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Due to the similarity in mass and nuclear properties between the proton and neutron, they are sometimes considered as two symmetric types of the same object, a nucleon. While only the proton has an electric charge, this is often negligible due to the weakness of the electromagnetic interaction relative to the strong nuclear interaction. The symmetry relating the proton and neutron is known as isospin and denoted I (or sometimes T).
Isospin is an SU(2) symmetry, like ordinary spin, so is completely analogous to it. The proton and neutron, each of which have isospin-, form an isospin doublet (analogous to a spin doublet), with a "down" state (↓) being a neutron and an "up" state (↑) being a proton. A pair of nucleons can either be in an antisymmetric state of isospin called singlet, or in a symmetric state called triplet. In terms of the "down" state and "up" state, the singlet is
:, which can also be written :
This is a nucleus with one proton and one neutron, i.e. a deuterium nucleus. The triplet is
and thus consists of three types of nuclei, which are supposed to be symmetric: a deuterium nucleus (actually a highly excited state of it), a nucleus with two protons, and a nucleus with two neutrons. These states are not stable. | 9 | Geochemistry |
Of the known types of bronze or brass, not distinguished in classical antiquity and interchangeably known in Latin as aes and in Greek as χαλκός, Corinthian bronze was the most valuable. Statues, vases and vessels, or other objects formed of this metal were priceless, of greater value than if they had been made of silver or gold. Pliny the Elder distinguished it into three kinds, depending on the metal that is added to the copper base: in the first, gold is added (luteum); in the second, silver (candidum); in the third, gold, silver, and copper are equally blended. Plutarch and Cicero both comment that Corinthian bronze, unlike many other copper alloys, is resistant to tarnishing. Pliny also refers to a fourth, dark alloy, known as hepatizon. Petronius and other authors mocked the connoisseurs of their day who claimed to be able to identify it.
According to legend, Corinthian bronze was first created by accident, during the burning of Corinth by Lucius Mummius Achaicus in 146 BC, when the city's immense quantities of gold, silver, and copper melted together. Pliny however, remarked that this story is unbelievable, because most of the creators of the highly valued works in Corinthian bronze in Ancient Greece lived at a much earlier period than second century BC. According to Pliny, the method of making it had been lost for a long time, although some sources describe the process by which it is created, involving heat treatment, quenching, leaching, and burnishing, in a process similar to depletion gilding. The lost ability to give an object made from bronze the appearance of gold or silver may be one strand behind the later alchemical quest to turn base metals into precious metals. | 8 | Metallurgy |
Cell proliferation is often regulated by not only external mitogens but also by anti-mitogens, which inhibit cell cycle progression past G1. In normal cells, anti-mitogenic signaling as a result of DNA damage, preventing the cells from replicating and dividing. Tumor cells that are resistant to anti-mitogens allow the cell cycle to move forward when it should be prevented by some anti-mitogenic mechanism. This resistance to anti-mitogens might simply arise from overstimulation by positive mitogens. In other cases, tumor cells possess loss-of-function mutations in some part of the anti-mitogenic pathway. For example, consider the well-known anti-mitogen, transforming growth factor (TGF-𝝱). TGF-𝝱 works by binding to cell-surface receptors and activating the Smad gene regulatory proteins. Smad proteins then trigger an increase in p15, which inhibits cyclin D1 and prevents cell cycle progression. In many cancers, there is a loss-of-function mutation in the Smad proteins, thus negating the entire anti-mitogenic pathway. | 1 | Biochemistry |
In physics, ferroics is the generic name given to the study of ferromagnets, ferroelectrics, and ferroelastics. | 7 | Physical Chemistry |
Because the motor events are stochastic, molecular motors are often modeled with the Fokker–Planck equation or with Monte Carlo methods. These theoretical models are especially useful when treating the molecular motor as a Brownian motor. | 6 | Supramolecular Chemistry |
For many non-coding RNAs, including tRNA, rRNA, snRNA, and snoRNA, polyadenylation is a way of marking the RNA for degradation, at least in yeast. This polyadenylation is done in the nucleus by the TRAMP complex, which maintains a tail that is around 4 nucleotides long to the 3′ end. The RNA is then degraded by the exosome. Poly(A) tails have also been found on human rRNA fragments, both the form of homopolymeric (A only) and heterpolymeric (mostly A) tails. | 1 | Biochemistry |
The simplest diffraction technique in TEM is selected area electron diffraction (SAED) where the incident beam is wide and close to parallel. An aperture is used to select a particular region of interest from which the diffraction is collected. These apertures are part of a thin foil of a heavy metal such as tungsten which has a number of small holes in it. This way diffraction information can be limited to, for instance, individual crystallites. Unfortunately the method is limited by the spherical aberration of the objective lens, so is only accurate for large grains with tens of thousands of atoms or more; for smaller regions a focused probe is needed.
If a parallel beam is used to acquire a diffraction pattern from a single-crystal, the result is similar to a two-dimensional projection of the crystal reciprocal lattice. From this one can determine interplanar distances and angles and in some cases crystal symmetry, particularly when the electron beam is down a major zone axis, see for instance the database by Jean-Paul Morniroli. However, projector lens aberrations such as barrel distortion as well as dynamical diffraction effects (e.g.) cannot be ignored. For instance, certain diffraction spots which are not present in x-ray diffraction can appear, for instance those due to Gjønnes-Moodie extinction conditions.
If the sample is tilted relative to the electron beam, different sets of crystallographic planes contribute to the pattern yielding different types of diffraction patterns, approximately different projections of the reciprocal lattice, see Figure 11. This can be used to determine the crystal orientation, which in turn can be used to set the orientation needed for a particular experiment. Furthermore, a series of diffraction patterns varying in tilt can be acquired and processed using a diffraction tomography approach. There are ways to combine this with direct methods algorithms using electrons and other methods such as charge flipping, or automated diffraction tomography to solve crystal structures. | 7 | Physical Chemistry |
Push-pull agriculture leads to beneficial economic outcomes on the level of individual smallholder and subsistence farmers through larger income streams coming from the sale of surplus grain, desmodium seeds, fodder, and milk. Economic study has calculated the return on investment of push-pull methods for farmers to be over 2.2 as compared to 1.8 for pesticide use, and .8 for monocrop. Although startup costs of push-pull technology are highly variable due to the requirements of labor to plant desmodium and Napier grass and purchase of these seeds, costs significantly decline in following growing years. Push-pull technology has also been seen to help boost local economies. Because these farmers have more income, they are able to spend money in their local economy which boosts the standards of living and prosperity of the community at large.
The primary economic opponents to such methods are large multinational corporations such as Monsanto and others that produce seasonal inputs such as chemical pesticides, fertilizers and high-yield seeds that require such inputs.
After controlling for extraneous maize yield determinants, it was found that there was a 61.9% maize yield increase with a 15.3% increase in the cost of maize production and a 38.6% increase in the average net income brought in from maize.
In households where push-pull technology has been adopted in Kenya, increased economic earnings have been associated with more years of education, improved access to rural institutions, and attendance to a larger number of field days when compared with households that have not adopted the technology. Additionally, if adoption of the technology continues at the current rate of 14.4%, a reduction of 75,077 people considered poor could be expected in a situation where the local economies remain closed, and 76,504 fewer people could be expected to be considered poor if the economies were open. | 1 | Biochemistry |
Luminol (CHNO) is a chemical that exhibits chemiluminescence, with a blue glow, when mixed with an appropriate oxidizing agent. Luminol is a white-to-pale-yellow crystalline solid that is soluble in most polar organic solvents, but insoluble in water.
Forensic investigators use luminol to detect trace amounts of blood at crime scenes, as it reacts with the iron in hemoglobin. Biologists use it in cellular assays to detect copper, iron, cyanides, as well as specific proteins via western blotting.
When luminol is sprayed evenly across an area, trace amounts of an activating oxidant make the luminol emit a blue glow that can be seen in a darkened room. The glow only lasts about 30 seconds, but can be documented photographically. The glow is stronger in areas receiving more spray; the intensity of the glow does not indicate the amount of blood or other activator present. | 3 | Analytical Chemistry |
The ability of enhancers to activate imprinted genes is dependent on the presence of an insulator on the unmethylated allele between the two genes. An example of this is the Igf2-H19 imprinted locus. In this locus the CTCF protein regulates imprinted expression by binding to the unmethylated maternal imprinted control region (ICR) but not on the paternal ICR. When bound to the unmethylated maternal sequence, CTCF effectively blocks downstream enhancer elements from interacting with the Igf2 gene promoter, leaving only the H19 gene to be expressed. | 1 | Biochemistry |
Buccianti was the 2003 winner of the Felix Chayes Prize of the International Association for Mathematical Geosciences. | 9 | Geochemistry |
* KEGG Pathway database is a popular pathway search database highly used by biologists.
* WikiPathways is a community curated pathway database using the "wiki" concept. All pathways have an open license and can be freely used.
* Reactome is a free and manually curated online database of biological pathways.
* NCI-Nature Pathway Interaction Database is a free biomedical database of human cellular signaling pathways (new official name: NCI Nature Pathway Interaction Database: Pathway, synonym: PID).
* PhosphoSitePlus is a database of observed post-translational modifications in human and mouse proteins; an online systems biology resource providing comprehensive information and tools for the study of protein post-translational modifications (PTMs) including phosphorylation, ubiquitination, acetylation and methylation.
* BioCyc database collection is an assortment of organism specific Pathway/Genome Databases.
* Human Protein Reference Database is a centralized platform to visually depict and integrate information pertaining to domain architecture, post-translational modifications, interaction networks and disease association for each protein in the human proteome (the last release was #9 in 2010).
* PANTHER (Protein ANalysis THrough Evolutionary Relationships) is a large curated biological database of gene/protein families and their functionally related subfamilies that can be used to classify and identify the function of gene products.
* TRANSFAC (TRANScription FACtor database) is a manually curated database of eukaryotic transcription factors, their genomic binding sites and DNA binding profiles (provided by geneXplain GmbH).
* MiRTarBase is a curated database of MicroRNA-Target Interactions.
* DrugBank is a comprehensive, high-quality, freely accessible, online database containing information on drugs and drug targets.
* esyN is a network viewer and builder that allows to import pathways from the biomodels database or from biogrid, flybase pombase and see what drugs interact with the proteins in your network.
* Comparative Toxicogenomics Database (CTD) is a public website and research tool that curates scientific data describing relationships between chemicals/drugs, genes/proteins, diseases, taxa, phenotypes, GO annotations, pathways, and interaction modules; CTD illuminates how environmental chemicals affect human health.
* Pathway commons is a project and database that uses BioPAX language to convert, integrate and query other biological pathway and interaction databases. | 1 | Biochemistry |
The Gaia theorem states that the Earth's atmospheric composition is kept at a dynamically steady state by the presence of life. The atmospheric composition provides the conditions that contemporary life has adapted to. All the atmospheric gases other than noble gases present in the atmosphere are either made by organisms or processed by them.
The stability of the atmosphere in Earth is not a consequence of chemical equilibrium. Oxygen is a reactive compound, and should eventually combine with gases and minerals of the Earth's atmosphere and crust. Oxygen only began to persist in the atmosphere in small quantities about 50 million years before the start of the Great Oxygenation Event. Since the start of the Cambrian period, atmospheric oxygen concentrations have fluctuated between 15% and 35% of atmospheric volume. Traces of methane (at an amount of 100,000 tonnes produced per year) should not exist, as methane is combustible in an oxygen atmosphere.
Dry air in the atmosphere of Earth contains roughly (by volume) 78.09% nitrogen, 20.95% oxygen, 0.93% argon, 0.039% carbon dioxide, and small amounts of other gases including methane. Lovelock originally speculated that concentrations of oxygen above about 25% would increase the frequency of wildfires and conflagration of forests. This mechanism, however, would not raise oxygen levels if they became too low. If plants can be shown to robustly over-produce O then perhaps only the high oxygen forest fires regulator is necessary. Recent work on the findings of fire-caused charcoal in Carboniferous and Cretaceous coal measures, in geologic periods when O did exceed 25%, has supported Lovelock's contention. | 9 | Geochemistry |
A stannide can refer to an intermetallic compound containing tin combined with one or more other metals; an anion consisting solely of tin atoms or a compound containing such an anion, or, in the field of organometallic chemistry an ionic compound containing an organotin anion (e.g.see an alternative name for such a compound is stannanide.) | 7 | Physical Chemistry |
Like all other soluble aerosols, increasing normal-sized sea salts suppresses the precipitation process in warm clouds by increasing cloud droplet number concentration and reducing the cloud droplet size. Also, they invigorate precipitation in mix-phase clouds because once the suppressed smaller cloud droplets are lifted above freezing level, more latent heat content would be released due to the freezing of cloud drops. Besides that, adding giant sea salt aerosols to polluted clouds can accelerate the precipitation process because giant CCNs could be nucleated into large particles which collect other smaller cloud drops and grow into rain droplets. Cloud drops formed on giant sea salt aerosols may grow much more rapidly by condensation that cloud drops formed on small soluble aerosol particles, as giant sea salt cloud drops may remain concentrated solution drops for long times after they are carried into cloud. Such drops may have condensational growth rates more than two times faster than drops formed on small aerosol particles, and unlike normal cloud drops, drops formed on the largest of the giant sea salt aerosols may even grow by condensation in otherwise subsaturated cloudy downdrafts. | 9 | Geochemistry |
In the original work, Cornforth used 5-ethoxy-2-phenyloxazole-4-carboxamide (R = phenyl, R = ethoxy, R = amino).
The reaction also works, however, with a large number of other carbonyl-substituted 1,3-oxazoles.
In the early 1970s, the reaction was further researched by Michael Dewar. It was shown that the reaction gave good yields, over 90%, when using nitrogen-containing heterocycles at the R position. | 0 | Organic Chemistry |
Crassulacean acid metabolism, also known as CAM photosynthesis, is a carbon fixation pathway that evolved in some plants as an adaptation to arid conditions that allows a plant to photosynthesize during the day, but only exchange gases at night. In a plant using full CAM, the stomata in the leaves remain shut during the day to reduce evapotranspiration, but they open at night to collect carbon dioxide () and allow it to diffuse into the mesophyll cells. The is stored as four-carbon malic acid in vacuoles at night, and then in the daytime, the malate is transported to chloroplasts where it is converted back to , which is then used during photosynthesis. The pre-collected is concentrated around the enzyme RuBisCO, increasing photosynthetic efficiency. This mechanism of acid metabolism was first discovered in plants of the family Crassulaceae. | 5 | Photochemistry |
Arginase is a binuclear manganese metalloprotein that catalyses the hydrolysis of L-arginine to L-ornithine and urea. It is also regarded as a drug target for the treatment of asthma. The mechanism of hydrolysis of L-arginine is carried out via nucleophilic attack on the guanidino group by water, forming a tetrahedral intermediate. Studies shown that a boronic acid moiety adopts a tetrahedral configuration and serves as an inhibitor. In addition, the sulfonamide functional group can also mimic the transition state structure. Evidence of boronic acid mimics as transition state analogue inhibitors of human arginase I was elucidated by x-ray crystal structures. | 1 | Biochemistry |
The reaction is used in a chemical test for the detection of aldehydes in combination with ferric chloride. In this test a few drops of aldehyde containing specimen is dissolved in ethanol, the sulfonamide is added together with some sodium hydroxide solution and then the solution is acidified to Congo red. An added drop of ferric chloride will turn the solution an intense red when aldehyde is present. The sulfonamide can be prepared by reaction of hydroxylamine and benzenesulfonyl chloride in ethanol with potassium metal. | 3 | Analytical Chemistry |
Toxicants that at low concentrations modify or inhibit some biological process by binding at a specific site or molecule have a specific acting mode of toxic action. However, at high enough concentrations, toxicants with specific acting modes of toxic actions can produce narcosis that may or may not be reversible. Nevertheless, the specific action of the toxicant is always shown first because it requires lower concentrations.
There are several specific acting modes of toxic action:
* Uncouplers of oxidative phosphorylation. Involves toxicants that uncouple the two processes that occur in oxidative phosphorylation: electron transfer and adenosine triphosphate (ATP) production.
* Acetylcholinesterase (AChE) inhibitors. AChE is an enzyme associated with nerve synapses that it’s designed to regulate nerve impulses by breaking down the neurotransmitter Acetylcholine (ACh). When toxicants bind to AChE, they inhibit the breakdown of ACh. This results in continued nerve impulses across the synapses, which eventually cause nerve system damage. Examples of AChE inhibitors are organophosphates and carbamates, which are components found in pesticides (see Acetylcholinesterase inhibitors).
* Irritants. These are chemicals that cause an inflammatory effect on living tissue by chemical action at the site of contact. The resulting effect of irritants is an increase in the volume of cells due to a change in size (hypertrophy) or an increase in the number of cells (hyperplasia). Examples of irritants are benzaldehyde, acrolein, zinc sulphate and chlorine.
* Central nervous system (CNS) seizure agents. CNS seizure agents inhibit cellular signaling by acting as receptor antagonists. They result in the inhibition of biological responses. Examples of CNS seizure agents are organochlorine pesticides.
* Respiratory blockers. These are toxicants that affect respiration by interfering with the electron transport chain in the mitochondria. Examples of respiratory blockers are rotenone and cyanide. | 1 | Biochemistry |
Let be primitive translation vectors (shortly called primitive vectors) of a crystal lattice , where atoms are located at lattice points described by with , , and as any integers. (So indicating each lattice point is an integer linear combination of the primitive vectors.)
Let be the wave vector of an incoming (incident) beam or wave toward the crystal lattice , and let be the wave vector of an outgoing (diffracted) beam or wave from . Then the vector , called the scattering vector or transferred wave vector, measures the difference between the incoming and outgoing wave vectors.
The three conditions that the scattering vector must satisfy, called the Laue equations, are the following:
where numbers are integer numbers. Each choice of integers , called Miller indices, determines a scattering vector . Hence there are infinitely many scattering vectors that satisfy the Laue equations as there are infinitely many choices of Miller indices . Allowed scattering vectors form a lattice , called the reciprocal lattice of the crystal lattice , as each indicates a point of . (This is the meaning of the Laue equations as shown below.) This condition allows a single incident beam to be diffracted in infinitely many directions. However, the beams corresponding to high Miller indices are very weak and can't be observed. These equations are enough to find a basis of the reciprocal lattice (since each observed indicates a point of the reciprocal lattice of the crystal under the measurement), from which the crystal lattice can be determined. This is the principle of x-ray crystallography. | 3 | Analytical Chemistry |
In geometry and crystallography, the Laves graph is an infinite and highly symmetric system of points and line segments in three-dimensional Euclidean space, forming a periodic graph. Three equal-length segments meet at 120° angles at each point, and all cycles use ten or more segments. It is the shortest possible triply periodic graph, relative to the volume of its fundamental domain. One arrangement of the Laves graph uses one out of every eight of the points in the integer lattice as its points, and connects all pairs of these points that are nearest neighbors, at distance . It can also be defined, divorced from its geometry, as an abstract undirected graph, a covering graph of the complete graph on four vertices.
named this graph after Fritz Laves, who first wrote about it as a crystal structure in 1932. It has also been called the K crystal, (10,3)-a network, diamond twin, triamond, and the srs net. The regions of space nearest each vertex of the graph are congruent 17-sided polyhedra that tile space. Its edges lie on diagonals of the regular skew polyhedron, a surface with six squares meeting at each integer point of space.
Several crystalline chemicals have known or predicted structures in the form of the Laves graph. Thickening the edges of the Laves graph to cylinders produces a related minimal surface, the gyroid, which appears physically in certain soap film structures and in the wings of butterflies. | 3 | Analytical Chemistry |
In thermodynamics, the saturation vapor curve is the curve separating the two-phase state and the superheated vapor state in the T–s diagram (temperature–entropy diagram).
The saturated liquid curve is the curve separating the subcooled liquid state and the two-phase state in the T–s diagram.
When used in a power cycle, the fluid expansion depends strongly on the nature of this saturation curve:
*A "wet" fluid shows a negative saturation vapor curve. If overheating before the expansion is limited, a two-phase state is obtained at the end of the expansion.
*An "isentropic" fluid shows a vertical saturation vapor curve. It remains very close to the saturated vapor state after an hypothetical isentropic expansion.
*A "dry" fluid shows a positive saturation vapor curve. It is in dry vapor state at the end of the expansion, and strongly overheated. | 7 | Physical Chemistry |
The rpoB gene encodes the β subunit of bacterial RNA polymerase and the homologous plastid-encoded RNA polymerase (PEP). It codes for 1342 amino acids in E. coli, making it the second-largest polypeptide in the bacterial cell. It is targeted by the rifamycin family of antibacterials, such as rifampin. Mutations in rpoB that confer resistance to rifamycins do so by altering the protein's drug-binding residues, thereby reducing affinity for these antibiotics.
Some bacteria contain multiple copies of the 16S rRNA gene, which is commonly used as the molecular marker to study phylogeny. In these cases, the single-copy rpoB gene can be used to study microbial diversity.
An inhibitor of transcription in bacteria, tagetitoxin, also inhibits PEP, showing that the complex found in plants is very similar to the homologous enzyme in bacteria. | 1 | Biochemistry |
Cefroxadine can be prepared by several routes, including one in which the enol is methylated with diazomethane as a key step. A rather more involved route starts with comparatively readily available phenoxymethylpenicillin sulfoxide benzhydryl ester (1).
This undergoes fragmentation when treated with benzothiazole-2-thiol to give 2. Ozonolysis (reductive work-up) cleaves the olefinic linkage and the unsymmetrical disulfide moiety is converted to a tosyl thioester (3). The enol moiety is methylated with diazomethane, the six-membered ring is closed by reaction with 1,5-diazabicyclo[5.4.0]undec-5-ene (DBU), and the ester protection is removed with trifluoroacetic acid to give 4. The amide side chain is removed by the usual PCl/dimethylaniline sequence followed by reamidation with the appropriate acid chloride to give cefroxadine (5). | 4 | Stereochemistry |
When comparing relative stability, 6- and 7-atom interactions can be used to approximate differences in enthalpy between conformations. Each 6-atom interaction is worth and each 7-atom interaction is worth . | 4 | Stereochemistry |
This system is also used by most bacteria for chromosome segregation.
Type I partition systems are composed of an ATPase which contains Walker motifs and a CBP which is structurally distinct in type Ia and Ib. ATPases and CBP from type Ia are longer than the ones from type Ib, but both CBPs contain an arginine finger in their N-terminal part.
ParA proteins from different plasmids and bacterial species show 25 to 30% of sequence identity to the protein ParA of the plasmid P1.
The partition of type I system uses a "diffusion-ratchet" mechanism. This mechanism works as follows:
# Dimers of ParA-ATP dynamically bind to nucleoid DNA
# ParA in its ATP-bound state interacts with ParB bound to parS
# ParB bound to parS stimulates the release of ParA from the nucleoid region surrounding the plasmid
# The plasmid then chases the resulting ParA gradient on the perimeter of the ParA depleted region of the nucleoid
# The ParA that was released from the nucleoid behind the plasmid's movement redistributes to other regions of the nucleoid after a delay
# After plasmid replication, the sister copies segregate to opposite cell halves as they chase ParA on the nucleoid in opposite directions
There are likely to be differences in the details of type I mechanisms.
Type 1 partition has been mathematically modelled with variations in the mechanism described above. | 1 | Biochemistry |
Methanogenesis in microbes is a form of anaerobic respiration. Methanogens do not use oxygen to respire; in fact, oxygen inhibits the growth of methanogens. The terminal electron acceptor in methanogenesis is not oxygen, but carbon. The two best described pathways involve the use of acetic acid or inorganic carbon dioxide as terminal electron acceptors:
:CO + 4 H → CH + 2 HO
:CHCOOH → CH + CO
During anaerobic respiration of carbohydrates, H and acetate are formed in a ratio of 2:1 or lower, so H contributes only to methanogenesis, with acetate contributing the greater proportion. In some circumstances, for instance in the rumen, where acetate is largely absorbed into the bloodstream of the host, the contribution of H to methanogenesis is greater.
However, depending on pH and temperature, methanogenesis has been shown to use carbon from other small organic compounds, such as formic acid (formate), methanol, methylamines, tetramethylammonium, dimethyl sulfide, and methanethiol. The catabolism of the methyl compounds is mediated by methyl transferases to give methyl coenzyme M. | 1 | Biochemistry |
After successful formation of a stable nucleus, a growth stage ensues in which free particles (atoms or molecules) adsorb onto the nucleus and propagate its crystalline structure outwards from the nucleating site. This process is significantly faster than nucleation. The reason for such rapid growth is that real crystals contain dislocations and other defects, which act as a catalyst for the addition of particles to the existing crystalline structure. By contrast, perfect crystals (lacking defects) would grow exceedingly slowly. On the other hand, impurities can act as crystal growth inhibitors and can also modify crystal habit. | 3 | Analytical Chemistry |
This phenomenon describes damage to the metal (nearly always iron or steel) at low temperature by diffusible hydrogen.
Hydrogen can embrittle a number of metals and steel is one of them. It tends to happen to harder and higher tensile steels. Hydrogen cam also embrittle aluminum at high temperatures.). Titanium metal and alloys are also susceptible. | 8 | Metallurgy |
* Post-doctorate fellowship senior scholar Fulbright Fellowship (1985), where he was a visiting Fulbright fellow.
* Post-doctorate fellow Association of Commonwealth Universities (1984-1985), where he was a visiting Commonwealth fellow | 1 | Biochemistry |
It is a suitable discharge option for cakes that are thin and have the tendency to stick with one another. Filter cakes on the drum and discharged roll are pressed against one another to ensure that the thin filter cake is peeled or pulled from the drum. Removal of solids from the discharge roll is done via a knife blade. Roll discharged is used if the desired separation requires high filtration rate, if high solid content slurry is used or if the slurry is easy to filter to produce cake formation or if the discharged solid is sticky or mud-like cake. | 3 | Analytical Chemistry |
Cryobiology is a bimonthly peer-reviewed scientific journal covering cryobiology. It was established in 1964 and is published by Elsevier on behalf of the Society for Cryobiology, of which it is the official journal. The editor-in-chief is D.M. Rawson (University of Bedfordshire). According to the Journal Citation Reports, the journal has a 2017 impact factor of 2.050. | 1 | Biochemistry |
The low-flow-rate method is based on the fact that the extraction efficiency is dependent on the flow-rate. At high flow-rates, the amount of drug diffusing from the sampling site into the dialysate per unit time is smaller (low extraction efficiency) than at lower flow-rates (high extraction efficiency). At a flow-rate of zero, a total equilibrium between these two sites is established (C = C). This concept is applied for the (low-)flow-rate method, where the probe is perfused with blank perfusate at different flow-rates. Concentration at the sampling site can be determined by plotting the extraction ratios against the corresponding flow-rates and extrapolating to zero-flow. The low-flow-rate method is limited by the fact that calibration times may be rather long before a sufficient sample volume has been collected. | 1 | Biochemistry |
Methods for performing protein sequencing
include:
*Edman degradation
*Peptide mass fingerprinting
*Mass spectrometry
*Protease digests
If the gene encoding the protein is known, it is currently much easier to sequence the DNA and infer the protein sequence. Determining part of a protein's amino-acid sequence (often one end) by one of the above methods may be sufficient to identify a clone carrying this gene. | 1 | Biochemistry |
The SECIS element is found in a wide variety of organisms from all three domains of life (including their viruses). | 1 | Biochemistry |
Gestonorone caproate, also known as gestronol hexanoate or norhydroxyprogesterone caproate and sold under the brand names Depostat and Primostat, is a progestin medication which is used in the treatment of enlarged prostate and cancer of the endometrium. It is given by injection into muscle typically once a week.
Side effects of gestonorone caproate include worsened glucose tolerance, decreased libido in men, and injection site reactions. Gestonorone caproate is a progestin, or a synthetic progestogen, and hence is an agonist of the progesterone receptor, the biological target of progestogens like progesterone. It has no other important hormonal activity.
Gestonorone caproate was discovered in 1960 and was introduced for medical use by 1973. It has been used widely throughout Europe, including in the United Kingdom, and has also been marketed in certain other countries such as Japan, China, and Mexico. However, it has since mostly been discontinued, and it remains available today only in a handful of countries, including the Czech Republic, Japan, Mexico, and Russia. | 4 | Stereochemistry |
If the flow is steady and conservative, the mean residence time equals the ratio between the amount of fluid contained in the control volume and the flow rate through it:
This ratio is commonly known as the turnover time or flushing time. When applied to liquids, it is also known as the hydraulic retention time (HRT), hydraulic residence time or hydraulic detention time. In the field of chemical engineering this is also known as space time.
The residence time of a specific compound in a mixture equals the turnover time (that of the compound, as well as that of the mixture) only if the compound does not take part in any chemical reaction (otherwise its flow is not conservative) and its concentration is uniform.
Although the equivalence between the residence time and the ratio does not hold if the flow is not stationary or it is not conservative, it does hold on average if the flow is steady and conservative on average, and not necessarily at any instant. Under such conditions, which are common in queueing theory and supply chain management, the relation is known as Little's Law. | 9 | Geochemistry |
With such table top laboratory equipment it is now also possible to produce films, fibers and test samples (rods, rings, tablets) from mixtures as small as 5 ml in less than 10 min. By the small footprint less lab space is needed than for a parallel twin screw extruder. Because of these benefits screening of optimum formulations in R&D is really feasible and affordable.
In pharmaceutical and biomedical R&D, where sample costs are a key issue, an easy to clean, 2 to 5 ml GMP compliant pharma micro-extruder was developed. This equipment is used for testing the improvement of bioavailability of poorly soluble drugs or realizing sustained release of dispersed or dissolved APIs. As pharmaceutical formulations are usually difficult to feed because of fluffy, static powders, this pharma micro-extruder has special options to easily fill and easily clean, which further speeds up the R&D process. | 7 | Physical Chemistry |
Urbanization increases surface runoff by creating more impervious surfaces such as pavement and buildings that do not allow percolation of the water down through the soil to the aquifer. It is instead forced directly into streams or storm water runoff drains, where erosion and siltation can be major problems, even when flooding is not. Increased runoff reduces groundwater recharge, thus lowering the water table and making droughts worse, especially for agricultural farmers and others who depend on the water wells.
When anthropogenic contaminants are dissolved or suspended in runoff, the human impact is expanded to create water pollution. This pollutant load can reach various receiving waters such as streams, rivers, lakes, estuaries and oceans with resultant water chemistry changes to these water systems and their related ecosystems.
As humans continue to alter the climate through the addition of greenhouse gases to the atmosphere, precipitation patterns are expected to change as the atmospheric capacity for water vapor increases. This will have direct consequences on runoff amounts. | 2 | Environmental Chemistry |
Most mononuclear carbonyl complexes are colorless or pale yellow volatile liquids or solids that are flammable and toxic. Vanadium hexacarbonyl, a uniquely stable 17-electron metal carbonyl, is a blue-black solid. Dimetallic and polymetallic carbonyls tend to be more deeply colored. Triiron dodecacarbonyl (Fe(CO)) forms deep green crystals. The crystalline metal carbonyls often are sublimable in vacuum, although this process is often accompanied by degradation. Metal carbonyls are soluble in nonpolar and polar organic solvents such as benzene, diethyl ether, acetone, glacial acetic acid, and carbon tetrachloride. Some salts of cationic and anionic metal carbonyls are soluble in water or lower alcohols. | 0 | Organic Chemistry |
The most convenient way of expressing the composition of a generic mixture is by using the mole fractions (written in the gas phase) of the different components (or chemical species: atoms or molecules) present in the system, where
: with , the number of moles of the component i, and , the total number of moles of all the different components present in the mixture.
The standard state of each component in the mixture is taken to be the pure substance, i.e. the pure substance has an activity of one. When activity coefficients are used, they are usually defined in terms of Raoult's law,
where is the Raoults law activity coefficient: an activity coefficient of one indicates ideal behaviour according to Raoults law. | 7 | Physical Chemistry |
With aqueous pK values of around 16–19, they are, in general, slightly weaker acids than water. With strong bases such as sodium hydride or sodium they form salts called alkoxides, with the general formula (where R is an alkyl and M is a metal).
The acidity of alcohols is strongly affected by solvation. In the gas phase, alcohols are more acidic than in water. In DMSO, alcohols (and water) have a pK of around 29–32. As a consequence, alkoxides (and hydroxide) are powerful bases and nucleophiles (e.g., for the Williamson ether synthesis) in this solvent. In particular, or in DMSO can be used to generate significant equilibrium concentrations of acetylide ions through the deprotonation of alkynes (see Favorskii reaction). | 0 | Organic Chemistry |
Defects due to both external and intrinsic factors may appear. External factors include the cleanliness of the substrate, method of preparation, and purity of the adsorbates. SAMs intrinsically form defects due to the thermodynamics of formation, e.g. thiol SAMs on gold typically exhibit etch pits (monatomic vacancy islands) likely due to extraction of adatoms from the substrate and formation of adatom-adsorbate moieties. Recently, a new type of fluorosurfactants have found that can form nearly perfect monolayer on gold substrate due to the increase of mobility of gold surface atoms. | 6 | Supramolecular Chemistry |
Water is the chemical substance with chemical formula ; one molecule of water has two hydrogen atoms covalently bonded to a single oxygen atom. Water is a tasteless, odorless liquid at ambient temperature and pressure. Liquid water has weak absorption bands at wavelengths of around 750 nm which cause it to appear to have a blue color. This can easily be observed in a water-filled bath or wash-basin whose lining is white. Large ice crystals, as in glaciers, also appear blue.
Under standard conditions, water is primarily a liquid, unlike other analogous hydrides of the oxygen family, which are generally gaseous. This unique property of water is due to hydrogen bonding. The molecules of water are constantly moving concerning each other, and the hydrogen bonds are continually breaking and reforming at timescales faster than 200 femtoseconds (2 × 10 seconds). However, these bonds are strong enough to create many of the peculiar properties of water, some of which make it integral to life. | 2 | Environmental Chemistry |
Iron is usually found as iron ore on Earth, except for one deposit of native iron in Greenland, which was used by the Inuit. Native copper, however, was found worldwide, along with silver, gold, and platinum, which were also used to make tools, jewelry, and other objects since Neolithic times. Copper was the hardest of these metals, and the most widely distributed. It became one of the most important metals to the ancients. Around 10,000 years ago in the highlands of Anatolia (Turkey), humans learned to smelt metals such as copper and tin from ore. Around 2500 BC, people began alloying the two metals to form bronze, which was much harder than its ingredients. Tin was rare, however, being found mostly in Great Britain. In the Middle East, people began alloying copper with zinc to form brass. Ancient civilizations took into account the mixture and the various properties it produced, such as hardness, toughness and melting point, under various conditions of temperature and work hardening, developing much of the information contained in modern alloy phase diagrams. For example, arrowheads from the Chinese Qin dynasty (around 200 BC) were often constructed with a hard bronze-head, but a softer bronze-tang, combining the alloys to prevent both dulling and breaking during use. | 8 | Metallurgy |
Agricultures role in developed countries has drastically changed in the last century due to many factors, including refrigeration. Statistics from the 2007 census gives information on the large concentration of agricultural sales coming from a small portion of the existing farms in the United States today. This is a partial result of the market created for the frozen meat trade by the first successful shipment of frozen sheep carcasses coming from New Zealand in the 1880s. As the market continued to grow, regulations on food processing and quality began to be enforced. Eventually, electricity was introduced into rural homes in the United States, which allowed refrigeration technology to continue to expand on the farm, increasing output per person. Today, refrigerations use on the farm reduces humidity levels, avoids spoiling due to bacterial growth, and assists in preservation. | 7 | Physical Chemistry |
Small molecules, proteins, and nucleic acids have been found to stimulate levels of frameshifting. For example, the mechanism of a negative feedback loop in the polyamine synthesis pathway is based on polyamine levels stimulating an increase in +1 frameshifts, which results in production of an inhibitory enzyme. Certain proteins which are needed for codon recognition or which bind directly to the mRNA sequence have also been shown to modulate frameshifting levels. MicroRNA (miRNA) molecules may hybridize to a RNA secondary structure and affect its strength. | 1 | Biochemistry |
Toxins are often distinguished from other chemical agents strictly based on their biological origin.
Less strict understandings embrace naturally occurring inorganic toxins, such as arsenic. Other understandings embrace synthetic analogs of naturally occurring organic poisons as toxins, and may or may not embrace naturally occurring inorganic poisons. It is important to confirm usage if a common understanding is critical.
Toxins are a subset of toxicants. The term toxicant is preferred when the poison is man-made and therefore artificial. The human and scientific genetic assembly of a natural-based toxin should be considered a toxin as it is identical to its natural counterpart. The debate is one of linguistic semantics.
The word toxin does not specify method of delivery (as opposed to venom, a toxin delivered via a bite, sting, etc.). Poison is a related but broader term that encompasses both toxins and toxicants; poisons may enter the body through any means - typically inhalation, ingestion, or skin absorption. Toxin, toxicant, and poison are often used interchangeably despite these subtle differences in definition. The term toxungen has also been proposed to refer to toxins that are delivered onto the body surface of another organism without an accompanying wound.
A rather informal terminology of individual toxins relates them to the anatomical location where their effects are most notable:
* Genitotoxin, damages the urinary organs or the reproductive organs
* Hemotoxin, causes destruction of red blood cells (hemolysis)
* Phototoxin, causes dangerous photosensitivity
* Hepatotoxins affect the liver
* Neurotoxins affect the nervous system
On a broader scale, toxins may be classified as either exotoxins, excreted by an organism, or endotoxins, which are released mainly when bacteria are lysed. | 1 | Biochemistry |
These dosage forms are commonly used to deliver drugs to the eye and nasal cavity. They often include mucoadhesive polymers to improve retention on dynamic mucosal surfaces. Some advanced eye drop formulations may also turn from a liquid to a gel (so called in situ gelling systems) upon drug administration. For example, gel-forming solutions containing Pluronics could be used to improve the efficiency of eye drops and provide better retention on ocular surfaces. | 1 | Biochemistry |
In chemistry, bond stretch isomerism is a concept of isomerism based on variations of bond length. The concept was proposed in the 1970s but was refuted in the 1990s.
The phenomenon was first invoked to explain the observation of blue and green isomers of , where is dimethylphenylphosphine. These isomers were shown, purportedly, by X-ray crystallography to differ with respect to the length of the Mo-O bond, which differed by 0.2 Å. Subsequent work showed that the supposed green bond stretch isomer consisted of blue contaminated with a small amount of yellow . The nearly isomorphous replacement of Mo-O unit with small amounts of Mo-Cl unit results in artifactually long Mo-O distance in the green sample. In essence the deception arises because the crystallographic disorder was not modeled appropriately. Several such examples were uncovered. | 4 | Stereochemistry |
In experiments in animals favipiravir has shown activity against West Nile virus, yellow fever virus, foot-and-mouth disease virus as well as other flaviviruses, arenaviruses, bunyaviruses and alphaviruses. Activity against enteroviruses and Rift Valley fever virus has also been demonstrated. Favipiravir has showed limited efficacy against Zika virus in animal studies, but was less effective than other antivirals such as MK-608. The agent has also shown some efficacy against rabies, and has been used experimentally in some humans infected with the virus. | 4 | Stereochemistry |
On heating a haloalkane and concentrated ammonia in a sealed tube with ethanol, a series of amines are formed along with their salts. The tertiary amine is usually the major product.
This is known as Hoffmann's ammonolysis. | 1 | Biochemistry |
*Alkylation
*Methoxy
*Titanium–zinc methylenation
*Petasis reagent
*Nysted reagent
*Wittig reaction
*Tebbe's reagent | 0 | Organic Chemistry |
Synthesis, properties, and reactivity of the compound were first described in 2006 by Antonio Togni and his coworkers at ETH Zurich. The article also contains information on Togni reagent I (1,3-dihydro-3,3-dimethyl-1-(trifluoromethyl)-1,2-benziodoxole). | 0 | Organic Chemistry |
Alogliptin, sold under the brand names Nesina and Vipidia, is an oral anti-diabetic drug in the DPP-4 inhibitor (gliptin) class. Like other members of the gliptin class, it causes little or no weight gain, exhibits relatively little risk of hypoglycemia, and has relatively modest glucose-lowering activity. Alogliptin and other gliptins are commonly used in combination with metformin in people whose diabetes cannot adequately be controlled with metformin alone.
In April 2016, the U.S. Food and Drug Administration (FDA) added a warning about increased risk of heart failure. It was developed by Syrrx, a company which was acquired by Takeda Pharmaceutical Company in 2005. In 2020, it was the 295th most commonly prescribed medication in the United States, with more than 1million prescriptions. | 4 | Stereochemistry |
Fermentation is the metabolism of organic compounds in the absence of air. It involves substrate-level phosphorylation in the absence of a respiratory electron transport chain. The equation for the reaction of glucose to form lactic acid is:
: + 2 ADP + 2 P → 2 + 2 ATP + 2
Anaerobic respiration is respiration in the absence of . Prokaryotes can utilize a variety of electron acceptors. These include nitrate, sulfate, and carbon dioxide. | 1 | Biochemistry |
* Chaikin P. M. and Lubensky T. C. Principles of Condensed Matter Physics (Cambridge University Press, Cambridge) 1995, sect.9.
* Feynman R. P. Progress in Low Temperature Physics Vol.1, edited by C. Gorter (North Holland, Amsterdam) 1955. | 7 | Physical Chemistry |
In organic chemistry, sulfamoyl fluoride is an organic compound having the chemical formula F−SO−N(−R)−R. Its derivatives are called sulfamoyl fluorides.
Examples of sulfamoyl fluorides include:
Sulfamoyl fluorides are contrasted with the sulfonimidoyl fluorides with structure R-S(O)(F)=N-R. | 0 | Organic Chemistry |
A linear biochemical pathway is a chain of enzyme-catalyzed reaction steps where the product of one reaction becomes the substrate for the next reaction. The molecules progress through the pathway sequentially from the starting substrate to the final product. Each step in the pathway is usually facilitated by a different specific enzyme that catalyzes the chemical transformation. An example includes DNA replication, which connects the starting substrate and the end product in a straightforward sequence.
Biological cells consume nutrients to sustain life. These nutrients are broken down to smaller molecules. Some of the molecules are used in the cells for various biological functions, and others are reassembled into more complex structures required for life. The breakdown and reassembly of nutrients is called metabolism. An individual cell will contain thousands of different kinds of small molecules, such as sugars, lipids, and amino acids. The interconversion of these molecules is carried out by catalysts called enzymes. For example, E. coli contains 2,338 metabolic enzymes. These enzymes form a complex web of reactions forming pathways by which nutrients are converted.
The figure below shows a four step pathway, with intermediates, and . To sustain a steady-state, the boundary species and are fixed. Each step is catalyzed by an enzyme, .
Linear pathways follow a step-by-step sequence, where each enzymatic reaction results in the transformation of a substrate into an intermediate product. This intermediate is processed by subsequent enzymes until the final product is synthesized.
A linear pathway can be studied in various ways. Multiple computer simulations can be run to try to understand the pathway's behavior. Another way to understand the properties of a linear pathway is to take a more analytical approach. Analytical solutions can be derived for the steady-state if simple mass-action kinetics are assumed. Analytical solutions for the steady-state when assuming Michaelis-Menten kinetics can be obtained but are quite often avoided. Instead, such models are linearized. The three approaches that are usually used are therefore:
* Computer simulation
* Analytical solutions using a linear mathematical model
* Linearization of a non-linear model | 1 | Biochemistry |
Specific uses for phenoxymethylpenicillin include:
* Infections caused by Streptococcus pyogenes
** Tonsillitis
** Pharyngitis
** Skin infections
* Anthrax (mild uncomplicated infections)
* Lyme disease (early stage in pregnant women or young children)
* Rheumatic fever (primary and secondary prophylaxis)
* Streptococcal skin infections
* Spleen disorders (pneumococcal infection prophylaxis)
* Initial treatment for dental abscesses
* Moderate-to-severe gingivitis (with metronidazole)
* Avulsion injuries of teeth (as an alternative to tetracycline)
* Blood infection prophylaxis in children with sickle cell disease.
Penicillin V is sometimes used in the treatment of odontogenic infections.
It is less active than benzylpenicillin (penicillin G) against Gram-negative bacteria. Phenoxymethylpenicillin has a range of antimicrobial activity against Gram-positive bacteria that is similar to that of benzylpenicillin and a similar mode of action, but it is substantially less active than benzylpenicillin against Gram-negative bacteria.
Phenoxymethylpenicillin is more acid-stable than benzylpenicillin, which allows it to be given orally.
Phenoxymethylpenicillin is usually used only for the treatment of mild to moderate infections, and not for severe or deep-seated infections since absorption can be unpredictable. Except for the treatment or prevention of infection with Streptococcus pyogenes (which is uniformly sensitive to penicillin), therapy should be guided by bacteriological studies (including sensitivity tests) and by clinical response. People treated initially with parenteral benzylpenicillin may continue treatment with phenoxymethylpenicillin by mouth once a satisfactory response has been obtained.
It is not active against beta-lactamase-producing bacteria, which include many strains of Staphylococci. | 4 | Stereochemistry |
2,4-Dinitrophenylhydrazine (2,4-DNPH or DNPH) is the organic compound CH(NO)NHNH. DNPH is a red to orange solid. It is a substituted hydrazine. The solid is relatively sensitive to shock and friction. For this reason DNPH is usually handled as a wet powder. DNPH is a precursor to the drug Sivifene. | 0 | Organic Chemistry |
Norvaline is a non-proteinogenic unbranched-chain amino acid. It has previously been reported to be a natural component of an antifungal peptide of Bacillus subtilis. Norvaline and other modified unbranched chain amino acids have received attention because they appear to be incorporated in some recombinant proteins found in E. coli. Its biosynthesis has been examined. The incorporation of Nva into peptides reflects the imperfect selectivity of the associated aminoacyl-tRNA synthetase. In Miller–Urey experiments probing prebiotic synthesis of amino acids, norvaline, but also norleucine, are produced. | 1 | Biochemistry |
Historically it was assumed that the nucleation rate of new recrystallized grains would be determined by the thermal fluctuation model successfully used for solidification and precipitation phenomena. In this theory it is assumed that as a result of the natural movement of atoms (which increases with temperature) small nuclei would spontaneously arise in the matrix. The formation of these nuclei would be associated with an energy requirement due to the formation of a new interface and an energy liberation due to the formation of a new volume of lower energy material. If the nuclei were larger than some critical radius then it would be thermodynamically stable and could start to grow.
The main problem with this theory is that the stored energy due to dislocations is very low (0.1–1 J m) while the energy of a grain boundary is quite high (~0.5 J m). Calculations based on these values found that the observed nucleation rate was greater than the calculated one by some impossibly large factor (~10).
As a result, the alternate theory proposed by Cahn in 1949 is now universally accepted. The recrystallized grains do not nucleate in the classical fashion but rather grow from pre-existing sub-grains and cells. The incubation time is then a period of recovery where sub-grains with low-angle boundaries (<1–2°) begin to accumulate dislocations and become increasingly misoriented with respect to their neighbors. The increase in misorientation increases the mobility of the boundary and so the rate of growth of the sub-grain increases. If one sub-grain in a local area happens to have an advantage over its neighbors (such as locally high dislocation densities, a greater size or favorable orientation) then this sub-grain will be able to grow more rapidly than its competitors. As it grows its boundary becomes increasingly misoriented with respect to the surrounding material until it can be recognized as an entirely new strain-free grain. | 8 | Metallurgy |
Another example of the apparent molar volume of the second component is less than its molar volume as a pure substance is the case of ethanol in water. For example, at 20 mass percents ethanol, the solution has a volume of 1.0326 liters per kg at 20 °C, while pure water is 1.0018 L/kg (1.0018 cc/g). The apparent volume of the added ethanol is 1.0326 L – 0.8 kg x 1.0018 L/kg = 0.2317 L. The number of moles of ethanol is 0.2 kg / (0.04607 kg/mol) = 4.341 mol, so that the apparent molar volume is 0.2317 L / 4.341 mol = 0.0532 L / mol = 53.2 cc/mole (1.16 cc/g). However pure ethanol has a molar volume at this temperature of 58.4 cc/mole (1.27 cc/g).
If the solution were ideal, its volume would be the sum of the unmixed components. The volume of 0.2 kg pure ethanol is 0.2 kg x 1.27 L/kg = 0.254 L, and the volume of 0.8 kg pure water is 0.8 kg x 1.0018 L/kg = 0.80144 L, so the ideal solution volume would be 0.254 L + 0.80144 L = 1.055 L. The nonideality of the solution is reflected by a slight decrease (roughly 2.2%, 1.0326 rather than 1.055 L/kg) in the volume of the combined system upon mixing. As the percent ethanol goes up toward 100%, the apparent molar volume rises to the molar volume of pure ethanol. | 7 | Physical Chemistry |
The Eastern Analytical Symposium (EAS) and Exposition is an American organization that sponsors a Symposium and Exposition generally held in Princeton, New Jersey, every November. The Symposium is attended by over 2000 scientists and typically contains several hundred papers by the world's leading authorities on analytical chemistry.
The associated exposition contains information on technology and information from companies that provide instrumentation and services for the community of analytical scientists. In addition, the EAS provides an ongoing education program that includes technical short courses and professional development workshops for laboratory scientists, as well as general-interest sessions directed at the public, especially students and their chemistry teachers. | 7 | Physical Chemistry |
Lipomannan is a mycobacterium immune agonist. In addition, it is a major constituent of the mycobacterium cell wall. This glycoconjugate is a virulence factor that plays a key role in the human immune system via interaction with various immune cells. It is also considered to be a precursor of lipoarabinomannans.
It is a trigger for TLR 2.
It consists of an α-linked mannan, which consists of 50–70 residues, with some branches points linked glycosidically to a diglyceride of which the fatty acids are similar to those of the whole cell lipid. In addition, succinic acid residues are present as O-acyl substituents on about one in four of the mannose residues, the terminal carboxyl group of the succinic acid providing the whole polymer with a considerable number of acidic functions.
Lipomannan has functional components that resemble lipoteichoic acids; a lipophilic region and a hydrophilic portion with frequent acid groups.
Lipomannan is a phosphorylated polysaccharide associated with the cell envelope and is considered to be the multimannosylated form of PIM which is primarily located in the plasma membrane. Structurally, LM is composed of two segments: a PI anchor to which is attached an α-D-mannan domain; both play key roles in inducing cytokine production by phagocytic cells. Mannose core consists of a linear α(1-6)-linked mannan backbone extending from the c-6 of the myo-inositol; the mannan chains is further substituted by α-(1-2) man-p side branches. | 1 | Biochemistry |
In 1969, two separate labs simultaneously identified antigens in the sera of SLE and SS patients. Clark et al. referred to the antigen as Ro – named after the patient from which the antibodies were extracted, while Alspaugh & Tanand used the term SSA. It was later found that the labs described the same antigen, hence the compound term for the antibody, Anti-SSA/Ro, Anti-Ro/SSA. | 1 | Biochemistry |
Heat can flow into or out of a closed system by way of thermal conduction or of thermal radiation to or from a thermal reservoir, and when this process is effecting net transfer of heat, the system is not in thermal equilibrium. While the transfer of energy as heat continues, the system's temperature can be changing. | 7 | Physical Chemistry |
Detailed sample preparation depends on the type of material. Pure standards are most likely to be prepared by chemical synthesis and purification and characterized by determination of remaining impurities. This is often done by commercial producers. Natural matrix CRMs (often shortened to matrix CRMs) contain an analyte or analytes in a natural sample (for, example, lead in fish tissue). These are typically produced by homogenization of a naturally occurring material followed by measurement of each analyte. Due to the difficulty in production and value assignment, these are usually produced by national or transnational metrology institutes like NIST (USA), BAM (Germany), KRISS (Korea) and EC JRC ( European Commission Joint Research Centre).
For natural materials, homogenization is often critical; natural materials are rarely homogeneous on the scale of grams so production of a solid natural matrix reference material typically involves processing to a fine powder or paste. Homogenization can have adverse effects, for example on proteins, so producers must take care not to over-process materials. Stability of a certified reference material is also important, so a range of strategies may be used to prepare a reference material that is more stable than the natural material it is prepared from. For example, stabilizing agents such as antioxidants or antimicrobial agents may be added to prevent degradation, liquids containing certified concentrations of trace metals may have pH adjusted to keep metals in solution, and clinical reference materials may be freeze-dried for long term storage if they can be reconstituted successfully. | 3 | Analytical Chemistry |
Norşuntepe was occupied from the Chalcolithic to the Iron Age. The excavators have recognized 40 different occupation levels ranging in date from the fifth millennium BC to ca. 600 BC. Its occupation levels overlap to a large degree with those excavated at nearby Arslantepe. | 8 | Metallurgy |
The MNR2 gene encodes a protein closely related to the Alr proteins, but includes conserved features that define a distinct subgroup of CorA proteins in fungal genomes, suggesting a distinct role in Mg homeostasis. Like an alr1 mutant, growth of an mnr2 mutant was sensitive to Mg-deficient conditions, but the mnr2 mutant was observed to accumulate more Mg than a wild-type strain under these conditions. These phenotypes suggested that Mnr2 may regulate Mg storage within an intracellular compartment. Consistent with this interpretation, the Mnr2 protein was localized to the membrane of the vacuole, an internal compartment implicated in the storage of excess mineral nutrients by yeast. A direct role of Mnr2 in Mg transport was suggested by the observation that increased Mnr2 expression, which redirected some Mnr2 protein to the cell surface, also suppressed the Mg-requirement of an alr1 alr2 double mutant strain. The mnr2 mutation also altered accumulation of other divalent cations, suggesting this mutation may increase Alr gene expression or protein activity. Recent work supported this model, by showing that Alr1 activity was increased in an mnr2 mutant strain, and that the mutation was associated with induction of Alr1 activity at a higher external Mg concentration than was observed for an Mnr2 wild-type strain. These effects were observed without any change in Alr1 protein accumulation, again indicating that Alr1 activity may be regulated directly by the Mg concentration within the cell. | 1 | Biochemistry |
An equation of state (for gases) is a mathematical model used to roughly describe or predict the state properties of a gas. At present, there is no single equation of state that accurately predicts the properties of all gases under all conditions. Therefore, a number of much more accurate equations of state have been developed for gases in specific temperature and pressure ranges. The "gas models" that are most widely discussed are "perfect gas", "ideal gas" and "real gas". Each of these models has its own set of assumptions to facilitate the analysis of a given thermodynamic system. Each successive model expands the temperature range of coverage to which it applies. | 7 | Physical Chemistry |
The reactivity of chloroformates and acyl chlorides are similar. Representative reactions are:
* Reaction with amines to form carbamates:
:ROC(O)Cl + HNR → ROC(O)-N(H)R + HCl
* Reaction with alcohols to form carbonate esters:
:ROC(O)Cl + HOR → ROC(O)-OR + HCl
* Reaction with carboxylic acids to form mixed anhydrides:
Typically these reactions would be conducted in the presence of a base which serves to absorb the HCl.
Alkyl chloroformate esters degrate to give the alkyl chloride, with retention of configuration:
The reaction is proposed to proceed via a substitution nucleophilic internal mechanism. | 0 | Organic Chemistry |
Angus Lamond, a Wellcome Principal Research Fellow, studies the composition and function of organelles and multiprotein complexes found within the nucleus. This work is helping to explain how a cell's nucleus is organised, an area that has particular importance to human diseases such as inherited genetic conditions which can have modified or disrupted organelles.
Jason Swedlow is a Wellcome Trust Senior Research Fellow and investigates how chromosomes are separated during cell division. The driving force behind this process are strands known as microtubules, which pull the chromosomes apart. His work looks at specialised structures known as kinetochores and the mechanisms which monitor the correct attachment of microtubules to the chromosomes.
Tomo Tanaka studies the processes by which eukaryotic cells maintain their genetic integrity. His group use budding yeast to study chromosome duplication and segregation. By understanding the processes that occur during cell division, it is hoped that a better knowledge will be gained of human diseases such as cancer which are often characterised by chromosome instability. | 1 | Biochemistry |
Ambient-temperature molten salts (also known as ionic liquids) are present in the liquid phase at standard conditions for temperature and pressure. Examples of such salts include N-ethylpyridinium bromide and aluminium chloride mix, discovered in 1951, and ethylammonium nitrate discovered by Paul Walden. Other ionic liquids take advantage of asymmetrical quaternary ammonium cations like alkylated imidazolium ions, and large, branched anions like the bistriflimide ion. | 8 | Metallurgy |
The inheritance pattern of genes existing in the cell organelles such as mitochondria which named cytoplasmic inheritance differs from nuclear genes pattern. | 1 | Biochemistry |
Magnetic nanoparticles conjugated to an antibody against an antigen of interest are not always available, but there is a way to circumvent it. Since fluorophore-conjugated antibodies are much more prevalent, it is possible to use magnetic nanoparticles coated with anti-fluorochrome antibodies. They are incubated with the fluorescent-labelled antibodies against the antigen of interest and may thus serve for cell separation with respect to the antigen. | 1 | Biochemistry |
The compilation contains information about the electromagnetic scattering by hexagonal ice crystals, large raindrops, and relevant links and applications. | 7 | Physical Chemistry |
An early ironmaster was John Winter (about 1600–1676) who owned substantial holdings in the Forest of Dean. During the English Civil War he cast cannons for Charles I. Following the Restoration, Winter developed his interest in the iron industry, and experimented with a new type of coking oven. This was a precursor to the later work of Abraham Darby I who successfully used coke to smelt iron. | 8 | Metallurgy |
The isomers which have been cited as examples of metamers in chemical literature consist primarily of ethers; but this could by the same reasoning be extended to thioethers, secondary as well as tertiary amines, esters, secondary as well as tertiary amides, (mixed) acid anhydrides etc.
Ketones however, should be excluded from this class of isomeric relationship, as they primarily are part of position isomerism - as there is no heteroatom present in the functional group, so the two alkyl groups (main chain and side chain) are not disconnected from each other. | 4 | Stereochemistry |
The regions of the rpoB gene which are susceptible to mutations are typically well conserved, indicating they are important for life. This makes it very likely that mutations within these regions have some effect on the overall fitness of the organism. These physiological changes can include a reduced rate of growth, increased sensitivity to increases or decreases in temperature, and alterations to the properties of RNA chain elongation and transcription termination. Such changes are not universal across all bacteria, though. A mutation in codon 450 of M. tuberculosis leads to a minor loss of fitness, while the corresponding mutation in S. aureus results in bacteria barely able to survive.
In Neisseria meningitidis rpoB mutations have been observed to increase expression of enzymes which are involved in metabolizing carbohydrates, as well as enzymes involved in the citric acid cycle and in transcription elongation. At the same time enzymes involved in ATP production, cell division, and lipid metabolism are all downregulated, or expressed at a lower than normal level.
In M. tuberculosis mutations in the rpoB gene can significantly upregulate polyketide synthase, potentially indicating increased production of phthiocerol dimycocerosate, a lipid produced by M. tuberculosis and implicated in virulence of the bacteria. Mutations also impact promoter binding, elongation, termination, and transcription-coupled repair processes in the RNA polymerase itself. Because of this, rpoB mutations were used to study transcription mechanisms before interest shifted to their ability to impart antibiotic resistance. Particular mutations can even result in strains of M. tuberculosis which grow better in the presence of rifampicin than they do when the antibiotic is not present.
In bacteria which are used to produce naturally occurring antibiotics such as erythromycin (Saccharopolyspora erythraea) and vancomycin (Amycolatopsis orientalis) certain rpoB mutations can increase the production of antibiotic by bacteria with those mutations. | 1 | Biochemistry |
Motor proteins are a class of molecular motors that can move along the cytoskeleton of cells. They convert chemical energy into mechanical work by the hydrolysis of ATP. Flagellar rotation, however, is powered by a proton pump. | 6 | Supramolecular Chemistry |
Lanthipeptides are one of the most well-studied families of RiPPs. The family is characterized by the presence of lanthionine (Lan) and 3-methyllanthionine (MeLan) residues in the final natural product. There are four major classes of lanthipeptides, delineated by the enzymes responsible for installation of Lan and MeLan. The dehydratase and cyclase can be two separate proteins or one multifunctional enzyme. Previously, lanthipeptides were known as "lantipeptides" before a consensus was reached in the field.
Lantibiotics are lanthipeptides that have known antimicrobial activity. The founding member of the lanthipeptide family, nisin, is a lantibiotic that has been used to prevent the growth of food-born pathogens for over 40 years. | 1 | Biochemistry |
A slippery sequence is a small section of codon nucleotide sequences (usually UUUAAAC) that controls the rate and chance of ribosomal frameshifting. A slippery sequence causes a faster ribosomal transfer which in turn can cause the reading ribosome to "slip." This allows a tRNA to shift by 1 base (−1) after it has paired with its anticodon, changing the reading frame. A −1 frameshift triggered by such a sequence is a programmed −1 ribosomal frameshift. It is followed by a spacer region, and an RNA secondary structure. Such sequences are common in virus polyproteins.
The frameshift occurs due to wobble pairing. The Gibbs free energy of secondary structures downstream give a hint at how often frameshift happens. Tension on the mRNA molecule also plays a role. A list of slippery sequences found in animal viruses is available from Huang et al.
Slippery sequences that cause a 2-base slip (−2 frameshift) have been constructed out of the HIV UUUUUUA sequence. | 1 | Biochemistry |
Following is the Roman script transliteration of the text:
J. F. Fleet's 1888 translation is as follows:
Due to the tablets installed on the building in 1903 by Pandit Banke Rai, the reading provided by him enjoys wide currency. However, Bankelals reading and interpretation have been challenged by more recent scholarship. The inscription has been revisited by Michael Willis in his book Archaeology of Hindu Ritual, his special concern being the nature of the kings spiritual identity after death. His reading and translation of verse 2 is as follows:
The Sanskrit portion given above can be translated as follows:
Willis concludes: | 8 | Metallurgy |
Dihydroxyacetone phosphate lies in the glycolysis metabolic pathway, and is one of the two products of breakdown of fructose 1,6-bisphosphate, along with glyceraldehyde 3-phosphate. It is rapidly and reversibly isomerised to glyceraldehyde 3-phosphate.
The numbering of the carbon atoms indicates the fate of the carbons according to their position in fructose 6-phosphate. | 5 | Photochemistry |
According to electron diffraction, the and distances in ethylene sulfide are respectively 1.473 and 1.811 Å. The and angles are respectively 66.0 and 48.0°. | 0 | Organic Chemistry |
Antitermination was discovered in bacteriophage infections. A common feature in the control of phage infection is that very few of the phage genes can be transcribed by the bacterial host RNA polymerase. Among these genes, however, are regulators whose products allow the next set of phage genes to be expressed. One of these types of regulator is an antitermination protein. In the absence of the antitermination protein, RNA polymerase terminates at the terminator. When the antitermination protein is present, it continues past the terminator.
The best characterized example of antitermination is provided by lambda phage, in which the phenomenon was discovered. It is used at two stages of phage expression. The antitermination protein produced at each stage is specific for the particular transcription units that are expressed at that stage.
The host RNA polymerase initially transcribes two genes, which are called the immediate early genes (N and cro). The transition to the next stage of expression is controlled by preventing termination at the ends of the immediate early genes, with the result that the delayed early genes are expressed. The antitermination protein pN acts specifically on the immediate early transcription units. Later during infection, another antitermination protein pQ acts specifically on the late transcription unit, to allow its transcription to continue past a termination sequence.
The different specificities on pN and pQ establish an important general principle: RNA polymerase interacts with transcription units in such a way that an ancillary factor can sponsor antitermination specifically for some transcripts. Termination can be controlled with the same sort of precision as initiation.
The antitermination activity of pN is highly specific, but the antitermination event is not determined by the terminators t and t; the recognition site needed for antitermination lies upstream in the transcription unit, that is, at a different place from the terminator site at which the action eventually is accomplished.
The recognition sites required for pN action are called nut (for N utilization). The sites responsible for determining leftward and rightward antitermination are described as nut and nut, respectively.
When pN recognizes the nut site, it forms a persistent antitermination complex in cooperation with a number of E. coli host proteins. These include three host Nus proteins, NusA, B, and C. NusA is an interesting protein. By itself in E. coli, it is part of the transcription termination system. However, when co-opted by N, it participates in antitermination. The complex must act on RNA polymerase to ensure that the enzyme can no longer respond to the terminator. The variable locations of the nut sites indicate that this event is linked neither to initiation nor to termination, but can occur to RNA polymerase as it elongates the RNA chain past the nut site. Phages that are related to lambda have different N genes and different antitermination specificities. The region on the phage genome in which the nut sites lie has a different sequence in each of these phages, and each phage must therefore have characteristic nut sites recognized specifically by its own pN. Each of these pN products must have the same general ability to interact with the transcription apparatus in an antitermination capacity, but each product also has a different specificity for the sequence of DNA that activates the mechanism. | 1 | Biochemistry |
TsOH is prepared on an industrial scale by the sulfonation of toluene. Common impurities include benzenesulfonic acid and sulfuric acid. TsOH monohydrate contains an amount of water. To estimate the total moisture present as impurity, the Karl Fischer method is used. Impurities can be removed by recrystallization from its concentrated aqueous solution followed by azeotropic drying with toluene.
TsOH finds use in organic synthesis as an "organic-soluble" strong acid. Examples of uses include:
*Acetalization of an aldehyde.
*Fischer–Speier esterification
*Transesterification reactions | 0 | Organic Chemistry |
The classical types of quantum systems, superconductors and superfluid helium, were discovered in the beginning of the 20th century. Near the end of the 20th century, scientists discovered how to create very dilute atomic or molecular gases, cooled first by laser cooling and then by evaporative cooling. They are trapped using magnetic fields or optical dipole potentials in ultrahigh vacuum chambers. Isotopes which have been used include rubidium (Rb-87 and Rb-85), strontium (Sr-87, Sr-86, and Sr-84) potassium (K-39 and K-40), sodium (Na-23), lithium (Li-7 and Li-6), and hydrogen (H-1). The temperatures to which they can be cooled are as low as a few nanokelvin. The developments have been very fast in the past few years. A team of NIST and the University of Colorado has succeeded in creating and observing vortex quantization in these systems. The concentration of vortices increases with the angular velocity of the rotation, similar to the case of superfluid helium and superconductivity. | 7 | Physical Chemistry |
The sum activity of peripheral deiodinases (G, also referred to as SPINA-GD) is reduced in nonthyroidal illness with hypodeiodination.
G is obtained with
or
: Dilution factor for T3 (reciprocal of apparent volume of distribution, 0.026 L)<br />
: Clearance exponent for T3 (8e-6 sec)<br />
K: Dissociation constant of type-1-deiodinase (5e-7 mol/L)<br />
K: Dissociation constant T3-TBG (2e9 L/mol) | 1 | Biochemistry |
In the adult brain, PPs are essential for synaptic functions and are involved in the negative regulation of higher-order brain functions such as learning and memory. Dysregulation of their activity has been linked to several disorders including cognitive ageing and neurodegeneration, as well as cancer, diabetes and obesity. | 1 | Biochemistry |
Imidoyl chlorides react readily with water, hydrogen sulfide, amines, and hydrogen halides. Treating imidoyl chlorides with water forms the corresponding amide:
:RC(NR’)Cl + HO → RCONHR’ + HCl
Aliphatic imidoyl chlorides are more sensitive toward hydrolysis than aryl derivatives. Electron-withdrawing substituents decrease the reaction rate. Imidoyl chlorides react with hydrogen sulfide to produce thioamides:
:RC(NR’)Cl + HS → RC(S)NHR’ + HCl
When amines are treated with imidoyl chlorides, amidines are obtained.
:RC(NR’)Cl + 2R”NH → RC(NR’)NHR” + R”NHCl
When R' ≠ R", two isomers are possible.
Upon heating, imidoyl chlorides also undergo dehydrohalogenation to form nitriles:
:RC(NR’)Cl → RC≡N + R’Cl
Treatment of imidoyl chloride with hydrogen halides, such as HCl, forms the corresponding iminium chloride cations:
:RC(NR’)Cl + HCl → [RC(NHR’)Cl]Cl | 0 | Organic Chemistry |
* The larvae of the berothid lacewing Lomamyia latipennis feed on termites which they subdue with an aggressive allomone. The first instar approaches a termite and waves the tip of its abdomen near the termite's head. The termite becomes immobile after 1 to 3 minutes, and completely paralysed very soon after this, although it may live for up to 3 hours. The berothid then feeds on the paralysed prey. The third instar feeds in a similar manner and may kill up to six termites at a time. Contact between the termite and the berothid is not necessary for subduing, and other insects present are not affected by the allomone.
* Bark beetles communicate via pheromones to announce a new food resource (i.e. dead trees, roots, living trees, etc.) ultimately resulting in the accumulation of a large concentration of bark beetles. Select species of bark beetles have the capability to emit pheromones that can negatively affect the behavioral response of another competing species of bark beetles when both species are attempting to inhabit the loblolly pine tree. A certain molecular compound within the released pheromone of one species can interfere with a competing species ability to respond its own species pheromone in the environment. This interaction aides the emitter by decreasing its local bark beetle competition. A competitive interaction occurring between two species of bark beetles is seen when the pheromones of G. sulcates interferes with the behavioral feedback of G. retusus. The impact of interactions between competing species fighting for food and space within an environment is seen when observing the California I. pini. The I. pinihave two receptors in which one is used to receive the pheromone of their own species and the other receptor receives the pheromone of their competing species. The presence of these two receptors makes sure that pheromones from their own species, I. pini, are not being interrupted by their competing species, I. paraconfusus.
* Arthropods that travel alone, like beetles and cockroaches, have evolved to emit pheromones when in the presence of ants in which the emitted pheromone is identical to the ant's alarm pheromone. The alarm pheromone of the worker ants causes the ants to stop what they are doing and to return to their nest till the alarm pheromone ceases in their environment. This release of an ant alarm pheromone by an arthropod causes the ants to go into alarm and allows the arthropod to escape its predators before the ants are able to recruit more workers. | 1 | Biochemistry |
Inhibition of DNA repair processes is considered one of main mechanism of inorganic arsenic genotoxicity. Nucleotide excision repair (NER) and base excision repair (BER) are the processes implicated in the repair of DNA base damage induced by ROS after arsenic exposure. In particular, the NER mechanism is the major pathway for repairing bulky distortions in DNA double helix, while the BER mechanism is mainly implicated in the repair of single strand breaks induced by ROS, but inorganic arsenic could also repress the BER mechanism. | 1 | Biochemistry |
On the diagram, lines of constant pressure, constant temperature and volume are plotted, so in a two-phase region, the lines of constant pressure and temperature coincide.
Thus, coordinates on the diagram represent entropy and heat.
The work done in a process on vapor cycles is represented by length of , so it can be measured directly, whereas in a T–s diagram it has to be computed using thermodynamic relationship between thermodynamic properties.
In an isobaric process, the pressure remains constant, so the heat interaction is the change in enthalpy.
In an isenthalpic process, the enthalpy is constant. A horizontal line in the diagram represents an isenthalpic process.
A vertical line in the h–s chart represents an isentropic process. The process 3–4 in a Rankine cycle is isentropic when the steam turbine is said to be an ideal one. So the expansion process in a turbine can be easily calculated using the h–s chart when the process is considered to be ideal (which is the case normally when calculating enthalpies, entropies, etc. Later the deviations from the ideal values and they can be calculated considering the isentropic efficiency of the steam turbine used.)
Lines of constant dryness fraction (x), sometimes called the quality, are drawn in the wet region and lines of constant temperature are drawn in the superheated region. X gives the fraction (by mass) of gaseous substance in the wet region, the remainder being colloidal liquid droplets. Above the heavy line, the temperature is above the boiling point, and the dry (superheated) substance is gas only.
In general such charts do not show the values of specific volumes, nor do they show the enthalpies of saturated water at pressures which are of the order of those experienced in condensers in a thermal power station. Hence the chart is only useful for enthalpy changes in the expansion process of the steam cycle. | 7 | Physical Chemistry |
In biochemistry, equilibrium unfolding is the process of unfolding a protein or RNA molecule by gradually changing its environment, such as by changing the temperature or pressure, pH, adding chemical denaturants, or applying force as with an atomic force microscope tip. If the equilibrium was maintained at all steps, the process theoretically should be reversible during equilibrium folding. Equilibrium unfolding can be used to determine the thermodynamic stability of the protein or RNA structure, i.e. free energy difference between the folded and unfolded states. | 7 | Physical Chemistry |
In November 2007, a controversial aerial approach was used to spray microencapsulated LBAM pheromone in urban and rural areas of the counties of Santa Cruz and Monterey California to combat the invasive light brown apple moth. Usually the effect of disruption of orientation of the male moths to females (or monitoring pheromone traps) can be detected by the reduction in moth capture in monitoring pheromone traps. The government campaign using areawide aerial microencapsulated pheromone applications failed to show any sign of mating disruption on the light brown apple moth populations in the treated area. It was found that the first aerial campaign was performed using an incomplete (the wrong) pheromone blend of the light brown apple moth (the wrong blend decreased tremendously the likelihood of success of the mating disruption program), and the LBAM microencapsulated formulation was untested, and finally, microencapsule formulations are notoriously known for their short field life, weak and erratic performance. Furthermore it is possible that the LBAM microencapsulated formulation used in the government campaign was unfit for aerial delivery in urban areas; although pheromone is safe, the formulation used had microcapsules of very small diameter which made it into a possible inhalation hazard that seems to be linked to an increase in allergenic reactions of the population in the target area. This set of LBAM mating disruption aerial applications done by the government has created tremendous dissent of the public in general as well as of several sectors of the scientific community. Now, several years later, the affected communities as well as the nascent US pheromone industry (which provides safer, yet very effective, alternatives to the use of conventional pesticides) are still suffering the ripple effects of these disastrous Bay Area LBAM eradication campaigns.
But there are numerous, successful pest suppression programs that rely on aerial dispersal of pheromone mating disruptants. One of the largest pheromone mating disruption programs in the globe is Slow the Spread. Slow the Spread has been implemented across the spongy moth frontier from Wisconsin to North Carolina. The program area is located ahead of the advancing front of the spongy moth population. The STS program focuses on early detection and suppression of the low–level populations along this advancing front, disrupting the natural progress of population buildup and spread. Every year hundreds of thousands of acres are aerially sprayed with two pheromone spongy moth pheromone mating disruption formulations, Flakes and SPLAT. A single mating disruption formulation application promotes season-long suppression of spongy moth in the treated areas. With a crew of 8 people it was possible to aerially treat with SPLAT GM over of forest in a single day. The consortium of Federal and State participants have been able to do the following:
• decrease the new territory invaded by the spongy moth each year from to ;
• protect forests, forest–based industries, urban and rural parks, and private property; and
• avoid at least $22 million per year in damage and management costs.
It seems that the tremendous success of the Slow the Spread program is related to extremely well planned campaigns, which involves communication, transparency and clarity of objectives: in advance to an application STS holds meetings that include the area population in general, concerned citizens, public officials, scientists and technical personnel to discuss strategies of management of spongy moths in the areas of concern. There is a movement requesting that new government invasive species eradication campaigns model their pest suppression actions on the existing successful suppression programs like STS, and embrace a more effective policy of communication, transparency and clarity of objectives. With the involvement and education of the public, areawide eradication campaigns will be better planned and more able to deliver decisive end effective pest eradication actions. | 1 | Biochemistry |
MEGAN ("MEtaGenome ANalyzer") is a computer program that allows optimized analysis of large metagenomic datasets.
Metagenomics is the analysis of the genomic sequences from a usually uncultured environmental sample. A large term goal of most metagenomics is to inventory and measure the extent and the role of microbial biodiversity in the ecosystem due to discoveries that the diversity of microbial organisms and viral agents in the environment is far greater than previously estimated. Tools that allow the investigation of very large data sets from environmental samples using shotgun sequencing techniques in particular, such as MEGAN, are designed to sample and investigate the unknown biodiversity of environmental samples where more precise techniques with smaller, better known samples, cannot be used.
Fragments of DNA from an metagenomics sample, such as ocean waters or soil, are compared against databases of known DNA sequences using BLAST or another sequence comparison tool to assemble the segments into discrete comparable sequences. MEGAN is then used to compare the resulting sequences with gene sequences from GenBank in NCBI. The program was used to investigate the DNA of a mammoth recovered from the Siberian permafrost and Sargasso Sea data set. | 1 | Biochemistry |
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