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Most scientific studies have found no link between uranium and birth defects, but some claim statistical correlations between soldiers exposed to DU, and those who were not, concerning reproductive abnormalities.
One study found epidemiological evidence for increased risk of birth defects in the offspring of persons exposed to DU. Several sources have attributed an increased rate of birth defects in the children of Gulf War veterans and in Iraqis to inhalation of depleted uranium. A 2001 study of 15,000 Gulf War combat veterans and 15,000 control veterans found that the Gulf War veterans were 1.8 (fathers) to 2.8 (mothers) times more likely to have children with birth defects.
A study of Gulf War Veterans from the UK found a 50% increased risk of malformed pregnancies reported by men over non-Gulf War veterans. The study did not find correlations between Gulf war deployment and other birth defects such as stillbirth, chromosomal malformations, or congenital syndromes. The fathers service in the Gulf War was associated with increased rate of miscarriage, but the mothers service was not. | 0 | Theoretical and Fundamental Chemistry |
Pol II-transcribed genes contain a region in the immediate vicinity of the transcription start site (TSS) that binds and positions the preinitiation complex. This region is called the core promoter because of its essential role in transcription initiation. Different classes of sequence elements are found in the promoters. For example, the TATA box is the highly conserved DNA recognition sequence for the TATA box binding protein, TBP, whose binding initiates transcription complex assembly at many genes.
Eukaryotic genes also contain regulatory sequences beyond the core promoter. These cis-acting control elements bind transcriptional activators or repressors to increase or decrease transcription from the core promoter. Well-characterized regulatory elements include enhancers, silencers, and insulators. These regulatory sequences can be spread over a large genomic distance, sometimes located hundreds of kilobases from the core promoters.
General transcription factors are a group of proteins involved in transcription initiation and regulation. These factors typically have DNA-binding domains that bind specific sequence elements of the core promoter and help recruit RNA polymerase to the transcriptional start site.
General transcription factors for RNA polymerase II include TFIID, TFIIA, TFIIB, TFIIF, TFIIE, and TFIIH. | 1 | Applied and Interdisciplinary Chemistry |
Sodium hydroxide is industrially produced as a 50% solution by variations of the electrolytic chloralkali process. Chlorine gas is also produced in this process. Solid sodium hydroxide is obtained from this solution by the evaporation of water. Solid sodium hydroxide is most commonly sold as flakes, prills, and cast blocks.
In 2004, world production was estimated at 60 million dry tonnes of sodium hydroxide, and demand was estimated at 51 million tonnes. In 1998, total world production was around 45 million tonnes. North America and Asia each contributed around 14 million tonnes, while Europe produced around 10 million tonnes. In the United States, the major producer of sodium hydroxide is Olin, which has annual production around 5.7 million tonnes from sites at Freeport, Texas; Plaquemine, Louisiana; St. Gabriel, Louisiana; McIntosh, Alabama; Charleston, Tennessee; Niagara Falls, New York; and Bécancour, Canada. Other major US producers include Oxychem, Westlake, Shintek, and Formosa. All of these companies use the chloralkali process.
Historically, sodium hydroxide was produced by treating sodium carbonate with calcium hydroxide in a metathesis reaction which takes advantage of the fact that sodium hydroxide is soluble, while calcium carbonate is not. This process was called causticizing.
This process was superseded by the Solvay process in the late 19th century, which was in turn supplanted by the Leblanc process and then chloralkali process which is in use today.
Sodium hydroxide is also produced by combining pure sodium metal with water. The byproducts are hydrogen gas and heat, often resulting in a flame.
This reaction is commonly used for demonstrating the reactivity of alkali metals in academic environments; however, it is not commercially viable, as the isolation of sodium metal is typically performed by reduction or electrolysis of sodium compounds including sodium hydroxide. | 0 | Theoretical and Fundamental Chemistry |
The American History Museum of the Smithsonian has several spinthariscopes in its collections, and an article discussing them. However, none are currently on display. | 0 | Theoretical and Fundamental Chemistry |
Upon binding of LH to the external part of the membrane spanning receptor, a transduction of the signal takes place. This process results in the activation of a heterotrimeric G protein. Binding of LH to the receptor shifts its conformation. The activated receptor promotes the binding of GTP to the G protein and its subsequent activation. After binding GTP, the G protein heterotrimer detaches from the receptor and disassembles. The alpha-subunit Gs binds adenylate cyclase and activates the cAMP system.
It is believed that a receptor molecule exists in a conformational equilibrium between active and inactive states. The binding of LH (or CG) to the receptor shifts the equilibrium towards the active form of the receptor. For a cell to respond to LH only a small percentage (≈1%) of receptor sites need to be activated. | 1 | Applied and Interdisciplinary Chemistry |
RAPD markers are decamer (10 nucleotides long) DNA fragments from PCR amplification of random segments of genomic DNA with a single primer of arbitrary nucleotide sequence and which are able to differentiate between genetically distinct individuals, although not necessarily in a reproducible way.
It is used to analyze the genetic diversity of an individual by using random primers. Due to problems in experiment reproducibility, many scientific journals do not accept experiments merely based on RAPDs anymore.
RAPD requires only one primer for amplification. | 1 | Applied and Interdisciplinary Chemistry |
Sulfide is an angular functional group, the C–S–C angle approaching 90° The C–S bonds are about 180 pm.
For the prototype, dimethylsulfide, the C-S-C angles is 99°, which is smaller than the C-O-C angle in ether (~110°). The C-S distance in dimethylsulfide is 1.81 Å.
Sulfides are characterized by their strong odors, which are similar to thiol odor. This odor limits the applications of volatile sulfides. In terms of their physical properties they resemble ethers, but are less volatile, higher melting, and less hydrophilic. These properties follow from the polarizability of the divalent sulfur center, which is greater than that for oxygen in ethers. | 0 | Theoretical and Fundamental Chemistry |
An induction furnace consists of a nonconductive crucible holding the charge of metal to be melted, surrounded by a coil of copper wire. A powerful alternating current flows through the wire. The coil creates a rapidly reversing magnetic field that penetrates the metal. The magnetic field induces eddy currents, circular electric currents, inside the metal, by electromagnetic induction. The eddy currents, flowing through the electrical resistance of the bulk metal, heat it by Joule heating. In ferromagnetic materials like iron, the material may also be heated by magnetic hysteresis, the reversal of the molecular magnetic dipoles in the metal. Once melted, the eddy currents cause vigorous stirring of the melt, assuring good mixing.
An advantage of induction heating is that the heat is generated within the furnace's charge itself rather than applied by a burning fuel or other external heat source, which can be important in applications where contamination is an issue.
Operating frequencies range from utility frequency (50 or 60 Hz) to 400 kHz or higher, usually depending on the material being melted, the capacity (volume) of the furnace and the melting speed required. Generally, the smaller the volume of the melts, the higher the frequency of the furnace used; this is due to the skin depth which is a measure of the distance an alternating current can penetrate beneath the surface of a conductor. For the same conductivity, the higher frequencies have a shallow skin depth—that is less penetration into the melt. Lower frequencies can generate stirring or turbulence in the metal.
A preheated, one-ton furnace melting iron can melt cold charge to tapping readiness within an hour. Power supplies range from 10 kW to 42 MW, with melt sizes of 20 kg to 65 tons of metal respectively.
An operating induction furnace usually emits a hum or whine (due to fluctuating magnetic forces and magnetostriction), the pitch of which can be used by operators to identify whether the furnace is operating correctly or at what power level. | 1 | Applied and Interdisciplinary Chemistry |
Wetlands are frequently applied to solve the issue of eutrophication. Nitrate is transformed in wetlands to free nitrogen and discharged to the air. Phosphorus is adsorbed by wetland soils which are taken up by the plants. Therefore, wetlands could help to reduce the concentration of nitrogen and phosphorus to remit and solve the eutrophication. However, wetland soils can only hold a limited amount of phosphorus. To remove phosphorus continually, it is necessary to add more new soils within the wetland from remnant plant stems, leaves, root debris, and undecomposable parts of dead algae, bacteria, fungi, and invertebrates. | 0 | Theoretical and Fundamental Chemistry |
Fallout comes in two varieties. The first is a small amount of carcinogenic material with a long half-life. The second, depending on the height of detonation, is a large quantity of radioactive dust and sand with a short half-life.
All nuclear explosions produce fission products, un-fissioned nuclear material, and weapon residues vaporized by the heat of the fireball. These materials are limited to the original mass of the device, but include radioisotopes with long lives. When the nuclear fireball does not reach the ground, this is the only fallout produced. Its amount can be estimated from the fission-fusion design and yield of the weapon. | 0 | Theoretical and Fundamental Chemistry |
The latter stages of the revolution was fuelled by the 1789 publication of Lavoisiers Traité Élémentaire de Chimie (Elements of Chemistry). Beginning with this publication and others to follow, Lavoisier synthesised the work of others and coined the term "oxygen". Antoine Lavoisier represented the chemical revolution not only in his publications, but also in the way he practiced chemistry. Lavoisiers work was characterized by his systematic determination of weights and his strong emphasis on precision and accuracy. While it has been postulated that the law of conservation of mass was discovered by Lavoisier, this claim has been refuted by scientist Marcellin Berthelot. Earlier use of the law of conservation of mass has been suggested by Henry Guerlac, noting that scientist Jan Baptist van Helmont had implicitly applied the methodology to his work in the 16th and 17th centuries. Earlier references of the law of conservation of mass and its use were made by Jean Rey in 1630. Although the law of conservation of mass was not explicitly discovered by Lavoisier, his work with a wider array of materials than what most scientists had available at the time allowed his work to greatly expand the boundaries of the principle and its fundamentals.
Lavoisier also contributed to chemistry a method of understanding combustion and respiration and proof of the composition of water by decomposition into its constituent parts. He explained the theory of combustion, and challenged the phlogiston theory with his views on caloric. The Traité incorporates notions of a "new chemistry" and describes the experiments and reasoning that led to his conclusions. Like Newtons Principia, which was the high point of the Scientific Revolution, Lavoisiers Traité can be seen as the culmination of the Chemical Revolution.
Lavoisiers work was not immediately accepted and it took several decades for it gain momentum. This transition was aided by the work of Jöns Jakob Berzelius, who came up with a simplified shorthand to describe chemical compounds based on John Daltons theory of atomic weights. Many people credit Lavoisier and his overthrow of phlogiston theory as the traditional chemical revolution, with Lavoisier marking the beginning of the revolution and John Dalton marking its culmination. | 1 | Applied and Interdisciplinary Chemistry |
Geometrical isomers of carboranes can exist on the basis of the various locations of carbon within the cage. Isomers necessitate the use of the numerical prefixes in a compounds name. The closo'-dicarbadecaborane can exist in three isomers: 1,2-, 1,7-, and 1,12-. | 0 | Theoretical and Fundamental Chemistry |
Heteroleptic complexes containing chloride are numerous. Most hydrated metal halides are members of this class. Hexamminecobalt(III) chloride and Cisplatin (cis-Pt(NH)Cl) are prominent examples of metal-ammine-chlorides. | 0 | Theoretical and Fundamental Chemistry |
A typical pressure injection cell holds a micro-tube or a vial in its central chamber. A small magnetic stir bar can be used to keep the particles in suspension. | 0 | Theoretical and Fundamental Chemistry |
In organic chemistry, a homologous series is a sequence of compounds with the same functional group and similar chemical properties in which the members of the series can be branched or unbranched, or differ by molecular formula of and molecular mass of 14u. This can be the length of a carbon chain, for example in the straight-chained alkanes (paraffins), or it could be the number of monomers in a homopolymer such as amylose. A homologue (also spelled as homolog) is a compound belonging to a homologous series.
Compounds within a homologous series typically have a fixed set of functional groups that gives them similar chemical and physical properties. (For example, the series of primary straight-chained alcohols has a hydroxyl at the end of the carbon chain.) These properties typically change gradually along the series, and the changes can often be explained by mere differences in molecular size and mass. The name "homologous series" is also often used for any collection of compounds that have similar structures or include the same functional group, such as the general alkanes (straight and branched), the alkenes (olefins), the carbohydrates, etc. However, if the members cannot be arranged in a linear order by a single parameter, the collection may be better called a "chemical family" or "class of homologous compounds" than a "series".
The concept of homologous series was proposed in 1843 by the French chemist Charles Gerhardt. A homologation reaction is a chemical process that converts one member of a homologous series to the next member. | 0 | Theoretical and Fundamental Chemistry |
A reaction rate can have a negative partial order with respect to a substance. For example, the conversion of ozone (O) to oxygen follows the rate equation in an excess of oxygen. This corresponds to second order in ozone and order (−1) with respect to oxygen.
When a partial order is negative, the overall order is usually considered as undefined. In the above example, for instance, the reaction is not described as first order even though the sum of the partial orders is , because the rate equation is more complex than that of a simple first-order reaction. | 0 | Theoretical and Fundamental Chemistry |
The planets of the Solar System are divided into two groups: the four inner planets are the terrestrial planets (Mercury, Venus, Earth and Mars), with relatively small sizes and rocky surfaces. The four outer planets are the giant planets, which are dominated by hydrogen and helium and have lower mean densities. These can be further subdivided into the gas giants (Jupiter and Saturn) and the ice giants (Uranus and Neptune) that have large icy cores.
Most of our direct information on the composition of the giant planets is from spectroscopy. Since the 1930s, Jupiter was known to contain hydrogen, methane and ammonium. In the 1960s, interferometry greatly increased the resolution and sensitivity of spectral analysis, allowing the identification of a much greater collection of molecules including ethane, acetylene, water and carbon monoxide. However, Earth-based spectroscopy becomes increasingly difficult with more remote planets, since the reflected light of the Sun is much dimmer; and spectroscopic analysis of light from the planets can only be used to detect vibrations of molecules, which are in the infrared frequency range. This constrains the abundances of the elements H, C and N. Two other elements are detected: phosphorus in the gas phosphine (PH) and germanium in germane (GeH).
The helium atom has vibrations in the ultraviolet range, which is strongly absorbed by the atmospheres of the outer planets and Earth. Thus, despite its abundance, helium was only detected once spacecraft were sent to the outer planets, and then only indirectly through collision-induced absorption in hydrogen molecules. Further information on Jupiter was obtained from the Galileo probe when it was sent into the atmosphere in 1995; and the final mission of the Cassini probe in 2017 was to enter the atmosphere of Saturn. In the atmosphere of Jupiter, He was found to be depleted by a factor of 2 compared to solar composition and Ne by a factor of 10, a surprising result since the other noble gases and the elements C, N and S were enhanced by factors of 2 to 4 (oxygen was also depleted but this was attributed to the unusually dry region that Galileo sampled).
Spectroscopic methods only penetrate the atmospheres of Jupiter and Saturn to depths where the pressure is about equal to 1 bar, approximately Earth's atmospheric pressure at sea level. The Galileo probe penetrated to 22 bars. This is a small fraction of the planet, which is expected to reach pressures of over 40 Mbar. To constrain the composition in the interior, thermodynamic models are constructed using the information on temperature from infrared emission spectra and equations of state for the likely compositions. High-pressure experiments predict that hydrogen will be a metallic liquid in the interior of Jupiter and Saturn, while in Uranus and Neptune it remains in the molecular state. Estimates also depend on models for the formation of the planets. Condensation of the presolar nebula would result in a gaseous planet with the same composition as the Sun, but the planets could also have formed when a solid core captured nebular gas.
In current models, the four giant planets have cores of rock and ice that are roughly the same size, but the proportion of hydrogen and helium decreases from about 300 Earth masses in Jupiter to 75 in Saturn and just a few in Uranus and Neptune. Thus, while the gas giants are primarily composed of hydrogen and helium, the ice giants are primarily composed of heavier elements (O, C, N, S), primarily in the form of water, methane, and ammonia. The surfaces are cold enough for molecular hydrogen to be liquid, so much of each planet is likely a hydrogen ocean overlaying one of heavier compounds. Outside the core, Jupiter has a mantle of liquid metallic hydrogen and an atmosphere of molecular hydrogen and helium. Metallic hydrogen does not mix well with helium, and in Saturn, it may form a separate layer below the metallic hydrogen. | 0 | Theoretical and Fundamental Chemistry |
Testican is a type of proteoglycan. Testican-1 is a highly conserved, multidomain proteoglycan that is most prominently expressed in the thalamus, and is upregulated in activated astroglial cells of the cerebrum. Several functions of this gene product have now been demonstrated in vitro including membrane-type matrix metalloproteinase inhibition, cathepsin L inhibition, and low-affinity calcium binding. The purified gene product has been shown to inhibit cell attachment and neurite extensions in culture. Functions of testican in vivo have yet to be demonstrated in knockout mice or other models. Testican has been shown to carry substantial amounts of chondroitin sulfate as well as other oligosaccharides, but the biological significance of these embellishments is not yet known.
In humans there are three testicans:
* SPOCK1 (Testican 1)
* SPOCK2 (Testican 2)
* SPOCK3 (Testican 3)
Testican-1 plays a role in lapatinib resistance, which is a drug used to treat HER2-positive gastric cancer. When testican-1 levels are artificially reduced, sensitivity towards lapatinib was once again increased. This shows the potential for future use in combating drug resistance. | 1 | Applied and Interdisciplinary Chemistry |
The full 3D representation of crystallographic texture is given by the orientation distribution function (ODF) which can be achieved through evaluation of a set of pole figures or diffraction patterns. Subsequently, all pole figures can be derived from the ODF.
The ODF is defined as the volume fraction of grains with a certain orientation .
The orientation is normally identified using three Euler angles. The Euler angles then describe the transition from the sample’s reference frame into the crystallographic reference frame of each individual grain of the polycrystal. One thus ends up with a large set of different Euler angles, the distribution of which is described by the ODF.
The orientation distribution function, ODF, cannot be measured directly by any technique. Traditionally both X-ray diffraction and EBSD may collect pole figures. Different methodologies exist to obtain the ODF from the pole figures or data in general. They can be classified based on how they represent the ODF. Some represent the ODF as a function, sum of functions or expand it in a series of harmonic functions. Others, known as discrete methods, divide the ODF space in cells and focus on determining the value of the ODF in each cell. | 1 | Applied and Interdisciplinary Chemistry |
The bacterial RNA polymerase, a leading enzyme involved in formation of a transcription bubble, uses DNA template to guide RNA synthesis. It is present in two main forms: as a core enzyme, when it is inactive, and as a holoenzyme, when it is activated. A sigma (σ) factor is a subunit that assists the process of transcription and it stabilizes the transcription bubble when it binds to unpaired bases. These two components, RNA polymerase and sigma factor, when paired together, build RNA polymerase holoenzyme which is then in its active form and ready to bind to a promoter and initiate DNA transcription. Once it binds to the DNA, RNA polymerase turns from a closed to an open complex, forming the transcription bubble. RNA polymerase synthesizes the new RNA in the 5 to 3 direction by adding complementary bases to the 3' end of a new strand. The holoenzyme composition dissociates after transcription initiation, where the σ factor disengages the complex and the RNA polymerase, in its core form, slides along the DNA molecule. | 1 | Applied and Interdisciplinary Chemistry |
cAMP-dependent protein kinase type I-alpha regulatory subunit is an enzyme that in humans is encoded by the PRKAR1A gene. | 1 | Applied and Interdisciplinary Chemistry |
In chemistry, a structural isomer (or constitutional isomer in the IUPAC nomenclature) of a compound is another compound whose molecule has the same number of atoms of each element, but with logically distinct bonds between them. The term metamer was formerly used for the same concept.
For example, butanol , methyl propyl ether , and diethyl ether have the same molecular formula but are three distinct structural isomers.
The concept applies also to polyatomic ions with the same total charge. A classical example is the cyanate ion and the fulminate ion . It is also extended to ionic compounds, so that (for example) ammonium cyanate and urea are considered structural isomers, and so are methylammonium formate and ammonium acetate .
Structural isomerism is the most radical type of isomerism. It is opposed to stereoisomerism, in which the atoms and bonding scheme are the same, but only the relative spatial arrangement of the atoms is different. Examples of the latter are the enantiomers, whose molecules are mirror images of each other, and the cis and trans versions of 2-butene.
Among the structural isomers, one can distinguish several classes including skeletal isomers, positional isomers (or regioisomers), functional isomers, tautomers, and structural topoisomers. | 0 | Theoretical and Fundamental Chemistry |
In certain cases, the plane stress model can be used in the analysis of gently curved surfaces. For example,
consider a thin-walled cylinder subjected to an axial compressive load uniformly distributed along its rim, and filled with a pressurized fluid. The internal pressure will generate a reactive hoop stress on the wall, a normal tensile stress directed perpendicular to the cylinder axis and tangential to its surface. The cylinder can be conceptually unrolled and analyzed as a flat thin rectangular plate subjected to tensile load in one direction and compressive load in another other direction, both parallel to the plate. | 1 | Applied and Interdisciplinary Chemistry |
A sol is a colloidal suspension made out of tiny solid particles in a continuous liquid medium. Sols are stable and exhibit the Tyndall effect, which is the scattering of light by the particles in the colloid. Examples include amongst others blood, pigmented ink, cell fluids, paint, antacids and mud.
Artificial sols can be prepared by two main methods: dispersion and condensation. In the dispersion method, solid particles are reduced to colloidal dimensions through techniques such as ball milling and Bredig's arc method. In the condensation method, small particles are formed from larger molecules through a chemical reaction.
The stability of sols can be maintained through the use of dispersing agents, which prevent the particles from clumping together or settling out of the suspension. Sols are often used in the sol-gel process, in which a sol is converted into a gel through the addition of a crosslinking agent.
In a sol, solid particles are dispersed in a liquid continuous phase, while in an emulsion, liquid droplets are dispersed in a liquid or semi-solid continuous phase.
Properties of a Colloid (applicable to sols)
* Heterogeneous Mixture
* Size of colloid varies from 1 nm - 100 nm
* They show the Tyndall effect
* They are quite stable and hence they do not settle down when left undisturbed | 0 | Theoretical and Fundamental Chemistry |
Examples of the application of ICP-AES include the determination of metals in wine, arsenic in food, and trace elements bound to proteins. ICP-AES methods are used to test for metals contamination in drinking water and wastewater.
ICP-AES is widely used in minerals processing to provide the data on grades of various streams, for the construction of mass balances.
In 2008, the technique was used at Liverpool University to demonstrate that a Chi Rho amulet found in Shepton Mallet and previously believed to be among the earliest evidence of Christianity in England, only dated to the nineteenth century.
ICP-AES is often used for analysis of trace elements in soil, and it is for that reason it is often used in forensics to ascertain the origin of soil samples found at crime scenes or on victims etc. Taking one sample from a control and determining the metal composition and taking the sample obtained from evidence and determine that metal composition allows a comparison to be made. While soil evidence may not stand alone in court it certainly strengthens other evidence.
It is also fast becoming the analytical method of choice for the determination of nutrient levels in agricultural soils. This information is then used to calculate the amount of fertiliser required to maximise crop yield and quality.
ICP-AES is used for motor oil analysis. Analyzing used motor oil reveals a great deal about how the engine is operating. Parts that wear in the engine will deposit traces in the oil which can be detected with ICP-AES. ICP-AES analysis can help to determine whether parts are failing. In addition, ICP-AES can determine what amount of certain oil additives remain and therefore indicate how much service life the oil has remaining. Oil analysis is often used by fleet manager or automotive enthusiasts who have an interest in finding out as much about their engine's operation as possible. ICP-AES is also used during the production of motor oils (and other lubricating oils) for quality control and compliance with production and industry specifications. | 0 | Theoretical and Fundamental Chemistry |
As outlined above, an efficient pV cell requires a material with an optical phonon mode more energetic than the bandgap, which in turn is much more energetic than the thermal energy at the intended operating temperature . Furthermore, the pV cell requires a material wherein a hot optical phonon prefers to produce an electron rather than multiple low energy acoustic phonons ().
Very few materials offer this combination of properties. Indeed, the vast majority of crystals have optical phonon energies limited to below 50 meV, and those with more energetic optical phonons tend to have much more energetic band gaps. In general, a material with a first-row element (periodic table) is required to have a highly energetic optical phonon. However, the high electronegativity of a first-row elements tends to create a very large band gap, as in diamond and the boron nitride allotropes. Graphene is one of the few materials which diverges from this trend, with no bandgap and an exceptionally energetic optical phonon mode near 200 meV. Thus, graphene has been the initial target for development of a phonovoltaic material through the opening and tuning of its bandgap.
Opening and tuning the bandgap of graphene has received substantial attention, and numerous strategies have been suggested and investigated. These include the use of uniaxial strain, electric fields, and chemical doping and functionalization. In general, these mechanisms work by either changing the symmetry of graphene (both Carbon atoms in the unit cell are identical) or hybridization ().
In the first phonovoltaic material investigations, it has been suggested that the latter technique destroys the electron-phonon coupling while the former preserves it. In particular, these investigations predict that hydrogenating graphene, to produce graphane, reduces the electron-phonon coupling so substantially that the material figure of merit vanishes; and that doping graphene with boron nitride maintains the strong electron-phonon coupling in graphene, such that its figure of merit is predicted to reach 0.65 and enable heat harvesting with twice the efficiency of a typical thermoelectric generator. | 0 | Theoretical and Fundamental Chemistry |
In the processing of dairy milk, for example during cheese making, syneresis is the formation of the curd due to the sudden removal of the hydrophilic macropeptides, which causes an imbalance in intermolecular forces. Bonds between hydrophobic sites start to develop and are enforced by calcium bonds, which form as the water molecules in the micelles start to leave the structure. This process is usually referred to as the phase of coagulation and syneresis. The splitting of the bond between residues 105 and 106 in the κ-casein molecule is often called the primary phase of the rennet action, while the phase of coagulation and syneresis is referred to as the secondary phase.
In cooking, syneresis is the sudden release of moisture contained within protein molecules, usually caused by excessive heat, which over-hardens the protective shell. Moisture inside expands upon heating. The hard protein shell pops, expelling the moisture.
This process is responsible for transforming juicy rare steak into dry steak when cooked thoroughly. It creates weeping in scrambled eggs, with dry protein curd swimming in the released moisture. It also causes emulsified sauces, such as hollandaise, to "break" ("split"). Additionally, it creates unsightly moisture pockets within baked custard dishes, such as flan or crème brûlée.
In dentistry, syneresis is the expulsion of water or other liquid molecules from dental impression materials (for instance, alginate) after an impression has been taken. Due to this process, the impression shrinks a little and therefore its size is no longer accurate. For this reason, many dental impression companies strongly recommend to pour the dental cast as soon as possible to prevent distortion of the dimension of the teeth and objects in the impression.
Gels formed from agarose are prone to syneresis, and the degree of syneresis is inversely proportional to the concentration of the agarose in the gels.
The opposite process of syneresis is imbibition, which is the process of a material absorbing water molecules from the surroundings. Alginate is also an example of imbibition because it will absorb water if soaked in it. | 0 | Theoretical and Fundamental Chemistry |
In the 1980s and 1990s, silicon carbide was studied in several research programs for high-temperature gas turbines in Europe, Japan and the United States. The components were intended to replace nickel superalloy turbine blades or nozzle vanes. However, none of these projects resulted in a production quantity, mainly because of its low impact resistance and its low fracture toughness.
Like other hard ceramics (namely alumina and boron carbide), silicon carbide is used in composite armor (e.g. Chobham armor), and in ceramic plates in bulletproof vests. Dragon Skin, which was produced by Pinnacle Armor, used disks of silicon carbide. Improved fracture toughness in SiC armor can be facilitated through the phenomenon of abnormal grain growth or AGG. The growth of abnormally long silicon carbide grains may serve to impart a toughening effect through crack-wake bridging, similar to whisker reinforcement. Similar
AGG-toughening effects have been reported in Silicon nitride (SiN).
Silicon carbide is used as a support and shelving material in high temperature kilns such as for firing ceramics, glass fusing, or glass casting. SiC kiln shelves are considerably lighter and more durable than traditional alumina shelves.
In December 2015, infusion of silicon carbide nano-particles in molten magnesium was mentioned as a way to produce a new strong and plastic alloy suitable for use in aeronautics, aerospace, automobile and micro-electronics. | 1 | Applied and Interdisciplinary Chemistry |
Kurt Martin Mislow (June 5, 1923 – October 5, 2017) was a German-born American organic chemist who specialized in stereochemistry.
Born in Berlin on June 5, 1923, Mislow had moved to London by 1938, after some time in Milan. With the help of his uncle Alfred Eisenstaedt, Mislows family left London for New York City in 1940. Mislow earned a bachelors degree in chemistry from Tulane University in 1944, and received a doctorate from the California Institute of Technology, where he was supervised by Linus Pauling. Mislow first taught at New York University, then moved to Princeton University in 1964. While at Princeton, Mislow served as Hugh Stott Taylor Professor of Chemistry and led the chemistry department from 1968 to 1974. He became a professor emeritus in 1988.
Over the course of his career, Mislow was named a Guggenheim fellow twice, in 1956 and 1974. Between 1959 and 1963, Mislow was granted the Sloan Research Fellowship. He became a member of the National Academy of Sciences in 1972, followed by fellowships in the American Academy of Arts and Sciences, granted in 1974, and the American Association for the Advancement of Science, bestowed in 1980. In 1999, Mislow was named a foreign member of the Accademia dei Lincei. The American Chemical Society honored Mislow with several awards, among them the James Flack Norris Award in Physical Organic Chemistry (1975), the William H. Nichols Medal Award (1987), and the Arthur C. Cope Scholar Award (1995). | 0 | Theoretical and Fundamental Chemistry |
As early as 1938, G. N. Lewis pointed out that the relative strength of an acid or base depended upon the base or acid against which it was measured. No single rank order of acid or base strength can predict the energetics of the cross reaction. Consider the following pair of acid–base reactions:.
: 4F-CHOH + OEt −ΔH = 5.94 kcal/mole
: 4F-CHOH + SMe −ΔH = 4.73 kcal/mole
These data suggest that OEt is a stronger base than SMe. The opposite is found, however, when I is the acid:
: I + OEt −ΔH = 4.16 kcal/mole
: I + SMe −ΔH = 7.63 kcal/mole | 0 | Theoretical and Fundamental Chemistry |
Immunomagnetic separation involves purified antigens biotinylated and bound to streptoavidin-coated paramagnetic particles. The raw sample is mixed with the beads, then a specific magnet is used to hold the target organisms against the vial wall and the non-bound material is poured off. This method can be used to recover specific indicator bacteria. | 0 | Theoretical and Fundamental Chemistry |
An ion-sensitive field-effect transistor (ISFET) is a field-effect transistor used for measuring ion concentrations in solution; when the ion concentration (such as H, see pH scale) changes, the current through the transistor will change accordingly. Here, the solution is used as the gate electrode. A voltage between substrate and oxide surfaces arises due to an ion sheath. It is a special type of MOSFET (metal–oxide–semiconductor field-effect transistor), and shares the same basic structure, but with the metal gate replaced by an ion-sensitive membrane, electrolyte solution and reference electrode. Invented in 1970, the ISFET was the first biosensor FET (BioFET).
The surface hydrolysis of Si–OH groups of the gate materials varies in aqueous solutions due to pH value. Typical gate materials are SiO, SiN, AlO and TaO.
The mechanism responsible for the oxide surface charge can be described by the site binding model, which describes the equilibrium between the Si–OH surface sites and the H ions in the solution. The hydroxyl groups coating an oxide surface such as that of SiO can donate or accept a proton and thus behave in an amphoteric way as illustrated by the following acid-base reactions occurring at the oxide-electrolyte interface:
:—Si–OH + HO ↔ —Si–O + HO
:—Si–OH + HO ↔ —Si–OH + HO
An ISFETs source and drain are constructed as for a MOSFET. The gate electrode is separated from the channel by a barrier which is sensitive to hydrogen ions and a gap to allow the substance under test to come in contact with the sensitive barrier. An ISFETs threshold voltage depends on the pH of the substance in contact with its ion-sensitive barrier. | 0 | Theoretical and Fundamental Chemistry |
Signal peptides are extremely heterogeneous, many prokaryotic and eukaryotic ones are functionally interchangeable within or between species and all determine protein secretion efficiency. | 1 | Applied and Interdisciplinary Chemistry |
Partition equilibrium is a special case of chemical equilibrium wherein one or more solutes are in equilibrium between two immiscible solvents. The most common chemical equilibrium systems involve reactants and products in the same phase - either all gases or all solutions. However, it is also possible to get equilibria between substances in different phases, such a liquid and gas that do not mix (are immiscible). One example is gas-liquid partition equilibrium chromatography, where an analyte equilibrates between a gas and liquid phase. Partition equilibria are described by Nernst's distribution law. Partition equilibrium are most commonly seen and used for Liquid–liquid extraction.
The time until a partition equilibrium emerges is influenced by many factors, such as: temperature, relative concentrations, surface area of interface, degree of stirring, and the nature of the solvents and solute. | 0 | Theoretical and Fundamental Chemistry |
Proteins and other molecules are constantly in competition with one another over binding sites on a surface. The Vroman Effect, developed by Leo Vroman, postulates that small and abundant molecules will be the first to coat a surface. However, over time, molecules with higher affinity for that particular surface will replace them. This is often seen in materials that contact the blood where fibrinogen will bind to the surface first and over time will be replaced by kininogen. | 1 | Applied and Interdisciplinary Chemistry |
The Hoffmann kiln is a series of batch process kilns. Hoffmann kilns are the most common kiln used in production of bricks and some other ceramic products. Patented by German Friedrich Hoffmann for brickmaking in 1858, it was later used for lime-burning, and was known as the Hoffmann continuous kiln. | 1 | Applied and Interdisciplinary Chemistry |
Gold mined from the Cordillera Mountain Range were brought down to the coast through the Aringay-Tonglo-Balatok gold trail, making commercial trade centers out of Aringay and the neighboring settlement of Agoo, whose coast at the time was shaped in such a way that it was a good harbor for foreign vessels coming into Lingayen Gulf. On the island of Mindanao, gold was mined along the Agusan River in the Butuan-Surigao area and extensively worked in the Butuan polity located at the mouth of the Agusan River. | 1 | Applied and Interdisciplinary Chemistry |
Phosphonates feature tetrahedral phosphorus centers. They are structurally closely related to (and often prepared from) phosphorous acid.
Phosphonate salts are the result of deprotonation of phosphonic acids, which are diprotic acids:
:RPO(OH) + NaOH → HO + RPO(OH)(ONa) (monosodium phosphonate)
:RPO(OH)(ONa) + NaOH → HO + RPO(ONa) (disodium phosphonate)
Phosphonate esters are the result of condensation of phosphonic acids with alcohols. | 0 | Theoretical and Fundamental Chemistry |
A cocurrent heat exchanger is an example of a cocurrent flow exchange mechanism. <br />
Two tubes have a liquid flowing in the same direction. One starts off hot at 60 °C, the second cold at 20 °C. A thermoconductive membrane or an open section allows heat transfer between the two flows.
The hot fluid heats the cold one, and the cold fluid cools down the warm one. The result is thermal equilibrium: Both fluids end up at around the same temperature: 40 °C, almost exactly between the two original temperatures (20 and 60 °C). At the input end, there is a large temperature difference of 40 °C and much heat transfer; at the output end, there is a very small temperature difference (both are at the same temperature of 40 °C or close to it), and very little heat transfer if any at all. If the equilibrium—where both tubes are at the same temperature—is reached before the exit of the liquid from the tubes, no further heat transfer will be achieved along the remaining length of the tubes.
A similar example is the cocurrent concentration exchange. The system consists of two tubes, one with brine (concentrated saltwater), the other with freshwater (which has a low concentration of salt in it), and a semi permeable membrane which allows only water to pass between the two, in an osmotic process. Many of the water molecules pass from the freshwater flow in order to dilute the brine, while the concentration of salt in the freshwater constantly grows (since the salt is not leaving this flow, while water is). This will continue, until both flows reach a similar dilution, with a concentration somewhere close to midway between the two original dilutions. Once that happens, there will be no more flow between the two tubes, since both are at a similar dilution and there is no more osmotic pressure. | 1 | Applied and Interdisciplinary Chemistry |
Birch reduction is a possible method to reduce reduces aromatic compounds into cycloalkenes, specifically cyclohexadiene. | 0 | Theoretical and Fundamental Chemistry |
For a single, nonrelativistic particle of mass m, in zero magnetic field, the transition dipole moment between two energy eigenstates ψ and ψ can alternatively be written in terms of the momentum operator, using the relationship
This relationship can be proven starting from the commutation relation between position x and the Hamiltonian :
Then
However, assuming that ψ and ψ are energy eigenstates with energy E and E, we can also write
Similar relations hold for y and z, which together give the relationship above. | 0 | Theoretical and Fundamental Chemistry |
By a wide margin, wet pipe sprinkler systems are installed more often than all other types of fire sprinkler systems. They also are the most reliable, because they are simple, with the only operating components being the automatic sprinklers and (commonly, but not always) the automatic alarm check valve. An automatic water supply provides water under pressure to the system piping.
Wet systems have optionally been charged with an antifreeze chemical, for use where pipes cannot reliably be kept above .
While such systems were once common in cold areas, after several fires which were not controlled because of sprinkler systems filled with too high a percentage of antifreeze, the regulatory authority in the United States effectively banned new antifreeze installations. A sunset date of 2022 applies to older antifreeze systems in the US. This regulatory action has greatly increased costs and reduced options for cold weather tolerant sprinkler systems. | 1 | Applied and Interdisciplinary Chemistry |
The organic ligands of the interfacial layer can influence the photoluminescence (PL) of a nanoparticle via various mechanisms, two of which are surface passivation and carrier trapping.
Surface passivation: At the surface of an uncovered nanoparticle (without an interfacial layer) dangling atoms are found. These bonds form energy levels between the HOMO-LUMO gap, thereby leading to non-radiative relaxation. Due to the binding of ligand molecules with the dangling orbitals, the energy of these states is shifted away from the HOMO-LUMO gap. This prevents nonradiative relaxation, and thus results in more PL. The strength of this effect strongly depends on the type of ligands. In general, small, linear ligands, do better than bulky ligands, because they lead to a higher surface coverage density, therefore allowing more dangling orbitals to be passivated.
Another surface effect is carrier trapping. Here the ligands can scavenge the electron(holes) in the nanoparticle, thereby precluding radiative recombination and thus leading towards a reduction in PL. A well-known example of such ligands are thiols.
The light conversion efficiency can also be improved using an interfacial layer that exists of compounds that absorb in a wider energy range and emit at the absorption energy of the nanoparticle. According to C. S. Inagaki et al the absorption band of a metallic nanoparticle was shown to drastically increase in width, caused by the overlap of transitions in the interfacial layer and the plasmon resonance band of the nanoparticle. This phenomenon can be used in practical applications like LED's and solar cells. In these technologies either the efficiency of absorption or emission is of critical importance and nanoparticles with an interfacial layer could be used to improve this efficiency by either absorbing or emitting at a wider range of energies. | 0 | Theoretical and Fundamental Chemistry |
The design of a constructed wetland can greatly effect the surrounding environment. A wide range of skills and knowledge is needed in the construction and can easily be detrimental to the site if not done correctly. A long list of professions ranging from civil engineers to hydrologists to wildlife biologists to landscape architects are needed in this design process. The landscape architect can utilize a wide range of skills to help accomplish the task of constructing a wetland that may not be thought of by other professions. Ecological landscape architects are also qualified to create wetland restoration designs in coordination with wetland scientists that increase the community value and appreciation of a project through well designed access, interpretation, and views of the project. Landscape architecture has a long history of engagement with the aesthetic dimension of wetlands. Landscape architects also guide through the laws and regulations associated with constructing a wetland. | 1 | Applied and Interdisciplinary Chemistry |
ISO 31-8 is the part of international standard ISO 31 that defines names and symbols for quantities and units related to physical chemistry and molecular physics. | 0 | Theoretical and Fundamental Chemistry |
Throughout history, extraction and purification methods have evolved from standard chromatographic methods to the utilisation of affinity tags. However, the final extraction and purification process undertaken highly depends on the chosen expression system. Please refer to subunit expression and synthesis for more insights. | 1 | Applied and Interdisciplinary Chemistry |
Robert John Ferrier FRSNZ, FNZIC, (7 August 1932 – 11 July 2013) was an organic chemist who discovered two chemical reactions, the Ferrier rearrangement and the Ferrier carbocyclization. Originally from Edinburgh, he moved to Wellington, New Zealand, in 1970. | 0 | Theoretical and Fundamental Chemistry |
For laminar (smooth) flows, it is a consequence of Poiseuille's law (which stems from an exact classical solution for the fluid flow) that
where is the Reynolds number
and where is the viscosity of the fluid and
is known as the kinematic viscosity. In this expression for Reynolds number, the characteristic length is taken to be the hydraulic diameter of the pipe, which, for a cylindrical pipe flowing full, equals the inside diameter. In Figures 1 and 2 of friction factor versus Reynolds number, the regime demonstrates laminar flow; the friction factor is well represented by the above equation.
In effect, the friction loss in the laminar regime is more accurately characterized as being proportional to flow velocity, rather than proportional to the square of that velocity: one could regard the Darcy–Weisbach equation as not truly applicable in the laminar flow regime.
In laminar flow, friction loss arises from the transfer of momentum from the fluid in the center of the flow to the pipe wall via the viscosity of the fluid; no vortices are present in the flow. Note that the friction loss is insensitive to the pipe roughness height : the flow velocity in the neighborhood of the pipe wall is zero. | 1 | Applied and Interdisciplinary Chemistry |
In 1929, Rinkel proposed a different method to calculate while using the Rüchardt apparatus: he noted that it may be shown that the vertical distance L which the sphere falls before it begin to rise is: , so may be calculated from measured values of L, m, V, P and A.
In 1951, Koehler and later, in 1972 Flammersfeld introduced a trick in the original Rüchardt setup, to increase the number of oscillations that are limited by the unavoidable friction-damping and gas leak (through the piston-tube seal): they made a thin hole on the tube (at half-height) and provided a gas-feeding pump to keep the pressure inside the vessel constant. By properly trimming the gas inlet flux (through a throttling valve) they obtained the following result: during the oscillations the piston is pushed-up by the gas overpressure until it crosses the hole position; then the gas leakage through the hole reduces the pressure, and the piston falls back. The force acting onto the piston varies at a rate that is regulated by the piston oscillation frequency leading to forced oscillation; fine adjustment of the throttle valve allows to achieve maximum amplitude at resonance.
In 1958, Christy and Rieser used only a gas-feeding pump to stabilize the gas pressure.
A slightly different solution was found in 1964 by Hafner who used a tapered tube (conical: slightly larger at the top).
In 1959, Taylor used a column of mercury oscillating inside a U-shaped tube instead of the Rüchardt sphere.
In 1964, Donnally and Jensen used a variable load attached to the Rüchardt sphere in order to allows frequency measurements with different oscillating mass.
In 1967, Lerner suggested a modified version of the Taylor method (with mercury replaced by water).
In 1979, Smith reported a simplified version of the complex Rüchardt-resonance method, originally invented by Clark and Katz, in which an oscillating magnetic piston is driven into resonance by an external coil.
In 1988, Connolly suggested the use of a photogate to measure more precisely the frequency of the Rüchardt sphere.
In 2001, Severn and Steffensen used a pressure transducer to monitor the pressure oscillations in the original Rüchardt setup.
In 2001, Torzo, Delfitto, Pecori and Scatturin implemented the version of Rüchardt apparatus (shown in the top picture) using three sensors: a sonar that monitors the breast-pump oscillations, and pressure and temperature sensors that monitor the changes in pressure and temperature inside the glass vessel. | 0 | Theoretical and Fundamental Chemistry |
The hydrodynamic entrance region refers to the area of a pipe where fluid entering a pipe develops a velocity profile due to viscous forces propagating from the interior wall of a pipe. This region is characterized by a non-uniform flow. The fluid enters a pipe at a uniform velocity, then fluid particles in the layer in contact with the surface of the pipe come to a complete stop due to the no-slip condition. Due to viscous forces within the fluid, the layer in contact with the pipe surface resists the motion of adjacent layers and slows adjacent layers of fluid down gradually, forming a velocity profile. For the conservation of mass to hold true, the velocity of layers of the fluid in the center of the pipe increases to compensate for the reduced velocities of the layers of fluid near the pipe surface. This develops a velocity gradient across the cross-section of the pipe. | 1 | Applied and Interdisciplinary Chemistry |
Base-catalyzed transesterification reacts lipids (fats and oils) with alcohol (typically methanol or ethanol) to produce biodiesel and an impure coproduct, glycerol. If the feedstock oil is used or has a high acid content, acid-catalyzed esterification can be used to react fatty acids with alcohol to produce biodiesel. Other methods, such as fixed-bed reactors, supercritical reactors, and ultrasonic reactors, forgo or decrease the use of chemical reaction that reduces the quality of substance in chemistry. | 0 | Theoretical and Fundamental Chemistry |
ADAM17 is understood to be involved in the processing of tumor necrosis factor alpha (TNF-α) at the surface of the cell, and from within the intracellular membranes of the trans-Golgi network. This process, which is also known as shedding, involves the cleavage and release of a soluble ectodomain from membrane-bound pro-proteins (such as pro-TNF-α), and is of known physiological importance. ADAM17 was the first sheddase to be identified, and is also understood to play a role in the release of a diverse variety of membrane-anchored cytokines, cell adhesion molecules, receptors, ligands, and enzymes.
Cloning of the TNF-α gene revealed it to encode a 26 kDa type II transmembrane pro-polypeptide that becomes inserted into the cell membrane during its maturation. At the cell surface, pro-TNF-α is biologically active, and is able to induce immune responses via juxtacrine intercellular signaling. However, pro-TNF-α can undergo a proteolytic cleavage at its Ala76-Val77 amide bond, which releases a soluble 17kDa extracellular domain (ectodomain) from the pro-TNF-α molecule. This soluble ectodomain is the cytokine commonly known as TNF-α, which is of pivotal importance in paracrine signaling. This proteolytic liberation of soluble TNF-α is catalyzed by ADAM17.
Recently, ADAM17 was discovered as a crucial mediator of resistance to radiotherapy. Radiotherapy can induce a dose-dependent increase of furin-mediated cleavage of the ADAM17 proform to active ADAM17, which results in enhanced ADAM17 activity in vitro and in vivo. It was also shown that radiotherapy activates ADAM17 in non-small cell lung cancer, which results in shedding of multiple survival factors, growth factor pathway activation, and radiotherapy-induced treatment resistance.
ADAM17 may play a prominent role in the Notch signaling pathway, during the proteolytic release of the Notch intracellular domain (from the Notch1 receptor) that occurs following ligand binding. ADAM17 also regulates the MAP kinase signaling pathway by regulating shedding of the EGFR ligand amphiregulin in the mammary gland. ADAM17 also has a role in the shedding of L-selectin, a cellular adhesion molecule. | 1 | Applied and Interdisciplinary Chemistry |
Electron transfer self-exchange rates can be also determined with the experimental value of line-width and chemical shift. Sharp peaks of diamagnetic compounds can be broadened during the electron transfer with its partner paramagnetic compound (one-electron oxidized species), since paramagnetic compounds exhibit broader peaks at a different chemical shift. If their self-exchange rate is sufficiently faster than the NMR timescale, the line-broadening of the peaks is observed at shifted chemical shifts in the spectrum. In order to determine the self-exchange rate of sample compounds, one can choose a certain characteristic peak of the sample diamagnetic compound, and examine the peak broadening in the mixture with its partner paramagnetic compound. The broadened line-widths are proportional to mole fraction, and the equation can be used to determine self-exchange rate with the value of mole fraction, chemical shift and line-width: , is the rate constant of electron transfer self-exchange, and are the mole fractions of diamagnetic and paramagnetic compounds, is the chemical shift difference (in Hz) between pure diamagnetic and paramagnetic compounds, and is the half-width of the peak (width at half height) of the selected peak. and are the peak widths of the pure diamagnetic and paramagnetic species, and is the total concentration of the exchanging species in M (mol/L).
For more accurate calculation of each mole fraction, the following equations can be used; , is a shifted chemical shift of the selected peak, and is the original chemical shift of the diamagnetic species based on the assumption that the change in chemical shift is linearly correlated to the mole fraction of the paramagnetic species. | 0 | Theoretical and Fundamental Chemistry |
From the equivalent circuit it is evident that the current produced by the solar cell is equal to that produced by the current source, minus that which flows through the diode, minus that which flows through the shunt resistor:
where
*I, output current (ampere)
*I, photogenerated current (ampere)
*I, diode current (ampere)
*I, shunt current (ampere).
The current through these elements is governed by the voltage across them:
where
*V, voltage across both diode and resistor R (volt)
*V, voltage across the output terminals (volt)
*I, output current (ampere)
*R, series resistance (Ω).
By the Shockley diode equation, the current diverted through the diode is:
where
*I, reverse saturation current (ampere)
*n, diode ideality factor (1 for an ideal diode)
*q, elementary charge
*k, Boltzmann constant
*T, absolute temperature
* the thermal voltage. At 25 °C, volt.
By Ohm's law, the current diverted through the shunt resistor is:
where
*R, shunt resistance (Ω).
Substituting these into the first equation produces the characteristic equation of a solar cell, which relates solar cell parameters to the output current and voltage:
An alternative derivation produces an equation similar in appearance, but with V on the left-hand side. The two alternatives are identities; that is, they yield precisely the same results.
Since the parameters I, n, R, and R cannot be measured directly, the most common application of the characteristic equation is nonlinear regression to extract the values of these parameters on the basis of their combined effect on solar cell behavior. An online simulator to extract the circuit parameters can be found at SolarDesign.
When R is not zero, the above equation does not give the current I directly, but it can then be solved using the Lambert W function:
When an external load is used with the cell, its resistance can simply be added to R and V set to zero in order to find the current.
When R is infinite there is a solution for V for any less than :
Otherwise one can solve for V using the Lambert W function:
However, when R is large it's better to solve the original equation numerically.
The general form of the solution is a curve with I decreasing as V increases (see graphs lower down). The slope at small or negative V (where the W function is near zero) approaches , whereas the slope at high V approaches . | 0 | Theoretical and Fundamental Chemistry |
As the name suggests, surge margin provides a measure of how close an operating point is to surge. Unfortunately, there are a number of different definitions of surge margin. A popular one in use is defined as follows:
where:
is the mass flow at the operating point, be it steady state or transient
is the mass flow at surge, at same corrected speed as | 0 | Theoretical and Fundamental Chemistry |
Rigid unit modes (RUMs) represent a class of lattice vibrations or phonons that exist in network materials such as quartz, cristobalite or zirconium tungstate. Network materials can be described as three-dimensional networks of polyhedral groups of atoms such as SiO tetrahedra or TiO octahedra. A RUM is a lattice vibration in which the polyhedra are able to move, by translation and/or rotation, without distorting. RUMs in crystalline materials are the counterparts of floppy modes in glasses, as introduced by Jim Phillips and Mike Thorpe. | 0 | Theoretical and Fundamental Chemistry |
After some years in the planning and enabling phase, the [http://www.geotraces.org/science/science-plan GEOTRACES Science Plan] was published in 2006 and the GEOTRACES programme formally launched its seagoing effort in January 2010. This phase is expected to last a decade. | 0 | Theoretical and Fundamental Chemistry |
The 25 year record of ocean carbon measurements at Station ALOHA document that the partial pressure of (p) in the mixed layer is increasing at a rate slightly greater than the trend observed in the atmosphere. This has been accompanied by progressive decreases in seawater pH. Although the effect of anthropogenic is evidenced by long-term decreases in seawater pH throughout the upper 600 m, the rate of acidification at Station ALOHA varies with depth. For example, in the upper mesopelagic waters (~160–310 m) pH is decreasing at nearly twice the rate observed in the surface waters. Such depth-dependent differences in acidification are due to a combination of regional differences in time-varying climate signatures, mixing, and changes in biological activity. | 0 | Theoretical and Fundamental Chemistry |
C NMR spectroscopy is much less sensitive (ca. by 4 orders of magnitude) to carbon than H NMR spectroscopy is to hydrogen, because of the lower abundance (1.1%) of C compared to H (>99%), and because of a lower(0.702 vs. 2.8) nuclear magnetic moment. Stated equivalently, the gyromagnetic ratio (6.728284 10 rad T s) is only 1/4th that of H.
On the other hand, the sensitivity of C NMR spectroscopy benefits to some extent from nuclear Overhauser effect, which enhances signal intensity for non-quaternary C atoms. | 0 | Theoretical and Fundamental Chemistry |
The C-O bonds that comprise simple ethers are strong. They are unreactive toward all but the strongest bases. Although generally of low chemical reactivity, they are more reactive than alkanes.
Specialized ethers such as epoxides, ketals, and acetals are unrepresentative classes of ethers and are discussed in separate articles. Important reactions are listed below. | 0 | Theoretical and Fundamental Chemistry |
In this formalism, a liquid crystal material is treated as a continuum; molecular details are entirely ignored. Rather, this theory considers perturbations to a presumed oriented sample. The distortions of the liquid crystal are commonly described by the Frank free energy density. One can identify three types of distortions that could occur in an oriented sample: (1) twists of the material, where neighboring molecules are forced to be angled with respect to one another, rather than aligned; (2) splay of the material, where bending occurs perpendicular to the director; and (3) bend of the material, where the distortion is parallel to the director and molecular axis. All three of these types of distortions incur an energy penalty. They are distortions that are induced by the boundary conditions at domain walls or the enclosing container. The response of the material can then be decomposed into terms based on the elastic constants corresponding to the three types of distortions. Elastic continuum theory is an effective tool for modeling liquid crystal devices and lipid bilayers. | 0 | Theoretical and Fundamental Chemistry |
BASys (Bacterial Annotation System) is a freely available web server that can be used to perform automated, comprehensive annotation of bacterial genomes. With the advent of next generation DNA sequencing it is now possible to sequence the complete genome of a bacterium (typically ~4 million bases) within a single day. This has led to an explosion in the number of fully sequenced microbes. In fact, as of 2013, there were more than 2700 fully sequenced bacterial genomes deposited with GenBank. However, a continuing challenge with microbial genomics is finding the resources or tools for annotating the large number of newly sequenced genomes. BASys was developed in 2005 in anticipation of these needs. In fact, BASys was the world’s first publicly accessible microbial genome annotation web server. Because of its widespread popularity, the BASys server was updated in 2011 through the addition of multiple server nodes to handle the large number of queries it was receiving.
The BASys server is designed to accept either assembled genome data (raw DNA sequence data) or complete proteome assignments as input. If raw DNA sequence is provided, BASys employs Glimmer (version 2.1.3) to identify the genes. The output from BASys is a comprehensive genome-wide annotation (with ~60 annotation subfields for each gene) and a zoomable, hyperlinked genome map of the query genome. BASys uses nearly 30 different programs to determine and annotate gene/protein names, GO functions, COG functions, possible paralogues and orthologues, molecular weight, isoelectric point, operon structure, subcellular localization, signal peptides, transmembrane regions, secondary structure, 3D structure, reactions and pathways. The full list of programs used by BASys is given below:
In addition to its extensive annotation for each gene/protein in the query genome, BASys also generates colorful, clickable and fully zoomable circular maps of each input chromosome. These bacterial genome maps are generated used a program called CGView (Circular Genome Viewer) which was developed in 2004. The genome maps are designed to allow rapid navigation and detailed visualization of all the BASys-generated gene annotations. A complete BASys run takes approximately 16 h for an average bacterial chromosome (approximately 4 Megabases). BASys annotations may be viewed and downloaded anonymously or through a password protected access system. BASys will store its bacterial genome annotations on the server for a maximum of 180 days. BASys handles approximately 1000 submissions a year. BASys is accessible at https://www.basys.ca/ | 1 | Applied and Interdisciplinary Chemistry |
The first recorded observation of capillary action was by Leonardo da Vinci. A former student of Galileo, Niccolò Aggiunti, was said to have investigated capillary action. In 1660, capillary action was still a novelty to the Irish chemist Robert Boyle, when he reported that "some inquisitive French Men" had observed that when a capillary tube was dipped into water, the water would ascend to "some height in the Pipe". Boyle then reported an experiment in which he dipped a capillary tube into red wine and then subjected the tube to a partial vacuum. He found that the vacuum had no observable influence on the height of the liquid in the capillary, so the behavior of liquids in capillary tubes was due to some phenomenon different from that which governed mercury barometers.
Others soon followed Boyle's lead. Some (e.g., Honoré Fabri, Jacob Bernoulli) thought that liquids rose in capillaries because air could not enter capillaries as easily as liquids, so the air pressure was lower inside capillaries. Others (e.g., Isaac Vossius, Giovanni Alfonso Borelli, Louis Carré, Francis Hauksbee, Josia Weitbrecht) thought that the particles of liquid were attracted to each other and to the walls of the capillary.
Although experimental studies continued during the 18th century, a successful quantitative treatment of capillary action was not attained until 1805 by two investigators: Thomas Young of the United Kingdom and Pierre-Simon Laplace of France. They derived the Young–Laplace equation of capillary action. By 1830, the German mathematician Carl Friedrich Gauss had determined the boundary conditions governing capillary action (i.e., the conditions at the liquid-solid interface). In 1871, the British physicist Sir William Thomson (later Lord Kelvin) determined the effect of the meniscus on a liquid's vapor pressure—a relation known as the Kelvin equation. German physicist Franz Ernst Neumann (1798–1895) subsequently determined the interaction between two immiscible liquids.
Albert Einsteins first paper, which was submitted to Annalen der Physik' in 1900, was on capillarity. | 0 | Theoretical and Fundamental Chemistry |
Sulfur is present in the environment in solids, gases, and aqueous species. Sulfur-containing solids on Earth include the common minerals pyrite (FeS), galena (PbS), and gypsum (CaSO•2HO). Sulfur is also an important component of biological material, including in the essential amino acids cysteine and methionine, the B vitamins thiamine and biotin, and the ubiquitous substrate coenzyme A. In the ocean and other natural waters, sulfur is abundant as dissolved sulfate. Hydrogen sulfide is also present in some parts of the deep ocean where it is released from hydrothermal vents. Both sulfate and sulfide can be used by specialized microbes to obtain energy or to grow. Gases including sulfur dioxide and carbonyl sulfide make up the atmospheric component of the sulfur cycle. Any process that transports or chemically transforms sulfur between these many natural materials also has the potential to fractionate sulfur isotopes. | 0 | Theoretical and Fundamental Chemistry |
The term dross derives from the Old English word dros, meaning the scum produced when smelting metals (extracting them from their ores). By the 15th century it had come to refer to rubbish in general. Dregs, and the geological term druse are also thought to be etymologically related. Popular non-metalworking uses of the word are derogatory:
*poorly written or plagiarized journalism - "a dross article"; "utter/complete/terrible dross" (adjective/noun), a stronger term than filler
*undesirable, unprofitable work - "lets hone in on the lions share and outsource the dross"; synonyms: corvée, hiding-to-nothing, and drudgery which are growing archaisms in business (noun); as strong a term as dogsbody work | 1 | Applied and Interdisciplinary Chemistry |
As the ordinate scale spans the entire range of theoretically possible vales, from to one can see at a glance at an Eadie–Hofstee plot how well the experimental design fills the theoretical design space, and the plot makes it impossible to hide poor design. By contrast, the other well known straight-line plots make it easy to choose scales that suggest that the design is better than it is. Faulty design, as shown in the right-hand diagram, is common with experiments with a substrate that is not soluble enough or too expensive to use concentrations above , and in this case cannot be estimated satisfactorily. The opposite case, with values concentrated above (left-hand diagram) is less common but not unknown, as for example in a study of nitrate reductase. | 1 | Applied and Interdisciplinary Chemistry |
PyBOP (benzotriazol-1-yloxytripyrrolidinophosphonium hexafluorophosphate) is a peptide coupling reagent used in solid phase peptide synthesis. It is used as a substitute for the BOP reagent - avoiding the formation of the carcinogenic waste product HMPA. | 1 | Applied and Interdisciplinary Chemistry |
The Chemical Engineer is a monthly chemical engineering technical and news magazine published by the Institution of Chemical Engineers (IChemE). It has technical articles of interest to practitioners and educators, and also addresses current events in world of chemical engineering including research, international business news and government policy as it affects the chemical engineering community. The magazine is sent to all members of the IChemE and is included in the cost of membership. Some parts of the magazine are available free online, including recent news and a series of biographies “Chemical Engineers who Changed the World”, although the core and the archive magazine is available only with a subscription. The online magazine also has freely available podcasts. | 1 | Applied and Interdisciplinary Chemistry |
OCOs measurements are designed to be accurate enough to show for the first time the geographic distribution of carbon dioxide sources and sinks on a regional scale. The data is planned to improve the understanding of the global carbon cycle, the natural processes and human activities that influence the abundance and distribution of the greenhouse gas. This improved understanding is expected to enable more reliable forecasts of future changes in the abundance and distribution of carbon dioxide in the atmosphere and the effect that these changes may have on Earths climate.
The OCO spacecraft was provided by Orbital Sciences Corporation. During its two-year mission, OCO will fly in a near polar orbit which enables the instrument to observe most of Earths surface at least once every sixteen days. It is intended to fly in loose formation with a series of other Earth-orbiting satellites known as the Earth Observing System Afternoon Constellation, or the A-train. This coordinated flight formation was intended to enable researchers to correlate OCO data with data acquired by other instruments on other spacecraft. In particular, Earth scientists would like to compare OCO data with nearly simultaneous measurements acquired by the Atmospheric Infrared Sounder (AIRS) instrument aboard NASAs Aqua satellite and ground-based data from the Total Carbon Column Observing Network (TCCON). Alignment with the A-train demands a particularly short launch window of 30 seconds.
The original cost of the mission was . It was sponsored by NASAs Earth System Science Pathfinder Program. NASAs Jet Propulsion Laboratory in Pasadena, California, manages OCO for NASA's Science Mission Directorate. | 1 | Applied and Interdisciplinary Chemistry |
Thomas and George Cranege (also spelled Cranage), who worked in the ironworking industry in England in the 1760s, are notable for introducing a new method of producing wrought iron from pig iron. | 1 | Applied and Interdisciplinary Chemistry |
In gas dynamics, Chaplygin's equation, named after Sergei Alekseevich Chaplygin (1902), is a partial differential equation useful in the study of transonic flow. It is
Here, is the speed of sound, determined by the equation of state of the fluid and conservation of energy. For polytropic gases, we have , where is the specific heat ratio and is the stagnation enthalpy, in which case the Chaplygin's equation reduces to
The Bernoulli equation (see the derivation below) states that maximum velocity occurs when specific enthalpy is at the smallest value possible; one can take the specific enthalpy to be zero corresponding to absolute zero temperature as the reference value, in which case is the maximum attainable velocity. The particular integrals of above equation can be expressed in terms of hypergeometric functions. | 1 | Applied and Interdisciplinary Chemistry |
In 1999 Robinson was elected a Fellow of the Royal Society of New Zealand. In 2010 he was awarded a Marsden Medal by the New Zealand Association of Scientists, in recognition of his lifetime contribution to science. He was also a Fellow of the New Zealand Institute of Chemistry, and the Society of Perfumers and Flavourists.
An active Rotarian, Robinson was a recipient of the Paul Harris Fellowship for community service in 2004. | 0 | Theoretical and Fundamental Chemistry |
To successfully sink a caisson, it's imperative that the flow velocity within the closing gap is minimized; thus, the operation is conducted during slack water. Given the extremely brief period during which the current is genuinely still, the sinking process must commence while the tidal flow remains at a manageable low speed. Past experiences with caisson closures have demonstrated that this speed should not exceed 0.3 m/s, guiding the timing for various phases of the operation as follows:
This schedule dictates that flow speeds must reduce to 0.30 m/s at most 13 minutes before slack water and to 0.75 m/s at most 30 minutes before. Considering the sinusoidal nature of tides in the Netherlands, with a cycle of 12.5 hours, the maximum velocity in the closing gap should not surpass 2.5 m/s. This velocity threshold can be ascertained through a storage/basin analysis. The accompanying diagram illustrates outcomes for sill heights at MSL -10 m and MSL -12 m, indicating that a sill at MSL -12 m is necessary as the sinking time at MSL -10 m is insufficient. Consequently, caisson closures are feasible only at considerable channel depths. | 1 | Applied and Interdisciplinary Chemistry |
Rif is a small (~21 kDa) signaling G protein (more specifically a GTPase), and is a member of the Rho family of GTPases. It is primarily active in the brain and plays a physiological role in the formation of neuronal dendritic spine. This process is regulated by FARP1, a type of activator for RhoA GTPases. Alternatively, Rif can induce the formation of actin stress fibers in epithelial cells, which is dependent on the activity levels of ROCK proteins since the absence of ROCK activity would mean Rif would be unable to stimulate the growth of stress fibers.
Rif is also seen expressed in diverse amount of human tissues such as in the colon and stomach due to Rhos use of actin dynamics to absorb intestinal epithelial cells. Rif is one way of generating filopodia (Rif-induced filopodia) through its interaction with mDia2. Specifically, the interaction is between the GTP from Rif and the GTPase binding domain (GBD) of mDia2. Rifs function in forming filopodia has a relation to the function of platelets. But in mice, Rif is not necessary for platelets to function. The co-expression of Rif with Rac or Cdc42, other GTPases that also participate in regulating cell structure and morphology, can give rise to new filopodial structures that differ from the filopodia arrangements stimulated by each of these GTPases functioning separately. | 1 | Applied and Interdisciplinary Chemistry |
Diagnostic biomarkers give intervention-independent information on identifying or aid in identifying if there is a presence or absence of the disease or a disease subcategory/subphenotype status. An example is the traumatic brain injury (TBI) blood-based biomarker test consisted of measuring the levels of neuronal Ubiquitin carboxy-terminal hydrolase L1 (UCH-L1) and Glial fibrillary acidic protein (GFAP) to aid in the diagnosis of the presence of cranial lesion(s) among moderate to mild TBI patients that is(are) otherwise only diagnosable with the use of a CT scan of the head. | 1 | Applied and Interdisciplinary Chemistry |
Constructed wetland systems can be surface flow systems with only free-floating macrophytes, floating-leaved macrophytes, or submerged macrophytes; however, typical free water surface systems are usually constructed with emergent macrophytes. Subsurface flow-constructed wetlands with a vertical or a horizontal flow regime are also common and can be integrated into urban areas as they require relatively little space.
The main three broad types of constructed wetlands include:
* Subsurface flow constructed wetland – this wetland can be either with vertical flow (the effluent moves vertically, from the planted layer down through the substrate and out) or with horizontal flow (the effluent moves horizontally, parallel to the surface)
* Surface flow constructed wetland (this wetland has horizontal flow)
* Floating treatment wetland
The former types are placed in a basin with a substrate to provide a surface area upon which large amounts of waste degrading biofilms form, while the latter relies on a flooded treatment basin upon which aquatic plants are held in flotation till they develop a thick mat of roots and rhizomes upon which biofilms form. In most cases, the bottom is lined with either a polymer geomembrane, concrete or clay (when there is appropriate clay type) in order to protect the water table and surrounding grounds. The substrate can be either gravel—generally limestone or pumice/volcanic rock, depending on local availability, sand or a mixture of various sizes of media (for vertical flow constructed wetlands).
Constructed wetlands can be used after a septic tank for primary treatment (or other types of systems) in order to separate the solids from the liquid effluent. Some constructed wetland designs however do not use upfront primary treatment. | 1 | Applied and Interdisciplinary Chemistry |
Iron can be stored in ferritin as ferric iron due to the ferroxidase activity of the ferritin heavy chain. Dysfunctional ferritin may accumulate as hemosiderin, which can be problematic in cases of iron overload. The ferritin storage iron pool is much larger than the labile iron pool, ranging in concentration from 0.7 mM to 3.6 mM. | 1 | Applied and Interdisciplinary Chemistry |
Phage display is a laboratory technique for the study of protein–protein, protein–peptide, and protein–DNA interactions that uses bacteriophages (viruses that infect bacteria) to connect proteins with the genetic information that encodes them. In this technique, a gene encoding a protein of interest is inserted into a phage coat protein gene, causing the phage to "display" the protein on its outside while containing the gene for the protein on its inside, resulting in a connection between genotype and phenotype. The proteins that the phages are displaying can then be screened against other proteins, peptides or DNA sequences, in order to detect interaction between the displayed protein and those of other molecules. In this way, large libraries of proteins can be screened and amplified in a process called in vitro selection, which is analogous to natural selection.
The most common bacteriophages used in phage display are M13 and fd filamentous phage, though T4, T7, and λ phage have also been used. | 1 | Applied and Interdisciplinary Chemistry |
The Asian Conference on Electrochemical Power Sources (ACEPS) is a series of scientific conferences focusing on electrochemical power sources that is held in East Asia, Southeast Asia and South Asia at different locations each time. It was initiated by Professor Zempachi Ogumi in Japan in 2006, and has subsequently been held in China (2007), South Korea (2008), Taiwan (2009), Singapore (2010), India (2012), Japan (2013), China (2015), Korea (2017), and Taiwan (2019). The next meeting will be held in Singapore (Postpone to 2022). | 0 | Theoretical and Fundamental Chemistry |
In fluid dynamics, Bickley jet is a steady two-dimensional laminar plane jet with large jet Reynolds number emerging into the fluid at rest, named after W. G. Bickley, who gave the analytical solution in 1937, to the problem derived by Schlichting in 1933 and the corresponding problem in axisymmetric coordinates is called as Schlichting jet. The solution is valid only for distances far away from the jet origin. | 1 | Applied and Interdisciplinary Chemistry |
CaL is usually designed using a dual fluidised bed system to ensure sufficient contact between the gas streams and the sorbent. The calciner and carbonator are fluidised beds with associated process equipment for separating the gases and solids attached (such as cyclones). Calcination is an endothermic process and as such requires the application of heat to the calciner. The opposite reaction, carbonation, is exothermic and heat must be removed. Since the exothermic reaction happens at about 650 °C and the endothermic reaction at 850-950 °C, the heat from the carbonator cannot be directly used to heat the calciner.
The fluidisation of the solid bed in the carbonator is achieved by passing the flue gas through the bed. In the calciner, some of the recovered CO is recycled through the system. Some oxygen may also be passed through the reactor if fuel is being burned in the calciner to provide energy. | 1 | Applied and Interdisciplinary Chemistry |
Deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) are the main examples of polynucleotides. They arise by condensation of nucleotides. Their backbones form by the condensation of a hydroxy group on a ribose with the phosphate group on another ribose. This linkage is called a phosphodiester bond. The condensation is catalyzed by enzymes called polymerases. DNA and RNA can be millions of nucleotides long thus allowing for the genetic diversity of life. The bases project from the pentose-phosphate polymer backbone and are hydrogen bonded in pairs to their complementary partners (A with T and G with C). This creates a double helix with pentose phosphate backbones on either side, thus forming a secondary structure. | 0 | Theoretical and Fundamental Chemistry |
Phosphoenolpyruvate carboxylase (PEPC) is an enzyme that combines bicarbonate and phosphoenolpyruvate (PEP) to form the four-carbon acid, oxaloacetate. It is an important enzyme in C4 photosynthesis and anaplerotic pathways. It is also responsible for the position-specific enrichment of oxaloacetate, due to the equilibrium isotope effect of converting the linear molecule CO into the trigonal planar molecule HCO-, which partitions C into bicarbonate. Inside the PEPC enzyme, HCO- reacts 1.0022 times faster than HCO- so that PEPC has a 0.22% kinetic isotope effect. This is not enough to compensate for the 13C enrichment in bicarbonate. Thus, oxaloacetate is left with a C-enriched carbon at the C4 position. However, the C1 site experiences a small inverse secondary isotope effect due to its bonding environment in the transition state, leaving the C1 site of oxaloacetate enriched in C. In this way, PEPC simultaneously partitions C into the C4 site and C into the C1 site of oxaloacetate, an example of multiple position-specific isotope effects. | 0 | Theoretical and Fundamental Chemistry |
Fibroblast-populated Skin Substitutes are scaffolds which contain fibroblasts that are able to proliferate and produce extracellular matrix and growth factors within 2 to 3 weeks. This creates a matrix similar to that of a dermis.
Commercially available types are for example:
* Dermagraft
* Apligraf
* Orcel
* Polyactive
* Hyalograf 3D | 1 | Applied and Interdisciplinary Chemistry |
The Jameson Cell reportedly has the following advantages:
* relatively low energy use – the only energy that is required to operate the Cell is to pump the slurry through the slurry lens. This means that it requires significantly less electricity than conventional mechanical or column flotation cells. In addition, the better particle–bubble contact means that fewer Cells are required for the equivalent duty of mechanical cells, giving an even bigger power saving.
* high recovery of fines – The Cell is able to achieve final product specification from previously discarded coal fines at very high recoveries (95–98%) in a single pass. It has also been shown to be effective in recovering fine particles in base metals, potash and phosphate applications.
* effective froth washing – The Cell uses froth washing as standard to control concentrate grade. A conventional flotation cell has problems with recovering fine particles at high grades due to the entrainment of gangue minerals in the froth. The high throughput of the Jameson Cell means that the froth is produced in a small surface area so it is economic to apply froth washing to all cells
* easily scaled up – the hydrodynamic conditions for particle collection inside the downcomer and separation in the tank are identical between the laboratory, pilot plant and industrial-scale Jameson Cell, meaning that there is direct scale-up. This makes predicting plant performance for small-scale tests straightforward. In contrast, factors have to be used to scale-up the design of mechanical and column flotation cells.
* relatively small footprint – the high intensity of bubble-particle contact means that very low residence times are required in the Cell (residence time in the downcomer is 5–10 seconds and the separation tank volume is small compared with alternative technologies). This means that the total volume of the Cell is lower than the alternatives.
* fast response to process changes – process variables such as air flow rate, froth depth and wash water are all automated making optimisation straightforward. The small tank volumes means very short residence times in the tank (typically 1–3 minutes) so changes made, whether they are deliberate or from normal plant fluctuations, are observed almost instantly.
* rapid start-up and shutdown – the small volume of the tank means that the Cell can be filled and drained quickly so with plant upsets the Cell can reach steady state very quickly.
* low maintenance costs – the Cell has no moving parts and is designed to provide easy access to serviceable parts. The slurry lens orifice has a service life exceeding 5 years under normal operating conditions and the service life of the other wet-end wear parts is reported to be over 10 years under normal operating conditions.
* low capital cost – the small footprint of the Cell reduces the amount of steel required in its construction and, coupled with the simplicity of its design, has lower installation costs when compared with conventional or column flotation cells.
* low operating costs – the lack of moving parts with a consequent lower power consumption, long wear life and easy access results in low operating costs.
* short payback periods – Cell users typically report short payback periods for their investments in the technology. For example, the 2007 installation of a 5.4 m diameter Jameson Cell with 18 downcomers to treat preflotation concentrate recovered up to 90% of the zinc previously lost to the tailings disposal facility and had a payback of approximately one year at the zinc prices of the day. Peko Mines reported a payback period of two months for its Cell installation. The complete replacement of 32 mechanical cells with eight Jameson Cells at the Goonyella coal mine had a payback of 17 months. More recently, the installation of a Cell ahead of each of two cleaner trains at the Telfer Mine had a payback of between two and seven months. | 1 | Applied and Interdisciplinary Chemistry |
Jonas Asevicius-Acus-Acukas (July 29, 1885 in Jieznas – July 11, 1976 in Kaunas) was a Lithuanian army officer and chemist. From 1909 to 1918, he served in the Imperial Russian Army at Kaunas Fortress. He fought in the First World War and the Russian Civil War. In 1921 he returned to Lithuania and was mobilized into the Lithuanian Armed Forces, where he attained the rank of colonel (1927) and served until 1940. Acus graduated from Vytautas Magnus University in 1930. He lectured on chemistry and commodity science at Vytautas Magnus University (1934–1940), Vilnius University (1940–1950), and Lithuanian University of Agriculture (1951–1957). He wrote textbooks on foundations of commodity science (1949) and a short course in physical chemistry (1957). Acus was awarded the Commander's Crosses of the Order of Vytautas the Great (1938) and the Order of the Lithuanian Grand Duke Gediminas (1928). | 0 | Theoretical and Fundamental Chemistry |
The nutritional value of sea salt and table salt are about the same as they are both primarily sodium chloride. Table salt is more processed than sea salt to eliminate minerals and usually contains an additive such as silicon dioxide to prevent clumping.
Iodine, an element essential for human health, is present only in small amounts in sea salt. Iodised salt is table salt mixed with a minute amount of various salts of the element iodine.
Studies have found some microplastic contamination in sea salt from the US, Europe and China. Sea salt has also been shown to be contaminated by fungi that can cause food spoilage as well as some that may be mycotoxigenic.
In traditional Korean cuisine, jugyeom (, 竹鹽), which means "bamboo salt", is prepared by roasting salt at temperatures between 800 and 2000 °C in a bamboo container plugged with mud at both ends. This product absorbs minerals from the bamboo and the mud, and is claimed to increase the anticlastogenic and antimutagenic properties of the fermented soybean paste known in Korea as doenjang. However, these claims are not substantiated by high-quality studies. | 0 | Theoretical and Fundamental Chemistry |
A symmetry of a Euclidean graph is an isometry of the underlying Euclidean space whose restriction to the graph is an automorphism; the symmetry group of the Euclidean graph is the group of its symmetries. A Euclidean graph in three-dimensional Euclidean space is periodic if there exist three linearly independent translations whose restrictions to the net are symmetries of the net. Often (and always, if one is dealing with a crystal net), the periodic net has finitely many orbits, and is thus uniformly discrete in that there exists a minimum distance between any two vertices.
The result is a three-dimensional periodic graph as a geometric object.
The resulting crystal net will induce a lattice of vectors so that given three vectors that generate the lattice, those three vectors will bound a unit cell, i.e. a parallelepiped which, placed anywhere in space, will enclose a fragment of the net that repeats in the directions of the three axes. | 0 | Theoretical and Fundamental Chemistry |
EDC couples primary amines, and other nucleophiles, to carboxylic acids by creating an activated ester leaving group. First, the carbonyl of the acid attacks the carbodiimide of EDC, and there is a subsequent proton transfer. The primary amine then attacks the carbonyl carbon of the acid which forms a tetrahedral intermediate before collapsing and discharging the urea byproduct. The desired amide is obtained. | 1 | Applied and Interdisciplinary Chemistry |
Of special interest are ion-abundant liquid media (such as ionic liquids, molten salts, liquid electrolytes, etc.), which represent “liquid ions” with excellent tunable properties for different applications. The systems are famous for their ability to solvent-solute self-organization phenomena and are often employed in chemistry, biochemistry and pharmaceutical research. One of the most important features of ion-abundant liquid media is their huge potential to be fine-tuned. Thus, one can design an ionic liquid with virtually any combination of physicochemical or biochemical properties.
Research in the area of “liquid ions” is a rapidly developing scientific field, and numerous data on their properties and activities have been accumulated so far. Currently, the concept finds applications in catalysis, electrochemistry, analytics, fuel production, biomass processing, biotechnology, biochemistry and pharmaceutics. | 1 | Applied and Interdisciplinary Chemistry |
Most simply, the greater the steric hindrance the more difficult it is for reactions to take place, and the radical form is favored by default. For example, compare the hydrogen-abstracted form of N-hydroxypiperidine to the molecule TEMPO. TEMPO, or (2,2,6,6-Tetramethylpiperidin-1-yl)oxyl, is too sterically hindered by the additional methyl groups to react making it stable enough to be sold commercially in its radical form. N-Hydroxypiperidine, however, does not have the four methyl groups to impede the way of a reacting molecule so the structure is unstable. | 1 | Applied and Interdisciplinary Chemistry |
In prokaryotes, the 5’ NAD+ modification is established by bacterial RNAP during transcription initiation and has been shown to display functions analogous to those of the eukaryotic 5’ cap. In-vitro transcribed NAD-modified RNA was shown to be more resistant to RNase E, the main enzyme in the decay pathway of E. coli. NAD-modification further was shown to decelerate RNA processing by RNA pyrophosphohydrolase (RppH), which is known to trigger RNase-E-mediated decay through the conversion of 5′-triphosphate-RNA to 5′-monophosphate-RNA. Nudc, a nudix phosphohydrolase, can decap NAD-RNA through hydrolyzing NAD(H) into NMN(H) and AMP, causing RNase-E-mediated decay, but is inactive against 5′-triphosphate-RNA. This 5’ modification allows for the selective initiation of degradation for a subset of RNAs as the NAD-capped RNAs are stabilized in the presence of RppH, but are decapped by Nudc, while the 5′-triphosphate-RNAs are susceptible to RppH but not Nudc.
Next generation sequencing (NGS) of the NAD-RNA conjugates in E. coli revealed an abundance of a specific group of small regulatory RNAs (sRNAs) which are known to be involved in stress response systems, as well as enzymes involved in cellular metabolism. The small number of RNA transcripts with a NAD cap might allow the cell to selectively degrade these RNAs separate from other pathways. Considering that the stress responses are known to affect NAD+ concentration, this finding further supports the possibility of undiscovered pathways linking the energetic state of a cell to mRNA turnover.
NAD capping has also been suggested to recruit specific proteins to the 5’ end of the RNA as NAD is one of the most common protein ligands. NAD-binding pockets are well characterized in many proteins and could help the localization of the RNA to an enzyme or receptor. Many NAD-utilizing metabolic enzymes can also bind to RNA, presenting the possibility of unknown ribonucleoprotein complexes. | 1 | Applied and Interdisciplinary Chemistry |
Ethnoarchaeology has been widely used in conjunction with experimental archaeology using the techniques of modern peoples as analogues to the processes of the past. The attempted use of ethnology in archaeology tries to counteract the cultural distance of the researcher from process by changing the context of experimentation. Africa has played a large role in reconstructing copper smelting and bloomery iron furnaces as there are still several places that practice a workshop production of iron. Killick has been one such archaeologist to utilize surviving iron production in Africa to gain further insight into how other furnaces from around the world may have been constructed. | 1 | Applied and Interdisciplinary Chemistry |
Emollients, anti-pruritics, antifungals, antiseptics, scabicides, pediculicides, tar products, vitamin A derivatives, vitamin D analogues, keratolytics, abrasives, systemic antibiotics, topical antibiotics, hormones, desloughing agents, exudate absorbents, fibrinolytics, proteolytics, sunscreens, antiperspirants, corticosteroids, immune modulators. | 1 | Applied and Interdisciplinary Chemistry |
Fusion–fission designs essentially replace the lithium blanket with a blanket of fission fuel, either natural uranium ore or even nuclear waste. The fusion neutrons have more than enough energy to cause fission in the U, as well as many of the other elements in the fuel, including some of the transuranic waste elements. The reaction can continue even when all of the U is burned off; the rate is controlled not by the neutrons from the fission events, but the neutrons being supplied by the fusion reactor.
Fission occurs naturally because each event gives off more than one neutron capable of producing additional fission events. Fusion, at least in D-T fuel, gives off only a single neutron, and that neutron is not capable of producing more fusion events. When that neutron strikes fissile material in the blanket, one of two reactions may occur. In many cases, the kinetic energy of the neutron will cause one or two neutrons to be struck out of the nucleus without causing fission. These neutrons still have enough energy to cause other fission events. In other cases the neutron will be captured and cause fission, which will release two or three neutrons. This means that every fusion neutron in the fusion–fission design can result in anywhere between two and four neutrons in the fission fuel.
This is a key concept in the hybrid concept, known as fission multiplication. For every fusion event, several fission events may occur, each of which gives off much more energy than the original fusion, about 11 times. This greatly increases the total power output of the reactor. This has been suggested as a way to produce practical fusion reactors in spite of the fact that no fusion reactor has yet reached break-even, by multiplying the power output using cheap fuel or waste. However, a number of studies have repeatedly demonstrated that this only becomes practical when the overall reactor is very large, 2 to 3 GWt, which makes it expensive to build.
These processes also have the side-effect of breeding Pu or U, which can be removed and used as fuel in conventional fission reactors. This leads to an alternate design where the primary purpose of the fusion–fission reactor is to reprocess waste into new fuel. Although far less economical than chemical reprocessing, this process also burns off some of the nastier elements instead of simply physically separating them out. This also has advantages for non-proliferation, as enrichment and reprocessing technologies are also associated with nuclear weapons production. However, the cost of the nuclear fuel produced is very high, and is unlikely to be able to compete with conventional sources. | 0 | Theoretical and Fundamental Chemistry |
The cross-sectional area of the flow is calculated from a depth measurement and the average velocity of the flow is measured directly (Doppler and propeller methods are common). Velocity times the cross-sectional area yields a flow rate which can be integrated into volumetric flow. There are two types of area velocity flowmeter: (1) wetted; and (2) non-contact. Wetted area velocity sensors have to be typically mounted on the bottom of a channel or river and use Doppler to measure the velocity of the entrained particles. With depth and a programmed cross-section this can then provide discharge flow measurement. Non-contact devices that use laser or radar are mounted above the channel and measure the velocity from above and then use ultrasound to measure the depth of the water from above. Radar devices can only measure surface velocities, whereas laser-based devices can measure velocities sub-surface. | 1 | Applied and Interdisciplinary Chemistry |
* Water temperature
* Specific conductance or electrical conductance (EC) or conductivity
* Total suspended solids (TSS)
* Transparency or turbidity
* Water clarity
* Total dissolved solids (TDS)
* Odour of water
* Color of water (such as Forel-Ule scale or Pt/Co scale)
* Taste of water | 0 | Theoretical and Fundamental Chemistry |
The composition of gases present in the soils pores, referred to commonly as the soil atmosphere or atmosphere of the soil, is similar to that of the Earths atmosphere. Unlike the atmosphere, moreover, soil gas composition is less stagnant due to the various chemical and biological processes taking place in the soil. The resulting changes in composition from these processes can be defined by their variation time (i.e. daily vs. seasonal). Despite this spatial- and temporal-dependent fluctuation, soil gases typically boast greater concentrations of carbon dioxide and water vapor in comparison to the atmosphere. Furthermore, concentration of other gases, such as methane and nitrous oxide, are relatively minor yet significant in determining greenhouse gas flux and anthropogenic impact on soils. | 0 | Theoretical and Fundamental Chemistry |
Virtual screening is a very useful application when it comes to identifying hit molecules as a beginning for medicinal chemistry. As the virtual screening approach begins to become a more vital and substantial technique within the medicinal chemistry industry the approach has had an expeditious increase. | 1 | Applied and Interdisciplinary Chemistry |
In molecular biology and genetics, a blot is a method of transferring large biomolecules (proteins, DNA or RNA) onto a carrier, such as a membrane composed of nitrocellulose, polyvinylidene fluoride or nylon. In many instances, this is done after a gel electrophoresis, transferring the molecules from the gel onto the blotting membrane, and other times adding the samples directly onto the membrane. After the blotting, the transferred molecules are then visualized by colorant staining (for example, silver staining of proteins), autoradiographic visualization of radiolabelled molecules (performed before the blot), or specific labelling of some proteins or nucleic acids. The latter is done with antibodies or hybridization probes that bind only to some molecules of the blot and have an enzyme joined to them. After proper washing, this enzymatic activity (and so, the molecules found in the blot) is visualized by incubation with a proper reagent, rendering either a colored deposit on the blot or a chemiluminescent reaction which is registered by photographic film. | 1 | Applied and Interdisciplinary Chemistry |
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