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The step → P680 is performed by an imperfectly understood structure embedded within PSII called the water-splitting complex or oxygen-evolving complex (OEC). It catalyzes a reaction that splits water into electrons, protons and oxygen,
using energy from P680. The actual steps of the above reaction possibly occur in the following way (Kok's diagram of S-states):
(I) 2 (monoxide) (II) OH. (hydroxide) (III) (peroxide) (IV) (super oxide)(V) (di-oxygen). (Dolai's mechanism)
The electrons are transferred to special chlorophyll molecules (embedded in PSII) that are promoted to a higher-energy state by the energy of photons. | 0 | Theoretical and Fundamental Chemistry |
A-values provide another measure of the bulk of substituents. A-values are derived from equilibrium measurements of monosubstituted cyclohexanes. The extent that a substituent favors the equatorial position gives a measure of its bulk. | 0 | Theoretical and Fundamental Chemistry |
Nanorobots have the potential to transform drug delivery processes and biological computing. Llopis-Lorente and co. developed a nanorobot that can perform logic operations and process information on glucose and urea. Thubagere and coworkers designed a DNA molecular nanorobot capable of sorting chemical cargo. The system could work without additional power as the robot was capable of walking across the DNA origami surface on its two feet. It also had an arm to transport cargo.
Molecular sequential logic is exemplified by Margulies et al., where they demonstrate a molecular keypad lock resembling the processing capabilities of an electronic security device which is equivalent to incorporates several interconnected AND logic gates in parallel. The molecule mimics an electronic keypad of an automated teller machine (ATM). The output signals are dependent not only on the combination of inputs but also on the correct order of inputs; i.e. the correct password must be entered. The molecule was designed using pyrene and fluorescein fluorophores connected by a siderophore, which binds to Fe(III), and the acidic of the solution changes the fluorescence properties of the fluorescein fluorophore.
Molecular logic gate systems can theoretically overcome the problems arising when semiconductors approach nano-dimensions. Molecular logic gates are more versatile than their silicon counterparts, with phenomena such as superposed logic unavailable to semiconductor electronics. Dry molecular gates, such as the one demonstrated by Avouris and colleagues, prove to be possible substitutes for semiconductor devices due to their small size, similar infrastructure, and data processing abilities. Avouris revealed a NOT logic gate composed of a bundle of carbon nanotubes. The nanotubes are doped differently in adjoining regions creating two complementary field effect transistors, and the bundle operates as a NOT logic gate only when satisfactory conditions are met. | 0 | Theoretical and Fundamental Chemistry |
The enzyme cytochrome c oxidase or Complex IV, (was , now reclassified as a translocase [https://www.enzyme-database.org/query.php?name=EC+7.1.1.9&search=search_all&display=show_all&order=ec_num&nr=50 EC 7.1.1.9]) is a large transmembrane protein complex found in bacteria, archaea, and the mitochondria of eukaryotes.
It is the last enzyme in the respiratory electron transport chain of cells located in the membrane. It receives an electron from each of four cytochrome c molecules and transfers them to one oxygen molecule and four protons, producing two molecules of water. In addition to binding the four protons from the inner aqueous phase, it transports another four protons across the membrane, increasing the transmembrane difference of proton electrochemical potential, which the ATP synthase then uses to synthesize ATP. | 1 | Applied and Interdisciplinary Chemistry |
The Eulerian approach to turbulent diffusion focuses on an infinitesimal volume at a specific space and time in a fixed frame of reference, at which physical properties such as mass, momentum, and temperature are measured. The model is useful because Eulerian statistics are consistently measurable and offer great application to chemical reactions. Similarly to molecular models, it must satisfy the same principles as the continuity equation below (where the advection of an element or species is balanced by its diffusion, generation by reaction, and addition from other sources or points) and the Navier–Stokes equations:
where = species concentration of interest, = velocity
t= time, = direction, = molecular diffusion constant, = rate of generated reaction, = rate of generated by source.
Note that is concentration per unit volume, and is not mixing ratio () in a background fluid.
If we consider an inert species (no reaction) with no sources and assume molecular diffusion to be negligible, only the advection terms on the left hand side of the equation survive. The solution to this model seems trivial at first, however we have ignored the random component of the velocity plus the average velocity in u= ū + u’ that is typically associated with turbulent behavior. In turn, the concentration solution for the Eulerian model must also have a random component c= + c’. This results in a closure problem of infinite variables and equations and makes it impossible to solve for a definite c on the assumptions stated.
Fortunately there exists a closure approximation in introducing the concept of eddy diffusivity and its statistical approximations for the random concentration and velocity components from turbulent mixing:
where K is the eddy diffusivity.
Substituting into the first continuity equation and ignoring reactions, sources, and molecular diffusion results in the following differential equation considering only the turbulent diffusion approximation in eddy diffusion:
Unlike the molecular diffusion constant D, the eddy diffusivity is a matrix expression that may vary in space, and thus may not be taken outside the outer derivative. | 1 | Applied and Interdisciplinary Chemistry |
In order to celebrate its centenary, in 2022 the Institution produced a website with short articles about historic matters in the history of chemical engineering and of the IChemE and to host videos and webinars during the year. [https://www.chemengevolution.org/ ChemEng Evolution] | 1 | Applied and Interdisciplinary Chemistry |
Polyphenols of several classes are widespread in plants, including anthocyanins, phytoestrogens, and tannins. Polyphenols are secondary metabolites produced by almost every part of plants, including fruits, flowers, leaves and bark. | 1 | Applied and Interdisciplinary Chemistry |
Once the gel has set, the comb is removed, leaving wells where DNA samples can be loaded. Loading buffer is mixed with the DNA sample before the mixture is loaded into the wells. The loading buffer contains a dense compound, which may be glycerol, sucrose, or Ficoll, that raises the density of the sample so that the DNA sample may sink to the bottom of the well. If the DNA sample contains residual ethanol after its preparation, it may float out of the well. The loading buffer also includes colored dyes such as xylene cyanol and bromophenol blue used to monitor the progress of the electrophoresis. The DNA samples are loaded using a pipette. | 1 | Applied and Interdisciplinary Chemistry |
Baubotanik is a building method in which architectural structures are created through the interaction of technical joints and plant growth. The term entails the practice of designing and building living structures using living plants. In this regard, living and non-living elements are intertwined in such a way that they grow together into plant-technical composite structures.
The Baubotanik method combines the aesthetic and ecological qualities of living trees with the static functions and structural requirements of buildings, thereby reducing the need for artificial building materials. The structures provide valuable habitats for a variety of animal species and make conventional foundations redundant, due to their root anchorage.
The use of Baubotanik is not a new invention and can be found in various historical and cultural contexts, such as the Tanzlinden (“dancing lime”) tree in Germany and living root bridge in North-East India. Common in the Indian state of Meghalaya and grown by the Khasi and Jaintia, the bridges consist of the aerial roots of rubber fig trees (Ficus elastica) and are grown over rivers to form walkable bridges. While the process can take fifteen years to complete, the bridges can be reinforced with natural materials and can withstand the strongest tropical storms. Furthermore, since the turn of the millennium, ‘willow churches’ (made of willow rods and lacking a fixed roof) have been constructed on various former garden show grounds, yet provide only limited functionality as buildings. | 1 | Applied and Interdisciplinary Chemistry |
In reversed-phase (e.g. aqueous mobile phase) elution, the aqueous phase is used as the mobile phase with a less polar stationary phase. In countercurrent chromatography the same solvent system may be used in either normal or reversed phase mode simply by switching the direction of mobile phase flow through the column. | 0 | Theoretical and Fundamental Chemistry |
Photostimulation is notable for its temporal precision, which may be used to obtain an accurate starting time of activation of caged effectors. In conjunction with caged inhibitors, the role of biomolecules at specific timepoints in an organism's lifecycle may be studied. A caged inhibitor of N-ethylmaleimide sensitive fusion protein (NSF), a key mediator of synaptic transmission, has been used to study the time dependency of NSF. Several other studies have effected action potential firing through use of caged neurotransmitters such as glutamate. Caged neurotransmitters, including photolable precursors of glutamate, dopamine, serotonin, and GABA, are commercially available.
Signaling during mitosis has been studied using reporter molecules with a caged fluorophore, which is not phosphorylated if photolysis has not occurred. The advantage of this technique is that it provides a “snapshot” of kinase activity at specific timepoints rather than recording all activity since the reporter's introduction.
Calcium ions play an important signaling role, and controlling their release with caged channels has been extensively studied.
Unfortunately, not all organisms produce or hold sufficient amounts of opsins. Thus, the opsin gene must be introduced to target neurons if they are not already present in the organism of study. The addition and expression of this gene is sufficient for the use of optogenetics. Possible means of achieving this include the construction of transgenic lines containing the gene or acute gene transfer to a specific area or region within an individual. These methods are known as germline transgenesis and somatic gene delivery, respectively.
Optogenetics has shown significant promise in the treatment of a series of neurological disorders such as Parkinson's disease and epilepsy. Optogenetics has the potential to facilitate the manipulation and targeting of specific cell types or neural circuits, characteristics that are lacking in current brain stimulation techniques like DBS. At this point, the use of optogenetics in treating neural diseases has only been practically implemented in the field of neurobiology to reveal more about the mechanisms of specific disorders. Before the technique can be implemented to directly treat these disorders developments in other related fields such as gene therapy, opsin engineering, and optoelectronics must also make certain developments. | 1 | Applied and Interdisciplinary Chemistry |
Previously a chart recorder and more recently a data logger or personal computer records the detector output as a function of time so that each sample output appears as a peak whose height depends on the analyte level in the sample. | 0 | Theoretical and Fundamental Chemistry |
In the original paper Ginzburg and Landau observed the existence of two types of superconductors depending
on the energy of the interface between the normal and superconducting states. The Meissner state breaks down when the applied magnetic field is too large. Superconductors can be divided into two classes according to how this breakdown occurs. In Type I superconductors, superconductivity is abruptly destroyed when the strength of the applied field rises above a critical value H. Depending on the geometry of the sample, one may obtain an intermediate state consisting of a baroque pattern of regions of normal material carrying a magnetic field mixed with regions of superconducting material containing no field. In Type II superconductors, raising the applied field past a critical value H leads to a mixed state (also known as the vortex state) in which an increasing amount of magnetic flux penetrates the material, but there remains no resistance to the flow of electric current as long as the current is not too large. At a second critical field strength H, superconductivity is destroyed. The mixed state is actually caused by vortices in the electronic superfluid, sometimes called fluxons because the flux carried by these vortices is quantized. Most pure elemental superconductors, except niobium and carbon nanotubes, are Type I, while almost all impure and compound superconductors are Type II.
The most important finding from Ginzburg–Landau theory was made by Alexei Abrikosov in 1957.
He used Ginzburg–Landau theory to explain experiments on superconducting alloys and thin films. He found that in a type-II superconductor in a high magnetic field, the field penetrates in a triangular lattice of quantized tubes of flux vortices. For this and related work, he was awarded the Nobel Prize in 2003 with Ginzburg and Leggett. | 0 | Theoretical and Fundamental Chemistry |
The Golden Gate assembly protocol was defined by Engler et al. 2008 to define a DNA assembly method that would give a final construct without a scar sequence, while also lacking the original restriction sites. This allows the protein to be expressed without containing unwanted protein sequences which could negatively affect protein folding or expression. By using the BsaI restriction enzyme that produces a 4 base pair overhang, up to 240 unique, non-palindromic sequences can be used for assembly.
Plasmid design and assembly
In Golden Gate cloning, each DNA fragment to be assembled is placed in a plasmid, flanked by inward facing BsaI restriction sites containing the programmed overhang sequences. For each DNA fragment, the 3 overhang sequence is complementary to the 5 overhang of the next downstream DNA fragment. For the first fragment, the 5 overhang is complementary to the 5 overhang of the destination plasmid, while the 3 overhang of the final fragment is complementary to the 3 overhang of the destination plasmid. Such a design allows for all DNA fragments to be assembled in a one-pot reaction (where all reactants are mixed together), with all fragments arranged in the correct sequence. Successfully assembled constructs are selected by detecting the loss of function of a screening cassette that was originally in the destination plasmid.
MoClo and Golden Braid
The original Golden Gate Assembly only allows for a single construct to be made in the destination vector . To enable this construct to be used in a subsequent reaction as an entry vector, the MoClo and Golden Braid standards were designed.
The MoClo standard involves defining multiple tiers of DNA assembly:
* Tier 1: Tier 1 assembly is the standard Golden Gate assembly, and genes are assembled from their components parts (DNA parts coding for genetic elements like UTRs, promoters, ribosome binding sites or terminator sequences). Flanking the insertion site of the tier 1 destination vectors are a pair of inward cutting BpiI restriction sites. This allows these plasmids to be used as entry vectors for tier two destination vectors.
* Tier 2: Tier 2 assembly involves further assembling the genes assembled in tier 1 assembly into multi-gene constructs. If there is a need for further, higher tier assembly, inward cutting BsaI restriction sites can be added to flank the insertion sites. These vectors can then be used as entry vectors for higher tier constructs.
Each assembly tier alternates the use of BsaI and BpiI restriction sites to minimise the number of forbidden sites, and sequential assembly for each tier is achieved by following the Golden Gate plasmid design. Overall, the MoClo standard allows for the assembly of a construct that contains multiple transcription units, all assembled from different DNA parts, by a series of one-pot Golden Gate reactions. However, one drawback of the MoClo standard is that it requires the use of dummy parts with no biological function, if the final construct requires less than four component parts. The Golden Braid standard on the other hand introduced a pairwise Golden Gate assembly standard.
The Golden Braid standard uses the same tiered assembly as MoClo, but each tier only involves the assembly of two DNA fragments, i.e. a pairwise approach. Hence in each tier, pairs of genes are cloned into a destination fragment in the desired sequence, and these are subsequently assembled two at a time in successive tiers. Like MoClo, the Golden Braid standard alternates the BsaI and BpiI restriction enzymes between each tier.
The development of the Golden Gate assembly methods and its variants has allowed researchers to design tool-kits to speed up the synthetic biology workflow. For example, EcoFlex was developed as a toolkit for E. Coli that uses the MoClo standard for its DNA parts, while a similar toolkit has also been developed for engineering the Chlamydomonas reinhardtii microalgae. | 1 | Applied and Interdisciplinary Chemistry |
Urea can be irritating to skin, eyes, and the respiratory tract. Repeated or prolonged contact with urea in fertilizer form on the skin may cause dermatitis.
High concentrations in the blood can be damaging. Ingestion of low concentrations of urea, such as are found in typical human urine, are not dangerous with additional water ingestion within a reasonable time-frame. Many animals (e.g. camels, rodents or dogs) have a much more concentrated urine which may contain a higher urea amount than normal human urine.
Urea can cause algal blooms to produce toxins, and its presence in the runoff from fertilized land may play a role in the increase of toxic blooms.
The substance decomposes on heating above melting point, producing toxic gases, and reacts violently with strong oxidants, nitrites, inorganic chlorides, chlorites and perchlorates, causing fire and explosion. | 0 | Theoretical and Fundamental Chemistry |
* H. J. M. Bowen, Trace Elements in Biochemistry. Academic Press, 1966.
* H. J. M. Bowen, Properties of Solids and their Structures. McGraw-Hill, 1967.
* H. J. M. Bowen, Environmental Chemistry of the Elements. Academic Press, 1979. . | 0 | Theoretical and Fundamental Chemistry |
When a chemical reactor is being brought into operation, the concentrations, temperatures, species compositions, and reaction rates are changing with time until operation reaches its nominal process variables. | 1 | Applied and Interdisciplinary Chemistry |
Some of the applications of multiplex PCR include:
# Pathogen Identification
# High Throughput SNP Genotyping
# Mutation Analysis
# Gene Deletion Analysis
# Template Quantitation
# Linkage Analysis
# RNA Detection
# Forensic Studies
# Diet Analysis | 1 | Applied and Interdisciplinary Chemistry |
ADP/ATP translocase transports ATP synthesized from oxidative phosphorylation into the cytoplasm, where it can be used as the principal energy currency of the cell to power thermodynamically unfavorable reactions. After the consequent hydrolysis of ATP into ADP, ADP is transported back into the mitochondrial matrix, where it can be rephosphorylated to ATP. Because a human typically exchanges the equivalent of his/her own mass of ATP on a daily basis, ADP/ATP translocase is an important transporter protein with major metabolic implications.
ANT transports the free, i.e. deprotonated, non-Magnesium, non-Calcium bound forms of ADP and ATP, in a 1:1 ratio. Transport is fully reversible, and its directionality is governed by the concentrations of its substrates (ADP and ATP inside and outside mitochondria), the chelators of the adenine nucleotides, and the mitochondrial membrane potential. The relationship of these parameters can be expressed by an equation solving for the 'reversal potential of the ANT" (Erev_ANT), a value of the mitochondrial membrane potential at which no net transport of adenine nucleotides takes place by the ANT. The ANT and the F0-F1 ATP synthase are not necessarily in directional synchrony.
Apart from exchange of ADP and ATP across the inner mitochondrial membrane, the ANT also exhibits an intrinsic uncoupling activity
ANT is an important modulatory and possible structural component of the Mitochondrial Permeability Transition Pore, a channel involved in various pathologies whose function still remains elusive. Karch et al. propose a "multi-pore model" in which ANT is at least one of the molecular components of the pore. | 1 | Applied and Interdisciplinary Chemistry |
Primer pheromones trigger a change of developmental events (in which they differ from all the other pheromones, which trigger a change in behavior). They were first described in Schistocerca gregaria by Maud Norris in 1954. | 1 | Applied and Interdisciplinary Chemistry |
In free radical polymerization, branching occurs when a chain curls back and bonds to an earlier part of the chain. When this curl breaks, it leaves small chains sprouting from the main carbon backbone. Branched carbon chains cannot line up as close to each other as unbranched chains can. This causes less contact between atoms of different chains, and fewer opportunities for induced or permanent dipoles to occur. A low density results from the chains being further apart. Lower melting points and tensile strengths are evident, because the intermolecular bonds are weaker and require less energy to break.
The problem of branching occurs during propagation, when a chain curls back on itself and breaks - leaving irregular chains sprouting from the main carbon backbone. Branching makes the polymers less dense and results in low tensile strength and melting points. Developed by Karl Ziegler and Giulio Natta in the 1950s, Ziegler–Natta catalysts (triethylaluminium in the presence of a metal(IV) chloride) largely solved this problem. Instead of a free radical reaction, the initial ethene monomer inserts between the aluminium atom and one of the ethyl groups in the catalyst. The polymer is then able to grow out from the aluminium atom and results in almost totally unbranched chains. With the new catalysts, the tacticity of the polypropene chain, the alignment of alkyl groups, was also able to be controlled. Different metal chlorides allowed the selective production of each form i.e., syndiotactic, isotactic and atactic polymer chains could be selectively created.
However, there were further complications to be solved. If the Ziegler–Natta catalyst was poisoned or damaged then the chain stopped growing. Also, Ziegler–Natta monomers have to be small, and it was still impossible to control the molecular mass of the polymer chains. Again new catalysts, the metallocenes, were developed to tackle these problems. Due to their structure they have less premature chain termination and branching. | 0 | Theoretical and Fundamental Chemistry |
A trickling filter is a type of wastewater treatment system. It consists of a fixed bed of rocks, coke, gravel, slag, polyurethane foam, sphagnum peat moss, ceramic, or plastic media over which sewage or other wastewater flows downward and causes a layer of microbial slime (biofilm) to grow, covering the bed of media. Aerobic conditions are maintained by splashing, diffusion, and either by forced-air flowing through the bed or natural convection of air if the filter medium is porous. The treatment of sewage or other wastewater with trickling filters is among the oldest and most well characterized treatment technologies.
The fundamental components of a complete trickling filter system are:
* a bed of filter medium upon which a layer of microbial slime is promoted and developed;
* an enclosure or a container which houses the bed of filter medium;
* a system for distributing the flow of wastewater over the filter medium; and
* a system for removing and disposing of any sludge from the treated effluent.
The terms trickle filter, trickling biofilter, biofilter, biological filter and biological trickling filter are often used to refer to a trickling filter. These systems have also been described as roughing filters, intermittent filters, packed media bed filters, alternative septic systems, percolating filters, attached growth processes, and fixed film processes. | 1 | Applied and Interdisciplinary Chemistry |
Nines are used in a similar manner to describe computer system availability. In this context, a "one nine" (90%) uptime indicates a system that is available 90% of the time or, as is more commonly described, unavailable 10% of the time – about 72 hours per month. A "five nines" (99.999%) uptime describes a system that is unavailable for at most 26 seconds per month. | 1 | Applied and Interdisciplinary Chemistry |
The sclerometer, also known as the Turner-sclerometer (from meaning "hard"), is an instrument used by metallurgists, material scientists and mineralogists to measure the scratch hardness of materials. It was invented in 1896 by Thomas Turner (1861–1951), the first Professor of metallurgy in Britain, at the University of Birmingham.
The Turner-Sclerometer test consists of measuring the amount of load required to make a scratch.
In test a weighted diamond point is drawn, once forward and once backward, over the smooth surface of the material to be tested. The hardness number is the weight in grams required to produce a standard scratch. The scratch selected is one which is just visible to the naked eye as a dark line on a bright reflecting surface. It is also the scratch which can just be felt with the edge of a quill when the latter is drawn over the smooth surface at right angles to a series of such scratches produced by regularly increasing weights. | 1 | Applied and Interdisciplinary Chemistry |
* 999.99—five nines fine: The purest silver ever produced. This was achieved by the Royal Silver Company of Bolivia.
* 999.9—four nines fine: ultra-fine silver used by the Royal Canadian Mint for their Silver Maple Leaf and other silver coins
* 999—fine silver or three nines fine: used in Good Delivery bullion bars and most current silver bullion coins. Used in U.S. silver commemorative coins and silver proof coins starting in 2019.
* 980: common standard used in Mexico ca. 1930–1945
* 958: () Britannia silver
* 950: French 1st Standard
* 947.9: 91 zolotnik Russian silver
* 935: Swiss standard for watchcases after 1887, to meet the British Merchandise Marks Act and to be of equal grade to 925 sterling. Sometimes claimed to have arisen as a Swiss misunderstanding of the standard required for British sterling. Usually marked with three Swiss bears.
* 935: used in the Art Deco period in Austria and Germany. Scandinavian silver jewellers used 935 silver after the 2nd World War
* 925: () Sterling silver The UK has used this alloy from the early 12th century. Equivalent to plata de primera ley in Spain (first law silver)
* 917: a standard used for the minting of Indian silver (rupees), during the British raj and for some coins during the first Brazilian Republic.
* 916: 88 zolotnik Russian silver
* 900: one nine fine, coin-silver, or 90% silver: e.g. Flowing Hair and 1837–1964 U.S. silver coins. Also used in U.S. silver commemorative coins and silver proof coins 1982–2018.
* 892.4: US coinage fine "standard silver" as defined by the Coinage Act of 1792: e.g. Draped Bust and Capped Bust U.S. silver coins (1795–1836)
* 875: 84 zolotnik is the most common fineness for Russian silver. Swiss standard, commonly used for export watchcases (also 800 and later 935).
* 868: 83 zolotnik. Imperial Russian coinage between 1797 and 1885.
* 835: A standard predominantly used in Germany after 1884, and for some Dutch silver; and for the minting of coins in countries of the Latin Monetary Union
* 833: () a common standard for continental silver especially among the Dutch, Swedish, and Germans
* 830: A common standard used in older Scandinavian silver
* 800: The minimum standard for silver in Germany after 1884; the French 2nd standard for silver; "plata de segunda ley" in Spain (second law silver); Egyptian silver; Canadian silver circulating coinage from 1920-1966/7
* 750: An uncommon silver standard found in older German, Swiss and Austro-Hungarian silver
* 720: Decoplata: many Mexican and Dutch silver coins use this standard, as well as some coins from Portugal's former colonies, Japan, Uruguay, Ecuador, Egypt, and Morocco.
* 600: Used in some examples of postwar Japanese coins, such as the 1957-1966 100 yen coin
* 500: Standard used for making British coinage 1920–1946 as well as Canadian coins from 1967-1968, and some coins from Colombia and Brazil.
* 400: Standard used for US half dollars between 1965 and 1970, and commemorative issue Eisenhower dollars between 1971 and 1978. Also used in some Swedish Krona coins.
* 350: Standard used for US Jefferson "war nickels" minted between 1942 and 1945. | 1 | Applied and Interdisciplinary Chemistry |
A spiropyran is a 2H-pyran isomer that has the hydrogen atom at position two replaced by a second ring system linked to the carbon atom at position two of the pyran molecule in a spiro way. So there is a carbon atom which is common on both rings, the pyran ring and the replaced ring. The second ring, the replaced one, is usually heterocyclic but there are exceptions.
When the spiropyran is in a solution with polar solvents or when it receives heating (thermochromism) or radiation (photochromism) it becomes coloured because its structure has changed and it has been transformed into the merocyanine form.
The structural differences between spiropyran and merocyanine form is that, while in the first one the ring is in the closed form, in the other one the ring is opened. The photochromism is due to electrocyclic cleavage of the C-spiro-O bond with photoexcitation. | 0 | Theoretical and Fundamental Chemistry |
Researchers in structural geology are concerned with the orientations of planes and lines for a number of reasons. The foliation of a rock is a planar feature that often contains a linear feature called lineation. Similarly, a fault plane is a planar feature that may contain linear features such as slickensides.
These orientations of lines and planes at various scales can be plotted using the methods of the Visualization of lines and planes section above. As in crystallography, planes are typically plotted by their poles. Unlike crystallography, the southern hemisphere is used instead of the northern one (because the geological features in question lie below the Earth's surface). In this context the stereographic projection is often referred to as the equal-angle lower-hemisphere projection. The equal-area lower-hemisphere projection defined by the Lambert azimuthal equal-area projection is also used, especially when the plot is to be subjected to subsequent statistical analysis such as density contouring. | 0 | Theoretical and Fundamental Chemistry |
Gastrointestinal symptoms are the most common side effects of potassium supplements, including nausea, vomiting, abdominal discomfort, and diarrhea. Taking potassium with meals or taking a microencapsulated form of potassium may reduce gastrointestinal side effects.
Hyperkalemia is the most serious adverse reaction to potassium. Hyperkalemia occurs when potassium builds up faster than the kidneys can remove it. It is most common in individuals with renal failure. Symptoms of hyperkalemia may include tingling of the hands and feet, muscular weakness, and temporary paralysis. The most serious complication of hyperkalemia is the development of an abnormal heart rhythm (arrhythmia), which can lead to cardiac arrest.
Although hyperkalemia is rare in healthy individuals, oral doses greater than 18 grams taken at one time in individuals not accustomed to high intakes can lead to hyperkalemia. | 1 | Applied and Interdisciplinary Chemistry |
Proteins are also known to contain [FeS] centres, which feature one iron less than the more common [FeS] cores. Three sulfide ions bridge two iron ions each, while the fourth sulfide bridges three iron ions. Their formal oxidation states may vary from [FeS] (all-Fe form) to [FeS] (all-Fe form). In a number of iron–sulfur proteins, the [FeS] cluster can be reversibly converted by oxidation and loss of one iron ion to a [FeS] cluster. E.g., the inactive form of aconitase possesses an [FeS] and is activated by addition of Fe and reductant. | 0 | Theoretical and Fundamental Chemistry |
Agriculture-
Gravity separation tables are used for the removal of impurities, admixture, insect damage and immature kernels from the following examples: wheat, barley, oilseed rape, peas, beans, cocoa beans, linseed. They can be used to separate and standardize coffee beans, cocoa beans, peanuts, corn, peas, rice, wheat, sesame and other food grains.
The gravity separator separates products of same size but with difference in specific weight. It has a vibrating rectangular deck, which makes it easy for the product to travel a longer distance, ensuring improved quality of the end product. The pressurized air in the deck enables the material to split according to its specific weight. As a result, the heavier particles travel to the higher level while the lighter particles travel to the lower level of the deck. It comes with easily adjustable air fans to control the volume of air distribution at different areas of the vibrating deck to meet the air supply needs of the deck. The table inclination, speed of eccentric motion and the feed rate can be precisely adjusted to achieve smooth operation of the machine. | 0 | Theoretical and Fundamental Chemistry |
In biochemistry, the hydrophobic effect can be used to separate mixtures of proteins based on their hydrophobicity. Column chromatography with a hydrophobic stationary phase such as phenyl-sepharose will cause more hydrophobic proteins to travel more slowly, while less hydrophobic ones elute from the column sooner. To achieve better separation, a salt may be added (higher concentrations of salt increase the hydrophobic effect) and its concentration decreased as the separation progresses. | 0 | Theoretical and Fundamental Chemistry |
Methylotrophs use the electron transport chain to conserve energy produced from the oxidation of compounds. An additional activation step is required in methanotrophic metabolism to allow degradation of chemically-stable methane. This oxidation to methanol is catalyzed by MMO, which incorporates one oxygen atom from into methane and reduces the other oxygen atom to water, requiring two equivalents of reducing power. Methanol is then oxidized to formaldehyde through the action of methanol dehydrogenase (MDH) in bacteria, or a non-specific alcohol oxidase in yeast. Electrons from methanol oxidation are passed to a membrane-associated quinone of the electron transport chain to produce .
In dissimilatory processes, formaldehyde is completely oxidized to <chem>CO2
associated dehydrogenases, is produced.
Finally, formate is oxidized to by cytoplasmic or membrane-bound Formate dehydrogenase (FDH), producing and . | 0 | Theoretical and Fundamental Chemistry |
In A. thaliana, the main feedback loop is proposed to involve a transcriptional regulation between several proteins. The three main components of this loop are TOC1 (also known as PRR1), CCA1 and LHY. Each individual component peaks in transcriptions at different times of day. PRR 9, 7 and 5 each significantly reduce the transcription levels of CCA1 and LHY. In the opposite manner, PRR 9 and 7 slightly increase the transcription levels of TOC1. The Constans (CO) is also indirectly regulated by the PRR proteins as well by setting up the molecular mechanism to dictate the photosensitive period in the afternoon. PRRs are also known to stabilize CO at certain times of day to mediate its accumulation. This results in the regulation of early flowering in shorter photoperiods, making light sensitivity and control of flowering time important functions of the PRR class. | 1 | Applied and Interdisciplinary Chemistry |
For turbulent flow, methods for finding the friction factor include using a diagram, such as the Moody chart, or solving equations such as the Colebrook–White equation (upon which the Moody chart is based), or the Swamee–Jain equation. While the Colebrook–White relation is, in the general case, an iterative method, the Swamee–Jain equation allows to be found directly for full flow in a circular pipe. | 1 | Applied and Interdisciplinary Chemistry |
For many years, gene mapping was limited to identifying organisms by traditional phenotypes markers. This included genes that encoded easily observable characteristics such as blood types or seed shapes. The insufficient number of these types of characteristics in several organisms limited the mapping efforts that could be done. This prompted the development of gene markers which could identify genetic characteristics that are not readily observable in organisms (such as protein variation). | 1 | Applied and Interdisciplinary Chemistry |
N-heterocyclic carbenes are similar to cyanide in reactivity. Like cyanide, they have an unusual chemical ambivalence, which allows them to trigger umpolung in reactions where they are involved. The carbene has six electrons - two each in the carbon-nitrogen single bonds, two in its sp-hybridized orbital, and an empty p-orbital. The sp lone pair acts as an electron donor, whereas the empty p-orbital is capable as acting as an electron acceptor.
In this example, the β-carbon of the α,β-unsaturated ester 1 formally acts as a nucleophile, whereas normally it would be expected to be a Michael acceptor.
This carbene reacts with the α,β-unsaturated ester 1 at the β-position forming the intermediate enolate 2. Through tautomerization 2b can displace the terminal bromine atom to 3. An elimination reaction regenerates the carbene and releases the product 4.
For comparison: in the Baylis-Hillman reaction the same electrophilic β-carbon atom is attacked by a reagent but resulting in the activation of the α-position of the enone as the nucleophile. | 0 | Theoretical and Fundamental Chemistry |
Ocean acidification threatens the Great Barrier Reef by reducing the viability and strength of coral reefs. The Great Barrier Reef, considered one of the seven natural wonders of the world and a biodiversity hotspot, is located in Australia. Similar to other coral reefs, it is experiencing degradation due to ocean acidification. Ocean acidification results from a rise in atmospheric carbon dioxide, which is taken up by the ocean. This process can increase sea surface temperature, decrease aragonite, and lower the pH of the ocean. The more humanity consumes fossil fuels, the more the ocean absorbs released CO₂, furthering ocean acidification.
This decreased health of coral reefs, particularly the Great Barrier Reef, can result in reduced biodiversity. Organisms can become stressed due to ocean acidification and the disappearance of healthy coral reefs, such as the Great Barrier Reef, is a loss of habitat for several taxa. | 0 | Theoretical and Fundamental Chemistry |
The Final Phase of the IEAGHG Weyburn-Midale CO Monitoring and Storage Project is utilizing scientific experts from most of the world's leading carbon capture and storage research organizations and universities to further develop and build upon the most scrutinized CO geological storage data set in the world.
The project's major technical research "themes" can be broadly broken out into four areas:
Technical Components:
* Site Characterization: The research will develop geocellular framework models that incorporate geotechnical and simulation work that will help with proper risk management of the site.
*Wellbore Integrity: increase the knowledge, and assess the risk of leakage from enclosed wells caused by materials and cement degradation. This issue is viewed as critical for resolving questions around long-term storage.
* Monitoring and Verification: Field test and assess a range of geochemical and geophysical techniques for monitoring the injected CO.
* Performance Assessment: Perform simulations for containment and performance assessments; engage public stakeholders and experts in the risk assessment process.
Ultimately, the goal of the final phase of the project is to produce a best practices manual that can be used by other jurisdictions and organizations to help transition CO-EOR operations into long-term storage projects. The research of the project's final phase should be complete in 2011, with the Best Practices Manual issued before the end of that year. | 1 | Applied and Interdisciplinary Chemistry |
Thermodynamic work is one of the principal processes by which a thermodynamic system can interact with its surroundings and exchange energy. This exchange results in externally measurable macroscopic forces on the system's surroundings, which can cause mechanical work, to lift a weight, for example, or cause changes in electromagnetic, or gravitational variables. The surroundings also can perform work on a thermodynamic system, which is measured by an opposite sign convention.
For thermodynamic work, appropriately chosen externally measured quantities are exactly matched by values of or contributions to changes in macroscopic internal state variables of the system, which always occur in conjugate pairs, for example pressure and volume or magnetic flux density and magnetization.
In the International System of Units (SI), work is measured in joules (symbol J). The rate at which work is performed is power, measured in joules per second, and denoted with the unit watt (W). | 0 | Theoretical and Fundamental Chemistry |
Amalgamated zinc is prepared by treating zinc metal with a 2% solution of mercury(II) chloride. The metal may be in the granulated form or as shavings, wool, or powder. The amalgam forms on the surface of the zinc. After washing to remove salts, the amalgam is placed in a long glass tube, similar to a chromatography column, equipped with a stopcock. The amalgam is a more effective reducing agent than zinc metal. The effluent is often air-sensitive, requiring the use of air-free techniques.
To use the reductor, the solution to be reduced is drawn through the tube. If the column is loosely packed, the solution may pass through without assistance. The length of the column or the flow rate are adjusted to effect full reduction of the soluble reagent. The effluent is also contaminated with zinc(II) salts, but they do not affect subsequent operations. These operations might include iodometric titration to determine the reducible content of the effluent. In some cases, the effluent is treated with other reagents to precipitate a compound of the reduced ions. | 0 | Theoretical and Fundamental Chemistry |
Levocetirizine is an antihistamine. It acts as an inverse agonist that decreases activity at histamine H1 receptors. This in turn prevents the release of other allergy chemicals and increases the blood supply to the area, providing relief from the typical symptoms of hay fever. Levocetirizine, (R)-(-)-cetirizine, is essentially a chiral switch of (±)-cetirizine. This enantiomer, the eutomer, is more selective and the (S)-counterpart, the distomer, is inactive. | 0 | Theoretical and Fundamental Chemistry |
Solid materials are formed from densely packed atoms, which interact intensely. These interactions produce the mechanical (e.g. hardness and elasticity), thermal, electrical, magnetic and optical properties of solids. Depending on the material involved and the conditions in which it was formed, the atoms may be arranged in a regular, geometric pattern (crystalline solids, which include metals and ordinary water ice) or irregularly (an amorphous solid such as common window glass).
The bulk of solid-state physics, as a general theory, is focused on crystals. Primarily, this is because the periodicity of atoms in a crystal — its defining characteristic — facilitates mathematical modeling. Likewise, crystalline materials often have electrical, magnetic, optical, or mechanical properties that can be exploited for engineering purposes.
The forces between the atoms in a crystal can take a variety of forms. For example, in a crystal of sodium chloride (common salt), the crystal is made up of ionic sodium and chlorine, and held together with ionic bonds. In others, the atoms share electrons and form covalent bonds. In metals, electrons are shared amongst the whole crystal in metallic bonding. Finally, the noble gases do not undergo any of these types of bonding. In solid form, the noble gases are held together with van der Waals forces resulting from the polarisation of the electronic charge cloud on each atom. The differences between the types of solid result from the differences between their bonding. | 1 | Applied and Interdisciplinary Chemistry |
The first pass effect (also known as first-pass metabolism or presystemic metabolism) is a phenomenon of drug metabolism at a specific location in the body which leads to a reduction in the concentration of the active drug before it reaches the site of action or systemic circulation. The effect is most associated with orally administered medications, but some drugs still undergo first-pass metabolism even when delivered via an alternate route (e.g., IV, IM, etc). During this metabolism, drug is lost during the process of absorption which is generally related to the liver and gut wall. The liver is the major site of first pass effect; however, it can also occur in the lungs, vasculature or other metabolically active tissues in the body. Notable drugs that experience a significant first-pass effect are buprenorphine, chlorpromazine, cimetidine, diazepam, ethanol (drinking alcohol), imipramine, insulin, lidocaine, midazolam, morphine, pethidine, propranolol, and tetrahydrocannabinol (THC). First-pass metabolism is not to be confused with Phase I metabolism, which is a separate process.
First pass metabolism may occur in the liver (for propranolol, lidocaine, clomethiazole, and nitroglycerin) or in the gut (for benzylpenicillin and insulin).
After a drug is swallowed, it is absorbed by the digestive system and enters the hepatic portal system. It is carried through the portal vein into the liver before it reaches the rest of the body. The liver metabolizes many drugs, sometimes to such an extent that only a small amount of active drug emerges from the liver to the rest of the circulatory system. This first pass through the liver thus may greatly reduce the bioavailability of the drug.
An example of a drug where first pass metabolism is a complication and disadvantage is in the antiviral drug remdesivir. Remdesivir cannot be administered orally because the entire dose would be trapped in the liver with little achieving systemic circulation or reaching target organs and cells (for example, cells infected with SARS-CoV-2). For this reason, remdesivir is administered by IV infusion, bypassing the portal vein. However, significant hepatic extraction still occurs because of second pass metabolism, whereby a fraction of venous blood travels through the hepatic portal vein and hepatocytes.
The four primary systems that affect the first pass effect of a drug are the enzymes of the gastrointestinal lumen, gut wall enzymes, bacterial enzymes, and hepatic enzymes.
In drug design, drug candidates may have good druglikeness but fail on first-pass metabolism because it is biochemically selective.
Alternative routes of administration, such as insufflation, suppository, intravenous, intramuscular, inhalational aerosol, transdermal, or sublingual, avoid the first-pass effect because they allow drugs to be absorbed directly into the systemic circulation.
Drugs with high first pass effect typically have a considerably higher oral dose than sublingual or parenteral dose. There is marked individual variation in the oral dose due to differences in the extent of first pass metabolism, frequently among several other factors. Oral bioavailability of many vulnerable drugs appears to be increased in patients with compromised liver function. Bioavailability is also increased if another drug competing for first pass metabolism enzymes is given concurrently (e.g., propranolol and chlorpromazine). | 1 | Applied and Interdisciplinary Chemistry |
Ion channels containing calixarenes of ring size 3 and 4 have both been reported. For calix[4]arene, two conformations are accessible, and examples of both 1,3-alt and cone conformation have been developed. | 0 | Theoretical and Fundamental Chemistry |
The magnetic Reynolds number has a similar form to both the Péclet number and the Reynolds number. All three can be regarded as giving the ratio of advective to diffusive effects for a particular physical field and have the form of the product of a velocity and a length divided by a diffusivity. While the magnetic Reynolds number is related to the magnetic field in an magnetohydrodynamic flow, the Reynolds number is related to the fluid velocity itself and the Péclet number is related to heat. The dimensionless groups arise in the non-dimensionalization of the respective governing equations: the induction equation, the Navier–Stokes equations, and the heat equation. | 1 | Applied and Interdisciplinary Chemistry |
In column chromatography a mixture of substances is dissolved in a mobile phase and passed over a stationary phase in a column. A selectivity factor is defined as the ratio of distribution coefficients, which describe the equilibrium distribution of an analyte between the stationary phase and the mobile phase. The selectivity factor is equal to the selectivity coefficient with the added assumption that the activity of the stationary phase, the substrate in this case, is equal to 1, the standard assumption for a pure phase. The resolution of a chromatographic column, R is related to the selectivity factor by:
where α is selectivity factor, N is the number of theoretical plates k and k are the retention factors of the two analytes. Retention factors are proportional to distribution coefficients. In practice substances with a selectivity factor very close to 1 can be separated. This is particularly true in gas-liquid chromatography where column lengths up to 60 m are possible, providing a very large number of theoretical plates.
In ion-exchange chromatography the selectivity coefficient is defined in a slightly different way | 0 | Theoretical and Fundamental Chemistry |
Normative mineralogy is a calculation of the composition of a rock sample that estimates the idealised mineralogy of a rock based on a quantitative chemical analysis according to the principles of geochemistry.
Normative mineral calculations can be achieved via either the CIPW Norm or the Barth-Niggli Norm (also known as the Cation Norm).
Normative calculations are used to produce an idealised mineralogy of a crystallized melt. First, a rock is chemically analysed to determine the elemental constituents. Results of the chemical analysis traditionally are expressed as oxides (e.g., weight percent Mg is expressed as weight percent MgO). The normative mineralogy of the rock then is calculated, based upon assumptions about the order of mineral formation and known phase relationships of rocks and minerals, and using simplified mineral formulas. The calculated mineralogy can be used to assess concepts such as silica saturation of melts.
Because the normative calculation is essentially a computation, it can be achieved via computer programs. | 0 | Theoretical and Fundamental Chemistry |
Organoberyllium phosphines are another class of compounds that is used in synthesis. Phosphine donates two electrons into the beryllium center. Phosphines are L-type ligands. Unlike most metal ammine complexes, metal phosphine complexes tend to be lipophilic, displaying good solubility in organic solvents. Phosphine ligands are also π-acceptors. Their π-acidity arises from overlap of P-C σ* anti-bonding orbitals with filled metal orbitals. Beryllium can coordinate with a phosphine due to its good π-acceptor ability, which is used extensively in beryllium chemistry literature. An organoberyllium phosphine can be prepared through coordination with a beryllium halide to form a four-coordinate tetrahedral compound. | 0 | Theoretical and Fundamental Chemistry |
Oxidative stress reflects an imbalance between the systemic manifestation of reactive oxygen species and a biological system's ability to readily detoxify the reactive intermediates or to repair the resulting damage. Disturbances in the normal redox state of cells can cause toxic effects through the production of peroxides and free radicals that damage all components of the cell, including proteins, lipids, and DNA. Oxidative stress from oxidative metabolism causes base damage, as well as strand breaks in DNA. Base damage is mostly indirect and caused by the reactive oxygen species generated, e.g., O (superoxide radical), OH (hydroxyl radical) and HO (hydrogen peroxide). Further, some reactive oxidative species act as cellular messengers in redox signaling. Thus, oxidative stress can cause disruptions in normal mechanisms of cellular signaling.
In humans, oxidative stress is thought to be involved in the development of attention deficit hyperactivity disorder, cancer, Parkinsons disease, Lafora disease, Alzheimers disease, atherosclerosis, heart failure, myocardial infarction, fragile X syndrome, sickle-cell disease, lichen planus, vitiligo, autism, infection, chronic fatigue syndrome, and depression; however, reactive oxygen species can be beneficial, as they are used by the immune system as a way to attack and kill pathogens. Short-term oxidative stress may also be important in prevention of aging by induction of a process named mitohormesis, and is required to initiate stress response processes in plants. | 1 | Applied and Interdisciplinary Chemistry |
Chrome Azurol S is a histological dye used in biomedical research.
Chrome Azural S (CAS) is a common spectrophotometric reagent for detection of certain metals like aluminum which can be toxic in excess and can contribute to people with neurodegenerative disorders. CAS is used to provide quantitative and qualitative information on molecules of interest like aluminum and siderophores. Qualitatively a color change can be observed while also allowing to quantitatively determine concentration of certain ions. | 1 | Applied and Interdisciplinary Chemistry |
When an object is placed on a liquid, its weight depresses the surface, and if surface tension and downward force become equal then it is balanced by the surface tension forces on either side , which are each parallel to the waters surface at the points where it contacts the object. Notice that small movement in the body may cause the object to sink. As the angle of contact decreases, surface tension decreases. The horizontal components of the two arrows point in opposite directions, so they cancel each other, but the vertical components point in the same direction and therefore add up to balance . The objects surface must not be wettable for this to happen, and its weight must be low enough for the surface tension to support it. If denotes the mass of the needle and acceleration due to gravity, we have | 0 | Theoretical and Fundamental Chemistry |
The most common way to measure surface energy is through contact angle experiments. In this method, the contact angle of the surface is measured with several liquids, usually water and diiodomethane. Based on the contact angle results and knowing the surface tension of the liquids, the surface energy can be calculated. In practice, this analysis is done automatically by a contact angle meter.
There are several different models for calculating the surface energy based on the contact angle readings. The most commonly used method is OWRK, which requires the use of two probe liquids and gives out as a result the total surface energy as well as divides it into polar and dispersive components.
Contact angle method is the standard surface energy measurement method due to its simplicity, applicability to a wide range of surfaces and quickness. The measurement can be fully automated and is standardized.
In general, as surface energy increases, the contact angle decreases because more of the liquid is being "grabbed" by the surface. Conversely, as surface energy decreases, the contact angle increases, because the surface doesn't want to interact with the liquid. | 0 | Theoretical and Fundamental Chemistry |
It is far more difficult to produce a fermionic superfluid than a bosonic one, because the Pauli exclusion principle prohibits fermions from occupying the same quantum state. However, there is a well-known mechanism by which a superfluid may be formed from fermions: That mechanism is the BCS transition, discovered in 1957 by J. Bardeen, L.N. Cooper, and R. Schrieffer for describing superconductivity. These authors showed that, below a certain temperature, electrons (which are fermions) can pair up to form bound pairs now known as Cooper pairs. As long as collisions with the ionic lattice of the solid do not supply enough energy to break the Cooper pairs, the electron fluid will be able to flow without dissipation. As a result, it becomes a superfluid, and the material through which it flows a superconductor.
The BCS theory was phenomenally successful in describing superconductors. Soon after the publication of the BCS paper, several theorists proposed that a similar phenomenon could occur in fluids made up of fermions other than electrons, such as helium-3 atoms. These speculations were confirmed in 1971, when experiments performed by D.D. Osheroff showed that helium-3 becomes a superfluid below 0.0025 K. It was soon verified that the superfluidity of helium-3 arises from a BCS-like mechanism. | 0 | Theoretical and Fundamental Chemistry |
Corpuscularianism is similar to the theory of atomism, except that where atoms were supposed to be indivisible, corpuscles could in principle be divided. In this manner, for example, it was theorized that mercury could penetrate into metals and modify their inner structure, a step on the way towards the production of gold by transmutation. | 1 | Applied and Interdisciplinary Chemistry |
The Eyring equation (occasionally also known as Eyring–Polanyi equation) is an equation used in chemical kinetics to describe changes in the rate of a chemical reaction against temperature. It was developed almost simultaneously in 1935 by Henry Eyring, Meredith Gwynne Evans and Michael Polanyi. The equation follows from the transition state theory, also known as activated-complex theory. If one assumes a constant enthalpy of activation and constant entropy of activation, the Eyring equation is similar to the empirical Arrhenius equation, despite the Arrhenius equation being empirical and the Eyring equation based on statistical mechanical justification. | 0 | Theoretical and Fundamental Chemistry |
Bubbling through algal cultivation systems can greatly increase productivity and yield (up to a saturation point). Typically, about 1.8 tonnes of CO2| will be utilised per tonne of algal biomass (dry) produced, though this varies with algae species. The Glenturret Distillery in Perthshire percolate CO2| made during the whisky distillation through a microalgae bioreactor. Each tonne of microalgae absorbs two tonnes of . Scottish Bioenergy, who run the project, sell the microalgae as high value, protein-rich food for fisheries. In the future, they will use the algae residues to produce renewable energy through anaerobic digestion. | 1 | Applied and Interdisciplinary Chemistry |
The structure of SAMs is also dependent on the curvature of the substrate. SAMs on nanoparticles, including colloids and nanocrystals, "stabilize the reactive surface of the particle and present organic functional groups at the particle-solvent interface". These organic functional groups are useful for applications, such as immunoassays or sensors, that are dependent on chemical composition of the surface. | 0 | Theoretical and Fundamental Chemistry |
In 2017, the European Food Safety Authority concluded that betaine was safe "as a novel food to be used at a maximum intake level of 6 mg/kg body weight per day in addition to the intake from the background diet." | 0 | Theoretical and Fundamental Chemistry |
Ethyl bromoacetate is listed by the World Health Organization as a riot control agent, and was first employed for that purpose by French police in 1912. The French army used rifle grenades grenades lacrymogènes filled with this gas against the Germans beginning in August 1914, but the weapons were largely ineffective, even though ethyl bromoacetate is twice as toxic as chlorine. In the early months of the war the British also used the weaponized use of tear gas agents and more toxic gasses including sulfur dioxide. The German army then used these attacks to justify their subsequent employment of it as odorant or warning agent in odorless, toxic gases and chemical weapons in 1915 under the German code Weisskreuz (White Cross).
In organic synthesis, it is a versatile alkylating agent. Its major application involves the Reformatsky reaction, wherein it reacts with zinc to form a zinc enolate. The resulting condenses with carbonyl compounds to give a β-hydroxy-esters.
It is also the starting point for the preparation of several other reagents. For example, the related Wittig reagent (prepared by reaction with triphenylphosphine) is commonly used to prepare alpha,beta-unsaturated esters from carbonyl compounds such as benzaldehyde: | 0 | Theoretical and Fundamental Chemistry |
(AD 800/900–1450)
Utilitarian and ceremonial objects; objects of personal adornment
#Amapa, Nayarit
#Apatzingán, Michoacán
#Atoyac, Jalisco
#Cojumatlán, Michoacán
#Coyuca de Catalán, Guerrero
#Culiacán, Sinaloa
#Jiquilpan, Michoacán
#Peñitas, Nayarit
#Río Balsas, Guerrero
#Tancitaro, Michoacán
#Telpalcátepec, Michoacán
#Tepic, Nayarit
#Texmelincan, Guerrero
#Tuxcacuesco, Jalisco
#Tzintzuntzan, Michoacán
#Yestla, Guerrero
#Zacpu, Michoacán
#Zamora, Michoacán | 1 | Applied and Interdisciplinary Chemistry |
Using mathematical terms, terminal speed—without considering buoyancy effects—is given by
where
* represents terminal velocity,
* is the mass of the falling object,
* is the acceleration due to gravity,
* is the drag coefficient,
* is the density of the fluid through which the object is falling, and
* is the projected area of the object.
In reality, an object approaches its terminal speed asymptotically.
Buoyancy effects, due to the upward force on the object by the surrounding fluid, can be taken into account using Archimedes' principle: the mass has to be reduced by the displaced fluid mass , with the volume of the object. So instead of use the reduced mass in this and subsequent formulas.
The terminal speed of an object changes due to the properties of the fluid, the mass of the object and its projected cross-sectional surface area.
Air density increases with decreasing altitude, at about 1% per (see barometric formula). For objects falling through the atmosphere, for every of fall, the terminal speed decreases 1%. After reaching the local terminal velocity, while continuing the fall, speed decreases to change with the local terminal speed.
Using mathematical terms, defining down to be positive, the net force acting on an object falling near the surface of Earth is (according to the drag equation):
with v(t) the velocity of the object as a function of time t.
At equilibrium, the net force is zero (F = 0) and the velocity becomes the terminal velocity :
Solving for V yields:
The drag equation is—assuming ρ, g and C to be constants:
Although this is a Riccati equation that can be solved by reduction to a second-order linear differential equation, it is easier to separate variables.
A more practical form of this equation can be obtained by making the substitution .
Dividing both sides by m gives
The equation can be re-arranged into
Taking the integral of both sides yields
After integration, this becomes
or in a simpler form
with artanh the inverse hyperbolic tangent function.
Alternatively,
with tanh the hyperbolic tangent function. Assuming that g is positive (which it was defined to be), and substituting α back in, the speed v becomes
Using the formula for terminal velocity
the equation can be rewritten as
As time tends to infinity (t → ∞), the hyperbolic tangent tends to 1, resulting in the terminal speed
For very slow motion of the fluid, the inertia forces of the fluid are negligible (assumption of massless fluid) in comparison to other forces. Such flows are called creeping or Stokes flows and the condition to be satisfied for the flows to be creeping flows is the Reynolds number, . The equation of motion for creeping flow (simplified Navier–Stokes equation) is given by:
where:
* is the fluid velocity vector field,
* is the fluid pressure field,
* is the liquid/fluid viscosity.
The analytical solution for the creeping flow around a sphere was first given by Stokes in 1851.
From Stokes' solution, the drag force acting on the sphere of diameter can be obtained as
where the Reynolds number, . The expression for the drag force given by equation () is called Stokes' law.
When the value of is substituted in the equation (), we obtain the expression for terminal speed of a spherical object moving under creeping flow conditions:
where is the density of the object. | 1 | Applied and Interdisciplinary Chemistry |
Uteroglobin, or blastokinin, also known as secretoglobin family 1A member 1 (SCGB1A1), is a protein that in humans is encoded by the SCGB1A1 gene.
SCGB1A1 is the founding member of the secretoglobin family of small, secreted, disulfide-bridged dimeric proteins found only in mammals. This antiparallel disulfide linked homodimeric protein is multifunctional and found in various tissues in various names such as: uteroglobin (UG, UGB), uteroglobin-like antigen (UGL), blastokinin, club-cell secretory protein (CCSP), Clara-cell 16 kD protein (17 in rat/mice), club-cell-specific 10 kD protein (CC10), human protein 1, urine protein 1 (UP-1), polychlorinated biphenyl-binding protein (PCB-BP), human club cell phospholipid-binding protein (hCCPBP), secretoglobin 1A member 1 (SCGB1A1).
This protein is specifically expressed in club cells in the lungs. | 1 | Applied and Interdisciplinary Chemistry |
The intermolecular oxidations of olefins with alcohols as nucleophile typically generate ketals, where as the palladium-catalyzed oxidations of olefins with carboxylic acids as nucleophile generates vinylic or allylic carboxylates. In case of diols, their reactions with alkenes typically generate ketals, whereas reactions of olefins bearing electron-withdrawing groups tend to form acetals.
Palladium-catalyzed intermolecular oxidations of dienes with carboxylic acids and alcohols as donors give 1,4-addition products. In the case of cyclohexadiene (Figure 4, A), Backvall found that stereochemical outcome of product was found to depend on concentration of LiCl. This reaction proceeds by first generating the Pd(OAc)(benzoquinone)(allyl) complex, through anti-nucleopalladation of diene with acetate as nucleophile. The absence of LiCl induces an inner sphere reductive elimination to afford the trans-acetate stereochemistry to give the trans-1,4-adduct. The presence of LiCl displaces acetate with chloride due to its higher binding affinity, which forces an outer sphere acetate attack anti to the palladium, and affords the cis-acetate stereochemistry to give the cis-1,4-adduct. Intramolecular oxidative cyclization: 2-(2-cyclohexenyl)phenol cyclizes to corresponding dihydro-benzofuran (Figure 4, B); 1-cyclohexadiene-acetic acid in presence of acetic acid cyclizes to corresponding lactone-acetate 1,4 adduct (Figure 4, C), with cis and trans selectivity controlled by LiCl presence. | 0 | Theoretical and Fundamental Chemistry |
During heat treating, a blacksmith causes phase changes in the iron-carbon system to control the material's mechanical properties, often using the annealing, quenching, and tempering processes. In this context, the color of light, or "blackbody radiation", emitted by the workpiece is an approximate gauge of temperature. Temperature is often gauged by watching the color temperature of the work, with the transition from a deep cherry-red to orange-red ( to ) corresponding to the formation of austenite in medium and high-carbon steel. In the visible spectrum, this glow increases in brightness as temperature increases. When cherry-red, the glow is near its lowest intensity and may not be visible in ambient light. Hence blacksmiths usually austenitize steel in low-light conditions to accurately judge the color of the glow. | 1 | Applied and Interdisciplinary Chemistry |
Peters died from hospital-acquired COVID-19 on April 13, 2020, four days before his 83rd birthday. He contracted the virus while in a Bloomington hospital recovering from a fall.
Peters name was included in the May 2020 New York Times tribute U.S. Deaths Near 100,000, An Incalculable Loss to the 100,000 Americans who lost their lives as a direct result of the pandemic. A reporter for the Indiana Daily Student' wrote that "Peters had a roaring voice that filled lecture halls". | 0 | Theoretical and Fundamental Chemistry |
Internal liners can be used to either protect the metallic bellows from erosion or reduce turbulence across the bellows. They must be used when purge connectors are included in the design. In order to provide enough clearance in the liner design, appropriate lateral and angular movements must be specified by the designer. When designing an expansion joint with combination ends, flow direction must be specified as well. | 1 | Applied and Interdisciplinary Chemistry |
Tertiary phosphines are often used as ligands in coordination chemistry. The binding of phosphines bind to metals, which serve as Lewis acids. For example, silver chloride reacts with triphenylphosphine to 1;1 and 1:2 complexes:
:PPh + AgCl → ClAgPPh
:PPh + ClAgPPh → ClAg(PPh)
The adducts formed from phosphines and borane are useful reagents. These phosphine-boranes are air-stable, but the borane protecting group can be removed by treatment with amines. | 0 | Theoretical and Fundamental Chemistry |
The lime stones selected were those that had the least amount of impurities within them. Limepits were almost always built near the supply of limestone, and a sufficient pile of wood kindling was heaped in great store before the actual burning process began, a supply that was to last between 3 and 7 days of continual burning, both, by night and day. In the southern Mediterranean regions, one of the favorite wood sources was thorny burnet (Sarcopoterium spinosum). The fire was attended by men with long staves and pitchforks who pushed the burning material into the pit. Initially, a cloud of smoke billowed from the pit. After several days of burning, when the uppermost stone in the fire pit began to glow a fiery red, it signaled that the burning process of the lime was finished, and that the process of carbon dioxide emissions from the limestone has been completed, and that the lime was now ready for marketing as lime or powder. After being allowed to cool, the burnt limestone was extracted from the pit when it was light and brittle. During the burning process, the limestone loses about 50% of its original anatomical weight. The lime becomes ready for use only after water has been added. | 1 | Applied and Interdisciplinary Chemistry |
Toxicants, ionic concentrations, available nutrients, temperature (and light), and dissolved oxygen are key stressors to urban streams. | 1 | Applied and Interdisciplinary Chemistry |
Water is the medium of the oceans, the medium which carries all the substances and elements involved in the marine biogeochemical cycles.
Water as found in nature almost always includes dissolved substances, so water has been described as the "universal solvent" for its ability to dissolve so many substances. This ability allows it to be the "solvent of life" Water is also the only common substance that exists as solid, liquid, and gas in normal terrestrial conditions. Since liquid water flows, ocean waters cycle and flow in currents around the world. Since water easily changes phase, it can be carried into the atmosphere as water vapour or frozen as an iceberg. It can then precipitate or melt to become liquid water again. All marine life is immersed in water, the matrix and womb of life itself. Water can be broken down into its constituent hydrogen and oxygen by metabolic or abiotic processes, and later recombined to become water again.
While the water cycle is itself a biogeochemical cycle, flow of water over and beneath the Earth is a key component of the cycling of other biogeochemicals. Runoff is responsible for almost all of the transport of eroded sediment and phosphorus from land to waterbodies. Cultural eutrophication of lakes is primarily due to phosphorus, applied in excess to agricultural fields in fertilizers, and then transported overland and down rivers. Both runoff and groundwater flow play significant roles in transporting nitrogen from the land to waterbodies. The dead zone at the outlet of the Mississippi River is a consequence of nitrates from fertilizer being carried off agricultural fields and funnelled down the river system to the Gulf of Mexico. Runoff also plays a part in the carbon cycle, again through the transport of eroded rock and soil. | 0 | Theoretical and Fundamental Chemistry |
The M30 Apoptosense® ELISA is a PEVIVA product owned by VLVbio (Nacka, Sweden) and was developed in collaboration with the Karolinska Institute in 2000.
Distributors:
* In the United States and Canada, the Peviva products are distributed by DiaPharma Group, Inc
* In the United Kingdom, the products are distributed by bioaxxess
* China - Boppard CO., Ltd.
* Distributors in Japan - Funakoshi Co., Ltd
* In Germany, Switzerland and Benelux, the products are distributed by TECOmedical | 1 | Applied and Interdisciplinary Chemistry |
Photoconductive detection is similar to photoconductive generation. Here, the voltage bias across the antenna leads is generated by the electric field of the THz pulse focused onto the antenna, rather than some external generation. The THz electric field drives current across the antenna leads, which is usually amplified with a low-bandwidth amplifier. This amplified current is the measured parameter that corresponds to the THz field strength. Again, the carriers in the semiconductor substrate have an extremely short lifetime. Thus, the THz electric field strength is only sampled for an extremely narrow slice (femtoseconds) of the entire electric field waveform. | 0 | Theoretical and Fundamental Chemistry |
Encapsulins serve many physiological functions, including catalysis, mineral storage, response to oxidative stress and secondary metabolism. There are ferritin-like encapsulins as well. | 1 | Applied and Interdisciplinary Chemistry |
Petite mutants can be generated in the laboratory by using high-efficiency treatments such as acriflavine, ethidium bromide, and other intercalating agents. Their mechanisms work to break down and cause the eventual loss of mitochondrial DNA: if the treatment time increases, the amount of mitochondrial DNA will decrease. After prolonged treatment, petites containing no detectable mitochondrial DNA were obtained. It is useful approach to illustrate the function of mitochondrial DNA in yeast growth. | 1 | Applied and Interdisciplinary Chemistry |
Liquid water is essential for carbon-based life. Chemical bonding of carbon molecules requires liquid water. Water has the chemical property to make compound-solvent pairing. In humans, 55% to 60% of the body is water. Water provides the reversible hydration of carbon dioxide. Hydration of carbon dioxide is needed in carbon-based life. All life on Earth uses the same biochemistry of carbon. Water is important in life's carbonic anhydrase the interaction of between carbon dioxide and water. Carbonic anhydrase needs a family of carbon base enzymes for the hydration of carbon dioxide and acid–base homeostasis, that regulates PH levels in life. In plant life, liquid water is needed for photosynthesis, the biological process plants use to convert light energy and carbon dioxide into chemical energy. | 1 | Applied and Interdisciplinary Chemistry |
Thermal spraying is a line of sight process and the bond mechanism is primarily mechanical. Thermal spray application is not compatible with the substrate if the area to which it is applied is complex or blocked by other bodies. | 1 | Applied and Interdisciplinary Chemistry |
The GEOMAR - Helmholtz Centre for Ocean Research Kiel (GEOMAR), formerly known as the Leibniz Institute of Marine Sciences (German: Leibniz-Institut für Meereswissenschaften, IFM-GEOMAR), is a research institute in Kiel, Germany. It was formed in 2004 by merging the Institute for Marine Science (Institut für Meereskunde Kiel, (IFM)) with the Research Center for Marine Geosciences (GEOMAR) and is co-funded by both federal and provincial governments. It was a member of the Leibniz Association until 2012 and is coordinator of the FishBase Consortium. Since 2012 it is member of the Helmholtz Association and named GEOMAR - Helmholtz Centre for Ocean Research Kiel. The institute operates worldwide in all ocean basins, specialising in climate dynamics, marine ecology and biogeochemistry, and ocean floor dynamics and circulation. GEOMAR offers degree courses in affiliation with the University of Kiel, and operates the Kiel Aquarium and the Lithothek, a repository for split sediment core samples. | 0 | Theoretical and Fundamental Chemistry |
Transport Phenomena is the first textbook about transport phenomena. It is specifically designed for chemical engineering students. The first edition was published in 1960, two years after having been preliminarily published under the title Notes on Transport Phenomena based on mimeographed notes prepared for a chemical engineering course taught at the University of Wisconsin–Madison during the academic year 1957-1958. The second edition was published in August 2001. A revised second edition was published in 2007. This text is often known simply as BSL after its authors' initials. | 1 | Applied and Interdisciplinary Chemistry |
Daltons atomic theory remained controversial throughout the 19th century. Whilst the Law of definite proportion was accepted, the hypothesis that this was due to atoms was not so widely accepted. For example, in 1826 when Sir Humphry Davy presented Dalton the Royal Medal from the Royal Society, Davy said that the theory only became useful when the atomic conjecture was ignored. English chemist Sir Benjamin Collins Brodie in 1866 published the first part of his Calculus of Chemical Operations as a non-atomic alternative to the atomic theory. He described atomic theory as a Thoroughly materialistic bit of joiners work. English chemist Alexander Williamson used his Presidential Address to the London Chemical Society in 1869 to defend the atomic theory against its critics and doubters. This in turn led to further meetings at which the positivists again attacked the supposition that there were atoms. The matter was finally resolved in Daltons favour in the early 20th century with the rise of atomic physics. | 1 | Applied and Interdisciplinary Chemistry |
Solid material in wastewater may be dissolved, suspended, or settled. Total dissolved solids or TDS (sometimes called filterable residue) is measured as the mass of residue remaining when a measured volume of filtered water is evaporated. The mass of dried solids remaining on the filter is called total suspended solids (TSS) or nonfilterable residue. Settleable solids are measured as the visible volume accumulated at the bottom of an Imhoff cone after water has settled for one hour. Turbidity is a measure of the light scattering ability of suspended matter in the water. Salinity measures water density or conductivity changes caused by dissolved materials. | 0 | Theoretical and Fundamental Chemistry |
The discovery of histone acetylation causing changes in transcription activity can be traced back to the work of Vicent Allfrey and colleagues in 1964. The group hypothesized that histone proteins modified by acetyl groups added negative charges to the positive lysines, and thus, reduced the interaction between DNA and histones. Histone modification is now considered a major regulatory mechanism that is involved in many different stages of genetic functions. Our current understanding is that acetylated lysine residues on histone tails is associated with transcriptional activation. In turn, deacetylated histones are associated with transcriptional repression. In addition, negative correlations have been found between several histone acetylation marks.
The regulatory mechanism is thought to be twofold. Lysine is an amino acid with a positive charge when unmodified. Lysines on the amino terminal tails of histones have a tendency to weaken the chromatin's overall structure. Addition of an acetyl group, which carries a negative charge, effectively removes the positive charge and hence, reduces the interaction between the histone tail and the nucleosome. This opens up the usually tightly packed nucleosome and allows transcription machinery to come into contact with the DNA template, leading to gene transcription. Repression of gene transcription is achieved by the reverse of this mechanism. The acetyl group is removed by one of the HDAC enzymes during deacetylation, allowing histones to interact with DNA more tightly to form compacted nucleosome assembly. This increase in the rigid structure prevents the incorporation of transcriptional machinery, effectively silencing gene transcription.
Another implication of histone acetylation is to provide a platform for protein binding. As a posttranslational modification, the acetylation of histones can attract proteins to elongated chromatin that has been marked by acetyl groups. It has been hypothesized that the histone tails offer recognition sites that attract proteins responsible for transcriptional activation. Unlike histone core proteins, histone tails are not part of the nucleosome core and are exposed to protein interaction. A model proposed that the acetylation of H3 histones activates gene transcription by attracting other transcription related complexes. Therefore, the acetyl mark provides a site for protein recognition where transcription factors interact with the acetylated histone tails via their bromodomain. | 0 | Theoretical and Fundamental Chemistry |
A beta particle, also called beta ray or beta radiation (symbol β), is a high-energy, high-speed electron or positron emitted by the radioactive decay of an atomic nucleus during the process of beta decay. There are two forms of beta decay, β decay and β decay, which produce electrons and positrons respectively.
Beta particles with an energy of 0.5 MeV have a range of about one metre in the air; the distance is dependent on the particle energy.
Beta particles are a type of ionizing radiation and for radiation protection purposes are regarded as being more ionising than gamma rays, but less ionising than alpha particles. The higher the ionising effect, the greater the damage to living tissue, but also the lower the penetrating power of the radiation. | 0 | Theoretical and Fundamental Chemistry |
One industrial application is the production of magnesium, which begins with production of magnesium chloride by chlorination of magnesium oxide:
Electrolysis of the resulting molten magnesium chloride is conducted at 700 °C:
Aluminium metal is produced from aluminium oxides by electrolysis of a molten mixture of sodium hexafluoroaluminate and alumina at 950 °C. This conversion is called the Hall-Haroult process. | 1 | Applied and Interdisciplinary Chemistry |
After the explanation of van der Waals forces by Fritz London, several scientists soon realised that his definition could be extended from the interaction of two molecules with induced dipoles to macro-scale objects by summing all of the forces between the molecules in each of the bodies involved. The theory is named after H. C. Hamaker, who derived the interaction between two spheres, a sphere and a wall, and presented a general discussion in a heavily cited 1937 paper.
The interaction of two bodies is then treated as the pairwise interaction of a set of N molecules at positions: R {i:1,2,... ...,N}. The distance between the molecules i and j is then:
The interaction energy of the system is taken to be:
where is the interaction of molecules i and j in the absence of the influence of other molecules.
The theory is however only an approximation which assumes that the interactions can be treated independently, the theory must also be adjusted to take into account quantum perturbation theory. | 0 | Theoretical and Fundamental Chemistry |
Laninamivir is approved for the treatment of influenza under the tradename Inavir in Japan but it is still in clinical trial in the USA. Laninamivir is a long acting inhaled drug given as a prodrug (laninamivir octanoate). Laninamivir is given as a single dose and remains active for at least 5 days and up to 7 days. | 1 | Applied and Interdisciplinary Chemistry |
In chemistry, a carbazide is a functional group with the general formula RNH-NH(C=O)NH-NHR. They can be derived from the condensation of carbonic acid with a hydrazine. Carbohydrazide is the simplest carbazide, with another common carbazide being diphenylcarbazide, which is used as an analytical reagent.
Diphenylcarbazide forms an intense blue color with chromium in the hexavalent state. It has an absorptivity coefficient of about 3400. That means very small amounts of chromium can be detected; 25 micrograms in 25 mL of solution are too dark to read on a spectral device, so concentrations well below that can be detected. | 0 | Theoretical and Fundamental Chemistry |
This method of organ printing uses spatially controlled light or laser to create a 2D pattern that is layered through a selective photopolymerization in the bio-ink reservoir. A 3D structure can then be built in layers using the 2D pattern. Afterwards the bio-ink is removed from the final product. SLA bioprinting allows for the creation of complex shapes and internal structures. The feature resolution for this method is extremely high and the only disadvantage is the scarcity of resins that are biocompatible. | 1 | Applied and Interdisciplinary Chemistry |
Endoglin has been found to be an auxiliary receptor for the TGF-beta receptor complex. It thus is involved in modulating a response to the binding of TGF-beta1, TGF-beta3, activin-A, BMP-2, BMP-7 and BMP-9. Beside TGF-beta signaling endoglin may have other functions. It has been postulated that endoglin is involved in the cytoskeletal organization affecting cell morphology and migration.
Endoglin has a role in the development of the cardiovascular system and in vascular remodeling. Its expression is regulated during heart development . Experimental mice without the endoglin gene die due to cardiovascular abnormalities. | 1 | Applied and Interdisciplinary Chemistry |
Before the development of the silicon microcantilever, gold foil or tungsten wires were used as AFM sensors. A range of designs of quartz crystal resonators have been used, the most famous is the above-mentioned qPlus sensor. A new development which is getting attention is the KolibriSensor, using a length extensional quartz resonator, with a very high resonant frequency (~1 MHz) allowing very fast operation. | 0 | Theoretical and Fundamental Chemistry |
IUPAC defines the temperature programmed chromatography Kovats index equation:
* & retention times of trailing and heading n-alkanes, respectively.
NOTE: TPGC index does depend on temperature program, gas velocity and the column used !
ASTM method D6730 defines the temperature programmed chromatography Kovats index equation:
Measured Kovats retention index values can be found in ASTM method D 6730 databases.
An extensive Kovats index database is compiled by NIST [https://webbook.nist.gov/chemistry/].
The equations produce significant different Kovats indices. | 0 | Theoretical and Fundamental Chemistry |
A cloudburst is an extreme form of production of liquid water from a supersaturated mixture of air and water vapour in the atmosphere. Supersaturation in the vapour phase is related to the surface tension of liquids through the Kelvin equation, the Gibbs–Thomson effect and the Poynting effect.
The International Association for the Properties of Water and Steam (IAPWS) provides a special equation for the Gibbs free energy in the metastable-vapor region of water in its Revised Release on the IAPWS Industrial Formulation 1997 for the Thermodynamic Properties of Water and Steam. All thermodynamic properties for the metastable-vapor region of water can be derived from this equation by means of the appropriate relations of thermodynamic properties to the Gibbs free energy. | 0 | Theoretical and Fundamental Chemistry |
The burning of octane, CH + / O → 8CO + 9HO has a ΔG° ~ –240 kcal/mol, corresponding to an equilibrium constant of 10, a number so large that it is of no practical significance, since there are only ~5 × 10 molecules in a kilogram of octane. | 0 | Theoretical and Fundamental Chemistry |
Yellow H-A or Reactive Yellow 3 has a formula of CHClNOS and a molecular weight of 593 g/mol, containing a monochlorotriazine ring. On agarose as supporting matrix, it was seen to purify cholesteryl ester transfer protein. | 0 | Theoretical and Fundamental Chemistry |
Metal carbonato and bicarbonate complexes are of no direct commercial importance. Several minerals are metal carbonates, and a few feature molecular carbonate complexes, e.g. hellyerite ([Ni(CO)(HO)]HO.
In the biological sphere, zinc bicarbonate complexes are central intermediates in the action of the carbonic anhydrase: | 0 | Theoretical and Fundamental Chemistry |
More generally, stereographic projection may be applied to the unit -sphere in ()-dimensional Euclidean space . If is a point of and a hyperplane in , then the stereographic projection of a point is the point of intersection of the line with . In Cartesian coordinates (, from 0 to ) on and (, from 1 to n) on , the projection from is given by
Defining
the inverse is given by
Still more generally, suppose that is a (nonsingular) quadric hypersurface in the projective space . In other words, is the locus of zeros of a non-singular quadratic form in the homogeneous coordinates . Fix any point on and a hyperplane in not containing . Then the stereographic projection of a point in is the unique point of intersection of with . As before, the stereographic projection is conformal and invertible on a non-empty Zariski open set. The stereographic projection presents the quadric hypersurface as a rational hypersurface. This construction plays a role in algebraic geometry and conformal geometry. | 0 | Theoretical and Fundamental Chemistry |
Scarlett served on several committees, including as the Chairman of the ISO Committee TC/24- “Methods of Particle Sizing other than Sieving”, Chairman of the Particle Size group of the Royal Society of Chemistry, and Secretary of the Particle Technology Subject group of the Institution of Chemical Engineers. He was a member of the AIChE Particle Technology Forum and of the Working Party on Particle Characterization and Agglomeration for the European Federation of Chemical Engineering. | 1 | Applied and Interdisciplinary Chemistry |
In addition, there are 4 other mammalian enzymes named CPA-3 through CPA-6, and none of these are expressed in the pancreas. Instead, these other CPA-like enzymes have diverse functions.
* CPA3 (also known as mast-cell CPA) is involved in the digestion of proteins by mast cells.
* CPA4 (previously known as CPA-3, but renumbered when mast-cell CPA was designated CPA-3) may be involved in tumor progression, but this enzyme has not been well studied.
* CPA5 has not been well studied.
* CPA6 is expressed in many tissues during mouse development, and in adult shows a more limited distribution in brain and several other tissues. CPA6 is present in the extracellular matrix where it is enzymatically active. A human mutation of CPA-6 has been linked to Duane's syndrome (abnormal eye movement). Recently, mutations in CPA6 were found to be linked to epilepsy. CPA6 is also one of several enzymes which degrade enkephalins. | 1 | Applied and Interdisciplinary Chemistry |
Jumping libraries or junction-fragment libraries are collections of genomic DNA fragments generated by chromosome jumping. These libraries allow the analysis of large areas of the genome and overcome distance limitations in common cloning techniques.
A jumping library clone is composed of two stretches of DNA that are usually located many kilobases away from each other. The stretch of DNA located between these two "ends" is deleted by a series of biochemical manipulations carried out at the start of this cloning technique. | 1 | Applied and Interdisciplinary Chemistry |
The potential for transcription and translation to regulate each other was recognized by the team of Marshall Nirenberg, who discovered that the processes are physically connected through the formation of a DNA-ribosome complex. As part of the efforts of Nirenbergs group to determine the genetic code that underlies protein synthesis, they pioneered the use of cell-free in vitro protein synthesis reactions. Analysis of these reactions revealed that protein synthesis is mRNA-dependent, and that the sequence of the mRNA strictly defines the sequence of the protein product. For this work in breaking in the genetic code, Nirenberg was jointly awarded the Nobel Prize in Physiology or Medicine in 1968. Having established that transcription and translation are linked biochemically (translation depends on the product of transcription), an outstanding question remained whether they were linked physically - whether the newly synthesized mRNA released from the DNA before it is translated, or if can translation occur concurrently with transcription. Electron micrographs of stained cell-free protein synthesis reactions revealed branched assemblies in which strings of ribosomes are linked to a central DNA fibre. DNA isolated from bacterial cells co-sediment with ribosomes, further supporting the conclusion that transcription and translation occur together. Direct contact between ribosomes and RNA polymerase are observable within these early micrographs. The potential for simultaneous regulation of transcription and translation at this junction was noted in Nirenbergs work as early as 1964. | 1 | Applied and Interdisciplinary Chemistry |
With primary amines, thionyl chloride gives sulfinylamine derivatives (RNSO), one example being N-sulfinylaniline. Thionyl chloride reacts with primary formamides to form isocyanides and with secondary formamides to give chloroiminium ions; as such a reaction with dimethylformamide will form the Vilsmeier reagent.
By an analogous process primary amides will react with thionyl chloride to form imidoyl chlorides, with secondary amides also giving chloroiminium ions. These species are highly reactive and can be used to catalyse the conversion of carboxylic acids to acyl chlorides, they are also exploited in the Bischler–Napieralski reaction as a means of forming isoquinolines.
Primary amides will continue on to form nitriles if heated (Von Braun amide degradation).
Thionyl chloride has also been used to promote the Beckmann rearrangement of oximes. | 0 | Theoretical and Fundamental Chemistry |
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