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Earth systems engineering and management (ESEM) is a discipline used to analyze, design, engineer and manage complex environmental systems. It entails a wide range of subject areas including anthropology, engineering, environmental science, ethics and philosophy. At its core, ESEM looks to "rationally design and manage coupled human–natural systems in a highly integrated and ethical fashion". ESEM is a newly emerging area of study that has taken root at the University of Virginia, Cornell and other universities throughout the United States, and at the Centre for Earth Systems Engineering Research (CESER) at Newcastle University in the United Kingdom. Founders of the discipline are Braden Allenby and Michael Gorman. | 1 | Applied and Interdisciplinary Chemistry |
The amide tail synthesis (scheme 7) was based on an asymmetric Aldol reaction. The starting compound is the commercially available Benzyloxyacetic acid 53 which was converted to the thio ester 55 (Ethanethiol) through the acid chloride 54 (thionyl chloride, pyridine). This formed the silyl enol ether 55 (n-butyllithium, trimethylsilyl chloride, Diisopropylamine) which reacted with chiral amine catalyst 58, tin triflate and nBu(OAc) in a Mukaiyama aldol addition with benzaldehyde to alcohol 59 with 99% anti selectivity and 96% ee. The next step converting the alcohol group to an amine in 60 was a Mitsunobu reaction (hydrogen azide, diethyl azodicarboxylate, triphenylphosphine with azide reduction to amine by PhP). The amine group was benzoylated with benzoyl chloride (61) and hydrolysis removes the thioether group in 62. | 0 | Theoretical and Fundamental Chemistry |
Jöns Jacob Berzelius was a Swedish chemist who studied medicine at the University of Uppsala and was a professor of chemistry in Stockholm. He drew on the ideas of both Davy and Dalton to create an electrochemical view of how elements combined together. Berzelius classified elements into two groups, electronegative and electropositive depending which pole of a galvanic battery they were released from when decomposed. He created a scale of charge with oxygen being the most electronegative element and potassium the most electropositive. This scale signified that some elements had positive and negative charges associated with them and the position of an element on this scale and the elements charge determined how that element combined with others. Berzeliuss work on electrochemical atomic theory was published in 1818 as Essai sur la théorie des proportions chimiques et sur linfluence chimique de lélectricité. He also introduced a new chemical nomenclature into chemistry by representing elements with letters and abbreviations, such as O for oxygen and Fe for iron. Combinations of elements were represented as sequences of these symbols and the number of atoms were represented at first by superscripts and then later subscripts. | 1 | Applied and Interdisciplinary Chemistry |
Solomon is co-author of nine books, including an historical account of the development of plastic banknotes (The Plastic Banknote: From Concept to Reality) and several text books (including The Chemistry of Radical Polymerization). He is also co-author of over 250 journal papers and 45 patents. | 0 | Theoretical and Fundamental Chemistry |
Modern weather satellites produce imagery in a variety of spectra.
In the case of Landsat satellites, several different band designations have been used, with as many as 11 bands (Landsat 8) comprising a multispectral image. Spectral imaging with a higher radiometric resolution
(involving hundreds or thousands of bands), finer spectral resolution (involving smaller bands), or wider spectral coverage may be called hyperspectral or ultraspectral. | 0 | Theoretical and Fundamental Chemistry |
EPIC-seq may be more effective in cancers with prominent genes or well-defined molecular subtypes. Consequently, its utility may be limited in cancers with less distinct genetic profiles or those characterized by significant interpatient variability. This restricts its generalizability across different cancer types and necessitates cautious interpretation of results in diverse oncological contexts. | 1 | Applied and Interdisciplinary Chemistry |
The simplest liquid crystalline phase that is formed by spherical micelles is the micellar cubic, denoted by the symbol I. This is a highly viscous, optically isotropic phase in which the micelles are arranged on a cubic lattice. Prior to becoming macroscopic liquid crystals, tactoids are formed, which are liquid crystal microdomains in an isotrophic phase. At higher amphiphile concentrations the micelles fuse to form cylindrical aggregates of indefinite length, and these cylinders are arranged on a long-ranged hexagonal lattice. This lyotropic liquid crystalline phase is known as the hexagonal phase, or more specifically the normal topology hexagonal phase and is generally denoted by the symbol H.
At higher concentrations of amphiphile the lamellar phase is formed. This phase is denoted by the symbol L and can be considered the lyotropic equivalent of a smectic A mesophase. This phase consists of amphiphilic molecules arranged in bilayer sheets separated by layers of water. Each bilayer is a prototype of the arrangement of lipids in cell membranes.
For most amphiphiles that consist of a single hydrocarbon chain, one or more phases having complex architectures are formed at concentrations that are intermediate between those required to form a hexagonal phase and those that lead to the formation of a lamellar phase. Often this intermediate phase is a bicontinuous cubic phase.
Increasing the amphiphile concentration beyond the point where lamellar phases are formed would lead to the formation of the inverse topology lyotropic phases, namely the inverse cubic phases, the inverse hexagonal columnar phase (columns of water encapsulated by amphiphiles, (H) and the inverse micellar cubic phase (a bulk liquid crystal sample with spherical water cavities). In practice inverse topology phases are more readily formed by amphiphiles that have at least two hydrocarbon chains attached to a headgroup. The most abundant phospholipids that are found in cell membranes of mammalian cells are examples of amphiphiles that readily form inverse topology lyotropic phases.
Even within the same phases, self-assembled structures are tunable by the concentration: For example, in lamellar phases, the layer distances increase with the solvent volume. Since lyotropic liquid crystals rely on a subtle balance of intermolecular interactions, it is more difficult to analyze their structures and properties than those of thermotropic liquid crystals.
The objects created by the amphiphiles are usually spherical (as in the case of micelles), but may also be disc-like (bicelles), rod-like, or biaxial (all three micelle axes are distinct). These anisotropic self-assembled nano-structures can then order themselves in much the same way as thermotropic liquid crystals do, forming large-scale versions of all the thermotropic phases (such as a nematic phase of rod-shaped micelles). | 0 | Theoretical and Fundamental Chemistry |
Recrystallization is prevented or significantly slowed by a dispersion of small, closely spaced particles due to Zener pinning on both low- and high-angle grain boundaries. This pressure directly opposes the driving force arising from the dislocation density and will influence both the nucleation and growth kinetics. The effect can be rationalized with respect to the particle dispersion level where is the volume fraction of the second phase and r is the radius. At low the grain size is determined by the number of nuclei, and so initially may be very small. However the grains are unstable with respect to grain growth and so will grow during annealing until the particles exert sufficient pinning pressure to halt them. At moderate the grain size is still determined by the number of nuclei but now the grains are stable with respect to normal growth (while abnormal growth is still possible). At high the unrecrystallized deformed structure is stable and recrystallization is suppressed. | 1 | Applied and Interdisciplinary Chemistry |
Few commercial applications exist for bioplastics. Cost and performance remain problematic. Typical is the example of Italy, where biodegradable plastic bags are compulsory for shoppers since 2011 with the introduction of a specific law. Beyond structural materials, electroactive bioplastics are being developed that promise to carry electric current.
Bioplastics are used for disposable items, such as packaging, crockery, cutlery, pots, bowls, and straws.
Biopolymers are available as coatings for paper rather than the more common petrochemical coatings.
Bioplastics called drop-in bioplastics are chemically identical to their fossil-fuel counterparts but made from renewable resources. Examples include bio-PE, bio-PET, bio-propylene, bio-PP, and biobased nylons. Drop-in bioplastics are easy to implement technically, as existing infrastructure can be used. A dedicated bio-based pathway allows to produce products that cannot be obtained through traditional chemical reactions and can create products which have unique and superior properties, compared to fossil-based alternatives. | 0 | Theoretical and Fundamental Chemistry |
Tertiary (3°) phosphines, with the formula RP, are traditionally prepared by alkylation of phosphorus trichloride using Grignard reagents or related organolithium compounds:
:3RMgX + PCl → PR + 3MgX
In the case of trimethylphosphine, triphenyl phosphite is used in place of the highly electrophilic PCl:
: 3 CHMgBr + P(OCH) → P(CH) + 3 CHOMgBr
Slightly more elaborate methods are employed for the preparation of unsymmetrical tertiary phosphines, with the formula RR'P. The use of organophosphorus-based nucleophiles is typical. For example, lithium diphenylphosphide is readily methylated with methyl iodide to give methyldiphenylphosphine:
:LiiP(CH) + CHI → CHP(CH) + LiI
Phosphine is a precursor to some tertiary phosphines by hydrophosphination of alkenes. For example, in the presence of basic catalysts PH adds of Michael acceptors such as acrylonitrile:
:PH + 3 CH=CHZ → P(CHCHZ) (Z = NO, CN, C(O)NH)
Tertiary phosphines of the type PRR′R″ are "P-chiral" and optically stable.
From the commercial perspective, the most important phosphine is triphenylphosphine, several million kilograms being produced annually. It is prepared from the reaction of chlorobenzene, PCl, and sodium. Phosphines of a more specialized nature are usually prepared by other routes. | 0 | Theoretical and Fundamental Chemistry |
Directional solidification uses a thermal gradient to promote nucleation of metal grains on a low temperature surface, as well as to promote their growth along the temperature gradient. This leads to grains elongated along the temperature gradient, and significantly greater creep resistance parallel to the long grain direction. In polycrystalline turbine blades, directional solidification is used to orient the grains parallel to the centripetal force. It is also known as dendritic solidification. | 1 | Applied and Interdisciplinary Chemistry |
HNF4 (Hepatocyte Nuclear Factor 4) is a nuclear receptor protein mostly expressed in the liver, gut, kidney, and pancreatic beta cells that is critical for liver development. In humans, there are two paralogs of HNF4, HNF4α and HNF4γ, encoded by two separate genes and respectively. | 1 | Applied and Interdisciplinary Chemistry |
Interleukin 6 (acronym: IL-6) is a cytokine that is important for many aspects of cellular biology including immune responses, cell survival, apoptosis, as well as proliferation. Several studies have outlined the importance of autocrine IL-6 signaling in lung and breast cancers. For example, one group found a positive correlation between persistently activated tyrosine-phosphorylated STAT3 (pSTAT3), found in 50% of lung adenocarcinomas, and IL-6. Further investigation revealed that mutant EGFR could activate the oncogenic STAT3 pathway via upregulated IL-6 autocrine signaling.
Similarly, HER2 overexpression occurs in approximately a quarter of breast cancers and correlates with poor prognosis. Recent research revealed that IL-6 secretion induced by HER2 overexpression activated STAT3 and altered gene expression, resulting in an autocrine loop of IL-6/STAT3 expression. Both mouse and human in vivo models of HER2-overexpressing breast cancers relied critically on this HER2–IL-6–STAT3 signaling pathway. Another group found that high serum levels of IL-6 correlated with poor outcome in breast cancer tumors. Their research showed that autocrine IL-6 signaling induced malignant features in Notch-3 expressing mammospheres. | 1 | Applied and Interdisciplinary Chemistry |
In both prokaryotes and eukaryotes signal sequences may act co-translationally or post-translationally.
The co-translational pathway is initiated when the signal peptide emerges from the ribosome and is recognized by the signal-recognition particle (SRP). SRP then halts further translation (translational arrest only occurs in Eukaryotes) and directs the signal sequence-ribosome-mRNA complex to the SRP receptor, which is present on the surface of either the plasma membrane (in prokaryotes) or the ER (in eukaryotes). Once membrane-targeting is completed, the signal sequence is inserted into the translocon. Ribosomes are then physically docked onto the cytoplasmic face of the translocon and protein synthesis resumes.
The post-translational pathway is initiated after protein synthesis is completed. In prokaryotes, the signal sequence of post-translational substrates is recognized by the SecB chaperone protein that transfers the protein to the SecA ATPase, which in turn pumps the protein through the translocon. Although post-translational translocation is known to occur in eukaryotes, it is poorly understood. It is known that in yeast post-translational translocation requires the translocon and two additional membrane-bound proteins, Sec62 and Sec63. | 1 | Applied and Interdisciplinary Chemistry |
The purpose of using RNA FISH is to detect target mRNA transcripts in cells, tissue sections, or even whole-mounts. The process is done in 3 main procedures: tissue preparation (pre-hybridization), hybridization, and washing (post-hybridization).
The tissue preparation starts by collecting the appropriate tissue sections to perform RNA FISH. First, cells, circulating tumor cells (CTCs), formalin-fixed paraffin-embedded (FFPE), or frozen tissue sections are fixed. Some commonly used fixatives are 4% formaldehyde or paraformaldehyde (PFA) in phosphate buffered saline (PBS). FISH has also been successfully done on unfixed cells. After fixation, samples are permeabilized to allow the penetration of hybridization reagents. The use of detergents at a 0.1% concentration is commonly used to enhance the tissue permeability such as Tween-20 or Triton X-100.
It is critical for the hybridization process to have all optimal conditions to have a successful in situ result, including temperature, pH, salt concentration, and time of the hybridization reaction. After checking all the necessary conditions, hybridization steps can be started by first adding a target-specific probe, composed of 20 oligonucleotide pairs, hybridizes to the target RNA(s). Separate but compatible signal amplification systems enable the multiplex assay (up to two targets per assay). Signal amplification is achieved via series of sequential hybridization steps.
After the hybridization steps, washing steps are performed. These steps aim to remove nonspecific hybrids and get rid of unbound probe molecules from the samples to reduce any background signaling. The use of ethanol washes are typically used at this stage to reduce autofluorescence in tissues or cells. At the end of the assay the tissue samples are visualized under a fluorescence microscope such as the confocal fluorescence microscope and the Keyence microscope. | 1 | Applied and Interdisciplinary Chemistry |
When carbon dioxide binds to hemoglobin, carbaminohemoglobin is formed, lowering hemoglobin's affinity for oxygen via the Bohr effect. The reaction is formed between a carbon dioxide molecule and an amino residue. In the absence of oxygen, unbound hemoglobin molecules have a greater chance of becoming carbaminohemoglobin. The Haldane effect relates to the increased affinity of de-oxygenated hemoglobin for Hydron (chemistry)|: offloading of oxygen to the tissues thus results in increased affinity of the hemoglobin for carbon dioxide, and , which the body needs to get rid of, which can then be transported to the lung for removal. Because the formation of this compound generates hydrogen ions, haemoglobin is needed to buffer it.
Hemoglobin can bind to four molecules of carbon dioxide. The carbon dioxide molecules form a carbamate with the four terminal-amine groups of the four protein chains in the deoxy form of the molecule. Thus, one hemoglobin molecule can transport four carbon dioxide molecules back to the lungs, where they are released when the molecule changes back to the oxyhemoglobin form. | 1 | Applied and Interdisciplinary Chemistry |
The mouth is the first part of the upper gastrointestinal tract and is equipped with several structures that begin the first processes of digestion. These include salivary glands, teeth and the tongue. The mouth consists of two regions; the vestibule and the oral cavity proper. The vestibule is the area between the teeth, lips and cheeks, and the rest is the oral cavity proper. Most of the oral cavity is lined with oral mucosa, a mucous membrane that produces a lubricating mucus, of which only a small amount is needed. Mucous membranes vary in structure in the different regions of the body but they all produce a lubricating mucus, which is either secreted by surface cells or more usually by underlying glands. The mucous membrane in the mouth continues as the thin mucosa which lines the bases of the teeth. The main component of mucus is a glycoprotein called mucin and the type secreted varies according to the region involved. Mucin is viscous, clear, and clinging. Underlying the mucous membrane in the mouth is a thin layer of smooth muscle tissue and the loose connection to the membrane gives it its great elasticity. It covers the cheeks, inner surfaces of the lips, and floor of the mouth, and the mucin produced is highly protective against tooth decay.
The roof of the mouth is termed the palate and it separates the oral cavity from the nasal cavity. The palate is hard at the front of the mouth since the overlying mucosa is covering a plate of bone; it is softer and more pliable at the back being made of muscle and connective tissue, and it can move to swallow food and liquids. The soft palate ends at the uvula. The surface of the hard palate allows for the pressure needed in eating food, to leave the nasal passage clear. The opening between the lips is termed the oral fissure, and the opening into the throat is called the fauces.
At either side of the soft palate are the palatoglossus muscles which also reach into regions of the tongue. These muscles raise the back of the tongue and also close both sides of the fauces to enable food to be swallowed. Mucus helps in the mastication of food in its ability to soften and collect the food in the formation of the bolus. | 1 | Applied and Interdisciplinary Chemistry |
In many instances, the oscillatory flow in the fluid interior of surface waves can be described accurately using potential flow theory, apart from boundary layers near the free surface and bottom (where vorticity is important, due to viscous effects, see Stokes boundary layer). Then, the flow velocity u can be described as the gradient of a velocity potential :
Consequently, assuming incompressible flow, the velocity field u is divergence-free and the velocity potential satisfies Laplace's equation
in the fluid interior.
The fluid region is described using three-dimensional Cartesian coordinates (x,y,z), with x and y the horizontal coordinates, and z the vertical coordinate – with the positive z-direction opposing the direction of the gravitational acceleration. Time is denoted with t. The free surface is located at , and the bottom of the fluid region is at .
The free-surface boundary conditions for surface gravity waves – using a potential flow description – consist of a kinematic and a dynamic boundary condition.
The kinematic boundary condition ensures that the normal component of the fluid's flow velocity, in matrix notation, at the free surface equals the normal velocity component of the free-surface motion :
The dynamic boundary condition states that, without surface tension effects, the atmospheric pressure just above the free surface equals the fluid pressure just below the surface. For an unsteady potential flow this means that the Bernoulli equation is to be applied at the free surface. In case of a constant atmospheric pressure, the dynamic boundary condition becomes:
where the constant atmospheric pressure has been taken equal to zero, without loss of generality.
Both boundary conditions contain the potential as well as the surface elevation η. A (dynamic) boundary condition in terms of only the potential can be constructed by taking the material derivative of the dynamic boundary condition, and using the kinematic boundary condition:
At the bottom of the fluid layer, impermeability requires the normal component of the flow velocity to vanish:
where h(x,y) is the depth of the bed below the datum and n is the coordinate component in the direction normal to the bed.
For permanent waves above a horizontal bed, the mean depth h is a constant and the boundary condition at the bed becomes: | 1 | Applied and Interdisciplinary Chemistry |
One application in which pressure exchangers are widely used is reverse osmosis (RO). In an RO system, pressure exchangers are used as energy recovery devices (ERDs). As illustrated, high-pressure concentrate from the membranes [C] is directed [3] to the ERD [D]. The ERD uses this high-pressure concentrate stream to pressurize the low-pressure seawater stream (stream [1] becomes stream [4]), which it then merges (with the aid of a circulation pump [B]) into the highest-pressure seawater stream created by the high-pressure pump [A]. This combined stream feeds the membranes [C]. The concentrate leaves the ERD at low pressure [5], expelled by the incoming feedwater flow [1].
Pressure exchangers save energy in these systems by reducing the load on the high pressure pump. In a seawater RO system operating at a 40% membrane water recovery rate, the ERD supplies 60% of the membrane feed flow. Energy is consumed by the circulation pump, however, because this pump merely circulates and does not pressurize water, its energy consumption is almost negligible: less than 3% of the energy consumed by the high pressure pump. Therefore, nearly 60% of the membrane feed flow is pressurized with almost no energy input. | 1 | Applied and Interdisciplinary Chemistry |
At neutral pH, thiocarboxylic acids are fully ionized. Thiocarboxylic acids are about 100 times more acidic than the analogous carboxylic acids. For PhC(O)SH pK = 2.48 vs 4.20 for PhC(O)OH. For thioacetic acid the pK is near 3.4 vs 4.72 for acetic acid.
The conjugate base of thioacetic acid, thioacetate is reagents for installing thiol groups via the displacement of alkyl halides to give the thioester, which in turn are susceptible to hydrolysis:
Thiocarboxylic acids react with various nitrogen functional groups, such as organic azide, nitro, and isocyanate compounds, to give amides under mild conditions. This method avoids needing a highly nucleophilic aniline or other amine to initiate an amide-forming acyl substitution, but requires synthesis and handling of the unstable thiocarboxylic acid. Unlike the Schmidt reaction or other nucleophilic-attack pathways, the reaction with an aryl or alkyl azide begins with a [3+2] cycloaddition; the resulting heterocycle expels N and the sulfur atom to give the monosubstituted amide. | 0 | Theoretical and Fundamental Chemistry |
In the United States, the Environmental Protection Agency has published pollution control regulations for smelters.
* Air pollution standards under the Clean Air Act
* Water pollution standards (effluent guidelines) under the Clean Water Act.
The RMI Conformant Smelter Program
As conflict mineral use grows, numerous initiatives have been launched to counteract the problem. They encourage responsible mineral sourcing practices in regions under circumstances of conflict, human rights abuse, or labour exploitation.
The Responsible Mineral Initiative, RMI, has developed a set of ideals and guidelines for smelter, including the Conformant Smelter Program. The program is a third-party audit and certification program that assesses the performance of smelters in the responsible sourcing of minerals. This program adheres to the Organization for Economic Co-operation and Development, OECD, guidelines. Published in the OECD Due Diligence Guidance for Responsible Supply Chains of Minerals from Conflict-Affected and High-Risk Areas. The OECD is a body focused on policies for bettering global practices.
The focus of the program is evaluating smelters on:
*Sourcing practices: Demonstrating sourced minerals do not contribute to active conflict, human rights issues, or environmental damage
*Due Diligence: Establishing a due diligence process to mitigate risks in the supply chain
*Transparency: Information being transparent about their sourcing
*Environmental and social performance: Minimizing the environmental impact and respecting workers' rights
Smelters that meet the RMI standards gain recognition on the RMI Conformant Smelter & Refiner Lists.
This is not the only program regulating the smelting industry, additional auditing programs include:
*The London Bullion Market Association, LBMA, focuses on gold, silver, platinum, and palladium. With successful smelters gaining recognition on the Good Suppliers List.
*Responsible Jewellery Council, RJC, promotes responsible practices in the jewellery supply chain. Successful smelters gaining recognition on the RJC members registry.
Similarly, to the RMI Conformant Smelter Program these entities comply with OECD guidelines and promote ethical and environmental supply chain management. However, the named organizations have varying additional guidelines therefore the only cross recognized audits with the RMI are:
*LBMA Responsible Gold Guidance
*RMI Responsible Minerals Assurance Process Gold Standard
*RJC Chain-of-Custody (CoC) Standard (provision 1 only)
*RJC Code of Practices (COP) Standard (provision 7 only) | 1 | Applied and Interdisciplinary Chemistry |
It is well known that optical interference often is a major problem in laser-based gas spectroscopy. In conventional laser-based gas spectrometers, the optical interference originates from e.g. etalon-type interference effects in (or between) optical components and multi-pass gas cells. Throughout the years, great efforts have been devoted to handle this problem. Proper optical design is important to minimize interference from the beginning (e.g. by tilting optical components, avoiding transmissive optics and using anti-reflection coating), but interference patterns can not be completely avoided and are often difficult to separate from gas absorption. Since gas spectroscopy often involves measurement of small absorption fractions (down to 10), appropriate handling of interference is crucial. Utilised countermeasures include customized optical design, tailored laser modulation, mechanical dithering, signal post-processing, sample modulation, and baseline recording and interference subtraction.
In the case of GASMAS, optical interference is particularly cumbersome. This is related to the severe speckle-type interference that originates from the interaction between laser light and highly scattering solid materials. Since this highly non-uniform interference is generated in same place as the utility signal, it cannot be removed by design. The optical properties of the porous material under study determines the interference pattern, and the level of interference is not seldom much stronger than actual gas absorption signals. Random mechanical dithering (e.g. laser beam dithering and/or sample rotation ) has been found effective in GASMAS. However, this approach converts stable interference into a random noise that must be averaged away, thus requiring longer acquisition times. Baseline recording and interference subtraction may be applicable in some GASMAS applications, as may other of the methods described above. | 0 | Theoretical and Fundamental Chemistry |
A prehormone is a biochemical substance secreted by glandular tissue and has minimal or no significant biological activity, but it is converted in peripheral tissues into an active hormone. Calcifediol is an example of a prehormone which is produced by hydroxylation of vitamin D (cholecalciferol) in the liver. Another example is adrenal androgens like dehydroepiandrosterone and androstenedione, which can be converted into testosterone and dihydrotestosterone. | 1 | Applied and Interdisciplinary Chemistry |
It is easiest to describe the flux of metabolites through a pathway by considering the reaction steps individually. The flux of the metabolites through each reaction (J) is the rate of the forward reaction (V), less that of the reverse reaction (V):
At equilibrium, there is no flux. Furthermore, it is observed that throughout a steady-state pathway, the flux is determined to varying degrees by all steps in the pathway. The degree of influence is measured by the flux control coefficient. | 1 | Applied and Interdisciplinary Chemistry |
Ignatius Gottfried Kaim was an Austrian chemist.
In his dissertation De metallis dubiis published in 1770 Kaim describes the reduction of manganese oxide with carbon and the formation of a brittle metal. This is the first description of manganese metal several years before the better known synthesis of Johan Gottlieb Gahn in 1774. | 1 | Applied and Interdisciplinary Chemistry |
For molecular systems in thermal equilibrium, the addition of energy. e. g. by mechanical work, can cause a change in entropy. This is known from the theories of thermodynamics and statistical mechanics. Specifically, both theories assert that the change in energy must be proportional to the entropy change times the absolute temperature. This rule is only valid so long as the energy is restricted to thermal states of molecules. If a rubber sample is stretched far enough, energy may reside in non-thermal states such as the distortion of chemical bonds and the rule doesn't apply. At low to moderate strains, theory predicts that the required stretching force is due to a change in entropy in the network chains. If this is correct, then we expect that the force necessary to stretch a sample to some value of strain should be proportional to the temperature of the sample. Measurements showing how the tensile stress in a stretched rubber sample varies with temperature are shown in Fig. 4. In these experiments, the strain of a stretched rubber sample was held fixed as the temperature was varied between 10 and 70 degrees Celsius. For each value of fixed strain, it is seen that the tensile stress varied linearly (to within experimental error). These experiments provide the most compelling evidence that entropy changes are the fundamental mechanism for rubber elasticity.
The positive linear behavior of the stress with temperature sometimes leads to the mistaken notion that rubber has a negative coefficient of thermal expansion, i.e. the length of a sample shrinks when heated. Experiments have shown conclusively that, like almost all other materials, the coefficient of thermal expansion natural rubber is positive. | 0 | Theoretical and Fundamental Chemistry |
Amines are ubiquitous in biology. The breakdown of amino acids releases amines, famously in the case of decaying fish which smell of trimethylamine. Many neurotransmitters are amines, including epinephrine, norepinephrine, dopamine, serotonin, and histamine. Protonated amino groups () are the most common positively charged moieties in proteins, specifically in the amino acid lysine. The anionic polymer DNA is typically bound to various amine-rich proteins. Additionally, the terminal charged primary ammonium on lysine forms salt bridges with carboxylate groups of other amino acids in polypeptides, which is one of the primary influences on the three-dimensional structures of proteins. | 0 | Theoretical and Fundamental Chemistry |
All 3 types of photooxygenation have been applied in the context of organic synthesis. In particular, type II photooxygenations have proven to be the most widely used (due to the low amount of energy required to generate singlet oxygen) and have been described as "one of the most powerful methods for the photochemical oxyfunctionalization of organic compounds." These reactions can proceed in all common solvents and with a broad range of sensitizers.
Many of the applications of type II photooxygenations in organic synthesis come from
Waldemar Adam's investigations into the ene-reaction of singlet oxygen with acyclic alkenes. Through the cis effect and the presence of appropriate steering groups the reaction can even provide high regioselectively and diastereoselectivity - two valuable stereochemical controls. | 0 | Theoretical and Fundamental Chemistry |
The thermodynamic entropy (at equilibrium) is a function of the state variables of the model description. It is therefore as "real" as the other variables in the model description. If the model constraints in the probability assignment are a "good" description, containing all the information needed to predict reproducible experimental results, then that includes all of the results one could predict using the formulae involving entropy from classical thermodynamics. To that extent, the MaxEnt S is as "real" as the entropy in classical thermodynamics.
Of course, in reality there is only one real state of the system. The entropy is not a direct function of that state. It is a function of the real state only through the (subjectively chosen) macroscopic model description. | 0 | Theoretical and Fundamental Chemistry |
The unit of osmotic concentration is the osmole. This is a non-SI unit of measurement that defines the number of moles of solute that contribute to the osmotic pressure of a solution. A milliosmole (mOsm) is 1/1,000 of an osmole. A microosmole (μOsm) (also spelled micro-osmole) is 1/1,000,000 of an osmole. | 0 | Theoretical and Fundamental Chemistry |
AFM-IR has been used to study the surface plasmon resonance in heavily silicon-doped indium arsenide microparticles. Gold split ring resonators have been studied for use with Surface-Enhanced Infrared Absorption Spectroscopy. In this case AFM-IR was used to measure the local field enhancement of the plasmonics structures (~30X) at 100 nm spatial resolution. | 0 | Theoretical and Fundamental Chemistry |
One of the earliest synthesis of gallium nitride was at the George Herbert Jones Laboratory in 1932.
An early synthesis of gallium nitride was by Robert Juza and Harry Hahn in 1938.
GaN with a high crystalline quality can be obtained by depositing a buffer layer at low temperatures. Such high-quality GaN led to the discovery of p-type GaN, p–n junction blue/UV-LEDs and room-temperature stimulated emission (essential for laser action). This has led to the commercialization of high-performance blue LEDs and long-lifetime violet laser diodes, and to the development of nitride-based devices such as UV detectors and high-speed field-effect transistors. | 0 | Theoretical and Fundamental Chemistry |
William Brownrigg ( – 6 January 1800) was a British doctor and scientist, who practised at Whitehaven in Cumberland. While there, Brownrigg carried out experiments that earned him the Copley Medal in 1766 for his work on carbonic acid gas. He was the first person to recognise platinum as a new element.
He was created a Fellow of the Royal Society. | 1 | Applied and Interdisciplinary Chemistry |
When applied to polymers, the term crystalline has a somewhat ambiguous usage. In some cases, the term crystalline finds identical usage to that used in conventional crystallography. For example, the structure of a crystalline protein or polynucleotide, such as a sample prepared for x-ray crystallography, may be defined in terms of a conventional unit cell composed of one or more polymer molecules with cell dimensions of hundreds of angstroms or more. A synthetic polymer may be loosely described as crystalline if it contains regions of three-dimensional ordering on atomic (rather than macromolecular) length scales, usually arising from intramolecular folding or stacking of adjacent chains. Synthetic polymers may consist of both crystalline and amorphous regions; the degree of crystallinity may be expressed in terms of a weight fraction or volume fraction of crystalline material. Few synthetic polymers are entirely crystalline. The crystallinity of polymers is characterized by their degree of crystallinity, ranging from zero for a completely non-crystalline polymer to one for a theoretical completely crystalline polymer. Polymers with microcrystalline regions are generally tougher (can be bent more without breaking) and more impact-resistant than totally amorphous polymers. Polymers with a degree of crystallinity approaching zero or one will tend to be transparent, while polymers with intermediate degrees of crystallinity will tend to be opaque due to light scattering by crystalline or glassy regions. For many polymers, crystallinity may also be associated with decreased transparency. | 0 | Theoretical and Fundamental Chemistry |
Sodium hydroxide is used in some relaxers to straighten hair. However, because of the high incidence and intensity of chemical burns, manufacturers of chemical relaxers use other alkaline chemicals in preparations available to consumers. Sodium hydroxide relaxers are still available, but they are used mostly by professionals. | 0 | Theoretical and Fundamental Chemistry |
For strong gradients the transport equation typically has to be modified with higher order terms (and higher order Transport coefficients). | 0 | Theoretical and Fundamental Chemistry |
Many proteins, including antibodies, are difficult to express in host cells due to problems with insolubility, disulfide bonds or host cell toxicity. Cell-free protein array makes many of such proteins available for use in protein microarrays. | 1 | Applied and Interdisciplinary Chemistry |
Two isozymes are encoded by the PKM gene: PKM1 and PKM2. The M-gene consists of 12 exons and 11 introns. PKM1 and PKM2 are different splicing products of the M-gene (exon 9 for PKM1 and exon 10 for PKM2) and solely differ in 23 amino acids within a 56-amino acid stretch (aa 378–434) at their carboxy terminus. | 1 | Applied and Interdisciplinary Chemistry |
* Middleton, Wilfrid & Habibi, Amin & Shankar, Sanjeev & Ludwig, Ferdinand. (2020). Characterizing Regenerative Aspects of Living Root Bridges. Sustainability. 12. 10.3390/su12083267. [https://www.mdpi.com/2071-1050/12/8/3267/html Open access article link]
* Well, Friederike & Ludwig, Ferdinand. (2020). Blue-green architecture: A case study analysis considering the synergetic effects of water and vegetation. 9. 191–202. 10.1016/j.foar.2019.11.001. [https://www.sciencedirect.com/science/article/pii/S2095263519300822 Open access article link]
* Ludwig, Ferdinand & Middleton, Wilfrid & Gallenmüller, Friederike & Rogers, Patrick & Speck, Thomas. (2019). Living bridges using aerial roots of ficus elastica – an interdisciplinary perspective. Scientific Reports. 9. 10.1038/s41598-019-48652-w. [https://www.nature.com/articles/s41598-019-48652-w Open access article link]
* Ludwig, Ferdinand & Schönle, Daniel & Vees, Ute. (2016). Baubotanik - Building Architecture with Nature. International Online Journal Biotope City. [https://www.researchgate.net/publication/320058217_Baubotanik_-_Building_Architecture_with_Nature PDF download and open access article link]
* Ludwig, Ferdinand & Mihaylov, Boyan & Schwinn, Tobias. (2013). Emergent Timber: A tool for designing the growth process of Baubotanik structures [https://www.researchgate.net/publication/320058050_Emergent_Timber_A_tool_for_designing_the_growth_process_of_Baubotanik_structures PDF download and open access article link] | 1 | Applied and Interdisciplinary Chemistry |
An apparent self-protective behaviour, known as "terminal burrowing", or "hide-and-die syndrome", occurs in the final stages of hypothermia. Those affected will enter small, enclosed spaces, such as underneath beds or behind wardrobes. It is often associated with paradoxical undressing. Researchers in Germany claim this is "obviously an autonomous process of the brain stem, which is triggered in the final state of hypothermia and produces a primitive and burrowing-like behavior of protection, as seen in hibernating mammals". This happens mostly in cases where temperature drops slowly. | 1 | Applied and Interdisciplinary Chemistry |
Fretting examples include wear of drive splines on driveshafts, wheels at the lug bolt interface, and cylinder head gaskets subject to differentials in thermal expansion coefficients.
There is currently a focus on fretting research in the aerospace industry. The dovetail blade-root connection and the spline coupling of gas turbine aero engines experience fretting.
Another example in which fretting corrosion may occur are the pitch bearings of modern wind turbines, which operate under oscillation motion to control the power and loads of the turbine.
Fretting can also occur between reciprocating elements in the human body. Especially implants, for example hip implants, are often affected by fretting effects. | 1 | Applied and Interdisciplinary Chemistry |
S-block compounds with low oxidation states can be short lived. There are various techniques available for use. However, the generation and detection of these molecules rely on frozen inert gas matrices, low pressures, high temperatures in the gas phase, or a combination of these. This can then be combined with theoretical studies to gain more information regarding the complex. Matrix isolation techniques were carried out for gaining spectroscopic insight on how the Mg(I) dimer may behave.
By heating magnesium diboride, MgB, at 700 Celsius (°C) with a pressure of 0.1 mbar, and passing HCl gas over it several products are formed, such as magnesium chloride, MgCl. The generation of •MgCl and subsequent compounds from the reaction then underwent further study. At 10 Kelvin (K), the solution was combined with an inert gas, undergoing IR and Raman spectroscopic techniques, combined with Density Functional Theory (DFT) calculations. This showed the monomeric and dimeric Mg(I) Halides, •MgCl and ClMgMgCl, a linear molecule. While these studies were useful in gaining more insight on the Mg-Mg bond characteristics, it failed to yield a stable Mg(I) dimer in ambient conditions. | 0 | Theoretical and Fundamental Chemistry |
The spectrochemical series was first proposed in 1938 based on the results of absorption spectra of cobalt complexes.
A partial spectrochemical series listing of ligands from small Δ to large Δ is given below. (For a table, see the ligand page.)
:I < NO < FOO CN < py (pyridine) < NH < en (ethylenediamine) < bipy (2,2'-bipyridine) < phen (1,10-phenanthroline) < NO (Triphenylphosphine) < CN</sup> < CO
Weak field ligands: HO, F</sup>
Strong field ligands: CO, CN, PPh
Ligands arranged on the left end of this spectrochemical series are generally regarded as weaker ligands and cannot cause forcible pairing of electrons within the 3d level, and thus form outer orbital octahedral complexes that are high spin. On the other hand, ligands lying at the right end are stronger ligands and form inner orbital octahedral complexes after forcible pairing of electrons within 3d level and hence are called low spin ligands.
However, it is known that "the spectrochemical series is essentially backwards from what it should be for a reasonable prediction based on the assumptions of crystal field theory." This deviation from crystal field theory highlights the weakness of crystal field theory's assumption of purely ionic bonds between metal and ligand.
The order of the spectrochemical series can be derived from the understanding that ligands are frequently classified by their donor or acceptor abilities. Some, like NH, are σ bond donors only, with no orbitals of appropriate symmetry for π bonding interactions. Bonding by these ligands to metals is relatively simple, using only the σ bonds to create relatively weak interactions. Another example of a σ bonding ligand would be ethylenediamine; however, ethylenediamine has a stronger effect than ammonia, generating a larger ligand field split, Δ.
Ligands that have occupied p orbitals are potentially π donors. These types of ligands tend to donate these electrons to the metal along with the σ bonding electrons, exhibiting stronger metal-ligand interactions and an effective decrease of Δ. Most halide ligands as well as OH</sup> are primary examples of π donor ligands.
When ligands have vacant π* and d orbitals of suitable energy, there is the possibility of pi backbonding, and the ligands may be π acceptors. This addition to the bonding scheme increases Δ. Ligands that do this very effectively include CN</sup>, CO, and many others. | 0 | Theoretical and Fundamental Chemistry |
In fluid dynamics, Lamb surfaces are smooth, connected orientable two-dimensional surfaces, which are simultaneously stream-surfaces and vortex surfaces, named after the physicist Horace Lamb. Lamb surfaces are orthogonal to the Lamb vector everywhere, where and are the vorticity and velocity field, respectively. The necessary and sufficient condition are
Flows with Lamb surfaces are neither irrotational nor Beltrami. But the generalized Beltrami flows has Lamb surfaces. | 1 | Applied and Interdisciplinary Chemistry |
Transition metal sulfates form a variety of hydrates, each of which crystallizes in only one form. The sulfate group often binds to the metal, especially for those salts with fewer than six aquo ligands. The heptahydrates, which are often the most common salts, crystallize as monoclinic and the less common orthorhombic forms. In the heptahydrates, one water is in the lattice and the other six are coordinated to the ferrous center. Many of the metal sulfates occur in nature, being the result of weathering of mineral sulfides. Many monohydrates are known. | 0 | Theoretical and Fundamental Chemistry |
The Krupp-Renn process is suitable for producing pre-reduced iron ore from highly siliceous and acidic ores (CaO/SiO2 basicity index of 0.1 to 0.4), which begin generating a pasty slag at 1,200 °C. Additionally, due to the slag's acidity, it becomes vitreous, facilitating separation from the iron through easy crushing. Furthermore, this process is also ideal for treating ores with high concentrations of titanium dioxide. Due to its ability to cause slag to become especially infusible and viscous, ores that contain this oxide cannot be used with blast furnaces as they must remove all their production in liquid form. For this reason, the preferred ores for this technique are those that would become uneconomical if they had to be modified with basic additives, usually those with a low iron content (between 35 and 51%), and whose gangue needs to be neutralized.
Integrated into a steelmaking complex, the Krupp-Renn process provides an alternative to sinter plants or beneficiation processes, effectively eliminating waste rock and undesired elements like zinc, lead, and tin. Integrated into a steelmaking complex, the Krupp-Renn process provides an alternative to sinter plants or beneficiation processes, effectively eliminating waste rock and undesired elements like zinc, lead, and tin. In a blast furnace, these elements undergo vaporization-condensation cycles which progressively saturates the furnace. However, with the Krupp-Renn process, the high temperature of the fumes prevents condensation within the furnace, before they are retrieved by the dust-removal system. The process recovers by-products or extracts specific metals. The Luppen is subsequently remelted in either the blast furnace or the cupola furnace, or the Martin-Siemens furnace, because it involves melting a pre-reduced, iron-rich charge.
The process has been effective in treating ores abundant in nickel(II) oxide, vanadium, and other metals. Additionally, the process is applicable in the production of ferronickel. In this instance, saprolitic ores with a high magnesium content are as infusible as highly acidic ores, distinguishing their relevance to the process.
Direct reduction methods such as this one offer the flexibility of using any solid fuel and in this case, 240 to 300 kg of hard coal is needed to process one metric ton of iron ore that contains 30 to 40% iron. Assuming a consumption of 300 kg/ton of ore at 30%, the hard coal consumption is 800 kg per ton of iron. Additionally, 300 kg of coke is consumed during the smelting of Luppen in the blast furnace. When this ore is smelted entirely in the blast furnace, total fuel consumption remains the same. However, it only uses coke, which is a much more expensive fuel than hard coal.
However, using slags with over 60% silica content, making them acidic, contradicts metal desulfurization that demands highly basic slags. Consequently, 30% of the fuel's sulfur settles in the iron, entailing expensive after-treatments to eliminate it. | 1 | Applied and Interdisciplinary Chemistry |
The Underground World Home was an exhibit at the 1964 New York Worlds Fair of a partially underground house which doubled as a bomb shelter. Designed by architect Jay Swayze, who made a specialty of underground homes, it was situated on the campus of the expo besides the Hall of Science and north of the expos heliport in Flushing Meadow Park in Queens. | 0 | Theoretical and Fundamental Chemistry |
Ziegler–Natta catalysts of the third class, non-metallocene catalysts, use a variety of complexes of various metals, ranging from scandium to lanthanoid and actinoid metals, and a large variety of ligands containing oxygen (O), nitrogen (N), phosphorus (P), and sulfur (S). The complexes are activated using MAO, as is done for metallocene catalysts.
Most Ziegler–Natta catalysts and all the alkylaluminium cocatalysts are unstable in air, and the alkylaluminium compounds are pyrophoric. The catalysts, therefore, are always prepared and handled under an inert atmosphere. | 0 | Theoretical and Fundamental Chemistry |
Lactoperoxidase-catalysed reactions yield short-lived intermediary oxidation products of SCN, providing antibacterial activity.
The major intermediary oxidation product is hypothiocyanite OSCN, which is produced in an amount of about 1 mole per mole of hydrogen peroxide. At the pH optimum of 5.3, the OSCN is in equilibrium with HOSCN. The uncharged HOSCN is considered to be the greater bactericidal of the two forms. At pH 7, it was evaluated that HOSCN represents 2% compare to OSCN 98%.
The action of OSCN against bacteria is reported to be caused by sulfhydryl (SH) oxidation.
The oxidation of -SH groups in the bacterial cytoplasmic membrane results in loss of the ability to transport glucose and also in leaking of potassium ions, amino acids and peptide.
OSCN has also been identified as an antimicrobial agent in milk, saliva, tears, and mucus.
OSCN is considered as a safe product as it is not mutagenic. | 1 | Applied and Interdisciplinary Chemistry |
A “cuboct” cubic lattice of vertex connected octahedrons, similar to the perovskite mineral structure provides a regular polyhedral unit cell that satisfies Maxwell’s rigidity criterion and has a coordination number z of eight. The dependence of the relative density on the coordination number is small relative to the dependence on strut diameter. Winding the reinforcing fibers around the connection holes optimizes their load bearing capacity, while coupling them to struts which themselves retain uniaxial fiber orientation. | 0 | Theoretical and Fundamental Chemistry |
Detailed reviews on occurrence of CoQ and dietary intake were published in 2010. Besides the endogenous synthesis within organisms, CoQ also is supplied by various foods. CoQ concentrations in various foods are:
Vegetable oils, meat and fish are quite rich in CoQ levels. Dairy products are much poorer sources of CoQ than animal tissues. Among vegetables, broccoli and cauliflower are good sources of CoQ. Most fruit and berries are poor sources of CoQ, with the exception of avocados, which have a relatively high oil and CoQ content. | 1 | Applied and Interdisciplinary Chemistry |
By raster scanning the sample, making measurements at several points across the surface, multi-megapixel images of the SAW velocity can be built up - providing rich microstructural maps. On samples with a good surface finish measurements can be made without averaging, allowing samples to be rapidly scanned. In-theory, means the acquisition rate is limited only by the repetition rate of the pump laser; modern laser repetition rates can exceed 10 kHz. As the measurements do not require a vacuum chamber or acoustic couplant there is little restriction, beyond the limit of scanning stages, to the size of sample which can be interrogated. The elastic anisotropy of most engineering materials means the acoustic response is a function of the loading direction. Hence, a unique velocity map exists for each propagation direction of the SAW direction. It is possible to combine multiple velocity maps to improve contrast between grains. | 0 | Theoretical and Fundamental Chemistry |
Periodic table --
Pharmacology --
Physical chemistry --
Plastic --
Polymer --
Process control --
Process design --
Process modeling --
Process safety -- | 1 | Applied and Interdisciplinary Chemistry |
MDMA or "ecstasy" originally gained popularity in the 1980s among college students. According to a survey conducted, 10% of college students at a big US institution reported using MDMA, with alcohol and marijuana being the most often used substances. MDMA users report increased enjoyment in physical contact and proximity rather than a sexual experience. MDMA has been shown to impair sexual performance, including erectile dysfunction and delayed orgasm, as well as to suppress sex desire. | 1 | Applied and Interdisciplinary Chemistry |
The nature of bonding in the 2-norbornyl cation was the center of a vigorous, well-known debate in the chemistry community through the middle of the twentieth century. While the majority of chemists believed that a three-center two-electron bond best depicted its ground state electronic structure, others argued that all data concerning the 2-norbornyl cation could be explained by depicting it as a rapidly equilibrating pair of cations.
At the height of the debate, all chemists agreed that the delocalized picture of electron bonding could be applied to the 2-norbornyl cation. But this did not answer the fundamental question on which the debate hinged. Researchers continued to search for novel ways to determine whether the three-centered delocalized picture described a low-energy transition state (saddle point on the multidimensional potential energy surface) or a potential energy minimum in its own right. Proponents of the "classical" picture believed that the system was best described by a double-well potential with a very low barrier, while those in the "non-classical" camp envisioned the delocalized electronic state to describe a single potential energy well. | 0 | Theoretical and Fundamental Chemistry |
Gallium arsenide is an important semiconductor material for high-cost, high-efficiency solar cells and is used for single-crystalline thin-film solar cells and for multi-junction solar cells.
The first known operational use of GaAs solar cells in space was for the Venera 3 mission, launched in 1965. The GaAs solar cells, manufactured by Kvant, were chosen because of their higher performance in high temperature environments. GaAs cells were then used for the Lunokhod rovers for the same reason.
In 1970, the GaAs heterostructure solar cells were developed by the team led by Zhores Alferov in the USSR, achieving much higher efficiencies. In the early 1980s, the efficiency of the best GaAs solar cells surpassed that of conventional, crystalline silicon-based solar cells. In the 1990s, GaAs solar cells took over from silicon as the cell type most commonly used for photovoltaic arrays for satellite applications. Later, dual- and triple-junction solar cells based on GaAs with germanium and indium gallium phosphide layers were developed as the basis of a triple-junction solar cell, which held a record efficiency of over 32% and can operate also with light as concentrated as 2,000 suns. This kind of solar cell powered the Mars Exploration Rovers Spirit and Opportunity, which explored Mars' surface. Also many solar cars utilize GaAs in solar arrays, as did the Hubble Telescope.
GaAs-based devices hold the world record for the highest-efficiency single-junction solar cell at 29.1% (as of 2019). This high efficiency is attributed to the extreme high quality GaAs epitaxial growth, surface passivation by the AlGaAs, and the promotion of photon recycling by the thin film design. GaAs-based photovoltaics are also responsible for the highest efficiency (as of 2022) of conversion of light to electricity, as researchers from the Fraunhofer Institute for Solar Energy Systems achieved a 68.9% efficiency when exposing a GaAs thin film photovoltaic cell to monochromatic laser light with a wavelength of 858 nanometers.
Today, multi-junction GaAs cells have the highest efficiencies of existing photovoltaic cells and trajectories show that this is likely to continue to be the case for the foreseeable future. In 2022, Rocket Lab unveiled a solar cell with 33.3% efficiency based on inverted metamorphic multi-junction (IMM) technology. In IMM, the lattice-matched (same lattice parameters) materials are grown first, followed by mismatched materials. The top cell, GaInP, is grown first and lattice matched to the GaAs substrate, followed by a layer of either GaAs or GaInAs with a minimal mismatch, and the last layer has the greatest lattice mismatch. After growth, the cell is mounted to a secondary handle and the GaAs substrate is removed. A main advantage of the IMM process is that the inverted growth according to lattice mismatch allows a path to higher cell efficiency.
Complex designs of AlGaAs-GaAs devices using quantum wells can be sensitive to infrared radiation (QWIP).
GaAs diodes can be used for the detection of X-rays. | 0 | Theoretical and Fundamental Chemistry |
Fluid-attenuated inversion recovery (FLAIR) is an inversion-recovery pulse sequence used
to nullify the signal from fluids. For example, it can be used in brain imaging to suppress cerebrospinal fluid so as to bring out periventricular hyperintense lesions, such as multiple sclerosis plaques. By carefully choosing the inversion time TI (the time between the inversion and excitation pulses), the signal from any particular tissue can be suppressed. | 0 | Theoretical and Fundamental Chemistry |
When used as a food additive, ractopamine added to feed can be distributed by the blood to the muscle tissues, where it serves as a full agonist to murine (mouse or rat) TAAR1, a receptor protein (not necessarily in humans). It is also an agonist to beta-adrenergic receptors. A cascade of events will then be initiated to increase protein synthesis, which results in increased muscle fiber size. Ractopamine is known to increase the rate of weight gain, improve feed efficiency, and increase carcass leanness in finishing swine. Its use in finishing swine yields about of additional lean pork per animal, and improves feed efficiency by 10%. In cattle on 28 January 2004 Elanco Animal Health
made Optaflexx commercially available in the US. Optaflexx is a "medicated feed additive that is labeled only for use in steers or market heifers (not breeding heifers or bulls) during the last 28–42 days on feed." | 0 | Theoretical and Fundamental Chemistry |
The release of a neurotransmitter is triggered by the arrival of a nerve impulse (or action potential) and occurs through an unusually rapid process of cellular secretion (exocytosis). Within the presynaptic nerve terminal, vesicles containing neurotransmitter are localized near the synaptic membrane. The arriving action potential produces an influx of calcium ions through voltage-dependent, calcium-selective ion channels at the down stroke of the action potential (tail current). Calcium ions then bind to synaptotagmin proteins found within the membranes of the synaptic vesicles, allowing the vesicles to fuse with the presynaptic membrane. The fusion of a vesicle is a stochastic process, leading to frequent failure of synaptic transmission at the very small synapses that are typical for the central nervous system. Large chemical synapses (e.g. the neuromuscular junction), on the other hand, have a synaptic release probability, in effect, of 1. Vesicle fusion is driven by the action of a set of proteins in the presynaptic terminal known as SNAREs. As a whole, the protein complex or structure that mediates the docking and fusion of presynaptic vesicles is called the active zone. The membrane added by the fusion process is later retrieved by endocytosis and recycled for the formation of fresh neurotransmitter-filled vesicles.
An exception to the general trend of neurotransmitter release by vesicular fusion is found in the type II receptor cells of mammalian taste buds. Here the neurotransmitter ATP is released directly from the cytoplasm into the synaptic cleft via voltage gated channels. | 1 | Applied and Interdisciplinary Chemistry |
Low molecular weight simple amines, such as ethylamine, are only weakly toxic with between 100 and 1000 mg/kg. They are skin irritants, especially as some are easily absorbed through the skin. Amines are a broad class of compounds, and more complex members of the class can be extremely bioactive, for example strychnine. | 0 | Theoretical and Fundamental Chemistry |
The neodymium found at Oklo has a different isotopic composition to that of natural neodymium: the latter contains 27% , while that of Oklo contains less than 6%. The is not produced by fission; the ore contains both fission-produced and natural neodymium. From this content, we can subtract the natural neodymium and gain access to the isotopic composition of neodymium produced by the fission of . The two isotopes and lead to the formation of and by neutron capture, and this excess must be corrected (see above) to obtain perfect agreement between this corrected isotopic composition and that deduced from fission yields. | 0 | Theoretical and Fundamental Chemistry |
The Landsupport consortium consists of the following partners:
*University of Naples, Italy
*ARIESPACE, Italy
*Barcelona Supercomputing Center, Spain
*University of Natural Resources and Life Sciences, Vienna, Austria
*Consiglio Nazionale delle Ricerche, Italy
*Crops for the Future, Malaysia
*ICARDA, Tunisia
*Institute of Advanced Studies, Hungary
*Institute for Environmental Protection and Research, Italy
*Rasdaman GmbH, Germany
*Joint Research Center, European Commission
*Regione Campania, Italy
*University of Milan, Italy
*Zala County, Hungary
*CMAST / Modis, Belgium
*Acteon, France
*Federal Environment Agency, Austria
*Slovenian Forestry Institute, Slovenia | 1 | Applied and Interdisciplinary Chemistry |
Expected progeny differences (EPD) are an evaluation of an animal’s genetic worth as a parent. They are based on animal models which combine all information known about an individual and its relatives to create a genetic profile of the animal’s merits. These profiles are then compared to other individuals of the same breed. | 1 | Applied and Interdisciplinary Chemistry |
- For visible light,
- For neutrons,
- For "hard" X-rays,
while typical values for polymers range in . This makes small-angle measurements in neutrons and X-rays a bit more tedious, as very small angles are needed, and the data in those angles is often "overpowered" by the spot emerging in usual scattering experiments. The problem is mitigated by conducting longer experiments with more exposure time, which allows the required data to "intensify". One must take care though, as to not allow the prolonged exposure to high levels of radiation damage the polymers (which might be a real problem when considering biological polymer samples – proteins, for example).
On the other hand, to resolve smaller polymers and structurals subtleties, one cannot always resort to using the long-wavelength rays, as the diffraction limit comes into play. | 0 | Theoretical and Fundamental Chemistry |
:* A graft polymer molecule is a branched polymer molecule in which one or more of the side chains are different, structurally or configurationally, from the main chain.
:* A star-shaped polymer molecule is a branched polymer molecule in which a single branch point gives rise to multiple linear chains or arms. If the arms are identical the star polymer molecule is said to be regular. If adjacent arms are composed of different repeating subunits, the star polymer molecule is said to be variegated.
:* A comb polymer molecule consists of a main chain with two or more three-way branch points and linear side chains. If the arms are identical the comb polymer molecule is said to be regular.
:* A brush polymer molecule consists of a main chain with linear, unbranched side chains and where one or more of the branch points has four-way functionality or larger.
:* A polymer network is a network in which all polymer chains are interconnected to form a single macroscopic entity by many crosslinks. See for example thermosets or interpenetrating polymer networks.
:* A dendrimer is a repetitively branched compound. | 0 | Theoretical and Fundamental Chemistry |
Radioactive primordial nuclides found in the Earth are residues from ancient supernova explosions that occurred before the formation of the Solar System. They are the fraction of radionuclides that survived from that time, through the formation of the primordial solar nebula, through planet accretion, and up to the present time. The naturally occurring short-lived radiogenic radionuclides found in todays rocks, are the daughters of those radioactive primordial nuclides. Another minor source of naturally occurring radioactive nuclides are cosmogenic nuclides, that are formed by cosmic ray bombardment of material in the Earths atmosphere or crust. The decay of the radionuclides in rocks of the Earths mantle and crust contribute significantly to Earths internal heat budget. | 0 | Theoretical and Fundamental Chemistry |
Nitrogen-15 nuclear magnetic resonance spectroscopy (nitrogen-15 NMR spectroscopy, or just simply N NMR) is a version of nuclear magnetic resonance spectroscopy that examines samples containing the N nucleus. N NMR differs in several ways from the more common C and H NMR. To circumvent the difficulties associated with measurement of the quadrupolar, spin-1 N nuclide, N NMR is employed in samples for detection since it has a ground-state spin of ½. SinceN is 99.64% abundant, incorporation of N into samples often requires novel synthetic techniques.
Nitrogen-15 is frequently used in nuclear magnetic resonance spectroscopy (NMR), because unlike the more abundant nitrogen-14, that has an integer nuclear spin and thus a quadrupole moment, N has a fractional nuclear spin of one-half, which offers advantages for NMR like narrower line width. Proteins can be isotopically labeled by cultivating them in a medium containing nitrogen-15 as the only source of nitrogen. In addition, nitrogen-15 is used to label proteins in quantitative proteomics (e.g. SILAC). | 0 | Theoretical and Fundamental Chemistry |
Certain perfusates have been shown to have toxic effects on kidneys as a result of the inadvertent inclusion of particular chemicals in their formulation. Collins showed that the procaine included in the formulation of his flush fluids could be toxic, and Pegg has commented how toxic materials, such as PVC plasticizers, may be washed out of perfusion circuit tubing. Dvorak showed that the methyl-prednisolone addition to the perfusate that was thought to be essential by Woods might in some circumstances be harmful. He showed that with over g of methyl-prednisolone in 650 mL of perfusate (compared with 250 mg in 1 litre used by Woods) irreversible haemodynamic and structural changes were produced in the kidney after 20 hours of perfusion. There was necrosis of capillary loops, occlusion of Bowman's spaces, basement membrane thickening and endothelial cell damage. | 1 | Applied and Interdisciplinary Chemistry |
Serum creatinine (a blood measurement) is an important indicator of kidney health, because it is an easily measured byproduct of muscle metabolism that is excreted unchanged by the kidneys. Creatinine itself is produced via a biological system involving creatine, phosphocreatine (also known as creatine phosphate), and adenosine triphosphate (ATP, the body's immediate energy supply).
Creatine is synthesized primarily in the liver from the methylation of glycocyamine (guanidino acetate, synthesized in the kidney from the amino acids arginine and glycine) by S-adenosyl methionine. It is then transported through blood to the other organs, muscle, and brain, where, through phosphorylation, it becomes the high-energy compound phosphocreatine. Creatine conversion to phosphocreatine is catalyzed by creatine kinase; spontaneous formation of creatinine occurs during the reaction.
Creatinine is removed from the blood chiefly by the kidneys, primarily by glomerular filtration, but also by proximal tubular secretion. Little or no tubular reabsorption of creatinine occurs. If the filtration in the kidney is deficient, blood creatinine concentrations rise. Therefore, creatinine concentrations in blood and urine may be used to calculate the creatinine clearance (CrCl), which correlates approximately with the glomerular filtration rate (GFR). Blood creatinine concentrations may also be used alone to calculate the estimated GFR (eGFR).
The GFR is clinically important as a measurement of kidney function. In cases of severe kidney dysfunction, though, the CrCl rate will overestimate the GFR because hypersecretion of creatinine by the proximal tubules will account for a larger fraction of the total creatinine cleared. Ketoacids, cimetidine, and trimethoprim reduce creatinine tubular secretion and, therefore, increase the accuracy of the GFR estimate, in particular in severe kidney dysfunction. (In the absence of secretion, creatinine behaves like inulin).
An alternative estimation of kidney function can be made when interpreting the blood plasma concentration of creatinine along with that of urea. BUN-to-creatinine ratio (the ratio of blood urea nitrogen to creatinine) can indicate other problems besides those intrinsic to the kidney; for example, a urea concentration raised out of proportion to the creatinine may indicate a prerenal problem such as volume depletion.
Counterintuitively, supporting the observation of higher creatinine production in women compared to men, and putting into question the algorithms for GFR that do not distinguish for sex accordingly, women have higher muscle protein synthesis and higher muscle protein turnover across the life span. As HDL supports muscle anabolism, higher muscle protein turnover links increased creatine to the generally higher serum HDL in women as compared to serum HDL in men and the HDL associated benefits like reduced incidence of cardiovascular complications and reduced COVID-19 severity. | 1 | Applied and Interdisciplinary Chemistry |
The Class IIB HDACs include HDAC6 and HDAC10. These two HDACs are most closely related to each other in overall sequence. However, HDAC6's catalytic domain is most similar to HDAC9. A unique feature of HDAC6 is that it contains two catalytic domains in tandem of one another. Another unique feature of HDAC6 is the HDAC6-, SP3, and Brap2-related zinc finger motif (HUB) domain in the C-terminus which shows some functions related to ubiquitination, meaning this HDAC is prone to degradation. HDAC10 has two catalytic domains as well. One active domain is located in the N-terminus and a putative catalytic domain is located in the C-terminus along with an NES domain. Two putative Rb-binding domains have also been found on HDAC10 which shows it may have roles in the regulation of the cell cycle. Two variants of HDAC10 have been found, both having slight differences in length. HDAC6 is the only HDAC to be shown to act on tubulin, acting as a tubulin deacetylase which helps in the regulation of microtubule-dependent cell motility. It is mostly found in the cytoplasm but has been known to be found in the nucleus, complexed together with HDAC11. HDAC10 has been seen to act on HDACs 1, 2, 3 (or SMRT), 4, 5 and 7. Some evidence has been shown that it may have small interactions with HDAC6 as well. This leads researchers to believe that HDAC10 may function more as a recruiter rather than a factor for deacetylation. However, experiments conducted with HDAC10 did indeed show deacetylation activity. | 0 | Theoretical and Fundamental Chemistry |
Another rare fission process, occurring in about 1 in 10 million fissions, is Quaternary fission. It is analogous to ternary fission, save that four charged products are seen. Typically two of these are light particles, with the most common mode of Quaternary fission apparently being two large particles and two alpha particles (rather than one alpha, the most common mode of ternary fission). | 0 | Theoretical and Fundamental Chemistry |
* Beautiful Swimmers: Watermen, Crabs and the Chesapeake Bay (1976), a Pulitzer Prize-winning non-fiction book by William W. Warner about the Chesapeake Bay, blue crabs, and watermen.
* Chesapeake (1978), a novel by author James A. Michener.
*Chesapeake Requiem: A Year with the Watermen of Vanishing Tangier Island (2018), by Earl Swift, a New York Times bestselling nonfiction book about the crabbing community of Chesapeake Bay.
* Diceys Song (1983) and the rest of Cynthia Voigts Tillerman series are set in Crisfield on the Chesapeake Bay.* John Barth wrote two novels featuring Chesapeake Bay
* Jacob Have I Loved (1980) by Katherine Paterson, winner of the 1981 Newbery Medal. This is a novel about the relationship between two sisters in a waterman family who grow up on an island in the Bay.
* Patriot Games (1987), in which protagonist Jack Ryan lives on the fictional Peregrine Cliffs overlooking the Chesapeake Bay, and Without Remorse (1993), in which protagonist John Kelly (later known as John Clark when he goes to work for the CIA), lives on a boat and an island in the Bay, both by Tom Clancy.
* Red Kayak (2004) by Priscilla Cummings portrays class conflict between waterman people and wealthy newcomers.
*Sabbatical: A Romance (1982) centered on a yacht race through the Bay, and The Tidewater Tales (1987) detailed a married couple telling stories to each other as they cruise the Bay, both novels by John Barth.
*The Oyster Wars of Chesapeake Bay (1997) by John Wennersten, on the Oyster Wars in the decades following the Civil War. | 1 | Applied and Interdisciplinary Chemistry |
The German chemist Wilhelm Körner suggested the prefixes ortho-, meta-, para- to distinguish di-substituted benzene derivatives in 1867; however, he did not use the prefixes to distinguish the relative positions of the substituents on a benzene ring. It was the German chemist Carl Gräbe who, in 1869, first used the prefixes ortho-, meta-, para- to denote specific relative locations of the substituents on a di-substituted aromatic ring (viz, naphthalene). In 1870, the German chemist Viktor Meyer first applied Gräbe's nomenclature to benzene. | 1 | Applied and Interdisciplinary Chemistry |
Adenylate-uridylate-rich elements (AU-rich elements; AREs) are found in the 3' untranslated region (UTR) of many messenger RNAs (mRNAs) that code for proto-oncogenes, nuclear transcription factors, and cytokines. AREs are one of the most common determinants of RNA stability in mammalian cells.
AREs are defined as a region with frequent adenine and uridine bases in a mRNA. They usually target the mRNA for rapid degradation.
ARE-directed mRNA degradation is influenced by many exogenous factors, including phorbol esters, calcium ionophores, cytokines, and transcription inhibitors. These observations suggest that AREs play a critical role in the regulation of gene transcription during cell growth and differentiation, and the immune response.
AREs have been divided into three classes with different sequences. The best characterised adenylate uridylate (AU)-rich Elements have a core sequence of AUUUA within U-rich sequences (for example WWWU(AUUUA)UUUW where W is A or U). This lies within a 50–150 base sequence, repeats of the core AUUUA element are often required for function.
A number of different proteins (e.g. HuA, HuB, HuC, HuD, HuR) bind to these elements and stabilise the mRNA while others (AUF1, TTP, BRF1, TIA-1, TIAR, and KSRP) destabilise the mRNA, miRNAs may also bind to some of them. HuD (also called ELAVL4) binds to AREs and increases the half-life of ARE-bearing mRNAs in neurons during brain development and plasticity.
AREsite—a database for ARE containing genes—has recently been developed with the aim to provide detailed bioinformatic characterization of AU-rich elements. | 1 | Applied and Interdisciplinary Chemistry |
TEOS-10 was developed by the [https://scor-int.org/ SCOR(Scientific Committee on Oceanic Research)]/IAPSO(International Association for the Physical Sciences of the Oceans) Working Group 127 which was chaired by Trevor McDougall. It has been approved as the official description of the thermodynamic properties of seawater, humid air and ice in 2009 by the Intergovernmental Oceanographic Commission (IOC) and in 2011 by the International Union of Geodesy and Geophysics (IUGG). | 0 | Theoretical and Fundamental Chemistry |
Before lead compounds can be discovered, a suitable target for rational drug design must be selected on the basis of biological plausibility or identified through screening potential lead compounds against multiple targets. Drug libraries are often tested by high-throughput screenings (active compounds are designated as "hits") which can screen compounds for their ability to inhibit (antagonist) or stimulate (agonist) a receptor of interest as well as determine their selectivity for them. | 1 | Applied and Interdisciplinary Chemistry |
Source:
The lipid tail is essential for enabling lipid membrane insertion and retention but also for giving the construct amphiphilic characteristics that enable hydrophilic surface coating (due to formation of bilipid layers). Different membrane lipids that can be used to create FSLs have different membrane physiochemical characteristics and thus can affect biological function of the FSL. Lipids in FSL Kode constructs include:
* Diacyl/diakyl e.g. DOPE
* Sterols e.g. cholesterol
* Ceramides | 1 | Applied and Interdisciplinary Chemistry |
There are many possible thermodynamically stable fuel-oxidizer combinations. Some of them are:
* Aluminium-molybdenum(VI) oxide
* Aluminium-copper(II) oxide
* Aluminium-iron(II,III) oxide
* Antimony-potassium permanganate
* Aluminium-potassium permanganate
* Aluminium-bismuth(III) oxide
* Aluminium-tungsten(VI) oxide hydrate
* Aluminium-fluoropolymer (typically Viton)
* Titanium-boron (burns to titanium diboride, which belongs to a class of compounds called intermetallic composites).
In military research, aluminium-molybdenum oxide, aluminium-Teflon and aluminium-copper(II) oxide have received considerable attention. Other compositions tested were based on nanosized RDX and with thermoplastic elastomers. PTFE or other fluoropolymer can be used as a binder for the composition. Its reaction with the aluminium, similar to magnesium/teflon/viton thermite, adds energy to the reaction. Of the listed compositions, that with potassium permanganate has the highest pressurization rate.
The most common method of preparing nanoenergetic materials is by ultrasonification in quantities of less than 2g. Some research has been developed to increase production scales. Due to the very high electrostatic discharge (ESD) sensitivity of these materials, sub 1 gram scales are currently typical. | 0 | Theoretical and Fundamental Chemistry |
In the absence of active stabilization, the repetition rate and carrier–envelope offset frequency would be free to drift. They vary with changes in the cavity length, refractive index of laser optics, and nonlinear effects such as the Kerr effect. The repetition rate can be stabilized using a piezoelectric transducer, which moves a mirror to change the cavity length.
In Ti:sapphire lasers using prisms for dispersion control, the carrier–envelope offset frequency can be controlled by tilting the high reflector mirror at the end of the prism pair. This can be done using piezoelectric transducers.
In high repetition rate Ti:sapphire ring lasers, which often use double-chirped mirrors to control dispersion, modulation of the pump power using an acousto-optic modulator is often used to control the offset frequency. The phase slip depends strongly on the Kerr effect, and by changing the pump power one changes the peak intensity of the laser pulse and thus the size of the Kerr phase shift. This shift is far smaller than 6 rad, so an additional device for coarse adjustment is needed. A pair of wedges, one moving in or out of the intra-cavity laser beam can be used for this purpose.
The breakthrough which led to a practical frequency comb was the development of technology for stabilizing the carrier–envelope offset frequency.
An alternative to stabilizing the carrier–envelope offset frequency is to cancel it completely by use of difference frequency generation (DFG). If the difference frequency of light of opposite ends of a broadened spectrum is generated in a nonlinear crystal, the resulting frequency comb is carrier–envelope offset-free since the two spectral parts contributing to the DFG share the same carrier–envelope offset frequency (CEO frequency). This was first proposed in 1999 and demonstrated in 2011 using an erbium fiber frequency comb at the telecom wavelength. This simple approach has the advantage that no electronic feedback loop is needed as in conventional stabilization techniques. It promises to be more robust and stable against environmental perturbations. | 0 | Theoretical and Fundamental Chemistry |
The English word lichen derives from the Greek ("tree moss, lichen, lichen-like eruption on skin") via Latin . The Greek noun, which literally means "licker", derives from the verb , "to lick". In American English, "lichen" is pronounced the same as the verb "liken" (). In British English, both this pronunciation and one rhyming with "kitchen" () are used. | 1 | Applied and Interdisciplinary Chemistry |
Ancient slag is difficult to date. It has no organic material with which to perform radiocarbon dating. There are no cultural artifacts like pottery shards in the slag with which to date it. Direct physical dating of slag through thermoluminescence dating could be a good method to solve this problem. Thermoluminescence dating is possible if the slag contains crystal elements such as quartz or feldspar. However, the complex composition of slag can make this technique difficult unless the crystal elements can be isolated. | 1 | Applied and Interdisciplinary Chemistry |
While Aristotelian philosophy eclipsed the importance of the atomists in late Roman and medieval Europe, their work was still preserved and exposited through commentaries on the works of Aristotle. In the 2nd century, Galen (AD 129–216) presented extensive discussions of the Greek atomists, especially Epicurus, in his Aristotle commentaries. | 1 | Applied and Interdisciplinary Chemistry |
Cis–trans isomerism, also known as geometric isomerism, describes certain arrangements of atoms within molecules. The prefixes "cis" and "trans" are from Latin: "this side of" and "the other side of", respectively. In the context of chemistry, cis indicates that the functional groups (substituents) are on the same side of some plane, while trans conveys that they are on opposing (transverse) sides. Cis–trans isomers are stereoisomers, that is, pairs of molecules which have the same formula but whose functional groups are in different orientations in three-dimensional space. Cis and trans isomers occur both in organic molecules and in inorganic coordination complexes. Cis and trans descriptors are not used for cases of conformational isomerism where the two geometric forms easily interconvert, such as most open-chain single-bonded structures; instead, the terms "syn" and "anti" are used.
According to IUPAC, "geometric isomerism" is an obsolete synonym of "cis–trans isomerism".
Cis–trans or geometric isomerism is classified as one type of configurational isomerism. | 0 | Theoretical and Fundamental Chemistry |
This is an assembly of three microchannel plates with channels aligned in a Z shape. Single MCPs can have gain up to 10,000 (40dB) but this system can provide gain more than 10 million (70dB). | 0 | Theoretical and Fundamental Chemistry |
Under certain conditions, protons can re-enter the mitochondrial matrix without contributing to ATP synthesis. This process is known as proton leak or mitochondrial uncoupling and is due to the facilitated diffusion of protons into the matrix. The process results in the unharnessed potential energy of the proton electrochemical gradient being released as heat. The process is mediated by a proton channel called thermogenin, or UCP1. Thermogenin is primarily found in brown adipose tissue, or brown fat, and is responsible for non-shivering thermogenesis. Brown adipose tissue is found in mammals, and is at its highest levels in early life and in hibernating animals. In humans, brown adipose tissue is present at birth and decreases with age. | 1 | Applied and Interdisciplinary Chemistry |
cAMP is a second messenger, used for intracellular signal transduction, such as transferring into cells the effects of hormones like glucagon and adrenaline, which cannot pass through the plasma membrane. It is also involved in the activation of protein kinases. In addition, cAMP binds to and regulates the function of ion channels such as the HCN channels and a few other cyclic nucleotide-binding proteins such as Epac1 and RAPGEF2. | 1 | Applied and Interdisciplinary Chemistry |
It is the recombinant form of factor VIII, a blood-clotting protein that is administered to patients with the bleeding disorder hemophilia, who are unable to produce factor VIII in quantities sufficient to support normal blood coagulation. Before the development of recombinant factor VIII, the protein was obtained by processing large quantities of human blood from multiple donors, which carried a very high risk of transmission of blood borne infectious diseases, for example HIV and hepatitis B. | 1 | Applied and Interdisciplinary Chemistry |
This section will review the drug development from one generation to the next with emphasis on the structural differences between the generations. The generation classification system relies on dividing the cephalosporins by their chemical properties and their relative activity against gram-negative versus gram-positive bacteria.
From the first generation cephalosporins to the third generation there is a development from being more effective against gram-positive bacteria to being more effective against gram-negative bacteria and less effective against gram-positive bacteria respectively. However the activity returns to a balanced effectiveness against gram-negative and gram-positive bacteria in the fourth generation. | 1 | Applied and Interdisciplinary Chemistry |
The vertebrate mitochondrial code (translation table 2) is the genetic code found in the mitochondria of all vertebrata. | 1 | Applied and Interdisciplinary Chemistry |
Antinuclear antibodies (ANAs, also known as antinuclear factor or ANF) are autoantibodies that bind to contents of the cell nucleus. In normal individuals, the immune system produces antibodies to foreign proteins (antigens) but not to human proteins (autoantigens). In some cases, antibodies to human antigens are produced.
There are many subtypes of ANAs such as anti-Ro antibodies, anti-La antibodies, anti-Sm antibodies, anti-nRNP antibodies, anti-Scl-70 antibodies, anti-dsDNA antibodies, anti-histone antibodies, antibodies to nuclear pore complexes, anti-centromere antibodies and anti-sp100 antibodies. Each of these antibody subtypes binds to different proteins or protein complexes within the nucleus. They are found in many disorders including autoimmunity, cancer and infection, with different prevalences of antibodies depending on the condition. This allows the use of ANAs in the diagnosis of some autoimmune disorders, including systemic lupus erythematosus, Sjögren syndrome, scleroderma, mixed connective tissue disease, polymyositis, dermatomyositis, autoimmune hepatitis and drug-induced lupus.
The ANA test detects the autoantibodies present in an individual's blood serum. The common tests used for detecting and quantifying ANAs are indirect immunofluorescence and enzyme-linked immunosorbent assay (ELISA). In immunofluorescence, the level of autoantibodies is reported as a titre. This is the highest dilution of the serum at which autoantibodies are still detectable. Positive autoantibody titres at a dilution equal to or greater than 1:160 are usually considered as clinically significant. Positive titres of less than 1:160 are present in up to 20% of the healthy population, especially the elderly. Although positive titres of 1:160 or higher are strongly associated with autoimmune disorders, they are also found in 5% of healthy individuals. Autoantibody screening is useful in the diagnosis of autoimmune disorders and monitoring levels helps to predict the progression of disease. A positive ANA test is seldom useful if other clinical or laboratory data supporting a diagnosis are not present. | 1 | Applied and Interdisciplinary Chemistry |
If the mass fraction of the dispersed phase is small, then one-way coupling between the phases is a reasonable assumption; that is, the dynamics of the particle phase are affected by the carrier phase, but the reverse is not the case. However, if the mass fraction of the dispersed phase is large, the interaction of the dynamics between the two phases must be considered - this is two-way coupling.
A problem with the Lagrangian treatment of the dispersed phase is that once the number of particles becomes large, it may require a prohibitive amount of computational power to track a sufficiently large sample of particles required for statistical convergence. In addition, if the particles are sufficiently light, they behave essentially like a second fluid. In this case, an Eulerian treatment of the dispersed phase is sensible. | 1 | Applied and Interdisciplinary Chemistry |
Northup joined the faculty at the University of New Mexico. At the UNM she started the Subsurface Life In Mineral Environments (SLIME) team. In particular, Northup studies the colourful ferromanganese deposits that line the walls of Lechuguilla and [https://www.nps.gov/media/photo/gallery-item.htm?id=00BDA79B-155D-451F-6737D552DE9FFADC&gid=002834EA-155D-451F-6776BADA00BE0B71 Spider Cave] in Carlsbad Caverns National Park. Her work on the Lechuguilla Cave was featured in a PBS Nova episode, "The Mysterious Life of Caves." She is also interested in the hydrogen sulphide cave (Cueva de las Sardinas) in Tabasco.
Northup was elected Fellow of the National Speleological Society in 1992, and awarded their Science Prize in 2013. | 0 | Theoretical and Fundamental Chemistry |
Usually the gamma-emitting tracer used in functional brain imaging is Tc-HMPAO (hexamethylpropylene amine oxime, exametazime). The similar Tc-EC tracer may also be used. These molecules are preferentially distributed to regions of high brain blood flow, and act to assess brain metabolism regionally, in an attempt to diagnose and differentiate the different causal pathologies of dementia. When used with the 3-D SPECT technique, they compete with brain FDG-PET scans and fMRI brain scans as techniques to map the regional metabolic rate of brain tissue. | 0 | Theoretical and Fundamental Chemistry |
Many units of measurement were historically, or are still, defined with reference to the properties of specific substances that, in many cases, occurred in nature as mixes of multiple isotopes, for example:
Since samples taken from different natural sources can have subtly different isotopic ratios, the relevant properties can differ between samples. If the definition simply refers to a substance without addressing the isotopic composition, this can lead to some level of ambiguity in the definition and variation in practical realizations of the unit by different laboratories, as was observed with the kelvin before 2007. If the definition refers only to one isotope (as that of the dalton does) or to a specific isotope ratio, e.g. Vienna Standard Mean Ocean Water, this removes a source of ambiguity and variation, but adds layers of technical difficulty (preparing samples of a desired isotopic ratio) and uncertainty (regarding how much an actual reference sample differs from the nominal ratio). The use of mononuclidic elements as reference material sidesteps these issues and notably the only substance referenced in the most recent iteration of the SI is caesium, a mononuclidic element.
Mononuclidic elements are also of scientific importance because their atomic weights can be measured to high accuracy, since there is minimal uncertainty associated with the isotopic abundances present in a given sample. Another way of stating this, is that, for these elements, the standard atomic weight and atomic mass are the same.
In practice, only 11 of the mononuclidic elements are used in standard atomic weight metrology. These are aluminium, bismuth, caesium, cobalt, gold, manganese, phosphorus, scandium, sodium, terbium, and thorium.
In nuclear magnetic resonance spectroscopy (NMR), the three most sensitive stable nuclei are hydrogen-1 (H), fluorine-19 (F) and phosphorus-31 (P). Fluorine and phosphorus are monoisotopic, with hydrogen nearly so. H NMR, F NMR and P NMR allow for identification and study of compounds containing these elements. | 0 | Theoretical and Fundamental Chemistry |
Further advances in aquasome research require additional investigation of their in vivo drug release and targeting. Applications such as delivery of dithranol for the treatment of psoriasis and oral delivery of bromelain for the treatment of inflammatory diseases such as cancer show promising results in vitro and ex vivo. However, such applications have been unexplored in vivo, limiting their clinical use. Applications using aquasomes as carriers of hemoglobin, vaccines, and insulin have been tested in vivo in small animal models such as rats, mice, and rabbits, but current literature lacks in vivo testing in more advanced animal models, preventing their use as treatments for human conditions. Aquasomes are promising drug delivery mechanisms due to their ability to stabilize and transport a variety of substrates while allowing for controlled drug release. Prior to expanding the clinical applications of aquasomes, the gap existing in current literature will need to be filled by further investigating immune clearance of aquasomes, exploring additional surface modifications such as PEGylation, and expanding in vivo drug testing. | 0 | Theoretical and Fundamental Chemistry |
Research and teaching activities related to natural products fall into a number of diverse academic areas, including organic chemistry, medicinal chemistry, pharmacognosy, ethnobotany, traditional medicine, and ethnopharmacology. Other biological areas include chemical biology, chemical ecology, chemogenomics, systems biology, molecular modeling, chemometrics, and chemoinformatics. | 1 | Applied and Interdisciplinary Chemistry |
A masking agent is a reagent used in chemical analysis which reacts with chemical species that may interfere in the analysis.
In sports a masking agent is used to hide or prevent detection of a banned substance or illegal drug like anabolic steroids or stimulants. Diuretics are the simplest form of masking agent and work by enhancing water loss via urine excretion and thus diluting the urine, which results in lower concentrations of the banned substance as more of it is being excreted from the body making it more difficult for laboratories to detect. | 0 | Theoretical and Fundamental Chemistry |
In the last step of glycolysis, phosphoenolpyruvate (PEP) is converted to pyruvate by pyruvate kinase. This reaction is strongly exergonic and irreversible; in gluconeogenesis, it takes two enzymes, pyruvate carboxylase and PEP carboxykinase, to catalyze the reverse transformation of pyruvate to PEP. | 1 | Applied and Interdisciplinary Chemistry |
The 4n+3 chain of uranium-235 is commonly called the "actinium series" or "actinium cascade". Beginning with the naturally-occurring isotope uranium-235, this decay series includes the following elements: actinium, astatine, bismuth, francium, lead, polonium, protactinium, radium, radon, thallium, and thorium. All are present, at least transiently, in any sample containing uranium-235, whether metal, compound, ore, or mineral. This series terminates with the stable isotope lead-207.
In the early Solar System this chain went back to Cm. This manifests itself today as variations in U/U ratios, since curium and uranium have noticeably different chemistries and would have separated differently.
The total energy released from uranium-235 to lead-207, including the energy lost to neutrinos, is 46.4 MeV. | 0 | Theoretical and Fundamental Chemistry |
Crystal optics is the branch of optics that describes the behaviour of light in anisotropic media, that is, media (such as crystals) in which light behaves differently depending on which direction the light is propagating. The index of refraction depends on both composition and crystal structure and can be calculated using the Gladstone–Dale relation. Crystals are often naturally anisotropic, and in some media (such as liquid crystals) it is possible to induce anisotropy by applying an external electric field. | 0 | Theoretical and Fundamental Chemistry |
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