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Candidate gene association study is commonly used in genetic study before the invention of high throughput genotyping or sequencing technologies. Candidate gene association study is to investigate limited number of pre-specified SNPs for association with diseases or clinical phenotypes or traits. So this is a hypothesis driven approach. Since only a limited number of SNPs are tested, a relatively small sample size is sufficient to detect the association. Candidate gene association approach is also commonly used to confirm findings from GWAS in independent samples. | 1 | Applied and Interdisciplinary Chemistry |
Tetrabutyltin is used as an antifouling paint for ships, for the prevention of slimes in industrial recirculating water systems, for combating freshwater snails that cause bilharzia, as a wood and textile preservative, and as a disinfectant. Tricyclohexyltin hydroxide is used as an acaricide. Triphenyltin hydroxide and triphenyltin acetate are used as fungicides. | 1 | Applied and Interdisciplinary Chemistry |
*CTSD can degrade insulin in hepatocytes
*CSTB May protect cell from leaking lysosomes
*LAMP1
*LAMP2
*M6PR | 1 | Applied and Interdisciplinary Chemistry |
As an azo dye, methyl red may be prepared by diazotization of anthranilic acid, followed by reaction with dimethylaniline: | 0 | Theoretical and Fundamental Chemistry |
Combining operando Raman, UV–Vis and ATR-IR is particularly useful for studying homogeneous catalysis in solution. Transition-metal complexes can perform catalytic oxidation reactions on organic molecules; however, much of the corresponding reaction pathways are still unclear. For example, an operando study of the oxidation of veratryl alcohol by salcomine catalyst at high pH determined that the initial oxidation of the two substrate molecules to aldehydes is followed by the reduction of molecular oxygen to water, and that the rate determining step is the detachment of the product. Understanding organometallic catalytic activity on organic molecules is incredibly valuable for the further development of material science and pharmaceuticals. | 0 | Theoretical and Fundamental Chemistry |
The diffusivity of spherical particles in a suspension is approximated by the Stokes–Einstein equation:
: where
* is the temperature
* is the particle radius
* is the Boltzmann constant
* is the hydrogel viscosity
Typical R-PEG hydrogel diffusivities for 2 nm quantum dots are on the order of 10 m/s, so suspensions of quantum dots tend to be very stable. Hydrogel viscosity can be determined by using rheological techniques. | 0 | Theoretical and Fundamental Chemistry |
In 1979, teams at Harvard and Caltech extended the basic idea of making DNA copies of mRNAs in vitro to amplifying a library of such in bacterial plasmids.
In 1982, the idea of selecting random or semi-random clones from such a cDNA library for sequencing was explored by Greg Sutcliffe and coworkers.
In 1983, Putney et al. sequenced 178 clones from a rabbit muscle cDNA library.
In 1991, Adams and co-workers coined the term EST and initiated more systematic sequencing as a project (starting with 600 brain cDNAs). | 1 | Applied and Interdisciplinary Chemistry |
Hydrometallurgy is concerned with processes involving aqueous solutions to extract metals from ores. The first step in the hydrometallurgical process is leaching, which involves dissolution of the valuable metals into the aqueous solution and or a suitable solvent. After the solution is separated from the ore solids, the extract is often subjected to various processes of purification and concentration before the valuable metal is recovered either in its metallic state or as a chemical compound. This may include precipitation, distillation, adsorption, and solvent extraction. The final recovery step may involve precipitation, cementation, or an electrometallurgical process. Sometimes, hydrometallurgical processes may be carried out directly on the ore material without any pretreatment steps. More often, the ore must be pretreated by various mineral processing steps, and sometimes by pyrometallurgical processes. | 1 | Applied and Interdisciplinary Chemistry |
All of V.G. Khlopin's further scientific activity was predetermined by this meeting. In the laboratory founded by Vladimir Ivanovich Vernadsky, a systematic study of radioactive minerals and rocks was carried out, the search for which in Russia was carried out by expeditions, also organized on his initiative. V. I. Vernadsky was the first Russian scientist who realized the importance of the discovery of radioactivity: "...For us it is not completely indifferent at all how radioactive minerals of Russia will be studied... Now, when mankind is entering a new age of radiant - atomic energy, we, and not others, should know, should find out what the soil of our native country holds in this respect".
In 1909 V. I. Vernadsky headed the research of radioactivity phenomena in Russia, under his chairmanship the Radium Commission was organized - all the works were united under the auspices of the Academy of Sciences, the Radiological Laboratory was founded, since 1914 the publication of the "Proceedings of the Radium Expedition of the Academy of Sciences" was started. In the mentioned speech V. I. Vernadsky notes the specific features of the new direction of scientific research: "This discovery has produced a huge revolution in the scientific outlook, caused the creation of a new science, different from physics and chemistry - the doctrine of radioactivity, put before life and technology practical tasks of a completely new kind...".
In 1915, V. I. Vernadsky attracted V. G. Khlopin to work in the Radiological Laboratory. V. G. Khlopin was destined to become the first, and for many years - the leading specialist in the new discipline. But research in the field of radioactivity, study of new radioactive elements already discovered in Russia at that time was still in the state of initial organizational period - there were no domestic radium preparations for laboratory experiments; however, deposits of minerals and ores - raw materials for consistent development of scientific work in this direction, systematic study of radioactive minerals - were already known. The leading experts of the profile - Professors K. A. Nenadkevich and A. E. Fersman - were invited to participate in the present work.
In the context of mastering the fundamental areas of activity, which for V.G. Khlopin became his life's work, he develops research of scientific and applied aspects, including methods of geochemistry of radioactive elements and noble gases, analytical chemistry and thermodynamics; at the same time, the scientist develops an independent direction, which gave the preconditions for the formation of a scientific school. By the early 1920s, four main lines had emerged, which in turn led to the establishment of an independent school:
1. radium technology;
2. chemistry of radioelements and applied radiochemistry;
3. geochemistry of radioelements and noble gases;
4.analytical chemistry. | 0 | Theoretical and Fundamental Chemistry |
Thermonuclear fusion is the process of atomic nuclei combining or "fusing" using high temperatures to drive them close enough together for this to become possible. Such temperatures cause the matter to become a plasma and, if confined, fusion reactions may occur due to collisions with extreme thermal kinetic energies of the particles. There are two forms of thermonuclear fusion: uncontrolled, in which the resulting energy is released in an uncontrolled manner, as it is in thermonuclear weapons ("hydrogen bombs") and in most stars; and controlled, where the fusion reactions take place in an environment allowing some or all of the energy released to be harnessed for constructive purposes.
Temperature is a measure of the average kinetic energy of particles, so by heating the material it will gain energy. After reaching sufficient temperature, given by the Lawson criterion, the energy of accidental collisions within the plasma is high enough to overcome the Coulomb barrier and the particles may fuse together.
In a deuterium–tritium fusion reaction, for example, the energy necessary to overcome the Coulomb barrier is 0.1 MeV. Converting between energy and temperature shows that the 0.1 MeV barrier would be overcome at a temperature in excess of 1.2 billion kelvin.
There are two effects that are needed to lower the actual temperature. One is the fact that temperature is the average kinetic energy, implying that some nuclei at this temperature would actually have much higher energy than 0.1 MeV, while others would be much lower. It is the nuclei in the high-energy tail of the velocity distribution that account for most of the fusion reactions. The other effect is quantum tunnelling. The nuclei do not actually have to have enough energy to overcome the Coulomb barrier completely. If they have nearly enough energy, they can tunnel through the remaining barrier. For these reasons fuel at lower temperatures will still undergo fusion events, at a lower rate.
Thermonuclear fusion is one of the methods being researched in the attempts to produce fusion power. If thermonuclear fusion becomes favorable to use, it would significantly reduce the world's carbon footprint. | 0 | Theoretical and Fundamental Chemistry |
Wellman and Noble proposed a new formulation for the Blue Bottle experiment in which vitamin C serves as a reducing agent instead of glucose; the methylene blue and oxygen are still used. Copper is added as a catalyst for the reoxidation of leucomethylene blue to methylene blue. These modifications give an experiment that generates a smaller amount of waste that is less corrosive and easier to neutralize, and therefore is an example of green chemistry modification. | 1 | Applied and Interdisciplinary Chemistry |
In electrochemistry, the electrode-electrolyte interface is generally charged. If the electrode is polarizable, then its surface charge depends on the electrode potential.
IUPAC defines the potential at the point of zero charge as the potential of an electrode (against a defined reference electrode) at which one of the charges defined is zero.
The potential of zero charge is used for determination of the absolute electrode potential in a given electrolyte.
IUPAC also defines the potential difference with respect to the potential of zero charge as:
where:
* E is the electrode potential difference with respect to the point of zero charge, E
* E is the potential of the same electrode against a defined reference electrode in volts
* E is the potential of the same electrode when the surface charge is zero, in the absence of specific adsorption other than that of the solvent, against the reference electrode as used above, in volts
The structure of electrolyte at the electrode surface can also depend on the surface charge, with a change around the pzc potential. For example, on a platinum electrode, water molecules have been reported to be weakly hydrogen-bonded with "oxygen-up" orientation on negatively charged surfaces, and strongly hydrogen-bonded with nearly flat orientation at positively charged surfaces.
At pzc, the colloidal system exhibits zero zeta potential (that is, the particles remain stationary in an electric field), minimum stability (exhibits maximum coagulation or flocculation rate), maximum solubility of the solid phase, maximum viscosity of the dispersion, and other peculiarities. | 0 | Theoretical and Fundamental Chemistry |
Stable isotope ratios of trace metals can be used to answer a variety of questions spanning diverse fields, including oceanography, geochemistry, biology, medicine, anthropology and astronomy. In addition to their modern applications, trace metal isotopic compositions can provide insight into ancient biogeochemical processes operated on Earth. These signatures arise because the processes that form and modify samples are recorded in the trace metal isotopic compositions of the samples. By analyzing and understanding trace metal isotopic compositions in biological, chemical or geological materials, one can answer questions such as the sources of nutrients for phytoplankton in the ocean, processes that drove the formation of geologic structures, the diets of modern or ancient organisms, and accretionary processes that took place in the early Solar System. Trace metal stable isotope biogeochemistry is still an emerging field, yet each trace metal isotope system has clear, powerful applications to diverse and important questions. Important heavy metal isotope systems are discussed (in order of increasing atomic mass) in the proceeding sections. | 0 | Theoretical and Fundamental Chemistry |
Lisinopril is typically used for the treatment of high blood pressure, congestive heart failure, and diabetic nephropathy and after acute myocardial infarction (heart attack). Lisinopril is part of the ACE inhibitors drug class. Lisinopril is indicated for the treatment of hypertension, adjunctive therapy for heart failure, and acute myocardial infarction. | 0 | Theoretical and Fundamental Chemistry |
Electrophoretic light scattering (also known as laser Doppler electrophoresis and phase analysis light scattering ) is based on dynamic light scattering. The frequency shift or phase shift of an incident laser beam depends on the dispersed particles mobility. With dynamic light scattering, Brownian motion causes particle motion. With electrophoretic light scattering, oscillating electric field performs this function.
The method is used for measuring electrophoretic mobility, from which zeta potential can then be calculated. Instruments for applying the method are commercially available from several manufacturers. The last set of calculations requires information on viscosity and dielectric permittivity of the dispersion medium; appropriate electrophoresis theory is also required. Sample dilution is often necessary to eliminate multiple scattering of the incident laser beam and/or particle interactions. | 0 | Theoretical and Fundamental Chemistry |
Breath analysis is a convenient and non-invasive way to detect chemicals in a bodily system such as alcohol content to determine intoxication, monitor the levels of anesthetics in the body during surgical procedures, and identify performance-enhancing substances in the system of athletes. However, conventional techniques are ineffective at low concentrations. An electrospray ionization interface assisted by an ion funnel used in a linear trap quadrupole Fourier-transform ion cyclotron resonance mass spectrometer was shown to greatly increase sensitivity with high resolution. | 0 | Theoretical and Fundamental Chemistry |
The magnitude of the Coulomb interaction F between two ions of charge q and Q a distance R apart is given by
directed along the axis between the two ions, where a positive value represents a repulsive force and vice versa.
Trapping techniques include variations on the Paul trap and Penning trap, where the former uses only electric fields while the latter also uses magnetic fields to confine the ions. Considering the simple case of two ions confined in a linear Paul trap, we have a radiofrequency oscillating field, which itself can confine a single ion in the (axial?) direction. | 0 | Theoretical and Fundamental Chemistry |
The term "library" can refer to a population of organisms, each of which carries a DNA molecule inserted into a cloning vector, or alternatively to the collection of all of the cloned vector molecules. | 1 | Applied and Interdisciplinary Chemistry |
Plants secrete a variety of chemicals to help seal off damaged areas. For example, the grape vine Vitis vinifera is able to block the xylem water-transport tubes in its stems using the chemical tylose in summertime, and gels in wintertime when the plant is dormant. Tylose helps to prevent pathogens such as wood-rotting fungi and the bacterium Xylella fastidiosa from spreading through the plant: the chemical is produced as a response both to the bacterium and to mechanical damage such as viticultural pruning. | 1 | Applied and Interdisciplinary Chemistry |
eIF3 independently binds the 40S ribosomal subunit, multiple initiation factors, and cellular and viral mRNA.
In mammals, eIF3 is the largest initiation factor, made up of 13 subunits (a-m). It has a molecular weight of ~800 kDa and controls the assembly of the 40S ribosomal subunit on mRNA that have a 5' cap or an IRES. eIF3 may use the eIF4F complex, or alternatively during internal initiation, an IRES, to position the mRNA strand near the exit site of the 40S ribosomal subunit, thus promoting the assembly of a functional pre-initiation complex.
In many human cancers, eIF3 subunits are overexpressed (subunits a, b, c, h, i, and m) and underexpressed (subunits e and f). One potential mechanism to explain this disregulation comes from the finding that eIF3 binds a specific set of cell proliferation regulator mRNA transcripts and regulates their translation. eIF3 also mediates cellular signaling through S6K1 and mTOR/Raptor to effect translational regulation. | 1 | Applied and Interdisciplinary Chemistry |
* Dedicated equipment is needed for precise continuous dosing (e.g. pumps), connections, etc.
* Start-up and shut-down procedures have to be established.
* Scale-up of micro effects such as the high area to volume ratio is not possible and economy of scale may not apply. Typically, a scale-up leads to a dedicated plant.
* Safety issues for the storage of reactive material still apply.
The drawbacks have been discussed in view of establishing small scale continuous production processes by Pashkova and Greiner. | 1 | Applied and Interdisciplinary Chemistry |
In order to ensure growth of only transformed bacteria (which carry the desired plasmids to be harvested), a marker gene is used in the destination vector for selection. Typical marker genes are for antibiotic resistance or nutrient biosynthesis. So, for example, the "marker gene" could be for resistance to the antibiotic ampicillin. If the bacteria that were supposed to pick up the desired plasmid had picked up the desired gene then they would also contain the "marker gene". Now the bacteria that picked up the plasmid would be able to grow in ampicillin whereas the bacteria that did not pick up the desired plasmid would still be vulnerable to destruction by the ampicillin. Therefore, successfully transformed bacteria would be "selected." | 1 | Applied and Interdisciplinary Chemistry |
Kyriacos Costa Nicolaou (; born July 5, 1946) is a Cypriot-American chemist known for his research in the area of natural products total synthesis. He is currently Harry C. and Olga K. Wiess Professor of Chemistry at Rice University, having previously held academic positions at The Scripps Research Institute/UC San Diego and the University of Pennsylvania. | 0 | Theoretical and Fundamental Chemistry |
As described by Smith, the original BCA assay is a two-component protocol. The two reagents are "stable indefinitely at room temperature". Modern (likely exact or highly similar) formulations are available from at least two commercial vendors. The BCA Working solution is generated by mixing Reagent A and Reagent B in a 50:1 ratio, and can be prepared either weekly (it is moderately stable), or as needed.
Reagent A
* 1% w/v BCA-Na (CAS: 979-88-4)
* 2% w/v NaCO·HO (CAS: 5968-11-6)
* 0.16% w/v Na tartrate (CAS: 868-18-8)
* 0.4% w/v NaOH (CAS: 1310-73-2)
* 0.95% w/v NaHCO (CAS: 144-55-8)
* Add 50% NaOH or solid NaHCO to adjust the pH to 11.25
A suggested but untested alternative formulation in the Smith manuscript is to leave out the NaOH (and presumably not perform the manual pH adjustment to 11.25), but instead to dissolve the other components in a preprepared buffer of 0.25 M NaCO and 0.01 M NaHCO.
Notably, Smith synthesized their own BCA via the Pfitzinger reaction of isatin and acetoin, substituting NaOH for KOH but otherwise following the synthetic method of Lesene and Henze, as the BCA available from commercial vendors of that time was too impure for their use. At least three successive recrystallizations of their synthesized BCA from 70˚C water was needed to sufficiently purify it for the assay.
Reagent B
* 4% w/v CuSO·5HO | 1 | Applied and Interdisciplinary Chemistry |
The synthesis of Malonyl-CoA consists of two half reactions. The first being the carboxylation of biotin with bicarbonate and the second being the transfer of the CO group to acetyl-CoA from carboxybiotin to allow for the formation of malonyl-CoA. Two different protein subassemblies, along with BCCP, are required for this two step reaction to be successful: biotin carboxylase (BC) and carboxyltransferase (CT). BCCP contains the biotin cofactor which is covalently bound to a lysine residue.
In fungi, mammals, and plant cytosols, all three of these components (BCCP, BC, and CT) exist on one polypeptide chain. However, most studies of this protein have been conducted on the E. coli form of the enzyme, where all three components exist as three separate complexes rather than being united on one polypeptide chain. | 1 | Applied and Interdisciplinary Chemistry |
A purely electronic device which generates a series of pulses, also generates a frequency comb. These are produced for electronic sampling oscilloscopes, but also used for frequency comparison of microwaves, because they reach up to 1 THz. Since they include 0 Hz, they do not need the tricks which make up the rest of this article. | 0 | Theoretical and Fundamental Chemistry |
Nanoparticle drug delivery systems are engineered technologies that use nanoparticles for the targeted delivery and controlled release of therapeutic agents. The modern form of a drug delivery system should minimize side-effects and reduce both dosage and dosage frequency. Recently, nanoparticles have aroused attention due to their potential application for effective drug delivery.
Nanomaterials exhibit different chemical and physical properties or biological effects compared to larger-scale counterparts that can be beneficial for drug delivery systems. Some important advantages of nanoparticles are their high surface-area-to-volume ratio, chemical and geometric tunability, and their ability to interact with biomolecules to facilitate uptake across the cell membrane. The large surface area also has a large affinity for drugs and small molecules, like ligands or antibodies, for targeting and controlled release purposes.
Nanoparticles refer to a large family of materials both organic and inorganic. Each material has uniquely tunable properties and thus can be selectively designed for specific applications. Despite the many advantages of nanoparticles, there are also many challenges, including but not exclusive to: nanotoxicity, biodistribution and accumulation, and the clearance of nanoparticles by human body.
The National Institute of Biomedical Imaging and Bioengineering has issued the following prospects for future research in nanoparticle drug delivery systems:
# crossing the blood-brain barrier (BBB) in brain diseases and disorders;
# enhancing targeted intracellular delivery to ensure the treatments reach the correct structures inside cells;
# combining diagnosis and treatment.
The development of new drug systems is time-consuming; it takes approximately seven years to complete fundamental research and development before advancing to preclinical animal studies. | 0 | Theoretical and Fundamental Chemistry |
* 2014: Connecticut Women's Hall of Fame honoree
* 2010: CURE award for neuroscience research
* 1987-1989: NIH postdoctoral fellow
* 1981-1983: Fulbright-Hays fellow | 1 | Applied and Interdisciplinary Chemistry |
The two main approaches to synthesis of N-H, N-alkyl, and N-aryloxaziridines are oxidation of imines with peracids (A) and amination of carbonyls (B).
Additionally, oxidation of chiral imines and oxidation of imines with chiral peracids may yield enantiopure oxaziridines. Some oxaziridines have the unique property of configurationally stable nitrogen atoms at room temperature due to an inversion barrier of 100 to 130 kJ/mol. Enantiopure oxaziridines where stereochemistry is entirely due to configurationally stable nitrogen are reported. | 0 | Theoretical and Fundamental Chemistry |
Extracellular matrix protein FRAS1 is a protein that in humans is encoded by the FRAS1 (Fraser syndrome 1) gene. This gene encodes an extracellular matrix protein that appears to function in the regulation of epidermal-basement membrane adhesion and organogenesis during development. | 1 | Applied and Interdisciplinary Chemistry |
DESIGN II for Windows is a rigorous process simulator for chemical and hydrocarbon processes including refining, refrigeration, petrochemical, gas processing, gas treating, pipelines, fuel cells, ammonia, methanol and hydrogen facilities. | 1 | Applied and Interdisciplinary Chemistry |
In organic chemistry, acroleinide is a functional group which is composed of a cyclic ketal of a diol with acrolein. In pharmaceutical chemistry, it is present in acrocinonide (triamcinolone acroleinide). | 0 | Theoretical and Fundamental Chemistry |
Alireza Mashaghi is a physician-scientist and biophysicist at Leiden University. He is known for his contributions to single-molecule analysis of chaperone assisted protein folding, molecular topology and medical systems biophysics and bioengineering. He is a leading advocate for interdisciplinary research and education in medicine and pharmaceutical sciences.
Mashaghi made the first observation of direct chaperone involvement during folding of a protein, using a single molecule force spectroscopy method. This work which has been published in Nature solved a long-standing puzzle in biology. In 2017, he reported a new model for chaperone DnaK function and made a discovery that, according to Ans Hekkenberg, "overturns the decades-old textbook model of action for a protein that is central for many processes in living cells". He and his co-workers found that chaperone DnaK can recognise natively folded protein parts and thereby promotes protein folding directly. Furthermore, the lab was the first to use optical tweezers to study folding of a single protein molecule in a cytosol, revealing the collective contribution of chaperones to folding. Inspired by single-molecule analysis of biopolymers, Mashaghi and his team developed a topology framework, termed as circuit topology, which enabled studying folded molecular chains, beyond what knot theory can offer. The approach allows for topological barcoding of proteins and cellular genomes for medical applications.
Mashaghi also contributed to others areas in biophysics and bioengineering including membrane biophysics, membrane based lab-on-a-chip biosensing, and organ-on-a-chip technology. In particular, the Mashaghi team was one of the first to introduce Organ Chip technology to the field of virology. His team engineered the first chip-based disease model for Ebola hemorrhagic shock syndrome, and later extended the applicability of the platform to various viral haemorrhagic syndromes. Ebola and similar viruses pathologically alter the mechanics of human cells, which is recapitulated in organ chip models. Moreover, the Mashaghi team developed optical tweezers and acoustic force spectroscopy based assays to probe such mechanical alterations at the single cell level.
Mashaghi is also active in interdisciplinary research in ophthalmology, immunopathology and medicine. His main contributions were in the areas of ocular inflammation and immunomodulation. In 2017, he and his co-workers at Harvard developed an immunotherapy strategy to improve survival of high-risk cornea grafts. Together with his co-workers, he contributed to the use of stem cell technology and omics technology in ophthalmology and medicine. Mashaghi and his co-workers were among the first to use stem cells to reprogram innate immune cells, including neutrophil and macrophages. Additionally, his lab was the first to measure human macrophage mechanics and metabolome using single-cell approaches. Finally, in their research, Mashaghi and his co-workers are linking statistical physics and medical diagnostics; this unprecedented link between physics and medicine may allow for early and efficient diagnosis of certain diseases.
During his academic career, Mashaghi has been affiliated with various institutions including Harvard University, Leiden University, Massachusetts Institute of Technology, Delft University of Technology, ETH Zurich, Max Planck Institutes, and AMOLF. Mashaghi has published more than 100 papers in peer-reviewed scientific journals including several papers in Nature and Nature specialty journals. He worked and co-authored with Hans Clevers, Cees Dekker, Anthony A. Hyman, Colin Adams, Erica Flapan, Donald E. Ingber, Huib Bakker, Reza Dana, and Petra Schwille. He serves on editorial board of several journals including Nano Research.
In 2018, Mashaghi has been named as "Discoverer of the Year" by Leiden University. He is the recipient of several awards including an honorarium from American Chemical Society. | 0 | Theoretical and Fundamental Chemistry |
In many substitution reactions, well-defined intermediates are not observed, when the rate of such processes are influenced by the nature of the entering ligand, the pathway is called associative interchange, abbreviated I. Representative is the interchange of bulk and coordinated water in [V(HO)]. In contrast, the slightly more compact ion [Ni(HO)] exchanges water via the I. | 0 | Theoretical and Fundamental Chemistry |
Redox reactions can occur slowly, as in the formation of rust, or rapidly, as in the case of burning fuel. Electron transfer reactions are generally fast, occurring within the time of mixing.
The mechanisms of atom-transfer reactions are highly variable because many kinds of atoms can be transferred. Such reactions can also be quite complex, involving many steps. The mechanisms of electron-transfer reactions occur by two distinct pathways, inner sphere electron transfer and outer sphere electron transfer.
Analysis of bond energies and ionization energies in water allow calculation of the thermodynamic aspects of redox reactions. | 0 | Theoretical and Fundamental Chemistry |
* Electrochemical Society Monograph Series
ECS Monographs provide accounts on specific topics in electrochemistry and solid-state science and technology. Since the 1940s, ECS and publishers have cooperated to publish titles in these fields. | 0 | Theoretical and Fundamental Chemistry |
The classical shotgun sequencing was based on the Sanger sequencing method: this was the most advanced technique for sequencing genomes from about 1995–2005. The shotgun strategy is still applied today, however using other sequencing technologies, such as short-read sequencing and long-read sequencing.
Short-read or "next-gen" sequencing produces shorter reads (anywhere from 25–500bp) but many hundreds of thousands or millions of reads in a relatively short time (on the order of a day).
This results in high coverage, but the assembly process is much more computationally intensive. These technologies are vastly superior to Sanger sequencing due to the high volume of data and the relatively short time it takes to sequence a whole genome. | 1 | Applied and Interdisciplinary Chemistry |
Conductive anodic filament, also called CAF, is a metallic filament that forms from an electrochemical migration process and is known to cause printed circuit board (PCB) failures. | 0 | Theoretical and Fundamental Chemistry |
Another reaction that can sometimes occur instead of disproportionation is recombination. During recombination, two radicals form one new non-radical product and one new bond. Similar to disproportionation, the recombination reaction is exothermic and requires little to no activation energy. The ratio of the rates of disproportionation to recombination is referred to as k/k and often favors recombination compared with disproportionation for alkyl radicals. As the number of transferable hydrogens increase, the rate constant for disproportionation increases relative to the rate constant for recombination. | 0 | Theoretical and Fundamental Chemistry |
A positive displacement meter may be compared to a bucket and a stopwatch. The stopwatch is started when the flow starts and stopped when the bucket reaches its limit. The volume divided by the time gives the flow rate. For continuous measurements, we need a system of continually filling and emptying buckets to divide the flow without letting it out of the pipe. These continuously forming and collapsing volumetric displacements may take the form of pistons reciprocating in cylinders, gear teeth mating against the internal wall of a meter or through a progressive cavity created by rotating oval gears or a helical screw. | 1 | Applied and Interdisciplinary Chemistry |
Burks developed an interest in forensic chemistry when she was 12 after a field trip that presented students with a science interaction challenge, asking students to solve a real-world problem using science. Burks earned her BS in chemistry at the University of Northern Iowa, her MSc in Forensic Science at Nebraska Wesleyan University, her PhD in chemistry from the University of Nebraska - Lincoln, and was a postdoctoral research associate at the Doane College. | 0 | Theoretical and Fundamental Chemistry |
The advent of displacement chromatography can be attributed to Arne Tiselius, who in 1943 first classified the modes of chromatography as frontal, elution, and displacement. Displacement chromatography found a variety of applications including isolation of transuranic elements and biochemical entities.
The technique was redeveloped by Csaba Horváth, who employed modern high-pressure columns and equipment. It has since found many applications, particularly in the realm of biological macromolecule purification. | 0 | Theoretical and Fundamental Chemistry |
Stereoelectronic effects can have a significant influence in pharmaceutical research. Generally, the substitution of hydrogen by fluorine could be regarded as a way to tune both the hydrophobicity and the metabolic stability of a drug candidate. Moreover, it can have a profound influence on conformations, often due to stereoelectronic effects, in addition to normal steric effects resulting from the larger size of the fluorine atom. For instance, the ground state geometries of anisole (methoxybenzene) and (trifluoromethoxy)benzene differ dramatically. In anisole, the methyl group prefers to be coplanar with the phenyl group, while (trifluoromethoxy)benzene favors a geometry in which the [C(aryl)–C(aryl)–O–C(F)] dihedral angle is around 90°. In other words, the O–CF bond is perpendicular to the plane of the phenyl group.
Further studies illustrate that even for only one or two hydrogen atoms in a methyl group being replaced by a fluorine atom, the distortion in the structure can also be significant, with the [C(aryl)–C(aryl)–O–C(HF)] dihedral angle in the energy minimized structure being around 24° and the [C(aryl)–C(aryl)–O–C(HF)] dihedral angle 33°. | 0 | Theoretical and Fundamental Chemistry |
This system functions similarly to the branch-chain fatty acid synthesizing system, however it uses short-chain carboxylic acids as primers instead of alpha-keto acids. In general, this method is used by bacteria that do not have the ability to perform the branch-chain fatty acid system using alpha-keto primers. Typical short-chain primers include isovalerate, isobutyrate, and 2-methyl butyrate. In general, the acids needed for these primers are taken up from the environment; this is often seen in ruminal bacteria.
The overall reaction is:
: Isobutyryl-CoA + 6 malonyl-CoA +12 NADPH + 12 → Isopalmitic acid + 6 12 NADP + 5 + 7 CoA
The difference between (straight-chain) fatty acid synthase and branch-chain fatty acid synthase is substrate specificity of the enzyme that catalyzes the reaction of acyl-CoA to acyl-ACP. | 1 | Applied and Interdisciplinary Chemistry |
In this boundary condition, the model is axisymmetric with respect to the main axis such that at a particular r = R, all θs and each z = Z-slice, each flow variable has the same value. A good example is the flow in a circular pipe where the flow and pipe axes coincide.
<br /> | 1 | Applied and Interdisciplinary Chemistry |
In some reactions, protons and hydroxide may directly act as acid and base in term of specific acid and specific base catalysis. But more often groups in substrate and active site act as Brønsted–Lowry acid and base. This is called general acid and general base theory. The easiest way to distinguish between them is to check whether the reaction rate is determined by the concentrations of the general acid and base. If the answer is yes then the reaction is the general type. Since most enzymes have an optimum pH of 6 to 7, the amino acids in the side chain usually have a pK of 4~10. Candidate include aspartate, glutamate, histidine, cysteine. These acids and bases can stabilise the nucleophile or electrophile formed during the catalysis by providing positive and negative charges. | 1 | Applied and Interdisciplinary Chemistry |
Possible reactivity at aldehydes include nucleophilic attack and addition of allylmetals. The stereoselectivity of nucleophilic attack at alpha-chiral aldehydes may be described by the Felkin–Anh or polar Felkin Anh models and addition of achiral allylmetals may be described by Cram’s rule. | 0 | Theoretical and Fundamental Chemistry |
In bacteria, the initiation of translation occurs when IF-3, along with the 30S ribosomal subunit, bind to the Shine–Dalgarno (SD) sequence of the 5′ UTR. This then recruits many other proteins, such as the 50S ribosomal subunit, which allows for translation to begin. Each of these steps regulates the initiation of translation.
Initiation in Archaea is less understood. SD sequences are much rarer, and the initiation factors have more in common with eukaryotic ones. There is no homolog of bacterial IF3. Some mRNAs are leaderless.
In both domains, genes without Shine–Dalgarno sequences are also translated in a less understood manner. A requirement seems to be a lack of secondary structure near the initiation codon. | 1 | Applied and Interdisciplinary Chemistry |
In some cases stoichiometric amounts of silver oxide can be used in place of CuI for copper-free Sonogashira couplings. | 0 | Theoretical and Fundamental Chemistry |
Women have served widely as pharmacists. However, as with women in many jobs, women in pharmacy have been restricted. For example, only in 1964 was the American Civil Rights Act of 1964 () enacted, which outlawed refusing to hire women because of their sex including though not limited to in the profession of pharmacist. Even today, not all countries ensure equal employment opportunities for women. | 1 | Applied and Interdisciplinary Chemistry |
Grignard reagents serve as a base for non-protic substrates (this scheme does not show workup conditions, which typically includes water). Grignard reagents are basic and react with alcohols, phenols, etc. to give alkoxides (ROMgBr). The phenoxide derivative is susceptible to formylation by paraformaldehyde to give salicylaldehyde. | 0 | Theoretical and Fundamental Chemistry |
In a closed system, no mass may be transferred in or out of the system boundaries. The system always contains the same amount of matter, but (sensible) heat and (boundary) work can be exchanged across the boundary of the system. Whether a system can exchange heat, work, or both is dependent on the property of its boundary.
* Adiabatic boundary – not allowing any heat exchange: A thermally isolated system
* Rigid boundary – not allowing exchange of work: A mechanically isolated system
One example is fluid being compressed by a piston in a cylinder. Another example of a closed system is a bomb calorimeter, a type of constant-volume calorimeter used in measuring the heat of combustion of a particular reaction. Electrical energy travels across the boundary to produce a spark between the electrodes and initiates combustion. Heat transfer occurs across the boundary after combustion but no mass transfer takes place either way.
The first law of thermodynamics for energy transfers for closed system may be stated:
where denotes the internal energy of the system, heat added to the system, the work done by the system. For infinitesimal changes the first law for closed systems may stated:
If the work is due to a volume expansion by at a pressure then:
For a quasi-reversible heat transfer, the second law of thermodynamics reads:
where denotes the thermodynamic temperature and the entropy of the system. With these relations the fundamental thermodynamic relation, used to compute changes in internal energy, is expressed as:
For a simple system, with only one type of particle (atom or molecule), a closed system amounts to a constant number of particles. For systems undergoing a chemical reaction, there may be all sorts of molecules being generated and destroyed by the reaction process. In this case, the fact that the system is closed is expressed by stating that the total number of each elemental atom is conserved, no matter what kind of molecule it may be a part of. Mathematically:
where denotes the number of -type molecules, the number of atoms of element in molecule , and the total number of atoms of element in the system, which remains constant, since the system is closed. There is one such equation for each element in the system. | 0 | Theoretical and Fundamental Chemistry |
Hot black oxide for stainless steel is a mixture of caustic, oxidizing, and sulfur salts. It blackens 300 and 400 series and the precipitation-hardened 17-4 PH stainless steel alloys. The solution can be used on cast iron and mild low-carbon steel. The resulting finish complies with military specification MIL-DTL–13924D Class 4 and offers abrasion resistance. Black oxide finish is used on surgical instruments in light-intensive environments to reduce eye fatigue.
Room-temperature blackening for stainless steel occurs by auto-catalytic reaction of copper-selenide depositing on the stainless-steel surface. It offers less abrasion resistance and the same corrosion protection as the hot blackening process. | 0 | Theoretical and Fundamental Chemistry |
Permeable paving surfaces are made of either a porous material that enables stormwater to flow through it or nonporous blocks spaced so that water can flow between the gaps. Permeable paving can also include a variety of surfacing techniques for roads, parking lots, and pedestrian walkways. Permeable pavement surfaces may be composed of; pervious concrete, porous asphalt, paving stones, or interlocking pavers. Unlike traditional impervious paving materials such as concrete and asphalt, permeable paving systems allow stormwater to percolate and infiltrate through the pavement and into the aggregate layers and/or soil below. In addition to reducing surface runoff, permeable paving systems can trap suspended solids, thereby filtering pollutants from stormwater.
Permeable pavement is commonly used on roads, paths and parking lots subject to light vehicular traffic, such as cycle-paths, service or emergency access lanes, road and airport shoulders, and residential sidewalks and driveways. | 1 | Applied and Interdisciplinary Chemistry |
In an inversion through a centre of symmetry, (the element), we imagine taking each point in a molecule and then moving it out the same distance on the other side. In summary, the inversion operation projects each atom through the centre of inversion and out to the same distance on the opposite side. The inversion center is a point in space that lies in the geometric center of the molecule. As a result, all the cartesian coordinates of the atoms are inverted (i.e. to ). The symbol used to represent inversion center is . When the inversion operation is carried out times, it is denoted by , where when is even and when is odd.
Examples of molecules that have an inversion center include certain molecules with octahedral geometry (general formula ), square planar geometry (general formula ), and ethylene (). Examples of molecules without inversion centers are cyclopentadienide () and molecules with trigonal pyramidal geometry (general formula ). | 0 | Theoretical and Fundamental Chemistry |
An other equation is applicable at low values of polarization . In such case, the dependence of current on polarization is usually linear (not logarithmic):
This linear region is called polarization resistance due to its formal similarity to Ohm's law. | 0 | Theoretical and Fundamental Chemistry |
Thermal rearrangements of aromatic hydrocarbons are considered to be unimolecular reactions that directly involve the atoms of an aromatic ring structure and require no other reagent than heat. These reactions can be categorized in two major types: one that involves a complete and permanent skeletal reorganization (isomerization), and one in which the atoms are scrambled but no net change in the aromatic ring occurs (automerization). The general reaction schemes of the two types are illustrated in Figure 1.
This class of reactions was uncovered through studies on the automerization of naphthalene as well as the isomerization of unsubstituted azulene, to naphthalene. Research on thermal rearrangements of aromatic hydrocarbons has since been expanded to isomerizations and automerizations of benzene and polycyclic aromatic hydrocarbons. | 0 | Theoretical and Fundamental Chemistry |
Ty5 is one of five endogenous retrotransposons native to the model organism Saccharomyces cerevisiae, all of which target integration to gene poor regions. Endogenous retrotransposons are hypothesized to target gene poor chromosomal targets in order to reduce the chance of inactivating host genes. Ty1-Ty4 integrate upstream of Pol III promoters, while Ty5 targets integration to loci bound in heterochromatin. In the case of Ty5, this likely occurs by means of an interaction between the C-terminus of integrase and a target protein. The tight targeting patterns seen for the Ty elements are thought to be a means to limit damage to its host, which has a very gene dense genome. Ty5 was discovered in the mid 1990s in the laboratory of Daniel Voytas at Iowa State University. Ty5 is used as a model system by which to understand the biology of the telomere and heterochromatin. The Ty5 retrotransposon is used as a genetic model to study the architecture and dynamics of the telomeres and heterochromatin. | 1 | Applied and Interdisciplinary Chemistry |
At the end of the Medieval Era and into the Post-Medieval Era, new types of crucible designs and processes started. Smelting and melting crucibles types started to become more limited in designs which are produced by a few specialists. The main types used during the Post Medieval period are the Hessian crucibles which were made in the Hesse region in Germany. These are triangular vessels made on a wheel or within a mold using high alumina clay and tempered with pure quartz sand. Furthermore, another specialized crucible which was made at the same time was that of a graphite crucible from southern Germany. These had a very similar design to that of the triangular crucibles from Hesse but they also occur in conical forms. These crucibles were traded all across Europe and the New World.
The refining of methods during the Medieval and Post-Medieval periods led to the invention of the cupel which resembles a small egg cup, made of ceramic or bone ash which was used to separate base metals from noble metals. This process is known as cupellation. Cupellation started long before the Post Medieval period, however, the first vessels made to carry out this process started in the 16th Century. Another vessel used for the same process is a scorifier which is similar to a cupel but slightly larger and removes the lead and leaves the noble metals behind. Cupels and scorifiers were mass-produced as after each reduction the vessels would have absorbed all of the lead and become fully saturated. These vessels were also used in the process of metallurgical assay where the noble metals are removed from a coin or a weight of metal to determine the amount of the noble metals within the object. | 0 | Theoretical and Fundamental Chemistry |
International treaties on the long-range transport of atmospheric pollutants have been agreed upon by western countries for some time now. Beginning in 1979, European countries convened in order to ratify general principles discussed during the UNECE Convention. The purpose was to combat Long-Range Transboundary Air Pollution. The 1985 Helsinki Protocol on the Reduction of Sulfur Emissions under the Convention on Long-Range Transboundary Air Pollution furthered the results of the convention. Results of the treaty have already come to fruition, as evidenced by an approximate 40 percent drop in particulate matter in North America. The effectiveness of the Convention in combatting acid rain has inspired further acts of international commitment to prevent the proliferation of particulate matter. Canada and the US signed the Air Quality Agreement in 1991. Most European countries and Canada signed the treaties. Activity of the Long-Range Transboundary Air Pollution Convention remained dormant after 1999, when 27 countries convened to further reduce the effects of acid rain. In 2000, foreign cooperation to prevent acid rain was sparked in Asia for the first time. Ten diplomats from countries ranging throughout the continent convened to discuss ways to prevent acid rain. Following these discussions, the Acid Deposition Monitoring Network in East Asia (EANET) was established in 2001 as an intergovernmental initiative to provide science-based inputs for decision makers and promote international cooperation on acid deposition in East Asia. In 2023, the EANET member countries include Cambodia, China, Indonesia, Japan, Lao PDR, Malaysia, Mongolia, Myanmar, the Philippines, Republic of Korea, Russia, Thailand and Vietnam. | 1 | Applied and Interdisciplinary Chemistry |
Victorium, originally named monium, is a mixture of gadolinium and terbium. In 1898, English chemist William Crookes reported his discovery of it in his inaugural address as president of the British Association for the Advancement of Science. He identified the new substance, based on an analysis of the unique phosphorescence and other ultraviolet-visible spectral phenomena, as a new chemical element, although this was later shown to be false. The name monium means "alone", because its spectral lines stood alone at the end of the ultraviolet spectrum. In 1899 Crookes renamed the purported element "victorium" in honor of Queen Victoria's recent diamond jubilee. He assigned it the symbol Vc. By 1905, however, French chemist Georges Urbain had proven that victorium was not a distinct element but rather an impurity of gadolinium. | 1 | Applied and Interdisciplinary Chemistry |
Non-protein phosphorylation has three general forms
* As a regulatory mechanism to control the function of the substrate, similar to the role of protein phosphorylation. Phosphoinositide lipids are important signaling molecules that have a variety of dedicated kinases and phosphatases.
* As an energetic intermediate. The phosphate bond is high-energy, so adding a phosphate increases the energy of a molecule, and removal of the phosphate can provide energy for an otherwise unfavorable reaction. For instance Glucose 6-phosphatase removes a phosphate group from glucose to complete gluconeogenesis.
* In biosynthesis, where the phosphate is a functional part of the mature molecule, and dephosphorylation degrades it or changes function. Nucleotidases are phosphatases used in nucleotide biosynthesis and breakdown.
The human non-protein phosphatome has been cataloged, but most phosphatome analyses are restricted to protein and lipid phosphatases that have regulatory functions. | 1 | Applied and Interdisciplinary Chemistry |
* Polyethylene glycol (PEG) hydrogels
* Poly (2-hydroxyethyl methacrylate) (PHEMA) hydrogels
Polyethylene glycol(PEG) polymers are synthetic materials that can be crosslinked to form hydrogels. PEG hydrogels are not toxic to the body, do not elicit an immune response, and have been approved by the US Food and Drug Administration for clinical use. The surfaces of PEG polymers are easily modified with peptide sequences that can attract cells for adhesion and could therefore be used for tissue regeneration.
Poly (2-hydroxyethyl methacrylate) (PHEMA) hydrogels can be combined with rosette nanotubes (RNTs). RNTs can emulate skin structures such as collagen and keratin and self-assemble when injected into the body. This type of hydrogel is being explored for use in skin regeneration and has shown promising results such as fibroblast and keratinocyte proliferation. Both of these cell types are crucial for the production of skin components. | 0 | Theoretical and Fundamental Chemistry |
After-rust is a form of rust which sometimes develops on a non-ferrous metal surface when that surface has been finished, deburred, or cleaned with a carbon steel brush or steel wool. It is caused by microscopic deposits of the steel which become embedded in the metal surface and which over time begin to oxidize. This oxidation causes the surface to become dull and may impart a brown color to it. After-rust can be avoided by cleaning such surfaces only with non-ferrous brushes/ wools including rustless bronze, aluminum, and stainless steel wool and nonferrous wools such as those made of brass. | 1 | Applied and Interdisciplinary Chemistry |
Perilipin expression is elevated in obese animals and humans. Polymorphisms in the human perilipin (PLIN) gene have been associated with variance in body-weight regulation and may be a genetic influence on obesity risk in humans.
This protein can be modified by O-linked acetylglucosamine (O-GlNac) moieties and the enzyme that intervenes is O-GlcNAc transferase (OGT). An abundance of OGT obstructs lipolysis and benefits diet-induced obesity and whole-body insulin resistance. Studies also propose that an overexpression of adipose O-GlcNAc signaling is a molecular expression of obesity and diabetes in humans. | 1 | Applied and Interdisciplinary Chemistry |
In at least one plant, Juglans regia, progesterone has been detected. In addition, progesterone-like steroids are found in Dioscorea mexicana. Dioscorea mexicana is a plant that is part of the yam family native to Mexico. It contains a steroid called diosgenin that is taken from the plant and is converted into progesterone. Diosgenin and progesterone are also found in other Dioscorea species, as well as in other plants that are not closely related, such as fenugreek.
Another plant that contains substances readily convertible to progesterone is Dioscorea pseudojaponica native to Taiwan. Research has shown that the Taiwanese yam contains saponins — steroids that can be converted to diosgenin and thence to progesterone.
Many other Dioscorea species of the yam family contain steroidal substances from which progesterone can be produced. Among the more notable of these are Dioscorea villosa and Dioscorea polygonoides. One study showed that the Dioscorea villosa contains 3.5% diosgenin. Dioscorea polygonoides has been found to contain 2.64% diosgenin as shown by gas chromatography-mass spectrometry. Many of the Dioscorea species that originate from the yam family grow in countries that have tropical and subtropical climates. | 0 | Theoretical and Fundamental Chemistry |
When orthoboric acid is dissolved in water, it partially dissociates to give metaboric acid:
The solution is mildly acidic due to ionization of the acids:
However, Raman spectroscopy of strongly alkaline solutions has shown the presence of ions, leading some to conclude that the acidity is exclusively due to the abstraction of from water:
Equivalently,
: + + (K = 7.3×10; pK = 9.14)
Or, more properly,
This reaction occurs in two steps, with the neutral complex aquatrihydroxyboron as an intermediate:
This reaction may be characterized as Lewis acidity of boron toward , rather than as Brønsted acidity. However, some of its behaviour towards some chemical reactions suggest it to be tribasic acid in the Brønsted sense as well.
Boric acid, mixed with borax (more properly ) in the weight ratio of 4:5, is highly soluble in water, though they are not so soluble separately. | 0 | Theoretical and Fundamental Chemistry |
From the description of the beginning of the fission process to the "scission point," it is apparent that the change of the shape of the nucleus is associated with a change of energy of some kind. In fact, it is the change of two types of energies: (1) the macroscopic energy related to the nuclear bulk properties as given by the liquid drop model and (2) the quantum mechanical energy associated with filling the shell model orbitals. For the nuclear bulk properties with small distortions, the surface, , and Coulomb, , energies are given by:
where and are the surface and Coulomb energies of the undistorted spherical drops, respectively, and is the quadrupole distortion parameter. When the changes in the Coulomb and surface energies (, ) are equal, the nucleus becomes unstable with respect to fission. At that point, the relationship between the undistorted surface and Coulomb energies becomes:
where is called the fissionability parameter. If , the liquid drop energy decreases with increasing , which leads to fission. If , then the liquid drop energy decreases with decreasing , which leads to spherical shapes of the nucleus.
The Coulomb and surface energies of a uniformly charged sphere can be approximated by the following expressions:
where is the atomic number of the nucleus, is the mass number of the nucleus, is the charge of an electron, is the radius of the undistorted spherical nucleus, is the surface tension per unit area of the nucleus, and . The equation for the fissionability parameter then becomes:
where the ratio of the constant is referred to as . The fissionability of a given nucleus can then be categorized relative to . As an example, plutonium-239 has a value of 36.97, while less fissionable nuclei like bismuth-209 have a value of 32.96.
For all stable nuclei, must be less than 1. In that case, the total deformation energy of nuclei undergoing fission will increase by an amount , as the nucleus deforms towards fission. This increase in potential energy can be thought of as the activation energy barrier for the fission reaction. However, modern calculations of the potential energy of deformation for the liquid drop model involve many deformation coordinates aside from and represent major computational tasks. | 0 | Theoretical and Fundamental Chemistry |
Digestion is a complex process controlled by several factors. pH plays a crucial role in a normally functioning digestive tract. In the mouth, pharynx and esophagus, pH is typically about 6.8, very weakly acidic. Saliva controls pH in this region of the digestive tract. Salivary amylase is contained in saliva and starts the breakdown of carbohydrates into monosaccharides. Most digestive enzymes are sensitive to pH and will denature in a high or low pH environment.
The stomach's high acidity inhibits the breakdown of carbohydrates within it. This acidity confers two benefits: it denatures proteins for further digestion in the small intestines, and provides non-specific immunity, damaging or eliminating various pathogens.
In the small intestines, the duodenum provides critical pH balancing to activate digestive enzymes. The liver secretes bile into the duodenum to neutralize the acidic conditions from the stomach, and the pancreatic duct empties into the duodenum, adding bicarbonate to neutralize the acidic chyme, thus creating a neutral environment. The mucosal tissue of the small intestines is alkaline with a pH of about 8.5. | 1 | Applied and Interdisciplinary Chemistry |
A transcription bubble is a molecular structure formed during DNA transcription when a limited portion of the DNA double helix is unwound. The size of a transcription bubble ranges from 12 to 14 base pairs. A transcription bubble is formed when the RNA polymerase enzyme binds to a promoter and causes two DNA strands to detach. It presents a region of unpaired DNA, where a short stretch of nucleotides are exposed on each strand of the double helix. | 1 | Applied and Interdisciplinary Chemistry |
Tripartite motif-containing 24 (TRIM24) also known as transcriptional intermediary factor 1α (TIF1α) is a protein that, in humans, is encoded by the TRIM24 gene. | 1 | Applied and Interdisciplinary Chemistry |
Dysfunctional or altered levels of carbaminohemoglobin do not generally cause disease or disorders. Carbaminohemoglobin is a part of the carbon dioxide transport process in the body. The levels of this protein can decrease and increase based on factors that regulate the protein in the body.
A way that carbaminohemoglobin can be associated with disease is when there is a change in its level caused by a pre-existing condition or imbalance in the respiratory and metabolic systems of the human body.
Some of these existing medical conditions can be the following:
# Respiratory acidosis: This condition is characterized by a build up of carbon dioxide in the blood, which leads to a drop in the blood's pH. This occurs when there is an impairment in the gas exchange process, such as respiratory failure.
# Hypoventilation: This type of condition can result in higher levels of carbaminohemoglobin. This condition can be caused by many factors, such as central nervous system disorders, and even some medications. | 1 | Applied and Interdisciplinary Chemistry |
Stars that burn hydrogen are called main sequence (MS) stars - these are by far the most common objects in the night sky. When the hydrogen fuel is exhausted and temperatures begin to fall, the object undergoes various transformations
and a white dwarf star is eventually born, the ember of the expired MS star. Temperatures of a new-born white dwarf may be in the hundreds of thousand kelvin, but if the mass of the white dwarf is less than just a few solar masses, burning of He to C and O is not possible and the star will slowly cool down forever. The coolest white dwarfs observed have temperatures of roughly 4000 K, which must mean that the universe is not old enough so that lower temperature stars cannot be found. The emission spectra of "cool" white dwarfs does not at all look like a Planck blackbody spectrum. Instead, nearly the whole infrared is attenuated or missing altogether from the star's emission, owing to CIA in the hydrogen-helium atmospheres surrounding their cores. The impact of CIA on the observed spectral energy distribution is well understood and accurately modeled for most cool white dwarfs. For white dwarfs with a mix H/He atmosphere, the intensity of the H-He CIA can be used to infer the hydrogen abundance at the white dwarf photosphere. However, predicting CIA in the atmospheres of the coolest white dwarfs is more challenging, in part because of the formation of many-body collisional complexes. | 0 | Theoretical and Fundamental Chemistry |
Cement-mortar lined ductile iron pipe is a ductile iron pipe with cement lining on the inside surface, and is commonly used for water distribution.
Cement-mortar lined ductile iron pipe is governed by standards set forth by DIPRA (Ductile Iron Pipe Research Association), and was first used in 1922 in Charleston, South Carolina.
Ductile Iron is commonly used in place of cast iron pipe for fluid distribution systems, the idea of lining the formerly cast iron and currently ductile iron was put into practice for the first time in Charleston, South Carolina in 1922. The purpose of installing a cement/mortar lining to the interior wall of the pipe is to reduce the process of tuberculation inside the pipe network. The cement/mortar lining provides an area of high pH near the pipe wall and provides a barrier between the water and the pipe, reducing its susceptibility to corrosion. | 1 | Applied and Interdisciplinary Chemistry |
Creeks have been closed to facilitate the creation of agricultural land and provide protection against floods in Bangladesh for many years. The combination of safeguarding against flooding, the need for agricultural land, and the availability of irrigation water served as the driving forces behind these initiatives. Prior to 1975, such closure works were relatively modest in scale. Some early examples include:
The approach to closures in Bangladesh did not significantly differ from practices elsewhere. However, due to the country's low labour costs and high unemployment rates, methods employing extensive local manpower were preferred.
These works primarily utilised a type of locally developed fascine rolls known as mata. The final gaps were closed swiftly within a single tidal cycle. Notably, the Gangrail closure failed twice.
In the years 1977/78, the Madargong creek was closed, safeguarding an agricultural area of 20,000 hectares. At the closure site, the creek spanned a width of 150 metres with a depth of 6 metres below mean sea level. The following year, 1978/79, saw the closure of the Chakamaya Khal, featuring a tidal prism of 10 million cubic metres, a tidal range of 3.3 metres, spanning 210 metres in width and 5 metres in depth.
In 1985, the Feni River was dammed to create an irrigation reservoir covering 1,200 hectares. The project was distinctive in its explicit request for the utilisation of local products and manual labour. The 1,200-metre-wide gap needed to be sealed during a neap tide. On the day of the closure, 12,000 workers placed 10,000 bags within the gap.
In 2020, the Nailan dam, originally constructed in the 1960s, experienced a breach that necessitated repair. At the time, the basin covered an area of 480 hectares, with a tidal range varying from 2.5 to 4 metres (neap tide to spring tide). The breach spanned a width of 500 metres, with a tidal prism of 7 million cubic metres. The closure was accomplished by deploying a substantial quantity of geobags, weighing up to 250 kg, though the majority of the bags in the core were 50 kg. The gap was progressively narrowed to 75 metres, the width of the final closure gap, which was sealed in one tidal cycle during a neap tide. To facilitate this, two rows of palisades were erected in the gap, and bags were used to fill the space between them, effectively creating a cofferdam. | 1 | Applied and Interdisciplinary Chemistry |
Vanillylmandelic acid (VMA) is a chemical intermediate in the synthesis of artificial vanilla flavorings and is an end-stage metabolite of the catecholamines (epinephrine, and norepinephrine). It is produced via intermediary metabolites. | 1 | Applied and Interdisciplinary Chemistry |
Many materials are able to be sprayed as coatings using the D-gun. These materials used for the feedstock are powders of metals, alloys and cermets; as well as their oxides. However, mainly high-tech coatings are used, these include ceramics, and complex composites. Characteristics such as strength, hardness, shrink, corrosion resistance and wearing quality of possible spraying materials are factored into the decision of selecting a coating material.
Some examples include:
* Al2O3
* Cu–Al
* Cu–SiC
* Al–Al2O3
* Cu–Al2O3
* Al–SiC
* Al–Ti
* TiMo(CN)–36NiCo
* Fe–A | 1 | Applied and Interdisciplinary Chemistry |
The correct structure of heme C was published in mid 20th century by the Swedish biochemist K.-G. Paul. This work confirmed the structure first inferred by the great Swedish biochemist Hugo Theorell. The structure of heme C, based upon NMR and IR experiments of the reduced Fe(II) form of the heme, was confirmed in 1975. The structure of heme C including the absolute stereochemical configuration about the thioether bonds was first presented for the vertebrate protein, cytochrome c and is now extended to many other heme C containing proteins. | 1 | Applied and Interdisciplinary Chemistry |
Radionuclides that find their way into the environment may cause harmful effects as radioactive contamination. They can also cause damage if they are excessively used during treatment or in other ways exposed to living beings, by radiation poisoning. Potential health damage from exposure to radionuclides depends on a number of factors, and "can damage the functions of healthy tissue/organs. Radiation exposure can produce effects ranging from skin redness and hair loss, to radiation burns and acute radiation syndrome. Prolonged exposure can lead to cells being damaged and in turn lead to cancer. Signs of cancerous cells might not show up until years, or even decades, after exposure." | 0 | Theoretical and Fundamental Chemistry |
Conditions for hydroformylation catalysis can induce degradation of supporting organophosphorus ligands. Triphenylphosphine is subject to hydrogenolysis, releasing benzene and diphenylphosphine. The insertion of carbon monoxide in an intermediate metal-phenyl bond can lead to the formation of benzaldehyde or by subsequent hydrogenation to benzyl alcohol. One of the ligands phenyl-groups can be replaced by propene, and the resulting diphenylpropylphosphine ligand can inhibit the hydroformylation reaction due to its increased basicity. | 0 | Theoretical and Fundamental Chemistry |
Cataclasis, or comminution, is a non-elastic brittle mechanism that operates under low to moderate homologous temperatures, low confining pressure and relatively high strain rates. It occurs only above a certain differential stress level, which is dependent on fluid pressure and temperature. Cataclasis accommodates the fracture and crushing of grains, causing grain size reduction, along with frictional sliding on grain boundaries and rigid body grain rotation. Intense cataclasis occurs in thin zones along slip or fault surfaces where extreme grain size reduction occurs. In rocks, cataclasis forms a cohesive and fine-grained fault rock called cataclasite. Cataclastic flow occurs during shearing when a rock deform by microfracturing and frictional sliding where tiny fractures (microcracks), and associated rock fragments move past each other. Cataclastic flow usually occurs at diagenetic to low-grade metamorphic conditions. However, this depends on the mineralogy of the material and the extent of pore fluid pressure. Cataclastic flow is generally unstable and will terminate by the localization of deformation into slip on fault planes. | 1 | Applied and Interdisciplinary Chemistry |
__FORCETOC__
Formamide-based prebiotic chemistry is a reconstruction of the beginnings of life on Earth, assuming that formamide could accumulate in sufficiently high amounts to serve as the building block and reaction medium for the synthesis of the first biogenic molecules.
Formamide (NHCHO), the simplest naturally occurring amide, contains all the elements (hydrogen, carbon, oxygen, and nitrogen), which are required for the synthesis of biomolecules, and is a ubiquitous molecule in the universe. Formamide has been detected in galactic centers, star-forming regions of dense molecular clouds, high-mass young stellar objects, the interstellar medium, comets, and satellites. In particular, dense clouds containing formamide, with sizes on the order of kiloparsecs, have been observed in the vicinity of the Solar System.
Formamide forms under a variety of conditions, corresponding to both terrestrial environments and interstellar media: e.g., on high-energy particle irradiation of binary mixtures of ammonia (NH) and carbon monoxide (CO), or from the reaction between formic acid (HCOOH) with NH. It has been suggested that in hydrothermal pores formamide may accumulate in sufficiently high concentrations to enable synthesis of biogenic molecules. Ab initio molecular dynamics simulations suggest that formamide could be a key intermediate of the Miller–Urey experiment as well.
The combinatorial power of carbon is manifested in the composition of the molecular populations detected in circum- and interstellar media (see the Astrochemistry.net web site). The number and the complexity of carbon-containing molecules are significantly higher than those of inorganic compounds, presumably all over the universe. One of the most abundant C-containing three-atoms molecule observed in space is hydrogen cyanide (HCN). The chemistry of HCN has thus attracted attention in origin of life studies since the earliest times, and the laboratory synthesis of adenine from HCN under presumptive prebiotic conditions was reported as early as 1961. The intrinsic limit of HCN stems from its high reactivity, which leads in turn, to instability and the difficulty associated with its concentration and accumulation in unreacted form. The “Warm Little Pond” in which life is supposed to have started, as imagined by Charles Darwin and re-elaborated by Alexander Oparin, had most likely to reach sufficiently high concentrations to start creating the next levels of complexity. Hence the necessity of a derivative of HCN that is sufficiently stable to survive for time periods extended enough to allow its concentration in the actual physico-chemical settings, but that is sufficiently reactive to originate new compounds in prebiotically plausible environments. Ideally, this derivative should be able to undergo reactions in various directions, without prohibitively high energy barriers, thus allowing the production of different classes of potentially prebiotic compounds. Formamide fulfils all these requirements and, due to its significantly higher boiling point (210 °C), enables chemical synthesis in a much broader temperature range than water. | 0 | Theoretical and Fundamental Chemistry |
Because of the magnitude and severity of the problems with chemical shift referencing in biomolecular NMR, a number of computer programs have been developed to help mitigate the problem (see Table 1 for a summary). The first program to comprehensively tackle chemical shift mis-referencing in biomolecular NMR was SHIFTCOR.
Table 1. Summary and comparison of different chemical shift re-referencing and mis-assignment detection programs. | 0 | Theoretical and Fundamental Chemistry |
3-Phosphoglyceric acid (3PG, 3-PGA, or PGA) is the conjugate acid of 3-phosphoglycerate or glycerate 3-phosphate (GP or G3P). This glycerate is a biochemically significant metabolic intermediate in both glycolysis and the Calvin-Benson cycle. The anion is often termed as PGA when referring to the Calvin-Benson cycle. In the Calvin-Benson cycle, 3-phosphoglycerate is typically the product of the spontaneous scission of an unstable 6-carbon intermediate formed upon CO fixation. Thus, two equivalents of 3-phosphoglycerate are produced for each molecule of CO that is fixed. In glycolysis, 3-phosphoglycerate is an intermediate following the dephosphorylation (reduction) of 1,3-bisphosphoglycerate. | 0 | Theoretical and Fundamental Chemistry |
Used nuclear fuel is a complex mixture of the fission products, uranium, plutonium, and the transplutonium metals. In fuel which has been used at high temperature in power reactors it is common for the fuel to be heterogeneous; often the fuel will contain nanoparticles of platinum group metals such as palladium. Also the fuel may well have cracked, swollen, and been heated close to its melting point. Despite the fact that the used fuel can be cracked, it is very insoluble in water, and is able to retain the vast majority of the actinides and fission products within the uranium dioxide crystal lattice. The radiation hazard from spent nuclear fuel declines as its radioactive components decay, but remains high for many years. For example 10 years after removal from a reactor, the surface dose rate for a typical spent fuel assembly still exceeds 10,000 rem/hour, resulting in a fatal dose in just minutes. | 0 | Theoretical and Fundamental Chemistry |
Detergents are classified into four broad groupings, depending on the electrical charge of the surfactants. | 0 | Theoretical and Fundamental Chemistry |
Formulation studies involve developing a preparation of the drug which is both stable and acceptable to the patients. For orally administered drugs, this usually involves incorporating the drug into a tablet or a capsule. It is important to make the distinction that a tablet contains a variety of other potentially inert substances apart from the drug itself, and studies have to be carried out to ensure that the encapsulated drug is compatible with these other substances in a way that does not cause harm, whether direct or indirect.
Preformulation involves the characterization of a drug's physical, chemical, and mechanical properties in order to choose what other ingredients (excipients) should be used in the preparation. In dealing with protein pre-formulation, the important aspect is to understand the solution behavior of a given protein under a variety of stress conditions such as freeze/thaw, temperature, shear stress among others to identify mechanisms of degradation and therefore its mitigation.
Formulation studies then consider such factors as particle size, polymorphism, pH, and solubility, as all of these can influence bioavailability and hence the activity of a drug. The drug must be combined with inactive ingredients by a method that ensures that the quantity of drug present is consistent in each dosage unit e.g. each tablet. The dosage should have a uniform appearance, with an acceptable taste, tablet hardness, and capsule disintegration.
It is unlikely that formulation studies will be complete by the time clinical trials commence. This means that simple preparations are developed initially for use in phase I clinical trials. These typically consist of hand-filled capsules containing a small amount of the drug and a diluent. Proof of the long-term stability of these formulations is not required, as they will be used (tested) in a matter of days. Consideration has to be given to what is known as "drug loading" - the ratio of the active drug to the total contents of the dose. A low drug load may cause homogeneity problems. A high drug load may pose flow problems or require large capsules if the compound has a low bulk density.
By the time phase III clinical trials are reached, the formulation of the drug should have been developed to be close to the preparation that will ultimately be used in the market. A knowledge of stability is essential by this stage, and conditions must have been developed to ensure that the drug is stable in the preparation. If the drug proves unstable, it will invalidate the results from clinical trials since it would be impossible to know what the administered dose actually was. Stability studies are carried out to test whether temperature, humidity, oxidation, or photolysis (ultraviolet light or visible light) have any effect, and the preparation is analysed to see if any degradation products have been formed. | 1 | Applied and Interdisciplinary Chemistry |
The second chapter of the Vaisheshika Sutras presents five substances (earth, air, water, fire, space) each with a distinct quality. Kanada argues that all except "air and space" is verifiable by perception, while existence of invisible air is established by inference (air blows, and that there must be a substance that affects the touch sensation to the skin; space, he argues, is inferred from one's ability to move from one point to another unhindered - a point he revises in later part of the text by asserting that sound is perceived and proves space). | 1 | Applied and Interdisciplinary Chemistry |
NRIP1 has been shown to interact with:
* AHR,
* CTBP1
* CTBP2,
* DAX1,
* HDAC5,
* NR1B1,
* NR2B1,
* NR3A1,
* NR3C1,
* NR5A1, and
* YWHAQ. | 1 | Applied and Interdisciplinary Chemistry |
The equation has been, and remains very useful because:
* Its coefficient of thermal expansion, has a simple analytic expression [this is also true of its isothermal compressibility, ]
* it explains the existence of the critical point and the liquid–vapor phase transition including the observed metastable states
* it establishes the law of corresponding states
* its specific heat at constant volume, , can be shown to be a function of only, and its thermodynamic properties, internal energy , entropy , as well as the specific heat at constant pressure have simple analytic expressions [this is also true of enthalpy , Helmholtz free energy , and Gibbs free energy ]
* its Joule–Thomson coefficient and associated inversion curve, which were instrumental in the commercial liquefaction of gases have simple analytic expressions.
The equation also plays an important role in the modern theory of phase transitions. It depicts the liquid metals, Mercury and Cesium, quantitatively, and describes most real fluids qualitatively. Consequently it can be regarded as one member of a family of equations of state, that depend on a molecular parameter such as the critical compressibility factor, , or the Pitzer (acentric) factor, , where is a dimensionless saturation pressure, and log is the logarithm base 10.
All this makes it a worthwhile pedagogical tool for physics, chemistry, and engineering lecturers, in addition to being a useful mathematical model which can aid student understanding. | 0 | Theoretical and Fundamental Chemistry |
In organic chemistry, anti-periplanar, or antiperiplanar, describes the bond angle in a molecule. In this conformer, the dihedral angle of the bond and the bond is greater than +150° or less than −150° (Figures 1 and ). Anti-periplanar is often used in textbooks to mean strictly anti-coplanar, with an dihedral angle of 180° (Figure 3). In a Newman projection, the molecule will be in a staggered arrangement with the anti-periplanar functional groups pointing up and down, 180° away from each other (see Figure 4). Figure 5 shows 2-chloro-2,3-dimethylbutane in a sawhorse projection with chlorine and a hydrogen anti-periplanar to each other.
Syn-periplanar or synperiplanar is similar to anti-periplanar. In the syn-periplanar conformer, the A and D are on the same side of the plane of the bond, with the dihedral angle of and between +30° and −30° (see Figure 2). | 0 | Theoretical and Fundamental Chemistry |
* Marion B. Sewer Distinguished Scholarship for Undergraduates
* Promoting Research Opportunities for Latin American Biochemists
* ASBMB Science Fair Award | 1 | Applied and Interdisciplinary Chemistry |
For individuals not previously exposed to OC effects, the general feelings after being sprayed can be best likened to being "set alight". The initial reaction, should the spray be directed at the face, is the involuntary closing of the eyes, an instant sensation of the restriction of the airways and the general feeling of sudden and intense searing pain about the face, nose, and throat. This is due to irritation of mucous membranes. Many people experience fear and are disoriented due to sudden restriction of vision even though it is temporary. There is associated shortness of breath, although studies performed with asthmatics have not produced any asthma attacks in those individuals, and monitoring is still needed for the individuals after exposure. Police are trained to repeatedly instruct targets to breathe normally if they complain of difficulty, as the shock of the exposure can generate considerable panic as opposed to actual physical symptoms. | 1 | Applied and Interdisciplinary Chemistry |
* Dragomir Vitorović, Snežana Bojović, Živorad Čeković: “Vukić M. Mićović 1896-1981, life and work", Faculty of Chemistry, Belgrade, 1996, 142 pages. | 0 | Theoretical and Fundamental Chemistry |
In Victoria, Australia, at the Brunswick brickworks, there are two surviving kilns converted to residences, and a chimney from a third kiln; there is another in Box Hill, Victoria; also in Melbourne.
In Adelaide, South Australia, the last remaining Hoffman kiln in the state is in at the old Hallett Brickworks site in Torrensville.
There is one at St Peters in Sydney, New South Wales.
In Western Australia, the kiln at the Maylands Brickworks in the Perth suburb of Maylands, which operated from 1927 to 1982 is the only remaining Hoffman kiln in the state. | 1 | Applied and Interdisciplinary Chemistry |
In the field of paleochemotaxonomy the presence of biogenic substances in geological sediments is useful for comparing old and modern biological samples and species. These biological markers can be used to verify the biological origin of fossils and serve as paleo-ecological markers. For example, the presence of pristane indicates that the petroleum or sediment is of marine origin, while biogenic material of non-marine origin tends to be in the form of polycyclic compounds or phytane. The biological markers also provide valuable information about the degradation reactions of biological material in geological environments. Comparing the organic material between geologically old and recent rocks shows the conservation of different biochemical processes. | 0 | Theoretical and Fundamental Chemistry |
DBTSS, the DataBase of Transcriptional Start Sites, is a database hosted by the Human Genome Center at the University of Tokyo. It contains the exact positions of transcriptional start sites in the genomes of various organisms. | 1 | Applied and Interdisciplinary Chemistry |
Carcinoembryonic antigen cell adhesion molecule-1 (Caecam1) is an immunoglobulin-like co-receptor that aids in cell adhesion in epithelial, endothelial and hematopoietic cells, and plays a vital role during vascularization and angiogenesis by binding vascular endothelial growth factor (VEGF).
Angiogenesis is important in embryonic development but it is also a fundamental process of tumor growth. Deletion of the gene in Caecam1-/- mice results in a reduction of the abnormal vascularization seen in cancer and lowered nitric oxide production, suggesting a therapeutic possibility through targeting of this gene. The neuropilin co-receptor family mediates binding of VEGF in conjunction with the VEGFR1/VEGFR2 and Plexin signaling receptors, and therefore also plays a role in tumor vascular development.
CD109 acts as a negative regulator of the tumor growth factor β (TGF-β) receptor. Upon binding TGF-β, the receptor is internalized via endocytosis through CD109's action which lowers signal transmission into the cell. In this case, the co-receptor is functioning in a critical regulatory manner to reduce signals that instruct the cell to grow and migrate – the hallmarks of cancer. In conjunction, the LRP co-receptor family also mediates binding of TGF-β with a variety of membrane receptors.
Interleukins 1, 2, and 5 all rely on interleukin co-receptors to bind to the primary interleukin receptors.
Syndecans 1 and 4 have been implicated in a variety of cancer types including cervical, breast, lung, and colon cancer, and abnormal expression levels have been associated with poorer prognosis. | 1 | Applied and Interdisciplinary Chemistry |
Depending on the regime under investigation, different approaches can be used to model the dispersed gas phase. The simplest is to use a fixed bubble size distribution. This approximation is suitable to simulate the homogeneous flow regime, where the interactions between the bubbles are negligible. In addition, this approach calls for the knowledge of the bubbles diameter since it is an input parameter for the simulations.
However, in industrial practice, large-scale bubble columns are typically employed, equipped with gas distributors characterized by large openings, so a heterogeneous flow regime is commonly observed. Bubble coalescence and breakup phenomena are relevant and can not be neglected. In this case, the CFD model can be coupled with a Population Balance Model (PBM) to account for the changes in bubbles size.
A Population Balance Model consists of a transport equation derived from the Boltzmann statistical transport equation, and it describes the particles entering or leaving a control volume via several mechanisms. The bubble number density transport equation is also known as Population Balance Equation (PBE):
Where is the bubble number density function and represents the probable number density of bubbles at a given time , about a position , with bubble volume between and , and is the bubble velocity. The right and side term of the Population Balance Equation is the source/sink term due to bubbles coalescence, breakup, phase change, pressure change, mass transfer, and chemical reactions. | 1 | Applied and Interdisciplinary Chemistry |
In the chemistry of electrolyte solutions, an ideal solution is a solution whose colligative properties are proportional to the concentration of the solute. Real solutions may show departures from this kind of ideality. In order to accommodate these effects in the thermodynamics of solutions, the concept of activity was introduced: the properties are then proportional to the activities of the ions. Activity, a, is proportional to concentration, c. The proportionality constant is known as an activity coefficient, .
In an ideal electrolyte solution the activity coefficients for all the ions are equal to one. Ideality of an electrolyte solution can be achieved only in very dilute solutions. Non-ideality of more concentrated solutions arises principally (but not exclusively) because ions of opposite charge attract each other due to electrostatic forces, while ions of the same charge repel each other. In consequence ions are not randomly distributed throughout the solution, as they would be in an ideal solution.
Activity coefficients of single ions cannot be measured experimentally because an electrolyte solution must contain both positively charged ions and negatively charged ions. Instead, a mean activity coefficient, is defined. For example, with the electrolyte NaCl
In general, the mean activity coefficient of a fully dissociated electrolyte of formula AB is given by
Activity coefficients are themselves functions of concentration as the amount of inter-ionic interaction increases as the concentration of the electrolyte increases. Debye and Hückel developed a theory with which single ion activity coefficients could be calculated. By calculating the mean activity coefficients from them the theory could be tested against experimental data. It was found to give excellent agreement for "dilute" solutions. | 0 | Theoretical and Fundamental Chemistry |
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