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Amongst members of the ETS family, there is extensive conservation in the DNA-binding ETS domain and, therefore, a lot of redundancy in DNA binding. It is thought that interactions with other proteins (eg: Modulator of the activity of Ets called Mae) is one way in which specific binding to DNA is achieved. Transcription factor Ets are a site of signalling convergence.
ETS factors act as transcriptional repressors, transcriptional activators, or both. | 1 | Biochemistry |
During elongation, RNA polymerase slides down the double stranded DNA, unwinding it and transcribing (copying) its nucleotide sequence into newly synthesized RNA. The movement of the RNA-DNA complex is essential for the catalytic mechanism of RNA polymerase. Additionally, RNA polymerase increases the overall stability of this process by acting as a link between the RNA and DNA strands. New nucleotides that are complementary to the DNA template strand are added to the 3 end of the RNA strand. The newly formed RNA strand is practically identical to the DNA coding strand (sense strand or non-template strand), except it has uracil substituting thymine, and a ribose sugar backbone instead of a deoxyribose sugar backbone. Because nucleoside triphosphates (NTPs) need to attach to the OH- molecule on the 3 end of the RNA, transcription always occurs in the 5 to 3 direction. The four NTPs are adenosine-5-triphosphate (ATP), guanoside-5-triphosphate (GTP), uridine-5-triphosphate (UTP), and cytidine-5-triphosphate (CTP). The attachment of NTPs onto the 3' end of the RNA transcript provides the energy required for this synthesis. NTPs are also energy producing molecules that provide the fuel that drives chemical reactions in the cell.
Multiple RNA polymerases can be active at once, meaning many strands of mRNA can be produced very quickly. RNA polymerase moves down the DNA rapidly at approximately 40 bases per second. Due to the quick nature of this process, DNA is continually unwound ahead of RNA polymerase and then rewound once RNA polymerase moves along further. The polymerase has a proofreading mechanism that limits mistakes to about 1 in 10,000 nucleotides transcribed. RNA polymerase has lower fidelity (accuracy) and speed than DNA polymerase. DNA polymerase has a very different proofreading mechanism that includes exonuclease activity, which contributes to the higher fidelity. The consequence of an error during RNA synthesis is usually harmless, where as an error in DNA synthesis could be detrimental.
The promoter sequence determines the frequency of transcription of its corresponding gene. | 1 | Biochemistry |
Yu is an organic synthetic chemist who develops of new methods for functionalizing carbon-hydrogen (C–H) bonds, or C–H activation. A longstanding goal in organic synthesis, C–H activation would allow for inert, unreactive C–H bonds to be replaced with bonds to functional groups that can alter a molecule's reactivity and properties. One strategy to achieve selective C–H activation under mild conditions is to use metal-based catalysts that are guided to the targeted C–H bond by nearby directing functional groups. These directing groups often must be removed once the new functional group has been appended to the molecule. This style of C–H activation methodology could greatly simplify the synthesis of pharmaceutical drug molecules, agrochemicals, and natural products.
Yu has contributed metal palladium-catalyzed C-H bond activation promoted by "weak coordination," that is by directing group effects. Other areas of interest are the development of remote C-H bond activation, for example at the meta-position to a directing group. Since many drugs and natural products are chiral, Yu has also developed important asymmetric C-H bond activation reactions, including those templated by modified amino acids that can act as transient, chiral directing groups. | 0 | Organic Chemistry |
* Clinistrips quantitatively test for sugar in urine
* The Kastle-Meyer test tests for the presence of hemoglobin
* Salicylate testing is a category of drug testing that is focused on detecting salicylates such as acetylsalicylic acid for either biochemical or medical purposes.
* The Phadebas test tests for the presence of saliva for forensic purposes
* Iodine solution tests for starch
* The Van Slyke determination tests for specific amino acids
* The Zimmermann test tests for ketosteroids
* Seliwanoff's test differentiates between aldose and ketose sugars
* Test for lipids: add ethanol to sample, then shake; add water to the solution, and shake again. If fat is present, the product turns milky white.
*The Sakaguchi test detects the presence of arginine in protein
*The Hopkins–Cole reaction tests for the presence of tryptophan in proteins
*The nitroprusside reaction tests for the presence of free thiol groups of cysteine in proteins
*The Sullivan reaction tests for the presence of cysteine and cystine in proteins
*The Acree–Rosenheim reaction tests for the presence of tryptophan in proteins
*The Pauly reaction tests for the presence of tyrosine or histidine in proteins
*Heller's test tests for the presence of albumin in urine
*Gmelin's test tests for the presence of bile pigments in urine
*Hay's test tests for the presence of bile pigments in urine | 3 | Analytical Chemistry |
Kinetic fractionation is an isotopic fractionation process that separates stable isotopes from each other by their mass during unidirectional processes. Biological processes are generally unidirectional and are very good examples of "kinetic" isotope reactions. All organisms preferentially use lighter isotopic species, because "energy costs" are lower, resulting in a significant fractionation between the substrate (heavier) and the biologically mediated product (lighter). As an example, photosynthesis preferentially takes up the light isotope of carbon C during assimilation of an atmospheric CO molecule. This kinetic isotope fractionation explains why plant material (and thus fossil fuels, which are derived from plants) is typically depleted in C by 25 per mil (2.5 per cent) relative to most inorganic carbon on Earth.
A naturally occurring example of non-biological kinetic fractionation occurs during the evaporation of seawater to form clouds under conditions in which some part of the transport is unidirectional, such as evaporation into very dry air. In this instance, isotopically lighter water molecules (i.e., those with O) will evaporate slightly more easily than will the isotopically heavier water molecules with O, and this difference will be greater than it would be if the evaporation was taking place under equilibrium conditions (with bidirectional transport).
During this process the oxygen isotopes are fractionated: the clouds become enriched with O, and the seawater becomes enriched in O. Whereas equilibrium fractionation makes the vapor about 10 per mil (1%) depleted in O relative to the liquid water, kinetic fractionation enhances this fractionation and often makes vapor that is about 15 per mil (1.5%) depleted. Condensation occurs almost exclusively by equilibrium processes, and so it enriches cloud droplets somewhat less than evaporation depletes the vapor. This explains part of the reason why rainwater is observed to be isotopically lighter than seawater.
The isotope of hydrogen in water, deuterium, is much less sensitive to kinetic fractionation than oxygen isotopes, relative to the very large equilibrium fractionation of deuterium. For this reason kinetic fractionation does not deplete deuterium nearly as much, in a relative sense, as O. This gives rise to an excess of deuterium in vapor and rainfall, relative to seawater. The value of this "deuterium excess", as it is called, is about +10 per mil (1%) in most meteoric waters and its non-zero value is a direct manifestation of kinetic isotope fractionation.
A generalized treatment of kinetic isotopic effects is via the GEBIK and GEBIF equations describing transient kinetic isotope effects. | 9 | Geochemistry |
The classification of soil structural forms is based largely on shape.
# Spheroidal structure: sphere-like or rounded in shape. All the axes are approximately of the same dimensions, with curved and irregular faces. These are found commonly in cultivated fields.
## Crumb structure: small and are like crumbs of bread due to them being porous
## Granular structure: less porous than crumb structure aggregates and are more durable than crumb structure aggregates
# Plate-like structure: mainly horizontally aligned along plant based areas, with thin units being laminar and the thick units of the aggregates are classified as platy. Platy structures are usually found in the surface and sometimes in the lower sub-soils.
# Block-like structure: particles that are arranged around a central point are enclosed by surfaces that may be either flat or somewhat rounded. These types are generally found in subsoil.
## Sub angular blocky: corners are more rounded than the angular blocky aggregates
# Prism-like structure: particles that are longer than they are wide, with the vertical axis being greater than the horizontal axis. They are commonly found in subsoil horizon of arid and semi-arid region soils.
## Prismatic: more angular and hexagonal at the top of the aggregate
## Columnar: particles that are rounded at the top of the aggregate | 9 | Geochemistry |
Anthropogenic heat is a small influence on rural temperatures, and becomes more significant in dense urban areas. It is one contributor to urban heat islands. Other human-caused effects (such as changes to albedo, or loss of evaporative cooling) that might contribute to urban heat islands are not considered to be anthropogenic heat by this definition.
Anthropogenic heat is a much smaller contributor to global warming than greenhouse gases are. In 2005, anthropogenic waste heat flux globally accounted for only 1% of the energy flux created by anthropogenic greenhouse gases. The heat flux is not evenly distributed, with some regions higher than others, and significantly higher in certain urban areas. For example, global forcing from waste heat in 2005 was 0.028 W/m, but was +0.39 and +0.68 W/m for the continental United States and western Europe, respectively.
Although waste heat has been shown to have influence on regional climates, climate forcing from waste heat is not normally calculated in state-of-the-art global climate simulations. Equilibrium climate experiments show statistically significant continental-scale surface warming (0.4–0.9 °C) produced by one 2100 AHF scenario, but not by current or 2040 estimates. Simple global-scale estimates with different growth rates of anthropogenic heat that have been actualized recently show noticeable contributions to global warming, in the following centuries. For example, a 2% p.a. growth rate of waste heat resulted in a 3 degree increase as a lower limit for the year 2300. Meanwhile, this has been confirmed by more refined model calculations.
A 2008 scientific paper showed that if anthropogenic heat emissions continue to rise at the current rate, they will become a source of warming as strong as GHG emissions in the 21st century. | 7 | Physical Chemistry |
Thure Cerling and James Ehleringer, a biology professor at the University of Utah, founded Isoforensics in 2003, a company with the aim of interpreting the stable isotope composition of various biological and synthetic materials. This was the first step for the discovery they made which was first published on February 25, 2008, by the "Proceedings of the National Academy of Sciences" with the title "Hydrogen and oxygen isotope ratios in human hair are related to geography".
To know where people have been and where they lived for a while are information that became available by analyzing the stable isotope composition of their scalp hair. Cerling discovered that a strand of hair could provide valuable clues about a person's travels by studying the variation of hydrogen-2 (δ2H) and oxygen-18 (δ18O) isotopes and comparing them to the ones in the drinking water. The extent of the information that can be deduced depends on the length of the hair: the longer is the hair, the greater is the extraction of information. The variation with geography of isotope concentrations is linked with precipitations, cloud temperatures and with the amount of water that evaporates from soil and plants. When clouds move off the ocean towards inland the ratios of oxygen-18 to oxygen-16 and hydrogen-2 to hydrogen-1 tend to decrease because of the rain water with oxygen-18 and hydrogen-2, being heavier, tends to fall first.
Samples of tap water were collected from more than 600 cities across the United States as well as hair samples from the barbershops in 65 cities in 20 states. The comparison showed that both hair and drinking water samples had the same isotopic variations. In order to display these information, the scientists produced color-coded maps based on the correlation of the isotopes in hair to those in drinking water. This maps show how ratios of hydrogen and oxygen isotopes in scalp hair vary in different areas of the United States. It was so proved that the water drank by a human being leaves in the hair an evidence which contain oxygen and hydrogen isotopes equal to the ones in the tap water.
This technique would have been a new tool for policemen, anthropologists, archaeologists and doctors. | 9 | Geochemistry |
Phred was originally conceived in the early 1990s by Phil Green, then a professor at Washington University in St. Louis. LaDeana Hillier, Michael Wendl, David Ficenec, Tim Gleeson, Alan Blanchard, and Richard Mott also contributed to the codebase and algorithm. Green moved to University of Washington in the mid 1990s, after which development was primarily managed by himself and Brent Ewing. Phred played a notable role in the Human Genome Project, where large amounts of sequence data were processed by automated scripts. It was at the time the most widely used base-calling software program by both academic and commercial DNA sequencing laboratories because of its high base calling accuracy. Phred is distributed commercially by [http://www.codoncode.com CodonCode Corporation], and used to perform the "Call bases" function in the program CodonCode Aligner. It is also used by the MacVector plugin Assembler. | 1 | Biochemistry |
Rotating their carbon–carbon bonds, the molecules ethane and propane have three local energy minima. They are structurally and energetically equivalent, and are called the staggered conformers. For each molecule, the three substituents emanating from each carbon–carbon bond are staggered, with each H–C–C–H dihedral angle (and H–C–C–CH dihedral angle in the case of propane) equal to 60° (or approximately equal to 60° in the case of propane). The three eclipsed conformations, in which the dihedral angles are zero, are transition states (energy maxima) connecting two equivalent energy minima, the staggered conformers.
The butane molecule is the simplest molecule for which single bond rotations result in two types of nonequivalent structures, known as the anti- and gauche-conformers (see figure).
For example, butane has three conformers relating to its two methyl (CH) groups: two gauche conformers, which have the methyls ±60° apart and are enantiomeric, and an anti conformer, where the four carbon centres are coplanar and the substituents are 180° apart (refer to free energy diagram of butane). The energy difference between gauche and anti is 0.9 kcal/mol associated with the strain energy of the gauche conformer. The anti conformer is, therefore, the most stable (≈ 0 kcal/mol). The three eclipsed conformations with dihedral angles of 0°, 120°, and 240° are transition states between conformers. Note that the two eclipsed conformations have different energies: at 0° the two methyl groups are eclipsed, resulting in higher energy (≈ 5 kcal/mol) than at 120°, where the methyl groups are eclipsed with hydrogens (≈ 3.5 kcal/mol).
While simple molecules can be described by these types of conformations, more complex molecules require the use of the Klyne–Prelog system to describe the different conformers.
More specific examples of conformational isomerism are detailed elsewhere:
*Ring conformation
**Cyclohexane conformations, including with chair and boat conformations among others.
**Cycloalkane conformations, including medium rings and macrocycles
**Carbohydrate conformation, which includes cyclohexane conformations as well as other details.
*Allylic strain – energetics related to rotation about the single bond between an sp carbon and an sp carbon.
*Atropisomerism – due to restricted rotation about a bond.
*Folding, including the secondary and tertiary structure of biopolymers (nucleic acids and proteins).
*Akamptisomerism – due to restricted inversion of a bond angle. | 4 | Stereochemistry |
According to the FDA approved prescribing information, levofloxacin is pregnancy category C. This designation indicates that animal reproduction studies have shown adverse effects on the fetus and there are no adequate and well-controlled studies in humans, but the potential benefit to the mother may in some cases outweigh the risk to the fetus. Available data point to a low risk for the unborn child. Exposure to quinolones, including levofloxacin, during the first-trimester is not associated with an increased risk of stillbirths, premature births, birth defects, or low birth weight.
Levofloxacin does penetrate into breastmilk, though the concentration of levofloxacin in the breastfeeding infant is expected to be low. Due to potential risks to the baby, the manufacturer does not recommend that nursing mothers take levofloxacin. However, the risk appears to be very low, and levofloxacin can be used in breastfeeding mothers with proper monitoring of the infant, combined with delaying breastfeeding for 4–6 hours after taking levofloxacin. | 4 | Stereochemistry |
The Fano resonance line-shape is due to interference between two scattering amplitudes, one due to scattering within a continuum of states (the background process) and the second due to an excitation of a discrete state (the resonant process). The energy of the resonant state must lie in the energy range of the continuum (background) states for the effect to occur. Near the resonant energy, the background scattering amplitude typically varies slowly with energy while the resonant scattering amplitude changes both in magnitude and phase quickly. It is this variation that creates the asymmetric profile.
For energies far from the resonant energy the background scattering process dominates. Within of the resonant energy, the phase of the resonant scattering amplitude changes by . It is this rapid variation in phase that creates the asymmetric line-shape.
Fano showed that the total scattering cross-section assumes the following form,
where describes the line width of the resonant energy and , the Fano parameter, measures the ratio of resonant scattering to the direct (background) scattering amplitude. This is consistent with the interpretation within the Feshbach–Fano partitioning theory. In the case the direct scattering amplitude vanishes, the parameter becomes zero and the Fano formula becomes :
Looking at transmission shows that this last expression boils down to the expected Breit–Wigner (Lorentzian) formula, as , the three parameters Lorentzian function (note that it is not a density function and does not integrate to 1, as its amplitude is 1 and not ). | 7 | Physical Chemistry |
Many gels display thixotropy – they become fluid when agitated, but resolidify when resting.
In general, gels are apparently solid, jelly-like materials. It is a type of non-Newtonian fluid.
By replacing the liquid with gas it is possible to prepare aerogels, materials with exceptional properties including very low density, high specific surface areas, and excellent thermal insulation properties. | 7 | Physical Chemistry |
Relative little is known about the normal functions and pathological actions of the CKLF2, CKLF3, and CKLF4 isoforms. | 1 | Biochemistry |
A redox indicator (also called an oxidation-reduction indicator) is an indicator which undergoes a definite color change at a specific electrode potential.
The requirement for fast and reversible color change means that the oxidation-reduction equilibrium for an indicator redox system needs to be established very quickly. Therefore, only a few classes of organic redox systems can be used for indicator purposes.
There are two common classes of redox indicators:
* metal complexes of phenanthroline and bipyridine. In these systems, the metal changes oxidation state.
* organic redox systems such as methylene blue. In these systems, a proton participates in the redox reaction. Therefore, sometimes redox indicators are also divided into two general groups: independent or dependent on pH.
The most common redox indicator are organic compounds.
Redox Indicator example:
The molecule 2,2'- Bipyridine is a redox Indicator. In solution, it changes from light blue to red at an electrode potential of 0.97 V. | 7 | Physical Chemistry |
Mitochondrial replacement therapy has been used to prevent the transmission of mitochondrial diseases from mother to child; it could only be performed in clinics licensed by the UK's Human Fertilisation and Embryology Authority (HFEA), only for people individually approved by the HFEA, for whom preimplantation genetic diagnosis is unlikely to be helpful, and only with informed consent that the risks and benefits are not well understood.
Relevant mutations are found in about 0.5% of the population and disease affects around one in 5000 individuals (0.02%)—the percentage of people affected is much smaller because cells contain many mitochondria, only some of which carry mutations, and the number of mutated mitochondria need to reach a threshold in order to affect the entire cell, and many cells need to be affected for the person to show disease.
The average number of births per year among women at risk for transmitting mtDNA disease is estimated to approximately 150 in the United Kingdom and 800 in the United States.
Prior to the development of MRT, and in places where it is not legal or feasible, the reproductive options for women who are at risk for transmitting mtDNA disease and who want to prevent transmission were using an egg from another woman, adoption, or childlessness. | 1 | Biochemistry |
Lyngbyastatins 1 and 3 are cytotoxic cyclic depsipeptides that possess antiproliferative activity against human cancer cell lines. These compounds, first isolated from the extract of a Lyngbya majuscula/Schizothrix calcicola assemblage and from L. majuscula Harvey ex Gomont (Oscillatoriaceae) strains, respectively, target the actin cytoskeleton of eukaryotic cells. | 1 | Biochemistry |
The cell has a non-conductive housing. The cathode is composed of thousands of sub-millimeter microspheres (co-polymer beads), with a flash coat of copper and multiple layers of electrolytically deposited thin film (650 Angstrom) nickel and palladium. The beads are submerged in water with a lithium sulfate (LiSO) electrolyte solution. | 7 | Physical Chemistry |
Hattori's research interest has also extended to porphyry-type deposits, which supply critical metals such as copper, molybdenum, and gold. Through her research, she presented evidence supporting the notion that sulfur and metals have their origin in the mantle, and proposed that they were extracted and transported by mafic magmas from the mantle to shallow crustal levels. This proposal was based on her earlier work on Pinatubo eruption products, where metals and sulphur are released from mafic magmas during their ascent and incorporated into overlying erupted felsic magmas. Furthermore, Cees-Jan DeHoog, her post-doctoral research fellow, provided evidence that oxidized magmas are capable to transport metals and sulphur from deep in the mantle to shallow levels of crust. | 9 | Geochemistry |
* 1970: Peter Goldacre Award from the Australian Society of Plant Scientists (previously called the Australian Society of Plant Physiologists).
* 1980: Charles F Kettering Award from the American Society of Plant Physiologists, shared with Hugo Kortschak and Marshall (Hal) Davidson Hatch.
* 1981: Rank Prize for Nutrition, shared with Hugo Kortschak and Marshall (Hal) Davidson Hatch.
* 1983: Elected as a Fellow of the Royal Society of New Zealand.
* 1989: Elected as a Fellow of the Royal Society. | 1 | Biochemistry |
Jeanette Grasselli Brown (born Jeanette Gecsy; August 4, 1928) is an American analytical chemist and spectroscopist who is known for her work with Standard Oil of Ohio (now BP America) as an industrial researcher in the field of spectroscopy.
Spectroscopy is a technique used to measure the interaction of electromagnetic radiation with matter. Her areas of expertise encompass fields such as vibrational spectroscopy, combined instrumental techniques, computerized spectroscopy, and environmental spectroscopy. She developed new techniques to solve problems like identifying contaminants in gasoline, analyzing the makeup of new plastics, and analyzing environmental problems such as pollution.
During her career, Grasselli Brown has striven to bridge the gap between research and practical applications between industry and academia. She is considered one of the foremost contributors to infrared and Raman spectrometry of the 20th century. | 3 | Analytical Chemistry |
Sulfimides (also called a sulfilimines) are sulfur–nitrogen compounds of structure RS=NR′, the nitrogen analog of sulfoxides. They are of interest in part due to their pharmacological properties. When two different R groups are attached to sulfur, sulfimides are chiral. Sulfimides form stable α-carbanions.
Sulfoximides (also called sulfoximines) are tetracoordinate sulfur–nitrogen compounds, isoelectronic with sulfones, in which one oxygen atom of the sulfone is replaced by a substituted nitrogen atom, e.g., RS(O)=NR′. When two different R groups are attached to sulfur, sulfoximides are chiral. Much of the interest in this class of compounds is derived from the discovery that methionine sulfoximide (methionine sulfoximine) is an inhibitor of glutamine synthetase.
Sulfonediimines (also called sulfodiimines, sulfodiimides or sulfonediimides) are tetracoordinate sulfur–nitrogen compounds, isoelectronic with sulfones, in which both oxygen atoms of the sulfone are replaced by a substituted nitrogen atom, e.g., RS(=NR′). They are of interest because of their biological activity and as building blocks for heterocycle synthesis. | 9 | Geochemistry |
tRNA (also tRNA-like) splicing is another rare form of splicing that usually occurs in tRNA. The splicing reaction involves a different biochemistry than the spliceosomal and self-splicing pathways.
In the yeast Saccharomyces cerevisiae, a yeast tRNA splicing endonuclease heterotetramer, composed of TSEN54, TSEN2, TSEN34, and TSEN15, cleaves pre-tRNA at two sites in the acceptor loop to form a 5-half tRNA, terminating at a 2,3-cyclic phosphodiester group, and a 3-half tRNA, terminating at a 5-hydroxyl group, along with a discarded intron. Yeast tRNA kinase then phosphorylates the 5-hydroxyl group using adenosine triphosphate. Yeast tRNA cyclic phosphodiesterase cleaves the cyclic phosphodiester group to form a 2-phosphorylated 3 end. Yeast tRNA ligase adds an adenosine monophosphate group to the 5 end of the 3-half and joins the two halves together. NAD-dependent 2-phosphotransferase then removes the 2-phosphate group. | 1 | Biochemistry |
The history of metallurgy in the Indian subcontinent began prior to the 3rd millennium BCE. Metals and related concepts were mentioned in various early Vedic age texts. The Rigveda already uses the Sanskrit term ayas (). The Indian cultural and commercial contacts with the Near East and the Greco-Roman world enabled an exchange of metallurgic sciences. The advent of the Mughals (established: April 21, 1526—ended: September 21, 1857) further improved the established tradition of metallurgy and metal working in India. During the period of British rule in India (first by the East India Company and then by the Crown), the metalworking industry in India stagnated due to various colonial policies, though efforts by industrialists led to the industry's revival during the 19th century. | 8 | Metallurgy |
The preparation of stable carbenes free from metal cations has been keenly sought to allow further study of the carbene species in isolation from these metals. Separating a carbene from a carbene-metal complex can be problematic due to the stability of the complex. Accordingly, it is preferable to make the carbene free from these metals in the first place. Indeed, some metal ions, rather than stabilising the carbene, have been implicated in the catalytic dimerisation of unhindered examples.
Shown right is an X-ray structure showing a complex between a diaminocarbene and potassium HMDS. This complex was formed when excess KHMDS was used as a strong base to deprotonate the formamidinium salt. Removing lithium ions resulting from deprotonation with reagents such as lithium diisopropylamide (LDA) can be especially problematic. Potassium and sodium salt by-products tend to precipitate from solution and can be removed. Lithium ions may be chemically removed by binding to species such as cryptands or crown ethers.
Metal free carbenes have been prepared in several ways as outlined below: | 0 | Organic Chemistry |
The FAST-fluorogen reporting system is used in fluorescence microscopy, flow cytometry and any other fluorometric methods to explore the living world, including biosensors and protein trafficking. FAST has been reported for dynamic imaging of biofilms because of its unique capacity of fluorescence in low-oxygen conditions. For the same reason it allows for imaging and FACSing anaerobes, such as Clostridium, used for biomass fermentation like the ABE fermentation. FAST has also been reported for super-resolution microscopy of living cells.
A number of fluorogens were developed for FAST and its derivates by The Twinkle Factory, varying by their emission wavelength, their brightness and their tag affinity. Some are non permeant, i.e., they cant go through cell membranes, hence specifically labeling membrane proteins or extracellular proteins, allowing for, e.g.', monitoring trafficking from synthesis until excretion. | 1 | Biochemistry |
Particle Display produces higher yields of higher affinity aptamers in less rounds than conventional selection methods. In this method, libraries of aptamers are separated into aptamer particles and separated by fluorescence-activated cell sorting based on affinity. Only the highest affinity aptamer particles are isolated and sequenced into aptamers. This is an affinity-base selection process that is more efficient than selection methods such as SELEX. Particle display may be a reliable aptamer generation method for E-AB sensors due to the high affinity and specificity of target binding.
Researchers tackled the challenge of isolating high-affinity aptamers in conventional SELEX by introducing Particle Display System (PDS). Using parallel single-molecule emulsion polymerase chain reaction (PCR) for monoclonal aptamer screening, PDS employs emulsion PCR and droplet digital PCR to prevent by-product propagation and preserve rare high-affinity sequences. The one-particle-one-sequence nature of PDS transforms the DNA-target interaction into a particle-target interaction, enabling swift confirmation of aptamer candidate affinities through fluorescence-activated cell sorting or flow cytometry assays. Unlike conventional SELEX, PDS efficiently segregates aptamers, providing a streamlined and effective method for identifying and isolating high-affinity binders. PDS significantly enhances the efficiency of enriching high-affinity aptamers, achieving this in a single round of screening.
Particle display yields higher quantities of higher affinity aptamers in fewer rounds compared to conventional selection methods. This method separates aptamer libraries into aptamer particles and employs fluorescence-activated cell sorting to isolate particles based on affinity. Only the highest affinity aptamer particles are isolated and sequenced into aptamers. This affinity-based selection process is more efficient than methods such as SELEX. Particle display may be a reliable aptamer generation method for E-AB sensors due to the high affinity and specificity of target binding | 7 | Physical Chemistry |
Azines characteristically undergo hydrolysis to hydrazines. The reaction proceeds by the intermediacy of a hydrazone:
:RC=N-N=CR + HO → RC=N-NH + RC=O
:RC=N-NH + HO → NH + RC=O
Azines have been used as precursors to hydrazones:
:RC=N-N=CR + NH → 2 RC=N-NH
They are also precursors to diazo compounds.
The coordination chemistry of azines (as ligands) has also been studied.
Acetone is used to derivatize hydrazine into acetone azine for analysis by gas chromatography. This method is used to determine trace levels of hydrazine in drinking water and pharmaceuticals. | 0 | Organic Chemistry |
The Maximum Entropy thermodynamics has some important opposition, in part because of the relative paucity of published results from the MaxEnt school, especially with regard to new testable predictions far-from-equilibrium.
The theory has also been criticized in the grounds of internal consistency. For instance, Radu Balescu provides a strong criticism of the MaxEnt School and of Jaynes work. Balescu states that Jaynes and coworkers theory is based on a non-transitive evolution law that produces ambiguous results. Although some difficulties of the theory can be cured, the theory "lacks a solid foundation" and "has not led to any new concrete result".
Though the maximum entropy approach is based directly on informational entropy, it is applicable to physics only when there is a clear physical definition of entropy. There is no clear unique general physical definition of entropy for non-equilibrium systems, which are general physical systems considered during a process rather than thermodynamic systems in their own internal states of thermodynamic equilibrium. It follows that the maximum entropy approach will not be applicable to non-equilibrium systems until there is found a clear physical definition of entropy. This problem is related to the fact that heat may be transferred from a hotter to a colder physical system even when local thermodynamic equilibrium does not hold so that neither system has a well defined temperature. Classical entropy is defined for a system in its own internal state of thermodynamic equilibrium, which is defined by state variables, with no non-zero fluxes, so that flux variables do not appear as state variables. But for a strongly non-equilibrium system, during a process, the state variables must include non-zero flux variables. Classical physical definitions of entropy do not cover this case, especially when the fluxes are large enough to destroy local thermodynamic equilibrium. In other words, for entropy for non-equilibrium systems in general, the definition will need at least to involve specification of the process including non-zero fluxes, beyond the classical static thermodynamic state variables. The entropy that is maximized needs to be defined suitably for the problem at hand. If an inappropriate entropy is maximized, a wrong result is likely. In principle, maximum entropy thermodynamics does not refer narrowly and only to classical thermodynamic entropy. It is about informational entropy applied to physics, explicitly depending on the data used to formulate the problem at hand. According to Attard, for physical problems analyzed by strongly non-equilibrium thermodynamics, several physically distinct kinds of entropy need to be considered, including what he calls second entropy. Attard writes: "Maximizing the second entropy over the microstates in the given initial macrostate gives the most likely target macrostate.". The physically defined second entropy can also be considered from an informational viewpoint. | 7 | Physical Chemistry |
Riboswitch sequences (in the mRNA leader transcript) bind molecules such as amino acids, nucleotides, sugars, vitamins, metal ions and other small ligands which cause a conformational change in the mRNA. Most of these attenuators are inhibitory and are employed by genes for biosynthetic enzymes or transporters whose expression is inversely related to the concentration of their corresponding metabolites.
Example- Cobalamine biosynthesis, Cyclic AMP-GMP switch, lysin biosynthesis, glycine biosynthesis, fluroide switch etc. | 1 | Biochemistry |
Merrilactone A occurs naturally in Illicium merrillianum, a plant indigenous to southern China and Myanmar. The genus Illicium belongs to the family Illiciaceae and is an evergreen shrub or tree. Approximately 40 species are disjunctively distributed in eastern North America, Mexico, the West Indies, and eastern Asia. The highest concentration of species is in northern Myanmar and southern China, where nearly 35 species have been described. The fruits of the Illicium species are distinctive star-shaped follicles that have a characteristic refreshing flavour. The fruits of Illicium merrillianum also have an aromatic odor, bland taste and cause numbness of the tongue when chewed.
The only economically important product from this genus is the fruit of Illicium verum, or Chinese star anise, which is widely used as a spice for flavouring food and beverages. In contrast, the fruit of Japanese star anise, Illicium anisatum, have been known to be very toxic for several centuries. | 0 | Organic Chemistry |
In physics and chemistry, there are two main macroscopic consequences of the time-reversibility of microscopic dynamics: the principle of detailed balance and the Onsager reciprocal relations.
The statistical description of the macroscopic process as an ensemble of the elementary indivisible events (collisions) was invented by L. Boltzmann and formalised in the Boltzmann equation. He discovered that the time-reversibility of the Newtonian dynamics leads to the detailed balance for collision: in equilibrium collisions are equilibrated by their reverse collisions. This principle allowed Boltzmann to deduce simple and nice formula for entropy production and prove his famous H-theorem. In this way, microscopic reversibility was used to prove macroscopic irreversibility and convergence of ensembles of molecules to their thermodynamic equilibria.
Another macroscopic consequence of microscopic reversibility is the symmetry of kinetic coefficients, the so-called reciprocal relations. The reciprocal relations were discovered in the 19th century by Thomson and Helmholtz for some phenomena but the general theory was proposed by Lars Onsager in 1931. He found also the connection between the reciprocal relations and detailed balance. For the equations of the law of mass action the reciprocal relations appear in the linear approximation near equilibrium as a consequence of the detailed balance conditions. According to the reciprocal relations, the damped oscillations in homogeneous closed systems near thermodynamic equilibria are impossible because the spectrum of symmetric operators is real. Therefore, the relaxation to equilibrium in such a system is monotone if it is sufficiently close to the equilibrium. | 7 | Physical Chemistry |
The p-hydroxyphenylpyruvate is synthesized from tyrosine, while the solanesyl diphosphate is synthesized through the MEP/DOXP pathway. Homogentisate is formed from p-hydroxyphenylpyruvate and is then combined with solanesyl diphosphate through a condensation reaction. The resulting intermediate, 2-methyl-6-solanesyl-1,4-benzoquinol is then methylated to form the final product, plastoquinol-9. This pathway is used in most photosynthetic organisms, like algae and plants. However, cyanobacteria appear to not use homogentisate for synthesizing plastoquinol, possibly resulting in a pathway different from the one shown below. | 5 | Photochemistry |
In the late 1950s and early 1960s, more than 10,000 children in 46 countries were born with deformities, such as phocomelia, as a consequence of thalidomide use. The severity and location of the deformities depended on how many days into the pregnancy the mother was before beginning treatment, with the time-sensitive window occurring approximately between day 20 and day 36 post-fertilisation. Thalidomide taken on the 20th day of pregnancy caused central brain damage, day 21 would damage the eyes, day 22 the ears and face, day 24 the arms, and leg damage would occur if taken up to day 28.
It is not known exactly how many worldwide victims of the drug there have been, although estimates range from 10,000 to 20,000. Despite the side effects, thalidomide was sold in pharmacies in Canada until 1962. | 4 | Stereochemistry |
Almost all methods for detection of nitrate rely on its conversion to nitrite followed by nitrite-specific tests. The reduction of nitrate to nitrite is effected by copper-cadmium material. The sample is introduced with a flow injection analyzer, and the resulting nitrite-containing effluent is then combined with a reagent for colorimetric or electrochemical detection. The most popular of these assays is the Griess test, whereby nitrite is converted to a deeply colored azo dye suited for UV-vis spectroscopic analysis. The method exploits the reactivity of nitrous acid derived from acidification of nitrite. Nitrous acid selectively reacts with aromatic amines to give diazonium salts, which in turn couple with a second reagent to give the azo dye. The detection limit is 0.02 to 2 μM. Such methods have been highly adapted to biological samples. | 0 | Organic Chemistry |
Secondary endosymbiosis results in the engulfment of an organism that has already performed primary endosymbiosis. Thus, four plasma membranes are formed. The first originating from the cyanobacteria, the second from the eukaryote that engulfed the cyanobacteria, and the third from the eukaryote who engulfed the primary endosymbiotic eukaryote. Chloroplasts contain 16S rRNA and 23S rRNA. 16S and 23S rRNA is found only in prokaryotes by definition. Chloroplasts and mitochondria also replicate semi-autonomously outside of the cell cycle replication system via binary fission. Consistent with the theory, decreased genome size within the organelle and gene integration into the nucleus occurred. Chloroplasts genomes encode 50-200 proteins, compared to the thousands in cyanobacterium. Furthermore, in Arabidopsis, nearly 20% of the nuclear genome originate from cyanobacterium, the highly recognized origin of chloroplasts. Recent studies have been able to identify the speed and size at which chloroplast genes are able to incorporate themselves into the host genome. Using chloroplast transformation genes encoding spectinomycin and kanamycin resistance were inserted into the DNA of chloroplasts found in tobacco plants. After subjecting the plants to spectinomycin and kanamycin selection, some plants began to tolerate spectinomycin and kanamycin. Roughly 1 in every 5 million cells on the tobacco leaves highly expressed spectinomycin and kanamycin resistant genes. By using the cells expressing resistances, they were able to grow tobacco from these cell to maturity. Once mature, the plants were mated with wild-type plants, and 50% of the progeny expressed spectinomycin and kanamycin resistance genes. Pollen was thought not to be able to transfer chloroplast DNA in tobacco (which later turned out not to be as true as was thought at the time), thus leading to believe that the genes were incorporated into the tobaccos genome. Furthermore, 11kb of integrated chloroplast DNA was introduced to the host genome, transferring more DNA that previously predicted at a faster rate than previously predicted. | 5 | Photochemistry |
Chemical exothermic reactions are generally more spontaneous than their counterparts, endothermic reactions.
In a thermochemical reaction that is exothermic, the heat may be listed among the products of the reaction. | 7 | Physical Chemistry |
There are twenty-one species currently classified under Ancyronyx. Eleven of these are endemic to the Philippines, which may indicate that the country is a center of diversity for the genus. Most of the species have highly restricted distributions, often being found in only one island.
*Ancyronyx acaroides – Southeast Asia
**Ancyronyx acaroides acaroides – Myanmar, Vietnam, Malaysia (peninsular Malaysia, Borneo), Brunei, Indonesia (Sumatra, Java)
**Ancyronyx acaroides cursor – Indonesia (Bali)
*Ancyronyx buhid – Philippines (Mindoro)
*Ancyronyx helgeschneideri – Philippines (Palawan, Busuanga)
*Ancyronyx hjarnei – Indonesia (Sulawesi)
*Ancyronyx jaechi – Sri Lanka
*Ancyronyx johanni – Indonesia (Siberut)
*Ancyronyx malickyi – Laos, southern Thailand, Malaysia (peninsular Malaysia, Borneo), Indonesia (Sumatra)
*Ancyronyx minerva – Philippines (Palawan, Busuanga, Mindoro)
*Ancyronyx minutulus – Philippines (Palawan)
*Ancyronyx montanus – Philippines (Palawan)
*Ancyronyx patrolus – Philippines (Palawan, Busuanga)
*Ancyronyx procerus – Vietnam, Malaysia (Borneo), Brunei, Philippines (Busuanga)
*Ancyronyx pseudopatrolus – Philippines (Palawan)
*Ancyronyx punkti – Philippines (Palawan)
*Ancyronyx raffaelacatharina – Indonesia (Sulawesi)
*Ancyronyx sarawacensis – Malaysia (Borneo)
*Ancyronyx schillhammeri – Philippines (Mindoro)
*Ancyronyx sophiemarie – Philippines (Sibuyan)
*Ancyronyx tamaraw – Philippines (Mindoro)
*Ancyronyx variegatus – United States of America
*Ancyronyx yunju – China (Jiangxi) | 2 | Environmental Chemistry |
Transcriptomics technologies are the techniques used to study an organism's transcriptome, the sum of all of its RNA transcripts. The information content of an organism is recorded in the DNA of its genome and expressed through transcription. Here, mRNA serves as a transient intermediary molecule in the information network, whilst non-coding RNAs perform additional diverse functions. A transcriptome captures a snapshot in time of the total transcripts present in a cell. Transcriptomics technologies provide a broad account of which cellular processes are active and which are dormant.
A major challenge in molecular biology is to understand how a single genome gives rise to a variety of cells. Another is how gene expression is regulated.
The first attempts to study whole transcriptomes began in the early 1990s. Subsequent technological advances since the late 1990s have repeatedly transformed the field and made transcriptomics a widespread discipline in biological sciences. There are two key contemporary techniques in the field: microarrays, which quantify a set of predetermined sequences, and RNA-Seq, which uses high-throughput sequencing to record all transcripts. As the technology improved, the volume of data produced by each transcriptome experiment increased. As a result, data analysis methods have steadily been adapted to more accurately and efficiently analyse increasingly large volumes of data. Transcriptome databases getting bigger and more useful as transcriptomes continue to be collected and shared by researchers. It would be almost impossible to interpret the information contained in a transcriptome without the knowledge of previous experiments.
Measuring the expression of an organisms genes in different tissues or conditions, or at different times, gives information on how genes are regulated and reveals details of an organisms biology. It can also be used to infer the functions of previously unannotated genes. Transcriptome analysis has enabled the study of how gene expression changes in different organisms and has been instrumental in the understanding of human disease. An analysis of gene expression in its entirety allows detection of broad coordinated trends which cannot be discerned by more targeted assays. | 1 | Biochemistry |
Degeneracy of the genetic code was identified by Lagerkvist. For instance, codons GAA and GAG both specify glutamic acid and exhibit redundancy; but, neither specifies any other amino acid and thus are not ambiguous or demonstrate no ambiguity.
The codons encoding one amino acid may differ in any of their three positions; however, more often than not, this difference is in the second or third position. For instance, the amino acid glutamic acid is specified by GAA and GAG codons (difference in the third position); the amino acid leucine is specified by UUA, UUG, CUU, CUC, CUA, CUG codons (difference in the first or third position); and the amino acid serine is specified by UCA, UCG, UCC, UCU, AGU, AGC (difference in the first, second, or third position).
Degeneracy results because there are more codons than encodable amino acids. For example, if there were two bases per codon, then only 16 amino acids could be coded for (4²=16). Because at least 21 codes are required (20 amino acids plus stop) and the next largest number of bases is three, then 4³ gives 64 possible codons, meaning that some degeneracy must exist. | 1 | Biochemistry |
Iodosobenzene is prepared from iodobenzene. It is prepared by first oxidizing iodobenzene by peracetic acid. Hydrolysis of resulting diacetate affords "PhIO":
The structure of iodosobenzene has been verified by crystallographically. Related derivatives are also oligomeric. Its low solubility in most solvents and vibrational spectroscopy indicate that it is not molecular, but is polymeric, consisting of –I–O–I–O– chains. The related diacetate, , illustrates the ability of iodine(III) to adopt a T-shaped geometry without multiple bonds.
Theoretical studies show that the bonding between the iodine and oxygen atoms in iodosobenzene represents a single dative I-O sigma bond, confirming the absence of the double I=O bond.
A monomeric derivative iodosylbenzene is known in the form of 2-(tert-butylsulfonyl)iodosylbenzene, a yellow solid. C-I-O angle is 94.78°, C-I and I-O distances are 2.128 and 1.848 Å. | 0 | Organic Chemistry |
Disulfide bonds can be formed under oxidising conditions and play an important role in the folding and stability of some proteins, usually proteins secreted to the extracellular medium. Since most cellular compartments are reducing environments, in general, disulfide bonds are unstable in the cytosol, with some exceptions as noted below, unless a sulfhydryl oxidase is present.
Disulfide bonds in proteins are formed between the thiol groups of cysteine residues by the process of oxidative folding. The other sulfur-containing amino acid, methionine, cannot form disulfide bonds. A disulfide bond is typically denoted by hyphenating the abbreviations for cysteine, e.g., when referring to ribonuclease A the "Cys26–Cys84 disulfide bond", or the "26–84 disulfide bond", or most simply as "C26–C84" where the disulfide bond is understood and does not need to be mentioned. The prototype of a protein disulfide bond is the two-amino-acid peptide cystine, which is composed of two cysteine amino acids joined by a disulfide bond. The structure of a disulfide bond can be described by its χ dihedral angle between the C−S−S−C atoms, which is usually close to ±90°.
The disulfide bond stabilizes the folded form of a protein in several ways:
#It holds two portions of the protein together, biasing the protein towards the folded topology. That is, the disulfide bond destabilizes the unfolded form of the protein by lowering its entropy.
#The disulfide bond may form the nucleus of a hydrophobic core of the folded protein, i.e., local hydrophobic residues may condense around the disulfide bond and onto each other through hydrophobic interactions.
#Related to 1 and 2, the disulfide bond links two segments of the protein chain, increases the effective local concentration of protein residues, and lowers the effective local concentration of water molecules. Since water molecules attack amide-amide hydrogen bonds and break up secondary structure, a disulfide bond stabilizes secondary structure in its vicinity. For example, researchers have identified several pairs of peptides that are unstructured in isolation, but adopt stable secondary and tertiary structure upon formation of a disulfide bond between them.
A disulfide species is a particular pairing of cysteines in a disulfide-bonded protein and is usually depicted by listing the disulfide bonds in parentheses, e.g., the "(26–84, 58–110) disulfide species". A disulfide ensemble is a grouping of all disulfide species with the same number of disulfide bonds, and is usually denoted as the 1S ensemble, the 2S ensemble, etc. for disulfide species having one, two, etc. disulfide bonds. Thus, the (26–84) disulfide species belongs to the 1S ensemble, whereas the (26–84, 58–110) species belongs to the 2S ensemble. The single species with no disulfide bonds is usually denoted as R for "fully reduced". Under typical conditions, disulfide reshuffling is much faster than the formation of new disulfide bonds or their reduction; hence, the disulfide species within an ensemble equilibrate more quickly than between ensembles.
The native form of a protein is usually a single disulfide species, although some proteins may cycle between a few disulfide states as part of their function, e.g., thioredoxin. In proteins with more than two cysteines, non-native disulfide species may be formed, which are almost always misfolded. As the number of cysteines increases, the number of nonnative species increases factorially. | 0 | Organic Chemistry |
In 2010, INFRA built a compact Pilot [http://en.infratechnology.com/technology/pilotplant/ Plant] for conversion of natural gas into synthetic oil. The plant modeled the full cycle of the GTL chemical process including the intake of pipeline gas, sulfur removal, steam methane reforming, syngas conditioning, and Fischer–Tropsch synthesis. In 2013 the first pilot plant was acquired by VNIIGAZ Gazprom LLC. In 2014 INFRA commissioned and operated on a continuous basis a new, larger scale full cycle Pilot Plant. It represents the second generation of INFRAs testing facility and is differentiated by a high degree of automation and extensive data gathering system. In 2015, INFRA built its own catalyst factory in Troitsk (Moscow, Russia). The catalyst factory has a capacity of over 15 tons per year, and produces the unique proprietary Fischer–Tropsch catalysts developed by the companys R&D division. In 2016, INFRA designed and built a modular, transportable GTL (gas-to-liquid) M100 plant for processing natural and associated gas into synthetic crude oil in Wharton (Texas, USA). The M100 plant is operating as a technology demonstration unit, R&D platform for catalyst refinement, and economic model to scale the Infra GTL process into larger and more efficient plants. | 0 | Organic Chemistry |
The basic process, patented in 1922, is called the Bosch–Meiser urea process after its discoverers Carl Bosch and Wilhelm Meiser. The process consists of two main equilibrium reactions, with incomplete conversion of the reactants. The first is carbamate formation: the fast exothermic reaction of liquid ammonia with gaseous carbon dioxide () at high temperature and pressure to form ammonium carbamate ():
:(ΔH = −117 kJ/mol at 110 atm and 160 °C)
The second is urea conversion: the slower endothermic decomposition of ammonium carbamate into urea and water:
:(ΔH = +15.5 kJ/mol at 160–180 °C)
The overall conversion of and to urea is exothermic, with the reaction heat from the first reaction driving the second. The conditions that favor urea formation (high temperature) have an unfavorable effect on the carbamate formation equilibrium. The process conditions are a compromise: the ill-effect on the first reaction of the high temperature (around 190 °C) needed for the second is compensated for by conducting the process under high pressure (140–175 bar), which favors the first reaction. Although it is necessary to compress gaseous carbon dioxide to this pressure, the ammonia is available from the ammonia production plant in liquid form, which can be pumped into the system much more economically. To allow the slow urea formation reaction time to reach equilibrium, a large reaction space is needed, so the synthesis reactor in a large urea plant tends to be a massive pressure vessel. | 0 | Organic Chemistry |
The progress of modern lipidomics has been greatly accelerated by the development of spectrometric methods in general and soft ionization techniques for mass spectrometry such as electrospray ionization (ESI), desorption electrospray ionization (DESI), and matrix-assisted laser desorption/ionization (MALDI) in particular. "Soft" ionization
does not cause extensive fragmentation, so that comprehensive detection of an entire range of lipids within a complex mixture can be correlated to experimental conditions or disease state. In addition, the technique of atmospheric pressure chemical ionization (APCI) has become increasingly popular for the analysis of nonpolar lipids. | 1 | Biochemistry |
Primary cells are not rechargeable and are generally disposed of after the cell's internal reaction has consumed the reactive starting chemicals.
Secondary cells are rechargeable, and may be reused multiple times.
* Primary cell
** Zinc–carbon cell
** Alkaline cell
** Lithium cell
** Mercury cell
** Silver-oxide cell
* Secondary cell
** Nickel–cadmium cell
** Lithium-ion cell
** Nickel–metal hydride cell | 7 | Physical Chemistry |
Holthusen (1921) first quantified the oxygen effect finding 2.5 to 3.0-fold less hatching eggs of the nematode Ascaris in oxygenated compared to anoxic conditions, which was incorrectly assigned to changes in cell division. However, two years later, Petry (1923) first attributed oxygen tension as affecting ionizing radiation effects on vegetable seeds. Later, the implications of the effects of oxygen on radiotherapy were discussed by Mottram (1936).
A key observation limiting hypotheses to explain the biological mechanisms of the oxygen effect is that the gas nitric oxide is a radiosensitizer with similar effects to oxygen observed in tumour cells. Another important observation is that oxygen must be present at irradiation or within milliseconds afterward for the oxygen effect to take place.
The best known explanation of the oxygen effect is the oxygen fixation hypothesis developed by Alexander in 1962, which posited that radiation-induced non-restorable or "fixed" nuclear DNA lesions are lethal to cells in the presence of diatomic oxygen. Recent hypotheses include one based on oxygen-enhanced damage from first principles. Another hypothesis posits that ionizing radiation provokes mitochondria to produce reactive oxygen (and nitrogen species), which are leakage during oxidative phosphorylation that varies with a hyperbolic saturation relationship observed with both the oxygen and nitric oxide effects. | 1 | Biochemistry |
To enhance carbon sequestration processes in oceans the following technologies have been proposed but none have achieved large scale application so far: Seaweed farming, ocean fertilisation, artificial upwelling, basalt storage, mineralization and deep sea sediments, adding bases to neutralize acids. The idea of direct deep-sea carbon dioxide injection has been abandoned. | 5 | Photochemistry |
Simple twinned crystals may be contact twins or penetration twins. Contact twins meet on a single composition plane, often appearing as mirror images across the boundary. Plagioclase, quartz, gypsum, and spinel often exhibit contact twinning. Merohedral twinning occurs when the lattices of the contact twins superimpose in three dimensions, such as by relative rotation of one twin from the other. An example is metazeunerite. Contact twinning characteristically creates reentrant faces where faces of the crystal segments meet on the contact plane at an angle greater than 180°.
A type of twinning involving 180° relationships is called hemitropism or hemitropy.
In penetration twins the individual crystals have the appearance of passing through each other in a symmetrical manner. Orthoclase, staurolite, pyrite, and fluorite often show penetration twinning. The composition surface in penetration twins is usually irregular and extends to the center of the crystal.
Contact twinning can arise from either reflection or rotation, whereas penetration twinning is usually produced by rotation.
If several twin crystal parts are aligned by the same twin law they are referred to as multiple or repeated twins. If these multiple twins are aligned in parallel they are called polysynthetic twins. When the multiple twins are not parallel they are cyclic twins. Albite, calcite, and pyrite often show polysynthetic twinning. Closely spaced polysynthetic twinning is often observed as striations or fine parallel lines on the crystal face. Rutile, aragonite, cerussite, and chrysoberyl often exhibit cyclic twinning, typically in a radiating pattern.
For rotational twinning the relationship between the twin axis and twin plane falls into one of three types:
:#parallel twinning, when the twin axis and compositional plane lie parallel to each other,
:#normal twinning, when the twin plane and compositional plane lie normally, and
:#complex twinning, a combination of parallel twinning and normal twinning on one compositional plane. | 3 | Analytical Chemistry |
Aside from its immense environmental impacts, Freon 113, like most chlorofluoroalkanes, forms phosgene gas when exposed to a naked flame. | 2 | Environmental Chemistry |
Microwave spectroscopy is the spectroscopy method that employs microwaves, i.e. electromagnetic radiation at GHz frequencies, for the study of matter. | 7 | Physical Chemistry |
Nuclear spectroscopy is a superordinate concept of methods that uses properties of a nucleus to probe material properties. By emission or absorption of radiation from the nucleus information of the local structure is obtained, as an interaction of an atom with its closest neighbours. Or a radiation spectrum of the nucleus is detected. Most methods base on hyperfine interactions, which are the interaction of the nucleus with its interaction of its atom's electrons and their interaction with the nearest neighbor atoms as well as external fields. Nuclear spectroscopy is mainly applied to solids and liquids, rarely in gases. Its methods are important tools in condensed matter physics, solid state chemistry., and analysis of chemical composition (analytical chemistry). | 7 | Physical Chemistry |
Middle and Late Minoan and Mycenaean vessels are many. First in size are some basins found at Tylissos in Crete, the largest measuring 1.40 metres in diameter. They are shallow hemispherical bowls with two or three loop-handles riveted on their edges, and are made in several sections. The largest is composed of seven hammered sheets, three at the lip, three in the body, and one at the base. This method of construction is usual in large complicated forms. The joints of necks and bodies of jugs and jars were often masked with a roll-moulding. Simpler and smaller forms were also cast. The finest specimens of such vases come from houses and tombs at Knossos. Their ornament is applied in separate bands, hammered or cast and chased, and soldered on the lip or shoulder of the vessel. A richly decorated form is a shallow bowl with wide ring-handle and flat lip, on both of which are foliate or floral patterns in relief.
A notable shape, connecting prehistoric with Hellenic metallurgy is a tripod-bowl, a hammered globular body with upright ring-handles on the lip and heavy cast legs attached to the shoulder. | 8 | Metallurgy |
In the case of nucleic acids, the direction of migration, from negative to positive electrodes, is due to the naturally occurring negative charge carried by their sugar-phosphate backbone.
Double-stranded DNA fragments naturally behave as long rods, so their migration through the gel is relative to their size or, for cyclic fragments, their radius of gyration. Circular DNA such as plasmids, however, may show multiple bands, the speed of migration may depend on whether it is relaxed or supercoiled. Single-stranded DNA or RNA tends to fold up into molecules with complex shapes and migrate through the gel in a complicated manner based on their tertiary structure. Therefore, agents that disrupt the hydrogen bonds, such as sodium hydroxide or formamide, are used to denature the nucleic acids and cause them to behave as long rods again.
Gel electrophoresis of large DNA or RNA is usually done by agarose gel electrophoresis. See the "chain termination method" page for an example of a polyacrylamide DNA sequencing gel. Characterization through ligand interaction of nucleic acids or fragments may be performed by mobility shift affinity electrophoresis.
Electrophoresis of RNA samples can be used to check for genomic DNA contamination and also for RNA degradation. RNA from eukaryotic organisms shows distinct bands of 28s and 18s rRNA, the 28s band being approximately twice as intense as the 18s band. Degraded RNA has less sharply defined bands, has a smeared appearance, and the intensity ratio is less than 2:1. | 1 | Biochemistry |
According to the extremum principle of thermodynamics and , namely that at equilibrium the entropy is a maximum. This leads to a requirement that . This mathematical criterion expresses a physical condition which Epstein described as follows:
"It is obvious that this middle part, dotted in our curves [the place where the requirement is violated, dashed gray in Fig. 1 and repeated here], can have no physical reality. In fact, let us imagine the fluid in a state corresponding to this part of the curve contained in a heat conducting vertical cylinder whose top is formed by a piston. The piston can slide up and down in the cylinder, and we put on it a load exactly balancing the pressure of the gas. If we take a little weight off the piston, there will no longer be equilibrium and it will begin to move upward. However, as it moves the volume of the gas increases and with it its pressure. The resultant force on the piston gets larger, retaining its upward direction. The piston will, therefore, continue to move and the gas to expand until it reaches the state represented by the maximum of the isotherm. Vice versa, if we add ever so little to the load of the balanced piston, the gas will collapse to the state corresponding to the minimum of the isotherm"
While on an isotherm this requirement is satisfied everywhere so all states are gas, those states on an isotherm, which lie between the local minimum, , and local maximum, , for which (shown dashed gray in Fig. 1), are unstable and thus not observed. This is the genesis of the phase change; there is a range , for which no observable states exist. The states for are liquid and for are vapor; due to gravity the denser liquid lies below the vapor. The transition points, states with zero slope, are called spinodal points. Their locus is the spinodal curve that separates the regions of the plane for which liquid, vapor, and gas exist from a region where no observable states exist. This spinodal curve is obtained here from the vdW equation by differentiation (or equivalently from ) as
A projection of this space curve is plotted in Fig. 1 as the black dash dot curve. It passes through the critical point which is also a spinodal point. | 7 | Physical Chemistry |
The first uses of ferrouranium date back to 1897, when the French government attempted to use it for guns. Ferrouranium is used as a deoxidizer (more powerful than ferrovanadium), for denitrogenizing steel, for forming carbides, and as an alloying element. In ferrous alloys, uranium increases the elastic limit and the tensile strength. In high speed steels, it has been used to increase toughness and strength in amounts between 0.05 and 5%. Uranium-alloyed steels can be used at very low temperatures; nickel-uranium alloys are resistant to even very aggressive chemicals, including aqua regia. | 8 | Metallurgy |
* Class "Melainabacteria" ["Vampirovibrionia"; "Vampirovibrionophyceae" ] (ACD20)
** Order "Caenarcanales" ["Caenarcaniphilales" ]
*** Family "Caenarcanaceae"
**** Genus "Ca. Caenarcanum"
***** "Ca. C. bioreactoricola"
** Order "Obscuribacterales"
*** Family "Obscuribacteraceae"
**** Genus "Ca. Obscuribacter"
***** "Ca. O. phosphatis"
** Order "Vampirovibrionales"
*** Family "Vampirovibrionaceae"
**** Genus Vampirovibrio
***** V. chlorellavorus
** Order "Gastranaerophilales"
*** Family CAJFVJ01
**** Genus "Ca. Adamsella"
***** "Ca. A. avium"
*** Family RUG14156
**** Genus "Ca. Galligastranaerophilus"
***** "Ca. G. faecipullorum"
***** "Ca. G. gallistercoris"
***** "Ca. G. intestinavium"
***** "Ca. G. intestinigallinarum"
*** Family "Gastranaerophilaceae"
**** Genus "Ca. Avigastranaerophilus"
***** "Ca. A. faecigallinarum"
**** Genus "Ca. Gastranaerophilus"
***** "Ca. G. phascolarctosicola"
***** "Ca. G. termiticola"
**** Genus "Ca. Limenecus"
***** "Ca. L. avicola"
**** Genus "Ca. Scatenecus"
***** "Ca. S. faecavius"
**** Genus "Ca. Spyradomonas"
***** "Ca. S. excrementavium"
**** Genus "Ca. Stercorousia"
***** "Ca. S. faecigallinarum"
**** Genus "Ca. Scatousia"
***** "Ca. S. excrementigallinarum"
***** "Ca. S. excrementipullorum" | 2 | Environmental Chemistry |
Short-term treatment of mild to moderate pain, including dysmenorrhoea. It is also used for migraines and knee pain. | 4 | Stereochemistry |
Velocyto is a package for the analysis of expression dynamics in single cell RNA seq data. In particular, it enables estimations of RNA velocities of single cells by distinguishing unspliced and spliced mRNAs in standard single-cell RNA sequencing protocols. It is the first paper proposed the concept of RNA velocity. velocyto predicted RNA velocity by solving the proposed differential equations for each gene. The authors envision future manifold learning algorithms that simultaneously fit a manifold and the kinetics on that manifold, on the basis of RNA velocity. | 1 | Biochemistry |
Palladium-catalyzes the cross-coupling of aryl halides with fluorinated arene. The process is unusual in that it involves C–H functionalisation at an electron deficient arene. | 0 | Organic Chemistry |
Topology of a transmembrane protein refers to locations of N- and C-termini of membrane-spanning polypeptide chain with respect to the inner or outer sides of the biological membrane occupied by the protein.
Several databases provide experimentally determined topologies of membrane proteins. They include Uniprot, TOPDB, OPM, and ExTopoDB. There is also a database of domains located conservatively on a certain side of membranes, TOPDOM.
Several computational methods were developed, with a limited success, for predicting transmembrane alpha-helices and their topology. Pioneer methods utilized the fact that membrane-spanning regions contain more hydrophobic residues than other parts of the protein, however applying different hydrophobic scales altered the prediction results. Later, several statistical methods were developed to improve the topography prediction and a special alignment method was introduced. According to the positive-inside rule, cytosolic loops near the lipid bilayer contain more positively-charged amino acids. Applying this rule resulted in the first topology prediction methods. There is also a negative-outside rule in transmembrane alpha-helices from single-pass proteins, although negatively charged residues are rarer than positively charged residues in transmembrane segments of proteins. As more structures were determined, machine learning algorithms appeared. Supervised learning methods are trained on a set of experimentally determined structures, however, these methods highly depend on the training set. Unsupervised learning methods are based on the principle that topology depends on the maximum divergence of the amino acid distributions in different structural parts. It was also shown that locking a segment location based on prior knowledge about the structure improves the prediction accuracy. This feature has been added to some of the existing prediction methods. The most recent methods use consensus prediction (i.e. they use several algorithm to determine the final topology) and automatically incorporate previously determined experimental informations. HTP database provides a collection of topologies that are computationally predicted for human transmembrane proteins.
Discrimination of signal peptides and transmembrane segments is an additional problem in topology prediction treated with a limited success by different methods. Both signal peptides and transmembrane segments contain hydrophobic regions which form α-helices. This causes the cross-prediction between them, which is a weakness of many transmembrane topology predictors. By predicting signal peptides and transmembrane helices simultaneously (Phobius), the errors caused by cross-prediction are reduced and the performance is substantially increased. Another feature used to increase the accuracy of the prediction is the homology (PolyPhobius).”
It is also possible to predict beta-barrel membrane proteins' topology. | 6 | Supramolecular Chemistry |
Two or more methine bridges can overlap, forming a chain or ring of carbon atoms connected by alternating single and double bonds, as in piperylene , or the compound
Every carbon atom in this molecule is a methine carbon atom, except for three; two that are attached to the two nitrogen atoms and not to any hydrogen atoms, and the carbon attached to the nitrogen atom, which is attached to two hydrogen atoms (far right). There is a five-carbon-atom poly-methine chain in the center of this molecule.
Chains of alternating single and double bonds often form conjugated systems. When closed, as in benzene , they often give aromatic character to the compound. | 0 | Organic Chemistry |
Bruce R. Kowalski (March 1942 – December 2012) was an American professor of analytical chemistry who is acknowledged by the world-wide scientific community to be one of the founders of the field of chemometrics. He was the founding editor of Journal of Chemometrics, and the founding director of the Center for Process Analytical Chemistry at University of Washington in Seattle. Kowalski and
Svante Wold formed the Chemometrics Society, which would later become the International Chemometrics Society. | 3 | Analytical Chemistry |
NEM blocks vesicular transport. In lysis buffers, 20 to 25 mM of NEM is used to inhibit de-sumoylation of proteins for Western Blot analysis. NEM has also been used as an inhibitor of deubiquitinases.
N-Ethylmaleimide was used by Arthur Kornberg and colleagues to knock out DNA polymerase III in order to compare its activity to that of DNA polymerase I (pol III and I, respectively). Kornberg had been awarded the Nobel Prize for discovering pol I, then believed to be the mechanism of bacterial DNA replication, although in this experiment he showed that pol III was the actual replicative machinery.
NEM activates ouabain-insensitive Cl-dependent K efflux in low K sheep and goat red blood cells. This discovery contributed to the molecular identification of K-Cl cotransport (KCC) in human embryonic cells transfected by KCC1 isoform cDNA, 16 years later. Since then, NEM has been widely used as a diagnostic tool to uncover or manipulate the membrane presence of K-Cl cotransport in cells of many species in the animal kingdom. Despite repeated unsuccessful attempts to identify chemically the target thiol group, at physiological pH, NEM may form adducts with thiols within protein kinases that phosphorylate KCC at specific serine and threonine residues primarily within the C-terminal domain of the transporter. The ensuing dephosphorylation of KCC by protein phosphatases leads to activation of KCC. | 1 | Biochemistry |
Shadow enhancers are groups of two or more enhancers that control the same target gene and drive overlapping spatiotemporal expression patterns. Shadow enhancers are found in a wide range of organisms, from insects to plants to mammals, particularly in association with developmental genes. While seemingly redundant, the individual enhancers of a shadow enhancer group have been shown to be critical for proper gene expression in the face of both environmental and genetic perturbations. Such perturbations may exacerbate fluctuations in upstream regulators. | 1 | Biochemistry |
Based on the properties of intercalating molecules, i.e. fluorescing upon binding to DNA and unwinding of DNA base-pairs, in 2016, a single-molecule technique has been introduced to directly visualize individual plectonemes along supercoiled DNA which would further allow to study the interactions of DNA processing proteins with supercoiled DNA. In that study, Sytox Orange (an intercalating dye) was used to induce supercoiling on surface tethered DNA molecules.
Using this assay, it was found that the DNA sequence encodes for the position of plectonemic supercoils. Furthermore, DNA supercoils were found to be enriched at the transcription start sites in prokaryotes. | 1 | Biochemistry |
Fatty acid degradation is the process in which fatty acids are broken down into their metabolites, in the end generating acetyl-CoA, the entry molecule for the citric acid cycle, the main energy supply of living organisms, including bacteria and animals. It includes three major steps:
* Lipolysis of and release from adipose tissue
* Activation and transport into mitochondria
* β-oxidation | 1 | Biochemistry |
The parent compound of the phosphines is PH, called phosphine in the US and British Commonwealth, but phosphane elsewhere. Replacement of one or more hydrogen centers by an organic substituents (alkyl, aryl), gives PHR, an organophosphine, generally referred to as phosphines.
From the commercial perspective, the most important phosphine is triphenylphosphine, several million kilograms being produced annually. It is prepared from the reaction of chlorobenzene, PCl, and sodium. Phosphines of a more specialized nature are usually prepared by other routes. Phosphorus halides undergo nucleophilic displacement by organometallic reagents such as Grignard reagents. Organophosphines are nucleophiles and ligands. Two major applications are as reagents in the Wittig reaction and as supporting phosphine ligands in homogeneous catalysis.
Their nucleophilicity is evidenced by their reactions with alkyl halides to give phosphonium salts. Phosphines are nucleophilic catalysts in organic synthesis, e.g. the Rauhut–Currier reaction and Baylis-Hillman reaction. Phosphines are reducing agents, as illustrated in the Staudinger reduction for the conversion of organic azides to amines and in the Mitsunobu reaction for converting alcohols into esters. In these processes, the phosphine is oxidized to phosphorus(V). Phosphines have also been found to reduce activated carbonyl groups, for instance the reduction of an α-keto ester to an α-hydroxy ester. | 0 | Organic Chemistry |
Cure monitoring is, for example, an essential component for the control of the manufacturing process of composite materials.
The material, initially liquid, at the end of the process will be solid: viscosity is the most important property that changes during the process.
Cure monitoring relies on monitoring various physical or chemical properties. | 7 | Physical Chemistry |
Due to the proximity of the Westinghouse site and other former manufacturing sites to the Watsessing Station, the Township of Bloomfield worked on the plan for transit-oriented development in that area. The Westinghouse site, although a brownfield site with ongoing remediation at the time, was re-zoned into Commuter Oriented Residential District which was a mixed-use concept that included high-density residential units which would be close to the train station.
The redevelopment was completed. The luxury apartments were marketed as "The Grove at Watsessing" which was part of the "Grove Crossing" complex. | 8 | Metallurgy |
A brass mill is a mill which processes brass. Brass mills are common in England; many date from long before the Industrial Revolution.
;Examples of brass mills include:
*Brassmill (Ross on Wye)
*Saltford Brass Mill | 8 | Metallurgy |
Lattice systems are a grouping of crystal structures according to the point groups of their lattice. All crystals fall into one of seven lattice systems. They are related to, but not the same as the seven crystal systems.
The most symmetric, the cubic or isometric system, has the symmetry of a cube, that is, it exhibits four threefold rotational axes oriented at 109.5° (the tetrahedral angle) with respect to each other. These threefold axes lie along the body diagonals of the cube. The other six lattice systems, are hexagonal, tetragonal, rhombohedral (often confused with the trigonal crystal system), orthorhombic, monoclinic and triclinic. | 3 | Analytical Chemistry |
Her awards and honours include;
* 2012 European Research Council Starting Grant
* 2012 University of Twente De Winter Prize
* 2014 Elected to the Royal Netherlands Academy of Arts and Sciences Young Academy
* 2016 Netherlands Organisation for Scientific Research Athena Award
* 2016 Elected a member of the Global Young Academy
* 2016 Elected to the Council for Physics and Chemistry
* 2017 Royal Netherlands Chemical Society Gold Medal
* 2018 European Research Council Consolidator Grant | 0 | Organic Chemistry |
A galvanic anode, or sacrificial anode, is the main component of a galvanic cathodic protection system used to protect buried or submerged metal structures from corrosion.
They are made from a metal alloy with a more "active" voltage (more negative reduction potential / more positive electrode potential) than the metal of the structure. The difference in potential between the two metals means that the galvanic anode corrodes, in effect being "sacrificed" in order to protect the structure. | 7 | Physical Chemistry |
Numerous hybrid organic–inorganic materials that contain POM cores,
Illustrative of the diverse structures of POM is the ion , which has face-shared octahedra with Mo atoms at the vertices of an icosahedron). | 7 | Physical Chemistry |
* Bangladesh:
** Bengal Police started using pepper spray to control opposition movement.
* China: Forbidden for civilians, it is used only by law enforcement agencies. Underground trade leads to some civilian self-defense use.
** Hong Kong: Forbidden for civilians, it is legal to possess and use only by the members of Disciplined Services when on duty.
*** Such devices are classified as "arms" under the "Laws of Hong Kong". Chap 238 Firearms and Ammunition Ordinance. Without a valid license from the Hong Kong Police Force, it is a crime to possess and can result in a fine of $100,000 and imprisonment for up to 14 years.
* India: Legal
** They are sold via government-approved companies after performing a background verification.
* Indonesia: It is legal, but there are restrictions on its sale and possession.
* Iran: Forbidden for civilians, it is used only by the police.
* Israel: OC and CS spray cans may be purchased by any member of the public without restriction and carried in public.
** In the 1980s, a firearms license was required for doing so, but these sprays have since been deregulated.
* Japan: There are no laws against possession or use, but using it could result in imprisonment, depending on the damage caused to the target.
* Malaysia: Use and possession of pepper spray for self-defense are legal.
* Mongolia: Possession and use for self-defense are legal, and it is freely available in stores.
* Pakistan: Possession and use for self-defense is legal and its available at physical and online stores.
* Philippines: Possession and use for self-defense is legal, and it is freely available in stores.
* Saudi Arabia: Use and possession of pepper spray for self-defense are legal.
** It is an offense to use pepper spray on anyone for reasons other than self-defense.
* Singapore: Travellers are prohibited from bringing pepper spray into the country, and it is illegal for the public to possess it.
* South Korea: Pepper sprays containing OC are legal.
** Requires a permit to distribute, own, carry pepper sprays containing pre-compressed gas or explosive propellent.
** Pepper sprays without any pre-compressed gas or explosive propellent are unrestricted.
* Thailand: Use for self-defense is legal, and it is freely available in stores.
** Possession in a public place can be punished by confiscation and a fine.
* Taiwan: Legal for self-defense, it is available in some shops.
** It is an offense to use pepper spray on anyone for reasons other than self-defense.
* Vietnam: Forbidden for civilians and used only by the police. | 1 | Biochemistry |
When atoms or molecules are adsorbed on a surface, two phenomena can lead to a change in the surface stress. One is a change in the electron density of the atoms in the surface, which changes the in-plane bonding and thus the surface stress. A second is due to interactions between the adsorbed atoms or molecules themselves, which may want to be further apart (or closer) than is possible with the atomic spacings in the surface. Note that since adsorption often depends strongly upon the environment, for instance gas pressure and temperature, the surface stress tensor will show a similar dependence. | 7 | Physical Chemistry |
Gelation of polymers can be described in the framework of the Erdős–Rényi model or the Lushnikov model, which answers the question when a giant component arises. | 7 | Physical Chemistry |
Several chemicals can eliminate cyanobacterial blooms from smaller water-based systems such as swimming pools. They include calcium hypochlorite, copper sulphate, Cupricide (chelated copper), and simazine. The calcium hypochlorite amount needed varies depending on the cyanobacteria bloom, and treatment is needed periodically. According to the Department of Agriculture Australia, a rate of 12 g of 70% material in 1000 L of water is often effective to treat a bloom. Copper sulfate is also used commonly, but no longer recommended by the Australian Department of Agriculture, as it kills livestock, crustaceans, and fish. Cupricide is a chelated copper product that eliminates blooms with lower toxicity risks than copper sulfate. Dosage recommendations vary from 190 mL to 4.8 L per 1000 m. Ferric alum treatments at the rate of 50 mg/L will reduce algae blooms. Simazine, which is also a herbicide, will continue to kill blooms for several days after an application. Simazine is marketed at different strengths (25, 50, and 90%), the recommended amount needed for one cubic meter of water per product is 25% product 8 mL; 50% product 4 mL; or 90% product 2.2 mL. | 5 | Photochemistry |
Genetic mutations occur when nucleotide sequences in an organism are altered. These mutations lead to not only observable phenotypic influences in an individual, but also alterations that are undetectable phenotypically. The sources for these mutations can be errors during replication, spontaneous mutations, and chemical and physical mutagens (UV and ionizing radiation, heat). Silencers, being encoded in the genome, are susceptible to such alterations which, in many cases, can lead to severe phenotypical and functional abnormalities. In general terms, mutations in silencer elements or regions could lead to either the inhibition of the silencers action or to the persisting repression of a necessary gene. This can then lead to the expression or suppression of an undesired phenotype which may affect the normal functionality of certain systems in the organism. Among the many silencer elements and proteins, REST/NSRF is an important silencer factor that has a variety of impacts, not only in neural aspects of development. In fact, in many cases, REST/NSRF acts in conjunction with RE-1/NRSE to repress and influence non-neuronal cells. Its effects range from frogs (Xenopus laevis) to humans, with innumerous effects in phenotype and also in development. In Xenopus laevis, REST/NRSF malfunction or damage has been associated to abnormal ectodermal patterning during development and significant consequences in neural tube, cranial ganglia, and eye development. In humans, a deficiency in the REST/NSRF silencer element has been correlated to Huntingtons disease due to the decrease in the transcription of BDNF.
Furthermore, ongoing studies indicate that NRSE is involved in the regulation of the ANP gene, which when over expressed, can lead to ventricular hypertrophy. Mutations in the Polycomb-group (PcG) complexes also presented significant modifications in physiological systems of organisms. Hence, modification in silencer elements and sequences can result in either devastating or unnoticeable changes. | 1 | Biochemistry |
Levocetirizine was first launched in 2001 by the Belgian pharmaceutical company UCB (Union Chimique Belge). | 4 | Stereochemistry |
Steady-states can be stable or unstable. A steady-state is unstable if a small perturbation in one or more of the concentrations results in the system diverging from its state. In contrast, if a steady-state is stable, any perturbation will relax back to the original steady state. Further details can be found on the page Stability theory. | 7 | Physical Chemistry |
A majority of the adhesion GPCRs are orphan receptors and work is underway to de-orphanize many of these receptors. Adhesion GPCRs get their name from their N-terminal domains that have adhesion-like domains, such as EGF, and the belief that they interact cell to cell and cell to extra cellular matrix. While ligands for many receptors are still not known, researchers are utilizing drug libraries to investigate compounds that can activate GPCRs and using these data for future ligand research.
One adhesion GPCR, GPR56, has a known ligand, collagen III, which is involved in neural migration inhibition. GPR56 has been shown to be the cause of polymicrogyria in humans and may play a role in cancer metastasis. The binding of collagen III to GPR56 occurs on the N-terminus and has been narrowed down to a short stretch of amino acids. The N-terminus of GPR56 is naturally glycosylated, but this glycosylation is not necessary for collagen III binding. Collagen III, results in GPR56 to signal through Gα12/13 activating RhoA. | 1 | Biochemistry |
Molecular tweezers, and molecular clips, are host molecules with open cavities capable of binding guest molecules. The open cavity of the molecular tweezers may bind guests using non-covalent bonding, which includes hydrogen bonding, metal coordination, hydrophobic forces, van der Waals forces, π–π interactions, and/or electrostatic effects. These complexes are a subset of macrocyclic molecular receptors and their structure is that the two "arms" that bind the guest molecule between them are only connected at one end leading to a certain flexibility of these receptor molecules (induced fit model). | 6 | Supramolecular Chemistry |
A reading frame is defined by the initial triplet of nucleotides from which translation starts. It sets the frame for a run of successive, non-overlapping codons, which is known as an "open reading frame" (ORF). For example, the string 5-AAATGAACG-3 (see figure), if read from the first position, contains the codons AAA, TGA, and ACG ; if read from the second position, it contains the codons AAT and GAA ; and if read from the third position, it contains the codons ATG and AAC. Every sequence can, thus, be read in its 5 → 3 direction in three reading frames, each producing a possibly distinct amino acid sequence: in the given example, Lys (K)-Trp (W)-Thr (T), Asn (N)-Glu (E), or Met (M)-Asn (N), respectively (when translating with the vertebrate mitochondrial code). When DNA is double-stranded, six possible reading frames are defined, three in the forward orientation on one strand and three reverse on the opposite strand. Protein-coding frames are defined by a start codon, usually the first AUG (ATG) codon in the RNA (DNA) sequence.
In eukaryotes, ORFs in exons are often interrupted by introns. | 1 | Biochemistry |
(AD 900–1500)
Objects of personal adornment and ceremonial objects
#Cerro Montoso, Veracruz
#Chachalacas, Veracruz
#El Tajin, Veracruz
#Isla de Sacrificios, Veracruz
#Pánuco, Veracruz
#Tampico, Veracruz | 8 | Metallurgy |
Sociedad Española de Construcciones Electromecánicas (abbreviated as SECEM), colloquially known as "electro", was a Spanish company in the non-ferrous metals industry that operated between 1917 and 1978. Throughout its existence it was one of the most important Spanish companies in the copper sector, having its main activity in Córdoba. Among its products were copper products, brass, electrical transformers, etc. | 8 | Metallurgy |
Proteases may be classified according to the catalytic group involved in its active site.
*Cysteine protease
*Serine protease
*Threonine protease
*Aspartic protease
*Glutamic protease
*Metalloprotease
*Asparagine peptide lyase | 1 | Biochemistry |
In spectral scanning, each 2-D sensor output represents a monochromatic (single-colored), spatial (x, y) map of the scene. HSI devices for spectral scanning are typically based on optical band-pass filters (either tunable or fixed). The scene is spectrally scanned by exchanging one filter after another while the platform remains stationary. In such staring, wavelength scanning systems, spectral smearing can occur if there is movement within the scene, invalidating spectral correlation/detection. Nonetheless, there is the advantage of being able to pick and choose spectral bands, and having a direct representation of the two spatial dimensions of the scene. If the imaging system is used on a moving platform, such as an airplane, acquired images at different wavelengths corresponds to different areas of the scene. The spatial features on each of the images may be used to realign the pixels. | 7 | Physical Chemistry |
Zinc-finger nucleases consist of DNA binding domains that can precisely target a DNA sequence. Each zinc-finger can recognize codons of a desired DNA sequence, and therefore can be modularly assembled to bind to a particular sequence. These binding domains are coupled with a restriction endonuclease that can cause a double stranded break (DSB) in the DNA. Repair processes may introduce mutations that destroy functionality of the gene. | 1 | Biochemistry |
PBr evolves corrosive HBr, which is toxic, and reacts violently with water and alcohols.
:PBr + 3 HO → HPO + 3 HBr
In reactions that produce phosphorous acid as a by-product, when working up by distillation be aware that this can decompose above about 160 °C to give phosphine which can cause explosions in contact with air. | 0 | Organic Chemistry |
The world's dependence on the declining reserves of fossil fuels poses not only environmental problems but also geopolitical ones. Solar fuels, in particular hydrogen, are viewed as an alternative source of energy for replacing fossil fuels especially where storage is essential. Electricity can be produced directly from sunlight through photovoltaics, but this form of energy is rather inefficient to store compared to hydrogen. A solar fuel can be produced when and where sunlight is available, and stored and transported for later usage. This makes it much more convenient, because it can be used in situations where direct sunlight is not available.
The most widely researched solar fuels are hydrogen, because the only product of using this fuel is water, and products of photochemical carbon dioxide reduction, which are more conventional fuels like methane and propane. Upcoming research also involves ammonia and related substances (i.e. hydrazine). These can address the challenges that come with hydrogen, by being a more compact and safer way of storing hydrogen. Direct ammonia fuel cells are also being researched.
Solar fuels can be produced via direct or indirect processes. Direct processes harness the energy in sunlight to produce a fuel without intermediary energy conversions. Solar thermochemistry uses the heat of the sun directly to heat a receiver adjacent to the solar reactor where the thermochemical process is performed. In contrast, indirect processes have solar energy converted to another form of energy first (such as biomass or electricity) that can then be used to produce a fuel. Indirect processes have been easier to implement but have the disadvantage of being less efficient than the direct method. Therefore, direct methods should be considered more interesting than their less efficient counterparts. New research therefore focusses more on this direct conversion, but also in fuels that can be used immediately to balance the power grid. | 5 | Photochemistry |
The initiating methionine (and, in prokaryotes, fMet) may be removed during translation of the nascent protein. For E. coli, fMet is efficiently removed if the second residue is small and uncharged, but not if the second residue is bulky and charged. In both prokaryotes and eukaryotes, the exposed N-terminal residue may determine the half-life of the protein according to the N-end rule. | 1 | Biochemistry |
The radicle is the first part of a seedling (a growing plant embryo) to emerge from the seed during the process of germination. The radicle is the embryonic root of the plant, and grows downward in the soil (the shoot emerges from the plumule) where it absorbs more water. Most part of the seed is stored energy so nutrients are not essential during the first days for the seedling. | 7 | Physical Chemistry |
The following process models are commonly applied to geometallurgy:
* The Bond equation
* The SPI calibration equation, CEET
* FLEET*
* SMC model
* Aminpro-Grind, Aminpro-Flot models | 8 | Metallurgy |
The isochore theory was the first to identify the nonuniformity of nucleotide composition within vertebrate genomes and predict that the genome of "warm-blooded" vertebrates such as mammals and birds are mosaic of isochores (Bernardi et al. 1985). The human genome, for example, was described as a mosaic of alternating low and high GC content isochores belonging to five compositional families, L1, L2, H1, H2, and H3, whose corresponding ranges of GC contents were said to be <38%, 38%-42%, 42%-47%, 47%-52%, and >52%, respectively.
The main predictions of the isochore theory are that:
* GC content of the third codon position (GC3) of protein coding genes is correlated with the GC content of the isochores embedding the corresponding genes.
* The genome organization of warm-blooded vertebrates is a mosaic of mostly GC-rich isochores.
* Genome organization of cold-blooded vertebrates is characterized by low GC content levels and lower compositional heterogeneity than warm-blooded vertebrates. Homogeneous domains do not reach the high GC levels attained by the genomes of warm-blooded vertebrates. | 1 | Biochemistry |
In a recent study, the production of pyoverdine (PVD), a type of siderophore, in the bacterium Pseudomonas aeruginosa has been explored. This study focused on the construction, modeling, and dynamic simulation of PVD biosynthesis, a virulence factor, through a systemic approach. This approach considers that the metabolic pathway of PVD synthesis is regulated by the phenomenon of quorum-sensing (QS), a cellular communication system that allows bacteria to coordinate their behavior based on their population density.
The study showed that as bacterial growth increases, so does the extracellular concentration of QS signaling molecules, thus emulating the natural behavior of P. aeruginosa PAO1. To carry out this study, a metabolic network model of P. aeruginosa was built based on the iMO1056 model, the genomic annotation of the P. aeruginosa PAO1 strain, and the metabolic pathway of PVD synthesis. This model included the synthesis of PVD, transport reactions, exchange, and QS signaling molecules.
The resulting model, called CCBM1146, showed that the QS phenomenon directly influences the metabolism of P. aeruginosa towards the biosynthesis of PVD as a function of the change in QS signal intensity. This work is the first in silico report of an integrative model that comprises the QS gene regulatory network and the metabolic network of P. aeruginosa, providing a detailed view of how the production of pyoverdine and siderophores in Pseudomonas aeruginosa are influenced by the quorum-sensing phenomenon | 1 | Biochemistry |
Most of the codes apply to arbitrary-shaped inhomogeneous nonmagnetic particles and particle systems in free space or homogeneous dielectric host medium. The calculated quantities typically include the Mueller matrices, integral cross-sections (extinction, absorption, and scattering), internal fields and angle-resolved scattered fields (phase function). There are some published comparisons of existing DDA codes. | 7 | Physical Chemistry |
He studied at the University of Kazan where he graduated in mathematics but he started teaching chemistry in 1835. To improve his skills he was asked to study in Europe for some time, which he did between 1838 and 1841. He studied with Justus Liebig in Giessen, where he finished his research on the benzoin condensation, which was discovered by Liebig several years before. He presented his research results at the University of Saint Petersburg, where he received his Ph.D. He became Professor for Chemistry in the same year at the University of Kazan and left for the University of Saint Petersburg in 1847 where he also became a member of the St. Petersburg Academy of Sciences and first president of the Russian Physical and Chemical Society (1868–1877).
In St. Petersburg, professor Zinin was a private teacher of chemistry to the young Alfred Nobel. | 0 | Organic Chemistry |
Loosely speaking, the existence or construction of a periodic table of elements creates an ordering of the elements, and so they can be numbered in order.
Dmitri Mendeleev said that he arranged his first periodic tables (first published on March 6, 1869) in order of atomic weight ("Atomgewicht"). However, in consideration of the elements observed chemical properties, he changed the order slightly and placed tellurium (atomic weight 127.6) ahead of iodine (atomic weight 126.9). This placement is consistent with the modern practice of ordering the elements by proton number, Z', but that number was not known or suspected at the time.
A simple numbering based on periodic table position was never entirely satisfactory. In addition to the case of iodine and tellurium, several other pairs of elements (such as argon and potassium, cobalt and nickel) were later shown to have nearly identical or reversed atomic weights, thus requiring their placement in the periodic table to be determined by their chemical properties. However the gradual identification of more and more chemically similar lanthanide elements, whose atomic number was not obvious, led to inconsistency and uncertainty in the periodic numbering of elements at least from lutetium (element 71) onward (hafnium was not known at this time). | 3 | Analytical Chemistry |
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