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TFA is a heterodimer with two subunits: one large unprocessed (subunit 1, or alpha/beta; gene name ) and one small (subunit 2, or gamma; gene name ). It was originally believed to be a heterotrimer of an alpha (p35), a beta (p19) and a gamma subunit (p12). In humans, the sizes of the encoded proteins are approximately 55 kD and 12 kD. Both genes are present in species ranging from humans to yeast, and their protein products interact to form a complex composed of a beta barrel domain and an alpha helical bundle domain. It is the N-terminal and C-terminal regions of the large subunit that participate in interactions with the small subunit. These regions are separated by another domain whose sequence is always present in large subunits from various species but whose size varies and whose sequence is poorly conserved. A second gene encoding a large TFA subunit has been found in some higher eukaryotes. This gene, ALF/TFIIAtau (gene name ) is expressed only in oocytes and spermatocytes, suggesting it has a TFA-like regulatory role for gene expression only in germ cells. | 1 | Applied and Interdisciplinary Chemistry |
Hard solders are used for brazing, and melt at higher temperatures. Alloys of copper with either zinc or silver are the most common.
In silversmithing or jewelry making, special hard solders are used that will pass assay. They contain a high proportion of the metal being soldered and lead is not used in these alloys. These solders vary in hardness, designated as "enameling", "hard", "medium" and "easy". Enameling solder has a high melting point, close to that of the material itself, to prevent the joint desoldering during firing in the enameling process. The remaining solder types are used in decreasing order of hardness during the process of making an item, to prevent a previously soldered seam or joint desoldering while additional sites are soldered. Easy solder is also often used for repair work for the same reason. Flux is also used to prevent joints from desoldering.
Silver solder is also used in manufacturing to join metal parts that cannot be welded. The alloys used for these purposes contain a high proportion of silver (up to 40%), and may also contain cadmium. | 1 | Applied and Interdisciplinary Chemistry |
The journal is abstracted and indexed in:
*CAB Abstracts
*Chemical Abstracts Service
*Current Contents/Physical, Chemical & Earth Sciences
*Science Citation Index Expanded
*Scopus
According to the Journal Citation Reports, the journal has a 2020 impact factor of 1.561. | 0 | Theoretical and Fundamental Chemistry |
The Environmental Residue Effects Database (ERED) is a database maintained by the U.S. Army Corps of Engineers that pairs data regarding the bioaccumulation of toxicants in tissue (via tissue residue) to endpoint effects such as mortality, growth, or physiological and biochemical responses. Response data also include low effect detected (LOED) and no effect detected (NOED) concentrations. This database is derived from 2329 peer-reviewed references regarding 413 chemicals. The database covers literature from 1964 to the present and includes more than 15,000 records. This database is updated with 300 or more records every year on average. The ERED database is specific to sediment toxicity and the effects of contaminates in dredged materials on freshwater organisms. It is intended to be used in evaluating the potential for contaminate concentrations of dredged sediment to have unacceptable adverse effects on aquatic organisms. Although the ERED database was designed as a tool for the Army Corps of Engineers to manage adverse effects of dredging, it is widely applicable to sediment toxicity studies and management. | 1 | Applied and Interdisciplinary Chemistry |
In 1859, Henri Étienne Sainte-Claire Deville in France developed a method for making alumina by heating bauxite in sodium carbonate, NaCO, at 1200 °C, leaching the sodium aluminate formed with water, then precipitating aluminium hydroxide by carbon dioxide, CO, which was then filtered and dried. This process is known as the Deville process. In 1886, the Hall–Héroult electrolytic aluminium process was invented, and the cyanidation process was invented in 1887.
The Bayer process was invented in 1888 by Carl Josef Bayer. Working in Saint Petersburg, Russia to develop a method for supplying alumina to the textile industry (it was used as a mordant in dyeing cotton), Bayer discovered in 1887 that the aluminium hydroxide that precipitated from alkaline solution was crystalline and could be easily filtered and washed, while that precipitated from acid medium by neutralization was gelatinous and difficult to wash. The industrial success of this process caused it to replace the Le Chatelier process which was used to produce alumina from bauxite. The Deville process was abandoned in favor of the Bayer process, which marks the birth of the modern field of hydrometallurgy.
The engineering aspects of the process were improved upon to decrease the cost starting in 1967 in Germany and Czechoslovakia. This was done by increasing the heat recovery and using large autoclaves and precipitation tanks. To more effectively use energy, heat exchangers and flash tanks were used and larger reactors decreased the amount of heat lost. Efficiency was increased by connecting the autoclaves to make operation more efficient.
Today, the process produces nearly all the world's alumina supply as an intermediate step in aluminium production. | 1 | Applied and Interdisciplinary Chemistry |
Bisulfite sequencing (also known as bisulphite sequencing) is the use of bisulfite treatment of DNA before routine sequencing to determine the pattern of methylation. DNA methylation was the first discovered epigenetic mark, and remains the most studied. In animals it predominantly involves the addition of a methyl group to the carbon-5 position of cytosine residues of the dinucleotide CpG, and is implicated in repression of transcriptional activity.
Treatment of DNA with bisulfite converts cytosine residues to uracil, but leaves 5-methylcytosine residues unaffected. Therefore, DNA that has been treated with bisulfite retains only methylated cytosines. Thus, bisulfite treatment introduces specific changes in the DNA sequence that depend on the methylation status of individual cytosine residues, yielding single-nucleotide resolution information about the methylation status of a segment of DNA. Various analyses can be performed on the altered sequence to retrieve this information. The objective of this analysis is therefore reduced to differentiating between single nucleotide polymorphisms (cytosines and thymidine) resulting from bisulfite conversion (Figure 1). | 1 | Applied and Interdisciplinary Chemistry |
Uniporters, also known as solute carriers or facilitated transporters, are a type of membrane transport protein that passively transports solutes (small molecules, ions, or other substances) across a cell membrane. It uses facilitated diffusion for the movement of solutes down their concentration gradient from an area of high concentration to an area of low concentration. Unlike active transport, it does not require energy in the form of ATP to function. Uniporters are specialized to carry one specific ion or molecule and can be categorized as either channels or carriers. Facilitated diffusion may occur through three mechanisms: uniport, symport, or antiport. The difference between each mechanism depends on the direction of transport, in which uniport is the only transport not coupled to the transport of another solute.
Uniporter carrier proteins work by binding to one molecule or substrate at a time. Uniporter channels open in response to a stimulus and allow the free flow of specific molecules.
There are several ways in which the opening of uniporter channels may be regulated:
# Voltage – Regulated by the difference in voltage across the membrane
# Stress – Regulated by physical pressure on the transporter (as in the cochlea of the ear)
# Ligand – Regulated by the binding of a ligand to either the intracellular or extracellular side of the cell
Uniporters are found in mitochondria, plasma membranes and neurons.The uniporter in the mitochondria is responsible for calcium uptake. The calcium channels are used for cell signaling and triggering apoptosis. The calcium uniporter transports calcium across the inner mitochondrial membrane and is activated when calcium rises above a certain concentration. The amino acid transporters function in transporting neutral amino acids for neurotransmitter production in brain cells. Voltage-gated potassium channels are also uniporters found in neurons and are essential for action potentials. This channel is activated by a voltage gradient created by sodium-potassium pumps. When the membrane reaches a certain voltage, the channels open, which depolarizes the membrane, leading to an action potential being sent down the membrane. Glucose transporters are found in the plasma membrane and play a role in transporting glucose. They help to bring glucose from the blood or extracellular space into cells usually to be utilized for metabolic processes in generating energy.
Uniporters are essential for certain physiological processes in cells, such as nutrient uptake, waste removal, and maintenance of ionic balance. | 1 | Applied and Interdisciplinary Chemistry |
DAVID provides a comprehensive set of functional annotation tools for investigators to understand biological meaning behind large list of genes. For any given gene list, DAVID tools are able to:
* Identify enriched biological themes, particularly GO terms
* Discover enriched functional-related gene groups
* Cluster redundant annotation terms
* Visualize genes on BioCarta & KEGG pathway maps
* Display related many-genes-to-many-terms on 2-D view.
* Search for other functionally related genes not in the list
* List interacting proteins
* Explore gene names in batch
* Link gene-disease associations
* Highlight protein functional domains and motifs
* Redirect to related literatures
* Convert gene identifiers from one type to another. | 1 | Applied and Interdisciplinary Chemistry |
When the dimension of the lattice rises to four or more, rotations need no longer be planar; the 2D proof is inadequate. However, restrictions still apply, though more symmetries are permissible. For example, the hypercubic lattice has an eightfold rotational symmetry, corresponding to an eightfold rotational symmetry of the hypercube. This is of interest, not just for mathematics, but for the physics of quasicrystals under the cut-and-project theory. In this view, a 3D quasicrystal with 8-fold rotation symmetry might be described as the projection of a slab cut from a 4D lattice.
The following 4D rotation matrix is the aforementioned eightfold symmetry of the hypercube (and the cross-polytope):
Transforming this matrix to the new coordinates given by
: will produce:
This third matrix then corresponds to a rotation both by 45° (in the first two dimensions) and by 135° (in the last two). Projecting a slab of hypercubes along the first two dimensions of the new coordinates produces an Ammann–Beenker tiling (another such tiling is produced by projecting along the last two dimensions), which therefore also has 8-fold rotational symmetry on average.
The A4 lattice and F4 lattice have order 10 and order 12 rotational symmetries, respectively.
To state the restriction for all dimensions, it is convenient to shift attention away from rotations alone and concentrate on the integer matrices . We say that a matrix A has order k when its k-th power (but no lower), A, equals the identity. Thus a 6-fold rotation matrix in the equilateral triangle basis is an integer matrix with order 6. Let Ord denote the set of integers that can be the order of an N×N integer matrix. For example, Ord = {1, 2, 3, 4, 6}. We wish to state an explicit formula for Ord.
Define a function ψ based on Eulers totient function φ; it will map positive integers to non-negative integers. For an odd prime, p, and a positive integer, k, set ψ(p) equal to the totient function value,
φ(p), which in this case is p−p. Do the same for ψ(2) when k > 1. Set ψ(2) and ψ(1) to 0. Using the fundamental theorem of arithmetic, we can write any other positive integer uniquely as a product of prime powers, m = Π p; set ψ(m) = Σ ψ(p). This differs from the totient itself, because it is a sum instead of a product.
The crystallographic restriction in general form states that Ord consists of those positive integers m such that ψ(m) ≤ N.
For m>2, the values of ψ(m) are equal to twice the algebraic degree of cos(2π/m); therefore, ψ(m) is strictly less than m and reaches this maximum value if and only if m is a prime.
These additional symmetries do not allow a planar slice to have, say, 8-fold rotation symmetry. In the plane, the 2D restrictions still apply. Thus the cuts used to model quasicrystals necessarily have thickness.
Integer matrices are not limited to rotations; for example, a reflection is also a symmetry of order 2. But by insisting on determinant +1, we can restrict the matrices to proper rotations. | 0 | Theoretical and Fundamental Chemistry |
The narrowness of the band of colors that a monochromator can generate is related to the focal length of the monochromator collimators. Using a longer focal length optical system also unfortunately decreases the amount of light that can be accepted from the source. Very high resolution monochromators might have a focal length of 2 meters. Building such monochromators requires exceptional attention to mechanical and thermal stability. For many applications a monochromator of about 0.4 meter focal length is considered to have excellent resolution. Many monochromators have a focal length less than 0.1 meter. | 0 | Theoretical and Fundamental Chemistry |
: MARS include identification and selection of several genomic regions (up to 20 or even more) for complex traits within a single population. | 1 | Applied and Interdisciplinary Chemistry |
He has spent most of his professional life at the “Giacomo Ciamician” Department of Chemistry of the University of Bologna, becoming full professor in 1973. He has been appointed emeritus professor on November 1, 2010. | 0 | Theoretical and Fundamental Chemistry |
* 2009 Nexxus Young Life Scientist of the Year
* 2013 Royal Society of Chemistry (RSC) Joseph Black Award
* 2016 Top 50 Women in Analytical Science
* 2016 Coblentz Society Craver Award
* 2017 The Analytical Scientist Top 10 Spectroscopists
* 2018 Elected Fellow of the Royal Society of Edinburgh (FRSE)
* 2023 The Analytical Scientist the Power List - Connectors and Interdisciplinarians
Faulds is a Fellow of the Society for Applied Spectroscopy (SAS) and a member of the Young Academy of Scotland (YAS).
In 2019 Faulds was included in the 2019 Power List of The Analytical Scientist. | 0 | Theoretical and Fundamental Chemistry |
A common route to primary amidines is the Pinner reaction. Reaction of the nitrile with alcohol in the presence of acid gives an iminoether. Treatment of the resulting compound with ammonia then completes the conversion to the amidine. Instead of using a Bronsted acid, Lewis acids such as aluminium trichloride promote the direct amination of nitriles. They are also generated by amination of an imidoyl chloride.
They are also prepared by the addition of organolithium reagents to diimines, followed by protonation or alkylation.
Dimethylformamide acetal reacts with primary amines to give amidines:
:MeNC(H)(OMe) + RNH → MeNC=NHR + 2 MeOH | 0 | Theoretical and Fundamental Chemistry |
TEOS-10 is based on thermodynamic potentials. Fluids like humid air and liquid water in TEOS-10 are therefore described by the Helmholtz energy F(m,T,V)=F(m,T,m/ρ) or the specific Helmholtz-energy f(T,ρ)=F(m,T,m/ρ)/m. The Helmholtz energy has a unique value across phase boundaries. For the calculation of the thermodynamic properties of seawater and ice, TEOS-10 uses the specific Gibbs potential g(T,P)=G/m, G=F+pV, because the pressure is a more easily measurable property than density in a geophysical context. Gibbs energies are multivalued around phase boundaries and need to be defined for each phase separately.
The thermodynamic potential functions are determined by a set of adjustable parameters which are tuned to fit experimental data and theoretical laws of physics like the ideal gas equation. Since absolute energy and entropy cannot be directly measured, arbitrary reference states for liquid water, seawater and dry air in TEOS-10 are defined in a way that
* internal energy and entropy of liquid water at the solid-liquid-gas triple point are zero,
* entropy and enthalpy of seawater are zero at S (Absolute Salinity) = 35.16504 g/kg, T (Temperature) = 273.15 K, p (pressure) = 101325 Pa,
* entropy and enthalpy of dry air are zero at T (Temperature) = 273.15 K, p (pressure) = 101325 Pa. | 0 | Theoretical and Fundamental Chemistry |
Different organisms may be used to express a genes target protein, and the expression vector used will therefore have elements specific for use in the particular organism. The most commonly used organism for protein production is the bacterium Escherichia coli. However, not all proteins can be successfully expressed in E. coli', or be expressed with the correct form of post-translational modifications such as glycosylations, and other systems may therefore be used. | 1 | Applied and Interdisciplinary Chemistry |
* 1999 – 2000 member of the founding committee of the Groningen Genomics Centre of the University of Groningen
* 1999 – 2007 member of the board of directors of the Groningen Biomolecular Sciences and Biotechnology Institute (GBB) of the University of Groningen
* 2000 – 2007 chairman of the Genetics Cluster of the University of Groningen
* 2011 – present member of the scientific advisory board of the LOEWE Institute for Synthetitic Microbiology (Synmikro) in Marburg (Germany)
* 2013 – present confidential advisor on scientific integrity, Faculty of Mathematics- and Natural Sciences, University of Groningen Groningen
* 2015 – present chairman and co-founder of the Centre for Sustainable Antimicrobials (CeSAM) of the University of Groningen
* 2015 – present cofounder, Centre for Antimicrobial Research (CARES). Chairman & Director: Prof. Gilles van Wezel. | 0 | Theoretical and Fundamental Chemistry |
The group of C. Dekker (Delft University) directly probed the interactions involved in homology search by combining magnetic and optical tweezers. They have found that homology search and recognition requires opening of the helix and can therefore be accelerated by unwinding the DNA. This is exactly the energy barrier predicted by the conformational proofreading model. The data indicate a physical picture for homology recognition in which the fidelity of the search process is governed by the distance between the DNA-binding sites. The authors conclude that their interpretation of the measurements "is akin to a conformational proofreading scheme ... where the dsDNA, and not the RecA filament, is the active, recognizing search entity. A large conformational mismatch exists between the target-bound and unbound states of the dsDNA. The target-bound state is accessed via energetically unfavorable intermediate states, as discussed above. The conformational mismatch improves the selectivity of the recognition reaction." In other words, they identified the energetic barrier and have shown that indeed the double-stranded DNA is the active participant, since it has to pass this barrier. | 1 | Applied and Interdisciplinary Chemistry |
In some instances, an mRNA will be edited, changing the nucleotide composition of that mRNA. An example in humans is the apolipoprotein B mRNA, which is edited in some tissues, but not others. The editing creates an early stop codon, which, upon translation, produces a shorter protein. | 1 | Applied and Interdisciplinary Chemistry |
Allyl thiocyanate isomerizes to the isothiocyanate:
Isothiocyanates can be prepared by degradation of dithiocarbamate salts, e.g. induced with lead nitrate.
A related method is tosyl chloride-mediated decomposition of dithiocarbamate salts.
Isothiocyanates may also be accessed by the fragmentation reactions of 1,4,2-oxathiazoles. This methodology has been applied to a polymer-supported synthesis of isothiocyanates. | 0 | Theoretical and Fundamental Chemistry |
Places significantly impacted by acid rain around the globe include most of eastern Europe from Poland northward into Scandinavia, the eastern third of the United States, and southeastern Canada. Other affected areas include the southeastern coast of China and Taiwan. | 1 | Applied and Interdisciplinary Chemistry |
Denagliptin (Figure 6) is an advanced compound with a branched side-chain at the P2 position, but also has (4S)-fluoro substitution on the cyanopyrrolidine ring. It is a well-known DPP-4 inhibitor developed by GlaxoSmithKline (GSK). Biological evaluations have shown that the S-configuration of the amino acid portion is essential for the inhibitory activity since the R-configuration showed reluctantly inhibition. These findings will be useful in future designs and synthesis of DPP-4 inhibitors. GSK suspended Phase III clinical trials in October 2008. | 1 | Applied and Interdisciplinary Chemistry |
Distillation and absorption separation processes using packed beds for vapor and liquid contacting have an equivalent concept referred to as the plate height or the height equivalent to a theoretical plate (HETP). HETP arises from the same concept of equilibrium stages as does the theoretical plate and is numerically equal to the absorption bed length divided by the number of theoretical plates in the absorption bed (and in practice is measured in this way).
where is the number of theoretical plates (also called the "plate count"), is the total bed height and is the height equivalent to a theoretical plate.
The material in packed beds can either be random dumped packing (1-3" wide) such as Raschig rings or structured sheet metal. Liquids tend to wet the surface of the packing and the vapors contact the wetted surface, where mass transfer occurs. | 1 | Applied and Interdisciplinary Chemistry |
In 2008, a California physician transferred 12 embryos to a woman who gave birth to octuplets (Suleman octuplets). This led to accusations that a doctor is willing to endanger the health and even life of people in order to gain money. Robert Winston, professor of fertility studies at Imperial College London, had called the industry "corrupt" and "greedy" stating that "one of the major problems facing us in healthcare is that IVF has become a massive commercial industry," and that "what has happened, of course, is that money is corrupting this whole technology", and accused authorities of failing to protect couples from exploitation: "The regulatory authority has done a consistently bad job. Its not prevented the exploitation of people, its not put out very good information to couples, it's not limited the number of unscientific treatments people have access to". The IVF industry has been described as a market-driven construction of health, medicine and the human body.
The industry has been accused of making unscientific claims, and distorting facts relating to infertility, in particular through widely exaggerated claims about how common infertility is in society, in an attempt to get as many couples as possible and as soon as possible to try treatments (rather than trying to conceive naturally for a longer time). This risks removing infertility from its social context and reducing the experience to a simple biological malfunction, which not only can be treated through bio-medical procedures, but should be treated by them. | 1 | Applied and Interdisciplinary Chemistry |
Cannabinoid receptors are G-protein coupled receptors located on the pre-synaptic membrane. While there have been some papers that have linked concurrent stimulation of dopamine and CB receptors to an acute rise in cyclic adenosine monophosphate (cAMP) production, it is generally accepted that CB activation via cannabinoids causes a decrease in cAMP concentration by inhibition of adenylyl cyclase and a rise in the concentration of mitogen-activated protein kinase (MAP kinase). The relative potency of different cannabinoids in inhibition of adenylyl cyclase correlates with their varying efficacy in behavioral assays. This inhibition of cAMP is followed by phosphorylation and subsequent activation of not only a suite of MAP kinases (p38/p42/p44), but also the PI3/PKB and MEK/ERK pathway. Results from rat hippocampal gene chip data after acute administration of tetrahydrocannabinol (THC) showed an increase in the expression of transcripts encoding myelin basic protein, endoplasmic proteins, cytochrome oxidase, and two cell adhesion molecules: NCAM, and SC1; decreases in expression were seen in both calmodulin and ribosomal RNAs. In addition, CB1 activation has been demonstrated to increase the activity of transcription factors like c-Fos and Krox-24. | 1 | Applied and Interdisciplinary Chemistry |
*Nikolaou, A., Meric, S., & Fatta, D. (2007). Occurrence patterns of pharmaceuticals in water and wastewater environments. Analytical and bioanalytical chemistry, 387, 1225–1234.
*Klavarioti, M., Mantzavinos, D., & Kassinos, D. (2009). Removal of residual pharmaceuticals from aqueous systems by advanced oxidation processes. Environment international, 35(2), 402–417.
*Fatta-Kassinos, D., Meric, S., & Nikolaou, A. (2011). Pharmaceutical residues in environmental waters and wastewater: current state of knowledge and future research. Analytical and bioanalytical chemistry, 399, 251–275.
*Rizzo, L., Manaia, C., Merlin, C., Schwartz, T., Dagot, C., Ploy, M. C., ... & Fatta-Kassinos, D. (2013). Urban wastewater treatment plants as hotspots for antibiotic resistant bacteria and genes spread into the environment: a review. Science of the Total Environment, 447, 345–360.
*Michael-Kordatou, I., Michael, C., Duan, X., He, X., Dionysiou, D. D., Mills, M. A., & Fatta-Kassinos, D. (2015). Dissolved effluent organic matter: characteristics and potential implications in wastewater treatment and reuse applications. Water Research, 77, 213–248.
*Michael-Kordatou, I., Iacovou, M., Frontistis, Z., Hapeshi, E., Dionysiou, D. D., & Fatta-Kassinos, D. (2015). Erythromycin oxidation and ERY-resistant Escherichia coli inactivation in urban wastewater by sulfate radical-based oxidation process under UV-C irradiation. Water research, 85, 346–358.
*Pärnänen, K. M., Narciso-da-Rocha, C., Kneis, D., Berendonk, T. U., Cacace, D., Do, T. T., ... & Manaia, C. M. (2019). Antibiotic resistance in European wastewater treatment plants mirrors the pattern of clinical antibiotic resistance prevalence. Science advances, 5(3), eaau9124.
*Karaolia, P., Michael, C., Schwartz, T., & Fatta-Kassinos, D. (2022). Membrane bioreactor followed by solar photo-Fenton oxidation: Bacterial community structure changes and bacterial reduction. Science of the Total Environment, 847, 157594.
*Manoli, K., Naziri, A., Ttofi, I., Michael, C., Allan, I. J., & Fatta-Kassinos, D. (2022). Investigation of the effect of microplastics on the UV inactivation of antibiotic-resistant bacteria in water. Water Research, 222, 118906. | 1 | Applied and Interdisciplinary Chemistry |
Clarke number or clarke is the relative abundance of a chemical element, typically in Earths crust. The technical definition of "Earths crust" varies among authors, and the actual numbers also vary significantly. | 0 | Theoretical and Fundamental Chemistry |
The PI3K pathway is a major source of drug resistance in prostate cancer. This is particularly true in castration-resistant prostate cancer, where tumours become resistant to androgen-deprivation therapy, which block the tumours ability to utilise the hormone androgen to grow. This is due to a complex feedback mechanism which exists between the androgen receptor and the PI3K pathway. As in other tumour types, mutations in key genes of this pathway can lead to hyperactivation of this pathway, for example in PIK3CA, Increases in the copy number of PIK3CA and increased mRNA expression also increases pathway activation in prostate cancers among others. Gains in the nearby genetic region 3q26.31-32 have been shown to co-occur with a number of nearby PI3K family members including PIK3CA, PIK3CB and PIK3R4, leading to transcriptional changes in PIK3C2G, PIK3CA, PIK3CB, PIK3R4 as well as pathways associated with cell proliferation. These large spanning gains associate with Gleason grade, tumour stage, lymph node metastasis and other aggressive clinical features. In patients treated with PI3K inhibitors, those with copy number gains in PIK3CB appear to have increased drug susceptibility. | 1 | Applied and Interdisciplinary Chemistry |
*SDHA NM_004168 Succinate Dehydrogenase subunit A
*SDHAF2 NM_017841
*SDHB NM_002973 Iron-sulfur protein (IP) subunit of succinate dehydrogenase (SDH) that is involved in complex II of the mitochondrial electron transport chain and is responsible for transferring electrons from succinate to ubiquinone (coenzyme Q)
*SDHC NM_003000 Membrane-anchoring subunit of succinate dehydrogenase (SDH) that is involved in complex II of the mitochondrial electron transport chain and is responsible for transferring electrons from succinate to ubiquinone (coenzyme Q).
*SDHD NM_003001 | 1 | Applied and Interdisciplinary Chemistry |
Ehrlichs reagent or Ehrlich reagent is a reagent containing p'-dimethylaminobenzaldehyde (DMAB) and thus can act as an indicator to presumptively identify indoles and urobilinogen. Several Ehrlich tests use the reagent in a medical test; some are drug tests and others contribute to diagnosis of various diseases or adverse drug reactions. It is named after Nobel Prize winner Paul Ehrlich who used it to distinguish typhoid from simple diarrhoea.
The Ehrlich reagent works by binding to the C2 position of two indole moieties to form a resonance stabilised carbenium ion compound. | 0 | Theoretical and Fundamental Chemistry |
Contraindications, conditions that warrant withholding treatment with lovastatin, include pregnancy, breast feeding, and liver disease. Lovastatin is contraindicated during pregnancy (Pregnancy Category X); it may cause birth defects such as skeletal deformities or learning disabilities. Owing to its potential to disrupt infant lipid metabolism, lovastatin should not be taken while breastfeeding. Patients with liver disease should not take lovastatin. | 0 | Theoretical and Fundamental Chemistry |
In most theories of this state, it is supposed that vacancies – empty sites normally occupied by particles in an ideal crystal – lead to supersolidity. These vacancies are caused by zero-point energy, which also causes them to move from site to site as waves. Because vacancies are bosons, if such clouds of vacancies can exist at very low temperatures, then a Bose–Einstein condensation of vacancies could occur at temperatures less than a few tenths of a Kelvin. A coherent flow of vacancies is equivalent to a "superflow" (frictionless flow) of particles in the opposite direction. Despite the presence of the gas of vacancies, the ordered structure of a crystal is maintained, although with less than one particle on each lattice site on average. Alternatively, a supersolid can also emerge from a superfluid. In this situation, which is realised in the experiments with atomic Bose–Einstein condensates, the spatially ordered structure is a modulation on top of the superfluid density distribution. | 0 | Theoretical and Fundamental Chemistry |
The characteristics of steel, in particular the carbon and chromium content, can be controlled by adjusting the oxygen/argon ratio during the manufacturing process. The oxygen/argon ratio is also important in the creation of thin films used in the manufacture of lithium ion batteries. | 0 | Theoretical and Fundamental Chemistry |
Phytostabilisation is a form of phytoremediation that uses hyperaccumulator plants for long-term stabilisation and containment of tailings, by sequestering pollutants in soil near the roots. The plants presence can reduce wind erosion, or the plants roots can prevent water erosion, immobilise metals by adsorption or accumulation, and provide a zone around the roots where the metals can precipitate and stabilise. Pollutants become less bioavailable and livestock, wildlife, and human exposure is reduced. This approach can be especially useful in dry environments, which are subject to wind and water dispersion. | 1 | Applied and Interdisciplinary Chemistry |
* In quaternary structure denaturation, protein sub-units are dissociated and/or the spatial arrangement of protein subunits is disrupted.
* Tertiary structure denaturation involves the disruption of:
** Covalent interactions between amino acid side-chains (such as disulfide bridges between cysteine groups)
** Non-covalent dipole-dipole interactions between polar amino acid side-chains (and the surrounding solvent)
** Van der Waals (induced dipole) interactions between nonpolar amino acid side-chains.
* In secondary structure denaturation, proteins lose all regular repeating patterns such as alpha-helices and beta-pleated sheets, and adopt a random coil configuration.
* Primary structure, such as the sequence of amino acids held together by covalent peptide bonds, is not disrupted by denaturation. | 1 | Applied and Interdisciplinary Chemistry |
The TTSI can be calculated with
from equilibrium serum or plasma concentrations of thyrotropin (TSH), free T4 (FT4) and the assay-specific upper limit of the reference interval for FT4 concentration (l). | 1 | Applied and Interdisciplinary Chemistry |
The radical decay time of NS alone is on the order of 1-3 ms. As evident by no change to this decay time upon addition of NO or O at ambient temperatures, the NS radical is unreactive with NO and O. However, rapid, first-order decay is observed with the addition of NO. This reaction is proposed to proceed through various intermediates, ultimately reaching final products of N and SO.
This rapid reaction occurs with a rate constant of k = (2.54 ± 0.12) × 10 cm molecules s at 295 K. By use of Density Functional Theory based computational calculations, the minima and transition states of the potential energy surface of this reaction have been predicted. | 0 | Theoretical and Fundamental Chemistry |
A Kingdon trap consists of a thin central wire, an outer cylindrical electrode and isolated end cap electrodes at both ends. A static applied voltage results in a radial logarithmic potential between the electrodes. In a Kingdon trap there is no potential minimum to store the ions; however, they are stored with a finite angular momentum about the central wire and the applied electric field in the device allows for the stability of the ion trajectories. In 1981, Knight introduced a modified outer electrode that included an axial quadrupole term that confines the ions on the trap axis. The dynamic Kingdon trap has an additional AC voltage that uses strong defocusing to permanently store charged particles. The dynamic Kingdon trap does not require the trapped ions to have angular momentum with respect to the filament. An Orbitrap is a modified Kingdon trap that is used for mass spectrometry. Though the idea has been suggested and computer simulations performed neither the Kingdon nor the Knight configurations were reported to produce mass spectra, as the simulations indicated mass resolving power would be problematic. | 0 | Theoretical and Fundamental Chemistry |
Trace fossils are generally difficult or impossible to assign to a specific maker. Only in very rare occasions are the makers found in association with their tracks. Further, entirely different organisms may produce identical tracks. Therefore, conventional taxonomy is not applicable, and a comprehensive form of taxonomy has been erected. At the highest level of the classification, five behavioral modes are recognized:
* Domichnia, dwelling structures reflecting the life position of the organism that created it.
* Fodinichnia, three-dimensional structures left by animals which eat their way through sediment, such as deposit feeders;
* Pascichnia, feeding traces left by grazers on the surface of a soft sediment or a mineral substrate;
* Cubichnia, resting traces, in the form of an impression left by an organism on a soft sediment;
* Repichnia, surface traces of creeping and crawling.
Fossils are further classified into form genera, a few of which are even subdivided to a "species" level. Classification is based on shape, form, and implied behavioural mode.
To keep body and trace fossils nomenclatorially separate, ichnospecies are erected for trace fossils. Ichnotaxa are classified somewhat differently in zoological nomenclature than taxa based on body fossils (see trace fossil classification for more information). Examples include:
*Late Cambrian trace fossils from intertidal settings include Protichnites and Climactichnites, amongst others
*Mesozoic dinosaur footprints including ichnogenera such as Grallator, Atreipus, and Anomoepus
*Triassic to Recent termite mounds, which can encompass several square kilometers of sediment | 1 | Applied and Interdisciplinary Chemistry |
Albert Jakob Eschenmoser (5 August 1925 – 14 July 2023) was a Swiss organic chemist, best known for his work on the synthesis of complex heterocyclic natural compounds, most notably vitamin B. In addition to his significant contributions to the field of organic synthesis, Eschenmoser pioneered work in the Origins of Life (OoL) field with work on the synthetic pathways of artificial nucleic acids. Before retiring in 2009, Eschenmoser held tenured teaching positions at the ETH Zurich and The Skaggs Institute for Chemical Biology at The Scripps Research Institute in La Jolla, California as well as visiting professorships at the University of Chicago, Cambridge University, and Harvard. | 0 | Theoretical and Fundamental Chemistry |
Inosine chemical erasing (ICE) refer to a process in which acrylonitrile is reacted with inosine to form N1-cyanoethylinosine (ce1I). This serves to stall reverse transcriptase and lead to truncated cDNA molecules. This was combined with deep-sequencing in a developed method called ICE-seq. Computational methods for automated analysis of the data are available, the main premise being the comparison of treated and untreated samples to identify truncated transcripts and thus infer an inosine modification by read count, with a step to reduce false positives by comparison to online database dbSNP. | 1 | Applied and Interdisciplinary Chemistry |
Although the optical transitions of the Si-V center preserve the electron spin, the rapid phonon-induced mixing between the Si-V orbital states causes spin decoherence. Yet it is possible to use the Si nuclear spin of the Si-V as a qubit for quantum information applications. | 0 | Theoretical and Fundamental Chemistry |
In 1994, Masri founded and now is the chairman of the board of Massar International, since the establishment of Massar, he has been one of the most prominent figures promoting private sector development and growth in Palestine.He has dedicated his life to establishing, investing, transforming, networking, training and building what is now a widely known group of businesses bridging Palestine to global technologies, knowledge, know-how and industry best practices. In the past decade, he has launched businesses in financial services, real estate, media and communications, retail businesses, agribusiness and information technology. | 1 | Applied and Interdisciplinary Chemistry |
CHAPS is a zwitterionic surfactant used in the laboratory to solubilize biological macromolecules such as proteins. It may be synthesized from cholic acid and is zwitterionic due to its quaternary ammonium and sulfonate groups; it is structurally similar to certain bile acids, such as taurodeoxycholic acid and taurochenodeoxycholic acid. It is used as a non-denaturing detergent in the process of protein purification and is especially useful in purifying membrane proteins, which are often sparingly soluble or insoluble in aqueous solution due to their native hydrophobicity.
CHAPS is an abbreviation for 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate. A related detergent, called CHAPSO, has the same basic chemical structure with an additional hydroxyl functional group; its full chemical name is 3-[(3-cholamidopropyl)dimethylammonio]-2-hydroxy-1-propanesulfonate. Both detergents have low light absorbance in the ultraviolet region of the electromagnetic spectrum, which is useful for monitoring ongoing chemical reactions or protein-protein binding with UV/Vis spectroscopy. | 1 | Applied and Interdisciplinary Chemistry |
Northwestern University researchers announced a solution to a primary problem of DSSCs, that of difficulties in using and containing the liquid electrolyte and the consequent relatively short useful life of the device. This is achieved through the use of nanotechnology and the conversion of the liquid electrolyte to a solid. The current efficiency is about half that of silicon cells, but the cells are lightweight and potentially of much lower cost to produce. | 0 | Theoretical and Fundamental Chemistry |
Standard temperature and pressure (STP) or Standard conditions for temperature and pressure are various standard sets of conditions for experimental measurements used to allow comparisons to be made between different sets of data. The most used standards are those of the International Union of Pure and Applied Chemistry (IUPAC) and the National Institute of Standards and Technology (NIST), although these are not universally accepted. Other organizations have established a variety of other definitions.
In industry and commerce, the standard conditions for temperature and pressure are often necessary for expressing the volumes of gases and liquids and related quantities such as the rate of volumetric flow (the volumes of gases vary significantly with temperature and pressure): standard cubic meters per second (Sm/s), and normal cubic meters per second (Nm/s).
However, many technical publications (books, journals, advertisements for equipment and machinery) simply state "standard conditions" without specifying them; often substituting the term with older "normal conditions", or "NC". In special cases this can lead to confusion and errors. Good practice always incorporates the reference conditions of temperature and pressure. If not stated, some room environment conditions are supposed, close to 1 atm pressure, 293 K (20 °C), and 0% humidity. | 0 | Theoretical and Fundamental Chemistry |
The C-terminal telopeptide (CTX), also known as carboxy-terminal collagen crosslinks, is the C-terminal telopeptide of fibrillar collagens such as collagen type I and type II. It is used as a biomarker in the serum to measure the rate of bone turnover. It can be useful in assisting clinicians to determine a patients nonsurgical treatment response as well as evaluate a patients risk of developing complications during healing following surgical intervention. The test used to detect the CTX marker is called the Serum CrossLaps, and it is more specific to bone resorption than any other test currently available. | 1 | Applied and Interdisciplinary Chemistry |
Irradiated mail is mail that has been deliberately exposed to radiation, typically in an effort to disinfect it. The most notable instance of mail irradiation in the US occurred in response to the 2001 anthrax attacks; the level of radiation chosen to kill anthrax spores was so high that it often changed the physical appearance of the mail.
The United States Postal Service began to irradiate mail in November 2001, in response to the discovery of large-scale contamination at several of its facilities that handled the letters that were sent in the attacks.
A facility in Bridgeport, New Jersey, operated by Sterigenics International, uses a Rhodotron continuous wave electron beam accelerator built by IBA Industrial, to irradiate the mail. A few facilities were planning to use cobalt-60 sources, though it is unclear whether this was ever done. | 0 | Theoretical and Fundamental Chemistry |
Time to obtain the test result is a key driver for these products. Tests results can be available in as little as a few minutes. Generally there is a trade off between time and sensitivity: more sensitive tests may take longer to develop. The other key advantage of this format of test compared to other immunoassays is the simplicity of the test, by typically requiring little or no sample or reagent preparation. | 1 | Applied and Interdisciplinary Chemistry |
In 1977, Carl Woese proposed dividing prokaryotes into the Bacteria and Archaea (originally Eubacteria and Archaebacteria) because of the major differences in the structure and genetics between the two groups of organisms. Archaea were originally thought to be extremophiles, living only in inhospitable conditions such as extremes of temperature, pH, and radiation but have since been found in all types of habitats. The resulting arrangement of Eukaryota (also called "Eucarya"), Bacteria, and Archaea is called the three-domain system, replacing the traditional two-empire system. | 1 | Applied and Interdisciplinary Chemistry |
It is however poorly soluble in solvents other than ammonia. Its use has been superseded by the related reagents sodium hydride, sodium bis(trimethylsilyl)amide (NaHMDS), and lithium diisopropylamide (LDA). | 0 | Theoretical and Fundamental Chemistry |
*[https://web.archive.org/web/20140210101323/http://s6.aeromech.usyd.edu.au/aero/cvanalysis/integral_approach.pdf Integral Approach to the Control Volume analysis of Fluid Flow] | 0 | Theoretical and Fundamental Chemistry |
A tertiary carbon atom is a carbon atom bound to three other carbon atoms. For this reason, tertiary carbon atoms are found only in hydrocarbons containing at least four carbon atoms. They are called saturated hydrocarbons because they only contain carbon-carbon single bonds. Tertiary carbons have a hybridization of sp3. Tertiary carbon atoms can occur, for example, in branched alkanes, but not in linear alkanes. | 0 | Theoretical and Fundamental Chemistry |
Importantly, the retina is immune-privileged, and thus does not experience a significant inflammation or immune-response when AAV is injected. Immune response to gene therapy vectors is what has caused previous attempts at gene therapy to fail, and is considered a key advantage of gene therapy in the eye. Re-administration has been successful in large animals, indicating that no long-lasting immune response is mounted.
Recent data indicates that the subretinal route may be subject to a greater degree of immune privilege compared to the intravitreal route. | 1 | Applied and Interdisciplinary Chemistry |
The field of organ printing stemmed from research in the area of stereolithography, the basis for the practice of 3D printing that was invented in 1984. In this early era of 3D printing, it was not possible to create lasting objects because of the material used for the printing process was not durable. 3D printing was instead used as a way to model potential end products that would eventually be made from different materials under more traditional techniques. In the beginning of the 1990s, nanocomposites were developed that allowed 3D printed objects to be more durable, permitting 3D printed objects to be used for more than just models. It was around this time that those in the medical field began considering 3D printing as an avenue for generating artificial organs. By the late 1990s, medical researchers were searching for biocompatible materials that could be used in 3D printing.
The concept of bioprinting was first demonstrated in 1988. At this time, a researcher used a modified HP inkjet printer to deposit cells using cytoscribing technology. Progress continued in 1999 when the first artificial organ made using bioprinting was printed by a team of scientist leads by Dr. Anthony Atala at the Wake Forest Institute for Regenerative Medicine. The scientists at Wake Forest printed an artificial scaffold for a human bladder and then seeded the scaffold with cells from their patient. Using this method, they were able to grow a functioning organ and ten years after implantation the patient had no serious complications.
After the bladder at Wake Forest, strides were taken towards printing other organs. In 2002, a miniature, fully functional kidney was printed. In 2003, Dr. Thomas Boland from Clemson University patented the use of inkjet printing for cells. This process utilized a modified spotting system for the deposition of cells into organized 3D matrices placed on a substrate. This printer allowed for extensive research into bioprinting and suitable biomaterials. For instance, since these initial findings, the 3D printing of biological structures has been further developed to encompass the production of tissue and organ structures, as opposed to cell matrices. Additionally, more techniques for printing, such as extrusion bioprinting, have been researched and subsequently introduced as a means of production.
In 2004, the field of bioprinting was drastically changed by yet another new bioprinter. This new printer was able to use live human cells without having to build an artificial scaffold first. In 2009, Organovo used this novel technology to create the first commercially available bioprinter. Soon after, Organovo's bioprinter was used to develop a biodegradable blood vessel, the first of its kind, without a cell scaffold.
In the 2010s and beyond, further research has been put forth into producing other organs, such as the liver and heart valves, and tissues, such as a blood-borne network, via 3D printing. In 2019, scientists in Israel made a major breakthrough when they were able to print a rabbit-sized heart with a network of blood vessels that were capable of contracting like natural blood vessels. The printed heart had the correct anatomical structure and function compared to real hearts. This breakthrough represented a real possibility of printing fully functioning human organs. In fact, scientists at the Warsaw Foundation for Research and Development of Science in Poland have been working on creating a fully artificial pancreas using bioprinting technology. As of today, these scientists have been able to develop a functioning prototype. This is a growing field and much research is still being conducted. | 1 | Applied and Interdisciplinary Chemistry |
Dicarbaboranes can be prepared from boron hydrides using alkynes as the source of the two carbon centers. In addition to the closo- series mentioned above, several open-cage dicarbon species are known including nido- (isostructural and isoelectronic with ) and arachno-.
Syntheses of icosahedral closo-dicarbadodecaborane derivatives () employ alkynes as the source and decaborane () to supply the unit. | 0 | Theoretical and Fundamental Chemistry |
GGT is predominantly used as a diagnostic marker for liver disease. Elevated serum GGT activity can be found in diseases of the liver, biliary system, pancreas and kidneys. Latent elevations in GGT are typically seen in patients with chronic viral hepatitis infections often taking 12 months or more to present.
Individual test results should always be interpreted using the reference range from the laboratory that performed the test, though example reference ranges are 15–85 IU/L for men, and 5–55 IU/L for women. GGT is similar to alkaline phosphatase (ALP) in detecting disease of the biliary tract. Indeed, the two markers correlate well, though there are conflicting data about whether GGT has better sensitivity. In general, ALP is still the first test for biliary disease. The main value of GGT is in verifying that ALP elevations are, in fact, due to biliary disease; ALP can also be increased in certain bone diseases, but GGT is not. | 1 | Applied and Interdisciplinary Chemistry |
Viscosity in gases arises principally from the molecular diffusion that transports momentum between layers of flow. An elementary calculation for a dilute gas at temperature and density gives
where is the Boltzmann constant, the molecular mass, and a numerical constant on the order of . The quantity , the mean free path, measures the average distance a molecule travels between collisions. Even without a priori knowledge of , this expression has nontrivial implications. In particular, since is typically inversely proportional to density and increases with temperature, itself should increase with temperature and be independent of density at fixed temperature. In fact, both of these predictions persist in more sophisticated treatments, and accurately describe experimental observations. By contrast, liquid viscosity typically decreases with temperature.
For rigid elastic spheres of diameter , can be computed, giving
In this case is independent of temperature, so . For more complicated molecular models, however, depends on temperature in a non-trivial way, and simple kinetic arguments as used here are inadequate. More fundamentally, the notion of a mean free path becomes imprecise for particles that interact over a finite range, which limits the usefulness of the concept for describing real-world gases. | 1 | Applied and Interdisciplinary Chemistry |
Dynorphin B, also known as rimorphin, is a form of dynorphin and an endogenous opioid peptide with the amino acid sequence Tyr-Gly-Gly-Phe-Leu-Arg-Arg-Gln-Phe-Lys-Val-Val-Thr. Dynorphin B is generated as a proteolytic cleavage product of leumorphin, which in turn is a cleavage product of preproenkephalin B (prodynorphin).
Dynorphin B has an identical N-terminal sequence, but different C-terminal sequence to Dynorphin A. In an alanine scan of the non-glycine residues of dynorphin B, it was discovered that Tyr and Phe residues are critical for both opioid receptor affinity and κ-opioid receptor agonist potency, Arg and Arg promote κ-opioid affinity and Lys contributes to the opioid receptor affinity. | 1 | Applied and Interdisciplinary Chemistry |
The energy efficiency and system capacity of systems designed for R-22 is slightly greater using R-22 than the available substitutes.
R-407A is for use in low- and medium-temp refrigeration. Uses a polyolester (POE) oil.
R-407C is for use in air conditioning. Uses a minimum of 20 percent POE oil.
R-407F and R-407H are for use in medium- and low-temperature refrigeration applications (supermarkets, cold storage, and process refrigeration); direct expansion system design only. They use a POE oil.
R-421A is for use in "air conditioning split systems, heat pumps, supermarket pak systems, dairy chillers, reach-in storage, bakery applications, refrigerated transport, self-contained display cabinets, and walk-in coolers." Uses mineral oil (MO), Alkylbenzene (AB), and POE.
R-422B is for use in low-, medium-, and high-temperature applications. It is not recommended for use in flooded applications.
R-422C is for use in medium- and low-temperature applications. The TXV power element will need to be changed to a 404A/507A element and critical seals (elastomers) may need to be replaced.
R-422D is for use in low-temp applications, and is mineral oil compatible.
R-424A is for use in air conditioning as well as medium-temp refrigeration temperature ranges of 20 to 50˚F. It works with MO, alkylbenzenes (AB), and POE oils.
R-427A is for use in air conditioning and refrigeration applications. It does not require all the mineral oil to be removed. It works with MO, AB, and POE oils.
R-434A is for use in water cooled and process chillers for air conditioning and medium- and low-temperature applications. It works with MO, AB, and POE oils.
R-438A (MO-99) is for use in low-, medium-, and high-temperature applications. It is compatible with all lubricants.
R-458A is for use in air conditioning and refrigeration applications, without capacity or efficiency loss. Works with MO, AB, and POE oils.
R-32 or HFC-32 (difluoromethane) is for use in air conditioning and refrigeration applications. It has zero ozone depletion potential (ODP) [2] and a global warming potential (GWP) index 675 times that of carbon dioxide. | 1 | Applied and Interdisciplinary Chemistry |
Acetalisation is the organic reaction that involves the formation of an acetal (or ketals). One way of acetal formation is the nucleophilic addition of an alcohol to a ketone or an aldehyde. Acetalisation is often used in organic synthesis to create a protecting group because it is a reversible reaction.
Acetalisation is acid catalysed with elimination of water; acetals do not form under basic conditions. The reaction can be driven to the acetal when water is removed from the reaction system either by azeotropic distillation or trapping water with molecular sieves or aluminium oxide.
The carbonyl group in 1 takes a proton from hydronium. The protonated carbonyl group 2 is activated for nucleophilic addition of the alcohol. The structures 2a and 2b are mesomers. After deprotonation of 3 by water the hemiacetal or hemiketal 4 is formed. The hydroxyl group in 4 is protonated leading to the oxonium ion 6 which accepts a second alcohol group to 7 with a final deprotonation to the acetal 8. The reverse reaction takes place by adding water in the same acidic medium. Acetals are stable towards basic media. In a transacetalisation or crossacetalisation a diol reacts with an acetal or two different acetals react with each other. Again this is possible because all the reaction steps are equilibria. | 0 | Theoretical and Fundamental Chemistry |
Viral (as well as some eukaryotic) 5′ UTRs contain internal ribosome entry sites, which is a cap-independent method of translational activation. Instead of building up a complex at the 5′ cap, the IRES allows for direct binding of the ribosomal complexes to the transcript to begin translation. The IRES enables the viral transcript to translate more efficiently due to the lack of needing a preinitation complex, allowing the virus to replicate quickly. | 1 | Applied and Interdisciplinary Chemistry |
The double bond of a glycal allows many other functional groups to be introduced into a monosaccharide. Like an alkene, a glycal can undergo electrophilic addition across the double bond to add in these new atoms such as halogens, epoxides, and nitrogen. The glycal double bond also allows a deoxy position (carbon in the ring that doesn’t have an oxygen bonded to it) to be easily introduced.
Glycals have many uses in synthetic carbohydrate chemistry. They are commonly used as glycosylation donors, meaning that they can react with other monosaccharides to form a longer chain of monosaccharides called an oligosaccharide.
Glycals can also have interesting applications in studying biological systems, particularly enzymes. D-glucal and radiolabelled D-galactal have been used to selectively bind with amino acids in the active sites of several enzymes. These enzyme-glycal complexes allow these amino acids that are essential for catalysis to be identified and allow for a better understanding of how these enzymes function. | 0 | Theoretical and Fundamental Chemistry |
Click Chemistry is a powerful tool to probe for the cellular localization of small molecules. Knowing where a small molecules goes in the cell gives powerful insights into their mechanisms of action. This approach has been used in numerous studies, and discoveries include that salinomycin localizes to lysosomes to initiate ferroptosis in cancer stem cells and that metformin derivatives accumulate in mitochondria to chelate copper(II), affecting metabolism and epigenetic changes downstream in inflammatory macrophages.
The commercial potential of click chemistry is great. The fluorophore rhodamine has been coupled onto norbornene, and reacted with tetrazine in living systems. In other cases, SPAAC between a cyclooctyne-modified fluorophore and azide-tagged proteins allowed the selection of these proteins in cell lysates.
Methods for the incorporation of click reaction partners into systems in and ex vivo contribute to the scope of possible reactions. The development of unnatural amino acid incorporation by ribosomes has allowed for the incorporation of click reaction partners as unnatural side groups on these unnatural amino acids. For example, an UAA with an azide side group provides convenient access for cycloalkynes to proteins tagged with this "AHA" unnatural amino acid. In another example, "CpK" has a side group including a cyclopropane alpha to an amide bond that serves as a reaction partner to tetrazine in an inverse diels-alder reaction.
The synthesis of luciferin exemplifies another strategy of isolating reaction partners, which is to take advantage of rarely-occurring, natural groups such as the 1,2-aminothiol, which appears only when a cysteine is the final N amino acid in a protein. Their natural selectivity and relative bioorthogonality is thus valuable in developing probes specific for these tags. The above reaction occurs between a 1,2-aminothiol and a 2-cyanobenzothiazole to make luciferin, which is fluorescent. This luciferin fluorescence can be then quantified by spectrometry following a wash, and used to determine the relative presence of the molecule bearing the 1,2-aminothiol. If the quantification of non-1,2-aminothiol-bearing protein is desired, the protein of interest can be cleaved to yield a fragment with a N Cys that is vulnerable to the 2-CBT.
Additional applications include:
*two-dimensional gel electrophoresis separation
*preparative organic synthesis of 1,4-substituted triazoles
*modification of peptide function with triazoles
*modification of natural products and pharmaceuticals
*natural product discovery
*drug discovery
*macrocyclizations using Cu(I) catalyzed triazole couplings
*modification of DNA and nucleotides by triazole ligation
*supramolecular chemistry: calixarenes, rotaxanes, and catenanes
*dendrimer design
*carbohydrate clusters and carbohydrate conjugation by Cu(1) catalyzed triazole ligation reactions
*polymers and biopolymers
*surfaces
*material science
*nanotechnology,
* bioconjugation, for example, azidocoumarin, and
*biomaterials
In combination with combinatorial chemistry, high-throughput screening, and building chemical libraries, click chemistry has hastened new drug discoveries by making each reaction in a multistep synthesis fast, efficient, and predictable. | 0 | Theoretical and Fundamental Chemistry |
Water body temperature is one of the most ubiquitous variables collected in aquatic biomonitoring. Temperatures at the water surface, through the water column, and in the lowest levels of the water body (benthic zone) can all provide insight into different aspects of an aquatic ecosystem. Water temperature is directly affected by climate change and can have negative affects on many aquatic species, such as salmon. Salmon spawning is temperature dependant: there is a heat accumulation threshold which must be reached before hatching can occur. Post-hatching, salmon live in water within a critical range in temperature, with exposure to temperatures outside of this being potentially lethal. This sensitivity makes them useful indicators of changes in water temperature, hence their use in climate change studies. Similarly, Daphnia populations have been evidenced as being negatively affected by climate change, as earlier springs have caused hatching periods to de-couple from the peak window of food availability. | 1 | Applied and Interdisciplinary Chemistry |
The tog is a measure of thermal insulance of a unit area, also known as thermal resistance. It is commonly used in the textile industry and often seen quoted on, for example, duvets and carpet underlay.
The Shirley Institute in Manchester, England developed the tog as an easy-to-follow alternative to the SI unit of m⋅K/W. The name comes from the informal word togs for clothing, which itself was probably derived from the word toga, a Roman garment. The backronym thermal overall grade is also attested.
The basic unit of insulation coefficient is the R, (1 m⋅K/W). 1 tog = 0.1 R. There is also a US clothing unit, the clo, equivalent to 0.155 R or 1.55 tog, described in ASTM D-1518.
A tog is 0.1⋅m⋅K/W. In other words, the thermal resistance in togs is equal to ten times the temperature difference (in °C) between the two surfaces of a material, when the flow of heat is equal to one watt per square metre.
British duvets are sold in steps of 1.5 tog from 3.0 tog (summer) to 16.5 tog (extra-warm). The stated values are a minimum; actual values may be up to 3 tog higher. Also, these values assume there is no added duvet cover that can trap air.
A few manufacturers have marketed combined duvet sets consisting of two duvets; one of approximately 4.5 tog and one of approximately 9.0 tog. These can be used individually as summer (4.5 tog) and spring/autumn (9.0 tog). When joined together using press studs around the edges, or Velcro strips across each of the corners, they become a 13.5 tog winter duvet and as such can be made to suit all seasons. | 0 | Theoretical and Fundamental Chemistry |
Amoxicillin was one of several semisynthetic derivatives of 6-aminopenicillanic acid (6-APA) developed by the Beecham Group in the 1960s. It was invented by Anthony Alfred Walter Long and John Herbert Charles Nayler, two British scientists. It became available in 1972 and was the second aminopenicillin to reach the market (after ampicillin in 1961). Co-amoxiclav became available in 1981. | 0 | Theoretical and Fundamental Chemistry |
Pseudouridine (Ψ, 5-ribosyluracil) is the most abundant RNA modification; in fact, at one time it was considered the "fifth nucleotide". This isomer of uridine is found in various types of RNA, such as snRNA, tRNA, small nucleolar RNA (snoRNA) and many others. Pseudouridine increases the stability of the modified RNA by making the sugar-phosphate backbone more rigid and by facilitating base stacking interactions (pseudouridine contains an extra hydrogen bond donor). When it comes to Watson-Crick base pair interactions, the pseudouridine-adenosine base pair is more stable than the uridine-adenosine base pair; therefore, pseudouridine increases stability. Apart from increasing RNA stability, this modification is also involved in regulation of translation. All eukaryotic stop codons contain one uridine (UAA, UGA and UGA); conversion of this uridine to pseudouridine results in suppression of translational termination and generation of unexpected sense codons. The artificial process of pseudouridylation has an effect on the function of mRNA: it changes the genetic code by making non-canonical base pairing possible in the ribosome decoding center.
Pseudouridylation reactions are catalyzed by enzymes that contain the pseudouridine synthase domain; 13 such enzymes have been identified in humans, which are called pseudouridine syntheses (PUS). These enzymes can be either RNA-dependent or RNA-independent depending on whether a small RNA is needed to guide the enzyme to its target or not. Additionally, different PUS enzymes work in different cell compartments. For instance, PUS4 (also known as TruB pseudouridine synthase family member 1, TRUB1) and PUS7, which are responsible for most of the mRNA pseudouridylation, are located in the nucleus or the cytoplasm. On the other hand, several PUS enzymes, such as PUS1 and TRUB2 are located in the mitochondria, modifying a number of mitochondrial mRNAs (mt-mRNAs). In tRNA, PUS1 and PUS7 modify the second uridine in the UGUAR consensus sequence, as long as this sequence is located in a very structured region of the tRNA.
To date, no pseudouridine erasers or readers have been identified. It is thought that pseudouridylation is most probably an irreversible process.
Pseudouridine is most commonly found in tRNAs, with almost all tRNA molecules having at least one pseudouridine. Therefore, because the addition of pseudouridine happens during the normal processing of tRNA, it is not considered an epitranscriptomic mark. However, pseudouridine acts as an epigenetic mark in mRNAs and ncRNAs of the brain, since pseudouridylation in these two RNAs responds dynamically to stress and differentiation in the cell, giving reason to believe that pseudouridylation may act as an important regulatory mechanism for RNA function. Pseudouridylation in mRNA can be conserved, tissue-specific or inducible, which reflects plasticity and regulatory function. Furthermore, expression of TRBU1, which is mostly expressed in the brain, goes up due to fear conditioning. In addition, expression of the ncRNAs needed to guide RNA-dependent PUS enzymes also goes up in response to fear. | 1 | Applied and Interdisciplinary Chemistry |
In 1643, the Italian physicist and mathematician, Evangelista Torricelli, who for a few months had acted as Galileos secretary, conducted a celebrated experiment in Florence. He demonstrated that a column of mercury in an inverted tube can be supported by the pressure of air outside of the tube, with the creation of a small section of vacuum above the mercury. This experiment essentially paved the way towards the invention of the barometer, as well as drawing the attention of Robert Boyle, then a "skeptical" scientist working in England. Boyle was inspired by Torricellis experiment to investigate how the elasticity of air responds to varying pressure, and he did this through a series of experiments with a setup reminiscent of that used by Torricelli. Boyle published his results in 1662.
Later on, in 1676, the French physicist Edme Mariotte, independently arrived at the same conclusions of Boyle, while also noting some dependency of air volume on temperature. However it took another century and a half for the development of thermometry and recognition of the absolute zero temperature scale, which eventually allowed the discovery of temperature-dependent gas laws. | 0 | Theoretical and Fundamental Chemistry |
The capillary length is a length scaling factor that relates gravity, density, and surface tension, and is directly responsible for the shape a droplet for a specific fluid will take. The capillary length stems from the Laplace pressure, using the radius of the droplet.
Using the capillary length we can define microdrops and macrodrops. Microdrops are droplets with radius smaller than the capillary length, where the shape of the droplet is governed by surface tension and they form a more or less spherical cap shape. If a droplet has a radius larger than the capillary length, they are known as macrodrops and the gravitational forces will dominate. Macrodrops will be flattened by gravity and the height of the droplet will be reduced. | 1 | Applied and Interdisciplinary Chemistry |
Used in hydrogeology, the groundwater flow equation is the mathematical relationship which is used to describe the flow of groundwater through an aquifer. The transient flow of groundwater is described by a form of the diffusion equation, similar to that used in heat transfer to describe the flow of heat in a solid (heat conduction). The steady-state flow of groundwater is described by a form of the Laplace equation, which is a form of potential flow and has analogs in numerous fields.
The groundwater flow equation is often derived for a small representative elemental volume (REV), where the properties of the medium are assumed to be effectively constant. A mass balance is done on the water flowing in and out of this small volume, the flux terms in the relationship being expressed in terms of head by using the constitutive equation called Darcy's law, which requires that the flow is laminar. Other approaches are based on Agent Based Models to incorporate the effect of complex aquifers such as karstic or fractured rocks (i.e. volcanic) | 1 | Applied and Interdisciplinary Chemistry |
Electric trace heating began in the 1930s but initially no dedicated equipment was available. Mineral insulated cables ran at high current densities to produce heat, and control equipment was adapted from other applications. Mineral-insulated resistance heating cable was introduced in the 1950s, and parallel-type heating cables that could be cut to length in the field became available. Self-limiting thermoplastic cables were marketed in 1971.
Control systems for trace heating systems developed from capillary filled-bulb thermostats and contactors in the 1970s to networked computerized controls in the 1990s, in large systems that require centralized control and monitoring.
One paper projected that between 2000 and 2010 trace heating would account for 100 megawatts of connected load, and that trace heating and insulation would account for up to CAD $700 million capital investment in the Alberta oil sands.
International standards applied in the design and installation of electric trace heating systems include IEEE standards 515 and 622, British standard BS 6351, and IEC standard 60208. | 1 | Applied and Interdisciplinary Chemistry |
Technologically, colloidal crystals have found application in the world of optics as photonic band gap (PBG) materials (or photonic crystals). Synthetic opals as well as inverse opal configurations are being formed either by natural sedimentation or applied forces, both achieving similar results: long-range ordered structures which provide a natural diffraction grating for lightwaves of wavelength comparable to the particle size.
Novel PBG materials are being formed from opal-semiconductor-polymer composites, typically utilizing the ordered lattice to create an ordered array of holes (or pores) which is left behind after removal or decomposition of the original particles. Residual hollow honeycomb structures provide a relative index of refraction (ratio of matrix to air) sufficient for selective filters. Variable index liquids or liquid crystals injected into the network alter the ratio and band gap.
Such frequency-sensitive devices may be ideal for optical switching and frequency selective filters in the ultraviolet, visible, or infrared portions of the spectrum, as well as higher efficiency antennae at microwave and millimeter wave frequencies. | 0 | Theoretical and Fundamental Chemistry |
Hexahydroxybenzene trisoxalate is a chemical compound, an oxide of carbon with formula . Its molecule consists of a benzene core with the six hydrogen atoms replaced by three oxalate groups. It can be seen as a sixfold ester of benzenehexol and oxalic acid.
The compound was first described by H. S. Verter and R. Dominic in 1967. | 0 | Theoretical and Fundamental Chemistry |
Sigma non-innocence has been extensively discussed for the prototypical example of a copper complex [Cu(CF)] in conjunction with the concept of an inverted ligand field. In 1995, Snyder suggested, based on his quantum chemical calculations, that this formal Cu(III) (d) complex would be more appropriately represented as a Cu(I) (d) complex. Snyder pointed out that the frontier molecular orbitals of [Cu(CF)] are dominated by ligand parentage due to the higher-lying ligand orbitals compared to the metal orbitals, and this inversion of the ligand field causes the d orbital to be occupied and the lowest unoccupied molecular orbital (LUMO) to be ligand centered.
Later, Lancaster et al. experimentally validated this inverted ligand field electronic structure of [Cu(CF)] using core spectroscopy techniques. Their findings revealed that the 3d orbitals are nearly fully occupied, supporting the formulation of this ion as a Cu(I) species. The assignment of what would be typically called a Cu(III) species as Cu(I) indicates the sigma non-innocence of the perfluoromethyl ligands in the complex.
The researchers also examined the electronic structure of other formally Cu(III) complexes using Cu L-edge X-ray absorption spectroscopy together with computational techniques. They reported that all the Cu(III) species they studied except CuF have significantly diminished metal d-character in their LUMOs compared to the formal d assignment. This implies that ligand field inversion and sigma non-innocence are not unique to [Cu(CF)] but is general in many systems. | 0 | Theoretical and Fundamental Chemistry |
Zero Carbon World were one of the Sponsors of the 2012 Bath Film Festival which included a showing of Revenge of the Electric Car. | 1 | Applied and Interdisciplinary Chemistry |
Hazards in water distribution systems can be in the forms of microbial, chemical and physical.
Most microorganisms are harmless within water distribution systems. However, when infectious microorganisms enter the systems, they form biofilms and create microbial hazards to the users. Biofilms are usually formed near the end of the distribution where the water circulation is low. This supports their growth and makes disinfection agents less effective. Common microbial hazards in distribution systems come from contamination of human faecal pathogens and parasites which enter the systems through cross-connections, breaks, water main works, and open storage tanks.
Chemical hazards are those of disinfection by-products, leaching of piping materials and fittings, and water treatment chemicals.
Physical hazards include turbidity of water, odors, colors, scales which are buildups of materials inside the pipes from corrosions, and sediment resuspension.
There are several bodies around the world that create standards to limit hazards in the distribution systems: NSF International in North America; European Committee for Standardization, British Standards Institution and Umweltbundesamt in Europe; Japanese Standards Association in Asia; Standards Australia in Australia; and Brazilian National Standards Organization in Brazil. | 1 | Applied and Interdisciplinary Chemistry |
If two systems, and , have identical intensive variables, a thermodynamic operation of wall removal can compose them into a single system, , with the same intensive variables. If, for example, their internal energies are in the ratio , then the composed system, , has internal energy in the ratio of to that of the system . By the inverse thermodynamic operation, the system can be split into two subsystems in the obvious way. As usual, these thermodynamic operations are conducted in total ignorance of the microscopic states of the systems. More particularly, it is characteristic of macroscopic thermodynamics that the probability vanishes, that the splitting operation occurs at an instant when system is in the kind of extreme transient microscopic state envisaged by the Poincaré recurrence argument. Such splitting and recomposition is in accord with the above defined additivity of extensive variables. | 0 | Theoretical and Fundamental Chemistry |
* Types of air pollutant emission sources – named for their characteristics
** Sources, by shape – there are four basic shapes which an emission source may have. They are:
*** Point source – single, identifiable source of air pollutant emissions (for example, the emissions from a combustion furnace flue gas stack). Point sources are also characterized as being either elevated or at ground-level. A point source has no geometric dimensions.
*** Line source – one-dimensional source of air pollutant emissions (for example, the emissions from the vehicular traffic on a roadway).
*** Area source – two-dimensional source of diffuse air pollutant emissions (for example, the emissions from a forest fire, a landfill or the evaporated vapors from a large spill of volatile liquid).
*** Volume source – three-dimensional source of diffuse air pollutant emissions. Essentially, it is an area source with a third (height) dimension (for example, the fugitive gaseous emissions from piping flanges, valves and other equipment at various heights within industrial facilities such as oil refineries and petrochemical plants). Another example would be the emissions from an automobile paint shop with multiple roof vents or multiple open windows.
** Sources, by motion
*** Stationary source – flue gas stacks are examples of stationary sources
*** Mobile source – buses are examples of mobile sources
** Sources, by urbanization level – whether the source is within a city or not is relevant in that urban areas constitute a so-called heat island and the heat rising from an urban area causes the atmosphere above an urban area to be more turbulent than the atmosphere above a rural area
*** Urban source – emission is in an urban area
*** Rural source – emission is in a rural area
** Sources, by elevation
*** Surface or ground-level source
*** Near surface source
*** Elevated source
** Sources, by duration
*** Puff or intermittent source – short term sources (for example, many accidental emission releases are short term puffs)
*** Continuous source – long term source (for example, most flue gas stack emissions are continuous) | 1 | Applied and Interdisciplinary Chemistry |
Forming acyliminium ions from α-hydroxyamides can be done using methanesulfonyl chloride and a base, typically triethylamine. | 0 | Theoretical and Fundamental Chemistry |
Acid-neutralizing capacity or ANC in short is a measure for the overall buffering capacity against acidification of a solution, e.g. surface water or soil water.
ANC is defined as the difference between cations of strong bases and anions of strong acids (see below), or dynamically as the amount of acid needed to change the pH value from the sample's value to a chosen different value. The concepts alkalinity are nowadays often used as a synonym to positive ANC and similarly acidity is often used to mean negative ANC. Alkalinity and acidity however also have definitions based on an experimental setup (titration).
ANC is often used in models to calculate acidification levels from acid rain pollution in different geographical areas, and as a basis for calculating critical loads for forest soils and surface waters.
The relation between pH and ANC in natural waters depends on three conditions: Carbon dioxide, organic acids and aluminium solubility. The amount of dissolved carbon dioxide is usually higher than would be the case if there was an equilibrium with the carbon dioxide pressure in the atmosphere. This is due to biological activity: Decomposition of organic material releases carbon dioxide and thus increases the amount of dissolved carbon dioxide. An increase in carbon dioxide decreases pH but has no effect on ANC. Organic acids, often expressed as dissolved organic carbon (DOC), also decrease pH and have no effect on ANC. Soil water in the upper layers usually have higher organic content than the lower soil layers. Surface waters with high DOC are typically found in areas where there is a lot of peat and bogs in the catchment. Aluminium solubility is a bit tricky and there are several curve fit variants used in modelling, one of the more common being
In the illustration to the right, the relation between pH and ANC is shown for four different solutions. In the blue line the solution has 1 mg/L DOC, a dissolved amount of carbon dioxide that is equivalent to a solution being in equilibrium with an atmosphere with twice the carbon dioxide pressure of our atmosphere. For the other lines, all three parameters except one is the same as for the blue line. Thus the orange line is a solution loaded with organic acids, having a DOC of 80 mg/L (typically very brown lake water or water in the top soil layer in a forest soil). The red line has a high amount of dissolved carbon dioxide (pCO=20 times ambient), a level that is not uncommon in ground water. Finally the black dotted line is a water with a lower aluminium solubility.
The reason why ANC is often defined as the difference between cations of strong bases and anions of strong acids is that ANC is derived from a charge balance: If we for simplicity consider a solution with only a few species and use the fact that a water solution is electrically neutral we get
where R denote an anion of an organic acid. ANC is then defined by collecting all species controlled by equilibrium (i.e. species related to weak acids and weak bases) on one side and species not controlled by equilibrium (i.e. species related to strong acids and strong bases) on the other side. Thus, with the species above we get
or | 1 | Applied and Interdisciplinary Chemistry |
Wiggins studied science at the University of Canterbury, but although she wanted to continue in physics, women at the university were not allowed to progress past stage one. Having switched to chemistry, Wiggins then won a scholarship to research at the Davy-Faraday Laboratory at the Royal Institution in London. She then completed a PhD at King's College London. Wiggins took time off to have a family and did not return to full-time work until the age of 48.
Upon returning to New Zealand, Wiggins worked at the University of Canterbury with Walter Metcalf from 1962–1966. After this she worked at the University of Otago, and began working on water in living cells.
Wiggins was awarded a Career Fellowship by the New Zealand Medical Research Council. From 1970, she continued her research in the Department of Medicine at the University of Auckland, as Professor of Membrane Physiology.
In 1994 Wiggins co-founded BiostoreNZ, which commercialised preservation and storage technology for cells. BiostoreNZ was later acquired by Genesis Research and Development. Wiggins worked as a research scientist for Genesis Research in 1997, and continued to publish until 2009. She held more than 40 patents.
Wiggins died in Auckland on 16 March 2017 aged 91. | 0 | Theoretical and Fundamental Chemistry |
In these processes, iron ore is brought into contact with reducing gases produced and heated by a separate plant in a closed enclosure. As a result, these processes are naturally suited to the use of natural gas. | 1 | Applied and Interdisciplinary Chemistry |
*ACVR1 NM_001105 similar to ACVRL1 TGF Beta receptor family Rendu-Osler-Weber syndrome
*ACVR1B NM_004302
*CD23 FCER2 low affinity IgE receptor (lectin) | 1 | Applied and Interdisciplinary Chemistry |
There are two main views on the derivation of the Greek word. According to one, the word comes from the greek χημεία, pouring, infusion, used in connexion with the study of the juices of plants, and thence extended to chemical manipulations in general; this derivation accounts for the old-fashioned spellings "chymist" and "chymistry". The other view traces it to khem or khame, hieroglyph khmi, which denotes black earth as opposed to barren sand, and occurs in Plutarch as χημεία; on this derivation alchemy is explained as meaning the "Egyptian art". The first occurrence of the word is said to be in a treatise of Julius Firmicus, an astrological writer of the 4th century, but the prefix al there must be the addition of a later Arabic copyist. In English, Piers Plowman (1362) contains the phrase "experimentis of alconomye", with variants "alkenemye" and " alknamye". The prefix al began to be dropped about the middle of the 16th century (further details of which are given below). | 1 | Applied and Interdisciplinary Chemistry |
In the Copper Country region of the Upper Peninsula of Michigan, the rock was reduced to fragments because further crushing would not result in enough additional copper recovery to be economical. The sand was then usually disposed near the mill. As mills often relied on steam power to operate and water for some of the processing methods, they were built on the shore of lakes and rivers. The stamp sand was thus dumped into the water, sometimes growing deep enough to create entirely new land. Stamp sand discarded into the water was sometimes reclaimed with dredges to be re-stamped when more efficient stamping technology was developed (for example, Quincy Dredge Number Two).
Stamp sand may be hazardous to human health, since it contains trace amounts of harmful heavy metals (such as arsenic). For this reason, land created from stamp sand may be poisonous to plant life, and can pollute nearby water as well. For example, aquatic life in the Keweenaw Waterway, near the Keweenaw copper mines of Michigan, has declined significantly near stamp sand deposits, while the waterway is reasonably healthy in other areas. Several stamp sand dumps have been designated as Superfund sites to remove or contain the sands. Some stamp sand land has been covered with clean fill dirt and used for housing developments.
The coarseness of the sand has led to its use in place of (or in combination with) road salt in some areas, such as the Copper Country of Michigan. Typically, only stamp sand which has not been chemically processed is used, due to environmental concerns. In addition, some companies have developed methods to reprocess stamp sands to reclaim their small mineral content. | 1 | Applied and Interdisciplinary Chemistry |
Wind stress in one of the drivers of the large-scale ocean circulation with other drivers being the gravitational pull exerted by the Moon and Sun, differences in atmospheric pressure at sea level and convection resulting from atmospheric cooling and evaporation. However, the contribution of the wind stress to the forcing of the oceanic general circulation is largest. Ocean waters respond to the wind stress because of their low resistance to shear and the relative consistence with which winds blow over the ocean. The combination of easterly winds near the equator and westerly winds at midlatitudes drives significant circulations in the North and South Atlantic Oceans, the North and South Pacific Oceans and the Indian Ocean with westward currents near the equator and eastward currents at midlatitudes. This results in characteristic gyre flows in the Atlantic and Pacific consisting of a subpolar and subtropical gyre. The strong westerlies in the Southern ocean drive the Antarctic Circumpolar Current which is the dominant current in the Southern Hemisphere whereof no comparable current exists in the Northern Hemisphere.
The equations to describe large-scale ocean dynamics were formulated by Harald Sverdrup and came to be known as Sverdrup dynamics. Important is the Sverdrup balance which describes the relation between the wind stress and the vertically integrated meridional transport of water. Other significant contributions to the description of large-scale ocean circulation were made by Henry Stommel who formulated the first correct theory for the Gulf Stream and theories of the abyssal circulation. Long before these theories were formulated, mariners have been aware of the major surface ocean currents. As an example, Benjamin Franklin already published a map of the Gulf Stream in 1770 and in European discovery of the gulf stream dates back to the 1512 expedition of Juan Ponce de León. Apart from such hydrographic measurement there are two methods to measure the ocean currents directly. Firstly, the Eulerian velocity can be measured using a current meter along a rope in the water column. And secondly, a drifter can be used which is an object that moves with the currents whereof the velocity can be measured. | 1 | Applied and Interdisciplinary Chemistry |
According to cohesion-tension theory, water transport in xylem relies upon the cohesion of water molecules to each other and adhesion to the vessels wall via hydrogen bonding combined with the high water pressure of the plants substrate and low pressure of the extreme tissues (usually leaves).
As in blood circulation in animals, (gas) embolisms may form within one or more xylem vessels of a plant. If an air bubble forms, the upward flow of xylem water will stop because the pressure difference in the vessel cannot be transmitted. Once these embolisms are nucleated , the remaining water in the capillaries begins to turn to water vapor. When these bubbles form rapidly by cavitation, the "snapping" sound can be used to measure the rate of cavitation within the plant . Plants do, however, have physiological mechanisms to reestablish the capillary action within their cells . | 1 | Applied and Interdisciplinary Chemistry |
Affinitymagnetic separation (AMS) is a laboratory tool that can efficiently isolate bacterial cells out of body fluid or cultured cells. It can also be used as a method of quantifying the pathogenicity of food, blood or feces. Another laboratory separation tool is the immunomagnetic separation (IMS), which is more suitable for the isolation of eucaryotic cells. | 1 | Applied and Interdisciplinary Chemistry |
In step-growth polymerization, the Carothers equation (or Carothers' equation) gives the degree of polymerization, , for a given fractional monomer conversion, .
There are several versions of this equation, proposed by Wallace Carothers, who invented nylon in 1935. | 0 | Theoretical and Fundamental Chemistry |
In general, "FRET" refers to situations where the donor and acceptor proteins (or "fluorophores") are of two different types. In many biological situations, however, researchers might need to examine the interactions between two, or more, proteins of the same type—or indeed the same protein with itself, for example if the protein folds or forms part of a polymer chain of proteins or for other questions of quantification in biological cells or in vitro experiments.
Obviously, spectral differences will not be the tool used to detect and measure FRET, as both the acceptor and donor protein emit light with the same wavelengths. Yet researchers can detect differences in the polarisation between the light which excites the fluorophores and the light which is emitted, in a technique called FRET anisotropy imaging; the level of quantified anisotropy (difference in polarisation between the excitation and emission beams) then becomes an indicative guide to how many FRET events have happened.
In the field of nano-photonics, FRET can be detrimental if it funnels excitonic energy to defect sites, but it is also essential to charge collection in organic and quantum-dot-sensitized solar cells, and various FRET-enabled strategies have been proposed for different opto-electronic devices. It is then essential to understand how isolated nano-emitters behave when they are stacked in a dense layer. Nanoplatelets are especially promising candidates for strong homo-FRET exciton diffusion because of their strong in-plane dipole coupling and low Stokes shift. Fluorescence microscopy study of such single chains demonstrated that energy transfer by FRET between neighbor platelets causes energy to diffuse over a typical 500-nm length (about 80 nano emitters), and the transfer time between platelets is on the order of 1 ps. | 1 | Applied and Interdisciplinary Chemistry |
Eventually, quantitative experiments revealed problems, including the fact that some metals gained weight after they burned, even though they were supposed to have lost phlogiston.
Some phlogiston proponents, like Robert Boyle, explained this by concluding that phlogiston has negative mass; others, such as Louis-Bernard Guyton de Morveau, gave the more conventional argument that it is lighter than air. However, a more detailed analysis based on Archimedes' principle, the densities of magnesium and its combustion product showed that just being lighter than air could not account for the increase in weight. Stahl himself did not address the problem of the metals that burn gaining weight, but those who followed his school of thought were the ones that worked on this problem.
During the eighteenth century, as it became clear that metals gained weight after they were oxidized, phlogiston was increasingly regarded as a principle rather than a material substance. By the end of the eighteenth century, for the few chemists who still used the term phlogiston, the concept was linked to hydrogen. Joseph Priestley, for example, in referring to the reaction of steam on iron, while fully acknowledging that the iron gains weight after it binds with oxygen to form a calx, iron oxide, iron also loses "the basis of inflammable air (hydrogen), and this is the substance or principle, to which we give the name phlogiston". Following Lavoisiers description of oxygen as the oxidizing principle (hence its name, from Ancient Greek: , "sharp"; , "birth" referring to oxygens supposed role in the formation of acids), Priestley described phlogiston as the alkaline principle.
Phlogiston remained the dominant theory until the 1770s when Antoine-Laurent de Lavoisier showed that combustion requires a gas that has weight (specifically, oxygen) and could be measured by means of weighing closed vessels. The use of closed vessels by Lavoisier and earlier by the Russian scientist Mikhail Lomonosov also negated the buoyancy that had disguised the weight of the gases of combustion, and culminated in the principle of mass conservation. These observations solved the mass paradox and set the stage for the new oxygen theory of combustion. The British chemist Elizabeth Fulhame demonstrated through experiment that many oxidation reactions occur only in the presence of water, that they directly involve water, and that water is regenerated and is detectable at the end of the reaction. Based on her experiments, she disagreed with some of the conclusions of Lavoisier as well as with the phlogiston theorists that he critiqued. Her book on the subject appeared in print soon after Lavoisier's execution for Farm-General membership during the French Revolution.
Experienced chemists who supported Stahl's phlogiston theory attempted to respond to the challenges suggested by Lavoisier and the newer chemists. In doing so, phlogiston theory became more complicated and assumed too much, contributing to the overall demise of the theory. Many people tried to remodel their theories on phlogiston to have the theory work with what Lavoisier was doing in his experiments. Pierre Macquer reworded his theory many times, and even though he is said to have thought the theory of phlogiston was doomed, he stood by phlogiston and tried to make the theory work. | 1 | Applied and Interdisciplinary Chemistry |
New technologies in genomics have changed the way researchers approach both basic and translational research. With approaches such as exome sequencing, it is possible to significantly enhance the data generated from individual genomes which has put forth a series of questions on how to deal with the vast amount of information. Should the individuals in these studies be allowed to have access to their sequencing information? Should this information be shared with insurance companies? This data can lead to unexpected findings and complicate clinical utility and patient benefit. This area of genomics still remains a challenge and researchers are looking into how to address these questions. | 1 | Applied and Interdisciplinary Chemistry |
Polyionic polymers are polymers with an ionic functional group. The ionic charges prevent the formation of tightly coiled polymer chains. This allows them to contribute more to viscosity in their stretched state, because the stretched-out polymer takes up more space. This is also the reason gel hardens. See polyelectrolyte for more information. | 0 | Theoretical and Fundamental Chemistry |
The E. coli strain W3110 was genetically engineered to generate 2 moles of acetate for every 1 mole of glucose that undergoes fermentation. This is known as a homoacetate pathway. | 1 | Applied and Interdisciplinary Chemistry |
The β-selective agonists were developed in the 20th century and are a very valuable class of drugs. In 1901 Jōkichi Takamine isolated the hormone adrenalin, also known as epinephrine. In 1890 adrenalin was first given to asthma patients orally. It had little or no effect because it is metabolized in the digestive tract and is deactivated. In 1930 epinephrine was for the first time given subcutaneously and was discovered to have a positive effect on asthma. When given subcutaneously adrenalin affects the whole body, giving various side effects and thus reducing the value of this treatment. The inhaled route was later tried and it gave much less adverse effects, but still had inconvenient side effects like fear, anxiety, restlessness, headache, dizziness and palpitation.
In 1940 isoproterenol (isoprenaline) was discovered. This compound had a similar effect as adrenalin but fewer side effects were found. In 1949 isoproterenol was used generally to treat asthma patients, given sublingually or inhaled. The first pressurized metered-dose inhaler was introduced in 1956. This was much more convenient for patients than the previously used squeeze-bulb inhalers. The pressurized metered-dose inhaler technique developed rapidly in the 1970s.
In 1967, it was shown that the β-receptor was responsible for bronchodilation and this led to development of more selective drugs. In 1961 orciprenaline, a longer acting β-agonist was found, but it was not as potent as isoproterenol. Orciprenaline does not have the catechol structure which was the reason for the longer action time. In the mid-1960s, albuterol or salbutamol was discovered, followed by tributalin and fenoterol a few years later. Albuterol and terbutaline gave fewer side effects, such as increased heart rate, than isoproterenol. The pharmaceutical company Glaxo discovered salmeterol, a long-acting β-agonist that had bronchodilation activity for up to 12 hours. It was marketed in 1990. Formoterol, another long-acting β-agonist, was marketed shortly after. This long duration of action made the treatment for severe asthma and COPD more convenient for the patients because it is inhaled twice a day.
In 2013 an extra long-acting β-agonist, vilanterol, was marketed. Its duration of action lasts for 24 hours which should improve patients' compliance and make the treatment more convenient. | 1 | Applied and Interdisciplinary Chemistry |
The single-cell eukaryote Paramecium tetraurelia can undergo both asexual and sexual reproduction. Asexual or clonal reproduction occurs by binary fission. Binary fission involves mitosis-like behavior of the chromosomes similar to that of cells in higher organisms. The sexual forms of reproduction are autogamy, a kind of self-fertilization, and conjugation, a kind of sexual interation between different cells. Clonal asexual reproduction can be initiated after completion of autogamy or conjugation. P. tetraurelia is able to replicate asexually for many generations but the dividing cells gradually age and after about 200 cell divisions, if the cells fail to undergo another autogamy or conjugation, they lose vitality and expire. This process is referred to as clonal aging. Experiments by Smith-Sonneborn, Holmes and Holmes and Gilley and Blackburn showed that accumulation of DNA damage is the likely cause of clonal aging in P. tetraurelia. This aging process has similarities to the aging process in multicellular eukaryotes (See DNA damage theory of aging). | 1 | Applied and Interdisciplinary Chemistry |
Since its invention by Dr. John T. Gleaves (then at Monsanto Company) in late 1980s,
TAP has been used to study a variety of industrially and academically relevant catalytic reactions, bridging the gap between surface science
experiments and applied catalysis.
The state-of-the-art TAP installations (TAP-3) do not only provide better signal-to-noise ratio than the first generation TAP machines (TAP-1),
but also allow for advanced automation and direct coupling with other techniques. | 0 | Theoretical and Fundamental Chemistry |
Protein arginine N-methyltransferase-4 (PRMT4/CARM1) methylation of arginine residues within proteins plays a critical key role in transcriptional regulation (see the PRMT4 pathway on the left). PRMT4 binds to the classes of transcriptional activators known as p160 and CBP/p300. The modified forms of these proteins are involved in stimulation of gene expression via steroid hormone receptors. Significantly, PRMT4 methylates core histones H3 and H4, which are also targets of the histone acetylase activity of CBP/p300 coactivators. PRMT4 recruitment of chromatin by binding to coactivators increases histone methylation and enhances the accessibility of promoter regions for transcription. Methylation of the transcriptional coactivator CBP by PRMT4 inhibits binding to CREB and thereby partitions the limited cellular pool of CBP for steroid hormone receptor interaction. | 1 | Applied and Interdisciplinary Chemistry |
Most cell types take up iron primarily through receptor-mediated endocytosis via transferrin receptor 1 (TFR1), transferrin receptor 2 (TFR2) and GAPDH. TFR1 has a 30-fold higher affinity for transferrin-bound iron than TFR2 and thus is the main player in this process. The higher order multifunctional glycolytic enzyme glyceraldehyde-3-phosphate dehydrogenase (GAPDH) also acts as a transferrin receptor. Transferrin-bound ferric iron is recognized by these transferrin receptors, triggering a conformational change that causes endocytosis. Iron then enters the cytoplasm from the endosome via importer DMT1 after being reduced to its ferrous state by a STEAP family reductase.
Alternatively, iron can enter the cell directly via plasma membrane divalent cation importers such as DMT1 and ZIP14 (Zrt-Irt-like protein 14). Again, iron enters the cytoplasm in the ferrous state after being reduced in the extracellular space by a reductase such as STEAP2, STEAP3 (in red blood cells), Dcytb (in enterocytes) and SDR2. | 1 | Applied and Interdisciplinary Chemistry |
Subsets and Splits