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Another possible effect would be an increase in harmful algal bloom events, which could contribute to the accumulation of toxins (domoic acid, brevetoxin, saxitoxin) in small organisms such as anchovies and shellfish, in turn increasing occurrences of amnesic shellfish poisoning, neurotoxic shellfish poisoning and paralytic shellfish poisoning. Although algal blooms can be harmful, other beneficial photosynthetic organisms may benefit from increased levels of carbon dioxide. Most importantly, seagrasses will benefit. Research found that as seagrasses increased their photosynthetic activity, calcifying algae's calcification rates rose, likely because localized photosynthetic activity absorbed carbon dioxide and elevated local pH. | 0 | Theoretical and Fundamental Chemistry |
TMTTF as well as BEDT-TTF are based on the molecule TTF (tetrathiafulvalene). Using tetrathiapentalene (TTP) as basic molecules one receives a variety of new organic molecules serving as cations in organic crystals. Some of them are superconducting. This class of superconductors was only reported recently and investigations are still under process. | 0 | Theoretical and Fundamental Chemistry |
The Nyaya of logic is said to have been founded by a sage named Gautama. He is also known as Gautama, Aksapada and Dirghatapas. The names Gotama and Gautama points to the family to which he belonged while the names Aksapada and Dirghatapas refer respectively to his meditative habit and practice of long penance. The people of Mithila (modern Darbhanga in North Bihar) ascribe the foundation of Nyāya philosophy to Gautama, husband of Ahalya, and point out as the place of his birth a village named Gautamasthana where a fair is held every year on the 9th day of the lunar month of Chaitra (March–April). It is situated 28 miles north-east of Darbhanga.
The historical development of Nyāya school is unclear, although Nasadiya hymns of Book 10 Chapter 129 of Rigveda recite its spiritual questions in logical propositions. In early centuries BCE, states Clooney, the early Nyāya scholars began compiling the science of rational, coherent inquiry and pursuit of knowledge. By the 2nd century CE, Aksapada Gautama had composed Nyāya Sūtras, a foundational text for Nyāya school, that primarily discusses logic, methodology and epistemology. The Nyāya scholars that followed refined it, expanded it, and applied it to spiritual questions. While the early Nyaya scholars published little to no analysis on whether supernatural power or God exists, they did apply their insights into reason and reliable means to knowledge to the questions of nature of existence, spirituality, happiness and moksha. Later Nyāya scholars, such as Udayana, examined various arguments on theism and attempted to prove existence of God. Other Nyāya scholars offered arguments to disprove the existence of God.
The most important contribution made by the Nyāya school to Hindu thought has been its treatises on epistemology and system of logic that, subsequently, has been adopted by the majority of the other Indian schools. | 1 | Applied and Interdisciplinary Chemistry |
The presence of fulgurites in an area can be used to estimate the frequency of lightning over a period of time, which can help to understand past regional climates. Paleolightning is the study of various indicators of past lightning strikes, primarily in the form of fulgurites and lightning-induced remanent magnetization (LIRM) signatures. | 0 | Theoretical and Fundamental Chemistry |
A device that can produce monochromatic light has many uses in science and in optics because many optical characteristics of a material are dependent on wavelength. Although there are a number of useful ways to select a narrow band of wavelengths (which, in the visible range, is perceived as a pure color), there are not as many other ways to easily select any wavelength band from a wide range. See below for a discussion of some of the uses of monochromators.
In hard X-ray and neutron optics, crystal monochromators are used to define wave conditions on the instruments. | 0 | Theoretical and Fundamental Chemistry |
In proliferating cells, certain pRb conformations (when RxL motif if bound by protein phosphatase 1 or when it is acetylated or methylated) are resistant to CDK phosphorylation and retain other function throughout cell cycle progression, suggesting not all pRb in the cell are devoted to guarding the G1/S transition.
Studies have also demonstrated that hyperphosphorylated pRb can specifically bind E2F1 and form stable complexes throughout the cell cycle to carry out unique unexplored functions, a surprising contrast from the classical view of pRb releasing E2F factors upon phosphorylation.
In summary, many new findings about pRb's resistance to CDK phosphorylation are emerging in pRb research and shedding light on novel roles of pRb beyond cell cycle regulation. | 1 | Applied and Interdisciplinary Chemistry |
The disadvantages in "receptivity" are compensated by the high sensitivity of C NMR signals to the chemical environment of the nucleus, i.e. the chemical shift "dispersion" is great, covering nearly 250 ppm. This dispersion reflects the fact that non-H nuclei are strongly influenced by excited states ("paramagnetic" contribution to shielding tensor. This paramagnetic contribution is unrelated to paramagnetism). For example, most H NMR signals for most organic compounds are within 15 ppm.
The chemical shift reference standard for
C is the carbons in tetramethylsilane (TMS),
whose chemical shift is set as 0.0 ppm at every temperature. | 0 | Theoretical and Fundamental Chemistry |
Thermodynamic cycles may be used to model real devices and systems, typically by making a series of assumptions. simplifying assumptions are often necessary to reduce the problem to a more manageable form. For example, as shown in the figure, devices such a gas turbine or jet engine can be modeled as a Brayton cycle. The actual device is made up of a series of stages, each of which is itself modeled as an idealized thermodynamic process. Although each stage which acts on the working fluid is a complex real device, they may be modelled as idealized processes which approximate their real behavior. If energy is added by means other than combustion, then a further assumption is that the exhaust gases would be passed from the exhaust to a heat exchanger that would sink the waste heat to the environment and the working gas would be reused at the inlet stage.
The difference between an idealized cycle and actual performance may be significant. For example, the following images illustrate the differences in work output predicted by an ideal Stirling cycle and the actual performance of a Stirling engine:
As the net work output for a cycle is represented by the interior of the cycle, there is a significant difference between the predicted work output of the ideal cycle and the actual work output shown by a real engine. It may also be observed that the real individual processes diverge from their idealized counterparts; e.g., isochoric expansion (process 1-2) occurs with some actual volume change. | 0 | Theoretical and Fundamental Chemistry |
The Lauritzen–Hoffman growth theory breaks the kinetics of polymer crystallization into ultimately two rates. The model breaks down into the addition of monomers onto a growing surface. This initial step is generally associated with the nucleation of the polymer. From there, the kinetics become the rate which the polymer grows on the surface, or the lateral growth rate, in comparison with the growth rate onto the polymer extending the chain, the secondary nucleation rate. These two rates can result in three situations. | 0 | Theoretical and Fundamental Chemistry |
Scytovirin is a 95-amino acid antiviral protein isolated from the cyanobacteria Scytonema varium. It has been cultured in E. coli and its structure investigated in detail. Scytovirin is thought to be produced by the bacteria to protect itself from viruses that might otherwise attack it, but as it has broad-spectrum antiviral activity against a range of enveloped viruses, scytovirin has also been found to be useful against a range of major human pathogens, most notably HIV / AIDS but also including SARS coronavirus and filoviruses such as Ebola virus and Marburg virus. While some lectins such as cyanovirin and Urtica dioica agglutinin are thought likely to be too allergenic to be used internally in humans, studies so far on scytovirin and griffithsin have not shown a similar level of immunogenicity. Scytovirin and griffithsin are currently being investigated as potential microbicides for topical use. | 1 | Applied and Interdisciplinary Chemistry |
Common organosulfur compounds present in petroleum fractions at the level of 200–500 ppm. Common compounds are thiophenes, especially dibenzothiophenes. By the process of hydrodesulfurization (HDS) in refineries, these compounds are removed as illustrated by the hydrogenolysis of thiophene: | 0 | Theoretical and Fundamental Chemistry |
In convergent beam electron diffraction (CBED), the incident electrons are normally focused in a converging cone-shaped beam with a crossover located at the sample, e.g. Figure 17, although other methods exist. Unlike the parallel beam, the convergent beam is able to carry information from the sample volume, not just a two-dimensional projection available in SAED. With convergent beam there is also no need for the selected area aperture, as it is inherently site-selective since the beam crossover is positioned at the object plane where the sample is located.
A CBED pattern consists of disks arranged similar to the spots in SAED. Intensity within the disks represents dynamical diffraction effects and symmetries of the sample structure, see Figure 7 and 18. Even though the zone axis and lattice parameter analysis based on disk positions does not significantly differ from SAED, the analysis of disks content is more complex and simulations based on dynamical diffraction theory is often required. As illustrated in Figure 18, the details within the disk change with sample thickness, as does the inelastic background. With appropriate analysis CBED patterns can be used for indexation of the crystal point group, space group identification, measurement of lattice parameters, thickness or strain.
The disk diameter can be controlled using the microscope optics and apertures. The larger is the angle, the broader the disks are with more features. If the angle is increased to significantly, the disks begin to overlap. This is avoided in large angle convergent electron beam diffraction (LACBED) where the sample is moved upwards or downwards. There are applications, however, where the overlapping disks are beneficial, for instance with a ronchigram. It is a CBED pattern, often but not always of an amorphous material, with many intentionally overlapping disks providing information about the optical aberrations of the electron optical system. | 0 | Theoretical and Fundamental Chemistry |
Fats are broken down by conversion to acyl-CoA. This conversion is one response to high energy demands such as exercise.
The oxidative degradation of fatty acids is a two-step process, catalyzed by acyl-CoA synthetase. Fatty acids are converted to their acyl phosphate, the precursor to acyl-CoA. The latter conversion is mediated by acyl-CoA synthase"
:acyl-P + HS-CoA → acyl-S-CoA + P + H
Three types of acyl-CoA synthases are employed, depending on the chain length of the fatty acid. For example, the substrates for medium chain acyl-CoA synthase are 4-11 carbon fatty acids. The enzyme acyl-CoA thioesterase takes of the acyl-CoA to form a free fatty acid and coenzyme A. | 1 | Applied and Interdisciplinary Chemistry |
Common chemical shift ranges for nuclei within carbohydrate residues are:
*Typical H NMR chemical shifts of carbohydrate ring protons are 3–6 ppm (4.5–5.5 ppm for anomeric protons).
*Typical C NMR chemical shifts of carbohydrate ring carbons are 60–110 ppm
In the case of simple mono- and oligosaccharide molecules, all proton signals are typically separated from one another (usually at 500 MHz or better NMR instruments) and can be assigned using 1D NMR spectrum only. However, bigger molecules exhibit significant proton signal overlap, especially in the non-anomeric region (3-4 ppm). Carbon-13 NMR overcomes this disadvantage by larger range of chemical shifts and special techniques allowing to block carbon-proton spin coupling, thus making all carbon signals high and narrow singlets distinguishable from each other.
The typical ranges of specific carbohydrate carbon chemical shifts in the unsubstituted monosaccharides are:
*Anomeric carbons: 90-100 ppm
*Sugar ring carbons bearing a hydroxy function: 68-77
*Open-form sugar carbons bearing a hydroxy function: 71-75
*Sugar ring carbons bearing an amino function: 50-56
*Exocyclic hydroxymethyl groups: 60-64
*Exocyclic carboxy groups: 172-176
*Desoxygenated sugar ring carbons: 31-40
*A carbon at pyranose ring closure: 71-73 (α-anomers), 74-76 (β-anomers)
*A carbon at furanose ring closure: 80-83 (α-anomers), 83-86 (β-anomers) | 0 | Theoretical and Fundamental Chemistry |
Surprisals add where probabilities multiply. The surprisal for an event of probability is defined as . If is then surprisal is in nats, bits, or so that, for instance, there are bits of surprisal for landing all "heads" on a toss of coins.
Best-guess states (e.g. for atoms in a gas) are inferred by maximizing the average surprisal (entropy) for a given set of control parameters (like pressure or volume ). This constrained entropy maximization, both classically and quantum mechanically, minimizes Gibbs availability in entropy units where is a constrained multiplicity or partition function.
When temperature is fixed, free energy () is also minimized. Thus if and number of molecules are constant, the Helmholtz free energy (where is energy and is entropy) is minimized as a system "equilibrates." If and are held constant (say during processes in your body), the Gibbs free energy is minimized instead. The change in free energy under these conditions is a measure of available work that might be done in the process. Thus available work for an ideal gas at constant temperature and pressure is where and (see also Gibbs inequality).
More generally the work available relative to some ambient is obtained by multiplying ambient temperature by relative entropy or net surprisal defined as the average value of where is the probability of a given state under ambient conditions. For instance, the work available in equilibrating a monatomic ideal gas to ambient values of and is thus , where relative entropy
The resulting contours of constant relative entropy, shown at right for a mole of Argon at standard temperature and pressure, for example put limits on the conversion of hot to cold as in flame-powered air-conditioning or in the unpowered device to convert boiling-water to ice-water discussed here. Thus relative entropy measures thermodynamic availability in bits. | 0 | Theoretical and Fundamental Chemistry |
The most basic rule of dimensional analysis is that of dimensional homogeneity.
However, the dimensions form an abelian group under multiplication, so:
For example, it makes no sense to ask whether 1 hour is more, the same, or less than 1 kilometre, as these have different dimensions, nor to add 1 hour to 1 kilometre. However, it makes sense to ask whether 1 mile is more, the same, or less than 1 kilometre, being the same dimension of physical quantity even though the units are different. On the other hand, if an object travels 100 km in 2 hours, one may divide these and conclude that the object's average speed was 50 km/h.
The rule implies that in a physically meaningful expression only quantities of the same dimension can be added, subtracted, or compared. For example, if , and denote, respectively, the mass of some man, the mass of a rat and the length of that man, the dimensionally homogeneous expression is meaningful, but the heterogeneous expression is meaningless. However, is fine. Thus, dimensional analysis may be used as a sanity check of physical equations: the two sides of any equation must be commensurable or have the same dimensions.
Even when two physical quantities have identical dimensions, it may nevertheless be meaningless to compare or add them. For example, although torque and energy share the dimension , they are fundamentally different physical quantities.
To compare, add, or subtract quantities with the same dimensions but expressed in different units, the standard procedure is first to convert them all to the same unit. For example, to compare 32 metres with 35 yards, use to convert 35 yards to 32.004 m.
A related principle is that any physical law that accurately describes the real world must be independent of the units used to measure the physical variables. For example, Newton's laws of motion must hold true whether distance is measured in miles or kilometres. This principle gives rise to the form that a conversion factor between a unit that measures the same dimension must take: multiplication by a simple constant. It also ensures equivalence; for example, if two buildings are the same height in feet, then they must be the same height in metres. | 1 | Applied and Interdisciplinary Chemistry |
The 2015 paper by Jónasdóttir et al., marked the first comprehensive accounting for the amount of carbon sequestration resulting from the movement of lipids by vertically migrating zooplankton during their overwintering diapuse. Although only elucidating the impact of one particular species, in this case, C. finmarchicus, both the magnitude of carbon flux and widespread global distribution of Calanus spp. suggest the possible importance of the lipid pump in global carbon cycling by contributing an estimated 50–100% of carbon sequestration to the biological pump. Subsequent research has underscored this significance as estimates that attempt to more accurately account for the mortality and respiration rates of other overwintering Calanus spp. have suggested similar, although regionally variable, magnitudes of carbon export from the lipid pump. Overwintering diapause is an ecological strategy to enable Calanus spp. to adapt to the seasonal variability in food availability in ocean basins. Changes in the timing or length of high food periods are likely to negatively impact the distribution and abundance of Calanus spp. Changes in ocean temperature and salinity due to anthropogenic climate change are also predicted to decrease concentrations of Calanus spp. in some ocean basins. In addition to potential ecosystem impacts due to the large number of species that rely on copepods as a major constituent of their diets, there may be implications for oceanic carbon sequestration from consequent changes in the magnitude of the lipid pump due to overwintering zooplankton. | 0 | Theoretical and Fundamental Chemistry |
Phosphoinositide phospholipase C (PLC, EC 3.1.4.11, triphosphoinositide phosphodiesterase, phosphoinositidase C, 1-phosphatidylinositol-4,5-bisphosphate phosphodiesterase, monophosphatidylinositol phosphodiesterase, phosphatidylinositol phospholipase C, PI-PLC, 1-phosphatidyl--myo-inositol-4,5-bisphosphate inositoltrisphosphohydrolase; systematic name 1-phosphatidyl-1-myo-inositol-4,5-bisphosphate inositoltrisphosphohydrolase) is a family of eukaryotic intracellular enzymes that play an important role in signal transduction processes. These enzymes belong to a larger superfamily of Phospholipase C. Other families of phospholipase C enzymes have been identified in bacteria and trypanosomes. Phospholipases C are phosphodiesterases.
Phospholipase Cs participate in phosphatidylinositol 4,5-bisphosphate (PIP) metabolism and lipid signaling pathways in a calcium-dependent manner. At present, the family consists of six sub-families comprising a total of 13 separate isoforms that differ in their mode of activation, expression levels, catalytic regulation, cellular localization, membrane binding avidity and tissue distribution. All are capable of catalyzing the hydrolysis of PIP into two important second messenger molecules, which go on to alter cell responses such as proliferation, differentiation, apoptosis, cytoskeleton remodeling, vesicular trafficking, ion channel conductance, endocrine function and neurotransmission. | 1 | Applied and Interdisciplinary Chemistry |
The idea that life originated from non-living matter in slow stages appeared in Herbert Spencers 1864–1867 book Principles of Biology, and in William Turner Thiselton-Dyers 1879 paper "On spontaneous generation and evolution". On 1 February 1871 Charles Darwin wrote about these publications to Joseph Hooker, and set out his own speculation, suggesting that the original spark of life may have begun in a "warm little pond, with all sorts of ammonia and phosphoric salts, light, heat, electricity, , present, that a compound was chemically formed ready to undergo still more complex changes." Darwin went on to explain that "at the present day such matter would be instantly devoured or absorbed, which would not have been the case before living creatures were formed."
Alexander Oparin in 1924 and J. B. S. Haldane in 1929 proposed that the first molecules constituting the earliest cells slowly self-organized from a primordial soup, and this theory is called the Oparin–Haldane hypothesis. Haldane suggested that the Earth's prebiotic oceans consisted of a "hot dilute soup" in which organic compounds could have formed. J. D. Bernal showed that such mechanisms could form most of the necessary molecules for life from inorganic precursors. In 1967, he suggested three "stages": the origin of biological monomers; the origin of biological polymers; and the evolution from molecules to cells. | 0 | Theoretical and Fundamental Chemistry |
Thymidine diphosphate glucose (often abbreviated dTDP-glucose or TDP-glucose) is a nucleotide-linked sugar consisting of deoxythymidine diphosphate linked to glucose. It is the starting compound for the syntheses of many deoxysugars. | 1 | Applied and Interdisciplinary Chemistry |
When laser cooling was proposed in 1975, a theoretical limit on the lowest possible temperature was predicted. Known as the Doppler limit, , this was given by the lowest possible temperature attainable considering the cooling of two-level atoms by Doppler cooling and the heating of atoms due to momentum diffusion from the scattering of laser photons. Here, , is the natural line-width of the atomic transition, , is the reduced Planck constant and, , is the Boltzmann constant.
Experiments at the National Institute of Standards and Technology, Gaithersburg, found the temperature of cooled atoms to be well below the theoretical limit.In 1988, Lett et al. directed Sodium atoms through an optical molasses and found the temperatures to be as low as ~40μk; 6 times lower than the expected 240μk doppler cooling limit. Other unexpected properties found in other experimentsincluded significant unexpected insensitivity to laser alignment of the counter-propagating beams. | 0 | Theoretical and Fundamental Chemistry |
Galling is adhesive wear that is caused by the microscopic transfer of material between metallic surfaces during transverse motion (sliding). It occurs frequently whenever metal surfaces are in contact, sliding against each other, especially with poor lubrication. It often occurs in high-load, low-speed applications, although it also can occur in high-speed applications with very little load. Galling is a common problem in sheet metal forming, bearings and pistons in engines, hydraulic cylinders, air motors, and many other industrial operations. Galling is distinct from gouging or scratching in that it involves the visible transfer of material as it is adhesively pulled (mechanically spalled) from one surface, leaving it stuck to the other in the form of a raised lump (gall). Unlike other forms of wear, galling is usually not a gradual process but occurs quickly and spreads rapidly as the raised lumps induce more galling.
It can often occur in screws and bolts, causing the threads to seize and tear free from the fastener or the hole. In extreme cases, the bolt may seize without stripping the threads, which can lead to breakage of the fastener, the tool, or both. Threaded inserts of hardened steel are often used in metals like aluminium or stainless steel that can gall easily.
Galling requires two properties common to most metals, cohesion through metallic-bonding attractions and plasticity (the ability to deform without breaking). The tendency of a material to gall is affected by the ductility of the material. Typically, hardened materials are more resistant to galling, whereas softer materials of the same type will gall more readily. The propensity of a material to gall is also affected by the specific arrangement of the atoms, because crystals arranged in a face-centered cubic (FCC) lattice will usually allow material-transfer to a greater degree than a body-centered cubic (BCC). This is because a face-centered cubic has a greater tendency to produce dislocations in the crystal lattice, which are defects that allow the lattice to shift, or "cross-slip," making the metal more prone to galling. However, if the metal has a high number of stacking faults (a difference in stacking sequence between atomic planes), it will be less apt to cross-slip at the dislocations. Therefore, a materials resistance to galling is primarily determined by its stacking-fault energy. A material with high stacking-fault energy, such as aluminium or titanium, will be far more susceptible to galling than materials with low stacking-fault energy, like copper, bronze, or gold. Conversely, materials with a hexagonal close packed (HCP) structure and a high c/a' ratio, such as cobalt-based alloys, are extremely resistant to galling.
Galling occurs initially with material transfer from individual grains on a microscopic scale, which become stuck or even diffusion welded to the adjacent surface. This transfer can be enhanced if one or both metals form a thin layer of hard oxides with high coefficients of friction, such as those found on aluminum or stainless steel. As the lump grows, it pushes against the adjacent material, forcing them apart and concentrating most of the friction heat energy into a very small area. This, in turn, causes more adhesion and material build-up. The localized heat increases the plasticity of the galled surface, deforming the metal until the lump breaks through the surface and begins plowing up large amounts of material from the galled surface. Methods of preventing galling include the use of lubricants like grease and oil, low-friction coatings and thin-film deposits like molybdenum disulfide or titanium nitride, and increasing the surface hardness of the metals using processes such as case hardening and induction hardening. | 0 | Theoretical and Fundamental Chemistry |
There are many environmental health mapping tools. TOXMAP is a Geographic Information System (GIS) from the Division of Specialized Information Services of the United States National Library of Medicine (NLM) that uses maps of the United States to help users visually explore data from the United States Environmental Protection Agencys (EPA) Toxics Release Inventory and Superfund programs. TOXMAP is a resource funded by the US Federal Government. TOXMAPs chemical and environmental health information is taken from NLM's Toxicology Data Network
(TOXNET) and PubMed, and from other authoritative sources. | 1 | Applied and Interdisciplinary Chemistry |
Dissimilar metals and alloys have different electrode potentials, and when two or more come into contact in an electrolyte, one metal (that is more reactive) acts as anode and the other (that is less reactive) as cathode. The electropotential difference between the reactions at the two electrodes is the driving force for an accelerated attack on the anode metal, which dissolves into the electrolyte. This leads to the metal at the anode corroding more quickly than it otherwise would and corrosion at the cathode being inhibited. The presence of an electrolyte and an electrical conducting path between the metals is essential for galvanic corrosion to occur. The electrolyte provides a means for ion migration whereby ions move to prevent charge build-up that would otherwise stop the reaction. If the electrolyte contains only metal ions that are not easily reduced (such as Na, Ca, K, Mg, or Zn), the cathode reaction is the reduction of dissolved H to H or O to OH.
In some cases, this type of reaction is intentionally encouraged. For example, low-cost household batteries typically contain carbon-zinc cells. As part of a closed circuit (the electron pathway), the zinc within the cell will corrode preferentially (the ion pathway) as an essential part of the battery producing electricity. Another example is the cathodic protection of buried or submerged structures as well as hot water storage tanks. In this case, sacrificial anodes work as part of a galvanic couple, promoting corrosion of the anode, while protecting the cathode metal.
In other cases, such as mixed metals in piping (for example, copper, cast iron and other cast metals), galvanic corrosion will contribute to accelerated corrosion of parts of the system. Corrosion inhibitors such as sodium nitrite or sodium molybdate can be injected into these systems to reduce the galvanic potential. However, the application of these corrosion inhibitors must be monitored closely. If the application of corrosion inhibitors increases the conductivity of the water within the system, the galvanic corrosion potential can be greatly increased.
Acidity or alkalinity (pH) is also a major consideration with regard to closed loop bimetallic circulating systems. Should the pH and corrosion inhibition doses be incorrect, galvanic corrosion will be accelerated. In most HVAC systems, the use of sacrificial anodes and cathodes is not an option, as they would need to be applied within the plumbing of the system and, over time, would corrode and release particles that could cause potential mechanical damage to circulating pumps, heat exchangers, etc. | 1 | Applied and Interdisciplinary Chemistry |
Denitrification is the biochemical reduction of oxidized nitrogen anions, nitrate and nitrite to produce the gaseous products nitric oxide (NO), nitrous oxide () and nitrogen gas (), with concomitant oxidation of organic matter. The end product, , and to a lesser extent the intermediary by product, , are gases that re-enter the atmosphere. | 1 | Applied and Interdisciplinary Chemistry |
In molecular biology, repeat-induced point mutation or RIP is a process by which DNA accumulates G:C to A:T transition mutations. Genomic evidence indicates that RIP occurs or has occurred in a variety of fungi while experimental evidence indicates that RIP is active in Neurospora crassa, Podospora anserina, Magnaporthe grisea, Leptosphaeria maculans, Gibberella zeae and Nectria haematococca. In Neurospora crassa, sequences mutated by RIP are often methylated de novo.
RIP occurs during the sexual stage in haploid nuclei after fertilization but prior to meiotic DNA replication. In Neurospora crassa, repeat sequences of at least 400 base pairs in length are vulnerable to RIP. Repeats with as low as 80% nucleotide identity may also be subject to RIP. Though the exact mechanism of repeat recognition and mutagenesis are poorly understood, RIP results in repeated sequences undergoing multiple transition mutations.
The RIP mutations do not seem to be limited to repeated sequences. Indeed, for example, in the phytopathogenic fungus L. maculans, RIP mutations are found in single copy regions, adjacent to the repeated elements. These regions are either non-coding regions or genes encoding small secreted proteins including avirulence genes.
The degree of RIP within these single copy regions was proportional to their proximity to repetitive elements.
Rep and Kistler have speculated that the presence of highly repetitive regions containing transposons, may promote mutation of resident effector genes. So the presence of effector genes within such regions is suggested to promote their adaptation and diversification when exposed to strong selection pressure.
As RIP mutation is traditionally observed to be restricted to repetitive regions and not single copy regions, Fudal et al. suggested that leakage of RIP mutation might occur within a relatively short distance of a RIP-affected repeat. Indeed, this has been reported in N. crassa whereby leakage of RIP was detected in single copy sequences at least 930 bp from the boundary of neighbouring duplicated sequences.
To elucidate the mechanism of detection of repeated sequences leading to RIP may allow to understand how the flanking sequences may also be affected. | 1 | Applied and Interdisciplinary Chemistry |
In 1906, Boltwood returned to Yale as an assistant professor of physics at a time when the newly discovered science of radioactivity was considered both chemistry and physics. He would eventually become the leading American scientist in the field, and be appointed chair of radiochemistry in 1910, a position that was the first of its kind. He developed a friendship with Ernest Rutherford, whose highly influential thinking played a role in much of Boltwoods work. They communicated primarily through overseas correspondence, with the exception of a short period from 1909-1910 when Rutherford invited Boltwood to join him at University of Manchester in England. Their letters from 1904-1912 were published in 1969 in the book Rutherford and Boltwood: Letters on Radioactivity, which reveals an ongoing conversation as the two scientists work to unravel details of radioactivity and the uranium decay series.' | 0 | Theoretical and Fundamental Chemistry |
Praseodymium(III) fluoride forms pale green crystals of trigonal system (or hexagonal system), space group P 3c1, (or P 6/mcm), cell parameters a = 0.7078 nm, c = 0.7239 nm, Z = 6, structure like cerium(III) fluoride (CeF). | 0 | Theoretical and Fundamental Chemistry |
Although not well understood at the time, the Fürst-Plattner rule played a critical role during R. B. Woodward's synthesis of Reserpine. The problematic stereocenter is highlighted in red, below.
Woodward's synthetic strategy used a Bischler-Napieralski reaction to form the tetrahydrocarbazole portion of Reserpine. The subsequent imine intermediate was treated with sodium borohydride, affording the wrong stereoisomer due to the Fürst-Plattner effect.
Examining the intermediate structure shows that the hydride preferentially added to the 3-carbon via the top face of the imine to avoid an unfavorable twist-boat intermediate. Unfortunately, this outcome required Woodward to perform several additional steps to complete the total synthesis of reserpine with the proper stereochemistry. | 0 | Theoretical and Fundamental Chemistry |
A distinction is made between high-pressure and low-pressure inflatables. In a high-pressure inflatable, structural limbs like pillars and arches are built out of a tough, flexible material and then inflated at a relatively high pressure. These limbs hold up passive membranes. The space where the visitors or inhabitants stay is at normal atmospheric pressure. For example, airplane emergency rafts are high-pressure inflatable structures. Low-pressure inflatables, on the other hand, are slightly pressurized environments completely held up by internal pressure. In other words, the visitors or inhabitants experience a slightly higher than normal pressure. Low-pressure inflatables are usually built of lighter materials. Both types of inflatables (the low-pressure type more so) are somewhat susceptible to high winds. | 1 | Applied and Interdisciplinary Chemistry |
In the history of the periodic table, Döbereiner's triads were an early attempt to sort the elements into some logical order and sets based on their physical properties. They are analogous to the groups (columns) on the modern periodic table. 53 elements were known at his time.
In 1817, a letter by reported Johann Wolfgang Döbereiner's observations of the alkaline earths; namely, that strontium had properties that were intermediate to those of calcium and barium.
By 1829, Döbereiner had found other groups of three elements (hence "triads") whose physical properties were similarly related. He also noted that some quantifiable properties of elements (e.g. atomic weight and density) in a triad followed a trend whereby the value of the middle element in the triad would be exactly or nearly predicted by taking the arithmetic mean of values for that property of the other two elements. These are as follows:
Limitations:
Not all the known elements could be arranged in the form of triads. For very low-mass or very high mass elements, the Döbereiners triads are not applicable. Take the example of F (Fluorine), Cl (Chlorine), and Br (Bromine). The atomic mass of Cl is not an arithmetic mean of the atomic masses of F and Br. As the techniques for accurately measuring atomic masses improved, the Döbereiners triad was found to fail to remain strictly valid. | 1 | Applied and Interdisciplinary Chemistry |
Devardas alloy (alloy of aluminium (~45%), copper (~50%) and zinc (~5%)) is a reducing agent that was commonly used in wet analytical chemistry to produce in situ' so-called nascent hydrogen under alkaline conditions for the determination of nitrates () after their reduction into ammonia ().
In the Marsh test, used for arsenic determination (from the reduction of arsenate () and arsenite () into arsine ()), hydrogen is generated by contacting zinc powder with hydrochloric acid.
So, hydrogen can be conveniently produced at low or high pH, according to the volatility of the species to be detected. Acid conditions in the Marsh test promote the fast escape of the arsine gas (AsH), while under hyperalkaline solution, the degassing of the reduced ammonia (NH) is greatly facilitated (the ammonium ion being soluble in aqueous solution under acidic conditions). | 0 | Theoretical and Fundamental Chemistry |
In metal processing, a reducing atmosphere is used in annealing ovens for relaxation of metal stresses without corroding the metal. A non-oxidizing gas, usually nitrogen or argon, is typically used as a carrier gas so that diluted amounts of reducing gases may be used. Typically, this is achieved through using the combustion products of fuels and tailoring the ratio of CO:CO. However, other common reducing atmospheres in the metal processing industries consist of dissociated ammonia, vacuum, and/or direct mixing of appropriately pure gases of N, Ar, and H.
A reducing atmosphere is also used to produce specific effects on ceramic wares being fired. A reduction atmosphere is produced in a fuel fired kiln by reducing the draft and depriving the kiln of oxygen. This diminished level of oxygen causes incomplete combustion of the fuel and raises the level of carbon inside the kiln. At high temperatures the carbon will bond with and remove the oxygen in the metal oxides used as colorants in the glazes. This loss of oxygen results in a change in the color of the glazes because it allows the metals in the glaze to be seen in an unoxidized form. A reduction atmosphere can also affect the color of the clay body. If iron is present in the clay body, as it is in most stoneware, then it will be affected by the reduction atmosphere as well.
In most commercial incinerators, exactly the same conditions are created to encourage the release of carbon bearing fumes. These fumes are then oxidized in reburn tunnels where oxygen is injected progressively. The exothermic oxidation reaction maintains the temperature of the reburn tunnels. This system allows lower temperatures to be employed in the incinerator section, where the solids are volumetrically reduced. | 1 | Applied and Interdisciplinary Chemistry |
Heat-shrinkable means just that, heat them up and they shrink, or more correctly, they recover in length. A heat-shrinkable sleeve starts out with a thick extruded poly olefin sheet (polyethylene or polypropylene) that is formulated to be cross-linkable. After extruding the thick sheet, it is taken to the "beam" where it is passed under a unit that subjects the sheet to electron irradiation. The irradiation process cross-links the polyolefin. This improves the molecular structure such that the polyolefin will work as part of a heat-shrinkable sleeve and provide the required level of mechanical protection while in-service. It makes the polyolefin perform more like a tough, heat-resistant, elastic material or rubber, rather than like a plastic material.
After cross-linking, the sheet is stretched by feeding it into a machine that heats it up, stretches it and cools it down. Because the sheet has been cross-linked, after stretching, it will want to recover to its original length when re-heated.
In recent years, many manufacturers had already developed their technologies of extruding and expansion of polyolefin backing. In the past, the production process of backing was done by extruding, cross-linking and expansion. However, in order to increase the production efficiency, some of manufacturers expand the backing during extruding, and then send the backing to e-beam for the cross-linking process. | 1 | Applied and Interdisciplinary Chemistry |
A random-coil conformation can be detected using spectroscopic techniques. The arrangement of the planar amide bonds results in a distinctive signal in circular dichroism. The chemical shift of amino acids in a random-coil conformation is well known in nuclear magnetic resonance (NMR). Deviations from these signatures often indicates the presence of some secondary structure, rather than complete random coil. Furthermore, there are signals in multidimensional NMR experiments that indicate that stable, non-local amino acid interactions are absent for polypeptides in a random-coil conformation. Likewise, in the images produced by crystallography experiments, segments of random coil result simply in a reduction in "electron density" or contrast. A randomly coiled state for any polypeptide chain can be attained by denaturing the system. However, there is evidence that proteins are never truly random coils, even when denatured (Shortle & Ackerman). | 0 | Theoretical and Fundamental Chemistry |
The Sentmanat extensional rheometer (SER) is actually a fixture that can be field installed on shear rheometers. A film of polymer is wound on two rotating drums, which apply constant or variable strain rate extensional deformation on the polymer film. The stress is determined from the torque exerted by the drums. | 1 | Applied and Interdisciplinary Chemistry |
The radical-pair is characterized as triplet or singlet by the spin state of the two lone electrons, paired together. The spin relationship is such that the two unpaired electrons, one in each radical molecule, may have opposite spin (singlet; anticorrelated), or the same spin (triplet; correlated). The singlet state is called such because there is only one way for the electrons’ spins to anticorrelate (S), whereas the triplet state is called such because the electron's spin may be correlated in three different fashions, denoted T, T, and T. | 0 | Theoretical and Fundamental Chemistry |
It has been proposed that oxidative stress may play a major role in determining cardiac complications in COVID-19. | 1 | Applied and Interdisciplinary Chemistry |
Galvanic phenomena were described in the literature before it was understood that they were of an electrical nature. In 1752, when the Swiss mathematician and physicist Johann Georg Sulzer placed his tongue between a piece of lead and a piece of silver, joined at their edges, he perceived a taste similar to that of iron(II) sulfate. Neither of the metals alone produced this taste. He realized that the contact between the metals probably did not produce a solution of either on the tongue. He did, however, not realize that this was an electrical phenomenon. He concluded that the contact between the metals caused their particles to vibrate, producing this taste by stimulating the nerves of the tongue. | 0 | Theoretical and Fundamental Chemistry |
Grasselli Brown serves on the boards of numerous non-profit organizations such as the Cleveland Hungarian Development Panel, the Cleveland Orchestra, the Great Lakes Science Center, the Cleveland Clinic Foundation, Breakthru, the Holden Arboretum, Martha Holden Jennings Foundation, Musical Arts Association of the Cleveland Orchestra, One Community, IdeaStream, the Cleveland Scholarship Programs, Inc., and the Northeastern Ohio Science and Engineering Fair. | 0 | Theoretical and Fundamental Chemistry |
Andersen was awarded many Visiting Professorships around the world, including appointments in Sevilla, Lyon, Montpellier, New South Wales, and Zurich. He was also an Alexander von Humboldt Professor in various locations in Germany (1994). Andersen was also a member of the Royal Chemical Society, American Chemical Society, and Sigma Xi. | 0 | Theoretical and Fundamental Chemistry |
The GRE subject test in chemistry is a standardized test in the United States created by the Educational Testing Service, and is designed to assess a candidate's potential for graduate or post-graduate study in the field of chemistry. It contains questions from many fields of chemistry. 15% of the questions will come from analytical chemistry, 25% will come from inorganic chemistry, 30% will come from organic chemistry and 30% will come from physical chemistry.
This exam, like all the GRE subject tests, is paper-based, as opposed to the GRE general test which is usually computer-based. It contains 130 questions, which are to be answered within 2 hours and 50 minutes. Scores on this exam are sometimes required for entrance to chemistry Ph.D. programs in the United States.
Scores are scaled and then reported as a number between 200 and 990; however, in recent versions of the test, the maximum and minimum reported scores have been 940 (corresponding to the 99 percentile) and 460 (1 percentile) respectively. The mean score for all test takers from July, 2009, to July, 2012, was 703 with a standard deviation of 115.
Tests generally take place three times per year, on one Saturday in each of September, October, and April. Students must register for the exam approximately five weeks before the administration.
The test was discontinued following the April 2023 administration. | 1 | Applied and Interdisciplinary Chemistry |
Many engineering disciplines engage in green engineering. This includes sustainable design, life cycle analysis (LCA), pollution prevention, design for the environment (DfE), design for disassembly (DfD), and design for recycling (DfR). As such, green engineering is a subset of sustainable engineering.
Green engineering involves four basic approaches to improve processes and products to make them more efficient from an environmental standpoint.
# Waste reduction;
# Materials management;
# Pollution prevention; and,
# Product enhancement.
Green engineering approaches design from a systematic perspective which integrates numerous professional disciplines. In addition to all engineering disciplines, green engineering includes land use planning, architecture, landscape architecture, and other design fields, as well as the social sciences(e.g. to determine how various groups of people use products and services. Green engineers are concerned with space, the sense of place, viewing the site map as a set of fluxes across the boundary, and considering the combinations of these systems over larger regions, e.g. urban areas.
The life cycle analysis is an important green engineering tool, which provides a holistic view of the entirety of a product, process or activity, encompassing raw materials, manufacturing, transportation, distribution, use, maintenance, recycling, and final disposal. Assessing its life cycle should yield a complete picture of the product. The first step in a life cycle assessment is to gather data on the flow of a material through an identifiable society. Once the quantities of various components of such a flow are known, the important functions and impacts of each step in the production, manufacture, use, and recovery/disposal are estimated. In sustainable design, engineers must optimize for variables that give the best performance in temporal frames.
The system approach employed in green engineering is similar to value engineering (VE). Daniel A. Vallero has compared green engineering to be a form of VE because both systems require that all elements and linkages within the overall project be considered to enhance the value of the project. Every component and step of the system must be challenged. Ascertaining overall value is determined not only be a project's cost-effectiveness, but other values, including environmental and public health factors. Thus, the broader sense of VE is compatible with and can be identical to green engineering, since VE is aimed at effectiveness, not just efficiency, i.e. a project is designed to achieve multiple objectives, without sacrificing any important values. Efficiency is an engineering and thermodynamic term for the ratio of an input to an output of energy and mass within a system. As the ratio approaches 100%, the system becomes more efficient. Effectiveness requires that efficiencies be met for each component, but also that the integration of components lead to an effective, multiple value-based design.
Green engineering is also a type of concurrent engineering, since tasks must be parallelized to achieve multiple design objectives. | 1 | Applied and Interdisciplinary Chemistry |
This is when a mesocrystal is formed by filling organic matrix compartments with crystalline matter. This crystalline matter would be oriented by the organic matrix. This is the process of biomineralization and this is how mesocrystals are produced in nature. | 0 | Theoretical and Fundamental Chemistry |
A refrigeration cycle, also known as heat pump, is a thermodynamic cycle that allows the removal of heat from a low temperature heat source and the rejection of heat into a high temperature heat source, thanks to mechanical power consumption. Traditional refrigeration cycles are subcritical, with the high pressure side (where heat rejection occurs) below the critical pressure.
Innovative transcritical refrigeration cycles, instead, should use a working fluid whose critical temperature is around the ambient temperature. For this reason, carbon dioxide is chosen due to its favourable critical conditions. In fact, the critical point of carbon dioxide is 31°C, reasonably in between the hot source and cold source of traditional refrigeration applications, thus suitable for a transcritical applications.
In transcritical refrigeration cycles the heat is dissipated through a gas cooler instead of a desuperheater and a condenser like in subcritical cycles. This limits the plant components, plant complexity and costs of the power block.
The advantages of using supercritical carbon dioxide as working fluid, instead of traditional refrigerant fluids (like HFC of HFO), in refrigeration cycles is represented both by economic aspects and environmental ones. The cost of carbon dioxide is two order of magnitude lower than the ones of the average refrigerant working fluid and the environmental impact of carbon dioxide is very limited (with a GWP of 1 and an ODP of 0), the fluid is not reactive nor significantly toxic. No other working fluids for refrigeration is able to reach the same environmental favourable characteristics of carbon dioxide. | 0 | Theoretical and Fundamental Chemistry |
The most common effect is fatigue or somnolence, particularly in older adults, although patients with pre-existing daytime sleepiness and fatigue may experience paradoxical improvement of these symptoms.
Escitalopram has not been shown to affect serial reaction time, logical reasoning, serial subtraction, multitask, or Mackworth Clock task performance. | 0 | Theoretical and Fundamental Chemistry |
Primer walking is an example of directed sequencing because the primer is designed from a known region of DNA to guide the sequencing in a specific direction. In contrast to directed sequencing, shotgun sequencing of DNA is a more rapid sequencing strategy.
There is a technique from the "old time" of genome sequencing. The underlying method for sequencing is the Sanger chain termination method which can have read lengths between 100 and 1000 basepairs (depending on the instruments used). This means you have to break down longer DNA molecules, clone and subsequently sequence them. There are two methods possible.
The first is called chromosome (or primer) walking and starts with sequencing the first piece. The next (contiguous) piece of the sequence is then sequenced using a primer which is complementary to the end of the first sequence read and so on. This technique doesn't require much assembling, but you need a lot of primers and it is relatively slow.
To overcome this problem the shotgun sequencing method was developed. Here the DNA is broken into different pieces (not all broken at the same place), cloned and sequenced with primers specific for the vector used for cloning. This leads to overlapping sequences which then have to be assembled into one sequence on the computer. This method allows for the parallelization of the sequencing (you can prepare a lot of sequencing reactions at the same time and run them) which makes the process much faster and also avoids the need for sequence specific primers. The challenge is to organize sequences into their order, as overlaps are not as clear here. To resolve this problem, a first draft is made and then critical regions are resequenced using other techniques such as primer walking. | 1 | Applied and Interdisciplinary Chemistry |
Several Bioconductor packages, for the R software, provide the facility for creating MA plots. These include affy (ma.plot, mva.pairs), limma (plotMA), marray (maPlot), and edgeR(maPlot)
Similar "RA" plots can be generated using the raPlot function in the caroline [https://cran.r-project.org/ CRAN] R package.
An interactive MA plot to filter genes by M, A and p-values, search by names or with a lasso, and save selected genes, is available as an R-Shiny code [https://github.com/alisheharyar/Enhanced_MA_Plot Enhanced-MA-Plot]. | 1 | Applied and Interdisciplinary Chemistry |
The three proteins that play a direct role in the M-cluster synthesis are NifH, NifEN, and NifB. The NifB protein is responsible for the assembly of the Fe-S core of the cofactor; a process that involves stitching together two [4Fe-4S] clusters. NifB belongs to the SAM (S-adenosyl-L-methionine) enzyme superfamily. During the biosynthesis of the FeMo cofactor, NifB and its SAM cofactor are directly involved in the insertion of a carbon atom at the center of the Fe-S complex. An equivalent of SAM donates a methyl group, which becomes the interstitial carbide of the M-cluster. The methyl group of SAM is mobilized by radical removal of an H by a 5’-deoxyadenosine radical (5’-dA·). Presumably, a transient –CH2· radical is formed that is subsequently incorporated into the metal cluster forming a Fe-carbide species. The interstitial carbon remains associated with the FeMo cofactor after insertion into the nitrogenase, The nature of the central atom in FeMoco as a carbon species was identified in 2011. The approach for the identification relied on a combination of C/N-labeling and pulsed EPR spectroscopy as well as X-ray christallographic studies at full atomic resolution. Additionally, X-ray diffractometry was used to verify that there was a central carbon atom in the middle of the FeMo cofactor and x-ray emission spectroscopic studies showed that central atom was carbon due to the 2p→1s carbon-iron transition. The use of X-ray crystallography showed that while the FeMo cofactor is not in its catalytic form, the carbon keeps the structure rigid which helps describe the reactivity of nitrogenase. | 0 | Theoretical and Fundamental Chemistry |
The process of N-linked glycosylation starts with the formation of dolichol-linked GlcNAc sugar. Dolichol is a lipid molecule composed of repeating isoprene units. This molecule is found attached to the membrane of the ER. Sugar molecules are attached to the dolichol through a pyrophosphate linkage (one phosphate was originally linked to dolichol, and the second phosphate came from the nucleotide sugar). The oligosaccharide chain is then extended through the addition of various sugar molecules in a stepwise manner to form a precursor oligosaccharide.
The assembly of this precursor oligosaccharide occurs in two phases: Phase I and II. Phase I takes place on the cytoplasmic side of the ER and Phase II takes place on the luminal side of the ER.
The precursor molecule, ready to be transferred to a protein, consists of 2 GlcNAc, 9 mannose, and 3 glucose molecules. | 0 | Theoretical and Fundamental Chemistry |
Stratification is commonly seen in the planetary sciences.
Solar energy passes as visible radiation through the air, and is absorbed by the ground, to be re-emitted as heat radiation. The lower atmosphere is therefore heated from below (UV absorption in the ozone layer heats that layer from within). Outdoor air is thus usually unstably stratified and convecting, giving us wind. Temperature inversions are a weather event which happens whenever an area of the lower atmosphere becomes stably-stratified and thus stops moving.
Oceans, on the other hand, are heated from above, and are usually stably stratified. Only near the poles does the coldest and saltiest water sink. The deep ocean waters slowly warm and freshen through internal mixing (a form of double diffusion), and then rise back to the surface.
Examples:
* Ocean stratification, the formation of water layers based on temperature and salinity in oceans
* Lake stratification, the formation of water layers based on temperature, with mixing in the spring and fall in seasonal climates.
* Atmospheric instability
* Atmospheric stratification, the dividing of the upper reaches of the Earth's atmosphere into stably-stratified layers
* Atmospheric circulation, caused by the unstable stratification of the atmosphere
* Thermohaline circulation, circulation in the oceans despite stable stratification.
* Stratified flows (such as the flow through the Straits of Gibraltar) | 1 | Applied and Interdisciplinary Chemistry |
In the presence of an appropriate transition metal (typically copper or rhodium), α-diazocarbonyl compounds are converted to transition metal carbenes, which undergo addition reactions in the presence of carbon–carbon double bonds to form cyclopropanes. Insertion into carbon–carbon or carbon–hydrogen bonds is possible in substrates lacking a double bond. The intramolecular version of this reaction forms fused carbocycles, although yields of reactions mediated by copper are typically moderate. For enantioselective cyclopropanations and insertions, both copper- and rhodium-based catalysts are employed, although the latter have been more heavily studied in recent years. | 0 | Theoretical and Fundamental Chemistry |
Signal amplification by reversible exchange (SABRE) is a technique to hyperpolarize samples without chemically modifying them. Compared to orthohydrogen or organic molecules, a much greater fraction of the hydrogen nuclei in parahydrogen align with an applied magnetic field. In SABRE, a metal center reversibly binds to both the test molecule and a parahydrogen molecule facilitating the target molecule to pick up the polarization of the parahydrogen. This technique can be improved and utilized for a wide range of organic molecules by using an intermediate "relay" molecule like ammonia. The ammonia efficiently binds to the metal center and picks up the polarization from the parahydrogen. The ammonia then transfers it other molecules that don't bind as well to the metal catalyst. This enhanced NMR signal allows the rapid analysis of very small amounts of material. | 0 | Theoretical and Fundamental Chemistry |
The copolymerization of ethylene with polar monomers has been heavily studied. The high oxophilicity of the early metals precluded their use in this application.
Efforts to copolymerize polar comonomers led to catalysts based upon nickel and palladium, inspired by the success of the Shell Higher Olefin Process. Typical post-metallocene catalysts feature bulky, neutral, alpha-diimine ligands. DuPont commercialized the Versipol olefin polymerization system. Eastman commercialized the related Gavilan technology. These complexes catalyze the homopolymerize ethylene to a variety of structures that range from high density polyethylene through hydrocarbon plastomers and elastomers by a mechanism referred to as “chain-walking”. By modifying the bulk of the alpha-diimine, the product distribution of these systems can be tuned to consist of hydrocarbon oils (alpha-olefins), similar to those produced by more tradition nickel(II) oligo/polymerization catalysts. As opposed to metallocenes, they can also randomly copolymerize ethylene with polar comonomers such as methyl acrylate.
A second class of catalysts feature mono-anionic bidentate ligands related to salen ligands. and DuPont.
The concept of bulky bis-imine ligands was extended to iron complexes Representative catalysts feature diiminopyridine ligands. These catalysts are highly active but do not promote chain walking. The give very linear high-density polyethylene when bulky and when the steric bulk is removed, they are very active for ethylene oligomerization to linear alpha-olefins.
A salicylimine catalyst system based on zirconium exhibits high activity for ethylene polymerization. The catalysts can also produce some novel polypropylene structures. Despite intensive efforts, few catalysts have been successfully commercialized for the copolymerization of polar monomers. | 0 | Theoretical and Fundamental Chemistry |
Drago's research covered both the theoretical and practical side of acid-base chemistry. He developed the E and C equation as a quantitative model for acid-base reactions. His group used a variety of physical methods to probe intermolecular interactions and helped pioneer NMR studies of paramagnetic systems. He contributed to the area of catalysis focusing primarily on chemical processes relevant to industrial applications. Work in this field contributed significantly to the understanding of ligand – metal and metal – metal interactions and their influence on the mechanisms, activity, and selectivity of numerous transition metals catalyzed systems.
A video interview with Drago is available. | 0 | Theoretical and Fundamental Chemistry |
Not all cells undergo a complete EMT, i.e. losing their cell-cell adhesion and gaining solitary migration characteristics. Instead, most cells undergo partial EMT, a state in which they retain some epithelial traits such as cell-cell adhesion or apico-basal polarity, and gain migratory traits, thus cells in this hybrid epithelial/mesenchymal (E/M) phenotype are endowed with special properties such as collective cell migration. Single-cell tracking contributes to enabling the visualization of morphological transitions during EMT, the discernment of cell migration phenotypes, and the correlation of the heritability of these traits among sister cells. Two mathematical models have been proposed, attempting to explain the emergence of this hybrid E/M phenotype, and its highly likely that different cell lines adopt different hybrid state(s), as shown by experiments in MCF10A, HMLE and H1975 cell lines. Although a hybrid E/M state has been referred to as metastable or transient, recent experiments in H1975 cells suggest that this state can be stably maintained by cells. | 1 | Applied and Interdisciplinary Chemistry |
Eletrospraying is used to create alginate spheres by pumping an alginate solution through a needle. A source of high voltage usually provided by a clamp attached to the needle is used to generate an electric potential with the alginate falling from the needle tip into a solution that contains a ground. Calcium chloride is used as cross linking solution in which the generated capsules drop into where they harden after approximately 30 minutes. Beads are formed from the needle due to charge and surface tension.
* Size dependency of the beads
** height alterations of device from needle to calcium chloride solution
** voltage alterations of clamp on the needle
** alginate concentration alterations | 1 | Applied and Interdisciplinary Chemistry |
Blast waves cause damage by a combination of the significant compression of the air in front of the wave (forming a shock front) and the subsequent wind that follows. A blast wave travels faster than the speed of sound and the passage of the shock wave usually lasts only a few milliseconds. Like other types of explosions, a blast wave can also cause damage to things and people by the blast wind, debris, and fires. The original explosion will send out fragments that travel very fast. Debris and sometimes even people can get swept up into a blast wave, causing more injuries such as penetrating wounds, impalement and broken bones. The blast wind is the area of low pressure that causes debris and fragments to rush back towards the original explosions. The blast wave can also cause fires or secondary explosions by a combination of the high temperatures that result from detonation and the physical destruction of fuel-containing objects. | 1 | Applied and Interdisciplinary Chemistry |
Delafontaine studied with Jean Charles Galissard de Marignac at the University of Geneva. He also worked at the University of Geneva.
Delafontaine moved to the United States of America, arriving in New York in 1870, and later becoming a naturalized citizen.
He taught in Chicago, Illinois at city high schools, and at a women's college.
He also worked as an analytical chemist with the
Chicago Police Department. | 1 | Applied and Interdisciplinary Chemistry |
From 1907 onward, Charles Moureu was a professor of chemical pharmacy at the École supérieure de Pharmacie in Paris. In 1913 he was named director of the laboratory of hydrological physical chemistry at the École pratique des hautes études.
He became a member of the Académie Nationale de Médecine (from 1907), Académie des sciences (from 1911) and Académie nationale de pharmacie (president 1913).
After the use of poison gas against French troops in the Second Battle of Ypres on April 22, 1915, Charles Moureu was appointed vice-chairman of France's Committee for Gas Warfare. Moreu headed the Section des produits agressifs (Aggressive Products Section). In this role, he was responsible for 16 chemistry laboratories in Paris, supervising and coordinating their work until 1918. He was also involved in conferences of the allied powers in September 1917, March
1918, and October 1918.
In 1917 Charles Moureu was appointed professor of organic chemistry at the Collège de France. Succeeding Émile Jungfleisch, Moureu was the only professor to be appointed to the college during the first world war.
Moureu supported initiatives for international cooperation and standardization among chemists. He served as a vice-president of the Société chimique de France (SCF) in 1910.
Moureu was active in the restructuring of chemical organizations in 1918–1919. The Allied Conference of Academies formally dissolved the International Association of Chemical Societies (IACS), as of July 22, 1919. Moureu was the founding President of the International Union of Pure and Applied Chemistry (IUPAC), holding the position from 1920 to 1922. He also supported the establishment of the Maison de la chimie in Paris as an international center for chemists.
In 1921 and 1922, Moureu visited the United States as a scientific expert. In 1921 he was part of a French Mission on Disarmament.
In 1922, he visited Washington, D.C. for discussions on the use of gas in warfare. He visited a number of universities in the United States and Canada, and was given an honorary degree by the University of Montreal.
Moureu became chairman of the French Committee of National Defence when it was established in 1925, leading it until his death in 1929. | 0 | Theoretical and Fundamental Chemistry |
The presence of chlorides to the steel surface, above a certain critical amount, can locally break the protective thin film of oxides on the steel surface, even if concrete is still alkaline, causing a very localized and aggressive form of corrosion known as pitting. Current regulations forbid the use of chloride contaminated raw materials, therefore one factor influencing the initiation time is chloride penetration rate from the environment. This is a complex task, because chloride solutions penetrate in concrete through the combination of several transport phenomena, such as diffusion, capillary effect and hydrostatic pressure. Chloride binding is another phenomenon affecting the kinetic of chloride penetration. Part of the total chloride ions can be absorbed or can chemically react with some constituents of the cement paste, leading to a reduction of chlorides in the pore solution (free chlorides that are steel able to penetrate in concrete). The ability of a concrete to chloride binding is related to the cement type, being higher for blended cements containing silica fume, fly ash or furnace slag.
Being the modelling of chloride penetration in concrete particularly complex, a simplified correlation is generally adopted, which was firstly proposed by Collepardi in 1972
Where is the chloride concentration at the exposed surface, x is the chloride penetration depth, D is the chloride diffusion coefficient, and t is time.
This equation is a solution of Fick's II law of diffusion in the hypothesis that chloride initial content is zero, that is constant in time on the whole surface, and D is constant in time and through the concrete cover. With and D known, the equation can be used to evaluate the temporal evolution of the chloride concentration profile in the concrete cover and evaluate the initiation time as the moment in which critical chloride threshold () is reached at the depth of steel rebar.
However, there are many critical issues related to the practical use of this model. For existing reinforced concrete structures in chloride-bearing environment and D can be identified calculating the best-fit curve for measured chloride concertation profiles. From concrete samples retrieved on field is therefore possible to define the values of C and D for residual service life evaluation.
On the other hand, for new structures it is more complicated to define and D. These parameters depend on the exposure conditions, the properties of concrete such as porosity (and therefore w/c ratio and curing process) and type of cement used. Furthermore, for the evaluation of long-term behaviour of structure, a critical issue is related to the fact that and D can not be considered constant in time, and that the transport penetration of chlorides can be considered as pure diffusion only for submerged structures.
A further issue is the assessment of . There are various influencing factors, such as are the potential of steel rebar and the pH of the solution included in concrete pores. Moreover, pitting corrosion initiation is a phenomenon with a stochastic nature, therefore also can be defined only on statistical basis. | 1 | Applied and Interdisciplinary Chemistry |
Viruses (i.e., measles, mumps, or parainfluenza), especially viruses that have an RNA genome, have been shown to have evolved to utilize RNA modifications in many ways when taking over the host cell. Viruses are known to utilize the RNA modifications in different parts of their infection cycle from immune evasion to protein translation enhancement. RNA editing is used for stability and generation of protein variants. Viral RNAs are transcribed by a virus-encoded RNA-dependent RNA polymerase, which is prone to pausing and "stuttering" at certain nucleotide combinations. In addition, up to several hundred non-templated As are added by the polymerase at the 3 end of nascent mRNA. These As help stabilize the mRNA. Furthermore, the pausing and stuttering of the RNA polymerase allows the incorporation of one or two Gs or As upstream of the translational codon. The addition of the non-templated nucleotides shifts the reading frame, which generates a different protein.
Additionally, the RNA modifications are shown to have both positive and negative effects on the replication and translation efficiency depending on the virus. For example, Courtney et al. showed that an RNA modification called 5-methylcytosine is added to the viral mRNA in infected host cells in order to enhance the protein translation of HIV-1 virus. The inhibition of the mC modification on viral mRNA results in significant reduction in viral protein translation, but interestingly it has no effect on the expression of viral mRNAs in the cell. On the other hand, Lichinchi et al. showed that the N6-methyladenosine modification on ZIKV mRNA inhibits the viral replication. | 1 | Applied and Interdisciplinary Chemistry |
In the early 20th century, chemists observed that various aromatic hydrocarbons in the presence of oxygen could absorb wavelength specific light to generate a peroxide species. This discovery of oxygen's reduction by a photosensitizer led to chemists studying photosensitizers as photoredox catalysts for their roles in the catalysis of pericyclic reactions and other reduction and oxidation reactions. Photosensitizers in synthetic chemistry allow for the manipulation of electronic transitions within molecules through an externally applied light source. These photosensitizers used in redox chemistry may be organic, organometallic, or nanomaterials depending on the physical and spectral properties required for the reaction. | 0 | Theoretical and Fundamental Chemistry |
The Chesapeake Bay is already experiencing the effects of climate change. Key among these is sea level rise: water levels in the bay have already risen one foot, with a predicted increase of 1.3 to 5.2 feet in the next 100 years. This has related environmental effects, causing changes in marine ecosystems, destruction of coastal marshes and wetlands, and intrusion of saltwater into otherwise brackish parts of the bay. Sea level rise also compounds the effects of extreme weather on the bay, making coastal flooding as part of the events more extreme and increasing runoff from upstream in the watershed.
With increases in flooding events and sea level rise, the 11,600 miles of coastline, which include significant historic buildings and modern infrastructure, will be at risk of erosion. Islands such as Holland Island have disappeared due to the rising sea levels.
Beyond sea level rise, other changes in the marine ecosystem due to climate change, such as ocean acidification and temperature increases, will put increasing pressure on marine life. Projected effects include decreasing dissolved oxygen, more acidic waters making it harder for shellfish to maintain shells and changing the seasonal cycles important for breeding and other lifecycle activities. Seasonal shifts and warmer temperatures also mean that there is a greater likelihood of pathogens to stay active in the ecosystem.
Climate change may worsen hypoxia. However, compared to the current effects of nutrient pollution and algal blooms, climate change’s effect to increase hypoxia is relatively small. Warmer waters can hold less dissolved oxygen. Therefore, as the Bay warms, there may be a longer duration of hypoxia each summer season in the deep central channel of the Bay. However, comparing the effects of climate change and nutrient pollution, reduced nutrient pollution would increase oxygen concentrations more dramatically than if climate change were to level out.
Climate change adaptation and mitigation programs in Maryland and Virginia often include significant programs to address the communities in the Chesapeake Bay. Key infrastructure in Virginia, such as the port of Norfolk, and major agriculture and fishing industries of the Eastern Shore of Maryland will be directly impacted by the changes in the Bay. | 1 | Applied and Interdisciplinary Chemistry |
Alkenes that are particularly amenable to asymmetric hydrogenation often feature a polar functional group adjacent to the site to be hydrogenated. In the absence of this functional group, catalysis often results in low ees. For some unfunctionalized olefins, iridium with P,N'-based ligands) have proven effective, however. Alkene substrates are often classified according to their substituents, e.g., 1,1-disubstituted, 1,2-diaryl trisubstituted, 1,1,2-trialkyl and tetrasubstituted olefins. and even within these classes variations may exist that make different solutions optimal.
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Conversely to the case of olefins, asymmetric hydrogenation of enamines has favoured diphosphine-type ligands; excellent results have been achieved with both iridium- and rhodium-based systems. However, even the best systems often suffer from low ee's and a lack of generality. Certain pyrrolidine-derived enamines of aromatic ketones are amenable to asymmetrically hydrogenation with cationic rhodium(I) phosphonite systems, and I and acetic acid system with ee values usually above 90% and potentially as high as 99.9%. A similar system using iridium(I) and a very closely related phosphoramidite ligand is effective for the asymmetric hydrogenation of pyrrolidine-type enamines where the double bond was inside the ring: in other words, of dihydropyrroles. In both cases, the enantioselectivity dropped substantially when the ring size was increased from five to six. | 0 | Theoretical and Fundamental Chemistry |
Pseudoephedrine is a stimulant, but it is well known for shrinking swollen nasal mucous membranes, so it is often used as a decongestant. It reduces tissue hyperemia, edema, and nasal congestion commonly associated with colds or allergies. Other beneficial effects may include increasing the drainage of sinus secretions, and opening of obstructed Eustachian tubes. The same vasoconstriction action can also result in hypertension, which is a noted side effect of pseudoephedrine.
Pseudoephedrine can be used either as oral or as topical decongestant. Due to its stimulating qualities, however, the oral preparation is more likely to cause adverse effects, including urinary retention. According to one study, pseudoephedrine may show effectiveness as an antitussive drug (suppression of cough).
Pseudoephedrine is indicated for the treatment of nasal congestion, sinus congestion, and Eustachian tube congestion. Pseudoephedrine is also indicated for vasomotor rhinitis, and as an adjunct to other agents in the optimum treatment of allergic rhinitis, croup, sinusitis, otitis media, and tracheobronchitis.
Pseudoephedrine is also used as a first-line prophylactic for recurrent priapism. Erection is largely a parasympathetic response, so the sympathetic action of pseudoephedrine may serve to relieve this condition. Treatment for urinary incontinence is an off-label use ("unlabeled use") for these medications. | 0 | Theoretical and Fundamental Chemistry |
In a fast neutron reactor, the minor actinides produced by neutron capture of uranium and plutonium can be used as fuel. Metal actinide fuel is typically an alloy of zirconium, uranium, plutonium, and minor actinides. It can be made inherently safe as thermal expansion of the metal alloy will increase neutron leakage. | 0 | Theoretical and Fundamental Chemistry |
In common usage the terms "ring" and "ring system" are frequently interchanged, with the appropriate definition depending upon context. Typically a "ring" denotes a simple ring, unless otherwise qualified, as in terms like "polycyclic ring", "fused ring", "spiro ring" and "indole ring", where clearly a polycyclic ring system is intended. Likewise, a "ring system" typically denotes a polycyclic ring system, except in terms like "monocyclic ring system" or "pyridine ring system". To reduce ambiguity, IUPAC's recommendations on organic nomenclature avoid the use of the term "ring" by using phrases such as "monocyclic parent" and "polycyclic ring system". | 0 | Theoretical and Fundamental Chemistry |
Docosatetraenoylethanolamide (DEA) (Adrenoyl-ethanolamide) (Adrenoyl-EA) is an endogenous ethanolamide that has been shown to act on the cannabinoid (CB) receptor. DEA is similar in structure to anandamide (AEA, a recognized endogenous ligand for the CB receptor), containing docosatetraenoic acid in place of arachidonic acid. While DEA has been shown to bind to the CB receptor with similar potency and efficacy as AEA, its role as a cannabinergic neurotransmitter is not well understood.
Docosatetraenoylethanolamide (DEA) has been found in Tropaeolum tuberosum (Mashua) and Leonotis leonurus (Wild Dagga / Lion's Tail). | 1 | Applied and Interdisciplinary Chemistry |
Several gene families are involved in the processes of hyperaccumulation including upregulation of absorption and sequestration of heavy metal metals. These hyperaccumulation genes (HA genes) are found in over 450 plant species, including the model organisms Arabidopsis and Brassicaceae. The expression of such genes is used to determine whether a species is capable of hyperaccumulation. Expression of HA genes provides the plant with capacity to uptake and sequester metals such as As, Co, Fe, Cu, Cd, Pb, Hg, Se, Mn, Zn, Mo and Ni in 100–1000x the concentration found in sister species or populations.
The ability to hyperaccumulate is determined by two major factors: environmental exposure and the expression of ZIP gene family.
Although experiments have shown that the hyperaccumulation is partially dependent on environmental exposure (i.e. only plants exposed to metal are observed with high concentrations of that metal), hyperaccumulation is ultimately dependent on the presence and upregulation of genes involved with that process. It has been shown that hyperaccumulation capacities can be inherited in Thlaspi caerulescens (Brassicaceae) and others. As there is a wide variety among hyperaccumulating species that span across different plant families, it is likely that HA genes were eco typically selected for.
In most hyperaccumulating plants, the main mechanism for metal transport are the proteins coded by genes in the ZIP family, however other families such as the HMA, MATE, YSL and MTP families have also been observed to be involved. The ZIP gene family is a novel, plant-specific gene family that encodes Cd, Mn, Fe and Zn transporters. The ZIP family plays a role in supplying Zn to metalloproteins.
In one study on Arabidopsis, it was found that the metallophyte Arabidopsis halleri expressed a member of the ZIP family that was not expressed in a non-metallophyte sister species. This gene was an iron regulated transporter (IRT-protein) that encoded several primary transporters involved with cellular uptake of cations above the concentration gradient. When this gene was transformed into yeast, hyperaccumulation was observed. This suggests that overexpression of ZIP family genes that encode cation transporters is a characteristic genetic feature of hyperaccumulation.
Another gene family that has been observed ubiquitously in hyperaccumulators are the ZTP and ZNT families. A study on T. caerulescens identified the ZTP family as a plant specific family with high sequence similarity to other zinc transporter4. Both the ZTP and ZNT families, like the ZIP family, are zinc transporters. It has been observed in hyperaccumulating species, that these genes, specifically ZNT1 and ZNT2 alleles are chronically overexpressed.
While the precise mechanism by which these genes facilitate hyperaccumulation is unknown, expression patterns strongly correlate with individual hyperaccumulation capacity and metal exposure, implying that these gene families play a regulatory role. Because the presence and expression of zinc transporter gene families are highly prevalent in hyperaccumulators, the ability to accumulate a diverse range of heavy metals is most likely due to the zinc transporters inability to discriminate against specific metal ions. The response of the plants to hyperaccumulation of any metal also supports this theory as it has been observed that AhHMHA3 is expressed in hyperaccumulating individuals. AhHMHA3 has been identified to be expressed in response to and aid of Zn detoxification. In another study, using metallophytic and non-metallophytic Arabidopsis' populations, back crosses indicated pleiotropy between Cd and Zn tolerances. This response suggests that plants are unable to detect specific metals, and that hyperaccumulation is likely a result of an overexpressed Zn transportation system.
The overall effect of these expression patterns has been hypothesized to assist in plant defense systems. In one hypothesis, "the elemental defense hypothesis", provided by Poschenrieder, it is suggested that the expression of these genes assist in antiherbivory or pathogen defenses by making tissues toxic to organisms attempting to feed on that plant. Another hypothesis, "the joint hypothesis", provided by Boyd, suggests that expression of these genes assists in systemic defense. | 1 | Applied and Interdisciplinary Chemistry |
DCvC has been used to make molecules with complex topological properties. In the case of Borromean rings, DCvC is used to synthesize a three ring interlocking system. Thermodynamic templates are used to stabilize interlocking macrocycle growth. | 0 | Theoretical and Fundamental Chemistry |
Optimal conditions for enantio-selective nucleophilic epoxidation depend on the substrate employed. Although a variety of substrates may be epoxidized using nucleophilic methods, each particular method tends to have limited substrate scope. This section describes asymmetric nucleophilic epoxidation methods, organizing them according to the constitution and configuration of the unsaturated substrate. | 0 | Theoretical and Fundamental Chemistry |
Although intelectins require calcium ion for function, the sequences bear no resemblance to C-type lectins. In addition, merely around 50 amino acids (the fibronogen-like domain) align with any known protein, specifically the ficolin family. The first structural details of an intelectin comes from the crystal structure of selenomethionine-labeled XEEL carbohydrate-recognition domain (Se-Met XEEL-CRD) solved by Se-SAD. XEEL-CRD was expressed and Se-Met-labeled in High Five insect cells using a recombinant baculovirus. The fibrinogen-like fold is conserved despite amino acid sequence divergence. However, extensive insertions are present in intelectin compared to ficolins, thus making intelectin a distinct lectin structural class. The Se-Met XEEL-CRD structure then enables the structure solution by molecular replacement of D-glycerol 1-phosphate (GroP)-bound XEEL-CRD, apo-human intelectin-1 (hIntL-1), and galactofuranose-bound hIntL-1.
Each polypeptide chain of XEEL and hIntL-1 contains three bound calcium ions: two in the structural calcium site and one in the ligand binding site. The amino acid residues in the structural calcium site are conserved among intelectins, thus it is likely that most, if not all, intelectins have two structural calcium ions.
In the ligand binding site of XEEL and hIntL-1, the exocyclic vicinal diol of the carbohydrate ligand directly coordinates to the calcium ion. There are large variations in the ligand binding site residues among intelectin homologs suggesting that the intelectin family may have broad ligand specificities and biological functions. As there is no intelectin numbering conventions in different organisms, one should not assume functional homology based on the intelectin number. For example, hIntL-1 has glutamic acid residues in the ligand binding site to coordinate a calcium ion, while zebrafish intelectin-1 are devoided of these acidic residues. Zebrafish intelectin-2 ligand binding site residues are similar to those present in hIntL-1. | 1 | Applied and Interdisciplinary Chemistry |
Gitelson (1999) states, "The ratio between chlorophyll fluorescence at 735 nm and the wavelength range 700nm to 710 nm, F735/F700 was found to be linearly proportional to the chlorophyll content (with determination coefficient, r2, more than 0.95) and thus this ratio can be used as a precise indicator of chlorophyll content in plant leaves." | 0 | Theoretical and Fundamental Chemistry |
In conventional δO analysis, both the δO values in carbonates and water are needed to estimate paleoclimate. However, for many times and places, the δO in water can only be inferred, and also the O/O ratio between carbonate and water may vary with the change in temperature. Therefore, the accuracy of the thermometer may be compromised.
Whereas for the carbonate clumped-isotope thermometer, the equilibrium is independent of the isotope compositions of waters from which carbonates grew. Therefore, the only information needed is the abundance of bonds between rare, heavy isotopes within the carbonate mineral. | 0 | Theoretical and Fundamental Chemistry |
Metal amides (systematic name metal azanides) are a class of coordination compounds composed of a metal center with amide ligands of the form NR. Amido complexes of the parent amido ligand NH are rare compared to complexes with diorganylamido ligand, such as dimethylamido. Amide ligands have two electron pairs available for bonding. | 0 | Theoretical and Fundamental Chemistry |
One important characteristic of a crystalline structure is its atomic packing factor (APF). This is calculated by assuming that all the atoms are identical spheres, with a radius large enough that each sphere abuts on the next. The atomic packing factor is the proportion of space filled by these spheres which can be worked out by calculating the total volume of the spheres and dividing by the volume of the cell as follows:
Another important characteristic of a crystalline structure is its coordination number (CN). This is the number of nearest neighbours of a central atom in the structure.
The APFs and CNs of the most common crystal structures are shown below:
The 74% packing efficiency of the FCC and HCP is the maximum density possible in unit cells constructed of spheres of only one size. | 0 | Theoretical and Fundamental Chemistry |
Clathrates have been explored for many applications including: gas storage, gas production, gas separation, desalination, thermoelectrics, photovoltaics, and batteries.
* Clathrate compounds with formula ABX, where A is an alkaline earth metal, B is a group III element, and X is an element from group IV have been explored for thermoelectric devices. Thermoelectric materials follow a design strategy called the phonon glass electron crystal concept. Low thermal conductivity and high electrical conductivity is desired to produce the Seebeck Effect. When the guest and host framework are appropriately tuned, clathrates can exhibit low thermal conductivity, i.e., phonon glass behavior, while electrical conductivity through the host framework is undisturbed allowing clathrates to exhibit electron crystal.
* Methane clathrates feature the hydrogen-bonded framework contributed by water and the guest molecules of methane. Large amounts of methane naturally frozen in this form exist both in permafrost formations and under the ocean sea-bed. Other hydrogen-bonded networks are derived from hydroquinone, urea, and thiourea. A much studied host molecule is Dianin's compound.
* Hofmann clathrates are coordination polymers with the formula Ni(CN)·Ni(NH)(arene). These materials crystallize with small aromatic guests (benzene, certain xylenes), and this selectivity has been exploited commercially for the separation of these hydrocarbons. Metal organic frameworks (MOFs) form clathrates. | 0 | Theoretical and Fundamental Chemistry |
Peroxisomes are derived from the smooth endoplasmic reticulum under certain experimental conditions and replicate by membrane growth and division out of pre-existing organelles. Peroxisome matrix proteins are translated in the cytoplasm prior to import. Specific amino acid sequences (PTS or peroxisomal targeting signal) at the C-terminus (PTS1) or N-terminus (PTS2) of peroxisomal matrix proteins signals them to be imported into the organelle by a targeting factor. There are currently 36 known proteins involved in peroxisome biogenesis and maintenance, called peroxins, which participate in the process of peroxisome assembly in different organisms. In mammalian cells there are 13 characterized peroxins. In contrast to protein import into the endoplasmic reticulum (ER) or mitochondria, proteins do not need to be unfolded to be imported into the peroxisome lumen. The matrix protein import receptors, the peroxins PEX5 and PEX7, accompany their cargoes (containing a PTS1 or a PTS2 amino acid sequence, respectively) all the way to the peroxisome where they release the cargo into the peroxisomal matrix and then return to the cytosol – a step named recycling. A special way of peroxisomal protein targeting is called piggy backing. Proteins that are transported by this unique method do not have a canonical PTS, but rather bind on a PTS protein to be transported as a complex. A model describing the import cycle is referred to as the extended shuttle mechanism. There is now evidence that ATP hydrolysis is required for the recycling of receptors to the cytosol. Also, ubiquitination is crucial for the export of PEX5 from the peroxisome to the cytosol. The biogenesis of the peroxisomal membrane and the insertion of peroxisomal membrane proteins (PMPs) requires the peroxins PEX19, PEX3, and PEX16. PEX19 is a PMP receptor and chaperone, which binds the PMPs and routes them to the peroxisomal membrane, where it interacts with PEX3, a peroxisomal integral membrane protein. PMPs are then inserted into the peroxisomal membrane.
The degradation of peroxisomes is called pexophagy. | 1 | Applied and Interdisciplinary Chemistry |
Many cell assays have been developed to assess specific parameters or response of cells (biomarkers, cell physiology). Techniques used to study cells include :
*reporter assays using i.e. Luciferase, calcium signaling assays using Coelenterazine, CFSE or Calcein
*Immunostaining of cells on slides by Microscopy (ImmunoHistoChemistry or Fluorescence), on microplates by photometry including the ELISpot (and its variant FluoroSpot) to enumerate B-Cells or antigen-specific cells, in solution by Flow cytometry
*Molecular biology techniques such as DNA microarrays, in situ hybridization, combined to PCR, Computational genomics, and Transfection; Cell fractionation or Immunoprecipitation
*Migration assays, Chemotaxis assay
*Secretion assays
*Apoptosis assays such as the DNA laddering assay, the Nicoletti assay, caspase activity assays, and Annexin V staining
*Chemosensitivity assay measures the number of tumor cells that are killed by a cancer drug
*Tetramer assay detect the presence of antigen specific T-cells
*Gentamicin protection assay or survival assay or invasion assay to assess ability of pathogens (bacteria) to invade eukaryotic cells
Metastasis Assay | 1 | Applied and Interdisciplinary Chemistry |
Capnellene derivatives have recently been identified as possible treatments for neuropathic pain. Neuropathic pain is characterized by damage to peripheral or central nerves that results in pathological nociceptive transmission, the neuronal process that responds noxious stimuli. Two capnellene derivatives Δ-capnellene-8β,10α-diol and 8α-acetoxy-Δ-capnellene-10α-ol demonstrate potential as analgesics capable of attenuating neuropathic pain. These compounds have been shown in vivo to reduce two proteins that mediate inflammation, cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS). In vivo, Δ-capnellene-8β,10α-diol inhibited hyperalgesia behavior in the mouse model for neuropathic pain in a dose-dependent manner. Additionally, treatment with Δ-capnellene-8β,10α-diol inhibited the up-regulation of immunoreactivity in the mouse model, specifically targeting the production of COX-2. Unlike many non-steroidal anti-inflammatory drugs, Δ-capnellene-8β,10α-diol is advantageous in its selectivity for the COX isoenzyme COX-2, avoiding many of the gastrointestinal side effects associated with the inhibition of COX-1. This fact would allow for the administration of Δ-capnellene-8β,10α-diol in higher doses, potentially offering significant relief from neuropathic pain. | 0 | Theoretical and Fundamental Chemistry |
White light is directed vertically onto a multiple-layer system of a SiO, a high-refractive TaO and an additional SiO layer (this additional layer can be chemically modified). The partial beams of the white light are reflected at each phase boundary and then refracted (transmitted). These reflected partial beams superimpose which results in an interference spectrum that is detected using a diode array spectrometer.<br>
Through chemical modification the upper SiO layer is changed in a way to allow interaction with target molecules. This interaction causes a change in the thickness of the physical layer d and the refractive index n within this layer. The product of both defines the optical thickness of the layer: n • d.<br>
A change in the optical thickness results in a modulation of the interference spectrum. Monitoring this change over time allows to observe the binding behaviour of the target molecules. | 0 | Theoretical and Fundamental Chemistry |
Electroporation allows cellular introduction of large highly charged molecules such as DNA which would never passively diffuse across the hydrophobic bilayer core. This phenomenon indicates that the mechanism is the creation of nm-scale water-filled holes in the membrane. Electropores were optically imaged in lipid bilayer models like droplet interface bilayers and giant unilamellar vesicles, while addition of cytoskeletal proteins such as actin networks to the giant unilamellar vesicles seem to prevent the formation of visible electropores. Experimental evidences for actin networks in regulating the cell membrane permeability has also emerged. Although electroporation and dielectric breakdown both result from application of an electric field, the mechanisms involved are fundamentally different. In dielectric breakdown the barrier material is ionized, creating a conductive pathway. The material alteration is thus chemical in nature. In contrast, during electroporation the lipid molecules are not chemically altered but simply shift position, opening up a pore which acts as the conductive pathway through the bilayer as it is filled with water.
Electroporation is a dynamic phenomenon that depends on the local transmembrane voltage at each point on the cell membrane. It is generally accepted that for a given pulse duration and shape, a specific transmembrane voltage threshold exists for the manifestation of the electroporation phenomenon (from 0.5 V to 1 V). This leads to the definition of an electric field magnitude threshold for electroporation (E). That is, only the cells within areas where E≧E are electroporated. If a second threshold (E) is reached or surpassed, electroporation will compromise the viability of the cells, i.e., irreversible electroporation (IRE).
Electroporation is a multi-step process with several distinct phases. First, a short electrical pulse must be applied. Typical parameters would be 300–400 mV for < 1 ms across the membrane (note- the voltages used in cell experiments are typically much larger because they are being applied across large distances to the bulk solution so the resulting field across the actual membrane is only a small fraction of the applied bias). Upon application of this potential the membrane charges like a capacitor through the migration of ions from the surrounding solution. Once the critical field is achieved there is a rapid localized rearrangement in lipid morphology. The resulting structure is believed to be a "pre-pore" since it is not electrically conductive but leads rapidly to the creation of a conductive pore. Evidence for the existence of such pre-pores comes mostly from the "flickering" of pores, which suggests a transition between conductive and insulating states. It has been suggested that these pre-pores are small (~3 Å) hydrophobic defects. If this theory is correct, then the transition to a conductive state could be explained by a rearrangement at the pore edge, in which the lipid heads fold over to create a hydrophilic interface. Finally, these conductive pores can either heal, resealing the bilayer or expand, eventually rupturing it. The resultant fate depends on whether the critical defect size was exceeded which in turn depends on the applied field, local mechanical stress and bilayer edge energy. | 1 | Applied and Interdisciplinary Chemistry |
Vinylidene chloride and fluoride can be converted to linear polymers polyvinylidene chloride (PVDC) and polyvinylidene fluoride (PVDF). The polymerization reaction is:
: n CH=CX → (CH−CX)
These vinylidene polymers are isomeric with those produced from vinylene monomers. Thus polyvinylene fluoride from vinylene fluoride (HFC=CHF). | 0 | Theoretical and Fundamental Chemistry |
Negishi began dating Sumire Suzuki in his freshman year and they announced their engagement to their parents in March 1958. They had met at a choir of which they were both members at in university. They married the next year and together they had two daughters.
Negishi loved playing the piano and conducting. During the "Pacifichem" 2015 conference's closing ceremony, he conducted an orchestra. | 0 | Theoretical and Fundamental Chemistry |
Commonly used indicator bacteria include total coliforms, or a subset of this group, fecal coliforms, which are found in the intestinal tracts of warm blooded animals. Total coliforms were used as fecal indicators by public agencies in the US as early as the 1920s. These organisms can be identified based on the fact that they all metabolize the sugar lactose, producing both acid and gas as byproducts. Fecal coliforms are more useful as indicators in recreational waters than total coliforms which include species that are naturally found in plants and soil; however, there are even some species of fecal coliforms that do not have a fecal origin, such as Klebsiella pneumoniae. Perhaps the biggest drawback to using coliforms as indicators is that they can grow in water under certain conditions.
Escherichia coli (E. coli) and enterococci are also used as indicators. | 0 | Theoretical and Fundamental Chemistry |
The Otto Cycle is an example of a reversible thermodynamic cycle.
*1→2: Isentropic / adiabatic expansion: Constant entropy (s), Decrease in pressure (P), Increase in volume (v), Decrease in temperature (T)
*2→3: Isochoric cooling: Constant volume(v), Decrease in pressure (P), Decrease in entropy (S), Decrease in temperature (T)
*3→4: Isentropic / adiabatic compression: Constant entropy (s), Increase in pressure (P), Decrease in volume (v), Increase in temperature (T)
*4→1: Isochoric heating: Constant volume (v), Increase in pressure (P), Increase in entropy (S), Increase in temperature (T) | 0 | Theoretical and Fundamental Chemistry |
In physics, thermalisation (or thermalization) is the process of physical bodies reaching thermal equilibrium through mutual interaction. In general, the natural tendency of a system is towards a state of equipartition of energy and uniform temperature that maximizes the system's entropy. Thermalisation, thermal equilibrium, and temperature are therefore important fundamental concepts within statistical physics, statistical mechanics, and thermodynamics; all of which are a basis for many other specific fields of scientific understanding and engineering application.
Examples of thermalisation include:
* the achievement of equilibrium in a plasma.
* the process undergone by high-energy neutrons as they lose energy by collision with a moderator.
* the process of heat or phonon emission by charge carriers in a solar cell, after a photon that exceeds the semiconductor band gap energy is absorbed.
The hypothesis, foundational to most introductory textbooks treating quantum statistical mechanics, assumes that systems go to thermal equilibrium (thermalisation). The process of thermalisation erases local memory of the initial conditions. The eigenstate thermalisation hypothesis is a hypothesis about when quantum states will undergo thermalisation and why.
Not all quantum states undergo thermalisation. Some states have been discovered which do not (see below), and their reasons for not reaching thermal equilibrium are unclear . | 0 | Theoretical and Fundamental Chemistry |
In the United Kingdom, CChem candidates must meet the following requirements:
* Be a Member or a Fellow of the RSC;
* Hold a Master level accredited degree by the RSC (or equivalent);
* Show that the chemical science knowledge and skills acquired from their education and training are essential for fulfilling the needs of their job;
* Demonstrate development of 14 Professional Attributes.
The 14 professional attributes for Chartered Chemist in the UK are divided into five sections. The full list of attributes is: <br />
A. Demonstrate and develop your knowledge of the chemical sciences.
# Use a high-level knowledge of the chemical sciences to inform decisions and create impact.
# Continue to develop your knowledge of the chemical sciences and use this to support your work.
# Solve problems and draw conclusions by interpreting data, using evidence-based judgement and critical thinking to develop courses of action.
B. Professionalism.
# Work with autonomy, accountability and integrity in your role.
# Make a successful and impactful contribution as part of a team.
# Plan, organise, deliver work, and manage resources to meet organisational requirements.
# Contribute to continuous improvement by evaluating work and displaying adaptability.
C. Communication and influencing skills.
# Effectively convey information using both verbal and written forms.
# Consider and respond to alternative views and note the influence this has on your actions.
# Exert influence in your role either directly or through networks.
D. Professional responsibilities.
# Make a personal and impactful contribution to ensuring a healthy and safe working environment.
# Contribute to a sustainable future.
# Adhere to relevant codes of conduct including the RSC Code of Conduct, relating to fulfilling your duties in the workplace, and apply ethical practice to your role.
E. Supporting the profession.
# Be an active member of the scientific community either at work or outside work. | 1 | Applied and Interdisciplinary Chemistry |
In magnetically driven multiferroics the macroscopic electric polarization is induced by long-range magnetic order which is non-centrosymmetric. Formally, the electric polarisation, , is given in terms of the magnetization, , by
Like the geometric ferroelectrics discussed above, the ferroelectricity is improper, because the polarisation is not the primary order parameter (in this case the primary order is the magnetisation) for the ferroic phase transition.
The prototypical example is the formation of the non-centrosymmetric magnetic spiral state, accompanied by a small ferroelectric polarization, below 28K in TbMnO. In this case the polarization is small, 10 μC/cm, because the mechanism coupling the non-centrosymmetric spin structure to the crystal lattice is the weak spin-orbit coupling. Larger polarizations occur when the non-centrosymmetric magnetic ordering is caused by the stronger superexchange interaction, such as in orthorhombic HoMnO and related materials. In both cases the magnetoelectric coupling is strong because the ferroelectricity is directly caused by the magnetic order. | 0 | Theoretical and Fundamental Chemistry |
Scientists performing biomonitoring testing are able to detect and measure concentrations of natural and manmade chemicals in human blood and urine samples at parts-per-billion to parts-per-quadrillion levels. A 2006 U.S. National Research Council report found that while scientists were capable of detecting the chemicals at these levels, methods for interpreting and communicating what their presence meant regarding potential health risks to an individual or population were still lacking. The report recommended that scientific research be done to improve the interpretation and communication of biomonitoring results through the use of existing risk assessments of specific chemicals.
To address this situation, several groups recognized that exposure guidance values, such as reference dose and tolerable daily intake, could, with sufficient data, be translated into corresponding estimates of biomarker concentrations for use in the interpretation of biomonitoring data. In 2007, the initial methodology for the systematic translation of exposure guidance values into corresponding screening values for biomonitoring data, dubbed Biomonitoring Equivalents, was published by scientists from Summit Toxicology. Subsequently, an expert panel from government, industry and academia, convened to develop detailed guidelines for deriving and communicating these Biomonitoring Equivalents.
Biomonitoring Equivalents can be used for evaluation of biomonitoring data in a risk assessment context. Comparing biomonitoring data for a chemical with its Biomonitoring Equivalent provides a means for assessing whether population exposures to chemicals are within or above the levels considered safe by regulatory agencies. Biomonitoring Equivalents can thus assist scientists and risk managers in the prioritization of chemicals for follow-up or risk management activities.
Since 2007, scientists have derived and published Biomonitoring Equivalents for more than 110 chemicals, including cadmium, benzene, chloroform, arsenic, toluene, methylene chloride, triclosan, dioxins, volatile organic compounds, and others. Several have been developed through collaborations of scientists from the U.S. Environmental Protection Agency, CDC and Health Canada. Researchers from the German Human Biomonitoring Commission have also proposed a concept for deriving screening values similar to Biomonitoring Equivalents. | 1 | Applied and Interdisciplinary Chemistry |
Although theoretically, any living cell might be used as the background to a two-hybrid analysis, there are practical considerations that dictate which is chosen. The chosen cell line should be relatively cheap and easy to culture and sufficiently robust to withstand application of the investigative methods and reagents. The latter is especially important for doing high-throughput studies. Therefore the yeast S. cerevisiae has been the main host organism for two-hybrid studies. However it is not always the ideal system to study interacting proteins from other organisms. Yeast cells often do not have the same post translational modifications, have a different codon use or lack certain proteins that are important for the correct expression of the proteins. To cope with these problems several novel two-hybrid systems have been developed. Depending on the system used agar plates or specific growth medium is used to grow the cells and allow selection for interaction. The most common used method is the agar plating one where cells are plated on selective medium to see of interaction takes place. Cells that have no interaction proteins should not survive on this selective medium. | 1 | Applied and Interdisciplinary Chemistry |
A topologically associating domain (TAD) is a self-interacting genomic region, meaning that DNA sequences within a TAD physically interact with each other more frequently than with sequences outside the TAD. The median size of a TAD in mouse cells is 880 kb, and they have similar sizes in non-mammalian species. Boundaries at both side of these domains are conserved between different mammalian cell types and even across species and are highly enriched with CCCTC-binding factor (CTCF) and cohesin. In addition, some types of genes (such as transfer RNA genes and housekeeping genes) appear near TAD boundaries more often than would be expected by chance.
The functions of TADs are not fully understood and are still a matter of debate. Most of the studies indicate TADs regulate gene expression by limiting the enhancer-promoter interaction to each TAD; however, a recent study uncouples TAD organization and gene expression. Disruption of TAD boundaries are found to be associated with wide range of diseases such as cancer, variety of limb malformations such as synpolydactyly, Cooks syndrome, and F-syndrome, and number of brain disorders like Hypoplastic corpus callosum and Adult-onset demyelinating leukodystrophy.
The mechanisms underlying TAD formation are also complex and not yet fully elucidated, though a number of protein complexes and DNA elements are associated with TAD boundaries. However, the handcuff model and the loop extrusion model describe the TAD formation by the aid of CTCF and cohesin proteins. Furthermore, it has been proposed that the stiffness of TAD boundaries itself could cause the domain insulation and TAD formation. | 1 | Applied and Interdisciplinary Chemistry |
In the presence of palladium acetate under 1-30 bar of CO, simple aromatic compounds convert to aromatic carboxylic acids. A PSiP-pincer ligand (5) promotes carboxylation of allene without using pre-functionalized substrates. Catalyst regeneration, EtAl was added to do transmetallation with palladium. Catalyst is regenerated by the following β-H elimination. Apart from terminal allenes, some of internal allenes are also tolerated in this reaction, generating allyl carboxylic acid with the yield between 54% and 95%. This system was also applied to 1,3-diene, generating carboxylic acid in 1,2 addition fashion. In 2015, Iwasawa et al. reported the germanium analogue (6) and combined CO source together with hydride source to formate salts.
Palladium has shown huge power to catalyze C-H functionalization. If the Pd-C intermediate in carboxylation reaction comes from C-H activation, such methodology must promote metal catalyzed carboxylation to a much higher level in utility. Iwasawa and co-workers reported direct carboxylation by styrenyl C-H activation generating coumarin derivatives. Benzene rings with different electronic properties and some heteroaromatic rings are tolerated in this reaction with yield from 50% to 90%. C-H activation was demonstrated by crystallography study. | 0 | Theoretical and Fundamental Chemistry |
For the free neutron, the decay energy for this process (based on the rest masses of the neutron, proton and electron) is . That is the difference between the rest mass of the neutron and the sum of the rest masses of the products. That difference has to be carried away as kinetic energy. The maximal energy of the beta decay electron (in the process wherein the neutrino receives a vanishingly small amount of kinetic energy) has been measured at . The latter number is not well-enough measured to determine the comparatively tiny rest mass of the neutrino (which must in theory be subtracted from the maximal electron kinetic energy); furthermore, neutrino mass is constrained by many other methods.
A small fraction (about 1 in 1,000) of free neutrons decay with the same products, but add an extra particle in the form of an emitted gamma ray:
This gamma ray may be thought of as a sort of "internal bremsstrahlung" that arises as the emitted beta particle (electron) interacts with the charge of the proton in an electromagnetic way. In this process, some of the decay energy is carried away as photon energy. Gamma rays produced in this way are also a minor feature of beta decays of bound neutrons, that is, those within a nucleus.
A very small minority of neutron decays (about four per million) are so-called "two-body (neutron) decays", in which a proton, electron and antineutrino are produced as usual, but the electron fails to gain the 13.6 eV necessary energy to escape the proton (the ionization energy of hydrogen), and therefore simply remains bound to it, as a neutral hydrogen atom (one of the "two bodies"). In this type of free neutron decay, in essence all of the neutron decay energy is carried off by the antineutrino (the other "body").
The transformation of a free proton to a neutron (plus a positron and a neutrino) is energetically impossible, since a free neutron has a greater mass than a free proton. However, see proton decay. | 0 | Theoretical and Fundamental Chemistry |
No commercial applications of organoniobium compounds have been reported. They have found limited use in organic synthesis. | 0 | Theoretical and Fundamental Chemistry |
Both the deoxygenation rate, and reaeration rate, can be temperature corrected, following the general formula.
where
* is the rate at 20 degrees Celsius.
*θ is a constant, which differs for the two rates.
* is the actual temperature in the stream in degC.
Normally θ has the value 1.048 for and 1.024 for .
An increasing temperature has the most impact on the deoxygenation rate, and results in an increased critical deficit (), and decreases. Furthermore, a decreased concentration occurs with increasing temperature, which leads to a decrease in the DO concentration. | 1 | Applied and Interdisciplinary Chemistry |
The original form of the Kelvin equation, published in 1871, is:
where:
* = vapor pressure at a curved interface of radius
* = vapor pressure at flat interface () =
* = surface tension
* = density of vapor
* = density of liquid
* , = radii of curvature along the principal sections of the curved interface.
This may be written in the following form, known as the Ostwald–Freundlich equation:
where is the actual vapour pressure,
is the saturated vapour pressure when the surface is flat,
is the liquid/vapor surface tension, is the molar volume of the liquid, is the universal gas constant, is the radius of the droplet, and is temperature.
Equilibrium vapor pressure depends on droplet size.
* If the curvature is convex, is positive, then
* If the curvature is concave, is negative, then
As increases, decreases towards , and the droplets grow into bulk liquid.
If the vapour is cooled, then decreases, but so does . This means increases as the liquid is cooled. and may be treated as approximately fixed, which means that the critical radius must also decrease.
The further a vapour is supercooled, the smaller the critical radius becomes. Ultimately it can become as small as a few molecules, and the liquid undergoes homogeneous nucleation and growth.
The change in vapor pressure can be attributed to changes in the Laplace pressure. When the Laplace pressure rises in a droplet, the droplet tends to evaporate more easily.
When applying the Kelvin equation, two cases must be distinguished: A drop of liquid in its own vapor will result in a convex liquid surface, and a bubble of vapor in a liquid will result in a concave liquid surface. | 0 | Theoretical and Fundamental Chemistry |
Akin to pinacol couplings, imines are susceptible to reductive coupling leading to 1,2-diamines.
Imine are oxidized with meta-chloroperoxybenzoic acid (mCPBA) to give an oxaziridines.
Imines are intermediates in the alkylation of amines with formic acid in the Eschweiler-Clarke reaction.
A rearrangement in carbohydrate chemistry involving an imine is the Amadori rearrangement.
A methylene transfer reaction of an imine by an unstabilised sulphonium ylide can give an aziridine system.
Imine react with dialkylphosphite in the Pudovik reaction and Kabachnik–Fields reaction | 0 | Theoretical and Fundamental Chemistry |
There are several bacteria that use the Entner–Doudoroff pathway for metabolism of glucose and are unable to catabolize via glycolysis (e.g., therefore lacking essential glycolytic enzymes such as phosphofructokinase as seen in Pseudomonas). Genera in which the pathway is prominent include Gram-negative, as listed below, Gram-positive bacteria such as Enterococcus faecalis, as well as several in the Archaea, the second distinct branch of the prokaryotes (and the "third domain of life", after the prokaryotic Eubacteria and the eukaryotes). Due to the low energy yield of the ED pathway, anaerobic bacteria seem to mainly use glycolysis while aerobic and facultative anaerobes are more likely to have the ED pathway. This is thought to be due to the fact that aerobic and facultative anaerobes have other non-glycolytic pathways for creating ATP such as oxidative phosphorylation. Thus, the ED pathway is favored due to the lesser amounts of proteins required. While anaerobic bacteria must rely on the glycolysis pathway to create a greater percentage of their required ATP thus its 2 ATP production is more favored over the ED pathway's 1 ATP production.
Examples of bacteria using the pathway are:
* Pseudomonas, a genus of Gram-negative bacteria
* Azotobacter, a genus of Gram-negative bacteria
* Rhizobium, a plant root-associated and plant differentiation-active genus of Gram-negative bacteria
* Agrobacterium, a plant pathogen (oncogenic) genus of Gram-negative bacteria, also of biotechnologic use
* Escherichia coli, a Gram-negative bacterium
* Enterococcus faecalis, a Gram-positive bacterium
* Zymomonas mobilis, a Gram-negative facultative anaerobe
* Xanthomonas campestris, a Gram-negative bacterium which uses this pathway as main pathway for providing energy.
To date there is evidence of Eukaryotes using the pathway, suggesting it may be more widespread than previously thought:
*Hordeum vulgare, barley uses the Entner–Duodoroff pathway.
*Phaeodactylum tricornutum diatom model species presents functional phosphogluconate dehydratase and dehoxyphosphogluconate aldolase genes in its genome
The Entner–Doudoroff pathway is present in many species of Archaea (caveat, see following), whose metabolisms "resemble... in [their] complexity those of Bacteria and lower Eukarya", and often include both this pathway and the Embden-Meyerhof-Parnas pathway of glycolysis, except most often as unique, modified variants. | 1 | Applied and Interdisciplinary Chemistry |