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Over-fertilized plants are said to have less flavor, and too much nitrogen can be consumed by eating certain plants which have been over-fertilised (e.g., spinach). Advocates state that overfertilization is a risk in the first year if woodchips are used, which will break down too fast. Instead raised beds made with whole logs release nutrients slowly over a period of years. It has been suggested that excessive use of decomposing organic matter in Hügelkultur could leach out and contaminate and disrupt soil and water habitats. | 1 | Applied and Interdisciplinary Chemistry |
While a thermocouple wire type is often described by its chemical composition, the actual aim is to produce a pair of wires that follow a standardized curve.
Impurities affect each batch of metal differently, producing variable Seebeck coefficients.
To match the standard behaviour, thermocouple wire manufacturers will deliberately mix in additional impurities to "dope" the alloy, compensating for uncontrolled variations in source material.
As a result, there are standard and specialized grades of thermocouple wire, depending on the level of precision demanded in the thermocouple behaviour.
Precision grades may only be available in matched pairs, where one wire is modified to compensate for deficiencies in the other wire.
A special case of thermocouple wire is known as "extension grade", designed to carry the thermoelectric circuit over a longer distance.
Extension wires follow the stated curve but for various reasons they are not designed to be used in extreme environments and so they cannot be used at the sensing junction in some applications.
For example, an extension wire may be in a different form, such as highly flexible with stranded construction and plastic insulation, or be part of a multi-wire cable for carrying many thermocouple circuits.
With expensive noble metal thermocouples, the extension wires may even be made of a completely different, cheaper material that mimics the standard type over a reduced temperature range. | 1 | Applied and Interdisciplinary Chemistry |
Hemodynamics is the study of blood flow in the circulatory system. Blood flow in straight sections of the arterial tree are typically laminar (high, directed wall stress), but branches and curvatures in the system cause turbulent flow. Turbulent flow in the arterial tree can cause a number of concerning effects, including atherosclerotic lesions, postsurgical neointimal hyperplasia, in-stent restenosis, vein bypass graft failure, transplant vasculopathy, and aortic valve calcification. | 1 | Applied and Interdisciplinary Chemistry |
Bromophenol is also used as a colour marker to monitor the process of agarose gel electrophoresis and polyacrylamide gel electrophoresis. Since bromophenol blue carries a slight negative charge at moderate pH, it will migrate in the same direction as DNA or protein in a gel; the rate at which it migrates varies according to gel density and buffer composition, but in a typical 1% agarose gel in a 1X TAE buffer or TBE buffer, bromophenol blue migrates at the same rate as a DNA fragment of about 300 base pairs, in 2% agarose as 150 bp. Xylene cyanol and orange G may also be used for this purpose. | 0 | Theoretical and Fundamental Chemistry |
A metallurgical method employed in the purification of copper which contains copper oxide as an impurity and also in the purification of tin which contains tin oxide (stannic oxide or "SnO") as an impurity. The impure metal, usually in the form of molten blister copper, is placed in an anode furnace for two stages of refining. In the first stage, sulphur and iron are removed by gently blowing air through the molten metal to form iron oxides and sulfur dioxide. The iron oxides are skimmed or poured off the top of the copper and the gaseous sulfur dioxide exits the furnace via the off-gas system. Once the first oxidation stage is complete, the second stage (reduction or poling) begins. This involves using a reducing agent, normally natural gas or diesel (but ammonia, liquid petroleum gas, and naphtha can also be used), to react with the oxygen in the copper oxide to form copper . In the past, freshly cut ("green") trees were used as wooden poles. The sap in these poles acted as the reducing agent. The heat of the copper makes the pole emit wood gas(CO and H) that reduces the cuprous oxide to copper.
It was the use of these greenwood poles gave rise to the term "poling."
Care must be taken to avoid removing too much of the oxygen from the anode copper, as this will cause other impurities to change from their oxide to metallic states and they will remain in solid solution in the copper, reduce its conductivity and change its physical properties. Also upper surface can be covered with coke to prevent reoxidation of metal. | 1 | Applied and Interdisciplinary Chemistry |
The noncanonical PCP pathway regulates cell morphology, division, and movement. Once again Wnt proteins binds to and activates Frizzled so that Frizzled activates a Dishevelled protein that is tethered to the plasma membrane through a Prickle protein and transmembrane Stbm protein. The active Dishevelled activates RhoA GTPase through Dishevelled associated activator of morphogenesis 1 (Daam1) and the Rac protein. Active RhoA is able to induce cytoskeleton changes by activating Roh-associated kinase (ROCK) and affect gene transcription directly. Active Rac can directly induce cytoskeleton changes and affect gene transcription through activation of JNK. | 1 | Applied and Interdisciplinary Chemistry |
Some forms of ribosomal pause are reversible without needing to discard the translated peptide and mRNA. This sort, usually described as a slowdown, is usually caused by polyproline stretches (resolved by EFP or eIF5A) and uncharged tRNA. Slowdowns are important for the cell to control how much protein is produced; it also aids co-translational folding of the nascent polypeptide on the ribosome, and delays protein translation while its encoding mRNA; this can trigger ribosomal frameshifting.
More severe "stalls" can be caused an actual lack of tRNA or by the mRNA terminating without a stop codon. In this case, ribosomal quality control (RQC) performs crisis rescue by translational abandonment. This releases the ribosome from the mRNA. The incomplete polypeptide is targeted for destruction; in eukaryotes, mRNA no-go decay is also triggered.
It is difficult for RQC machinery to differentiate between a slowdown and a stall. It is possible for a mRNA sequence that normally produces a protein slowly to produce nothing instead due to intervention by RQC under different conditions. | 1 | Applied and Interdisciplinary Chemistry |
If one disregards the tangential components of the velocity field, as frequently done in the study of thin fluid film, one arrives at the following simplified system with only two unknowns: the two dimensional density and the normal velocity : | 1 | Applied and Interdisciplinary Chemistry |
EosFP consists of 226 amino acids. It has a molecular mass of 25.8 kDa and its pI is 6.9. Eos has 84% identical residues to Kaede, a fluorescent protein that originated in a different scleractinian coral Trachyphyllia geoffroyi, but can also be irreversibly converted from a green to red emitting form using UV light. Excluding residues Phe-61 and His-62, the chromophore environment and chromophore itself are unaffected by photochemical modification. Wild-type EosFP has a tetrameric arrangement of subunits where each subunit has the same β-can structure as GFP. This structure includes an 11-stranded barrel and, down the central axis, the fluorophore-containing helix. | 1 | Applied and Interdisciplinary Chemistry |
Heat is not to be confused with internal energy or synonymously thermal energy. While intimately connected to heat, they are distinct physical quantities.
As a heating technology, Joule heating has a coefficient of performance of 1.0, meaning that every joule of electrical energy supplied produces one joule of heat. In contrast, a heat pump can have a coefficient of more than 1.0 since it moves additional thermal energy from the environment to the heated item.
The definition of the efficiency of a heating process requires defining the boundaries of the system to be considered. When heating a building, the overall efficiency is different when considering heating effect per unit of electric energy delivered on the customer's side of the meter, compared to the overall efficiency when also considering the losses in the power plant and transmission of power. | 0 | Theoretical and Fundamental Chemistry |
He was born in Logroño, La Rioja, Spain son of Basque-French parents from Hasparren, France.
Between 1773 and 1777, Elhúyar studied medicine, surgery and chemistry, as well as mathematics, physics and natural history with his brother Juan José Elhuyar in Paris. After graduating, he returned to Spain, where he exercised himself in the study of mineralogy, specially that of the Basque Country and Navarre, where he resided. In 1781, he was appointed a member of the Real Sociedad Bascongada de Amigos del País (Royal Basque Society of Friends to the Country), an enlightened institution thanks to which he started teaching as professor of mineralogy and metallurgy in Bergara, the seat of both the Vascongada Society and the University of Vergara (nowadays merged with the University of the Basque Country). During those years, he published numerous articles and dossiers about minerals, ways to extract and purify them, etc., which made him famous throughout Europe as one of the top experts on the subject. In 1780, he started working in the Laboratorium Chemicum of Vergara along with François Chavaneau, with whom he was the first to purify platinum. After several months, he was the first person to discover and isolate tungsten, of which hes credited, along with his brother Juan José, as its discoverer. He also collaborated with Joseph-Louis Proust, the famous French chemist at the service of king Charles IV of Spain, who directed the National Laboratory' in Segovia.
In 1783, he visited several European universities, such as the School of Mines of Freiberg, at which he lectured on metallurgy and mine machinery; the University of Uppsala, where he collaborated with Torbern Olof Bergman; and Köping, where he visited Carl Wilhelm Scheele, the one who announced Elhúyar's discovery of tungsten, and for some reason is credited for having made the discovery himself.
After his return to Spain, in 1785 he renounced his professorship and, in July 1786, was appointed General Director of Mines in Mexico. Before departing to his new office, he toured Europe again from 1786 to 1788 in order to study Borns method on refining silver. During this trip, he married Joan Raab in Vienna, in 1787. For the next thirty three years, he resided in Mexico City, where the crown founded the capitals School of Mines (January 1, 1792), with Elhuyar as its first director. During his tenure, he commissioned and directed the construction of that institutions seat, the Palacio de Minería, which was finished in 1813 and is considered one of the jewels of the Spanish American neoclassicism. He also visited and improved several of the existing Royal Mines of Mexico, dramatically increasing their productivity due to the introduction of new methods of exploitation. He aided Alexander von Humboldt during his time in New Spain, along with other mining experts then in Mexico, allowing Humboldts section on mining in his Political essay on the Kingdom of New Spain to be replete with statistics and insights.
After Mexican Independence, he returned to Spain, where, due to his wide experience in modern minery methods, he was appointed Minister of Minery in 1822, and supervised the modern mining of the mines in Almadén, Guadalcanal, and Río Tinto. After falling from his ministry, he was appointed yet again General Director of Mines, and resumed his research activities in chemistry from this quieter office till his death in Madrid on January 6, 1833. | 1 | Applied and Interdisciplinary Chemistry |
Prelog attended elementary school in Sarajevo, but in 1915, as a child, Prelog moved to Zagreb (then part of the Austro-Hungary) with his parents. In Zagreb he graduated from elementary school. At first, he attended gymnasium in Zagreb, but soon afterwards, his father got a job in Osijek, so he continued his education there. He spent two years in Osijek gymnasium, where he became interested in chemistry under the influence of his professor Ivan Kuria.
In 1922, as a 16-year-old boy, his first scientific work was published in the German scientific journal Chemiker Zeitung. The article concerned an analytical instrument used in chemical labs. Prelog completed his high school education in Zagreb in 1924. Following his fathers wishes, he moved to Prague, where he received his diploma in chemical engineering from the Czech Technical University in 1928. He received his Sc.D in 1929. His teacher was Emil Votoček, while his assistant and mentor Rudolf Lukeš introduced him to the world of organic chemistry.
Upon leaving the Czech Technical University, Prelog worked in the plant laboratory of the private firm of G.J. Dríza in Prague; few academic positions were available due to the Great Depression. Prelog was in charge of the production of rare chemicals that were not commercially available at that time. He worked for Driza from 1929 until 1935. During the time, he got his first doctoral candidate, a company owner at Driza. He performed research in his spare time, investigating alkaloids in cacao bark. | 0 | Theoretical and Fundamental Chemistry |
The phase structure of quark matter remains mostly conjectural because it is difficult to perform calculations predicting the properties of quark matter. The reason is that QCD, the theory describing the dominant interaction between quarks, is strongly coupled at the densities and temperatures of greatest physical interest, and hence it is very hard to obtain any predictions from it. Here are brief descriptions of some of the standard approaches. | 0 | Theoretical and Fundamental Chemistry |
Defined by flows through a system, a flow process is a steady state of flow into and out of a vessel with definite wall properties. The internal state of the vessel contents is not the primary concern. The quantities of primary concern describe the states of the inflow and the outflow materials, and, on the side, the transfers of heat, work, and kinetic and potential energies for the vessel. The states of the inflow and outflow materials consist of their internal states, and of their kinetic and potential energies as whole bodies. Very often, the quantities that describe the internal states of the input and output materials are estimated on the assumption that they are bodies in their own states of internal thermodynamic equilibrium. Because rapid reactions are permitted, the thermodynamic treatment may be approximate, not exact. | 0 | Theoretical and Fundamental Chemistry |
ESP was first developed and published in 2003 by Dr. Collins and his colleagues in University of California, San Francisco. Their study revealed the chromosome rearrangements and CNV of MCF7 human cancer cells at a 150kb resolution, which is much more accurate compared to both CGH and spectral karyotyping at that time. In 2007, Dr. Snyder and his group improved the ESP to 3kb resolution by sequencing both pairs of 3-kb DNA fragments without BAC construction. Their approach is able to identify deletions, inversions, insertions with an average breakpoint resolution of 644bp, which close to the resolution of polymerase chain reaction (PCR). | 1 | Applied and Interdisciplinary Chemistry |
Manufacturers such as Victaulic and Grinnell produce sleeve-clamp fittings, which replace many flange connections. They attach to the end of a pipe segment via circumferential grooves pressed (or cut) around the end of the pipe to be joined. They are widely used on larger steel pipes and can also be used with other materials.
The chief advantage of these connectors is that they can be installed after cutting the pipe to length in the field. This can save time and considerable expense compared to flange connections, which must be factory- or field-welded to pipe segments. However, mechanically fastened joints are sensitive to residual and thickness stresses caused by dissimilar metals and temperature changes.
A grooved fitting, also known as a grooved coupling, has four elements: grooved pipe, gasket, coupling housing, and nuts and bolts. The groove is made by cold-forming (or machining) a groove at the end of a pipe. A gasket encompassed by coupling housing is wrapped around the two pipe ends, with the coupling engaging the groove; the bolts and nuts are tightened with a socket or impact wrench. The installed coupling housing encases the gasket and engages the grooves around the pipe to create a leakproof seal in a self-restrained pipe joint. There are two types of grooved coupling; a flexible coupling allows a limited amount of angular movement, and a rigid coupling does not allow movement and may be used where joint immobility is required (similar to a flange or welded joint). | 1 | Applied and Interdisciplinary Chemistry |
There are 2 regular complex apeirogons, sharing the vertices of the trihexagonal tiling. Regular complex apeirogons have vertices and edges, where edges can contain 2 or more vertices. Regular apeirogons p{q}r are constrained by: 1/p + 2/q + 1/r = 1. Edges have p vertices arranged like a regular polygon, and vertex figures are r-gonal.
The first is made of triangular edges, two around every vertex, second has hexagonal edges, two around every vertex. | 0 | Theoretical and Fundamental Chemistry |
In quantum mechanics, the energy levels of electrons in atoms depend on the reduced mass of the system of electron and nucleus. For the hydrogen atom, the role of reduced mass is most simply seen in the Bohr model of the atom, where the reduced mass appears in a simple calculation of the Rydberg constant and Rydberg equation, but the reduced mass also appears in the Schrödinger equation, and the Dirac equation for calculating atomic energy levels.
The reduced mass of the system in these equations is close to the mass of a single electron, but differs from it by a small amount about equal to the ratio of mass of the electron to the nucleus. For normal hydrogen, this amount is about , or 1.000545, and for deuterium it is even smaller: , or 1.0002725. The energies of electronic spectra lines for H and H therefore differ by the ratio of these two numbers, which is 1.000272. The wavelengths of all deuterium spectroscopic lines are shorter than the corresponding lines of light hydrogen, by 0.0272%. In astronomical observation, this corresponds to a blue Doppler shift of 0.0272% of the speed of light, or 81.6 km/s.
The differences are much more pronounced in vibrational spectroscopy such as infrared spectroscopy and Raman spectroscopy, and in rotational spectra such as microwave spectroscopy because the reduced mass of the deuterium is markedly higher than that of protium. In nuclear magnetic resonance spectroscopy, deuterium has a very different NMR frequency (e.g. 61 MHz when protium is at 400 MHz) and is much less sensitive. Deuterated solvents are usually used in protium NMR to prevent the solvent from overlapping with the signal, though deuterium NMR on its own right is also possible. | 0 | Theoretical and Fundamental Chemistry |
Tetraanthraporphyrin, or tetraanthra[2,3]porphyrin (TAP), is a representative of extended porphyrins.
Despite promising properties, tetraanthraporphyrins have until recently been little studied. As was theoretically predicted,
extension of pi-electronic system results in the case of TAPs in the destabilization of the third LUMOs and the first HOMOs that makes it unstable against oxidation and reduction. | 1 | Applied and Interdisciplinary Chemistry |
One conducting polymer coating that has shown promising results for improving the performance of neural electrodes is polypyrrole (PPy). Polypyrrole has great biocompatibility and conductive properties, which makes it a good option for the use in neural electrodes. PPy has been shown to have a good interaction with biological tissues. This is due to the boundary it creates between the hard electrode and the soft tissue. PPy has been shown to support cell adhesion and growth of a number of different cell types including primary neurons which is important in neural implants. PPy also decreases the impedance of the electrode system by increasing the roughness on the surface. The roughness on the electrode surface is directly related to an increased surface area (increased neuron interface with electrode) which increases the signal conduction. In one paper, polypyrrole (PPy) was doped with polystyrene sulfonate (PSS) to electrochemically deposit a polypyrrole coating on the electrode surface. The film was coated onto the electrode at different thickness, increasing the roughness. The increased roughness (increased effective surface) leads to a decreased overall electrode impedance from about 400 kΩ (bare stent) to less than 10 kΩ (PPy/PSS coating) at 1 kHz. This decrease in impedance leads to improved charge transfer from the electrode to the tissue and an overall more effective electrode for recording and stimulating applications. | 0 | Theoretical and Fundamental Chemistry |
The current production method is based on the first scalable synthesis developed by Gilead Sciences starting from naturally occurring quinic acid or shikimic acid. Due to lower yields and the extra steps required (because of the additional dehydration), the quinic acid route was dropped in favour of the one based on shikimic acid, which received further improvements by Hoffmann-La Roche.
The current industrial synthesis is summarised below: | 0 | Theoretical and Fundamental Chemistry |
Neopterin is an organic compound belonging to the pteridine class of heterocyclic compounds.
Neopterin belongs to the chemical group known as pteridines. It is synthesised by human macrophages upon stimulation with the cytokine interferon-gamma and is indicative of a pro-inflammatory immune status. Neopterin serves as a marker of cellular immune system activation. In humans neopterin follows a circadian and circaseptan rhythm. | 1 | Applied and Interdisciplinary Chemistry |
In a system of Euclidean spatial dimension that has an arbitrary number of components, the sum is made over all the constituents. and are respectively the fraction and the conductivity of each component, and is the effective conductivity of the medium. (The sum over the 's is unity.) | 0 | Theoretical and Fundamental Chemistry |
Further work by Goossen et al. described the synthesis of ketones from α-oxocarboxylic acids with aryl or heteroaryl bromides through an acyl anion intermediate. | 0 | Theoretical and Fundamental Chemistry |
This family of clusters includes the closo cages . This family of clusters are also lightly studied owing to synthetic difficulties. Also reflecting synthetic challenges, many of these compounds are best known as their alkyl derivatives. 1,5- is the only known isomer of the five-vertex cage. It is prepared from the reaction of pentaborane(9) with acetylene in two operations beginning with condensation with acetylene followed by pyrolysis (cracking) of the product:
: nido-2,3-
: closo-2,3- | 0 | Theoretical and Fundamental Chemistry |
Specific dynamic action (SDA), also known as thermic effect of food (TEF) or dietary induced thermogenesis (DIT), is the amount of energy expenditure above the basal metabolic rate due to the cost of processing food for use and storage. Heat production by brown adipose tissue which is activated after consumption of a meal is an additional component of dietary induced thermogenesis. The thermic effect of food is one of the components of metabolism along with resting metabolic rate and the exercise component. A commonly used estimate of the thermic effect of food is about 10% of one's caloric intake, though the effect varies substantially for different food components. For example, dietary fat is very easy to process and has very little thermic effect, while protein is hard to process and has a much larger thermic effect. | 1 | Applied and Interdisciplinary Chemistry |
Hexamer primers are sequences composed of six random nucleotides. For MDA applications, these primers are usually thiophosphate-modified at their 3’ end to convey resistance to the 3’–5’ exonuclease activity of Ф29 DNA polymerase. MDA reactions start with the annealing of such primers to the DNA template followed by polymerase-mediated chain elongation. Increasing numbers of primer annealing events happen along the amplification reaction. | 1 | Applied and Interdisciplinary Chemistry |
Absorption is the journey of a drug travelling from the site of administration to the site of action.
The drug travels by some route of administration (oral, topical-dermal, etc.) in a chosen dosage form (e.g., tablets, capsules, or in solution). Absorption by some other routes, such as intravenous therapy, intramuscular injection, enteral nutrition, is even more straightforward and there is less variability in absorption and bioavailability is often near 100%. Intravascular administration does not involve absorption, and there is no loss of drug. The fastest route of absorption is inhalation.
Absorption is a primary focus in drug development and medicinal chemistry, since a drug must be absorbed before any medicinal effects can take place. Moreover, the drug's pharmacokinetic profile can be easily and significantly changed by adjusting factors that affect absorption. | 1 | Applied and Interdisciplinary Chemistry |
The introduction of lasers in atomic manipulation experiments was the precursor to the laser cooling proposals in the mid 1970s. Laser cooling was proposed separately in 1975 by two different research groups: Hänsch and Schawlow,
and Wineland and Dehmelt. Both proposals outlined the simplest laser cooling process, known as Doppler cooling, where laser light below an atom's resonant frequency is repeatedly absorbed and the velocity distribution of the atoms is reduced.
In 1977 Ashkin submitted a paper which describes how Doppler cooling could be used to provide the necessary damping to load atoms into an optical trap. In this work he emphasized how this process could allow for long spectroscopic measurements without the atoms escaping the trap and proposed the overlapping of optical traps in order to study interactions between different atoms. | 0 | Theoretical and Fundamental Chemistry |
The Dalitz plot is a two-dimensional plot often used in particle physics to represent the relative frequency of various (kinematically distinct) manners in which the products of certain (otherwise similar) three-body decays may move apart.
The phase-space of a decay of a pseudoscalar into three spin-0 particles can be completely described using two variables. In a traditional Dalitz plot, the axes of the plot are the squares of the invariant masses of two pairs of the decay products. (For example, if particle A decays to particles 1, 2, and 3, a Dalitz plot for this decay could plot m on the x-axis and m on the y-axis.) If there are no angular correlations between the decay products then the distribution of these variables is flat. However symmetries may impose certain restrictions on the distribution. Furthermore, three-body decays are often dominated by resonant processes, in which the particle decays into two decay products, with one of those decay products immediately decaying into two additional decay products. In this case, the Dalitz plot will show a non-uniform distribution, with a peak around the mass of the resonant decay. In this way, the Dalitz plot provides an excellent tool for studying the dynamics of three-body decays.
Dalitz plots play a central role in the discovery of new particles in current high-energy physics experiments, including Higgs boson research, and are tools in exploratory efforts that might open avenues beyond the Standard Model.
R.H. Dalitz introduced this technique in 1953 to study decays of K mesons (which at that time were still referred to as "tau-mesons"). It can be adapted to the analysis of four-body decays as well. A specific form of a four-particle Dalitz plot (for non-relativistic kinematics), which is based on a tetrahedral coordinate system, was first applied to study the few-body dynamics in atomic four-body fragmentation processes. | 0 | Theoretical and Fundamental Chemistry |
Electroanalytical methods utilize the potential or current of a electrochemical cell. The three main sections of this type of analysis are potentiometry, coulometry and voltammetry. Potentiometry measures the cells potential, coulometry measures the cells current, and voltammetry measures the change in current when cell potential changes. | 0 | Theoretical and Fundamental Chemistry |
Thomas Messinger Drown (March 19, 1842 – November 17, 1904) was the fourth University President of Lehigh University in Bethlehem, Pennsylvania, United States. He was also an analytical chemist and metallurgist. | 0 | Theoretical and Fundamental Chemistry |
Depending on the virus, a variety of genetic changes can occur in the host cell. In the case of a lytic cycle virus, the cell will only survive long enough to the replication machinery to be used to create additional viral units. In other cases, the viral DNA will persist within the host cell and replicate as the cell replicates. This viral DNA can either be incorporated into the host cells genetic material or persist as a separate genetic vector. Either case can lead to damage of the host cells chromosomes. It is possible that the damage can be repaired; however, the most common result is an instability in the original genetic material or suppression or alteration of the gene expression. | 1 | Applied and Interdisciplinary Chemistry |
It also brings around the conversion of a hydrazone to a diazo compound, for example in the diazo-thioketone coupling. It also converts thioacetals to their parent carbonyl compounds. | 0 | Theoretical and Fundamental Chemistry |
In organic chemistry, a dipolar compound or simply dipole is an electrically neutral molecule carrying a positive and a negative charge in at least one canonical description. In most dipolar compounds the charges are delocalized.
Unlike salts, dipolar compounds have charges on separate atoms, not on positive and negative ions that make up the compound. Dipolar compounds exhibit a dipole moment.
Dipolar compounds can be represented by a resonance structure. Contributing structures containing charged atoms are denoted as zwitterions.
Some dipolar compounds can have an uncharged canonical form. | 0 | Theoretical and Fundamental Chemistry |
An auxiliary bridge allows armourstone to be directly deposited into the closing gap. This method was contemplated for the Delta Works' Oesterdam closure but was ultimately deemed more expensive than sand closure. In the Netherlands, such a technique was applied during the closure of the dike around De Biesbosch polder in 1926, where a temporary bridge facilitated the dumping of materials into the gap using tipping carts propelled by a steam locomotive. | 1 | Applied and Interdisciplinary Chemistry |
Aeration times vary according to the plant size and the composition/quantity of the incoming liquor, but are typically 60 to 90 minutes. The addition of oxygen to the liquor encourages the multiplication of aerobic bacteria and they consume the nutrients. This process encourages the conversion of nitrogen from its reduced ammonia form to oxidized nitrite and nitrate forms, a process known as nitrification.
To remove phosphorus compounds from the liquor, aluminium sulfate (alum) is often added during this period. It reacts to form non-soluble compounds, which settle into the sludge in the next stage.
The settling stage is usually the same length in time as the aeration. During this stage the sludge formed by the bacteria is allowed to settle to the bottom of the tank. The aerobic bacteria continue to multiply until the dissolved oxygen is all but used up. Conditions in the tank, especially near the bottom are now more suitable for the anaerobic bacteria to flourish. Many of these, and some of the bacteria which would prefer an oxygen environment, now start to use oxidized nitrogen instead of oxygen gas (as an alternate terminal electron acceptor) and convert the nitrogen to a gaseous state, as nitrogen oxides or, ideally, molecular nitrogen (dinitrogen, N) gas. This is known as denitrification.
An anoxic SBR can be used for anaerobic processes, such as the removal of ammonia via Anammox, or the study of slow-growing microorganisms. In this case, the reactors are purged of oxygen by flushing with inert gas and there is no aeration.
As the bacteria multiply and die, the sludge within the tank increases over time and a waste activated sludge (WAS) pump removes some of the sludge during the settling stage to a digester for further treatment. The quantity or “age” of sludge within the tank is closely monitored, as this can have a marked effect on the treatment process.
The sludge is allowed to settle until clear water is on the top 20 to 30 percent of the tank contents.
The decanting stage most commonly involves the slow lowering of a scoop or “trough” into the basin. This has a piped connection to a lagoon where the final effluent is stored for disposal to a wetland, tree plantation, ocean outfall, or to be further treated for use on parks, golf courses etc. | 1 | Applied and Interdisciplinary Chemistry |
The Young equation assumes a perfectly flat and rigid surface often referred to as an ideal surface. In many cases, surfaces are far from this ideal situation, and two are considered here: the case of rough surfaces , to the so-called receding contact angle, . The equilibrium contact angle () can be calculated from and as was shown by Tadmor as,
where | 0 | Theoretical and Fundamental Chemistry |
Gibson & Ashby micromechanical models for porous materials provide mathematical equations for the prediction of mechanical parameters based on experimentally determined geometric constants. The constants of proportionality are determined by fitting experimental data to various mathematical models for structures consisting of cubes and solid struts and are dependent upon cell geometry. A limitation of the Gibson & Ashby model is that it is most accurate for foams exhibiting porosities higher than 70%, although experimental comparisons for lower porosity foams have shown agreement with this model. Ye & Dunand found reasonable agreement to the Gibson & Ashby model for titanium foams exhibiting 42% porosity. Ultrasonic measurements provided an average Young's modulus value of 39 GPa, which is in relatively good agreement with the Gibson & Ashby prediction of 35 GPa.
The Gibson & Ashby models assume ideal structures; microstructural irregularities (e.g. inhomogeneous pore distribution; defects) are not considered. Additionally, experimental results from which the predetermined proportionality constants were based on experimental values that were obtained from simple compression tests. Consequently, they may not be applicable for multiaxial loads. | 0 | Theoretical and Fundamental Chemistry |
The shower-curtain effect in physics describes the phenomenon of a shower curtain being blown inward when a shower is running. The problem of identifying the cause of this effect has been featured in Scientific American magazine, with several theories given to explain the phenomenon but no definite conclusion.
The shower-curtain effect may also be used to describe the observation how nearby phase front distortions of an optical wave are more severe than remote distortions of the same amplitude. | 1 | Applied and Interdisciplinary Chemistry |
The Leuckart thiophenol reaction is the decomposition of a diazoxanthate, by gentle warming in a slightly acidic cuprous medium, to its corresponding aryl xanthates which give aryl thiols on alkaline hydrolysis and aryl thioethers on further warming.
This reaction was first reported by Rudolf Leuckart in 1890. | 0 | Theoretical and Fundamental Chemistry |
Untreated organic matter that contains fecal coliform can be harmful to the environment. Aerobic decomposition of this material can reduce dissolved oxygen levels if discharged into rivers or waterways. This may reduce the oxygen level enough to kill fish and other aquatic life. Reduction of fecal coliform in wastewater may require the use of chlorine and other disinfectant chemicals, or UV disinfection treatment. Such materials may kill the fecal coliform and disease bacteria. They also kill bacteria essential to the proper balance of the aquatic environment, endangering the survival of species dependent on those bacteria. So higher levels of fecal coliform require higher levels of chlorine, threatening those aquatic organisms. | 0 | Theoretical and Fundamental Chemistry |
Palmitoylcarnitine contains the saturated fatty acid known as palmitic acid (C16:0) which is bound to the β-hydroxy group of the carnitine. The core carnitine structure, consisting of butanoate with a quaternary ammonium attached to C4 and hydroxy group at C3, is a common molecular backbone for the transfer of multiple long chain fatty acids in the TCA cycle. | 1 | Applied and Interdisciplinary Chemistry |
Photosensitizers have existed within natural systems for as long as chlorophyll and other light sensitive molecules have been a part of plant life, but studies of photosensitizers began as early as the 1900s, where scientists observed photosensitization in biological substrates and in the treatment of cancer. Mechanistic studies related to photosensitizers began with scientists analyzing the results of chemical reactions where photosensitizers photo-oxidized molecular oxygen into peroxide species. The results were understood by calculating quantum efficiencies and fluorescent yields at varying wavelengths of light and comparing these results with the yield of reactive oxygen species. However, it was not until the 1960s that the electron donating mechanism was confirmed through various spectroscopic methods including reaction-intermediate studies and luminescence studies.
The term photosensitizer does not appear in scientific literature until the 1960s. Instead, scientists would refer to photosensitizers as sensitizers used in photo-oxidation or photo-oxygenation processes. Studies during this time period involving photosensitizers utilized organic photosensitizers, consisting of aromatic hydrocarbon molecules, which could facilitate synthetic chemistry reactions. However, by the 1970s and 1980s, photosensitizers gained attraction in the scientific community for their role within biologic processes and enzymatic processes. Currently, photosensitizers are studied for their contributions to fields such as energy harvesting, photoredox catalysis in synthetic chemistry, and cancer treatment. | 0 | Theoretical and Fundamental Chemistry |
The earliest application of photoredox catalysis to Reductive dehalogenation were limited by narrow substrate scope or competing reductive coupling.
Unactivated carbon-iodine bonds can be reduced using the strongly reducing photocatalyst tris-(2,2’-phenylpyridine)iridium (Ir(ppy)). The increased reduction potential of Ir(ppy) compared to [Ru(bipy)] allows direct reduction of the carbon-iodine bond without interacting with a stoichiometric reductant. Thus, the iridium complex transfers an electron to the substrate, causing fragmentation of the substrate and oxidizing the catalyst to the Ir(IV) oxidation state. The oxidized photocatalyst is returned to its original oxidation state by oxidising a reaction additives.
Like tin-mediated radical dehalogenation reactions, photocatalytic reductive dehalogenation can be used to initiate cascade cyclizations | 0 | Theoretical and Fundamental Chemistry |
The Stöber process is a sol-gel approach to preparing monodisperse (uniform) spherical silica () materials that was developed by a team led by Werner Stöber and reported in 1968. The process, an evolution and extension of research described in Gerhard Kolbe's 1956 Ph.D. dissertation, was an innovative discovery that still has wide applications more than 50 years later. Silica precursor tetraethyl orthosilicate (, TEOS) is hydrolyzed in alcohol (typically methanol or ethanol) in the presence of ammonia as a catalyst:
The reaction produces ethanol and a mixture of ethoxysilanols (such as , , and even ), which can then condense with either TEOS or another silanol with loss of alcohol or water:
Further hydrolysis of the ethoxy groups and subsequent condensation leads to crosslinking. It is a one-step process as the hydrolysis and condensation reactions occur together in a single reaction vessel.
The process affords microscopic particles of colloidal silica with diameters ranging from 50 to 2000 nm; particle sizes are fairly uniform with the distribution determined by the choice of conditions such as reactant concentrations, catalysts, and temperature. Larger particles are formed when the concentrations of water and ammonia are raised, but with a consequent broadening of the particle-size distribution. The initial concentration of TEOS is inversely proportional to the size of the resulting particles; thus, higher concentrations on average lead to smaller particles due to the greater number of nucleation sites, but with a greater spread of sizes. Particles with irregular shapes can result when the initial precursor concentration is too high. The process is temperature-dependent, with cooling (and hence slower reaction rates) leading to a monotonic increase in average particle size, but control distribution cannot be maintained at overly low temperatures. | 0 | Theoretical and Fundamental Chemistry |
The modern approach is to carry out DNA–DNA hybridization in silico utilizes completely or partially sequenced genomes. The [http://ggdc.dsmz.de GGDC] and [https://tygs.dsmz.de/ TYGS] developed at DSMZ are the most accurate known tools for calculating DDH-analogous values. Among other algorithmic improvements, it solves the problem with paralogous sequences by carefully filtering them from the matches between the two genome sequences. The method has been used for resolving difficult taxa such as Escherichia coli, Bacillus cereus group, and Aeromonas. The Judicial Commission of International Committee on Systematics of Prokaryotes has admitted dDDH as taxonomic evidence. | 1 | Applied and Interdisciplinary Chemistry |
The School of Chemistry is a school of the University of Edinburgh, in Scotland. In the 2008 Research Assessment Exercise (RAE) the school was ranked sixth in the UK. | 1 | Applied and Interdisciplinary Chemistry |
Gamma radiation penetrates further through matter than alpha or beta radiation. Most of the design of a typical fallout shelter is intended to protect against gamma rays. Gamma rays are better absorbed by materials with high atomic numbers and high density, although neither effect is important compared to the total mass per area in the path of the gamma ray. Thus, lead is only modestly better as a gamma shield than an equal mass of another shielding material such as aluminum, concrete, water or soil.
Some gamma radiation from fallout will penetrate into even the best shelters. However, the radiation dose received while inside a shelter can be significantly reduced with proper shielding. Ten halving thicknesses of a given material can reduce gamma exposure to less than of unshielded exposure. | 0 | Theoretical and Fundamental Chemistry |
The Rhodopsin haloprotein family shares the ligand retinal, one of the many types of Vitamin A. Retinal is a conjugated poly-unsaturated chromophore (polyene), obtained from carnivorous diet or by the carotene pathway (β-carotene 15,15'-monoxygenase). | 0 | Theoretical and Fundamental Chemistry |
A few molecules have a tetrahedral geometry with no central atom. An inorganic example is tetraphosphorus () which has four phosphorus atoms at the vertices of a tetrahedron and each bonded to the other three. An organic example is tetrahedrane () with four carbon atoms each bonded to one hydrogen and the other three carbons. In this case the theoretical C−C−C bond angle is just 60° (in practice the angle will be larger due to bent bonds), representing a large degree of strain. | 0 | Theoretical and Fundamental Chemistry |
Al-Kindi authored works on a number of important mathematical subjects, including arithmetic, geometry, the Hindu numbers, the harmony of numbers, lines and multiplication with numbers, relative quantities, measuring proportion and time, and numerical procedures and cancellation. He also wrote four volumes, On the Use of the Hindu Numerals ( Kitāb fī Isti`māl al-A`dād al-Hindīyyah') which contributed greatly to diffusion of the Hindu system of numeration in the Middle-East and the West. In geometry, among other works, he wrote on the theory of parallels. Also related to geometry were two works on optics. One of the ways in which he made use of mathematics as a philosopher was to attempt to disprove the eternity of the world by demonstrating that actual infinity is a mathematical and logical absurdity. | 1 | Applied and Interdisciplinary Chemistry |
The material with which a pipe is manufactured is often the basis for choosing a pipe. Materials used for manufacturing pipes include:
* Carbon (CS) and galvanized steel
* Impact-tested carbon steel (ITCS)
* Low-temperature carbon steel (LTCS)
* Stainless steel (SS)
* Malleable iron
* Chrome-molybdenum (alloy) steel (generally used for high-temperature service)
* Non-ferrous metals (includes copper, inconel, incoloy, and cupronickel)
* Non-metallic (includes acrylonitrile butadiene styrene (ABS), fibre-reinforced plastic (FRP), polyvinyl chloride (PVC), chlorinated polyvinyl chloride (CPVC), high-density polyethylene (HDPE), Cross-linked polyethylene (PEX), and toughened glass; polybutylene has also been used, but is now banned in North America because of poor reliability)
The bodies of fittings for pipe and tubing are often the same base material as the pipe or tubing connected: copper, steel, PVC, CPVC, or ABS. Any material permitted by the plumbing, health, or building code (as applicable) may be used, but it must be compatible with the other materials in the system, the fluids being transported, and the temperature and pressure inside (and outside) the system. Brass or bronze fittings are common in copper piping and plumbing systems. Fire resistance, earthquake resistance, mechanical ruggedness, theft resistance, and other factors also influence the choice of pipe and fitting materials. | 1 | Applied and Interdisciplinary Chemistry |
Kallidin is a bioactive kinin formed in response to injury from kininogen precursors through the action of kallikreins.
Kallidin is a decapeptide whose sequence is H-Lys-Arg-Pro-Pro-Gly-Phe-Ser-Pro-Phe-Arg-OH. It can be converted to bradykinin by the aminopeptidase enzyme.
It can be a substrate for carboxypeptidase M and N.
Kallidin is identical to bradykinin with an additional lysine residue added at the N-terminal end and signals through the bradykinin receptor. | 1 | Applied and Interdisciplinary Chemistry |
RNA interference (RNAi) methods can be used to transiently silence or knockdown gene expression using ~20 base-pair double-stranded RNA typically delivered by transfection of synthetic ~20-mer short-interfering RNA molecules (siRNAs) or by virally encoded short-hairpin RNAs (shRNAs). RNAi screens, typically performed in cell culture-based assays or experimental organisms (such as C. elegans) can be used to systematically disrupt nearly every gene in a genome or subsets of genes (sub-genomes); possible functions of disrupted genes can be assigned based on observed phenotypes. | 1 | Applied and Interdisciplinary Chemistry |
The Underground House in Ward, Colorado, was a subterranean dwelling known for its architectural design, which embraced the concept of underground living. The house was designed by architect Julian "Jay" Swayze (1923–1981) in the 1960s. The dwelling is an example of an unconventional approach to residential construction and integration with the natural environment. It was included in the Underground World Home exhibit at the 1964 New York World's Fair. | 0 | Theoretical and Fundamental Chemistry |
In 2019, Floriana participated in a research which reported the capability of a MFI-type zeolite (NbAlS-1) could be used to convert aqueous solutions of γ-valerolactone (GVL) (obtained from biomass-derived carbohydrates) into butenes with a yield of more than 99% at ambient pressure under continuous flow conditions. The conversion of the renewable biomass into butenes offered the prospect for the sustainable production of butene as a platform chemical for the manufacture of renewable materials.
In 2019, she participated in a research which showed the capability to use a porous metal–organic framework (MOF) to provide a selective, fully reversible and repeatable capability to capture nitrogen dioxide (NO), a toxic air pollutant produced particularly by diesel and bio-fuel use. The NO can then be easily converted into nitric acid, an industry with a wide range of uses including, agricultural fertilizer for crops; rocket propellant and nylon.
In 2016, Floriana confirmed the capability to use pulsed EPR spectroscopy to measure the covalency of actinide complexes in a research in collaboration with Eric McInnes and David P. Mills at the University of Manchester. Prior to this research, the extent of covalency in actinide complexes was less understood as this nature of bonding was not studied due to limited technology and methods of experimentation at the time. The use of pulsed EPR spectroscopy was able to determine the covalency of thorium and Uranium complexes for the first time and this paved the way to further research on the use of these complexes in the separation and recycling of nuclear waste. | 0 | Theoretical and Fundamental Chemistry |
*2001 – Chester F. Carlson Award, American Society for Engineering Education
*2006 – Distinguished Alumni Award, University of Minnesota
*2006 – Distinguished Service Award, American Society for Engineering Education
*2014 – Honorary Doctorate, University of Technology Malaysia
*2015 – Lifetime Achievement Award, American Society for Engineering Education
*2023 – Hall of Fame, American Society for Engineering Education | 1 | Applied and Interdisciplinary Chemistry |
Molecules adsorbed on a surface are picked up by a
microscopic tip (nanometres wide) that is located on the end of an elastic cantilever. In a more sophisticated version of this experiment (Chemical Force Microscopy) the tips are covalently functionalized with the molecules of interest. A piezoelectric controller then pulls up the cantilever. If some force is acting on the elastic cantilever (for example because some molecule is being stretched between the surface and the tip), this will deflect upward (repulsive force) or downward (attractive force). According to Hookes law, this deflection will be proportional to the force acting on the cantilever. Deflection is measured by the position of a laser beam reflected by the cantilever. This kind of set-up can measure forces as low as 10 pN (10 N), the fundamental resolution limit is given by the cantilevers thermal noise.
The so-called force curve is the graph of force (or more precisely, of cantilever deflection) versus the piezoelectric position on the Z axis. An ideal Hookean spring, for example, would display a straight diagonal force curve.
Typically, the force curves observed in the force spectroscopy experiments consist of a contact (diagonal) region where the probe contacts the sample surface, and a non-contact region where the probe is off the sample surface. When the restoring force of the cantilever exceeds tip-sample adhesion force the probe jumps out of contact, and the magnitude of this jump is often used as a measure of adhesion force or rupture force. In general the rupture of a tip-surface bond is a stochastic process; therefore reliable quantification of the adhesion force requires taking multiple individual force curves. The histogram of the adhesion forces obtained in these multiple measurements provides the main data output for force spectroscopy measurement.
In biophysics, single-molecule force spectroscopy can be used to study the energy landscape underlying the interaction between two bio-molecules, like proteins. Here, one binding partner can be attached to a cantilever tip via a flexible linker molecule (PEG chain), while the other one is immobilized on a substrate surface. In a typical approach, the cantilever is repeatedly approached and retracted from the sample at a constant speed. In some cases, binding between the two partners will occur, which will become visible in the force curve, as the use of a flexible linker gives rise to a characteristic curve shape (see Worm-like chain model) distinct from adhesion. The collected rupture forces can then be analysed as a function of the bond loading rate. The resulting graph of the average rupture force as a function of the loading rate is called the force spectrum and forms the basic dataset for dynamic force spectroscopy.
In the ideal case of a single sharp energy barrier for the tip-sample interactions the dynamic force spectrum will show a linear increase of the rupture force as function of a logarithm of the loading rate, as described by a model proposed by Bell et al. Here, the slope of the rupture force spectrum is equal to the , where is the distance from the energy minimum to the transition state. So far, a number of theoretical models exist describing the relationship between loading rate and rupture force, based upon different assumptions and predicting distinct curve shapes.
For example, Ma X.,Gosai A. et al., utilized dynamic force spectroscopy along with molecular dynamics simulations to find out the binding force between thrombin, a blood coagulation protein, and its DNA aptamer. | 0 | Theoretical and Fundamental Chemistry |
Geopolymerization is the process of combining many small molecules known as oligomers into a covalently bonded network. The geo-chemical syntheses are carried out through oligomers (dimer, trimer, tetramer, pentamer) which are believed to contribute to the formation of the actual structure of the three-dimensional macromolecular framework, either through direct incorporation or through rearrangement via monomeric species. These oligomers are named by some geopolymer chemists as sialates following the scheme developed by Davidovits, although this terminology is not universally accepted within the research community due in part to confusion with the earlier (1952) use of the same word to refer to the salts of the important biomolecule sialic acid.
The image shows 5 examples of small oligomeric potassium aluminosilicate species (labelled in the diagram according to the poly(sialate) / poly(sialate-siloxo) nomenclature), which are key intermediates in potassium-based alumino-silicate geopolymerization. The aqueous chemistry of aluminosilicate oligomers is complex, and also plays an important role in the discussion of zeolite synthesis, a process which has many details in common with geopolymerization.
Example of (-Si-O-Al-O-) geopolymerization with metakaolin MK-750 in alkaline medium
It involves four main phases comprising seven chemical reaction steps:
* Alkaline depolymerization of the layered structure of the calcined kaolinite;
* Formation of monomeric and oligomeric species;
* In the presence of waterglass (soluble potassium or sodium silicate), cyclic Al-Si structures can form (e.g. #5 in the figure), whereby the hydroxide is liberated by condensation reactions and can react again;
* Geopolymerization (polycondensation) into polymeric 3D-networks.
The reaction processes involving other aluminosilicate precursors, e.g. low-calcium fly ash, crushed or synthetic glasses, or natural pozzolans, are broadly similar to the steps described above. | 0 | Theoretical and Fundamental Chemistry |
The grand potential or Landau potential or Landau free energy is a quantity used in statistical mechanics, especially for irreversible processes in open systems.
The grand potential is the characteristic state function for the grand canonical ensemble. | 0 | Theoretical and Fundamental Chemistry |
Biomarkers of exposure are the actual chemicals, or chemical metabolites, that can be measured in the body or after excretion from the body to determine different characteristics of an organism’s exposure. For example, a person or fish’s blood can be tested to see the levels of lead and therefore determine the exposure. | 1 | Applied and Interdisciplinary Chemistry |
He was born in Kanazawa, Ishikawa prefecture, in 1885. In 1906 he entered the Department of Chemistry of Tokyo Imperial University, where he studied under Tamemasa Haga and Kikunae Ikeda. He continued his study in the graduate college of the university, and the Degree of Doctorate of Science was conferred for his research related to cyano-complex compounds of iron. </p>
In 1917 he entered the Institute of Physical and Chemical Research (RIKEN), where he started to work in the research of analysis of various minerals. As he appointed to study radiochemistry, he went to U.K. in 1919. He was appointed to join the laboratory of Frederick Soddy, however due to the circumstance of Soddy he studied in the laboratory with Charles Heycock for a while, who was the chemist in the Cambridge University. He joined to work in the laboratory of Frederick Soddy from October 1920 until June 1921, in which his study was focused on the radiochemistry. After returning to Japan, he led his own laboratory as the chief researcher of RIKEN. Along with working for the research of radiochemistry, the laboratory conducted the research of analytical chemistry, mineralogical chemistry, photochemistry, geochemistry especially of rare elements, luminescence of minerals and ceramics as well.
During World War II, he contributed to the for search uranium ore, as part of the project "Ni-Goh Kenkyu" (Project NIGO), as his major research was mainly focused on radiochemical minerals. After the war the research of radiochemistry was prohibited by US authority, and he started to develop the field of ceramic materials and retired from RIKEN in 1952.
While he had his specific interest in the "actinolite" he tried to create it and this creation made him start the various creation of artificial gemstones. They are based on his own idea as a mineralogist.
They were called "IL Stone", which had patented in 1955. He established "Iimori Laboratory, Ltd." to run the business for the creation and trading them. Some of those gemstones were exported mostly to the U.S. in 70's as well as traded in Japan. | 0 | Theoretical and Fundamental Chemistry |
Freweini was born in Ethiopia and educated in the United States, studying chemical engineering at Prairie View A&M University. In 2005, she patented a reusable menstrual pad that can be used for up to 2 years with proper care. As of 2019, she employs hundreds of locals in Tigray region of Ethiopia, and makes more than 700,000 of the reusable pads that are mainly provided to non-governmental organizations. | 1 | Applied and Interdisciplinary Chemistry |
Smolková-Keulemansová was born on 27 April 1927, in Prague, the Czech Republic (then Czechoslovakia) to a Jewish family. She had a normal childhood in Czechoslovakia as an only child to her parents Alice and Oskar. She finished primary school and had started grammar school but was taken out of school by her father after anti-Jewish laws started applying to grammar schools. She was employed at various Jewish workshops after leaving school. | 0 | Theoretical and Fundamental Chemistry |
Anthocyanins are approved for use as food colorants in the European Union, Australia, and New Zealand, having colorant code E163. In 2013, a panel of scientific experts for the European Food Safety Authority concluded that anthocyanins from various fruits and vegetables have been insufficiently characterized by safety and toxicology studies to approve their use as food additives. Extending from a safe history of using red grape skin extract and blackcurrant extracts to color foods produced in Europe, the panel concluded that these extract sources were exceptions to the ruling and were sufficiently shown to be safe.
Anthocyanin extracts are not specifically listed among approved color additives for foods in the United States; however, grape juice, red grape skin and many fruit and vegetable juices, which are approved for use as colorants, are rich in naturally occurring anthocyanins. No anthocyanin sources are included among approved colorants for drugs or cosmetics. When esterified with fatty acids, anthocyanins can be used as a lipophilic colorant for foods. | 0 | Theoretical and Fundamental Chemistry |
The theory is based on the principle that the statistical properties are invariant for rotations about a particular direction (say), and reflections in planes containing and perpendicular to . This type of axisymmetry is sometimes referred to as strong axisymmetry or axisymmetry in the strong sense, opposed to weak axisymmetry, where reflections in planes perpendicular to or planes containing are not allowed.
Let the two-point correlation for homogeneous turbulence be
A single scalar describes this correlation tensor in isotropic turbulence, whereas, it turns out for axisymmetric turbulence, two scalar functions are enough to uniquely specify the correlation tensor. In fact, Batchelor was unable to express the correlation tensor in terms of two scalar functions, but ended up with four scalar functions, nevertheless, Chandrasekhar showed that it could be expressed with only two scalar functions by expressing the solenoidal axisymmetric tensor as the curl of a general axisymmetric skew tensor (reflectionally non-invariant tensor).
Let be the unit vector which defines the axis of symmetry of the flow, then we have two scalar variables, and . Since , it is clear that represents the cosine of the angle between and . Let and be the two scalar functions that describes the correlation function, then the most general axisymmetric tensor which is solenoidal (incompressible) is given by,
where
The differential operators appearing in the above expressions are defined as
Then the evolution equations (equivalent form of Kármán–Howarth equation) for the two scalar functions are given by
where is the kinematic viscosity and
The scalar functions and are related to triply correlated tensor , exactly the same way and are related to the two point correlated tensor . The triply correlated tensor is
Here is the density of the fluid. | 1 | Applied and Interdisciplinary Chemistry |
A chemolithotroph is able to use inorganic reduced compounds in its energy-producing reactions. This process involves the oxidation of inorganic compounds coupled to ATP synthesis. The majority of chemolithotrophs are chemolithoautotrophs, able to fix carbon dioxide (CO) through the Calvin cycle, a metabolic pathway in which CO is converted to glucose. This group of organisms includes sulfur oxidizers, nitrifying bacteria, iron oxidizers, and hydrogen oxidizers.
The term "chemolithotrophy" refers to a cell's acquisition of energy from the oxidation of inorganic compounds, also known as electron donors. This form of metabolism is believed to occur only in prokaryotes and was first characterized by Ukrainian microbiologist Sergei Winogradsky. | 1 | Applied and Interdisciplinary Chemistry |
The parent nuclide of Tc, Mo, is mainly extracted for medical purposes from the fission products created in neutron-irradiated uranium-235 targets, the majority of which is produced in five nuclear research reactors around the world using highly enriched uranium (HEU) targets. Smaller amounts of Mo are produced from low-enriched uranium in at least three reactors. | 0 | Theoretical and Fundamental Chemistry |
Alex Berman (February 7, 1914 - June 29, 2000) was professor emeritus of history and of historical studies in pharmacy at the University of Cincinnati. He was a specialist in the history of French pharmacy. His papers are kept at the Lloyd Library and Museum. He was the recipient of the Kremers Award for excellence in the history of pharmacy.
Berman received a pharmacy degree from Fordham University in the 1930s. He served as a pharmacist with the United States Army Air Forces during World War II. He then studied the history of pharmacy at the University of Wisconsin where he earned his Ph.D. in 1954. | 1 | Applied and Interdisciplinary Chemistry |
Examples of alkaliphiles include Halorhodospira halochloris, Natronomonas pharaonis, and Thiohalospira alkaliphila. | 1 | Applied and Interdisciplinary Chemistry |
The test was used in forensics for many years to test for the traces of nitroglycerine. Caustic soda is used to break down sample containing nitroglycerine to produce nitrite ions.
The test involves the taking of a sample with ether and its division into two bowls. Caustic soda is added to the first bowl followed by the Griess reagent; if the solution turns pink within ten seconds, this indicates the presence of nitrites. The test itself is positive if, after adding only Griess reagent to the second bowl, the solution there remains clear.
The convictions of Judith Ward and the Birmingham Six were assisted by Frank Skuse's flawed interpretation of Griess test results. | 0 | Theoretical and Fundamental Chemistry |
Although the movement of the mass center of the monomer is restricted by the crystal during the polymerization, the slight change of the bond length before and after the reaction give rise to the shifting of lattice parameters. Consider a real-life topochemical polymerization initiated by irradiation: if monomer beneath the surface polymerizes later due to the light absorption near the surface, the already polymerized layer will shrink or expand, causing unbalanced stress within the crystal. The crystal might break or even lose crystallinity if the stress isn't handled properly.
Using elastic interaction such as weak hydrogen bonds is a common strategy to release the stress. It has been found that the bond length of the hydrogen bond in the crystal would change after polymerization, acting as cushion. Another possible routine is to introduce "soft" parts (C-C or C-O bond free to rotate instead of rigid conjugated system) in the monomer molecule. But it will in turn increase the difficulty of crystallization. | 0 | Theoretical and Fundamental Chemistry |
Naphthalene, an organic compound commonly found in pesticides such as mothballs, sublimes easily because it is made of non-polar molecules that are held together only by van der Waals intermolecular forces. Naphthalene is a solid that sublimes gradually at standard temperature and pressure, at a high rate, with the critical sublimation point at around 80°C or 176°F. At low temperature, its vapour pressure is high enough, 1mmHg at 53°C, to make the solid form of naphthalene evaporate into gas. On cool surfaces, the naphthalene vapours will solidify to form needle-like crystals. | 0 | Theoretical and Fundamental Chemistry |
A knowledge of environmental soil chemistry is paramount to predicting the fate of contaminants, as well as the processes by which they are initially released into the soil. Once a chemical is exposed to the soil environment, myriad chemical reactions can occur that may increase or decrease contaminant toxicity. These reactions include adsorption/desorption, precipitation, polymerization, dissolution, hydrolysis, hydration, complexation and oxidation/reduction. These reactions are often disregarded by scientists and engineers involved with environmental remediation. Understanding these processes enable us to better predict the fate and toxicity of contaminants and provide the knowledge to develop scientifically correct, and cost-effective remediation strategies. | 0 | Theoretical and Fundamental Chemistry |
CoQ taken as a pharmacological substance has potential to inhibit the effects of theophylline as well as the anticoagulant warfarin; CoQ may interfere with warfarins actions by interacting with cytochrome p450 enzymes thereby reducing the INR, a measure of blood clotting. The structure of CoQ is similar to that of vitamin K, which competes with and counteracts warfarins anticoagulation effects. CoQ is not recommended in people taking warfarin due to the increased risk of clotting. | 1 | Applied and Interdisciplinary Chemistry |
The structure of trityl persulfide has been determined by X-ray crystallography. The S-S bond length is 204 picometers and the C-S-S-H dihedral angle is 82°. These parameters are unexceptional. (CH)CSSH behaves as a source of sulfur, illustrated by its reaction with triphenylphosphine to give triphenylphosphine sulfide and triphenylmethanethiol:
:(CH)CSSH + P(CH) → (CH)CSH + SP(CH) | 0 | Theoretical and Fundamental Chemistry |
When an excess of Ba is added to a non-ionic surfactant of the alkyl propylene oxide derivative type, a pseudo-cationic complex is formed. This may be titrated with standard sodium tetraphenylborate. Two moles tetraphenylborate react with one mole of the Ba/ non-ionic surfactant complex. | 0 | Theoretical and Fundamental Chemistry |
The persistent radical effect (PRE) in chemistry describes and explains the selective product formation found in certain free-radical cross-reactions. In these type of reactions, different radicals compete in secondary reactions. The so-called persistent (long-lived) radicals do not self-terminate and only react in cross-couplings. In this way, the cross-coupling products in the product distribution are more prominent.
The effect was first described in 1936 by Bachmann & Wiselogle. They heated pentaphenylethane and observed that the main reaction product was the starting product (87%) with only 2% of tetraphenylethane formed. They concluded that the dissociation of pentaphenylethane into triphenylmethyl and diphenylmethyl radicals was reversible and that persistent triphenylmethyl did not self terminate and transient diphenylmethyl did to a certain extent. In 1964, Perkins performed a similar reaction with phenylazotriphenylmethane in benzene. Again, the dimerization product of the persistent radical (phenylcyclohexydienyl) was absent as reaction product. In 1981, Geiger and Huber found that the photolysis of dimethylnitrosamine into dimethylaminyl radical and nitrous oxide was also completely reversible. A similar effect was observed by Kräutler in 1984 for methylcobalamin. The term persistent radical effect was coined in 1992 by Daikh and Finke in their work related to the thermolysis of a cyanocobalamin model compound.
The PRE is a kinetic feature which provides a self-regulating effect in certain controlled/living radical polymerization systems such as atom transfer radical polymerization and nitroxide mediated polymerization. Propagating radicals P* are rapidly trapped in the deactivation process (with a rate constant of deactivation, k) by species X, which is typically a stable radical such as a nitroxide. The dormant species are activated (with a rate constant k) either spontaneously/thermally, in the presence of light, or with an appropriate catalyst (as in ATRP) to reform the growing centers. Radicals can propagate (k) but also terminate (k). However, persistent radicals (X), as stated above, cannot terminate with each other but only (reversibly) cross-couple with the growing species (k). Thus, every act of radical–radical termination is accompanied by the irreversible accumulation of X. Consequently, the concentration of radicals as well as the probability of termination decreases with time. The growing radicals (established through the activation–deactivation process) then predominantly react with X rather than with themselves. | 0 | Theoretical and Fundamental Chemistry |
Some modern plugholes dispense with the need for a separate plug, having instead a built-in pop-up plug operated by a handle on the sink, that can move up or down to open or close the plughole. | 1 | Applied and Interdisciplinary Chemistry |
Glucosylceramides (GluCer) are the most widely distributed glycosphingolipids in cells serving as precursors for the formation of over 200 known glycosphingolipids. GluCer is formed by the glycosylation of ceramide in an organelle called Golgi via enzymes called glucosylceramide synthase (GCS) or by the breakdown of complex glycosphingolipids (GSLs) through the action of specific hydrolase enzymes. In turn, certain β-glucosidases hydrolyze these lipids to regenerate ceramide. GluCer appears to be synthesized in the inner leaflet of the Golgi. Studies show that GluCer has to flip to the inside of the Golgi or transfer to the site of GSL synthesis to initiate the synthesis of complex GSLs. Transferring to the GSL synthesis site is done with the help of a transport protein known as four phosphate adaptor protein 2 (FAPP2) while the flipping to the inside of the Golgi is made possible by the ABC transporter P-glycoprotein, also known as the multi-drug resistance 1 transporter (MDR1). GluCer is implicated in post-Golgi trafficking and drug resistance particularly to chemotherapeutic agents. For instance, a study demonstrated a correlation between cellular drug resistance and modifications in GluCer metabolism.
In addition to their role as building blocks of biological membranes, glycosphingolipids have long attracted attention because of their supposed involvement in cell growth, differentiation, and formation of tumors. The production of GluCer from Cer was found to be important in the growth of neurons or brain cells. On the other hand, pharmacological inhibition of GluCer synthase is being considered a technique to avoid insulin resistance. | 1 | Applied and Interdisciplinary Chemistry |
The oldest inscription on the pillar is that of a king named Chandra (IAST: ), generally identified as the Gupta emperor Chandragupta II. | 1 | Applied and Interdisciplinary Chemistry |
Robinose is a disaccharide composed of 6″-O-α-rhamnopyranosyl-β-galactopyranoside. The sugar can be found in Acalypha hispida.
Robinin is a kaempferol-3-O-robinoside-7-O-rhamnoside. | 1 | Applied and Interdisciplinary Chemistry |
In organic chemistry, an isodiazene, also known by the incorrectly constructed (but commonly used) name 1,1-diazene or systematic name diazanylidene, is an organic derivative of the parent isodiazene (HN=N, also called 1,1-diimide) with general formula RRN=N. The functional group has two major resonance forms, a diazen-2-ium-1-ide form, and an aminonitrene form:
Although isodiazenes are formally isoelectronic with ketones and aldehydes, the reactivity of this exotic functional group is very different. They are generally prepared by oxidation of the hydrazine (RN–NH), reduction of the 1,1-diazene oxide (RN–N=O), 1,1-elimination of MX from RN–NMX (M = Na, K; X = SOAr), or treatment of secondary amines with Angelis salt, NaNO, in the presence of acid. Isodiazenes participate in cycloaddition reactions with alkenes to generate N'-aminoaziridines. In the absence of other reactants, they undergo reactions in which N is eliminated to give an organic residue or residues through both concerted and nonconcerted pathways. Cyclic isodizenes in particular readily undergo cycloelimination and chelotropic elimination reactions. Some of these reactions are believed to be concerted pericyclic processes, as evidenced by stereospecificity that is consistent with the conservation of orbital symmetry.
The absence of cyclobutane from the decomposition of the isodiazene derived from the saturated 5-membered azacycle is evidence against radical intermediates, and the process is also believed to be concerted and pericyclic.
Due to the facile elimination of N, most isodiazenes can only be isolated in a matrix at cryogenic temperatures. A small number of highly hindered derivatives with tertiary R groups (e.g., R= R = t-Bu, stable at –127 °C, decomposes at –90 °C; R—R = C(CH)CHCHCH(CH)C, stable up to –78 °C) are isolable by preparation and chromatography or filtration at low temperature as red solutions.
Isodiazenes have been observed to serve as ligands in transition metals complexes, including those of molybdenum and vanadium. | 0 | Theoretical and Fundamental Chemistry |
The Water Environment Federation (WEF) is a not-for-profit technical and educational organization of more than 34,000 individual members and 75 Member Associations (MAs) representing water quality professionals around the world. WEF, which was formerly known as the Federation of Sewage Works Associations and later as the Water Pollution Control Federation, and originated in 1928. WEF members include experts and specialists in the fields of:
:*environmental engineering
:*industrial wastewater treatment
:*sewage treatment and sewage sludge treatment
:*stormwater management
:*water quality analysis and planning
and related disciplines.
WEF is headquartered in Alexandria, Virginia, United States. | 1 | Applied and Interdisciplinary Chemistry |
Electrolyte: The electrolyte is a molten bath of cryolite (NaAlF) and dissolved alumina. Cryolite is a good solvent for alumina with low melting point, satisfactory viscosity, and low vapour pressure. Its density is also lower than that of liquid aluminium (2 vs 2.3 g/cm), which allows natural separation of the product from the salt at the bottom of the cell. The cryolite ratio (NaF/AlF) in pure cryolite is 3, with a melting temperature of 1010 °C, and it forms a eutectic with 11% alumina at 960 °C. In industrial cells the cryolite ratio is kept between 2 and 3 to decrease its melting temperature to 940–980 °C.
Cathode: Carbon cathodes are essentially made of anthracite, graphite and petroleum coke, which are calcined at around 1200 °C and crushed and sieved prior to being used in cathode manufacturing. Aggregates are mixed with coal-tar pitch, formed, and baked. Carbon purity is not as stringent as for anode, because metal contamination from cathode is not significant. Carbon cathode must have adequate strength, good electrical conductivity and high resistance to wear and sodium penetration. Anthracite cathodes have higher wear resistance and slower creep with lower amplitude [15] than graphitic and graphitized petroleum coke cathodes. Instead, dense cathodes with more graphitic order have higher electrical conductivity, lower energy consumption [14], and lower swelling due to sodium penetration. Swelling results in early and non-uniform deterioration of cathode blocks.
Anode: Carbon anodes have a specific situation in aluminium smelting and depending on the type of anode, aluminium smelting is divided in two different technologies; “Soderberg” and “prebaked” anodes. Anodes are also made of petroleum coke, mixed with coal-tar-pitch, followed by forming and baking at elevated temperatures. The quality of anode affects technological, economical and environmental aspects of aluminium production. Energy efficiency is related to the nature of anode materials, as well as the porosity of baked anodes. Around 10% of cell power is consumed to overcome the electrical resistance of prebaked anode (50–60 μΩm). Carbon is consumed more than theoretical value due to a low current efficiency and non-electrolytic consumption. Inhomogeneous anode quality due to the variation in raw materials and production parameters also affects its performance and the cell stability.
Prebaked consumable carbon anodes are divided into graphitized and coke types. For manufacturing of the graphitized anodes, anthracite and petroleum coke are calcined and classified. They are then mixed with coal-tar pitch and pressed. The pressed green anode is then baked at 1200 °C and graphitized. Coke anodes are made of calcined petroleum coke, recycled anode butts, and coal-tar pitch (binder). The anodes are manufactured by mixing aggregates with coal tar pitch to form a paste with a doughy consistency. This material is most often vibro-compacted but in some plants pressed. The green anode is then sintered at 1100–1200 °C for 300–400 hours, without graphitization, to increase its strength through decomposition and carbonization of the binder. Higher baking temperatures increase the mechanical properties and thermal conductivity, and decrease the air and CO reactivity. The specific electrical resistance of the coke-type anodes is higher than that of the graphitized ones, but they have higher compressive strength and lower porosity.
Soderberg electrodes (in-situ baking), used for the first time in 1923 in Norway, are composed of a steel shell and a carbonaceous mass which is baked by the heat being escaped from the electrolysis cell. Soderberg Carbon-based materials such as coke and anthracite are crushed, heat-treated, and classified. These aggregates are mixed with pitch or oil as binder, briquetted and loaded into the shell. Temperature increases bottom to the top of the column and in-situ baking takes place as the anode is lowered into the bath. Significant amount of hydrocarbons are emitted during baking which is a disadvantage of this type of electrodes. Most of the modern smelters use prebaked anodes since the process control is easier and a slightly better energy efficiency is achieved, compared to Soderberg anodes. | 1 | Applied and Interdisciplinary Chemistry |
Microwave digestion is a common technique used by elemental scientists to dissolve heavy metals in the presence of organic molecules prior to analysis by inductively coupled plasma, atomic absorption, or atomic emission measurements.
This technique is usually accomplished by exposing a sample to a strong acid in a closed vessel and raising the pressure and temperature through microwave irradiation. This increase in temperature and pressure of the low pH sample medium increases both the speed of thermal decomposition of the sample and the solubility of heavy metals in solution. Once these heavy metals are in solution, it is possible to quantify the sample through elemental techniques. A program can be configured in the microwave, establishing a series of temperature ramps. The temperature in the interior of the vessel is monitored by an infrared external sensor or by a optic fiber probe, and the microwave power is regulated to maintain the temperature defined by the active program. The vessel solution must contain at least one solvent that absorbs microwave radiation, usually water.
Before the microwave digestion technology was developed, digestion of samples was made by heating vessels in a stove, typically for at least 24 hours. The use of microwave energy allows a much faster sample heating, so digestions time can be reduced to 1 hour. | 0 | Theoretical and Fundamental Chemistry |
[https://iifiir.org/en/fridoc FRIDOC] is the most comprehensive database in the world dedicated to refrigeration. It contains over 110,000 references to documents in all domains of refrigeration.
A large number of the documents referenced in FRIDOC are scientific and technical. FRIDOC also contains many review articles, documents on economic data and statistics, articles dealing with regulations and standardization, etc. | 0 | Theoretical and Fundamental Chemistry |
Microarrays use hybridization probes to test the prevalence of known DNA sequences, thus they cannot be used to identify unexpected genetic changes. In contrast, the high-throughput sequencing technologies used in exome sequencing directly provide the nucleotide sequences of DNA at the thousands of exonic loci tested. Hence, WES addresses some of the present limitations of hybridization genotyping arrays.
Although exome sequencing is more expensive than hybridization-based technologies on a per-sample basis, its cost has been decreasing due to the falling cost and increased throughput of whole genome sequencing. | 1 | Applied and Interdisciplinary Chemistry |
The inscription covers an area of 2′9.5″× 10.5″(65.09 cm x 26.67 cm). The ancient writing is preserved well because of the corrosion-resistant iron on which it is engraved. However, during the engraving process, iron appears to have closed up over some of the strokes, making some of the letters imperfect.
It contains verses composed in Sanskrit language, in shardulvikridita metre. It is written in the eastern variety of the Gupta script. The letters vary from 0.3125″ to 0.5″ in size, and resemble closely to the letters on the Allahabad Pillar inscription of Samudragupta. However, it had distinctive s (diacritics), similar to the ones in the Bilsad inscription of Kumaragupta I. While the edges of the characters on the Allahabad inscription are more curved, the ones on the Delhi inscription have more straight edges. This can be attributed to the fact that the Allahabad inscription was inscribed on softer sandstone, while the Delhi inscription is engraved on the harder material (iron).
The text has some unusual deviations from the standard Sanskrit spelling, such as:
* instead of : the use of dental nasal instead of anusvāra
* instead of : omission of the second t
* instead of : omission of the second t
* instead of śatru (enemy): an extra t | 1 | Applied and Interdisciplinary Chemistry |
The CMC generally depends on the method of measuring the samples, since A and B depend on the properties of the solution such as conductance, photochemical characteristics, or surface tension. When the degree of aggregation is monodisperse, then the CMC is not related to the method of measurement. On the other hand, when the degree of aggregation is polydisperse, then CMC is related to both the method of measurement and the dispersion.
The common procedure to determine the CMC from experimental data is to look for the intersection (inflection point) of two straight lines traced through plots of the measured property versus the surfactant concentration. This visual data analysis method is highly subjective and can lead to very different CMC values depending on the type of representation, the quality of the data and the chosen interval around the CMC. A preferred method is the fit of the experimental data with a model of the measured property. Fit functions for properties such as electrical conductivity, surface tension, NMR chemical shifts, absorption, self-diffusion coefficients, fluorescence intensity and mean translational diffusion coefficient of fluorescent dyes in surfactant solutions have been presented. These fit functions are based on a model for the concentrations of monomeric and micellised surfactants in solution, which establishes a well-defined analytical definition of the CMC, independent from the technique.
The CMC is the concentration of surfactants in the bulk at which micelles start forming. The word bulk is important because surfactants partition between the bulk and interface and CMC is independent of interface and is therefore a characteristic of the surfactant molecule. In most situations, such as surface tension measurements or conductivity measurements, the amount of surfactant at the interface is negligible compared to that in the bulk and CMC can be approximated by the total concentration. In practice, CMC data is usually collected using laboratory instruments which allow the process to be partially automated, for instance by using specialised tensiometers. | 0 | Theoretical and Fundamental Chemistry |
The NDUFAF6 gene is located on the q arm of chromosome 8 in position 22.1 and spans 222,728 base pairs. The gene produces a 38.2 kDa protein composed of 333 amino acids. The protein contains a predicted phytoene synthase domain. | 1 | Applied and Interdisciplinary Chemistry |
* Chapter (Molecular Spectroscopy), Section (Vibration-rotation spectra) and page numbers may be different in different editions. | 0 | Theoretical and Fundamental Chemistry |
In the 1950s, three groups made it their goal to determine the structure of DNA. The first group to start was at Kings College London and was led by Maurice Wilkins and was later joined by Rosalind Franklin. Another group consisting of Francis Crick and James Watson was at Cambridge. A third group was at Caltech and was led by Linus Pauling. Crick and Watson built physical models using metal rods and balls, in which they incorporated the known chemical structures of the nucleotides, as well as the known position of the linkages joining one nucleotide to the next along the polymer. At Kings College Maurice Wilkins and Rosalind Franklin examined X-ray diffraction patterns of DNA fibers. Of the three groups, only the London group was able to produce good quality diffraction patterns and thus produce sufficient quantitative data about the structure. | 1 | Applied and Interdisciplinary Chemistry |
Acid–base imbalance occurs when a significant insult causes the blood pH to shift out of the normal range (7.32 to 7.42). An abnormally low pH in the extracellular fluid is called an acidemia and an abnormally high pH is called an alkalemia.
Acidemia and alkalemia unambiguously refer to the actual change in the pH of the extracellular fluid (ECF). Two other similar sounding terms are acidosis and alkalosis. They refer to the customary effect of a component, respiratory or metabolic. Acidosis would cause an acidemia on its own (i.e. if left "uncompensated" by an alkalosis). Similarly, an alkalosis would cause an alkalemia on its own. In medical terminology, the terms acidosis and alkalosis should always be qualified by an adjective to indicate the etiology of the disturbance: respiratory (indicating a change in the partial pressure of carbon dioxide), or metabolic (indicating a change in the Base Excess of the ECF). There are therefore four different acid-base problems: metabolic acidosis, respiratory acidosis, metabolic alkalosis, and respiratory alkalosis. One or a combination of these conditions may occur simultaneously. For instance, a metabolic acidosis (as in uncontrolled diabetes mellitus) is almost always partially compensated by a respiratory alkalosis (hyperventilation). Similarly, a respiratory acidosis can be completely or partially corrected by a metabolic alkalosis. | 0 | Theoretical and Fundamental Chemistry |
About 20 million kg per year are produced industrially as both a by-product of and precursor to the manufacture of Teflon. It is produced by reaction of chloroform with HF:
It is also generated biologically in small amounts apparently by decarboxylation of trifluoroacetic acid. | 1 | Applied and Interdisciplinary Chemistry |
OFM was developed and is manufactured by Aroa Biosurgery Limited (New Zealand, formerly Mesynthes Limited, New Zealand) and was first patented in 2008 and described in the scientific literature in 2010. OFM is manufactured from sheep rumen tissue, using a process of decellularization to selectively remove the unwanted sheep cells and cell components to leave an intact and functional extracellular matrix. OFM comprises a special layer of tissue found in rumen, the propria submucosa, which is structurally and functionally distinct from the submucosa of other gastrointestinal tissues.
OFM was first cleared by the FDA in 2009 for the treatment of wounds. Since 2008 there have been >70 publications describing OFM and its clinical applications, and over 6 million clinical applications of OFM-based devices. | 1 | Applied and Interdisciplinary Chemistry |
The use of cross-linked enzyme crystals (CLECs) as industrial biocatalysts was pioneered by Altus Biologics in the 1990s. CLECs proved to be significantly more stable to denaturation by heat, organic solvents and proteolysis than the corresponding soluble enzyme or lyophilized (freeze-dried) powder. CLECs are robust, highly active immobilized enzymes of controllable particle size, varying from 1 to 100 micrometer. Their operational stability and ease of recycling, coupled with their high catalyst and volumetric productivities, renders them ideally suited for industrial biotransformations.
However, CLECs have an inherent disadvantage: enzyme crystallization is a laborious procedure requiring enzyme of high purity, which translates to prohibitively high costs. The more recently developed cross-linked enzyme aggregates (CLEAs), on the other hand, are produced by simple precipitation of the enzyme from aqueous solution, as physical aggregates of protein molecules, by the addition of salts, or water miscible organic solvents or non-ionic polymers. The physical aggregates are held together by covalent bonding without perturbation of their tertiary structure, that is without denaturation. Subsequent cross-linking of these physical aggregates renders them permanently insoluble while maintaining their pre-organized superstructure, and, hence their catalytic activity. This discovery led to the development of a new family of immobilized enzymes: cross-linked enzyme aggregates (CLEAs). Since precipitation from an aqueous medium, by addition of ammonium sulfate or polyethylene glycol, is often used to purify enzymes, the CLEA methodology essentially combines purification and immobilization into a single unit operation that does not require a highly pure enzyme. It could be used, for example, for the direct isolation of an enzyme, in a purified and immobilized form suitable for performing biotransformations, from a crude fermentation broth.
CLEAs are very attractive biocatalysts, owing to their facile, inexpensive and effective production method. They can readily be reused and exhibit improved stability and performance. The methodology is applicable to essentially any enzyme, including cofactor dependent oxidoreductases. Application to penicillin acylase used in antibiotic synthesis showed large improvements over other type of biocatalysts.
The potential applications of CLEAs are numerous and include:
# Synthesis of pharmaceuticals, flavors and fragrances, agrochemicals, nutraceuticals, fine chemicals, bulk monomers and biofuels.
# Animal feed, e.g. phytase for utilization of organically bound phosphate by pigs and poultry.
# Food and beverage processing, e.g. lipases in cheese manufacture and laccase in wine clarification.
# Cosmetics, e.g. in skin care products
# Oils and fats processing, e.g. in biolubricants, bioemulsifiers, bio-derived emollients.
# Carbohydrate processing, e.g. laccase in carbohydrate oxidations.
# Pulp and paper, e.g. in pulp bleaching.
# Detergents, e.g. proteases, amylases and lipases for removal of protein, carbohydrate and fat stains.
# Waste water treatment, e.g. for removal of phenols, dyes, and endocrine disrupters.
# Biosensors/diagnostics, e.g. glucose oxidase and cholesterol oxidase biosensors.
# Delivery of proteins as therapeutic agents or nutritional/digestive supplements e.g. beta-galactosidase for digestive hydrolysis of lactose in dairy products to alleviate the symptoms of lactose intolerance. | 0 | Theoretical and Fundamental Chemistry |
Americium-241 has been used as a source of low energy gamma photons, it has been used in some applications such as portable X-ray fluorescence equipment (XRF) and common household ionizing smoke detectors. Americium-241 is produced from in nuclear reactors through multiple neutron captures and subsequent beta decays with the plutonium-239 itself being produced mostly from neutron capture and subsequent beta decays by (99% of natural uranium and usually roughly 97% of low enriched uranium or MOX fuel). | 0 | Theoretical and Fundamental Chemistry |
As studied in coordination chemistry, metal ions (usually transition metal ions) exist in solution bound to ligands, In many cases, the coordination sphere defines geometries conducive to reactions either between ligands or involving ligands and other external reagents.
A well known metal-ion-templating was described by Charles Pedersen in his synthesis of various crown ethers using metal cations as template. For example, 18-crown-6 strongly coordinates potassium ion thus can be prepared through the Williamson ether synthesis using potassium ion as the template metal.
Metal ions are frequently used for assembly of large supramolecular structures. Metal organic frameworks (MOFs) are one example. MOFs are infinite structures where metal serve as nodes to connect organic ligands together. SCCs are discrete systems where selected metals and ligands undergo self-assembly to form finite supramolecular complexes, usually the size and structure of the complex formed can be determined by the angularity of chosen metal-ligand bonds. | 0 | Theoretical and Fundamental Chemistry |
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