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Real-life crime scene investigators and forensic scientists warn that popular television shows do not give a realistic picture of the work, often wildly distorting its nature, and exaggerating the ease, speed, effectiveness, drama, glamour, influence and comfort level of their jobs—which they describe as far more mundane, tedious and boring.
Some claim these modern TV shows have changed individuals' expectations of forensic science, sometimes unrealistically—an influence termed the "CSI effect".
Further, research has suggested that public misperceptions about criminal forensics can create, in the mind of a juror, unrealistic expectations of forensic evidence—which they expect to see before convicting—implicitly biasing the juror towards the defendant. Citing the "CSI effect," at least one researcher has suggested screening jurors for their level of influence from such TV programs. | 0 | Theoretical and Fundamental Chemistry |
In polymer chemistry, compatibilization is the addition of a substance to an immiscible blend of polymers that will increase their stability. Polymer blends are typically described by coarse, unstable phase morphologies; this results in poor mechanical properties. Compatibilizing the system will make a more stable and better blended phase morphology by creating interactions between the two previously immiscible polymers. Not only does this enhance the mechanical properties of the blend, but it often yields properties that are generally not attainable in either single pure component. | 0 | Theoretical and Fundamental Chemistry |
Generally speaking, carbohydrates can be classified into two groups, simple sugars, and complex carbohydrates. Simple sugars, also called monosaccharides, are carbohydrates that cannot be further broke down by hydrolysis. When glycosidic linkages connect two or more monosaccharide units, complex carbohydrates are formed. Complex carbohydrates, according to the different number of monosaccharide units, can be classed into three groups, disaccharides, oligosaccharides, and polysaccharides. A disaccharide is formed from two monosaccharides. When a carbohydrate contains 3-10 monosaccharides, it is called a oligosaccharide. Higher oligosaccharides with more than 10 monosaccharides are polysaccharides.
So far, there has not been a unified synthetic strategy of consistent oligosaccharide production because of the nuances in the anomeric effects of monomers and the complexity in the carbohydrate structures. The facile procedures such as the one-pot and solid phase synthesis which ensures atom economy are used. However, further developments in those synthetic approaches are needed since still not fully controlled and automated. | 0 | Theoretical and Fundamental Chemistry |
K'Airmobiles vehicles were intended to be commercialized from a project developed in France in 2006–2007 by a small group of researchers. However, the project has not been able to gather the necessary funds.
People should note that, meantime, the team has recognized the physical impossibility to use on-board stored compressed air due to its poor energy capacity and the thermal losses resulting from the expansion of the gas.
These days, using the patent pending KAir Generator', converted to work as a compressed-gas motor, the project should be launched in 2010, thanks to a North American group of investors, but for the purpose of developing first a green energy power system. | 1 | Applied and Interdisciplinary Chemistry |
Stefan adhesion is the normal stress (force per unit area) acting between two discs when their separation is attempted. Stefan's law governs the flow of a viscous fluid between the solid parallel plates and thus the forces acting when the plates are approximated or separated.
The force resulting at distance between two parallel circular disks of radius , immersed in a Newtonian fluid with viscosity , at time , depends on the rate of change of separation :
Stefan adhesion is mentioned in conjunction with bioadhesion by mucus-secreting animals. Nevertheless, most such systems violate the assumptions of the equation. In addition, these systems are much more complex when the fluid is non-Newtonian or inertial effects are relevant (high flow rate). | 0 | Theoretical and Fundamental Chemistry |
Immunologic adjuvants are substances, administered in conjunction with a vaccine, that stimulate the immune system and increase the response to the vaccine. Squalene is not itself an adjuvant, but it has been used in conjunction with surfactants in certain adjuvant formulations.
An adjuvant using squalene is Seqirus proprietary MF59, which is added to influenza vaccines to help stimulate the human bodys immune response through production of CD4 memory cells. It is the first oil-in-water influenza vaccine adjuvant to be commercialised in combination with a seasonal influenza virus vaccine. It was developed in the 1990s by researchers at Ciba-Geigy and Chiron; both companies were subsequently acquired by Novartis. Novartis was later acquired by CSL Bering and created the company Seqirus. It is present in the form of an emulsion and is added to make the vaccine more immunogenic. However, the mechanism of action remains unknown. MF59 is capable of switching on a number of genes that partially overlap with those activated by other adjuvants. How these changes are triggered is unclear; to date, no receptors responding to MF59 have been identified. One possibility is that MF59 affects the cell behaviour by changing the lipid metabolism, namely by inducing accumulation of neutral lipids within the target cells. An influenza vaccine called [https://www.fluad.ca/patient/en/index.html?gclid=Cj0KCQiAzMGNBhCyARIsANpUkzPPnohR9VXZ2WLu-FjLHTTuYljtqZti7Qybbq-nr59zQ3gcvSBUwlwaAng1EALw_wcB FLUAD] which used MF59 as an adjuvant was approved for use in the US in people 65 years of age and older, beginning with the 2016–2017 flu season.
A 2009 meta-analysis assessed data from 64 clinical trials of influenza vaccines with the squalene-containing adjuvant MF59 and compared them to the effects of vaccines with no adjuvant. The analysis reported that the adjuvated vaccines were associated with slightly lower risks of chronic diseases, but that neither type of vaccines altered the rate of autoimmune diseases; the authors concluded that their data "supports the good safety profile associated with MF59-adjuvated influenza vaccines and suggests there may be a clinical benefit over non-MF59-containing vaccines". | 1 | Applied and Interdisciplinary Chemistry |
The International Society for the History of Pharmacy (ISHP) is a non profit international society devoted to the academic study of the history of pharmacy. The umbrella organization of 29 national societies promotes research, teaching and publication in pharmaceutical history. It regularly organizes congresses and awards a research grant every two years. Publication organs are an annual newsletter and the peer-reviewed journal Pharmaceutical Historian, which is published in cooperation with the British Society for the History of Pharmacy. | 1 | Applied and Interdisciplinary Chemistry |
CDI is mainly employed to convert amines into amides, carbamates, ureas. It can also be used to convert alcohols into esters. | 0 | Theoretical and Fundamental Chemistry |
The hexahydrate and the anhydrous salt are weak Lewis acids. The adducts are usually either octahedral or tetrahedral. It forms an octahedral complex with pyridine ():
With triphenylphosphine (), a tetrahedral complex results:
Salts of the anionic complex CoCl can be prepared using tetraethylammonium chloride:
: + 2 [(CH)N]Cl → [(CH)N)][CoCl]
The tetrachlorocobaltate ion [CoCl] is the blue ion that forms upon addition of hydrochloric acid to aqueous solutions of hydrated cobalt chloride, which are pink. | 0 | Theoretical and Fundamental Chemistry |
FRELEX was developed in 2016 by [https://neoaptamers.com/ NeoVentures Biotechnology Inc] to allow the selection of aptamers without immobilizing the target or the oligonucleotide library. Immobilization is a necessary component of SELEX; however, it has the potential to inhibit key epitopes, and thus weaken the likelihood of successful binding, particularly when working with small molecules. FRELEX follows a similar overall methodology to SELEX; however, instead of immobilizing the target, the researcher introduces a series of random and blocker oligonucleotides to an immobilization field before introduction to the target. This allows the researcher to better target small molecules that may be lost during partitioning. It also can be used in some circumstances to select an aptamer library without knowing the target.
Most modern aptamer selection methods strive to improve the conventional SELEX aptamer search method. Despite the publication of various methods aimed at increasing the affinity and specificity of aptamers, experimental approaches face limitations in the number and variety of sequences that can be examined and selected. Library capacity for SELEX experiments is practically limited to 10 candidates, whereas, assuming there is a 4-monomeric repertoire from which pools can be created, there are ~1.6 × 10 unique sequences in sequence space limited to a 100-residue matrix, which is clearly beyond experimental capabilities. The library of oligonucleotides must be extremely diverse and not contain linear, incapable of providing a stable spatial arrangement, and double-stranded structures; due to these limitations, oligonucleotide libraries can cover the diversity of only ~10 sequences. This means that existing aptamers may not fully cover the diversity of target molecules or may not have optimal properties due to limitations of the underlying method. To yield the best possible aptamers one must maximize the effectiveness of the discovery process and the library itself.
RNA and DNA secondary structure prediction by dynamic programming algorithms such as RNAfold (ViennaRNA) and by machine learning models such as SPOT-RNA, MXfold2 provides the opportunity to assess the ability of sequences in the primary library to fold into complex structures, allowing for the selection of only the most promising sequences from the entire pool. However, these algorithms are low-performance, making them poorly suited for this task. For this reason, algorithms like Ufold from the University of California and AliNA from Nanobiorobots Inc. have been developed, which demonstrate a significant increase in computational speed due to their faster architecture, and can be applied for preliminary in silico analysis of these libraries. | 1 | Applied and Interdisciplinary Chemistry |
For the parallel-plate capacitor we have , where is the applied voltage. As a single ionization was assumed is the elementary charge . We can now put () and () into () and get
Putting this into (5) and transforming to we get the Paschen law for the breakdown voltage that was first investigated by Paschen in
and whose formula was first derived by Townsend in | 0 | Theoretical and Fundamental Chemistry |
In chemical physics and physical chemistry, chemical affinity is the electronic property by which dissimilar chemical species are capable of forming chemical compounds. Chemical affinity can also refer to the tendency of an atom or compound to combine by chemical reaction with atoms or compounds of unlike composition.
In modern terms, we relate affinity to the phenomenon whereby certain atoms or molecules have the tendency to aggregate or bond. For example, in the 1919 book Chemistry of Human Life physician George W. Carey states that, "Health depends on a proper amount of iron phosphate Fe(PO) in the blood, for the molecules of this salt have chemical affinity for oxygen and carry it to all parts of the organism." In this antiquated context, chemical affinity is sometimes found synonymous with the term "magnetic attraction". Many writings, up until about 1925, also refer to a "law of chemical affinity".
Ilya Prigogine summarized the concept of affinity, saying, "All chemical reactions drive the system to a state of equilibrium in which the affinities of the reactions vanish." | 0 | Theoretical and Fundamental Chemistry |
1-Pyrroline-5-carboxylic acid (systematic name 3,4-dihydro-2H-pyrrole-2-carboxylic acid) is a cyclic imino acid. Its conjugate base and anion is 1-pyrroline-5-carboxylate (P5C). In solution, P5C is in spontaneous equilibrium with glutamate-5-semialdhyde (GSA). | 1 | Applied and Interdisciplinary Chemistry |
In Batesian mimicry, potential prey organisms will mimic chemicals emitted by an organism that poses a greater risk to the predator in order to deter attack. Most commonly this form of chemical mimicry is seen in plant species through the release of mimicked defense chemicals. The organism being mimicked may contain noxious chemicals used to deter predators from consuming them as it will lead to the predator becoming ill. By using Batesian mimicry the operator will mimic a chemical aspect, such as “defense signals" used by plants, in order to deceive the herbivore or predator into avoiding an edible organism. | 1 | Applied and Interdisciplinary Chemistry |
A linear combination of atomic orbitals or LCAO is a quantum superposition of atomic orbitals and a technique for calculating molecular orbitals in quantum chemistry. In quantum mechanics, electron configurations of atoms are described as wavefunctions. In a mathematical sense, these wave functions are the basis set of functions, the basis functions, which describe the electrons of a given atom. In chemical reactions, orbital wavefunctions are modified, i.e. the electron cloud shape is changed, according to the type of atoms participating in the chemical bond.
It was introduced in 1929 by Sir John Lennard-Jones with the description of bonding in the diatomic molecules of the first main row of the periodic table, but had been used earlier by Linus Pauling for H. | 0 | Theoretical and Fundamental Chemistry |
Bioswales work to remove pollutants through vegetation and the soil. As the storm water runoff flows through the bioswale, the pollutants are captured and settled by the leaves and stems of the plants. The pollutants then enter the soil where they decompose or can be broken down by bacteria in healthy soil.
There are several classes of water pollutants that may be collected or arrested with bioswales. These fall into the categories of silt, inorganic contaminants, organic chemicals and pathogens.
* Silt. How bioswales and plants are constructed slow the conveyance of silt and reduce the turbidity of receiving waters. Filters can be established to capture debris and silt during the process.
* Organics. Many organic contaminants including Polycyclic aromatic hydrocarbons will volatilize or degrade over time and Bioswales slow the conveyance of these materials into waterways, and before they can affect aquatic life. Although not all organic material will be captured, the concentration of organic material is greatly reduced by bioswales.
* Pathogens are deprived of a host or from a nutrient supply long enough for them to become the target of a heterotroph.
* Common inorganic compounds are macronutrients such as phosphates and nitrates. Principal sources of these nutrients comes from agricultural runoff attributed to excess fertilization. Excess phosphates and nitrates can cause eutrophication in disposal zones and receiving waters. Specific bioswale plants absorb these excess nutrients.
* Metallic compounds such as mercury, lead, chromium, cadmium and other heavy metals are concentrated in the structures. Unfortunately, these metals slowly poison the surrounding soil. Regular soil removal is required in order to prevent metals from dissolving and releasing back into the environment. Some bioswales are designed to include hyperaccumulator plant species. These plants absorb but do not transform the metals. Cuttings from these plants often decompose back into the pond or are pruned by gardening services that do not know the compost they are collecting is poisonous. | 1 | Applied and Interdisciplinary Chemistry |
Homing endonucleases are always indicated with a prefix that identifies their genomic origin, followed by a hyphen: "I-" for homing endonucleases encoded within an intron, "PI-" (for "protein insert") for those encoded within an intein. Some authors have proposed using the prefix "F-" ("freestanding") for viral enzymes and other natural enzymes not encoded by introns nor inteins, and "H-" ("hybrid") for enzymes synthesized in a laboratory. Next, a three-letter name is derived from the binominal name of the organism, taking one uppercase letter from the genus name and two lowercase letters from the specific name. (Some mixing is usually done for hybrid enzymes.) Finally, a Roman numeral distinguishes different enzymes found in the same organism:
* PI-TliII () is the second-identified enzyme encoded by an intein found in the archaea Thermococcus litoralis.
* H-DreI () is the first synthetic homing endonuclease, created in a laboratory from the enzymes I-DmoI () and I-CreI (), taken respectively from Desulfurococcus mobilis and Chlamydomonas reinhardtii. | 1 | Applied and Interdisciplinary Chemistry |
The synthesis of an mRNA display library starts from the synthesis of a DNA library. A DNA library for any protein or small peptide of interest can be synthesized by solid-phase synthesis followed by PCR amplification. Usually, each member of this DNA library has a T7 RNA polymerase transcription site and a ribosomal binding site at the 5’ end. The T7 promoter region allows large-scale in vitro T7 transcription to transcribe the DNA library into an mRNA library, which provides templates for the in vitro translation reaction later. The ribosomal binding site in the 5’-untranslated region (5’ UTR) is designed according to the in vitro translation system to be used. There are two popular commercially available in vitro translation systems. One is E. coli S30 Extract System (Promega) that requires a Shine-Dalgarno sequence in the 5’ UTR as a ribosomal binding site; the other one is Red Nova Lysate (Novagen), which needs a ΔTMV ribosomal binding site.
Once the mRNA library is generated, it will be Urea-PAGE purified and ligated using T4 DNA ligase to the DNA spacer linker containing puromycin at the 3’ end. In this ligation step, a piece of mRNA is ligated with a single stranded DNA with the help from T4 DNA ligase. This is not a standard T4 DNA ligase ligation reaction, where two pieces of double stranded DNA are ligated together. To increase the yield of this special ligation, a single stranded DNA splint may be used to aid the ligation reaction. The 5’ terminus of the splint is designed to be complementary to the 3’ end of the mRNA, and the 3’ terminus of the splint is designed to be complementary to the 5’ end of the DNA spacer linker, which usually consists of poly dA nucleotides (Figure 2).
The ligated mRNA-DNA-puromycin library is translated in Red Nova Lysate (Novagen) or E. coli S30 Extract System (Promega), resulting in polypeptides covalently linked in cis to the encoding mRNA. The in vitro translation can also be done in a PURE (protein synthesis using recombinant elements) system. PURE system is an E. coli cell-free translation system in which only essential translation components are present. Some components, such as amino acids and aminoacyl-tRNA synthases (AARSs) can be omitted from the system. Instead, chemically acylated tRNA can be added into the PURE system. It has been shown that some unnatural amino acids, such as N-methyl-amino acid accylated tRNA can be incorporated into peptides or mRNA-polypeptide fusions in a PURE system.
After translation, the single-stranded mRNA portions of the fusions will be converted to heteroduplex of RNA/DNA by reverse transcriptase to eliminate any unwanted RNA secondary structures, and render the nucleic acid portion of the fusion more stable. This step is a standard reverse transcription reaction. For instance, it can be done by using Superscript II (GIBCO-BRL) following the manufacturer’s protocol.
The mRNA/DNA-polypeptide fusions can be selected over immobilized selection targets for several rounds (Figure 3). There might be a relatively high background for the first few rounds of selection, and this can be minimized by increasing selection stringency, such as adjusting salt concentration, amount of detergent, and/or temperature during the target/fusion binding period. Following binding selection, those library members that stay bound to the immobilized target are PCR amplified. The PCR amplification step will enrich the population from the mRNA-display library that has higher affinity for the immobilized target. Error-prone PCR can also be done in between each round of selection to further increase the diversity of the mRNA-display library and reduce background in selection.
A less time-consuming protocol for mRNA display was recently published. | 1 | Applied and Interdisciplinary Chemistry |
In recent years, more advanced UV-VIS detectors have been increasingly used, based on diode arrays and entire spectrum collection at any given moment of data collection. The are called Diode Array detectors, and they collect entire UV spectra of every point the eluting peaks, while operating as a multi-wavelength UV-vis detector. This way they give additional information, which help understand more about the nature of the substances appearing in the chromatogram and allow their identification. Since the detector facilitates better peak identification it is the preferred detector for HPLC method development.
A schematic of the optical systems is shown in Figure 1. The variable UV-vis absorbance detector's optical bench is showing how the flow cell is positioned after the optical system, including the monochromator, which typically has a physical slit and a moving grating, so it is illuminated by a selected wavelength, reaching a photo-diode. The bench of the diode array detector, however, is configured so that the flow cell is positioned before the optical parts, so that the beam containing the entire spectrum is passing through it. The optical parts consist also with a monochromator and a slit, but with a fixed grating, which disperses the light onto a diode array imaging element. | 0 | Theoretical and Fundamental Chemistry |
In the absence of plentiful oxygen, aerobic bacteria were prevented from decaying the organic matter after it was buried under a layer of sediment or water. However, anaerobic bacteria were able to reduce sulfates and nitrates among the matter to HS and N respectively by using the matter as a source for other reactants. Due to such anaerobic bacteria, at first, this matter began to break apart mostly via hydrolysis: polysaccharides and proteins were hydrolyzed to simple sugars and amino acids respectively. These were further anaerobically oxidized at an accelerated rate by the enzymes of the bacteria: e.g., amino acids went through oxidative deamination to imino acids, which in turn reacted further to ammonia and α-keto acids. Monosaccharides in turn ultimately decayed to CO and methane. The anaerobic decay products of amino acids, monosaccharides, phenols and aldehydes combined into fulvic acids. Fats and waxes were not extensively hydrolyzed under these mild conditions. | 0 | Theoretical and Fundamental Chemistry |
Section 3.8 introduces atomic units and gives a table of atomic units of various physical quantities and the conversion factor to the SI units. Section 7.3(v) gives a concise but clear tutorial on practical use of atomic units, in particular how to understand equations "written in atomic units". | 0 | Theoretical and Fundamental Chemistry |
Andrew Carnegie, a Scottish immigrant, advanced the cheap and efficient mass production of steel rails for railroad lines, by adopting the Bessemer process. After an early career in railroads, Carnegie foresaw the potential for steel to amass vast profits. He asked his cousin, George Lauder to join him in America from Scotland. Lauder was a leading mechanical engineer who had studied under Lord Kelvin. Lauder devised several new systems for the Carnegie Steel Company including the process for washing and coking dross from coal mines, which resulted in a significant increase in scale, profits, and enterprise value.
Lauder would go on to lead the development of the use of steel in armor and armaments for the Carnegie Steel Company, spending significant time at the Krupp factory in Germany in 1886 before returning to build the massive armor plate mill at the Homestead Steel Works that would revolutionize naval warfare.
Carnegies first mill was the Edgar Thomson Works in Braddock, PA, just outside of Pittsburgh. In 1888, he bought the rival Homestead Steel Works, which included an extensive plant served by tributary coal and iron fields, a 425-mile (685 km) long railway, and a line of lake steamships. He would also add the Duquesne Works to his empire. These three mills on the Monongahela River would make Pittsburgh the steel capital of the world. In the late 1880s, the Carnegie Steel Company was the largest manufacturer of pig iron, steel rails, and coke in the world, with a capacity to produce approximately 2,000 tons of pig iron per day. A consolidation of Carnegies assets and those of his associates occurred in 1892 with the launching of the Carnegie Steel Company.
Lauder would go on to lead the development of the use of steel in armor and armaments for the Carnegie Steel Company, spending significant time at the Krupp factory in Germany in 1886 before returning to build the massive armor plate mill at the Homestead Steel Works that would revolutionize naval warfare.
By 1889, the U.S. output of steel exceeded that of Britain, and Andrew Carnegie owned a large part of it. By 1900, the profits of Carnegie Bros. & Company alone stood at $480,000,000 with $225,000,000 being Carnegie's share.
Carnegie, through Keystone, supplied the steel for and owned shares in the landmark Eads Bridge project across the Mississippi River in St. Louis, Missouri (completed 1874). This project was an important proof-of-concept for steel technology which marked the opening of a new steel market.
The Homestead Strike was a violent labor dispute in 1892 that involved an attack by strikers against private security guards. The governor called in the National Guard. The strike failed and the union collapsed. The dispute took place at Carnegie's Homestead Steel Works between the Amalgamated Association of Iron and Steel Workers and the Carnegie Steel Company. The final result was a major defeat for the union and a setback for efforts to unionize steelworkers.
Carnegie sold all his steel holdings in 1901; they were merged into U.S. Steel and it was non-union until the late 1930s. | 1 | Applied and Interdisciplinary Chemistry |
Usually the initial measurement is the minimal level of fluorescence, . This is the fluorescence in the absence of photosynthetic light.
To use measurements of chlorophyll fluorescence to analyse photosynthesis, researchers must distinguish between photochemical quenching and non-photochemical quenching (heat dissipation). This is achieved by stopping photochemistry, which allows researchers to measure fluorescence in the presence of non-photochemical quenching alone. To reduce photochemical quenching to negligible levels, a high intensity, short flash of light is applied to the leaf. This transiently closes all PSII reaction centres, which prevents energy of PSII being passed to downstream electron carriers. Non-photochemical quenching will not be affected if the flash is short. During the flash, the fluorescence reaches the level reached in the absence of any photochemical quenching, known as maximum fluorescence .
The efficiency of photochemical quenching (which is a proxy of the efficiency of PSII) can be estimated by comparing to the steady yield of fluorescence in the light and the yield of fluorescence in the absence of photosynthetic light .
The efficiency of non-photochemical quenching is altered by various internal and external factors. Alterations in heat dissipation mean changes in . Heat dissipation cannot be totally stopped, so the yield of chlorophyll fluorescence in the absence of non-photochemical quenching cannot be measured. Therefore, researchers use a dark-adapted point () with which to compare estimations of non-photochemical quenching. | 0 | Theoretical and Fundamental Chemistry |
Levofloxacin is a broad-spectrum antibiotic that is active against both Gram-positive and Gram-negative bacteria. Like all quinolones, it functions by inhibiting the DNA gyrase and topoisomerase IV, two bacterial type IIA topoisomerases. Topoisomerase IV is necessary to separate DNA that has been replicated (doubled) prior to bacterial cell division. With the DNA not being separated, the process is stopped, and the bacterium cannot divide. DNA gyrase, on the other hand, is responsible for supercoiling the DNA, so that it will fit in the newly formed cells. Both mechanisms amount to killing the bacterium. Levofloxacin acts as a bactericide.
As of 2011, the mechanism of action for the drug's musculoskeletal complications were not clear. | 0 | Theoretical and Fundamental Chemistry |
The visualization of single molecules, single biological cells, biological tissues and nanomaterials is very important and attractive approach in analytical science. Also, hybridization with other traditional analytical tools is revolutionizing analytical science. Microscopy can be categorized into three different fields: optical microscopy, electron microscopy, and scanning probe microscopy. Recently, this field has been rapidly progressing because of the rapid development of the computer and camera industries. | 0 | Theoretical and Fundamental Chemistry |
In 1913, chemists Frederick Soddy and Kasimir Fajans independently observed that alpha decay caused atoms to shift down two places on the periodic table, while the loss of two beta particles restored it to its original position. Under the resulting reorganisation of the periodic table, radium was placed in group II, actinium in group III, thorium in group IV and uranium in group VI. This left a gap between thorium and uranium. Soddy predicted that this unknown element, which he referred to (after Dmitri Mendeleev) as "ekatantalium", would be an alpha emitter with chemical properties similar to tantalium. It was not long before Fajans and Oswald Helmuth Göhring discovered it as a decay product of a beta-emitting product of thorium. Based on the radioactive displacement law of Fajans and Soddy, this was an isotope of the missing element, which they named "brevium" after its short half life. However, it was a beta emitter, and therefore could not be the mother isotope of actinium. This had to be another isotope of the same element.
Hahn and Meitner set out to find the missing mother isotope. They developed a new technique for separating the tantalum group from pitchblende, which they hoped would speed the isolation of the new isotope. The work was interrupted by the First World War. Meitner became an X-ray nurse, working in Austrian Army hospitals, but she returned to the Kaiser Wilhelm Institute in October 1916. Hahn joined the new gas command unit at Imperial Headquarters in Berlin in December 1916 after travelling between the western and eastern front, Berlin and Leverkusen between the summer of 1914 and late 1916.
Most of the students, laboratory assistants and technicians had been called up, so Hahn, who was stationed in Berlin between January and September 1917, and Meitner had to do everything themselves. By December 1917 she was able to isolate the substance, and after further work were able to prove that it was indeed the missing isotope. Meitner submitted her and Hahn´s findings for publication in March 1918 to the scientific paper Physikalischen Zeitschrift under the title .
Although Fajans and Göhring had been the first to discover the element, custom required that an element was represented by its longest-lived and most abundant isotope, and brevium did not seem appropriate. Fajans agreed to Meitner and Hahn naming the element protoactinmium, and assigning it the chemical symbol Pa. In June 1918, Soddy and John Cranston announced that they had extracted a sample of the isotope, but unlike Hahn and Meitner were unable to describe its characteristics. They acknowledged Hahn´s and Meitner's priority, and agreed to the name. The connection to uranium remained a mystery, as neither of the known isotopes of uranium decayed into protactinium. It remained unsolved until the mother isotope, uranium-235, was discovered in 1929.
For their discovery Hahn and Meitner were repeatedly nominated for the Nobel Prize in Chemistry in the 1920s by several scientists, among them Max Planck, Heinrich Goldschmidt, and Fajans himself. In 1949, the International Union of Pure and Applied Chemistry (IUPAC) named the new element definitively protactinium, and confirmed Hahn and Meitner as discoverers. | 0 | Theoretical and Fundamental Chemistry |
The world's supply of titanium metal, about 250,000 tons per year, is made from . The conversion involves the reduction of the tetrachloride with magnesium metal. This procedure is known as the Kroll process:
In the Hunter process, liquid sodium is the reducing agent instead of magnesium. | 0 | Theoretical and Fundamental Chemistry |
Laplaces improvements in theory were substantial, but they still left prediction in an approximate state. This position changed in the 1860s when the local circumstances of tidal phenomena were more fully brought into account by William Thomsons application of Fourier analysis to the tidal motions as harmonic analysis. Thomsons work in this field was further developed and extended by George Darwin, applying the lunar theory current in his time. Darwins symbols for the tidal harmonic constituents are still used.
Darwins harmonic developments of the tide-generating forces were later improved when A.T. Doodson, applying the lunar theory of E.W. Brown, developed the tide-generating potential (TGP) in harmonic form, distinguishing 388 tidal frequencies. Doodsons work was carried out and published in 1921. Doodson devised a practical system for specifying the different harmonic components of the tide-generating potential, the Doodson numbers, a system still in use.
Since the mid-twentieth century further analysis has generated many more terms than Doodson's 388. About 62 constituents are of sufficient size to be considered for possible use in marine tide prediction, but sometimes many fewer can predict tides to useful accuracy. The calculations of tide predictions using the harmonic constituents are laborious, and from the 1870s to about the 1960s they were carried out using a mechanical tide-predicting machine, a special-purpose form of analog computer. More recently digital computers, using the method of matrix inversion, are used to determine the tidal harmonic constituents directly from tide gauge records. | 1 | Applied and Interdisciplinary Chemistry |
The Influenza Antiviral Drug Search conducted millions of virtual docking experiments in order to discover compounds that may be suitable for real-world clinical trials to combat new or drug resistant strains of influenza virus.
One vulnerability of all influenza strains is that they need viral neuraminidase, NS1 Influenza Protein and hemagglutinin in order to infect a body. A chemical compound that can disable one of these molecules has the potential to be an effective antiviral drug. | 1 | Applied and Interdisciplinary Chemistry |
In addition to the scanning forms of Fourier-transform spectrometers, there are a number of stationary or self-scanned forms. While the analysis of the interferometric output is similar to that of the typical scanning interferometer, significant differences apply, as shown in the published analyses. Some stationary forms retain the Fellgett multiplex advantage, and their use in the spectral region where detector noise limits apply is similar to the scanning forms of the FTS. In the photon-noise limited region, the application of stationary interferometers is dictated by specific consideration for the spectral region and the application. | 0 | Theoretical and Fundamental Chemistry |
Brills submissions to the XIVth International Congress on Glass, which took place in New Delhi in 1986, can be seen to represent the origins of his work on the Great Silk Road, the impressive trade route carrying goods from the East through India to Europe. Here, chemical analysis of Early Indian glasses helped Brill determine the ingredients and techniques of production, ‘to make certain broad generalizations as to regions or periods of manufacture’, and therefore to follow an objects movement along the trade route (1987, 1). For the XIVth Congress, Brill conducted atomic absorption spectroscopy (AAS) and optical emission spectroscopy (OES) on samples of 38 glasses from India, and the success of his method was made clear when he was able to separate 21 samples away from those made in the Middle East and Europe (Brill 1987). The glasses were shown to have mixed alkali compositions, a feature that is ‘rare among glasses from more westerly sources’, and therefore Brill concluded that they had definitely been manufactured in India (1987, 4). Brill also collaborated with Mckinnon to conduct chemical analyses of some glass samples from Sumatra, Indonesia, the results of which would be the ‘first data of their kind from this island’ (1987, 1). The results of the study, which also used samples from Java, another important location for the Silk Road, were hoped by McKinnon and Brill to ‘stimulate a greater awareness of glass in the economy [...] of ancient Sumatra and further new lines of research in the archaeology of the region’ (1987, 1). | 0 | Theoretical and Fundamental Chemistry |
O-donors such as HPO were abundant in the prebiotic atmosphere. Metal ion binding to such O-donors was required to build the biological polymers, since the bond is generally weak, it can catalyze the required reaction and dissociate after (i.e. Mg in DNA synthesis). | 0 | Theoretical and Fundamental Chemistry |
Massive parallel signature sequencing (MPSS) is a procedure that is used to identify and quantify mRNA transcripts, resulting in data similar to serial analysis of gene expression (SAGE), although it employs a series of biochemical and sequencing steps that are substantially different. | 1 | Applied and Interdisciplinary Chemistry |
The industrial production of microbial food cultures is carried out after careful selection process and under strictly controlled conditions. First, the microbiology laboratory, where the original strains are kept, prepares the inoculation material, which is a small quantity of microbes of a single (pure) strain. Then, the inoculation material is multiplied and grown either in fermenters (liquid) or on a surface (solid) under defined and monitored conditions. Grown cells of pure culture are harvested, eventually blended with other cultures and, finally, formulated (preserved) for subsequent transportation and storage. They are sold in liquid, frozen or freeze-dried formats.
Another and traditional way of starting a food fermentation is often referred to as spontaneous fermentation. Cultures come from raw milk, i.e. milk that has not undergone any sanitation treatment or from the reuse of a fraction of the previous production (back-slopping). The composition of such cultures is complex and extremely variable. The use of such techniques is steadily decreasing in developed countries. Some countries even prohibit the back-slopping technique because of the "potential to magnify pathogen loads to very dangerous levels". | 1 | Applied and Interdisciplinary Chemistry |
Cobalt extraction refers to the techniques used to extract cobalt from its ores and other compound ores. Several methods exist for the separation of cobalt from copper and nickel. They depend on the concentration of cobalt and the exact composition of the ore used. | 1 | Applied and Interdisciplinary Chemistry |
Symplekin (SYMPK) is a scaffolding protein that mediates the interaction between CPSF and CstF.
In mammalian CPSF, both cleavage factor I (CFI) and cleavage and polyadenylation specificity factor (CPSF) are required for cleavage and polyadenylation whereas cleavage stimulation factor (CstF) is only essential for the cleavage step. CPSF and CstF travel along with RNA polymerase II (RNAP II) during nascent gene transcription in search of the PAS.
Cleavage factor I (CFI) is made of 25 (CPSF5), 59 (CPSF7), and 68 (CPSF6) kDa proteins. Cleavage factor II (CFII) is made of Pcf11, Clp1, and cleavage stimulation factor (CstF). CFII binds to the RNAP II C-terminal domain and other CpA factors.
Cleavage stimulation factor (CstF) has three subunits: CstF77 (CstF3), CstF50 (CstF1), and CstF64 (CstF2 and CstF2T). CstF recognizes the PAS that is 20 nucleotides downstream the signaling region of the cleavage site, which is a GU-rich sequence motif followed by U-rich sequences. CstF contributes to the selection of the cleavage site, as well as alternative polyadenylation. | 1 | Applied and Interdisciplinary Chemistry |
This is a device formed by a metallic bar (called the agitation bar) which is normally covered by a plastic layer, and a sheet that has underneath it a rotatory magnet or a series of electromagnets arranged in a circular form to create a magnetic rotatory field. Commonly, the sheet has an arrangement of electric resistances that can heat some chemical solutions.
During the operation of a typical magnetic agitator, the agitator bar is moved inside a container such as to dissolve a substance in a liquid. The container must be placed on the sheet, so that the magnetic field influences the agitation bar and makes it rotate. This allows it to mix different substances at high speeds. | 1 | Applied and Interdisciplinary Chemistry |
A partial extraction procedure was developed in 1935 which involved reacting the compound with benzoyl chloride to allow it to be separated from the water-soluble components. The compound was first isolated and purified to crystals by Osamu Shimomura. The structure of the compound was confirmed some years later. Feeding experiments suggest that the compound is synthesized in the animal from three amino-acids: tryptophan, isoleucine, and arginine. | 1 | Applied and Interdisciplinary Chemistry |
Soderholm was awarded her PhD in 1982 by McMaster University under the direction of Prof John Greedan. Her dissertation focused on characterizing the structural and magnetic properties of a series of ternary f-ion oxides. After graduating, she was awarded a NATO postdoctoral fellow at the Centre national de la recherche scientifique in France from 1982 until 1985. After a short postdoctoral appointment as an Argonne postdoctoral fellow she was promoted to staff scientist the same year. Over several years, she moved up the ranks, becoming a senior chemist in 2001. She was also an adjunct professor at the University of Notre Dame from 2003 until 2007. In 2021, Soderholm was appointed interim Division Director for the Chemical Sciences and Engineering Division. | 0 | Theoretical and Fundamental Chemistry |
Although there are many diverse pathogens, many of which are constantly mutating, it is a surprise that a majority of individuals remain free of infections. Thus, maintenance of health requires the body to recognize all pathogens (antigens they present or produce) likely to exist. This is achieved by maintaining a pool of immensely large (about 10) clones of B cells, each of which reacts against a specific epitope by recognizing and producing antibodies against it. However, at any given time very few clones actually remain receptive to their specific epitope. Thus, approximately 10 different epitopes can be recognized by all the B cell clones combined. Moreover, in a lifetime, an individual usually requires the generation of antibodies against very few antigens in comparison with the number that the body can recognize and respond against. | 1 | Applied and Interdisciplinary Chemistry |
Trandolapril is a prodrug that is deesterified to trandolaprilat. It is believed to exert its antihypertensive effect through the renin–angiotensin–aldosterone system. Trandolapril has a half-life of about six hours, while trandolaprilat has a half life of about ten hours. Trandolaprilat has about eight times the activity of its parent drug. About one-third of trandolapril and its metabolites are excreted in the urine, and about two-thirds of trandolapril and its metabolites are excreted in the feces. Serum protein binding of trandolapril is about 80%. | 0 | Theoretical and Fundamental Chemistry |
From 1995 Murray worked at the Thomas J. Watson Research Center at IBM. From 2000 to 2006 he headed their Nanoscale Materials and Devices Department. In 2006 the University of Pennsylvania announced his appointment as the Richard Perry University Professor, with appointments in Chemistry and Materials Science, in the schools of Arts and Sciences, and Engineering and Applied Science. | 0 | Theoretical and Fundamental Chemistry |
Swiss-Prot lists 137 types of neuraminidase from various species as of October 18, 2006. Nine subtypes of influenza neuraminidase are known; many occur only in various species of duck and chicken. Subtypes N1 and N2 have been positively linked to epidemics in humans, and strains with N3 or N7 subtypes have been identified in a number of isolated deaths.
CAZy defines a total of 85 glycosyl hydrolase families, of which families GH34 (viral), GH33 (cellular organisms), GH58 (viral and bacterial), GH83 (viral) are major families that contain this enzyme. GH58 is the only endo-acting family.
The following is a list of major classes of neuraminidase enzymes:
* Viral neuraminidase
* Bacterial neuraminidase
* Mammalian neuraminidases: | 0 | Theoretical and Fundamental Chemistry |
To specify the crystal form of a compound or element the Pearson symbol may be used. The use of Strukturbericht (e.g. A1 etc) or Greek letters is not acceptable. The Pearson symbol may be followed by the space group and the prototype formula. Examples are:
* , diamond
* ( type) | 0 | Theoretical and Fundamental Chemistry |
At least five different kinds of snRNPs join the spliceosome to participate in splicing. They can be visualized by gel electrophoresis and are known individually as: U1, U2, U4, U5, and U6. Their snRNA components are known, respectively, as: U1 snRNA, U2 snRNA, U4 snRNA, U5 snRNA, and U6 snRNA.
In the mid-1990s, it was discovered that a variant class of snRNPs exists to help in the splicing of a class of introns found only in metazoans, with highly conserved 5' splice sites and branch sites. This variant class of snRNPs includes: U11 snRNA, U12 snRNA, U4atac snRNA, and U6atac snRNA. While different, they perform the same functions as do U1, U2, U4, and U6, respectively.
Additionally, U7 snRNP is made of U7 small nuclear RNA and associated proteins and is involved in the processing of the 3′ stem-loop of histone pre-mRNA. | 1 | Applied and Interdisciplinary Chemistry |
A crystal model is a teaching aid used for understanding concepts in crystallography and the morphology of crystals. Models are ideal to learn recognizing symmetry elements in crystals. | 0 | Theoretical and Fundamental Chemistry |
Bifidobacterium bifidum utilizes a lactic acid fermentation pathway that produces more ATP than either homolactic fermentation or heterolactic fermentation:
:2 Glucose + 5 ADP + 5 P → 3 Acetate + 2 Lactate + 5 ATP | 1 | Applied and Interdisciplinary Chemistry |
Two or more methine bridges can overlap, forming a chain or ring of carbon atoms connected by alternating single and double bonds, as in piperylene , or the compound
Every carbon atom in this molecule is a methine carbon atom, except for three; two that are attached to the two nitrogen atoms and not to any hydrogen atoms, and the carbon attached to the nitrogen atom, which is attached to two hydrogen atoms (far right). There is a five-carbon-atom poly-methine chain in the center of this molecule.
Chains of alternating single and double bonds often form conjugated systems. When closed, as in benzene , they often give aromatic character to the compound. | 0 | Theoretical and Fundamental Chemistry |
In November 2007, a controversial aerial approach was used to spray microencapsulated LBAM pheromone in urban and rural areas of the counties of Santa Cruz and Monterey California to combat the invasive light brown apple moth. Usually the effect of disruption of orientation of the male moths to females (or monitoring pheromone traps) can be detected by the reduction in moth capture in monitoring pheromone traps. The government campaign using areawide aerial microencapsulated pheromone applications failed to show any sign of mating disruption on the light brown apple moth populations in the treated area. It was found that the first aerial campaign was performed using an incomplete (the wrong) pheromone blend of the light brown apple moth (the wrong blend decreased tremendously the likelihood of success of the mating disruption program), and the LBAM microencapsulated formulation was untested, and finally, microencapsule formulations are notoriously known for their short field life, weak and erratic performance. Furthermore it is possible that the LBAM microencapsulated formulation used in the government campaign was unfit for aerial delivery in urban areas; although pheromone is safe, the formulation used had microcapsules of very small diameter which made it into a possible inhalation hazard that seems to be linked to an increase in allergenic reactions of the population in the target area. This set of LBAM mating disruption aerial applications done by the government has created tremendous dissent of the public in general as well as of several sectors of the scientific community. Now, several years later, the affected communities as well as the nascent US pheromone industry (which provides safer, yet very effective, alternatives to the use of conventional pesticides) are still suffering the ripple effects of these disastrous Bay Area LBAM eradication campaigns.
But there are numerous, successful pest suppression programs that rely on aerial dispersal of pheromone mating disruptants. One of the largest pheromone mating disruption programs in the globe is Slow the Spread. Slow the Spread has been implemented across the spongy moth frontier from Wisconsin to North Carolina. The program area is located ahead of the advancing front of the spongy moth population. The STS program focuses on early detection and suppression of the low–level populations along this advancing front, disrupting the natural progress of population buildup and spread. Every year hundreds of thousands of acres are aerially sprayed with two pheromone spongy moth pheromone mating disruption formulations, Flakes and SPLAT. A single mating disruption formulation application promotes season-long suppression of spongy moth in the treated areas. With a crew of 8 people it was possible to aerially treat with SPLAT GM over of forest in a single day. The consortium of Federal and State participants have been able to do the following:
• decrease the new territory invaded by the spongy moth each year from to ;
• protect forests, forest–based industries, urban and rural parks, and private property; and
• avoid at least $22 million per year in damage and management costs.
It seems that the tremendous success of the Slow the Spread program is related to extremely well planned campaigns, which involves communication, transparency and clarity of objectives: in advance to an application STS holds meetings that include the area population in general, concerned citizens, public officials, scientists and technical personnel to discuss strategies of management of spongy moths in the areas of concern. There is a movement requesting that new government invasive species eradication campaigns model their pest suppression actions on the existing successful suppression programs like STS, and embrace a more effective policy of communication, transparency and clarity of objectives. With the involvement and education of the public, areawide eradication campaigns will be better planned and more able to deliver decisive end effective pest eradication actions. | 1 | Applied and Interdisciplinary Chemistry |
By chemically crosslinking the rings contained in the polyrotaxanes, sliding gels are obtained by being topologically interlocked by figure-of-eight crosslinks. Although it is a polymer network (gel), the rings are not fixed on the polyrotaxanes in the polymer network, the crosslinks of rings are able to freely move along the polymer chain. This can equalize the tension of the network, just like a pulley manner, which is referred to pulley effect. In chemical gels, the polymer chains are easy to be broken because the lengths of the heterogeneous polymer are limited or fixed. As a result, when the chemical gel is under a high pressure, the tension can not be equalized to the whole. On the opposite, the weakest part in the network will be broken easier, which leads to the damage of the gel. However, in the slide-ring materials, the polymer chain are able to pass through the figure-of-eight crosslinks which is like pulleys, and equalize the tension of network. As a result, slide-ring materials are applied to construct highly stretchable materials, up to 24 times its length when stretching and this process can be reversible. | 0 | Theoretical and Fundamental Chemistry |
In some cases, an additional rate enhancement is seen for the lighter isotope, possibly due to quantum mechanical tunnelling. This is typically only observed for reactions involving bonds to hydrogen atoms.
Tunneling occurs when a molecule penetrates through a potential energy barrier rather than over it. Although not allowed by the laws of classical mechanics, particles can pass through classically forbidden regions of space in quantum mechanics based on wave–particle duality.
Analysis of tunneling can be made using Bell's modification of the Arrhenius equation, which includes the addition of a tunneling factor, Q:
where A is the Arrhenius parameter, E is the barrier height and
where and
Examination of the β term shows exponential dependency on the mass of the particle. As a result, tunneling is much more likely for a lighter particle such as hydrogen. Simply doubling the mass of a tunneling proton by replacing it with its deuterium isotope drastically reduces the rate of such reactions. As a result, very large kinetic isotope effects are observed that can not be accounted for by differences in zero point energies.
In addition, the β term depends linearly with barrier width, 2a. As with mass, tunneling is greatest for small barrier widths. Optimal tunneling distances of protons between donor and acceptor atom is 0.4 Å. | 0 | Theoretical and Fundamental Chemistry |
The main properties of these conductors include:
* Good corrosion resistance of copper
* High tensile strength of steel
* Resistance against material fatigue | 1 | Applied and Interdisciplinary Chemistry |
Not all atoms attract electrons with the same force. The amount of "pull" an atom exerts on its electrons is called its electronegativity. Atoms with high electronegativitiessuch as fluorine, oxygen, and nitrogenexert a greater pull on electrons than atoms with lower electronegativities such as alkali metals and alkaline earth metals. In a bond, this leads to unequal sharing of electrons between the atoms, as electrons will be drawn closer to the atom with the higher electronegativity.
Because electrons have a negative charge, the unequal sharing of electrons within a bond leads to the formation of an electric dipole: a separation of positive and negative electric charge. Because the amount of charge separated in such dipoles is usually smaller than a fundamental charge, they are called partial charges, denoted as δ+ (delta plus) and δ− (delta minus). These symbols were introduced by Sir Christopher Ingold and Edith Hilda (Usherwood) Ingold in 1926. The bond dipole moment is calculated by multiplying the amount of charge separated and the distance between the charges.
These dipoles within molecules can interact with dipoles in other molecules, creating dipole-dipole intermolecular forces. | 0 | Theoretical and Fundamental Chemistry |
Faradays electrochemical paradox arises from his famous experiment of 1833. Concentrated nitric acid had been synthesized and although Faraday did not have a pH meter (the pH scale would not be developed for another seventy years), Faraday knew from various tests (e.g. taste and time of dissolution of calcite chips) that concentrated nitric acid was a much stronger acid than dilute nitric acid. Thus, when he placed the iron in the dilute acid, gas (now known to be hydrogen) was evolved from the surface and the iron dissolved. When he placed the iron in the concentrated nitric acid, he expected that it would dissolve at a higher rate, but no attack was observed. He then scratched the surface and a burst of bubbles was generated but then ceased. He stated that the surface had become "passive" and, therefore, he correctly assumed that the surface was oxidized and became covered with a protective oxide film. However, the oxide film did not dissolve and the attack did not continue in the concentrated nitric acid. This became known as Faradays electrochemical paradox, and was not solved until 1989.
The key to resolving the paradox is passivation. When the acid is concentrated enough, and because concentrated nitric acid is an oxidizing agent, the potential of the metal is raised to the point that a layer of metastable FeO forms on the surface and protects it from further corrosion, even though the pH is so low that stable FeO cannot exist. This explanation is supported by the observation that scratching the surface causes a burst of bubbles. Diluted nitric acid is not as strong an oxidizing agent and hence does not raise the potential of the metal to the extent that metastable FeO forms on the surface. In this case, the metal freely corrodes. | 0 | Theoretical and Fundamental Chemistry |
RPMs were originally developed for screening individuals and vehicles at secure facilities such as weapons laboratories. They were deployed at scrap metal facilities to detect radiation sources mixed among scrap that could contaminate a facility and result in a costly clean up. As part of the effort to thwart nuclear smuggling after the breakup of the Soviet Union, RPMs were deployed around that territory, and later around many other European and Asian countries, by the US Department of Energy (DOE) National Nuclear Security Administration (NNSA) Second Line of Defense Program (SLD) starting in the late 1990s. After the attack of 9/11, the US Customs and Border Protection (CBP) started the Radiation Portal Monitor Program (RPMP) to deploy RPMs around all US borders (land, sea and air). | 0 | Theoretical and Fundamental Chemistry |
In humans, DNA methylation occurs at the 5' position of the pyrimidine ring of the cytosine residues within CpG sites to form 5-methylcytosines. The presence of multiple methylated CpG sites in CpG islands of promoters causes stable silencing of genes. Silencing of a gene may be initiated by other mechanisms, but this is often followed by methylation of CpG sites in the promoter CpG island to cause the stable silencing of the gene. | 1 | Applied and Interdisciplinary Chemistry |
The germanium-vacancy center (Ge-V) is an optically active defect in diamond, which can be created by doping germanium into diamond during its growth or by implanting germanium ions into diamond after its growth. Its properties are similar to those of the silicon-vacancy center in diamond (SiV). Ge-V can behave as a single-photon source and shows potential for quantum and nanoscience applications due to its narrow zero-phonon line (ZPL) and minimal phononic-sideband (compared to that of the nitrogen-vacancy center (NV)). | 0 | Theoretical and Fundamental Chemistry |
The LH 2 is usually bound to photosystem II, but it can undock and bind PS I instead depending on light conditions. This behavior is controlled by reversible phosphorylation. This reaction represents a system for balancing the excitation energy between the two photosystems. | 0 | Theoretical and Fundamental Chemistry |
Chemokines (), or chemotactic cytokines, are a family of small cytokines or signaling proteins secreted by cells that induce directional movement of leukocytes, as well as other cell types, including endothelial and epithelial cells. In addition to playing a major role in the activation of host immune responses, chemokines are important for biological processes, including morphogenesis and wound healing, as well as in the pathogenesis of diseases like cancers.
Cytokine proteins are classified as chemokines according to behavior and structural characteristics. In addition to being known for mediating chemotaxis, chemokines are all approximately 8–10 kilodaltons in mass and have four cysteine residues in conserved locations that are key to forming their 3-dimensional shape.
These proteins have historically been known under several other names including the SIS family of cytokines, SIG family of cytokines, SCY family of cytokines, Platelet factor-4 superfamily or intercrines. Some chemokines are considered pro-inflammatory and can be induced during an immune response to recruit cells of the immune system to a site of infection, while others are considered homeostatic and are involved in controlling the migration of cells during normal processes of tissue maintenance or development. Chemokines are found in all vertebrates, some viruses and some bacteria, but none have been found in other invertebrates.
Chemokines have been classified into four main subfamilies: CXC, CC, CX3C and C. All of these proteins exert their biological effects by interacting with G protein-linked transmembrane receptors called chemokine receptors, that are selectively found on the surfaces of their target cells. | 1 | Applied and Interdisciplinary Chemistry |
Intensities of spectra of individual atoms or molecules typically vary linearly
with the numerical gas density. However, if gas densities are sufficiently
increased, quite generally contributions may also be observed that vary as density
squared, cubed... These are the collision-induced spectra of two-body (and
quite possibly three-body,...) collisional complexes. The collision-induced spectra
have sometimes been separated from the continua of individual atoms and
molecules, based on the characteristic density dependences. In other words, a
virial expansion in terms of powers of the numerical gas density is often
observable, just as this is widely known for the virial expansion of the equation
of state of compressed gases. The first term of the expansion, which is linear
in density, represents the ideal gas (or "ordinary) spectra where these
exist. (This first term vanishes for the infrared inactive gases,) And
the quadratic, cubic,... terms of the virial expansions arise from optical
transitions of binary, ternary,... intermolecular complexes, which are
(often unjustifyably) neglected in the ideal gas approximation of spectroscopy. | 0 | Theoretical and Fundamental Chemistry |
There is great variability in the use of the lost-wax method in East Asia. The casting method to make bronzes till the early phase of Eastern Zhou (770-256 ) was almost invariably section-mold process. Starting from around 600 , there was an unmistakable rise of lost-wax casting in the central plains of China, first witnessed in the Chu cultural sphere.
Further investigations have revealed this not to be the case as it is clear that the piece-mould casting method was the principal technique used to manufacture bronze vessels in China. The lost-wax technique did not appear in northern China until the 6th century BC. Lost-wax casting is known as rōgata in Japanese, and dates back to the Yayoi period, . The most famous piece made by cire perdue is the bronze image of Buddha in the temple of the Todaiji monastery at Nara. It was made in sections between 743 and 749, allegedly using seven tons of wax. | 1 | Applied and Interdisciplinary Chemistry |
Catastrophin (Catastrophe-related protein) is a term use to describe proteins that are associated with the disassembly of microtubules. Catastrophins affect microtubule shortening, a process known as microtubule catastrophe. | 1 | Applied and Interdisciplinary Chemistry |
Forging temperature is the temperature at which a metal becomes substantially more soft, but is lower than the melting temperature, such that it can be reshaped by forging. Bringing a metal to its forging temperature allows the metal's shape to be changed by applying a relatively small force, without creating cracks. For most metals, forging temperature is approximately 70% of the absolute temperature (usually measured in kelvins) of its melting point.
Selecting the maximum forging temperature allows metals to be forged more easily, lowering the forging pressure and thus the wear on metal-forming dies. The temperature at which a metal is forged can affect the homogeneity in microstructure and mechanical properties of forged products, which can highly affect the performance of products used in manufacturing. | 0 | Theoretical and Fundamental Chemistry |
Lichens demonstrate chemical defenses similar to those mentioned above. Their defenses act against herbivores and pathogens including bacterial, viral, and fungal varieties. To that end, a variety of chemicals are produced by the lichens mycobiont via hydrocarbons produced by the lichens photobiont. However, a single defensive chemical may serve multiple purposes. Usnic acid, for example, is implicated across anti-bacterial, -viral, and -fungal actions. Such defensive chemicals may be stored in various tissue types of the lichen thallus, or they may accumulate on the mycobiont hyphae as extracellular crystals.
Mycobiont-produced acids, including but not limited to, evernic, stictic, and squamatic acids exhibit allelopathy, more specifically, lichen defensive chemicals may inhibit a primary metabolic pathway within competing lichens, mosses, microorganisms, and vascular plants. Documented allelopathic targets include jack pine, white spruce, and garden variety tomato, cabbage, lettuce, and pepper plants. Antimicrobial efforts of lichen are also mediated by various mycobiont-produced acids such as lecanoric and gyrophoric. Similar defensive chemicals were found to inhibit herbivores and insects. Some of these lichen defensive compounds show pharmaceutical potential, too.
In 2004 the death of hundreds of elk near Rawlins, Wyoming was linked to consumption of tumbleweed shield lichen (Xanthoparmelia chlorochroa). This strangely powerful chemical defense is irregular given that such poisoning is very rare while the consumption of this lichen is fairly regular. | 1 | Applied and Interdisciplinary Chemistry |
On 16 September 2015, first linking was completed of rivers Krishna and Godavari. It is still under review. But it isn't considered as a true river interlinking as it is just a small lift irrigation with few lines of pipes. | 1 | Applied and Interdisciplinary Chemistry |
Lipofuscin is the name given to fine yellow-brown pigment granules composed of lipid-containing residues of lysosomal digestion. It is considered to be one of the aging or "wear-and-tear" pigments, found in the liver, kidney, heart muscle, retina, adrenals, nerve cells, and ganglion cells. | 1 | Applied and Interdisciplinary Chemistry |
The boat conformation (C, below) is a transition state, allowing the interconversion between two different twist-boat conformations. While the boat conformation is not necessary for interconversion between the two chair conformations of cyclohexane, it is often included in the reaction coordinate diagram used to describe this interconversion because its energy is considerably lower than that of the half-chair, so any molecule with enough energy to go from twist-boat to chair also has enough energy to go from twist-boat to boat. Thus, there are multiple pathways by which a molecule of cyclohexane in the twist-boat conformation can achieve the chair conformation again. | 0 | Theoretical and Fundamental Chemistry |
A typical XPS spectrum is a plot of the number of electrons detected at a specific binding energy. Each element produces a set of characteristic XPS peaks. These peaks correspond to the electron configuration of the electrons within the atoms, e.g., 1s, 2s, 2p, 3s, etc. The number of detected electrons in each peak is directly related to the amount of element within the XPS sampling volume. To generate atomic percentage values, each raw XPS signal is corrected by dividing the intensity by a relative sensitivity factor (RSF), and normalized over all of the elements detected. Since hydrogen is not detected, these atomic percentages exclude hydrogen. | 0 | Theoretical and Fundamental Chemistry |
Uranium-lead dating is usually performed on the mineral zircon (ZrSiO), though other materials can be used. Zircon incorporates uranium atoms into its crystalline structure as substitutes for zirconium, but strongly rejects lead. It has a high blocking temperature, is resistant to mechanical weathering and is chemically inert. Zircon also forms multiple crystal layers during metamorphic events, which each may record an isotopic age of the event. These can be dated by a SHRIMP ion microprobe.
One of the advantages of this method is that any sample provides two clocks, one based on uranium-235s decay to lead-207 with a half-life of about 703 million years, and one based on uranium-238s decay to lead-206 with a half-life of about 4.5 billion years, providing a built-in crosscheck that allows accurate determination of the age of the sample even if some of the lead has been lost. | 0 | Theoretical and Fundamental Chemistry |
The light chain gene has three gene segments. These include: the light chain variable region (V), joining region (J), and constant region (C) gene segments. The variable region of light is therefore encoded by the rearrangement of VJ segments. The light chain can be either kappa,κ or lambda,λ. This process takes place at the level of mRNAs processing. Random rearrangements and recombinations of the gene segments at DNA level to form one kappa or lambda light chain occurs in an orderly fashion. As a result, "a functional variable region gene of a light chain contains two coding segments that are separated by a non-coding DNA sequence in unrearranged germ-line DNA" (Barbara et al., 2007). | 1 | Applied and Interdisciplinary Chemistry |
The ETS family is present throughout the body and is involved in a wide variety of functions including the regulation of cellular differentiation, cell cycle control, cell migration, cell proliferation, apoptosis (programmed cell death) and angiogenesis.
Multiple ETS factors have been found to be associated with cancer, such as through gene fusion. For example, the ERG ETS transcription factor is fused to the EWS gene, resulting in a condition called Ewing's sarcoma. The fusion of TEL to the JAK2 protein results in early pre-B acute lymphoid leukaemia. ERG and ETV1 are known gene fusions found in prostate cancer.
In addition, ETS factors, e.g. the vertebrate Etv1 and the invertebrate Ast-1, have been shown to be important players in the specification and differentiation of dopaminergic neurons in both C. elegans and olfactory bulbs of mice. | 1 | Applied and Interdisciplinary Chemistry |
In industrial cleaning applications, cavitation has sufficient power to overcome the particle-to-substrate adhesion forces, loosening contaminants. The threshold pressure required to initiate cavitation is a strong function of the pulse width and the power input. This method works by generating acoustic cavitation in the cleaning fluid, picking up and carrying contaminant particles away in the hope that they do not reattach to the material being cleaned (which is a possibility when the object is immersed, for example in an ultrasonic cleaning bath). The same physical forces that remove contaminants also have the potential to damage the target being cleaned. | 1 | Applied and Interdisciplinary Chemistry |
Combination therapy with two or more antibiotics are often used in an effort to treat multi-drug resistant Gram-negative bacteria. | 1 | Applied and Interdisciplinary Chemistry |
The intramolecular Heck reaction (IMHR) in chemistry is the coupling of an aryl or alkenyl halide with an alkene in the same molecule. The reaction may be used to produce carbocyclic or heterocyclic organic compounds with a variety of ring sizes. Chiral palladium complexes can be used to synthesize chiral intramolecular Heck reaction products in non-racemic form. | 0 | Theoretical and Fundamental Chemistry |
These works concern, on the one hand, consideration of the basics of the method and analysis of the nature of errors, and, on the other hand, experimental determination of the age of uranites from different pegmatite veins both by the uranium/lead ratio and by Lan's oxygen method, which was developed and refined in the works of V.G. Khlopin. The scientist supervised research in this direction in the Radium Institute - on helium and lead methods, which gave the determination of the geologic age of some formations. The work (with E. K. Gerling and E. M. Ioffe) on helium migration from minerals and rocks and the influence of the gas phase on this process should be attributed to this cycle. | 0 | Theoretical and Fundamental Chemistry |
The scientific activities of the IIR are organised into five Sections, each of which is divided into two Commissions; there are thus 10 Commissions: | 0 | Theoretical and Fundamental Chemistry |
The one-dimensional infinite square well of length L is a model for a one-dimensional box with the potential energy:
It is a standard model-system in quantum mechanics for which the solution for a single particle is well known. Since the potential inside the box is uniform, this model is referred to as 1D uniform gas, even though the actual number density profile of the gas can have nodes and anti-nodes when the total number of particles is small.
The levels are labelled by a single quantum number n and the energies are given by:
where is the zero-point energy (which can be chosen arbitrarily as a form of gauge fixing), the mass of a single fermion, and is the reduced Planck constant.
For N fermions with spin- in the box, no more than two particles can have the same energy, i.e., two particles can have the energy of , two other particles can have energy and so forth. The two particles of the same energy have spin (spin up) or − (spin down), leading to two states for each energy level. In the configuration for which the total energy is lowest (the ground state), all the energy levels up to n = N/2 are occupied and all the higher levels are empty.
Defining the reference for the Fermi energy to be , the Fermi energy is therefore given by
where is the floor function evaluated at n = N/2. | 0 | Theoretical and Fundamental Chemistry |
PSI accepts electrons from plastocyanin and transfers them either to NADPH (noncyclic electron transport) or back to cytochrome bf (cyclic electron transport):
plastocyanin → P700 → P700 → FNR → NADPH
bf ← phylloquinone
PSI, like PSII, is a complex, highly organized transmembrane structure that contains antenna chlorophylls, a reaction center (P700), phylloquinone, and a number of iron-sulfur proteins that serve as intermediate redox carriers.
The light-harvesting system of PSI uses multiple copies of the same transmembrane proteins used by PSII. The energy of absorbed light (in the form of delocalized, high-energy electrons) is funneled into the reaction center, where it excites special chlorophyll molecules (P700, with maximum light absorption at 700 nm) to a higher energy level. The process occurs with astonishingly high efficiency.
Electrons are removed from excited chlorophyll molecules and transferred through a series of intermediate carriers to ferredoxin, a water-soluble electron carrier. As in PSII, this is a solid-state process that operates with 100% efficiency.
There are two different pathways of electron transport in PSI. In noncyclic electron transport, ferredoxin carries the electron to the enzyme ferredoxin reductase (FNR) that reduces to NADPH. In cyclic electron transport, electrons from ferredoxin are transferred (via plastoquinol) to a proton pump, cytochrome bf. They are then returned (via plastocyanin) to P700. NADPH and ATP are used to synthesize organic molecules from . The ratio of NADPH to ATP production can be adjusted by adjusting the balance between cyclic and noncyclic electron transport.
It is noteworthy that PSI closely resembles photosynthetic structures found in green sulfur bacteria, just as PSII resembles structures found in purple bacteria. | 0 | Theoretical and Fundamental Chemistry |
Host response is defined as the "response of the host organism (local and systemic) to the implanted material or device". Most materials will have a reaction when in contact with the human body. The success of a biomaterial relies on the host tissue's reaction with the foreign material. Specific reactions between the host tissue and the biomaterial can be generated through the biocompatibility of the material. | 1 | Applied and Interdisciplinary Chemistry |
Tritium's decay product helium-3 has a very large cross section (5330 barns) for reacting with thermal neutrons, expelling a proton; hence, it is rapidly converted back to tritium in nuclear reactors. | 0 | Theoretical and Fundamental Chemistry |
Since facultative anaerobes are able to grow in both the presence and absence of oxygen, they can survive in many different environments, adapt easily to changing conditions, and thus have a selective advantage over other bacteria. As a result, most life-threatening pathogens are facultative anaerobes.
The ability of facultative anaerobic pathogens to survive without oxygen is important since their infection is shown to reduce oxygen levels in their host's gut tissue. Moreover, the ability of facultative anaerobes to limit oxygen levels at infection sites is beneficial to them and other bacteria, as dioxygen can form reactive oxygen species (ROS). These species are toxic to bacteria and can damage their DNA, among other constituents. | 1 | Applied and Interdisciplinary Chemistry |
A number of methods of measuring distribution coefficients have been developed, including the shake-flask, separating funnel method, reverse-phase HPLC, and pH-metric techniques. | 0 | Theoretical and Fundamental Chemistry |
In the context of coding theory, can be constructed by measuring the expected number of extra bits required to code samples from using a code optimized for rather than the code optimized for . | 0 | Theoretical and Fundamental Chemistry |
Biochemistry is the study of the chemical processes in living organisms. It deals with the structure and function of cellular components such as proteins, carbohydrates, lipids, nucleic acids and other biomolecules.
Articles related to biochemistry include:
__NOTOC__ | 1 | Applied and Interdisciplinary Chemistry |
A thermal power station is a type of power station in which heat energy is converted to electrical energy. In a steam-generating cycle heat is used to boil water in a large pressure vessel to produce high-pressure steam, which drives a steam turbine connected to an electrical generator. The low-pressure exhaust from the turbine enters a steam condenser where it is cooled to produce hot condensate which is recycled to the heating process to generate more high pressure steam. This is known as a Rankine cycle.
The design of thermal power stations depends on the intended energy source: fossil fuel, nuclear and geothermal power, solar energy, biofuels, and waste incineration are all used. Certain thermal power stations are also designed to produce heat for industrial purposes; for district heating; or desalination of water, in addition to generating electrical power.
Fuels such as natural gas or oil can also be burnt directly in gas turbines (internal combustion). These plants can be of the open cycle or the more efficient combined cycle type. | 1 | Applied and Interdisciplinary Chemistry |
Surface diffusion may be studied by a variety of techniques, including both direct and indirect observations. Two experimental techniques that have proved very useful in this area of study are field ion microscopy and scanning tunneling microscopy. By visualizing the displacement of atoms or clusters over time, it is possible to extract useful information regarding the manner in which the relevant species diffuse-both mechanistic and rate-related information. In order to study surface diffusion on the atomistic scale it is unfortunately necessary to perform studies on rigorously clean surfaces and in ultra high vacuum (UHV) conditions or in the presence of small amounts of inert gas, as is the case when using He or Ne as imaging gas in field-ion microscopy experiments. | 0 | Theoretical and Fundamental Chemistry |
Nucleobases, such as guanine and adenine, can be synthesized from simple carbon and nitrogen sources, such as hydrogen cyanide (HCN) and ammonia. Formamide produces all four ribonucleotides when warmed with terrestrial minerals. Formamide is ubiquitous in the Universe, produced by the reaction of water and HCN. It can be concentrated by the evaporation of water. HCN is poisonous only to aerobic organisms (eukaryotes and aerobic bacteria), which did not yet exist. It can play roles in other chemical processes such as the synthesis of the amino acid glycine.
DNA and RNA components including uracil, cytosine and thymine can be synthesized under outer space conditions, using starting chemicals such as pyrimidine found in meteorites. Pyrimidine may have been formed in red giant stars or in interstellar dust and gas clouds. All four RNA-bases may be synthesized from formamide in high-energy density events like extraterrestrial impacts.
Other pathways for synthesizing bases from inorganic materials have been reported. Freezing temperatures are advantageous for the synthesis of purines, due to the concentrating effect for key precursors such as hydrogen cyanide. However, while adenine and guanine require freezing conditions for synthesis, cytosine and uracil may require boiling temperatures. Seven amino acids and eleven types of nucleobases formed in ice when ammonia and cyanide were left in a freezer for 25 years. S-triazines (alternative nucleobases), pyrimidines including cytosine and uracil, and adenine can be synthesized by subjecting a urea solution to freeze-thaw cycles under a reductive atmosphere, with spark discharges as an energy source. The explanation given for the unusual speed of these reactions at such a low temperature is eutectic freezing, which crowds impurities in microscopic pockets of liquid within the ice, causing the molecules to collide more often.] | 0 | Theoretical and Fundamental Chemistry |
In mammals, UPR has mostly been studied using transfection with a truncated, dysfunctional mitochondrial enzyme (OTCΔ) that does not fold correctly after translocation into the mitochondrial matrix. Using this approach, several components of the mammalian UPR have been identified including the mitochondrial chaperone heat shock protein 60 (Hsp60), the mitochondrial caseinolytic peptidase ClpP, the transcription factor Chop and the kinases c-Jun N-terminal kinase (JNK) and the interferon-induced, double-stranded RNA-activated protein kinase (Pkr).
The appropriately named activating transcription factor associated with stress (ATFS-1) is one of the primary transcription factors required for UPR activation in worms. ATFS-1 has a nuclear localization sequence that allows it to be imported into the nucleus as well as an N-terminal mitochondrial targeting sequence (MTS) that allows for import into the mitochondria. In healthy cells, ATFS-1 is preferentially targeted to the mitochondrial matrix where it is degraded by the Lon protease. The MTS on ATFS-1 is predicted by Mitofates to be substantially weaker than most MTSs which would allow it to be sensitive to subtle mitochondrial dysfunction. Following mitochondrial stress, ATFS-1 mitochondrial import efficiency is decreased resulting in a cytoplasmic accumulation of ATFS-1. Subsequently, ATFS-1 will enter the nucleus via its nuclear transport signal. In the nucleus, ATFS-1 has a broad transcriptional regulation as it will: attenuate OXPHOS gene expression in both the nucleus and mitochondria, upregulate chaperones and proteases to re-establish mitochondrial proteostasis, increase ROS detoxification, and increase mitochondrial import machinery. | 1 | Applied and Interdisciplinary Chemistry |
The preinitiation complex (abbreviated PIC) is a complex of approximately 100 proteins that is necessary for the transcription of protein-coding genes in eukaryotes and archaea. The preinitiation complex positions RNA polymerase II (Pol II) at gene transcription start sites, denatures the DNA, and positions the DNA in the RNA polymerase II active site for transcription.
The minimal PIC includes RNA polymerase II and six general transcription factors: TFA, TFB, TFD, TFE, TFF, and TFH. Additional regulatory complexes (such as the mediator coactivator and chromatin remodeling complexes) may also be components of the PIC.
Preinitiation complexes are also formed during RNA Polymerase I and RNA Polymerase III transcription. | 1 | Applied and Interdisciplinary Chemistry |
Advantages of screening low molecular weight fragment based libraries over traditional higher molecular weight chemical libraries are several. These include:
* More hydrophilic hits in which hydrogen bonding is more likely to contribute to affinity (enthalpically driven binding). It is generally much easier to increase affinity by adding hydrophobic groups (entropically driven binding); starting with a hydrophilic ligand increases the chances that the final optimized ligand will not be too hydrophobic (log P < 5).
* Higher ligand efficiency so that the final optimized ligand will more likely be relatively low in molecular weight (MW < 500).
* Since two to three fragments in theory can be combined to form an optimized ligand, screening a fragment library of N compounds is equivalent to screening N - N compounds in a traditional library.
* Fragments are less likely to contain sterically blocking groups that interfere with an otherwise favorable ligand-protein interaction, increasing the combinatorial advantage of a fragment library even further. | 1 | Applied and Interdisciplinary Chemistry |
If the gas is ideal, both the initial (, , ) and final (, , ) conditions follow the Ideal Gas Law, so that initially
and then, after the tap is opened,
Here is the number of moles of gas and is the molar ideal gas constant. Because the internal energy does not change and the internal energy of an ideal gas is solely a function of temperature, the temperature of the gas does not change; therefore . This implies that
Therefore if the volume doubles, the pressure halves.
The fact that the temperature does not change makes it easy to compute the change in entropy of the universe for this process. | 0 | Theoretical and Fundamental Chemistry |
petite (ρ–) is a mutant first discovered in the yeast Saccharomyces cerevisiae. Due to the defect in the respiratory chain, petite yeast are unable to grow on media containing only non-fermentable carbon sources (such as glycerol or ethanol) and form small colonies when grown in the presence of fermentable carbon sources (such as glucose). The petite phenotype can be caused by the absence of, or mutations in, mitochondrial DNA (termed "cytoplasmic Petites"), or by mutations in nuclear-encoded genes involved in oxidative phosphorylation. A neutral petite produces all wild type progeny when crossed with wild type.
petite mutations can be induced using a variety of mutagens, including DNA intercalating agents, as well as chemicals that can interfere with DNA synthesis in growing cells. Mutagens that create Petites are implicated in increased rates of degenerative diseases and in the aging process. | 1 | Applied and Interdisciplinary Chemistry |
In the context of chemical engineering, process integration can be defined as a holistic approach to process design and optimization, which exploits the interactions between different units in order to employ resources effectively and minimize costs.
Process integration is not limited to the design of new plants, but it also covers retrofit design (e.g. new units to be installed in an old plant) and the operation of existing systems. Nick Hallale (2001) explains that with process integration, industries are making more money from their raw materials and capital assets while becoming cleaner and more sustainable.
The main advantage of process integration is to consider a system as a whole (i.e. integrated or holistic approach) in order to improve their design and/or operation. In contrast, an analytical approach would attempt to improve or optimize process units separately without necessarily taking advantage of potential interactions among them.
For instance, by using process integration techniques it might be possible to identify that a process can use the heat rejected by another unit and reduce the overall energy consumption, even if the units are not running at optimum conditions on their own. Such an opportunity would be missed with an analytical approach, as it would seek to optimize each unit, and thereafter it wouldn’t be possible to re-use the heat internally.
Typically, process integration techniques are employed at the beginning of a project (e.g. a new plant or the improvement of an existing one) to screen out promising options to optimize the design and/or operation of a process plant.
Also it is often employed, in conjunction with simulation and mathematical optimization tools to identify opportunities in order to better integrate a system (new or existing) and reduce capital and/or operating costs.
Most process integration techniques employ Pinch analysis or Pinch Tools to evaluate several processes as a whole system. Therefore, strictly speaking, both concepts are not the same, even if in certain contexts they are used interchangeably. The review by Nick Hallale (2001) explains that in the future, several trends are to be expected in the field. In the future, it seems probable that the boundary between targets and design will be blurred and that these will be based on more structural information regarding the process network. Second, it is likely that we will see a much wider range of applications of process integration. There is still much work to be carried out in the area of separation, not only in complex distillation systems, but also in mixed types of separation systems. This includes processes involving solids, such as flotation and crystallization. The use of process integration techniques for reactor design has seen rapid progress, but is still in its early stages. Third, a new generation of software tools is expected. The emergence of commercial software for process integration is fundamental to its wider application in process design. | 1 | Applied and Interdisciplinary Chemistry |
The aniline point of an oil is defined as the minimum temperature at which equal volumes of aniline () and lubricant oil are miscible, i.e. form a single phase upon mixing.
The value gives an approximation for the content of aromatic compounds in the oil, since the miscibility of aniline, which is also an aromatic compound suggests the presence of similar (i.e. aromatic) compounds in the oil. The lower the aniline point, the greater is the content of aromatic compounds in the oil.
The aniline point serves as a reasonable proxy for aromaticity of oils consisting mostly of saturated hydrocarbons (i.e. alkanes, paraffins) or unsaturated compounds (mostly aromatics). Significant chemical functionalization of the oil (chlorination, sulfonation, etc.) can interfere with the measurement, due to changes to the solvency of the functionalized oil.
Aniline point indicates if an oil is likely to damage elastomers (rubber compounds) that come in contact with the oil. | 0 | Theoretical and Fundamental Chemistry |
Paleosalinity (or palaeosalinity) is the salinity of the global ocean or of an ocean basin at a point in geological history. | 0 | Theoretical and Fundamental Chemistry |
Given an increasing wartime shortage of tin, his team also commenced investigations into the production of titanium tetrachloride from local resources as an alternative material to replace stannic (tin) chloride in a number of applications. Previously prepared overseas by chlorinating titanium white pigment (titanium dioxide), McTaggart's work demonstrated that the potential expense of proposals to import titanium white could be avoided through development of his process in which rutile sand, briquetted with coal or charcoal, was chlorinated directly. At first operated on a pilot-plant scale with Australian rutile sand replacing titanium pigment, the process was adopted for large-scale manufacture. | 0 | Theoretical and Fundamental Chemistry |
When the tissues release carbon dioxide into the bloodstream, around 10% is dissolved into the plasma. The rest of the carbon dioxide is carried either directly or indirectly by hemoglobin. Approximately 10% of the carbon dioxide carried by hemoglobin is in the form of carbaminohemoglobin. This carbaminohemoglobin is formed by the reaction between carbon dioxide and an amino (-NH) residue from the globin molecule, resulting in the formation of a carbamino residue (-NH.COO). The rest of the carbon dioxide is transported in the plasma as bicarbonate anions. | 1 | Applied and Interdisciplinary Chemistry |
Tertiary phosphines characteristically oxidize to give phosphine oxides with the formula RPO. The reaction with oxygen is spin-forbidden but still proceeds at sufficient rate that samples of tertiary phosphines are characteristically contaminated with phosphine oxides. Qualitatively, the rates of oxidation are higher for trialkyl vs triarylphosphines. Faster still are oxidations using hydrogen peroxide. Primary and secondary phosphines also oxidize, but the product(s) are subject to tautomerization and further oxidation.
Tertiary phosphines characteristically oxidize to give phosphine sulfides.
The reducing properties of organophosphiines is also illustrated in the Staudinger reduction for the conversion of organic azides to amines and in the Mitsunobu reaction for converting alcohols into esters. In these processes, the phosphine is oxidized to phosphorus(V). Phosphines have also been found to reduce activated carbonyl groups, for instance the reduction of an α-keto ester to an α-hydroxy ester in scheme 2. In the proposed reaction mechanism, the first proton is on loan from the methyl group in trimethylphosphine (triphenylphosphine does not react). | 0 | Theoretical and Fundamental Chemistry |
Squalene is a biochemical precursor to both steroids and hopanoids. For sterols, the squalene conversion begins with oxidation (via squalene monooxygenase) of one of its terminal double bonds, resulting in 2,3-oxidosqualene. It then undergoes an enzyme-catalysed cyclisation to produce lanosterol, which can be elaborated into other steroids such as cholesterol and ergosterol in a multistep process by the removal of three methyl groups, the reduction of one double bond by NADPH and the migration of the other double bond. In many plants, this is then converted into stigmasterol, while in many fungi, it is the precursor to ergosterol.
The biosynthetic pathway is found in many bacteria, and most eukaryotes, though has not been found in Archaea. | 1 | Applied and Interdisciplinary Chemistry |
The ancient phrase survives in modified form in the British Medical Journals long-established "Materia Non Medica" column, the title indicating non-medical material that doctors wished to report from their travels and other experiences. For example, in June 1977, the journal contained "Materia Non Medica" reports on an exhibition at the Whitechapel Art Gallery by a London physician, the making of matches by hand in an Indian village by a missionary general practitioner, and a cruise to Jamaica by a University of the West Indies lecturer in medicine. | 1 | Applied and Interdisciplinary Chemistry |
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