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Constructed wetlands are not designed for pathogen removal, but have been designed to remove other water quality constituents such as suspended solids, organic matter (biochemical oxygen demand and chemical oxygen demand) and nutrients (nitrogen and phosphorus).
All types of pathogens are expected to be removed in a constructed wetland; however, greater pathogen removal is expected to occur in a subsurface wetland. In a free water surface flow wetland one can expect 1 to 2 log10 reduction of pathogens; however, bacteria and virus removal may be less than 1 log10 reduction in systems that are heavily planted with vegetation. This is because constructed wetlands typically include vegetation which assists in removing other pollutants such as nitrogen and phosphorus. Therefore, the importance of sunlight exposure in removing viruses and bacteria is minimized in these systems.
Removal in a properly designed and operated free water surface flow wetland is reported to be less than 1 to 2 log10 for bacteria, less than 1 to 2 log10 for viruses, 1 to 2 log10 for protozoa, and 1 to 2 log10 for helminths. In subsurface flow wetlands, the expected removal of pathogens is reported to be 1 to 3 log10 for bacteria, 1 to 2 log10 for viruses, 2 log10 for protozoa, and 2 log10 for helminths.
The log10 removal efficiencies reported here can also be understood in terms of the common way of reporting removal efficiencies as percentages: 1 log10 removal is equivalent to a removal efficiency of 90%; 2 log10 = 99%; 3 log10 = 99.9%; 4 log10 = 99.99% and so on. | 1 | Applied and Interdisciplinary Chemistry |
Diaryl-strained-cyclooctynes including dibenzylcyclooctyne (DIBO) have also been used to react with 1,3-nitrones in strain-promoted alkyne-nitrone cycloadditions (SPANC) to yield N-alkylated isoxazolines.
Because this reaction is metal-free and proceeds with fast kinetics (k2 as fast as 60 1/Ms, faster than both the CuAAC or the SPAAC) SPANC can be used for live cell labeling. Moreover, substitution on both the carbon and nitrogen atoms of the nitrone dipole, and acyclic and endocyclic nitrones are all tolerated. This large allowance provides a lot of flexibility for nitrone handle or probe incorporation.
However, the isoxazoline product is not as stable as the triazole product of the CuAAC and the SpAAC, and can undergo rearrangements at biological conditions. Regardless, this reaction is still very useful as it has notably fast reaction kinetics.
The applications of this reaction include labeling proteins containing serine as the first residue: the serine is oxidized to aldehyde with NaIO and then converted to nitrone with p-methoxybenzenethiol, N-methylhydroxylamine and p-ansidine, and finally incubated with cyclooctyne to give a click product. The SPANC also allows for multiplex labeling. | 0 | Theoretical and Fundamental Chemistry |
Another common method of converting between fractional and Cartesian coordinates involves the use of a cell tensor which contains each of the basis vectors of the space expressed in Cartesian coordinates. | 0 | Theoretical and Fundamental Chemistry |
Metal thiolate complexes are commonly prepared by reactions of metal complexes with thiols (RSH), thiolates (RS), and disulfides (RS). The salt metathesis reaction route is common. In this method, an alkali metal thiolate is treated with a transition metal halide to produce an alkali metal halide and the metal thiolate complex:
:LiSCH + CuI → Cu(SCH) + LiI
Lithium tert-butylthiolate reacts with MoCl to give the tetrathiolate complex:
:MoCl + 4 t-BuSLi → Mo(t-BuS) + 4 LiCl
Mo(t-BuS) is a dark red diamagnetic complex that is sensitive to air and moisture. The molybdenum center has a distorted tetrahedral coordination to four sulfur atoms, with overall D symmetry.
Nickelocene and ethanethiol give a dimeric thiolate, one cyclopentadienyl ligand serving as a base:
:2 HSCH + 2 Ni(CH) → [Ni(SCH)(CH)] + 2 CH
Regarding their mechanism of formation from thiols, metal thiolate complexes can arise via deprotonation of thiol complexes. | 0 | Theoretical and Fundamental Chemistry |
To meet the NADPH and ATP demands in the mesophyll and bundle sheath, light needs to be harvested and shared between two distinct electron transfer chains. ATP may be produced in the bundle sheath mainly through cyclic electron flow around Photosystem I, or in the M mainly through linear electron flow depending on the light available in the bundle sheath or in the mesophyll. The relative requirement of ATP and NADPH in each type of cells will depend on the photosynthetic subtype. The apportioning of excitation energy between the two cell types will influence the availability of ATP and NADPH in the mesophyll and bundle sheath. For instance, green light is not strongly adsorbed by mesophyll cells and can preferentially excite bundle sheath cells, or vice versa for blue light. Because bundle sheaths are surrounded by mesophyll, light harvesting in the mesophyll will reduce the light available to reach BS cells. Also, the bundle sheath size limits the amount of light that can be harvested. | 0 | Theoretical and Fundamental Chemistry |
Paucimannosylation has been extensively studied and documented in insects, nematodes and plants over the past decades. The paucimannosidic proteins are constitutively and broadly expressed across tissues in these organisms under normal physiology. It is widely recognised that paucimannosylation is a central component of the glycoproteome in these "lower" organisms. Recently, paucimannosylation was reported to form an unconventional type of protein N-glycosylation in vertebrates. It has been proposed that "higher" species including humans, rodents and other mammals use paucimannosylation in a more tissue- and context-restricted manner in pathophysiological conditions including cancer, pathogen infection, inflammation and stemness. | 1 | Applied and Interdisciplinary Chemistry |
This reaction is a considerable subject area of research with implications for fuel cell design.
Its main utility lies in the removal of carbon monoxide (CO) from the fuel cell's feed gas. CO poisons the catalyst of most low-temperature fuel cells.
Carbon monoxide is often produced as a by-product from steam reforming of hydrocarbons, which produces hydrogen and CO.
It is possible to consume most of the CO by reacting it with steam in the water-gas shift reaction:
:CO + HO H + CO
The water-gas shift reaction can reduce CO to 1% of the feed, with the added benefit of producing more hydrogen, but not eliminate it completely.
To be used in a fuel cell, feed gas must have CO below 10 ppm. | 0 | Theoretical and Fundamental Chemistry |
A nested intronic gene lies within the non-coding intronic region of a larger gene, and occurs relatively frequently, especially in the introns of metazoans and higher eukaryotes. Because only eukaryotic DNA contains intronic regions, this type of gene does not occur in bacteria or archaea.
The human genome contains a relatively high proportion of nested intronic genes. It is predicted to contain at least 158 functional intronic nested genes, with an additional 212 pseudogenes and three snoRNA genes nested in intronic regions. These genes seem to be distributed randomly across all chromosomes, and the majority code for proteins that are functionally unrelated to their host genes. | 1 | Applied and Interdisciplinary Chemistry |
The simultaneous carrying out of glycolysis and gluconeogenesis is an example of a futile cycle, represented by the following equation:
For example, during glycolysis, fructose-6-phosphate is converted to fructose-1,6-bisphosphate in a reaction catalysed by the enzyme phosphofructokinase 1 (PFK-1).
But during gluconeogenesis (i.e. synthesis of glucose from pyruvate and other compounds) the reverse reaction takes place, being catalyzed by fructose-1,6-bisphosphatase (FBPase-1).
Giving an overall reaction of:
That is, hydrolysis of ATP without any useful metabolic work being done. Clearly, if these two reactions were allowed to proceed simultaneously at a high rate in the same cell, a large amount of chemical energy would be dissipated as heat. This uneconomical process has therefore been called a futile cycle. | 1 | Applied and Interdisciplinary Chemistry |
A multiple hearth furnace also known as a vertical calciner, is used for continuous preparation and calcining of materials. | 1 | Applied and Interdisciplinary Chemistry |
The pulsatile flow profile changes its shape depending on the Womersley number
For , viscous forces dominate the flow, and the pulse is considered quasi-static with a parabolic profile.
For , the inertial forces are dominant in the central core, whereas viscous forces dominate near the boundary layer. Thus, the velocity profile gets flattened, and phase between the pressure and velocity waves gets shifted towards the core. | 1 | Applied and Interdisciplinary Chemistry |
The normal and the bigger alkylcycloalkanes are very stable like alkanes and their reactions (cf. radicalic chain reactions) are like alkanes.
The small alkylcycloalkanes - particularly alkylcyclopropane - has a lower stability due to the Bayer tension. They react similar to alkenes, though they don't react with the EA (cf. electrophilic addition), but with the SN2 (cf. nucleophilic substitution) reaction mechanism. These reactions are both ring opening reactions and cleavage reactions. | 0 | Theoretical and Fundamental Chemistry |
A Pythagorean siphon is composed of 4 chambers with 1 chamber in the center that liquids can escape through. As liquid fills up the 4 chambers, the pressure acting on the liquids remains constant and so the level of liquid in each chamber remains the same. Once the liquid reaches the top of the Pythagorean siphon it begins to escape through the central chamber as the effects of gravity take hold. As this process happens, the liquid from both two chambers next to each side of the central chamber forms a seal above the central chamber due to the surface tension of the liquids. Due to this seal, air can then not escape through the central chamber, so the weight of the water in the central chamber forces all the remaining liquid in every chamber to pour out of the Pythagorean siphon. | 1 | Applied and Interdisciplinary Chemistry |
Environmental engineers apply scientific and engineering principles to evaluate if there are likely to be any adverse impacts to water quality, air quality, habitat quality, flora and fauna, agricultural capacity, traffic, ecology, and noise. If impacts are expected, they then develop mitigation measures to limit or prevent such impacts. An example of a mitigation measure would be the creation of wetlands in a nearby location to mitigate the filling in of wetlands necessary for a road development if it is not possible to reroute the road.
In the United States, the practice of environmental assessment was formally initiated on January 1, 1970, the effective date of the National Environmental Policy Act (NEPA). Since that time, more than 100 developing and developed nations either have planned specific analogous laws or have adopted procedure used elsewhere. NEPA is applicable to all federal agencies in the United States. | 1 | Applied and Interdisciplinary Chemistry |
After 125 years of study, 1,3,5-trinitrobenzene yielded a second polymorph. The usual form has the space group Pbca, but in 2004, a second polymorph was obtained in the space group Pca2 when the compound was crystallised in the presence of an additive, trisindane. This experiment shows that additives can induce the appearance of polymorphic forms. | 0 | Theoretical and Fundamental Chemistry |
The phosphatases in the PHLPP family, PHLPP1 and PHLPP2 have been shown to directly dephosphorylate, and therefore inactivate, distinct Akt isoforms, at one of the two critical phosphorylation sites required for activation: Serine473. PHLPP2 dephosphorylates AKT1 and AKT3, whereas PHLPP1 is specific for AKT2 and AKT3. Lack of PHLPP appears to have effects on growth factor-induced Akt phosphorylation. When both PHLPP1 and PHLPP2 are knocked down using siRNA and cells are stimulated using epidermal growth factor, peak Akt phosphorylation at both Serine473 and Threonine308 (the other site required for full Akt activation) is increased dramatically. | 1 | Applied and Interdisciplinary Chemistry |
In the late 1800s, working-class women discovered that lead poisoning caused by ingesting diachylon could cause abortion, or, as they described it, "bring on their period." "Diachylon was readily at hand in every working-class home for use on cuts and sores, as a plaster and for drawing milk away after parturition. Now it was put to a new use. In the words of one doctor, I have reason to suspect that in this district the practice of taking diachylon in the form of pills to bring on miscarriage is far more prevalent among the working-class than is generally supposed.". | 1 | Applied and Interdisciplinary Chemistry |
The inscription is undated, and contains a eulogy of a king named Candra, whose dynasty it does not mention. The identity of this king, and thus the date of the pillar, has been the subject of much debate. The various viewpoints about the identity of the issuer were assembled and analyzed in a volume edited by M. C. Joshi and published in 1989.
The king is now generally identified with the Gupta King Chandragupta II. This identification is based on several points:
* The script and the poetic style of the inscription, which point to a date in the late fourth or early fifth century CE: the Gupta period.
* The inscription describes the king as a devotee of the God Vishnu, and records the erection of a dhvaja ("standard", or pillar) of Vishnu, on a hill called Viṣṇupada ("hill of the footprint of Viṣṇu"). Other Gupta inscriptions also describe Chandragupta II as a Bhagavata (devotee of Vishnu). The names of the places mentioned in the inscription are also characteristic of the Gupta Era. For example, (the Indian Ocean) and (the Bengal region).
* The short name Candra is inscribed on the archer-type gold coins of Chandragupta II, while his full name and titles appear in a separate, circular legend on the coin.
* A royal seal of Chandragupta's wife Dhruvadevi contains the phrase ("Nārāyaṇa, the lord of the illustrious Viṣṇupada").
As the inscription is a eulogy and states that the king has abandoned the earth, there has been some discussion as to whether it is posthumous, i.e. whether King Chandra was dead when the record was created. Dasharatha Sharma (1938) argued that it was non-posthumous. According to B. Chhabra and G. S. Gai, the inscription states that the king's mind is "fixed upon Vishnu with devotion", and therefore, indicates that the king was alive at the time. They theorize that it may have been recorded when Chandragupta II abdicated his throne, and settled down as a vanaprastha (retiree) in Viṣṇupada. | 1 | Applied and Interdisciplinary Chemistry |
The number concentration is defined as the number of entities of a constituent in a mixture divided by the volume of the mixture :
The SI unit is 1/m. | 0 | Theoretical and Fundamental Chemistry |
Bacteria are inoculated on a medium containing sodium citrate and a pH indicator such as bromothymol blue. The medium also contains inorganic ammonium salts, which are utilized as sole source of nitrogen. Use of citrate involves the enzyme citrate lyase, which breaks down citrate to oxaloacetate and acetate. Oxaloacetate is further broken down to pyruvate and carbon dioxide (CO). Production of sodium bicarbonate (NaHCO) as well as ammonia (NH) from the use of sodium citrate and ammonium salts results in alkaline pH. This results in a change of the medium's color from green (neutral) to blue (alkaline).
Bacterial colonies are picked up from a straight wire and inoculated into slope of Simmons citrate agar and incubated overnight at 37 °C. Inoculating from a broth culture is not recommended because the inoculum would be too heavy. If the organism has the ability to use citrate, the medium usually changes its color from green to blue, though growth on the medium even without colour change is considered a positive result. An observation of no growth is a negative result.
Examples:
* Escherichia coli: Negative
* Klebsiella pneumoniae: Positive
* Frateuria aurantia: Positive | 0 | Theoretical and Fundamental Chemistry |
The most widely used technique to monitor the dispersion state of a product, and to identify and quantify destabilization phenomena, is multiple light scattering coupled with vertical scanning. This method, known as turbidimetry, is based on measuring the fraction of light that, after being sent through the sample, it backscattered by the colloidal particles. The backscattering intensity is directly proportional to the average particle size and volume fraction of the dispersed phase. Therefore, local changes in concentration caused by sedimentation or creaming, and clumping together of particles caused by aggregation, are detected and monitored. These phenomena are associated with unstable colloids.
Dynamic light scattering can be used to detect the size of a colloidal particle by measuring how fast they diffuse. This method involves directing laser light towards a colloid. The scattered light will form an interference pattern, and the fluctuation in light intensity in this pattern is caused by the Brownian motion of the particles. If the apparent size of the particles increases due to them clumping together via aggregation, it will result in slower Brownian motion. This technique can confirm that aggregation has occurred if the apparent particle size is determined to be beyond the typical size range for colloidal particles. | 0 | Theoretical and Fundamental Chemistry |
Suggested in 1919, the centrifugal process was first successfully performed in 1934. American scientist Jesse Beams and his team at the University of Virginia developed the process by separating two chlorine isotopes through a vacuum ultracentrifuge. It was one of the initial isotopic separation means pursued during the Manhattan Project, more particularly by Harold Urey and Karl P. Cohen, but research was discontinued in 1944 as it was felt that the method would not produce results by the end of the war, and that other means of uranium enrichment (gaseous diffusion and electromagnetic separation) had a better chance of success in the short term. This method was successfully used in the Soviet nuclear program, making the Soviet Union the most effective supplier of enriched uranium. Franz Simon, Rudolf Peierls, Klaus Fuchs and Nicholas Kurti made important contributions to the centrifugal process. Paul Dirac also made important theoretical contributions to the centrifugal process during World War II. Dirac developed the fundamental theory of separation processes that underlies the design and analysis of modern uranium enrichment plants.
In the long term, especially with the development of the Zippe-type centrifuge, the gas centrifuge has become a very economical mode of separation, using considerably less energy than other methods and having numerous other advantages.
Research in the physical performance of centrifuges was carried out by the Pakistani scientist Abdul Qadeer Khan in the 1970s–80s, using vacuum methods for advancing the role of centrifuges in the development of nuclear fuel for Pakistan's atomic bomb. Many of the theorists working with Khan were unsure that either gaseous and enriched uranium would be feasible on time. One scientist recalled: "No one in the world has used the [gas] centrifuge method to produce military-grade uranium.... This was not going to work. He was simply wasting time." In spite of skepticism, the program was quickly proven to be feasible. Enrichment via centrifuge has been used in experimental physics, and the method was smuggled to at least three different countries by the end of the 20th century. | 0 | Theoretical and Fundamental Chemistry |
A caesium-137 capsule went missing from a steam power plant in Prachin Buri province, Thailand on 23 February 2023, triggering a search by officials from Thailand's Office of Atoms for Peace (OAP) and the Prachin Buri provincial administration. However, the Thai public was not notified until 14 March.
On 20 March, the Secretary-General of the OAP and the governor of Prachin Buri held a press conference stating that they had found caesium-137 contaminated furnace dust at a steel melting plant in Kabin Buri district. | 0 | Theoretical and Fundamental Chemistry |
Human proteins containing this domain include:
* ABL1; ABL2
* BCAR3; BLK; BLNK; BMX; BTK
* CHN2; CISH; CRK; CRKL; CSK
* DAPP1
* FER; FES; FGR; FRK; FYN
* GRAP; GRAP2; GRB10; GRB14; GRB2; GRB7
* HCK; HSH2D
* INPP5D; INPPL1; ITK; JAK2; LCK; LCP2; LYN
* MATK; NCK1; NCK2
* PIK3R1; PIK3R2; PIK3R3; PLCG1; PLCG2; PTK6; PTPN11; PTPN6; RASA1
* SH2B1; SH2B2; SH2B3; SH2D1A; SH2D1B; SH2D2A; SH2D3A; SH2D3C; SH2D4A; SH2D4B; SH2D5; SH2D6; SH3BP2; SHB; SHC1; SHC3; SHC4; SHD; SHE
* SLA; SLA2
* SOCS1; SOCS2; SOCS3; SOCS4; SOCS5; SOCS6; SOCS7
* SRC; SRMS
* STAT1; STAT2; STAT3; STAT4; STAT5A; STAT5B; STAT6
* SUPT6H; SYK
* TEC; TENC1; TNS; TNS1; TNS3; TNS4; TXK
* VAV1; VAV2; VAV3
* YES1; ZAP70 | 1 | Applied and Interdisciplinary Chemistry |
It has been shown by Fulda et al. that the naturally occurring compound resveratrol (a polyphenol found in grapes and red wine) can be used as a sensitizer for anticancer drug-induced apoptosis by the action of causing cell cycle arrest. This cell cycle arrest causes a dramatic decline in survivin levels in the cells, as it is known from the literature that survivin expression is highly linked with the cell cycle phase state. Thus, the decrease in survivin, which is a contributing factor to chemotherapy resistance and apoptosis induction therapies, would render the cancer cells more prone to such cancer treatments. Fulda et al. have demonstrated the benefits of resveratrol through a series of experiments. First, the authors of the paper tested the intrinsic cytotoxic effects of resveratrol. They found that it induced moderate apoptosis levels only in SHEP neuroblastoma cells. After, they tested resveratrol in combination with several different known anticancer agents. They found a consistent increase in the level of apoptosis induced by the drugs when resveratrol was also present. Moreover, they varied the order with which either the drugs or resveratrol was introduced to the cancer cells to determine whether the sequence of treatment had any important effect. It was found that the highest levels of apoptosis induction were observed when resveratrol was added prior to anticancer drug treatment. Next, the authors tested for any differential sensitivity to apoptosis linked to the phase of the cell cycle the cells were in. Analysis by flow cytometry revealed an accumulation of cells in S phase upon treatment with resveratrol. The cells were also halted in different phases of the cell cycle using special compounds and then treated with the anticancer drugs. They found that cells halted in S phase were significantly more sensitive to the cytotoxic effects of the drugs.
To determine the involvement of survivin in resveratrol-mediated sensitization, the authors decided to test whether downregulation of the specific survivin protein expression would confer a similar effect on the phenotype of resveratrol-treated cells. In terms of seeing at which level resveratrol worked, they did a northern blot and found that resveratrol treatment resulted in a decrease in survivin mRNA levels, thus implying resveratrol's inhibitory action at the transcriptional level. To further see whether survivin played a key role in sensitization of the cancer cells to cytotoxic drugs, survivin antisense oligonucleotides were used to knock down any survivin mRNA, and, thus, its possibility to be translated is also eliminated. siRNAs for survivin are complements in sequence to the mRNA sequence encoding survivin. When these siRNAs for survivin are introduced into cells, they will bind to the respective complementary mRNA and, thus, prevent its translation since the mRNA is now impeded from proper physical interaction with the translational machinery. In this way, the siRNAs for survivin effectively downregulates survivin expression level in the cell. Cells treated with antisense oligonucleotides for survivin showed similar sensitization to cytotoxic drugs as cells treated with resveratrol, which offers support for the mechanism of action of resveratrol. | 1 | Applied and Interdisciplinary Chemistry |
In plants and some algae, another enzyme, RuBisCO activase (Rca, , ), is required to allow the rapid formation of the critical carbamate in the active site of RuBisCO. This is required because ribulose 1,5-bisphosphate (RuBP) binds more strongly to the active sites of RuBisCO when excess carbamate is present, preventing processes from moving forward. In the light, RuBisCO activase promotes the release of the inhibitory (or — in some views — storage) RuBP from the catalytic sites of RuBisCO. Activase is also required in some plants (e.g., tobacco and many beans) because, in darkness, RuBisCO is inhibited (or protected from hydrolysis) by a competitive inhibitor synthesized by these plants, a substrate analog 2-carboxy-D-arabitinol 1-phosphate (CA1P). CA1P binds tightly to the active site of carbamylated RuBisCO and inhibits catalytic activity to an even greater extent. CA1P has also been shown to keep RuBisCO in a conformation that is protected from proteolysis. In the light, RuBisCO activase also promotes the release of CA1P from the catalytic sites. After the CA1P is released from RuBisCO, it is rapidly converted to a non-inhibitory form by a light-activated CA1P-phosphatase. Even without these strong inhibitors, once every several hundred reactions, the normal reactions with carbon dioxide or oxygen are not completed; other inhibitory substrate analogs are still formed in the active site. Once again, RuBisCO activase can promote the release of these analogs from the catalytic sites and maintain the enzyme in a catalytically active form. However, at high temperatures, RuBisCO activase aggregates and can no longer activate RuBisCO. This contributes to the decreased carboxylating capacity observed during heat stress. | 0 | Theoretical and Fundamental Chemistry |
This parameter is often used in biomechanics, when describing the motion of joints of the body. For any period of time, joint motion can be seen as the movement of a single point on one articulating surface with respect to the adjacent surface (usually distal with respect to proximal). The total translation and rotations along the path of motion can be defined as the time integrals of the instantaneous translation and rotation velocities at the IHA for a given reference time.
In any single plane, the path formed by the locations of the moving instantaneous axis of rotation (IAR) is known as the centroid, and is used in the description of joint motion. | 0 | Theoretical and Fundamental Chemistry |
Aluminothermic reactions are exothermic chemical reactions using aluminium as the reducing agent at high temperature. The process is industrially useful for production of alloys of iron. The most prominent example is the thermite reaction between iron oxides and aluminium to produce iron itself:
: FeO + 2 Al → 2 Fe + AlO
This specific reaction is however not relevant to the most important application of aluminothermic reactions, the production of ferroalloys. For the production of iron, a cheaper reducing agent, coke, is used instead via the carbothermic reaction. | 1 | Applied and Interdisciplinary Chemistry |
An interesting way of achieving chiral distinction on a CSP is the use of selectors with chiral cavity. These chiral selectors are attached to the stationary phase support material. In this category, there are basically three types of cavity chiral selectors namely cyclodextrins, crown ethers and macrocyclic glycopeptide antibiotics. Among these cyclodextrin based CSP is popular. In this type of CSPs the enantioselective guest-host interaction governs the chiral distinction. | 0 | Theoretical and Fundamental Chemistry |
Most biofilters use media such as sand, crushed rock, river gravel, or some form of plastic or ceramic material shaped as small beads and rings. | 1 | Applied and Interdisciplinary Chemistry |
New NA inhibitor analogues were synthesized, based on Zanamivir, Oseltamivir and Peramivir, with rational structure-based drug design and can be categorized into four groups. | 1 | Applied and Interdisciplinary Chemistry |
Currently the most important application is due to the special magnetic properties of some ferromagnetic metallic glasses. The low magnetization loss is used in high efficiency transformers (amorphous metal transformer) at line frequency and some higher frequency transformers. Amorphous steel is a very brittle material which makes it difficult to punch into motor laminations. Also electronic article surveillance (such as theft control passive ID tags,) often uses metallic glasses because of these magnetic properties.
A commercial amorphous alloy, Vitreloy 1 (41.2% Zr, 13.8% Ti, 12.5% Cu, 10% Ni, and 22.5% Be), was developed at Caltech, as a part of Department of Energy and NASA research of new aerospace materials.
Ti-based metallic glass, when made into thin pipes, have a high tensile strength of , elastic elongation of 2% and high corrosion resistance. Using these properties, a Ti–Zr–Cu–Ni–Sn metallic glass was used to improve the sensitivity of a Coriolis flow meter. This flow meter is about 28-53 times more sensitive than conventional meters, which can be applied in fossil-fuel, chemical, environmental, semiconductor and medical science industry.
Zr-Al-Ni-Cu based metallic glass can be shaped into pressure sensors for automobile and other industries, and these sensors are smaller, more sensitive, and possess greater pressure endurance compared to conventional stainless steel made from cold working. Additionally, this alloy was used to make the world's smallest geared motor with diameter to be produced and sold at the time. | 1 | Applied and Interdisciplinary Chemistry |
In chemistry, a ladder polymer is a type of double stranded polymer with the connectivity of a ladder. In a typical one-dimensional polymer, e.g. polyethylene and polysiloxanes, the monomers form two bonds, giving a chain. In a ladder polymer the monomers are interconnected by four bonds. Inorganic ladder polymers are found in synthetic and natural settings. Ladder polymers are a special case of cross-linked polymers because the crosslinks exist only with pairs of chains.
According to one definition, a ladder polymer, adjacent rings have two or more atoms in common. | 0 | Theoretical and Fundamental Chemistry |
In 2004, Panek and his co-workers reported an approach which takes advantage of chiral crotylsilane-based C-C bond construction methodology to obtain the absolute stereochemistry of the three subunits of (+)-discodermolide. One of the key features of the Paterson approach is the utilization of hydrozirconation-cross-coupling methodology for the construction of C13-C14 (Z)-olefin. Acetate aldol reaction with high levels of 1,5-anti stereo induction and palladium-mediated sp2-sp3 cross coupling reaction are used to connect subunits. The Panek synthesis of (+)-discodermolide has an overall yield of 2.1% with a longest linear sequence of 27 steps and 42 total steps. | 0 | Theoretical and Fundamental Chemistry |
In soil mechanics and petroleum engineering the water saturation or degree of saturation, , is defined as
where is the porosity, in terms of the volume of void or pore space and the total volume of the substance . Values of S can range from 0 (dry) to 1 (saturated). In reality, S never reaches 0 or 1 - these are idealizations for engineering use.
The normalized water content, , (also called effective saturation or ) is a dimensionless value defined by van Genuchten as:
where is the volumetric water content; is the residual water content, defined as the water content for which the gradient becomes zero; and, is the saturated water content, which is equivalent to porosity, . | 0 | Theoretical and Fundamental Chemistry |
Other challenges of the cyanosulfidic prebiotic synthesis approach is that the reductant, sulfide, has low solubility in water except in alkaline conditions and the main catalyst, copper, has a relatively low abundance in Earth’s crust. To address these problems, an alternative scheme for prebiotic systems chemistry called cyanosulfitic prebiotic synthesis has been proposed. These set of reactions relies on sulfite instead of sulfide, and ferrocyanide to catalyze reactions when exposed to ultraviolet light. The products of these reactions rely on similar chemistry to cyanofidic mechanisms such as reductive homologation and produce similar products such as amino acid precursors as well as sugars and hydroxy acids. Both sulfite (from sulfur dioxide released by volcanos) and ferrous iron (FeII) are hypothesized to have been present in high quantities on the early Earth, suggesting that this is potentially a much for feasible set of reactions. | 0 | Theoretical and Fundamental Chemistry |
Levetiracetam is available as regular and extended release oral formulations and as intravenous formulations.
The immediate release tablet has been available as a generic in the United States since 2008, and in the UK since 2011. The patent for the extended release tablet will expire in 2028.
The branded version Keppra is manufactured by UCB Pharmaceuticals S.A.
In 2015, Aprecia's 3D-printed orally disintegrating tablet form of the drug was approved by the FDA, under the trade name Spritam. Some have said that the drug has been improved by 3D printing, as the formula used now has improved disintegration properties. | 0 | Theoretical and Fundamental Chemistry |
Many metal foam manufacturing techniques are accomplished by the introduction of a gaseous phase into a precursor matrix, which can occur in either molten metal or a powdered metal form. Due to titanium's high melting point (1670 °C) and high chemical affinity with oxygen, nitrogen, carbon and hydrogen (which dissolve rapidly either in liquid or solid titanium at a temperature above 400 °C), solid-state processes based on powder densification are the preferred method of fabrication.
Processing methods must also be designed to avoid exposure to air or moisture; vacuum or inert gas sintering processes are usually sufficient for preventing contamination. | 0 | Theoretical and Fundamental Chemistry |
The discoverer of the inner sphere mechanism was Henry Taube, who was awarded the Nobel Prize in Chemistry in 1983 for his pioneering studies. A particularly historic finding is summarized in the abstract of the seminal publication.
)Cl is reduced by Cr in M [meaning 1 M] HClO, 1 Cl appears attached to Cr for each Cr(III) which is formed or Co(III) reduced. When the reaction is carried on in a medium containing radioactive Cl, the mixing of the Cl attached to Cr(III) with that in solution is less than 0.5%. This experiment shows that transfer of Cl to the reducing agent from the oxidizing agent is direct…"</blockquote>
The paper and the excerpt above can be described with the following equation:
:[CoCl(NH)] + [Cr(HO)] → [Co(NH)(HO)] + [CrCl(HO)]
The point of interest is that the chloride that was originally bonded to the cobalt, the oxidant, becomes bonded to chromium, which in its +3 oxidation state, forms kinetically inert bonds to its ligands. This observation implies the intermediacy of the bimetallic complex [Co(NH)(μ-Cl)Cr(HO)], wherein "μ-Cl" indicates that the chloride bridges between the Cr and Co atoms, serving as a ligand for both. This chloride serves as a conduit for electron flow from Cr(II) to Co(III), forming Cr(III) and Co(II). | 0 | Theoretical and Fundamental Chemistry |
A wide range of biological changes may follow the irradiation of animals. These vary from rapid death following high doses of penetrating whole-body radiation, to essentially normal lives for a variable period of time until the development of delayed radiation effects, in a portion of the exposed population, following low dose exposures.
The unit of actual exposure is the röntgen, defined in ionisations per unit volume of air. All ionisation based instruments (including geiger counters and ionisation chambers) measure exposure. However, effects depend on the energy per unit mass, not the exposure measured in air. A deposit of 1 joule per kilogram has the unit of 1 gray (Gy). For 1 MeV energy gamma rays, an exposure of 1 röntgen in air produces a dose of about 0.01 gray (1 centigray, cGy) in water or surface tissue. Because of shielding by the tissue surrounding the bones, the bone marrow only receives about 0.67 cGy when the air exposure is 1 röntgen and the surface skin dose is 1 cGy. Some lower values reported for the amount of radiation that would kill 50% of personnel (the ) refer to bone marrow dose, which is only 67% of the air dose. | 0 | Theoretical and Fundamental Chemistry |
SFRS1 is a proto-oncogene, and thus ASF/SF2 can act as an oncoprotein; it can alter the splicing patterns of crucial cell cycle regulatory genes and suppressor genes. ASF/SF2 controls the splicing of various tumor suppressor genes, kinases, and kinase receptors, all of which have the potential to be alternatively spliced into oncogenic isoforms. As such, ASF/SF2 is an important target for cancer therapy, as it is over-expressed in many tumors.
Modifications and defects in the alternative splicing pathway are associated with a variety of human diseases.
ASF/SF2 is involved in the replication of HIV-1, as HIV-1 needs a delicate balance of spliced and unspliced forms of its viral DNA. ASF/SF2 action in the replication of HIV-1 is a potential target for HIV therapy. ASF/SF2 is also implicated in the production of T cell receptors in Systemic Lupus Erythematosus, altering specific chain expression in T cell receptors through alternative splicing. | 1 | Applied and Interdisciplinary Chemistry |
Silver(I) forms , a rare example of a tetrahedral aquo complex. Palladium(II) and platinum(II) were once thought to form square planar aquo complexes. | 0 | Theoretical and Fundamental Chemistry |
A further occurrence of ordered columnar arrangement on the macroscale are foam structures confined inside a glass tube. They can be realised experimentally with equal-sized soap bubbles inside a glass tube, produced by blowing air of constant gas flow through a needle dipped in a surfactant solution. By putting the resulting foam column under forced drainage (feeding it with surfactant solution from the top), the foam can be adjusted to either a dry (bubbles shaped as polyhedrons) or wet (spherical bubbles) structure.
Due to this simple experimental set-up, many columnar structures have been discovered and investigated in the context of foams with experiments as well as simulation. Many simulations have been carried out using the Surface Evolver to investigate dry structure or the hard sphere model for the wet limit where the bubbles are spherical.
In the zigzag structure the bubbles are stacked on top of each other in a continuous w-shape. For this particular structure a moving interface with increasing liquid fraction was reported by Hutzler et al. in 1997. This included an unexpected 180° twist interface, whose explanation is still lacking.
The first experimental observation of a line-slip structure was discovered by Winkelmann et al. in a system of bubbles.
Further discovered structures include complex structures with internal spheres/foam cells. Some dry foam structures with interior cells were found to consist of a chain of pentagonal dodecahedra or Kelvin cells in the centre of the tube. For many more arrangements of this type, it was observed that the outside bubble layer is ordered, with each internal layer resembling a different, simpler columnar structure by using X-ray tomography. | 0 | Theoretical and Fundamental Chemistry |
Water supply networks usually represent the majority of assets of a water utility. Systematic documentation of maintenance works using a computerized maintenance management system (CMMS) is a key to a successful operation of a water utility. | 1 | Applied and Interdisciplinary Chemistry |
It was not until the end of the 18th century that Joseph Priestley accidentally discovered the ability of plants to "restore" air that had been "injured" by the burning of a candle. He followed up on the experiment by showing that air "restored" by vegetation was "not at all inconvenient to a mouse." He was later awarded a medal for his discoveries that "...no vegetable grows in vain... but cleanses and purifies our atmosphere." Priestley's experiments were further evaluated by Jan Ingenhousz, a Dutch physician, who then showed that the "restoration" of air only worked while in the presence of light and green plant parts. | 0 | Theoretical and Fundamental Chemistry |
There are many ways in which humans may limit the viability of a potential biosignature. The resolution of a telescope becomes important when vetting certain false-positive mechanisms, and many current telescopes do not have the capabilities to observe at the resolution needed to investigate some of these. In addition, probes and telescopes are worked on by huge collaborations of scientists with varying interests. As a result, new probes and telescopes carry a variety of instruments that are a compromise to everyone's unique inputs. For a different type of scientist to detect something unrelated to biosignatures, a sacrifice may have to be made in the capability of an instrument to search for biosignatures. | 1 | Applied and Interdisciplinary Chemistry |
A common concept in materials science is that, at ambient conditions, smaller features (like grain size or absolute size) generally lead to stronger materials (see Hall-Petch strengthening, Weibull statistics). However, due to the high-level of porosity in the dealloyed materials, their strengths and stiffnesses are relatively low compared to the bulk counterparts. The decrease in strength due to porosity can be described with the Gibson-Ashby (GA) relations, which give the yield strength and Young's modulus of a foam according to the following equations:
where and <math>C_E
and <math>n_E
is the relative density of the foam.
The GA relations can be used to estimate the strength and stiffness of a given dealloyed, porous material, but more extensive study has revealed an additional factor: ligament size. When the ligament diameter is greater than 100 nm, increasing ligament size leads to greater agreement between GA predictions and experimental measurements of yield stress and Young's modulus. However, when the ligament size is under 100 nm, which is very common in many dealloying processes, there is an addition to the GA strength that looks similar to Hall-Petch strengthening of bulk polycrystalline metals (i.e., the yield stress increases with the inverse square root of grain size). Combining this relationship with the GA relation from before, an expression for the yield stress of dealloyed materials with ligaments smaller than 100 nm can be determined:
where A and m are empirically determined constants, and is the ligament size. The represents the Hall-Petch-like contribution.
There are two theories for why this increase in strength occurs: 1) dislocations are less common in smaller sample volumes, so deformation requires activation of sources (which is a more difficult process), or 2) dislocations pile-up, which strengthens the material. Either way, there would be significant surface and small volume effects in the ligaments <100 nm, which lead to this increase in yield stress. A relationship between ligament size and Young's modulus has not been studied past the GA relation.
Occasionally, the metastable nature of these materials means that ligaments in the structure may "pinch off" due to surface diffusion, which decreases the connectivity of the structure, and reduces the strength of the dealloyed material past what would be expected from simply porosity (as predicted by the Gibson-Ashby relations). | 1 | Applied and Interdisciplinary Chemistry |
Active targeting of drug-loaded nanoparticles enhances the effects of passive targeting to make the nanoparticle more specific to a target site. There are several ways that active targeting can be accomplished. One way to actively target solely diseased tissue in the body is to know the nature of a receptor on the cell for which the drug will be targeted to. Researchers can then utilize cell-specific ligands that will allow the nanoparticle to bind specifically to the cell that has the complementary receptor. This form of active targeting was found to be successful when utilizing transferrin as the cell-specific ligand. The transferrin was conjugated to the nanoparticle to target tumor cells that possess transferrin-receptor mediated endocytosis mechanisms on their membrane. This means of targeting was found to increase uptake, as opposed to non-conjugated nanoparticles. Another cell-specific ligand is the RGD motif which binds to the integrin αvβ3. This integrin is upregulated in tumor and activated endothelial cells. Conjugation of RGD to chemotherapeutic-loaded nanoparticles has been shown to increase cancer cell uptake in vitro and therapeutic efficacy in vivo.
Active targeting can also be achieved by utilizing magnetoliposomes, which usually serves as a contrast agent in magnetic resonance imaging. Thus, by grafting these liposomes with a desired drug to deliver to a region of the body, magnetic positioning could aid with this process.
Furthermore, a nanoparticle could possess the capability to be activated by a trigger that is specific to the target site, such as utilizing materials that are pH responsive. Most of the body has a consistent, neutral pH. However, some areas of the body are naturally more acidic than others, and, thus, nanoparticles can take advantage of this ability by releasing the drug when it encounters a specific pH. Another specific triggering mechanism is based on the redox potential. One of the side effects of tumors is hypoxia, which alters the redox potential in the vicinity of the tumor. By modifying the redox potential that triggers the payload release the vesicles can be selective to different types of tumors.
By utilizing both passive and active targeting, a drug-loaded nanoparticle has a heightened advantage over a conventional drug. It is able to circulate throughout the body for an extended period of time until it is successfully attracted to its target through the use of cell-specific ligands, magnetic positioning, or pH responsive materials. Because of these advantages, side effects from conventional drugs will be largely reduced as a result of the drug-loaded nanoparticles affecting only diseased tissue. However, an emerging field known as nanotoxicology has concerns that the nanoparticles themselves could pose a threat to both the environment and human health with side effects of their own. Active targeting can also be achieved through peptide based drug targeting system. | 1 | Applied and Interdisciplinary Chemistry |
Microfluidic structures include micropneumatic systems, i.e. microsystems for the handling of off-chip fluids (liquid pumps, gas valves, etc.), and microfluidic structures for the on-chip handling of nanoliter (nl) and picoliter (pl) volumes. To date, the most successful commercial application of microfluidics is the inkjet printhead. Additionally, microfluidic manufacturing advances mean that makers can produce the devices in low-cost plastics and automatically verify part quality.
Advances in microfluidics technology are revolutionizing molecular biology procedures for enzymatic analysis (e.g., glucose and lactate assays), DNA analysis (e.g., polymerase chain reaction and high-throughput sequencing), proteomics, and in chemical synthesis. The basic idea of microfluidic biochips is to integrate assay operations such as detection, as well as sample pre-treatment and sample preparation on one chip.
An emerging application area for biochips is clinical pathology, especially the immediate point-of-care diagnosis of diseases. In addition, microfluidics-based devices, capable of continuous sampling and real-time testing of air/water samples for biochemical toxins and other dangerous pathogens, can serve as an always-on "bio-smoke alarm" for early warning.
Microfluidic technology has led to the creation of powerful tools for biologists to control the complete cellular environment, leading to new questions and discoveries. Many diverse advantages of this technology for microbiology are listed below:
* General single cell studies including growth
* Cellular aging: microfluidic devices such as the "mother machine" allow tracking of thousands of individual cells for many generations until they die
* Microenvironmental control: ranging from mechanical environment to chemical environment
* Precise spatiotemporal concentration gradients by incorporating multiple chemical inputs to a single device
* Force measurements of adherent cells or confined chromosomes: objects trapped in a microfluidic device can be directly manipulated using optical tweezers or other force-generating methods
* Confining cells and exerting controlled forces by coupling with external force-generation methods such as Stokes flow, optical tweezer, or controlled deformation of the PDMS (Polydimethylsiloxane) device
* Electric field integration
* Plant on a chip and plant tissue culture
* Antibiotic resistance: microfluidic devices can be used as heterogeneous environments for microorganisms. In a heterogeneous environment, it is easier for a microorganism to evolve. This can be useful for testing the acceleration of evolution of a microorganism / for testing the development of antibiotic resistance.
Some of these areas are further elaborated in the sections below: | 1 | Applied and Interdisciplinary Chemistry |
Knot theory which categorises chain entanglements. The usage of knot theory is limited to a small percentage of proteins as most of them are unknot. | 0 | Theoretical and Fundamental Chemistry |
Lead and LBE coolant are more corrosive to steel than sodium, and this puts an upper limit on the velocity of coolant flow through the reactor due to safety considerations. Furthermore, the higher melting points of lead and LBE (327 °C and 123.5 °C respectively) may mean that solidification of the coolant may be a greater problem when the reactor is operated at lower temperatures.
Finally, upon neutron radiation bismuth-209, the main isotope of bismuth present in LBE coolant, undergoes neutron capture and subsequent beta decay, forming polonium-210, a potent alpha emitter. The presence of radioactive polonium in the coolant would require special precautions to control alpha contamination during refueling of the reactor and handling components in contact with LBE. | 1 | Applied and Interdisciplinary Chemistry |
Ionic potential is the ratio of the electrical charge (z) to the radius (r) of an ion.
As such, this ratio is a measure of the charge density at the surface of the ion; usually the denser the charge, the stronger the bond formed by the ion with ions of opposite charge.
The ionic potential gives an indication of how strongly, or weakly, the ion will be electrostatically attracted by ions of opposite charge; and to what extent the ion will be repelled by ions of the same charge.
Victor Moritz Goldschmidt, the father of modern geochemistry found that the behavior of an element in its environment could be predicted from its ionic potential and illustrated this with a diagram (plot of the bare ionic radius as a function of the ionic charge). For instance, the solubility of dissolved iron is highly dependent on its redox state. with a lower ionic potential than is much more soluble because it exerts a weaker interaction force with ion present in water and exhibits a less pronounced trend to hydrolysis and precipitation. Under reducing conditions Fe(II) can be present at relatively high concentration in anoxic water, similar to these encountered for other divalent species such as and . However, once anoxic ground water is pumped from a deep well and is discharged to the surface, it enters in contact with atmospheric oxygen. Then is easily oxidized to and this latter rapidly hydrolyzes and precipitates because of its lower solubility due to a higher z/r ratio.
Millot (1970) also illustrated the importance of the ionic potential of cations to explain the high, or the low, solubility of minerals and the expansive behaviour (swelling/shrinking) of clay materials.
The ionic potential of the different cations (, , and ) present in the interlayer of clay minerals also contribute to explain their swelling/shrinking properties. The more hydrated cations such as and are responsible for the swelling of smectite while the less hydrated and cause the collapse of the interlayer. In illite, the interlayer is totally collapsed because of the presence of the poorly hydrated .
Ionic potential is also a measure of the polarising power of a cation.
Ionic potential could be used as a general criterion for the selection of efficient adsorbents for toxic elements. | 0 | Theoretical and Fundamental Chemistry |
Aromatic compounds are subject to electrophilic halogenation:
This kind of reaction typically works well for chlorine and bromine. Often a Lewis acidic catalyst is used, such as ferric chloride. Many detailed procedures are available.
Because fluorine is so reactive, other methods, such as the Balz–Schiemann reaction, are used to prepare fluorinated aromatic compounds. | 0 | Theoretical and Fundamental Chemistry |
Dechelation (or de-chelation) is a reverse process of the chelation in which the chelating agent is recovered by acidifying solution with a mineral acid to form a precipitate. | 0 | Theoretical and Fundamental Chemistry |
Temperature in the test section:
with = 330 K: = 70 K at = 4
The velocity range is limited by reservoir temperature | 1 | Applied and Interdisciplinary Chemistry |
In 1920 Armstrong and Hilditch first proposed the associative mechanism. In this mechanism CO and HO are adsorbed onto the surface of the catalyst, followed by formation of an intermediate and the desorption of H and CO. In general, HO dissociates onto the catalyst to yield adsorbed OH and H. The dissociated water reacts with CO to form a carboxyl or formate intermediate. The intermediate subsequently dehydrogenates to yield CO and adsorbed H. Two adsorbed H atoms recombine to form H.
There has been significant controversy surrounding the kinetically relevant intermediate during the associative mechanism. Experimental studies indicate that both intermediates contribute to the reaction rate over metal oxide supported transition metal catalysts. However, the carboxyl pathway accounts for about 90% of the total rate owing to the thermodynamic stability of adsorbed formate on the oxide support. The active site for carboxyl formation consists of a metal atom adjacent to an adsorbed hydroxyl. This ensemble is readily formed at the metal-oxide interface and explains the much higher activity of oxide-supported transition metals relative to extended metal surfaces. The turn-over-frequency for the WGSR is proportional to the equilibrium constant of hydroxyl formation, which rationalizes why reducible oxide supports (e.g. CeO) are more active than irreducible supports (e.g. SiO) and extended metal surfaces (e.g. Pt). In contrast to the active site for carboxyl formation, formate formation occurs on extended metal surfaces. The formate intermediate can be eliminated during the WGSR by using oxide-supported atomically dispersed transition metal catalysts, further confirming the kinetic dominance of the carboxyl pathway. | 0 | Theoretical and Fundamental Chemistry |
Devardas alloy (Copper/Aluminium/Zinc) is a reducing agent. When reacted with nitrate in sodium hydroxide solution, ammonia is liberated. The ammonia formed may be detected by its characteristic odor, and by damp red litmus papers turning blue, signalling that it is an alkali — very few gases other than ammonia evolved from wet chemistry are alkaline.
:3 + 8 Al + 5 + 18 → 3 + 8
Aluminium is the reducing agent in this reaction that will occur. | 0 | Theoretical and Fundamental Chemistry |
Contact X-ray brachytherapy (also called "CXB", "electronic brachytherapy" or the "Papillon Technique") is a type of radiation therapy using low energy (50 kVp) kilovoltage X-rays applied directly to the tumor to treat rectal cancer. The process involves edoscopic examination first to identify the tumour in the rectum and then inserting treatment applicator on the tumour through the anus into the rectum and placing it against the cancerous tissue. Finally, treatment tube is inserted into the applicator to deliver high doses of X-rays (30Gy) emitted directly onto the tumor at two weekly intervals for three times over four weeks period. It is typically used for treating early rectal cancer in patients who may not be candidates for surgery. A 2015 NICE review found the main side effect to be bleeding that occurred in about 38% of cases, and radiation-induced ulcer which occurred in 27% of cases. | 0 | Theoretical and Fundamental Chemistry |
Historically, LSD was distributed not for profit, but because those who made and distributed it truly believed that the psychedelic experience could be beneficial for humanity. A limited number of chemists, probably fewer than a dozen, are believed to have manufactured nearly all of the illicit LSD available in the United States. The best known of these is undoubtedly Augustus Owsley Stanley III, usually known simply as Owsley or Bear.
The former chemistry student set up a private LSD lab in the mid-60s in San Francisco and supplied the LSD consumed at the famous Acid Test parties held by Ken Kesey and his Merry Pranksters, as well as the Human Be-In in San Francisco in January 1967 and the Monterey International Pop Festival in June 1967. He also had close social connections with the Grateful Dead, Jefferson Airplane, and Big Brother and The Holding Company, regularly supplying them with LSD and working as their live sound engineer, creating many tapes of these groups in concert. Owsleys LSD activities—immortalized by Steely Dan in their song "Kid Charlemagne"—ended with his arrest at the end of 1967, but some other manufacturers most likely operated continuously for 30 years or more. Announcing Owsleys first bust in 1966, The San Francisco Chronicle headline "LSD Millionaire Arrested" inspired the rare Grateful Dead song "Alice D. Millionaire".
Owsley associated with other early LSD producers, Tim Scully and Nicholas Sand. | 1 | Applied and Interdisciplinary Chemistry |
** Nanotubes synthesized hollow carbon molecules and determined their crystal structure for the first time in the soot of arc discharge at NEC, by Japanese researcher Sumio Iijima.
** August — Nanotubes discovered in CVD by Al Harrington and Tom Maganas of Maganas Industries, leading to development of a method to synthesize monomolecular thin film nanotube coatings.
* 1992 – First theoretical predictions of the electronic properties of single-walled carbon nanotubes by groups at Naval Research Laboratory, USA; Massachusetts Institute of Technology; and NEC Corporation.
* 1993 – Groups led by Donald S. Bethune at IBM and Sumio Iijima at NEC independently discover single-wall carbon nanotubes and methods to produce them using transition-metal catalysts.
* 1995 – Swiss researchers are the first to demonstrate the electron emission properties of carbon nanotubes. German inventors Till Keesmann and Hubert Grosse-Wilde predicted this property of carbon nanotubes earlier in the year in their patent application.
** First carbon nanotube single-electron transistors (operating at low temperature) are demonstrated by groups at Delft University and UC Berkeley.
** The first suggestion of using carbon nanotubes as optical antennas is made in the patent application of inventor Robert Crowley filed in January 1997.
* 1998 – First carbon nanotube field-effect transistors are demonstrated by groups at Delft University and IBM. | 1 | Applied and Interdisciplinary Chemistry |
*Lomagundi-Jatuli event (2,300–2,080 Ma) Paleoproterozoic - Positive excursion
*Shunga-Francevillian event (2,080 Ma) Paleoproterozoic - Negative excursion
*Shuram-Wonoka excursion (570–551 Ma) Neoproterozoic - Negative excursion
*Steptoean positive carbon isotope excursion (494.6-492 Ma) Paleozoic - Positive excursion
*Ireviken event (433.4 Ma) Paleozoic - Positive excursion
*Mulde event (427 Ma) Paleozoic - Positive excursion
*Lau event (424 Ma) Paleozoic - Positive excursion
*Cenomanian-Turonian boundary event (93.9 Ma) Mesozoic - Positive excursion
*Paleocene–Eocene Thermal Maximum (55.5 Ma) Cenozoic - Negative excursion | 0 | Theoretical and Fundamental Chemistry |
Reading et al. have explored the use of a broadband QCL combined with thermal expansion measurements. Above, the inability of thermal broadband sources to achieve high spatial resolution is discussed (see history). In this case the frequency of modulation is limited by the mirror speed of the interferometer which, in turn, limits the lateral spatial resolution that can be achieved. When using a broadband QCL the resolution is limited not by the mirror speed but by the modulation frequency of the laser pulses (or other waveforms). The benefit of using a broadband source is that an image can be acquired that comprises an entire spectrum or part of a spectrum for each pixel. This is much more powerful than acquiring images bases on a single wavelength. The preliminary results of Reading et al. show that directing a broadband QCL though an interferometer can give an easily detectable response from a conventional AFM probe measuring thermal expansion. | 0 | Theoretical and Fundamental Chemistry |
On January 29, 2008, the U.S. Department of Energy announced that it would pull its funding for the project, mostly due to higher than expected costs. The move is likely to delay the project as other members seek the additional funds that the DOE was to provide. The sudden concern over cost after an Illinois site was chosen over those in Texas raised questions about the motives for the cancellation. Local and state officials in Illinois, including then Governor Rod Blagojevich, expressed frustration at the move, especially in light of the money and resources that the state had spent to attract the project. Democratic Senator Dick Durbin of Illinois accused Energy Secretary Samuel Bodman of "cruel deception" of Illinoisans by "creating false hope in a FutureGen project which he has no intention of funding or supporting." Durbin claimed that "when the city of Mattoon, Illinois, was chosen over possible locations in Texas, the secretary of energy set out to kill FutureGen." Mattoon mayor David Cline said "one could question the motivation of the Department of Energy which was ready to move forward with the project until a site other than Texas was chosen."
In March 2009, Congressional auditors determined that the DOE had miscalculated the government portion of the project's cost, overstating the amount by a half billion dollars. As a result, the Bush administration cited the project as having nearly doubled in cost when, in reality, it had increased by 39%
Secretary Bodman stated that with restructuring the FutureGen project, DOE plans "to equip multiple new clean-coal power plants with advanced CCS technology, instead of one demonstration plant. That will provide more electricity from multiple clean-coal plants, sequestering at least twice as much CO and providing for wider use and more rapid commercialization." | 1 | Applied and Interdisciplinary Chemistry |
Electroplating is a common surface-treatment technique. It involves bonding a thin layer of another metal such as gold, silver, chromium or zinc to the surface of the product by hydrolysis. It is used to reduce corrosion, create abrasion resistance and improve the product's aesthetic appearance. Plating can even change the properties of the original part including conductivity, heat dissipation or structural integrity. There are four main electroplating methods to ensure proper coating and cost effectiveness per product: mass plating, rack plating, continuous plating and line plating. | 1 | Applied and Interdisciplinary Chemistry |
One way of understanding the carcinogenic effects of benzene is by examining the products of biological oxidation. Pure benzene, for example, oxidizes in the body to produce an epoxide, benzene oxide, which is not excreted readily and can interact with DNA to produce harmful mutations. | 1 | Applied and Interdisciplinary Chemistry |
The Wu theory (after Souheng Wu) is also essentially similar to the Owens/Wendt and Fowkes theories, in that it divides surface energy into a polar and a dispersive component. The primary difference is that Wu uses the harmonic means rather than the geometric means of the known surface tensions, and subsequently the use of more rigorous mathematics is employed. | 0 | Theoretical and Fundamental Chemistry |
Although uncompetitive economically, bitumen can be made from nonpetroleum-based renewable resources such as sugar, molasses and rice, corn and potato starches. Bitumen can also be made from waste material by fractional distillation of used motor oil, which is sometimes otherwise disposed of by burning or dumping into landfills. Use of motor oil may cause premature cracking in colder climates, resulting in roads that need to be repaved more frequently.
Nonpetroleum-based asphalt binders can be made light-colored. Lighter-colored roads absorb less heat from solar radiation, reducing their contribution to the urban heat island effect. Parking lots that use bitumen alternatives are called green parking lots. | 0 | Theoretical and Fundamental Chemistry |
The citric acid cycle, also known as the Krebs cycle or the TCA (tricarboxylic acid) cycle is an 8-step process that takes the pyruvate generated by glycolysis and generates 4 NADH, FADH2, and GTP, which is further converted to ATP. It is only in step 5, where GTP is generated, by succinyl-CoA synthetase, and then converted to ATP, that ADP is used (GTP + ADP → GDP + ATP). | 1 | Applied and Interdisciplinary Chemistry |
The addition of certain alloying elements, such as manganese and nickel, can stabilize the austenitic structure, facilitating heat-treatment of low-alloy steels. In the extreme case of austenitic stainless steel, much higher alloy content makes this structure stable even at room temperature.
On the other hand, such elements as silicon, molybdenum, and chromium tend to de-stabilize austenite, raising the eutectoid temperature. | 1 | Applied and Interdisciplinary Chemistry |
In mathematics and empirical science, quantification (or quantitation) is the act of counting and measuring that maps human sense observations and experiences into quantities. | 0 | Theoretical and Fundamental Chemistry |
* B – magnetic field
* L – characteristic length
* σ – electric conductivity
* U – characteristic velocity scale
* ρ – density
* Ha – Hartmann number
* Re – Reynolds number | 1 | Applied and Interdisciplinary Chemistry |
Instead of cloning, adaptors containing the endonuclease sequence are ligated to the ends of fragmented genomic DNA or cDNA. The molecules are then self-circularized and digested with endonuclease, releasing the PET. Before sequencing, these PETs are ligated to adaptors to which PCR primers anneal for amplification.
The advantage of cloning based construction of the library is that it maintains the fragments or cDNA intact for future use. However, the construction process is much longer than the cloning-free method. Variations on library construction have been produced by next-generation sequencing companies to suit their respective technologies. | 1 | Applied and Interdisciplinary Chemistry |
Thallium(III) nitrate, also known as thallic nitrate, is a thallium compound with chemical formula Tl(NO). It is normally found as the trihydrate. It is a colorless and highly toxic salt. It is a strong oxidizing agent useful in organic synthesis. Among its many transformations, it oxidizes methoxyl phenols to quinone acetals, alkenes to acetals, and cyclic alkenes to ring-contracted aldehydes. | 0 | Theoretical and Fundamental Chemistry |
Devereux recruited E A G Liddiard from The British Non-Ferrous Metals Research Association (BNF) to be Fulmer's Director of Research
Among other senior staff recruited were:
* Philipp Gross a refugee from Vienna who was an expert in chemical thermodynamics and had been working at International Alloys (another Almin company) on the direct reduction of magnesite to magnesium, appointed Principal Scientist
* Ted Calnan, appointed Principal Physicist
* Arthur Sully, recruited from Special Metals Wiggin Limited, was an expert on the creep of jet engine turbine blades. He established Fulmer's reputation in physical metallurgy
* Harold Hardy, another metallurgist, worked on the development of new aluminium alloys
* Gordon Metcalfe, recruited from the Royal Aircraft Establishment to head the corrosion section
* Tom Heal, a physicist who had served in the Navy working on counter measures against acoustic and magnetic mines, became head of physics
* Eric Brandes, a process metallurgist from the Ford Motor Company
* Leon Levi, a physical chemist
By the end of 1946 Fulmer had about 40 Staff. | 1 | Applied and Interdisciplinary Chemistry |
In combination with indapamide, perindopril has been shown to significantly reduce the progression of chronic kidney disease and renal complications in patients with type 2 diabetes. In addition, the Perindopril pROtection aGainst REcurrent Stroke Study (PROGRESS) found that whilst perindopril monotherapy demonstrated no significant benefit in reducing recurrent strokes when compared to placebo, the addition of low dose indapamide to perindopril therapy was associated with larger reductions in both blood pressure lowering and recurrent stroke risk in patients with pre-existing cerebrovascular disease, irrespective of their blood pressure. There is evidence to support the use of perindopril and indapamide combination over perindopril monotherapy to prevent strokes and improve mortality in patients with a history of stroke, transient ischaemic attack or other cardiovascular disease. | 0 | Theoretical and Fundamental Chemistry |
When carbon dioxide is the substrate, the product of the carboxylase reaction is an unstable six-carbon phosphorylated intermediate known as 3-keto-2-carboxyarabinitol-1,5-bisphosphate, which decays rapidly into two molecules of glycerate-3-phosphate. This product, also known as 3-phosphoglycerate, can be used to produce larger molecules such as glucose.
When molecular oxygen is the substrate, the products of the oxygenase reaction are phosphoglycolate and 3-phosphoglycerate. Phosphoglycolate is recycled through a sequence of reactions called photorespiration, which involves enzymes and cytochromes located in the mitochondria and peroxisomes (this is a case of metabolite repair). In this process, two molecules of phosphoglycolate are converted to one molecule of carbon dioxide and one molecule of 3-phosphoglycerate, which can reenter the Calvin cycle. Some of the phosphoglycolate entering this pathway can be retained by plants to produce other molecules such as glycine. At ambient levels of carbon dioxide and oxygen, the ratio of the reactions is about 4 to 1, which results in a net carbon dioxide fixation of only 3.5. Thus, the inability of the enzyme to prevent the reaction with oxygen greatly reduces the photosynthetic capacity of many plants. Some plants, many algae, and photosynthetic bacteria have overcome this limitation by devising means to increase the concentration of carbon dioxide around the enzyme, including carbon fixation, crassulacean acid metabolism, and the use of pyrenoid.
Rubisco side activities can lead to useless or inhibitory by-products. Important inhibitory by-products include xylulose 1,5-bisphosphate and glycero-2,3-pentodiulose 1,5-bisphosphate, both caused by "misfires" halfway in the enolisation-carboxylation reaction. In higher plants, this process causes RuBisCO self-inhibition, which can be triggered by saturating and RuBP concentrations and solved by Rubisco activase (see below). | 0 | Theoretical and Fundamental Chemistry |
The carboxy-terminal domain is also the binding site of the cap-synthesizing and cap-binding complex. In eukaryotes, after transcription of the 5 end of an RNA transcript, the cap-synthesizing complex on the CTD will remove the gamma-phosphate from the 5-phosphate and attach a GMP, forming a 5,5-triphosphate linkage. The synthesizing complex falls off and the cap then binds to the cap-binding complex (CBC), which is bound to the CTD.
The 5'cap of eukaryotic RNA transcripts is important for binding of the mRNA transcript to the ribosome during translation, to the CTD of RNAP, and prevents RNA degradation. | 1 | Applied and Interdisciplinary Chemistry |
For molecular biology research different types of markers may be used based on the selection sought. These include:
*Positive or selection markers are selectable markers that confer selective advantage to the host organism. An example would be antibiotic resistance, which allows the host organism to survive antibiotic selection.
*Negative or counterselectable markers are selectable markers that eliminate or inhibit growth of the host organism upon selection. An example would be thymidine kinase, which makes the host sensitive to ganciclovir selection.
*Positive and negative selectable markers can serve as both a positive and a negative marker by conferring an advantage to the host under one condition, but inhibits growth under a different condition. An example would be an enzyme that can complement an auxotrophy (positive selection) and be able to convert a chemical to a toxic compound (negative selection). | 1 | Applied and Interdisciplinary Chemistry |
Phenolphthalein is used in toys, for example as a component of disappearing inks, or disappearing dye on the "Hollywood Hair" Barbie hair. In the ink, it is mixed with sodium hydroxide, which reacts with carbon dioxide in the air. This reaction leads to the pH falling below the color change threshold as hydrogen ions are released by the reaction:
:OH + CO → carbonate| + H.
To develop the hair and "magic" graphical patterns, the ink is sprayed with a solution of hydroxide, which leads to the appearance of the hidden graphics by the same mechanism described above for color change in alkaline solution. The pattern will eventually disappear again because of the reaction with carbon dioxide. Thymolphthalein is used for the same purpose and in the same way, when a blue color is desired. | 0 | Theoretical and Fundamental Chemistry |
;Chemical shrinkage (self-desiccation)
The cement hydration process consumes water molecules. The sum of the volumes of the hydration products present in the hardened cement paste is smaller than the sum of the volumes of the reacting mineral phases present in the cement clinker. Therefore, the volume of the fresh and very young concrete undergoes a contraction due to the hydration reaction: it is what is called "chemical shrinkage" or "self-desiccation". It is not a problem as long as the very fresh concrete is still in a liquid, or a sufficiently plastic, state and can easily accommodate volume changes (contraction).
;Plastic shrinkage
Later in the setting phase, when the fresh concrete becomes more viscous and starts to harden, water loss due to unwanted evaporation can cause "plastic shrinkage". This occur when concrete is placed under hot conditions, e.g. in the summer and not sufficiently protected against evaporation. Cracks often develop above reinforcement bars because the contraction of concrete is locally restrained at this level and the still setting and weakly resistant concrete cannot freely shrink.
;Cracks due to a poor curing (loss of water at early age)
The curing of concrete when it continues to harden after its initial setting and progressively develops its mechanical strength is a critical phase to avoid unwanted cracks in concrete. Depending on the temperature (summer or winter conditions) and thus on the cement hydration kinetics controlling the setting and hardening rate of concrete, curing time can require a few days only (summer) or up to two weeks (winter). It is then capital to avoid losses of water by evaporation because water is still necessary for continuing the slow cement hydration. Water loss at this stage aggravates concrete shrinkage and can cause unacceptable cracks to develop in concrete. Cracks form in case of a too short, or too poor, curing when young concrete has not yet developed a sufficient early strength to withstand tensile stress caused by undesirable and premature drying. Cracks development occurs when early-age concrete is insufficiently protected against desiccation and too much water evaporates with heat because of unfavorable meteorological conditions: e.g, high temperature, direct solar insolation, dry air, low relative humidity, and high wind speed during summer, or in hot conditions. Curing is intended to maintain moist conditions at the surface of concrete. It can be done by letting the formworks in place for a longer time, or by applying a hydrophobic thin film of an oily product (curing compound) at the concrete surface (e.g., for large slabs or rafts) to minimize water evaporation.
;Drying shrinkage
After sufficient setting and hardening of concrete (after 28 days), the progressive loss of capillary water is also responsible for the "drying shrinkage". It is a continuous and long-term process occurring later during the concrete life when under dry conditions the larger pores of concrete are no longer completely saturated by water.
;Thermal cracks
When concrete is subject to an excessive temperature increase during its setting and hardening as in massive concrete structures from where cement hydration heat cannot easily escape (semi-adiabatic conditions), the temperature gradients and the differential volume changes can also cause the formation of thermal cracks and fissures. To minimize them a slowly-setting cement (CEM III, with blast furnace slags) is preferred to a quickly setting cement (CEM I: Portland cement). Pouring concrete under colder conditions (e.g., during the night, or in the winter), or using cold water and ice mixed with cooled aggregates to prepare concrete, may also contribute to minimize thermal cracks. | 1 | Applied and Interdisciplinary Chemistry |
In quantum mechanics the free rotation of a molecule is quantized, so that the rotational energy and the angular momentum can take only certain fixed values, which are related simply to the moment of inertia, , of the molecule. For any molecule, there are three moments of inertia: , and about three mutually orthogonal axes A, B, and C with the origin at the center of mass of the system. The general convention, used in this article, is to define the axes such that , with axis corresponding to the smallest moment of inertia. Some authors, however, define the axis as the molecular rotation axis of highest order.
The particular pattern of energy levels (and, hence, of transitions in the rotational spectrum) for a molecule is determined by its symmetry. A convenient way to look at the molecules is to divide them into four different classes, based on the symmetry of their structure. These are | 0 | Theoretical and Fundamental Chemistry |
Solubility values of organic acids, bases, and ampholytes of pharmaceutical interest may be obtained by a process called "Chasing equilibrium solubility". In this procedure, a quantity of substance is first dissolved at a pH where it exists predominantly in its ionized form and then a precipitate of the neutral (un-ionized) species is formed by changing the pH. Subsequently, the rate of change of pH due to precipitation or dissolution is monitored and strong acid and base titrant are added to adjust the pH to discover the equilibrium conditions when the two rates are equal. The advantage of this method is that it is relatively fast as the quantity of precipitate formed is quite small. However, the performance of the method may be affected by the formation supersaturated solutions. | 0 | Theoretical and Fundamental Chemistry |
Formally, amidines are a class of oxoacids. The oxoacid from which an amidine is derived must be of the form RE(=O)OH, where R is a substituent. The −OH group is replaced by an −NH group and the =O group is replaced by =NR, giving amidines the general structure RE(=NR)NR. When the parent oxoacid is a carboxylic acid, the resulting amidine is a carboxamidine or carboximidamide (IUPAC name). Carboxamidines are frequently referred to simply as amidines, as they are the most commonly encountered type of amidine in organic chemistry. | 0 | Theoretical and Fundamental Chemistry |
Cephalothin, a first generation cephalosporin for parenteral use was the first cephalosporin to become available for patients in the US in 1964. It was chosen for clinical trials from series of 7-ACA derivatives prepared at Eli Lilly. The second cephalosporin for parenteral use became available little later and was marketed in the US under the name Cephaloridine. The clinical successes of these two cephalosporins urged researchers to improve the pharmacological properties and develop more agents. Today we are left with thousands of semisynthesized analogues of natural cephalosporin compounds based on the knowledge gained by intensive research on the chemistry of those two starting materials. | 1 | Applied and Interdisciplinary Chemistry |
mRNA binding allows repression of protein translation through direct blocking, degradation or cleavage of mRNA. Certain mRNA binding mechanisms have high specificity, which can act as a form of the intrinsic immune response during certain viral infections. Certain segmented RNA viruses can also regulate viral gene expression through RNA binding of another genome segment, however, the details of this mechanism are still unclear.
Specific examples include:
* RNA binding protein
* siRNA
* miRNA
* piRNA | 1 | Applied and Interdisciplinary Chemistry |
The National Historic Chemical Landmarks program was launched by the American Chemical Society in 1992 to recognize significant achievements in the history of chemistry and related professions. The program celebrates the centrality of chemistry. The designation of such generative achievements in the history of chemistry demonstrates how chemists have benefited society by fulfilling the ACS vision: Improving people's lives through the transforming power of chemistry.
The program occasionally designates International Historic Chemical Landmarks to commemorate "chemists and chemistry from around the world that have had a major impact in the United States". | 1 | Applied and Interdisciplinary Chemistry |
These are the Bravais lattice types in three dimensions:
* P – Primitive
* I – Body centered (from the German "Innenzentriert")
* F – Face centered (from the German "Flächenzentriert")
* A – Base centered on A faces only
* B – Base centered on B faces only
* C – Base centered on C faces only
* R – Rhombohedral | 0 | Theoretical and Fundamental Chemistry |
Very commonly when the supersaturation (or degree of supercooling) is high, and sometimes even when it is not high, growth kinetics may be diffusion-controlled. Under such conditions, the polyhedral crystal form will be unstable, it will sprout protrusions at its corners and edges where the degree of supersaturation is at its highest level. The tips of these protrusions will clearly be the points of highest supersaturation. It is generally believed that the protrusion will become longer (and thinner at the tip) until the effect of interfacial free energy in raising the chemical potential slows the tip growth and maintains a constant value for the tip thickness.
In the subsequent tip-thickening process, there should be a corresponding instability of shape. Minor bumps or "bulges" should be exaggerated—and develop into rapidly growing side branches. In such an unstable (or metastable) situation, minor degrees of anisotropy should be sufficient to determine directions of significant branching and growth. The most appealing aspect of this argument, of course, is that it yields the primary morphological features of dendritic growth. | 0 | Theoretical and Fundamental Chemistry |
In a fission bomb, the fissile fuel is "assembled" quickly by a uniform spherical implosion created with conventional explosives, producing a supercritical mass. In this state, many of the neutrons released by the fissioning of a nucleus will induce fission of other nuclei in the fuel mass, also releasing additional neutrons, leading to a chain reaction. This reaction consumes at most 20% of the fuel before the bomb blows itself apart, or possibly much less if conditions are not ideal: the Little Boy (gun type mechanism) and Fat Man (implosion type mechanism) bombs had efficiencies of 1.38% and 13%, respectively.
Fusion boosting is achieved by introducing tritium and deuterium gas. Solid lithium deuteride-tritide has also been used in some cases, but gas allows more flexibility (and can be stored externally) and can be injected into a hollow cavity at the center of the sphere of fission fuel, or into a gap between an outer layer and a "levitated" inner core, sometime before implosion. By the time about 1% of the fission fuel has fissioned, the temperature rises high enough to cause thermonuclear fusion, which produces relatively large numbers of neutrons, speeding up the late stages of the chain reaction and approximately doubling its efficiency.
Deuterium-tritium fusion neutrons are extremely energetic, seven times more energetic than an average fission neutron, which makes them much more likely to be captured in the fissile material and lead to fission. This is due to several reasons:
# When these energetic neutrons strike a fissile nucleus, a much larger number of secondary neutrons are released by the fission (e.g. 4.6 vs 2.9 for Pu-239).
# The fission cross section is larger both in absolute terms, and in proportion to the scattering and capture cross sections.
Taking these factors into account, the maximum alpha value for D-T fusion neutrons in plutonium (density 19.8 g/cm) is some 8 times higher than for an average fission neutron (2.5 vs 3).
A sense of the potential contribution of fusion boosting can be gained by observing that the complete fusion of one mole of tritium (3 grams) and one mole of deuterium (2 grams) would produce one mole of neutrons (1 gram), which, neglecting escape losses and scattering for the moment, could fission one mole (239 grams) of plutonium directly, producing 4.6 moles of secondary neutrons, which can in turn fission another 4.6 moles of plutonium (1,099 g). The fission of this 1,338 g of plutonium in the first two generations would release 23 kilotons of TNT equivalent (97 TJ) of energy, and would by itself result in a 29.7% efficiency for a bomb containing 4.5 kg of plutonium (a typical small fission trigger). The energy released by the fusion of the 5 g of fusion fuel itself is only 1.73% of the energy released by the fission of 1,338 g of plutonium. Larger total yields and higher efficiency are possible, since the chain reaction can continue beyond the second generation after fusion boosting.
Fusion-boosted fission bombs can also be made immune to neutron radiation from nearby nuclear explosions, which can cause other designs to predetonate, blowing themselves apart without achieving a high yield.
The combination of reduced weight in relation to yield and immunity to radiation has ensured that most modern nuclear weapons are fusion-boosted.
The fusion reaction rate typically becomes significant at 20 to 30 megakelvins. This temperature is reached at very low efficiencies, when less than 1% of the fissile material has fissioned (corresponding to a yield in the range of hundreds of tons of TNT). Since implosion weapons can be designed that will achieve yields in this range even if neutrons are present at the moment of criticality, fusion boosting allows the manufacture of efficient weapons that are immune to predetonation. Elimination of this hazard is a very important advantage in using boosting. It appears that every weapon now in the U.S. arsenal is a boosted design.
According to one weapons designer, boosting is mainly responsible for the remarkable 100-fold increase in the efficiency of fission weapons since 1945. | 0 | Theoretical and Fundamental Chemistry |
Tic20 is an integral protein thought to have four transmembrane α-helices. It is found in the 1 million dalton TIC complex. Because it is similar to bacterial amino acid transporters and the mitochondrial import protein Tim17 (translocase on the inner mitochondrial membrane), it has been proposed to be part of the TIC import channel. There is no in vitro evidence for this though. In Arabidopsis thaliana, it is known that for about every five Toc75 proteins in the outer chloroplast membrane, there are two Tic20 I proteins (the main form of Tic20 in Arabidopsis) in the inner chloroplast membrane.
Unlike Tic214, Tic100, or Tic56, Tic20 has homologous relatives in cyanobacteria and nearly all chloroplast lineages, suggesting it evolved before the first chloroplast endosymbiosis. Tic214, Tic100, and Tic56 are unique to chloroplastidan chloroplasts, suggesting that they evolved later. | 0 | Theoretical and Fundamental Chemistry |
The conventional method of performing laser-induced fluorescence, as well as other types of spectroscopic measurements, such as infrared, ultraviolet-visible spectroscopy, phosphorescence, etc., is to use a small transparent laboratory vessel, a cuvette, to contain the sample to be analyzed.
To perform a measurement, the cuvette is filled with the liquid to be investigated and then illuminated with a laser focused through one of the cuvette's faces. A lens is placed in line with one of the faces of the cuvette located at 90° from the input window to collect the laser-induced fluorescent light. Only a small volume of the cuvette is actually illuminated by the laser and produces a detectable spectroscopic emission. The output signal is significantly reduced because the lens picks up only about 10% of the spectroscopic emission due to solid angle considerations. This technique has been used for at least 75 years; even before the laser existed, when conventional light sources were used to excite the fluorescence.
SOFIA solves the problem of low collection efficiency, as it collects nearly all of the fluorescent light produced from the sample being analyzed, increasing the amount of fluorescence signal by around a factor of 10 over conventional apparatus. | 1 | Applied and Interdisciplinary Chemistry |
Transposable elements have been recognized as good candidates for stimulating gene adaptation, through their ability to regulate the expression levels of nearby genes. Combined with their "mobility", transposable elements can be relocated adjacent to their targeted genes, and control the expression levels of the gene, dependent upon the circumstances.
The study conducted in 2008, "High Rate of Recent Transposable Element–Induced Adaptation in Drosophila melanogaster", used D. melanogaster that had recently migrated from Africa to other parts of the world, as a basis for studying adaptations caused by transposable elements. Although most of the TEs were located on introns, the experiment showed a significant difference in gene expressions between the population in Africa and other parts of the world. The four TEs that caused the selective sweep were more prevalent in D. melanogaster from temperate climates, leading the researchers to conclude that the selective pressures of the climate prompted genetic adaptation. From this experiment, it has been confirmed that adaptive TEs are prevalent in nature, by enabling organisms to adapt gene expression as a result of new selective pressures.
However, not all effects of adaptive TEs are beneficial to the population. In the research conducted in 2009, "A Recent Adaptive Transposable Element Insertion Near Highly Conserved Developmental Loci in Drosophila melanogaster", a TE, inserted between Jheh 2 and Jheh 3, revealed a downgrade in the expression level of both of the genes. Downregulation of such genes has caused Drosophila to exhibit extended developmental time and reduced egg to adult viability. Although this adaptation was observed in high frequency in all non-African populations, it was not fixed in any of them. This is not hard to believe, since it is logical for a population to favor higher egg to adult viability, therefore trying to purge the trait caused by this specific TE adaptation.
At the same time, there have been several reports showing the advantageous adaptation caused by TEs. In the research done with silkworms, "An Adaptive Transposable Element insertion in the Regulatory Region of the EO Gene in the Domesticated Silkworm", a TE insertion was observed in the cis-regulatory region of the EO gene, which regulates molting hormone 20E, and enhanced expression was recorded. While populations without the TE insert are often unable to effectively regulate hormone 20E under starvation conditions, those with the insert had a more stable development, which resulted in higher developmental uniformity.
These three experiments all demonstrated different ways in which TE insertions can be advantageous or disadvantageous, through means of regulating the expression level of adjacent genes. The field of adaptive TE research is still under development and more findings can be expected in the future. | 1 | Applied and Interdisciplinary Chemistry |
Many agrochemicals are toxic, and agrichemicals in bulk storage may pose significant environmental and/or health risks, particularly in the event of accidental spills. In many countries, use of agrichemicals is highly regulated. Government-issued permits for purchase and use of approved agrichemicals may be required. Significant penalties can result from misuse, including improper storage resulting in spillage. On farms, proper storage facilities and labeling, emergency clean-up equipment and procedures, and safety equipment and procedures for handling, application and disposal are often subject to mandatory standards and regulations. Usually, the regulations are carried out through the registration process.
For instance, bovine somatotropin, though widely used in the United States, is not approved in Canada and some other jurisdictions as there are concerns for the health of cows using it. | 1 | Applied and Interdisciplinary Chemistry |
Advanced polymer composites are used in the strengthening and rehabilitation of old structures. These advanced composites can be made using many different methods including prepreg, resin, infusion, filament winding and pultrusion. Advanced polymer composites are used in many airplane structures and their largest market is in aerospace and defense. | 0 | Theoretical and Fundamental Chemistry |
Reciprocating steam engines have been used for mechanical power sources since the 18th Century, with notable improvements being made by James Watt. The very first commercial central electrical generating stations in New York and London, in 1882, also used reciprocating steam engines. As generator sizes increased, eventually turbines took over due to higher efficiency and lower cost of construction. By the 1920s any central station larger than a few thousand kilowatts would use a turbine prime mover. | 1 | Applied and Interdisciplinary Chemistry |
Twenty-two DNA repair genes with hypermethylated promoters, and reduced or absent expression, were found to occur among 17 types of cancer, as listed in two review articles. Promoter hypermethylation of MGMT occurs frequently in a number of cancers including 93% of bladder cancers, 88% of stomach cancers, 74% of thyroid cancers, 40%-90% of colorectal cancers and 50% of brain cancers. That review also indicated promoter hypermethylation of LIG4, NEIL1, ATM, MLH1 or FANCB occurs at frequencies between 33% and 82% in one or more of head and neck cancers, non-small-cell lung cancers or non-small-cell lung cancer squamous cell carcinomas. The article Epigenetic inactivation of the premature aging Werner syndrome gene in human cancer indicates the DNA repair gene WRN has a promoter that is frequently hypermethylated in a number of cancers, with hypermethylation occurring in 11% to 38% of colorectal, head and neck, stomach, prostate, breast, thyroid, non-Hodgkin lymphoma, chondrosarcoma and osteosarcoma cancers (see WRN). | 1 | Applied and Interdisciplinary Chemistry |
Transition metal carbonate and bicarbonate complexes are coordination compounds containing carbonate (CO) and bicarbonate (HCO) as ligands. The inventory of complexes is large, enhanced by the fact that the carbonate ligand can bind metal ions in a variety of bonding modes. They illustrate the fate of low valent complexes when exposed to air. | 0 | Theoretical and Fundamental Chemistry |
In a polymer solution, a theta solvent (or θ solvent) is a solvent in which polymer coils act like ideal chains, assuming exactly their random walk coil dimensions. Therefore, the Mark–Houwink equation exponent is in a theta solvent. Thermodynamically, the excess chemical potential of mixing between a polymer and a theta solvent is zero. | 0 | Theoretical and Fundamental Chemistry |
The development of extensional rheometers has proceeded more slowly than shear rheometers, due to the challenges associated with generating a homogeneous extensional flow. Firstly, interactions of the test fluid or melt with solid interfaces will result in a component of shear flow, which will compromise the results. Secondly, the strain history of all the material elements must be controlled and known. Thirdly, the strain rates and strain levels must be high enough to stretch the polymeric chains beyond their normal radius of gyration, requiring instrumentation with a large range of deformation rates and a large travel distance.
Commercially available extensional rheometers have been segregated according to their applicability to viscosity ranges. Materials with a viscosity range from approximately 0.01 to 1 Pa.s. (most polymer solutions) are best characterized with capillary breakup rheometers, opposed jet devices, or contraction flow systems. Materials with a viscosity range from approximately 1 to 1000 Pa.s. are used in filament stretching rheometers. Materials with a high viscosity >1000 Pa.s., such as polymer melts, are best characterized by constant-length devices.
Extensional rheometry is commonly performed on materials that are subjected to a tensile deformation. This type of deformation can occur during processing, such as injection molding, fiber spinning, extrusion, blow-molding, and coating flows. It can also occur during use, such as decohesion of adhesives, pumping of hand soaps, and handling of liquid food products.
A list of currently and previously marketed commercially available extensional rheometers is shown in the table below. | 1 | Applied and Interdisciplinary Chemistry |
In previous stages acetyl-CoA is transferred from the mitochondria to the cytoplasm where fatty acid synthase resides. The acetyl-CoA is transported as a citrate, which has been previously formed in the mitochondrial matrix from acetyl-coA and oxaloacetate. This reaction usually initiates the citric acid cycle, but when there is no need of energy it is transported to the cytoplasm where it is broken down to cytoplasmic acetyl-CoA and oxaloacetate.
Another part of the cycle requires NADPH for the synthesis of fatty acids. Part of this reducing power is generated when the cytosolic oxaloacetate is returned to the mitochondria as long as the internal mitochondrial layer is non-permeable for oxaloacetate. Firstly the oxaloacetate is reduced to malate using NADH. Then the malate is decarboxylated to pyruvate. Now this pyruvate can easily enter the mitochondria, where it is carboxylated again to oxaloacetate by pyruvate carboxylase. In this way, the transfer of acetyl-CoA that is from the mitochondria into the cytoplasm produces a molecule of NADH. The overall reaction, which is spontaneous, may be summarized as:
:HCO + ATP + acetyl-CoA → ADP + P + malonyl-CoA | 1 | Applied and Interdisciplinary Chemistry |
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