lose its non-stick properties if overheated; all manufacturers recommend that temperatures be kept below, typically, .
Utensils used with PTFE-coated pans can scratch the coating if the utensils are harder than the coating; this can be prevented by using non-metallic (usually plastic or wood) cooking tools. | 0 | Theoretical and Fundamental Chemistry |
By the early 1970s the climate for R&D was again changing.
Government R&D budgets continued to tighten.
The earlier pattern of Fulmer sponsorship, with a large proportion of contracts from UK ministries and government agencies, no longer applied. In 1955 this proportion had been 70% but by 1970 it had fallen to 45%. By 1985 it was to become less than 5%.
Meanwhile, contract R&D was becoming a familiar concept in the UK.
Following Fulmer, many other contract R&D companies had been formed, important examples being Huntingdon Life Sciences(1957) and Cambridge Consultants(1960).
This gave Fulmer opportunities for collaboration but also increased competition.
Fulmer promoted contract R&D by publishing Register of Consulting Scientists and Contract Research Organizations.
In 1971 Lord Rothschild published his report on Government R&D in which a major recommendation was that "applied R&D ... must be done on a customer-contractor basis. The customer says what he wants; the contractor does it (if he can); and the customer pays".
Despite Rothschild's recommendations, government procurement was slow to change. By 1975, leading independent research companies felt that they were not getting a fair share of government R&D contracts and needed a stronger voice. Fulmer joined with six other companies in setting up the Association of Independent Contract Research Organizations (AICRO).
The journal New Scientist published a special supplement on Contract Research in 1974
There were two major developments that intensified competition in Fulmer's market.
Firstly, organizations such as Harwell, which had been fully government funded, were seeking contracts from industry to make good their declining government income.
Secondly by 1969, following the Robbins Report(1963) on higher education, nine completely new universities had been founded and the ten existing Colleges of Advanced Technology had been converted into full universities.
Robbins found that in the existing universities, teachers spent a third of their time on teaching and rather less than a third on research.
He recommended that "The balance between teaching and research in the universities should in general be maintained."
The net effect was a huge expansion of R&D facilities in universities, funded by their block grants, and they were naturally keen to supplement their incomes with contracts using these facilities. | 1 | Applied and Interdisciplinary Chemistry |
Correct selection of the material by the design engineer affects the design life of a structure. Sometimes stainless steel is not the correct choice and carbon steel would be better. There is a misconception that stainless steel has excellent corrosion resistance and will not corrode. This is not always the case and should not be used to handle deoxygenated solutions for example, as the stainless steel relies on oxygen to maintain passivation and is also susceptible to crevice corrosion.
Galvanizing or hot-dip galvanizing is used to coat steel with a layer of metallic zinc. Lead or antimony are often added to the molten zinc bath, and also other metals have been studied. | 1 | Applied and Interdisciplinary Chemistry |
The World Health Organization in 1987 found that comfortable indoor temperatures of between were not associated with health risks for healthy adults with appropriate clothing, humidity, and other factors. For infants, elderly, and those with significant health problems, a minimum was recommended. Temperatures lower than with humidity above 65% were associated with respiratory hazards including allergies.
The WHO's 2018 guidelines give a strong recommendation that a minimum of is a "safe and well-balanced indoor temperature to protect the health of general populations during cold seasons". A higher minimum temperature may be necessary for vulnerable groups including children, the elderly, and people with cardiorespiratory disease and other chronic illnesses. However, the recommendation regarding risk of exposure to high indoor temperatures is only "conditional". Minimal-risk high temperatures range from about depending on the region, with maximum acceptable temperatures between . | 1 | Applied and Interdisciplinary Chemistry |
Aziridine is highly toxic with an LD of 14 mg (oral, rats). It is a skin irritant. As an alkylating agent, it is also a mutagen. It is reactive toward DNA, potentially relevant to its mutagenicity. Aziridine containing compounds also appear to be similarly dangerous. | 0 | Theoretical and Fundamental Chemistry |
POU class 1 homeobox 1, also known as pituitary-specific positive transcription factor 1 (PIT1), POU domain, class 1, transcription factor 1 (POU1F1) and growth hormone factor 1 (GHF1), is a transcription factor for growth hormone encoded by the gene POU1F1. | 1 | Applied and Interdisciplinary Chemistry |
Diamond battery is the name of a nuclear battery concept proposed by the University of Bristol Cabot Institute during its annual lecture held on 25 November 2016 at the Wills Memorial Building. This battery is proposed to run on the radioactivity of waste graphite blocks (previously used as neutron moderator material in graphite-moderated reactors) and would generate small amounts of electricity for thousands of years.
The battery is a betavoltaic cell using carbon-14 (C) in the form of diamond-like carbon (DLC) as the beta radiation source, and additional normal-carbon DLC to make the necessary semiconductor junction and encapsulate the carbon-14. | 0 | Theoretical and Fundamental Chemistry |
For example, a new radiolabelled compound is injected intravenously into a group of 16-20 rodents (typically mice or rats). At intervals of 1, 2, 4, and 24 hours, smaller groups (4-5) of the animals are euthanized, then dissected. The organs of interest (usually: blood, liver, spleen, kidney, muscle, fat, adrenals, pancreas, brain, bone, stomach, small intestine, and upper and lower large intestine, a tumor if present) are placed in pre-weighed containers and weighed, then placed into a device that measures radioactivity (e.g. gamma radiation). Normalizing the tissue radioactivity concentrations to the injected dose gives values in units of percent of the injected dose per gram of organ or biological tissue. The results give a dynamic view of how the compound moves through the animal and where it is retained. | 1 | Applied and Interdisciplinary Chemistry |
The calculation of K at a particular temperature from a known K at another given temperature can be approached as follows if standard thermodynamic properties are available. The effect of temperature on equilibrium constant is equivalent to the effect of temperature on Gibbs energy because:
where ΔG</sup> is the reaction standard Gibbs energy, which is the sum of the standard Gibbs energies of the reaction products minus the sum of standard Gibbs energies of reactants.
Here, the term "standard" denotes the ideal behaviour (i.e., an infinite dilution) and a hypothetical standard concentration (typically 1 mol/kg). It does not imply any particular temperature or pressure because, although contrary to IUPAC recommendation, it is more convenient when describing aqueous systems over wide temperature and pressure ranges.
The standard Gibbs energy (for each species or for the entire reaction) can be represented (from the basic definitions) as:
In the above equation, the effect of temperature on Gibbs energy (and thus on the equilibrium constant) is ascribed entirely to heat capacity. To evaluate the integrals in this equation, the form of the dependence of heat capacity on temperature needs to be known.
If the standard molar heat capacity C can be approximated by some analytic function of temperature (e.g. the Shomate equation), then the integrals involved in calculating other parameters may be solved to yield analytic expressions for them. For example, using approximations of the following forms:
*For pure substances (solids, gas, liquid):
*For ionic species at :
then the integrals can be evaluated and the following final form is obtained:
The constants A, B, C, a, b and the absolute entropy, S̆, required for evaluation of C(T), as well as the values of G and S for many species are tabulated in the literature. | 0 | Theoretical and Fundamental Chemistry |
These inequalities set a stringent maximum limit to the time step size and represents a serious limitation for the explicit scheme. This method is not recommended for general transient problems because the maximum possible time step has to be reduced as the square of . | 1 | Applied and Interdisciplinary Chemistry |
In 1956, two British scientists, John Barnes and Peter Magee, reported that a simple member of the large class of N-nitrosamines, dimethylnitrosamine, produced liver tumours in rats. Subsequent studies showed that approximately 90% of the 300 nitrosamines tested were carcinogenic in a wide variety of animals. | 0 | Theoretical and Fundamental Chemistry |
Sucrose esters are stable in the pH range of 4 to 8, so they can be used as an additive in most foods. At pH higher than 8, saponification (hydrolysis of the ester bond to release the original sucrose and the salt of fatty acids) might occur. Hydrolysis could also occur at pH lower than 4. | 0 | Theoretical and Fundamental Chemistry |
Until recently, the application of molecular evolution in the laboratory had been limited to display technologies involving biological molecules, where small molecules lead discovery was considered beyond this biological approach. DELs have opened the field of display technology to include non-natural compounds such as small molecules, extending the application of molecular evolution and natural selection to the identification of small molecule compounds of desired activity and function.
DNA encoded chemical libraries bear resemblance to biological display technologies such as antibody phage display technology, yeast display, mRNA display and aptamer SELEX. In antibody phage display, antibodies are physically linked to phage particles that bear the gene coding for the attached antibody, which is equivalent to a physical linkage of a “phenotype” (the protein) and a “genotype” (the gene encoding for the protein ). Phage-displayed antibodies can be isolated from large antibody libraries by mimicking molecular evolution: through rounds of selection (on an immobilized protein target), amplification and translation.
In DELs the linkage of a small molecule to an identifier DNA code allows the facile identification of binding molecules. DELs are subjected to affinity selection procedures on an immobilized target protein of choice, after which non-binders are removed by washing steps, and binders can subsequently be amplified by polymerase chain reaction (PCR) and identified by virtue of their DNA code (e.g.by DNA sequencing). In evolution-based DEL technologies hits can be further enriched by performing rounds of selection, PCR amplification and translation in analogy to biological display systems such as antibody phage display. This makes it possible to work with much larger libraries. | 1 | Applied and Interdisciplinary Chemistry |
Anthoxanthins (flavones and flavonols) are a type of flavonoid pigments in plants. Anthoxanthins are water-soluble pigments which range in color from white or colorless to a creamy to yellow, often on petals of flowers. These pigments are generally whiter in an acid medium and yellowed in an alkaline medium. They are very susceptible to color changes with minerals and metal ions, similar to anthocyanins. | 1 | Applied and Interdisciplinary Chemistry |
Yeast ATP synthase is one of the best-studied eukaryotic ATP synthases; and five F, eight F subunits, and seven associated proteins have been identified. Most of these proteins have homologues in other eukaryotes. | 0 | Theoretical and Fundamental Chemistry |
The reaction involving benzaldehyde was discovered by Claisen using sodium benzylate as base. The reaction produces benzyl benzoate.
Enolizable aldehydes are not amenable to Claisen's conditions. Vyacheslav Tishchenko discovered that aluminium alkoxides allowed the conversion of enolizable aldehydes to esters. | 0 | Theoretical and Fundamental Chemistry |
Aurin was first prepared in 1834 by the German chemist Friedlieb Ferdinand Runge, who obtained it by distilling coal tar. He named it Rosölsäure or Rosaölsäure (red oil acid). In 1861, the German chemists Hermann Kolbe and Rudolf Schmitt presented the synthesis of aurin by heating oxalic acid and creosote (which contains phenol) in the presence of concentrated sulfuric acid. (Gradually, chemists realized that commercial aurin was not a pure compound, but was actually a mixture of similar compounds.)
Aurin is formed by heating of phenol and oxalic acid in concentrated sulfuric acid. | 0 | Theoretical and Fundamental Chemistry |
The photodegradation of pesticides is of great interest because of the scale of agriculture and the intensive use of chemicals. Pesticides are however selected in part not to photodegrade readily in sunlight in order to allow them to exert their biocidal activity. Thus, more modalities are implemented to enhance their photodegradation, including the use of photosensitizers, photocatalysts (e.g., titanium dioxide), and the addition of reagents such as hydrogen peroxide that would generate hydroxyl radicals that would attack the pesticides. | 0 | Theoretical and Fundamental Chemistry |
The majority of current advancements in muscle tissue engineering reside in the skeletal muscle category, so the majority of these examples will have to do with skeletal muscle engineering and regeneration. We will review a couple of examples of smooth muscle tissue engineering and cardiac muscle tissue engineering in this section as well. | 1 | Applied and Interdisciplinary Chemistry |
While C enhances the efficiency of RuBisCO, the concentration of carbon is highly energy intensive. This means that C plants only have an advantage over C organisms in certain conditions: namely, high temperatures and low rainfall. C plants also need high levels of sunlight to thrive. Models suggest that, without wildfires removing shade-casting trees and shrubs, there would be no space for C plants. But, wildfires have occurred for 400 million years – why did C take so long to arise, and then appear independently so many times? The Carboniferous period (~) had notoriously high oxygen levels – almost enough to allow spontaneous combustion – and very low , but there is no C isotopic signature to be found. And there doesn't seem to be a sudden trigger for the Miocene rise.
During the Miocene, the atmosphere and climate were relatively stable. If anything, increased gradually from before settling down to concentrations similar to the Holocene. This suggests that it did not have a key role in invoking C evolution. Grasses themselves (the group which would give rise to the most occurrences of C) had probably been around for 60 million years or more, so had had plenty of time to evolve C, which, in any case, is present in a diverse range of groups and thus evolved independently. There is a strong signal of climate change in South Asia; increasing aridity – hence increasing fire frequency and intensity – may have led to an increase in the importance of grasslands. However, this is difficult to reconcile with the North American record. It is possible that the signal is entirely biological, forced by the fire- and grazer- driven acceleration of grass evolution – which, both by increasing weathering and incorporating more carbon into sediments, reduced atmospheric levels. Finally, there is evidence that the onset of C from is a biased signal, which only holds true for North America, from where most samples originate; emerging evidence suggests that grasslands evolved to a dominant state at least 15Ma earlier in South America. | 0 | Theoretical and Fundamental Chemistry |
Fluorescent labeling is known for its non-destructive nature and high sensitivity. This has made it one of the most widely used methods for labeling and tracking biomolecules. Several techniques of fluorescent labeling can be utilized depending on the nature of the target. | 1 | Applied and Interdisciplinary Chemistry |
The idea of eating "natural foods" was promoted by cookbook writers in the United States during the 1970s with cookbooks emphasizing "natural," "health" and "whole" foods in opposition to processed foods which were considered bad for health. In 1971, Eleanor Levitt authored The Wonderful World of Natural Food Cookery which dismissed processed foods such as readymade dinners, cookie mixes, and cold cuts as being full of preservatives and other "chemical poisons."
Jean Hewitt authored the New York Times Natural Foods Cookbook, an influential cookbook on the use of natural foods. Hewitt suggested that before large-scale mechanized farming and modern food production methods, people ate "fresh, natural and unrefined foods for granted" and but have since abandoned this way of eating for highly processed foods which are devoid of flavor and nutrition. Hewitt's cookbook offered "the textures, tastes and nutritional benefits of the natural, fresh foods that grandmother knew" and dedicated the recipes to "the thousands of people across the country who believe in, and practice, the natural way of eating for good health". | 1 | Applied and Interdisciplinary Chemistry |
* Institute of Organoelement Compounds. A. N. Nesmeyanov RAS. In front of Institute building a memorial bust was installed (sculptor Oleg Komov). At the Institute of the annual annual day of memory of A. N. Nesmeyanov with relatives and graduate students.
* On September 26, 1980, one of the streets of the Gagarinsky district of Moscow was named after Alexander Nikolayevich.
* Russian Academy of Sciences was founder Prize named after A.N. Nesmeyanov, awarded since 1994 for outstanding work in the field of chemistry of organoelement compounds.
* In December 1980, a stamp in memory of A. N. Nesmeyanov was issued in the USSR.
* Alexander Petrovich Kazantsev dedicated to him the novel The Dome of Hope felt the phrase: “To the vivid memory of America, the Hero of Socialist Labor, Academician Alexander Nikolayevich NESMEYANOV, as a token of admiration for his life and work, I dedicate this novel-dream. Author». | 0 | Theoretical and Fundamental Chemistry |
Anion-exchange chromatography is a process that separates substances based on their charges using an ion-exchange resin containing positively charged groups, such as diethyl-aminoethyl groups (DEAE). In solution, the resin is coated with positively charged counter-ions (cations). Anion exchange resins will bind to negatively charged molecules, displacing the counter-ion. Anion exchange chromatography is commonly used to purify proteins, amino acids, sugars/carbohydrates and other acidic substances with a negative charge at higher pH levels. The tightness of the binding between the substance and the resin is based on the strength of the negative charge of the substance. | 0 | Theoretical and Fundamental Chemistry |
Typical dispersities vary based on the mechanism of polymerization and can be affected by a variety of reaction conditions. In synthetic polymers, it can vary greatly due to reactant ratio, how close the polymerization went to completion, etc. For typical addition polymerization, Đ can range around 5 to 20. For typical step polymerization, most probable values of Đ are around 2 —Carothers' equation limits Đ to values of 2 and below.
Living polymerization, a special case of addition polymerization, leads to values very close to 1. Such is the case also in biological polymers, where the dispersity can be very close or equal to 1, indicating only one length of polymer is present. | 0 | Theoretical and Fundamental Chemistry |
Flucloxacillin can reduce the excretion of methotrexate, potentially resulting in a risk of methotrexate toxicity. The level of flucloxacillin in the blood may rise in kidney failure and with the use of probenecid. | 0 | Theoretical and Fundamental Chemistry |
The most common vehicle currently used for targeted drug delivery is the liposome. Liposomes are non-toxic, non-hemolytic, and non-immunogenic even upon repeated injections; they are biocompatible and biodegradable and can be designed to avoid clearance mechanisms (reticuloendothelial system (RES), renal clearance, chemical or enzymatic inactivation, etc.) Lipid-based, ligand-coated nanocarriers can store their payload in the hydrophobic shell or the hydrophilic interior depending on the nature of the drug/contrast agent being carried.
The only problem to using liposomes in vivo is their immediate uptake and clearance by the RES system and their relatively low stability in vitro. To combat this, polyethylene glycol (PEG) can be added to the surface of the liposomes. Increasing the mole percent of PEG on the surface of the liposomes by 4-10% significantly increased circulation time in vivo from 200 to 1000 minutes.
PEGylation of the liposomal nanocarrier elongates the half-life of the construct while maintaining the passive targeting mechanism that is commonly conferred to lipid-based nanocarriers. When used as a delivery system, the ability to induce instability in the construct is commonly exploited allowing the selective release of the encapsulated therapeutic agent in close proximity to the target tissue/cell in vivo. This nanocarrier system is commonly used in anti-cancer treatments as the acidity of the tumour mass caused by an over-reliance on glycolysis triggers drug release.
Additional endogenous trigger pathways have been explored through the exploitation of inner and outer tumor environments, such as reactive oxygen species, glutathione, enzymes, hypoxia, and adenosine-5’- triphosphate (ATP), all of which are generally highly present in and around tumors. External triggers are also used, such as light, low frequency ultrasound (LFUS), electrical fields, and magnetic fields. In specific, LFUS has demonstrated high efficacy in the controlled trigger of various drugs in mice, such as cisplatin and calcein. | 1 | Applied and Interdisciplinary Chemistry |
The compounds used as isotopic references have a relatively complex history. The broad evolution of reference materials for the hydrogen, carbon, oxygen, and sulfur stable isotope systems are shown in Figure 1. Materials with red text define the primary reference commonly reported in scientific publications and materials with blue text are those available commercially. The hydrogen, carbon, and oxygen isotope scales are defined with two anchoring reference materials. For hydrogen the modern scale is defined by VSMOW2 and SLAP2, and is reported relative to VSMOW. For carbon the scale is defined by either NBS-19 or IAEA-603 depending on the age of the lab, as well as LSVEC, and is reported relative to VPDB. Oxygen isotope ratios can be reported relative to either the VSMOW or VPDB scales. The isotopic scales for sulfur and nitrogen are both defined for only a single anchoring reference material. For sulfur the scale is defined by IAEA-S-1 and is reported relative to VCDT, while for nitrogen the scale is both defined by and reported relative to AIR. | 0 | Theoretical and Fundamental Chemistry |
To formally describe time-translation symmetry we say the equations, or laws, that describe a system at times and are the same for any value of and .
For example, considering Newton's equation:
One finds for its solutions the combination:
does not depend on the variable . Of course, this quantity describes the total energy whose conservation is due to the time-translation invariance of the equation of motion. By studying the composition of symmetry transformations, e.g. of geometric objects, one reaches the conclusion that they form a group and, more specifically, a Lie transformation group if one considers continuous, finite symmetry transformations. Different symmetries form different groups with different geometries. Time independent Hamiltonian systems form a group of time translations that is described by the non-compact, abelian, Lie group . TTS is therefore a dynamical or Hamiltonian dependent symmetry rather than a kinematical symmetry which would be the same for the entire set of Hamiltonians at issue. Other examples can be seen in the study of time evolution equations of classical and quantum physics.
Many differential equations describing time evolution equations are expressions of invariants associated to some Lie group and the theory of these groups provides a unifying viewpoint for the study of all special functions and all their properties. In fact, Sophus Lie invented the theory of Lie groups when studying the symmetries of differential equations. The integration of a (partial) differential equation by the method of separation of variables or by Lie algebraic methods is intimately connected with the existence of symmetries. For example, the exact solubility of the Schrödinger equation in quantum mechanics can be traced back to the underlying invariances. In the latter case, the investigation of symmetries allows for an interpretation of the degeneracies, where different configurations to have the same energy, which generally occur in the energy spectrum of quantum systems. Continuous symmetries in physics are often formulated in terms of infinitesimal rather than finite transformations, i.e. one considers the Lie algebra rather than the Lie group of transformations | 0 | Theoretical and Fundamental Chemistry |
*Johnson, D. W., Johnson, R. T., & Smith, K. A. (1998). Cooperative learning returns to college what evidence is there that it works?. Change: the magazine of higher learning, 30(4), 26–35.
*Smith, K.A. (2000). Going deeper: Formal small-group learning in large classes. In MacGregor, J., Cooper, J., Smith, K, and Robinson, P., eds. Strategies for Energizing Large Classes: From Small Groups to Learning Communities. New Directions for Teaching and Learning, 81, 25–46. San Francisco: Jossey-Bass.
*Johnson, D.W., Johnson, R.T., and Smith, K.A. (2000). Constructive controversy: The power of intellectual conflict. Change, 32 (1), 28–37.
*Wankat, P. C., Felder, R. M., Smith, K. A., & Oreovicz, F. S. (2002). The scholarship of teaching and learning in engineering. In M.T. Huber & S.P. Morreale, eds., Disciplinary styles in the scholarship of teaching and learning, 217–237.
*Smith, K. A., Sheppard, S. D., Johnson, D. W., & Johnson, R. T. (2005). Pedagogies of engagement: Classroom‐based practices. Journal of Engineering Education, 94(1), 87–101.
*Johnson, D. W., Johnson, R. T., & Smith, K. (2007). The state of cooperative learning in postsecondary and professional settings. Educational psychology review, 19, 15–29.
*Froyd, J. E., Wankat, P. C., & Smith, K. A. (2012). Five major shifts in 100 years of engineering education. Proceedings of the IEEE, 100(Special Centennial Issue), 1344–1360.
*Singer, S. & Smith, K.A. (2013). Discipline-Based Education Research: Understanding and Improving Learning in Undergraduate Science and Engineering. Guest Editorial. Journal of Engineering Education, 102, 468–471.
*Lichtenstein, G., Chen, H.L., Smith, K.A. & Maldonado, T.A. (2013). Retention and Persistence of Women and Minorities Along the Engineering Pathway in the United States. In A. Johri & B. Olds (Eds), Cambridge Handbook on Engineering Education Research.
*Johnson, D. W., Johnson, R. T., & Smith, K. A. (2014). Cooperative learning: Improving university instruction by basing practice on validated theory. Journal on Excellence in University Teaching, 25(4), 1-26.
*Streveler, R.A. & Smith, K.A. (2020). Opinion: Course Design in the Time of Coronavirus: Put on your Designer's CAP. Advances in Engineering Education, COVID-19 Issue.
*Smith, K.A. & Starfield, A.M. (2023). Reflections on modeling and teaching modeling. The Journal of Undergraduate Mathematics and Its Applications (UMAP), 44(2).
*Smith, K.A. & Felder, R.M. (2023). Cooperative Learning in Engineering Education: The Story of an Ongoing Uphill Climb. In Robyn Gillies, Barbara Millis, and Neil Davidson, eds. Contemporary Global Perspectives on Cooperative Learning. New York: Routledge. | 1 | Applied and Interdisciplinary Chemistry |
Titanium tetrachloride is the inorganic compound with the formula . It is an important intermediate in the production of titanium metal and the pigment titanium dioxide. is a volatile liquid. Upon contact with humid air, it forms thick clouds of titanium dioxide () and hydrochloric acid, a reaction that was formerly exploited for use in smoke machines. It is sometimes referred to as "tickle" or "tickle 4", as a phonetic representation of the symbols of its molecular formula (). | 0 | Theoretical and Fundamental Chemistry |
Particulate organic carbon (POC) is operationally defined as all combustible, non-carbonate carbon that can be collected on a filter. The oceanographic community has historically used a variety of filters and pore sizes, most commonly 0.7, 0.8, or 1.0 μm glass or quartz fiber filters. The biomass of living zooplankton is intentionally excluded from POC through the use of a pre-filter or specially designed sampling intakes that repel swimming organisms. Sub-micron particles, including most marine prokaryotes, which are 0.2–0.8 μm in diameter, are often not captured but should be considered part of POC rather than dissolved organic carbon (DOC), which is usually operationally defined as < 0.2 μm. Typically POC is considered to contain suspended and sinking particles ≥ 0.2 μm in size, which therefore includes biomass from living microbial cells, detrital material including dead cells, fecal pellets, other aggregated material, and terrestrially-derived organic matter. Some studies further divide POC operationally based on its sinking rate or size, with ≥ 51 μm particles sometimes equated to the sinking fraction. Both DOC and POC play major roles in the carbon cycle, but POC is the major pathway by which organic carbon produced by phytoplankton is exported – mainly by gravitational settling – from the surface to the deep ocean and eventually to sediments, and is thus a key component of the biological pump. | 0 | Theoretical and Fundamental Chemistry |
The Z-factor defines a characteristic parameter of the capability of hit identification for each given assay. The following categorization of HTS assay quality by the value of the Z-Factor is a modification of Table 1 shown in Zhang et al. (1999); note that the Z-factor cannot exceed one.
Note that by the standards of many types of experiments, a zero Z-factor would suggest a large effect size, rather than a borderline useless result as suggested above. For example, if σ=σ=1, then μ=6 and μ=0 gives a zero Z-factor. But for normally-distributed data with these parameters, the probability that the positive control value would be less than the negative control value is less than 1 in 10. Extreme conservatism is used in high throughput screening due to the large number of tests performed. | 1 | Applied and Interdisciplinary Chemistry |
Glass has been around since the Egyptian XVIII Dynasty, as the very earliest specimen is a glass bead that has been dated to that time during the reign of Queen Hatshepsut. Glass is very versatile, and there many different types of glass that serve various purposes, such as stained-glass windows, table glassware, and even glass photographic plates. This means that the treatment of these objects depends upon their uses and original purposes. Glass throughout the ages mostly consisted of glass drinking or eating vessels, and then evolved to be part of churches and housing in the form of window glass. According to the Victoria and Albert Museum, most glass is composed of silica (sand), alkali (usually soda or potash), an alkaline earth (lime) and a little waste glass. Other materials, such as lead and barium, could also be added to create a specialized effect in the finished product. Methods of cleaning have evolved from washing with water, to using special chemical cleansers especially made for glass, to even dismantling a large glass object, like a window, to be assessed and cleaned under a microscope in a lab. There was not a need to clean glass thoroughly until glass evolved as part of the 20th-century home, and it suddenly became important to keep glass windows clean and the common cleanser Windex came into the picture in the 1930s. For glass objects that are not window glass, the most common way of cleaning is by water if the glass object is intact and not super fragile. The Victoria and Albert Museum provides guidance about how to go about this way of cleaning. The methods of cleaning may differ if the glass is already damaged, extremely thin or fragile, or very old. | 0 | Theoretical and Fundamental Chemistry |
Prior to these studies, HPLC analyses were tuned by modifying the mobile and stationary phases only. Gradient elution for HPLC merely meant changing the ratio of solvents to improve column efficiency, and this requires the use of sophisticated solvent pumping mechanisms along with extra steps and precautions in the chromatographic analysis. Enlightened by the prospect of using temperature gradient elutions for HPLC analyses, Hosoya et al. sought to make surface modification of HPLC stationary phases more accessible. Their study utilizes graft-type copolymerization of PNIPAAm onto macroporous polymeric materials. The in-situ preparation compared the use of cyclohexanol and toluene as porogens in the preparation of the modified polystyrene seeds. Reverse-phased size-exclusion chromatography (SEC) revealed pore size and pore size distribution of the particles and its dependence on temperature. Cyclohexanol acted as a successful porogen showing a dependent relationship of pore size to temperature. The use of toluene as a porogen gave results that were similar to unmodified macroporous particles. This indicates that PNIPAAm can be successfully grafted onto the surface and within the pores of macroporous materials. The application of this preparatory technique gives rise to tunable pore sizes. Temperature gradient elutions can be used to improve column efficiency through the changing of pore size in SEC. The mechanism of the change in pore size is simple, the pores are smaller under LCST due to the elongated chains of PNIPAAm within the pores, as temperature increases to and above LCST, the chains retract into a globular formation increasing the pore size. | 0 | Theoretical and Fundamental Chemistry |
On Saturns largest moon, Titan, lakes of liquid hydrocarbons comprising methane, ethane, propane and other constituents, occur naturally. Data collected by the space probe Cassini–Huygens yield an estimate that the visible lakes and seas of Titan contain about 300 times the volume of Earths proven oil reserves. Drilled samples from the surface of Mars taken in 2015 by the Curiosity rover's Mars Science Laboratory have found organic molecules of benzene and propane in 3-billion-year-old rock samples in Gale Crater. | 0 | Theoretical and Fundamental Chemistry |
Phasor analysis is commonly used for fluorescence-lifetime imaging microscopy (FLIM) data analysis and has been adapted for pump–probe imaging data analysis. Signals are decomposed into their real and imaginary parts of the Fourier transform at a given frequency. By plotting the real and imaginary parts against one another, the distribution of different chromophores with distinct lifetimes can be mapped. In melanoma studies, this approach has again shown to be able to distinguish between the different forms of melanin. One of the main advantages of phasor analysis is that it provides an intuitive qualitative, graphical view of the content It has also been combined with PCA for quantitative analysis. | 0 | Theoretical and Fundamental Chemistry |
A Lorentzian line shape function can be represented as
where L signifies a Lorentzian function standardized, for spectroscopic purposes, to a maximum value of 1; is a subsidiary variable defined as
where is the position of the maximum (corresponding to the transition energy E), p is a position, and w is the full width at half maximum (FWHM), the width of the curve when the intensity is half the maximum intensity (this occurs at the points ). The unit of , and is typically wavenumber or frequency. The variable x is dimensionless and is zero at . | 0 | Theoretical and Fundamental Chemistry |
In alphabetic order
* Alanine transaminase (ALT)
* Body fat percentage
* Body mass index
* Body temperature
* Blood pressure
* Blood sugar level
* Complete blood count
* Creatinine
* C-reactive protein (inflammation)
* Glial fibrillary acidic protein (GFAP)
* Heart rate
* Hematocrit (HCT)
* Hemoglobin (Hgb)
* Mean corpuscular volume (MCV)
* Red Blood Cell Count (RBC)
* Thyroid-stimulating hormone (TSH)
* Triglyceride
* Troponin (cardiac TN-T, Tn-I)
* Ubiquitin carboxy-terminal hydrolase L1 (UCH-L1)
* Waist circumference
* Waist-to-hip ratio (WHR) | 1 | Applied and Interdisciplinary Chemistry |
The following are examples of cyclic compounds exhibiting more complex ring systems and stereochemical features: | 0 | Theoretical and Fundamental Chemistry |
Compressibility is an important factor in aerodynamics. At low speeds, the compressibility of air is not significant in relation to aircraft design, but as the airflow nears and exceeds the speed of sound, a host of new aerodynamic effects become important in the design of aircraft. These effects, often several of them at a time, made it very difficult for World War II era aircraft to reach speeds much beyond .
Many effects are often mentioned in conjunction with the term "compressibility", but regularly have little to do with the compressible nature of air. From a strictly aerodynamic point of view, the term should refer only to those side-effects arising as a result of the changes in airflow from an incompressible fluid (similar in effect to water) to a compressible fluid (acting as a gas) as the speed of sound is approached. There are two effects in particular, wave drag and critical mach.
One complication occurs in hypersonic aerodynamics, where dissociation causes an increase in the “notional” molar volume because a mole of oxygen, as O, becomes 2 moles of monatomic oxygen and N similarly dissociates to 2 N. Since this occurs dynamically as air flows over the aerospace object, it is convenient to alter the compressibility factor , defined for an initial 30 gram moles of air, rather than track the varying mean molecular weight, millisecond by millisecond. This pressure dependent transition occurs for atmospheric oxygen in the 2,500–4,000 K temperature range, and in the 5,000–10,000 K range for nitrogen.
In transition regions, where this pressure dependent dissociation is incomplete, both beta (the volume/pressure differential ratio) and the differential, constant pressure heat capacity greatly increases. For moderate pressures, above 10,000 K the gas further dissociates into free electrons and ions. for the resulting plasma can similarly be computed for a mole of initial air, producing values between 2 and 4 for partially or singly ionized gas. Each dissociation absorbs a great deal of energy in a reversible process and this greatly reduces the thermodynamic temperature of hypersonic gas decelerated near the aerospace object. Ions or free radicals transported to the object surface by diffusion may release this extra (nonthermal) energy if the surface catalyzes the slower recombination process. | 1 | Applied and Interdisciplinary Chemistry |
An acid dissociation constant is a particular example of an equilibrium constant. The dissociation of a monoprotic acid, HA, in dilute solution can be written as
The thermodynamic equilibrium constant can be defined by
where represents the activity, at equilibrium, of the chemical species X. is dimensionless since activity is dimensionless. Activities of the products of dissociation are placed in the numerator, activities of the reactants are placed in the denominator. See activity coefficient for a derivation of this expression.
Since activity is the product of concentration and activity coefficient (γ) the definition could also be written as
where represents the concentration of HA and is a quotient of activity coefficients.
To avoid the complications involved in using activities, dissociation constants are determined, where possible, in a medium of high ionic strength, that is, under conditions in which can be assumed to be always constant. For example, the medium might be a solution of 0.1 molar (M) sodium nitrate or 3 M potassium perchlorate. With this assumption,
is obtained. Note, however, that all published dissociation constant values refer to the specific ionic medium used in their determination and that different values are obtained with different conditions, as shown for acetic acid in the illustration above. When published constants refer to an ionic strength other than the one required for a particular application, they may be adjusted by means of specific ion theory (SIT) and other theories. | 0 | Theoretical and Fundamental Chemistry |
In 1961, Peter Mitchell proposed chemiosmosis as a cell's primary system of energy conversion. The mechanism, now ubiquitous in living cells, powers energy conversion in micro-organisms and in the mitochondria of eukaryotes, making it a likely candidate for early life. Mitochondria produce adenosine triphosphate (ATP), the energy currency of the cell used to drive cellular processes such as chemical syntheses. The mechanism of ATP synthesis involves a closed membrane in which the ATP synthase enzyme is embedded. The energy required to release strongly bound ATP has its origin in protons that move across the membrane. In modern cells, those proton movements are caused by the pumping of ions across the membrane, maintaining an electrochemical gradient. In the first organisms, the gradient could have been provided by the difference in chemical composition between the flow from a hydrothermal vent and the surrounding seawater, or perhaps meteoric quinones that were conducive to the development of chemiosmotic energy across lipid membranes if at a terrestrial origin. | 0 | Theoretical and Fundamental Chemistry |
Molecular propeller is a molecule that can propel fluids when rotated, due to its special shape that is designed in analogy to macroscopic propellers: it has several molecular-scale blades attached at a certain pitch angle around the circumference of a shaft, aligned along the rotational axis.
The molecular propellers designed in the group of Prof. Petr Král from the University of Illinois at Chicago have their blades formed by planar aromatic molecules and the shaft is a carbon nanotube. Molecular dynamics simulations show that these propellers can serve as efficient pumps in the bulk and at the surfaces of liquids. Their pumping efficiency depends on the chemistry of the interface between the blades and the liquid. For example, if the blades are hydrophobic, water molecules do not bind to them, and the propellers can pump them well. If the blades are hydrophilic, water molecules form hydrogen bonds with the atoms in the polar blades. This can largely block the flow of other water molecules around the blades and significantly slow down their pumping. | 0 | Theoretical and Fundamental Chemistry |
Drug repositioning is a "universal strategy" for neglected diseases due to 1) reduced number of required clinical trial steps could reduce the time and costs for the medicine to reach market, 2) existing pharmaceutical supply chains could facilitate "formulation and distribution" of the drug, 3) known possibility of combining with other drugs could allow more effective treatment, 4) the repositioning could facilitate the discovery of "new mechanisms of action for old drugs and new classes of medicines", 5) the removal of “activation barriers” of early research stages can enable the project to advance rapidly into disease-oriented research.
Often considered as a serendipitous approach, where repurposable drugs are discovered by chance, drug repurposing has heavily benefited from advances in human genomics, network biology, and chemoproteomics. It is now possible to identify serious repurposing candidates by finding genes involved in a specific disease and checking if they interact, in the cell, with other genes which are targets of known drugs. It was shown that drugs against targets supported by human genetics are twice as likely to succeed than overall drugs in the pharmaceutical pipeline. Drug repurposing can be a time and cost effective strategy for treating dreadful diseases such as cancer and is applied as a means of solution-finding to combat the COVID-19 pandemic.
Computational drug repurposing is the in silico screening of approved drugs for use against new indications. It can use molecular, clinical or biophysical data. Electronic health records and real-world evidence gained popularity in drug repurposing, for instance for COVID 19. Computational drug repurposing is expected to reduce drug development costs and time. | 1 | Applied and Interdisciplinary Chemistry |
Polymer scattering experiments are one of the main scientific methods used in chemistry, physics and other sciences to study the characteristics of polymeric systems: solutions, gels, compounds and more. As in most scattering experiments, it involves subjecting a polymeric sample to incident particles (with defined wavelengths), and studying the characteristics of the scattered particles: angular distribution, intensity polarization and so on. This method is quite simple and straightforward, and does not require special manipulations of the samples which may alter their properties, and hence compromise exact results.
As opposed to crystallographic scattering experiments, where the scatterer or "target" has very distinct order, which leads to well defined patterns (presenting Bragg peaks for example), the stochastic nature of polymer configurations and deformations (especially in a solution), gives rise to quite different results. | 0 | Theoretical and Fundamental Chemistry |
Countries in the Caspian region, particularly Azerbaijan, Kazakhstan and Turkmenistan, have high-value natural-resource-based economies, where the oil and gas compose more than 10 percent of their GDP and 40 percent of their exports. All the Caspian region economies are highly dependent on this type of mineral wealth. The world energy markets were influenced by Azerbaijan and Kazakhstan, as they became strategically crucial in this sphere, thus attracting the largest share of foreign direct investment (FDI).
All of the countries are rich in solar energy and harnessing potential, with the highest rainfall much less than the mountains of central Europe in the mountains of the west, which are also rich in hydroelectricity sources.
Iran has high fossil fuel energy potential. It has reserves of 137.5 billion barrels of crude oil, the fourth largest in the world, producing around four million barrels a day. Iran has an estimated 988.4 trillion cubic feet of natural gas, around 16 percent of world reserves, thus key to current paradigms in global energy security.
Russias economy ranks as the twelfth largest by nominal GDP and sixth largest by purchasing power parity in 2015. Russias extensive mineral and energy resources are the largest such reserves in the world, making it the second leading producer of oil and natural gas globally.
Caspian littoral states join efforts to develop infrastructure, tourism and trade in the region. The first Caspian Economic Forum was convened on August 12, 2019, in Turkmenistan and brought together representatives of Kazakhstan, Russia, Azerbaijan, Iran and that state. It hosted several meetings of their ministers of economy and transport.
The Caspian countries develop robust cooperation in the tech and digital field as part of the Caspian Digital Hub. The project helps expand data transmission capabilities in Kazakhstan as well as data transit capabilities between Asia and Europe. The project generated interest from investors from all over the world, including the UK. | 1 | Applied and Interdisciplinary Chemistry |
The rise of systems biology, seeking to comprehend biological processes as a whole, highlighted the need to not only develop corresponding quantitative models but also to create standards allowing their exchange and integration. This concern drove the community to design common data formats, such as SBML and CellML. SBML is now largely accepted and used in the field. However, as important as the definition of a common syntax is, it is also necessary to make clear the semantics of models. SBO tries to give us a way to label models with words that describe how they should be used in a large group of models that are commonly used in computational systems biology. The development of SBO was first discussed at the 9th SBML Forum Meeting in Heidelberg on October 14–15, 2004. During the forum, Pedro Mendes mentioned that modellers possessed a lot of knowledge that was necessary to understand the model and, more importantly, to simulate it, but this knowledge was not encoded in SBML. Nicolas Le Novère proposed to create a controlled vocabulary to store the content of Pedro Mendes' mind before he wandered out of the community. The development of the ontology was announced more officially in a message from Le Novère to Michael Hucka and Andrew Finney on October 19. | 1 | Applied and Interdisciplinary Chemistry |
In the mechanical stream of thinking about a process of transfer of energy between two bodies or closed systems, heat transferred is defined as a residual amount of energy transferred after the energy transferred as work has been determined, assuming for the calculation the law of conservation of energy, without reference to the concept of temperature. There are five main elements of the underlying theory.
*The existence of states of thermodynamic equilibrium, determinable by precisely one (called the non-deformation variable) more variable of state than the number of independent work (deformation) variables.
*That a state of internal thermodynamic equilibrium of a body have a well defined internal energy, that is postulated by the first law of thermodynamics.
*The universality of the law of conservation of energy.
*The recognition of work as a form of energy transfer.
*The universal irreversibility of natural processes.
*The existence of adiabatic enclosures.
*The existence of walls permeable only to heat.
Axiomatic presentations of this stream of thinking vary slightly, but they intend to avoid the notions of heat and of temperature in their axioms. It is essential to this stream of thinking that heat is not presupposed as being measurable by calorimetry. It is essential to this stream of thinking that, for the specification of the thermodynamic state of a body or closed system, in addition to the variables of state called deformation variables, there be precisely one extra real-number-valued variable of state, called the non-deformation variable, though it should not be axiomatically recognized as an empirical temperature, even though it satisfies the criteria for one. | 0 | Theoretical and Fundamental Chemistry |
Compared to the elemental form, potassium iodide has a median lethal dose (LD) that is relatively high in several animals: in rabbits, it is 10 g/kg; in rats, 14 g/kg, and in mice, 22 g/kg. The tolerable upper intake level for iodine as established by the Food and Nutrition Board is 1,100 µg/day for adults. The safe upper limit of consumption set by the Ministry of Health, Labor and Welfare in Japan is 3,000 µg/day.
The biological half-life of iodine differs between the various organs of the body, from 100 days in the thyroid, to 14 days in the kidneys and spleen, to 7 days in the reproductive organs. Typically the daily urinary elimination rate ranges from 100 to 200 µg/L in humans. However, the Japanese diet, high in iodine-rich kelp, contains 1,000 to 3,000 µg of iodine per day, and research indicates the body can readily eliminate excess iodine that is not needed for thyroid hormone production. The literature reports as much as 30,000 µg/L (30 mg/L) of iodine being safely excreted in the urine in a single day, with levels returning to the standard range in a couple of days, depending on seaweed intake. One study concluded the range of total body iodine content in males was 12.1 mg to 25.3 mg, with a mean of 14.6 mg. It is presumed that once thyroid-stimulating hormone is suppressed, the body simply eliminates excess iodine, and as a result, long-term supplementation with high doses of iodine has no additional effect once the body is replete with enough iodine. It is unknown if the thyroid gland is the rate-limiting factor in generating thyroid hormone from iodine and tyrosine, but assuming it is not, a short-term loading dose of one or two weeks at the tolerable upper intake level may quickly restore thyroid function in iodine-deficient patients.
Excessive iodine intake presents symptoms similar to those of iodine deficiency. Commonly encountered symptoms are abnormal growth of the thyroid gland and disorders in functioning, as well as in growth of the organism as a whole. Iodide toxicity is similar to (but not the same as) toxicity to ions of the other halogens, such as bromides or fluorides. Excess bromine and fluorine can prevent successful iodine uptake, storage and use in organisms, as both elements can selectively replace iodine biochemically.
Excess iodine may also be more cytotoxic in combination with selenium deficiency. Iodine supplementation in selenium-deficient populations is theoretically problematic, partly for this reason. Selenocysteine (abbreviated as Sec or U, in older publications also as Se-Cys) is the 21st proteinogenic amino acid, and is the root of iodide ion toxicity when there is a simultaneous insufficiency of biologically available selenium. Selenocysteine exists naturally in all kingdoms of life as a building block of selenoproteins. | 1 | Applied and Interdisciplinary Chemistry |
Another simple case of diffusion is the Brownian motion of one particle. The particle's Mean squared displacement from its original position is:
where is the dimension of the particle's Brownian motion. For example, the diffusion of a molecule across a cell membrane 8 nm thick is 1-D diffusion because of the spherical symmetry; However, the diffusion of a molecule from the membrane to the center of a eukaryotic cell is a 3-D diffusion. For a cylindrical cactus, the diffusion from photosynthetic cells on its surface to its center (the axis of its cylindrical symmetry) is a 2-D diffusion.
The square root of MSD, , is often used as a characterization of how far has the particle moved after time has elapsed. The MSD is symmetrically distributed over the 1D, 2D, and 3D space. Thus, the probability distribution of the magnitude of MSD in 1D is Gaussian and 3D is a Maxwell-Boltzmann distribution. | 0 | Theoretical and Fundamental Chemistry |
Polysaccharides (), or polycarbohydrates, are the most abundant carbohydrates found in food. They are long-chain polymeric carbohydrates composed of monosaccharide units bound together by glycosidic linkages. This carbohydrate can react with water (hydrolysis) using amylase enzymes as catalyst, which produces constituent sugars (monosaccharides, or oligosaccharides). They range in structure from linear to highly branched. Examples include storage polysaccharides such as starch, glycogen and galactogen and structural polysaccharides such as cellulose and chitin.
Polysaccharides are often quite heterogeneous, containing slight modifications of the repeating unit. Depending on the structure, these macromolecules can have distinct properties from their monosaccharide building blocks. They may be amorphous or even insoluble in water.
When all the monosaccharides in a polysaccharide are the same type, the polysaccharide is called a homopolysaccharide or homoglycan, but when more than one type of monosaccharide is present, they are called heteropolysaccharides or heteroglycans.
Natural saccharides are generally composed of simple carbohydrates called monosaccharides with general formula (CHO) where n is three or more. Examples of monosaccharides are glucose, fructose, and glyceraldehyde. Polysaccharides, meanwhile, have a general formula of C(HO) where x and y are usually large numbers between 200 and 2500. When the repeating units in the polymer backbone are six-carbon monosaccharides, as is often the case, the general formula simplifies to (CHO), where typically .
As a rule of thumb, polysaccharides contain more than ten monosaccharide units, whereas oligosaccharides contain three to ten monosaccharide units, but the precise cutoff varies somewhat according to the convention. Polysaccharides are an important class of biological polymers. Their function in living organisms is usually either structure- or storage-related. Starch (a polymer of glucose) is used as a storage polysaccharide in plants, being found in the form of both amylose and the branched amylopectin. In animals, the structurally similar glucose polymer is the more densely branched glycogen, sometimes called "animal starch". Glycogen's properties allow it to be metabolized more quickly, which suits the active lives of moving animals. In bacteria, they play an important role in bacterial multicellularity.
Cellulose and chitin are examples of structural polysaccharides. Cellulose is used in the cell walls of plants and other organisms and is said to be the most abundant organic molecule on Earth. It has many uses such as a significant role in the paper and textile industries and is used as a feedstock for the production of rayon (via the viscose process), cellulose acetate, celluloid, and nitrocellulose. Chitin has a similar structure but has nitrogen-containing side branches, increasing its strength. It is found in arthropod exoskeletons and in the cell walls of some fungi. It also has multiple uses, including surgical threads. Polysaccharides also include callose or laminarin, chrysolaminarin, xylan, arabinoxylan, mannan, fucoidan and galactomannan. | 0 | Theoretical and Fundamental Chemistry |
The Sommerfeld–Kossel displacement law states that the first spark (singly ionized) spectrum of an element is similar in all details to the arc (neutral) spectrum of the element preceding it in the periodic table. Likewise, the second (doubly ionized) spark spectrum of an element is similar in all details to the first (singly ionized) spark spectrum of the element preceding it, or to the arc (neutral) spectrum of the element with atomic number two less, and so forth.
Hence, the spectra of C I (neutral carbon), N II (singly ionized nitrogen), and O III (doubly ionized oxygen) atoms are similar, apart from shifts of the spectra to shorter wavelengths. C I, N II, and O III all have the same number of electrons, six, and the same ground-state electron configuration:
The law was discovered by and named after Arnold Sommerfeld and Walther Kossel, who set it forth in a paper submitted to Verhandungen der Deutschen Physikalischen Gesellschaft in early 1919. | 0 | Theoretical and Fundamental Chemistry |
With an appropriate exercise program, dietary supplementation with 3 grams of HMB per day has been shown to increase exercise-induced gains in muscle size, muscle strength and power, and lean body mass, reduce exercise-induced skeletal muscle damage, and expedite recovery from high-intensity exercise. Based upon limited clinical research, HMB supplementation may also improve aerobic exercise performance and increase gains in aerobic fitness when combined with high-intensity interval training. These effects of HMB are more pronounced in untrained individuals and athletes who perform high intensity resistance or aerobic exercise. In resistance-trained populations, the effects of HMB on muscle strength and lean body mass are limited. HMB affects muscle size, strength, mass, power, and recovery in part by stimulating myofibrillar muscle protein synthesis and inhibiting muscle protein breakdown through various mechanisms, including the activation of mechanistic target of rapamycin complex 1 (mTORC1) and inhibition of proteasome-mediated proteolysis in skeletal muscles.
The efficacy of HMB supplementation for reducing skeletal muscle damage from prolonged or high-intensity exercise is affected by the time that it is used relative to exercise. The greatest reduction in skeletal muscle damage from a single bout of exercise has been shown to occur when is ingested hours prior to exercise or is ingested minutes prior to exercise.
In 2006, only about 2% of college student athletes in the United States used HMB as a dietary supplement. As of 2017, HMB has found widespread use as an ergogenic supplement among athletes. HMB has not been banned by the National Collegiate Athletic Association, World Anti-Doping Agency, or any other prominent national or international athletic organization. | 1 | Applied and Interdisciplinary Chemistry |
Adenoviruses are viruses that carry their genetic material in the form of double-stranded DNA. They cause respiratory, intestinal, and eye infections in humans (especially the common cold). When these viruses infect a host cell, they introduce their DNA molecule into the host. The genetic material of the adenoviruses is not incorporated (transient) into the host cell's genetic material. The DNA molecule is left free in the nucleus of the host cell, and the instructions in this extra DNA molecule are transcribed just like any other gene. The only difference is that these extra genes are not replicated when the cell is about to undergo cell division so the descendants of that cell will not have the extra gene.
As a result, treatment with the adenovirus will require re-administration in a growing cell population although the absence of integration into the host cell's genome should prevent the type of cancer seen in the SCID trials. This vector system has been promoted for treating cancer and indeed the first gene therapy product to be licensed to treat cancer, Gendicine, is an adenovirus. Gendicine, an adenoviral p53-based gene therapy was approved by the Chinese food and drug regulators in 2003 for treatment of head and neck cancer. Advexin, a similar gene therapy approach from Introgen, was turned down by the US Food and Drug Administration (FDA) in 2008.
Concerns about the safety of adenovirus vectors were raised after the 1999 death of Jesse Gelsinger while participating in a gene therapy trial. Since then, work using adenovirus vectors has focused on genetically limited versions of the virus. | 1 | Applied and Interdisciplinary Chemistry |
A rapid antigen test (RAT), sometimes called a rapid antigen detection test (RADT), antigen rapid test (ART), or loosely just a rapid test, is a rapid diagnostic test suitable for point-of-care testing that directly detects the presence or absence of an antigen. RATs are a type of lateral flow test detecting antigens, rather than antibodies (antibody tests) or nucleic acid (nucleic acid tests). Rapid tests generally give a result in 5 to 30 minutes, require minimal training or infrastructure, and have significant cost advantages. Rapid antigen tests for the detection of SARS-CoV-2, the virus that causes COVID-19, have been commonly used during the COVID-19 pandemic.
For many years, an early and major class of RATs—the rapid strep tests for streptococci—were so often the referent when RATs or RADTs were mentioned that the two latter terms were often loosely treated as synonymous with those. Since the COVID-19 pandemic, awareness of RATs is no longer limited to health professionals and COVID-19 has become the expected referent, so more precise usage is required in other circumstances.
RATs are based on the principle of antigen-antibody interaction. They detect antigens (generally a protein on the surface of a virus). A linear chromatography substrate (a porous piece of material) bears an indicator line, onto which antibodies directed against the target antigen are fixed. Antibodies are also fixed to a visualisation marker (generally a dye, though sometimes these antibodies are modified to fluoresce), to which the sample is added. Any virus particles present will bind to these markers. This mix then travels through the substrate through capillarity. When it reaches the indicator line, virus particles are immobilised by the antibodies fixed there, along with the visualisation marker, allowing concentration and thus visual detection of significant levels of virus in a sample.
A positive result with an antigen test should generally be confirmed by RT-qPCR or some other test with higher sensitivity and specificity. | 1 | Applied and Interdisciplinary Chemistry |
Potency is the amount of agonist needed to elicit a desired response. The potency of an agonist is inversely related to its EC value. The EC can be measured for a given agonist by determining the concentration of agonist needed to elicit half of the maximum biological response of the agonist. The EC value is useful for comparing the potency of drugs with similar efficacies producing physiologically similar effects. The smaller the EC value, the greater the potency of the agonist, the lower the concentration of drug that is required to elicit the maximum biological response. | 1 | Applied and Interdisciplinary Chemistry |
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