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Enantiomers of chiral compounds have similar chemical and physical properties, but can be metabolized by the body differently. This was looked at in bowhead whales (Balaena mysticetus) for two main reasons: they are large animals with slow metabolisms (meaning PCBs will accumulate in fatty tissue) and few studies have measured chiral PCBs in cetaceans. They found that the average PCB concentrations in the blubber were approximately four times higher than the liver; however, this result is most likely age- and sex-dependent. As reproductively active females transferred PCBs and other poisonous substances to the fetus, the PCB concentrations in the blubber were significantly lower than males of the same body length (less than 13 meters). | 1 | Applied and Interdisciplinary Chemistry |
Damping serves to reduce resonance in the room, by absorption or redirection through reflection or diffusion. Absorption reduces the overall sound level, whereas redirection makes unwanted sound harmless or even beneficial by reducing coherence. Damping can be separately applied to reduce the acoustic resonance in the air or to reduce mechanical resonance in the structure of the room itself or things in the room. | 1 | Applied and Interdisciplinary Chemistry |
* Alexander Dawson School, Nothing Without Labor of Love of the Land, Alexander Dawson School, Lafayette, Colorado, 2012
* Colorado Mountain Hideaway," Previews Inc., Denver, Colorado, 1986
* Add A Fourth "R"...Responsibility," Colorado Junior Republic School, Lafayette, Colorado, ca. 1973
* CJR Health Education Center, Alexander Dawson School, Lafayette, Colorado
* The Hub, The Colorado Junior Republic, Volume 2, 1973-1974 | 0 | Theoretical and Fundamental Chemistry |
The Circe effect is a phenomenon proposed by William Jencks seen in chemistry and biochemistry where in order to speed up a reaction, the ground state of the substrate is destabilized by an enzyme. | 1 | Applied and Interdisciplinary Chemistry |
The current edition of the British Pharmacopoeia comprises six volumes, which contain nearly 3,000 monographs for drug substances, excipients, and formulated preparation, together with supporting general notices, appendices (test methods, reagents etc.), and reference spectra, used in the practice of medicine, all comprehensively indexed and cross-referenced for easy reference. Items used exclusively in veterinary medicine in the UK are included in the BP (Veterinary).
Volumes I and II
*Medicinal Substances
Volume III
*Formulated Preparations
*Blood related Preparations
*Immunological Products
*Radiopharmaceutical Preparations
*Surgical Materials
*Homeopathic Preparations
Volume IV
*Appendices
*Infrared Reference Spectra
*Index
Volume V
*British Pharmacopoeia (Veterinary)
Volume VI: (CD-ROM version)
*British Pharmacopoeia
*British Pharmacopoeia (Veterinary)
*British Approved Names
The British Pharmacopoeia is available as a printed volume and electronically in both on-line and CD-ROM versions; the electronic products use sophisticated search techniques to locate information quickly. For example, pharmacists referring to a monograph can immediately link to other related substances and appendices referenced in the content by using 130,000+ hypertext links within the text. | 1 | Applied and Interdisciplinary Chemistry |
The City of Whitwell in Tennessee is named in his honour. Tom was a founder and Chairman of the Southern States Coal, Iron and Land Company which developed coal mining in Whitwell and Iron smelting in nearby South Pittsburg. Tom visited the area at least twice hosting a banquet for five hundred workers and guests of ‘all classes’. After his death, the company was acquired by the Tennessee Coal and Iron Company. | 1 | Applied and Interdisciplinary Chemistry |
Dexlansoprazole, is a medication which reduces stomach acid. It is used to treat gastroesophageal reflux disease. Effectiveness is similar to other proton pump inhibitors (PPIs). It is taken by mouth.
Common side effects include diarrhea, abdominal pain, and nausea. Serious side effects may include osteoporosis, low blood magnesium, Clostridium difficile infection, anaphylaxis, and pneumonia. Use in pregnancy and breastfeeding is of unclear safety. It works by blocking H/K-ATPase in the parietal cells of the stomach.
Dexlansoprazole was approved for medical use in the United States in 2009. In Canada in 2016, it was the most expensive PPI available. In 2020, it was the 263rd most commonly prescribed medication in the United States, with more than 1million prescriptions. | 0 | Theoretical and Fundamental Chemistry |
Using the thermodynamic data from ITC, it is possible to deduce enzyme kinetics including proton or electron transfer, allostery and cooperativity, and enzyme inhibition. ITC collects data over time that is useful for any kinetic experiments, but especially with the proteins due to constant aliquots of injections. In terms of calculation, equilibrium constant and the slopes of binding can be directly utilized to determine the allostery and charge transfer, by comparing experimental data of different conditions (pH, use of mutated peptide chain and binding sites, etc.) . | 0 | Theoretical and Fundamental Chemistry |
The excited state of oxygen is somewhat more stable than nitrogen. While deexcitation can occur by emission of photons, the more probable mechanism at atmospheric pressure is a chemical reaction with other oxygen molecules, forming ozone:
: O* + 2 O → 2 O
This reaction is responsible for the production of ozone in the vicinity of strongly radioactive materials and electrical discharges. | 0 | Theoretical and Fundamental Chemistry |
The average coverage for a whole genome can be calculated from the length of the original genome (G), the number of reads (N), and the average read length (L) as . For example, a hypothetical genome with 2,000 base pairs reconstructed from 8 reads with an average length of 500 nucleotides will have 2× redundancy. This parameter also enables one to estimate other quantities, such as the percentage of the genome covered by reads (sometimes also called breadth of coverage). A high coverage in shotgun sequencing is desired because it can overcome errors in base calling and assembly. The subject of DNA sequencing theory addresses the relationships of such quantities. | 1 | Applied and Interdisciplinary Chemistry |
* Phase Change Material (PCM) Based Energy Storage Materials and Global Application Examples, Zafer URE M.Sc., C.Eng. MASHRAE [https://www.pcmproducts.net/Building_Temperature_Control.htm HVAC Applications]
* Phase Change Material Based Passive Cooling Systems Design Principal and Global Application Examples, Zafer URE M.Sc., C.Eng. MASHRAE [https://www.pcmproducts.net/Passive_Enclosure_Cooling.htm Passive Cooling Application] | 0 | Theoretical and Fundamental Chemistry |
Paul-Émile Lecoq de Boisbaudran, also called François Lecoq de Boisbaudran (18 April 1838 – 28 May 1912), was a French chemist known for his discoveries of the chemical elements gallium, samarium and dysprosium. He developed methods for separation and purification of the rare earth elements and was one of the pioneers of the science of spectroscopy. | 1 | Applied and Interdisciplinary Chemistry |
The IF2 initiation factor is a crucial component in the process of protein synthesis. The largest among the three indispensable translation initiation factors is IF-2, which possesses a molecular mass of 97 kDa. The protein has many domains, including an N-terminal domain, a GTPase domain, a linker region, C1, C2, and C-terminal domains. The GTPase domain encompasses the G1-G5 motif, which is responsible for the binding and hydrolysis of GTP. The activity of IF2 is regulated by conformational changes induced by the binding and hydrolysis of GTP. The primary function of IF-2 is to transport the initiator fMet-tRNA to the P-site of the 30S ribosomal subunit. The C2 domain of IF2 has a unique recognition and binding affinity towards the initiator tRNA. The IF-2 protein has been observed to form a ternary complex when interacting with GTP and fMet-tRNA. This complex has been found to interact with the 30S subunit. The initiation of mRNA translation involves the placement of the start codon in the P-site through the codon-anticodon base matching with the tRNA anti-codon. IF2 regulates start codon selection accuracy and inhibits elongator tRNAs' binding by selectively binding to fMet-tRNA. Additionally, it relocates the initiator tRNA on the 30S subunit to enhance the optimum contact with the P-site. Furthermore, IF2 exhibits RNA chaperone activity, which enables it to rectify misfolded RNA structures. In general, the IF2 protein plays a crucial role in coordinating many steps of translation initiation, including the binding of mRNA and fMet-tRNA to the start codon, the joining of sub-units, and the activation of GTPase. | 1 | Applied and Interdisciplinary Chemistry |
The EDF1 gene encodes a protein that acts as a transcriptional coactivator by interconnecting the general transcription factor TATA element-binding protein (TBP) and gene-specific activators.
TFIID and human mediator coactivator (THRAP3) complexes (mediator complex, plus THRAP3 protein) assemble cooperatively on promoter DNA, from which they become part of the RNAPII holoenzyme. | 1 | Applied and Interdisciplinary Chemistry |
In 1946, some maple syrup producers started using RO to remove water from sap before boiling the sap to syrup. RO allows about 75–90% of the water to be removed, reducing energy consumption and exposure of the syrup to high temperatures. | 0 | Theoretical and Fundamental Chemistry |
The excitation P680 → P680 of the reaction center pigment P680 occurs here. These special chlorophyll molecules embedded in PSII absorb the energy of photons, with maximal absorption at 680 nm. Electrons within these molecules are promoted to a higher-energy state. This is one of two core processes in photosynthesis, and it occurs with astonishing efficiency (greater than 90%) because, in addition to direct excitation by light at 680 nm, the energy of light first harvested by antenna proteins at other wavelengths in the light-harvesting system is also transferred to these special chlorophyll molecules.
This is followed by the electron transfer P680 → pheophytin, and then on to plastoquinol, which occurs within the reaction center of PSII. The electrons are transferred to plastoquinone and two protons, generating plastoquinol, which released into the membrane as a mobile electron carrier. This is the second core process in photosynthesis. The initial stages occur within picoseconds, with an efficiency of 100%. The seemingly impossible efficiency is due to the precise positioning of molecules within the reaction center. This is a solid-state process, not a typical chemical reaction. It occurs within an essentially crystalline environment created by the macromolecular structure of PSII. The usual rules of chemistry (which involve random collisions and random energy distributions) do not apply in solid-state environments. | 0 | Theoretical and Fundamental Chemistry |
Biological soil uptake is the dominant sink of atmospheric H. Both aerobic and anaerobic microbial metabolisms consume H by oxidizing it in order to reduce other compounds during respiration. Aerobic H oxidation is known as the Knallgas reaction.
Anaerobic H oxidation often occurs during interspecies hydrogen transfer in which H produced during fermentation is transferred to another organism, which uses the H to reduce CO to CH or acetate, to HS, or Fe to Fe. Interspecies hydrogen transfer keeps H concentrations very low in most environments because fermentation becomes less thermodynamically favorable as the partial pressure of H increases. | 1 | Applied and Interdisciplinary Chemistry |
The GFAJ-1 bacterium was discovered by geomicrobiologist Felisa Wolfe-Simon, a NASA astrobiology fellow in residence at the US Geological Survey in Menlo Park, California. GFAJ stands for "Give Felisa a Job". The organism was isolated and cultured beginning in 2009 from samples she and her colleagues collected from sediments at the bottom of Mono Lake, California, U.S.A. Mono Lake is hypersaline (about 90 grams/liter) and highly alkaline (pH 9.8). It also has one of the highest natural concentrations of arsenic in the world (200 μM). The discovery was widely publicized on 2 December 2010. | 1 | Applied and Interdisciplinary Chemistry |
Thallium compounds such as thallium sulfate have been used for impregnating wood and leather to kill fungal spores and bacteria, and for the protection of textiles from attack by moths. Thallium sulfate has been used as a depilatory and in the treatment of venereal disease, skin fungal infections, and tuberculosis. | 1 | Applied and Interdisciplinary Chemistry |
Around 4 Ga, the acidic seawater contained high amounts of HS and thus created a reducing environment with a potential of around −0.2 V. So any element that had a large negative value with respect to the reduction potential of the environment was available in its free ionic form and can subsequently be incorporated into cells, i.e. Mg has a reduction potential of −2.372 V, and was available in its ionic form at that time. | 0 | Theoretical and Fundamental Chemistry |
The basis for determination of the absolute electrode potential under the Trasatti definition is given by the equation:
where:
: is the absolute potential of the electrode made of metal M
: is the electron work function of metal M
: is the contact (Volta) potential difference at the metal(M)–solution(S) interface.
For practical purposes, the value of the absolute electrode potential of the standard hydrogen electrode is best determined with the utility of data for an ideally-polarizable mercury (Hg) electrode:
where:
: is the absolute standard potential of the hydrogen electrode
: denotes the condition of the point of zero charge at the interface.
The types of physical measurements required under the Rockwood definition are similar to those required under the Trasatti definition, but they are used in a different way, e.g. in Rockwood's approach they are used to calculate the equilibrium vapour pressure of the electron gas. The numerical value for the absolute potential of the standard hydrogen electrode one would calculate under the Rockwood definition is sometimes fortuitously close to the value one would obtain under the Trasatti definition. This near-agreement in the numerical value depends on the choice of ambient temperature and standard states, and is the result of the near-cancellation of certain terms in the expressions. For example, if a standard state of one atmosphere ideal gas is chosen for the electron gas then the cancellation of terms occurs at a temperature of 296 K, and the two definitions give an equal numerical result. At 298.15 K a near-cancellation of terms would apply and the two approaches would produce nearly the same numerical values. However, there is no fundamental significance to this near agreement because it depends on arbitrary choices, such as temperature and definitions of standard states. | 0 | Theoretical and Fundamental Chemistry |
Brownian motion is the mathematical model used to describe the random movement of particles suspended in a fluid. The gas particle animation, using pink and green particles, illustrates how this behavior results in the spreading out of gases (entropy). These events are also described by particle theory.
Since it is at the limit of (or beyond) current technology to observe individual gas particles (atoms or molecules), only theoretical calculations give suggestions about how they move, but their motion is different from Brownian motion because Brownian motion involves a smooth drag due to the frictional force of many gas molecules, punctuated by violent collisions of an individual (or several) gas molecule(s) with the particle. The particle (generally consisting of millions or billions of atoms) thus moves in a jagged course, yet not so jagged as would be expected if an individual gas molecule were examined. | 0 | Theoretical and Fundamental Chemistry |
Phase 0 and Phase I drug trials seek healthy volunteers. Most other clinical trials seek patients who have a specific disease or medical condition. The diversity observed in society should be reflected in clinical trials through the appropriate inclusion of ethnic minority populations. Patient recruitment or participant recruitment plays a significant role in the activities and responsibilities of sites conducting clinical trials.
All volunteers being considered for a trial are required to undertake a medical screening. Requirements differ according to the trial needs, but typically volunteers would be screened in a medical laboratory for:
* Measurement of the electrical activity of the heart (ECG)
* Measurement of blood pressure, heart rate, and body temperature
* Blood sampling
* Urine sampling
* Weight and height measurement
* Drug abuse testing
* Pregnancy testing
It has been observed that participants in clinical trials are disproportionately white. Often, minorities are not informed about clinical trials. One recent systematic review of the literature found that race/ethnicity as well as sex were not well-represented nor at times even tracked as participants in a large number of clinical trials of hearing loss management in adults. This may reduce the validity of findings in respect of non-white patients by not adequately representing the larger populations. | 1 | Applied and Interdisciplinary Chemistry |
Control joints, or contraction joints, are sometimes confused with expansion joints, but have a different purpose and function. Concrete and asphalt have relatively weak tensile strength, and typically form random cracks as they age, shrink, and are exposed to environmental stresses (including stresses of thermal expansion and contraction). Control joints attempt to attenuate cracking by designating lines for stress relief. They are cut into pavement at regular intervals. Cracks tend to form along the cuts, rather than in random fashion elsewhere. This is primarily an aesthetic issue; the appearance of even, regular cracking, which may be hidden in the joint’s crevice, is often preferred over random cracking.
Thus, expansion joints reduce cracks, including in the overall structure, while control joints manage cracks, primarily along the visual surface.
Roadway control joints may be sealed with hot tar, cold sealant (such as silicone), or compression sealant (such as rubber or polymers based crossed linked foams). Mortar with a breakaway bond may be used to fill some control joints.
Control joints must have adequate depth and not exceed maximum spacing for them to be effective. Typical specifications for a four-inch-thick slab are:
* 25% depth of material
* spacing at 24× to 36× of slab depth (some specification call for a maximum of 30×)
* special care for inside corners | 1 | Applied and Interdisciplinary Chemistry |
Iron(II) is oxidized by hydrogen peroxide to iron(III), forming a hydroxyl radical and a hydroxide ion in the process. Iron(III) is then reduced back to iron(II) by another molecule of hydrogen peroxide, forming a hydroperoxyl radical and a proton. The net effect is a disproportionation of hydrogen peroxide to create two different oxygen-radical species, with water (H + OH) as a byproduct.
The free radicals generated by this process engage in secondary reactions. For example, the hydroxyl is a powerful, non-selective oxidant. Oxidation of an organic compound by Fenton's reagent is rapid and exothermic and results in the oxidation of contaminants to primarily carbon dioxide and water.
Reaction () was suggested by Haber and Weiss in the 1930s as part of what would become the Haber–Weiss reaction.
Iron(II) sulfate is typically used as the iron catalyst. The exact mechanisms of the redox cycle are uncertain, and non-OH oxidizing mechanisms of organic compounds have also been suggested. Therefore, it may be appropriate to broadly discuss Fenton chemistry rather than a specific Fenton reaction.
In the electro-Fenton process, hydrogen peroxide is produced in situ from the electrochemical reduction of oxygen.
Fenton's reagent is also used in organic synthesis for the hydroxylation of arenes in a radical substitution reaction such as the classical conversion of benzene into phenol.
An example hydroxylation reaction involves the oxidation of barbituric acid to alloxane. Another application of the reagent in organic synthesis is in coupling reactions of alkanes. As an example tert-butanol is dimerized with Fentons reagent and sulfuric acid to 2,5-dimethyl-2,5-hexanediol. Fentons reagent is also widely used in the field of environmental science for water purification and soil remediation. Various hazardous wastewater were reported to be effectively degraded through Fenton's reagent. | 1 | Applied and Interdisciplinary Chemistry |
Water clarity is a descriptive term for how deeply visible light penetrates through water. In addition to light penetration, the term water clarity is also often used to describe underwater visibility. Water clarity is one way that humans measure water quality, along with oxygen concentration and the presence or absence of pollutants and algal blooms.
Water clarity governs the health of underwater ecosystems because it impacts the amount of light reaching the plants and animals living underwater. For plants, light is needed for photosynthesis. The clarity of the underwater environment determines the depth ranges where aquatic plants can live. Water clarity also impacts how well visual animals like fish can see their prey. Clarity affects the aquatic plants and animals living in all kinds of water bodies, including rivers, ponds, lakes, reservoirs, estuaries, coastal lagoons, and the open ocean.
Water clarity also affects how humans interact with water, from recreation and property values to mapping, defense, and security. Water clarity influences human perceptions of water quality, recreational safety, aesthetic appeal, and overall environmental health. Tourists visiting the Great Barrier Reef were willing to pay to improve the water clarity conditions for recreational satisfaction. Water clarity also influences waterfront property values. In the United States, a 1% improvement in water clarity increased property values by up to 10%. Water clarity is needed to visualize targets underwater, either from above or in water. These applications include mapping and military operations. To map shallow-water features such as oyster reefs and seagrass beds, the water must be clear enough for those features to be visible to a drone, airplane, or satellite. Water clarity is also needed to detect underwater objects such as submarines using visible light. | 0 | Theoretical and Fundamental Chemistry |
A trace fossil, also known as an ichnofossil (; from ikhnos "trace, track"), is a fossil record of biological activity by lifeforms but not the preserved remains of the organism itself. Trace fossils contrast with body fossils, which are the fossilized remains of parts of organisms' bodies, usually altered by later chemical activity or mineralization. The study of such trace fossils is ichnology and is the work of ichnologists.
Trace fossils may consist of physical impressions made on or in the substrate by an organism. For example, burrows, borings (bioerosion), urolites (erosion caused by evacuation of liquid wastes), footprints, feeding marks, and root cavities may all be trace fossils.
The term in its broadest sense also includes the remains of other organic material produced by an organism; for example coprolites (fossilized droppings) or chemical markers (sedimentological structures produced by biological means; for example, the formation of stromatolites). However, most sedimentary structures (for example those produced by empty shells rolling along the sea floor) are not produced through the behaviour of an organism and thus are not considered trace fossils.
The study of traces – ichnology – divides into paleoichnology, or the study of trace fossils, and neoichnology, the study of modern traces. Ichnological science offers many challenges, as most traces reflect the behaviour – not the biological affinity – of their makers. Accordingly, researchers classify trace fossils into form genera, based on their appearance and on the implied behaviour, or ethology, of their makers. | 1 | Applied and Interdisciplinary Chemistry |
The future of photopharmacology holds immense promise. It has the potential to revolutionize conventional drug therapy offering new avenues for precision medicine, treating neurological disorders, and in the field of oncology and ophthalmology. Additionally, it holds promise for the field of regenerative medicine where photoswitches can be used to modulate the activity of signaling pathways for targeted tissue repair and regeneration.
Photopharmacology will continue to grow and expand with the new discoveries and advances happening in other related fields such as synthetic chemistry, biology, nanotechnology, pharmacology, and bioengineering. While the potential of photopharmacology is vast, there are some challenges that need to be addressed to make it a clinical reality. One such challenge is the development of stable and biocompatible photoswitches that are selective for their target receptors without cross-activity. It is particularly important that these photoswitchables have their absorbance bands fall within the wavelength range of 650 nm to 900 nm. Hence, optimum molecular designing of photoswitches is required to achieve the characteristics mentioned above and desired level of performance. At present, photopharmacology uses a rational drug design approach based on studying the structure-activity relationship, however, a phenotypic screening for photoswitchable drugs could also be beneficial.
In order to achieve good spatial-temporal control over drug activity there should be a significant difference between the activity of isomers. However, understanding the structural changes during the biological effects induced by photoswitching is limited. This scarcity of knowledge is also a challenge for the growth of this field as it hampers the optimization of the activity and potency of the isomers to obtain the expected outcomes during applications.
Another hurdle, the biggest challenge in photopharmacology is finding appropriate and effective ways to deliver light to deep tissues in the body and tissues avoiding issues such as scattering and absorption. Various strategies have been attempted in this regard, one being the development of photoswitchable ligands that respond to deep-tissue penetrating wavelengths like red or infrared light. Moreover, some recent preclinical studies have spurred the development of wireless, compact or injectable, and remotely controllable devices capable of delivering light to neural tissues with minimal damage. There are novel optofluidic systems that can simultaneously regulate both drug delivery and light activity at specific sites. Although, external delivery of light is the most preferred method, the use of internal exogenous light sources such as luminescent compounds where light would be delivered directly at the site of action. This could avoid the issues related to light penetration and also enhance the degree of selectivity. In addition, this creates the opportunity to use photopharmacology as a theranostic approach that combines targeted drug delivery and molecular imaging. | 1 | Applied and Interdisciplinary Chemistry |
The equations and their parameters are calibrated for adult humans with a body mass of 70 kg and a plasma volume of ca. 2.5 L. | 1 | Applied and Interdisciplinary Chemistry |
In nuclear physics, the Bateman equation is a mathematical model describing abundances and activities in a decay chain as a function of time, based on the decay rates and initial abundances. The model was formulated by Ernest Rutherford in 1905 and the analytical solution was provided by Harry Bateman in 1910.
If, at time t, there are atoms of isotope that decays into isotope at the rate , the amounts of isotopes in the k-step decay chain evolves as:
(this can be adapted to handle decay branches). While this can be solved explicitly for i = 2, the formulas quickly become cumbersome for longer chains. The Bateman equation is a classical master equation where the transition rates are only allowed from one species (i) to the next (i+1) but never in the reverse sense (i+1 to i is forbidden).
Bateman found a general explicit formula for the amounts by taking the Laplace transform of the variables.
(it can also be expanded with source terms, if more atoms of isotope i are provided externally at a constant rate).
While the Bateman formula can be implemented in a computer code, if for some isotope pair, catastrophic cancellation can lead to computational errors. Therefore, other methods such as numerical integration or the matrix exponential method are also in use.
For example, for the simple case of a chain of three isotopes the corresponding Bateman equation reduces to
Which gives the following formula for activity of isotope (by substituting ) | 0 | Theoretical and Fundamental Chemistry |
In most GTPases, the specificity for the base guanine versus other nucleotides is imparted by the base-recognition motif, which has the consensus sequence [N/T]KXD. The following classification is based on shared features; some examples have mutations in the base-recognition motif that shift their substrate specificity, most commonly to ATP. | 1 | Applied and Interdisciplinary Chemistry |
In 2011, members of the international STAR collaboration using the Relativistic Heavy Ion Collider at the U.S. Department of Energy's Brookhaven National Laboratory detected the antimatter partner of the helium nucleus, also known as the anti-alpha. The experiment used gold ions moving at nearly the speed of light and colliding head on to produce the antiparticle. | 0 | Theoretical and Fundamental Chemistry |
The aza-Payne rearrangement may be effected in either the "forward" (epoxide to aziridine) or "reverse" (aziridine to epoxide) direction depending on the conditions employed. Electron-poor aziridines undergo the reverse rearrangement in the presence of hydride base, while the corresponding epoxy amines undergo the forward rearrangement in the presence of boron trifluoride etherate.
The thia-Payne rearrangement has only been observed in the forward direction (epoxide to thiiranium) with in situ opening of the thiiranium. Invertive nucleophilic opening at C-2 is possible through the use of trialkylaluminum reagents. | 0 | Theoretical and Fundamental Chemistry |
Ballentine earned his Ph.D. at the University of Cambridge in 1992. He went on to hold research positions at the Paul Scherrer Institut, Switzerland, the University of Michigan, and ETH Zurich, Switzerland. From 2001 to 2013, he held positions at the University of Manchester before joining the faculty at the University of Oxford.
Ballentine has held the vice president, president, and past president positions with the European Association of Geochemistry. He is a member of the Board of Governors of the Oxford Museum of Natural History and the American Geophysical Union, as well as a former scientific steering committee member for the Deep Carbon Observatory. In 2008, he won the Geological Society of London Bigsby medal for significant contributions to geology. The AGU chose Ballentine as a Fellow in 2013, and in 2016, he won the Eni Award, given to researchers who make advanced scientific breakthroughs in the field of energy, for "New Frontiers of Hydrocarbons". | 0 | Theoretical and Fundamental Chemistry |
The main components of a gamma spectrometer are the energy-sensitive radiation detector and the electronic devices that analyse the detector output signals, such as a pulse sorter (i.e., multichannel analyzer). Additional components may include signal amplifiers, rate meters, peak position stabilizers, and data handling devices. | 0 | Theoretical and Fundamental Chemistry |
In their analysis, Michaelis and Menten (and also Henri) assumed that the substrate is in instantaneous chemical equilibrium with the complex, which implies
in which e is the concentration of free enzyme (not the total concentration) and x is the concentration of enzyme-substrate complex EA.
Conservation of enzyme requires that
where is now the total enzyme concentration. After combining the two expressions some straightforward algebra leads to the following expression for the concentration of the enzyme-substrate complex:
where is the dissociation constant of the enzyme-substrate complex. Hence the rate equation is the Michaelis–Menten equation,
where corresponds to the catalytic constant and the limiting rate is . Likewise with the assumption of equilibrium the Michaelis constant . | 0 | Theoretical and Fundamental Chemistry |
A Bland–Altman plot (difference plot) in analytical chemistry or biomedicine is a method of data plotting used in analyzing the agreement between two different assays. It is identical to a Tukey mean-difference plot, the name by which it is known in other fields, but was popularised in medical statistics by J. Martin Bland and Douglas G. Altman. | 0 | Theoretical and Fundamental Chemistry |
Coefficient φ is dependent on the following;
Which reflects the competition of two processes in the resonance region: absorption of neutrons and their deceleration. The cross section Σ, by definition, is analogous to the macroscopic absorption cross section with replacement of the microscopic cross section by the effective resonance integral J. It also characterizes the loss of slowing neutrons in the resonance region. As the U concentration increases, the absorption of resonant neutrons increases and hence fewer neutrons are slowed down to thermal energies. The resonance absorption is influenced by the slowing down of neutrons. Collisions with the moderator nuclei take neutrons out of the resonance region and are more intense the greater the moderating power . So, for the same concentration of U, the probability of avoiding resonance capture in the uranium-water medium is greater than in the uranium-carbon medium.
Let us calculate the probability of avoiding resonance capture in homogeneous and heterogeneous environments natural uranium-graphite. In both media the ratio of carbon and U nuclei N/N=215. The diameter of the uranium rod is d=3 cm. Taking into account that ξC=0.159, σ=4.7 barn, we calculate the following probability;
: barn.
Calculating the coefficients φ in homogeneous and heterogeneous mixtures, we get;
: φ = e = e ≈ 0,65,
: φ = e = e ≈ 0,93.
The transition from homogeneous to heterogeneous medium slightly reduces the thermal neutron absorption in uranium. However, this loss is considerably overlapped by the decrease of the resonance neutron absorption, and the propagation properties of the medium improve. | 0 | Theoretical and Fundamental Chemistry |
Claudins allow for Mg transport via the paracellular pathway; that is, it mediates the transport of the ion through the tight junctions between cells that form an epithelial cell layer. In particular, Claudin-16 allows the selective reuptake of Mg in the human kidney. Some patients with mutations in the CLDN19 gene also have altered magnesium transport.
The gene Claudin-16 was cloned by Simon et al. (1999), but only after a series of reports described the Mg flux itself with no gene or protein. The expression pattern of the gene was determined by RT-PCR, and was shown to be very tightly confined to a continuous region of the kidney tubule running from the medullary thick descending limb to the distal convoluted tubule. This localisation was consistent with the earlier reports for the location of Mg re-uptake by the kidney. Following the cloning, mutations in the gene were identified in patients with familial hypomagnesaemia with hypercalciuria and nephrocalcinosis, strengthening the links between the gene and the uptake of Mg. | 1 | Applied and Interdisciplinary Chemistry |
The Min System is a mechanism composed of three proteins MinC, MinD, and MinE used by E. coli as a means of properly localizing the septum prior to cell division. Each component participates in generating a dynamic oscillation of FtsZ protein inhibition between the two bacterial poles to precisely specify the mid-zone of the cell, allowing the cell to accurately divide in two. This system is known to function in conjunction with a second negative regulatory system, the nucleoid occlusion system (NO), to ensure proper spatial and temporal regulation of chromosomal segregation and division. | 1 | Applied and Interdisciplinary Chemistry |
Suppose that a chemical system has elements and chemical species (elements or compounds). The latter are combinations of the former, and each species can be represented as a sum of elements:
where are the integers denoting number of atoms of element in molecule . Each species is determined by a vector (a row of this matrix), but the rows are not necessarily linearly independent. If the rank of the matrix is , then there are linearly independent vectors, and the remaining vectors can be obtained by adding up multiples of those vectors. The chemical species represented by those vectors are components of the system.
If, for example, the species are C (in the form of graphite), CO and CO, then
Since CO can be expressed as CO = (1/2)C + (1/2)CO, it is not independent and C and CO can be chosen as the components of the system.
There are two ways that the vectors can be dependent. One is that some pairs of elements always appear in the same ratio in each species. An example is a series of polymers that are composed of different numbers of identical units. The number of such constraints is given by . In addition, some combinations of elements may be forbidden by chemical kinetics. If the number of such constraints is , then
Equivalently, if is the number of independent reactions that can take place, then
The constants are related by . | 0 | Theoretical and Fundamental Chemistry |
Interleukin 10 is produced by regulatory T lymphocytes, B cells, and monocytes. It is a homodimer that functions through the IL-10R1 and IL-10R2 receptor complexes, activating such kinases as Janus kinase and tyrosine kinase 2. IL-10R2 receptor is presented in most cells, when IL-10R1 receptor is IL-10 is also an inhibitor of expressions of CD80 and CD86 by dendritic cells (DC) and antigen-presenting cells (APC), and of T cells, decreasing their cytokine production, therefore, controlling their activation. IL-10 plays a big role in regulating allergies by inhibiting cytokines responsible for allergic inflammation. | 1 | Applied and Interdisciplinary Chemistry |
Common substrates that are used as terminal electron acceptors in organohalide respiration are organochloride pesticides, aryl halides and alkyl solvents. Many of these are persistent and toxic pollutants that can only be degraded anaerobically by organohalide respiration, either partially or completely. Trichloroethylene (TCE) and tetrachloroethylene (PCE) are two examples of such pollutants, and their degradation has been a focus of research. PCE is an alkyl solvent that was previously used in dry cleaning, degreasing machinery and other applications. It remains a common contaminant of groundwater. Bacteria that are capable of completely degrading PCE to ethene, a nontoxic chemical, have been isolated. They have been found to belong to the genus Dehalococcoides and to use H as their electron donor. The process of organohalide respiration has been applied to in situ bioremediation of PCE and TCE in the past. For example, enhanced reductive dechlorination has been used to treat contaminated groundwater by introducing electron donors and dehalorespiring bacteria into the contaminated site, to create conditions that stimulate bacterial growth and organohalide respiration. In enhanced reductive dechlorination, the pollutants act as the electron acceptors and are completely reduced to ultimately produce ethene in a series of reactions. | 0 | Theoretical and Fundamental Chemistry |
Isotopic mass data from [http://physics.nist.gov/PhysRefData/Compositions/ Atomic Weights and Isotopic Compositions] ed. J. S. Coursey, D. J. Schwab and R. A. Dragoset, National Institute of Standards and Technology (2005). | 0 | Theoretical and Fundamental Chemistry |
Signaling Gateway Molecule Pages is a database containing "essential information on more than 8000 mammalian proteins (Mouse and Human) involved in cellular signaling."
The content of molecule pages is authored by invited experts and is peer-reviewed. The published pages are citable by digital object identifiers (DOIs). All data in the Molecule Pages are freely available to the public.
Data can be exported to PDF, XML, BioPAX/SBPAX and SBML.
MIRIAM Registry Details. | 1 | Applied and Interdisciplinary Chemistry |
A kinetic scheme is a network (a directed graph) of distinct states (although repetition of states may occur and this depends on the system), where each pair of states i and j are associated with directional rates, (and ). It is described with a master equation: a first-order differential equation for the probability of a system to occupy each one its states at time t (element i represents state i). Written in a matrix form, this states: , where is the matrix of connections (rates) .
In a Markovian kinetic scheme the connections are constant with respect to time (and any jumping time probability density function for state i is an exponential, with a rate equal the value of all the exiting connections).
When detailed balance exists in a system, the relation holds for every connected states i and j. The result represents the fact that any closed loop in a Markovian network in equilibrium does not have a net flow.
Matrix can also represent birth and death, meaning that probability is injected (birth) or taken from (death) the system, where then, the process is not in equilibrium. These terms are different than a birth–death process, where there is simply a linear kinetic scheme. | 0 | Theoretical and Fundamental Chemistry |
Vapor pressure is the pressure of a vapor in equilibrium with its non-vapor phases (i.e., liquid or solid). Most often the term is used to describe a liquids tendency to evaporate. It is a measure of the tendency of molecules and atoms to escape from a liquid or a solid. A liquids atmospheric pressure boiling point corresponds to the temperature at which its vapor pressure is equal to the surrounding atmospheric pressure and it is often called the normal boiling point.
The higher the vapor pressure of a liquid at a given temperature, the lower the normal boiling point of the liquid.
The vapor pressure chart displayed has graphs of the vapor pressures versus temperatures for a variety of liquids. As can be seen in the chart, the liquids with the highest vapor pressures have the lowest normal boiling points.
For example, at any given temperature, methyl chloride has the highest vapor pressure of any of the liquids in the chart. It also has the lowest normal boiling point (−24.2 °C), which is where the vapor pressure curve of methyl chloride (the blue line) intersects the horizontal pressure line of one atmosphere (atm) of absolute vapor pressure. At higher altitudes, the atmospheric pressure is less than that at sea level, so boiling points of liquids are reduced. At the top of Mount Everest, the atmospheric pressure is approximately 0.333 atm, so by using the graph, the boiling point of diethyl ether would be approximately 7.5 °C versus 34.6 °C at sea level (1 atm). | 0 | Theoretical and Fundamental Chemistry |
Oxychlorination is employed in the conversion of ethylene into vinyl chloride. In the first step in this process, ethylene undergoes oxychlorination to give ethylene chloride:
:CH=CH + 2 HCl + ½ O → ClCHCHCl + HO
Oxychlorination is of special importance in the making of 1,2-dichloroethane, which is then converted into vinyl chloride. As can be seen in the following reaction, 1,2-dichloroethane is cracked:
:ClCHCHCl → CH=CHCl + HCl
The HCl from this cracking process is recycled by oxychlorination in order to reduce the consumption of raw material HCl (or Cl, if direct chlorination of ethylene is chosen as main way to produce 1,2-dichloroethane).
Iron(III) chloride is produced commercially by oxychlorination (and other methods). For example, dissolution of iron ores in hydrochloric acid gives a mixture of ferrous and ferric chlorides:
The iron(II) chloride is converted to the iron(III) derivative by treatment with oxygen and hydrochloric acid: | 0 | Theoretical and Fundamental Chemistry |
The second-order correlation function is of special importance, as it is directly related (via a Fourier transform) to the structure factor of the system and can thus be determined experimentally using X-ray diffraction or neutron diffraction.
If the system consists of spherically symmetric particles, depends only on the relative distance between them, . We will drop the sub- and superscript: . Taking particle 0 as fixed at the origin of the coordinates, is the average number of particles (among the remaining ) to be found in the volume around the position .
We can formally count these particles and take the average via the expression , with the ensemble average, yielding:
where the second equality requires the equivalence of particles . The formula above is useful for relating to the static structure factor , defined by , since we have:
and thus:
, proving the Fourier relation alluded to above.
This equation is only valid in the sense of distributions, since is not normalized: , so that diverges as the volume , leading to a Dirac peak at the origin for the structure factor. Since this contribution is inaccessible experimentally we can subtract it from the equation above and redefine the structure factor as a regular function:
Finally, we rename and, if the system is a liquid, we can invoke its isotropy: | 0 | Theoretical and Fundamental Chemistry |
An example problem is that of star formation. Stars form out of the interstellar medium, with this formation mostly occurring in giant molecular clouds such as the Rosette Nebula. An interstellar cloud can collapse due to its self-gravity if it is large enough; however, in the ordinary interstellar medium this can only happen if the cloud has a mass of several thousands of solar masses—much larger than that of any star. Stars may still form, however, from processes that occur if the magnetic pressure is much larger than the thermal pressure, which is the case in giant molecular clouds. These processes rely on the interaction of magnetohydrodynamic waves with a thermal instability. A magnetohydrodynamic wave in a medium in which the magnetic pressure is much larger than the thermal pressure can produce dense regions, but they cannot by themselves make the density high enough for self-gravity to act. However, the gas in star forming regions is heated by cosmic rays and is cooled by radiative processes. The net result is that a gas in a thermal equilibrium state in which heating balances cooling can exist in three different phases at the same pressure: a warm phase with a low density, an unstable phase with intermediate density and a cold phase at low temperature. An increase in pressure due to a supernova or a spiral density wave can shift the gas from the warm phase to the unstable phase, with a magnetohydrodynamic wave then being able to produce dense fragments in the cold phase whose self-gravity is strong enough for them to collapse into stars. | 1 | Applied and Interdisciplinary Chemistry |
With surface chemistries that are weakly ionic, the choice of pH can affect the ionic nature of the column chemistry. Properly adjusted, the pH can be set to reduce the selectivity toward functional groups with the same charge as the column, or enhance it for oppositely charged functional groups. Similarly, the choice of pH affects the polarity of the solutes. However, for column surface chemistries that are strongly ionic, and thus resistant to pH values in the mid-range of the pH scale (pH 3.5–8.5), these separations will be reflective of the polarity of the analytes alone, and thus might be easier to understand when doing methods development. | 1 | Applied and Interdisciplinary Chemistry |
In the first experiments with laser heating, temperature came from a calibration of laser power made with known melting points of various materials. When using the pulsed ruby laser this was unreliable due to the short pulse. YAG lasers quickly become the standard, heating for relatively long duration, and allowing observation of the sample throughout the heating process. It was with the first use of YAG lasers that Bassett used an optical pyrometer to measure temperatures in the range of 1000 °C to 1600 °C. The first temperature measurements had a standard deviation of 30 °C from the brightness temperature, but due to the small sample size was estimated to be 50 °C with the possibility that the true temperature of the sample being was 200 °C higher than that of the brightness measurement. Spectrometry of the incandescent light became the next method of temperature measurement used in Bassett's group. The energy of the emitted radiation could be compared to known black-body radiation spectra to derive a temperature. Calibration of these systems is done with published melting points or melting points as measured by resistive heating. | 0 | Theoretical and Fundamental Chemistry |
The typical SAF setup consists of a laser line (typically 450-633 nm), which is reflected into the aspheric lens by a dichroic mirror. The lens focuses the laser beam in the sample, causing the particles to fluoresce. The fluorescent light then passes through a parabolic lens before reaching a detector, typically a photomultiplier tube or avalanche photodiode detector. It is also possible to arrange SAF elements as arrays, and image the output onto a CCD, allowing the detection of multiple analytes. | 0 | Theoretical and Fundamental Chemistry |
In gravity and pressure driven fluid dynamical and geophysical mass flows such as ocean waves, avalanches, debris flows, mud flows, flash floods, etc., kinematic waves are important mathematical tools to understand the basic features of the associated wave phenomena.
These waves are also applied to model the motion of highway traffic flows.
In these flows, mass and momentum equations can be combined to yield a kinematic wave equation. Depending on the flow configurations, the kinematic wave can be linear or non-linear, which depends on whether the wave phase speed is a constant or a variable. Kinematic wave can be described by a simple partial differential equation with a single unknown field variable (e.g., the flow or wave height, ) in terms of the two independent variables, namely the time () and the space () with some parameters (coefficients) containing information about the physics and geometry of the flow. In general, the wave can be advecting and diffusing. However, in simple situations, the kinematic wave is mainly advecting. | 1 | Applied and Interdisciplinary Chemistry |
Phase transformation crystallography describes the orientation relationship and interface orientation after a phase transformation (such as martensitic transformation or precipitation). | 0 | Theoretical and Fundamental Chemistry |
Alclad is a corrosion-resistant aluminium sheet formed from high-purity aluminium surface layers metallurgically bonded (rolled onto) to high-strength aluminium alloy core material. It has a melting point of about . Alclad is a trademark of Alcoa but the term is also used generically.
Since the late 1920s, Alclad has been produced as an aviation-grade material, being first used by the sector in the construction of the ZMC-2 airship. The material has significantly more resistance to corrosion than most aluminium-based alloys, for only a modest increase in weight, making Alclad attractive for building various elements of aircraft, such as the fuselage, structural members, skin, and cowling. Accordingly, it became a relatively popular material for aircraft manufacturing. | 1 | Applied and Interdisciplinary Chemistry |
Smaller arc furnaces may be adequately cooled by circulation of air over structural elements of the shell and roof, but larger installations require intensive forced cooling to maintain the structure within safe operating limits. The furnace shell and roof may be cooled either by water circulated through pipes which form a panel, or by water sprayed on the panel elements. Tubular panels may be replaced when they become cracked or reach their thermal stress life cycle.
Spray cooling is the most economical and is the highest efficiency cooling method. A spray cooling piece of equipment can be relined almost endlessly. Equipment that lasts 20 years is the norm. While a tubular leak is immediately noticed in an operating furnace due to the pressure loss alarms on the panels, at this time there exists no immediate way of detecting a very small volume spray cooling leak. These typically hide behind slag coverage and can hydrate the refractory in the hearth, leading to a break out of molten metal or in the worst case a steam explosion. | 1 | Applied and Interdisciplinary Chemistry |
A clean MRF accepts recyclable materials that have already been separated at the source from municipal solid waste generated by either residential or commercial sources. There are a variety of clean MRFs. The most common are single stream where all recyclable material is mixed, or dual stream MRFs, where source-separated recyclables are delivered in a mixed container stream (typically glass, ferrous metal, aluminum and other non-ferrous metals, PET [No.1] and HDPE [No.2] plastics) and a mixed paper stream including corrugated cardboard boxes, newspapers, magazines, office paper and junk mail. Material is sorted to specifications, then baled, shredded, crushed, compacted, or otherwise prepared for shipment to market. | 1 | Applied and Interdisciplinary Chemistry |
Commercially available sea salts on the market today vary widely in their chemical composition. Although the principal component is sodium chloride, the remaining portion can range from less than 0.2 to 10% of other salts. These are mostly calcium, potassium, and magnesium salts of chloride and sulfate with substantially lesser amounts of many trace elements found in natural seawater. Though the composition of commercially available salt may vary, the ionic composition of natural saltwater is relatively constant. | 0 | Theoretical and Fundamental Chemistry |
In normal operation, a rolling-element bearing has the rollers and races separated by a thin layer of lubricant such as grease or oil. Although these lubricants normally appear liquid (not solid), under high pressure they act as solids and keep the bearing and race from touching.
If the lubricant is removed, the bearings and races can touch directly. While bearings and races appear smooth to the eye, they are microscopically rough. Thus, high points of each surface can touch, but "valleys" do not. The bearing load is thus spread over much less area increasing the contact stress, causing pieces of each surface to break off or to become pressure-welded then break off when the bearing rolls on.
The broken-off pieces are also called wear debris. Wear debris is bad because it is relatively large compared to the surrounding surface finish and thus creates more regions of high contact stress. Worse, the steel in ordinary bearings can oxidize (rust), producing a more abrasive compound which accelerates wear. | 1 | Applied and Interdisciplinary Chemistry |
The general outline for the organic synthesis of a CBS catalyst is shown below. The first leg of the reaction sequence starts from the azeotropic dehydration of a boronic acid (1) such as one based on toluene to a boroxine (2). This boroxine reacts with the proline derivative (3d) to form the basic oxazaborolidine CBS catalyst (4). The oxazaborolidine was first developed as a ketone reducing agent by the laboratory of Itsuno, and thus is more properly called the Itsuno-Corey oxazaborolidine. Proline derivative 3d is prepared in a separate leg from a Grignard reaction with Grignard reagent 3c and proline ester 3b. A Lewis acid superacid salt (6) can be obtained with the aid of triflic acid (5). Many other such catalysts exist with different derivatives of these reactants. | 0 | Theoretical and Fundamental Chemistry |
The Cromer cycle is a thermodynamic cycle that uses a desiccant to interact with higher relative humidity air leaving a cold surface. When a system is taken through a series of different states and finally returned to its initial state, a thermodynamic cycle is said to have occurred. The desiccant absorbs moisture from the air leaving the cold surface, releasing heat and drying the air, which can be used in a process requiring dry air. The desiccant is then dried by an air stream at a lower relative humidity, where the desiccant gives up its moisture by evaporation, increasing the air's relative humidity and cooling it. This cooler, moister air can then be presented to the same cold surface as above to take it below its dew point and dry it further, or it can be expunged from the system.
The desiccant undergoes a reversible process whereby in the first part of the cycle, it absorbs or adsorbs moisture from air leaving a cold surface, releasing heat, and then in the second part of the cycle evaporates moisture, absorbing heat and returning the desiccant to its original state to complete the cycle again. The result of the Cromer cycle is that the process air leaving the cycle is dehumidified further (higher latent ratio) than it would be leaving the cold surface without the cycle. The Cromer cycle concept was originally patented in the mid-1980s. Those patents have expired and thus the cycle is free for anyone to use. The cycle was first publicized in 1997 by Popular Mechanics' in its Tech Update section. | 0 | Theoretical and Fundamental Chemistry |
Depending on the size of the alloying element, a substitutional solid solution or an interstitial solid solution can form. In both cases, atoms are visualised as rigid spheres where the overall crystal structure is essentially unchanged. The rationale of crystal geometry to atom solubility prediction is summarized in the Hume-Rothery rules and Pauling's rules.
Substitutional solid solution strengthening occurs when the solute atom is large enough that it can replace solvent atoms in their lattice positions. Some alloying elements are only soluble in small amounts, whereas some solvent and solute pairs form a solution over the whole range of binary compositions. Generally, higher solubility is seen when solvent and solute atoms are similar in atomic size (15% according to the Hume-Rothery rules) and adopt the same crystal structure in their pure form. Examples of completely miscible binary systems are Cu-Ni and the Ag-Au face-centered cubic (FCC) binary systems, and the Mo-W body-centered cubic (BCC) binary system.
Interstitial solid solutions form when the solute atom is small enough (radii up to 57% the radii of the parent atoms) to fit at interstitial sites between the solvent atoms. The atoms crowd into the interstitial sites, causing the bonds of the solvent atoms to compress and thus deform (this rationale can be explained with Pauling's rules). Elements commonly used to form interstitial solid solutions include H, Li, Na, N, C, and O. Carbon in iron (steel) is one example of interstitial solid solution. | 1 | Applied and Interdisciplinary Chemistry |
Plutonium silicide is a binary inorganic compound of plutonium and silicon with the chemical formula PuSi. The compound forms gray crystals. | 0 | Theoretical and Fundamental Chemistry |
The software system is modular. The functionalities of the COMOS platform support the digital transformation of a plant via the object-oriented database and a special layer technology that permits joint and consistent work on data and documents. Object properties or attributes can be changed in data sheets and various entry masks. Batch queries and changes are also possible.<br />
The system is used to design process engineering. Integration into standard process simulators results in the definition of process data at an early planning stage using process flow diagrams and combination with the engineering of processing plants. Another module is used to make this data more precise. The pipework engineering based on piping and instrumentation diagrams followed specified industry standards for the respective pipe classes. Data is exchanged in the further geometrical planning using isometries based on ISO 15926. At the end one gets the virtual 3D design of the plant.
The system serves for the electrical engineering of plants all the way to their complete automation: it covers electrical, measurement, control, and regulation (EMSR) processes. Functional plans and sequences can be generated based on common standards. Sequence controls can also be represented graphically. This information can be exchanged directly with distributed control system (DCS) process control systems such as Simatic PCS 7.
It supports plant operation after start-up. Engineering data can be used and expanded in the operating phase. Repairs or maintenance work can be reported directly from the field to the central system using mobile maintenance processes. It permits traceable document and data management. It meets the strict requirements of the FDA. Secure access possibilities permit work with distributed information all over the world. It also makes it possible to train plant personnel with visualization and simulation in 3D VR models combined with corresponding training scenarios. Walkinside was developed by the 3D specialist VRcontext and was integrated into the software after the takeover of the company by Siemens in 2011. | 1 | Applied and Interdisciplinary Chemistry |
Chondroitinase treatment is a treatment of proteoglycans, a protein in the fluid among cells where (among other things) they affect neural activity (communication, plasticity). Chondroitinase treatment has been shown to allow adults vision to be restored as far as ocular dominance is concerned. Moreover, there is some evidence that Chondroitinase could be used for the treatment of spinal injuries.
In addition, the enzyme that is used in the chondroitinase treatment, chondroitinase ABC, derives from the bacterium Proteus vulgaris. In recent years, pre-clinical research involving the chondroitinase ABC enzyme has been mainly directed towards utilizing it as a way of treating spinal cord injuries in test animals using viral vectors. In general, the way chondroitinase ABC works in vivo is it cleaves off the side chains of molecules known as chondroitin sulfate proteoglycans (CSPGs) which are over produced by glial cells in the central nervous system when a spinal injury occurs. When chondroitin sulfate proteoglycans are bonded to their side chains called chondroitin sulfate glycosaminoglycans, these molecules are known to prevent neural restoration to the damaged region of the central nervous system because they form glial scar tissue which inhibits both neuroplasticity and repair of damaged axons. However, when the side chains of the chondroitin sulfate proteoglycans are cleaved by chondroitinase ABC, this promotes the damaged region of the CNS to recover from the spinal cord injury.
It has recently been proposed that chondroitinase treatment promotes plasticity by activation of Tropomyosin receptor kinase B, receptor for Brain-derived neurotrophic factor and a major plasticity orchestrator in the brain. Cleavage of CSPGs by chondroitinase ABC leads to inactivation of PTPRS, the membrane receptor for CSPGs and a phosphatase that inactivates TRKB under normal physiological conditions, which subsequently promotes TRKB phosphorylation and activation of neuroplasticity. | 1 | Applied and Interdisciplinary Chemistry |
Glycolipids are lipids with a carbohydrate attached by a glycosidic (covalent) bond. Their role is to maintain the stability of the cell membrane and to facilitate cellular recognition, which is crucial to the immune response and in the connections that allow cells to connect to one another to form tissues. Glycolipids are found on the surface of all eukaryotic cell membranes, where they extend from the phospholipid bilayer into the extracellular environment. | 0 | Theoretical and Fundamental Chemistry |
Geochemical Perspectives Letters is a peer-reviewed open access scholarly journal publishing original research in geochemistry. It is published by the European Association for Geochemistry. | 0 | Theoretical and Fundamental Chemistry |
In the beginning of the 1970s, gradual technological improvements over the previous decade resulted in the second generation of Type I tapes. These tapes had uniformly needle-shaped, highly orientable particles (HOP) of much smaller size, around in length, hence the trade term microferrics. Their uniform shape allowed very dense packing of particles, with less binder and more particles per unit volume, and a corresponding rise in remanence to around . The first microferric (TDK SD) was introduced in 1971, and in 1973 Pfizer began marketing patented microferric powder that soon became an industry standard. In the 20th century, Pfizer had a strong mineral pigment division, with factories in California, Illinois and Indiana. In 1990 Pfizer sold its iron-oxide business to Harrisons & Crosfield of the United Kingdom. The next step was to align needle-shaped particles in parallel with the flux lines generated by the recording head; this was done by controlled flow of liquid magnetic mix over substrate (rheological orientation), or by applying a strong magnetic field while the binder was curing.
Typical microferric cassettes of the 1980s had less hiss and at least higher MOL than basic Type I tapes, at the cost of increased print-through. Noise and print-through are interrelated, and directly depend on the size of oxide particles. A decrease in particle size invariably decreases noise and increases print-through. The worst combination of noise and print-through occurs in highly irregular formulations containing both unusually large and unusually small particles. Small improvements continued for thirty years, with a gradual rise of squareness ratio from 0.75 to over 0.9. Newer tapes consistently produced higher output with less distortion at the same levels of bias and audio recording signals. The transition was smooth; after the introduction of new, superior tape formulations, manufacturers often kept older ones in production, selling them in different markets or under different, cheaper, designations. Thus, for example, TDK ensured that its premium microferric AD cassette was always ahead of entry-level microferric D, having finer particles and lower noise. | 0 | Theoretical and Fundamental Chemistry |
An intein is a "parasitic" segment of a protein that is able to excise itself from the chain of amino acids as they emerge from the ribosome and rejoin the remaining portions with a peptide bond in such a manner that the main protein "backbone" does not fall apart. This is a case of a protein changing its own primary sequence from the sequence originally encoded by the DNA of a gene. Additionally, most inteins contain a homing endonuclease or HEG domain which is capable of finding a copy of the parent gene that does not include the intein nucleotide sequence. On contact with the intein-free copy, the HEG domain initiates the DNA double-stranded break repair mechanism. This process causes the intein sequence to be copied from the original source gene to the intein-free gene. This is an example of protein directly editing DNA sequence, as well as increasing the sequence's heritable propagation. | 1 | Applied and Interdisciplinary Chemistry |
9-Fluorenylidene is an aryl carbene derived from the bridging methylene group of fluorene. Fluorenylidene has the unusual property that the triplet ground state is only 1.1 kcal/mol (4.6 kJ/mol) lower in energy than the singlet state. For this reason, fluorenylidene has been studied extensively in organic chemistry.
Fluorenylidene is a reactive intermediate. Reactions involving fluorenylidene proceed through either the triplet or singlet state carbene, and the products formed depend on the relative concentration of spin states in solution, as influenced by experimental conditions. The rate of intersystem crossing is determined by the temperature and concentration of specific spin-trapping agents. | 0 | Theoretical and Fundamental Chemistry |
The bioinformatics core contributes bioinformatic analysis by collecting and curating complete sequence data sets, generating sequence similarity networks, and classification of superfamily members into subgroups and families for subsequent annotation transfer and evaluation as targets for functional characterization.
The protein core develops cloning, expression, and protein purification strategies for the enzymes targeted for study.
The structure core fulfills the structural biology component for EFI by providing high resolution structures of targeted enzymes.
The computation core performs in silico docking to generate rank-ordered lists of predicted substrates for targeted enzymes using both experimentally determined and/or homology modeled protein structures.
The microbiology core examines in vivo functions using genetic techniques and metabolomics to complement in vitro functions determined by the Bridging Projects.
The data and dissemination core maintains a public database for experimental data (EFI-DB). | 1 | Applied and Interdisciplinary Chemistry |
The Earth’s gravitational field acts upon colloidal particles. Therefore, if the colloidal particles are denser than the medium of suspension, they will sediment (fall to the bottom), or if they are less dense, they will cream (float to the top). Larger particles also have a greater tendency to sediment because they have smaller Brownian motion to counteract this movement.
The sedimentation or creaming velocity is found by equating the Stokes drag force with the gravitational force:
where
: is the Archimedean weight of the colloidal particles,
: is the viscosity of the suspension medium,
: is the radius of the colloidal particle,
and is the sedimentation or creaming velocity.
The mass of the colloidal particle is found using:
where
: is the volume of the colloidal particle, calculated using the volume of a sphere ,
and is the difference in mass density between the colloidal particle and the suspension medium.
By rearranging, the sedimentation or creaming velocity is:
There is an upper size-limit for the diameter of colloidal particles because particles larger than 1 μm tend to sediment, and thus the substance would no longer be considered a colloidal suspension.
The colloidal particles are said to be in sedimentation equilibrium if the rate of sedimentation is equal to the rate of movement from Brownian motion. | 0 | Theoretical and Fundamental Chemistry |
Clinopyroxene thermobarometry is a scientific method that uses the mineral clinopyroxene to determine the temperature and pressure of the magma when the mineral crystalized. Clinopyroxene is found in many igneous rocks, so the method can be used to determine information about the entire rock. Many different minerals can be used for geothermobarometry, but clinopyroxene is especially useful because it's a common phenocryst in igneous rocks and easy to identify, and the crystallization of jadeite, a type of clinopyroxene, implies a growth in molar volume, making it a good indicator of pressure.
The data given by this technique is used for understanding magmatic crystallization, prograde and retrograde metamorphism, and ore deposit formation. Understanding these processes can aid industries as well as the scientific community. With this data, information about the lithosphere composition can be extrapolated in more detail, and the diamond exploration industry can determine the probability that a kimberlite contains diamonds. | 0 | Theoretical and Fundamental Chemistry |
Precession electron diffraction is accomplished utilizing the standard instrument configuration of a modern TEM. The animation illustrates the geometry used to generate a PED pattern. Specifically, the beam tilt coils located pre-specimen are used to tilt the electron beam off of the optic axis so it is incident with the specimen at an angle, φ. The image shift coils post-specimen are then used to tilt the diffracted beams back in a complementary manner such that the direct beam falls in the center of the diffraction pattern. Finally, the beam is precessed around the optic axis while the diffraction pattern is collected over multiple revolutions.
The result of this process is a diffraction pattern that consists of a summation or integration over the patterns generated during precession. While the geometry of this pattern matches the pattern associated with a normally incident beam, the intensities of the various reflections approximate those of the kinematical pattern much more closely. At any moment in time during precession, the diffraction pattern consists of a Laue circle with a radius equal to the precession angle, φ. It is crucial to note that these snapshots contain far fewer strongly excited reflections than a normal zone axis pattern and extend farther into reciprocal space. Thus, the composite pattern will display far less dynamical character, and will be well suited for use as input into direct methods calculations. | 0 | Theoretical and Fundamental Chemistry |
Sir Ronald Sydney Nyholm (29 January 1917 – 4 December 1971) was an Australian chemist who was a leading figure in inorganic chemistry in the 1950s and 1960s. | 0 | Theoretical and Fundamental Chemistry |
RuBP was originally discovered by Andrew Benson in 1951 while working in the lab of Melvin Calvin at UC Berkeley. Calvin, who had been away from the lab at the time of discovery and was not listed as a co-author, controversially removed the full molecule name from the title of the initial paper, identifying it solely as "ribulose". At the time, the molecule was known as ribulose diphosphate (RDP or RuDP) but the prefix di- was changed to bis- to emphasize the nonadjacency of the two phosphate groups. | 0 | Theoretical and Fundamental Chemistry |
It is possible to work out the equilibrium constant for a chemical reaction involving a mixture of gases given the partial pressure of each gas and the overall reaction formula. For a reversible reaction involving gas reactants and gas products, such as:
the equilibrium constant of the reaction would be:
For reversible reactions, changes in the total pressure, temperature or reactant concentrations will shift the equilibrium so as to favor either the right or left side of the reaction in accordance with Le Chatelier's Principle. However, the reaction kinetics may either oppose or enhance the equilibrium shift. In some cases, the reaction kinetics may be the overriding factor to consider. | 0 | Theoretical and Fundamental Chemistry |
Every surface though appears smooth at macro scale has roughness in micro scales which can be measured by a profilometer. The wetting liquid between contacting rough surfaces develops a sub-ambient pressure inside itself, which forces the surfaces toward more intimate contact. Since the pressure drop across the liquid is proportional to the curvature at the free surface and this curvature, in turn, is approximately inversely proportional to the local spacing, the thinner the liquid bridge, the greater is the pull effect.
where:
* are the liquid-solid contact angles for the lower and upper surfaces, respectively,
* is the gap between the two solids at the location of the free surface of the liquid.
These tensile stresses put the two surfaces into more contact while the compressive stresses due to the elastic deformation of the surfaces tend to resist them.
Two scenarios could happen in this case: 1. The tensile and compressive stresses come into balance which in this case the gap between the two surfaces is in the order of Surface roughness|roughness of the surfaces, or, 2. The tensile stresses overcome the compressive stresses and the two surfaces come into near complete contact in which gap between surfaces is a small fraction of the Surface roughness|surface roughness. The latter case is the reason for failure of most microscale devices. An estimate of the tensile stresses exerted by the capillary film can be obtained by dividing the adhesion force, , between two surfaces to the area wetted by the liquid film, . Because for relative smooth surfaces, the magnitude of the capillary pressure is predicted to be large, it is anticipated that the capillary pressures will be of large magnitude. A lot of works have been done to ascertain whether there may be some practical limit to the development of such negative pressures (e.g. ). | 1 | Applied and Interdisciplinary Chemistry |
Organoberyllium chemistry involves the synthesis and properties of organometallic compounds featuring the group 2 alkaline earth metal beryllium (Be). The area remains understudied, relative to the chemistry of other main-group elements, because although metallic beryllium is relatively unreactive, its dust causes berylliosis and compounds are toxic. Organoberyllium compounds are typically prepared by transmetallation or alkylation of beryllium chloride.
The beryllium functional group in organoberyllium compounds usually serves to coordinate other elements and ligands. Beryllium, one of the smallest atoms on the periodic table, almost always exhibits a +2 oxidation state. The cation is characterized by the highest known charge density (Z/r = 6.45), making it one of the hardest cations and a very strong Lewis acid.
Coordination in beryllium can range from a coordination number of two to four. Most common ligands attached to beryllium are halides, hydride (like beryllium borohydride in a three-center two-electron bond), methyl, aryl, and alkyl. Beryllium can form complexes with known organic compounds such as phosphines, N-hetereocyclic carbenes (NHC), cyclic alkyl amino carbenes (CAAC), and β-diketiminates (NacNac). | 0 | Theoretical and Fundamental Chemistry |
Mar Menor (, "minor/smaller sea") is a coastal saltwater lagoon in the Iberian Peninsula located south-east of the Autonomous Community of Murcia, Spain, near Cartagena.
Its name is the opposite of the Mediterranean, which is the (greater/larger sea) of the region.
Four municipalities border the Mar Menor: Cartagena, Los Alcázares, San Javier and San Pedro del Pinatar.
With a surface area of 135 km, a coastal length of 70 km, and warm and clear water no more than 7 metres in depth, it is the largest lagoon in Spain.
The lagoon is separated from the Mediterranean Sea by La Manga ("the sleeve"), a sandbar 22 km in length whose width ranges from 100 to 1,200 metres, with Cape Palos in its south-eastern vertex making for the lagoon's roughly triangular shape. There are five islets located within the lagoon: Perdiguera islet, Mayor or El Barón islet, Ciervo islet, Redonda islet and del Sujeto islet.
Its relatively high salinity (which aids flotation), low waves, and remarkable sporting infrastructures makes it a popular place for a wide variety of water sports. | 1 | Applied and Interdisciplinary Chemistry |
Two basic mechanisms are responsible for fluid mixing: diffusion and advection. In liquids, molecular diffusion alone is hardly efficient for mixing. Advection, that is the transport of matter by a flow, is required for better mixing.
The fluid flow obeys fundamental equations of fluid dynamics (such as the conservation of mass and the conservation of momentum) called Navier–Stokes equations. These equations are written for the Eulerian velocity field rather than for the Lagrangian position of fluid particles. Lagrangian trajectories are then obtained by integrating the flow. Studying the effect of advection on fluid mixing amounts to describing how different Lagrangian fluid particles explore the fluid domain and separate from each other. | 1 | Applied and Interdisciplinary Chemistry |
Following Swendsen, we allow two systems to exchange particles. This essentially makes room in phase space for particles to enter or leave without requiring a change in the number of dimensions of phase space. The total number of particles is :
* particles have coordinates .
*: The total energy of these particles is
* particles have coordinates .
*: The total energy of these particles is
* The system is subject to the constraints, and
Taking the integral over phase space, we have:
The question marks (?) serve as a reminder that we may not assume that the first n particles (i.e. 1 through n) are in system A while the other particles (n through N) are in system B. (This is further discussed in the next section.)
Taking the logarithm and keeping only the largest terms, we have:
This can be interpreted as the sum of the entropy of system A and system B, both extensive. And there is a term, , that is not extensive. | 0 | Theoretical and Fundamental Chemistry |
Arsenic is highly detrimental to the innate and the adaptive immune system of the body. When the amount of unfolded and misfolded proteins in endoplasmic reticulum stress is excessive, the unfolded protein response (UPR) is activated to increase the activity of several receptors that are responsible the restoration of homeostasis. The inositol-requiring enzyme-1 (IRE1) and protein kinase RNA-like endoplasmic reticulum kinase (PERK) are two receptors that restrict the rate of translation. On the other hand, the unfolded proteins are corrected by the production of chaperones, which are induced by the activating transcription factor 6 (ATF6). If the number of erroneous proteins elevates, further mechanism is active which triggers apoptosis. Arsenic has evidentially shown to increase the activity of these protein sensors. | 1 | Applied and Interdisciplinary Chemistry |
One group of ferredoxins, originally found in chloroplast membranes, has been termed "chloroplast-type" or "plant-type" (). Its active center is a [FeS] cluster, where the iron atoms are tetrahedrally coordinated both by inorganic sulfur atoms and by sulfurs of four conserved cysteine (Cys) residues.
In chloroplasts, FeS ferredoxins function as electron carriers in the photosynthetic electron transport chain and as electron donors to various cellular proteins, such as glutamate synthase, nitrite reductase, sulfite reductase, and the cyclase of chlorophyll biosynthesis. Since the cyclase is a ferredoxin dependent enzyme this may provide a mechanism for coordination between photosynthesis and the chloroplasts need for chlorophyll by linking chlorophyll biosynthesis to the photosynthetic electron transport chain. In hydroxylating bacterial dioxygenase systems, they serve as intermediate electron-transfer carriers between reductase flavoproteins and oxygenase. | 0 | Theoretical and Fundamental Chemistry |
Pit water, mine water or mining water is water that collects in a mine and which has to be brought to the surface by water management methods in order to enable the mine to continue working. | 0 | Theoretical and Fundamental Chemistry |
The modern discipline of aeroacoustics can be said to have originated with the first publication of Lighthill in the early 1950s, when noise generation associated with the jet engine was beginning to be placed under scientific scrutiny. | 1 | Applied and Interdisciplinary Chemistry |
Multistep tandem reactions (or cascade reactions) are a sequence of chemical transformations (usually more than two steps) that happens consecutively to convert a starting material to a complex product. This kind of organic reactions are designed to construct difficult structures encountered in natural product total synthesis.
In the total synthesis of spiroketal ionophore antibiotic routiennocin 1 (Fig. 1), the central spiroketal skeleton was constructed by a multistep tandem reaction (Fig. 2). Fragment A and fragment B were coupled in a single step to form the key intermediate G that could be further elaborated to afford the final product routiennocin.
Four chemical transformations happened in this tandem reaction. First, treating fragment A with n-butyllithium formed carbon anion that attacked the alkyliodide part of fragment B to generate intermediate C (step 1). Then a 3, 4-dihydropyran derivative D was formed through base-mediated elimination reaction on intermediate C (step 2). The protecting group on 1, 3-diol moiety in intermediate D was removed by acid treatment to give the diol product E (step 3). The spiroketal product G was generated via intramolecular ketal formation reaction. This multistep tandem reaction greatly simplified the construction of this complex spiroketal structure and eased the path towards the total synthesis of routiennocin. | 0 | Theoretical and Fundamental Chemistry |
An air quality control region is an area, designated by the federal government, where communities share a common air pollution problem. | 1 | Applied and Interdisciplinary Chemistry |
UMRC states at its website that its vision for the world, "is a full awareness of the risks of using nuclear products and by-products AND to contain the still reversible alterations of the earth's biosphere since the advent of nuclear events and the resulting contamination".
They go on to state further that: "There needs to be an appreciation of the enormous effects and damage of uranium on the environment and human health. Governments, scientific communities, and the general public need to understand the many forms of contamination and specific effects. Continued abuses of uranium and radioisotopes will only lead to the steady degradation and eventual end of meaningful life on earth." www.UMRC.net | 0 | Theoretical and Fundamental Chemistry |
Müller was born in 1740 or 1742 in the Habsburg Empire. While the Allgemeine Deutsche Biographie gives 1 July 1740 and Vienna as date and place of birth, the Neue Deutsche Biographie prefers 4 October 1742 and the small town of Poysdorf in Lower Austria. The much older works Neuer Nekrolog der Deutschen and Oesterreichische National-Encyklopädie do not give a place of birth and only the year 1740 for his birth. Even articles by Mary Elvira Weeks on the discovery of tellurium, published in the Journal of Chemical Education in 1932, and 1935 quote two different locations of his birth: one in Vienna, Archduchy of Austria and the other Hermannstadt, Principality of Transylvania (present-day Sibiu, Romania). A newer biography on the topic makes clear that date and place of birth are not definitely known. | 1 | Applied and Interdisciplinary Chemistry |
The adsorption of gases and solutes is usually described through isotherms, that is, the amount of adsorbate on the adsorbent as a function of its pressure (if gas) or concentration (for liquid phase solutes) at constant temperature. The quantity adsorbed is nearly always normalized by the mass of the adsorbent to allow comparison of different materials. To date, 15 different isotherm models have been developed. | 0 | Theoretical and Fundamental Chemistry |
The safety of cosmetic products is constantly in question as the components are always changing or being discovered as a possibly harmful substance. The sulfite components of cosmetic ingredients, such as sodium bisulfite, underwent clinical trials to find out their safety in cosmetic formulations. Sodium bisulfite functions as a reducing agent and furthermore as a hair-waiving/straightening agent. As of 1998, sodium bisulfite was used in 58 different cosmetic products including hair conditioners, moisturizers, and hair dyes.
In a cosmetic context, the reducing ability of sodium bisulfite is used to prevent discoloration, bleach food starches, and delay spoilage of the product. Since the sulfite molecule was used in so many compounds in the 1990s, the EPA, FDA, and American Conference of Governmental Industrial Hygienists established a working place threshold limit value for sulfur dioxide of 2ppm averaged over 8 hours, and a 3-hour level of 5ppm. Even with this threshold established, the FDA recognized sodium bisulfite as a "generally recognized as safe" compound.
A final examination on the carcinogenicity, genotoxicity, oral toxicity, and cellular toxicity on consumed sodium bisulfite was conducted using living subjects such as mice and rats. The International Agency for Research on Cancer concluded that there was inadequate evidence that sodium bisulfite was carcinogenic. Under specific conditions such as acidity and concentration level, sodium bisulfite was able to cause negative alterations to the genome such as catalyzing transamination, and induce sister-chromatid exchanges suggesting possible genotoxicity. In a study using Osbourne-Mendel strain rats, it was concluded that oral toxicity was not significant if the consumed concentration was less than 0.1% (615ppm as SO2). A study done by Servalli, Lear, and Cottree in 1984 found that sodium bisulfite did not produce membrane fusion in hepatic and murine glial cells and human fibroblasts so there is no oral toxicity. These clinical studies concluded that sodium bisulfite was safe to use in cosmetic formulations. | 0 | Theoretical and Fundamental Chemistry |
Pregnanediol, or 5β-pregnane-3α,20α-diol, is an inactive metabolic product of progesterone. A test can be done to measure the amount of pregnanediol in urine, which offers an indirect way to measure progesterone levels in the body.
From the urine of pregnant women from London clinics, Guy Frederic Marrian isolated a substance that contained two hydroxyl groups and could be converted into a diacetate with acetic anhydride. However, the formula had not been clearly clarified. Almost at the same time, Adolf Butenandt at the Chemical University Laboratory in Göttingen investigated the constituents of pregnant urine and clarified the structure of the diol. The name pregnandiol, coined by Butenandt, is derived from the Latin verb praegnans (pregnant) or the English pregnant and pregnancy. This gave rise to the name pregnane for the underlying parent hydrocarbon.
In 1936, Venning and Browne demonstrated the presence of pregnanediol, specifically the glucuronide of pregnanediol in pregnancy urine. Their study extracted pregnanediol from pregnancy urine and revealed that pregnanediol concentration in urine indicates the amount of progesterone excreted. Since progesterone levels indicate the functionality of a corpus luteum, and pregnanediol concentration represents 40-45% of the progesterone excreted, estimations of pregnanediol reveal the functionality of a corpus luteum. However, pregnanediol concentrations vary with menstrual cycle phases, so it is essential to consider the menstrual cycle phase when examining them. Furthermore, current research has demonstrated that pregnanediol concentration in urine is also a measure of ovarian activity. | 1 | Applied and Interdisciplinary Chemistry |
Cryosurgery is a minimally invasive procedure, and is often preferred to other types of surgery because of its safety, ease of use, minimal pain and scarring as well as low cost; however, as with any medical treatment, there are risks involved, primarily that of damage to nearby healthy tissue. Damage to nerve tissue is of particular concern but is rare.
Cryosurgery cannot be used on lesions that would subsequently require biopsy as the technique destroys tissue and precludes the use of histopathology.
More common complications of cryosurgery include blistering and edema which are transient. Cryosurgery may cause complications due to damage of underlying structures. Destruction of the basement membrane may cause scarring and destruction of hair follicles can cause alopecia or hair loss. Occasionally, hypopigmentation may occur in the area of skin treated with cryosurgery, however, this complication is usually transient and often resolves as melanocytes migrate and repigment the area over several months. Bleeding can also occur, which can be delayed or immediate, due to damage of underlying arteries and arterioles. Tendon rupture and cartillage necrosis can occur, particularly if cryosurgery is done over bony prominences. These complications can be avoided or minimized if freeze times of less than 30 seconds are used during cryosurgery.
Patients undergoing cryosurgery usually experience redness and minor-to-moderate localized pain, which most of the time can be alleviated sufficiently by oral administration of mild analgesics such as ibuprofen, codeine or acetaminophen (paracetamol). Blisters may form as a result of cryosurgery, but these usually scab over and peel away within a few days. | 1 | Applied and Interdisciplinary Chemistry |
In 2022, Malaysia was the third-largest PV module producer, with a production capacity of 10.8 GW, accounting for 2.8% of global production. This placed it behind China, which dominated with 77.8%, and Vietnam, which contributed 6.4%. | 0 | Theoretical and Fundamental Chemistry |
Consider a gas flow with a uniform velocity field and having a pressure , density , entropy and sound speed . Now we add small perturbations to these variables, which are denoted with a symbol . The perturbed variables being small quatities satisfy linearized form of the Euler equations, which is given by
where in the continuity equation, we have used the relation (since and ) and the used the entropy equation to simplify it. Taking perturbations to be of the plane-wave form , the linearised equations can be reduced to algebraic equations
The last equation shows that either , which corresponds to sound waves in which entropy does not change or . The later condition indicating that perturbations are carried by the gas corresponds to the entropy-vortex wave. In this case, we have
where is the vorticity perturbation. As we can see, the entropy perturbation and the vorticity perturbation are independent meaning that one can have entropy waves without vorticity waves or vorticity waves with entropy waves or both entropy and vorticity waves.
In non-reacting mutlicomponent gas, we can also have compositional perturbations since in this case, , where is the mass fraction of ith specices of total chemical species. In the entropy-vorticity wave, we have then | 1 | Applied and Interdisciplinary Chemistry |
Maintaining an electric field in an electrolyte requires Faradaic reactions to occur at the anode and cathode. This is typically electrolysis of water, which generates hydrogen peroxide, hydrogen ions (acid) and hydroxide (base) as well as oxygen and hydrogen gas bubbles. The hydrogen peroxide and/or pH changes generated can adversely affect biological cells and biomolecules such as proteins, while gas bubbles tend to "clog" microfluidic systems. These problems can be alleviated by using alternative electrode materials such as conjugated polymers which can undergo the Faradaic reactions themselves, dramatically reducing electrolysis. | 0 | Theoretical and Fundamental Chemistry |
Some examples of exothermic processes are:
* Combustion of fuels such as wood, coal and oil/petroleum
* The thermite reaction
* The reaction of alkali metals and other highly electropositive metals with water
* Condensation of rain from water vapor
* Mixing water and strong acids or strong bases
* The reaction of acids and bases
* Dehydration of carbohydrates by sulfuric acid
* The setting of cement and concrete
* Some polymerization reactions such as the setting of epoxy resin
* The reaction of most metals with halogens or oxygen
* Nuclear fusion in hydrogen bombs and in stellar cores (to iron)
* Nuclear fission of heavy elements
* The reaction between zinc and hydrochloric acid
* Respiration (breaking down of glucose to release energy in cells) | 0 | Theoretical and Fundamental Chemistry |
Georgy Vasilyevich Pigulevsky (; – 19 September 1964) was a soviet organic chemist, specializing in natural product chemistry. He studied essential oils and resins of plants, as well as terpene compounds extracted from them. | 0 | Theoretical and Fundamental Chemistry |
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