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Increased RNA levels of Alu, which requires L1 proteins, are associated with a form of age-related macular degeneration, a neurological disorder of the eyes.
The naturally occurring mouse retinal degeneration model rd7 is caused by an L1 insertion in the Nr2e3 gene. | 1 | Applied and Interdisciplinary Chemistry |
Niyazi Serdar Sarıçiftçi graduated from the Austrian St. George's College in Istanbul. He also studied classical piano at the Music Conservatory in Istanbul (1970–1980).
Then he began studying physics at the University of Vienna (1980–1989). After obtaining the doctorate (1989), he conducted research on the 2nd Physical Institute of the University of Stuttgart, Germany (1989–1992). In 1992 he received the academic teaching license (venia docendi) by the Central Interuniversitary Commission (YÖK) in Ankara, Turkey. He then went to the Institute for Polymers & Organic Solids at the University of California, Santa Barbara, California, United States, where he worked for four years and, together with Alan J. Heeger (Nobel Prize in Chemistry, 2000) discovered and investigated the polymeric organic solar cells has (1992–1996). In April 1996, he accepted the appointment as Chair of Physical Chemistry at the Johannes Kepler University Linz.
Since 1996 he gives lectures as a full professor at the JKU and is the head of the Institute for Physical Chemistry. In 2000 he was appointed founding director of the Linz Institute for Organic Solar Cells (LIOS) at JKU. Between 2003 and 2009 he was elected to the City Council of the City of Linz (SPÖ Group). Furthermore, Sarıçiftçi is a founding member of the Linz Circle. He is also a member of various associations and societies: Fellow of the Royal Society of Chemistry (FRSC), American Chemical Society (ACS), Materials Research Society (MRS), Austrian Physical Society (ÖPG), Austrian Chemical Society (GÖCH) and Fellow of SPIE. 2014, he was elected a corresponding member of the Austrian Academy of Sciences (AAS). | 0 | Theoretical and Fundamental Chemistry |
To analyze the behavior of the crystals in this type of polymers, the WAXS and DSC techniques are used; these techniques help to determine what percentage of the polymer are crystals and how they are organized. This is due to the fact that the crystallinity decreases as the crosslinking increases, since the chains lose the ability to arrange themselves and order is essential to achieve crystallinity.
A second problem present when crosslinking molecules is melting, since an excess of crosslinking modifies the molecule in such a way that it stops melting (similar to a thermoset) and therefore the temporary shape cannot be obtained.
The control of curing either by electromagnetic waves or with peroxides is very important since it increases the T and decreases the crystallinity, determining factors in the shape-shape-memory effect.
In the case of biocompatible semicrystalline systems such as poly(ε-caprolactone) and poly(n-butyl acrylate), crosslinked by photopolymerization it has been reported that the crystallization behavior is affected by the cooling rate, as in any other semicrystalline polymer, but the heat of crystallization remains independent of the cooling rate.
The influence of the crosslinking of the molecules, the cooling rate and the crystallization behavior are specific to each system and impossible to enumerate since the synthesis possibilities are almost infinite.
Crystallizable polymers such as oligo(ε-caprolactone) can have amorphous segments such as poly(n-butyl acrylate) and the molecular mass ratio of each determine the behavior of the system in programming temporary form and recovery to permanent form. | 0 | Theoretical and Fundamental Chemistry |
Phycobilisomes are light-harvesting antennae that transmit the energy of harvested photons to photosystem II and photosystem I in cyanobacteria and in the chloroplasts of red algae and glaucophytes. They were lost during the evolution of the chloroplasts of green algae and plants. | 0 | Theoretical and Fundamental Chemistry |
The hydrophobic interaction is mostly an entropic effect originating from the disruption of the highly dynamic hydrogen bonds between molecules of liquid water by the nonpolar solute, causing the water to form a clathrate-like structure around the non-polar molecules. This structure formed is more highly ordered than free water molecules due to the water molecules arranging themselves to interact as much as possible with themselves, and thus results in a higher entropic state which causes non-polar molecules to clump together to reduce the surface area exposed to water and decrease the entropy of the system. Thus, the two immiscible phases (hydrophilic vs. hydrophobic) will change so that their corresponding interfacial area will be minimal. This effect can be visualized in the phenomenon called phase separation. | 0 | Theoretical and Fundamental Chemistry |
The energy efficiency of a conventional thermal power station is defined as saleable energy produced as a percent of the heating value of the fuel consumed. A simple cycle gas turbine achieves energy conversion efficiencies from 20 to 35%. Typical coal-based power plants operating at steam pressures of 170 bar and 570 °C run at efficiency of 35 to 38%, with state-of-the-art fossil fuel plants at 46% efficiency. Combined-cycle systems can reach higher values. As with all heat engines, their efficiency is limited, and governed by the laws of thermodynamics.
The Carnot efficiency dictates that higher efficiencies can be attained by increasing the temperature of the steam. Sub-critical pressure fossil fuel power stations can achieve 36–40% efficiency. Supercritical designs have efficiencies in the low to mid 40% range, with new "ultra critical" designs using pressures above 4400 psi (30.3 MPa) and multiple stage reheat reaching 45–48% efficiency. Above the critical point for water of and 3212 psi (22.06 MPa), there is no phase transition from water to steam, but only a gradual decrease in density.
Currently most nuclear power stations must operate below the temperatures and pressures that coal-fired plants do, in order to provide more conservative safety margins within the systems that remove heat from the nuclear fuel. This, in turn, limits their thermodynamic efficiency to 30–32%. Some advanced reactor designs being studied, such as the very-high-temperature reactor, Advanced Gas-cooled Reactor, and supercritical water reactor, would operate at temperatures and pressures similar to current coal plants, producing comparable thermodynamic efficiency.
The energy of a thermal power station not utilized in power production must leave the plant in the form of heat to the environment. This waste heat can go through a condenser and be disposed of with cooling water or in cooling towers. If the waste heat is instead used for district heating, it is called cogeneration. An important class of thermal power station is that associated with desalination facilities; these are typically found in desert countries with large supplies of natural gas, and in these plants freshwater production and electricity are equally important co-products.
Other types of power stations are subject to different efficiency limitations. Most hydropower stations in the United States are about 90 percent efficient in converting the energy of falling water into electricity while the efficiency of a wind turbine is limited by Betz's law, to about 59.3%, and actual wind turbines show lower efficiency. | 1 | Applied and Interdisciplinary Chemistry |
Water undergoes electrolysis at high temperatures to form hydrogen gas and oxygen gas. The energy to perform this is extracted from renewable sources such as wind power. Then, the hydrogen is reacted with compressed carbon dioxide captured by direct air capture. The reaction produces blue crude which consists of hydrocarbon. The blue crude is then refined to produce high efficiency E-diesel. This method is, however, still debatable because with the current production capability it can only produce 3,000 liters in a few months, 0.0002% of the daily production of fuel in the US. Furthermore, the thermodynamic and economic feasibility of this technology have been questioned. An article suggests that this technology does not create an alternative to fossil fuel but rather converting renewable energy into liquid fuel. The article also states that the energy return on energy invested using fossil diesel is 18 times higher than that for e-diesel. | 0 | Theoretical and Fundamental Chemistry |
Mitochondrial threshold effect is a phenomenon where the number of mutated mtDNA has surpassed a certain threshold which causes the electron transport chain and ATP synthesis of a mitochondrion to fail. There isn't a set number that needs to be surpassed, however, it is associated with an increase of the number of mutated mtDNA. When there is 60-80% of mutated mtDNA present, that is said to be the threshold level. While 60-80% is the general threshold level, this is also dependent on the individual, the specific organ in question and what the specific mutation is. There are three specific types of mitochondrial threshold effects: phenotypic threshold effect, biochemical threshold effect and translational threshold effect.
Threshold expression is a phenomenon in which phenotypic expression of a mitochondrial disease within an organ system occurs when the severity of the mutation, relative number of mutant mtDNA, and reliance of the organ system on oxidative phosphorylation combine in such a way that ATP production of the tissue falls below the level required by the tissue. The phenotype may be expressed even if the percentage of mutant mtDNA is below 50% if the mutation is severe enough. | 1 | Applied and Interdisciplinary Chemistry |
The Goldschmidt tolerance factor () is a dimensionless number that is calculated from the ratio of the ionic radii:
In an ideal cubic perovskite structure, the lattice parameter (i.e., length) of the unit cell (a) can be calculated using the following equation: | 0 | Theoretical and Fundamental Chemistry |
A typical laboratory FPLC consist of one or two high-precision pumps, a control unit, a column, a detection system and a fraction collector. Although it is possible to operate the system manually, the components are normally linked to a personal computer or, in older units, a microcontroller. | 0 | Theoretical and Fundamental Chemistry |
Mary Jean Garson (born 6 November 1953) is an organic chemist and academic in Australia. She currently works for the University of Queensland. | 0 | Theoretical and Fundamental Chemistry |
Uranium is a naturally occurring element found in low levels within all rock, soil, and water. This is the highest-numbered element to be found naturally in significant quantities on earth. According to the United Nations Scientific Committee on the Effects of Atomic Radiation the normal concentration of uranium in soil is 300 μg/kg to 11.7 mg/kg.
It is considered to be more plentiful than antimony, beryllium, cadmium, gold, mercury, silver, or tungsten and is about as abundant as tin, arsenic or molybdenum. It is found in many minerals including uraninite (most common uranium ore), autunite, uranophane, torbernite, and coffinite. Significant concentrations of uranium occur in some substances such as phosphate rock deposits, and minerals such as lignite, and monazite sands in uranium-rich ores (it is recovered commercially from these sources). Coal fly ash from uranium bearing coal is particularly rich in uranium and there have been several proposals to "mine" this waste product for its uranium content. Due to the fact that part of the ash of a coal power plant escapes through the smokestack, the radioactive contamination released by coal power plants in regular operation is actually higher than that of nuclear power plants.
Seawater contains about 3.3 parts per billion of uranium by weight, approximately (3.3 µg/kg) or, 3.3 micrograms per liter of seawater. | 0 | Theoretical and Fundamental Chemistry |
The mechanism of the Hofmeister series is not entirely clear, but does not seem to result from changes in general water structure, instead more specific interactions between ions and proteins and ions and the water molecules directly contacting the proteins may be more important. Simulation studies have shown that the variation in solvation energy between the ions and the surrounding water molecules underlies the mechanism of the Hofmeister series. A quantum chemical investigation suggests an electrostatic origin to the Hofmeister series. This work provides site-centred radial charge densities of the ions' interacting atoms (to approximate the electrostatic potential energy of interaction), and these appear to quantitatively correlate with many reported Hofmeister series for electrolyte properties, reaction rates and macromolecular stability (such as polymer solubility, and virus and enzyme activities).
Early members of the series increase solvent surface tension and decrease the solubility of nonpolar molecules ("salting out"); in effect, they strengthen the hydrophobic interaction. By contrast, later salts in the series increase the solubility of nonpolar molecules ("salting in") and decrease the order in water; in effect, they weaken the hydrophobic effect.
The "salting out" effect is commonly exploited in protein purification through the use of ammonium sulfate precipitation. However, these salts also interact directly with proteins (which are charged and have strong dipole moments) and may even bind specifically (e.g., phosphate and sulfate binding to ribonuclease A).
Ions that have a strong "salting in" effect such as I and SCN are strong denaturants, because they salt in the peptide group, and thus interact much more strongly with the unfolded form of a protein than with its native form. Consequently, they shift the chemical equilibrium of the unfolding reaction towards unfolded protein. | 0 | Theoretical and Fundamental Chemistry |
After 1990, the entire pharmacy underwent extensive refurbishment, as the building had been neglected for almost 50 years. This refurbishment lasted over 10 years until 2003.
Presently the main part of the pharmacy is located on the first floor and sells most modern medicines, including aspirin, and even supplies condoms.
There is an antiques shop on the first floor and in 1999 a garlic restaurant called "Balthasar" was opened on the second floor. | 1 | Applied and Interdisciplinary Chemistry |
A galvanic anode, or sacrificial anode, is the main component of a galvanic cathodic protection system used to protect buried or submerged metal structures from corrosion.
They are made from a metal alloy with a more "active" voltage (more negative reduction potential / more positive electrode potential) than the metal of the structure. The difference in potential between the two metals means that the galvanic anode corrodes, in effect being "sacrificed" in order to protect the structure. | 0 | Theoretical and Fundamental Chemistry |
In physics, interference is the meeting of two correlated waves and either increasing or lowering the net amplitude, depending on whether it is constructive or destructive interference. If a crest of a wave meets a crest of another wave at the same point then the crests interfere constructively and the resultant crest wave amplitude is increased; forming a much more powerful wave than either of the beginning waves. Similarly two troughs make a trough of increased amplitude. If a crest of a wave meets a trough of another wave then they interfere destructively, and the overall amplitude is decreased; thus making a wave that is much smaller than either of the parent waves.
The formation of a mach stem is one example of constructive interference. Whenever a blast wave reflects off of a surface, such as a building wall or the inside of a vehicle, different reflected waves can interact with each other to cause an increase in pressure at a certain point (constructive interference) or a decrease (destructive interference). In this way the interaction of blast waves is similar to that of sound waves or water waves. | 1 | Applied and Interdisciplinary Chemistry |
The line coefficient (Fig 5) suggests that this is a fairly accurate result, however this is only the case for the pairing of that particular solid with those particular liquids. In other cases, the fit may not be so great (such is the case if we replace polyethylene with poly(methyl methacrylate), wherein the line coefficient of the plot results using the same list of liquids would be significantly lower). This shortcoming is a result of the fact that the Zisman theory treats the surface energy as one single parameter, rather than accounting for the fact that, for example, polar interactions are much stronger than dispersive ones, and thus the degree to which one is happening versus the other greatly affects the necessary calculations. As such, it is a simple but not particularly robust theory. Since the premise of this procedure is to determine the hypothetical properties of a liquid, the precision of the result depends on the precision to which the surface energy values of the probe liquids are known. | 0 | Theoretical and Fundamental Chemistry |
Temperature plays a key role in the ecology, physiology and metabolism of aquatic species. The rate of PCB metabolism was temperature dependent in yellow perch (Perca flavescens). In fall and winter, only 11 out of 72 introduced PCB congeners were excreted and had halflives of more than 1,000 days. During spring and summer when the average daily water temperature was above 20 °C, persistent PCBs had halflives of 67 days. The main excretion processes were fecal egestion, growth dilution and loss across respiratory surfaces. The excretion rate of PCBs matched with the perch's natural bioenergetics, where most of their consumption, respiration and growth rates occur during the late spring and summer. Since the perch is performing more functions in the warmer months, it naturally has a faster metabolism and has less PCB accumulation. However, multiple cold-water periods mixed with toxic PCBs with coplanar chlorine molecules can be detrimental to perch health. | 1 | Applied and Interdisciplinary Chemistry |
Methylene iodide and two equivalents of ethyl acetoacetate react in the presence of sodium methoxide to form the diethyl ester of 2,4-diacetyl pentane. This precursor is treated with base to induce cyclization. Finally, heat is applied to generate Hagemann's ester. | 0 | Theoretical and Fundamental Chemistry |
The defensive spray of skunks consists mainly of low-molecular-weight thiols and derivatives with a foul odor, which protects the skunk from predators. Owls are able to prey on skunks, as they lack a sense of smell. | 0 | Theoretical and Fundamental Chemistry |
The citric acid cycle (Krebs cycle) is a good example of an amphibolic pathway because it functions in both the degradative (carbohydrate, protein, and fatty acid) and biosynthetic processes. The citric acid cycle occurs on the cytosol of bacteria and within the mitochondria of eukaryotic cells. It provides electrons to the electron transport chain which is used to drive the production of ATP in oxidative phosphorylation. Intermediates in the citric acid cycle, such as oxaloacetate, are used to synthesize macromolecule constituents such as amino acids, e.g. glutamate and aspartate.
The first reaction of the cycle, in which oxaloacetate (a four-carbon compound) condenses with acetate (a two-carbon compound) to form citrate (a six-carbon compound) is typically anabolic. The next few reactions, which are intramolecular rearrangements, produce isocitrate. The following two reactions, namely the conversion of D-isocitrate to α-Ketoglutarate followed by its conversion to succinyl-CoA, are typically catabolic. Carbon dioxide is lost in each step and succinate (a four-carbon compound) is produced.
There is an interesting and critical difference in the coenzymes used in catabolic and anabolic pathways; in catabolism NAD+ serves as an oxidizing agent when it is reduced to NADH. Whereas in anabolism the coenzyme NADPH serves as the reducing agent and is converted to its oxidized form NADP.
Citric acid cycle has two modes that play two roles, the first being energy production produced by the oxidative mode, as the acetyl group of acetyl-coA is fully oxidized to CO. This produces most of the ATP in the metabolism of aerobic heterotrophic metabolism, as this energy conversion in the membrane structure (cytoplasmic membrane in bacteria and mitochondria in eukaryotes) by oxidative phosphorylation by moving electron from donor (NADH and FADH) to the acceptor O. Every cycle give 3 NADH, 1 FADH, CO and GTP. The second role is biosynthetic, as citric acid cycle regenerate oxaloacetate when cycle intermediates are removed for biosynthesis. | 1 | Applied and Interdisciplinary Chemistry |
Turner angle is related to the density ratio mathematically by:
Meanwhile, Turner angle has more advantages than density ratio in aspects of:
* The infinite scale of is replaced by a finite one running from +π to -π;
* The strong fingering () and weak fingering () regions occupy about the same space on the Tu scale;
* The indeterminate value obtained when is well defined in terms of Tu;
* The regimes and their corresponding angles are easy to remember, and symmetric in the sense that if Tu corresponds to R, then -Tu corresponds to R. This links roughly equal strengths of finger and diffusive sense convection.
Nevertheless, Turner angle is not as directly obvious as density ratio when assessing different attributions of thermal and haline stratification. Its strength mainly focuses on classification. | 1 | Applied and Interdisciplinary Chemistry |
We use z as an axial coordinate and r as the radial
coordinate, and assume axisymmetry. The pipe has radius a, and
the fluid velocity is:
The concentration of the diffusing species is denoted c and its
diffusivity is D. The concentration is assumed to be governed by
the linear advection–diffusion equation:
The concentration and velocity are written as the sum of a cross-sectional average (indicated by an overbar) and a deviation (indicated by a prime), thus:
Under some assumptions (see below), it is possible to derive an equation just involving the average quantities:
Observe how the effective diffusivity multiplying the derivative on the right hand side is greater than the original value of diffusion coefficient, D. The effective diffusivity is often written as:
where is the Péclet number, based on the channel radius . The interesting result is that for large values of the Péclet number, the effective diffusivity is inversely proportional to the molecular diffusivity. The effect of Taylor dispersion is therefore more pronounced at higher Péclet numbers.
In a frame moving with the mean velocity, i.e., by introducing , the dispersion process becomes a purely diffusion process,
with diffusivity given by the effective diffusivity.
The assumption is that for given , which is the case if the length scale in the direction is long enough to smooth the gradient in the direction. This can be translated into the requirement that the length scale in the direction satisfies:
Dispersion is also a function of channel geometry. An interesting phenomenon for example is that the dispersion of a flow between two infinite flat plates and a rectangular channel, which is infinitely thin, differs approximately 8.75 times. Here the very small side walls of the rectangular channel have an enormous influence on the dispersion.
While the exact formula will not hold in more general circumstances, the mechanism still applies, and the effect is stronger at higher Péclet numbers. Taylor dispersion is of particular relevance for flows in porous media modelled by Darcy's law. | 1 | Applied and Interdisciplinary Chemistry |
It can be synthesised in the following ways:
* as an intermetallic compound, by direct fusion of pure components according to stoichiometric calculations:
* by reduction of uranium dioxide with hydrogen in the presence of platinum: | 1 | Applied and Interdisciplinary Chemistry |
Phenylmercuric borate and acetate were used for disinfecting mucous membranes at an effective concentration of 0.07% in aqueous solutions. Due to toxicological and ecotoxicological reasons phenylmercury salts are no longer in use. However, some surgeons use mercurochrome despite toxicological objections. Mercurochrome is still available to purchase in Australia to use on minor wounds. Dental amalgam used in fillings inhibits bacterial reproduction.
Organic mercury compounds have been used as topical disinfectants (thimerosal, nitromersol, and merbromin) and preservatives in medical preparations (thimerosal) and grain products (both methyl and ethyl mercurials). Mercury was used in the treatment of syphilis. Calomel was commonly used in infant teething powders in the 1930s and 1940s. Mercurials are also used agriculturally as insecticides and fungicides. | 1 | Applied and Interdisciplinary Chemistry |
1-Octene, 1-hexene, and 1-butene are used comonomers in the manufacture of polyethylenes. The advantages to such copolymers has led to a focus on catalysts that facilitate the incorporation of these comonomers, e.g., constrained geometry complexes.
Comonomers are often employed to improve the plastification of polymeric materials, i.e. the flexibility of the polymer. Unlike traditional plasticizers, comonomers are not leachable. | 0 | Theoretical and Fundamental Chemistry |
Some representative examples of Crich’s β-mannosylation are shown in Scheme 3. It is noteworthy that, with this method in hand, primary, secondary, and tertiary alcohols (9, 12, and 13) all serve as glycosyl acceptors effectively in terms of yields and selectivity. In a recent version, the β-mannosylation of thioglycoside 14 and its analogues were examined to prepare sterically hindered glycosides, in which PhSOTf (or other newly developed sulfur-type oxidants) served as a convenient reagent for the in situ generation of the glycosyl triflate from 14, thus facilitating the reaction. | 0 | Theoretical and Fundamental Chemistry |
The cAMP signal transduction contains five main characters: stimulative hormone receptor (Rs) or inhibitory hormone receptor (Ri); stimulative regulative G-protein (Gs) or inhibitory regulative G-protein (Gi); adenylyl cyclase; protein kinase A (PKA); and cAMP phosphodiesterase.
Stimulative hormone receptor (Rs) is a receptor that can bind with stimulative signal molecules, while inhibitory hormone receptor (Ri) is a receptor that can bind with inhibitory signal molecules.
Stimulative regulative G-protein is a G-protein linked to stimulative hormone receptor (Rs), and its α subunit upon activation could stimulate the activity of an enzyme or other intracellular metabolism. On the contrary, inhibitory regulative G-protein is linked to an inhibitory hormone receptor, and its α subunit upon activation could inhibit the activity of an enzyme or other intracellular metabolism.
Adenylyl cyclase is a 12-transmembrane glycoprotein that catalyzes the conversion of ATP to cAMP with the help of cofactor Mg or Mn. The cAMP produced is a second messenger in cellular metabolism and is an allosteric activator of protein kinase A.
Protein kinase A is an important enzyme in cell metabolism due to its ability to regulate cell metabolism by phosphorylating specific committed enzymes in the metabolic pathway. It can also regulate specific gene expression, cellular secretion, and membrane permeability. The protein enzyme contains two catalytic subunits and two regulatory subunits. When there is no cAMP，the complex is inactive. When cAMP binds to the regulatory subunits, their conformation is altered, causing the dissociation of the regulatory subunits, which activates protein kinase A and allows further biological effects.
These signals then can be terminated by cAMP phosphodiesterase, which is an enzyme that degrades cAMP to 5'-AMP and inactivates protein kinase A. | 1 | Applied and Interdisciplinary Chemistry |
Ion exchange sorbents separate analytes based on electrostatic interactions between the analyte of interest and the positively or negatively charged groups on the stationary phase. For ion exchange to occur, both the stationary phase and sample must be at a pH where both are charged. | 0 | Theoretical and Fundamental Chemistry |
The dye-tuning capabilities cucurbiturils possess have been explored by researchers in recent years. In general, it has been found that the confined, low-polarity environment provided by the cucurbiturils leads to enhanced brightness, increased photostability, increased fluorescence lifetimes, and solvatochromism consistent with moving to an environment of lower polarity. | 0 | Theoretical and Fundamental Chemistry |
An isotope and/or nuclide is specified by the name of the particular element (this indicates the atomic number) followed by a hyphen and the mass number (e.g. helium-3, helium-4, carbon-12, carbon-14, uranium-235 and uranium-239). When a chemical symbol is used, e.g. "C" for carbon, standard notation (now known as "AZE notation" because A is the mass number, Z the atomic number, and E for element) is to indicate the mass number (number of nucleons) with a superscript at the upper left of the chemical symbol and to indicate the atomic number with a subscript at the lower left (e.g. , , , , , and ). Because the atomic number is given by the element symbol, it is common to state only the mass number in the superscript and leave out the atomic number subscript (e.g. , , , , , and ). The letter m is sometimes appended after the mass number to indicate a nuclear isomer, a metastable or energetically excited nuclear state (as opposed to the lowest-energy ground state), for example (tantalum-180m).
The common pronunciation of the AZE notation is different from how it is written: is commonly pronounced as helium-four instead of four-two-helium, and as uranium two-thirty-five (American English) or uranium-two-three-five (British) instead of 235-92-uranium. | 0 | Theoretical and Fundamental Chemistry |
Antoine Lavoisier noted in 1780 that heat production, in some cases, can be predicted from oxygen consumption, using multiple regression. Indirect calorimetry, as we know it, was developed around 1900 as an application of thermodynamics to animal life. Although the development of indirect calorimetry dates back over 200 years, its greatest use has been in the last two decades with the development of total parenteral nutrition, interdisciplinary nutrition support teams, and the production of portable, reliable, relatively inexpensive calorimeters. | 1 | Applied and Interdisciplinary Chemistry |
In the field of stable isotope geochemistry, isotopologues of simple molecules containing rare heavy isotopes of carbon, oxygen, hydrogen, nitrogen, and sulfur are used to trace equilibrium and kinetic processes in natural environments and in Earth's past. | 0 | Theoretical and Fundamental Chemistry |
In combustion, Liñán's flame speed provides the estimate of the upper limit for edge-flame propagation velocity, when the flame curvature is small. The formula is named after Amable Liñán. When the flame thickness is much smaller than the mixing-layer thickness through which the edge flame is propagating, a flame speed can be defined as the propagating speed of the flame front with respect to a region far ahead of the flame. For small flame curvatures (flame stretch), each point of the flame front propagates at a laminar planar premixed speed that depends on a local equivalence ratio just ahead of the flame. However, the flame front as a whole do not propagate at a speed since the mixture ahead of the flame front undergoes thermal expansion due to the heating by the flame front, that aids the flame front to propagate faster with respect to the region far ahead from the flame front. Liñán estimated the edge flame speed to be:
where and is the density of the fluid far upstream and far downstream of the flame front. Here is the stoichiometric value () of the planar speed. Due to the thermal expansion, streamlines diverges as it approaches the flame and a pressure builds just ahead of the flame.
The scaling law for the flame speed was verified experimentally In constant density approximation, this influence due to density variations disappear and the upper limit of the edge flame speed is given by the maximum value of . | 1 | Applied and Interdisciplinary Chemistry |
A pure fusion weapon is a hypothetical hydrogen bomb design that does not need a fission "primary" explosive to ignite the fusion of deuterium and tritium, two heavy isotopes of hydrogen used in fission-fusion thermonuclear weapons. Such a weapon would require no fissile material and would therefore be much easier to develop in secret than existing weapons. Separating weapons-grade uranium (U-235) or breeding plutonium (Pu-239) requires a substantial and difficult-to-conceal industrial investment, and blocking the sale and transfer of the needed machinery has been the primary mechanism to control nuclear proliferation to date. | 0 | Theoretical and Fundamental Chemistry |
Because water has strong cohesive and adhesive forces, it exhibits capillary action. Strong cohesion from hydrogen bonding and adhesion allows trees to transport water more than 100 m upward. | 1 | Applied and Interdisciplinary Chemistry |
While the AnMBR technology has many benefits for revolutionizing wastewater treatment, it does not come without its drawbacks. The AnMBR is prone to membrane fouling by aggregation of bacteria. This proves to be quite dangerous for the technology as it would drastically reduce the efficiency of filtration, in turn also increasing energy consumption, making the entire process more expensive. Membrane fouling also leads to the technology having to be replaced much more often, which is also expensive. In addition, the anaerobic bacteria are susceptible to entering the effluent, which leads to their loss in the reactor unit. | 1 | Applied and Interdisciplinary Chemistry |
When light leaves one material and enters another it bends, or refracts. The refractive index of a material is a measure of how much light bends when it enters. Differential refractometers contain a flow cell with two parts: one for the sample and one for the reference solvent. The detector measures the refractive index of both components. When only solvent is passing through the sample component the measured refractive index of both components is the same, but when an analyte passes through the flow cell the two measured refractive index are different. The difference appears as a peak in the chromatogram. | 0 | Theoretical and Fundamental Chemistry |
In addition to both surfaces' being practically conformal (in practice often completely flat), the surfaces must also be extremely clean and free from any small contamination that would prevent or weaken the bond—including grease films and specks of dust. For bonding to occur, the surfaces need only to be brought together; the intermolecular forces draw the bodies into the lowest energy conformation, and no pressure needs to be applied. | 0 | Theoretical and Fundamental Chemistry |
The biosynthetic pathway to paclitaxel has been investigated and consists of approximately 20 enzymatic steps. The complete scheme is still unavailable. The segments that are known are very different from the synthetic pathways tried thus far (Scheme 1). The starting compound is geranylgeranyl diphosphate 2 which is a dimer of geraniol 1. This compound already contains all the required 20 carbon atoms for the paclitaxel skeleton. More ring closing through intermediate 3 (taxadiene) leads to taxusin 4. The two main reasons why this type of synthesis is not feasible in the laboratory is that nature does a much better job controlling stereochemistry and a much better job activating a hydrocarbon skeleton with oxygen substituents for which cytochrome P450 is responsible in some of the oxygenations. Intermediate 5 is called 10-deacetylbaccatin III.
A biochemical kilogram-scale production of taxadiene was reported using genetically engineered E. coli in 2011. | 0 | Theoretical and Fundamental Chemistry |
The set of translations and rotations together form the rigid motions or rigid displacements. This set forms a group under composition, the group of rigid motions, a subgroup of the full group of Euclidean isometries. | 0 | Theoretical and Fundamental Chemistry |
Recent advances in technology have allowed for the use of argon gas to drive ice formation using a principle known as the Joule-Thomson effect. This gives physicians excellent control of the ice and minimizes complications using ultra-thin 17 gauge cryoneedles. | 1 | Applied and Interdisciplinary Chemistry |
The Orphan Drug Act (ODA) of January 1983, passed in the United States, with lobbying from the National Organization for Rare Disorders and many other organizations, is meant to encourage pharmaceutical companies to develop drugs for diseases that have a small market. Under the ODA drugs, vaccines, and diagnostic agents would qualify for orphan status if they were intended to treat a disease affecting fewer than 200,000 American citizens. Under the ODA orphan drug sponsors qualify for seven-year FDA-administered market Orphan Drug Exclusivity (ODE), "tax credits of up to 50% of R&D costs, R&D grants, waived FDA fees, protocol assistance and may get clinical trial tax incentives.
In the U.S., orphan drug designation means that the sponsor qualifies for certain benefits, but it does not mean the drug is safe, effective or legal.
In 2002, the Rare Diseases Act was signed into law. It amended the Public Health Service Act to establish the Office of Rare Diseases. It also increased funding for the development of treatments for people with rare diseases. | 1 | Applied and Interdisciplinary Chemistry |
Primary treatment settling removes about half of the solids and a third of the BOD from raw sewage. Secondary treatment is defined as the "removal of biodegradable organic matter (in solution or suspension) and suspended solids. Disinfection is also typically included in the definition of conventional secondary treatment." Biological nutrient removal is regarded by some sanitary engineers as secondary treatment and by others as tertiary treatment.
After this kind of treatment, the wastewater may be called secondary-treated wastewater. | 1 | Applied and Interdisciplinary Chemistry |
*Reiner Salzer (Chair), TU Dresden, Dresden, Germany
*Martino Di Serio (Vice-Chair), University of Naples Federico II, Naples, Italy
*Jiří Barek (Secretary for Internal Matters), Charles University, Prague, Czech Republic
*Gergely Tóth (Secretary for External Matters), Eötvös Loránd University, Budapest, Hungary | 1 | Applied and Interdisciplinary Chemistry |
* Polyethylene
* Polypropylene
* Copolymers of ethylene and 1-alkenes
* Polybutene-1
* Polymethylpentene
* Polycycloolefins
* Polybutadiene
* Polyisoprene
* Amorphous poly-alpha-olefins (APAO)
* Polyacetylene | 0 | Theoretical and Fundamental Chemistry |
Photochromism is the phenomenon that produces a change of colour in a substance by incident radiation. In other words, Photochromism is a light-induced change of colour of a chemical substance. The spiropyrans are one of the photochromatic molecules that have raised more interest lately. These molecules consist of two heterocyclic functional groups in orthogonal planes bound by a carbon atom. Spiropyrans are one of the oldest families of photochromism. As solids, the spiropyrans do not present photochromism. It is possible in solution and in the dry state that radiation between 250 nm and 380 nm (approximately) is able to, by breaking the C-O binding, transform the spiropyrans into its colour emitting merocyanin-form. The structure of the colourless molecules, the substrate of the reaction (N), is more thermodynamically stable than the product – depending on the solvent in which it is stored. For example in NMP the equilibrium could be switched more toward the merocyanin form (solvatochromic effects). The photoisomers of the spiropyrans have a structure similar to cyanines, even though it is not symmetric about the center of the polymethine chain, and it is classified as a merocyanine (Figure 2).
Once the irradiation has stopped, the merocyanine in solution starts to discolour and to revert to its original form, the spiropyran (N).
Procedure:
* Irradiation of spiropyrans in solution with UV light of wavelength 250–380 nm breaks C-O bonds.
* Consequently, the structure of the initial molecule changes, the resulting one being merocyanine (MC). Because of the apparent conjugated system after UV illumination the extinction coefficient of the MC-form is significantly higher than the one of the closed spiropyran form.
* Unlike the initial solution, the product of the photochromism reaction is not colourless.
*Depending on substituent on the aromatic system the switching behaviour of the derivatives can change in their switching velocity and photo-fatigue resistance. | 0 | Theoretical and Fundamental Chemistry |
Phosphine imides can be isolated as intermediates in the Staudinger reaction and have also been prepared by the action of hydroxylamine-O-sulfonic acid on phosphines, proceeding via a p-aminophosphonium salt. | 0 | Theoretical and Fundamental Chemistry |
If the reaction is a simple electron transfer reaction, the peaks should remain symmetrical at fast scan rates. A peak separation is observed when the scan rate , where is the exchange electron transfer rate constant in Butler Volmer theory. Laviron equation predicts that at fast scan rates, the peaks separate in proportion to . The larger or the smaller , the larger the peak separation. The peak potentials are , as shown by lines in fig 2B ( is the charge transfer coefficient). Examining the experimental change in peak position against scan rate therefore informs on the rate of interfacial electron transfer . | 0 | Theoretical and Fundamental Chemistry |
Imines are common in nature. The pyridoxal phosphate-dependent enzymes (PLP enzymes) catalyze myriad reactions involving aldimines (or Schiff bases). Cyclic imines are also substrates for many imine reductase enzymes. | 0 | Theoretical and Fundamental Chemistry |
The U.S. Food and Drug Administration (FDA) launched the Critical Path Initiative in 2004 to transform the way FDA-regulated medical products are developed, evaluated, and manufactured. C-Path was created as an independent organization to respond to the needs outlined in the FDA's initiative and with support and funding from the FDA, [http://www.sfaz.org/ Science Foundation Arizona], and the Tucson, Arizona community. It operates as a neutral third party to enable scientists from the regulated industry and international regulatory agencies to work together with scientists from academia and patient groups to improve the drug development process. | 1 | Applied and Interdisciplinary Chemistry |
Hepoxilin-epoxide hydrolase or hepoxilin hydrolase is currently best defined as an enzyme activity that converts the biologically active monohydroxy-epoxide metabolites of arachidonic acid hepoxilin A3s and hepoxilin B3s to essentially inactive trihydroxy products, the trioxilins. That is, hepoxilin A3s (8-hydroxy-11,12-oxido-5Z,9E,14Z-eicosatrienoic acid) are metabolized to trioxilin A3s (8,11,12-trihydroxy-5Z,9E,14Z-eicosatrienoic acids) and hepoxilins B3s (10-hydroxy-11,12-oxido-5Z,8Z,14Z-eicosatrienoic acids) are metabolized to trioxilin B3s (10,11,12-trihydroxy-5Z,8Z,14Z-eicosatrienoic acids). However, this activity has not been characterized at the purified protein or gene level and recent work indicate that sEH readily metabolizes an hepoxilin A3 to a trioxilin A3 and that hepoxilin-epoxide hydrolase activity is due to sEH, at least as it is detected in mouse liver. | 1 | Applied and Interdisciplinary Chemistry |
Lipotoxicity affects the pancreas when excess free fatty acids are found in beta cells, causing their dysfunction and death. The effects of the lipotoxicity is treated with leptin therapy and insulin sensitizers. | 1 | Applied and Interdisciplinary Chemistry |
On 18 August 2014, the British Columbia government ordered an independent engineering investigation into the pond breach and a third-party review of all 2014 dam safety inspections for every permitted mines tailings pond in the province. The report found that the tailings dam collapsed because of its construction on underlying earth containing a layer of glacial till, which had been unaccounted for by the companys original engineering contractor.
The report investigated whether the piezometers measuring the water pressure on the dam had been located correctly, as the last readings, 2 August 2014, did not show any changes in the water pressure. In 2010, Mount Polley Mining Corporation's (MPMC) engineering firm reported a crack in the earthen dam while working to raise it, and that piezometers were broken, which were later fixed.
In 2018, three engineers who worked on the tailings storage facility were charged by their professional association with negligence or unprofessional conduct. | 1 | Applied and Interdisciplinary Chemistry |
Permeable clay brick pavements are fired clay brick units with open, permeable spaces between the units. Clay pavers provide a durable surface that allows stormwater runoff to permeate through the joints. | 1 | Applied and Interdisciplinary Chemistry |
Gaskets are mechanical seals, usually ring-shaped, which seal flange joints. Gaskets vary by construction, materials and features. Commonly used gaskets are non-metallic (ASME B 16.21), spiral-wound (ASME B 16.20) and ring-joint (ASME B 16.20). Non-metallic gaskets are used with flat- or raised-face flanges. Spiral-wound gaskets are used with raised-face flanges, and ring-joint gaskets are used with ring-type joint (RTJ) flanges. Stress develops between an RTJ gasket and the flange groove when the gasket is bolted to a flange, leading to plastic deformation of the gasket. | 1 | Applied and Interdisciplinary Chemistry |
SOD2 uses cyclic proton-coupled electron transfer reactions to convert superoxide (O) into either oxygen (O) or hydrogen peroxide (HO), depending on the oxidation state of the manganese metal and the protonation status of the active site.
Mn + O ↔ Mn + O
Mn + O + 2H ↔ Mn + HO
The protons of the active site have been directly visualized and revealed that SOD2 utilizes proton transfers between a glutamine residue and a Mn-bound solvent molecule in concert with its electron transfers. During the Mn to Mn redox reaction, Gln143 donates an amide proton to hydroxide bound to the Mn and forms an amide anion. The amide anion is stabilized by short-strong hydrogen bonds (SSHBs) with the Mn-bound solvent and the nearby Trp123 residue. For the Mn to Mn redox reaction, the proton is donated back to the glutamine to reform the neutral amide state. The fast and efficient PCET catalysis of SOD2 is explained by the use of a proton that is always present and never lost to bulk solvent. | 0 | Theoretical and Fundamental Chemistry |
Various cultures divide the semantic field of colors differently from the English language usage and some do not distinguish between blue and green in the same way. An example is Welsh where can mean blue or green, or Vietnamese where likewise can mean either. Conversely, in Russian and some other languages, there is no single word for blue, but rather different words for light blue (, ) and dark blue (, ).
Other color names assigned to bodies of water are sea green and ultramarine blue. Unusual oceanic colorings have given rise to the terms red tide and black tide.
The Ancient Greek poet Homer uses the epithet "wine-dark sea"; in addition, he also describes the sea as "grey". William Ewart Gladstone has suggested that this is due to the Ancient Greeks classifying colors primarily by luminosity rather than hue, while others believe Homer was color blind.
The Ancient Indian Wisdom of Veda consider life giving contributions of water a part of divine and recognize water as a primeval God Varuna; and the color of Varuna is described as blue. In the Gayatri associated with Varuna, the word "neela purusha" comes in second line which calls the water deity, the blue one. | 0 | Theoretical and Fundamental Chemistry |
Consider a strong explosion (such as nuclear bombs) that releases a large amount of energy in a small volume during a short time interval. This will create a strong spherical shock wave propagating outwards from the explosion center. The self-similar solution tries to describe the flow when the shock wave has moved through a distance that is extremely large when compared to the size of the explosive. At these large distances, the information about the size and duration of the explosion will be forgotten; only the energy released will have influence on how the shock wave evolves. To a very high degree of accuracy, then it can be assumed that the explosion occurred at a point (say the origin ) instantaneously at time .
The shock wave in the self-similar region is assumed to be still very strong such that the pressure behind the shock wave is very large in comparison with the pressure (atmospheric pressure) in front of the shock wave , which can be neglected from the analysis. Although the pressure of the undisturbed gas is negligible, the density of the undisturbed gas cannot be neglected since the density jump across strong shock waves is finite as a direct consequence of Rankine–Hugoniot conditions. This approximation is equivalent to setting and the corresponding sound speed , but keeping its density non zero, i.e., .
The only parameters available at our disposal are the energy and the undisturbed gas density . The properties behind the shock wave such as are derivable from those in front of the shock wave. The only non-dimensional combination available from and is
It is reasonable to assume that the evolution in and of the shock wave depends only on the above variable. This means that the shock wave location itself will correspond to a particular value, say , of this variable, i.e.,
The propagation velocity of the shock wave is
With the approximation described above, Rankine–Hugoniot conditions determines the gas velocity immediately behind the shock front , and for an ideal gas as follows
where is the specific heat ratio. Since is a constant, the density immediately behind the shock wave is not changing with time, whereas and decrease as and , respectively. | 1 | Applied and Interdisciplinary Chemistry |
In 1975, John H. Beynon was appointed the Royal Society Research Professor and established the Mass Spectrometry Research Unit at Swansea University (at that time known as the University College of Swansea). In 1986, Dai Games moved from Cardiff University to become the Units new Director.
In 1984, the first observation of He was made at the unit, its the same as molecular hydrogen (isolectronic molecules) except it has lots more energy 3310 kJ per mole. | 0 | Theoretical and Fundamental Chemistry |
Potassium sulfides are formed when black powder is burned and are important intermediates in many pyrotechnic effects, such as senko hanabi and some glitter formulations. | 0 | Theoretical and Fundamental Chemistry |
Bacteriorhodopsin is a light-driven H ion transporter found in some haloarchaea, most notably Halobacterium salinarum (formerly known as syn. H. halobium). The proton-motive force generated by the protein is used by ATP synthase to generate adenosine triphosphate (ATP). By expressing bacteriorhodopsin, the archaea cells are able to synthesise ATP in the absence of a carbon source. | 0 | Theoretical and Fundamental Chemistry |
Bases: adenine (A), cytosine (C), guanine (G) and thymine (T) or uracil (U).
Amino acids: Alanine (Ala, A), Arginine (Arg, R), Asparagine (Asn, N), Aspartic acid (Asp, D), Cysteine (Cys, C), Glutamic acid (Glu, E), Glutamine (Gln, Q), Glycine (Gly, G), Histidine (His, H), Isoleucine (Ile, I), Leucine (Leu, L), Lysine (Lys, K), Methionine (Met, M), Phenylalanine (Phe, F), Proline (Pro, P), Serine (Ser, S), Threonine (Thr, T), Tryptophan (Trp, W), Tyrosine (Tyr, Y), Valine (Val, V) | 1 | Applied and Interdisciplinary Chemistry |
Carbon nitrides are compounds consisting only of carbon and nitrogen atoms. Carbon nitrides are also known as organic semiconductors with a band gap of 2.7 eV. Due to its hydrogen-bonding motifs and electron-rich properties, this carbon material is considered a potential candidate for material applications in carbon supplementation. | 0 | Theoretical and Fundamental Chemistry |
Early efforts to use rule-based modeling in simulation of biochemical systems include the stochastic simulation systems StochSim
A widely used tool for rule-based modeling of biochemical networks is BioNetGen It is released under the GNU GPL, version 3. BioNetGen includes a language to describe chemical substances, including the states they can assume and the bindings they can undergo. These rules can be used to create a reaction network model or to perform computer simulations directly on the rule set. The biochemical modeling framework Virtual Cell includes a BioNetGen interpreter.
A close alternative is the Kappa language. Another alternative is BioChemical Space language. | 1 | Applied and Interdisciplinary Chemistry |
Lee's group combines experimental and computational methods to understand mechanisms of reactions important for chemistry and biology. Specifically, Lee has pioneered the use of traditionally physical methods, primarily mass spectrometry and computational chemistry, to tackle problems at the chemistry/biology interface, focusing on catalysis. | 0 | Theoretical and Fundamental Chemistry |
It was envisaged that Taxol (51) could be accessed through tail addition of the Ojima lactam 48 to alcohol 47. Of the four rings of Taxol, the D ring was formed last, the result of a simple intramolecular S2 reaction of hydroxytosylate 38, which could be synthesized from hydroxyketone 27. Formation of the six-membered C ring took place through a Dieckmann condensation of lactone 23, which could be obtained through a Chan rearrangement of carbonate ester 15. Substrate 15 could be derived from ketone 6, which, after several oxidations and rearrangements, could be furnished from commercially available patchoulene oxide 1. | 0 | Theoretical and Fundamental Chemistry |
In an effort to explain the surprising stereoselectivities in the systems above, alternative explanations to the Cieplak effect have been proposed. In substituted cyclohexanones, the tendency of small reducing agents to add hydride axially is proposed to be caused by torsional strain instead of hyperconjugation. In an equatorial attack, the nucleophile approaches by eclipsing a neighboring hydrogen atom and subsequently pushes the carbonyl substituents into eclipsing positions as it pyramidalizes the carbonyl carbon. In an axial approach, the nucleophile approaches gauche to neighboring hydrogen atoms and so does not cause eclipsing interactions while pyramidalizing the carbonyl carbon. It is this torsional strain—the energy cost of rotating the bonds out of an eclipsed position—that favors axial over equatorial approach.
In the case of substituted norbornones, stereoselectivity may be explained by electrostatic interactions between substituents and nucleophiles. Electron-withdrawing groups create a partial positive charge on the alpha carbon, which interacts favorably with the partial negative charge on the incoming nucleophile. This interaction may guide attack syn to the electron-withdrawing substituent, and anti to electron-donating substituents. This conclusion is supported by computations, where modeling the partial charges predicts product distribution without including orbital interactions. The same explanation has been made to justify similar results in the case of substituted adamantones.
Similarly, in Houk's trans-decalone system, the nucleophile with its partial negative charge prefers to attack away from the partial negative charge of the acyl ester. When this substituent is axial, the equatorial pathway brings the nucleophile into closer proximity and is therefore disfavored. This is less pronounced for equatorially substituted ester because the group is now positioned further away from the carbonyl. | 0 | Theoretical and Fundamental Chemistry |
The U.S. National Academy of Medicine (NAM), on behalf of both the U.S. and Canada, sets Dietary Reference Intakes, including Estimated Average Requirements (EARs) and Recommended Dietary Allowances (RDAs), or Adequate Intakes (AIs) for when there is not sufficient information to set EARs and RDAs.
For both males and females under 9 years of age, the AIs for potassium are: 400mg of potassium for 0 to 6-month-old infants, 860mg of potassium for 7 to 12-month-old infants, 2,000mg of potassium for 1 to 3-year-old children, and 2,300mg of potassium for 4 to 8-year-old children.
For males 9 years of age and older, the AIs for potassium are: 2,500mg of potassium for 9 to 13-year-old males, 3,000mg of potassium for 14 to 18-year-old males, and 3,400mg for males that are 19 years of age and older.
For females 9 years of age and older, the AIs for potassium are: 2,300mg of potassium for 9 to 18-year-old females, and 2,600mg of potassium for females that are 19 years of age and older.
For pregnant and lactating females, the AIs for potassium are: 2,600mg of potassium for 14 to 18-year-old pregnant females, 2,900mg for pregnant females that are 19 years of age and older; furthermore, 2,500mg of potassium for 14 to 18-year-old lactating females, and 2,800mg for lactating females that are 19 years of age and older. As for safety, the NAM also sets tolerable upper intake levels (ULs) for vitamins and minerals, but for potassium the evidence was insufficient, so no UL was established.
In 2019, the National Academies of Sciences, Engineering, and Medicine revised the Adequate Intake for potassium to 2,600 mg/day for females 19 years of age and older who are not pregnant or lactating, and 3,400 mg/day for males 19 years of age and older.
The European Food Safety Authority (EFSA) refers to the collective set of information as Dietary Reference Values, with Population Reference Intake (PRI) instead of RDA, and Average Requirement instead of EAR. AI and UL defined the same as in United States. For people ages 15 and older the AI is set at 3,500 mg/day. AIs for pregnancy is 3,500 mg/day, for lactation 4,000 mg/day. For children ages 1–14 years the AIs increase with age from 800 to 2,700 mg/day. These AIs are lower than the U.S. RDAs. The EFSA reviewed the same safety question and decided that there was insufficient data to establish a UL for potassium. | 1 | Applied and Interdisciplinary Chemistry |
Pietro Andrea Mattioli was a renowned botanist and physician. He published a translation of De Materia Medica into Italian in 1544 and ten years later published a work in Latin with all the plants of Dioscorides and 562 woodcut illustrations. It appeared in 1554, printed by Vicenzo Valgrisi, in Venice. Mattioli made a massive contribution to the original text of Pedani's Dioscorides. In some sections Mattioli added information that exceeded 15 times the length of the original text. It resulted in a very big extension of the work, in beauty and information. It was later translated into German, French and Bohemian.
Mattioli held a post in the Imperial Court as physician to Ferdinand II, Archduke of Austria, and the Emperor Maximilian II, Holy Roman Emperor. This position granted him an immense influence. He frequently tested the effects of poisonous plants on prisoners in order to popularize his works. He also affirmed that Jean Ruel had declared some information in the lycopsis chapter of his Materia Medica. This is false, but still Mattioli used it as a reason for attacking Ruel. He did not tolerate either rivals nor corrections. The naturalists and physicians daring to disagree with him, or who had corrected him, were attacked. The list of important characters that were admonished, rebuked, or pursued by the Inquisition contains Wieland, Anguillara, Gesner, Lusitanus and others. This made editions of Matioli's De Materia Medica omnipresent throughout the continent, especially in northern Europe. | 1 | Applied and Interdisciplinary Chemistry |
The rate of substrate utilization is related to the specific growth rate as
where
: X is the total biomass (since the specific growth rate μ is normalized to the total biomass),
: Y is the yield coefficient.
r is negative by convention.
In some applications, several terms of the form [S] / (K + [S]) are multiplied together where more than one nutrient or growth factor has the potential to be limiting (e.g. organic matter and oxygen are both necessary to heterotrophic bacteria). When the yield coefficient, being the ratio of mass of microorganisms to mass of substrate utilized, becomes very large, this signifies that there is deficiency of substrate available for utilization. | 0 | Theoretical and Fundamental Chemistry |
* Wolfram Saenger, Principles of Nucleic Acid Structure, 1984, Springer-Verlag New York Inc.
* Bruce Alberts, Alexander Johnson, Julian Lewis, Martin Raff, Keith Roberts, and Peter Walter Molecular Biology of the Cell, 2007, . Fourth edition is available online through the NCBI Bookshelf: [https://www.ncbi.nlm.nih.gov/bookshelf/br.fcgi?book=mboc4 link]
* Jeremy M Berg, John L Tymoczko, and Lubert Stryer, Biochemistry 5th edition, 2002, W H Freeman. Available online through the NCBI Bookshelf: [https://www.ncbi.nlm.nih.gov/bookshelf/br.fcgi?book=stryer link] | 1 | Applied and Interdisciplinary Chemistry |
In 1896 Zeeman learned that his laboratory had one of Henry Augustus Rowlands highest resolving Rowland grating, an imaging spectrographic mirror. Zeeman had read James Clerk Maxwells article in Encyclopædia Britannica describing Michael Faraday's failed attempts to influence light with magnetism. Zeeman wondered if the new spectrographic techniques could succeed where early efforts had not.
When illuminated by a slit shaped source, the grating produces a long array of slit images corresponding to different wavelengths. Zeeman placed a piece of asbestos soaked in salt water into a Bunsen burner flame at the source of the grating: he could easily see two lines for sodium light emission. Energizing a 10 kilogauss magnet around the flame he observed a slight broadening of the sodium images.
When Zeeman switched to cadmium at the source he observed the images split when the magnet was energized. These splitting could be analyzed with Hendrik Lorentz's then new electron theory. In retrospect we now know that the magnetic effects on sodium require quantum mechanical treatment. Zeeman and Lorentz were awarded the 1902 Nobel prize; in his acceptance speech Zeeman explained his apparatus and showed slides of the spectrographic images. | 0 | Theoretical and Fundamental Chemistry |
Graphite intercalation compounds have fascinated materials scientists for many years owing to their diverse electronic and electrical properties. | 0 | Theoretical and Fundamental Chemistry |
The process of transcriptional termination is less understood in eukaryotes, which have extensive post-transcriptional RNA processing, and each of the three types of eukaryotic RNA polymerase have a different termination system.
In RNA polymerase I, Transcription termination factor, RNA polymerase I binds downstream of the pre-rRNA coding regions, causing the dissociation of the RNA polymerase from the template and the release of the new RNA strand.
In RNA polymerase II, the termination occurs via a polyadenylation/cleaving complex. The 3' tail on the ending of the strand is bound at the polyadenylation site, but the strand will continue to code. The newly synthesised ribonucleotides are removed one at a time by the cleavage factors CSTF and CPSF, in a process that is still not fully understood. The remainder of the strand is disengaged by a 5′-exonuclease when the transcription is finished.
RNA polymerase III terminates after a series of uracil polymerization residues in the transcribed mRNA. Unlike in bacteria and in polymerase I, the termination RNA hairpin needs to be upstream to allow for correct cleaving. | 1 | Applied and Interdisciplinary Chemistry |
In microwave sintering, heat is sometimes generated internally within the material, rather than via surface radiative heat transfer from an external heat source. Some materials fail to couple and others exhibit run-away behavior, so it is restricted in usefulness. A benefit of microwave sintering is faster heating for small loads, meaning less time is needed to reach the sintering temperature, less heating energy is required and there are improvements in the product properties.
A failing of microwave sintering is that it generally sinters only one compact at a time, so overall productivity turns out to be poor except for situations involving one of a kind sintering, such as for artists. As microwaves can only penetrate a short distance in materials with a high conductivity and a high permeability, microwave sintering requires the sample to be delivered in powders with a particle size around the penetration depth of microwaves in the particular material. The sintering process and side-reactions run several times faster during microwave sintering at the same temperature, which results in different properties for the sintered product.
This technique is acknowledged to be quite effective in maintaining fine grains/nano sized grains in sintered bioceramics. Magnesium phosphates and calcium phosphates are the examples which have been processed through the microwave sintering technique. | 1 | Applied and Interdisciplinary Chemistry |
Genes nested opposite the coding sequences of their host genes are very rare, and have been observed in prokaryotes, and more recently, in yeast (S. cerevisiae) and in Tetrahymena thermophila. These non-intronic nested genes remain to be identified in metazoan genomes. As with intronic nested genes, nonintronic nested genes typically do not share functions or expression patterns with their host genes. | 1 | Applied and Interdisciplinary Chemistry |
Through the process of alternative splicing, the CKLF gene encodes 4 CKLF protein isoforms, i.e. proteins made from different areas of the same gene. These isoforms are 1) CKLF1 and CKLF3 proteins that consist of 99 and 67 amino acids, respectively, and are secreted from their parent cells and 2) CKLF2 (which is the full-length product of the CKLF gene) and CKLF4 proteins which consist of 152 and 120 amino acids, respectively, and are located in the membranes of their parent cells. | 1 | Applied and Interdisciplinary Chemistry |
Chromium is claimed to be an essential element involved in the regulation of blood glucose levels within the body. More recent reviews have questioned this, however.
It is believed to interact with the low-molecular weight chromium (LMWCr) binding substance to amplify the action of insulin. Today, the use of chromium as a dietary supplement for the treatment of diabetes mellitus type 2 is still controversial. This is because most of the clinical studies that have been conducted around chromium have been administered only for short periods of time on small sample populations, and have in turn yielded variable findings. To better understand the potential role chromium may play in the treatment of type II diabetes, long-term trials need to be conducted for the future. | 1 | Applied and Interdisciplinary Chemistry |
Plant viruses are viruses that affect plants. Like all other viruses, plant viruses are obligate intracellular parasites that do not have the molecular machinery to replicate without a host. Plant viruses can be pathogenic to vascular plants ("higher plants").
Most plant viruses are rod-shaped, with protein discs forming a tube surrounding the viral genome; isometric particles are another common structure. They rarely have an envelope. The great majority have an RNA genome, which is usually small and single stranded (ss), but some viruses have double-stranded (ds) RNA, ssDNA or dsDNA genomes. Although plant viruses are not as well understood as their animal counterparts, one plant virus has become very recognizable: tobacco mosaic virus (TMV), the first virus to be discovered. This and other viruses cause an estimated US$60 billion loss in crop yields worldwide each year. Plant viruses are grouped into 73 genera and 49 families. However, these figures relate only to cultivated plants, which represent only a tiny fraction of the total number of plant species. Viruses in wild plants have not been well-studied, but the interactions between wild plants and their viruses often do not appear to cause disease in the host plants.
To transmit from one plant to another and from one plant cell to another, plant viruses must use strategies that are usually different from animal viruses. Most plants do not move, and so plant-to-plant transmission usually involves vectors (such as insects). Plant cells are surrounded by solid cell walls, therefore transport through plasmodesmata is the preferred path for virions to move between plant cells. Plants have specialized mechanisms for transporting mRNAs through plasmodesmata, and these mechanisms are thought to be used by RNA viruses to spread from one cell to another. Plant defenses against viral infection include, among other measures, the use of siRNA in response to dsRNA. Most plant viruses encode a protein to suppress this response. Plants also reduce transport through plasmodesmata in response to injury. | 1 | Applied and Interdisciplinary Chemistry |
The equilibrium hypothesis does not stand for very rapid chemical reactions in which the transition state theory breaks down. In such cases involving strongly dipolar, slowly relaxing solvents, solvation of the transition state does not play a very large role in affecting the reaction rate. Instead, dynamic contributions of the solvent (such as friction, density, internal pressure, or viscosity) play a large role in affecting the reaction rate. | 0 | Theoretical and Fundamental Chemistry |
Oxidative addition into cyclopropenes normally occurs at the less hindered position to yield the metallacyclobutane. This reaction can result in formation of cyclopentadienones, cyclohexenones, and phenols. | 0 | Theoretical and Fundamental Chemistry |
The final loaded carbon is removed from the machinery and extracted with a hot alkaline solution of cyanide. The elute solution passes through an electrowinning cell where the gold metal is deposited. The solution then passes back through the loaded carbon, extracting more gold and other metals. This process continues until the carbon has been stripped of its metals.
The cathodes (wire wool, now plated with gold and other metals) are removed and placed in sulfuric, hydrochloric, or nitric acid. The acid burns off the wire wool and other metals such as copper, and leaves a sediment of gold and a solution of acid and dissolved silver. The acid and silver are drained off, after which the gold sediment is washed with water numerous times. | 1 | Applied and Interdisciplinary Chemistry |
Herbertsmithite is one of the most extensively studied QSL candidate materials. It is a mineral with chemical composition ZnCu(OH)Cl and a rhombohedral crystal structure. Notably, the copper ions within this structure form stacked two-dimensional layers of kagome lattices. Additionally, superexchange over the oxygen bonds creates a strong antiferromagnetic interaction between the copper spins within a single layer, whereas coupling between layers is negligible. Therefore, it is a good realization of the antiferromagnetic spin-1/2 Heisenberg model on the kagome lattice, which is a prototypical theoretical example of a quantum spin liquid.
Synthetic, polycrystalline herbertsmithite powder was first reported in 2005, and initial magnetic susceptibility studies showed no signs of magnetic order down to 2K. In a subsequent study, the absence of magnetic order was verified down to 50 mK, inelastic neutron scattering measurements revealed a broad spectrum of low energy spin excitations, and low-temperature specific heat measurements had power law scaling. This gave compelling evidence for a spin liquid state with gapless spinon excitations. A broad array of additional experiments, including O NMR, and neutron spectroscopy of the dynamic magnetic structure factor, reinforced the identification of herbertsmithite as a gapless spin liquid material, although the exact characterization remained unclear as of 2010.
Large (millimeter size) single crystals of herbertsmithite were grown and characterized in 2011. These enabled more precise measurements of possible spin liquid properties. In particular, momentum-resolved inelastic neutron scattering experiments showed a broad continuum of excitations. This was interpreted as evidence for gapless, fractionalized spinons. Follow-up experiments (using O NMR and high-resolution, low-energy neutron scattering) refined this picture and determined there was actually a small spinon excitation gap of 0.07–0.09 meV.
Some measurements were suggestive of quantum critical behavior. Magnetic response of this material displays scaling relation in both the bulk ac susceptibility and the low energy dynamic susceptibility, with the low temperature heat capacity strongly depending on magnetic field. This scaling is seen in certain quantum antiferromagnets, heavy-fermion metals, and two-dimensional He as a signature of proximity to a quantum critical point.
In 2020, monodisperse single-crystal nanoparticles of herbertsmithite (~10 nm) were synthesized at room temperature, using gas-diffusion electrocrystallization, showing that their spin liquid nature persists at such small dimensions.
It may realize a U(1)-Dirac spin liquid. | 0 | Theoretical and Fundamental Chemistry |
The Caspian has characteristics common to both seas and lakes. It is often listed as the world's largest lake, although it is not freshwater: the 1.2% salinity classes it with brackish water bodies.
It contains about 3.5 times as much water, by volume, as all five of North Americas Great Lakes combined. The Volga River (about 80% of the inflow) and the Ural River discharge into the Caspian Sea, but it has no natural outflow other than by evaporation. Thus the Caspian ecosystem is a closed basin, with its own sea level history that is independent of the eustatic level of the worlds oceans.
The sea level of the Caspian has fallen and risen, often rapidly, many times over the centuries. Some Russian historians claim that a medieval rising of the Caspian, perhaps caused by the Amu Darya changing its inflow to the Caspian from the 13th century to the 16th century, caused the coastal towns of Khazaria, such as Atil, to flood. In 2004, the water level was below sea level.
Over the centuries, Caspian Sea levels have changed in synchrony with the estimated discharge of the Volga, which in turn depends on rainfall levels in its vast catchment basin. Precipitation is related to variations in the amount of North Atlantic depressions that reach the interior, and they in turn are affected by cycles of the North Atlantic oscillation. Thus levels in the Caspian Sea relate to atmospheric conditions in the North Atlantic, thousands of kilometres to the northwest.
The last short-term sea-level cycle started with a sea-level fall of from 1929 to 1977, followed by a rise of from 1977 until 1995. Since then smaller oscillations have taken place.
A study by the Azerbaijan Academy of Sciences estimated that the level of the sea was dropping by more than six centimetres per year due to increased evaporation due to rising temperatures caused by climate change. | 1 | Applied and Interdisciplinary Chemistry |
The formation of raw iron ore pellets, also known as pelletizing, has the objective of producing pellets in an appropriate band of sizes and with mechanical properties high usefulness during the stresses of transference, transport, and use. For example, waste materials are ground before being heated and introduced into a press for compression. Both mechanical force and thermal processes are used to produce the correct pellet properties. From an equipment point of view there are two alternatives for industrial production of iron ore pellets: the drum and the pelletizing disk. | 1 | Applied and Interdisciplinary Chemistry |
;Woven wire mesh sieves
Woven wire mesh sieves are according to technical requirements of ISO 3310-1. These sieves usually have nominal aperture ranging from 20 micrometers to 3.55 millimeters, with diameters ranging from 100 to 450 millimeters.
;Perforated plate sieves
Perforated plate sieves conform to ISO 3310-2 and can have round or square nominal apertures ranging from 1 millimeter to 125 millimeters. The diameters of the sieves range from 200 to 450 millimeters.
;American standard sieves
American standard sieves also known as ASTM sieves conform to ASTM E11 standard. The nominal aperture of these sieves range from 20 micrometers to 200 millimeters, however these sieves have only and diameter sizes. | 1 | Applied and Interdisciplinary Chemistry |
Often a multi-disciplinary approach is taken in compiling all the components of a Phase I study, since skills in chemistry, atmospheric physics, geology, microbiology and even botany are frequently required. Many of the preparers are environmental scientists who have been trained to integrate these diverse disciplines. Many states have professional registrations which are applicable to the preparers of Phase I ESAs; for example, the state of California had a registration entitled "California Registered Environmental Assessor Class I or Class II" until July 2012, when it removed this REA certification program due to budget cuts.
Under ASTM E 1527-13 parameters were set forth as to who is qualified to perform Phase I ESAs. An Environmental Professional is someone with:
# a current Professional Engineers or Professional Geologists license or registration from a state or U.S. territory with 3 years equivalent full-time experience; or
# a Baccalaureate or higher degree from an accredited institution of higher education in a discipline of engineering or science and 5 years equivalent full-time experience; or
# have the equivalent of 10 years full-time experience.
A person not meeting one or more of those qualifications may assist in the conduct of a Phase I ESA if the individual is under the supervision or responsible charge of a person meeting the definition of an Environmental Professional when concluding such activities.
Most site assessments are conducted by private companies independent of the owner or potential purchaser of the land. | 1 | Applied and Interdisciplinary Chemistry |
Precondition for the applicability of sensor-based ore sorting is the presence of liberation at the particle size of interest. Before entering into sensor-based ore sorting testing procedures there is the possibility to assess the degree of liberation through the inspection of drill cores, hand-counting and washability analysis. The quantification of liberation does not include any process efficiencies, but gives an estimate of the possible sorting result and can thus be applied for desktop financial feasibility analysis.
Drill core analysis
Both for green-field and brown-field applications, inspection of drill core in combination with the grade distribution and mineralogical description is a good option for estimation of the liberation characteristics and the possible success of sensor-based ore sorting. In combination with the mining method and mine plan, an estimation of possible grade distribution in coarse particles can be done. | 0 | Theoretical and Fundamental Chemistry |
G proteins, also known as guanine nucleotide-binding proteins, are a family of proteins that act as molecular switches inside cells, and are involved in transmitting signals from a variety of stimuli outside a cell to its interior. Their activity is regulated by factors that control their ability to bind to and hydrolyze guanosine triphosphate (GTP) to guanosine diphosphate (GDP). When they are bound to GTP, they are on, and, when they are bound to GDP, they are off. G proteins belong to the larger group of enzymes called GTPases.
There are two classes of G proteins. The first function as monomeric small GTPases (small G-proteins), while the second function as heterotrimeric G protein complexes. The latter class of complexes is made up of alpha (G), beta (G) and gamma (G) subunits. In addition, the beta and gamma subunits can form a stable dimeric complex referred to as the beta-gamma complex
Heterotrimeric G proteins located within the cell are activated by G protein-coupled receptors (GPCRs) that span the cell membrane. Signaling molecules bind to a domain of the GPCR located outside the cell, and an intracellular GPCR domain then in turn activates a particular G protein. Some active-state GPCRs have also been shown to be "pre-coupled" with G proteins, whereas in other cases a collision coupling mechanism is thought to occur. The G protein triggers a cascade of further signaling events that finally results in a change in cell function. G protein-coupled receptors and G proteins working together transmit signals from many hormones, neurotransmitters, and other signaling factors. G proteins regulate metabolic enzymes, ion channels, transporter proteins, and other parts of the cell machinery, controlling transcription, motility, contractility, and secretion, which in turn regulate diverse systemic functions such as embryonic development, learning and memory, and homeostasis. | 1 | Applied and Interdisciplinary Chemistry |
In the work Life of Apollonius by Philostratus the Athenian, an allegorical description is given of an occult hill. The author gives this hill the name "Athanor".
"Athanor" is the name of two works by 20th century German artist Anselm Kiefer: one currently displayed in the Toledo Museum of Art and the other commissioned by the Louvre museum in 2007 and displayed there. The word was also used the title of a 1968 book of poetry by the Romanian author Gellu Naum, a musical work for orchestra by French composer Joël-François Durand (written in 2001 and premiered by the BBC Symphony Orchestra in 2003), a 1990s noel series by American author Jane Lindskold, a photo collage by Romanian artist Geta Bratescu (b. 1926), and an artwork by Janet Saad-Cook located at Boston University's Photonics Center.
The Athanor Academy of Performing Arts Passau founded in 1995 in the German town Passau is named after this furnace, as is the Belgian , a Masonic Lodge.
The Athanor magazine is a review of language philosophy, history, and international politics, published once or twice a year. | 1 | Applied and Interdisciplinary Chemistry |
Early items designed and produced by Friedrich Deusch are very classical, and this was followed by an abstract phase of Art Déco in its purest form. From the 1950s, it was more a concrete style with flowers and so forth. Deusch applied silver overlay to vases, plates, coffee and tea services, and other items.
From the outset, the firm of Alfred Veyhl had its own style. It was mostly the combination of polychromatic painted details of birds, flowers, and similar motifs, framed with silver.
The more abstract designs are rare. Alfred, and later his son Manfred Veyhl, were the only ones who used a varnish to avoid silver oxidation. Alfred used more softer and rounder lines in his designs, whereas Manfred had a more angular, expressive style. A specialty for this company was that clients could choose from a certain range of porcelain forms and décors. The items were then produced exclusively in a single production run.
An outstanding figure is Friedrich Wilhelm Spahr. There is evidence that he learned his skill from Friedrich Deusch (some items of both firms have very similar formal designs). He was not only an artisan but an artist in developing repeating circumferential forms in a perfect and harmonic proportion. Very often it is the pure arrangement of lines (curved or straight), or their combination, with flowers or birds. Never over-designed, but enough to divide the small surface (for example of a vase) in a self-evident and harmonious way. Like the others, not only did he design and apply the silver overlay, he also prepared the porcelain with his own enamel colors, painted the motifs and engraved the silver. Of course he did not produce all these items by himself. Spahr's factory employed about forty specialized workers. The outstanding engraved pieces show the unrivaled quality of Spahr.
The early items typically have a thicker silver layer. One can also see the stroke of the brush which proves the overlay and painted surface were handcrafted. Printed designs were used more often on items produced later, especially those of Manfred Vehyl. These can be recognized by studying the design: if the color is flat and full of small dots, this strongly indicates a printed design. Also, the silver work on printed color designs appears not to cover the design closely, as it should.
The three companies bought and used porcelain blanks from several well known producers such as Rosenthal, Hutschenreuther, Thomas Bavaria, Krautheim & Adelberg and marketed the finished products under their own names. They also produced silver overlay glass in the same manner. A large amount of glassware came from WMF in Geislingen, which is not far from Schwäbisch Gmünd. A respectable amount of glass to be overlaid also came from Jean Beck, a famous glass designer in Munich. Until recently, it was believed that Beck created the brilliant silver designs himself and that Deusch only produced them. However, this was not the case. As with the porcelain, Deusch and others bought the delightfully stylized glass blanks, decorated them in silver overlay, and sold them under their own names. | 1 | Applied and Interdisciplinary Chemistry |
In fluid dynamics, a moving shock is a shock wave that is travelling through a fluid (often gaseous) medium with a velocity relative to the velocity of the fluid already making up the medium. As such, the normal shock relations require modification to calculate the properties before and after the moving shock. A knowledge of moving shocks is important for studying the phenomena surrounding detonation, among other applications. | 1 | Applied and Interdisciplinary Chemistry |
Surface tension of a liquid is the force per unit length. In the illustration on the right, the rectangular frame, composed of three unmovable sides (black) that form a "U" shape, and a fourth movable side (blue) that can slide to the right. Surface tension will pull the blue bar to the left; the force required to hold the movable side is proportional to the length of the immobile side. Thus the ratio depends only on the intrinsic properties of the liquid (composition, temperature, etc.), not on its geometry. For example, if the frame had a more complicated shape, the ratio , with the length of the movable side and the force required to stop it from sliding, is found to be the same for all shapes. We therefore define the surface tension as
The reason for the is that the film has two sides (two surfaces), each of which contributes equally to the force; so the force contributed by a single side is . | 0 | Theoretical and Fundamental Chemistry |
ACh is always used as the neurotransmitter within the autonomic ganglion. Nicotinic receptors on the postganglionic neuron are responsible for the initial fast depolarization (Fast EPSP) of that neuron. As a consequence of this, nicotinic receptors are often cited as the receptor on the postganglionic neurons at the ganglion. However, the subsequent hyperpolarization (IPSP) and slow depolarization (Slow EPSP) that represent the recovery of the postganglionic neuron from stimulation are actually mediated by muscarinic receptors, types M and M respectively (discussed below).
Peripheral autonomic fibers (sympathetic and parasympathetic fibers) are categorized anatomically as either preganglionic or postganglionic fibers, then further generalized as either adrenergic fibers, releasing noradrenaline, or cholinergic fibers, both releasing acetylcholine and expressing acetylcholine receptors. Both preganglionic sympathetic fibers and preganglionic parasympathetic fibers are cholinergic. Most postganglionic sympathetic fibers are adrenergic: their neurotransmitter is norepinephrine except postganglionic sympathetic fibers to the sweat glands, piloerectile muscles of the body hairs, and the skeletal muscle arterioles do not use adrenaline/noradrenaline.
The adrenal medulla is considered a sympathetic ganglion and, like other sympathetic ganglia, is supplied by cholinergic preganglionic sympathetic fibers: acetylcholine is the neurotransmitter utilized at this synapse. The chromaffin cells of the adrenal medulla act as "modified neurons", releasing adrenaline and noradrenaline into the bloodstream as hormones instead of as neurotransmitters. The other postganglionic fibers of the peripheral autonomic system belong to the parasympathetic division; all are cholinergic fibers, and use acetylcholine as the neurotransmitter. | 1 | Applied and Interdisciplinary Chemistry |
ISO 7027:1999 is an ISO standard for water quality that enables the determination of turbidity. The ISO 7027 technique is used to determine the concentration of suspended particles in a sample of water by measuring the incident light scattered at right angles from the sample. The scattered light is captured by a photodiode, which produces an electronic signal that is converted to a turbidity. | 0 | Theoretical and Fundamental Chemistry |
Adhesives commonly react with oxygen at low temperatures, which leads to a slow break down of polymer chains. The breakdown of polymer chains is often undetectable until the adhesive has reached a critical point where the stability of remainder of the adhesive rapidly degrades. High temperature accelerated testing often cannot be used to estimate stability in oxygen environments since high temperatures often lead to new reaction pathways that would not typically exist at the temperature the adhesives would be used.
Moisture sensitivity accelerated tests involve either increased temperatures or increased surface area of a sample. The surface area of samples is increased by applying adhesives to a single surface rather than placing it between two surfaces and placing the sample in a water bath. | 0 | Theoretical and Fundamental Chemistry |
Unlike other GDNF family of ligands, persephin only contains one RXXR cleavage site, rather than multiple, indicating that it can only make one length of functional peptide. | 1 | Applied and Interdisciplinary Chemistry |
The crushed ore is irrigated with a dilute alkaline cyanide solution. The solution containing the dissolved precious metals in a pregnant solution continues percolating through the crushed ore until it reaches the liner at the bottom of the heap where it drains into a storage (pregnant solution) pond. After separating the precious metals from the pregnant solution, the dilute cyanide solution (now called "barren solution") is normally re-used in the heap-leach-process or occasionally sent to an industrial water treatment facility where the residual cyanide is treated and residual metals are removed. In very high rainfall areas, such as the tropics, in some cases there is surplus water that is then discharged to the environment, after treatment, posing possible water pollution if treatment is not properly carried out.
The production of one gold ring through this method, can generate 20 tons of waste material.
During the extraction phase, the gold ions form complex ions with the cyanide:
Recuperation of the gold is readily achieved with a redox-reaction:
The most common methods to remove the gold from solution are either using activated carbon to selectively absorb it, or the Merrill-Crowe process where zinc powder is added to cause a precipitation of gold and zinc. The fine product can be either doré (gold-silver bars) or zinc-gold sludge that is then refined elsewhere. | 1 | Applied and Interdisciplinary Chemistry |
Immunogold labeling or immunogold staining (IGS) is a staining technique used in electron microscopy. This staining technique is an equivalent of the indirect immunofluorescence technique for visible light. Colloidal gold particles are most often attached to secondary antibodies which are in turn attached to primary antibodies designed to bind a specific antigen or other cell component. Gold is used for its high electron density which increases electron scatter to give high contrast dark spots.
First used in 1971, immunogold labeling has been applied to both transmission electron microscopy and scanning electron microscopy, as well as brightfield microscopy. The labeling technique can be adapted to distinguish multiple objects by using differently-sized gold particles.
Immunogold labeling can introduce artifacts, as the gold particles reside some distance from the labelled object and very thin sectioning is required during sample preparation. | 1 | Applied and Interdisciplinary Chemistry |
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