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To determine the fundamental model for any process, the inputs and outputs of the system are defined differently than for other chemical processes. The balance equations are defined by the control inputs and outputs rather than the material inputs. The control model is a set of equations used to predict the behavior of a system and can help determine what the response to change will be. The state variable (x) is a measurable variable that is a good indicator of the state of the system, such as temperature (energy balance), volume (mass balance) or concentration (component balance). Input variable (u) is a specified variable that commonly include flow rates.
It is important to note that the entering and exiting flows are both considered control inputs. The control input can be classified as a manipulated, disturbance, or unmonitored variable. Parameters (p) are usually a physical limitation and something that is fixed for the system, such as the vessel volume or the viscosity of the material. Output (y) is the metric used to determine the behavior of the system. The control output can be classified as measured, unmeasured, or unmonitored. | 1 | Applied and Interdisciplinary Chemistry |
Nitrogen assimilation is the formation of organic nitrogen compounds like amino acids from inorganic nitrogen compounds present in the environment. Organisms like plants, fungi and certain bacteria that can fix nitrogen gas (N) depend on the ability to assimilate nitrate or ammonia for their needs. Other organisms, like animals, depend entirely on organic nitrogen from their food. | 1 | Applied and Interdisciplinary Chemistry |
There are no general solutions to the general dynamic equation (GDE); common methods used to solve the general dynamic equation include:
* Moment method
* Modal/sectional method, and
* Quadrature method of moments/Taylor-series expansion method of moments, and
* Monte Carlo method. | 0 | Theoretical and Fundamental Chemistry |
2,6-Di-tert-butylpyridine is prepared by the reaction of tert-butyllithium with pyridine. The synthesis is reminiscent of the Chichibabin reaction.
Some related bulky pyridine compounds have been described, including 2,4,6-tri-t-butylpyridine and 2,6-di-tert-butyl-4-methylpyridine. | 0 | Theoretical and Fundamental Chemistry |
Shaw was born on 28 March 1930 in Springhead (then in the West Riding of Yorkshire). His parents were Tom and Vera Shaw. He was educated at Hulme Grammar School in Oldham.
Shaw married Mary Elizabeth Neild in 1951. | 0 | Theoretical and Fundamental Chemistry |
Phosphagens, also known as macroergic compounds, are high energy storage compounds, also known as high-energy phosphate compounds, chiefly found in muscular tissue in animals. They allow a high-energy phosphate pool to be maintained in a concentration range, which, if it all were adenosine triphosphate (ATP), would create problems due to the ATP-consuming reactions in these tissues. As muscle tissues can have sudden demands for much energy, these compounds can maintain a reserve of high-energy phosphates that can be used as needed, to provide the energy that could not be immediately supplied by glycolysis or oxidative phosphorylation. Phosphagens supply immediate but limited energy.
The actual biomolecule used as a phosphagen is dependent on the organism. The majority of animals use arginine as phosphagen; however, the phylum Chordata (i.e., animals with spinal cords) use creatine. Creatine phosphate (CP), or phosphocreatine (PCr), is made from ATP by the enzyme creatine kinase in a reversible reaction:
* Creatine + ATP creatine phosphate + ADP + H (this reaction is Mg-dependent)
However, annelids (segmented worms) use a set of unique phosphagens; for example, earthworms use the compound lombricine.
Phosphagens were discovered by Philip Eggleton and his wife Grace Eggleton. | 1 | Applied and Interdisciplinary Chemistry |
In 1947 the couple departed Australia on the Stratheden, and from September lived in Mt. Pleasant Rd., Cambridge while McTaggart worked with inorganic chemist Harry Julius Emeléus laboratory in Downing Street. He resumed his amateur radio operation with callsign G3CUA. In 1948 he worked in Paris with Yvette Cauchois on a study concerning differences in the x-ray absorption of the elements zirconium and hafnium which they published in the Comptes Rendues' of the French Academy of Science When the need arose to separate the two metals for use in atomic reactors, their basic study contributed to further CSIRO investigations to devise an effective method.
While in Europe McTaggart visited Brussels, Eindhoven, Oslo and Porsgrunn before spending three months from September in the US, then in January 1949 returned to Australia from Vancouver on the Aorangi, to continue work at CSIRO while living in Box Hill. Daughter Jennifer was born 8 August 1950 and in December McTaggart left CSIRO, sailing with his family on the Himalaya for employment in the UK with the British company, Laporte Industries in Luton where his work found commercial potential, and during which time he made further trips, by car, through Europe before rejoining CSIRO at the end of 1952. | 0 | Theoretical and Fundamental Chemistry |
The mathematical models that describe chemical reaction kinetics provide chemists and chemical engineers with tools to better understand and describe chemical processes such as food decomposition, microorganism growth, stratospheric ozone decomposition, and the chemistry of biological systems. These models can also be used in the design or modification of chemical reactors to optimize product yield, more efficiently separate products, and eliminate environmentally harmful by-products. When performing catalytic cracking of heavy hydrocarbons into gasoline and light gas, for example, kinetic models can be used to find the temperature and pressure at which the highest yield of heavy hydrocarbons into gasoline will occur.
Chemical Kinetics is frequently validated and explored through modeling in specialized packages as a function of ordinary differential equation-solving (ODE-solving) and curve-fitting. | 0 | Theoretical and Fundamental Chemistry |
Vancomycin is indicated for the treatment of serious, life-threatening infections by Gram-positive (aerobic and/or anaerobic) bacteria unresponsive to other antibiotics.
The increasing emergence of vancomycin-resistant enterococci has resulted in the development of guidelines for use by the Centers for Disease Control Hospital Infection Control Practices Advisory Committee. These guidelines restrict use of vancomycin to these indications:
* treatment of serious infections caused by susceptible organisms resistant to penicillins (methicillin-resistant S. aureus (MRSA) and multidrug-resistant S. epidermidis (MRSE)) or in individuals with serious allergy to penicillins,
* treatment of pseudomembranous colitis caused by C. difficile; in particular, in cases of relapse or where the infection is unresponsive to metronidazole treatment (for this indication, vancomycin is given orally, rather than by its typical intravenous route),
* treatment of infections caused by Gram-positive microorganisms in patients with serious allergies to beta-lactam antimicrobials,
* antibacterial prophylaxis for endocarditis following certain procedures in penicillin-hypersensitive individuals at high risk,
* surgical prophylaxis for major procedures involving implantation of prostheses in institutions with a high rate of MRSA or MRSE,
* early in treatment as an empiric antibiotic for possible MRSA infection while waiting for culture identification of the infecting organism,
* halting the progression of primary sclerosing cholangitis and preventing symptoms; vancomycin does not cure the patient and success is limited,
* treatment of endophthalmitis by intravitreal injection for gram-positive bacteria coverage; it has been used to prevent the condition, however, is not recommended due to the risk of side effects. | 0 | Theoretical and Fundamental Chemistry |
He Jiankui, the researcher, took sperm and eggs from the couples, performed in vitro fertilisation with the eggs and sperm, and then edited the genomes of the embryos using CRISPR/Cas9. The editing targeted a gene, CCR5, that codes for a protein that HIV uses to enter cells. He was trying to reproduce the phenotype of a specific mutation in the gene, CCR5-Δ32, that few people naturally have and that possibly confers innate resistance to HIV, as seen in the case of the Berlin Patient. However, rather than introducing the known CCR5-Δ32 mutation, he introduced a frameshift mutation intended to make the CCR5 protein entirely nonfunctional. According to He, Lulu and Nana carried both functional and mutant copies of CCR5 given mosaicism inherent in the present state of the art in germ-line editing. There are forms of HIV that use a different receptor instead of CCR5; therefore, the work of He did not theoretically protect Lulu and Nana from those forms of HIV. He used a preimplantation genetic diagnosis process on the embryos that were edited, where three to five single cells were removed, and fully sequenced them to identify chimerism and off-target errors. He says that during the pregnancy, cell-free fetal DNA was fully sequenced to check for off-target errors, and an amniocentesis was offered to check for problems with the pregnancy, but the mother declined. Lulu and Nana were born in secrecy in October 2018. They were reported by He to be normal and healthy. | 1 | Applied and Interdisciplinary Chemistry |
The preparation of certified reference materials is described in general in ISO Guide 17034 and in more detail in ISO Guide 35. Preparation of biological reference standards is described in WHO Guidance. General steps required in production of a certified reference material typically include:
* Collection or synthesis of material
* Sample preparation (including homogenization, stabilization, bottling etc.)
* Homogeneity testing
* Stability assessment
* Value assignment ("characterization" in ISO REMCO terms).
In addition it may be important to assess the commutability of a reference material; this is especially important for biological materials. | 0 | Theoretical and Fundamental Chemistry |
Imine formation is an important reaction. Primary amines react with ketones and aldehydes to form imines. In the case of formaldehyde (R' H), these products typically exist as cyclic trimers.
Reduction of these imines gives secondary amines:
Similarly, secondary amines react with ketones and aldehydes to form enamines: | 0 | Theoretical and Fundamental Chemistry |
The Gibbs–Donnan effect (also known as the Donnan's effect, Donnan law, Donnan equilibrium, or Gibbs–Donnan equilibrium) is a name for the behaviour of charged particles near a semi-permeable membrane that sometimes fail to distribute evenly across the two sides of the membrane. The usual cause is the presence of a different charged substance that is unable to pass through the membrane and thus creates an uneven electrical charge. For example, the large anionic proteins in blood plasma are not permeable to capillary walls. Because small cations are attracted, but are not bound to the proteins, small anions will cross capillary walls away from the anionic proteins more readily than small cations.
Thus, some ionic species can pass through the barrier while others cannot. The solutions may be gels or colloids as well as solutions of electrolytes, and as such the phase boundary between gels, or a gel and a liquid, can also act as a selective barrier. The electric potential arising between two such solutions is called the Donnan potential.
The effect is named after the American physicist Josiah Willard Gibbs who proposed it in 1878 and the British chemist Frederick G. Donnan who studied it experimentally in 1911.
The Donnan equilibrium is prominent in the triphasic model for articular cartilage proposed by Mow and Lai, as well as in electrochemical fuel cells and dialysis.
The Donnan effect is tactic pressure attributable to cations (Na and K) attached to dissolved plasma proteins. | 0 | Theoretical and Fundamental Chemistry |
Though often placed at the top of the alkali metal column in the periodic table, hydrogen does not, under ordinary conditions, exhibit the properties of an alkali metal. Instead, it forms diatomic molecules, similar to halogens and some nonmetals in the second period of the periodic table, such as nitrogen and oxygen. Diatomic hydrogen is a gas that, at atmospheric pressure, liquefies and solidifies only at very low temperature (20 K and 14 K respectively).
In 1935, physicists Eugene Wigner and Hillard Bell Huntington predicted that under an immense pressure of around , hydrogen would display metallic properties: instead of discrete molecules (which consist of two electrons bound between two protons), a bulk phase would form with a solid lattice of protons and the electrons delocalized throughout. Since then, producing metallic hydrogen in the laboratory has been described as "the holy grail of high-pressure physics".
The initial prediction about the amount of pressure needed was eventually shown to be too low. Since the first work by Wigner and Huntington, the more modern theoretical calculations point toward higher but potentially achievable metalization pressures of around . | 0 | Theoretical and Fundamental Chemistry |
Since 1980 two theories were worked on to explain adsorption and obtain equations that work. These two are referred to as the chi hypothesis, the quantum mechanical derivation, and excess surface work, ESW. Both these theories yield the same equation for flat surfaces:
Where U is the unit step function. The definitions of the other symbols is as follows:
where "ads" stands for "adsorbed", "m" stands for "monolayer equivalence" and "vap" is reference to the vapor pressure ("ads" and "vap" are the latest IUPAC convention but "m" has no IUAPC equivalent notation) of the liquid adsorptive at the same temperature as the solid sample. The unit function creates the definition of the molar energy of adsorption for the first adsorbed molecule by:
The plot of adsorbed versus is referred to as the chi plot. For flat surfaces, the slope of the chi plot yields the surface area. Empirically, this plot was notice as being a very good fit to the isotherm by Polanyi and also by deBoer and Zwikker but not pursued. This was due to criticism in the former case by Einstein and in the latter case by Brunauer. This flat surface equation may be used as a "standard curve" in the normal tradition of comparison curves, with the exception that the porous sample's early portion of the plot of versus acts as a self-standard. Ultramicroporous, microporous and mesoporous conditions may be analyzed using this technique. Typical standard deviations for full isotherm fits including porous samples are typically less than 2%.
A typical fit to good data on a homogeneous non-porous surface is shown in figure 3. The data is by Payne, Sing and Turk and was used to create the -s standard curve. Unlike the BET, which can only be at best fit over the range of 0.05 to 0.35 of P/P, the range of the fit is the full isotherm. | 0 | Theoretical and Fundamental Chemistry |
In organic chemistry, the vanillyl group (also known as vanilloyl) is a functional group. Compounds containing a vanillyl group are called vanilloids, and include vanillin, vanillic acid, capsaicin, vanillylmandelic acid, etc. | 0 | Theoretical and Fundamental Chemistry |
Periodic ordered lattices behave as linear viscoelastic solids when subjected to small amplitude mechanical deformations. Okano's group experimentally correlated the shear modulus to the frequency of standing shear modes using mechanical resonance techniques in the ultrasonic range (40 to 70 kHz). In oscillatory experiments at lower frequencies (< 40 Hz), the fundamental mode of vibration as well as several higher frequency partial overtones (or harmonics) have been observed. Structurally, most systems exhibit a clear instability toward the formation of periodic domains of relatively short-range order Above a critical amplitude of oscillation, plastic deformation is the primary mode of structural rearrangement. | 0 | Theoretical and Fundamental Chemistry |
The English word "chitin" comes from the French word chitine, which was derived in 1821 from the Greek word χιτών (khitōn) meaning covering.
A similar word, "chiton", refers to a marine animal with a protective shell. | 1 | Applied and Interdisciplinary Chemistry |
A protein-based chiral stationary phase is based on silica-gel, on which a protein is immobilized or bonded. The protein is based on many chiral centers, therefore the mechanism of chiral interaction between the protein and the analytes involves many interactions, such as hydrophobic and electrostatic interactions, hydrogen bonding and charge-transfer interactions, which may contribute to chiral recognition. Hydrophobic interactions between the protein and the analyte are affected by percent organic in the mobile phase. As the organic content increases, retention on protein-based columns decreases. | 0 | Theoretical and Fundamental Chemistry |
Methylene (IUPAC name: Methylidene, also called carbene or methene) is an organic compound with the chemical formula (also written ). It is a colourless gas that fluoresces in the mid-infrared range, and only persists in dilution, or as an adduct.
Methylene is the simplest carbene. It is usually detected only at very low temperatures, or as a short-lived intermediate in chemical reactions. | 0 | Theoretical and Fundamental Chemistry |
Herman Thompson Briscoe (November 6, 1893 – October 8, 1960) was an American chemist and professor of chemistry. The Herman T. Briscoe Professorship in Chemistry at Indiana University was established in 1961, and the Herman T. Briscoe Quadrangle Dormitory was dedicated in 1966. | 0 | Theoretical and Fundamental Chemistry |
Ibuprofen was made available by prescription in the United Kingdom in 1969 and in the United States in 1974.
Ibuprofen is the International nonproprietary name (INN), British Approved Name (BAN), Australian Approved Name (AAN) and United States Adopted Name (USAN). In the United States, it has been sold under the brand-names Motrin and Advil since 1974 and 1984, respectively. Ibuprofen is commonly available in the United States up to the FDA's 1984 dose limit OTC, rarely used higher by prescription.
In 2009, the first injectable formulation of ibuprofen was approved in the United States, under the brand name Caldolor.
Ibuprofen can be taken orally (by mouth) (as a tablet, a capsule, or a suspension) and intravenously. | 0 | Theoretical and Fundamental Chemistry |
Topological ideas are relevant to fluid dynamics (including magnetohydrodynamics) at the kinematic level, since any fluid flow involves continuous deformation of any transported scalar or vector field. Problems of stirring and mixing are particularly susceptible to topological techniques. Thus, for example, the Thurston–Nielsen classification has been fruitfully applied to the problem of stirring in two-dimensions by any number of stirrers following a time-periodic stirring protocol (Boyland, Aref & Stremler 2000). Other studies are concerned with flows having chaotic particle paths, and associated exponential rates of mixing (Ottino 1989).
At the dynamic level, the fact that vortex lines are transported by any flow governed by the classical Euler equations implies conservation of any vortical structure within the flow. Such structures are characterised at least in part by the helicity of certain sub-regions of the flow field, a topological invariant of the equations. Helicity plays a central role in dynamo theory, the theory of spontaneous generation of magnetic fields in stars and planets (Moffatt 1978, Parker 1979, Krause & Rädler 1980). It is known that, with few exceptions, any statistically homogeneous turbulent flow having nonzero mean helicity in a sufficiently large expanse of conducting fluid will generate a large-scale magnetic field through dynamo action. Such fields themselves exhibit magnetic helicity, reflecting their own topologically nontrivial structure.
Much interest attaches to the determination of states of minimum energy, subject to prescribed topology. Many problems of fluid dynamics and magnetohydrodynamics fall within this category. Recent developments in topological fluid dynamics include also applications to magnetic braids in the solar corona, DNA knotting by topoisomerases, polymer entanglement in chemical physics and chaotic behavior in dynamical systems. A mathematical introduction to this subject is given by Arnold & Khesin (1998) and recent survey articles and contributions may be found in Ricca (2009), and Moffatt, Bajer & Kimura (2013).
Topology is also crucial to the structure of neutral surfaces in a fluid (such as the ocean) where the equation of state nonlinearly depends on multiple components (e.g. salinity and heat). Fluid parcels remain neutrally buoyant as they move along neutral surfaces, despite variations in salinity or heat. On such surfaces, the salinity and heat are functionally related, but this function is multivalued. The spatial regions within which this function becomes single-valued are those where there is at most one contour of salinity (or heat) per isovalue, which are precisely the regions associated with each edge of the Reeb graph of the salinity (or heat) on the surface (Stanley 2019). | 1 | Applied and Interdisciplinary Chemistry |
One of the more classic applications of DKR is Noyori's asymmetric hydrogenation. The presence of an acidic center between two carbonyl groups allows for easy epimerization at the chiral center under basic conditions. To select for one of the four possible stereoisomers, a BINAP-Ru catalyst is used to control the outcome of the reaction through the steric bulk of the phosphorus ligand. Some of the early transformations are shown below.
To further understand the stereochemical outcome, one must look at the transition state geometry.
The steric bulk of the BINAP ligand coupled with the coordination of ruthenium to the carbonyl oxygen atoms results in high selectivity for hydrogen insertion on one face. This resulting stereochemistry of (R,S) and (R,R) is obtained in 94.5% yield while the other three stereoisomers range from 0.5-3% yield. Noyori's accomplishments of 1990 paved the way for even more useful applications of DKR. | 0 | Theoretical and Fundamental Chemistry |
For a simple volume with two openings, the cross wind flow rate can be calculated using the following equation:
where is the far-field wind speed; is a local pressure drag coefficient for the building, defined at the location of the upstream opening; is a local pressure drag coefficient for the building, defined at the location of the downstream opening; is the cross-sectional area of the upstream opening; is the cross-sectional area of the downstream opening; is the discharge coefficient of the upstream opening; and is the discharge coefficient of the downstream opening.
For rooms with single opening, the calculation of ventilation rate is more complicated than cross ventilation due to the bi-directional flow and strong turbulent effect. The ventilation rate for single-sided ventilation can be accurately predicted by combining different models for mean flow, pulsating flow and eddy penetration. The mean flow rate for single-sided ventilation is determined by:
where
l = width of the window;
h = elevation of the top edge of the window;
z = elevation of neural level (where inside and outside pressure balance);
z = reference elevation where the wind velocity is measured (at 10 m) and
= mean wind velocity at the reference elevation.
As observed in the equation (1), the air exchange depends linearly on the wind speed in the urban place where the architectural project will be built. CFD (Computational Fluid Dynamics) tools and zonal modelings are usually used to design naturally ventilated buildings. Windcatchers can assist wind-driven ventilation by guiding air in and out of structures. | 1 | Applied and Interdisciplinary Chemistry |
TRANSDIP, based on a α-cyclodextrin, is the first ligand to give exclusively trans-spanned complexes, even with d metal ion halides. Xantphos is sometimes classified as a trans-spanning ligand, with less steric bulk compared to TRANSPHOS. SPANphos is comparable to XANTPHOS but more reliably trans-spanning. | 0 | Theoretical and Fundamental Chemistry |
The Manhès–David process is a refining process of the copper mattes, invented in 1880 by the French industrialist Pierre Manhès and his engineer . Inspired by the Bessemer process, it consists of the use of a converter to oxidise with air the undesirable chemical elements (mainly iron and sulfur) contained in the matte, to transform it into copper.
The quantity of the elements to be oxidized, as well as the low heat produced by the chemical reactions, lead to drastics modifications of the converter. Manhès and David designed it as a horizontal cylinder, with nozzles aligned from one end to the other. A few years later, the Americans engineers William H. Peirce and Elias Anton Cappelen Smith lined it with basic refractory materials, much more durable than that used by the French inventors. While this improvement does not alter the principles of the process, it eases its widespread use, accelerating the switchover of copper production from Britain to the United States.
At the beginning of the 21st century, the refine 90% of the copper mattes and is used in 60% of the nickel extracted. This converter, like the addition of pure oxygen, the automation of the running, the treatment of smoke and the increasing size of the tools, ensured the durability of the Manhès–David process, even if modern tools have little relationship with their ancestors. | 1 | Applied and Interdisciplinary Chemistry |
Lysine is synthesized from aspartate via the diaminopimelate (DAP) pathway. The initial two stages of the DAP pathway are catalyzed by aspartokinase and aspartate semialdehyde dehydrogenase. These enzymes play a key role in the biosynthesis of lysine, threonine, and methionine. There are two bifunctional aspartokinase/homoserine dehydrogenases, ThrA and MetL, in addition to a monofunctional aspartokinase, LysC. Transcription of aspartokinase genes is regulated by concentrations of the subsequently produced amino acids, lysine, threonine, and methionine. The higher these amino acids concentrations, the less the gene is transcribed. ThrA and LysC are also feed-back inhibited by threonine and lysine. Finally, DAP decarboxylase LysA mediates the last step of the lysine synthesis and is common for all studied bacterial species. The formation of aspartate kinase (AK), which catalyzes the phosphorylation of aspartate and initiates its conversion into other amino acids, is also inhibited by both lysine and threonine, which prevents the formation of the amino acids derived from aspartate. Additionally, high lysine concentrations inhibit the activity of dihydrodipicolinate synthase (DHPS). So, in addition to inhibiting the first enzyme of the aspartate families biosynthetic pathway, lysine also inhibits the activity of the first enzyme after the branch point, i.e. the enzyme that is specific for lysine's own synthesis. | 1 | Applied and Interdisciplinary Chemistry |
A vortex line or vorticity line is a line which is everywhere tangent to the local vorticity vector. Vortex lines are defined by the relation
where is the vorticity vector in Cartesian coordinates.
A vortex tube is the surface in the continuum formed by all vortex lines passing through a given (reducible) closed curve in the continuum. The strength of a vortex tube (also called vortex flux) is the integral of the vorticity across a cross-section of the tube, and is the same everywhere along the tube (because vorticity has zero divergence). It is a consequence of Helmholtzs theorems (or equivalently, of Kelvins circulation theorem) that in an inviscid fluid the strength of the vortex tube is also constant with time. Viscous effects introduce frictional losses and time dependence.
In a three-dimensional flow, vorticity (as measured by the volume integral of the square of its magnitude) can be intensified when a vortex line is extended — a phenomenon known as vortex stretching. This phenomenon occurs in the formation of a bathtub vortex in outflowing water, and the build-up of a tornado by rising air currents. | 1 | Applied and Interdisciplinary Chemistry |
RNA splicing errors have been estimated to occur in a third of genetic diseases. To understand pathogenesis and identify potential targets of therapeutic intervention in these diseases, explicating the splicing elements involved is essential. Determining the complete set of components involved in splicing presents many challenges due to the abundance of alternative splicing, which occurs in most human genes, and the specificity in which splicing is carried out in vivo. Splicing is distinctly conducted from cell type to cell type and across different stages of cellular development. Therefore, it is critical that any in vitro or bioinformatic assumptions about splicing regulation are confirmed in vivo. Minigenes are used to elucidate cis-regulatory elements, trans-regulatory elements and other regulators of pre-mature RNA splicing in vivo. Minigenes have been applied to the study of a diverse array of genetic diseases due to the aforementioned abundance of alternatively spliced genes and the specificity and variation observed in splicing regulation. The following are examples of minigene use in various diseases. While it is not an exhaustive list, it does provide a better understanding of how minigenes are utilized. | 1 | Applied and Interdisciplinary Chemistry |
The usual process of electrorefining copper consists of placing a copper anode (about 99.5–99.7% pure copper) in sulfuric acid (HSO) bath of copper electrolyte, together with a cathode, and passing a current between the anode and cathode through an external circuit. At the applied electropotential, copper and less noble elements dissolve in the electrolyte, while elements more noble than copper, such as gold (Au) and silver (Ag), do not. Under the influence of the applied electrical potential, copper ions migrate from the anode and deposit on the cathode, forming cathode copper.
The current IsaKidd technology represents the merger of the copper refining technologies developed by the two different organisations. The initial Isa Process development in the late 1970s, with its reusable stainless-steel cathode starter sheets, represented an advance on the previous technology of single-use starter sheets of pure copper, the production of which was a labour-intensive process.
The production of the single-use starter sheets involved laying down a sheet of copper by electrolysis on each side of a “mother plate”. Generating the sheet took a day, and thousands of sheets could be needed every day. Originally, the copper starter sheets were separated from the mother plate manually, but over time the process was automated. In addition, limitations associated with the use of copper starter sheets meant that it was difficult to meet the purity specifications of some new copper applications that were, in the 1970s and 1980s, demanding higher quality copper. | 1 | Applied and Interdisciplinary Chemistry |
It was previously thought that it was the relatively small RNA polymerase that moves along the comparatively larger DNA template during transcription. However, increasing evidence supports the notion that due to the tethering of a transcription factory to the nuclear matrix, it is in fact the large DNA template that is moved to accommodate RNA polymerisation. In vitro studies for example have shown that RNA polymerases attached to a surface are capable of both rotating the DNA template and threading it through the polymerase to start transcription; which indicates the capabilities of RNA polymerase to be a molecular motor. Chromosome Conformation Capture (3C) also supports the idea of the DNA template diffusing towards a stationary RNA polymerase.
There remains a doubt to this mechanism of transcription. Firstly, it is unknown how a stationary polymerase is capable of transcribing genes on the (+)-strand and (-)-strand at the same genomic locus at the same time. This is in addition to a lack of conclusive evidence on how the polymerase remains immobilised (how it is tethered) and what structure it is tethered to. | 1 | Applied and Interdisciplinary Chemistry |
Ribosomal RNA (rRNA) includes non-coding RNAs that play essential roles in rRNA regulation. Ribosomal RNA (rRNA) takes part in protein synthesis. Occasional RNA molecules act catalytically, as RNA enzymes (ribozymes) or take part in protein export. The most important ribozyme is the major rRNA of the large subunit of the ribosome (28s rRNA in eukaryotes). It is now accepted that 28S rRNA catalyzes the critical step in polypeptide synthesis in addition to playing a major structural role. | 1 | Applied and Interdisciplinary Chemistry |
The suction specific speed is mainly used to see if there will be problems with cavitation during the pumps operation on the suction side. It is defined by centrifugal and axial pumps inherent physical characteristics and operating point. The suction specific speed of a pump will define the range of operation in which a pump will experience stable operation. The higher the suction specific speed, then the smaller the range of stable operation, up to the point of cavitation at 8500 (unitless). The envelope of stable operation is defined in terms of the best efficiency point of the pump.
The suction specific speed is defined as:
where:
:suction specific speed
:rotational speed of pump in rpm
:flow of pump in US gallons per minute
: Net positive suction head (NPSH) required in feet at pump's best efficiency point | 1 | Applied and Interdisciplinary Chemistry |
To explain each part of the terminology, "scattering" refers to the deflection of leptons' (electron, muon, etc.) off of hadrons. Measuring the angles of deflection gives information about the nature of the process. "Inelastic" means that the target absorbs some kinetic energy. In fact, at the very high energies of leptons used, the target is "shattered" and emits many new particles. These particles are hadrons and, to oversimplify greatly, the process is interpreted as a constituent quark of the target being "knocked out" of the target hadron, and due to quark confinement, the quarks are not actually observed but instead produce the observable particles by hadronization. "Deep" refers to the high energy of the lepton, which gives it a very short wavelength and hence the ability to probe distances that are small compared with the size of the target hadron, so it can probe "deep inside" the hadron. Also, note that in the perturbative approximation it is a high-energy virtual photon emitted from the lepton and absorbed by the target hadron which transfers energy to one of its constituent quarks, as in the adjacent diagram.
Povh and Rosina pointed out that the term “deep inelastic scattering against nucleons” was coined when the quark substructure of nucleons was unknown. They prefer the term “quasielastic lepton-quark scattering”. | 0 | Theoretical and Fundamental Chemistry |
A uniform polymer (often referred to as a monodisperse polymer) is composed of molecules of the same mass. Nearly all natural polymers are uniform. Synthetic near-uniform polymer chains can be made by processes such as anionic polymerization, a method using an anionic catalyst to produce chains that are similar in length. This technique is also known as living polymerization. It is used commercially for the production of block copolymers. Uniform collections can be easily created through the use of template-based synthesis, a common method of synthesis in nanotechnology.
A polymer material is denoted by the term disperse, or non-uniform, if its chain lengths vary over a wide range of molecular masses. This is characteristic of man-made polymers. Natural organic matter produced by the decomposition of plants and wood debris in soils (humic substances) also has a pronounced polydispersed character. It is the case of humic acids and fulvic acids, natural polyelectrolyte substances having respectively higher and lower molecular weights. Another interpretation of dispersity is explained in the article Dynamic light scattering (cumulant method subheading). In this sense, the dispersity values are in the range from 0 to 1.
The dispersity (Đ), also known as the polydispersity index (PDI) or heterogeneity index, is a measure of the distribution of molecular mass in a given polymer sample. Đ (PDI) of a polymer is calculated:
where is the weight average molecular weight and is the number average molecular weight. is more sensitive to molecules of low molecular mass, while is more sensitive to molecules of high molecular mass. The dispersity indicates the distribution of individual molecular masses in a batch of polymers. Đ has a value equal to or greater than 1, but as the polymer chains approach uniform chain length, Đ approaches unity (1). For some natural polymers Đ is almost taken as unity. | 0 | Theoretical and Fundamental Chemistry |
In organic synthesis, VCl is used for the oxidative coupling of phenols. For example, it converts phenol into a mixture of 4,4-, 2,4-, and 2,2'-biphenols:
:2 CHOH + 2 VCl → HOCH–CHOH + 2 VCl + 2 HCl | 0 | Theoretical and Fundamental Chemistry |
Tributyltin azide is synthesized by the salt metathesis reaction of tributyltin chloride and sodium azide.
It is a reagent used in the synthesis of tetrazoles, which in turn are used to generate angiotensin II receptor antagonists. In some applications, tributyltin azide has been replaced by the less toxic trioctyltin azide and organoaluminium azides. | 0 | Theoretical and Fundamental Chemistry |
The database content can be viewed in self-contained, pre-defined pathways. The database can also dynamically generate interaction networks to visualize the results of database searches. Pathways and dynamically generated networks are displayed in GIF and SVG images and can be downloaded as XML (including the standard pathway interchange format, BioPAX). The entire database is also available for download. | 1 | Applied and Interdisciplinary Chemistry |
The basic term is often prefixed to define the actual purpose of the ladle. The basic ladle design can therefore include many variations that improve the usage of the ladle for specific tasks. For example:
* Casting ladle: a ladle used to pour molten metal into moulds to produce the casting.
* Transfer ladle: a ladle used to transfer a large amount of molten metal from one process to another. Typically a transfer ladle will be used to transfer molten metal from a primary melting furnace to either a holding furnace or an auto-pour unit.
* Treatment ladle: a ladle used for a process to take place within the ladle to change some aspect of the molten metal. A typical example being to convert cast iron to ductile iron by the addition of various elements into the ladle.
Unless the ladle is to be used with alloys that have very low temperature melting point, the ladle is also fitted with a refractory lining. It is the refractory lining that stops the steel vessel from suffering damage when the ladle is used to transport metals with high melting temperatures that, if the molten metal came in direct contact with the ladle shell, would rapidly melt through the shell. Refractory lining materials come in many forms and the right choice very much depends on each foundry's working practices. Traditionally ladles used to be lined using pre-cast firebricks however refractory concretes have tended to supersede these in many countries.
Foundry ladles are normally rated by their working capacity rather than by their physical size. Hand-held ladles are typically known as handshank ladles and are fitted with a long handle to keep the heat of the metal away from the person holding it. Their capacity is limited to what a man can safely handle. Larger ladles are usually referred to as geared crane ladles. Their capacity is usually determined by the ladle function. Small hand-held ladles might also be crucibles that are fitted with carrying devices. However, in most foundries, the foundry ladle refers to a steel vessel that has a lifting bail fitted so that the vessel can be carried by an overhead crane or monorail system and is also fitted with a mechanical means for rotating the vessel, usually in the form of a gearbox. The gearbox can either be manually operated or powered operation. (See the paragraph below for further details).
For the transportation of very large volumes of molten metal, such as in steel mills, the ladle can run on wheels, a purpose-built ladle transfer car or be slung from an overhead crane and will be tilted using a second overhead lifting device.
The most common shape for a ladle is a vertical cone, but other shapes are possible. Having a tapered cone as the shell adds strength and rigidity to the shell. Having the taper also helps when it comes time to remove the refractory lining. However straight sided shells are also fabricated as are other shapes.
The most common of these other shapes is known as a drum ladle and is shaped as a horizontal cylinder suspended between two bogies. Large versions, often having capacities in excess of are used in steel mills are often referred to as torpedo ladles. Torpedo ladles are commonly used to transport liquid iron from a blast furnace to another part of the steel mill. Some versions are even adapted so that they can be carried on special bogies that can be transported by either road or rail. | 1 | Applied and Interdisciplinary Chemistry |
Differential thermal analysis (DTA) is a thermoanalytic technique that is similar to differential scanning calorimetry. In DTA, the material under study and an inert reference are made to undergo identical thermal cycles, (i.e., same cooling or heating programme) while recording any temperature difference between sample and reference. This differential temperature is then plotted against time, or against temperature (DTA curve, or thermogram). Changes in the sample, either exothermic or endothermic, can be detected relative to the inert reference. Thus, a DTA curve provides data on the transformations that have occurred, such as glass transitions, crystallization, melting and sublimation. The area under a DTA peak is the enthalpy change and is not affected by the heat capacity of the sample. | 0 | Theoretical and Fundamental Chemistry |
*Thermal radiation emitted by a body at any temperature consists of a wide range of frequencies. The frequency distribution is given by Planck's law of black-body radiation for an idealized emitter as shown in the diagram at top.
*The dominant frequency (or color) range of the emitted radiation shifts to higher frequencies as the temperature of the emitter increases. For example, a red hot object radiates mainly in the long wavelengths (red and orange) of the visible band. If it is heated further, it also begins to emit discernible amounts of green and blue light, and the spread of frequencies in the entire visible range cause it to appear white to the human eye; it is white hot. Even at a white-hot temperature of 2000 K, 99% of the energy of the radiation is still in the infrared. This is determined by Wien's displacement law. In the diagram the peak value for each curve moves to the left as the temperature increases. | 0 | Theoretical and Fundamental Chemistry |
If one monomer is present in stoichiometric excess, then the equation becomes
:* r is the stoichiometric ratio of reactants, the excess reactant is conventionally the denominator so that r < 1. If neither monomer is in excess, then r = 1 and the equation reduces to the equimolar case above.
The effect of the excess reactant is to reduce the degree of polymerization for a given value of p. In the limit of complete conversion of the limiting reagent monomer, p → 1 and
Thus for a 1% excess of one monomer, r = 0.99 and the limiting degree of polymerization is 199, compared to infinity for the equimolar case. An excess of one reactant can be used to control the degree of polymerization. | 0 | Theoretical and Fundamental Chemistry |
Pentanoyl chloride is an acyl chloride derived from pentanoic acid. It is a colorless liquid that is used to attach the valeroyl group. It is usually produced by chlorination of valeric acid. | 0 | Theoretical and Fundamental Chemistry |
The same team was also involved in the claimed discovery of technetium. They reported the discovery of element 75 and element 43 in 1925 and named element 43 masurium (after Masuria in eastern Prussia, now in Poland, the region where Walter Noddacks family originated). The group bombarded columbite with a beam of electrons and deduced element 43 was present by examining X-ray diffraction spectrograms. The wavelength of the X-rays produced is related to the atomic number by a formula derived by Henry Moseley in 1913. The team claimed to detect a faint X-ray signal at a wavelength produced by element 43. Contemporary experimenters could not replicate the discovery, and it was dismissed as an error for many years. Some more recent attempts have been made to rehabilitate the Noddacks claims, but they are disproved by Paul Kurodas study on the amount of technetium that could have been present in the ores they studied: it could not have exceeded 3 × 10 μg/kg of ore, and thus would have been undetectable by the Noddacks methods. Discovery of element 43 was finally confirmed by a 1937 experiment in Sicily. | 1 | Applied and Interdisciplinary Chemistry |
Benzeneselenol, also known as selenophenol, is the organoselenium compound with the chemical formula , often abbreviated PhSeH. It is the selenium analog of phenol. This colourless, malodorous compound is a reagent in organic synthesis. | 0 | Theoretical and Fundamental Chemistry |
The unique metabolism of acetogens has significant applications in biotechnology. In carbohydrate fermentations, the decarboxylation reactions end up in the conversion of organic carbon into carbon dioxide, the main greenhouse gas. This release is no longer compatible with the need to minimize the world CO emissions. It is not only an environmental concern but also not economically profitable in the frame of the biofuel competition with fossil fuels. Acetogens can ferment glucose without CO emission and convert one glucose molecule into three molecules of acetic acid, increasing the production yield of this latter by 50%. Acetogenesis does not replace glycolysis with a different pathway, but rather captures the CO from glycolysis and uses it for acetogenesis. Although three molecules of acetic acid can be produced in this way, the production of three molecules of ethanol would require an additional reducing agent such as hydrogen gas. | 1 | Applied and Interdisciplinary Chemistry |
*First Prize – "Kisahmu Belum Berakhir" (song: music and lyrics) for Pertandingan Mencipta Lagu Patriotik Alaf Baru, by International College of Music Malaysia, 2001
*Mandarin Oriental Fan of the Arts Most Promising Artist Award, 2nd BOH Cameronian Arts Awards, 2003
*Best Male Vocal in an Album, for Dilanda Cinta, 13th Anugerah Industri Muzik, 2005
*Best Original Script (Bahasa Malaysia), for Air Con, 7th BOH Cameronian Arts Awards, 2008 | 1 | Applied and Interdisciplinary Chemistry |
The symptoms of palytoxin poisoning and how quickly they appear depend partially on how much and through what route one has been exposed, e.g. if the poison has been inhaled or if the exposure has happened via skin.
In some non-lethal cases the symptoms in people have appeared in 6–8 hours after inhalation or skin exposure, and have lasted for 1–2 days. In different animals the symptoms have appeared in 30–60 minutes after intravenous injection and after 4 hours of eye-exposure.
The most common complication of severe palytoxin poisoning is rhabdomyolysis. This involves skeletal muscle breakdown and the leakage of intracellular contents into the blood. Other symptoms in humans are bitter/metallic taste, abdominal cramps, nausea, vomiting, diarrhea, mild to acute lethargy, tingling, slow heart rate, kidney failure, impairment of sensation, muscle spasms, tremor myalgia, cyanosis, and respiratory distress. In lethal cases palytoxin usually causes death by cardiac arrest via myocardial injury.
Exposure to aerosols of palytoxin analogue ovatoxin-a have resulted mainly in respiratory illness. Other symptoms caused by these aerosols included fever associated with serious respiratory disturbances, such as bronchoconstriction, mild dyspnea, and wheezes, while conjunctivitis was observed in some cases.
Clupeotoxism, poisoning after consuming clupeoid fish, is also suggested to be caused by palytoxin. Neurological and gastrointestinal disturbances are associated with clupeotoxism. Haff disease might be related to palytoxin and is characterized by rhabdomyolysis and gastrointestinal problems. In addition to ciguatoxin, palytoxin could be related to ciguatera seafood poisoning in some cases and thus give rise to a number of symptoms in this poisoning. | 0 | Theoretical and Fundamental Chemistry |
Tengiz Beridze (Georgian: თენგიზ გიორგის ძე ბერიძე) is a Georgian biochemist. He was born on 26 October 1939 in Tbilisi, Georgian SSR, USSR. | 1 | Applied and Interdisciplinary Chemistry |
Besides involvement in the infection process, viral replicase is a directly necessary part of the packaging of RNA viruses' genetic material. This was expected due to replicase involvement already being confirmed in various other viruses. | 1 | Applied and Interdisciplinary Chemistry |
Using the Coriolis effect that causes a laterally vibrating tube to distort, a direct measurement of mass flow can be obtained in a coriolis flowmeter. Furthermore, a direct measure of the density of the fluid is obtained. Coriolis measurement can be very accurate irrespective of the type of gas or liquid that is measured; the same measurement tube can be used for hydrogen gas and bitumen without recalibration.
Coriolis flowmeters can be used for the measurement of natural gas flow. | 1 | Applied and Interdisciplinary Chemistry |
The equation is derived by solving a linearized version of the Navier–Stokes equation, in presence of gravity and a mean density gradient (with gradient-length ), for the perturbation velocity field
where is the unperturbed or basic flow. The perturbation velocity has the wave-like solution (real part understood). Using this knowledge, and the streamfunction representation
for the flow, the following dimensional form of the Taylor–Goldstein equation is obtained:
where denotes the Brunt–Väisälä frequency. The eigenvalue parameter of the problem is . If the imaginary part of the wave speed is positive, then the flow is unstable, and the small perturbation introduced to the system is amplified in time.
Note that a purely imaginary Brunt–Väisälä frequency results in a flow which is always unstable. This instability is known as the Rayleigh–Taylor instability. | 1 | Applied and Interdisciplinary Chemistry |
Colletto et al. developed a regioselective -arylation of benzo[b]thiophenes at room temperature with aryl iodides as coupling partners and sought to understand the mechanism of this reaction by performing natural abundance kinetic isotope effect measurements via single pulse NMR.
The observation of a primary C isotope effect at C3, an inverse H isotope effect, a secondary C isotope effect at C2, and the lack of an H isotope effect at C2 lead Colletto et al. to suggest a Heck-type reaction mechanism for the regioselective -arylation of benzo[b]thiophenes at room temperature with aryl iodides as coupling partners.
Frost et al. sought to understand the effects of Lewis acid additives on the mechanism of enantioselective palladium catalyzed C-N bond activation using natural abundance kinetic isotope effect measurements via single pulse NMR.
The primary C kinetic isotope effect observed in the absence of BPh suggests a reaction mechanism with rate limiting cis oxidation into the C–CN bond of the cyanoformamide. The addition of BPh causes a relative decrease in the observed C kinetic isotope effect which led Frost et al. to suggest a change in the rate limiting step from cis oxidation to coordination of palladium to the cyanoformamide. | 0 | Theoretical and Fundamental Chemistry |
If the synthesized molecules of a combinatorial library are cleaved from the solid support a soluble mixture forms. In such solution, millions of different compounds may be found. When this synthetic method was developed, it first seemed impossible to identify the molecules, and to find molecules with useful properties. Strategies for identification of the useful components had been developed, however, to solve the problem. All these strategies are based on synthesis and testing of partial libraries.
The earliest iterative strategy is described in the above-mentioned document of Furka notarized in 1982 and. The method was later independently published by Erb et al. under the name "Recursive deconvolution" | 1 | Applied and Interdisciplinary Chemistry |
Foraminifera shells are composed of calcium carbonate (CaCO) and are found in many common geological environments. The ratio of O to O in the shell is used to indirectly determine the temperature of the surrounding water at the time the shell was formed. The ratio varies slightly depending on the temperature of the surrounding water, as well as other factors such as the water's salinity, and the volume of water locked up in ice sheets.
also reflects local evaporation and freshwater input, as rainwater is O-enriched—a result of the preferential evaporation of the lighter O from seawater. Consequently, the surface ocean contains greater proportions of O around the subtropics and tropics where there is more evaporation, and lesser proportions of O in the mid-latitudes where it rains more.
Similarly, when water vapor condenses, heavier water molecules holding O atoms tend to condense and precipitate first. The water vapor gradient heading from the tropics to the poles gradually becomes more and more depleted of O. Snow falling in Canada has much less HO than rain in Florida; similarly, snow falling in the center of ice sheets has a lighter signature than that at its margins, since heavier O precipitates first.
Changes in climate that alter global patterns of evaporation and precipitation therefore change the background ratio.
Solid samples (organic and inorganic) for oxygen isotope analysis are usually stored in silver cups and measured with pyrolysis and mass spectrometry. Researchers need to avoid improper or prolonged storage of the samples for accurate measurements. | 0 | Theoretical and Fundamental Chemistry |
As mentioned before, N-acyl-homoserine lactones (AHL) are the quorum sensing signaling molecules of the gram-negative bacteria. However, these molecules may have different functional groups on their acyl chain, and also a different length of acyl chain. Therefore, there exist many different AHL signaling molecules, for example, 3-oxododecanoyl-L-homoserine lactone (3OC12-HSL) or 3-hydroxydodecanoyl-L-homoserine lactone (3OHC12-HSL). The modification of those quorum sensing (QS) signaling molecules is another sort of quorum quenching. This can be carried out by an oxidoreductase activity. As an example, we will discuss the interaction between a host, Hydra vulgaris, and the main colonizer of its epithelial cell surfaces, Curvibacter spp. Those bacteria produce 3-oxo-HSL quorum sensing molecules. However, the oxidoreductase activity of the polyp Hydra is able to modify the 3-oxo-HSL into their 3-hydroxy-HSL counterparts. We can characterize this as quorum quenching since there is an interference with quorum sensing molecules. In this case, the outcomes differ from simple QS inactivation: the host modification results in a phenotypic switch of Curvibacter, which modifies its ability to colonize the epithelial cell surfaces of H. vulgaris. | 1 | Applied and Interdisciplinary Chemistry |
*FasR: The Fas receptor (FasR), or CD95, is the most intensely studied member of the death receptor family. The gene is situated on chromosome 10 in humans and 19 in mice. Previous reports have identified as many as eight splice variants, which are translated into seven isoforms of the protein. Many of these isoforms are associated with rare haplotypes that are usually associated with a state of disease. Apoptosis-inducing Fas receptor is dubbed isoform 1 and is a type 1 transmembrane protein. It consists of three cysteine-rich pseudorepeats, a transmembrane domain, and an intracellular death domain.
*DcR3: Decoy receptor 3 (DcR3) is a recently discovered decoy receptor of the tumor necrosis factor superfamily that binds to FasL, LIGHT, and TL1A. DcR3 is a soluble receptor that has no signal transduction capabilities (hence a "decoy") and functions to prevent FasR-FasL interactions by competitively binding to membrane-bound Fas ligand and rendering them inactive. | 1 | Applied and Interdisciplinary Chemistry |
Perrin estimated the Avogadro number by a variety of methods, at the turn of the 20th century. He was awarded the 1926 Nobel Prize in Physics, largely for this work. | 0 | Theoretical and Fundamental Chemistry |
One of the first European initiatives in cleaner production was started in Austria in 1992 by the BMVIT (Bundesministerium für Verkehr, Innovation und Technologie). This resulted in two initiatives: "Prepare" and EcoProfit.
The "PIUS" initiative was founded in Germany in 1999. Since 1994, the United Nations Industrial Development Organization operates the National Cleaner Production Centre Programme with centres in Central America, South America, Africa, Asia, and Europe. | 1 | Applied and Interdisciplinary Chemistry |
Unique VUV absorbance spectra not only enable unambiguous compound identification, and allows GC run times to be deliberately shortened. VUV detectors operate at ambient pressure and are thus not flow rate limited. GC run times can be reduced by increasing the GC column flow and oven temperature program rates.
Flow rate-enhanced chromatographic compression utilizes VUV spectral deconvolution to resolve any co-elution that may result from shortening GC runtimes. VUV absorption is additive, meaning that overlapping peaks give a spectrum that corresponds to the sum absorbance of each compound. The individual contribution of each analyte can be determined if the VUV spectra for co-eluting compounds are stored in the VUV library. The ability to differentiate coeluting analyte spectra and use them to deconvolve the overlapping signals is demonstrated in Figure 4. The individual spectra of terpenes limonene and p-Cymene are shown in Panel A along with the summed absorbance of the selected retention time window (blue region in Panel B) and the fit with VUV library spectra. The R >0.999 fit result confirms their identities, and enables the deconvolution of these and other terpenes analyzed by GC-VUV as featured in Panel B.
Testing for the presence of residual solvents in Active Pharmaceutical Ingredients (APIs) is critical for patient safety and commonly follows United States Pharmacopeia (USP) Method <467> guidelines, or more broadly, International Council for Harmonization (ICH) Guideline Q3C(R6). The gas chromatography (GC) runtime suggested by USP Method 467 is approximately 60 min. A generic method for residual solvent analysis by GC-MS describes conditions that include a runtime of approximately 30 minutes. A GC-VUV and static headspace method was developed using a chromatographic compression strategy that resulted in a GC runtime of 8 minutes. The GC-VUV method uses a flow rate of 4 mL/min and an oven ramp of 35 °C (held for 1 min), followed by an increase to 245 °C at a rate of 30 °C/min.
Figure 5 compares the results when the general conditions of the GC-MS method were followed against the GC-VUV method run with Class 2 residual solvents. Tetralin eluted at approximately 35 minutes using the GC-MS method conditions, whereas the analyte had a retention time of less than 7 minutes when the GC-VUV method was applied. The co-elution of m- and p-xylene occurred in both GC-MS and GC-VUV method runs. VUV software matched the analyte absorbance of both isomers with VUV library spectra (Figure 2) to deconvolve the overlapping signals as displayed in Figure 6. Goodness of fit information ensures that the correct compound assignment takes place during the post-run data analysis.
The flow rate-enhanced chromatographic compression strategy has been applied to a diverse set of applications since the development of the GC-VUV method for residual solvents analysis. The fast GC-VUV approach reduced GC runtimes for terpene analysis from 30 minutes to 9 minutes (the deconvolution of monoterpene isomers is shown in Figure 4). It has also been demonstrated that GC runtimes as short as 14 minutes can be used for PIONA compound analysis of gasoline samples. Typical GC separation times range between 1 – 2 hours using alternative methods. | 0 | Theoretical and Fundamental Chemistry |
Bis(trimethylsilyl)acetamide (BSA) is an organosilicon compound with the formula (Me = CH). It is a colorless liquid that is soluble in diverse organic solvents, but reacts rapidly with moisture and solvents containing OH and NH groups. It is used in analytical chemistry to increase the volatility of analytes, e.g., for gas chromatography. It is also used to introduce the trimethylsilyl protecting group in organic synthesis. A related reagent is N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA). | 0 | Theoretical and Fundamental Chemistry |
A dearomatization reaction is an organic reaction in which the reactants are arenes and the products permanently lose their aromaticity. It is of some importance in synthetic organic chemistry for the organic synthesis of new building blocks and in total synthesis. Types of carbocyclic arene dearomization include hydrogenative (Birch reduction), alkylative, photochemical, thermal, oxidative, transition metal-assisted and enzymatic. | 0 | Theoretical and Fundamental Chemistry |
* Chemistry
* Chemical technology
* Biotechnology
* Material Science and Technology of Materials
* Standardization and Certification
* Technosphere Safety
* Applied Informatics
* Applied mathematics
* Management | 1 | Applied and Interdisciplinary Chemistry |
The Ramsey Group at the University of Chapel Hill is interested in utilizing micro- and nano fabrication strategies to create devices that facilitate people's ability to gather chemical and biochemical information. Their motivations for fabricating devices include clinical diagnostics, high-throughput biochemical experimentation, understanding of transport mechanisms in nanoscale-confined spaces, and development of portable mass spectrometers operating at high-pressures (>1 Torr).
Applications for the devices that they develop include drug discovery, health care, environmental monitoring, chemical process control, and high-throughput laboratory analysis and basic research.
The four main areas of active research in the Ramsey group include:
# Microchip electrospray
# Microfluidic point of care
# Microscale Ion Trap MS
# Nanofluidics | 0 | Theoretical and Fundamental Chemistry |
Klein et al. computationally analyzed the electronic structure of a high valent Nickel complex "1". This complex was previously reported to readily undergo aryl-CF bond-forming reductive elimination.
Klein et al. reported that this formally Ni(IV) complex is best described as Ni approaching the +II oxidation state. They used intrinsic bond orbital method to analyze the bonding of the complex and identified that the bond between C and Ni is polarized to Ni with the partial charge on Ni (0.988) larger than the one on C (0.973). They attributed the +II oxidation state of Ni to the oxidation of the aryl ligand due to sigma non-innocence.
Based on calculations, they also asserted that the formal reductive elimination from this complex is essentially redox neutral, with the Ni center retaining its Ni(II) state throughout the C-C bond-forming event. They interpreted the bond-formation mechanism as the nucleophilic CF group attacking the electrophilic aryl group. | 0 | Theoretical and Fundamental Chemistry |
Inverted sugar syrup for fermented water is usually home-made by fully dissolving sugar in cold tap water. Yeast requires oxygen rich water that do not exceed 25 degrees Celsius.
A common manual way to dissolve refined sugar is to mix with water in a container which is half filled, and then sealed and shaken. However, a mixer or blender may be used to automatically dissolve the sugar, in turns, if necessary. | 1 | Applied and Interdisciplinary Chemistry |
In general, action potentials that reach the synaptic knobs cause a neurotransmitter to be released into the synaptic cleft. Neurotransmitters are small molecules that may open ion channels in the postsynaptic cell; most axons have the same neurotransmitter at all of their termini. The arrival of the action potential opens voltage-sensitive calcium channels in the presynaptic membrane; the influx of calcium causes vesicles filled with neurotransmitter to migrate to the cell's surface and release their contents into the synaptic cleft. This complex process is inhibited by the neurotoxins tetanospasmin and botulinum toxin, which are responsible for tetanus and botulism, respectively. | 0 | Theoretical and Fundamental Chemistry |
When monomers with two types of functional groups A and B undergo step growth polymerisation by virtue of a reaction between A and B groups, a similar analytical results are known. See the table on the right for several examples. In this case, is the fraction of initial monomers with groups A and groups B. Suppose that A is the group that is depleted first. Random graph theory states that gelation takes place when , where the gelation conversion is and . Molecular size distribution, the molecular weight averages, and the distribution of gyration radii have known formal analytical expressions. When degree distribution , giving the fraction of monomers in the network with neighbours connected via A group and connected via B group at time is solved numerically, the gel state is detected when , where and . | 0 | Theoretical and Fundamental Chemistry |
In simple terms, phosphorescence is a process in which energy absorbed by a substance is released relatively slowly in the form of light. This is in some cases the mechanism used for glow-in-the-dark materials which are "charged" by exposure to light. Unlike the relatively swift reactions in fluorescence, such as those seen in laser mediums like the common ruby, phosphorescent materials "store" absorbed energy for a longer time, as the processes required to reemit energy occur less often. However, timescale is still only a general distinction, as there are slow-emitting fluorescent materials, for example uranyl salts, and, likewise, some phosphorescent materials like zinc sulfide (in violet) are very fast. Scientifically, the phenomena are classified by the different mechanisms that produce the light, as materials that phosphoresce may be suitable for some purposes such as lighting, but may be completely unsuitable for others that require fluorescence, like lasers. Further blurring the lines, a substance may emit light by one, two, or all three mechanisms depending on the material and excitation conditions.
When the stored energy becomes locked in by the spin of the atomic electrons, a triplet state can occur, slowing the emission of light, sometimes by several orders of magnitude. Because the atoms usually begin in a singlet state of spin, favoring fluorescence, these types of phosphors typically produce both types of emission during illumination, and then a dimmer afterglow of strictly phosphorescent light typically lasting less than a second after the illumination is switched off.
Conversely, when the stored energy is due to persistent phosphorescence, an entirely different process occurs without a fluorescence precursor. When electrons become trapped within a defect in the atomic or molecular lattice, light is prevented from reemitting until the electron can escape. To escape, the electron needs a boost of thermal energy to help spring it out of the trap and back into orbit around the atom. Only then can the atom emit a photon. Thus, persistent phosphorescence is highly dependent on the temperature of the material. | 0 | Theoretical and Fundamental Chemistry |
Prout's hypothesis was an early 19th-century attempt to explain the existence of the various chemical elements through a hypothesis regarding the internal structure of the atom. In 1815 and 1816, the English chemist William Prout published two papers in which he observed that the atomic weights that had been measured for the elements known at that time appeared to be whole multiples of the atomic weight of hydrogen. He then hypothesized that the hydrogen atom was the only truly fundamental object, which he called protyle, and that the atoms of other elements were actually groupings of various numbers of hydrogen atoms.
Prouts hypothesis was an influence on Ernest Rutherford when he succeeded in "knocking" hydrogen nuclei out of nitrogen atoms with alpha particles in 1917, and thus concluded that perhaps the nuclei of all elements were made of such particles (the hydrogen nucleus), which in 1920 he suggested be named protons, from the suffix for particles, added to the stem of Prouts word "protyle". The assumption as discussed by Rutherford was of a nucleus consisting of Z + N = A protons plus N electrons somehow trapped within thereby reducing the positive charge to +Z as observed and vaguely explaining beta decay radioactivity. Such a nuclear constitution was known to be inconsistent with dynamics either classical or early quantum but seemed inevitable until the neutron hypothesis by Rutherford and discovery by English physicist James Chadwick.
The discrepancy between Prouts hypothesis and the known variation of some atomic weights to values far from integral multiples of hydrogen, was explained between 1913 and 1932 by the discovery of isotopes and the neutron. According to the whole number rule of Francis Aston, Prouts hypothesis is correct for atomic masses of individual isotopes, with an error of at most 1%. | 1 | Applied and Interdisciplinary Chemistry |
The Casein kinase 1 family () of protein kinases are serine/threonine-selective enzymes that function as regulators of signal transduction pathways in most eukaryotic cell types. CK1 isoforms are involved in Wnt signaling, circadian rhythms, nucleo-cytoplasmic shuttling of transcription factors, DNA repair, and DNA transcription. | 1 | Applied and Interdisciplinary Chemistry |
Pressure (along with temperature) determines the super- or subcritical state of solvents as well as overall reaction kinetics and the energy inputs required to yield the desirable HTL products (oil, gas, chemicals, char etc.). | 0 | Theoretical and Fundamental Chemistry |
Identification, sampling and analysis of acid sulfate soils should be conducted in line with:
* the National acid sulfate soils sampling and identification methods manual;
* the National acid sulfate soils identification and laboratory methods manual; and
* the National Environment Protection (Assessment of Site Contamination) Measure 1999 (Cth) (Site Contamination NEPM).
The Site Contamination NEPM is not specific to acid sulfate soils and is not discussed here.
The national sampling and identification manual provides: background information on acid sulfate soil formation and disturbance processes and environmental impacts; the minimum requirements of a desktop assessment and site inspection; and a guide to sampling and field testing.
Key features of the national laboratory methods manual are:
* the action criteria triggering the need for an Acid Sulfate Soil Management Plan (ASSMP);
* a description of the key pools of actual and potential acidity; an overview of the hazards associated with the disturbance of acid sulfate soils (e.g., acidification, deoxygenation, and salinisation of soil/water systems, and mobilisation of metals/metalloids); and
* a description of the standard analytical techniques used to quantify these hazards (e.g., Acid Base Accounting, Acid Volatile Sulfide analysis, and sequential metal/metalloid extraction).
These manuals do not provide guidance on the management of acid sulfate soils. For topic-specific management strategies see:
* Guidance for the Dredging of Acid Sulfate Soil Sediments and Associated Dredge Spoil Management;
* Guidance for the Dewatering of Acid Sulfate Soils in Shallow Groundwater Environments; and
* Overview and Management of Monosulfidic Black Ooze (MBO) Accumulation in Waterways and Wetlands.
These documents are comprehensive and publicly available through the Water Quality Australia website. | 0 | Theoretical and Fundamental Chemistry |
The word transcriptome is a portmanteau of the words transcript and genome. It appeared along with other neologisms formed using the suffixes -ome and -omics to denote all studies conducted on a genome-wide scale in the fields of life sciences and technology. As such, transcriptome and transcriptomics were one of the first words to emerge along with genome and proteome. The first study to present a case of a collection of a cDNA library for silk moth mRNA was published in 1979. The first seminal study to mention and investigate the transcriptome of an organism was published in 1997 and it described 60,633 transcripts expressed in S. cerevisiae using serial analysis of gene expression (SAGE). With the rise of high-throughput technologies and bioinformatics and the subsequent increased computational power, it became increasingly efficient and easy to characterize and analyze enormous amount of data. Attempts to characterize the transcriptome became more prominent with the advent of automated DNA sequencing during the 1980s. During the 1990s, expressed sequence tag sequencing was used to identify genes and their fragments. This was followed by techniques such as serial analysis of gene expression (SAGE), cap analysis of gene expression (CAGE), and massively parallel signature sequencing (MPSS). | 1 | Applied and Interdisciplinary Chemistry |
The above-described process with the capture of two electrons and emission of two neutrinos (two-neutrino double electron capture) is allowed by the Standard Model of particle physics: No conservation laws (including lepton number conservation) are violated. However, if the lepton number is not conserved, or equivalently the neutrino is its own antiparticle, another kind of process can occur: the so-called neutrinoless double electron capture. In this case, two electrons are captured by nucleus, but neutrinos are not emitted. The energy released in this process is carried away by an internal bremsstrahlung gamma quantum.
Example:
This mode of decay has never been observed experimentally, and would contradict the Standard Model if it were observed. | 0 | Theoretical and Fundamental Chemistry |
One katal refers to an amount of enzyme that gives a catalysed rate of conversion of one mole per second. Because this is such a large unit for most enzymatic reactions, the nanokatal (nkat) is used in practice.
The katal is not used to express the rate of a reaction; that is expressed in units of concentration per second, as moles per liter per second. Rather, the katal is used to express catalytic activity, which is a property of the catalyst. | 0 | Theoretical and Fundamental Chemistry |
Oscillating binding energies of all surface chemical species introduces periodic instances of transient behavior to the catalytic surface. For slow oscillation frequencies, the transient period is only a small quantity of the oscillation time scale, and the surface reaction achieves a new steady state. However, as the oscillation frequency increases, the surface transient period approaches the timescale of the oscillation and the catalytic surface remains in a constant transient condition. A plot of the averaged turnover frequency of a reaction with respect to applied oscillation frequency identifies the resonant frequency range for which the transient conditions of the catalyst surface match the applied frequencies. The resonance band exists above the Sabatier volcano plot maximum of a static system with average reaction rates as high as five orders of magnitude faster than that achievable by conventional catalysis.
Surface binding energy oscillation also occurs to different extent with the various chemical surface species as defined by the γ parameter. For any non-unity γ system, the asymmetry in the surface energy profile results in conducting work to bias the reaction to a steady state away from equilibrium. Similar to the controlled directionality of molecular machines, the resulting ratchet (device) energy mechanism selectively moves molecules through a catalytic reaction against a free energy gradient.
Application of dynamic binding energy to a surface with multiple catalytic reactions exhibits complex behavior derived from the differences in the natural frequencies of each chemistry; these frequencies are identified by the inverse of the adsorption, desorption, and surface kinetic rate parameters. Considering a system of two parallel elementary reactions of A-to-B and A-to-C that only occur on a surface, the performance of the catalyst under dynamic conditions will result in varying capability for selecting either reaction product (B or C). For the depicted system, both reactions have the same overall thermodynamics and will produce B and C in equal amounts (50% selectivity) at chemical equilibrium. Under normal static catalyst operation, only product B can be produced at selectivities greater than 50% and product C is never favored. However, as shown, the application of surface binding dynamics in the form of a square wave at varying frequency and fixed oscillation amplitude but varying endpoints exhibits the full range of possible reactant selectivity. In the range of 1-10 Hertz, there exists a small island of parameters for which product C is highly selective; this condition is only accessible via dynamics. | 0 | Theoretical and Fundamental Chemistry |
There are many ways to define the proportionality constant of Henrys law, which can be subdivided into two fundamental types: One possibility is to put the aqueous phase into the numerator and the gaseous phase into the denominator ("aq/gas"). This results in the Henrys law solubility constant . Its value increases with increased solubility. Alternatively, numerator and denominator can be switched ("gas/aq"), which results in the Henrys law volatility constant . The value of decreases with increased solubility. IUPAC describes several variants of both fundamental types. This results from the multiplicity of quantities that can be chosen to describe the composition of the two phases. Typical choices for the aqueous phase are molar concentration (), molality (), and molar mixing ratio (). For the gas phase, molar concentration () and partial pressure () are often used. It is not possible to use the gas-phase mixing ratio () because at a given gas-phase mixing ratio, the aqueous-phase concentration depends on the total pressure and thus the ratio is not a constant. To specify the exact variant of the Henrys law constant, two superscripts are used. They refer to the numerator and the denominator of the definition. For example, refers to the Henry solubility defined as . | 0 | Theoretical and Fundamental Chemistry |
Lipid profiling is a targeted metabolomics platform that provides a comprehensive analysis of lipid species within a cell or tissue. Profiling based on electrospray ionization tandem mass spectrometry (ESI-MS/MS) is capable of providing quantitative data and is adaptable to high throughput analyses. The powerful approach of transgenics, namely deletion and/or overexpression of a gene product coupled with lipidomics, can give valuable insights into the role of biochemical pathways. Lipid profiling techniques have also been applied to plants and microorganisms such as yeast. A combination of quantitative lipidomic data in conjunction with the corresponding transcriptional data (using gene-array methods) and proteomic data (using tandem MS) enables a systems biology approach to a more in-depth understanding of the metabolic or signaling pathways of interest. | 1 | Applied and Interdisciplinary Chemistry |
The need for additional nomenclature for organometallic compounds became apparent in the mid-1950s when Dunitz, Orgel, and Rich described the structure of the "sandwich complex" ferrocene by X-ray crystallography where an iron atom is "sandwiched" between two parallel cyclopentadienyl rings. Cotton later proposed the term hapticity derived from the adjectival prefix hapto (from the Greek haptein, to fasten, denoting contact or combination) placed before the name of the olefin, where the Greek letter η (eta) is used to denote the number of contiguous atoms of a ligand that bind to a metal center. The term is usually employed to refer to ligands containing extended π-systems or where agostic bonding is not obvious from the formula. | 0 | Theoretical and Fundamental Chemistry |
The journal is abstracted and indexed in:
* BIOSIS
* Elsevier BIOBASE
* Cambridge Scientific Abstracts
* Chemical Abstracts Service
* Current Contents/Life Sciences
* MEDLINE/PubMed
* EMBASE | 0 | Theoretical and Fundamental Chemistry |
Isolated photosystems offer the most direct connection between water photolysis and anode reduction. Typically, photosystems are isolated and adsorbed to a conductive surface. A soluble redox mediator (a small molecule capable of accepting and donating electrons) may be required to improve the electrical communication between photosystem and anode. Because other cellular components required for repair are absent, biological photovoltaic systems based on isolated photosystems have relatively short lifetimes (a few hours) and often require low temperatures to improve stability. | 0 | Theoretical and Fundamental Chemistry |
A small loop is made in the end of a platinum wire and heated in a Bunsen burner flame until red hot. A stick made of another inert substance such as a magnesia stick (MgO) may also be used.
It is then dipped into powdered borax and held in the hottest part of the flame where it swells up as it loses its water of crystallization and then shrinks, forming a colourless, transparent glass-like bead (a mixture of sodium metaborate and boric anhydride).
The bead is allowed to cool and then wetted and dipped into the sample to be tested such that only a tiny amount of the substance adheres to the bead. If too much substance is used, the bead will become dark and opaque. The bead and adhering substance is then heated in the lower, reducing, part of the flame, allowed to cool, and the colour observed. It is then heated in the upper, oxidizing, part of the flame, allowed to cool, and the colour observed again.
Characteristic coloured beads are produced with salts of copper, iron, chromium, manganese, cobalt and nickel. After the test, the bead is removed by heating it to fusion point, and plunging it into a vessel of water. | 0 | Theoretical and Fundamental Chemistry |
Marquis reagent is used as a simple spot-test to presumptively identify alkaloids as well as other compounds. It is composed of a mixture of formaldehyde and concentrated sulfuric acid, which is dripped onto the substance being tested. The United States Department of Justice method for producing the reagent is the addition of 100 mL of concentrated (95–98%) sulfuric acid to 5 mL of 40% formaldehyde. Different compounds produce different color reactions. Methanol may be added to slow down the reaction process to allow better observation of the colour change. | 0 | Theoretical and Fundamental Chemistry |
Rats that were given a diet containing ptaquiloside for a prolonged period developed tumors in both the ileum and urinary bladder. Prakash, Smith and co-workers showed that ptaquiloside-induced carcinogenesis was initiated by the activation of the H-ras oncogene. Other non-ruminants such as pig, rabbit, and guinea pig, also develop syndromes after ingestion of ptaquiloside, which include haematuria, tumors and organ abnormities (see the diagram). | 0 | Theoretical and Fundamental Chemistry |
Assuming that catalytic activity largely depends on the catalyst's affinity to the transition state, one could synthesize a transition state analog (TSA), a structure that resembles the transition state of the reaction. Then one could link the TSA to a solid-support or identifiable tag and use that TSA to select an optimal catalyst from a mixture of many different potential catalysts generated chemically or biologically by a diversity oriented synthesis. This method allows quick screening of a library of diverse compounds. It does not require as much synthetic effort and it allows a study of various catalytic factors simultaneously. Hence the method could potentially yield an efficient catalyst that we could not have designed with our current knowledge.
Many catalytic antibodies were developed and studied using this approach. | 0 | Theoretical and Fundamental Chemistry |
In 2017, two research groups from ETH Zurich and from MIT reported on the creation of an ultracold quantum gas with supersolid properties. The Zurich group placed a Bose–Einstein condensate inside two optical resonators, which enhanced the atomic interactions until they started to spontaneously crystallize and form a solid that maintains the inherent superfluidity of Bose–Einstein condensates. This setting realises a special form of a supersolid, the so-called lattice supersolid, where atoms are pinned to the sites of an externally imposed lattice structure. The MIT group exposed a Bose–Einstein condensate in a double-well potential to light beams that created an effective spin–orbit coupling. The interference between the atoms on the two spin–orbit coupled lattice sites gave rise to a characteristic density modulation.
In 2019, three groups from Stuttgart, Florence, and Innsbruck observed supersolid properties in dipolar Bose–Einstein condensates formed from lanthanide atoms. In these systems, supersolidity emerges directly from the atomic interactions, without the need for an external optical lattice. This facilitated also the direct observation of superfluid flow and hence the definitive proof for the existence of the supersolid state of matter.
In 2021, dysprosium was used to create a 2-dimensional supersolid quantum gas. In 2022, the same team created a supersolid disk in a round trap.
In 2021, confocal cavity quantum electrodynamics with a Bose–Einstein condensate was used to create a supersolid that possesses a key property of solids, vibration. That is, a supersolid was created that possesses lattice phonons with a Goldstone mode dispersion exhibiting a 16 cm/s speed of sound. | 0 | Theoretical and Fundamental Chemistry |
Since the wider recognition of the importance of sanitation, marked by the UN declaring 2008 as the Year of Sanitation, there has been a steady increase in commitment, uptake, implementation, and knowledge generation in non-sewered sanitation. The incorporation of the entire sanitation management service chain in the Sustainable Development Goal (SDG) 6, as opposed to just providing access to toilets, has further established acknowledge of the importance of FSM. The SDGs were launched in 2015, and SDG 6 is for "clean water and sanitation for all by 2030"), launched in 2015, has further established acknowledgement of its importance. There has also been an increase in the incorporation of fecal sludge management in national regulations and development agency agendas, increased funding from foundations and governments, and implementation of infrastructure and service provision.
There has been a rapid increase in evidence-based research and journal publications on the topic (e.g. for Africa and Asia). There are rapidly evolving technology developments along the entire service chain. Some have the potential to alter the existing service chain, such as container-based sanitation, decentralized options, and innovations developed through the Bill & Melinda Gates Foundation Reinvent the Toilet Challenge since at least 2012.
Curriculums have been, and are continuing to be, developed and implemented. Initiatives include the Global Sanitation Graduate School, and freely available online courses, such as the Sandec MOOC series. | 1 | Applied and Interdisciplinary Chemistry |
Settling basins are used as a separation mechanism to eliminate rejected products (i.e. waste solids management strategies) of a specified size and quantity in various fields, such as aquaculture, mining, dairy, food processing, alcohol production and wine making. Regular draining and desilting of settling basins is required to maintain satisfactory performance. | 1 | Applied and Interdisciplinary Chemistry |
Starting around 1927, Paul Dirac began the process of unifying quantum mechanics with special relativity by proposing the Dirac equation for the electron. The Dirac equation achieves the relativistic description of the wavefunction of an electron that Schrödinger failed to obtain. It predicts electron spin and led Dirac to predict the existence of the positron. He also pioneered the use of operator theory, including the influential bra–ket notation, as described in his famous 1930 textbook. During the same period, Hungarian polymath John von Neumann formulated the rigorous mathematical basis for quantum mechanics as the theory of linear operators on Hilbert spaces, as described in his likewise famous 1932 textbook. These, like many other works from the founding period, still stand, and remain widely used. | 1 | Applied and Interdisciplinary Chemistry |
In chemistry, electro-osmotic flow (EOF, hyphen optional; synonymous with electro-osmosis or electro-endosmosis) is the motion of liquid induced by an applied potential across a porous material, capillary tube, membrane, microchannel, or any other fluid conduit. Because electro-osmotic velocities are independent of conduit size, as long as the electrical double layer is much smaller than the characteristic length scale of the channel, electro-osmotic flow will have little effect. Electro-osmotic flow is most significant when in small channels, and is an essential component in chemical separation techniques, notably capillary electrophoresis. Electro-osmotic flow can occur in natural unfiltered water, as well as buffered solutions. | 0 | Theoretical and Fundamental Chemistry |
In 2020, the FDA granted orphan drug designation deulinoleate ethyl for the treatment of patients with progressive supranuclear palsy (PSP). PSP is a disease involving modification and dysfunction of tau protein; mechanism of action of deulinoleate ethyl both lowers lipid peroxidation and prevents mitochondrial cell death of neurons which is associated with disease onset and progression. | 1 | Applied and Interdisciplinary Chemistry |
Though veterinarians and bovine farmers point to the effectiveness of transfaunation for treating digestive disease, many animal rights groups argue that the practice is unnecessarily harmful to the quality of life of the cannulated cow. Use of a rumen-fluid collector instead of fistulation is well tolerated by the donor cow. People for the Ethical Treatment of Animals points to the surgerys four- to six-week recovery period and suggests that arguments for the health benefits of cannulation obscure the profit motive of the dairy industry: "While some claim that this transfer can improve the health of cows, the procedure seems mostly to benefit the meat and dairy industries bottom lines—optimizing food and digestion for animals who will ultimately be exploited and slaughtered." Similarly, The New Zealand Anti-Vivisection Society describes the practice as "cruel, insensitive and barbaric [...] the epitome of using cows as mere objects, like cars with gas tanks."
The fact-checking site Snopes has determined that the description of a circulating video of a cannulated cow as "abuse" is a "miscategorization," saying that cannulation "is neither a form of abuse nor a method to increase dairy production." However, rumen cannulation has long been used by the dairy industry to study methods that improve milk production. For instance, a 1940 study used cannulated cows to determine that a vitamin-rich diet makes for more antiscorbutic milk than a vitamin-poor diet, and a 2004 study used cannulated cows to evaluate treatments for a pH imbalance called subacute ruminal acidosis that is of concern to dairy farmers primarily because it damages milk production. | 1 | Applied and Interdisciplinary Chemistry |
Nano-thermite or super-thermite is a metastable intermolecular composite (MIC) characterized by a particle size of its main constituents, a metal and a metal oxide, under 100 nanometers. This allows for high and customizable reaction rates. Nano-thermites contain an oxidizer and a reducing agent, which are intimately mixed on the nanometer scale. MICs, including nano-thermitic materials, are a type of reactive materials investigated for military use, as well as for general applications involving propellants, explosives, and pyrotechnics.
What distinguishes MICs from traditional thermites is that the oxidizer and a reducing agent, normally iron oxide and aluminium, are in the form of extremely fine powders (nanoparticles). This dramatically increases the reactivity relative to micrometre-sized powder thermite. As the mass transport mechanisms that slow down the burning rates of traditional thermites are not so important at these scales, the reaction proceeds much more quickly. | 0 | Theoretical and Fundamental Chemistry |
Radiation emitted by a moving source is subject to Doppler shift due to a finite line-of-sight velocity projection. If different parts of the emitting body have different velocities (along the line of sight), the resulting line will be broadened, with the line width proportional to the width of the velocity distribution. For example, radiation emitted from a distant rotating body, such as a star, will be broadened due to the line-of-sight variations in velocity on opposite sides of the star (this effect usually referred to as rotational broadening). The greater the rate of rotation, the broader the line. Another example is an imploding plasma shell in a Z-pinch. | 0 | Theoretical and Fundamental Chemistry |
In a jet engine, each major rotating section usually has a separate gauge devoted to monitoring its speed of rotation.
Depending on the make and model, a jet engine may have an N gauge that monitors the low-pressure compressor section and/or fan speed in turbofan engines. The gas generator section may be monitored by an N gauge, while triple spool engines may have an N gauge as well. Each engine section rotates at many thousands RPM. Their gauges therefore are calibrated in percent of a nominal speed rather than actual RPM, for ease of display and interpretation. | 1 | Applied and Interdisciplinary Chemistry |
Studies have indicated that IVF mothers show greater emotional involvement with their child, and they enjoy motherhood more than mothers by natural conception. Similarly, studies have indicated that IVF fathers express more warmth and emotional involvement than fathers by adoption and natural conception and enjoy fatherhood more. Some IVF parents become overly involved with their children. | 1 | Applied and Interdisciplinary Chemistry |
RNA splicing errors can have drastic effects on how proteins function, including the hormones secreted by the endocrine system. These effects on hormones have been identified as the cause of many endocrine disorders including thyroid-related pathological conditions, rickets, hyperinsulinemic hypoglycemia and congenital adrenal hyperplasia. One specific example of a splicing error causing an endocrine disease that has been studied using minigenes is a type of growth hormone deficiency called isolated growth hormone deficiency (IGHD), a disease that results in growth failure. IGHD type II is an autosomal dominant form caused by a mutation in the intervening sequence (IVS) adjacent to exon 3 of the gene encoding growth hormone 1, the GH-1 gene. This mutated form of IVS3 causes exon 3 to be skipped in the mRNA product. The mRNA (-E3) encodes a truncated form of hGH that then inhibits normal hGH secretion. Minigenes were used to determine that a point mutation within an intron splice enhancer (ISE) embedded in IVS3 was to blame for the skipping of E3. Moreover, it was determined that the function of the ISE is influenced by a nearby transposable AC element, revealing that this particular splicing error is caused by a trans-acting factor. | 1 | Applied and Interdisciplinary Chemistry |
Norsteroid examples include: 19-norpregnane (from pregnane), desogestrel, ethylestrenol, etynodiol diacetate, ethinylestradiol, gestrinone, levonorgestrel, norethisterone (norethindrone), norgestrel, norpregnatriene (from pregnatriene), quinestrol, 19-norprogesterone (from a progesterone), Nomegestrol acetate, 19-nortestosterone (from a testosterone), and norethisterone acetate. | 1 | Applied and Interdisciplinary Chemistry |
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