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Iodine-131 is used for unsealed source radiotherapy in nuclear medicine to treat several conditions. It can also be detected by gamma cameras for diagnostic imaging, however it is rarely administered for diagnostic purposes only, imaging will normally be done following a therapeutic dose. Use of the I as iodide salt exploits the mechanism of absorption of iodine by the normal cells of the thyroid gland. | 0 | Theoretical and Fundamental Chemistry |
Deposits are formed from either calcite or aragonite. Precipitation is brought about by degassing of CO, which decreases the solubility of calcite/aragonite. (See tufa/geochemistry) | 0 | Theoretical and Fundamental Chemistry |
Hydrazines and hydroxylamines displace carbonyl oxygens much more readily than amines. Their equilibria strongly favor the dehydrated product, and the carbonyl is recovered only with difficulty. | 0 | Theoretical and Fundamental Chemistry |
The synthesis of polycatenanes is considered a very challenging task. The formation of poly-[2]-catenanes can be achieved by polymerization of functionalized [2]-catenanes. Also the synthesis of [3]-catenanes, [5]-catenanes, [6]-catenanes and [7]-catenanes is reported in many articles. The synthesis of poly-[n]-catenanes has instead some practical issues. To this purpose, molecular dynamic simulation is very used as a tool for the design of the optimal synthetic path toward the desired product by predicting the final topology.
There are two main synthetic routes: the Statistical approach and the Template-Directed approach.
The statistical approach is based on a stochastic methodology. When the reactants are together, there is a probability that they will fit together first and then close on top of each other in a process of cyclization. The catenation of two rings into a catenane is already complex, thus, as expected, the interlocking of multiple cycles into a polycatenane is statistically improbable. Being an unfavored entropically process the product is obtained in very small amount. Also, the cyclization process requires high dilutions, but the elongation of the chain is favored at high concentrations, making the synthesis even more difficult.
The Template directed approach is based on the host-guest interactions that can direct the cyclization of pre-organized linear unit upon the existing macrocycle. These interactions can be hydrogen bonds, π-π interactions, hydrophobic interactions or metal ions coordinations. In this way the synthesis can be enthalpy-driven, obtaining quantitative results.
The yield and selectivity are restrained by the kinetic or thermodynamic control of the reaction.
Generally the kinetic control induces the formation of a product after short reaction times because it is favoued by irreversible reactions (or equilibrium reaction moved very much toward the formation of the products). The thermodynamic product is obtained for longer reaction times for reversible processes. In this case the units have the time to rearrange themselves toward the most stable state, in a sort of error-checking process. This is obtained by breaking covalent and coordination bonds and forming the most stable ones. | 0 | Theoretical and Fundamental Chemistry |
Algae grow much faster than food crops, and can produce hundreds of times more oil per unit area than conventional crops such as rapeseed, palms, soybeans, or jatropha. As algae have a harvesting cycle of 1–10 days, their cultivation permits several harvests in a very short time-frame, a strategy differing from that associated with annual crops. In addition, algae can be grown on land unsuitable for terrestrial crops, including arid land and land with excessively saline soil, minimizing competition with agriculture. Most research on algae cultivation has focused on growing algae in clean but expensive photobioreactors, or in open ponds, which are cheap to maintain but prone to contamination. | 1 | Applied and Interdisciplinary Chemistry |
Glyceraldehyde 3-phosphate occurs as a reactant in the biosynthesis pathway of thiamine (Vitamin B), another substance that cannot be produced by the human body. | 0 | Theoretical and Fundamental Chemistry |
Carnivory in plants has evolved at least six times independently, some examples include the Venus flytrap, pitcher plant, and butterwort. Although many outside of the scientific community usually believe these plants excel in defenses, many of these plants have evolved in poor nutrient soil. In order to get sufficient nutrients in these conditions they must use an alternative method. They use insects and small birds as a way to gain the minerals they need through carnivory. Carnivorous plants do not use carnivory as self-defense, but to get the nutrients they need. | 1 | Applied and Interdisciplinary Chemistry |
The ECPM participated to many different networks in order to communicate with factories, institutions or students.
That different networks are :
-The Gay-Lussac federation: The federation was found by Louis Joseph Gay Lussac. It regroups no more than 20 schools of chemistry and chemical engineering. These 20 schools, through their teaching activities, research and training, are working together to raise awareness, develop and promote engineering courses in chemistry.
-The network “Alsace Tech“: Alsace Tech regroups 12 reputed engineering, management and architecture schools of Alsace. Its main objective is to promote, to contribute to the national and international influence and to increase the legibility of its schools' members. | 1 | Applied and Interdisciplinary Chemistry |
There is an intimate connection of quantum thermodynamics with the theory of open quantum systems.
Quantum mechanics inserts dynamics into thermodynamics, giving a sound foundation to finite-time-thermodynamics.
The main assumption is that the entire world is a large closed system, and therefore, time evolution
is governed by a unitary transformation generated by a global Hamiltonian. For the combined system
bath scenario, the global Hamiltonian can be decomposed into:
where is the system Hamiltonian, is the bath Hamiltonian and is the system-bath interaction.
The state of the system is obtained from a partial trace over the combined system and bath:
Reduced dynamics is an equivalent description of the system dynamics utilizing only system operators.
Assuming Markov property for the dynamics the basic equation of motion for an open quantum system is the Lindblad equation (GKLS):
is a (Hermitian) Hamiltonian part and :
is the dissipative part describing implicitly through system operators the influence of the bath on the system.
The Markov property imposes
that the system and bath are uncorrelated at all times .
The L-GKS equation is unidirectional and leads any initial state to a steady state solution which is an invariant of the equation of motion .
The Heisenberg picture supplies a direct link to quantum thermodynamic observables. The dynamics of a system observable represented by the operator, , has the form:
where the possibility that the operator, is explicitly time-dependent, is included. | 0 | Theoretical and Fundamental Chemistry |
One mechanism proposed for the oxidation of adsorbed organics from solution is the production of hydroxyl radical by the valence holes migrating to the surface and reacting with adsorbed hydroxyl groups, resulting in a very strong oxidizing radical. Identification of hydroxylated oxidation intermediates and hydroxyl radicals supports this proposed mechanism, however this does not negate the possibility of the direct oxidation of the organic reactant by the valence holes because similar intermediates would be expected in either case. Some photo-oxidation reactions are shown below. | 0 | Theoretical and Fundamental Chemistry |
In the reaction between hydrogen and fluorine, hydrogen is being oxidized and fluorine is being reduced:
This reaction is spontaneous and releases 542 kJ per 2 g of hydrogen because the H-F bond is much stronger than the F-F bond. This reaction can be analyzed as two half-reactions. The oxidation reaction converts hydrogen to protons:
The reduction reaction converts fluorine to the fluoride anion:
The half reactions are combined so that the electrons cancel:
The protons and fluoride combine to form hydrogen fluoride in a non-redox reaction:
:2 H + 2 F → 2 HF
The overall reaction is: | 0 | Theoretical and Fundamental Chemistry |
* Chemical synthesis
* Enzyme-mediated exchange
* Recombinant protein expression in isotopic labeled media. | 0 | Theoretical and Fundamental Chemistry |
One may consider a system contained in a very tall adiabatically isolating vessel with rigid walls initially containing a thermally heterogeneous distribution of material, left for a long time under the influence of a steady gravitational field, along its tall dimension, due to an outside body such as the earth. It will settle to a state of uniform temperature throughout, though not of uniform pressure or density, and perhaps containing several phases. It is then in internal thermal equilibrium and even in thermodynamic equilibrium. This means that all local parts of the system are in mutual radiative exchange equilibrium. This means that the temperature of the system is spatially uniform. This is so in all cases, including those of non-uniform external force fields. For an externally imposed gravitational field, this may be proved in macroscopic thermodynamic terms, by the calculus of variations, using the method of Langrangian multipliers. Considerations of kinetic theory or statistical mechanics also support this statement. | 0 | Theoretical and Fundamental Chemistry |
A flange can also be a plate or ring to form a rim at the end of a pipe when fastened to the pipe (for example, a closet flange). A blind flange is a plate for covering or closing the end of a pipe. A flange joint is a connection of pipes, where the connecting pieces have flanges by which the parts are bolted together.
Although the word flange generally refers to the actual raised rim or lip of a fitting, many flanged plumbing fittings are themselves known as flanges.
Common flanges used in plumbing are the Surrey flange or Danzey flange, York flange, Sussex flange and Essex flange.
Surrey and York flanges fit to the top of the hot water tank allowing all the water to be taken without disturbance to the tank. They are often used to ensure an even flow of water to showers. An Essex flange requires a hole to be drilled in the side of the tank.
There is also a Warix flange which is the same as a York flange but the shower output is on the top of the flange and the vent on the side. The York and Warix flange have female adapters so that they fit onto a male tank, whereas the Surrey flange connects to a female tank.
A closet flange provides the mount for a toilet. | 1 | Applied and Interdisciplinary Chemistry |
In chemistry, a chemical trap is a chemical compound that is used to detect unstable compounds. The method relies on efficiency of bimolecular reactions with reagents to produce a more easily characterize trapped product. In some cases, the trapping agent is used in large excess. | 0 | Theoretical and Fundamental Chemistry |
Shihwa Bay is a costal resevior created in 1994 to supply surrounding agricultural lands with water, and act as a run-off lake for nearby industrial plants. The Bay was made without much enviornmental consideration, and by 1999, water quality had a significant drop. This drop in water quality is attributed to the bay not having enough circulation or new water flow to accomadate for the domestic and industrial waste being dumped. In response, the Korean government set up a pollution management system within the bay, and has a gate system that allows the Bay to mix with water in the sea. Shihwa Bay is also experiencing an imbalance of phosphorus to nitrogen, but also large sources of Ammonium. | 0 | Theoretical and Fundamental Chemistry |
There was no fundamental change in the technology of iron production in Europe for many centuries. European metal workers continued to produce iron in bloomeries. However, the Medieval period brought two developments—the use of water power in the bloomery process in various places (outlined above), and the first European production in cast iron. | 1 | Applied and Interdisciplinary Chemistry |
While the term pewter covers a range of tin-based alloys, the term English pewter has come to represent a strictly-controlled alloy, specified by BSEN611-1 and British Standard 5140, consisting mainly of tin (ideally 92%), with the balance made up of antimony and copper. Significantly, it is free of lead and nickel. Although the exact percentages vary between manufacturers, a typical standard for present-day pewter is approximately 91% tin, 7.5% antimony and 1.5% copper.
By the 15th century, the Worshipful Company of Pewterers controlled pewter constituents in England. This company originally had two grades of pewter, but in the 16th century a third grade was added. The first type, known as "fine metal", was used for tableware. It consisted of tin with as much copper as it could absorb, which is about 1%. The second type, known as "trifling metal" or "trifle", was used for holloware. It is made up of fine metal with approximately 4% lead. The last type of pewter, known as "lay" or "ley" metal, was used for items that were not in contact with food or drink. It consisted of tin with 15% lead. These three alloys were used, with little variation, until the 20th century.
Lead was removed from the composition in 1974, by BS5140, reinforced by the European directive BSEN611 in 1994.
Until the end of the 18th century, the only method of manufacture was by casting and the soldering of components. From the last quarter of the 18th century, improvement in alloys (e.g. britannia metal) and techniques allowed objects to be made from pewter by stamping and spinning. | 1 | Applied and Interdisciplinary Chemistry |
In an ideal continuous stirred-tank reactor (CSTR), the flow at the inlet is completely and instantly mixed into the bulk of the reactor. The reactor and the outlet fluid have identical, homogeneous compositions at all times. The residence time distribution is exponential:
Where; the mean is T and the variance is 1. A notable difference from the plug flow reactor is that material introduced into the system will never completely leave it.
In reality, it is impossible to obtain such rapid mixing, as there is necessarily a delay between any molecule passing through the inlet and making its way to the outlet, and hence the RTD of a real reactor will deviate from the ideal exponential decay, especially in the case of large reactors. For example, there will be some finite delay before E reaches its maximum value and the length of the delay will reflect the rate of mass transfer within the reactor. Just as was noted for a plug-flow reactor, an early mean will indicate some stagnant fluid within the vessel, while the presence of multiple peaks could indicate channeling, parallel paths to the exit, or strong internal circulation. Short-circuiting fluid within the reactor would appear in an RTD curve as a small pulse of concentrated tracer that reaches the outlet shortly after injection.
Reactants continuously enter and leave a tank where they are mixed. Consequently, the reaction proceeds at a rate dependent on the outlet concentration: | 0 | Theoretical and Fundamental Chemistry |
The following list provides information and external links to various programs and databases for inverted repeats:
*[https://web.archive.org/web/20131113054733/http://nonb.abcc.ncifcrf.gov/apps/site/default non-B DB] A Database for Integrated Annotations and Analysis of non-B DNA Forming Motifs. This database is provided by The Advanced Biomedical Computing Center (ABCC) at then Frederick National Laboratory for Cancer Research (FNLCR). It covers the A-DNA and Z-DNA conformations otherwise known as "non-B DNAs" because they are not the more common B-DNA form of a right-handed Watson-Crick double-helix. These "non-B DNAs" include left-handed Z-DNA, cruciform, triplex, tetraplex and hairpin structures. Searches can be performed on a variety of "repeat types" (including inverted repeats) and on several species.
*[http://tandem.bu.edu/cgi-bin/irdb/irdb.exe Inverted Repeats Database] Boston University. This database is a web application that allows query and analysis of repeats held in the PUBLIC DATABASE project. Scientists can also analyze their own sequences with the Inverted Repeats Finder algorithm.
*[http://pmite.hzau.edu.cn/django/mite/ P-MITE: a Plant MITE database] — this database for Miniature Inverted-repeat Transposable Elements (MITEs) contains sequences from plant genomes. Sequences may be searched or downloaded from the database.
*EMBOSS is the "European Molecular Biology Open Software Suite" which runs on UNIX and UNIX-like operating systems. Documentation and program source files are available on the [http://emboss.sourceforge.net/news/ EMBOSS website]. Applications specifically related to inverted repeats are listed below:
**[http://emboss.sourceforge.net/apps/cvs/emboss/apps/einverted.html EMBOSS einverted]: Finds inverted repeats in nucleotide sequences. Threshold values can be set to limit the scope of the search.
**[http://emboss.sourceforge.net/apps/cvs/emboss/apps/palindrome.html EMBOSS palindrome]: Finds palindromes such as stem loop regions in nucleotide sequences. The program will find sequences that include sections of mismatches and gaps that may correspond to bulges in a stem loop. | 1 | Applied and Interdisciplinary Chemistry |
The binding of CTCF has been shown to have many effects, which are enumerated below. In each case, it is unknown if CTCF directly evokes the outcome or if it does so indirectly (in particular through its looping role). | 1 | Applied and Interdisciplinary Chemistry |
A plastid is a membrane-bound organelle found in plants, algae and other eukaryotic organisms that contribute to the production of pigment molecules. Most plastids are photosynthetic, thus leading to color production and energy storage or production. There are many types of plastids in plants alone, but all plastids can be separated based on the number of times they have undergone endosymbiotic events. Currently there are three types of plastids; primary, secondary and tertiary. Endosymbiosis is reputed to have led to the evolution of eukaryotic organisms today, although the timeline is highly debated. | 0 | Theoretical and Fundamental Chemistry |
The magmas that produce ultrapotassic rocks are produced by a variety of mechanisms and from a variety of sources, but generally occur in a heterogenous, anomalous, phlogopite-bearing upper mantle.
The following conditions are favorable for the formation of ultrapotassic magmas.
* partial melting at a great depth
* low degrees of partial melting
* lithophile element (K, Ba, Cs, Rb) enrichment in sources
* enriched peridotite (variety harzburgite), especially in potassium
* pyroxene and phlogopite-rich volumes within the mantle, not from peridotite alone
* carbon dioxide or water (each condition leading to a distinctive magma);
* reaction of melts with surrounding rock as they rise from their sources
Mantle sources of ultrapotassic magmas may contain subducted sediments, or the sources may have been enriched in potassium by melts or fluids partly derived from subducted sediments. Phlogopite and/or potassic amphibole are typical in the sources from which many such magmas have been derived. Ultrapotassic granites are uncommon and may be produced by melting of the continental crust above upwelling mafic magma, such as at rift zones. | 0 | Theoretical and Fundamental Chemistry |
Some radioisotopes occur in nature with a half-life of less than 7 years (carbon-14: 5,730 ± 40 years, tritium: 12.32 years etc.). They are synthesised all the time by cosmic radiation. A practical use is radiocarbon dating with carbon-14. | 0 | Theoretical and Fundamental Chemistry |
"Thus, we have the ability to do away with oil (and other fossil fuels) but it will take 4–6 years and ca. $100–200M to build the full-scale plant and demonstrate it."
"Somebody will build it; and when it's built, it will work; and when it works people will begin to use it, and it will begin to displace all other forms of energy." | 0 | Theoretical and Fundamental Chemistry |
The Macromolecular Crystallographic Information File (mmCIF) also known as PDBx/mmCIF is a standard text file format for representing macromolecular structure data, developed by the International Union of Crystallography (IUCr) and the Protein Data Bank It is an extension of the Crystallographic Information File (CIF), specifically for macromolecular data, such as proteins and nucleic acids, incorporating elements from the PDB file format.
mmCIF is intended as an alternative to the Protein Data Bank (PDB) format and is now the default format used by the Protein Data Bank.
mmCIF was designed to address limitations of the PDB format in terms of capacity and flexibility, especially with the increasing size and complexity of macromolecular structures being determined.
The format is part of the larger Crystallographic Information Framework, a system of exchange protocols based on data dictionaries and relational rules expressible in different machine-readable manifestations, including, but not restricted to, the original Crystallographic Information File and XML. | 0 | Theoretical and Fundamental Chemistry |
Phosphorylated amino acids are crucial for the modulation of the binding of transcription factors and other gene regulatory proteins. Pin1s effect on isomerization of proline residues leads to an increase or decrease in recruitment of phosphatases, namely Scp1 and Ssu72 and their recruitment to the RNAP II CTD. The cis-Pro formation is associated with an increase in Ssu72. Scp1 on recognizes trans'-Pro formations, and is not affected by such isomerization. Pin1 also triggers the activation of the DSIF complex and NELF, which are responsible for pausing RNAP II in mammalian cells, and their conversion into positive elongation factors, facilitating elongation. This potentially could be an isomerization dependent process. | 0 | Theoretical and Fundamental Chemistry |
* Depurination is caused by hydrolysis and results in loss if the purine base of a nucleic acid. DNA is more prone to this, as the transition state in the depurination reaction has much greater energy in RNA.
* Tautomerization is a chemical reaction that is primarily relevant in the behavior of amino acids and nucleic acids. Both of which are correlated to DNA and RNA. The process of tautomerization of DNA bases occurs during DNA replication. The ability for the wrong tautomer of one of the standard nucleic bases to mispair causes a mutation during the process of DNA replication which can be cytotoxic or mutagenic to the cell. These mispairings can result in transition, transversion, frameshift, deletion, and/or duplication mutations. Some diseases that result from tautomerization induced DNA lesions include Kearns-Sayre syndrome, Fragile X syndrome, Kennedy disease, and Huntington's disease.
* Cytosine deamination commonly occurs under physiological conditions and essentially is the deamination of cytosine. This process yields uracil as its product, which is not a base pair found within DNA. This process causes extensive DNA damage. The rate of this process is slowed down significantly in double-stranded DNA compared to single-stranded DNA. | 1 | Applied and Interdisciplinary Chemistry |
N-tert-Butylbenzenesulfinimidoyl chloride is a useful oxidant for organic synthesis reactions. It is a good electrophile, and the sulfimide S=N bond can be attacked by nucleophiles, such as alkoxides, enolates, and amide ions. The nitrogen atom in the resulting intermediate is basic, and can abstract an α-hydrogen to create a new double bond. | 0 | Theoretical and Fundamental Chemistry |
The Crick, Brenner et al. experiment (1961) was a scientific experiment performed by Francis Crick, Sydney Brenner, Leslie Barnett and R.J. Watts-Tobin.
It was a key experiment in the development of what is now known as molecular biology and led to a publication entitled "The General Nature of the Genetic Code for Proteins" and according to the historian of Science Horace Judson is "regarded...as a classic of intellectual clarity, precision and rigour". This study demonstrated that the genetic code is made up of a series of three base pair codons which code for individual amino acids. The experiment also elucidated the nature of gene expression and frame-shift mutations. | 1 | Applied and Interdisciplinary Chemistry |
Reaction centers are present in all green plants, algae, and many bacteria. A variety in light-harvesting complexes exist across the photosynthetic species. Green plants and algae have two different types of reaction centers that are part of larger supercomplexes known as P700 in Photosystem I and P680 in Photosystem II. The structures of these supercomplexes are large, involving multiple light-harvesting complexes. The reaction center found in Rhodopseudomonas bacteria is currently best understood, since it was the first reaction center of known structure and has fewer polypeptide chains than the examples in green plants.
A reaction center is laid out in such a way that it captures the energy of a photon using pigment molecules and turns it into a usable form. Once the light energy has been absorbed directly by the pigment molecules, or passed to them by resonance transfer from a surrounding light-harvesting complex, they release electrons into an electron transport chain and pass energy to a hydrogen donor such as HO to extract electrons and protons from it. In green plants, the electron transport chain has many electron acceptors including pheophytin, quinone, plastoquinone, cytochrome bf, and ferredoxin, which result finally in the reduced molecule NADPH, while the energy used to split water results in the release of oxygen. The passage of the electron through the electron transport chain also results in the pumping of protons (hydrogen ions) from the chloroplast's stroma and into the lumen, resulting in a proton gradient across the thylakoid membrane that can be used to synthesize ATP using the ATP synthase molecule. Both the ATP and NADPH are used in the Calvin cycle to fix carbon dioxide into triose sugars. | 0 | Theoretical and Fundamental Chemistry |
: M–R + M–X → M–X + M–R.
In redox-transmetalation/ligand exchange the ligands of two metal complexes switch places with each other, bonding with the other metal center. The R ligand can be an alkyl, aryl, alkynyl, or allyl group and the X ligand can be a halogen, pseudo-halogen, alkyl, or aryl group. The reaction can proceed by two possible intermediate steps. The first is an associative intermediate, where the R and X ligands bridge the two metals, stabilizing the transition state. The second and less common intermediate is the formation of a cation where R is bridging the two metals and X is anionic. The RTLE reaction proceeds in a concerted manner. Like in RT reactions, the reaction is driven by electronegativity values. The X ligand is attracted to highly electropositive metals. If M is a more electropositive metal than M, it is thermodynamically favorable for the exchange of the R and X ligands to occur. | 0 | Theoretical and Fundamental Chemistry |
In addition to M–M single bonds, metal pairs can be linked by double, triple, quadruple, and in a few cases, quintuple bonds. Isolable complexes with multiple bonds are most common among the transition metals in the middle of the d-block, such as rhenium, tungsten, technetium, molybdenum and chromium. Typical the coligands are π-donors, not π-acceptors. Well studied examples are the tetraacetates, such as dimolybdenum tetraacetate (quadruple bond) and dirhodium tetraacetate (single bond). Mixed-valence druthenium tetraacetates have fractional M–M bond orders, i.e., 2.5 for [Ru(OAc)(HO)].
The complexes NbX(SR) adopt a face-sharing bioctahedral structures (X = Cl, Br; SR = thioether). As dimers of Nb(III), they feature double metal–metal bonds, the maximum possible for a pair of metals with d configuration.
Hexa(tert-butoxy)ditungsten(III) is a well studied example of a complex with a metal–metal triple bond. | 0 | Theoretical and Fundamental Chemistry |
One case study monitored the dehydrogenation of propane to propene using micro-GC. Reproducibility for the experiment was high. The study found that the catalyst (Cr/AlO) activity increased to a sustained maximum of 10% after 28 minutes — an industrially useful insight into the working stability of a catalyst. | 0 | Theoretical and Fundamental Chemistry |
Each nerve is composed of a bundle of axons. Each axon is surrounded by the endoneurium connective tissue layer. These axons are bundled into fascicles surrounded by the perineurium connective tissue layer. Multiple fascicles are then surrounded by the epineurium, which is the outermost connective tissue layer of the nerve. The axons of myelinated nerves have a myelin sheath made up of Schwann cells that coat the axon. | 1 | Applied and Interdisciplinary Chemistry |
Thomas James Marrow (born 23 November 1966) is a British scientist who is a professor of nuclear materials at the University of Oxford and holds the James Martin Chair in Energy Materials. He specialises in physical metallurgy, micromechanics, and X-ray crystallography of engineering materials, mainly ceramic matrix composite and nuclear graphite. | 1 | Applied and Interdisciplinary Chemistry |
Research into solar power for terrestrial applications became prominent with the U.S. National Science Foundation's Advanced Solar Energy Research and Development Division within the "Research Applied to National Needs" program, which ran from 1969 to 1977, and funded research on developing solar power for ground electrical power systems. A 1973 conference, the "Cherry Hill Conference", set forth the technology goals required to achieve this goal and outlined an ambitious project for achieving them, kicking off an applied research program that would be ongoing for several decades. The program was eventually taken over by the Energy Research and Development Administration (ERDA), which was later merged into the U.S. Department of Energy.
Following the 1973 oil crisis, oil companies used their higher profits to start (or buy) solar firms, and were for decades the largest producers. Exxon, ARCO, Shell, Amoco (later purchased by BP) and Mobil all had major solar divisions during the 1970s and 1980s. Technology companies also participated, including General Electric, Motorola, IBM, Tyco and RCA. | 0 | Theoretical and Fundamental Chemistry |
The complex analysis of the data measured with the TAS can be reduced to the solution of a linear problem:
d = Ri
given that it relates the measured data (d) with the feedings (i) from which the beta intensity distribution I can be obtained.
R is the response matrix of the detector (meaning the probability that a decay that feeds a certain level gives a count in certain bin of the spectrum). The function R depends on the detector but also of the particular level scheme that is being measured. To be able to extract the value of i from the data d the equation has to be inverted (this equation is also called the "inverse problem").
Unfortunately this can not be done easily because there is similar response to the feeding of adjacent levels when they are at high excitation energies where the level density is high. In other words, this is one of the so-called "ill-posed" problems, for which several sets of parameters can reproduce closely the same data set. Then, to find i, the response has to be obtained for which the branching ratios and a precise simulation of the geometry of the detector are needed. The higher the efficiency of the TAS used, the lower the dependence of the response on the branching ratios will be. Then it is possible to introduce the unknown branching ratios by hand from a plausible guess. A good guess can be calculated by means of the Statistical Model.
Then the procedure to find the feedings is iterative: using the expectation-maximization algorithm to solve the inverse problem, Then the procedure to find the feedings is iterative: using the expectation-maximization algorithm to solve the inverse problem, the feedings are extracted; if they don't reproduce the experimental data, it means that the initial guess of the branching ratios is wrong and has to be changed (of course, it is possible to play with other parameters of the analysis). Repeating this procedure iteratively in a reduced number of steps, the data is finally reproduced. | 0 | Theoretical and Fundamental Chemistry |
The Chen-Kao test is performed by creating an acidic solution of the compound to be tested and adding dilute Copper (II) Sulfate and Sodium hydroxide solutions.<br />The procedure is as follows:
#Place small amount of material to be tested on a spot plate.
#Add 2 drops of reagent A
#Add 2 drops of reagent B
#Add 2 drops of reagent C
#A violet color indicates presence of ephedrine or pseudoephedrine
*Reagent A - 1% (vol/vol) aqueous acetic acid solution
*Reagent B - dissolve 1g Copper(II) sulfate in 100ml water
*Reagent C - dissolve 8g of NaOH in 100ml of water (that is 2N NaOH solution)
Further, the coordination complex might be extracted with organic solvent like diethyl Ether or n-butanol (see Table II), as proposed in the literature, which provides additional confirmation of the original results, but no further differentiation. This modification is not included in the UN Precursor Test Kit and other spot tests alike. In order to further differentiate between ephedrine enantiomers - ephedrine, pseudoephedrine and other ephedrine-related compounds, Simon’s test (with acetaldehyde) and Simon’s test (with acetone) are used. (see Table III) | 0 | Theoretical and Fundamental Chemistry |
A large fraction of the I contained in spent fuel is released into the gas phase, when spent fuel is first chopped and then dissolved in boiling nitric acid during reprocessing. At least for civil reprocessing plants, special scrubbers are supposed to withhold 99.5% (or more) of the Iodine by adsorption, before exhaust air is released into the environment. However, the Northeastern Radiological Health Laboratory (NERHL) found, during their measurements at the first US civil reprocessing plant, which was operated by Nuclear Fuel Services, Inc. (NFS) in Western New York, that "between 5 and 10% of the total I available from the dissolved fuel" was released into the exhaust stack. They further wrote that "these values are greater than predicted output (Table 1). This was expected since the iodine scrubbers were not operating during the dissolution cycles monitored."
The Northeastern Radiological Health Laboratory further states that, due to limitations of their measuring systems, the actual release of I may have even been higher, "since [I] losses [by adsorption] probably occurred in the piping and ductwork between the stack and the sampler". Furthermore, the sample taking system used by the NERHL had a bubbler trap for measuring the tritium content of the gas samples before the iodine trap. The NERHL found out only after taking the samples that "the bubbler trap retained 60 to 90% of the I sampled". They concluded: "The bubblers located upstream of the ion exchangers removed a major portion of the gaseous I before it reached the ion exchange sampler. The iodine removal ability of the bubbler was anticipated, but not in the magnitude that it occurred." The documented release of "between 5 and 10% of the total I available from the dissolved fuel" is not corrected for those two measurement deficiencies.
Military isolation of plutonium from spent fuel has also released I to the atmosphere: "More than 685,000 curies of iodine 131 spewed from the stacks of Hanford's separation plants in the first three years of operation." As I and I have very similar physical and chemical properties, and no isotope separation was performed at Hanford, I must have also been released there in large quantities during the Manhattan project. As Hanford reprocessed "hot" fuel, that had been irradiated in a reactor only a few months earlier, the activity of the released short-lived I, with a half-life time of just 8 days, was much higher than that of the long-lived I. However, while all of the I released during the times of the Manhattan project has decayed by now, over 99.999% of the I is still in the environment.
Ice borehole data obtained from the university of Bern at the Fiescherhorn glacier in the Alpian mountains at a height of 3950 m show a somewhat steady increase in the I deposit rate (shown in the image as a solid line) with time. In particular, the highest values obtained in 1983 and 1984 are about six times as high as the maximum that was measured during the period of the atmospheric bomb testing in 1961. This strong increase following the conclusion of the atmospheric bomb testing indicates that nuclear fuel reprocessing has been the primary source of atmospheric iodine-129 since then. These measurements lasted until 1986. | 0 | Theoretical and Fundamental Chemistry |
In the U.S., standard methods have been established by the National Institute for Occupational Safety and Health (NIOSH) and another by U.S. OSHA. Each method uses a single component solvent; butanol and hexane cannot be sampled, however, on the same sample matrix using the NIOSH or OSHA method.
VOCs are quantified and identified by two broad techniques. The major technique is gas chromatography (GC). GC instruments allow the separation of gaseous components. When coupled to a flame ionization detector (FID) GCs can detect hydrocarbons at the parts per trillion levels. Using electron capture detectors, GCs are also effective for organohalide such as chlorocarbons.
The second major technique associated with VOC analysis is mass spectrometry, which is usually coupled with GC, giving the hyphenated technique of GC-MS.
Direct injection mass spectrometry techniques are frequently utilized for the rapid detection and accurate quantification of VOCs. PTR-MS is among the methods that have been used most extensively for the on-line analysis of biogenic and anthropogenic VOCs. PTR-MS instruments based on time-of-flight mass spectrometry have been reported to reach detection limits of 20 pptv after 100 ms and 750 ppqv after 1 min. measurement (signal integration) time. The mass resolution of these devices is between 7000 and 10,500 m/Δm, thus it is possible to separate most common isobaric VOCs and quantify them independently. | 0 | Theoretical and Fundamental Chemistry |
Cataracts are the primary cause of blindness in humans and mutations in one particular protein, γD-crystallin, have been linked to a number of congenital forms of this disease. An amino acid mutation, proline (P) to threonine (T) at position 23 of the polypeptide chain has been linked to at least four different forms of this ailment. SRCD investigations were conducted on the wild-type protein and two variants, the P23T mutant found in the disease, and a related modification, P23S (proline to serine, a chemically similar amino acid to threonine), to establish the nature of the cause of cataract formation. Two possible reasons were suggested as the causative factor; the reduced solubility of the mutant protein, or an instability in the structure of the protein being introduced by the mutation. Significantly, because the mutant had limited solubility, lab-based CD machines were only able to provide very noisy spectra and the data were uninterpretable as a result. However, the SRCD spectra produced had very low noise associated with their data, including the mutant, and showed clearly that the structures of the wild-type, the mutant, and the related protein all had very similar conformations. These data also established that the mutant retained stability to thermal denaturation, very similar to that of the wild-type protein. The data confirmed that the causative factor for the cataracts was the reduction in solubility associated with the P23T mutation and not changes in the stability of the protein.
Because of a high degree of flexibility, it had proven difficult to determine the structure of the extramembranous C-terminal domain of bacterial voltage-gated sodium channels. Using a series of synthesised channels where this C-terminal domain had been truncated, in some cases by a single amino acid difference between the constructs, the Wallace lab used SRCD to successfully identify the structure of this region. | 0 | Theoretical and Fundamental Chemistry |
A clinical trial produces data that could reveal quantitative differences between two or more interventions; statistical analyses are used to determine whether such differences are true, result from chance, or are the same as no treatment (placebo). Data from a clinical trial accumulate gradually over the trial duration, extending from months to years. Accordingly, results for participants recruited early in the study become available for analysis while subjects are still being assigned to treatment groups in the trial. Early analysis may allow the emerging evidence to assist decisions about whether to stop the study, or to reassign participants to the more successful segment of the trial. Investigators may also want to stop a trial when data analysis shows no treatment effect. | 1 | Applied and Interdisciplinary Chemistry |
A final component is an optional epoxy primer. Primers for heat-shrinkable sleeves work in the same manner as an FBE primer does when it is specified on 3-layer polyolefin pipeline coatings and is typically applied between 150 μm and 300 μm thick. Usually, the primer of heat shrinkable sleeve is two components non-solvent Epoxy, one is primer base and the other is curing agent. | 1 | Applied and Interdisciplinary Chemistry |
The sensitivity of NMR signal detection depends on the gyromagnetic ratio (γ) of the nucleus. In general, the signal intensity produced from a nucleus with a gyromagnetic ratio of γ is proportional to γ because the magnetic moment, the Boltzmann populations, and the nuclear precession frequency all increase in proportion to the gyromagnetic ratio γ. For example, the gyromagnetic ratio of C is 4 times lower than that of H, so the signal intensity it produces will be 64 times lower than one produced by a proton. However, since noise also increases as the square root of the frequency, the sensitivity is roughly proportional to γ. A C nucleus would be 32 times less sensitive than a proton, and N around 300 times less sensitive. Sensitivity enhancement techniques are therefore desirable when recording an NMR signal from an insensitive nucleus.
The sensitivity can be enhanced artificially by increasing the Boltzmann factors. One method may be through NOE; for example, for C signal, the signal-to-noise ratio can be improved three-fold when the attached protons are saturated. However, for NOE, a negative value of K, the ratio of gyromagnetic ratios of the nuclei, may result in a reduction in signal intensity. SinceN has a negative gyromagnetic ratio, the observed N signal can be near zero if the dipolar relaxation has to compete with other mechanisms. Alternative methods are therefore necessary for nuclei with a negative gyromagnetic ratio. One such method using the INEPT pulse sequence was proposed by Ray Freeman in 1979, which became widely adopted. | 0 | Theoretical and Fundamental Chemistry |
tert-butyllithium is a pyrophoric substance, meaning that it spontaneously ignites on exposure to air. Air-free techniques are important so as to prevent this compound from reacting violently with oxygen and moisture:
:t-BuLi + O → t-BuOOLi
:t-BuLi + HO → t-BuH + LiOH
The solvents used in common commercial preparations are themselves flammable. While it is possible to work with this compound using cannula transfer, traces of tert-butyllithium at the tip of the needle or cannula may ignite and clog the cannula with lithium salts. While some researchers take this "pilot light" effect as a sign that the product is "fresh" and has not degraded due to time or improper storage/handling, others prefer to enclose the needle tip or cannula in a short glass tube, which is flushed with an inert gas and sealed at each end with septa. Serious laboratory accidents involving tert-butyllithium have occurred. For example, in 2008 a staff research assistant, Sheharbano Sangji, in the lab of Patrick Harran at the University of California, Los Angeles, died after being severely burned by a fire ignited by tert-butyllithium.
Large-scale reactions may lead to runaway reactions, fires, and explosions when tert-butyllithium is mixed with ethers such as diethyl ether, and tetrahydrofuran. The use of hydrocarbon solvents may be preferred. | 0 | Theoretical and Fundamental Chemistry |
In metallurgy, solid solution strengthening is a type of alloying that can be used to improve the strength of a pure metal. The technique works by adding atoms of one element (the alloying element) to the crystalline lattice of another element (the base metal), forming a solid solution. The local nonuniformity in the lattice due to the alloying element makes plastic deformation more difficult by impeding dislocation motion through stress fields. In contrast, alloying beyond the solubility limit can form a second phase, leading to strengthening via other mechanisms (e.g. the precipitation of intermetallic compounds). | 1 | Applied and Interdisciplinary Chemistry |
The molecular organization of the nodes corresponds to their specialized function in impulse propagation. The level of sodium channels in the node versus the internode suggests that the number IMPs corresponds to sodium channels. Potassium channels are essentially absent in the nodal axolemma, whereas they are highly concentrated in the paranodal axolemma and Schwann cell membranes at the node. The exact function of potassium channels have not quite been revealed, but it is known that they may contribute to the rapid repolarization of the action potentials or play a vital role in buffering the potassium ions at the nodes. This highly asymmetric distribution of voltage-gated sodium and potassium channels is in striking contrast to their diffuse distribution in unmyelinated fibers.
The filamentous network subjacent to the nodal membrane contains cytoskeletal proteins called spectrin and ankyrin. The high density of ankyrin at the nodes may be functionally significant because several of the proteins that are populated at the nodes share the ability to bind to ankyrin with extremely high affinity. All of these proteins, including ankyrin, are enriched in the initial segment of axons which suggests a functional relationship. Now the relationship of these molecular components to the clustering of sodium channels at the nodes is still not known. Although some cell-adhesion molecules have been reported to be present at the nodes inconsistently; however, a variety of other molecules are known to be highly populated at the glial membranes of the paranodal regions where they contribute to its organization and structural integrity. | 1 | Applied and Interdisciplinary Chemistry |
This type of BCA assay includes a proprietary thiol covalent blocking "Compatibility Reagent" aka a Reducing Agent Compatibility Agent (RACA). Although this allows greater compatibility with reducing agents, the assay has a different interference profile from other non-protein components. | 1 | Applied and Interdisciplinary Chemistry |
In Gaunts and Yus works, some derivatives of drug molecules and biologically active compounds were successfully functionalized in their meta-position. For instance, meta-arylated derivatives of anti-inflammatory drugs (S)-ibruprofen and (S)-naproxen were synthesized with copper catalyzed C–H arylation. Meta-olefinated biologically important biphenyl, amino acid and Baclofen derivatives have been accessed by remote C–H activation assisted by the "end-on" template. These demonstrate the potential applications of meta-selective C–H functionalization in medicinal chemistry. | 0 | Theoretical and Fundamental Chemistry |
As metals only exist in solution as coordination complexes, it follows then that this class of compounds is useful in a wide variety of ways. | 0 | Theoretical and Fundamental Chemistry |
Recent studies focus on the integration of nanofluidic devices into microsystems. An interface should be created for the connection between two length-scales. A system with solely nanofluidic devices standalone is impractical because it would requires a large driving pressure to make fluids flow into the nano-channel.
Nanofluidic devices are powerful in their high sensitivity and accurate manipulation of sample materials even down to a single molecule. Nevertheless, the drawback of nanofuidic separation systems is the relatively low sample throughput and its result in detection. One possible approach to deal with the problem is to use parallel separation channels with parallel detection in each channel. In addition, a better approach for detection needs to be created in view of the very small quantities of molecules present.
One of the biggest challenges in this research area are due to the peculiar size-effect. Researchers try to solve the problems caused by the extremely high surface-to-volume ratios. Under this condition, adsorption of molecules can lead to large losses and can also change the surface properties.
Another issue arises when the sample for detection is a relatively large molecule, such as DNA or protein. In the application for large molecule, clogging is a concern because the small size of the nanochannel makes it easy to happen. A low friction coating at inner surface of the channel is desired to avoid blocking of fluid channels in this application. | 0 | Theoretical and Fundamental Chemistry |
Acylsilanes can be synthesized by treating acyl anion equivalents with silyl halides (typically trimethylsilyl chloride, tmsCl). Silylation of 2-lithio-1,3-dithiane, followed by hydrolysis of the dithioacetal group with mercury(II) chloride. Analogous methods has also been used to produce acylgermanes.
Several approches to acylsilanes start with carboxylic acid derivatives. Esters undergo reductive silylation en route to acylsilanes:
Tertiary amides react with silyl lithium reagents:
Acid chlorides are converted using hexamethyldisilane:
Some acyl silanes are prepared by oxidation of a suitable silanes. | 0 | Theoretical and Fundamental Chemistry |
Hydrogen lowers tensile ductility in many materials. In ductile materials, like austenitic stainless steels and aluminium alloys, no marked embrittlement may occur, but may exhibit significant lowering in tensile ductility (% elongation or % reduction in area) in tensile tests. | 1 | Applied and Interdisciplinary Chemistry |
There are a very large number of petrochemicals produced from the BTX aromatics. The following diagram shows the chains leading from the BTX components to some of the petrochemicals that can be produced from those components: | 0 | Theoretical and Fundamental Chemistry |
Under ideal conditions, implants should initiate the desired host response. Ideally, the implant should not cause any undesired reaction from neighboring or distant tissues. However, the interaction between the implant and the tissue surrounding the implant can lead to complications. The process of implantation of medical devices is subjected to the same complications that other invasive medical procedures can have during or after surgery. Common complications include infection, inflammation, and pain. Other complications that can occur include risk of rejection from implant-induced coagulation and allergic foreign body response. Depending on the type of implant, the complications may vary.
When the site of an implant becomes infected during or after surgery, the surrounding tissue becomes infected by microorganisms. Three main categories of infection can occur after operation. Superficial immediate infections are caused by organisms that commonly grow near or on skin. The infection usually occurs at the surgical opening. Deep immediate infection, the second type, occurs immediately after surgery at the site of the implant. Skin-dwelling and airborne bacteria cause deep immediate infection. These bacteria enter the body by attaching to the implant's surface prior to implantation. Though not common, deep immediate infections can also occur from dormant bacteria from previous infections of the tissue at the implantation site that have been activated from being disturbed during the surgery. The last type, late infection, occurs months to years after the implantation of the implant. Late infections are caused by dormant blood-borne bacteria attached to the implant prior to implantation. The blood-borne bacteria colonize on the implant and eventually get released from it. Depending on the type of material used to make the implant, it may be infused with antibiotics to lower the risk of infections during surgery. However, only certain types of materials can be infused with antibiotics, the use of antibiotic-infused implants runs the risk of rejection by the patient since the patient may develop a sensitivity to the antibiotic, and the antibiotic may not work on the bacteria.
Inflammation, a common occurrence after any surgical procedure, is the body's response to tissue damage as a result of trauma, infection, intrusion of foreign materials, or local cell death, or as a part of an immune response. Inflammation starts with the rapid dilation of local capillaries to supply the local tissue with blood. The inflow of blood causes the tissue to become swollen and may cause cell death. The excess blood, or edema, can activate pain receptors at the tissue. The site of the inflammation becomes warm from local disturbances of fluid flow and the increased cellular activity to repair the tissue or remove debris from the site.
Implant-induced coagulation is similar to the coagulation process done within the body to prevent blood loss from damaged blood vessels. However, the coagulation process is triggered from proteins that become attached to the implant surface and lose their shapes. When this occurs, the protein changes conformation and different activation sites become exposed, which may trigger an immune system response where the body attempts to attack the implant to remove the foreign material. The trigger of the immune system response can be accompanied by inflammation. The immune system response may lead to chronic inflammation where the implant is rejected and has to be removed from the body. The immune system may encapsulate the implant as an attempt to remove the foreign material from the site of the tissue by encapsulating the implant in fibrinogen and platelets. The encapsulation of the implant can lead to further complications, since the thick layers of fibrous encapsulation may prevent the implant from performing the desired functions. Bacteria may attack the fibrous encapsulation and become embedded into the fibers. Since the layers of fibers are thick, antibiotics may not be able to reach the bacteria and the bacteria may grow and infect the surrounding tissue. In order to remove the bacteria, the implant would have to be removed. Lastly, the immune system may accept the presence of the implant and repair and remodel the surrounding tissue. Similar responses occur when the body initiates an allergic foreign body response. In the case of an allergic foreign body response, the implant would have to be removed. | 1 | Applied and Interdisciplinary Chemistry |
Reflection high-energy electron diffraction (RHEED) is a technique used to characterize the surface of crystalline materials. RHEED systems gather information only from the surface layer of the sample, which distinguishes RHEED from other materials characterization methods that also rely on diffraction of high-energy electrons. Transmission electron microscopy, another common electron diffraction method samples mainly the bulk of the sample due to the geometry of the system, although in special cases it can provide surface information. Low-energy electron diffraction (LEED) is also surface sensitive, but LEED achieves surface sensitivity through the use of low energy electrons. | 0 | Theoretical and Fundamental Chemistry |
The properties are similar to those of rock-based geopolymer cement but involve geological elements with high iron oxide content. The geopolymeric make up is of the type (Ca,K)-(Fe-O)-(Si-O-Al-O). This user-friendly geopolymer cement is in the development and commercialization phase. | 0 | Theoretical and Fundamental Chemistry |
Josef Fried was born in the town of Przemyśl, Poland, on July 21, 1914.
Fried received his Ph.D. in organic chemistry from Columbia University in 1940.
Fried joined the Squibb Institute in 1944 as a head of its antibiotics and steroids department. He was later promoted to director of the organic chemistry section in 1959.
In 1963 Fried was appointed professor at the Ben May Laboratory for Cancer Research at the University of Chicago. | 0 | Theoretical and Fundamental Chemistry |
Soil pH affects the availability of some plant nutrients:
As discussed above, aluminium toxicity has direct effects on plant growth; however, by limiting root growth, it also reduces the availability of plant nutrients. Because roots are damaged, nutrient uptake is reduced, and deficiencies of the macronutrients (nitrogen, phosphorus, potassium, calcium and magnesium) are frequently encountered in very strongly acidic to ultra-acidic soils (pH<5.0). When aluminum levels increase in the soil, it decreases the pH levels. This does not allow for trees to take up water, meaning they cannot photosynthesize, leading them to die. The trees can also develop yellowish colour on their leaves and veins.
Molybdenum availability is increased at higher pH; this is because the molybdate ion is more strongly sorbed by clay particles at lower pH.
Zinc, iron, copper and manganese show decreased availability at higher pH (increased sorption at higher pH).
The effect of pH on phosphorus availability varies considerably, depending on soil conditions and the crop in question. The prevailing view in the 1940s and 1950s was that P availability was maximized near neutrality (soil pH 6.5–7.5), and decreased at higher and lower pH. Interactions of phosphorus with pH in the moderately to slightly acidic range (pH 5.5–6.5) are, however, far more complex than is suggested by this view. Laboratory tests, glasshouse trials and field trials have indicated that increases in pH within this range may increase, decrease, or have no effect on P availability to plants. | 0 | Theoretical and Fundamental Chemistry |
The term "autoinduction" was first coined in 1970, when it was observed that the bioluminescent marine bacterium Vibrio fischeri produced a luminescent enzyme (luciferase) only when cultures had reached a threshold population density. At low cell concentrations, V. fischeri did not express the luciferase gene. However, once the cultures had reached exponential growth phase, the luciferase gene was rapidly activated. This phenomenon was termed “autoinduction” because it involved a molecule (autoinducer) that accumulated in a growth medium and induced the synthesis of components of the luminescence system. Subsequent research revealed that the actual autoinducer used by V. fischeri is an acylated homoserine lactone (AHL) signaling molecule. | 1 | Applied and Interdisciplinary Chemistry |
BREEAM is used in more than 70 countries, with several in Europe having gone a stage further to develop country-specific BREEAM schemes operated by National Scheme Operators (NSOs). There are currently NSOs affiliated to BREEAM in:
* Netherlands: the Dutch Green Building Council operates BREEAM NL
* Spain: the Instituto Tecnológico de Galicia operates BREEAM ES
* Norway: the Norwegian Green Building Council operates BREEAM NOR
* Sweden: the Swedish Green Building Council operates BREEAM SE
* Germany: the German Institute for Sustainable Real Estate (DIFNI) operates BREEAM DE.
Schemes developed by NSOs can take any format as long as they comply with a set of overarching requirements laid down in the Code for a Sustainable Built Environment. They can be produced from scratch by adapting current BREEAM schemes to the local context, or by developing existing local schemes. | 1 | Applied and Interdisciplinary Chemistry |
The property of photoconversion in Kaede is contributed by the tripeptide, His-Tyr-Gly, that acts as a green chromophore that can be converted to red. Once Kaede is synthesized, a chromophore, 4-(p-hydroxybenzylidene)-5-imidazolinone, derived from the tripeptide mediates green fluorescence in Kaede. When exposed to UV, Kaede protein undergoes unconventional cleavage between the amide nitrogen and the α carbon (Cα) at His62 via a formal β-elimination reaction. Followed by the formation of a double bond between His62-Cα and –Cβ, the π-conjugation is extended to the imidazole ring of His62. A new chromophore, 2-[(1E)-2-(5-imidazolyl)ethenyl]-4-(p-hydroxybenzylidene)-5-imidazolinone, is formed with the red-emitting property.
The cleavage of the tripeptide was analysed by SDS-PAGE analysis. Unconverted green Kaede shows one band at 28 kDa, whereas two bands at 18 kDa and 10 kDa are observed for converted red Kaede, indicating that the cleavage is crucial for the photoconversion.
A shifting of the absorption and emission spectrum in Kaede is caused by the cleavage of the tripeptide. Before the photoconversion, Kaede displays a major absorption wavelength maximum at 508 nm, accompanied with a slight shoulder at 475 nm. When it is excited at 480 nm, green fluorescence is emitted with a peak of 518 nm.
When Kaede is irradiated with UV or violet light, the major absorption peak shifts to 572 nm. When excited at 540 nm, Kaede showed an emission maximum at 582 nm with a shoulder at 627 nm and the 518-nm peak. Red fluorescence is emitted after this photoconversion.
The photoconversion in Kaede is irreversible. Exposure in dark or illumination at 570 nm cannot restore its original green fluorescence. A reduced fluorescence is observed in red, photoconverted Kaede when it is intensively exposed to 405 nm light, followed by partial recover after several minutes. | 1 | Applied and Interdisciplinary Chemistry |
The Warburg diffusion element () is a constant phase element (CPE), with a constant phase of 45° (phase independent of frequency) and with a magnitude inversely proportional to the square root of the frequency by:
where
* is the Warburg coefficient (or Warburg constant);
* is the imaginary unit;
* is the angular frequency.
This equation assumes semi-infinite linear diffusion, that is, unrestricted diffusion to a large planar electrode. | 0 | Theoretical and Fundamental Chemistry |
Partial agonists are defined as drugs that, at a given receptor, might differ in the amplitude of the functional response that they elicit after maximal receptor occupancy. Although they are agonists, partial agonists can act as a competitive antagonist in the presence of a full agonist, as it competes with the full agonist for receptor occupancy, thereby producing a net decrease in the receptor activation as compared to that observed with the full agonist alone. Clinically, their usefulness is derived from their ability to enhance deficient systems while simultaneously blocking excessive activity. Exposing a receptor to a high level of a partial agonist will ensure that it has a constant, weak level of activity, whether its normal agonist is present at high or low levels. In addition, it has been suggested that partial agonism prevents the adaptive regulatory mechanisms that frequently develop after repeated exposure to potent full agonists or antagonists. E.g. Buprenorphine, a partial agonist of the μ-opioid receptor, binds with weak morphine-like activity and is used clinically as an analgesic in pain management and as an alternative to methadone in the treatment of opioid dependence. | 1 | Applied and Interdisciplinary Chemistry |
Glucose is an energy source in most life forms. For instance, polysaccharides are broken down into their monomers by enzymes (glycogen phosphorylase removes glucose residues from glycogen, a polysaccharide). Disaccharides like lactose or sucrose are cleaved into their two component monosaccharides. | 1 | Applied and Interdisciplinary Chemistry |
Base degradation of ortho carborane gives the anionic 11-vertex derivative, precursor to dicarbollide complexes:
:CBH + NaOEt + 2 EtOH → NaCBH + H + B(OEt)
:NaCBH + NaH → NaCBH + H
Dicarbollides (CBH) function as ligands for transition metals and f-elements. The dianion forms sandwich compounds, bis(dicarbollides). Dicarbollides, being strong electron donors, stabilize higher oxidation states, e.g. Ni(IV). | 0 | Theoretical and Fundamental Chemistry |
Radical cyclization reactions produce mono- or polycyclic products through the action of radical intermediates. Because they are intramolecular transformations, they are often very rapid and selective. Selective radical generation can be achieved at carbons bound to a variety of functional groups, and reagents used to effect radical generation are numerous. The radical cyclization step usually involves the attack of a radical on a multiple bond. After this step occurs, the resulting cyclized radicals are quenched through the action of a radical scavenger, a fragmentation process, or an electron-transfer reaction. Five- and six-membered rings are the most common products; formation of smaller and larger rings is rarely observed.
Three conditions must be met for an efficient radical cyclization to take place:
* A method must be available to generate a radical selectively on the substrate.
* Radical cyclization must be faster than trapping of the initially formed radical.
* All steps must be faster than undesired side reactions such as radical recombination or reaction with solvent.
Advantages: because radical intermediates are not charged species, reaction conditions are often mild and functional group tolerance is high and orthogonal to that of many polar processes. Reactions can be carried out in a variety of solvents (including arenes, alcohols, and water), as long as the solvent does not have a weak bond that can undergo abstraction, and products are often synthetically useful compounds that can be carried on using existing functionality or groups introduced during radical trapping.
Disadvantages: the relative rates of the various stages of radical cyclization reactions (and any side reactions) must be carefully controlled so that cyclization and trapping of the cyclized radical is favored. Side reactions are sometimes a problem, and cyclization is especially slow for small and large rings (although macrocyclizations, which resemble intermolecular radical reactions, are often high yielding). | 0 | Theoretical and Fundamental Chemistry |
Bacteriorhodopsin (Bop) is a protein used by Archaea, most notably by haloarchaea, a class of the Euryarchaeota. It acts as a proton pump; that is, it captures light energy and uses it to move protons across the membrane out of the cell. The resulting proton gradient is subsequently converted into chemical energy. | 0 | Theoretical and Fundamental Chemistry |
Mono(ADP-ribosyl)transferases commonly catalyze the addition of ADP-ribose to arginine side chains using a highly conserved R-S-EXE motif of the enzyme. The reaction proceeds by breaking the bond between nicotinamide and ribose to form an oxonium ion. Next, the arginine side chain of the target protein then acts a nucleophile, attacking the electrophilic carbon adjacent to the oxonium ion. In order for this step to occur, the arginine nucleophile is deprotonated by a glutamate residue on the catalyzing enzyme. Another conserved glutamate residue forms a hydrogen bond with one of the hydroxyl groups on the ribose chain to further facilitate this nucleophilic attack. As a result of the cleavage reaction, nicotinamide is released. The modification can be reversed by (ADP-ribosyl)hydrolases, which cleave the N-glycosidic bond between arginine and ribose to release ADP-ribose and unmodified protein; NAD is not restored by the reverse reaction. | 1 | Applied and Interdisciplinary Chemistry |
Alpha-oxidation of phytanic acid is believed to take place entirely within peroxisomes.
#Phytanic acid is first attached to CoA to form phytanoyl-CoA.
#Phytanoyl-CoA is oxidized by phytanoyl-CoA dioxygenase, in a process using Fe and O, to yield 2-hydroxyphytanoyl-CoA.
#2-hydroxyphytanoyl-CoA is cleaved by 2-hydroxyphytanoyl-CoA lyase in a TPP-dependent reaction to form pristanal and formyl-CoA (in turn later broken down into formate and eventually CO).
#Pristanal is oxidized by aldehyde dehydrogenase to form pristanic acid (which can then undergo beta-oxidation).
(Propionyl-CoA is released as a result of beta oxidation when the beta carbon is substituted) | 1 | Applied and Interdisciplinary Chemistry |
Many natural products have very complex structures. The perceived complexity of a natural product is a qualitative matter, consisting of consideration of its molecular mass, the particular arrangements of substructures (functional groups, rings etc.) with respect to one another, the number and density of those functional groups, the stability of those groups and of the molecule as a whole, the number and type of stereochemical elements, the physical properties of the molecule and its intermediates (which bear on the ease of its handling and purification), all of these viewed in the context of the novelty of the structure and whether preceding related synthetic efforts have been successful (see below for details).
Some natural products, especially those less complex, are easily and cost-effectively prepared via complete chemical synthesis from readily available, simpler chemical ingredients, a process referred to as total synthesis (especially when the process involves no steps mediated by biological agents). Not all natural products are amenable to total synthesis, cost-effective or otherwise. In particular, those most complex often are not. Many are accessible, but the required routes are simply too expensive to allow synthesis on any practical or industrial scale. However, to be available for further study, all natural products must yield to isolation and purification. This may suffice if isolation provides appropriate quantities of the natural product for the intended purpose (e.g. as a drug to alleviate disease). Drugs such as penicillin, morphine, and paclitaxel proved to be affordably acquired at needed commercial scales solely via isolation procedures (without any significant synthetic chemistry contributing). However, in other cases, needed agents are not available without synthetic chemistry manipulations. | 1 | Applied and Interdisciplinary Chemistry |
* Worldwide: alcohol (beer, wine), vinegar, olives, yogurt, bread, cheese
* Asia
** East and Southeast Asia: amazake, atchara, belacan, burong mangga, com ruou, doenjang, douchi, fish sauce, lah pet, lambanog, kimchi, kombucha, leppet-so, narezushi, miso, nata de coco, nattō, ngapi, oncom, padaek, pla ra, prahok, ruou nep, sake, shrimp paste, soju, soy sauce, stinky tofu, tape, tempeh, zha cai
** Central Asia: kumis, kefir, shubat, qatiq (yogurt)
** South Asia: achar, appam, dosa, dhokla, dahi (yogurt), idli, mixed pickle, ngari, sinki, tongba, paneer
* Africa: garri, injera, laxoox, mageu, ogi, ogiri, iru
* Americas: chicha, chocolate, vanilla, hot sauce, tibicos, pulque, muktuk, kiviak , parakari
* Middle East: torshi, boza
* Europe: sourdough bread, elderberry wine, kombucha, pickling, rakfisk, sauerkraut, pickled cucumber, surströmming, mead, kvass, salami, sucuk, prosciutto, cultured milk products such as quark, kefir, filmjölk, crème fraîche, smetana, skyr, rakı, tupí, żur.
* Oceania: poi, kānga pirau | 1 | Applied and Interdisciplinary Chemistry |
Dehydrogenation of amine-boranes is thermodynamically favourable, making the process attractive for hydrogen storage systems. Ammonia borane has attracted particular interest due to its high weight percent of hydrogen (19.6%). Dehydrogenation occurs in three steps, creating polyamino-boranes and borazines as insoluble side products. The dehydrogenation reactions are irreversible, which limits the utility of this process for hydrogen storage. | 0 | Theoretical and Fundamental Chemistry |
Any compound with a log Kow of less than or equal to 3 can concentrate in a POCIS sampler. Applicable classes of contaminants measured by POCIS are pharmaceuticals, household and industrial products, hormones, herbicides, and polar pesticides (Table 1). Currently, there are two POCIS configurations that are targeted for different classes of contaminants. A general POCIS design contains a sorbent that is used to collect pesticides, natural as well as synthetic hormones, and wastewater related chemicals. The pharmaceutical POCIS configuration contains a sorbent that is designed to specifically target classes of pharmaceuticals.
::Applicable contaminants that concentrate in a POCIS device. Not to be considered a complete list. | 0 | Theoretical and Fundamental Chemistry |
In his 1803 publication about the quantity of gases absorbed by water, William Henry described the results of his experiments:
Charles Coulston Gillispie states that John Dalton "supposed that the separation of gas particles one from another in the vapor phase bears the ratio of a small whole number to their interatomic distance in solution. Henry's law follows as a consequence if this ratio is a constant for each gas at a given temperature." | 0 | Theoretical and Fundamental Chemistry |
In coordination chemistry and crystallography, the geometry index or structural parameter () is a number ranging from 0 to 1 that indicates what the geometry of the coordination center is. The first such parameter for 5-coordinate compounds was developed in 1984. Later, parameters for 4-coordinate compounds were developed. | 0 | Theoretical and Fundamental Chemistry |
Derived from “the addition of a hydrophilic heterocyclic group to the α-amino group of ampicillin”, the structure consists of a thiazolidine ring conjoined to a β-lactam ring contained within several ring compounds. The addition of this substituent increases the compounds affinity to penicillin-binding protein PBP-3, improving activity against Gram-negative bacteria, and thus broadening its spectrum of activity. Susceptible β-lactamase producing bacteria such as Staphylococcus spp. or Haemophilus influenzae', the combination of tazobactam (which shares a similar structure to sulbactam, another β-lactamase inhibitor), and piperacillin significantly improves the stability of the drug against β-lactamases. | 0 | Theoretical and Fundamental Chemistry |
Reversed phase SPE separates analytes based on their polarity. The stationary phase of a reversed phase SPE cartridge is derivatized with hydrocarbon chains, which retain compounds of mid to low polarity due to the hydrophobic effect. The analyte can be eluted by washing the cartridge with a non-polar solvent, which disrupts the interaction of the analyte and the stationary phase.
A stationary phase of silicon with carbon chains is commonly used. Relying on mainly non-polar, hydrophobic interactions, only non-polar or very weakly polar compounds will adsorb to the surface. | 0 | Theoretical and Fundamental Chemistry |
There are several ways of measuring fluxes, however all of these are indirect. Due to this, these methods make one key assumption which is that all fluxes into a given intracellular metabolite pool balance all the fluxes out of the pool.
This assumption means that for a given metabolic network the balances around each metabolite impose a number of constraints on the system.
The techniques currently used mainly revolve around the use of either nuclear magnetic resonance (NMR) or gas chromatography–mass spectrometry (GC–MS).
In order to avoid the complexity of data analysis, a simpler method of estimating flux ratios has recently been developed which is based on cofeeding unlabelled and uniformly C labelled glucose. The metabolic intermediate patterns are then analysed using NMR spectroscopy.
This method can also be used to determine the metabolic network topologies. | 1 | Applied and Interdisciplinary Chemistry |
One disadvantage of alkaline water electrolyzers is the low-performance profiles caused by the commonly-used thick diaphragms that increase ohmic resistance, the lower intrinsic conductivity of OH− compared to H+, and the higher gas crossover observed for highly porous diaphragms. | 0 | Theoretical and Fundamental Chemistry |
The characteristics capable of supporting Type 1 pits were determined empirically by Lucey after examining the compositions of waters in which the pitting behaviour was known. They should be cold, less than 30°C, hard or moderately hard, 170 to 300 mg/L carbonate hardness, and organically pure. Organically pure waters usually originate from deep wells, or boreholes. Surface waters from rivers or lakes contain naturally occurring organic compounds that inhibit the formation of Type 1 pits, unless a deflocculation treatment has been carried out that removes organic material. Type 1 pitting is relatively uncommon in North America and this may be a result of the lower population density allowing a significant proportion of the potable water to be obtained from surface derived sources. In addition to being cold hard and organically pure, the water needs a specific chemistry. The effect of the water chemistry can be empirically determined though use of the Pitting Propensity Rating (PPR) a number that takes into account the sulfate, chloride, nitrate and sodium ion concentrations of the water as well as its acidity or pH. A water with a positive PPR has been shown to be capable of propagating Type 1 pits. | 1 | Applied and Interdisciplinary Chemistry |
To find the shape of the minimal surface bounded by some arbitrary shaped frame using strictly mathematical means can be a daunting task. Yet by fashioning the frame out of wire and dipping it in soap-solution, a locally minimal surface will appear in the resulting soap-film within seconds.
The reason for this is that the pressure difference across a fluid interface is proportional to the mean curvature, as seen in the Young–Laplace equation. For an open soap film, the pressure difference is zero, hence the mean curvature is zero, and minimal surfaces have the property of zero mean curvature. | 0 | Theoretical and Fundamental Chemistry |
The first representative of the TAP family was prepared by Kobayashi and co-workers, using high-temperature template condensation method, which resembles the classical procedures of phthalocyanine synthesis. Melting of anthracene-2,3-
dicarboxyimide with sodium biphenylacetate in the presence of zinc acetate resulted in the formation of zinc complex of triarylsubstituted TAP. The synthesis of both meso-unsubstituted and meso-arylsubstituted TAPs was reported by Ono and coworkers using a common approach to extended porphyrins relying on thermal retro-Diels−Alder extrusion of ethylene
from bicyclo[2.2.2]octadiene-annelated porphyrins. Thus obtained materials were reported to be poorly soluble and unstable toward photooxidation.
An obvious drawback of reported syntheses of TAPs is a need for harsh conditions of condensation or aromatization steps, which are poorly compatible with the emerging huge and fragile TAP system. This results in low yields and poor quality of the obtained materials and limits opportunities of introducing functionality to improve solubility and stability or to modulate optical properties.
As an advanced method delivering tetraanthraporphyrins, the dihydroisoindole method based on an oxidative aromatization of the closest partially hydrogenated porphyrin precursor was applied. It warrants that the conditions of aromatization of
the annelated system are as soft as possible and occur spontaneously along with the aromatization of the porphyrinogen
intermediates | 1 | Applied and Interdisciplinary Chemistry |
The Combined gas law or General Gas Equation is obtained by combining Boyles Law, Charless law, and Gay-Lussac's Law. It shows the relationship between the pressure, volume, and temperature for a fixed mass of gas:
This can also be written as:
With the addition of Avogadro's law, the combined gas law develops into the ideal gas law:
:where P is the pressure, V is volume, n is the number of moles, R is the universal gas constant and T is the absolute temperature.
:The proportionality constant, now named R, is the universal gas constant with a value of 8.3144598 (kPa∙L)/(mol∙K).
An equivalent formulation of this law is:
:where P is the pressure, V is the volume, N is the number of gas molecules, k is the Boltzmann constant (1.381×10J·K in SI units) and T is the absolute temperature.
These equations are exact only for an ideal gas, which neglects various intermolecular effects (see real gas). However, the ideal gas law is a good approximation for most gases under moderate pressure and temperature.
This law has the following important consequences:
# If temperature and pressure are kept constant, then the volume of the gas is directly proportional to the number of molecules of gas.
# If the temperature and volume remain constant, then the pressure of the gas changes is directly proportional to the number of molecules of gas present.
# If the number of gas molecules and the temperature remain constant, then the pressure is inversely proportional to the volume.
# If the temperature changes and the number of gas molecules are kept constant, then either pressure or volume (or both) will change in direct proportion to the temperature. | 0 | Theoretical and Fundamental Chemistry |
Radionuclides are present in many homes as they are used inside the most common household smoke detectors. The radionuclide used is americium-241, which is created by bombarding plutonium with neutrons in a nuclear reactor. It decays by emitting alpha particles and gamma radiation to become neptunium-237. Smoke detectors use a very small quantity of Am (about 0.29 micrograms per smoke detector) in the form of americium dioxide. Am is used as it emits alpha particles which ionize the air in the detectors ionization chamber. A small electric voltage is applied to the ionized air which gives rise to a small electric current. In the presence of smoke, some of the ions are neutralized, thereby decreasing the current, which activates the detectors alarm. | 0 | Theoretical and Fundamental Chemistry |
Schuster married his wife Carlotta, a psychiatrist, in 1962. He is a lifelong classical music enthusiast and serious pianist. | 0 | Theoretical and Fundamental Chemistry |
Much of the work of installing a piping or plumbing system involves making leakproof, reliable connections, and most piping requires mechanical support against gravity and other forces (such as wind loads and earthquakes) which might disrupt an installation. Depending on the connection technology and application, basic skills may be sufficient, or specialized skills and professional licensure may be legally required. | 1 | Applied and Interdisciplinary Chemistry |
In fluid dynamics and elasticity, hydroelasticity or flexible fluid-structure interaction (FSI), is a branch of science which is concerned with the motion of deformable bodies through liquids. The theory of hydroelasticity has been adapted from aeroelasticity, to describe the effect of structural response of the body on the fluid around it. | 1 | Applied and Interdisciplinary Chemistry |
The wet chemical synthesis of thiolate-protected gold clusters is achieved by the reduction of gold(III) salt solutions, using a mild reducing agent in the presence of thiol compounds. This method starts with gold ions and synthesizes larger particles from them, therefore this type of synthesis can be regarded as a "bottom-up approach" in nanotechnology to the synthesis of nanoparticles.
The reduction process depends on the equilibrium between different oxidation states of the gold and the oxidized or reduced forms of the reducing agent, or thiols. Gold(I)-thiolate polymers have been identified as important in the initial steps of the reaction. Several synthesis recipes exist that are similar to the Brust synthesis of colloidal gold, however the mechanism is not yet fully understood. The synthesis produces a mixture of dissolved, thiolate-protected gold clusters of different sizes. These particles can then be separated by gel electrophoresis (PAGE). If the synthesis is performed in a kinetically controlled manner, particularly stable representatives can be obtained with particles of uniform size (monodispersely), avoiding further separation steps. | 0 | Theoretical and Fundamental Chemistry |
In chemistry, the term supramolecular chirality is used to describe supramolecular assemblies that are non-superposable on their mirror images.
Chirality in supramolecular chemistry implies the non-symmetric arrangement of molecular components in a non-covalent assembly. Chirality may arise in a supramolecular system if one of its component is chiral or if achiral components arrange in a non symmetrical way to produce a supermolecule that is chiral. | 0 | Theoretical and Fundamental Chemistry |
ECL proved to be very useful in analytical applications as a highly sensitive and selective method. It combines analytical advantages of chemiluminescent analysis (absence of background optical signal) with ease of reaction control by applying electrode potential. As an analytical technique it presents outstanding advantages over other common analytical methods due to its versatility, simplified optical setup compared with photoluminescence (PL), and good temporal and spatial control compared with chemiluminescence (CL). Enhanced selectivity of ECL analysis is reached by variation of electrode potential thus controlling species that are oxidized/reduced at the electrode and take part in ECL reaction (see electrochemical analysis).
It generally uses Ruthenium complexes, especially [[tris(bipyridine)ruthenium(II) chloride|[Ru(bpy)]]] (bpy = 2,2'-bipyridine) which releases a photon at ~620 nm regenerating with TPrA (Tripropylamine) in liquid phase or liquid–solid interface. It can be used as monolayer immobilized on an electrode surface (made e.g. of nafion, or special thin films made by Langmuir–Blogett technique or self-assembly technique) or as a coreactant or more commonly as a tag and used in HPLC, Ru tagged antibody based immunoassays, Ru Tagged DNA probes for PCR etc., NADH or HO generation based biosensors, oxalate and organic amine detection and many other applications and can be detected from picomolar sensitivity to dynamic range of more than six orders of magnitude. Photon detection is done with photomultiplier tubes (PMT) or silicon photodiode or gold coated fiber-optic sensors. The importance of ECL techniques detection for bio-related applications has been well established. ECL is heavily used commercially for many clinical lab applications. | 0 | Theoretical and Fundamental Chemistry |
Besides being participants in a clinical trial, members of the public can be actively collaborate with researchers in designing and conducting clinical research. This is known as patient and public involvement (PPI). Public involvement involves a working partnership between patients, caregivers, people with lived experience, and researchers to shape and influence what is researcher and how. PPI can improve the quality of research and make it more relevant and accessible. People with current or past experience of illness can provide a different perspective than professionals and compliment their knowledge. Through their personal knowledge they can identify research topics that are relevant and important to those living with an illness or using a service. They can also help to make the research more grounded in the needs of the specific communities they are part of. Public contributors can also ensure that the research is presented in plain language that is clear to the wider society and the specific groups it is most relevant for. | 1 | Applied and Interdisciplinary Chemistry |
The Tremolite Asbestos Registry contains people who lived in or worked in Libby, Montana, while vermiculite was mined there; these people were at risk for exposure to the tremolite asbestos that was naturally occurring in the vermiculite. ATSDR began addressing public health concerns in Libby in 1999 and created the registry in 2004. The purpose of the registry was to monitor the long-term health effects of people in Libby exposed to tremolite asbestos and to assist with communicating important health information to registrants. Researchers have used the registry to study how asbestos exposure affects human health. This research has yielded several important findings. Registry data was used to conduct the first study of the relationship between asbestos exposure and respiratory problems in children. Another study using registry data found a significant relationship between asbestos exposure and death from cardiovascular disease. | 1 | Applied and Interdisciplinary Chemistry |
Two atoms can be bonded by sharing more than one pair of electrons. The common bonds to carbon are single, double and triple bonds. Single bonds are most common and are represented by a single, solid line between two atoms in a skeletal formula. Double bonds are denoted by two parallel lines, and triple bonds are shown by three parallel lines.
In more advanced theories of bonding, non-integer values of bond order exist. In these cases, a combination of solid and dashed lines indicate the integer and non-integer parts of the bond order, respectively. | 0 | Theoretical and Fundamental Chemistry |
The determination of enantiomeric purity and absolute configuration is frequently necessary in organic synthesis. Pirkles alcohol is applied to obtain this information by NMR spectroscopy. When Pirkles alcohol is in solution with an ensemble of chiral molecules, short-lived diastereomeric solvates may be formed from Pirkles alcohol and the enantiomers of the analyte. Enantiomorphic protons of the analyte enantiomers, which without Pirkles alcohol are indistinguishable by NMR, become diastereomorphic when the analyte interacts with Pirkle's alcohol, and appear as different signals in an NMR spectrum. The relative magnitude of the signals quantitatively reveals the enantiomeric purity of the analyte. Also, a model of the solvated complex may be used to deduce absolute configuration of an enantioenriched analyte. | 0 | Theoretical and Fundamental Chemistry |
According to Reetz, the Cram-chelate model for 1,2-inductions can be extended to predict the chelated complex of a β-alkoxy aldehyde and metal. The nucleophile is seen to attack from the less sterically hindered side and anti- to the substituent R, leading to the anti-adduct as the major product.
To make such chelates, the metal center must have at least two free coordination sites and the protecting ligands should form a bidentate complex with the Lewis acid. | 0 | Theoretical and Fundamental Chemistry |
The N-terminus for Caldoramide is N,N-dimethylvaline which is attached to a valine which is attached to an N-Me-valine connected to an N-Me-isoleucine which is attached to the C-terminus. The molecule can also be written as N,N-diMe-Val-Val-N-Me-Val-N-Me-Ile-3-O-Me-4-benzylpyrrolinone. | 1 | Applied and Interdisciplinary Chemistry |
Small-angle laser light scattering has provided information about spatial density fluctuations or the shape of growing crystal grains. In addition, confocal laser scanning microscopy has been used to observe crystal growth near a glass surface. Electro-optic shear waves have been induced by an ac pulse, and monitored by reflection spectroscopy as well as light scattering. Kinetics of colloidal crystallization have been measured quantitatively, with nucleation rates being depending on the suspension concentration. Similarly, crystal growth rates have been shown to decrease linearly with increasing reciprocal concentration. | 0 | Theoretical and Fundamental Chemistry |
Perstraction is a membrane extraction process, where two liquid phases are contacted across a membrane. The desired species in the feed (solute), selectively crosses the membrane into the extracting solution. Perstraction was originally developed to overcome the downsides of liquid–liquid extraction, for example extractant toxicity and emulsion formation. Perstraction has been applied to many fields including fermentation, waste water treatment and alcohol-free beverage production. | 0 | Theoretical and Fundamental Chemistry |
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