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Electrostatic interaction: In an aqueous environment, the oppositely charged groups in amino acid side chains within the active site and substrates attract each other, which is termed electrostatic interaction. For example, when a carboxylic acid (R-COOH) dissociates into RCOO and H ions, COO will attract positively charged groups such as protonated guanidine side chain of arginine.
Hydrogen bond: A hydrogen bond is a specific type of dipole-dipole interaction between a partially positive hydrogen atom and a partially negative electron donor that contain a pair of electrons such as oxygen, fluorine and nitrogen. The strength of hydrogen bond depends on the chemical nature and geometric arrangement of each group.
Van der Waals force: Van der Waals force is formed between oppositely charged groups due to transient uneven electron distribution in each group. If all electrons are concentrated at one pole of the group this end will be negative, while the other end will be positive. Although the individual force is weak, as the total number of interactions between the active site and substrate is massive the sum of them will be significant.
Hydrophobic interaction: Non-polar hydrophobic groups tend to aggregate together in the aqueous environment and try to leave from polar solvent. These hydrophobic groups usually have long carbon chain and do not react with water molecules. When dissolving in water a protein molecule will curl up into a ball-like shape, leaving hydrophilic groups in outside while hydrophobic groups are deeply buried within the centre. | 1 | Applied and Interdisciplinary Chemistry |
A desmut solution can be applied to the surface of aluminium to remove contaminates. Nitric acid is typically used to remove smut (residue), but is being replaced because of environmental concerns. | 1 | Applied and Interdisciplinary Chemistry |
As one of the most famous scientists in history, Marie Curie has become an icon in the scientific world and has received tributes from across the globe, even in the realm of pop culture. She also received many honorary degrees from universities across the world.
Marie Curie was the first woman to win a Nobel Prize, the first person to win two Nobel Prizes, the only woman to win in two fields, and the only person to win in multiple sciences. Awards and honours that she received include:
* Nobel Prize in Physics (1903, with her husband Pierre Curie and Henri Becquerel)
* Davy Medal (1903, with Pierre)
* Matteucci Medal (1904, with Pierre)
* Actonian Prize (1907)
* Elliott Cresson Medal (1909)
* Legion of Honour (1909, rejected)
* Nobel Prize in Chemistry (1911)
* Civil Order of Alfonso XII (1919)
* Franklin Medal of the American Philosophical Society (1921)
* Order of the White Eagle (2018, posthumously)
Entities that have been named after Marie Curie include:
* The curie (symbol Ci), a unit of radioactivity, is named in honour of her and Pierre Curie (although the commission which agreed on the name never clearly stated whether the standard was named after Pierre, Marie, or both).
* The element with atomic number 96 was named curium (symbol Cm).
* Three radioactive minerals are also named after the Curies: curite, sklodowskite, and cuprosklodowskite.
* The Marie Skłodowska-Curie Actions fellowship program of the European Union for young scientists wishing to work in a foreign country
* In 2007, a metro station in Paris was renamed to honour both of the Curies.
* The sole Polish nuclear reactor in operation, the research reactor Maria
* The 7000 Curie asteroid
* Marie Curie, a registered charitable organisation in the United Kingdom
* The IEEE Marie Sklodowska-Curie Award, an international award presented for outstanding contributions to the field of nuclear and plasma sciences and engineering, was established by the Institute of Electrical and Electronics Engineers in 2008.
* The Marie Curie Medal, an annual science award established in 1996 and conferred by the Polish Chemical Society
* The Marie Curie-Sklodowska Medal and Prize, an annual award conferred by the London-based Institute of Physics for distinguished contributions to physics education
*Maria Curie-Skłodowska University in Lublin, Poland
*Pierre and Marie Curie University in Paris
*Maria Skłodowska-Curie National Research Institute of Oncology in Poland
*École élémentaire Marie-Curie in London, Ontario, Canada; Curie Metropolitan High School in Chicago, United States; Marie Curie High School in Ho Chi Minh City, Vietnam; Lycée français Marie Curie de Zurich, Switzerland; see Lycée Marie Curie for a list of other schools named after her
Numerous biographies are devoted to her, including:
* Ève Curie (Marie Curies daughter), Madame Curie', 1938.
* Françoise Giroud, Marie Curie: A Life, 1987.
* Barbara Goldsmith, Obsessive Genius: The Inner World of Marie Curie, 2005.
* Lauren Redniss, Radioactive: Marie and Pierre Curie, a Tale of Love and Fallout, 2011, adapted into the 2019 British film.
Marie Curie has been the subject of a number of films:
* 1943: Madame Curie, a U.S. Oscar-nominated film by Mervyn LeRoy starring Greer Garson.
* 1997: Les Palmes de M. Schutz, a French film adapted from a play of the same title, and directed by Claude Pinoteau. Marie Curie is played by Isabelle Huppert.
* 2014: Marie Curie, une femme sur le front, a French-Belgian film, directed by and starring Dominique Reymond.
* 2016: Marie Curie: The Courage of Knowledge, a European co-production by Marie Noëlle starring Karolina Gruszka.
* 2016: Super Science Friends, an American Internet animated series created by Brett Jubinville featuring Hedy Gregor as Marie Curie.
* 2019: Radioactive, a British film by Marjane Satrapi starring Rosamund Pike.
Curie is the subject of the 2013 play False Assumptions by Lawrence Aronovitch, in which the ghosts of three other women scientists observe events in her life. Curie has also been portrayed by Susan Marie Frontczak in her play, Manya: The Living History of Marie Curie, a one-woman show which by 2014 had been performed in 30 U.S. states and nine countries. Lauren Gundersons 2019 play The Half-Life of Marie Curie' portrays Curie during the summer after her 1911 Nobel Prize victory, when she was grappling with depression and facing public scorn over the revelation of her affair with Paul Langevin.
Curie has appeared on more than 600 postage stamps in many countries across the world.
Between 1989–1996, she was featured on a 20,000-zloty banknote designed by Andrzej Heidrich. In 2011, a commemorative 20-zloty banknote depicting Curie was issued by the National Bank of Poland on the 100th anniversary of the scientist receiving the Nobel Prize in Chemistry.
In 1994, the Bank of France issued a 500-franc banknote featuring Marie and Pierre Curie. As of the middle of 2024, Curie is depicted on French 50 euro cent coins to commemorate her impact on French history. | 0 | Theoretical and Fundamental Chemistry |
Ionic bonding is a type of chemical bonding that involves the electrostatic attraction between oppositely charged ions, or between two atoms with sharply different electronegativities, and is the primary interaction occurring in ionic compounds. It is one of the main types of bonding, along with covalent bonding and metallic bonding. Ions are atoms (or groups of atoms) with an electrostatic charge. Atoms that gain electrons make negatively charged ions (called anions). Atoms that lose electrons make positively charged ions (called cations). This transfer of electrons is known as electrovalence in contrast to covalence. In the simplest case, the cation is a metal atom and the anion is a nonmetal atom, but these ions can be more complex, e.g. molecular ions like or . In simpler words, an ionic bond results from the transfer of electrons from a metal to a non-metal to obtain a full valence shell for both atoms.
Clean ionic bonding — in which one atom or molecule completely transfers an electron to another — cannot exist: all ionic compounds have some degree of covalent bonding or electron sharing. Thus, the term "ionic bonding" is given when the ionic character is greater than the covalent character – that is, a bond in which there is a large difference in electronegativity between the two atoms, causing the bonding to be more polar (ionic) than in covalent bonding where electrons are shared more equally. Bonds with partially ionic and partially covalent characters are called polar covalent bonds.
Ionic compounds conduct electricity when molten or in solution, typically not when solid. Ionic compounds generally have a high melting point, depending on the charge of the ions they consist of. The higher the charges the stronger the cohesive forces and the higher the melting point. They also tend to be soluble in water; the stronger the cohesive forces, the lower the solubility. | 0 | Theoretical and Fundamental Chemistry |
In some cells certain amino acids can be depleted and thus affect translation efficiency. For instance, activated T cells secrete interferon-γ which triggers intracellular tryptophan shortage by upregulating the indoleamine 2,3-dioxygenase 1 (IDO1) enzyme. Surprisingly, despite tryptophan depletion, in-frame protein synthesis continues across tryptophan codons. This is achieved by incorporation of phenylalanine instead of tryptophan. The resulting peptides are called W>F "substitutants". Such W>F substitutants are abundant in certain cancer types and have been associated with increased IDO1 expression. Functionally, W>F substitutants can impair protein activity. | 1 | Applied and Interdisciplinary Chemistry |
In 1964 Impalco decided to offer Fulmer for sale.
At that time Dr (later Sir) James Taylor, who was Chairman of Imperial Metal Industries (IMI), was also the Honorary Treasurer of the Institute of Physics and the Physical Society (IOP). He proposed that IOP should acquire Fulmer and thus become the first Learned Society to own a commercial research company. The Council of the IOP, in recommending the purchase of Fulmer to its membership, expressed the intention that, after providing for equipment needs, income from the investment in Fulmer was to be used to support the scientific and educational work of the IOP. The purchase was made possible by a grant from ICI, to be repaid over ten years from Fulmer profits. Thus, in 1965, IOP became the owner of Fulmer. | 1 | Applied and Interdisciplinary Chemistry |
A valve exerciser is a device that operates a valve periodically in order to prevent it from becoming so stiff that it no longer works. Valves that are left in a static position for a long time may corrode, or become blocked with mineral deposits. Electronic valve exercisers can provide information on the health of a valve by monitoring the required operating torque. | 1 | Applied and Interdisciplinary Chemistry |
The process is named after the Italian physician, physicist, biologist and philosopher Luigi Galvani (9 September 1737 – 4 December 1798). The earliest known example of galvanized iron was discovered on 17th-century Indian armour in the Royal Armouries Museum collection in the United Kingdom.
The term "galvanized" can also be used metaphorically of any stimulus which results in activity by a person or group of people.
In modern usage, the term "galvanizing" has largely come to be associated with zinc coatings, to the exclusion of other metals. Galvanic paint, a precursor to hot-dip galvanizing, was patented by Stanislas Sorel, of Paris, on June 10, 1837, as an adoption of a term from a highly fashionable field of contemporary science, despite having no evident relation to it. | 1 | Applied and Interdisciplinary Chemistry |
The armed/disarmed approach to glycosylation is an effective way to prevent sugar molecules from self-glycosylation when synthesizing disaccharides. This approach was first recognized when acetylated sugars only acted as glycosyl acceptors when reacted with benzylated sugars. The acetylated sugars were termed “disarmed” while the benzylated sugars were termed “armed”. | 0 | Theoretical and Fundamental Chemistry |
Large surface-to-volume ratios and low coordination of surface atoms are primary reasons for the unique reactivity of nanoclusters. Thus, nanoclusters are widely used as catalysts. Gold nanocluster is an excellent example of a catalyst. While bulk gold is chemically inert, it becomes highly reactive when scaled down to nanometer scale. One of the properties that govern cluster reactivity is electron affinity. Chlorine has highest electron affinity of any material in the periodic table. Clusters can have high electron affinity and nanoclusters with high electron affinity are classified as super halogens. Super halogens are metal atoms at the core surrounded by halogen atoms. | 0 | Theoretical and Fundamental Chemistry |
* Reiner Salzer (Chair), TU Dresden, Dresden, Germany
*Pavel Drašar (Past-Chair), University of Chemistry and Technology, Prague, Czech Republic
*Evangelia Varella (Secretary), University of Thessaloniki, Thessaloniki, Greece
*a number of members | 1 | Applied and Interdisciplinary Chemistry |
(E)-4-Hydroxy-3-methyl-but-2-enyl pyrophosphate (HMBPP or HMB-PP) is an intermediate of the MEP pathway (non-mevalonate pathway) of isoprenoid biosynthesis. The enzyme HMB-PP synthase (GcpE, IspG) catalyzes the conversion of 2-C-methyl--erythritol 2,4-cyclodiphosphate (MEcPP) into HMB-PP. HMB-PP is then converted further to isopentenyl pyrophosphate (IPP) and dimethylallyl pyrophosphate (DMAPP) by HMB-PP reductase (LytB, IspH).
HMB-PP is an essential metabolite in most pathogenic bacteria including Mycobacterium tuberculosis as well as in malaria parasites, but is absent from the human host.
HMB-PP is the physiological activator ("phosphoantigen") for human Vγ9/Vδ2 T cells, the major γδ T cell population in peripheral blood. With a bioactivity of 0.1 nM it is 10,000-10,000,000 times more potent than any other natural compound, such as IPP or alkyl amines. HMB-PP functions in this capacity by binding the B30.2 domain of BTN3A1. | 1 | Applied and Interdisciplinary Chemistry |
The simplest way to understand the origin of RUMs is to consider the balance between the numbers of constraints and degrees of freedom of the network, an engineering analysis that dates back to James Clerk Maxwell and which was introduced to amorphous materials by Jim Phillips and Mike Thorpe. If the number of constraints exceeds the number of degrees of freedom, the structure will be rigid. On the other hand, if the number of degrees of freedom exceeds the number of constraints, the structure will be floppy.
For a structure that consists of corner-linked tetrahedra (such as the SiO tetrahedra in silica, SiO) we can count the numbers of constraints and degrees of freedom as follows. For a given tetrahedron, the position of any corner has to have its three spatial coordinates (x,y,z) match the spatial coordinates of the corresponding corner of a linked tetrahedron. Thus each corner has three constraints. These are shared by the two linked tetrahedra, so contribute 1.5 constraints to each tetrahedron. There are 4 corners, so we have a total of 6 constraints per tetrahedron. A rigid three-dimensional object has 6 degrees of freedom, 3 translations and 3 rotations. Thus there is an exact balance between the numbers of constraints and degrees of freedom.
(Note that we can get an identical result by considering the atoms to be the basic units. There are 5 atoms in the structural tetrahedron, but 4 of there are shared by two tetrahedra, so that there are 3 + 4*3/2 = 9 degrees of freedom per tetrahedron. The number of constraints to hold together such a tetrahedron is 9 (4 distances and 5 angles)).
What this balance means is that a structure composed of structural tetrahedra joined at corners is exactly on the border between being rigid and floppy. What appears to happen is that symmetry reduces the number of constraints so that structures such as quartz and cristobalite are slightly floppy and thus support some RUMs.
The above analysis can be applied to any network structure composed of polyhedral groups of atoms. One example is the perovskite family of structures, which consist of corner-linked BX octahedra such as TiO or ZrO. A simple counting analysis would in fact suggest that such structures are rigid, but in the ideal cubic phase symmetry allows some degree of flexibility. Zirconium tungstate, the archetypal material showing negative thermal expansion, contains ZrO octahedra and WO tetrahedra, with one of the corners of each WO tetrahedra having no linkage. The counting analysis shows that, like silica, zirconium tungstate has an exact balance between the numbers of constraints and degrees of freedom, and further analysis has shown the existence of RUMs in this material. | 0 | Theoretical and Fundamental Chemistry |
Fine particles dispersed in the atmosphere can serve as cloud condensation nuclei and thereby cause marine cloud brightening
Eventually all FeCl particles are washed out of the air and fall on land or water, where they dissolve into iron compounds and salt.
Iron salt aerosols may also therefore contribute to iron fertilization. | 1 | Applied and Interdisciplinary Chemistry |
In a 1998 analysis of the E. coli genome, a large number of genes with unknown function were designated names beginning with the letter y, followed by sequentially generated letters without a mnemonic meaning (e.g., ydiO and ydbK). Since being designated, some y-genes have been confirmed to have a function, and assigned a synonym (alternative) name in recognition of this. However, as y-genes are not always re-named after being further characterised, this designation is not a reliable indicator of a gene's significance. | 1 | Applied and Interdisciplinary Chemistry |
Closed-cell metal foam was first reported in 1926 by Meller in a French patent where foaming of light metals, either by inert gas injection or by blowing agent, was suggested. Two patents on sponge-like metal were issued to Benjamin Sosnik in 1948 and 1951 who applied mercury vapor to blow liquid aluminium.
Closed-cell metal foams were developed in 1956 by John C. Elliott at Bjorksten Research Laboratories. Although the first prototypes were available in the 1950s, commercial production began in the 1990s by Shinko Wire company in Japan. Closed-cell metal foams are primarily used as an impact-absorbing material, similarly to the polymer foams in a bicycle helmet but for higher impact loads. Unlike many polymer foams, metal foams remain deformed after impact and can therefore only be deformed once. They are light (typically 10–25% of the density of an identical non-porous alloy; commonly those of aluminium) and stiff and are frequently proposed as a lightweight structural material. However, they have not been widely used for this purpose.
Closed-cell foams retain the fire resistance and recycling potential of other metal foams, but add the property of flotation in water. | 0 | Theoretical and Fundamental Chemistry |
In crystallography, the R-factor (sometimes called residual factor or reliability factor or the R-value or R) is a measure of the agreement between the crystallographic model and the experimental X-ray diffraction data. In other words, it is a measure of how well the refined structure predicts the observed data. The value is also sometimes called the discrepancy index, as it mathematically describes the difference between the experimental observations and the ideal calculated values. It is defined by the following equation:
where F is the so-called structure factor and the sum extends over all the reflections of X-rays measured and their calculated counterparts respectively. The structure factor is closely related to the intensity of the reflection it describes:
The minimum possible value is zero, indicating perfect agreement between experimental observations and the structure factors predicted from the model. There is no theoretical maximum, but in practice, values are considerably less than one even for poor models, provided the model includes a suitable scale factor. Random experimental errors in the data contribute to even for a perfect model, and these have more leverage when the data are weak or few, such as for a low-resolution data set. Model inadequacies such as incorrect or missing parts and unmodeled disorder are the other main contributors to , making it useful to assess the progress and final result of a crystallographic model refinement. For large molecules, the R-factor usually ranges between 0.6 (when computed for a random model and against an experimental data set) and 0.2 (for example for a well refined macro-molecular model at a resolution of 2.5 Ångström). Small molecules (up to ca. 1000 atoms) usually form better-ordered crystals than large molecules, and thus it is possible to attain lower R-factors. In the Cambridge Structural Database of small-molecule structures, more than 95% of the 500,000+ crystals have an R-factor lower than 0.15, and 9.5% have an R-factor lower than 0.03.
Crystallographers also use the Free R-Factor () to assess possible overmodeling of the data. is computed according to the same formula given above, but on a small, random sample of data that are set aside for the purpose and never included in the refinement. will always be greater than because the model is not fitted to the reflections that contribute to , but the two statistics should be similar because a correct model should predict all the data with uniform accuracy. If the two statistics differ significantly then that indicates the model has been over-parameterized, so that to some extent it predicts not the ideal error-free data for the correct model, but rather the error-afflicted data actually observed.
The quantities and are similarly used to describe the internal agreement of measurements in a crystallographic data set. | 0 | Theoretical and Fundamental Chemistry |
Lead isotope analysis is a technique for determining the source of ore in ancient smelting. Lead isotope composition is a signature of ore deposits and varies very little throughout the whole deposit. Also, lead isotope composition is unchanged in the smelting process.
The amount of each of the four stable isotopes of lead are used in the analysis. They are Pb, Pb, Pb and Pb. Ratios: Pb/Pb, Pb/Pb and Pb/Pb are measured by mass spectrometry. Apart from Pb, the lead isotopes are all products of the radioactive decay of uranium and thorium. When ore is deposited, uranium and thorium are separated from the ore. Thus, deposits formed in different geological periods will have different lead isotope signatures.
:::::::U →Pb
:::::::U →Pb
:::::::Th→Pb
For example, Hauptmann performed lead isotope analysis on slags from Faynan, Jordan. The resulting signature was the same as that from ores from the dolomite, limestone and shale deposits in the Wadi Khalid and Wadi Dana areas of Jordan. | 1 | Applied and Interdisciplinary Chemistry |
In standard Golden Gate Cloning, the restriction sites from the previous tier construct cannot be reused. To add more genes to the construct, restriction sites of a different Type IIS restriction enzyme need to be added to the destination vector. This can be done using either level 2, or M and P. A variant version of level M and P is also provided by GoldenBraid.
GoldenBraid overcomes the problem of designing numerous destination vectors by having a double loop, which is the "braid," to allow binary assembly of multiple constructs. There are two levels of destination plasmids, level α and level Ω. Each level of plasmids can be used as entry plasmids for the other level of plasmids for multiple times because both levels of plasmids have different Type IIS restriction sites that are in inverted orientation. For counterselection, the two levels of plasmids differ in their antibiotic resistance markers. | 1 | Applied and Interdisciplinary Chemistry |
Cell-free protein array technology produces protein microarrays by performing in vitro synthesis of the target proteins from their DNA templates. This method of synthesizing protein microarrays overcomes the many obstacles and challenges faced by traditional methods of protein array production that have prevented widespread adoption of protein microarrays in proteomics. Protein arrays made from this technology can be used for testing protein–protein interactions, as well as protein interactions with other cellular molecules such as DNA and lipids. Other applications include enzymatic inhibition assays and screenings of antibody specificity. | 1 | Applied and Interdisciplinary Chemistry |
Bronze and brass are both copper alloys that are solid solution strengthened. Bronze is the result of adding about 12% tin to copper while brass is the result of adding about 34% zinc to copper. Both of these alloys are being utilized in coins production, ship hardware, and art. | 1 | Applied and Interdisciplinary Chemistry |
In biochemistry, lipogenesis is the conversion of fatty acids and glycerol into fats, or a metabolic process through which acetyl-CoA is converted to triglyceride for storage in fat. Lipogenesis encompasses both fatty acid and triglyceride synthesis, with the latter being the process by which fatty acids are esterified to glycerol before being packaged into very-low-density lipoprotein (VLDL). Fatty acids are produced in the cytoplasm of cells by repeatedly adding two-carbon units to acetyl-CoA. Triacylglycerol synthesis, on the other hand, occurs in the endoplasmic reticulum membrane of cells by bonding three fatty acid molecules to a glycerol molecule. Both processes take place mainly in liver and adipose tissue. Nevertheless, it also occurs to some extent in other tissues such as the gut and kidney. A review on lipogenesis in the brain was published in 2008 by Lopez and Vidal-Puig. After being packaged into VLDL in the liver, the resulting lipoprotein is then secreted directly into the blood for delivery to peripheral tissues. | 1 | Applied and Interdisciplinary Chemistry |
CAM plants, such as cacti and succulent plants, also use the enzyme PEP carboxylase to capture carbon dioxide, but only at night. Crassulacean acid metabolism allows plants to conduct most of their gas exchange in the cooler night-time air, sequestering carbon in 4-carbon sugars which can be released to the photosynthesizing cells during the day. This allows CAM plants to minimize water loss (transpiration) by maintaining closed stomata during the day. CAM plants usually display other water-saving characteristics, such as thick cuticles, stomata with small apertures, and typically lose around 1/3 of the amount of water per fixed. | 0 | Theoretical and Fundamental Chemistry |
GLV release is correlated with fruit ripeness. Although this may be of effect in attracting pollinators, it also can cause issues if these GLV’s attract predators. One such example of this is with boll weevils, as an increase of GLV release when the plants are ripe has been found to increase the predation rate of these beetles.
Another issue with GLV release and increasing predation is with populations that alter GLV emissions from the affected plants. In one case, it was noted that secretions from certain species of caterpillars significantly decrease the effect amount of GLV emissions. In order to determine what was being done to decrease GLV emissions, a study was run on four unique species of caterpillars to measure their effectiveness in decreasing GLV levels released from the predated plant. It’s been found that compounds in the gut and salivary glands, as well as modifications to those compounds in these various species, has been able to mute a large part of the effect of GLV released into the external environment. How this is done is though stopping the flow of pheromone molecules, so they can’t interact with receptors on the leaves of other plants. | 1 | Applied and Interdisciplinary Chemistry |
In bacteria and fungi, the sulfur assimilation pathway is similar to that in plants, where inorganic sulfate is reduced to sulfide, and then incorporated into cysteine and other sulfur-containing compounds.
Bacteria and fungi can absorb inorganic sulfate from the environment through a sulfate transporter, which is regulated by the presence of sulfate in the medium. Once inside the cell, sulfate is activated by ATP sulfurylase to form adenosine 5'-phosphosulfate (APS), which is then reduced to sulfite by APS reductase. Sulfite is further reduced to sulfide by sulfite reductase, which is then incorporated into cysteine by enzyme.
Cysteine, once synthesized, can be used for the biosynthesis of methionine and other important biomolecules. In addition, microorganisms also use sulfur-containing compounds for various other purposes, such as the synthesis of antibiotics.
Sulfur assimilation in microorganisms is regulated by a variety of environmental factors, including the availability of sulfur in the medium and the presence of other nutrients. The activity of key enzymes in the sulfur assimilation pathway is also regulated by feedback inhibition from downstream products, similar to the regulation seen in plants. | 1 | Applied and Interdisciplinary Chemistry |
Glycoside hydrolases are classified into EC 3.2.1 as enzymes catalyzing the hydrolysis of O- or S-glycosides. Glycoside hydrolases can also be classified according to the stereochemical outcome of the hydrolysis reaction: thus they can be classified as either retaining or inverting enzymes. Glycoside hydrolases can also be classified as exo or endo acting, dependent upon whether they act at the (usually non-reducing) end or in the middle, respectively, of an oligo/polysaccharide chain. Glycoside hydrolases may also be classified by sequence or structure-based methods. | 0 | Theoretical and Fundamental Chemistry |
RNA splicing is a process in molecular biology where a newly-made precursor messenger RNA (pre-mRNA) transcript is transformed into a mature messenger RNA (mRNA). It works by removing all the introns (non-coding regions of RNA) and splicing back together exons (coding regions). For nuclear-encoded genes, splicing occurs in the nucleus either during or immediately after transcription. For those eukaryotic genes that contain introns, splicing is usually needed to create an mRNA molecule that can be translated into protein. For many eukaryotic introns, splicing occurs in a series of reactions which are catalyzed by the spliceosome, a complex of small nuclear ribonucleoproteins (snRNPs). There exist self-splicing introns, that is, ribozymes that can catalyze their own excision from their parent RNA molecule. The process of transcription, splicing and translation is called gene expression, the central dogma of molecular biology. | 1 | Applied and Interdisciplinary Chemistry |
The cryophorus was first described by William Hyde Wollaston in an 1813 paper titled, "On a method of freezing at a distance." | 0 | Theoretical and Fundamental Chemistry |
Modern direct measurements are based on precision measurements of the atomic energy levels in hydrogen and deuterium, and measurements of scattering of electrons by nuclei. There is most interest in knowing the charge radii of protons and deuterons, as these can be compared with the spectrum of atomic hydrogen and deuterium: the nonzero size of the nucleus causes a shift in the electronic energy levels which shows up as a change in the frequency of the spectral lines. Such comparisons are a test of quantum electrodynamics (QED).
Since 2002, the proton and deuteron charge radii have been independently refined parameters in the CODATA set of recommended values for physical constants. Both scattering data and spectroscopic data are used to determine the recommended values. Furthermore, spectroscopic measurements can be made both with regular hydrogen (consisting of a proton and an electron) or muonic hydrogen (an exotic atom consisting of a proton and a negative muon). An inconsistency between proton charge radius measurements made using different techniques was known as the proton radius puzzle, but more recent measurements show consistent results.
The 2018 CODATA recommended values are:
:proton: R = 8.414(19)×10 m
:deuteron: R = 2.127 99(74)×10 m | 0 | Theoretical and Fundamental Chemistry |
Amoxicillin is occasionally used for the treatment of skin infections, such as acne vulgaris. It is often an effective treatment for cases of acne vulgaris that have responded poorly to other antibiotics, such as doxycycline and minocycline. | 0 | Theoretical and Fundamental Chemistry |
The concept of human-equivalent energy (H-e) assists in understanding of energy flows in physical and biological systems by expressing energy units in human terms: it provides a “feel” for the use of a given amount of energy by expressing it in terms of the relative quantity of energy needed for human metabolism, assuming an average human energy expenditure of 12,500 kJ per day and a basal metabolic rate of 80 watts. A light bulb running at 100 watts is running at 1.25 human equivalents (100/80), i.e. 1.25 H-e. On the other hand, a human may generate as much as 1,000 watts for a task lasting a few minutes, or even more for a task of a few seconds' duration, while climbing a flight of stairs may represent work at a rate of about 200 watts. | 1 | Applied and Interdisciplinary Chemistry |
Within the environmental sciences, screening broadly refers to a set of analytical techniques used to monitor levels of potentially hazardous organic compounds in the environment, particularly in tandem with mass spectrometry techniques. Such screening techniques are typically classified as either targeted, where compounds of interest are chosen before the analysis begins, or non-targeted, where compounds of interest are chosen at a later stage of the analysis. These two techniques can be organized into at least three approaches: target screening, using reference standards that are analogous to the target compound; suspect screening, which uses a library of cataloged data such as exact mass, isotope patterns, and chromatographic retention times in lieu of reference standards; and non-target screening, using no pre-existing knowledge for comparison before analysis. As such, target screening is most useful when monitoring the presence of specific organic compounds—particularly for regulatory purposes—which requires higher selectivity and sensitivity. When the number of detected compounds and associated metabolites needs to be maximized for discovering new or emerging environmental trends or biomarkers for disease, a more non-targeted approach has traditionally been used. However, the rapid improvement of mass spectrometers into more high-resolution forms, with increased sensitivity, has made suspect and non-target screening more attractive, either as stand-alone approaches or in conjunction with more targeted methods. | 0 | Theoretical and Fundamental Chemistry |
The transition temperature of an ELP depends to a certain extent on the identity of the "X" residue found at the fourth position of the pentapeptide monomeric unit. Residues that are highly hydrophobic, such as leucine and phenylalanine, tend to decrease the transition temperature. On the other hand, residues that are highly hydrophilic, such as serine and glutamine, tend to increase the transition temperature. The presence of a potentially charged residue at the "X" position will determine how the ELP responds to varying pHs, with glutamic acid and aspartic acid raising the T at pH values in which the residues are deprotonated and lysine and arginine raising the T at pH values in which the residues are protonated. The pH needs to be compatible with the charged states of these amino acids in order to raise the T. Also higher molecular mass ELPs and higher concentrations of ELPs in solution make it much easier for the polymer to form aggregates, in effect lowering the experimental T | 0 | Theoretical and Fundamental Chemistry |
The Joback method (often named Joback/Reid method) predicts eleven important and commonly used pure component thermodynamic properties from molecular structure only. | 0 | Theoretical and Fundamental Chemistry |
Ultraviolet germicidal irradiation (UVGI) is a disinfection technique employing ultraviolet (UV) light, particularly UV-C (180-280 nm), to kill or inactivate microorganisms. UVGI primarily inactivates microbes by damaging their genetic material, thereby inhibiting their capacity to carry out vital functions.
The use of UVGI extends to an array of applications, encompassing food, surface, air, and water disinfection. UVGI devices can inactivate microorganisms including bacteria, viruses, fungi, molds, and other pathogens. Recent studies have substantiated the ability of UV-C light to inactivate SARS-CoV-2, the strain of coronavirus that causes COVID-19.
UV-C wavelengths demonstrate varied germicidal efficacy and effects on biological tissue. Many germicidal lamps like low-pressure mercury (LP-Hg) lamps, with peak emissions around 254 nm, contain UV wavelengths that can be hazardous to humans. As a result, UVGI systems have been primarily limited to applications where people are not directly exposed, including hospital surface disinfection, [https://www.cdc.gov/coronavirus/2019-ncov/community/ventilation/uvgi.html upper-room UVGI], and water treatment. More recently, the application of wavelengths between 200-235 nm, often referred to as far-UVC, has gained traction for surface and air disinfection. These wavelengths are regarded as much safer due to their significantly reduced penetration into human tissue.
Notably, UV-C light is virtually absent in sunlight reaching the Earth's surface due to the absorptive properties of the ozone layer within the atmosphere. | 0 | Theoretical and Fundamental Chemistry |
:V09XX01 Cobalt (Co) cyanocobalamine
:V09XX02 Cobalt (Co) cyanocobalamine
:V09XX03 Selenium (Se) norcholesterol
:V09XX04 Ferric (Fe) citrate | 1 | Applied and Interdisciplinary Chemistry |
Clinical Chemistry and Laboratory Medicine is the official journal of the European Federation of Clinical Chemistry and Laboratory Medicine (EFLM). It is also the official journal of the Association of Clinical Biochemists in Ireland, the Belgian Society of Clinical Chemistry, the German United Society of Clinical Chemistry and Laboratory Medicine, the Greek Society of Clinical Chemistry-Clinical Biochemistry, the Italian Society of Clinical Biochemistry and Clinical Molecular Biology, the Slovenian Association for Clinical Chemistry, and the Spanish Society for Clinical Biochemistry and Molecular Pathology. | 1 | Applied and Interdisciplinary Chemistry |
Phytobenthos are subcategorized into microphytobenthos and macrophytobenthos. Microphytobenthos such as diatoms can be as small as 0.2 μm in diameter, and macrophytobenthos such as kelps can be tens of meters long. To establish themselves on surfaces, phytobenthos usually stabilize themselves onto substrates through the use of various polysaccharides, glycoproteins, and even lipids that make up the extracellular polymeric substance, of which 40 - 90% of the carbons are derived from carbohydrates. Some species of phytobenthos such as Ostreobium and diatoms such as the Synedra acus Kütznig have been observed to live in a free-living state. Benthic diatoms have been found to be useful indicator species for determining the state of the aquatic environment as many study models have demonstrated association between the type of diatom communities that are present and the stability and the size of the sediments. Non-diatom phytobenthos such as the cyanobacteria Nostoc spp. and Phormidium spp. have also been used as biological indicators. | 0 | Theoretical and Fundamental Chemistry |
Bernard Courtois, also spelled Barnard Courtois, (8 February 1777 – 27 September 1838) was a French chemist credited with first isolating iodine, making early photography possible.
By 1811 the Napoleonic Wars had made the government-controlled saltpeter business taper off since there was by then a shortage of wood ashes with which potassium nitrate was made. As an alternative, the needed potassium nitrate was derived from seaweed that was abundant on the Normandy and Brittany shores. The seaweed also had another, yet undiscovered, important chemical. One day towards the end of 1811 while Courtois was isolating sodium and potassium compounds from seaweed ash, he discovered iodine after he added sulfuric acid to the seaweed ash. He was investigating corrosion of his copper vessels when he noticed a vapor given off. It was in the form of an unusual purple vapor. Humphry Davy later records | 1 | Applied and Interdisciplinary Chemistry |
Carbonate was defined as "a compound formed by the union of carbonic acid with an earth, alkali, or metallic oxide [...] they are distinguished by the property of effervescing on the addition of an acid" The definition expands upon fixed air being fixated within carbonate to suggest carbonic acid is a constituent of carbonate, therefore in the ancient language the suffix "-ic acid" and "-ate" were not interchangeable.
The modern definition is similar, although equipped with the molecular knowledge of carbonate's structure and reassignment of the meaning of carbonic acid from CO to the HCO molecule, "Carbonates are the salts of carbonic acids. They form when a positively charged metal ion comes into contact with the oxygen atoms of the carbonate ion." | 1 | Applied and Interdisciplinary Chemistry |
* Anne of Denmark, Electress of Saxony (1532–1585), while an interested amateur and not a professional pharmacist, is now considered to have been the first female pharmacist in Germany.
* Caterina Vitale (1566–1619) was the first female pharmacist and chemist in Malta, and the first female pharmacist of the Knights Hospitaller.
* Maria Dauerer (1624-1688) was first Swedish female apothecary (first formally trained female pharmacist was Märtha Leth).
* Elizabeth Gooking Greenleaf (1681–1762) was the first female apothecary in the Thirteen Colonies. She is considered to be the first female pharmacist in the United States.
* Susan Hayhurst (1820–1909) was the first woman to receive a pharmacy degree in the United States, which she received in 1883 from the Philadelphia College of Pharmacy.
* Mary Corinna Putnam Jacobi (1842–1906), who upon graduating from the New York College of Pharmacy in 1863, became the first woman to graduate from a United States school of pharmacy.
*Isabella Skinner Clarke (1842–1926) and Rose Coombes Minshull (1845–1905) became the first two women elected as full members of the Pharmaceutical Society of Great Britain in 1879.
* Margaret Elizabeth Buchanan (1865–1940) became the first woman to be elected to the Council of the Pharmaceutical Society of Great Britain in 1918, serving until 1926.
* Cora Dow (1868–1915), a pharmacist in Cincinnati, Ohio, the leading female pharmacist of her time, with eleven stores under her name when she died.
* Fanny Deacon (née Potter) became the first female pharmacist in the United Kingdom in 1870.
* Julia Pearl Hughes (1873–1950) was the first African-American female pharmacist to own and operate her own drug store.
* Jean Irvine (1877–1962) became the first female president of the Pharmaceutical Society of Great Britain in 1947, which position she held until 1948.
* Charlotte Jacobs became the first female pharmacist in the Netherlands in 1879.
* Caroline Copp became the first female pharmacist in Australia in 1880.
* In 1896 Charlotte Schou and Nielsine Schousen became the first female pharmacists in Denmark.
* Anna Louise James (1886–1977) was the first African-American female pharmacist in Connecticut.
* Ella P. Stewart (1893–1987) was one of the first African-American female pharmacists in the United States.
* Christina Jesop Wilson became the first female pharmacist to qualify in the south of Ireland in 1900.
* Kamran Aziz (1922-2017) and Ayşe Dana became the first female pharmacists in Northern Cyprus in 1944.
* Mary Munson Runge (1928–2014) became the first woman and the first African-American elected president of the American Pharmacists Association (APhA), which occurred in 1979; she was president for two terms, from 1979 to 1981.
* Remedios M. "Remy" Gabriel became the first civilian woman to become a licensed pharmacist in Guam in 1953.
* Julie Zinihite became the first Solomon Islands woman to serve as the Chief Pharmacist at the National Referral Hospital in 2010.
* Angelita Bosch was the first female pharmacist in Puerto Rico. | 1 | Applied and Interdisciplinary Chemistry |
To image time-dependent, periodically fluctuating phenomena, topography can be combined with stroboscopic exposure techniques. In this way, one selected phase of a sinusoidally varying movement is selectively images as a "snapshot". First applications were in the field of surface acoustic waves on semiconductor surfaces.
Literature: | 0 | Theoretical and Fundamental Chemistry |
A number of metal borates are known. They can be obtained by treating boric acid or boron oxides with metal oxides. | 0 | Theoretical and Fundamental Chemistry |
Hindered amine light stabilizers (HALS) stabilise against weathering by scavenging free radicals that are produced by photo-oxidation of the polymer matrix. UV-absorbers stabilise against weathering by absorbing ultraviolet light and converting it into heat. Antioxidants stabilise the polymer by terminating the chain reaction because of the absorption of UV light from sunlight. The chain reaction initiated by photo-oxidation leads to cessation of crosslinking of the polymers and degradation of the property of polymers. Antioxidants are used to protect from thermal degradation. | 0 | Theoretical and Fundamental Chemistry |
Nanogeoscience is the study of nanoscale phenomena related to geological systems. Predominantly, this is investigated by studying environmental nanoparticles between 1–100 nanometers in size. Other applicable fields of study include studying materials with at least one dimension restricted to the nanoscale (e.g. thin films, confined fluids) and the transfer of energy, electrons, protons, and matter across environmental interfaces. | 0 | Theoretical and Fundamental Chemistry |
The equilibrium concentrations of the products and reactants do not directly depend on the total pressure of the system. They may depend on the partial pressure of the products and reactants, but if the number of moles of gaseous reactants is equal to the number of moles of gaseous products, pressure has no effect on equilibrium.
Changing total pressure by adding an inert gas at constant volume does not affect the equilibrium concentrations (see Effect of adding an inert gas below).
Changing total pressure by changing the volume of the system changes the partial pressures of the products and reactants and can affect the equilibrium concentrations (see §Effect of change in volume below). | 0 | Theoretical and Fundamental Chemistry |
The critical edition of the Vaisheshika Sutras are divided into ten chapters, each subdivided into two sections called āhnikas: | 1 | Applied and Interdisciplinary Chemistry |
Pseudoephedrine amides undergo deprotonation by a strong base such as lithium diisopropylamide (LDA) to give the corresponding (Z)-enolates. Alkylation of these lithium enolates proceeds with high facial selectivity.
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The diastereoselectivity is believed to result from a configuration wherein one face of the lithium enolate is blocked by the secondary lithium alkoxide and the solvent molecules associated with that lithium cation. In accordance with this proposal, it has been observed that the diastereoselectivity of the alkylation step is highly dependent on the amount of lithium chloride present and on the solvent, tetrahydrofuran (THF). Typically, 4 to 6 equivalents of lithium chloride are sufficient to saturate a solution of enolate in THF at the reaction molarity.
<br />
One primary advantage of asymmetric alkylation with pseudoephedrine amides is that the amide enolates are typically nucleophilic enough to react with primary and even secondary halides at temperatures ranging from –78 °C to 0 °C. Construction of quaternary carbon centers by alkylation of α-branched amide enolates is also possible, though the addition of DMPU is necessary for less reactive electrophiles. | 0 | Theoretical and Fundamental Chemistry |
Permeable solutions can be based on porous asphalt and concrete surfaces, concrete pavers (permeable interlocking concrete paving systems – PICP), or polymer-based grass pavers, grids and geocells. Porous pavements such as pervious concrete and pervious asphalt are better suited for urbanized areas that see more frequent vehicular traffic, while concrete pavers, grids, and geocells are better suited for light vehicular traffic, pedestrian and cycling pathways, and overflow parking lots. Pervious concrete pavers allow water to percolate and infiltrate through the pavers and into the aggregate layers and/or soil below. Impervious concrete pavers installed with ample void space between each paver function in the same way as pervious concrete pavers as they enable stormwater to drain into the voids between each paver, either filled with coarse aggregate or vegetation, to a stone and/or soil base layer for on-site infiltration and filtering. Polymer based grass grid or cellular paver systems provide load bearing reinforcement for unpaved surfaces of gravel or turf.
Grass pavers, plastic turf reinforcing grids (PTRG), and geocells (cellular confinement systems) are honeycombed 3D grid-cellular systems, made of thin-walled HDPE plastic or other polymer alloys. These provide grass reinforcement, ground stabilization and gravel retention. The 3D structure reinforces infill and transfers vertical loads from the surface, distributing them over a wider area. Selection of the type of cellular grid depends to an extent on the surface material, traffic and loads. The cellular grids are installed on a prepared base layer of open-graded stone (higher void spacing) or engineered stone (stronger). The surface layer may be compacted gravel or topsoil seeded with grass and fertilizer. In addition to load support, the cellular grid reduces compaction of the soil to maintain permeability, while the roots improve permeability due to their root channels.
In new suburban growth, porous pavements protect watersheds by delaying and filtering the surge flow. In existing built-up areas and towns, redevelopment and reconstruction are opportunities to implement stormwater water management practices. Permeable paving is an important component in Low Impact Development (LID), a process for land development in the United States that attempts to minimize impacts on water quality and the similar concept of sustainable drainage systems (SuDS) in the United Kingdom.
The infiltration capacity of the native soil is a key design consideration for determining the depth of base rock for stormwater storage or for whether an underdrain system is needed. | 1 | Applied and Interdisciplinary Chemistry |
The distribution of hydraulic head through an aquifer determines where groundwater will flow. In a hydrostatic example (first figure), where the hydraulic head is constant, there is no flow. However, if there is a difference in hydraulic head from the top to bottom due to draining from the bottom (second figure), the water will flow downward, due to the difference in head, also called the hydraulic gradient. | 1 | Applied and Interdisciplinary Chemistry |
Resazurin can be used as one of a series of rapid tests to determine the quality of a milk sample. In this test, resazurin is added as a violet redox dye which turns mauvish-pink due to conversion to resorufin and then to colourless dihydroresorufin. This happens due to lowering of the oxidation-reduction potential in the milk sample caused by presence of bacteria which utilize available oxygen present in the milk for aerobic respiration. The rate of the colour change is used as an index for the number of bacteria present in the milk sample. | 0 | Theoretical and Fundamental Chemistry |
* The Physics and Chemistry of Wave Packets, with John Yeazell [https://books.google.com/books?id=_sScnHz1kfsC&dq=Turgay+Uzer&pg=PP9 at books.google]
* Lecture Notes on Atomic and Molecular Physics with Şakir Erkoç [https://books.google.com/books?id=KWssMj81fpkC&q=Lecture+Notes+on+Atomic+and+Molecular+Physics at books.google] | 0 | Theoretical and Fundamental Chemistry |
Control of the process of gene transcription affects patterns of gene expression and, thereby, allows a cell to adapt to a changing environment, perform specialized roles within an organism, and maintain basic metabolic processes necessary for survival. Therefore, it is hardly surprising that the activity of RNAP is long, complex, and highly regulated. In Escherichia coli bacteria, more than 100 transcription factors have been identified, which modify the activity of RNAP.
RNAP can initiate transcription at specific DNA sequences known as promoters. It then produces an RNA chain, which is complementary to the template DNA strand. The process of adding nucleotides to the RNA strand is known as elongation; in eukaryotes, RNAP can build chains as long as 2.4 million nucleotides (the full length of the dystrophin gene). RNAP will preferentially release its RNA transcript at specific DNA sequences encoded at the end of genes, which are known as terminators.
Products of RNAP include:
* Messenger RNA (mRNA)—template for the synthesis of proteins by ribosomes.
* Non-coding RNA or "RNA genes"—a broad class of genes that encode RNA that is not translated into protein. The most prominent examples of RNA genes are transfer RNA (tRNA) and ribosomal RNA (rRNA), both of which are involved in the process of translation. However, since the late 1990s, many new RNA genes have been found, and thus RNA genes may play a much more significant role than previously thought.
** Transfer RNA (tRNA)—transfers specific amino acids to growing polypeptide chains at the ribosomal site of protein synthesis during translation
** Ribosomal RNA (rRNA)—a component of ribosomes
** Micro RNA—regulates gene activity
** Catalytic RNA (Ribozyme)—enzymatically active RNA molecules
RNAP accomplishes de novo synthesis. It is able to do this because specific interactions with the initiating nucleotide hold RNAP rigidly in place, facilitating chemical attack on the incoming nucleotide. Such specific interactions explain why RNAP prefers to start transcripts with ATP (followed by GTP, UTP, and then CTP). In contrast to DNA polymerase, RNAP includes helicase activity, therefore no separate enzyme is needed to unwind DNA. | 1 | Applied and Interdisciplinary Chemistry |
But what happens to the pressure conditions in the flow if you change the flow speed? The scientist Daniel Bernoulli dealt with this question as early as the beginning of the 18th century. Based on the considerations of continuity mentioned above, and incorporating the conservation of energy, he linked the two quantities of pressure and speed. The core statement of the Bernoulli equation is that the pressure in a liquid falls where the velocity increases (and vice versa): Flow according to Bernoulli and Venturi. | 1 | Applied and Interdisciplinary Chemistry |
In August 1962 the Ministry of Health announced it was forming a poisons information service. This was after the Emergency Treatment in Hospital of Cases of Acute Poisoning published by the Central Health Services Council in March 1962. Many more household chemicals were on the market, and the chemical composition was only known to the manufacturers. 4,000 to 5,000 people each year were lethally poisoned, with 6,085 in 1962; however, many of the deaths were (non-accidental) suicides.
It started in 1963 by Dr Roy Goulding at the Medical Toxicology Unit of Guy's Hospital, with a staff of 65. By the late 1960s, recreational drugs were presenting a widespread danger. Other centres were soon set up in Edinburgh, Belfast and Cardiff.
UKTIS was based in Newcastle from 1995. | 1 | Applied and Interdisciplinary Chemistry |
The stable isotope composition of amino acids refers to the abundance of heavy and light non-radioactive isotopes of carbon (C and C), nitrogen (N and N), and other elements within these molecules. Amino acids are the building blocks of proteins. They are synthesized from alpha-keto acid precursors that are in turn intermediates of several different pathways in central metabolism. Carbon skeletons from these diverse sources are further modified before transamination, the addition of an amino group that completes amino acid biosynthesis. Bonds to heavy isotopes are stronger than bonds to light isotopes, making reactions involving heavier isotopes proceed slightly slower in most cases. This phenomenon, known as a kinetic isotope effect, gives rise to isotopic differences between reactants and products that can be detected using isotope ratio mass spectrometry. Amino acids are synthesized via a variety of pathways with reactions containing different, unknown isotope effects. Because of this, the C content of amino acid carbon skeletons varies considerably between the amino acids. There is also an isotope effect associated with transamination, which is apparent from the abundance of N in some amino acids.
Because of these properties, amino acid isotopes record useful information about the organisms that produce them. Variations in metabolism between different taxonomical groups give rise to characteristic patterns of C enrichment in their amino acids. This allows the sources of carbon in food webs to be identified. The isotope effect associated with transamination also makes amino acid nitrogen isotopes a useful tool to study the structure of food webs. Repeated transamination by consumers results in a predictable increase in the abundance of N as amino acids are transferred up food chains. Together, these application, among others in ecology, demonstrate the utility of stable isotopes as tracers of environmental processes that are difficult to measure directly. | 0 | Theoretical and Fundamental Chemistry |
In 1949, Saul Winstein observed that 2-exo-norbornyl brosylate (p-bromobenzenesulfonate) and 2-endo-norbornyl tosylate (p-toluenesulfonate) gave a racemic mixture of the same product, 2-exo-norbornyl acetate, upon acetolysis (see Figure 6). Since tosylates and brosylates work equally well as leaving groups, he concluded that both the 2-endo and 2-exo substituted norbornane must be going through a common cationic intermediate with a dominant exo reactivity. He reported that this intermediate was most likely a symmetric, delocalized 2-norbornyl cation. It was later shown via vapor phase chromatography that the amount of the endo epimer of product produced was less than 0.02%, proving the high stereoselectivity of the reaction.
When a single enantiomer of 2-exo-norbornyl brosylate undergoes acetolysis, no optical activity is seen in the resulting 2-exo-norbornyl acetate (see Figure 7). Under the non-classical description of the 2-norbornyl cation, the plane of symmetry present (running through carbons 4, 5, and 6) allow equal access to both enantiomers of the product, resulting in the observed racemic mixture.
It was also observed that the 2-exo-substituted norbornanes reacted 350 times faster than the corresponding endo isomers. Anchimeric assistance of the sigma bond between carbons 1 and 6 was rationalized as the explanation for this kinetic effect. Importantly, the invoked anchimeric assistance led many chemists to postulate that the energetic stability of the 2-norbornyl cation was directly due to the symmetric, bridged structure invoked in the non-classical explanation. However, some other authors offered alternative explanations for the high stability without invoking a non-classical structure.
In 1951, it was first suggested that the 2-norbornyl cation could actually be better described when viewed as a nortricyclonium ion. It has been shown that the major product formed from an elimination reaction of the 2-norbornyl cation is nortricyclene (not norbornene), but this has been claimed to support both non-classical ion postulates. | 0 | Theoretical and Fundamental Chemistry |
The polymerase chain reaction method is used to quantify nucleic acids by amplifying a nucleic acid molecule with the enzyme DNA polymerase. Conventional PCR is based on the theory that amplification is exponential. Therefore, nucleic acids may be quantified by comparing the number of amplification cycles and amount of PCR end-product to those of a reference sample. However, many factors complicate this calculation, creating uncertainties and inaccuracies. These factors include the following: initial amplification cycles may not be exponential; PCR amplification eventually plateaus after an uncertain number of cycles; and low initial concentrations of target nucleic acid molecules may not amplify to detectable levels. However, the most significant limitation of PCR is that PCR amplification efficiency in a sample of interest may be different from that of reference samples.
Instead of performing one reaction per well, dPCR involves partitioning the PCR solution into tens of thousands of nano-liter sized droplets, where a separate PCR reaction takes place in each one. A PCR solution is made similarly to a TaqMan assay, which consists of template DNA (or RNA), fluorescence-quencher probes, primers, and a PCR master mix, which contains DNA polymerase, dNTPs, MgCl, and reaction buffers at optimal concentrations. Several different methods can be used to partition samples, including microwell plates, capillaries, oil emulsion, and arrays of miniaturized chambers with nucleic acid binding surfaces. The PCR solution is partitioned into smaller units, each with the necessary components for amplification. The partitioned units are then subjected to thermocycling so that each unit may independently undergo PCR amplification. After multiple PCR amplification cycles, the samples are checked for fluorescence with a binary readout of “0” or “1”. The fraction of fluorescing droplets is recorded. The partitioning of the sample allows one to estimate the number of different molecules by assuming that the molecule population follows the Poisson distribution, thus accounting for the possibility of multiple target molecules inhabiting a single droplet. Using Poissons law of small numbers, the distribution of target molecule within the sample can be accurately approximated allowing for a quantification of the target strand in the PCR product. This model simply predicts that as the number of samples containing at least one target molecule increases, the probability of the samples containing more than one target molecule increases. In conventional PCR, the number of PCR amplification cycles is proportional to the starting copy number. Different from many peoples belief that dPCR provides absolute quantification, digital PCR uses statistical power to provide relative quantification. For example, if Sample A, when assayed in 1 million partitions, gives one positive reaction, it does not mean that the Sample A has one starting molecule.
The benefits of dPCR include increased precision through massive sample partitioning, which ensures reliable measurements in the desired DNA sequence due to reproducibility. Error rates are larger when detecting small-fold change differences with basic PCR, while error rates are smaller with dPCR due to the smaller-fold change differences that can be detected in DNA sequence. The technique itself reduces the use of a larger volume of reagent needed, which inevitably will lower experiment cost. Also, dPCR is highly quantitative as it does not rely on relative fluorescence of the solution to determine the amount of amplified target DNA. | 1 | Applied and Interdisciplinary Chemistry |
Ethyl chloroformate is a highly toxic, flammable, corrosive substance. It causes severe burns when comes in contact with eyes and/or skin, can be harmful if swallowed or inhaled. | 0 | Theoretical and Fundamental Chemistry |
Sulfides are typically prepared by alkylation of thiols. Alkylating agents include not only alkyl halides, but also epoxides, aziridines, and Michael acceptors.
Such reactions are usually conducted in the presence of a base, which converts the thiol into the more nucleophilic thiolate. Analogously, the reaction of disulfides with organolithium reagents produces thioethers:
Analogous reactions are known starting with Grignard reagents.
Alternatively, sulfides can be synthesized by the addition of a thiol to an alkene in the thiol-ene reaction:
This reaction is often catalysed by free radicals produced from a photoinitiator.
Sulfides can also be prepared by many other methods, such as the Pummerer rearrangement. Trialkysulfonium salts react with nucleophiles with a dialkyl sulfide as a leaving group:
This reaction is exploited in biological systems as a means of transferring an alkyl group. For example, S-adenosylmethionine acts as a methylating agent in biological S2 reactions.
An unusual but well tested method for the synthesis of thioethers involves addition of alkenes, especially ethylene across the S-Cl bond of sulfur dichloride. This method has been used in the production of bis(2-chloroethyl)sulfide, a mustard gas: | 0 | Theoretical and Fundamental Chemistry |
Hexamethylenetetramine was first introduced into the medical setting in 1895 as a urinary antiseptic. It was officially approved by the FDA for medical use in the United States in 1967. However, it was only used in cases of acidic urine, whereas boric acid was used to treat urinary tract infections with alkaline urine. Scientist De Eds found that there was a direct correlation between the acidity of hexamethylenetetramine's environment and the rate of its decomposition. Therefore, its effectiveness as a drug depended greatly on the acidity of the urine rather than the amount of the drug administered. In an alkaline environment, hexamethylenetetramine was found to be almost completely inactive.
Hexamethylenetetramine was also used as a method of treatment for soldiers exposed to phosgene in World War I. Subsequent studies have shown that large doses of hexamethylenetetramine provide some protection if taken before phosgene exposure but none if taken afterwards. | 0 | Theoretical and Fundamental Chemistry |
The Thyrotroph Thyroid Hormone Sensitivity Index (TTSI, also referred to as Thyrotroph T4 Resistance Index or TT4RI) was developed to enable fast screening for resistance to thyroid hormone. Somewhat similar to the TSH Index it is calculated from equilibrium values for TSH and FT4, however with a different equation. | 1 | Applied and Interdisciplinary Chemistry |
Senapathy analyzed the distribution of the ORF lengths in computer-generated random DNA sequences first. Surprisingly, this study revealed that about 200 codons (600 bases) was the upper limit in ORF lengths. The shortest ORF (zero base in length) was the most frequent. At increasing lengths of ORFs, their frequency decreased logarithmically, approaching zero at about 600 bases. When the probability of ORF lengths in a random sequence was plotted, it revealed that the probability of increasing lengths of ORFs decreased exponentially and tailed off at a maximum of about 600 bases. From this “negative exponential” distribution of ORF lengths, it was found that most of ORFs were far shorter than the maximum.This finding was surprising because the coding sequence for the average protein length of 400 AAs (with ~1,200 bases of coding sequence) and longer proteins of thousands of AAs (requiring >10,000 bases of coding sequence) would not occur at a stretch in a random sequence. If this was true, a typical gene with a contiguous coding sequence could not originate in a random sequence. Thus, the only possible way that any gene could originate from a random sequence was to split the coding sequence into shorter segments and select these segments from short ORFs available in the random sequence, rather than to increase the ORF length by eliminating consecutive stop codons. This process of choosing short segments of coding sequences from the available ORFs to make a long ORF would lead to a split structure.
If this hypothesis was true, eukaryotic DNA sequences should reflect it. When Senapathy plotted the distribution of ORF lengths in eukaryotic DNA sequences, the plot was remarkably similar to that from random DNA sequences. This plot was also a negative exponential distribution that tailed off at a maximum of about 600 bases, as with eukaryotic genes, which coincided exactly with the maximum length of ORFs observed in both random DNA and eukaryotic DNA sequences.
The split genes thus originated from random DNA sequences by choosing the best of the short coding segments (exons) and splicing them. The intervening intron sequences were left-over vestiges of the random sequences, and thus were earmarked to be removed by the spliceosome. These findings indicated that split genes could have originated from random DNA sequences with exons and introns as they appear in today's eukaryotic organisms. Nobel Laureate Marshall Nirenberg, who deciphered the codons, stated that these findings strongly showed that the split gene theory for the origin of introns and the split structure of genes must be valid.
Blake proposed the Gilbert-Blake hypothesis in 1979 for the origin of introns and stated that Senapathy's split gene theory comprehensively explained the origin of the split gene structure. In addition, he stated that it explained several key questions including the origin of the splicing mechanism: | 1 | Applied and Interdisciplinary Chemistry |
Traditional classification shows several theoretical and practical deficiencies. One of the most important is the fact that no perfectly isentropic fluid exists. Isentropic fluids have two extrema (ds/dT=0) on the saturation vapour curve. Practically, there are some fluids which are very close to this behaviour or at least in a certain temperature range, for example trichlorofluoromethane (CClF). Another problem is the extent of how dry or isentropic the fluid behaves, which has significant practical importance when designing for example an Organic Rankine Cycle layout and choosing proper expander.
A new kind of classification was proposed by G. Györke et al. to resolve the problems and deficiencies of the traditional three-class classification system. The new classification is also based on the shape of the saturation vapour curve of the fluid in temperature-entropy diagram similarly to the traditional one. The classification uses a characteristic-point based method to differentiate the fluids. The method defines three primary and two secondary characteristic points. The relative location of these points on the temperature-entropy saturation curve defines the categories. Every pure fluid has primary characteristic points A, C and Z:
* Primary point A and Z are the lowest temperature points on the saturation liquid and saturation vapour curve respectively. This temperature belongs to the melting point, which practically equals the triple point of the fluid. The choice of A and Z refers to the first and last point of the saturation curve visually.
* Primary point C refers to the critical point, which is an already well-defined thermodynamic property of the fluids.
The two secondary characteristic points, namely M and N are defined as local entropy extrema on the saturation vapour curve, more accurately, at those points, where with the decrease of the saturation temperature entropy stays constant: ds/dT=0. We can easily realise that considering traditional classification, wet-type fluids have only primary (A, C and Z), dry-type fluids have primary points and exactly one secondary point (M) and redefined isentropic-type fluids have both primary and secondary points (M and N) as well. See figure for better understanding.
The ascending order of entropy values of the characteristic points gives a useful tool to define categories. The mathematically possible number of orderings are 3! (if there are no secondary points), 4! (if only secondary point M exists) and 5! (if both secondary points exist), which makes it 150. There are some physical constraints including the existence of the secondary points decrease the number of possible categories to 8. The categories are to be named after the ascending order of the entropy of their characteristic points. Namely the possible 8 categories are ACZ, ACZM, AZCM, ANZCM, ANCZM, ANCMZ, ACNZM and ACNMZ. The categories (also called sequences) can be fitted into the traditional three-class classification, which makes the two classification system compatible. No working fluids have been found, which could be fitted into ACZM or ACNZM categories. Theoretical studies confirmed that these two categories may not even exist. Based on the database of NIST, the proved 6 sequences of the novel classification and their relation to the traditional one can be seen in the figure. | 0 | Theoretical and Fundamental Chemistry |
A YAC is built using an initial circular DNA plasmid, which is typically cut into a linear DNA molecule using restriction enzymes; DNA ligase is then used to ligate a DNA sequence or gene of interest into the linearized DNA, forming a single large, circular piece of DNA. [https://doi.org/10.1073/pnas.87.11.4256] The basic generation of linear yeast artificial chromosomes can be broken down into 6 main steps: | 1 | Applied and Interdisciplinary Chemistry |
;Cryosurgical systems
A number of medical supply companies have developed cryogen delivery systems for cryosurgery. Most are based on the use of liquid nitrogen, although some employ the use of proprietary mixtures of gases that combine to form the cryogen. | 1 | Applied and Interdisciplinary Chemistry |
The Greenhouse Project was started in 2008 by a small group of public school parents and educators to facilitate hands-on learning, not only to teach about food and nutrition, but also to help children make educated choices regarding their impact on the environment.
The laboratory is typically built as a traditional greenhouse on school rooftops and accommodates a hydroponic urban farm and environmental science laboratory. It includes solar panels, hydroponic growing systems, a rainwater catchment system, a weather station and a vermi composting station.
Main topics of education include nutrition, water resource management, efficient land use, climate change, biodiversity, conservation, contamination, pollution, waste management, and sustainable development. Students learn the relationship between humans and the environment and gain a greater appreciation of sustainable development and its direct relationship to cultural diversity. | 1 | Applied and Interdisciplinary Chemistry |
*X-ray crystallography
*NMR
*Electron microscopy
*Molecular dynamics
*Mass spectrometry
*Isotopic labeling | 1 | Applied and Interdisciplinary Chemistry |
Secondary treatment systems are classified as fixed-film or suspended-growth systems A great number of secondary treatment processes exist, see List of wastewater treatment technologies. The main ones are explained below. | 1 | Applied and Interdisciplinary Chemistry |
Early vacuum experimenters found a rather surprising behavior. An arc would sometimes take place in a long irregular path rather than at the minimal distance between the electrodes. For example, in air, at a pressure of one atmosphere, the distance for minimal breakdown voltage is about 7.5 μm. The voltage required to arc this distance is 327 V, which is insufficient to ignite the arcs for gaps that are either wider or narrower. For a 3.5 μm gap, the required voltage is 533 V, nearly twice as much. If 500 V were applied, it would not be sufficient to arc at the 2.85 μm distance, but would arc at a 7.5 μm distance.
Paschen found that breakdown voltage was described by the equation
where is the breakdown voltage in volts, is the pressure in pascals, is the gap distance in meters, is the secondary-electron-emission coefficient (the number of secondary electrons produced per incident positive ion), is the saturation ionization in the gas at a particular (electric field/pressure), and is related to the excitation and ionization energies.
The constants and interpolate the first Townsend coefficient . They are determined experimentally and found to be roughly constant over a restricted range of for any given gas. For example, air with an in the range of 450 to 7500 V/(kPa·cm), = 112.50 (kPa·cm) and = 2737.50 V/(kPa·cm).
The graph of this equation is the Paschen curve. By differentiating it with respect to and setting the derivative to zero, the minimal voltage can be found. This yields
and predicts the occurrence of a minimal breakdown voltage for = 7.5×10 m·atm. This is 327 V in air at standard atmospheric pressure at a distance of 7.5 μm.
The composition of the gas determines both the minimal arc voltage and the distance at which it occurs. For argon, the minimal arc voltage is 137 V at a larger 12 μm. For sulfur dioxide, the minimal arc voltage is 457 V at only 4.4 μm. | 0 | Theoretical and Fundamental Chemistry |
The effectiveness of honeycomb, in reducing the swirl and turbulence level, is studied by simulating the flow field using standard k-ε turbulence model in commercial computational fluid dynamics (CFD). CFD is the most precise and economical approach to estimate the effectiveness of a honeycomb.
A computational domain of honeycomb is created as shown in Fig. 1
We know computationally, it is very difficult to provide the realistic non-uniform flow at the entry of honeycomb as experienced in the experiments. Such random inlet conditions would essentially simulate the realistic case in which air can enter the honeycomb from any direction and at any level of turbulence. Therefore, special domain is designed for introducing practical inlet condition
The solid model of honeycomb is meshed in GAMBIT 2.3.16. As shown in Fig. 2. A structured rectangular mesh is used for the simulation with square honeycomb configuration. Governing equations for mass and momentum conservations for subsonic flow along with the equations for turbulence and porous flow are solved for the honeycomb using commercial CFD. RANS type RNG k-ε model is used for the turbulence modeling.
The separate domain created upstream of the honeycomb is provided with various inlet conditions to arrive at the disorderly motion at the exit, which should be given as an inlet to the honeycomb cells. This essentially simulates the more realistic case that the flow can enter into the honeycomb from any direction. Specifications of this inlet along with other necessary boundary conditions are mentioned here. Flow at the inlet of the honeycomb shall necessarily have turbulent and swirling motions. Therefore, in order to incorporate these requirements, a separate fluid domain is constructed.
Top and bottom circular faces are considered as inlet to this domain to get a flow field with higher magnitude of lateral velocity. This domain is provided with vertical and horizontal cylinders as an obstruction to the inlet to produce sufficient swirling at the exit of this section. A tetrahedral mesh as shown in Fig. 3 with tetrahedral elements is generated for this geometry. The number of nodes are 1,47,666. Three faces of this configuration are specified as inlets with velocity boundary conditions. Fluid velocity at these inlet faces has been so taken that averaged mean velocity at the outlet is 1 m/s, which is in the operational wind tunnel.
A pressure outlet boundary condition is used at exit of the settling chamber where pressure at outlet is set to zero for gauge pressure.
It is always possible to predict the entire flow field by meshing whole fluid domain; however simulation for the prediction of entire flow field using symmetry boundary condition. This approach reduces the mesh requirement and computational efforts. Therefore, symmetry boundary is used at the periphery of the computational domain.
All the solid boundaries in the computational domain are specified as viscous walls with no-slip wall boundary condition.
Turbulence intensity profile at the exit of turbulence model is shown in Fig. 4. This figure shows the turbulence intensity and which is maximum at the center (30%) and at the walls is around 16-18%, now this profile is incorporated inside the honeycomb as shown in Fig. 2, the profile of turbulence intensity comes out from the honeycomb is shown in Fig. 5. In this profile we can see that the turbulence intensity is reduced from 30% to 1.2% at the center and 16% to 3.5%, it means the honeycomb effectiveness is very high which is around 96%. | 1 | Applied and Interdisciplinary Chemistry |
The lime industry is a significant carbon dioxide emitter. The manufacture of one tonne of calcium oxide involves decomposing calcium carbonate, with the formation of 785 kg of CO in some applications, such as when used as mortar; this CO is later re-absorbed as the mortar goes off.
If the heat supplied to form the lime (3.75 MJ/kg in an efficient kiln) is obtained by burning fossil fuel it will release CO: in the case of coal fuel 295 kg/t; in the case of natural gas fuel 206 kg/t. The electric power consumption of an efficient plant is around 20 kWh per tonne of lime. This additional input is the equivalent of around 20 kg CO per ton if the electricity is coal-generated. Thus, total emission may be around 1 tonne of CO for every tonne of lime even in efficient industrial plants, but is typically 1.3 t/t. However, if the source of heat energy used in its manufacture is a fully renewable power source, such as solar, wind, hydro or even nuclear; there may be no net emission of CO from the calcination process. Less energy is required in production per weight than portland cement, primarily because a lower temperature is required. | 1 | Applied and Interdisciplinary Chemistry |
The methylglyoxal pathway is an offshoot of glycolysis found in some prokaryotes, which converts glucose into methylglyoxal and then into pyruvate. However unlike glycolysis the methylglyoxal pathway does not produce adenosine triphosphate, ATP. The pathway is named after the substrate methylglyoxal which has three carbons and two carbonyl groups located on the 1st carbon and one on the 2nd carbon. Methylglyoxal is, however, a reactive aldehyde that is very toxic to cells, it can inhibit growth in E. coli at milimolar concentrations. The excessive intake of glucose by a cell is the most important process for the activation of the methylglyoxal pathway. | 1 | Applied and Interdisciplinary Chemistry |
[https://digitalinsights.qiagen.com/products-overview/discovery-insights-portfolio/analysis-and-visualization/qiagen-ipa/ Ingenuity Pathway Analysis (IPA)] is a metabolic pathway analysis software package that helps researchers model, analyze, and comprehend complex biological systems by associating specific metabolites with potential metabolic pathways for data analysis. This software has been used by researchers to elucidate regulatory networks on oncometabolites like hydroxyglutarate. | 1 | Applied and Interdisciplinary Chemistry |
This step is very critical and important for any molecular-based technique since it ensures that the small RNA fragments found in the samples to be analyzed are characterized by a good level of purity and quality. There are different purification methods that can be used, based on the purposes of the experiment:
* acid guanidinium thiocyanate-phenol-chloroform extraction: it is based on the use of a guanidinium-thiocyanate solution combined with acid phenol that disrupts cell membranes bringing in solution the nucleic acids and inactivating cellular ribonucleases (chaotropic agent). After this step an aliquot of chloroform is added in order to separate the aqueous phase (containing the RNA molecules) from the organic phase (cellular debris and other contaminants).
* spin column chromatography: universally used method to purify nucleic acids that exploits a spin column containing a special resin that, after a first step of cell lysis, allows the binding of the RNA molecules, eluting unbound particles (several proteins and rRNA). The protocol includes two separate chromatographic runs: the first one is required to isolate the whole RNA content from the sample, while the second one is specific for the isolation of small RNA by adding a small RNA enriched matrix to the column and by using a specific buffer to finally elute them. This method can separate small RNA molecules without the need of adding phenol.
Once small RNAs have been isolated, it is important to quantify them and to evaluate the quality of the purification. There are two different methods to do this:
* analysis of the absorbances and gel electrophoresis: this practical approach exploits the use of a spectrophotometer to evaluate the absorbance of RNA molecules at 260 nm (1 OD = 40 μg/μL) in order to estimate their concentration and to discover possible contaminations (i.g. proteins or carbohydrates); this can be coupled with an electrophoretic run performed in denaturating conditions (8 M urea) to analyze the quality of the purification extracts (low quality extracts will be degraded and displayed as smears in the gel).
* Agilent bioanalyzer: fully automated technique that is based on the use of a special apparatus composed by a chip that allows to perform capillary electrophoresis (CE) using small aliquots of the starting samples and obtaining an electropherogram that is useful to estimate the quality of the extracts thanks to a score (ranging from 1 to 10) attributed by the system. | 1 | Applied and Interdisciplinary Chemistry |
Beginning with this initial sequence:<br />
The complement created by base pairing is:<br />
The reverse complement is:<br />
And, the inverted repeat sequence is:<br />
"nnnnnn" represents any number of intervening nucleotides. | 1 | Applied and Interdisciplinary Chemistry |
Today, the College comprises one of the largest chemistry programs in the nation, with a faculty of 96 professors, researchers, and lecturers and an enrollment of 963 undergraduate, 539 postgraduate, and 123 postdoctoral students. In the spring of 2021, the College conferred 187 bachelor's degrees and 93 graduate degrees. The faculty includes a Nobel laureate, twelve members of the National Academy of Engineering; 37 members of the National Academy of Sciences; and 34 members of the American Academy of Arts and Sciences. The College has thirty endowed chairs and professorships. | 1 | Applied and Interdisciplinary Chemistry |
Cellosaurus is an online knowledge base on cell lines, which attempts to document all cell lines used in biomedical research. It is provided by the Swiss Institute of Bioinformatics (SIB). It is an ELIXIR Core Data Resource as well as an IRDiRC's Recognized Resource. It is the contributing resource for cell lines on the Resource Identification Portal. As of December 2022, it contains information for more than 144,000 cell lines.
Its scope includes immortalised cell lines, naturally immortal cell lines (example: embryonic stem cells) and finite life cell lines when those are distributed and used widely. The Cellosaurus provides a wealth of manually curated information; for each cell line it lists a recommended name, synonyms and the species of origin. Other types of information include standardised disease terminology (for cancer or genetic disorder cell lines), the transformant used to immortalise a cell line, transfected or knocked-out genes, microsatellite instability, doubling time, gender and age of donor (patient or animal), important sequence variations, web links, publication references and cross-references to close to 100 different databases, ontologies, cell collections and other relevant resources.
Since many cell lines used in research have been misidentified or contaminated, the Cellosaurus keeps track of problematic cell lines, including all those listed in the International Cell Line Authentication Committee (ICLAC) tables. For human as well as some dog cell lines, it provides short tandem repeat (STR) profile information. Since July 2018, cell lines in the Cellosaurus are represented as items in Wikidata. In March 2020, the Cellosaurus created a page containing cell line information relevant to SARS-CoV-2 in response to the COVID-19 pandemic.
The Cellosaurus encyclopedia is widely recognized as an authoritative source for cell line information, providing unique identifiers and as source of curated information. | 1 | Applied and Interdisciplinary Chemistry |
In physics and chemistry, a selection rule, or transition rule, formally constrains the possible transitions of a system from one quantum state to another. Selection rules have been derived for electromagnetic transitions in molecules, in atoms, in atomic nuclei, and so on. The selection rules may differ according to the technique used to observe the transition. The selection rule also plays a role in chemical reactions, where some are formally spin-forbidden reactions, that is, reactions where the spin state changes at least once from reactants to products.
In the following, mainly atomic and molecular transitions are considered. | 0 | Theoretical and Fundamental Chemistry |
Cyclooxygenase-2 (COX-2) and microsomal prostaglandin E synthase-1 (mPGES-1) structures were studied using both photo-methionine (photo-activatable) and bifunctional cross linkers. Photo-methionine used in COX-2 had shown just as the bifunctional cross-linker that there was a dimeric structure which this was consistent with the crystal structure of the enzyme. In mPGES-1, the human cells (A549) had been treated with disuccinimidyl suberate (chemical cross-linker) had yielded a dimer of 33kDa and a trimer of 45kDa while it was treated with photo-methionine had yielded a dimer of the same molecular weight (33kDa) and two putative trimers (50kDa and 55kDa). Once a mPGES-1 inhibitor (MF63) was introduced; this had inhibited the formation of the 50kDa and 55kDa complexes. The dimer and trimer yielded by the chemical cross-linker was not affected by the inhibitor. Yet, photo-methionine nor disuccinimidyl suberate had not shown any protein-protein interactions between COX-2 and mPGES-1 and this could be due to various reasons. For photo-methionine; one could be due to the low incorporation at this time as it was 0.7%. So, for mPGES-1; this has 152 amino acids so only one photo-methionine would be incorporated per monomer. That also means not one specific methionine would be replaced so that results in a heterogeneous population of mPGES-1 resulting in different cross-linking. Even though it did not show any protein-protein interactions, it could be used to detect inhibitor-induced protein conformational changes in the cell membranes on top of determining oligomeric structures. | 0 | Theoretical and Fundamental Chemistry |
Many coal-firing power stations use flue-gas desulfurization (FGD) to remove sulfur-containing gases from their stack gases. For a typical coal-fired power station, FGD will remove 95% or more of the SO in the flue gases. An example of FGD is the wet scrubber which is commonly used. A wet scrubber is basically a reaction tower equipped with a fan that extracts hot smoke stack gases from a power plant into the tower. Lime or limestone in slurry form is also injected into the tower to mix with the stack gases and combine with the sulfur dioxide present. The calcium carbonate of the limestone produces pH-neutral calcium sulfate that is physically removed from the scrubber. That is, the scrubber turns sulfur pollution into industrial sulfates.
In some areas the sulfates are sold to chemical companies as gypsum when the purity of calcium sulfate is high. In others, they are placed in landfill. The effects of acid rain can last for generations, as the effects of pH level change can stimulate the continued leaching of undesirable chemicals into otherwise pristine water sources, killing off vulnerable insect and fish species and blocking efforts to restore native life.
Fluidized bed combustion also reduces the amount of sulfur emitted by power production.
Vehicle emissions control reduces emissions of nitrogen oxides from motor vehicles. | 1 | Applied and Interdisciplinary Chemistry |
Some species secrete gels that are effective in parasite control. For example, the long-finned pilot whale secretes an enzymatic gel that rests on the outer surface of this animal and helps prevent other organisms from establishing colonies on the surface of these whales' bodies.
Hydrogels existing naturally in the body include mucus, the vitreous humor of the eye, cartilage, tendons and blood clots. Their viscoelastic nature results in the soft tissue component of the body, disparate from the mineral-based hard tissue of the skeletal system. Researchers are actively developing synthetically derived tissue replacement technologies derived from hydrogels, for both temporary implants (degradable) and permanent implants (non-degradable). A review article on the subject discusses the use of hydrogels for nucleus pulposus replacement, cartilage replacement, and synthetic tissue models. | 0 | Theoretical and Fundamental Chemistry |
In Australia, the average age of women undergoing ART treatment is 35.5 years among those using their own eggs (one in four being 40 or older) and 40.5 years among those using donated eggs. While IVF is available in Australia, Australians using IVF are unable to choose their baby's gender. | 1 | Applied and Interdisciplinary Chemistry |
In 1893, the American botanist Charles Reid Barnes proposed two terms, photosyntax and photosynthesis, for the biological process of synthesis of complex carbon compounds out of carbonic acid, in the presence of chlorophyll, under the influence of light. The term photosynthesis is derived from the Greek phōs (φῶς, gleam) and sýnthesis (σύνθεσις, arranging together), while another word that he designated was photosyntax, from sýntaxis (σύνταξις, configuration). Over time, the term photosynthesis came into common usage. Later discovery of anoxygenic photosynthetic bacteria and photophosphorylation necessitated redefinition of the term. | 0 | Theoretical and Fundamental Chemistry |
The idea of a database to document all known molecular interactions was originally put forth by Tony Pawson in the 1990s and was later developed by scientists at the University of Toronto in collaboration with the University of British Columbia. The development of the Biomolecular Interaction Network Database (BIND) has been supported by grants from the Canadian Institutes of Health Research (CIHR), Genome Canada, the Canadian Foundation for Innovation and the Ontario Research and Development Fund. BIND was originally designed to be a constantly growing depository for information regarding biomolecular interactions, molecular complexes and pathways. As proteomics is a rapidly advancing field, there is a need to have information from scientific journals readily available to researchers. BIND facilitates the understanding of molecular interactions and pathways involved in cellular processes and will eventually give scientists a better understanding of developmental processes and disease pathogenesis
The major goals of the BIND project are: to create a public proteomics resource that is available to all; to create a platform to enable datamining from other sources (PreBIND); to create a platform capable of presenting visualizations of complex molecular interactions. From the beginning, BIND has been open access and software can be freely distributed and modified. Currently, BIND includes a data specification, a database and associated data mining and visualization tools. Eventually, it is hoped that BIND will be a collection of all the interactions occurring in each of the major model organisms. | 1 | Applied and Interdisciplinary Chemistry |
Typical levels of beryllium that industries may release into the air are of the order of , averaged over a 30-day period, or of workroom air for an 8-hour work shift. Compliance with the current U.S. Occupational Safety and Health Administration (OSHA) permissible exposure limit for beryllium of has been determined to be inadequate to protect workers from developing beryllium sensitization and chronic beryllium disease. The American Conference of Governmental Industrial Hygienists (ACGIH), which is an independent organization of experts in the field of occupational health, has proposed a threshold limit value (TLV) of in a 2006 Notice of Intended Change (NIC). This TLV is 40 times lower than the current OSHA permissible exposure limit, reflecting the ACGIH analysis of best available peer-reviewed research data concerning how little airborne beryllium is required to cause sensitization and chronic beryllium disease.
Because it can be difficult to control industrial exposures to beryllium, it is advisable to use any methods possible to reduce airborne and surface contamination by beryllium, to minimize the use of beryllium and beryllium-containing alloys whenever possible, and to educate people about the potential hazards if they are likely to encounter beryllium dust or fumes. It is important to damp wipe metallographic preparation equipment to prevent accumulation of dry particles. Sectioning, grinding, and polishing must be performed under sufficiently vented hoods equipped with special filters.
On 29 January 2009, the Los Alamos National Laboratory announced it was notifying nearly 2,000 current and former employees and visitors that they may have been exposed to beryllium in the lab and may be at risk of disease. Concern over possible exposure to the material was first raised in November 2008, when a box containing beryllium was received at the laboratory's short-term storage facility. | 1 | Applied and Interdisciplinary Chemistry |
Like mitochondria, chloroplasts use the potential energy stored in an H, or hydrogen ion, gradient to generate ATP energy. The two photosystems capture light energy to energize electrons taken from water, and release them down an electron transport chain. The molecules between the photosystems harness the electrons' energy to pump hydrogen ions into the thylakoid space, creating a concentration gradient, with more hydrogen ions (up to a thousand times as many) inside the thylakoid system than in the stroma. The hydrogen ions in the thylakoid space then diffuse back down their concentration gradient, flowing back out into the stroma through ATP synthase. ATP synthase uses the energy from the flowing hydrogen ions to phosphorylate adenosine diphosphate into adenosine triphosphate, or ATP. Because chloroplast ATP synthase projects out into the stroma, the ATP is synthesized there, in position to be used in the dark reactions. | 0 | Theoretical and Fundamental Chemistry |
SNP genotyping is the measurement of genetic variations of single nucleotide polymorphisms (SNPs) between members of a species. It is a form of genotyping, which is the measurement of more general genetic variation. SNPs are one of the most common types of genetic variation. An SNP is a single base pair mutation at a specific locus, usually consisting of two alleles (where the rare allele frequency is > 1%). SNPs are found to be involved in the etiology of many human diseases and are becoming of particular interest in pharmacogenetics. Because SNPs are conserved during evolution, they have been proposed as markers for use in quantitative trait loci (QTL) analysis and in association studies in place of microsatellites. The use of SNPs is being extended in the HapMap project, which aims to provide the minimal set of SNPs needed to genotype the human genome. SNPs can also provide a genetic fingerprint for use in identity testing. The increase of interest in SNPs has been reflected by the furious development of a diverse range of SNP genotyping methods. | 1 | Applied and Interdisciplinary Chemistry |
Since their discovery in the 1970s, many restriction enzymes have been identified; for example, more than 3500 different Type II restriction enzymes have been characterized. Each enzyme is named after the bacterium from which it was isolated, using a naming system based on bacterial genus, species and strain. For example, the name of the EcoRI restriction enzyme was derived as shown in the box. | 1 | Applied and Interdisciplinary Chemistry |
SOFIA provides, among other things, methods to diagnose prion diseases by detection of PrP in biological samples. Samples can be brain tissue, nerve tissue, blood, urine, lymphatic fluid, cerebrospinal fluid, or a combination thereof. Absence of PrP indicates no infection with the infectious agent up to the detection limits of the methods. Detection of a presence of PrP indicates infection with the infectious agent associated with prion disease. Infection with the prion agent may be detected in both presymptomatic and symptomatic stages of disease progression.
These and other improvements have been achieved with SOFIA. SOFIA's sensitivity and specificity eliminates the need for PK digestion to distinguish between the normal and abnormal PrP isoforms. Further detection of PrP in blood plasma has been addressed by limited protein misfolding cyclic amplification (PMCA) followed by SOFIA. Because of the sensitivity of SOFIA, PMCA cycles can be reduced, thus decreasing the chances of spontaneous PrP formation and the detection of false-positive samples. SOFIA meets the needs of increased sensitivity in the detection of prion diseases in both presymptomatic and symptomatic TSE infected animals, including humans, by providing methods of analysis using highly sensitive instrumentation, which requires less sample preparation than previously described methods, in combination with recently developed Mabs against PrP. The method of the present version of SOFIA provides sensitivity levels sufficient to detect PrP in brain tissue. When coupled with limited sPMCA, the methods of the present inventions provide sensitivity levels sufficient to detect PrP in blood plasma, tissue and other fluids collected antemortem.
The methods combine the specificity of the Mabs for antigen capture and concentration with the sensitivity of a surround optical fiber detection technology. In contrast to previously described methods for detection of PrP in brain homogenates, these techniques, when used to study brain homogenates, do not use seeded polymerization, amplification, or enzymatic digestion (for example, by proteinase K, or “PK”). This is important in that previous reports have indicated the existence of PrP isoforms with varied PK sensitivity, which decreases reliability of the assay. The sensitivity of this assay makes it suitable as a platform for rapid prion detection assay in biological fluids. In addition to prion diseases, the method may provide a means for rapid, high-throughput testing for a wide spectrum of infections and disorders.
While about 40 cycles of sPMCA combined with immunoprecipitation were found to be inadequate for PrP detection in plasma by ELISA or western blotting, the PrP has also been found to be readily measured by SOFIA methods. The limited numbers of cycles necessary for the present assay platform virtually eliminates the possibility of obtaining PMCA-related false-positive results such as those previously reported (Thorne and Terry, 2008). | 1 | Applied and Interdisciplinary Chemistry |
A knockout moss is a kind of genetically modified moss. One or more of the moss's specific genes are deleted or inactivated ("knocked out"), for example by gene targeting or other methods. After the deletion of a gene, the knockout moss has lost the trait encoded by this gene. Thus, the function of this gene can be inferred. This scientific approach is called reverse genetics because the scientist wants to understand the function of a specific gene. In classical genetics, the scientist starts with a phenotype of interest and searches for the gene that causes this phenotype. Knockout mosses are relevant for basic research in biology as well as in biotechnology. | 1 | Applied and Interdisciplinary Chemistry |
Water is the most abundant substance on Earths surface and also the third most abundant molecule in the universe, after and . 0.23 ppm of the earths mass is water and 97.39% of the global water volume of 1.38 km is found in the oceans.
Water is far more prevalent in the outer Solar System, beyond a point called the frost line, where the Suns radiation is too weak to vaporize solid and liquid water (as well as other elements and chemical compounds with relatively low melting points, such as methane and ammonia). In the inner Solar System, planets, asteroids, and moons formed almost entirely of metals and silicates. Water has since been delivered to the inner Solar System via an as-yet unknown mechanism, theorized to be the impacts of asteroids or comets carrying water from the outer Solar System, where bodies contain much more water ice. The difference between planetary bodies located inside and outside the frost line can be stark. Earths mass is 0.000023% water, while Tethys, a moon of Saturn, is almost entirely made of water. | 1 | Applied and Interdisciplinary Chemistry |
Air turbines spin the burr in high-speed dental handpieces, at speeds over 180,000 rpm, but with limited torque. A turbine is small enough to fit in the tip of a handpiece without adding to the weight. | 1 | Applied and Interdisciplinary Chemistry |
Lectin and antibody arrays provide high-throughput screening of many samples containing glycans. This method uses either naturally occurring lectins or artificial monoclonal antibodies, where both are immobilized on a certain chip and incubated with a fluorescent glycoprotein sample.
Glycan arrays, like that offered by the Consortium for Functional Glycomics and [http://www.zbiotech.com/ Z Biotech LLC], contain carbohydrate compounds that can be screened with lectins or antibodies to define carbohydrate specificity and identify ligands. | 0 | Theoretical and Fundamental Chemistry |
S is made by neutron bombardment of Cl
:Cl + n → S + p
It decays by beta-decay with a half-life of 87.51 days. It is used to label the sulfur-containing amino-acids methionine and cysteine. When a sulfur atom replaces an oxygen atom in a phosphate group on a nucleotide a thiophosphate is produced, so S can also be used to trace a phosphate group. | 0 | Theoretical and Fundamental Chemistry |
Inadequate magnesium intake frequently causes muscle spasms, and has been associated with cardiovascular disease, diabetes, high blood pressure, anxiety disorders, migraines, osteoporosis, and cerebral infarction. Acute deficiency (see hypomagnesemia) is rare, and is more common as a drug side-effect (such as chronic alcohol or diuretic use) than from low food intake per se, but it can occur in people fed intravenously for extended periods of time.
The most common symptom of excess oral magnesium intake is diarrhea. Supplements based on amino acid chelates (such as glycinate, lysinate etc.) are much better-tolerated by the digestive system and do not have the side-effects of the older compounds used, while sustained-release dietary supplements prevent the occurrence of diarrhea. Since the kidneys of adult humans excrete excess magnesium efficiently, oral magnesium poisoning in adults with normal renal function is very rare. Infants, which have less ability to excrete excess magnesium even when healthy, should not be given magnesium supplements, except under a physician's care.
Pharmaceutical preparations with magnesium are used to treat conditions including magnesium deficiency and hypomagnesemia, as well as eclampsia. Such preparations are usually in the form of magnesium sulfate or chloride when given parenterally. Magnesium is absorbed with reasonable efficiency (30% to 40%) by the body from any soluble magnesium salt, such as the chloride or citrate. Magnesium is similarly absorbed from Epsom salts, although the sulfate in these salts adds to their laxative effect at higher doses. Magnesium absorption from the insoluble oxide and hydroxide salts (milk of magnesia) is erratic and of poorer efficiency, since it depends on the neutralization and solution of the salt by the acid of the stomach, which may not be (and usually is not) complete.
Magnesium orotate may be used as adjuvant therapy in patients on optimal treatment for severe congestive heart failure, increasing survival rate and improving clinical symptoms and patient's quality of life.
In 2021, magnesium salts were the 211th most commonly prescribed medication in the United States, with more than 2million prescriptions. | 1 | Applied and Interdisciplinary Chemistry |
The use of oxacillin is contraindicated in individuals that have experienced a hypersensitivity reaction to any medication in the penicillin family of antibiotics. Cross-allergenicity has been documented in individuals taking oxacillin that experienced a previous hypersensitivity reaction when given cephalosporins and cephamycins. | 0 | Theoretical and Fundamental Chemistry |
Magnetoelastic filaments are one-dimensional composite structures that exhibit both magnetic and elastic properties. Interest in these materials tends to focus on the ability to precisely control mechanical events using an external magnetic field. Like piezoelectricity materials, they can be used as actuators, but do not need to be physically connected to a power source. The conformations adopted by magnetoelastic filaments are dictated by the competition between its elastic and magnetic properties. | 0 | Theoretical and Fundamental Chemistry |
The Warburg diffusion element is an equivalent electrical circuit component that models the diffusion process in dielectric spectroscopy. That element is named after German physicist Emil Warburg.
A Warburg impedance element can be difficult to recognize because it is nearly always associated with a charge-transfer resistance (see charge transfer complex) and a double-layer capacitance, but is common in many systems. The presence of the Warburg element can be recognised if a linear relationship on the log of a Bode plot ( vs. ) exists with a slope of value –1/2. | 0 | Theoretical and Fundamental Chemistry |
Current methods to radiofluorinate non-activated aromatic rings are generally limited to esoteric electrophilic [F]F reactions, transition-metal mediated, or iodonium salt based methods. The Vasdev Lab has a long-established history of labeling non-activated aromatics and recently discovered a simple synthetic strategy for incorporating [F]fluoride into non-activated aromatic molecules using spirocyclic iodoium ylide based precursors. Based on their paper in Nature Communications, a patent has been licensed by the pharmaceutical industry to employ this method for the synthesis of radiopharmaceuticals in humans. Hence, the iodonium ylide technology for fluorination represents a major advance for PET imaging. | 0 | Theoretical and Fundamental Chemistry |