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In the case of esterification with acetic anhydrides the currently accepted mechanism involves three steps. First, DMAP and acetic anhydride react in a pre-equilibrium reaction to form an ion pair of acetate and the acetylpyridinium ion. In the second step the alcohol adds to the acetylpyridinium, and elimination of pyridine forms an ester. Here the acetate acts as a base to remove the proton from the alcohol as it nucleophilically adds to the activated acylpyridinium. The bond from the acetyl group to the catalyst gets cleaved to generate the catalyst and the ester. The described bond formation and breaking process runs synchronous concerted without the appearance of a tetrahedral intermediate. The acetic acid formed will then protonate the DMAP. In the last step of the catalytic cycle the auxiliary base (usually triethylamine or pyridine) deprotonates the protonated DMAP, reforming the catalyst. The reaction runs through the described nucleophilic reaction pathway irrespective of the anhydride used, but the mechanism changes with the pKa value of the alcohol used. For example, the reaction runs through a base-catalyzed reaction pathway in the case of a phenol. In this case, DMAP acts as a base and deprotonates the phenol, and the resulting phenolate ion adds to the anhydride. | 0 | Theoretical and Fundamental Chemistry |
Since 2012, the Bill and Melinda Gates Foundation has been funding research into omni processors. An omni processor is any of various types of technologies that treat fecal sludge, also known as septage to remove pathogens and simultaneously extract byproducts with commercial value, for example energy or soil nutrients, the latter which could be reused in agriculture. The omni processor program, which targets community-scale solutions that may optionally combine sludge and solid waste processing, complements the foundation's pit latrine emptying ("omni-ingestor") and "Reinvent the Toilet" programs. | 1 | Applied and Interdisciplinary Chemistry |
In chemistry, phosphorus oxoacid (or phosphorus acid) is a generic name for any acid whose molecule consists of atoms of phosphorus, oxygen, and hydrogen. There is a potentially infinite number of such compounds. Some of them are unstable and have not been isolated, but the derived anions and organic groups are present in stable salts and esters. The most important ones—in biology, geology, industry, and chemical research—are the phosphoric acids, whose esters and salts are the phosphates.
In general, any hydrogen atom bonded to an oxygen atom is acidic, meaning that the –OH group can lose a proton leaving a negatively charged – group and thus turning the acid into a phosphorus oxoanion. Each additional proton lost has an associated acid dissociation constant K, K K, ..., often expressed by its cologarithm (pK, pK, pK, ...). Hydrogen atoms bonded directly to phosphorus are generally not acidic. | 0 | Theoretical and Fundamental Chemistry |
Optical isomerism occurs when a complex is not superimposable with its mirror image. It is so called because the two isomers are each optically active, that is, they rotate the plane of polarized light in opposite directions. In the first molecule shown, the symbol Λ (lambda) is used as a prefix to describe the left-handed propeller twist formed by three bidentate ligands. The second molecule is the mirror image of the first, with the symbol Δ (delta) as a prefix for the right-handed propeller twist. The third and fourth molecules are a similar pair of Λ and Δ isomers, in this case with two bidentate ligands and two identical monodentate ligands. | 0 | Theoretical and Fundamental Chemistry |
These glycosides contain an aglycone group that is a derivative of anthraquinone. They have a laxative effect. They are mainly found in dicot plants except the family Liliaceae which are monocots. They are present in senna, rhubarb and Aloe species. Anthron and anthranol are reduced forms of anthraquinone. | 0 | Theoretical and Fundamental Chemistry |
Gofman was born in Cleveland, Ohio to Jewish parents, David and Sarah Gofman, who immigrated to the US from the Russian Empire in about 1905. His father had been "involved in some of the early revolutionary activities against the Czar." Gofman died of heart failure at age 88 on August 15, 2007, in his home in San Francisco. | 0 | Theoretical and Fundamental Chemistry |
Genome-wide association studies are general applications to find specific gene targets and polymorphisms within the human race. In fact, the International HapMap project was created through a partnership of scientists and agencies from several countries to catalog and utilize this data. The goal of this project is to compare genetic sequences of different individuals to elucidate similarities and differences within chromosomal regions. Scientists from all of the participating nations are cataloging these attributes with data from populations of African, Asian, and European ancestry. Such genome-wide assessments may lead to further diagnostic and drug therapies while also helping future teams focus on orchestrating therapeutics with genetic features in mind. These concepts are already being exploited in genetic engineering. For example, a research team has actually constructed a PAC shuttle vector that creates a library representing two-fold coverage of the human genome. This could serve as an incredible resource to identify genes, or sets of genes, causing disease. Moreover, these studies can serve as a powerful way to investigate transcriptional regulation as it has been seen in the study of baculoviruses. Overall, advances in genome library construction and DNA sequencing has allowed for efficient discovery of different molecular targets. Assimilation of these features through such efficient methods can hasten the employment of novel drug candidates. | 1 | Applied and Interdisciplinary Chemistry |
Materials in certain cosmetics such as sun cream, moisturizer, and deodorant may have potential benefits from the use of nanochemistry. Manufacturers are working to increase the effectiveness of various cosmetics by facilitating oil nanoemulsion. These particles have extended the boundaries in managing wrinkling, dehydrated, and inelastic skin associated with aging. In sunscreen, titanium dioxide and zinc oxide nanoparticles prove to be effective UV filters but can also penetrate through skin. These chemicals protect the skin against harmful UV light by absorbing or reflecting the light and prevent the skin from retaining full damage by photoexcitation of electrons in the nanoparticle. | 0 | Theoretical and Fundamental Chemistry |
An E1 reaction consists of a unimolecular elimination, where the rate determining step of the mechanism depends on the removal of a single molecular species. This is a two-step mechanism. The more stable the carbocation intermediate is, the faster the reaction will proceed, favoring the products. Stabilization of the carbocation intermediate lowers the activation energy. The reactivity order is (CH3)3C- > (CH3)2CH- > CH3CH2- > CH3-.
Furthermore, studies describe a typical kinetic resolution process that starts out with two enantiomers that are energetically equivalent and, in the end, forms two energy-inequivalent intermediates, referred to as diastereomers. According to Hammond's postulate, the more stable diastereomer is formed faster. | 0 | Theoretical and Fundamental Chemistry |
Fluorescence cross-correlation spectroscopy (FCCS) has several applications in the field of biophysics and biochemistry. Fluorescence cross-correlation spectroscopy (FCCS) is a powerful technique that enables the investigation of interactions between various types of biomolecules, including proteins, nucleic acids, and lipids.
FCCS is one of the few techniques that can provide information about protein-protein interactions at a specific time and location within a living cell. FCCS can be used to study the dynamics of biomolecules in living cells, including their diffusion rates and localization.
This can provide insights into the function and regulation of cellular processes. Unlike fluorescence resonance energy transfer, FCCS does not have a distance limit for interactions making it suitable for probing large complexes. However, FCCS requires active diffusion of the complexes through the microscope focus on a relatively short time scale, typically seconds. FCCS allows for measuring simple molecular stoichiometries and binding constants. | 0 | Theoretical and Fundamental Chemistry |
A boiler feedwater pump is a specific type of pump used to pump feedwater into a steam boiler. The water may be freshly supplied or returning condensate produced as a result of the condensation of the steam produced by the boiler. These pumps are normally high pressure units that take suction from a condensate return system and can be of the centrifugal pump type or positive displacement type. | 1 | Applied and Interdisciplinary Chemistry |
In the hands of Blaise Pascal hydrostatics assumed the dignity of a science, and in a treatise on the equilibrium of liquids (Sur l’équilibre des liqueurs), found among his manuscripts after his death and published in 1663, the laws of the equilibrium of liquids were demonstrated in the most simple manner, and amply confirmed by experiments. | 1 | Applied and Interdisciplinary Chemistry |
The Sir William Dunn Professorship of Biochemistry is the senior professorship in biochemistry at the University of Cambridge. The position was established in 1914 by the trustees of the will of Sir William Dunn, banker, merchant and philanthropist.
The first holder of the chair was Frederick Gowland Hopkins, winner of the 1929 Nobel Prize in Medicine for his work on the discovery of vitamins. | 1 | Applied and Interdisciplinary Chemistry |
The flotation process is also widely used in industrial waste water treatment plants, where it removes fats, oil, grease and suspended solids from waste water. These units are called dissolved air flotation (DAF) units. In particular, dissolved air flotation units are used in removing oil from the wastewater effluents of oil refineries, petrochemical and chemical plants, natural gas processing plants and similar industrial facilities. | 1 | Applied and Interdisciplinary Chemistry |
Human genetic enhancement or human genetic engineering refers to human enhancement by means of a genetic modification. This could be done in order to cure diseases (gene therapy), prevent the possibility of getting a particular disease (similarly to vaccines), to improve athlete performance in sporting events (gene doping), or to change physical appearance, metabolism, and even improve physical capabilities and mental faculties such as memory and intelligence.
These genetic enhancements may or may not be done in such a way that the change is heritable (which has raised concerns within the scientific community). | 1 | Applied and Interdisciplinary Chemistry |
Levomilnacipran has a high oral bioavailability of 92% and a low plasma protein binding of 22%. It is metabolized in the liver by the cytochrome P450 enzyme CYP3A4, thereby making the medication susceptible to grapefruit-drug interactions. The drug has an elimination half-life of approximately 12 hours, allowing for once-daily administration. Levomilnacipran is excreted in urine. | 0 | Theoretical and Fundamental Chemistry |
Calcareous () is an adjective meaning "mostly or partly composed of calcium carbonate", in other words, containing lime or being chalky. The term is used in a wide variety of scientific disciplines. | 0 | Theoretical and Fundamental Chemistry |
Ida Tacke was born in Lackhausen (nowadays a part of the city of Wesel) in the northern Rhine region in 1896. She described how she picked her path of study by stating, "since I did not want to be a teacher at all, and research and industry employed proportionally fewer physicists at that time, I decided to become a chemist– a decision that was welcomed by my father who owned a small varnish factory in the Lower Rhine region." She chose to attend the Technical University of Berlin because she was drawn to its long and demanding programs. She entered the school in 1915, six years after women were allowed to study in all of Berlin's universities. Nine out of the eighty-five members of her class studied chemistry. In 1918, she graduated from the University with a degree in chemical and metallurgical engineering, specifically on higher aliphatic fatty acid anhydrides. She was one of the first women in Germany to study chemistry, and she was a part of one of the first generations of female students in Germany. In addition, the percent of women studying chemistry increased from 3% before World War I to 35% during the war. After graduating, she worked in the chemistry laboratory of the Berlin turbine factory of AEG, which is a company that is affiliated with General Electric in the United States.
The building she worked in, designed by Peter Behrens, was world-famous and resembled a turbine. She met her husband, Walter Noddack, at the Technical University of Berlin while he was working as a researcher. They were married in 1926. Both before and after their marriage they worked as partners, an "Arbeitsgemeinschaft" or "work unit." | 1 | Applied and Interdisciplinary Chemistry |
Alarm signalling varies depending on the receiver's knowledge of a certain threat. Chimpanzees are significantly more likely to produce an alarm call when conspecifics are unaware of a potential threat or were not nearby when a previous alarm call was emitted. When judging if conspecifics are unaware of potential dangers, chimpanzees do not solely look for behavioural cues, but also assess receiver mental states and use this information to target signalling and monitoring. In a recent experiment, caller chimpanzees were shown a fake snake as a predator and were played pre-recorded calls from receivers. Some receivers emitted calls that were snake-related, and therefore represented receivers with knowledge of the predator, while other receivers emitted calls that were not snake-related, and therefore represented receivers without knowledge of the predator. In response to the non-snake-related calls from receivers, the signallers increased their vocal and nonvocal signalling and coupled it with increased receiver monitoring. | 1 | Applied and Interdisciplinary Chemistry |
Dissolved inorganic carbon is a key component of the biological pump, which is defined as the amount of biologically produced organic carbon flux from the upper ocean to the deep ocean. Dissolved inorganic carbon in the form of carbon dioxide is fixed into organic carbon is produced through photosynthesis. Respiration is the reverse process and consumes organic carbon to produce inorganic carbon. Photosynthesis, and the biological pump, is dependent on the availability of inorganic nutrients and carbon dioxide.
:Photosynthesis: 6 CO + 6 HO + light → CHO + 6 O
:Respiration: CHO + 6 O → 6 CO + 6 HO + energy
Oceanographers seek to understand the metabolic state of the ocean, or the efficiency of the biological pump, by estimating the net community production (NCP) which is the gross primary productivity (GPP) minus the community respiration (sum of the respiration of the local autotrophs and heterotrophs). An efficient biological pump increases biological export to the deeper ocean which has been hypothesized to suppress CO outgassing in the upper ocean. | 0 | Theoretical and Fundamental Chemistry |
Plant viruses need to be transmitted by a vector, most often insects such as leafhoppers. One class of viruses, the Rhabdoviridae, has been proposed to actually be insect viruses that have evolved to replicate in plants. The chosen insect vector of a plant virus will often be the determining factor in that virus's host range: it can only infect plants that the insect vector feeds upon. This was shown in part when the old world white fly made it to the United States, where it transferred many plant viruses into new hosts. Depending on the way they are transmitted, plant viruses are classified as non-persistent, semi-persistent and persistent. In non-persistent transmission, viruses become attached to the distal tip of the stylet of the insect and on the next plant it feeds on, it inoculates it with the virus. Semi-persistent viral transmission involves the virus entering the foregut of the insect. Those viruses that manage to pass through the gut into the haemolymph and then to the salivary glands are known as persistent. There are two sub-classes of persistent viruses: propagative and circulative. Propagative viruses are able to replicate in both the plant and the insect (and may have originally been insect viruses), whereas circulative can not. Circulative viruses are protected inside aphids by the chaperone protein symbionin, produced by bacterial symbionts. Many plant viruses encode within their genome polypeptides with domains essential for transmission by insects. In non-persistent and semi-persistent viruses, these domains are in the coat protein and another protein known as the helper component. A bridging hypothesis has been proposed to explain how these proteins aid in insect-mediated viral transmission. The helper component will bind to the specific domain of the coat protein, and then the insect mouthparts – creating a bridge. In persistent propagative viruses, such as tomato spotted wilt virus (TSWV), there is often a lipid coat surrounding the proteins that is not seen in other classes of plant viruses. In the case of TSWV, 2 viral proteins are expressed in this lipid envelope. It has been proposed that the viruses bind via these proteins and are then taken into the insect cell by receptor-mediated endocytosis. | 1 | Applied and Interdisciplinary Chemistry |
The technique has been used to evolve aptamers of extremely high binding affinity to a variety of target ligands, including small molecules such as ATP and adenosine and proteins such as prions and vascular endothelial growth factor (VEGF). Moreover, SELEX has been used to select high-affinity aptamers for complex targets such as tumor cells, tumor exosomes, or tumor tissue. Clinical uses of the technique are suggested by aptamers that bind tumor markers, GFP-related fluorophores, and a VEGF-binding aptamer trade-named Macugen has been approved by the FDA for treatment of macular degeneration. Additionally, SELEX has been utilized to obtain highly specific catalytic DNA or DNAzymes. Several metal-specific DNAzymes have been reported including the GR-5 DNAzyme (lead-specific), the CA1-3 DNAzymes (copper-specific), the 39E DNAzyme (uranyl-specific) and the NaA43 DNAzyme (sodium-specific).
These developed aptamers have seen diverse application in therapies for macular degeneration and various research applications including biosensors, fluorescent labeling of proteins and cells, and selective enzyme inhibition. | 1 | Applied and Interdisciplinary Chemistry |
Metal organic frameworks, porous, three-dimensional coordination polymers, are often derived from metal carboxylate clusters. These clusters, called secondary bonding units (SBU's), are often linked by the conjugate bases of benzenedi- and tricarboxylic acids. | 0 | Theoretical and Fundamental Chemistry |
Chromatin Immuno-Precipitation, or (ChIP), is an alternative method to assay protein binding at specific loci of the genome. Unlike ChIP, DamID does not require a specific antibody against the protein of interest. On the one hand, this allows to map proteins for which no such antibody is available. On the other hand, this makes it impossible to specifically map posttranslationally modified proteins.
Another fundamental difference is that ChIP assays where the protein of interests is at a given time, whereas DamID assays where it has been. The reason is that m6A stays in the DNA after the Dam fusion protein goes away. For proteins that are either bound or unbound on their target sites this does not change the big picture. However, this can lead to strong differences in the case of proteins that slide along the DNA (e.g. RNA polymerase). | 1 | Applied and Interdisciplinary Chemistry |
Reaction intermediates serve purposes in a variety of biological settings. An example of this is demonstrated with the enzyme reaction intermediate of metallo-β-lactamase, which bacteria can use to acquire resistance to commonly used antibiotics such as penicillin. Metallo-β-lactamase can catalyze β-lactams, a family of common antibiotics. Spectroscopy techniques have found that the reaction intermediate of metallo-β-lactamase uses zinc in the resistance pathway.
Another example of the importance of reaction intermediates is seen with AAA-ATPase p97, a protein that used in a variety of cellular metabolic processes. p97 is also linked to degenerative disease and cancer. In a study looking at reaction intermediates of the AAA-ATPase p97 function found an important ADP.P nucleotide intermediate is important in the p97 molecular operation.
An additional example of biologically relevant reaction intermediates can be found with the RCL enzymes, which catalyzes glycosidic bonds. When studied using methanolysis, it was found that the reaction required the formation of a reaction intermediate. | 0 | Theoretical and Fundamental Chemistry |
Although Unruh's prediction that an accelerating detector would see a thermal bath is not controversial, the interpretation of the transitions in the detector in the non-accelerating frame is. It is widely, although not universally, believed that each transition in the detector is accompanied by the emission of a particle, and that this particle will propagate to infinity and be seen as Unruh radiation.
The existence of Unruh radiation is not universally accepted. Smolyaninov claims that it has already been observed, while O'Connell and Ford claim that it is not emitted at all. While these skeptics accept that an accelerating object thermalizes at the Unruh temperature, they do not believe that this leads to the emission of photons, arguing that the emission and absorption rates of the accelerating particle are balanced. | 0 | Theoretical and Fundamental Chemistry |
G protein-coupled receptors (GPCRs), also known as seven-(pass)-transmembrane domain receptors, 7TM receptors, heptahelical receptors, serpentine receptors, and G protein-linked receptors (GPLR), form a large group of evolutionarily related proteins that are cell surface receptors that detect molecules outside the cell and activate cellular responses. They are coupled with G proteins. They pass through the cell membrane seven times in the form of six loops (three extracellular loops interacting with ligand molecules, three intracellular loops interacting with G proteins, an N-terminal extracellular region and a C-terminal intracellular region) of amino acid residues, which is why they are sometimes referred to as seven-transmembrane receptors. Ligands can bind either to the extracellular N-terminus and loops (e.g. glutamate receptors) or to the binding site within transmembrane helices (rhodopsin-like family). They are all activated by agonists, although a spontaneous auto-activation of an empty receptor has also been observed.
G protein-coupled receptors are found only in eukaryotes, including yeast, and choanoflagellates. The ligands that bind and activate these receptors include light-sensitive compounds, odors, pheromones, hormones, and neurotransmitters, and vary in size from small molecules to peptides to large proteins. G protein-coupled receptors are involved in many diseases.
There are two principal signal transduction pathways involving the G protein-coupled receptors:
*the cAMP signal pathway and
*the phosphatidylinositol signal pathway.
When a ligand binds to the GPCR it causes a conformational change in the GPCR, which allows it to act as a guanine nucleotide exchange factor (GEF). The GPCR can then activate an associated G protein by exchanging the GDP bound to the G protein for a GTP. The G protein's α subunit, together with the bound GTP, can then dissociate from the β and γ subunits to further affect intracellular signaling proteins or target functional proteins directly depending on the α subunit type (G, G, G, G).
GPCRs are an important drug target and approximately 34% of all Food and Drug Administration (FDA) approved drugs target 108 members of this family. The global sales volume for these drugs is estimated to be 180 billion US dollars . It is estimated that GPCRs are targets for about 50% of drugs currently on the market, mainly due to their involvement in signaling pathways related to many diseases i.e. mental, metabolic including endocrinological disorders, immunological including viral infections, cardiovascular, inflammatory, senses disorders, and cancer. The long ago discovered association between GPCRs and many endogenous and exogenous substances, resulting in e.g. analgesia, is another dynamically developing field of the pharmaceutical research. | 1 | Applied and Interdisciplinary Chemistry |
If each quark is represented as , with color index taking values 1, 2, 3 corresponding to red, green, and blue, and flavor index taking values 1, 2, 3 corresponding to up, down, and strange, then the color-flavor-locked pattern of Cooper pairing is
This means that a Cooper pair of an up quark and a down quark must have colors red and green, and so on. This pairing pattern is special because it leaves a large unbroken symmetry group. | 0 | Theoretical and Fundamental Chemistry |
The HHRA report was published in May. The Ecological Risk Assessment (ERA) report was published in December and detailed the work done by Golder to understand the ecological significance of the tailings dam breach of 2014. The ERA report was completed as a component of the MPMC's remediation strategy to help inform rehabilitation work in affected areas. The ERA considered levels of metal contaminants in the soil, water, and sediment. Territorial and Aquatic risk assessments were concluded as part of the investigative work of the report. The report found excess concentrations of copper and vanadium in the soil however it was determined that the tailings were not acid generating and were unlikely to leach metals. The ERA determined the cause of some tree death post-breach and attributed a root smothering effect of the tailings effluent in the forested region. It was determined that tailings decreased soil aeration causing a poor environment for soil biota to support tree growth and survival. The food chain of local wildlife was modeled to determine if copper and vanadium exceeded standards. The cumulative dose according to these models was determined to be below a conservative threshold for most wildlife species. The report concluded low risk associated with copper and vanadium contamination. The bioavailability of the metals was likewise determined to be low. As part of the aquatic risk assessment, copper and arsenic were investigated in the sediment, while copper was the contaminant of potential concern investigated in the water of Polley Lake, Hazeltine Creek, Quesnel Lake, and Quesnel River. It was determined that copper levels decreased below the accepted guideline through 2015 in both lakes and Quesnel River, but not in Hazeltine Creek which was the site of active remediation and restructuring. The plants, water-column invertebrates, and fish in Polley Lake and Quesnel Lake are not expected to face long-term effects of the 2014 breach, according to ERA report. Likewise, risk to fish-consuming wildlife was also determined to be low. The deep ecological benthic ecosystem was also considered to have little risk from copper as a limiting factor in the recovery of these organisms at the sediment layer. The ERA concluded that ecological risks associated with metals released by the dam breach and tailings spill are low. | 1 | Applied and Interdisciplinary Chemistry |
Initial studies on carboxypeptidases focused on pancreatic carboxypeptidases A1, A2, and B in the digestion of food. Most carboxypeptidases are not, however, involved in catabolism. Instead they help to mature proteins, for example Post-translational modification. They also regulate biological processes, such as the biosynthesis of neuroendocrine peptides such as insulin requires a carboxypeptidase. Carboxypeptidases also function in blood clotting, growth factor production, wound healing, reproduction, and many other processes. | 1 | Applied and Interdisciplinary Chemistry |
The high-frequency impact treatment or HiFIT – Method is the treatment of welded steel constructions at the weld transition to increase the fatigue strength. | 1 | Applied and Interdisciplinary Chemistry |
Lanthanum oxide can crystallize in at least three polymorphs.
Hexagonal has been produced by spray pyrolysis of lanthanum chloride.
An alternative route to obtaining hexagonal involves precipitation of nominal from aqueous solution using a combination of 2.5% and the surfactant sodium dodecyl sulfate followed by heating and stirring for 24 hours at 80 °C:
Other routes include: | 0 | Theoretical and Fundamental Chemistry |
The enamine is generally generated in situ from catalytic amine (such as pyrrolidine) and a ketone. The enamine then reacts as the dienophile with a 1,2,4-triazine. The initial adduct then expels nitrogen, and the pyridine is rearomatized with loss of the amine. | 0 | Theoretical and Fundamental Chemistry |
Alain Viel is the director of Northwest Undergraduate Laboratories and senior lecturer in the Department of Molecular and Cellular Biology at Harvard University. | 1 | Applied and Interdisciplinary Chemistry |
During thin film growth, there can be a balance between surface energy and internal strain, with surface stress a coupling term combining the two. Instead of growing as a continuous thin film, a morphological instability can occur and the film can start to become very uneven, in many cases due to a breakdown of a balance between elastic and surface energies. The surface stress can lead to comparable wrinkling in nanowires, and also a morphological instability in a thin film. | 0 | Theoretical and Fundamental Chemistry |
A homogeneous method for screening yoctoreactor libraries (yR) has recently been developed which uses water-in-oil emulsion technology to isolate individual ligand-target complexes. Called Binder Trap Enrichment (BTE), ligands to a protein target are identified by trapping binding pairs (DNA-labelled protein target and yR ligand) in emulsion droplets during dissociation dominated kinetics. Once trapped, the target and ligand DNA are joined by ligation, thus preserving the binding information.
Hereafter, identification of hits is essentially a counting exercise: information on binding events is deciphered by sequencing and counting the joined DNA - selective binders are counted with a much higher frequency than random binders. This is possible because random trapping of target and ligand is "diluted" by the high number of water droplets in the emulsion. The low noise and background signal characteristic of BTE is attributed to the "dilution" of the random signal, the lack of surface artifacts and the high fidelity of the yR library and screening method. Screening is performed in a single tube method. Biologically active hits are identified in a single round of BTE characterized by a low false positive rate.
BTE mimics the non-equilibrium nature of in vivo ligand-target interactions and offers the unique possibility to screen for target specific ligands based on ligand-target residence time because the emulsion, which traps the binding complex, is formed during a dynamic dissociation phase. | 1 | Applied and Interdisciplinary Chemistry |
In genetics, an expressed sequence tag (EST) is a short sub-sequence of a cDNA sequence. ESTs may be used to identify gene transcripts, and were instrumental in gene discovery and in gene-sequence determination. The identification of ESTs has proceeded rapidly, with approximately 74.2 million ESTs now available in public databases (e.g. GenBank 1 January 2013, all species). EST approaches have largely been superseded by whole genome and transcriptome sequencing and metagenome sequencing.
An EST results from one-shot sequencing of a cloned cDNA. The cDNAs used for EST generation are typically individual clones from a cDNA library. The resulting sequence is a relatively low-quality fragment whose length is limited by current technology to approximately 500 to 800 nucleotides. Because these clones consist of DNA that is complementary to mRNA, the ESTs represent portions of expressed genes. They may be represented in databases as either cDNA/mRNA sequence or as the reverse complement of the mRNA, the template strand.
One can map ESTs to specific chromosome locations using physical mapping techniques, such as radiation hybrid mapping, HAPPY mapping, or FISH. Alternatively, if the genome of the organism that originated the EST has been sequenced, one can align the EST sequence to that genome using a computer.
The current understanding of the human set of genes () includes the existence of thousands of genes based solely on EST evidence. In this respect, ESTs have become a tool to refine the predicted transcripts for those genes, which leads to the prediction of their protein products and ultimately of their function. Moreover, the situation in which those ESTs are obtained (tissue, organ, disease state - e.g. cancer) gives information on the conditions in which the corresponding gene is acting. ESTs contain enough information to permit the design of precise probes for DNA microarrays that then can be used to determine gene expression profiles.
Some authors use the term "EST" to describe genes for which little or no further information exists besides the tag. | 1 | Applied and Interdisciplinary Chemistry |
The three principal phosphate producer countries (China, Morocco and the United States) account for about 70% of world production. | 0 | Theoretical and Fundamental Chemistry |
Phosphinooxazolines (often abbreviated PHOX) are a class of chiral ligands used in asymmetric catalysis. Their complexes are particularly effective at generating single enatiomers in reactions involving highly symmetric transition states, such as allylic substitutions, which are typically difficult to perform stereoselectively. The ligands are bidentate and have been shown to be hemilabile
with the softer P‑donor being more firmly bound than the harder N‑donor. | 0 | Theoretical and Fundamental Chemistry |
Nitric oxide can also serve as a bridging ligand. In the compound [Mn(ηCH) (μ-NO) (μ-NO)], three NO groups bridge two metal centres and one NO group bridge to all three. | 0 | Theoretical and Fundamental Chemistry |
Using the MagPen (a Nano3D Biosciences, Inc. product), organized 3D co-cultures similar to native tissue architecture can be rapidly created. Endothelial cells (PEC), smooth muscle cells (SMC), fibroblasts (PF), and epithelial cells (EpiC) cultured with the Bio-Assembler can be sequentially layered in a drag-and-drop manner to create bronchioles that maintain phenotype and induce extracellular matrix formation. | 0 | Theoretical and Fundamental Chemistry |
Cellular biomarkers allow cells to be isolated, sorted, quantified and characterized by their morphology and physiology. Cellular biomarkers are used in both clinical and laboratory settings, and can discriminate between a large sample of cells based on their antigens. An example of a cellular biomarker sorting technique is Fluorescent-activated cell sorting. | 1 | Applied and Interdisciplinary Chemistry |
In natural photosynthesis, photosynthetic organisms produce energy-rich organic molecules from water and carbon dioxide by using solar radiation. Therefore, the process of photosynthesis removes carbon dioxide, a greenhouse gas, from the air. Artificial photosynthesis, as performed by the Bionic Leaf, is approximately 10 times more efficient than natural photosynthesis. Using a catalyst, the Bionic Leaf can remove excess carbon dioxide in the air and convert that to useful alcohol fuels, like isopropanol and isobutanol.
The efficiency of the Bionic Leafs artificial photosynthesis is the result of bypassing obstacles in natural photosynthesis by virtue of its artificiality. In natural systems, there are numerous energy conversion bottlenecks that limit the overall efficiency of photosynthesis. As a result, most plants do not exceed 1% efficiency and even microalgae grown in bioreactors do not exceed 3%. Existing artificial photosynthetic solar-to-fuels cycles may exceed natural efficiencies but cannot complete the cycle via carbon fixation. When the catalysts of the Bionic Leaf are coupled with the bacterium Ralstonia eutropha', this results in a hybrid system capable of carbon dioxide fixation. This system can store more than half of its input energy as products of carbon dioxide fixation. Overall, the hybrid design allows for artificial photosynthesis with efficiencies rivaling that of natural photosynthesis. | 0 | Theoretical and Fundamental Chemistry |
Atmospheric chemistry is a branch of atmospheric science in which the chemistry of the Earth's atmosphere and that of other planets is studied. It is a multidisciplinary field of research and draws on environmental chemistry, physics, meteorology, computer modeling, oceanography, geology and volcanology and other disciplines. Research is increasingly connected with other areas of study such as climatology.
The composition and chemistry of the atmosphere is of importance for several reasons, but primarily because of the interactions between the atmosphere and living organisms. The composition of the Earth's atmosphere has been changed by human activity and some of these changes are harmful to human health, crops and ecosystems. Examples of problems which have been addressed by atmospheric chemistry include acid rain, photochemical smog and global warming. Atmospheric chemistry seeks to understand the causes of these problems, and by obtaining a theoretical understanding of them, allow possible solutions to be tested and the effects of changes in government policy evaluated. | 1 | Applied and Interdisciplinary Chemistry |
Sedimentation field flow fractionation (SFFF) is a non-destructive separation technique which can be used for both separation, and collecting fractions. Some applications of SFFF include characterization of particle size of latex materials for adhesives, coatings and paints, colloidal silica for binders, coatings and compounding agents, titanium oxide pigments for paints, paper and textiles, emulsion for soft drinks, and biological materials like viruses and liposomes.
Some main aspects of SFFF include: it provides high-resolution possibilities for size distribution measurements with high precision, the resolution is dependent on experimental conditions, the typical analysis time is 1 to 2 hours, and it is a non-destructive technique which offers the possibility of collecting fraction. | 0 | Theoretical and Fundamental Chemistry |
CREB-regulated transcription coactivator 1 (CRTC1), previously referred to as TORC1 (), is a protein that in humans is encoded by the CRTC1 gene. It is expressed in a limited number of tissues that include fetal brain and liver and adult heart, skeletal muscles, liver and salivary glands and various regions of the adult central nervous system. | 1 | Applied and Interdisciplinary Chemistry |
Decantation can also separate solid and liquid mixtures by allowing gravity to pull the solid fragments to settle at the bottom of the container. In laboratory situations, decantation of mixtures containing solids and liquids occur in test tubes. To enhance productivity, test tubes should be placed at a 45° angle to allow sediments to settle at the bottom of the apparatus.
A centrifuge machine may also be used in decantation as the natural process of settling down is time-consuming and tedious. A centrifuge forces the precipitate to the bottom of the container; if the force is high enough, solids can aggregate to form pellets, making it easier to separate the mixtures. Then the liquid can be more easily poured away, as the precipitate will tend to remain in its compressed form.
A decanter centrifuge may be used for continuous solid-liquid separation. | 0 | Theoretical and Fundamental Chemistry |
From the second equation described above, it follows that when , . More precisely, as , that equation can be approximated as
As , and if decreases as . The left hand side of the above equation can become positive infinity only if . Thus, when decreases to the value , the gas comes to rest (Here is the sound speed corresponding to ). Thus, the rarefaction motion occurs for and there is no fluid motion for . | 1 | Applied and Interdisciplinary Chemistry |
For the case of counterpropagating waves with orthogonal circular polarizations the resulting polarization is linear everywhere, but rotates about at an angle . As a result, there is no Sisyphus effect. The rotating polarization instead leads to motion-induced population imbalances in the Zeeman levels that cause imbalances in radiation pressure leading to a damping of the atomic motion. These population imbalances are only present for states with or higher.
Consider two EM waves detuned from an atomic transition with equal amplitudes: and . The superposition of these two waves is:
As previously stated, the polarization of the total field is linear, but rotated around by an angle with respect to .
Consider an atom moving along z with some velocity v. The atom sees the polarization rotating with a frequency of . In the rotating frame, the polarization is fixed, however, there is an inertial field due to the frame rotating. This inertial term appears in the Hamiltonian as follows.
Here we see the inertial term looks like a magnetic field along with an amplitude such that the Larmor precession frequency is equal to rotation frequency in the lab frame. For small v, this term in Hamiltonian can be treated using perturbation theory.
Choosing the polarization in the rotating frame to be fixed along , the unperturbed atomic eigenstates are the eigenstates of . The rotating term in the Hamiltonian causes perturbations in the atomic eigenstates such that the Zeeman sublevels become contaminated by each other. For the is light shifted more than the states. Thus the steady state population of the is higher than that of the other states. The populations are equal for the states. Thus states are balanced with . However, when we change basis we see that populations are not balanced in the z-basis and there is a non-zero value of proportional to the atom's velocity:
Where is the light shift for the state. There is a motion induced population imbalance in the Zeeman sublevels in the z basis. For red detuned light, is negative, and thus there will be a higher population in the state when the atom is moving to the right (positive velocity) and a higher population in the state when the atom is moving to the left (negative velocity). From the Clebsch-Gordan coefficients, we see that the state has a six times greater probability of absorbing a photon moving to the left than a photon moving to the right. The opposite is true for the state. When the atom moves to the right it is more likely to absorb a photon moving to the left and likewise when the atom moves to the left it is more likely to absorb a photon moving to the right. Thus there is an unbalanced radiation pressure when the atom moves which dampens the motion of the atom, lowering its velocity and therefore its temperature.
Note the similarity to Doppler cooling in the unbalanced radiation pressures due to the atomic motion. The unbalanced pressure in PG cooling is not due to a Doppler shift but an induced population imbalance. Doppler cooling depends on the parameter where is the scattering rate, whereas PG cooling depends on . At low intensity and thus PG cooling works at lower atomic velocities (temperatures) than Doppler Cooling. | 0 | Theoretical and Fundamental Chemistry |
After two years of post-doctoral research with Merle Battiste at the University of Florida, where he worked on small ring chemistry, Halton was appointed as a faculty member in the Department of Chemistry at Victoria University of Wellington in 1968, eventually rising to become a full professor. When he retired in 2004, he was conferred the title of professor emeritus.
Haltons research was centred on the synthesis and investigation of highly strained and fused aromatic compounds and their unstable cyclopropanated derivatives, known as cycloproparenes, which included highly strained didehydrobenzenes and some exceptionally fluorescent compounds. in 1987, Halton was conferred with the degree of Doctor of Science by Victoria University of Wellington, on the basis of his submission of 57 papers, collectively titled Studies of some strained organic molecules', published between 1971 and 1987.
Halton was active in the New Zealand Institute of Chemistry (NZIC), serving as chair of the Wellington branch, editor of Chemistry in New Zealand between 2002 and 2012, and president of the NZIC from 1986 to 1987. He represented New Zealand on the organising committee of Pacifichem, the international chemical congress of Pacific basin societies, for 18 years. | 0 | Theoretical and Fundamental Chemistry |
DPP-4 is attached to the plasma membrane of the endothelium of almost every organ in the body. Tissues which strongly express DPP-4 include the exocrine pancreas, sweat glands, salivary and mammary glands, thymus, lymph nodes, biliary tract, kidney, liver, placenta, uterus, prostate, skin, and the capillary bed of the gut mucosa (where most GLP-1 is inactivated locally). It is also present, in soluble form, in body fluids, such as blood plasma and cerebrospinal fluid. (It also happens that DPP-4 is the CD26 T-cell activating antigen.)
DPP-4 selectively cleaves two amino acids from peptides, such as GLP-1 and GIP, which have proline or alanine in the second position (Figure 2). At the active site where DPP-4 has its effect, there is a characteristic arrangement of three amino acids, Asp-His-Ser. Since alanine and proline are crucial for the biological activity of GPL-1 and GIP, they are inactivated by cleaving away these amino acids. Thus, preventing the degradation of the incretin hormones GLP-1 and GIP by inhibition of DPP-4 has potential as a therapeutic strategy in the treatment of type 2 diabetes. | 1 | Applied and Interdisciplinary Chemistry |
Melzer's reagent can be used to test whether spores are amyloid, nonamyloid, or dextrinoid.
* Spores that stain bluish-gray to bluish-black are amyloid
* Spores that stain brown to reddish-brown are dextrinoid
This test is normally performed on white spored mushrooms. If the spores are not light colored, a change will not be readily apparent. It is easiest to see the color change under a microscope, but it is possible to see it with the naked eye with a good spore print. | 0 | Theoretical and Fundamental Chemistry |
Early work in the development of liquid-liquid separation techniques was undertaken by Cornish et al. with a process called "systematic fractional distribution" as well as Randall and Longtin, however, the central figure is certainly Lyman C. Craig. Lyman Craigs development of countercurrent distribution began with studying the distribution of a pharmaceutical, mepacrine (atabrine), between the two layers of an ethylene dichloride, methanol, and aqueous buffer biphasic solvent system. The distribution coefficient (K which coincides with partition coefficient) of atabrine varied by the composition of the solvent system and the pH of the buffer. In the next article, Craig was inspired by the work of Martin and Synge with partition chromatography to develop an apparatus that would separate compounds based on their distribution constant (K which coincides with partition coefficient). It was shown that a solvent system composed of benzene, n'-hexane, methanol and water would separate mixtures of organic acids. It is remarkable that the mathematical theory developed hand-in-hand with the progression of applications. Craig continued to pursue this method of separation by testing different compounds, formulating biphasic solvent systems, and most importantly developing a commercially viable instrument.
The CCD technique was employed in many notable separations such as penicillin, polycyclic aromatic hydrocarbons, insulin, bile acids, ribonucleic acids, taxol, Streptomyces antibiotics. and many other antibiotics. | 0 | Theoretical and Fundamental Chemistry |
For a Van der Waals gas, the coefficient iswith inversion temperature .
For the Dieterici gas, the reduced inversion temperature is , and the relation between reduced pressure and reduced inversion temperature is . This is plotted on the right. The critical point falls inside the region where the gas cools on expansion. The outside region is where the gas warms on expansion. | 0 | Theoretical and Fundamental Chemistry |
The Laporte rule is a selection rule formally stated as follows: In a centrosymmetric environment, transitions between like atomic orbitals such as s-s, p-p, d-d, or f-f, transitions are forbidden. The Laporte rule (law) applies to electric dipole transitions, so the operator has u symmetry (meaning ungerade, odd). p orbitals also have u symmetry, so the symmetry of the transition moment function is given by the triple product u×u×u, which has u symmetry. The transitions are therefore forbidden. Likewise, d orbitals have g symmetry (meaning gerade, even), so the triple product g×u×g also has u symmetry and the transition is forbidden.
The wave function of a single electron is the product of a space-dependent wave function and a spin wave function. Spin is directional and can be said to have odd parity. It follows that transitions in which the spin "direction" changes are forbidden. In formal terms, only states with the same total spin quantum number are "spin-allowed". In crystal field theory, d-d transitions that are spin-forbidden are much weaker than spin-allowed transitions. Both can be observed, in spite of the Laporte rule, because the actual transitions are coupled to vibrations that are anti-symmetric and have the same symmetry as the dipole moment operator. | 0 | Theoretical and Fundamental Chemistry |
Photofermentation is the fermentative conversion of organic substrate to biohydrogen manifested by a diverse group of photosynthetic bacteria by a series of biochemical reactions involving three steps similar to anaerobic conversion. Photofermentation differs from dark fermentation because it only proceeds in the presence of light.
For example, photo-fermentation with Rhodobacter sphaeroides SH2C (or many other purple non-sulfur bacteria) can be employed to convert small molecular fatty acids into hydrogen and other products. | 1 | Applied and Interdisciplinary Chemistry |
In analytical chemistry, biomonitoring is the measurement of the body burden of toxic chemical compounds, elements, or their metabolites, in biological substances. Often, these measurements are done in blood and urine. Biomonitoring is performed in both environmental health, and in occupational safety and health as a means of exposure assessment and workplace health surveillance.
The two best established environmental biomonitoring programs in representative samples of the general population are those of the United States and Germany, although population-based programs exist in a few other countries. In 2001, the U.S. Centers for Disease Control and Prevention (CDC) began to publish its biennial National Report on Human Exposure to Environmental Chemicals, which reports a statistically representative sample of the U.S. population. | 1 | Applied and Interdisciplinary Chemistry |
Stable nuclides are nuclides that are not radioactive and so (unlike radionuclides) do not spontaneously undergo radioactive decay. When such nuclides are referred to in relation to specific elements, they are usually termed stable isotopes.
The 80 elements with one or more stable isotopes comprise a total of 251 nuclides that have not been known to decay using current equipment (see list at the end of this article). Of these 80 elements, 26 have only one stable isotope; they are thus termed monoisotopic. The rest have more than one stable isotope. Tin has ten stable isotopes, the largest number of stable isotopes known for an element. | 0 | Theoretical and Fundamental Chemistry |
The thermodynamic square is mostly used to compute the derivative of any thermodynamic potential of interest. Suppose for example one desires to compute the derivative of the internal energy . The following procedure should be considered:
# Place oneself in the thermodynamic potential of interest, namely (, , , ). In our example, that would be .
# The two opposite corners of the potential of interest represent the coefficients of the overall result. If the coefficient lies on the left hand side of the square, a negative sign should be added. In our example, an intermediate result would be .
# In the opposite corner of each coefficient, you will find the associated differential. In our example, the opposite corner to would be (volume) and the opposite corner for would be (entropy). In our example, an interim result would be: . Notice that the sign convention will affect only the coefficients, not the differentials.
# Finally, always add , where denotes the chemical potential. Therefore, we would have: .
The Gibbs–Duhem equation can be derived by using this technique. Notice though that the final addition of the differential of the chemical potential has to be generalized. | 0 | Theoretical and Fundamental Chemistry |
Alkali metal nitrates are relatively low melting and thermally stable. The least stable, lithium nitrate| (m.p. 255 °C) decomposes only at 474 °C. At the other extreme, cesium nitrate melts at 414 °C and decomposes at 584 °C.
*60:40 mixture of sodium nitrate and potassium nitrate is a liquid between 260-550 °C. It has a heat of fusion of 161 J/g, and a heat capacity of 1.53 J/(g·K).
*1:1 mixture :, m.p. 125 °C.
*40:7:53 ::, m. p. 142 °C, stable to 600 °C. | 1 | Applied and Interdisciplinary Chemistry |
In 2014 and 2016 the Department of Biochemistry and Molecular Biology, Yonsei University College of Medicine, hosted academic symposiums to commemorate his life's work.
A Special Memorial Exhibition was also held in 2015 at the Dong-Eun Museum of Medical Science in Seoul, Korea. The exhibit included a collection of papers left by the late Suksin Lee. | 1 | Applied and Interdisciplinary Chemistry |
Ptaquiloside has unstable chemical structure and readily undergoes glucose liberation. The resulting ptaquilodienone is the active form of ptaquiloside and accounts for the observed biological effects. The cyclopropyl group in the dienone is highly reactive as an electrophile, not only because it is conjugated with the keto group, but because it also constitutes a cyclopropyl carbinol system, from which the facile formation of the stable non-classical cation is well-known. | 0 | Theoretical and Fundamental Chemistry |
High-performance thin-layer chromatography (HPTLC) serves as an extension of thin-layer chromatography (TLC), offering robustness, simplicity, speed, and efficiency in the quantitative analysis of compounds. This TLC-based analytical technique enhances compound resolution for quantitative analysis. Some of these improvements involve employing higher-quality TLC plates with finer particle sizes in the stationary phase, leading to improved resolution. Additionally, the separation can be further refined through repeated plate development using a multiple development device. As a result, HPTLC provides superior resolution and lower Limit of Detection (LODs). | 0 | Theoretical and Fundamental Chemistry |
Group-specific CSIs are commonly shared by different species belonging to a particular taxon (e.g. genus, family, class, order, phylum) but they are not present in other groups. These CSIs were most likely introduced in an ancestor of the group of species before the members of the taxa diverged. They provide molecular means for distinguishing members of a particular taxon from all other organisms.
Figure 1 shows an example of 5aa CSI found in all species belonging to the taxon X. This is a distinctive characteristic of this taxon as it is not found in any other species. This signature was likely introduced in a common ancestor of the species from this taxon. Similarly other group-specific signatures (not shown) could be shared by either A1 and A2 or B1 and B2, etc., or even by X1 and X2 or by X3 and X4, etc. The groups A, B, C, D and X, in this diagram could correspond to various bacterial or Eukaryotic phyla.
Group-specific CSIs have been used in the past to determine the phylogenetic relationship of a number of bacterial phyla and subgroups within it. For example a 3 amino acid insert was uniquely shared by members of the phylum Thermotogota (formerly Thermotogae) in the essential 50S ribosomal protein L7/L12, within a highly conserved region (82-124 amino acid). This is not present in any other bacteria species and could be used to characterize members of Thermotogota from all other bacteria. Group-specific CSIs were also used to characterize subgroups within Thermotogota. | 1 | Applied and Interdisciplinary Chemistry |
Companion plants that produce copious nectar or pollen in a vegetable garden (insectary plants) may help encourage higher populations of beneficial insects that control pests.
Some companion herbs that produce aromatic volatiles attract natural enemies, which can help to suppress pests. Mint, basil, and marigold all attract herbivorous insects enemies, such as generalist predators. For instance, spearmint attracts the mirid bug Nesidiocoris tenuis, while basil attracts the green lacewing Ceraeochrysa cubana'.
The multiple interactions between the plant species, and between them, pest species, and the pests natural enemies, are complex and not well understood. A 2019 field study in Brazil found that companion planting with parsley among a target crop of collard greens helped to suppress aphid pests (Brevicoryne brassicae, Myzus persicae'), even though it also cut down the numbers of parasitoid wasps. Predatory insect species increased in numbers, and may have predated on the aphid-killing parasitoids, while the reduction in aphids may have been caused by the increased numbers of generalist predators. | 1 | Applied and Interdisciplinary Chemistry |
* Orbifold signature:
* Coxeter notation: [4,4]
* Lattice: square
* Point group: D
* The group p4g has two centres of rotation of order four (90°), which are each other's mirror image, but it has reflections in only two directions, which are perpendicular. There are rotations of order two (180°) whose centres are located at the intersections of reflection axes. It has glide reflections axes parallel to the reflection axes, in between them, and also at an angle of 45° with these.
A p4g pattern can be looked upon as a checkerboard pattern of copies of a square tile with 4-fold rotational symmetry, and its mirror image. Alternatively it can be looked upon (by shifting half a tile) as a checkerboard pattern of copies of a horizontally and vertically symmetric tile and its 90° rotated version. Note that neither applies for a plain checkerboard pattern of black and white tiles, this is group p4m (with diagonal translation cells).
;Examples of group p4g | 0 | Theoretical and Fundamental Chemistry |
The bowl and stand were favourite archaic forms. The Greek stand was a fusion of the cast-rod tripod and the embossed cone. Some early examples have large triangular plates between the legs, worked in relief; but the developed type has separate legs and stays of which the joints are masked with decorative rims and feet and covering-plates. These ornaments are cast and chased, and are modelled in floral, animal and human forms. The feet are lions' paws, which sometimes clasp a ball or stands on toads; the rims and plaques bear groups of fighting animals, warriors, revelles or athletes, nymphs and satyrs, or mythological subjects in relief. Feasters recline and horsemen gallop on the rims of bowls; handles are formed by single standing figures, arched pairs of wrestlers, lovers holding hands, or two vertical soldiers carrying a horizontal comrade. Nude athletes serve as handles for all kinds of lids and vessels, draped women support mirror-disks around which love-gods fly, and similar figures crown tall shafts of candelabra. Handle-bases are modelled as satyr-masks, palmettes and sphinxes. This is Greek ornament of the 6th and later centuries. Its centres of manufacture are not precisely known, but the style of much archaic work points to Ionia.
Etruscan fabrics approach their Greek originals so closely that it is not possible to separate them in technique or design, and the Etruscan style is no more than provincial Greek. Bronze was quite plentiful in Italy, the earliest Roman coinage was of heavy bronze, and there is literary evidence that Etruscan bronzes were exported. The process of line engraving seems to have been a Latin speciality; it was applied in pictorial subjects on the backs of mirrors and on the sides large cylindrical boxes, both of which are particularly connected with Praeneste. The finest of all such boxes, the Firconi cista in the Villa Giulia at Rome, bears the signature of a Roman artist. These belong to the 4th and 3rd centuries BC. Greek mirrors of the same period are seldom engraved; the disk is usually contained in a flat box which has a repoussé design on its lid. | 1 | Applied and Interdisciplinary Chemistry |
# Somatic cell fusion appears to be the only means through which two different parental genomes can be recombined among plants that cannot reproduce sexually (asexual or sterile).
# Protoplasts of sexually sterile (haploid, triploid, and aneuploid) plants can be fused to produce fertile diploids and polyploids.
# Somatic cell fusion overcomes sexual incompatibility barriers. In some cases somatic hybrids between two incompatible plants have also found application in industry or agriculture.
# Somatic cell fusion is useful in the study of cytoplasmic genes and their activities and this information can be applied in plant breeding experiments. | 1 | Applied and Interdisciplinary Chemistry |
Electric arc is a continuous electric discharge between two electrodes, similar to lightning.
With ample current density, the discharge forms a luminous arc, where the inter-electrode material (usually, a gas) undergoes various stages — saturation, breakdown, glow, transition, and thermal arc. The voltage rises to its maximum in the saturation stage, and thereafter it undergoes fluctuations of the various stages, while the current progressively increases throughout. Electrical resistance along the arc creates heat, which dissociates more gas molecules and ionizes the resulting atoms. Therefore, the electrical energy is given to electrons, which, due to their great mobility and large numbers, are able to disperse it rapidly by elastic collisions to the heavy particles. | 0 | Theoretical and Fundamental Chemistry |
As with any functional group, the hazards of halohydrins are difficult to generalize as they may form part of an almost limitless series of compounds, with each structure having different pharmacology. In general, simpler low molecular weight compounds are often toxic and carcinogenic (e.g. 2-chloroethanol, 3-MCPD) by virtue of being alkylating agents. This reactivity can be put to good use, for instance in the anti-cancer drug mitobronitol. A number of synthetic corticosteroids exist bearing a fluorohydrin motif (triamcinolone, dexamethasone). | 0 | Theoretical and Fundamental Chemistry |
In their reactions with metal complexes, diazonium cations behave similarly to . For example, low-valent metal complexes add with diazonium salts. Illustrative complexes are and the chiral-at-metal complex . | 0 | Theoretical and Fundamental Chemistry |
He is a member of American Academy of Arts and Sciences, National Academy of Sciences, American Philosophical Society, European Molecular Biology Organization, American Crystallographic Association and American Association for the Advancement of Science. | 1 | Applied and Interdisciplinary Chemistry |
The electronic transitions in organic compounds and some other compounds can be determined by ultraviolet–visible spectroscopy, provided that transitions in the ultraviolet (UV) or visible range of the electromagnetic spectrum exist for the compound. Electrons occupying a HOMO (highest-occupied molecular orbital) of a sigma bond (σ) can get excited to the LUMO (lowest-unoccupied molecular orbital) of that bond. This process is denoted as a transition. Likewise, promotion of an electron from a pi-bonding orbital (π) to an antibonding pi orbital (π*) is denoted as a transition. Auxochromes with free electron pairs (denoted as "n") have their own transitions, as do aromatic pi bond transitions. Sections of molecules which can undergo such detectable electron transitions can be referred to as chromophores, since such transitions absorb electromagnetic radiation (light), which may be hypothetically perceived as color somewhere in the electromagnetic spectrum. The following molecular electronic transitions exist:
In addition to these assignments, electronic transitions also have so-called bands associated with them. The following bands are defined (by A. Burawoy in 1930):
*The R-band ();
*The K-band ();
*The B-band (from benzoic);
*The E-band (from ethylenic).
For example, the absorption spectrum for ethane shows a transition at 135 nm and that of water a transition at 167 nm with an extinction coefficient of 7,000. Benzene has three transitions; two E-bands at 180 and 200 nm and one B-band at 255 nm with extinction coefficients respectively 60,000, 8,000 and 215. These absorptions are not narrow bands but are generally broad because the electronic transitions are superimposed on the other molecular energy states. | 0 | Theoretical and Fundamental Chemistry |
In biology, the word gene (, ; generation, or birth, or gender) has two meanings. The Mendelian gene is a basic unit of heredity. The molecular gene is a sequence of nucleotides in DNA, that is transcribed to produce a functional RNA. There are two types of molecular genes: protein-coding genes and non-coding genes.
During gene expression, DNA is first copied into RNA. RNA can be directly functional or be the intermediate template for the synthesis of a protein.
The transmission of genes to an organism's offspring, is the basis of the inheritance of phenotypic traits from one generation to the next. These genes make up different DNA sequences, together called a genotype, that is specific to every given individual, within the genepool of a population of a given species. The genotype, along with environmental and developmental factors, ultimately determines the phenotype of the individual. Most biological traits occur under the combined influence of polygenes (a set of different genes) and gene–environment interactions. Some genetic traits are instantly visible, such as eye color or the number of limbs, others are not, such as blood type, the risk for specific diseases, or the thousands of basic biochemical processes that constitute life.
A gene can acquire mutations in its sequence, leading to different variants, known as alleles, in the population. These alleles encode slightly different versions of a gene, which may cause different phenotypical traits. Genes evolve due to natural selection / survival of the fittest and genetic drift of the alleles.
The term gene was introduced by Danish botanist, plant physiologist and geneticist Wilhelm Johannsen in 1909. It is inspired by the Ancient Greek: γόνος, gonos, that means offspring and procreation. | 1 | Applied and Interdisciplinary Chemistry |
Steric effects play a major role in the assignment of configurations in cyclohexanes. One can use steric hindrances to determine the propensity of a substituent to reside in the axial or equatorial plane. It is known that axial bonds are more hindered than the corresponding equatorial bonds. This is because substituents in the axial position are relatively close to two other axial substituents. This makes it very crowded when bulky substituents are oriented in the axial position. These types of steric interactions are commonly known as 1,3 diaxial interactions. These types of interactions are not present with substituents at the equatorial position.
There are generally considered three principle contributions to the conformational free energy:
# Baeyer strain, defined as the strain arising from deformation of bond angles.
# Pitzer strain, defined as the torsional strain arising from 1,2 interactions between groups attached to contiguous carbons,
# Van der Waals interactions, which are similar to 1,3 diaxial interactions. | 0 | Theoretical and Fundamental Chemistry |
The Hyper-IL-6 protein has also been used to explore the physiologic role of Interleukin-6 trans-signaling in vivo. It turned out that this signaling mode was involved in many types of inflammation and cancer.
Hyper-IL-6 has helped to establish the concept of Interleukin-6 trans-signaling. Interleukin-6 trans-signaling mediates the pro-inflammatory activities of Interleukin-6 whereas Interleukin-6 classic signaling governs the protective and regenerative Interleukin-6 activities. Recently, in breast cancer patients, it was shown with the help of Hyper-IL-6 that IL-6 trans-signaling via phosphoinositid-3-kinase signaling activates disseminated cancer cells long before metastases are formed. In addition, it was demonstrated in mice that Hyper-IL-6 transneuronal delivery enabled functional recovery after severe spinal cord injury. | 1 | Applied and Interdisciplinary Chemistry |
Poroma is a benign, relatively common skin tumor that has the cellular features similar to those of a sweat gland duct. This tumor typically occurs as a solitary stalkless nodule on the soles and palms but may occur in any area where there are sweat glands. Porocarcinoma (also termed eccrine porocarcinoma and malignant eccrine poroma) is an extremely rare malignant counterpart of poromas. It may arise from a longstanding poroma but more commonly appears to develop independently of any precursor poroma. Porocarcinoma tumors predominantly afflict elderly individuals. A study of 104 poroma tumors detected the YAP1-NUTM1 and WWTR1-NUTM1 fusion genes in 21 cases and 1 case, respectively, while the same study of 11 porocarcinoma tumors detected the YAP1-NUTM1 fusion gene in 6 cases. Expression of the NUTM1 (fusion) protein was observed in 25 poroma and 6 porocarcinoma cases but not in a wide range of other skin tumor types. Studies on cultured immortalized human dermal keratinocyte (i.e. HDK) and mouse embryonic fibroblast NIH-3T3 cell lines found that the YAP1-NUTM1 and WWTR1-NUTM1 fusion genes stimulated the anchorage-independent growth of NIH-3T3 cells and activated a transcriptional enhancer factor family member (i.e. TEAD family) reporter gene. The TEAD family in mammals includes four members, TEAD1, TEAD2, TEAD3, and TEAD4 that are transcription factors, i.e. proteins that regulate the expression of various genes. TEAD family proteins have been found to promote the development, progression, and/or metastasis of various cancer types and, based on the studies just cited, are thought to do so in poromas and porocarcinomas. However, further studies are needed to confirm this association and determine if TEAD family transcription factors may be useful targets for treating the porocarcinomas. | 1 | Applied and Interdisciplinary Chemistry |
For hydrogels, their elasticity comes from the solid polymer matrix while the viscosity originates from the polymer network mobility and the water and other components that make up the aqueous phase. Viscoelastic properties of a hydrogel is highly dependent on the nature of the applied mechanical motion. Thus, the time dependence of these applied forces is extremely important for evaluating the viscoelasticity of the material.
Physical models for viscoelasticity attempt to capture the elastic and viscous material properties of a material. In an elastic material, the stress is proportional to the strain while in a viscous material, the stress is proportional to the strain rate. The Maxwell model is one developed mathematical model for linear viscoelastic response. In this model, viscoelasticity is modeled analogous to an electrical circuit with a Hookean spring, that represents the Young's modulus, and a Newtonian dashpot that represents the viscosity. A material that exhibit properties described in this model is a Maxwell material. Another physical model used is called the Kelvin-Voigt Model and a material that follow this model is called a Kelvin–Voigt material. In order to describe the time-dependent creep and stress-relaxation behavior of hydrogel, a variety of physical lumped parameter models can be used. These modeling methods vary greatly and are extremely complex, so the empirical Prony Series description is commonly used to describe the viscoelastic behavior in hydrogels.
In order to measure the time-dependent viscoelastic behavior of polymers dynamic mechanical analysis is often performed. Typically, in these measurements the one side of the hydrogel is subjected to a sinusoidal load in shear mode while the applied stress is measured with a stress transducer and the change in sample length is measured with a strain transducer. One notation used to model the sinusoidal response to the periodic stress or strain is:
in which G' is the real (elastic or storage) modulus, G" is the imaginary (viscous or loss) modulus. | 0 | Theoretical and Fundamental Chemistry |
α-Ketoisovaleric acid is an organic compound with the formula (CH)CHC(O)COH. It is a ketoacid. With a melting point just above room temperature, it is usually an oil or semi-solid. The compound is colorless. It is a metabolite of valine and a precursor to pantothenic acid, a prosthetic group found in several cofactors. In the biological context, is usually encountered as its conjugate base ketoisovalerate, (CH)CHC(O)CO. | 1 | Applied and Interdisciplinary Chemistry |
In a gas of finite-sized particles there are collisions among particles that depend on their cross-sectional size. The average distance that a particle travels between collisions depends on the density of gas particles. These quantities are related by
where
: is the cross section of a two-particle collision (SI units: m),
: is the mean free path between collisions (SI units: m),
: is the number density of the target particles (SI units: m).
If the particles in the gas can be treated as hard spheres of radius that interact by direct contact, as illustrated in Figure 1, then the effective cross section for the collision of a pair is
If the particles in the gas interact by a force with a larger range than their physical size, then the cross section is a larger effective area that may depend on a variety of variables such as the energy of the particles.
Cross sections can be computed for atomic collisions but also are used in the subatomic realm. For example, in nuclear physics a "gas" of low-energy neutrons collides with nuclei in a reactor or other nuclear device, with a cross section that is energy-dependent and hence also with well-defined mean free path between collisions. | 0 | Theoretical and Fundamental Chemistry |
Omega oxidation (ω-oxidation) is a process of fatty acid metabolism in some species of animals. It is an alternative pathway to beta oxidation that, instead of involving the β carbon, involves the oxidation of the ω carbon (the carbon most distant from the carboxyl group of the fatty acid). The process is normally a minor catabolic pathway for medium-chain fatty acids (10-12 carbon atoms), but becomes more important when β oxidation is defective.
In vertebrates, the enzymes for ω oxidation are located in the smooth ER of liver and kidney cells, instead of in the mitochondria as with β oxidation. The steps of the process are as follows:
After these three steps, either end of the fatty acid can be attached to coenzyme A. The molecule can then enter the mitochondrion and undergo β oxidation. The final products after successive oxidations include succinic acid, which can enter the citric acid cycle, and adipic acid.
The first step in ω-oxidation, i.e. addition of a hydroxy residue to the omega carbon of short, intermediate, and long chain unsaturated or saturated fatty acids, can serve to produce or inactivate signaling molecules. In humans, a subset of Cytochrome P450 (CYP450) microsome-bound ω-hydroxylases (termed Cytochrome P450 omega hydroxylases) metabolize arachidonic acid (also known as eicosatetraenoic acid) to 20-hydroxyeicosatetraenoic acid (20-HETE). 20-HETE possesses a range of activities in animal and cellular model systems, e.g. it constricts blood vessels, alters the kidneys reabsorption of salt and water, and promotes the growth of cancer cells; genetic studies in humans suggest that 20-HETE contributes to hypertension, myocardial infarction, and brain stroke (see 20-Hydroxyeicosatetraenoic acid). Among the CYP450 superfamily, members of the CYP4A and CYP4F subfamilies viz., CYP4A11, CYP4F2, CYP4F3, are considered the predominant cytochrome P450 enzymes responsible in most tissues for forming 20-HETE. CYP2U1 and CYP4Z1 contribute to 20-HETE production in a more limited range of tissues. The cytochrome ω-oxidases including those belonging to the CYP4A and CYP4F sub-families and CYPU21 also ω-hydroxylate and thereby reduce the activity of various fatty acid metabolites of arachidonic acid including LTB4, 5-HETE, 5-oxo-eicosatetraenoic acid, 12-HETE, and several prostaglandins that are involved in regulating various inflammatory, vascular, and other responses in animals and humans. This hydroxylation-induced inactivation may underlie the proposed roles of the cytochromes in dampening inflammatory responses and the reported associations of certain CYP4F2 and CYP4F3 single nucleotide variants with human Crohns disease and Celiac disease, respectively. | 1 | Applied and Interdisciplinary Chemistry |
Grignard reagents of acetylene or alkynes can be used to perform alkynylations on compounds that are liable to polymerization reactions via enolate intermediates. However, substituting lithium for sodium or potassium acetylides accomplishes similar results, often giving this route little advantage over the conventional reaction. | 0 | Theoretical and Fundamental Chemistry |
Monatomic ions are formed by the gain or loss of electrons to the valence shell (the outer-most electron shell) in an atom. The inner shells of an atom are filled with electrons that are tightly bound to the positively charged atomic nucleus, and so do not participate in this kind of chemical interaction. The process of gaining or losing electrons from a neutral atom or molecule is called ionization.
Atoms can be ionized by bombardment with radiation, but the more usual process of ionization encountered in chemistry is the transfer of electrons between atoms or molecules. This transfer is usually driven by the attaining of stable ("closed shell") electronic configurations. Atoms will gain or lose electrons depending on which action takes the least energy.
For example, a sodium atom, Na, has a single electron in its valence shell, surrounding 2 stable, filled inner shells of 2 and 8 electrons. Since these filled shells are very stable, a sodium atom tends to lose its extra electron and attain this stable configuration, becoming a sodium cation in the process
On the other hand, a chlorine atom, Cl, has 7 electrons in its valence shell, which is one short of the stable, filled shell with 8 electrons. Thus, a chlorine atom tends to gain an extra electron and attain a stable 8-electron configuration, becoming a chloride anion in the process:
This driving force is what causes sodium and chlorine to undergo a chemical reaction, wherein the "extra" electron is transferred from sodium to chlorine, forming sodium cations and chloride anions. Being oppositely charged, these cations and anions form ionic bonds and combine to form sodium chloride, NaCl, more commonly known as table salt. | 0 | Theoretical and Fundamental Chemistry |
Hybrid metal foams typically have a thin film on the underlying porous substrate. Coating metal foams with a different material has been shown to improve the mechanical properties of the metal foam, especially because they are prone to bending deformation mechanisms due to their cellular structure. The addition of a thin film can also improve other properties such as corrosion resistance and enable surface functionalization for catalytic flow processes.
To fabricate hybrid metal foams, thin films are deposited onto a foam substrate with electrodeposition at room temperature. A two-electrode cell setup in a Watt's bath can be used. Recent studies have demonstrated issues with the uniformity of the thin-film due to the complex geometry of metal foams. Issues with uniformity have been addressed in more recent studies through the implementation of nanoparticle thin films, leading to improved mechanical and corrosion resistance properties.
Recent studies on hybrid foams have also been used to address non-renewable energy resources. Transition metal hybrid foams have previously been fabricated through a combination of electrodeposition and hydrogen bubbling processes to enhance the diffusivity of fluids through the porous material and improve the electrical properties for enhanced charge transfer. Thus, such foams can be used to make electrocatalytic water splitting processes more efficient.
Hybrid metal foams may have favorable conductive properties for flexible devices. Through the application of a thin layer of metal onto a porous polymer substrate via gas-phase deposition, researchers have been able to achieve high conductivity while maintaining the flexibility of the polymer matrix. Through cycling testing, it has been shown that hybrid foams are capable of surface deformation sensing. Future efforts seek to characterize the change in cross-linking and porosity of materials as deposition occurs. Additionally, the interaction or compatibility between different polymers and metals in foam ligands can be explored in order to get an improved understanding of their sensitivity to external forces. This would help improve resistance to compressive forces. | 0 | Theoretical and Fundamental Chemistry |
To a solution of 1,3-dihydro-1,3-bis(chloromethyl)benzo[c] thiophene 2,2-dioxide (0.584 g, 2.2 mmol) in 50 ml of dry benzene was added 0.80 mL (2.8 mmol) of a 70% benzene solution of NaAlH(OCHCHOCH) via syringe, and the solution was refluxed for 12 hours. The mixture was cooled to 0° and decomposed with 20% sulfuric acid. The benzene layer was separated, washed with 10 mL of water, dried over potassium carbonate, and concentrated to give the product as a yellow oil in 91% yield (0.480 g); IR (film) 770, 1140, and 1320 cm–1; NMR (CDCl) δ 4.22 (q, 2 H), 1.61 and 1.59 (2 d, 6 H, J = 7 Hz), 7.3 (s, 4 H); m/e (rel. intensity) 196 (M+) (14), 132 (M-SO2) (100); MS analysis 196.055796 (calc.), 196.057587 (obs.). | 0 | Theoretical and Fundamental Chemistry |
Some nutrients are complex molecules (for example vitamin B) which would be destroyed if they were broken down into their functional groups. To digest vitamin B non-destructively, haptocorrin in saliva strongly binds and protects the B molecules from stomach acid as they enter the stomach and are cleaved from their protein complexes.
After the B-haptocorrin complexes pass from the stomach via the pylorus to the duodenum, pancreatic proteases cleave haptocorrin from the B molecules which rebind to intrinsic factor (IF). These B-IF complexes travel to the ileum portion of the small intestine where cubilin receptors enable assimilation and circulation of B-IF complexes in the blood. | 1 | Applied and Interdisciplinary Chemistry |
Irma Goldberg (born 1871) was a Russian-born chemist. She was one of the first female organic chemists to have and sustain a successful career, her work even being quoted in her own name in standard textbooks. | 0 | Theoretical and Fundamental Chemistry |
Golden rice is a recombinant variety of rice that has been engineered to express the enzymes responsible for β-carotene biosynthesis. This variety of rice holds substantial promise for reducing the incidence of vitamin A deficiency in the world's population. Golden rice is not currently in use, pending the resolution of regulatory and intellectual property issues. | 1 | Applied and Interdisciplinary Chemistry |
These are also called injectable formulations and are used with intravenous, subcutaneous, intramuscular, and intra-articular administration. The drug is stored in liquid or if unstable, lyophilized form.
Many parenteral formulations are unstable at higher temperatures and require storage at refrigerated or sometimes frozen conditions. The logistics process of delivering these drugs to the patient is called the cold chain. The cold chain can interfere with delivery of drugs, especially vaccines, to communities where electricity is unpredictable or nonexistent. NGOs like the Gates Foundation are actively working to find solutions. These may include lyophilized formulations which are easier to stabilize at room temperature.
Most protein formulations are parenteral due to the fragile nature of the molecule which would be destroyed by enteric administration. Proteins have tertiary and quaternary structures that can be degraded or cause aggregation at room temperature. This can impact the safety and efficacy of the medicine. | 1 | Applied and Interdisciplinary Chemistry |
The presence of water in a solution of sodium chloride must be examined in respect to its reduction and oxidation in both electrodes. Usually, water is electrolysed as mentioned above in electrolysis of water yielding gaseous oxygen in the anode and gaseous hydrogen in the cathode. On the other hand, sodium chloride in water dissociates in Na and Cl ions. The cation, which is the positive ion, will be attracted to the cathode (−), thus reducing the sodium ion. The chloride anion will then be attracted to the anode (+), where it is oxidized to chlorine gas.
The following half reactions should be considered in the process mentioned:
# Cathode: Na + e → NaE° = –2.71 V
# Anode: 2 Cl → Cl + 2 eE° = +1.36 V
# Cathode: 2 HO + 2 e → H + 2 OHE° = –0.83 V
# Anode: 2 HO → O + 4 H + 4 eE° = +1.23 V
Reaction 1 is discarded as it has the most negative value on standard reduction potential thus making it less thermodynamically favorable in the process.
When comparing the reduction potentials in reactions 2 and 4, the oxidation of chloride ion is favored over oxidation of water, thus chlorine gas is produced at the anode and not oxygen gas.
Although the initial analysis is correct, there is another effect, known as the overvoltage effect. Additional voltage is sometimes required, beyond the voltage predicted by the E°. This may be due to kinetic rather than thermodynamic considerations. In fact, it has been proven that the activation energy for the chloride ion is very low, hence favorable in kinetic terms. In other words, although the voltage applied is thermodynamically sufficient to drive electrolysis, the rate is so slow that to make the process proceed in a reasonable time frame, the voltage of the external source has to be increased (hence, overvoltage).
The overall reaction for the process according to the analysis is the following:
:Anode (oxidation): 2 Cl → Cl + 2 e
:Cathode (reduction): 2 HO + 2 e → H + 2 OH
:Overall reaction: 2 HO + 2 Cl → H + Cl + 2 OH
As the overall reaction indicates, the concentration of chloride ions is reduced in comparison to OH ions (whose concentration increases). The reaction also shows the production of gaseous hydrogen, chlorine and aqueous sodium hydroxide. | 0 | Theoretical and Fundamental Chemistry |
Inductively coupled plasma atomic emission spectroscopy (ICP-AES), also referred to as inductively coupled plasma optical emission spectroscopy (ICP-OES), is an analytical technique used for the detection of chemical elements. It is a type of emission spectroscopy that uses the inductively coupled plasma to produce excited atoms and ions that emit electromagnetic radiation at wavelengths characteristic of a particular element. The plasma is a high temperature source of ionised source gas (often argon). The plasma is sustained and maintained by inductive coupling from electrical coils at megahertz frequencies. The source temperature is in the range from 6000 to 10,000 K. The intensity of the emissions from various wavelengths of light are proportional to the concentrations of the elements within the sample. | 0 | Theoretical and Fundamental Chemistry |
In fragment-based drug discovery, the low binding affinities of the fragments pose significant challenges for screening. Many biophysical techniques have been applied to address this issue. In particular, ligand-observe nuclear magnetic resonance (NMR) methods such as water-ligand observed via gradient spectroscopy (waterLOGSY), saturation transfer difference spectroscopy (STD-NMR), F NMR spectroscopy and inter-ligand Overhauser effect (ILOE) spectroscopy, protein-observe NMR methods such as H-N heteronuclear single quantum coherence (HSQC) that utilises isotopically-labelled proteins, surface plasmon resonance (SPR), isothermal titration calorimetry (ITC) and Microscale Thermophoresis (MST) are routinely-used for ligand screening and for the quantification of fragment binding affinity to the target protein. At modern X-ray crystallography synchrotron beamlines, several hundred data sets of protein-ligand complex crystal structures can be obtained within 24 hours. This technology makes crystallographic fragment screening possible, i.e. the use of X-ray crystallography directly for the fragment screening step.
Once a fragment (or a combination of fragments) have been identified, protein X-ray crystallography is used to obtain structural models of the protein- complexes. Such information can then be used to guide organic synthesis for high-affinity protein ligands and enzyme inhibitors. | 1 | Applied and Interdisciplinary Chemistry |
Adsorption is the first step in the viral life cycle. The next steps are penetration, uncoating, synthesis (transcription if needed, and translation), and release. The virus replication cycle, in this respect, is similar for all types of viruses. Factors such as transcription may or may not be needed if the virus is able to integrate its genomic information in the cells nucleus, or if the virus can replicate itself directly within the cells cytoplasm. | 0 | Theoretical and Fundamental Chemistry |
A mechanical tube cleaning system is a cleaning body that is moved through the tube in order to remove deposits from the tube wall. In the most simple case it is a matter of a brush that is moved in the tube by means of a rod or a flexible spring (device). In large-scale technology and industrial sector, however, several processes have developed which necessitate a more detailed definition. | 1 | Applied and Interdisciplinary Chemistry |
TADs are defined as regions whose DNA sequences preferentially contact each other. They were discovered in 2012 using chromosome conformation capture techniques including Hi-C. They have been shown to be present in multiple species, including fruit flies (Drosophila), mouse, plants, fungi and human genomes. In bacteria, they are referred to as Chromosomal Interacting Domains (CIDs). | 1 | Applied and Interdisciplinary Chemistry |
In 1928, German chemist H. O. Albrecht found that blood, among other substances, enhanced the luminescence of luminol in an alkaline solution of hydrogen peroxide. In 1936, Karl Gleu and Karl Pfannstiel confirmed this enhancement in the presence of haematin, a component of blood. In 1937, German forensic scientist Walter Specht made extensive studies of luminol's application to the detection of blood at crime scenes. In 1939, San Francisco pathologists Frederick Proescher and A. M. Moody made three important observations about luminol:
# although the test is presumptive, large areas of suspected material can be examined rapidly;
# dried and decomposed blood gave a stronger and more lasting reaction than fresh blood; and
# if the luminescence disappears, it may be reproduced by the application of a fresh luminol-hydrogen peroxide solution; dried bloodstains may thus be made luminescent repeatedly. | 0 | Theoretical and Fundamental Chemistry |
Suspended solids (or SS), is the mass of dry solids retained by a filter of a given porosity related to the volume of the water sample. This includes particles 10 μm and greater.
Colloids are particles of a size between 1 nm (0.001 µm) and 1 µm depending on the method of quantification. Because of Brownian motion and electrostatic forces balancing the gravity, they are not likely to settle naturally.
The limit sedimentation velocity of a particle is its theoretical descending speed in clear and still water. In settling process theory, a particle will settle only if:
# In a vertical ascending flow, the ascending water velocity is lower than the limit sedimentation velocity.
# In a longitudinal flow, the ratio of the length of the tank to the height of the tank is higher than the ratio of the water velocity to the limit sedimentation velocity.
Removal of suspended particles by sedimentation depends upon the size, zeta potential and specific gravity of those particles. Suspended solids retained on a filter may remain in suspension if their specific gravity is similar to water while very dense particles passing through the filter may settle. Settleable solids are measured as the visible volume accumulated at the bottom of an Imhoff cone after water has settled for one hour.
Gravitational theory is employed, alongside the derivation from Newton's second law and the Navier–Stokes equations.
Stokes' law explains the relationship between the settling rate and the particle diameter. Under specific conditions, the particle settling rate is directly proportional to the square of particle diameter and inversely proportional to liquid viscosity.
The settling velocity, defined as the residence time taken for the particles to settle in the tank, enables the calculation of tank volume. Precise design and operation of a sedimentation tank is of high importance in order to keep the amount of sediment entering the diversion system to a minimum threshold by maintaining the transport system and stream stability to remove the sediment diverted from the system. This is achieved by reducing stream velocity as low as possible for the longest period of time possible. This is feasible by widening the approach channel and lowering its floor to reduce flow velocity thus allowing sediment to settle out of suspension due to gravity. The settling behavior of heavier particulates is also affected by the turbulence. | 0 | Theoretical and Fundamental Chemistry |
* pentacyanopyridine -
* tetracyanopyrazine -
* tricyanotriazine -
* tetracyano-bitriazine -
* dicyanotetrazine -
* hexacyanotrisimidazole -
* hexacyanohexaazatriphenylene - | 0 | Theoretical and Fundamental Chemistry |
The work of the Italian physician and humanist Ermolao Barbaro was published in 1516, 23 years after his death. Poliziano wrote to Ermalao Barbaro, forwarding a manuscript of the 1st-century pharmacologist Pedanius Dioscorides, asking him to send it back "annotated by that very learned hand of yours, thus lending the volume additional value and authority." Barbaro was professor of the University of Padua in 1477 and translated many texts from Greek to Latin.
He sought to avoid mistakes by gathering as many manuscripts as he could for checking the texts. He claimed to have corrected 5000 mistakes between two editions of Pliny the Elders Naturalis historia, a work he found very similar to Materia Medica', for which he used at least two editions as well.
The result of Barbaros effort occupied no fewer than 58 pages printed in three columns of about 50 entries each. The work provides a key to over 9,000 items; all references were to pages. This was the first annotated Latin translation of Dioscorides Materia Medica, and so Barbaro became the earliest of the Renaissance translators of Dioscorides, a practice that saw its golden age in the 16th century. Barbaro's work was later corrected by Giovanni-Battista. | 1 | Applied and Interdisciplinary Chemistry |
Consider the example burning of magnesium ribbon (Mg). When magnesium burns, it combines with oxygen () from the air to form magnesium oxide (MgO) according to the following equation:
Magnesium oxide is an ionic compound containing and ions whereas and are elements with no charges.
The with zero charge gains a +2 charge going from the reactant side to product side, and the with zero charge gains a –2 charge. This is because when becomes , it loses 2 electrons. Since there are 2 Mg on left side, a total of 4 electrons are lost according to the following oxidation half reaction:
On the other hand, was reduced: its oxidation state goes from 0 to -2. Thus, a reduction half reaction can be written for the O2 as it gains 4 electrons:
The overall reaction is the sum of both half reactions:
When chemical reaction, especially, redox reaction takes place, we do not see the electrons as they appear and disappear during the course of the reaction. What we see is the reactants (starting material) and end products. Due to this, electrons appearing on both sides of the equation are canceled. After canceling, the equation is re-written as
Two ions, positive () and negative () exist on product side and they combine immediately to form a compound magnesium oxide (MgO) due to their opposite charges (electrostatic attraction). In any given oxidation-reduction reaction, there are two half reactions—oxidation half reaction and reduction half reaction. The sum of these two half reactions is the oxidation–reduction reaction. | 0 | Theoretical and Fundamental Chemistry |
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