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Hydrazones are susceptible to hydrolysis:
Alkyl hydrazones are 10- to 10-fold more sensitive to hydrolysis than analogous oximes.
When derived from hydrazine itself, hydrazones condense with a second equivalent of a carbonyl to give azines:
Hydrazones are intermediates in the Wolff–Kishner reduction.
Hydrazones are reactants in hydrazone iodination, the Shapiro reaction, and the Bamford-Stevens reaction to vinyl compounds. Hydrazones can also be synthesized by the Japp–Klingemann reaction via β-keto acids or β-keto-esters and aryl diazonium salts. Hydrazones are converted to azines when used in the preparation of 3,5-disubstituted 1H-pyrazoles, a reaction also well known using hydrazine hydrate. With a transition metal catalyst, hydrazones can serve as organometallic reagent surrogates to react with various electrophiles. | 0 | Theoretical and Fundamental Chemistry |
Green infrastructure is often cheaper than more conventional water management strategies. Philadelphia found that its new green infrastructure plan will cost $1.2 billion over 25 years, compared with the $6 billion a gray infrastructure would have cost. The expenses for implementing green infrastructure are often smaller, planting a rain garden to deal with drainage costs less than digging tunnels and installing pipes. But even when it is not cheaper, green infrastructure still has a good long-term effect. A green roof lasts twice as long as a regular roof, and low maintenance costs of permeable pavement can make for a good long-term investment. The Iowa town of West Union determined it could save $2.5 million over the lifespan of a single parking lot by using permeable pavement instead of traditional asphalt. Green infrastructure also improves the quality of water drawn from rivers and lakes for drinking, which reduces the costs associated with purification and treatment, in some cases by more than 25 percent. And green roofs can reduce heating and cooling costs, leading to energy savings of as much as 15 percent. | 1 | Applied and Interdisciplinary Chemistry |
Agricultural chemistry often aims at preserving or increasing the fertility of soil with the goals of maintaining or improving the agricultural yield and improving the quality of the crop. Soils are analyzed with attention to the inorganic matter (minerals), which comprise most of the mass of dry soil, and organic matter, which consists of living organisms, their degradation products, humic acids and fulvic acids.
Fertilizers are a major consideration. While organic fertilizers are time-honored, their use has largely been displaced by chemicals produced from mining (phosphate rock) and the Haber-Bosch process. The use of these materials dramatically increased the rate at which crops are produced, which is able to support the growing human population. Common fertilizers include urea, ammonium sulphate, diammonium phosphate, and calcium ammonium phosphate. | 1 | Applied and Interdisciplinary Chemistry |
The inducer in the lac operon is allolactose. If lactose is present in the medium, then a small amount of it will be converted to allolactose by a few molecules of β-galactosidase that are present in the cell. Allolactose binds to the repressor and decreases the repressor's affinity for the operator site.
However, when lactose and glucose are both available in the system, the lac operon is repressed. This is because glucose actively prevents the induction of lacZYA. | 0 | Theoretical and Fundamental Chemistry |
The surge of depolarization traveling from the axon hillock to the axon terminal is known as an action potential. Action potentials reach the axon terminal, where the action potential triggers the release of neurotransmitters from the neuron. The neurotransmitters that are released from the axon continue on to stimulate other cells such as other neurons or muscle cells. After an action potential travels down the axon of a neuron, the resting membrane potential of the axon must be restored before another action potential can travel the axon. This is known as the recovery period of the neuron, during which the neuron cannot transmit another action potential. | 0 | Theoretical and Fundamental Chemistry |
An oxyhydrogen torch (also known as hydrogen torch) is an oxy-gas torch that burns hydrogen (the fuel) with oxygen (the oxidizer). It is used for cutting and welding metals, glasses, and thermoplastics.
Due to competition from arc welding and other oxy-fuel torches such as the acetylene-fueled cutting torch, the oxyhydrogen torch is seldom used today, but it remains the preferred cutting tool in some niche applications.
Oxyhydrogen was once used in working platinum, because at the time, only it could burn hot enough to melt the metal . These techniques have been superseded by the electric arc furnace. | 0 | Theoretical and Fundamental Chemistry |
Where it is impossible or impractical to discharge sewage from a property into a gravity sanitary sewer, a pressure sewer may provide an alternative means of connection. A macerator pump in a pumping well close to the property ejects sewage through a small diameter high pressure pipe into the nearest gravity sewer. | 1 | Applied and Interdisciplinary Chemistry |
Specific weight is often used as a property of soil to solve earthwork problems.
In soil mechanics, specific weight may refer to: | 0 | Theoretical and Fundamental Chemistry |
Cereals & Grains Association has eleven [https://web.archive.org/web/20060927023025/http://www.aaccnet.org/divisions/default.cfm divisions]. These include biotechnology, carbohydrate, engineering/processing, milling/baking, nutrition, protein, rheology, rice, [https://www.cerealsgrains.org/membership/divisions/Pages/FoodSafetyandQuality.aspx food safety and quality], pet and animal food, and pulses. | 1 | Applied and Interdisciplinary Chemistry |
Gofman considered that "nuclear deterrence is important", for he did not believe that comprehensive test bans were enforceable; thus he favored underground atomic bomb tests while acknowledging that "They are harmful, a little will leak out. A small number of people will get hurt." He claimed "I dont understand the disarmament movement". More precisely, he was of the opinion that if the US were to disarm unilaterally, "the Soviet leaders may well try to make [the US] a slave state. […] There will surely never be a solution to human problems by any coercion or force. But there will also never be a solution through unarmed freedom as long as powerful bullies exist who will use' force." | 0 | Theoretical and Fundamental Chemistry |
About 99% of the mass of the human body is made up of six elements: oxygen, carbon, hydrogen, nitrogen, calcium, and phosphorus. Only about 0.85% is composed of another five elements: potassium, sulfur, sodium, chlorine, and magnesium. All 11 are necessary for life. The remaining elements are trace elements, of which more than a dozen are thought on the basis of good evidence to be necessary for life. All of the mass of the trace elements put together (less than 10 grams for a human body) do not add up to the body mass of magnesium, the least common of the 11 non-trace elements. | 1 | Applied and Interdisciplinary Chemistry |
Some ferredoxins have a sufficiently high redox potential that they can be directly reduced by NADPH. One such ferredoxin is adrenoxin (-274mV) which takes part in the biosynthesis of many mammalian steroids. The ferredoxin Fd3 in the roots of plants that reduces nitrate and sulfite has a midpoint potential of -337mV and is also reduced by NADPH. | 0 | Theoretical and Fundamental Chemistry |
While a finite thermal contact conductance is due to voids at the interface, surface waviness, and surface roughness, etc., a finite conductance exists even at near ideal interfaces as well. This conductance, known as thermal boundary conductance, is due to the differences in electronic and vibrational properties between the contacting materials. This conductance is generally much higher than thermal contact conductance, but becomes important in nanoscale material systems. | 0 | Theoretical and Fundamental Chemistry |
These tests validated the system for planetary exploration. Some improvements to be addressed in the future are instrument miniaturization, extraction protocols, and antibody stability under outer space conditions. SOLID would be one of the payloads of the proposed Icebreaker Life to Mars, or a lander to Europa. | 1 | Applied and Interdisciplinary Chemistry |
As a Tumor Associated Carbohydrate Antigen (TACA), Globo-H is a promising clinical target for immunotherapy. While absent in normal tissues, the glycosphingolipid is overexpressed in a variety of epithelial cancer cell types including human pancreatic, gastric, lung, colorectal, esophageal, and breast tumors. | 1 | Applied and Interdisciplinary Chemistry |
Marmesin (nodakenetin) is a chemical compound precursor in psoralen and linear furanocoumarins biosynthesis.
Marmesin plays a central role in the biosynthesis of furocoumarins in the plant ruta graveolens, more commonly known as rue. It acts as the natural intermediate in the formation of the furan ring that leads to a 4’,5’-dihydro furocoumarin-derivative. This substance can then be transformed into psoralen and other furocoumarins present in rue. Upon feeding the herb a dose of marmesin, radioactivity became strongly incorporated into psoralen and thus the plant itself. | 1 | Applied and Interdisciplinary Chemistry |
The frictional coefficient of an arbitrary spheroid of volume equals
where is the translational friction coefficient of a sphere of equivalent volume (Stokes' law)
and is the Perrin translational friction factor
The frictional coefficient is related to the diffusion constant D by the Einstein relation
Hence, can be measured directly using analytical ultracentrifugation, or indirectly using various methods to determine the diffusion constant (e.g., NMR and dynamic light scattering). | 1 | Applied and Interdisciplinary Chemistry |
Organophosphines are organophosphorus compounds with the formula PRH, where R is an organic substituent. These compounds can be classified according to the value of n: primary phosphines (n = 1), secondary phosphines (n = 2), tertiary phosphines (n = 3). All adopt pyramidal structures. Organophosphines are generally colorless, lipophilic liquids or solids. The parent of the organophosphines is phosphine (PH). | 0 | Theoretical and Fundamental Chemistry |
A subunit vaccine is a vaccine that contains purified parts of the pathogen that are antigenic, or necessary to elicit a protective immune response. Subunit vaccine can be made from dissembled viral particles in cell culture or recombinant DNA expression, in which case it is a recombinant subunit vaccine.
A "subunit" vaccine doesnt contain the whole pathogen, unlike live attenuated or inactivated vaccine, but contains only the antigenic parts such as proteins, polysaccharides or peptides. Because the vaccine doesnt contain "live" components of the pathogen, there is no risk of introducing the disease, and is safer and more stable than vaccines containing whole pathogens.
Other advantages include being well-established technology and being suitable for immunocompromised individuals. Disadvantages include being relatively complex to manufacture compared to some vaccines, possibly requiring adjuvants and booster shots, and requiring time to examine which antigenic combinations may work best.
The first recombinant subunit vaccine was produced in the mid-1980s to protect people from Hepatitis B. Other recombinant subunit vaccines licensed include Engerix-B (hepatitis B), Gardasil 9 (Human Papillomavirus), Flublok(influenza), Shingrix (Herpes zoster) and Nuvaxovid (Coronavirus disease 2019).
After injection, antigens trigger the production of antigen-specific antibodies, which are responsible for recognising and neutralising foreign substances. Basic components of recombinant subunit vaccines include recombinant subunits, adjuvants and carriers. Additionally, recombinant subunit vaccines are popular candidates for the development of vaccines against infectious diseases (e.g. tuberculosis, dengue)
Recombinant subunit vaccines are considered to be safe for injection. The chances of adverse effects vary depending on the specific type of vaccine being administered. Minor side effects include injection site pain, fever, and fatigue, and serious adverse effects consist of anaphylaxis and potentially fatal allergic reaction. The contraindications are also vaccine-specific; they are generally not recommended for people with the previous history of anaphylaxis to any component of the vaccines. Advice from medical professionals should be sought before receiving any vaccination. | 1 | Applied and Interdisciplinary Chemistry |
Resin bound paving is a mixture of resin binder and aggregate. Clear resin is used to fully coat each aggregate particle before laying. Enough resin is used to allow each aggregate particle to adhere to one another and to the base yet leave voids for water to permeate through. Resin bound paving provides a strong and durable surface that is suitable for pedestrian and vehicular traffic in applications such as pathways, driveways, car parks and access roads. | 1 | Applied and Interdisciplinary Chemistry |
Nanostructures with spectrally selective thermal emittance properties offer numerous technological applications for energy generation and efficiency, e.g., for daytime radiative cooling of photovoltaic cells and buildings. These applications require high emittance in the frequency range corresponding to the atmospheric transparency window in 8 to 13 micron wavelength range. A selective emitter radiating strongly in this range is thus exposed to the clear sky, enabling the use of the outer space as a very low temperature heat sink. | 0 | Theoretical and Fundamental Chemistry |
HDAC11 has been shown to be related to HDACs 3 and 8, but its overall sequence is quite different from the other HDACs, leading it to be in its own category. HDAC11 has a catalytic domain located in its N-terminus. It has not been found incorporated in any HDAC complexes such as Nurd or SMRT which means it may have a special function unique to itself. It has been found that HDAC11 remains mainly in the nucleus. | 0 | Theoretical and Fundamental Chemistry |
Use of Tramadol during pregnancy is generally avoided, as it may cause some reversible withdrawal effects in the newborn. A small prospective study in France found, while an increased risk of miscarriages existed, no major malformations were reported in the newborn. Its use during lactation is also generally advised against, but a small trial found that infants breastfed by mothers taking tramadol were exposed to about 2.88% of the dose the mothers were taking. No evidence of this dose harming the newborn was seen. | 0 | Theoretical and Fundamental Chemistry |
Exohedral fullerenes, also called exofullerenes, are fullerenes that have additional atoms, ions, or clusters attached their outer spheres, such as CCl and CH. or fullerene ligands. | 0 | Theoretical and Fundamental Chemistry |
VMA synthesis is the first step of a two-step process practiced by Rhodia since the 1970s to synthesize artificial vanilla. Specifically the reaction entails the condensation of guaiacol and glyoxylic acid in an ice cold, aqueous solution with sodium hydroxide. | 1 | Applied and Interdisciplinary Chemistry |
The congress opened in the assembly hall of the Baden Parliament the 3th September, with Weltzien serving as the general secretary. In his address, he highlighted the international and discipline-specific nature of the meeting. Kekulé delivered an opening address. Wurtz documented the proceedings for future publication. A dinner for 120 people was held in the museum hall.
The next day, the assembly, led by Weltzien, discussed the committee's proposed theme of the day before regarding the disputed meanings of "atom," "molecule," and "equivalence." However, no conclusions were reached, leading the committee to meet twice on the same day. They decided to present three specific nomenclature proposals to the assembly for further consideration. | 1 | Applied and Interdisciplinary Chemistry |
Adverse effects include nausea, indigestion, diarrhea, constipation, gastrointestinal ulceration, headache, dizziness, rash, salt and fluid retention, and high blood pressure.
Infrequent adverse effects include esophageal ulceration, heart failure, high blood levels of potassium, kidney impairment, confusion, and bronchospasm. Ibuprofen can exacerbate asthma, sometimes fatally.
Allergic reactions, including anaphylaxis and anaphylactic shock, may occur. Ibuprofen may be quantified in blood, plasma, or serum to demonstrate the presence of the drug in a person having experienced an anaphylactic reaction, confirm a diagnosis of poisoning in people who are hospitalized, or assist in a medicolegal death investigation. A monograph relating ibuprofen plasma concentration, time since ingestion, and risk of developing renal toxicity in people who have overdosed has been published.
In October 2020, the US FDA required the drug label to be updated for all NSAID medications to describe the risk of kidney problems in unborn babies that result in low amniotic fluid. | 0 | Theoretical and Fundamental Chemistry |
Photoionization is the physical process in which an ion is formed from the interaction of a photon with an atom or molecule. | 0 | Theoretical and Fundamental Chemistry |
Although losing favor in the medical industry, reporting of serum concentrations in units of "eq/L" (= 1 N) or "meq/L" (= 0.001 N) still occurs. | 0 | Theoretical and Fundamental Chemistry |
Solid diazonium halides are often dangerously explosive, and fatalities and injuries have been reported.
The nature of the anions affects stability of the salt. Arenediazonium perchlorates, such as nitrobenzenediazonium perchlorate, have been used to initiate explosives. | 0 | Theoretical and Fundamental Chemistry |
The ab initio binding energy between the two water molecules is estimated to be 5-6 kcal/mol, although values between 3 and 8 have been obtained depending on the method. The experimentally measured dissociation energy (including nuclear quantum effects) of (HO) and (DO) are 3.16 ± 0.03 kcal/mol (13.22 ± 0.12 kJ/mol) and 3.56 ± 0.03 kcal/mol (14.88 ± 0.12 kJ/mol), respectively. The values are in excellent agreement with calculations. The O-O distance of the vibrational ground-state is experimentally measured at ca. 2.98 Å; the hydrogen bond is almost linear, but the angle with the plane of the acceptor molecule is about 57°. The vibrational ground-state is known as the linear water dimer (shown in the figure to the right), which is a near prolate top (viz., in terms of rotational constants, A > B ≈ C). Other configurations of interest include the cyclic dimer and the bifurcated dimer. | 0 | Theoretical and Fundamental Chemistry |
As the Weber number increases, the drop deformation upon impact also increases. The drop deformation pattern can be split up into regimes based on the Weber number.
* At We << 1, there is not significant deformation.
* For We on the order of 1, the drop experiences significant deformation, and flattens somewhat on the surface.
* When We ~ 4, waves form on the drop.
* When We ~ 18, satellite droplet(s) break off of the drop, which is now an elongated vertical column.
* For large We (for which the magnitude depends on the specific surface structure), many satellite drops break off during spreading and/or retraction of the drop. | 1 | Applied and Interdisciplinary Chemistry |
Most living tissues prosper at a near-neutral pH—that is, a pH close to 7. The pH of blood ranges from 7.35 to 7.45, for instance. When cells are grown in tissue culture, the medium in which they grow is held close to this physiological pH. A small amount of phenol red added to this growth medium will have a pink-red color under normal conditions. Typically, 15 mg/L are used for cell culture.
In the event of problems, waste products produced by dying cells or overgrowth of contaminants will cause a change in pH, leading to a change in indicator color. For example, a culture of relatively slowly dividing mammalian cells can be quickly overgrown by bacterial contamination. This usually results in an acidification of the medium, turning it yellow. Many biologists find this a convenient way to rapidly check on the health of tissue cultures. In addition, the waste products produced by the mammalian cells themselves will slowly decrease the pH, gradually turning the solution orange and then yellow. This color change is an indication that even in the absence of contamination, the medium needs to be replaced (generally, this should be done before the medium has turned completely orange).
Since the color of phenol red can interfere with some spectrophotometric and fluorescent assays, many types of tissue culture media are also available without phenol red. | 0 | Theoretical and Fundamental Chemistry |
Cytochrome b was synthesized with photo-methionine to map the protein-protein interactions while also identifying its structure to study the mammalian mixed function oxidase system (also known as the MFO). This system is located in the membrane of the endoplasmic reticulum and it is composed of cytochrome P450, NADPH: cytochrome P450 reductase, and cytochrome b along with NADH: cytochrome b reductase. Once the cytochrome b complex had photo-methionine incorporated (meaning photo-met was substituted in place of methionine and now photo-cyt b), photo-cyt b and cytochrome P450 were put under UV-light and the products were able to be studied using SDS-Page; this method had shown three cross-links. The photo-methionine had proven successful in mapping photo-cyt b as the MALDI-TOF method shown three oligomers (from chymotryptic peptides) that were composed of photo-cyt b and cytochrome P450 in molecular weight ratio's of 1:1, 1:2, and 2:1. What makes photo-methionine here so useful in studying cytochrome P450 and cytochrome b is that this method not only mapped protein-protein interfaces not only in regions exposed to solvent, but also in the native environment; the membrane. A typical cross-linking method can only work in solvent exposed regions, proving once again that photo-methionine is useful to map these protein-protein interactions with the protein in their native environment. | 0 | Theoretical and Fundamental Chemistry |
DREADDS have been used in many animal models (e.g., mice and other non-primate animals) to target and influence the activity of various cells. Chemogenetics used in animals assists with demonstrating human disease models such as Parkinsons disease. Having this information allows scientists understand whether viral expression of DREADD proteins, both in-vivo enhancers and inhibitors of neuronal function can be used to bidirectionally affect the behaviors and the activity of the involved neurons. Recent studies have shown that DREADDs were successfully used to treat the motor deficits of rats modeling Parkinsons disease. Other studies have had successes linking the usage of DREADDs and influencing drug seeking and drug sensitization behavior.
The progression of chemogenetics from rodents to non-human primates has been slow due to increased demand in time and expense surrounding these projects. However, some recent studies in 2016 have been able to demonstrate successes showing that silencing the activity of neurons in the orbitofrontal cortex along with the removal of rhinal cortex, restricted the reward task performance in macaques. | 1 | Applied and Interdisciplinary Chemistry |
The production of transparent wood from the delignification process vary study by study. However, the basics behind it are as follows: a wood sample is drenched in heated (80 °C–100 °C) solutions containing sodium chloride, sodium hypochlorite, or sodium hydroxide/sulfite for about 3–12 hours followed by immersion in boiling hydrogen peroxide. Then, the lignin is separated from the cellulose and hemicellulose structure, turning the wood white and allowing the resin penetration to start. Finally, the sample is immersed in a matching resin, usually PMMA, under high temperatures (85 °C) and a vacuum for 12 hours. This process fills the space previously occupied by the lignin and the open wood cellular structure resulting in the final transparent wood composite.
While the delignification process is a successful method of production, it is limited to its laboratory and experimental production of a small, and low-thickness material that is unable to meet its practical application requirements. However, at Jiangsu Co-Innovation Center for Efficient Processing and Utilization of Forest Resources in 2018, Xuan Wang and his colleagues developed a new production method of infiltrating a prepolymerized methyl methacrylate (MMA) solution into delignified wood fibers. By utilizing this new technique, large-size transparent wood with any thickness or any measure can be easily made. Yet in spite of this success in the manufacture, challenges still exist with regard to mechanical stability and adjustable optical performance. | 0 | Theoretical and Fundamental Chemistry |
Communities may implement low impact development techniques to reduce flows of stormwater into the collection system. This includes:
*constructing new and renovated streets, parking lots and sidewalks with interlocking stones, permeable paving and pervious concrete
*installing green roofs on buildings
*installing bioretention systems, also called rain gardens, in landscaped areas
*installing rainwater harvesting equipment to collect runoff from building roofs during wet weather for irrigating landscapes and gardens during dry weather
*implementing graywater collection and use on site to reduce sewage discharges at all times | 1 | Applied and Interdisciplinary Chemistry |
Antiaromaticity is a chemical property of a cyclic molecule with a π electron system that has higher energy, i.e., it is less stable due to the presence of 4n delocalised (π or lone pair) electrons in it, as opposed to aromaticity. Unlike aromatic compounds, which follow Hückels rule ([4n'+2] π electrons) and are highly stable, antiaromatic compounds are highly unstable and highly reactive. To avoid the instability of antiaromaticity, molecules may change shape, becoming non-planar and therefore breaking some of the π interactions. In contrast to the diamagnetic ring current present in aromatic compounds, antiaromatic compounds have a paramagnetic ring current, which can be observed by NMR spectroscopy.
Examples of antiaromatic compounds are pentalene (A), biphenylene (B), cyclopentadienyl cation (C). The prototypical example of antiaromaticity, cyclobutadiene, is the subject of debate, with some scientists arguing that antiaromaticity is not a major factor contributing to its destabilization.
Cyclooctatetraene is an example of a molecule adopting a non-planar geometry to avoid the destabilization that results from antiaromaticity. If it were planar, it would have a single eight-electron π system around the ring, but it instead adopts a boat-like shape with four individual π bonds. Because antiaromatic compounds are often short-lived and difficult to work with experimentally, antiaromatic destabilization energy is often modeled by simulation rather than by experimentation. | 0 | Theoretical and Fundamental Chemistry |
Any sort of saturated molecule can be the starting point for generating isolobal fragments. The molecule's bonding and nonbonding molecular orbitals (MOs) should be filled and the antibonding MOs empty. With each consecutive generation of an isolobal fragment, electrons are removed from the bonding orbitals and a frontier orbital is created. The frontier orbitals are at a higher energy level than the bonding and nonbonding MOs. Each frontier orbital contains one electron. For example, consider Figure 5, which shows the production of frontier orbitals in tetrahedral and octahedral molecules.
As seen above, when a fragment is formed from CH, one of the sp hybrid orbitals involved in bonding becomes a nonbonding singly occupied frontier orbital. The frontier orbital’s increased energy level is also shown in the figure. Similarly when starting with a metal complex such as d-ML, the dsp hybrid orbitals are affected. Furthermore, the t nonbonding metal orbitals are unaltered. | 0 | Theoretical and Fundamental Chemistry |
Radionuclide therapy (also known as systemic radioisotope therapy, radiopharmaceutical therapy, or molecular radiotherapy), is a form of targeted therapy. Targeting can be due to the chemical properties of the isotope such as radioiodine which is specifically absorbed by the thyroid gland a thousandfold better than other bodily organs. Targeting can also be achieved by attaching the radioisotope to another molecule or antibody to guide it to the target tissue. The radioisotopes are delivered through infusion (into the bloodstream) or ingestion. Examples are the infusion of metaiodobenzylguanidine (MIBG) to treat neuroblastoma, of oral iodine-131 to treat thyroid cancer or thyrotoxicosis, and of hormone-bound lutetium-177 and yttrium-90 to treat neuroendocrine tumors (peptide receptor radionuclide therapy).
Another example is the injection of radioactive yttrium-90 or holmium-166 microspheres into the hepatic artery to radioembolize liver tumors or liver metastases. These microspheres are used for the treatment approach known as selective internal radiation therapy. The microspheres are approximately 30 µm in diameter (about one-third of a human hair) and are delivered directly into the artery supplying blood to the tumors. These treatments begin by guiding a catheter up through the femoral artery in the leg, navigating to the desired target site and administering treatment. The blood feeding the tumor will carry the microspheres directly to the tumor enabling a more selective approach than traditional systemic chemotherapy. There are currently three different kinds of microspheres: SIR-Spheres, TheraSphere and QuiremSpheres.
A major use of systemic radioisotope therapy is in the treatment of bone metastasis from cancer. The radioisotopes travel selectively to areas of damaged bone, and spare normal undamaged bone. Isotopes commonly used in the treatment of bone metastasis are radium-223, strontium-89 and samarium (Sm) lexidronam.
In 2002, the United States Food and Drug Administration (FDA) approved ibritumomab tiuxetan (Zevalin), which is an anti-CD20 monoclonal antibody conjugated to yttrium-90.
In 2003, the FDA approved the tositumomab/iodine (I) tositumomab regimen (Bexxar), which is a combination of an iodine-131 labelled and an unlabelled anti-CD20 monoclonal antibody.
These medications were the first agents of what is known as radioimmunotherapy, and they were approved for the treatment of refractory non-Hodgkin's lymphoma. | 0 | Theoretical and Fundamental Chemistry |
IBX is notable for oxidizing vicinal diols (or glycols) to diketones without cleavage of the carbon-carbon bond, but oxidative cleavage of glycols to two aldehydes or ketones can occur when modified conditions are used (elevated temperatures or trifluoroacetic acid solvent).
The reaction mechanism for this glycol cleavage is based on initial formation of an adduct between 10-I-4 IBX and DMSO to a 12-I-5 intermediate 3 in which DMSO acts as a leaving group for incoming alcohol 4 to intermediate 5. One equivalent of water is split off forming 12-I-5 spirobicyclic periodinane 6 setting the stage for fragmentation to 7. With hydroxyl alpha protons present, oxidation to the acyloin competes. Trifluoroacetic acid is found to facilitate the overall reaction. | 0 | Theoretical and Fundamental Chemistry |
Conductivity or specific conductance of an electrolyte solution is a measure of its ability to conduct electricity. The SI unit of conductivity is siemens per meter (S/m).
Conductivity measurements are used routinely in many industrial and environmental applications as a fast, inexpensive and reliable way of measuring the ionic content in a solution. For example, the measurement of product conductivity is a typical way to monitor and continuously trend the performance of water purification systems.
In many cases, conductivity is linked directly to the total dissolved solids (TDS). <br> <br>High quality deionized water has a conductivity of <br>
at 25 °C.
<br>The preparation of salt solutions often takes place in unsealed beakers. In this case the conductivity of purified water often is 10 to 20 times higher. A discussion can be found below.
Typical drinking water is in the range of 200–800 μS/cm, while sea water is about 50 mS/cm (or 0.05 S/cm).
Conductivity is traditionally determined by connecting the electrolyte in a Wheatstone bridge. Dilute solutions follow Kohlrauschs law of concentration dependence and additivity of ionic contributions. Lars Onsager gave a theoretical explanation of Kohlrauschs law by extending Debye–Hückel theory. | 0 | Theoretical and Fundamental Chemistry |
An organotroph is an organism that obtains hydrogen or electrons from organic substrates. This term is used in microbiology to classify and describe organisms based on how they obtain electrons for their respiration processes. Some organotrophs such as animals and many bacteria, are also heterotrophs. Organotrophs can be either anaerobic or aerobic.
Antonym: Lithotroph, Adjective: Organotrophic. | 1 | Applied and Interdisciplinary Chemistry |
A valve ball is also used for severe duty, high-pressure, high-tolerance applications. They are typically made of stainless steel, titanium, Stellite, Hastelloy, brass, or nickel. They can also be made of different types of plastic, such as ABS, PVC, PP or PVDF. | 1 | Applied and Interdisciplinary Chemistry |
Friedrich Kohlrausch in 1875–1879 established that to a high accuracy in dilute solutions, molar conductivity can be decomposed into contributions of the individual ions. This is known as Kohlrausch's law of independent ionic migration.
For any electrolyte AB, the limiting molar conductivity is expressed as x times the limiting molar conductivity of A and y times the limiting molar conductivity of B.
where:
: λ is the limiting molar ionic conductivity of ion i,
: ν is the number of ions i in the formula unit of the electrolyte (e.g. 2 and 1 for Na and sulfate| in NaSO).
Kohlrausch's evidence for this law was that the limiting molar conductivities of two electrolytes with two different cations and a common anion differ by an amount which is independent of the nature of the anion. For example, = for X = Cl, I and . This difference is ascribed to a difference in ionic conductivities between K and Na. Similar regularities are found for two electrolytes with a common anion and two cations. | 0 | Theoretical and Fundamental Chemistry |
Homoserine (also called isothreonine) is an α-amino acid with the chemical formula HOCCH(NH)CHCHOH. -Homoserine is not one of the common amino acids encoded by DNA. It differs from the proteinogenic amino acid serine by insertion of an additional -CH- unit into the backbone. Homoserine, or its lactone form, is the product of a cyanogen bromide cleavage of a peptide by degradation of methionine.
-homoserine from -aspartic acid This image shows the wrong enantiomers! -->
Homoserine is an intermediate in the biosynthesis of three essential amino acids: methionine, threonine (an isomer of homoserine), and isoleucine. Its complete biosynthetic pathway includes glycolysis, the tricarboxylic acid (TCA) or citric acid cycle (Krebs cycle), and the aspartate metabolic pathway. It forms by two reductions of aspartic acid via the intermediacy of aspartate semialdehyde. Specifically, the enzyme homoserine dehydrogenase, in association with NADPH, catalyzes a reversible reaction that interconverts -aspartate-4-semialdehyde to -homoserine. Then, two other enzymes, homoserine kinase and homoserine O-succinyltransferase use homoserine as a substrate and produce phosphohomoserine and O-succinyl homoserine respectively. | 1 | Applied and Interdisciplinary Chemistry |
Bragg diffraction (also referred to as the Bragg formulation of X-ray diffraction) was first proposed by Lawrence Bragg and his father, William Henry Bragg, in 1913 after their discovery that crystalline solids produced surprising patterns of reflected X-rays (in contrast to those produced with, for instance, a liquid). They found that these crystals, at certain specific wavelengths and incident angles, produced intense peaks of reflected radiation.
Lawrence Bragg explained this result by modeling the crystal as a set of discrete parallel planes separated by a constant parameter . He proposed that the incident X-ray radiation would produce a Bragg peak if reflections off the various planes interfered constructively. The interference is constructive when the phase difference between the wave reflected off different atomic planes is a multiple of ; this condition (see Bragg condition section below) was first presented by Lawrence Bragg on 11 November 1912 to the Cambridge Philosophical Society. Although simple, Bragg's law confirmed the existence of real particles at the atomic scale, as well as providing a powerful new tool for studying crystals. Lawrence Bragg and his father, William Henry Bragg, were awarded the Nobel Prize in physics in 1915 for their work in determining crystal structures beginning with NaCl, ZnS, and diamond. They are the only father-son team to jointly win.
The concept of Bragg diffraction applies equally to neutron diffraction and approximately to electron diffraction. In both cases the wavelengths are comparable with inter-atomic distances (~ 150 pm). Many other types of matter waves have also been shown to diffract, and also light from objected with a larger ordered structure such as opals. | 0 | Theoretical and Fundamental Chemistry |
Like other Short interspersed nuclear elements (SINEs), MIR elements used the machinery of LINE elements for their propagation in the genome, which took place around 130 million years ago. They cannot retrotranspose anymore since the loss of activity of the required reverse transcriptase. | 1 | Applied and Interdisciplinary Chemistry |
*Alchemy and chemistry in medieval Islam
*Chinese Alchemy
**Neidan
**Processing (Chinese materia medica)
*Iatrochemistry
**Spagyric
*New Age
*Psychoanalysis
**Analytical psychology
***Individuation
**Metacognition
*Rasayana | 1 | Applied and Interdisciplinary Chemistry |
The Middle Bronze Age settlement is smaller than its precursor and no evidence for a palace has been found. | 1 | Applied and Interdisciplinary Chemistry |
In chemistry, metallacrowns are a macrocyclic compounds that consist of metal ions and solely or predominantly heteroatoms in the ring. Classically, metallacrowns contain an [M–N–O] repeat unit in the macrocycle. First discovered by Vincent L. Pecoraro and Myoung Soo Lah in 1989, metallacrowns are best described as inorganic analogues of crown ethers. To date, over 600 reports of metallacrown research have been published. Metallacrowns with sizes ranging from 12-MC-4 to 60-MC-20 have been synthesized. | 0 | Theoretical and Fundamental Chemistry |
Methanosarcina acetivorans is a versatile methane producing microbe which is found in such diverse environments as oil wells, trash dumps, deep-sea hydrothermal vents, and oxygen-depleted sediments beneath kelp beds. Only M. acetivorans and microbes in the genus Methanosarcina use all three known metabolic pathways for methanogenesis. Methanosarcinides, including M. acetivorans, are also the only archaea capable of forming multicellular colonies, and even show cellular differentiation. The genome of M. acetivorans is one of the largest archaeal genomes ever sequenced. Furthermore, one strain of M. acetivorans, M. a. C2A, has been identified to possess an F-type ATPase (unusual for archaea, but common for bacteria, mitochondria and chloroplasts) along with an A-type ATPase. | 1 | Applied and Interdisciplinary Chemistry |
The KhAB-500 is the provisional naming of a series of World War II-era aerial bombs developed by the Soviet Air Force to deliver chemical weapons. | 1 | Applied and Interdisciplinary Chemistry |
Triptans is a word commonly used for a class of anti-migraine drugs that are selective 5-hydroxytryptamine/serotonin (5-HT) agonists. Migraine is a complex disease which affects about 15% of the population and can be highly disabling.
Triptans have advantages over ergotamine and dihydroergotamine, such as selective pharmacology, well established safety record and evidence-based prescribing instructions. Triptans are therefore often preferred treatment in migraine. | 1 | Applied and Interdisciplinary Chemistry |
Studies on insect cell lines and in vivo experiments on D. melanogaster have revealed active expression of Hexo1 and Hexo2, and, most importantly, the fused lobe (fdl) gene encoding fused ß-lobe (FDL), also known as GNase, an orthologue of A. thaliana and human Hex. FDL is expressed in high abundance in vesicles and the plasma membrane and has, unlike Hexo1 and Hexo2, been linked to fruit fly paucimannosidic protein production. However, except for the well-studied D. melanogaster and other common insect model organisms, solid evidence for active involvement of Hex and/or the possible concerted usage of the GnT-I-independent pathway or alternative truncation pathways for paucimannosidic protein production remains unavailable across the diverse class of insects. | 1 | Applied and Interdisciplinary Chemistry |
A Ramachandran plot (also known as a Ramachandran diagram or a [φ,ψ] plot), originally developed in 1963 by G. N. Ramachandran, C. Ramakrishnan, and V. Sasisekharan, is a way to visualize energetically allowed regions for backbone dihedral angles ψ against φ of amino acid residues in protein structure.
In a protein chain three dihedral angles are defined:
* ω (omega) is the angle in the chain C − C' − N − C,
* φ (phi) is the angle in the chain C − N − C − C
* ψ (psi) is the angle in the chain N − C − C − N (called φ′' by Ramachandran)
The figure at right illustrates the location of each of these angles (but it does not show correctly the way they are defined).
The planarity of the peptide bond usually restricts ω to be 180° (the typical trans case) or 0° (the rare cis case). The distance between the C atoms in the trans and cis isomers is approximately 3.8 and 2.9 Å, respectively. The vast majority of the peptide bonds in proteins are trans, though the peptide bond to the nitrogen of proline has an increased prevalence of cis compared to other amino-acid pairs.
The side chain dihedral angles are designated with χ (chi-n). They tend to cluster near 180°, 60°, and −60°, which are called the trans, gauche, and gauche conformations. The stability of certain sidechain dihedral angles is affected by the values φ and ψ. For instance, there are direct steric interactions between the Cγ of the side chain in the gauche rotamer and the backbone nitrogen of the next residue when ψ is near -60°. This is evident from statistical distributions in backbone-dependent rotamer libraries. | 0 | Theoretical and Fundamental Chemistry |
Typically, process flow diagrams of a single unit process include the following:
* Process piping
* Major equipment items
*Connections with other systems
* Major bypass and recirculation (recycle) streams
* Operational data (temperature, pressure, mass flow rate, density, etc.), often by stream references to a mass balance
* Process stream names
Process flow diagrams generally do not include:
* Pipe classes or piping line numbers
* Instrumentation details
* Minor bypass lines
* Instrumentation
* Controllers like Level Control or Flow Control
* Isolation and shutoff valves
* Maintenance vents and drains
* Relief and safety valves
* Flanges
Process flow diagrams of multiple process units within a large industrial plant will usually contain less detail and may be called block flow diagrams or schematic flow diagrams. | 1 | Applied and Interdisciplinary Chemistry |
The term geochemistry was first used by the Swiss-German chemist Christian Friedrich Schönbein in 1838: "a comparative geochemistry ought to be launched, before geognosy can become geology, and before the mystery of the genesis of our planets and their inorganic matter may be revealed." However, for the rest of the century the more common term was "chemical geology", and there was little contact between geologists and chemists.
Geochemistry emerged as a separate discipline after major laboratories were established, starting with the United States Geological Survey (USGS) in 1884, which began systematic surveys of the chemistry of rocks and minerals. The chief USGS chemist, Frank Wigglesworth Clarke, noted that the elements generally decrease in abundance as their atomic weights increase, and summarized the work on elemental abundance in The Data of Geochemistry.
The composition of meteorites was investigated and compared to terrestrial rocks as early as 1850. In 1901, Oliver C. Farrington hypothesised that, although there were differences, the relative abundances should still be the same. This was the beginnings of the field of cosmochemistry and has contributed much of what we know about the formation of the Earth and the Solar System.
In the early 20th century, Max von Laue and William L. Bragg showed that X-ray scattering could be used to determine the structures of crystals. In the 1920s and 1930s, Victor Goldschmidt and associates at the University of Oslo applied these methods to many common minerals and formulated a set of rules for how elements are grouped. Goldschmidt published this work in the series Geochemische Verteilungsgesetze der Elemente [Geochemical Laws of the Distribution of Elements].
The research of Manfred Schidlowski from the 1960s to around the year 2002 was concerned with the biochemistry of the Early Earth with a focus on isotope-biogeochemistry and the evidence of the earliest life processes in Precambrian. | 0 | Theoretical and Fundamental Chemistry |
It exploits the favourable properties of the central difference and upwind scheme. It switches to upwind difference scheme when central difference scheme produces inaccurate results for high Peclet numbers. It produces physically realistic solution and has proved to be helpful in the prediction of practical flows. The only disadvantage associated with hybrid difference scheme is that the accuracy in terms of Taylor series truncation error is only first order. | 1 | Applied and Interdisciplinary Chemistry |
Nucleotides are the monomers which polymerize into nucleic acids. All nucleotides contain a sugar, a phosphate, and a nitrogenous base. The bases found in nucleic acids are either purines or pyrimidines. In the more complex multicellular animals, they are both primarily produced in the liver but the two different groups are synthesized in different ways. However, all nucleotide synthesis requires the use of phosphoribosyl pyrophosphate (PRPP) which donates the ribose and phosphate necessary to create a nucleotide. | 1 | Applied and Interdisciplinary Chemistry |
Mass transfer is the net movement of mass from one location (usually meaning stream, phase, fraction, or component) to another. Mass transfer occurs in many processes, such as absorption, evaporation, drying, precipitation, membrane filtration, and distillation. Mass transfer is used by different scientific disciplines for different processes and mechanisms. The phrase is commonly used in engineering for physical processes that involve diffusive and convective transport of chemical species within physical systems.
Some common examples of mass transfer processes are the evaporation of water from a pond to the atmosphere, the purification of blood in the kidneys and liver, and the distillation of alcohol. In industrial processes, mass transfer operations include separation of chemical components in distillation columns, absorbers such as scrubbers or stripping, adsorbers such as activated carbon beds, and liquid-liquid extraction. Mass transfer is often coupled to additional transport processes, for instance in industrial cooling towers. These towers couple heat transfer to mass transfer by allowing hot water to flow in contact with air. The water is cooled by expelling some of its content in the form of water vapour. | 1 | Applied and Interdisciplinary Chemistry |
Emissive power is the rate at which radiation is emitted per unit area. It is a measure of heat flux. The total emissive power from a surface is denoted as and can be determined by,where is in units of steradians and is the total intensity.
The total emissive power can also be found by integrating the spectral emissive power over all possible wavelengths. This is calculated as,where represents wavelength.
The spectral emissive power can also be determined from the spectral intensity, as follows,
where both spectral emissive power and emissive intensity are functions of wavelength. | 0 | Theoretical and Fundamental Chemistry |
Membership of the European Molecular Biology Organization (EMBO) is an award granted by the European Molecular Biology Organization (EMBO) in recognition of "research excellence and the outstanding achievements made by a life scientist".
, 88 EMBO Members and Associate Members have been awarded Nobel Prizes in either Physiology or Medicine, Chemistry or Physics. See :Category:Members of the European Molecular Biology Organization for examples of EMBO members. | 1 | Applied and Interdisciplinary Chemistry |
Examples of heterogeneous mixtures are emulsions and foams. In most cases, the mixture consists of two main constituents. For an emulsion, these are immiscible fluids such as water and oil. For a foam, these are a solid and a fluid, or a liquid and a gas. On larger scales both constituents are present in any region of the mixture, and in a well-mixed mixture in the same or only slightly varying concentrations. On a microscopic scale, however, one of the constituents is absent in almost any sufficiently small region. (If such absence is common on macroscopic scales, the combination of the constituents is a dispersed medium, not a mixture.) One can distinguish different characteristics of heterogeneous mixtures by the presence or absence of continuum percolation of their constituents. For a foam, a distinction is made between reticulated foam in which one constituent forms a connected network through which the other can freely percolate, or a closed-cell foam in which one constituent is present as trapped in small cells whose walls are formed by the other constituents. A similar distinction is possible for emulsions. In many emulsions, one constituent is present in the form of isolated regions of typically a globular shape, dispersed throughout the other constituent. However, it is also possible each constituent forms a large, connected network. Such a mixture is then called bicontinuous. | 0 | Theoretical and Fundamental Chemistry |
In certain countries, including Austria, Italy, Estonia, Hungary, Spain and Israel, the male does not have the full ability to withdraw consent to storage or use of embryos once they are fertilised. In the United States, the matter has been left to the courts on a more or less ad hoc basis. If embryos are implanted and a child is born contrary to the wishes of the male, he still has legal and financial responsibilities of a father. | 1 | Applied and Interdisciplinary Chemistry |
The grain macrostructure in ingots and most castings have three distinct regions or zones: the chill zone, columnar zone, and equiaxed zone. The image below depicts these zones.
The chill zone is named so because it occurs at the walls of the mold where the wall chills the material. Here is where the nucleation phase of the solidification process takes place. As more heat is removed the grains grow towards the center of the casting. These are thin, long columns that are perpendicular to the casting surface, which are undesirable because they have anisotropic properties. Finally, in the center the equiaxed zone contains spherical, randomly oriented crystals. These are desirable because they have isotropic properties. The creation of this zone can be promoted by using a low pouring temperature, alloy inclusions, or inoculants. | 1 | Applied and Interdisciplinary Chemistry |
All cells require ATP as an energy source for their metabolic activity. The kidney is damaged by anoxia when kidney cortical cells are unable to generate sufficient ATP under anaerobic conditions to meet the needs of the cells. When excising a kidney some anoxia is inevitable in the interval between dividing the renal artery and cooling the kidney. It has been shown by Bergstrom that 50% of a dogs kidneys cortical cells ATP content is lost within 1 minute of clamping the renal artery, and similar results were found by Warnick in whole mice kidneys, with a fall in cellular ATP by 50% after about 30 seconds of warm anoxia. Warnick and Bergstrom also showed that cooling the kidney immediately after removal markedly reduced any further ATP loss. When these non warm-injured kidneys were perfused with oxygenated hypothermic plasma, ATP levels were reduced by 50% after 24-hour storage and, after 48 hours, mean tissue ATP levels were a little higher than this indicating that synthesis of ATP had occurred. Pegg has shown that rabbit kidneys can resynthesize ATP after a period of perfusion storage following warm injury, but no resynthesis occurred in non warm-injured kidneys.
Warm anoxia can also occur during reimplantation of the kidney after storage. Lannon showed, by measurements of succinate metabolism, how the kidney was more sensitive to a period of warm hypoxia occurring after storage than to the same period of warm hypoxia occurring immediately prior to storage. | 1 | Applied and Interdisciplinary Chemistry |
A group from Princeton University reported the application of diffusiophoresis to water purification. Contaminated water is treated with CO to create carbonic acid, and to split the water into a waste stream and a potable water stream. This allows for easy ionic separation of suspended particles. This has huge energy cost and time savings opportunity to make drinking water safe compared to traditional water filtration methods for dirty water sources. | 0 | Theoretical and Fundamental Chemistry |
Standard ellipsometry (or just short ellipsometry) is applied, when no s polarized light is converted into p polarized light nor vice versa. This is the case for optically isotropic samples, for instance, amorphous materials or crystalline materials with a cubic crystal structure. Standard ellipsometry is also sufficient for optically uniaxial samples in the special case, when the optical axis is aligned parallel to the surface normal. In all other cases, when s polarized light is converted into p polarized light and/or vice versa, the generalized ellipsometry approach must be applied. Examples are arbitrarily aligned, optically uniaxial samples, or optically biaxial samples. | 0 | Theoretical and Fundamental Chemistry |
Number of chiral environments are created within the polymer. Cavities are formed between adjacent glucose units, and spaces/channels between polysaccharide chains. These chiral cavities or channels give the chiral discrimination capability to polysaccharide CSPs. The mechanism of Chiral discrimination is not well understood but believed to involve hydrogen bonding and dipole-dipole interaction between the analyte molecule and the ester or carbamate linkage of the CSP. | 0 | Theoretical and Fundamental Chemistry |
Victoreen produced their Model 496 in the 1980s and many were purchased by the United States Department of Energy. The 496 used a modified version of the same casing as the CD V-700 Model 6Bs that Victoreen had produced in the 1960s. If the decal on top of a Model 496 is removed, the markings of the older civil defense meter can be found cast into the top cover. However, the 496 features a number of improvements over any of the older civil defense versions, including modernized electronics, a BNC connector or MHV connector for external probes, a built-in speaker with on-off knob, a built-in battery test circuit, and a meter face graduated in Counts Per Minute for use with various probes. Other 490-series Victoreen models of the same era shared similar physical characteristics but varied considerably in their features. | 0 | Theoretical and Fundamental Chemistry |
The atomic nucleus is the small, dense region consisting of protons and neutrons at the center of an atom, discovered in 1911 by Ernest Rutherford based on the 1909 Geiger–Marsden gold foil experiment. After the discovery of the neutron in 1932, models for a nucleus composed of protons and neutrons were quickly developed by Dmitri Ivanenko and Werner Heisenberg. An atom is composed of a positively charged nucleus, with a cloud of negatively charged electrons surrounding it, bound together by electrostatic force. Almost all of the mass of an atom is located in the nucleus, with a very small contribution from the electron cloud. Protons and neutrons are bound together to form a nucleus by the nuclear force.
The diameter of the nucleus is in the range of () for hydrogen (the diameter of a single proton) to about for uranium. These dimensions are much smaller than the diameter of the atom itself (nucleus + electron cloud), by a factor of about 26,634 (uranium atomic radius is about ()) to about 60,250 (hydrogen atomic radius is about ).
The branch of physics concerned with the study and understanding of the atomic nucleus, including its composition and the forces that bind it together, is called nuclear physics. | 0 | Theoretical and Fundamental Chemistry |
Once they are identified along the z-axis, individual layers of DVD-like data may be accessed and tracked in similar ways to DVDs. The possibility of using parallel or page-based addressing has also been demonstrated. This allows much faster data transfer rates, but requires the additional complexity of spatial light modulators, signal imaging, more powerful lasers, and more complex data handling. | 0 | Theoretical and Fundamental Chemistry |
Optical rotation is measured with an instrument called a polarimeter. There is a linear relationship between the observed rotation and the concentration of optically active compound in the sample. There is a nonlinear relationship between the observed rotation and the wavelength of light used. Specific rotation is calculated using either of two equations, depending on whether the sample is a pure chemical to be tested or that chemical dissolved in solution. | 0 | Theoretical and Fundamental Chemistry |
The Journal of Chemical Ecology is a monthly peer-reviewed scientific journal published by Springer Science+Business Media covering all aspects of chemical ecology. The journal was established in 1975 and is the official journal of the International Society of Chemical Ecologists and the Asia-Pacific Association of Chemical Ecologists. The editor-in-chief is Gary W. Felton (Pennsylvania State University). According to the Journal Citation Reports, the journal has a 2013 impact factor of 2.239. | 1 | Applied and Interdisciplinary Chemistry |
Memory foam derives its viscoelastic properties from several effects, due to the materials internal structure. The network effect is the force working to restore the foams structure when it is deformed. This effect is generated by the deformed porous material pushing outwards to restore its structure against an applied pressure. Three effects work against the network effect, slowing the regeneration of the foam's original structure:
* The pneumatic effect, caused by the time it takes air to flow into the foam's porous structure.
* The adhesive effect, or adhesion, caused by the stickiness of the surfaces within the foam, which work against decompression as the internal pores within the foam are pressed together
* The relaxation effect (the strongest of the three forces working against expansion), caused by the foam's material being near its glass transition temperature—limiting its mobility, forcing any change to be gradual, and slowing the expansion of the foam once the applied pressure has been removed
The effects are temperature-dependent, so the temperature range at which memory foam retains its properties is limited. If it is too cold, it hardens. If it is too hot, it acts like conventional foams, quickly springing back to its original shape. The underlying physics of this process can be described by polymeric creep.
The pneumatic and adhesive effects are strongly correlated with the size of the pores within memory foam. Smaller pores lead to higher internal surface area and reduced air flow, increasing the adhesion and pneumatic effects. Thus the foams properties can be controlled by changing its cell structure and porosity. Its glass transition temperature can also be modulated by using additives in the foams material.
Memory foam's mechanical properties can affect the comfort of mattresses produced with it. There is also a trade-off between comfort and durability. Certain memory foams may have a more rigid cell structure, leading to a weaker distribution of weight, but better recovery of the original structure, leading to improved cyclability and durability. Denser cell structure can also resist the penetration of water vapor, leading to reduced weathering and better durability and overall appearance. | 0 | Theoretical and Fundamental Chemistry |
The "twin prime editing" (twinPE) mechanism reported in 2021 allows editing large sequences of DNA – sequences as large as genes – which addresses the method's key drawback. It uses a prime editor protein and two prime editing guide RNAs. | 1 | Applied and Interdisciplinary Chemistry |
The polypyrimidine tract is a region of pre-messenger RNA (mRNA) that promotes the assembly of the spliceosome, the protein complex specialized for carrying out RNA splicing during the process of post-transcriptional modification. The region is rich with pyrimidine nucleotides, especially uracil, and is usually 15–20 base pairs long, located about 5–40 base pairs before the 3' end of the intron to be spliced.
A number of protein factors bind to or associate with the polypyrimidine tract, including the spliceosome component U2AF and the polypyrimidine tract-binding protein (PTB), which plays a regulatory role in alternative splicing. PTB's primary function is in exon silencing, by which a particular exon region normally spliced into the mature mRNA is instead left out, resulting in the expression of an isoform of the protein for which the mRNA codes. Because PTB is ubiquitously expressed in many higher eukaryotes, it is thought to suppress the inclusion of "weak" exons with poorly defined splice sites. However, PTB binding is not sufficient to suppress "robust" exons.
The suppression or selection of exons is critical to the proper expression of tissue-specific isoforms. For example, smooth muscle and skeletal muscle express alternate isoforms distinguished by mutually exclusive exon selection in alpha-tropomyosin. | 1 | Applied and Interdisciplinary Chemistry |
The selection of the space-holder is one of the most crucial steps because it defines many of the properties of the resulting foam, including cell shape, cell size and macroporosity. The space-holder should be inert and represent the size and shape of the desired pores. The porosity may be adjusted anywhere between 50 and 85% without the filler material becoming a part of the resultant foam. It is also important to select a spacer that has limited or no solubility in titanium, as this incorporation will affect the mechanical properties of the resulting foam. | 0 | Theoretical and Fundamental Chemistry |
Another species that exhibits alarm calls is the Barbary macaque. Barbary macaque mothers are able to recognize their own offspring's calls and behave accordingly. | 1 | Applied and Interdisciplinary Chemistry |
When referring to a promoter some authors actually mean promoter + operator; i.e., the lac promoter is IPTG inducible, meaning that besides the lac promoter, the lac operon is also present. If the lac operator were not present the IPTG would not have an inducible effect.
Another example is the Tac-Promoter system (Ptac). Notice how tac is written as a tac promoter, while in fact tac is actually both a promoter and an operator. | 1 | Applied and Interdisciplinary Chemistry |
*The extremely strong complexation between avidin and biotin is instrumental in blood clotting, and has been used as the recognition motif to construct synthetic systems.
*The binding of enzymes with their cofactors has been used as a route to produce modified enzymes, electrically contacted enzymes, and even photoswitchable enzymes.
*DNA has been used both as a structural and as a functional unit in synthetic supramolecular systems. | 0 | Theoretical and Fundamental Chemistry |
One cheminformatics study identified 849,574 unique substituents up to 12 non-hydrogen atoms large and containing only carbon, hydrogen, nitrogen, oxygen, sulfur, phosphorus, selenium, and the halogens in a set of 3,043,941 molecules. Fifty substituents can be considered common as they are found in more than 1% of this set, and 438 are found in more than 0.1%. 64% of the substituents are found in only one molecule. The top 5 most common are the methyl, phenyl, chlorine, methoxy, and hydroxyl substituents. The total number of organic substituents in organic chemistry is estimated at 3.1 million, creating a total of 6.7×10 molecules. An infinite number of substituents can be obtained simply by increasing carbon chain length. For instance, the substituents methyl (-CH) and pentyl (-CH). | 0 | Theoretical and Fundamental Chemistry |
Liquefaction processes are used for scientific, industrial and commercial purposes. Many gases can be put into a liquid state at normal atmospheric pressure by simple cooling; a few, such as carbon dioxide, require pressurization as well. Liquefaction is used for analyzing the fundamental properties of gas molecules (intermolecular forces), or for the storage of gases, for example: LPG, and in refrigeration and air conditioning. There the gas is liquefied in the condenser, where the heat of vaporization is released, and evaporated in the evaporator, where the heat of vaporization is absorbed. Ammonia was the first such refrigerant, and is still in widespread use in industrial refrigeration, but it has largely been replaced by compounds derived from petroleum and halogens in residential and commercial applications.
Liquid oxygen is provided to hospitals for conversion to gas for patients with breathing problems, and liquid nitrogen is used in the medical field for cryosurgery, by inseminators to freeze semen, and by field and lab scientists to preserve samples. Liquefied chlorine is transported for eventual solution in water, after which it is used for water purification, sanitation of industrial waste, sewage and swimming pools, bleaching of pulp and textiles and manufacture of carbon tetrachloride, glycol and numerous other organic compounds as well as phosgene gas.
Liquefaction of helium (He) with the precooled Hampson–Linde cycle led to a Nobel Prize for Heike Kamerlingh Onnes in 1913. At ambient pressure the boiling point of liquefied helium is . Below 2.17 K liquid He becomes a superfluid (Nobel Prize 1978, Pyotr Kapitsa) and shows characteristic properties such as heat conduction through second sound, zero viscosity and the fountain effect among others.
The liquefaction of air is used to obtain nitrogen, oxygen, and argon and other atmospheric noble gases by separating the air components by fractional distillation in a cryogenic air separation unit. | 0 | Theoretical and Fundamental Chemistry |
The discovery of SEOP took decades for all the pieces to fall into place to create a complete technique. First, in 1897, Zeemans studies of sodium vapor led to the first result of optical pumping. The next piece was found in 1950 when Kastler determined a method to electronically spin-polarize rubidium alkali metal vapor using an applied magnetic field and illuminating the vapor with resonant circularly polarized light. Ten years later, Marie-Anne Bouchiat, T. M. Carver, and C. M. Varnum performed spin exchange', in which the electronic spin polarization was transferred to nuclear spins of a noble gas (He and Xe) through gas-phased collisions. Since then, this method has been greatly improved and expanded to use with other noble gases and alkali metals. | 0 | Theoretical and Fundamental Chemistry |
The overall performance of PET systems can be evaluated by quality control tools such as the Jaszczak phantom. | 1 | Applied and Interdisciplinary Chemistry |
In the quantum model of the electron, there is non-zero probability of finding the electron within the nucleus. In internal conversion, the wavefunction of an inner shell electron (usually an s electron) penetrates the nucleus. When this happens, the electron may couple to an excited energy state of the nucleus and take the energy of the nuclear transition directly, without an intermediate gamma ray being first produced. The kinetic energy of the emitted electron is equal to the transition energy in the nucleus, minus the binding energy of the electron to the atom.
Most IC electrons come from the K shell (the 1s state), as these two electrons have the highest probability of being within the nucleus. However, the s states in the L, M, and N shells (i.e., the 2s, 3s, and 4s states) are also able to couple to the nuclear fields and cause IC electron ejections from those shells (called L or M or N internal conversion). Ratios of K-shell to other L, M, or N shell internal conversion probabilities for various nuclides have been prepared.
An amount of energy exceeding the atomic binding energy of the s electron must be supplied to that electron in order to eject it from the atom to result in IC; that is to say, internal conversion cannot happen if the decay energy of the nucleus is less than a certain threshold.
Though s electrons are more likely for IC due to their superior nuclear penetration compared to electrons with greater orbital angular momentum, spectral studies show that p electrons (from shells L and higher) are occasionally ejected in the IC process. There are also a few radionuclides in which the decay energy is not sufficient to convert (eject) a 1s (K shell) electron, and these nuclides, to decay by internal conversion, must decay by ejecting electrons from the L or M or N shells (i.e., by ejecting 2s, 3s, or 4s electrons) as these binding energies are lower.
After the IC electron is emitted, the atom is left with a vacancy in one of its electron shells, usually an inner one. This hole will be filled with an electron from one of the higher shells, which causes another outer electron to fill its place in turn, causing a cascade. Consequently, one or more characteristic X-rays or Auger electrons will be emitted as the remaining electrons in the atom cascade down to fill the vacancies. | 0 | Theoretical and Fundamental Chemistry |
The radiotracer dilution method is used to calibrate open channel flow measurements. A solution with a known tracer concentration is injected at a constant known velocity into the channel flow. Downstream the tracer solution is thoroughly mixed over the flow cross-section, a continuous sample is taken and its tracer concentration in relation to that of the injected solution is determined. The flow reference value is determined by using the tracer balance condition between the injected tracer flow and the diluting flow.
The procedure is standardised (ISO 9555-1 and ISO 9555-2 for liquid flow in open channels). The best accredited measurement uncertainty is 1%. | 1 | Applied and Interdisciplinary Chemistry |
Formation of the Pol I preinitiation complex requires the binding of selective factor 1 (SL1 or TIF-IB) to the core element of the rDNA promoter. SL1 is a complex composed of TBP and at least three TBP-associated factors (TAFs). For basal levels of transcription, only SL1 and the initiation-competent form of Pol I (Pol Iβ), characterized by RRN3 binding, are required.
For activated transcription levels, UBTF (UBF) is also required. UBTF binds as a dimer to both the upstream control element (UCE) and core element of the rDNA promoter, bending the DNA to form an enhanceosome. SL1 has been found to stabilize the binding of UBTF to the rDNA promoter.
The subunits of the Pol I PIC differ between organisms. | 1 | Applied and Interdisciplinary Chemistry |
Reports on the "classical" pharmacology of pempidine have been published. The Spinks group, at ICI, compared pempidine, its N-ethyl analogue, and mecamylamine in considerable detail, with additional data related to several structurally simpler compounds. | 0 | Theoretical and Fundamental Chemistry |
RNA replication is the copying of one RNA to another. Many viruses replicate this way. The enzymes that copy RNA to new RNA, called RNA-dependent RNA polymerases, are also found in many eukaryotes where they are involved in RNA silencing.
RNA editing, in which an RNA sequence is altered by a complex of proteins and a "guide RNA", could also be seen as an RNA-to-RNA transfer. | 1 | Applied and Interdisciplinary Chemistry |
Other factors, such as signaller arousal, receiver identity, or increased risk of predation from calling, do not have a significant effect on the frequency of alarm call production. | 1 | Applied and Interdisciplinary Chemistry |
In materials science, work hardening, also known as strain hardening, is the strengthening of a metal or polymer by plastic deformation. Work hardening may be desirable, undesirable, or inconsequential, depending on the context.
This strengthening occurs because of dislocation movements and dislocation generation within the crystal structure of the material. Many non-brittle metals with a reasonably high melting point as well as several polymers can be strengthened in this fashion. Alloys not amenable to heat treatment, including low-carbon steel, are often work-hardened. Some materials cannot be work-hardened at low temperatures, such as indium, however others can be strengthened only via work hardening, such as pure copper and aluminum. | 1 | Applied and Interdisciplinary Chemistry |
Pyruvate is converted into acetyl-coenzyme A (acetyl-CoA) by the enzyme pyruvate dehydrogenase. This acetyl-CoA is then converted into acetate in E. coli, whilst producing ATP by substrate-level phosphorylation. Acetate formation requires two enzymes: phosphate acetyltransferase and acetate kinase.
acetyl-CoA + phosphate → acetyl-phosphate + CoA
acetyl-phosphate + ADP → acetate + ATP | 1 | Applied and Interdisciplinary Chemistry |
Propane-1,3-dithiol is the parent member of this series. It is employed as a reagent in organic chemistry, since it forms 1,3-dithianes upon treatment with ketones and aldehydes. When derived from aldehydes, the methyne () group is sufficiently acidic that it can be deprotonated and the resulting anion can be C-alkylated. The process is the foundation of the umpolung phenomenon.
Like 1,2-ethanedithiol, propanedithiol forms complexes with metals, for example with triiron dodecacarbonyl:
A naturally occurring 1,3-dithiol is dihydrolipoic acid.
1,3-Dithiols oxidize to give 1,2-dithiolanes. | 0 | Theoretical and Fundamental Chemistry |
The iodine clock reaction is a classical chemical clock demonstration experiment to display chemical kinetics in action; it was discovered by Hans Heinrich Landolt in 1886. The iodine clock reaction exists in several variations, which each involve iodine species (iodide ion, free iodine, or iodate ion) and redox reagents in the presence of starch. Two colourless solutions are mixed and at first there is no visible reaction. After a short time delay, the liquid suddenly turns to a shade of dark blue due to the formation of a triiodide–starch complex. In some variations, the solution will repeatedly cycle from colorless to blue and back to colorless, until the reagents are depleted. | 0 | Theoretical and Fundamental Chemistry |
The most common radical in the lower atmosphere is molecular dioxygen. Photodissociation of source molecules produces other radicals. In the lower atmosphere, important radical are produced by the photodissociation of nitrogen dioxide to an oxygen atom and nitric oxide (see below), which plays a key role in smog formation—and the photodissociation of ozone to give the excited oxygen atom O(1D) (see below). The net and return reactions are also shown ( and , respectively).
In the upper atmosphere, the photodissociation of normally unreactive chlorofluorocarbons (CFCs) by solar ultraviolet radiation is an important source of radicals (see eq. 1 below). These reactions give the chlorine radical, Cl, which catalyzes the conversion of ozone to O, thus facilitating ozone depletion (– below).
Such reactions cause the depletion of the ozone layer, especially since the chlorine radical is free to engage in another reaction chain; consequently, the use of chlorofluorocarbons as refrigerants has been restricted. | 1 | Applied and Interdisciplinary Chemistry |
Many retrosynthetic disconnections important for organic synthesis planning use carbocationic synthons. Carbon-carbon bonds, for example, exist ubiquitously in organic molecules, and are usually disconnected during a retrosynthetic analysis to yield carbocationic and carbanionic synthons. Carbon-heteroatom bonds, such as those found in alkyl halides, alcohols, and amides, can also be traced backwards retrosynthetically to polar C-X bond disconnections yielding a carbocation on carbon. oxonium and acylium ions are carbocationic synthons for carbonyl compounds such as ketones, aldehydes and carboxylic acid derivatives. An oxonium-type synthon was used in a disconnection en route to the hops ether, a key component of beer (see fig.1). In the forward direction, the researchers used an intramolecular aldol reaction catalyzed by titanium tetrachloride to form the tetrahydrofuran ring of hops ether.
Another common disconnection that features carbocationic synthons is the Pictet-Spengler reaction. The mechanism of the reaction involves C-C pi-bond attack onto an iminium ion, usually formed in situ from the condensation of an amine and an aldehyde. The Pictet-Spengler reaction has been used extensively for the synthesis of numerous indole and isoquinoline alkaloids.
Carbanion alkylation is a common strategy used to create carbon-carbon bonds. The alkylating agent is usually an alkyl halide or an equivalent compound with a good leaving group on carbon. Allyl halides are particularly attractive for S2-type reactions due to the increased reactivity added by the allyl system. Celestolide (4-acetyl-6-t-butyl-1,1-dimethylindane, a component of musk perfume) can be synthesized using a benzyl anion alkylation with 3-chloro-2-methyl-1-propene as an intermediate step. The synthesis is fairly straightforward, and has been adapted for teaching purposes in an undergraduate laboratory. | 0 | Theoretical and Fundamental Chemistry |
Vertebrate ferritin consists of two or three subunits which are named based on their molecular weight: L "light", H "heavy", and M "middle" subunits. The M subunit has only been reported in bullfrogs. In bacteria and archaea, ferritin consists of one subunit type. H and M subunits of eukaryotic ferritin and all subunits of bacterial and archaeal ferritin are H-type and have ferroxidase activity, which is the conversion of iron from the ferrous (Fe) to ferric (Fe) forms. This limits the deleterious reaction which occurs between ferrous iron and hydrogen peroxide known as the Fenton reaction which produces the highly damaging hydroxyl radical. The ferroxidase activity occurs at a diiron binding site in the middle of each H-type subunits. After oxidation of Fe(II), the Fe(III) product stays metastably in the ferroxidase center and is displaced by Fe(II), a mechanism that appears to be common among ferritins of all three domains of life. The light chain of ferritin has no ferroxidase activity but may be responsible for the electron transfer across the protein cage. | 1 | Applied and Interdisciplinary Chemistry |
Availability of IVF in England is determined by Clinical Commissioning Groups (CCGs). The National Institute for Health and Care Excellence (NICE) recommends up to 3 cycles of treatment for people under 40 years old with minimal success conceiving after 2 years of unprotected sex. Cycles will not be continued for people who are older than 40 years. CCGs in Essex, Bedfordshire and Somerset have reduced funding to one cycle, or none, and it is expected that reductions will become more widespread. Funding may be available in "exceptional circumstances" – for example if a male partner has a transmittable infection or one partner is affected by cancer treatment. According to the campaign group Fertility Fairness "at the end of 2014 every CCG in England was funding at least one cycle of IVF". Prices paid by the NHS in England varied between under £3,000 to more than £6,000 in 2014/5. In February 2013, the cost of implementing the NICE guidelines for IVF along with other treatments for infertility was projected to be £236,000 per year per 100,000 members of the population.
IVF increasingly appears on NHS treatments blacklists. In August 2017 five of the 208 CCGs had stopped funding IVF completely and others were considering doing so. By October 2017 only 25 CCGs were delivering the three recommended NHS IVF cycles to eligible people under 40. Policies could fall foul of discrimination laws if they treat same sex couples differently from heterosexual ones. In July 2019 Jackie Doyle-Price said that women were registering with surgeries further away from their own home in order to get around CCG rationing policies.
The Human Fertilisation and Embryology Authority said in September 2018 that parents who are limited to one cycle of IVF, or have to fund it themselves, are more likely choose to implant multiple embryos in the hope it increases the chances of pregnancy. This significantly increases the chance of multiple births and the associated poor outcomes, which would increase NHS costs. The president of the Royal College of Obstetricians and Gynaecologists said that funding 3 cycles was "the most important factor in maintaining low rates of multiple pregnancies and reduce(s) associated complications". | 1 | Applied and Interdisciplinary Chemistry |
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