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In the Bosch synthesis of (1999, chiral) the olefin group in dione 1 was converted to an aldehyde by ozonolysis and chiral amine 2 was formed in a double reductive amination with (S)-1-phenethylamine. The phenylethyl substituent was removed using ClCOCHClCH and the enone group was introduced in a Grieco elimination using TMSI, HMDS then PhSeCl then ozone and then diisopropylamine forming carbamate 3. The amino group was deprotected by refluxing in methanol and then alkylated using (Z)-BrCHCICH=CHOTBDMS, to tertiary amine 4. A reductive Heck reaction took place next followed by methoxycarbonylation (LiHMDS, NCCOMe) to tricycle 5. Reaction with zinc dust in 10% sulfuric acid removed the TBDMS protective group, reduced the nitro group and brought about a reductive amino-carbonyl cyclization in a single step to tetracyclic 6 (epimeric mixture). In the final step to the Wieland-Gumlich aldehyde 7 reaction with NaH in MeOH afforded the correct epimer was followed by DIBAH reduction of the methyl ester. | 0 | Theoretical and Fundamental Chemistry |
While chemical kinetics is concerned with the rate of a chemical reaction, thermodynamics determines the extent to which reactions occur. In a reversible reaction, chemical equilibrium is reached when the rates of the forward and reverse reactions are equal (the principle of dynamic equilibrium) and the concentrations of the reactants and products no longer change. This is demonstrated by, for example, the Haber–Bosch process for combining nitrogen and hydrogen to produce ammonia. Chemical clock reactions such as the Belousov–Zhabotinsky reaction demonstrate that component concentrations can oscillate for a long time before finally attaining the equilibrium. | 0 | Theoretical and Fundamental Chemistry |
Levodropropizine is a cough suppressant. It is the levo isomer of dropropizine. It acts as a peripheral antitussive, with no action in the central nervous system. It does not cause side effects such as constipation or respiratory depression which can be produced by opioid antitussives such as codeine and its derivatives. | 0 | Theoretical and Fundamental Chemistry |
This problem was addressed by George Keith Batchelor(1951). Let be the angular velocity at infinity. Now the pressure at is . Hence and .<br />
Then the boundary conditions for the fluid are
Self-similar solution is obtained by introducing following transformation,
The self-similar equations are
with boundary conditions for the fluid is
The solution is easy to obtain only for i.e., the fluid at infinity rotates in the same sense as the plate. For , the solution is more complex, in the sense that many-solution branches occur. Evans(1969) obtained solution for the range . Zandbergen and Dijkstra showed that the solution exhibits a square root singularity as and found a second-solution branch merging with the solution found for . The solution of the second branch is continued till , at which point, a third-solution branch is found to emerge. They also discovered an infinity of solution branches around the point . Bodoyni(1975) calculated solutions for large negative , showed that the solution breaks down at . If the rotating plate is allowed to have uniform suction velocity at the plate, then meaningful solution can be obtained for .
For ( represents solid body rotation, the whole fluid rotates at the same speed) the solution reaches the solid body rotation at infinity in an oscillating manner from the plate. The axial velocity is negative for and positive for . There is an explicit solution when . | 1 | Applied and Interdisciplinary Chemistry |
Molecular motion in condensed matter can be represented by a Fourier series whose physical interpretation consists of a superposition of longitudinal and transverse waves of atomic displacement with varying directions and wavelengths. In monatomic systems, these waves are called density fluctuations. (In polyatomic systems, they may also include compositional fluctuations.)
Thus, thermal motion in liquids can be decomposed into elementary longitudinal vibrations (or acoustic phonons) while transverse vibrations (or shear waves) were originally described only in elastic solids exhibiting the highly ordered crystalline state of matter. In other words, simple liquids cannot support an applied force in the form of a shearing stress, and will yield mechanically via macroscopic plastic deformation (or viscous flow). Furthermore, the fact that a solid deforms locally while retaining its rigidity – while a liquid yields to macroscopic viscous flow in response to the application of an applied shearing force – is accepted by many as the mechanical distinction between the two.
The inadequacies of this conclusion, however, were pointed out by Frenkel in his revision of the kinetic theory of solids and the theory of elasticity in liquids. This revision follows directly from the continuous characteristic of the viscoelastic crossover from the liquid state into the solid one when the transition is not accompanied by crystallization—ergo the supercooled viscous liquid. Thus we see the intimate correlation between transverse acoustic phonons (or shear waves) and the onset of rigidity upon vitrification, as described by Bartenev in his mechanical description of the vitrification process.
The velocities of longitudinal acoustic phonons in condensed matter are directly responsible for the thermal conductivity that levels out temperature differentials between compressed and expanded volume elements. Kittel proposed that the behavior of glasses is interpreted in terms of an approximately constant "mean free path" for lattice phonons, and that the value of the mean free path is of the order of magnitude of the scale of disorder in the molecular structure of a liquid or solid. The thermal phonon mean free paths or relaxation lengths of a number of glass formers have been plotted versus the glass transition temperature, indicating a linear relationship between the two. This has suggested a new criterion for glass formation based on the value of the phonon mean free path.
It has often been suggested that heat transport in dielectric solids occurs through elastic vibrations of the lattice, and that this transport is limited by elastic scattering of acoustic phonons by lattice defects (e.g. randomly spaced vacancies).
These predictions were confirmed by experiments on commercial glasses and glass ceramics, where mean free paths were apparently limited by "internal boundary scattering" to length scales of . The relationship between these transverse waves and the mechanism of vitrification has been described by several authors who proposed that the onset of correlations between such phonons results in an orientational ordering or "freezing" of local shear stresses in glass-forming liquids, thus yielding the glass transition. | 0 | Theoretical and Fundamental Chemistry |
In the first step, holo-retinol binding protein (holo-RBP; simply means RBP bound to retinol, i.e. the RBP-ROH complex) binds to the extracellular portion of STRA6. This facilitates the release of retinol through the transporter. ROH is then transferred to cellular retinol binding protein 1 (CRBP1), an intracellular acceptor of retinol that attaches to the CRBP Binding Loop (or CBL) on STRA6. This transport of ROH, in turn, activates JAK2, thereby phosphorylating STRA6 at the Y643 (tyrosine) residue. This phosphorylation enables the extension of the CBL further into the cell. Holo-CRBP-I, leaves the CBL and is replaced by apo-CRBP-I (unbound). Holo-CRBP-I will continue to the Endoplasmic Reticulum (ER) where lecithin retinol acyltransferase (LRAT) is bound. ROH is released to LRAT which will convert retinol into retinylesters. Following the release of holo-CRBP-I from intercellular STRA6, STAT5 is recruited to STRA6 phosphorylated Y643 region where it is then phosphorylated by JAK2. This phosphorylation activates STAT5 which then makes its way to the nucleus to induce expression of target genes including suppressor of cytokine signaling 3 (SOCS3), a strong inhibitor of insulin signaling. | 1 | Applied and Interdisciplinary Chemistry |
The General Conference on Weights and Measures and other international organizations recommend use of the katal. It replaces the non-SI enzyme unit of catalytic activity. The enzyme unit is still more commonly used than the katal, especially in biochemistry. The adoption of the katal has been slow. | 0 | Theoretical and Fundamental Chemistry |
Heteroboranes are classes of boranes in which at least one boron atom is replaced by another elements. Like many of the related boranes, these clusters are polyhedra and are similarly classified as closo-, nido-, arachno-, and hypho-, according to the so-called electron count. Closo- represents a complete polyhedron, while nido-, arachno- and hypho- stand for polyhedrons that are missing one, two and three vertices.
Besides carbon (carboranes or carbaboranes), other elements can also be included in the heteroborane molecules as well, such as Si (silaboranes), N (azaboranes, including borazine), P (phosphaboranes), As (arsaboranes), Sb (stibaboranes), O (oxaboranes), S (thiaboranes), Se (selenaboranes) and Te (telluraboranes), either alone or in combination.
Structurally, some heteroboranes can be derived from the icosahedral (I) Dodecaborate| anion via formal replacement of its BH fragments with isoelectronic , or fragments, e.g., closo-1- and closo-1,2- (two of the carboranes), closo-1,2- (one of the phosphaboranes) or closo-1- (one of the thiaboranes).
Heteroboranes are used in various fields, such as drug discovery, imaging, and nanotechnology. | 0 | Theoretical and Fundamental Chemistry |
The theoretical description of contact angle arises from the consideration of a thermodynamic equilibrium between the three phases: the liquid phase (L), the solid phase (S), and the gas or vapor phase (G) (which could be a mixture of ambient atmosphere and an equilibrium concentration of the liquid vapor). (The "gaseous" phase could be replaced by another immiscible liquid phase.) If the solid–vapor interfacial energy is denoted by , the solid–liquid interfacial energy by , and the liquid–vapor interfacial energy (i.e. the surface tension) by , then the equilibrium contact angle is determined from these quantities by the Young equation:
The contact angle can also be related to the work of adhesion via the Young–Dupré equation:
where is the solid – liquid adhesion energy per unit area when in the medium G. | 0 | Theoretical and Fundamental Chemistry |
Acetyl-CoA is formed into malonyl-CoA by acetyl-CoA carboxylase, at which point malonyl-CoA is destined to feed into the fatty acid synthesis pathway. Acetyl-CoA carboxylase is the point of regulation in saturated straight-chain fatty acid synthesis, and is subject to both phosphorylation and allosteric regulation. Regulation by phosphorylation occurs mostly in mammals, while allosteric regulation occurs in most organisms. Allosteric control occurs as feedback inhibition by palmitoyl-CoA and activation by citrate. When there are high levels of palmitoyl-CoA, the final product of saturated fatty acid synthesis, it allosterically inactivates acetyl-CoA carboxylase to prevent a build-up of fatty acids in cells. Citrate acts to activate acetyl-CoA carboxylase under high levels, because high levels indicate that there is enough acetyl-CoA to feed into the Krebs cycle and produce energy.
High plasma levels of insulin in the blood plasma (e.g. after meals) cause the dephosphorylation and activation of acetyl-CoA carboxylase, thus promoting the formation of malonyl-CoA from acetyl-CoA, and consequently the conversion of carbohydrates into fatty acids, while epinephrine and glucagon (released into the blood during starvation and exercise) cause the phosphorylation of this enzyme, inhibiting lipogenesis in favor of fatty acid oxidation via beta-oxidation. | 1 | Applied and Interdisciplinary Chemistry |
The conventional distinction between X-rays and gamma rays has changed over time. Originally, the electromagnetic radiation emitted by X-ray tubes almost invariably had a longer wavelength than the radiation (gamma rays) emitted by radioactive nuclei. Older literature distinguished between X- and gamma radiation on the basis of wavelength, with radiation shorter than some arbitrary wavelength, such as 10 m, defined as gamma rays. Since the energy of photons is proportional to their frequency and inversely proportional to wavelength, this past distinction between X-rays and gamma rays can also be thought of in terms of its energy, with gamma rays considered to be higher energy electromagnetic radiation than are X-rays.
However, since current artificial sources are now able to duplicate any electromagnetic radiation that originates in the nucleus, as well as far higher energies, the wavelengths characteristic of radioactive gamma ray sources vs. other types now completely overlap. Thus, gamma rays are now usually distinguished by their origin: X-rays are emitted by definition by electrons outside the nucleus, while gamma rays are emitted by the nucleus. Exceptions to this convention occur in astronomy, where gamma decay is seen in the afterglow of certain supernovas, but radiation from high energy processes known to involve other radiation sources than radioactive decay is still classed as gamma radiation.
For example, modern high-energy X-rays produced by linear accelerators for megavoltage treatment in cancer often have higher energy (4 to 25 MeV) than do most classical gamma rays produced by nuclear gamma decay. One of the most common gamma ray emitting isotopes used in diagnostic nuclear medicine, technetium-99m, produces gamma radiation of the same energy (140 keV) as that produced by diagnostic X-ray machines, but of significantly lower energy than therapeutic photons from linear particle accelerators. In the medical community today, the convention that radiation produced by nuclear decay is the only type referred to as "gamma" radiation is still respected.
Due to this broad overlap in energy ranges, in physics the two types of electromagnetic radiation are now often defined by their origin: X-rays are emitted by electrons (either in orbitals outside of the nucleus, or while being accelerated to produce bremsstrahlung-type radiation), while gamma rays are emitted by the nucleus or by means of other particle decays or annihilation events. There is no lower limit to the energy of photons produced by nuclear reactions, and thus ultraviolet or lower energy photons produced by these processes would also be defined as "gamma rays" (indeed, this happens for the isomeric transition of the extremely low-energy isomer Th). The only naming-convention that is still universally respected is the rule that electromagnetic radiation that is known to be of atomic nuclear origin is always referred to as "gamma rays", and never as X-rays. However, in physics and astronomy, the converse convention (that all gamma rays are considered to be of nuclear origin) is frequently violated.
In astronomy, higher energy gamma and X-rays are defined by energy, since the processes that produce them may be uncertain and photon energy, not origin, determines the required astronomical detectors needed. High-energy photons occur in nature that are known to be produced by processes other than nuclear decay but are still referred to as gamma radiation. An example is "gamma rays" from lightning discharges at 10 to 20 MeV, and known to be produced by the bremsstrahlung mechanism.
Another example is gamma-ray bursts, now known to be produced from processes too powerful to involve simple collections of atoms undergoing radioactive decay. This is part and parcel of the general realization that many gamma rays produced in astronomical processes result not from radioactive decay or particle annihilation, but rather in non-radioactive processes similar to X-rays. Although the gamma rays of astronomy often come from non-radioactive events, a few gamma rays in astronomy are specifically known to originate from gamma decay of nuclei (as demonstrated by their spectra and emission half life). A classic example is that of supernova SN 1987A, which emits an "afterglow" of gamma-ray photons from the decay of newly made radioactive nickel-56 and cobalt-56. Most gamma rays in astronomy, however, arise by other mechanisms. | 0 | Theoretical and Fundamental Chemistry |
There are several aspects of FAIRE-seq that require attention when analysing and interpreting the data. For one, it has been stated that FAIRE-seq will have a higher coverage at enhancer regions over promoter regions. This is in contrast to the alternative method of DNase-seq who is known to show a higher sensitivity towards promoter regions. In addition, FAIRE-seq has been stated to show prefers for internal introns and exons. In general it is also believed that FAIRE-seq data displays a higher background level, making it a less sensitive method. | 1 | Applied and Interdisciplinary Chemistry |
A specialized form of cell signaling
*BLOC1S1
*BLOC1S2NM_173809
*BLOC1S3NM_212550
*BLOC1S4NM_018366
*BLOC1S6NM_012388
*AP1G1 NM_001128
*AP1M1 NM_032493
*AP2A1 NM_014203
*AP2A2 NM_012305
*AP2M1
*AP2S1 NM_004069
*AP3B1 NM_003664
*AP3D1 NM_003938
*AP3M1 NM_012095
*AP3S1 NM_001284
*AP3S2 NM_005829
*AP4B1 NM_006594
*AP5M1 NM_018229
*ANXA6 Annexin 6
*ANXA7 Annexin 7
*AP1B1 Coated vesicles
*CLTA Clathrin A (vesicles)
*CLTB Clathrin B (vesicles)
*CLTC | 1 | Applied and Interdisciplinary Chemistry |
Quantum devices can operate either continuously or by a reciprocating cycle.
Continuous devices include solar cells converting solar radiation to electrical power, thermoelectric where the output is current and lasers where the output power is coherent light.
The primary example of a continuous refrigerator is optical pumping and laser cooling.
Similarly to classical reciprocating engines, quantum heat engines also have a cycle that is divided into different strokes. A stroke is time segment in which a certain operation takes place (e.g. thermalization, or work extraction). Two adjacent strokes do not commute with each other. The most common reciprocating heat machines are the four-stroke machine, and the two-stroke machine. Reciprocating devices have been suggested operating either by the Carnot cycle or the Otto cycle.
In both types the quantum description allows to obtain equation of motion for the working medium
and the heat flow from the reservoirs. | 0 | Theoretical and Fundamental Chemistry |
The plasmalysis of wastewater and liquid manure enables hydrogen to be recovered from pollutants contained in the wastewater (ammonium (NH4) or hydrocarbon compounds (COD)). The plasma-catalytic decomposition of ammonia takes place as shown in the following reaction equation:
The treated wastewater is purified in the process. The energy requirement for the production of green hydrogen is approx. 12 kWh/kg.
This technology can also be used as ammonia cracking (chemistry) technology for splitting the hydrogen carrier ammonia. | 0 | Theoretical and Fundamental Chemistry |
SHIFTCOR generates and reports chemical shift offsets or differences for each nucleus. The results contain the chemical shift analyses (including lists of potential mis-assignments, the estimated referencing errors, the estimated error in the calculated reference offset (95% confidence interval), the applied or suggested reference offset, correlation coefficients, RMSD values) and the corrected BMRB formatted chemical shift file (see Figure 1 for details).
SHIFTCOR uses the chemical shift calculation program SHIFTX to predict 1Hα, 13Cα,15N shifts based on the 3D structure coordinates of the protein being analyzed. By comparing the predicted shifts to the observed shifts, SHIFTCOR is able to accurately identify chemical shift reference offsets as well as potential mis-assignments. A key limitation to the SHIFTCOR approach is that requires that the 3D structure for the target protein be available to assess the chemical shift reference offsets. Given that chemical shift assignments are typically made before the structure is determined, it was soon realized that structure-independent approaches were required to develop. | 0 | Theoretical and Fundamental Chemistry |
Nucleic acid analogues are used in molecular biology for several purposes:
* Investigation of possible scenarios of the origin of life: By testing different analogs, researchers try to answer the question of whether life's use of DNA and RNA was selected over time due to its advantages, or if they were chosen by arbitrary chance;
* As a tool to detect particular sequences: XNA can be used to tag and identify a wide range of DNA and RNA components with high specificity and accuracy;
* As an enzyme acting on DNA, RNA and XNA substrates - XNA has been shown to have the ability to cleave and ligate DNA, RNA and other XNA molecules similar to the actions of RNA ribozymes;
* As a tool with resistance to RNA hydrolysis;
* Investigation of the mechanisms used by enzyme; and
* Investigation of the structural features of nucleic acids. | 1 | Applied and Interdisciplinary Chemistry |
The thermodynamics of an ideal Bose gas is best calculated using the grand canonical ensemble. The grand potential for a Bose gas is given by:
where each term in the sum corresponds to a particular single-particle energy level ε; g is the number of states with energy ε; z is the absolute activity (or "fugacity"), which may also be expressed in terms of the chemical potential μ by defining:
and β defined as:
where k is Boltzmanns constant and T is the temperature. All thermodynamic quantities may be derived from the grand potential and we will consider all thermodynamic quantities to be functions of only the three variables z , β (or T ), and V '. All partial derivatives are taken with respect to one of these three variables while the other two are held constant.
The permissible range of z is from negative infinity to +1, as any value beyond this would give an infinite number of particles to states with an energy level of 0 (it is assumed that the energy levels have been offset so that the lowest energy level is 0). | 0 | Theoretical and Fundamental Chemistry |
The mechanism of progesterone protective effects may be the reduction of inflammation that follows brain trauma and hemorrhage.
Damage incurred by traumatic brain injury is believed to be caused in part by mass depolarization leading to excitotoxicity. One way in which progesterone helps to alleviate some of this excitotoxicity is by blocking the voltage-dependent calcium channels that trigger neurotransmitter release. It does so by manipulating the signaling pathways of transcription factors involved in this release. Another method for reducing the excitotoxicity is by up-regulating the GABA, a widespread inhibitory neurotransmitter receptor.
Progesterone has also been shown to prevent apoptosis in neurons, a common consequence of brain injury. It does so by inhibiting enzymes involved in the apoptosis pathway specifically concerning the mitochondria, such as activated caspase 3 and cytochrome c.
Not only does progesterone help prevent further damage, it has also been shown to aid in neuroregeneration. One of the serious effects of traumatic brain injury includes edema. Animal studies show that progesterone treatment leads to a decrease in edema levels by increasing the concentration of macrophages and microglia sent to the injured tissue. This was observed in the form of reduced leakage from the blood brain barrier in secondary recovery in progesterone treated rats. In addition, progesterone was observed to have antioxidant properties, reducing the concentration of oxygen free radicals faster than without. There is also evidence that the addition of progesterone can also help remyelinate damaged axons due to trauma, restoring some lost neural signal conduction. Another way progesterone aids in regeneration includes increasing the circulation of endothelial progenitor cells in the brain. This helps new vasculature to grow around scar tissue which helps repair the area of insult. | 0 | Theoretical and Fundamental Chemistry |
The stem transmits motion from the handle or controlling device to the disc. The stem typically passes through the bonnet when present. In some cases, the stem and the disc can be combined in one piece, or the stem and the handle are combined in one piece.
The motion transmitted by the stem may be a linear force, a rotational torque, or some combination of these (Angle valve using torque reactor pin and Hub Assembly). The valve and stem can be threaded such that the stem can be screwed into or out of the valve by turning it in one direction or the other, thus moving the disc back or forth inside the body. Packing is often used between the stem and the bonnet to maintain a seal. Some valves have no external control and do not need a stem as in most check valves.
Valves whose disc is between the seat and the stem and where the stem moves in a direction into the valve to shut it are normally-seated or front seated. Valves whose seat is between the disc and the stem and where the stem moves in a direction out of the valve to shut it are reverse-seated or back seated. These terms don't apply to valves with no stem or valves using rotors. | 1 | Applied and Interdisciplinary Chemistry |
Colonies of lichens may be spectacular in appearance, dominating the surface of the visual landscape as part of the aesthetic appeal to visitors of Yosemite National Park, Sequoia National Park, and the Bay of Fires. Orange and yellow lichens add to the ambience of desert trees, tundras, and rocky seashores. Intricate webs of lichens hanging from tree branches add a mysterious aspect to forests. Fruticose lichens are used in model railroading and other modeling hobbies as a material for making miniature trees and shrubs. | 1 | Applied and Interdisciplinary Chemistry |
Non-exclusives, "standard" or "catalogue products" constitute the second most important outlet for fine chemicals after custom manufacturing. API-for-Generics are the most important sub-category. Because of patent expiries, over 60 of the top 200 drugs alone, representing aggregated sales of over $150 billion, have fallen into the public domain within the past decade. This, along with government-backed incentives, are causing global sales of generics to rapidly increase.
Asian companies currently dominate the API-for-Generics business. They have multiple advantages of their low cost basis, their large home markets, and significant previous manufacturing experience compared to western manufacturers in producing for their domestic and other non-regulated markets. | 0 | Theoretical and Fundamental Chemistry |
A free radical is formed from the carboxylic acid in an oxidative decarboxylation with silver salts and an oxidizing agent. The oxidizing agent (ammonium persulfate) oxidizes the Ag(+) to Ag(2+) under the acidic reaction conditions. This induces a hydrogen atom abstraction by the silver, followed by radical decarboxylation. The carbon-centered radical then reacts with the pyridinium aromatic compound. The ultimate product is formed by rearomatization. The acylated product is formed from the acyl radical. | 0 | Theoretical and Fundamental Chemistry |
Various effects of heat on the freezing of water were described by ancient scientists, including Aristotle: "The fact that the water has previously been warmed contributes to its freezing quickly: for so it cools sooner. Hence many people, when they want to cool water quickly, begin by putting it in the sun." Aristotles explanation involved antiperistasis': "...the supposed increase in the intensity of a quality as a result of being surrounded by its contrary quality."
Francis Bacon noted that "slightly tepid water freezes more easily than that which is utterly cold." René Descartes wrote in his Discourse on the Method, relating the phenomenon to his vortex theory: "One can see by experience that water that has been kept on a fire for a long time freezes faster than other, the reason being that those of its particles that are least able to stop bending evaporate while the water is being heated."
Scottish scientist Joseph Black investigated a special case of the phenomenon by comparing previously boiled with unboiled water; he found that the previously boiled water froze more quickly. Evaporation was controlled for. He discussed the influence of stirring on the results of the experiment, noting that stirring the unboiled water led to it freezing at the same time as the previously boiled water, and also noted that stirring the very-cold unboiled water led to immediate freezing. Joseph Black then discussed Daniel Gabriel Fahrenheit's description of supercooling of water, arguing that the previously boiled water could not be as readily supercooled. | 0 | Theoretical and Fundamental Chemistry |
Pertussis toxin (PT) is a protein-based AB-type exotoxin produced by the bacterium Bordetella pertussis, which causes whooping cough. PT is involved in the colonization of the respiratory tract and the establishment of infection. Research suggests PT may have a therapeutic role in treating a number of common human ailments, including hypertension, viral infection, and autoimmunity. | 1 | Applied and Interdisciplinary Chemistry |
Mefloquine may cause abnormalities with heart rhythms that are visible on electrocardiograms. Combining mefloquine with other drugs that cause similar effects, such as quinine or quinidine, can increase these effects. Combining mefloquine with halofantrine can cause significant increases in QTc intervals. | 0 | Theoretical and Fundamental Chemistry |
Ambergris ( or ; ; ), ambergrease, or grey amber is a solid, waxy, flammable substance of a dull grey or blackish colour produced in the digestive system of sperm whales. Freshly produced ambergris has a marine, fecal odor. It acquires a sweet, earthy scent as it ages, commonly likened to the fragrance of isopropyl alcohol without the vaporous chemical astringency.
Ambergris has been highly valued by perfume makers as a fixative that allows the scent to last much longer, although it has been mostly replaced by synthetic ambroxide. Dogs are attracted to the smell of ambergris and are sometimes used by ambergris searchers. | 1 | Applied and Interdisciplinary Chemistry |
The standard liter per minute (SLM or SLPM) is a unit of (molar or) mass flow rate of a gas at standard conditions for temperature and pressure (STP), which is most commonly practiced in the United States, whereas European practice revolves around the normal litre per minute (NLPM). Until 1982, STP was defined as a temperature of 273.15 K (0 °C, 32 °F) and an absolute pressure of 101.325 kPa (1 atm). Since 1982, STP is defined as a temperature of 273.15 K (0 °C, 32 °F) and an absolute pressure of 100 kPa (1 bar).
Conversions between each volume flow metric are calculated using the following formulas:
Prior to 1982,
Post 1982,
assuming zero degree Celsius reference point for STP when using SLPM, which differs from the "room" temperature reference for the NLPM standard. These methods are used due to differences in environmental temperatures and pressures during data collection.
In the SI system of units, the preferred unit for volumetric flow rate is cubic meter per second, equivalent to 60,000 liters per minute. If the gas is to be considered as an ideal gas, then SLPM can be expressed as mole per second using the molar gas constant = 8.314510 J⋅K⋅mol: mol/s. | 1 | Applied and Interdisciplinary Chemistry |
RNA-Seq was first developed in mid 2000s with the advent of next-generation sequencing technology. The first manuscripts that used RNA-Seq even without using the term includes those of prostate cancer cell lines (dated 2006), Medicago truncatula (2006), maize (2007), and Arabidopsis thaliana (2007), while the term "RNA-Seq" itself was first mentioned in 2008. The number of manuscripts referring to RNA-Seq in the title or abstract (Figure, blue line) is continuously increasing with 6754 manuscripts published in 2018. The intersection of RNA-Seq and medicine (Figure, gold line) has similar celerity. | 1 | Applied and Interdisciplinary Chemistry |
Ammonium carbamate solutions are highly corrosive to metallic construction materials – even to resistant forms of stainless steel – especially in the hottest parts of the synthesis plant such as the stripper. Historically corrosion has been minimized (although not eliminated) by continuous injection of a small amount of oxygen (as air) into the plant to establish and maintain a passive oxide layer on exposed stainless steel surfaces. Highly corrosion resistant materials have been introduced to reduce the need for passivation oxygen, such as specialized duplex stainless steels in the 1990s, and zirconium or zirconium-clad titanium tubing in the 2000s. | 0 | Theoretical and Fundamental Chemistry |
The N-terminal domain of restriction endonuclease EcoRII; the C-terminal domain of restriction endonuclease BfiI possess a similar DNA-binding pseudobarrel protein fold. | 1 | Applied and Interdisciplinary Chemistry |
Long-held green roof traditions started in the early industrialization period more than 100 years ago exist in Germany. In the 1970s, green roof technology was elevated to the next level. Serious storm-water issues made cities think about innovative solutions, preferably with living plants. Modern green roof technology with high performance, lightweight materials were used to grow hardy vegetation even on roofs that can hardly support any additional load. In the 1980s modern green roof technology was common knowledge in Germany while it was practically unknown in any other country in the world. In Stuttgart, with one of the most innovative Department of Parks and Recreation and with the world's oldest horticultural Universities, modern green roof technology was perfected and implemented on a large scale. By the early 2000s, Germany had laws mandating that many metropolitan areas have green roofs.
With the first green roof industry boom in Germany there were quality issues recorded. The FLL formed a committee that is focused on modern green roof technology. FLL stands for Forschungsgesellschaft Landschaftsentwicklung Landschaftsbau e.V. (German Landscape Research, Development and Construction Society). The FLL is an independent non-profit organization. It was founded in 1975 by eight professional organizations for "the improvement of environmental conditions through the advancement and dissemination of plant research and its planned applications". The FLL green roof working group is only one of 40 committees which have published a long list of guidelines and labor instructions. Some of these guidelines also available in English including the German FLL-Guideline for the Planning, Execution and Upkeep of Green-Roof Sites. The results of the research and synthesis done by FLL members are constantly updated and promulgated utilizing the same principles which govern the compilation of DIN standards and are published as either guiding principles or labor instructions.
The current Green Roof Guideline was published in 2011.
Today most elements of the German FLL are part of standards and guidelines around the world (FM Global, ASTM, NRCA, SPRI etc.).
Fachvereinigung Bauwerksbegrünung (FBB) was founded in 1990 as the second green roof association after DDV (Deutscher Dachgaertner Verband) in 1985. FBB was founded as an open forum for manufacturers and planners, merchants and operators in 1990. The organization was born from the then-visionary idea of understanding the relationship between nature and constructions not as oppositional, but as an opportunity. Both the green roofing and conventional roofing industries are equally represented.
The FBB has developed to become an innovative lobbying group with a strong market presence, internationally known through its cooperation with other European associations. Today, approximately 100 member companies use the multifaceted services offered by FBB, which offers a greater degree of market expertise and competitiveness. "Kompetenz im Markt".
Today, about of new green roofs are being constructed each year. According latest studies about of these are extensive; the last are roof gardens. The cities with the most green roofs in Germany are Berlin and Stuttgart. Surveys about the status of regulation are done by the FBB. Nearly one third of all German cities have regulations to support green-roof and rain-water technology. Green-roof research institutions are located in several cities as including Hannover, Berlin, Geisenheim and Neubrandenburg.
Germany is the country with the most green roofs in the world as well as the country with the most advanced knowledge in modern green roof technology. Green roofs in Germany are part of the 2 –3 years apprentice educations system of landscaping professionals. | 1 | Applied and Interdisciplinary Chemistry |
The phenomena of superfluidity of a Bose gas and superconductivity of a strongly-correlated Fermi gas (a gas of Cooper pairs) are tightly connected to Bose–Einstein condensation. Under corresponding conditions, below the temperature of phase transition, these phenomena were observed in helium-4 and different classes of superconductors. In this sense, the superconductivity is often called the superfluidity of Fermi gas. In the simplest form, the origin of superfluidity can be seen from the weakly interacting bosons model. | 0 | Theoretical and Fundamental Chemistry |
A Lavoisier Medal is an award named and given in honor of Antoine Lavoisier, considered by some to be a father of modern chemistry.
At least three organizations independently give awards for achievement in chemical-related disciplines, each using the name Lavoisier Medal. Lavoisier Medals are awarded by the following organizations: | 1 | Applied and Interdisciplinary Chemistry |
Sulfuryl fluoride is marketed in the U.S. by three manufacturers, under four different brand names. Vikane (Dow) (EPA Reg. No. 62719- 4-ZA) has been commercially available since the early 1960s, with Zythor (marketed by competitor Ensystex of North Carolina) (EPA Reg. No. 81824- 1-AA) being more recently introduced gradually as its use is approved by individual states (in Florida circa 2004, but not in California until October 2006, for example). Sulfuryl fluoride has been marketed as a post-harvest fumigant for dry fruits, nuts, and grains under the trade name ProFume (U.S. EPA Reg. No. 62719- 376-AA). Most recently Drexel Chemical Company has registered Master Fume (EPA Reg. No. 19713-596-AA) for the structural market, competing against Vikane and Zythor. | 1 | Applied and Interdisciplinary Chemistry |
Wasium was the suggested name of a chemical element found by J. F. Bahr. The name was derived from the House of Vasa the Royal House of Sweden.
In 1862 Bahr analysed the mineral Orthite—Allanite-(Y)—from the Norwegian island Rönsholm and found an oxide which he concluded contained a new element. In the following years several articles were published making clear that the wasium oxide was a mixture of several other elements.
Wasium was said by M. Bahr to exist in Norwegian orthite and orthite from Ytterby. Bahr also said that it existed on the island of Raenshohm. Wasium was supposedly found in the mineral wasite, which is a form of allanite. | 1 | Applied and Interdisciplinary Chemistry |
There are a number of methods by which tablets and capsules can be modified in order to allow for sustained release of the active compound as it moves through the digestive tract. One of the most common methods is to embed the active ingredient in an insoluble porous matrix, such that the dissolving drug must make its way out of the matrix before it can be absorbed. In other sustained release formulations the matrix swells to form a gel through which the drug exits.
Another method by which sustained release is achieved is through an osmotic controlled-release oral delivery system, where the active compound is encased in a water-permeable membrane with a laser drilled hole at one end. As water passes through the membrane the drug is pushed out through the hole and into the digestive tract where it can be absorbed. | 1 | Applied and Interdisciplinary Chemistry |
A positive displacement meter is a type of flow meter that requires fluid to mechanically displace components in the meter in order for flow measurement. Positive displacement (PD) flow meters measure the volumetric flow rate of a moving fluid or gas by dividing the media into fixed, metered volumes (finite increments or volumes of the fluid). A basic analogy would be holding a bucket below a tap, filling it to a set level, then quickly replacing it with another bucket and timing the rate at which the buckets are filled (or the total number of buckets for the “totalized” flow). With appropriate pressure and temperature compensation, the mass flow rate can be accurately determined.
These devices consist of a chamber(s) that obstructs the media flow and a rotating or reciprocating mechanism that allows the passage of fixed-volume amounts. The number of parcels that pass through the chamber determines the media volume. The rate of revolution or reciprocation determines the flow rate. There are two basic types of positive displacement flow meters. Sensor-only systems or transducers are switch-like devices that provide electronic outputs for processors, controllers, or data acquisition systems.
Complete sensor systems provide additional capabilities such as an integral display and/or user interface. For both types of positive displacement flow meters, performance specifications include the minimum and maximum measurable flow rate, operating pressure, temperature range, maximum allowable material viscosity, connection size, and percent accuracy (typically as a percentage of actual reading, not full scale). Suppliers indicate whether devices are designed to measure fluid or gas. | 1 | Applied and Interdisciplinary Chemistry |
Lipophilicity of the statins is considered to be quite important since the hepatoselectivity of the statins is related to their lipophilicity. The more lipophilic statins tend to achieve higher levels of exposure in non-hepatic tissues, while the hydrophilic statins tend to be more hepatoselective. The difference in selectivity is because lipophilic statins passively and non-selectively diffuse into both hepatocyte and non-heptatocyte, while the hydrophilic statins rely largely on active transport into hepatocyte to exert their effects. High hepatoselectivity is thought to translate into reduced risk of adverse effects. It has been reported that the organic anion transporting polypeptide (OATP) is important for the hepatic uptake of hydrophilic statins such as rosuvastatin and pravastatin. OATP-C is expressed in liver tissue on the basolateral membrane of hepatocytes and is considered to be a potential contributor for the low IC for rosuvastatin in hepatocytes. Of the marketed statins, cerivastatin was the most lipophilic and also had the largest percentage of serious adverse effects due to its ability to inhibit vascular smooth muscle proliferation and as a result was voluntarily removed from the market by the manufacturer. | 1 | Applied and Interdisciplinary Chemistry |
In addition to the use of the multiprotein complexes listed above, gram-negative bacteria possess another method for release of material: the formation of outer membrane vesicles. Portions of the outer membrane pinch off, forming spherical structures made of a lipid bilayer enclosing periplasmic materials. Vesicles from a number of bacterial species have been found to contain virulence factors, some have immunomodulatory effects, and some can directly adhere to and intoxicate host cells. While release of vesicles has been demonstrated as a general response to stress conditions, the process of loading cargo proteins seems to be selective. | 1 | Applied and Interdisciplinary Chemistry |
There are three types of viral infections that can be considered under the topic of viral transformation. These are cytocidal, persistent, and transforming infections. Cytocidal infections can cause fusion of adjacent cells, disruption of transport pathways including ions and other cell signals, disruption of DNA, RNA and protein synthesis, and nearly always leads to cell death. Persistent infections involve viral material that lays dormant within a cell until activated by some stimulus. This type of infection usually causes few obvious changes within the cell but can lead to long chronic diseases. Transforming infections are also referred to as malignant transformation. This infection causes a host cell to become malignant and can be either cytocidal (usually in the case of RNA viruses) or persistent (usually in the case of DNA viruses). Cells with transforming infections undergo immortalization and inherit the genetic material to produce tumors. Since the term cytocidal, or cytolytic, refers to cell death, these three infections are not mutually exclusive. Many transforming infections by DNA tumor viruses are also cytocidal.
Table 1: Cellular effects of viral infections
Rounding of the cell<br/>
Fusion with adjacent cells<br/>
Appearance of inclusion bodies
Inhibit DNA, RNA, and protein synthesis<br/>
Interfere with sub-cellular interactions
Insufficient movement of ions<br/>
Formation of secondary messengers<br/>
Activation of cellular cascades
| Persistent ||
Fusion with adjacent cells<br/>
Appearance of inclusion bodies<br/>
Budding
Immune responses limit viral spread<br/>
Antigen-antibody complexes can incorporate <br/>viral antigens causing inflammation
Rare until stimulated
| Transforming ||
Unlimited cell replication
Inactivates tumor suppressor proteins<br/>
Impairs cell cycle regulation
Unlimited cell replication | 1 | Applied and Interdisciplinary Chemistry |
In atmospheric sciences, one often refers to the optical depth of the atmosphere as corresponding to the vertical path from Earths surface to outer space; at other times the optical path is from the observers altitude to outer space. The optical depth for a slant path is , where τ′ refers to a vertical path, m is called the relative airmass, and for a plane-parallel atmosphere it is determined as where θ is the zenith angle corresponding to the given path. Therefore,The optical depth of the atmosphere can be divided into several components, ascribed to Rayleigh scattering, aerosols, and gaseous absorption. The optical depth of the atmosphere can be measured with a Sun photometer.
The optical depth with respect to the height within the atmosphere is given by and it follows that the total atmospheric optical depth is given by
In both equations:
* k is the absorption coefficient
* w is the mixing ratio
* ρ is the density of air at sea level
* H is the scale height of the atmosphere
* z is the height in question
The optical depth of a plane parallel cloud layer is given bywhere:
* Q is the extinction efficiency
* L is the liquid water path
* H is the geometrical thickness
* N is the concentration of droplets
* ρ is the density of liquid water
So, with a fixed depth and total liquid water path, . | 0 | Theoretical and Fundamental Chemistry |
Ions that hit the doorknob release secondary electrons. A high voltage (about ) between the doorknob and the scintillator accelerates the electrons onto the phosphor screen, where they are converted to photons. These photons are detected by the photomultiplier.
The advantage of the Daly detector is that the photomultiplier can be separated by a window, which lets the photons through from the high vacuum of the mass spectrometer, thus preventing an otherwise possible contamination and extending life span of the detector. The Daly detector also allows a higher acceleration after the field-free region of a time-of-flight mass spectrometer flight tube, which can improve the sensitivity for heavy ions. | 0 | Theoretical and Fundamental Chemistry |
Beginning in the early 1900s, modern chemistry sets targeted younger people with the intention to popularize chemistry. In the United States, Porter Chemical Company and the A. C. Gilbert Company produced the best known sets. Although Porter and Gilbert were the largest American producers of chemistry sets, other manufacturers such as the Skilcraft corporation were also active.
John J. Porter and his brother Harold Mitchell Porter began The Porter Chemical Company in 1914. Their initial purpose was to sell packaged chemicals, but they soon introduced kits. John researched the experiments, while Harold wrote the instruction manuals. Their earliest toys, under the "Chemcraft" trademark, were "chemical magic" sets, selling for less than one dollar (or about $25 in 2017). By the 1920s, they sold six different sets, the largest of which sold for $25 (or about $320 in 2017). Their range of toys broadened throughout the 1930s. In the 1950s it was possible to buy toys featuring radioactive ores, such as the "Gilbert U-238 Atomic Energy Laboratory," which included a Geiger counter and cloud chamber.
Alfred Carlton Gilbert earned money by performing magic tricks while a medical student at Yale. He and John Petrie formed the Mysto Manufacturing Company (later the A. C. Gilbert Company) in 1909, and began selling boxed magic sets. By 1917, they sold chemistry sets, which they produced through World War II, in spite of restrictions on materials. Robert Treat Johnson, noting the number of chemistry students at Yale whose interest in the science began with a chemistry set, argued the production of chemistry sets was a "patriotic duty."
Toy companies promoted chemistry sets through advertising campaigns, the "Chemcraft Chemist Club" and its accompanying "Chemcraft Science Magazine", comic books, and essay contests such as Porters "Why I want to be a scientist". The goal of attracting students to a potential career in chemistry was often explicit in the sets naming and promotion. Chemistry sets may have been the first American toys marketed toward parents with the goal of "improving" children for success in later life.
The target market for chemistry sets was almost exclusively boys, deemed "young men of science." However, during the 1950s, Gilbert introduced a set targeting girls. They sold the set in an attractive pink box, but the set identified girls as "laboratory assistants" or "lab technicians," not scientists.
In 1971, a Johnny Horizon Environmental Test Kit was licensed by the U. S. Department of the Interior and produced by Parker Brothers. It included four air pollution tests and six water pollution tests for young environmental scientists.
The Johnny Horizon Environmental Test Kit was marketed to both boys and girls.
Well-known chemistry sets from the United Kingdom include the 1960s and 1970s sets by Thomas Salter Science (produced in Scotland) and later Salter Science, then the "MERIT" sets through the 1970s and 1980s. Dekkertoys created a range of sets which were similar, complete with glass test tubes of dry chemicals. | 1 | Applied and Interdisciplinary Chemistry |
Most NONOates are stable in alkaline solution above pH 8.0 (e. g. 10 mM NaOH) and can be stored at −20 °C in this way for the short term. To generate NO from NONOates, the pH is lowered accordingly. Typically, a dilution of the stock NONOate solution is made in a phosphate buffer (pH 7.4; tris buffers can also be used) and incubated at room temperature for the desired time to allow NO to accumulate in solution. This is often visible as bubbles at high NONOate concentrations. Incubation time is important, since the different NONOates have different half-lives (t) in phosphate buffer at pH 7.4. For example, the half-life of MAHMA NONOate under these conditions is ~3.5 minutes, whilst the t of DPTA NONOate is 300 minutes. This is often useful in biological systems, where a combination of different NONOates can be used to give a sustained release of nitric oxide. At pH 5.0, most NONOates are considered to decompose almost instantaneously. | 0 | Theoretical and Fundamental Chemistry |
Synthesis of DDQ involves cyanation of chloranil. J. Thiele and F. Günther first reported a 6-step preparation in 1906. The substance did not receive interest until its potential as a dehydrogenation agent was discovered. A single-step chlorination from 2,3-dicyanohydroquinone was reported in 1965. | 0 | Theoretical and Fundamental Chemistry |
Consider the reaction below:
The two elements involved, iron and chlorine, each change oxidation state; iron from +2 to +3, chlorine from 0 to −1. There are then effectively two half reactions occurring. These changes can be represented in formulas by inserting appropriate electrons into each half reaction:
Given two half reactions it is possible, with knowledge of appropriate electrode potentials, to arrive at the complete (original) reaction the same way. The decomposition of a reaction into half reactions is key to understanding a variety of chemical processes. For example, in the above reaction, it can be shown that this is a redox reaction in which Fe is oxidised, and Cl is reduced. Note the transfer of electrons from Fe to Cl. Decomposition is also a way to simplify the balancing of a chemical equation. A chemist can atom balance and charge balance one piece of an equation at a time.
For example:
* becomes
* is added to
* and finally becomes
It is also possible and sometimes necessary to consider a half reaction in either basic or acidic conditions, as there may be an acidic or basic electrolyte in the redox reaction. Due to this electrolyte it may be more difficult to satisfy the balance of both the atoms and charges. This is done by adding , and/or to either side of the reaction until both atoms and charges are balanced.
Consider the half reaction below:
, and can be used to balance the charges and atoms in basic conditions, as long as it is assumed that the reaction is in water.
Again consider the half reaction below:
, and can be used to balance the charges and atoms in acidic conditions, as long as it is assumed that the reaction is in water.
Notice that both sides are both charge balanced and atom balanced.
Often there will be both and present in acidic and basic conditions but that the resulting reaction of the two ions will yield water, (shown below): | 0 | Theoretical and Fundamental Chemistry |
Soon after the Big Bang, which occurred roughly 14 Gya, the only chemical elements present in the universe were hydrogen, helium, and lithium, the three lightest atoms in the periodic table. These elements gradually accreted and began orbiting in disks of gas and dust. Gravitational accretion of material at the hot and dense centers of these protoplanetary disks formed stars by the fusion of hydrogen. Early stars were massive and short-lived, producing all the heavier elements through stellar nucleosynthesis. Element formation through stellar nucleosynthesis proceeds to its most stable element Iron-56. Heavier elements were formed during supernovae at the end of a stars lifecycle. Carbon, currently the fourth most abundant chemical element in the universe (after hydrogen, helium, and oxygen), was formed mainly in white dwarf stars, particularly those bigger than twice the mass of the sun. As these stars reached the end of their lifecycles, they ejected these heavier elements, among them carbon and oxygen, throughout the universe. These heavier elements allowed for the formation of new objects, including rocky planets and other bodies. According to the nebular hypothesis, the formation and evolution of the Solar System began 4.6 Gya with the gravitational collapse of a small part of a giant molecular cloud. Most of the collapsing mass collected in the center, forming the Sun, while the rest flattened into a protoplanetary disk out of which the planets, moons, asteroids, and other small Solar System bodies formed. | 0 | Theoretical and Fundamental Chemistry |
Since multiple studies have shown that RNA Pol II can be found at a very large number of extragenic regions, it is possible that eRNAs simply represent the product of random “leaky” transcription and carry no functional significance. The non-specific activity of RNA Pol II would therefore allow extragenic transcriptional noise at sites where chromatin is already in an open and transcriptionally competent state. This would explain even tissue-specific eRNA expression as open sites are tissue-specific as well. | 1 | Applied and Interdisciplinary Chemistry |
Tritiation of drug candidates allows detailed analysis of their absorption and metabolism. Tritium has also been used for biological radiometric assays, in a process akin to radiocarbon dating. For example, [H] retinyl acetate was traced through the bodies of rats. | 0 | Theoretical and Fundamental Chemistry |
Sedative hypnotic drugs including eszopiclone are more commonly prescribed to the elderly than to younger patients despite benefits of medication being generally unimpressive.
In 2015, the American Geriatrics Society reviewed the safety information about eszopiclone and similar drugs and concluded that the "nonbenzodiazepine, benzodiazepine receptor agonist hypnotics (eszopiclone, zaleplon, zolpidem) are to be avoided without consideration of duration of use because of their association with harms balanced with their minimal efficacy in treating insomnia."
The review made this determination both because of the relatively large dangers to elderly individuals from zolpidem and other "z-drugs" together with the fact the drugs have "minimal efficacy in treating insomnia." This was a change from the 2012 AGS recommendation, which suggested limiting use to 90 days or less. The review stated: "the 90‐day‐use caveat [was] removed from nonbenzodiazepine, benzodiazepine receptor agonist hypnotics, resulting in an unambiguous avoid statement (without caveats) because of the increase in the evidence of harm in this area since the 2012 update."
An extensive review of the medical literature regarding the management of insomnia and the elderly found that there is considerable evidence of the effectiveness and durability of non-drug treatments for insomnia in adults of all ages and that these interventions are underutilized. Compared with the benzodiazepines, the nonbenzodiazepine sedative-hypnotics, including eszopiclone appeared to offer few, if any, significant clinical advantages in efficacy or tolerability in elderly persons. It was found that newer agents with novel mechanisms of action and improved safety profiles, such as the melatonin receptor agonists, hold promise for the management of chronic insomnia in elderly people. Long-term use of sedative-hypnotics for insomnia lacks an evidence base and has traditionally been discouraged for reasons that include concerns about such potential adverse drug effects as cognitive impairment (anterograde amnesia), daytime sedation, motor incoordination, and increased risk of motor vehicle accidents and falls. In addition, the effectiveness and safety of long-term use of these agents remain to be determined. It was concluded that more research is needed to evaluate the long-term effects of treatment and the most appropriate management strategy for elderly persons with chronic insomnia.
A 2009 meta-analysis found a higher rate of infections. | 0 | Theoretical and Fundamental Chemistry |
Flotufolastat F-18 is indicated for positron emission tomography of prostate-specific membrane antigen positive lesions in men with prostate cancer. | 1 | Applied and Interdisciplinary Chemistry |
The term electronic sputtering can mean either sputtering induced by energetic electrons (for example in a transmission electron microscope), or sputtering due to very high-energy or highly charged heavy ions that lose energy to the solid, mostly by electronic stopping power, where the electronic excitations cause sputtering. Electronic sputtering produces high sputtering yields from insulators, as the electronic excitations that cause sputtering are not immediately quenched, as they would be in a conductor. One example of this is Jupiters ice-covered moon Europa, where a MeV sulfur ion from Jupiters magnetosphere can eject up to 10,000 HO molecules. | 0 | Theoretical and Fundamental Chemistry |
One general form of cell engineering involves altering natural cell production to achieve a more desirable yield or shorter production time. A possible method for changing natural cell production includes boosting or repressing genes that are involved in the metabolism of the product. For example, researchers were able to overexpress transporter genes in hamster ovary cells to increase monoclonal antibody yield. Another approach could involve incorporating biologically foreign genes into an existing cell line. For example, E.Coli, which synthesizes ethanol, can be modified using genes from Zymomonas mobilis to make ethanol fermentation the primary cell fermentation product. | 1 | Applied and Interdisciplinary Chemistry |
* Mestel. J. [http://www.ma.ic.ac.uk/~ajm8/M4A33/taylor.pdf Taylor dispersion — shear augmented diffusion], Lecture Handout for Course M4A33, Imperial College. | 1 | Applied and Interdisciplinary Chemistry |
DNA separation by silica adsorption is a method of DNA separation that is based on DNA molecules binding to silica surfaces in the presence of certain salts and under certain pH conditions. | 1 | Applied and Interdisciplinary Chemistry |
The word chemistry derives from the word alchemy, which is found in various forms in European languages. Alchemy derives from the Arabic word kimiya () or al-kīmiyāʾ (). The Arabic term is derived from the Ancient Greek , khēmia, or , khēmeia, art of alloying metals, from χύμα (khúma, “fluid”), from χέω (khéō, “I pour”).
However, the ultimate origin of the word is uncertain.
According to the Oxford English Dictionary, al-kīmiyāʾ may be derived from the greek , which is derived from the ancient Egyptian name of Egypt, khem or khm, khame, or khmi, meaning "blackness", i.e., the rich dark soil of the Nile river valley. Therefore, alchemy can be seen as the "Egyptian art" or the "black art". However, it is also possible that al-kīmiyāʾ derived from , meaning "cast together". | 1 | Applied and Interdisciplinary Chemistry |
Side effects seen more often with levomilnacipran than with placebo in clinical trials included nausea, dizziness, sweating, constipation, insomnia, increased heart rate and blood pressure, urinary hesitancy, erectile dysfunction and delayed ejaculation in males, vomiting, tachycardia, and palpitations. | 0 | Theoretical and Fundamental Chemistry |
Cross-phase modulation is caused by the Kerr effect, in which the refractive index of the specimen changes in the presence of a large electric field. In this case, the pump beam modulates the phase of the probe, which can then be measured through interferometric techniques. In certain cases, referred to as cross-phase modulation spectral shifting, this phase change induces a change to the pump spectrum that can be detected with a spectral filter. | 0 | Theoretical and Fundamental Chemistry |
Polyaniline nanofibers have been used in the creation of monolithic actuators. They can be used in this application due to their ability to be flash-welded. When exposed to light, polyaniline converts the absorbed energy directly into heat. In a polyaniline film, the heat is dispersed throughout the polymer. In polyaniline nanofibers, however, the heat is trapped within the individual fibers. Therefore, if the intensity of the light is great enough, it will cause the temperature of the nanofibers to rise rapidly, which causes them to weld together or burn. With a moderate flash intensity, the nanofibers will melt rapidly to form a smooth film. Using mask, welds in specific patterns can be made using this technique. In a thick enough sample of nanofibers, only the side exposed to the flash will be welded, creating an asymmetric film where one side remains intact as nanofibers while the other side is effectively crosslinked due to welding. These asymmetric films demonstrate rapid reversible actuation in the presence of acids and bases, in the form of bending and curling. The advantages polyaniline nanofiber asymmetric films have over other actuators include the ease of synthesis, large degree of bending, patternability, and no delamination. These actuators could be used in the development of microtweezers, microvalves, artificial muscles, chemical sensors, and patterned actuator structures. | 0 | Theoretical and Fundamental Chemistry |
Acid sulfate soils are widespread around coastal regions, and are also locally associated with freshwater wetlands and saline sulfate-rich groundwater in some agricultural areas. In Australia, coastal acid sulfate soils occupy an estimated 58,000 km, underlying coastal estuaries and floodplains near where the majority of the Australian population lives. Acid sulfate soil disturbance is often associated with dredging, excavation dewatering activities during canal, housing and marina developments. Droughts can also result in acid sulfate soil exposure and acidification. | 0 | Theoretical and Fundamental Chemistry |
Many researches claim that nanoparticles can be used to enhance crude oil recovery. It is evident that development of nanofluids for oil and gas industry has a great practical aspects. | 0 | Theoretical and Fundamental Chemistry |
Lotka said (1922b: 151):
Gilliland noted that these difficulties in analysis in turn required some new theory to adequately explain the interactions and transactions of these different energies (different concentrations of fuels, labour and environmental forces). Gilliland (Gilliland 1978, p. 101) suggested that Odum's statement of the maximum power principle (H.T.Odum 1978, pp. 54–87) was, perhaps, an adequate expression of the requisite theory:
This theory Odum called maximum power theory. In order to formulate maximum power theory Gilliland observed that Odum had added another law (the maximum power principle) to the already well established laws of thermodynamics. In 1978 Gilliland wrote that Odum's new law had not yet been validated (Gilliland 1978, p. 101). Gilliland stated that in maximum power theory the second law efficiency of thermodynamics required an additional physical concept: "the concept of second law efficiency under maximum power" (Gilliland 1978, p. 101):
In this way the concept of maximum power was being used as a principle to quantitatively describe the selective law of biological evolution. Perhaps H.T.Odum's most concise statement of this view was (1970, p. 62):
The Odum–Pinkerton approach to Lotkas proposal was to apply Ohms law – and the associated maximum power theorem (a result in electrical power systems) – to ecological systems. Odum and Pinkerton defined "power" in electronic terms as the rate of work, where Work is understood as a "useful energy transformation". The concept of maximum power can therefore be defined as the maximum rate of useful energy transformation. Hence the underlying philosophy aims to unify the theories and associated laws of electronic and thermodynamic systems with biological systems. This approach presupposed an analogical view which sees the world as an ecological-electronic-economic engine. | 0 | Theoretical and Fundamental Chemistry |
In IUPAC nomenclature of chemistry, a pendant group (sometimes spelled pendent) or side group is a group of atoms attached to a backbone chain of a long molecule, usually a polymer. Pendant groups are different from pendant chains, as they are neither oligomeric nor polymeric.
For example, the phenyl groups are the pendant groups on a polystyrene chain.
Large, bulky pendant groups such as adamantyl usually raise the glass transition temperature () of a polymer by preventing the chains from sliding past each other easily. Short alkyl pendant groups may lower the by a lubricant effect. | 0 | Theoretical and Fundamental Chemistry |
The pH value at the surface of oceans in pre-industrial time (before 1850) was around 8.2. Since then, it has been decreasing due to a human-caused process called ocean acidification that is related to carbon dioxide emissions: Between 1950 and 2020, the average pH of the ocean surface fell from approximately 8.15 to 8.05.
The pH value of seawater is naturally as low as 7.8 in deep ocean waters as a result of degradation of organic matter in these waters. It can be as high as 8.4 in surface waters in areas of high biological productivity.
Measurement of pH is complicated by the chemical properties of seawater, and several distinct pH scales exist in chemical oceanography. There is no universally accepted reference pH-scale for seawater and the difference between measurements based on different reference scales may be up to 0.14 units. | 0 | Theoretical and Fundamental Chemistry |
2-deoxy-2,3-didehydro-N-acetylneuraminic acid (Neu5Ac2en) is a pan-selective inhibitor for neuraminidase. Neu5Ac2en is a dehydrogenated Neu5Ac and can be synthesized by the hNEU enzyme if Neu5Ac is in high enough concentration. Neu5Ac is also a mild inhibitor for the enzyme but as Neu5Ac2en is a transition-state analogue it is a much better inhibitor. | 1 | Applied and Interdisciplinary Chemistry |
Dicarbollides are obtained by base-degradation of 12-vertex dicarboranes. This degradation of the ortho derivative has been most heavily studied. The conversion is conducted in two-steps, first "deboronation" and second deprotonation:
:CBH + NaOEt + 2 EtOH → NaCBH + H + B(OEt)
:NaCBH + NaH → NaCBH + H
The dianion derived from dicarboranes, [CBH], are nido clusters. Three isomers exist. Most commonly studies is the 7,8-isomer, with two adjacent carbon centers on the rim. 7,9- has non-adjacent carbon centers on the rim. It is derived by degradation of meta-. 2,9- has only one carbon center on the rim. It is derived by degradation of para-. | 0 | Theoretical and Fundamental Chemistry |
Primary metabolites are compounds made during the ordinary metabolism of the organism during the growth phase. A common example is ethanol or lactic acid, produced during glycolysis. Citric acid is produced by some strains of Aspergillus niger as part of the citric acid cycle to acidify their environment and prevent competitors from taking over. Glutamate is produced by some Micrococcus species, and some Corynebacterium species produce lysine, threonine, tryptophan and other amino acids. All of these compounds are produced during the normal "business" of the cell and released into the environment. There is therefore no need to rupture the cells for product recovery. | 1 | Applied and Interdisciplinary Chemistry |
Wong et al. developed a surface inspired by the system on the pitcher plant. This surface, named “slippery liquid-infused porous surfaces” (SLIPS) is a micro- or nano-porous substrate, with a lubricating liquid locked in place. For the system to work, the lubricating liquid must fully wet the substrate, the solid must be preferentially wetted by the lubricating substrate when compared to the repelling substrate, and the lubricating and encroaching liquid must be immiscible. Although the concept of SLIPS was biomimetic of the pitcher plant, it is not superhydrophilic with a contact angle of 116°, though it does repel blood and oil. | 0 | Theoretical and Fundamental Chemistry |
If a compound has a very large specific rotation or a sample is very concentrated, the actual rotation of the sample may be larger than 180°, and so a single polarimeter measurement cannot detect when this has happened (for example, the values +270° and −90° are not distinguishable, nor are the values 361° and 1°). In these cases, measuring the rotation at several different concentrations allows one to determine the true value. Another method would be to use shorter path-lengths to perform the measurements.
In cases of very small or very large angles, one can also use the variation of specific rotation with wavelength to facilitate measurement. Switching wavelength is particularly useful when the angle is small. Many polarimeters are equipped with a mercury lamp (in addition to the sodium lamp) for this purpose. | 0 | Theoretical and Fundamental Chemistry |
Building codes and local government ordinances vary greatly on the handling of storm drain runoff. New developments might be required to construct their own storm drain processing capacity for returning the runoff to the water table and bioswales may be required in sensitive ecological areas to protect the watershed.
In the United States, cities, suburban communities and towns with over 10,000 population are required to obtain discharge permits for their storm sewer systems, under the Clean Water Act. The Environmental Protection Agency (EPA) issued stormwater regulations for large cities in 1990 and for other communities in 1999. The permits require local governments to operate stormwater management programs, covering both construction of new buildings and facilities, and maintenance of their existing municipal drainage networks. For new construction projects, many municipalities require builders to obtain approval of the site drainage system along with the structural plans. State government facilities, such as roads and highways, are also subject to the stormwater management regulations. | 1 | Applied and Interdisciplinary Chemistry |
Like Sisyphus cooling, the cooling mechanism of gray molasses relies on a two-photon Raman-type transition between two hyperfine-split ground states mediated by an excited state. Orthogonal superpositions of these ground states constitute "bright" and "dark" states, so called since the former couples to the excited state via dipole transitions driven by the laser, and the latter is only accessible via spontaneous emission from the excited state. As neither are eigenstates of the kinetic energy operator, the dark state also evolves into the bright state with frequency proportional to the atom's external momentum. Gradients in the polarization of the molasses beam create a sinusoidal potential energy landscape for the bright state in which atoms lose kinetic energy by traveling "uphill" to potential energy maxima that coincide with circular polarizations capable of executing electric dipole transitions to the excited state. Atoms in the excited state are then optically pumped to the dark state and subsequently evolve back to the bright state to restart the cycle. Alternately, the pair of bright and dark ground states can be generated by electromagnetically-induced transparency (EIT).
The net effect of many cycles from bright to excited to dark states is to subject atoms to Sisyphus-like cooling in the bright state and select the coldest atoms to enter the dark state and escape the cycle. The latter process constitutes velocity-selective coherent population trapping (VSCPT).
The combination of bright and dark states thus inspires the name "gray molasses." | 0 | Theoretical and Fundamental Chemistry |
AMS counts the atoms of and in a given sample, determining the / ratio directly. The sample, often in the form of graphite, is made to emit C ions (carbon atoms with a single negative charge), which are injected into an accelerator. The ions are accelerated and passed through a stripper, which removes several electrons so that the ions emerge with a positive charge. The ions, which may have from 1 to 4 positive charges (C to C), depending on the accelerator design, are then passed through a magnet that curves their path; the heavier ions are curved less than the lighter ones, so the different isotopes emerge as separate streams of ions. A particle detector then records the number of ions detected in the stream, but since the volume of (and , needed for calibration) is too great for individual ion detection, counts are determined by measuring the electric current created in a Faraday cup. The large positive charge induced by the stripper forces molecules such as , which has a weight close enough to to interfere with the measurements, to dissociate, so they are not detected. Most AMS machines also measure the samples , for use in calculating the samples radiocarbon age. The use of AMS, as opposed to simpler forms of mass spectrometry, is necessary because of the need to distinguish the carbon isotopes from other atoms or molecules that are very close in mass, such as and . As with beta counting, both blank samples and standard samples are used. Two different kinds of blank may be measured: a sample of dead carbon that has undergone no chemical processing, to detect any machine background, and a sample known as a process blank made from dead carbon that is processed into target material in exactly the same way as the sample which is being dated. Any signal from the machine background blank is likely to be caused either by beams of ions that have not followed the expected path inside the detector or by carbon hydrides such as or . A signal from the process blank measures the amount of contamination introduced during the preparation of the sample. These measurements are used in the subsequent calculation of the age of the sample. | 0 | Theoretical and Fundamental Chemistry |
Maximum entropy spectral estimation is a method of spectral density estimation. The goal is to improve the spectral quality based on the principle of maximum entropy. The method is based on choosing the spectrum which corresponds to the most random or the most unpredictable time series whose autocorrelation function agrees with the known values. This assumption, which corresponds to the concept of maximum entropy as used in both statistical mechanics and information theory, is maximally non-committal with regard to the unknown values of the autocorrelation function of the time series. It is simply the application of maximum entropy modeling to any type of spectrum and is used in all fields where data is presented in spectral form. The usefulness of the technique varies based on the source of the spectral data since it is dependent on the amount of assumed knowledge about the spectrum that can be applied to the model.
In maximum entropy modeling, probability distributions are created on the basis of that which is known, leading to a type of statistical inference about the missing information which is called the maximum entropy estimate. For example, in spectral analysis the expected peak shape is often known, but in a noisy spectrum the center of the peak may not be clear. In such a case, inputting the known information allows the maximum entropy model to derive a better estimate of the center of the peak, thus improving spectral accuracy. | 0 | Theoretical and Fundamental Chemistry |
Elongating polymerase is associated with a set of protein factors required for various types of RNA processing. mRNA is capped as soon as it emerges from the RNA-exit channel of the polymerase. After capping, dephosphorylation of Ser-5 within the CTD repeats may be responsible for dissociation of the capping machinery. Further phosphorylation of Ser-2 causes recruitment of the RNA splicing machinery that catalyzes the removal of non-coding introns to generate mature mRNA. Alternative splicing expands the protein complements in eukaryotes. Just as with 5’-capping and splicing, the CTD tail is involved in recruiting enzymes responsible for 3’-polyadenylation, the final RNA processing event that is coupled with the termination of transcription. | 1 | Applied and Interdisciplinary Chemistry |
Primary chloroplasts are cell organelles found in some eukaryotic lineages, where they are specialized in performing photosynthesis. They are considered to have evolved from endosymbiotic cyanobacteria. After some years of debate, it is now generally accepted that the three major groups of primary endosymbiotic eukaryotes (i.e. green plants, red algae and glaucophytes) form one large monophyletic group called Archaeplastida, which evolved after one unique endosymbiotic event.
The morphological similarity between chloroplasts and cyanobacteria was first reported by German botanist Andreas Franz Wilhelm Schimper in the 19th century Chloroplasts are only found in plants and algae, thus paving the way for Russian biologist Konstantin Mereschkowski to suggest in 1905 the symbiogenic origin of the plastid. Lynn Margulis brought this hypothesis back to attention more than 60 years later but the idea did not become fully accepted until supplementary data started to accumulate. The cyanobacterial origin of plastids is now supported by various pieces of phylogenetic, genomic, biochemical and structural evidence. The description of another independent and more recent primary endosymbiosis event between a cyanobacterium and a separate eukaryote lineage (the rhizarian Paulinella chromatophora) also gives credibility to the endosymbiotic origin of the plastids.
In addition to this primary endosymbiosis, many eukaryotic lineages have been subject to secondary or even tertiary endosymbiotic events, that is the "Matryoshka-like" engulfment by a eukaryote of another plastid-bearing eukaryote.
Chloroplasts have many similarities with cyanobacteria, including a circular chromosome, prokaryotic-type ribosomes, and similar proteins in the photosynthetic reaction center. The endosymbiotic theory suggests that photosynthetic bacteria were acquired (by endocytosis) by early eukaryotic cells to form the first plant cells. Therefore, chloroplasts may be photosynthetic bacteria that adapted to life inside plant cells. Like mitochondria, chloroplasts still possess their own DNA, separate from the nuclear DNA of their plant host cells and the genes in this chloroplast DNA resemble those in cyanobacteria. DNA in chloroplasts codes for redox proteins such as photosynthetic reaction centers. The CoRR hypothesis proposes this co-location is required for redox regulation. | 0 | Theoretical and Fundamental Chemistry |
Englishman William Haynes patented a process in 1860 for separating sulfide and gangue minerals using oil. Later writers have pointed to Haynes's as the first "bulk oil flotation" patent, though there is no evidence of its being field tested, or used commercially. In 1877 the brothers Bessel (Adolph and August) of Dresden, Germany, introduced their commercially successful oil and froth flotation process for extracting graphite, considered by some the root of froth flotation. However, the Bessel process became uneconomical after the discovery of high-grade graphite in Sri Lanka and was largely forgotten.
Inventor Hezekiah Bradford of Philadelphia invented a "method of saving floating material in ore-separation” and received US patent No. 345951 on July 20, 1886. He would later go on to patent the Bradford Breaker, currently in use by the coal industry, in 1893. His "Bradford washer," patented 1870, was used to concentrate iron, copper and lead-zinc ores by specific gravity, but lost some of the metal as float off the concentration process. The 1886 patent was to capture this "float" using surface tension, the first of the skin-flotation process patents that were eclipsed by oil froth flotation.
On August 24, 1886, Carrie Everson received a patent for her process calling for oil[s] but also an acid or a salt, a significant step in the evolution of the process history. By 1890, tests of the Everson process had been made at Georgetown and Silver Cliff, Colorado, and Baker, Oregon. She abandoned the work upon the death of her husband, and before perfecting a commercially successful process. Later, during the height of legal disputes over the validity of various patents during the 1910s, Everson's was often pointed to as the initial flotation patent - which would have meant that the process was not patentable again by later contestants. Much confusion has been clarified recently by historian Dawn Bunyak. | 1 | Applied and Interdisciplinary Chemistry |
A major bulk of work in the synthesis of lovastatin was done by M. Hirama in the 1980s.
Hirama synthesized compactin and used one of the intermediates to follow a different path to get to lovastatin. The synthetic sequence is shown in the schemes below. The γ-lactone was synthesized using Yamada methodology starting with glutamic acid. Lactone opening was done using lithium methoxide in methanol and then silylation to give a separable mixture of the starting lactone and the silyl ether. The silyl ether on hydrogenolysis followed by Collins oxidation gave the aldehyde. Stereoselective preparation of (E,E)-diene was accomplished by addition of trans-crotyl phenyl sulfone anion, followed by quenching with AcO and subsequent reductive elimination of sulfone acetate. Condensation of this with lithium anion of dimethyl methylphosphonate gave compound 1. Compound 2 was synthesized as shown in the scheme in the synthetic procedure. Compounds 1 and 2 were then combined using 1.3 eq sodium hydride in THF followed by reflux in chlorobenzene for 82 hr under nitrogen to get the enone 3.
Simple organic reactions were used to get to lovastatin as shown in the scheme. | 0 | Theoretical and Fundamental Chemistry |
In classic polarography, the standard addition method involves creating two samples – one sample without any spikes, and another one with spikes. By comparing the current measured from two samples, the amount of analyte in the unknown is determined. This approach was the first reported use of standard addition, and was introduced by a German mining chemist, Hans Hohn, in 1937. In his polarography practical book, titled Chemische Analysen mit dem Polargraphen, Hohn referred this method as Eizhusatzes, which translates to "calibration addition" in English. Later in the German literature, this method was called as Standardzugabe, meaning "standard addition" in English.
Modern polarography typically involves using three solutions: the standard solution, the unknown solution, and a mixture of the standard and unknown solution. By measuring any two of these solutions, the unknown concentration is calculated.
As polarographic standard addition involves using only one solution with the standard added – the two-level design, polarographers always refer to the method as singular, standard addition. | 0 | Theoretical and Fundamental Chemistry |
Sterilization is an important factor to consider during the fermentation of foods. Failing to completely remove any microbes from equipment and storing vessels may result in the multiplication of harmful organisms within the ferment, potentially increasing the risks of food borne illnesses like botulism. However, botulism in vegetable ferments is only possible when not properly canned. The production of off smells and discoloration may be indications that harmful bacteria may have been introduced to the food.
Alaska has witnessed a steady increase of cases of botulism since 1985. It has more cases of botulism than any other state in the United States of America. This is caused by the traditional Alaska Native practice of allowing animal products such as whole fish, fish heads, walrus, sea lion, and whale flippers, beaver tails, seal oil, and birds, to ferment for an extended period of time before being consumed. The risk is exacerbated when a plastic container is used for this purpose instead of the old-fashioned, traditional method, a grass-lined hole, as the Clostridium botulinum bacteria thrive in the anaerobic conditions created by the air-tight enclosure in plastic.
The World Health Organization has classified pickled foods as possibly carcinogenic, based on epidemiological studies. Other research found that fermented food contains a carcinogenic by-product, ethyl carbamate (urethane). "A 2009 review of the existing studies conducted across Asia concluded that regularly eating pickled vegetables roughly doubles a person's risk for esophageal squamous cell carcinoma." | 1 | Applied and Interdisciplinary Chemistry |
Specific ultraviolet absorbance (SUVA) is the absorbance of ultraviolet light in a water sample at a specified wavelength that is normalized for dissolved organic carbon (DOC) concentration. Specific UV absorbance (SUVA) wavelengths have analytical uses to measure the aromatic character of dissolved organic matter by detecting density of electron conjugation which is associated with aromatic bonds. | 0 | Theoretical and Fundamental Chemistry |
* Orthodontic items, such as wires and foams for endovascular procedures.
* Microelements for intelligent suturing.
* Intravenous needles that soften in the body and laparoscopy devices
* Drug delivery systems.
* In-body degradable implants for minimally invasive surgeries.
* Inner soles of orthopedic or special needs shoes and utensils for people with disabilities.
* Intravenous catheters. | 0 | Theoretical and Fundamental Chemistry |
The above calculations for NNT are valid under monotonicity, where treatment can't have a negative effect on any individual. However, in the case where the treatment may benefit some individuals and harm others, the NNT as defined above cannot be estimated from a Randomized Controlled Trial (RCT) alone. The inverse of the absolute risk reduction only provides an upper bound, i.e., .
The modern approach defines NNT literally, as the number of patients one needs to treat (on the average) before saving one. However, since "saving" is a counterfactual notion (a patient must recover if treated and not recover if not treated) the logic of counterfactuals must be invoked to estimate this quantity from experimental or observational studies. The probability of "saving" is captured by the Probability of Necessity and Sufficiency (PNS), where
. Once PNS is estimated, NNT is given as . However, due to the counterfactual nature of PNS, only bounds can be computed from an RCT, rather than a precise estimate. Tian and Pearl have derived tight bounds on PNS, based on multiple data sources, and Pearl showed that a combination of observational and experimental data may sometimes make the bounds collapse to a point estimate. Mueller and Pearl provide a conceptual interpretation for this phenomenon and illustrate its impact on both individual and policy-makers decisions. | 1 | Applied and Interdisciplinary Chemistry |
*Development of the Pennsylvania oil industry by Edwin Drake and Samuel Kier in the 1850s
*Deciphering of the genetic code by Marshall Warren Nirenberg and J. Heinrich Matthaei at the National Institutes of Health in the 1960s | 1 | Applied and Interdisciplinary Chemistry |
The cleanup process started when there was a survey of Manhattan Project sites. The plant was inspected in 1976 and found low levels of radiation. Westinghouse filed an application in 1988 with the Nuclear Regulatory Commission (NRC) to decommission those buildings. The demolition of the buildings was done from 1993 through 2004. During that period, certain radioactive contamination was removed from the site. However, some contaminated areas were covered with asphalt and concrete. The license on the site was terminated by NRC in 2003 so that the site can be released for unrestricted use, although New Jersey Department of Environmental Protection (NJDEP) disagreed with that decision. In 2006, NJDEP sued Viacom (successor of Westinghouse) and others for the continuation of ground water contamination at the site. | 1 | Applied and Interdisciplinary Chemistry |
Acetic acid bacteria (AAB) incompletely oxidize sugars and alcohols, usually glucose and ethanol, to acetic acid, in a process called AAB oxidative fermentation (AOF). After glycolysis, the produced pyruvate is broken down to acetaldehyde by pyruvate decarboxylase, which in turn is oxidized to acetic acid by acetaldehyde dehydrogenase. Ethanol is first oxidized to acetaldehyde by alcohol dehydrogenase, which is then converted to acetic acid. Both of these processes either generate NAD(P)H, or shuttle electrons into the electron transport chain via ubiquinol. This process is exploited in the use of acetic acid bacteria to produce vinegar. | 1 | Applied and Interdisciplinary Chemistry |
Members of Ancyronyx superficially resemble spiders and are aquatic, hence their common name, "spider water beetles". They are typically very small, with an average body length (without legs) of . They are characterized by extremely long legs (longer than the body length). The legs have widely separated coxae, with the procoxae (coxae attached to the prothorax) usually visible dorsally. The legs are tipped with large claws, each with two or three basal teeth. The distal teeth are the largest. The pair of antennae are typically 11-segmented. Most of the species possess brightly colored patterns on their elytra, but not all. The elytra also possess eight to eleven grooves (elytral striae), as well as small depressions (elytral punctures) of varying depth and number. The pronotum possesses a transverse groove and a more or less straight front margin, with pronotal carinae absent or weakly present.
Spider water beetles can be divided into two species groups, based on morphological and ecological adaptation patterns.
*The Ancyronyx variegatus species group are larger in size (usually larger than ), with very long legs, stout coxites on the ovipositor, and a transverse prosternal process. Their larvae are also larger, depressed in cross-section, and possess large side-pointing projections on the sides of the abdomen.
*The Ancyronyx patrolus species group have small and slender bodies, with comparatively shorter legs, long and slender coxites on the ovipositor, and a squarish prosternal process. Their larvae are smaller, with a more vaulted cross-section, and backwards pointing projections from the sides of the abdomen.
Ancyronyx is closely related to the genus Podelmis, but can be distinguished from the latter by the more or less straight and slender last segment of the ovipositor (versus the conical sideways-bent terminal segment of the ovipositor of Podelmis), and the absence of an anterior process on the prosternum. | 1 | Applied and Interdisciplinary Chemistry |
Special Weber's transform is an important tool in solving problems of the hydrodynamics. It is defined for as
where , are the Bessel functions of the first and second kind respectively. For it has a non-trivial kernel which consists of the functions .
The inverse transform is given by the formula
Due to non-triviality of the kernel, the inversion identity
is valid if . Also it is valid in the case of but only for functions, which are orthogonal to the kernel of in with infinitesimal element : | 1 | Applied and Interdisciplinary Chemistry |
At Pannon University software the tools PNS Editor and PNS Studio were programmed to generate maximum structure of processes. This software includes the p-graph method and MSG, SSG and ABB branch and bound algorithms to detect optimum structures within the maximum available process flows.
PNS is used in different applications where it can be used to find optimum process structures like:
* Process engineering: Chemical process designs and the Synthesis of chemical processes is applied in different case studies.
* Optimum energy technology networks for regional and urban energy systems: In case of regional and urban energy planning the financially most feasible solution for resource systems is selected as target value. With this setting material- and energy flows, energy demand and cost of technologies are considered and the optimum technology network can be found. Simultaneously the robustness of technologies due to price changes and limitations in resource availability can be identified.
* Evacuation routes in buildings: The aim is to find optimal routes to evacuate buildings depending on specific side parameters.
* Transportation routes: In this research area transportation routes with minimum cost and lowest environmental impact can be identified. | 1 | Applied and Interdisciplinary Chemistry |
Gun development and proliferation in China continued under the Ming dynasty. The success of its founder Zhu Yuanzhang, who declared his reign to be the era of Hongwu, or "Great Martiality," has often been attributed to his effective use of guns.
Most early Ming guns weighed two to three kilograms while guns considered "large" at the time weighed around only seventy-five kilograms. Ming sources suggest guns such as these shot stones and iron balls, but were primarily used against men rather than for causing structural damage to ships or walls. Accuracy was low and they were limited to a range of only 50 paces or so.
Despite the relatively small size of early Ming guns, some elements of gunpowder weapon design followed world trends. The growing length to muzzle bore ratio matched the rate at which European guns were developing up until the 1450s. The practice of corning gunpowder had been developed by 1370 for the purpose of increasing explosive power in land mines, and was arguably used in guns as well according to one record of a fire-tube shooting a projectile 457 meters, which was probably only possible at the time with the usage of corned powder. Around the same year Ming guns transitioned from using stone shots to iron ammunition, which has greater density and increased firearm power. Aside from firearms, the Ming pioneered in the usage of rocket launchers known as "wasp nests", which it manufactured for the army in 1380 and was used by the general Li Jinglong in 1400 against Zhu Di, the future Yongle Emperor.
The peak of Chinese cannon development prior to the incorporation of European weaponry in the 16th century is exemplified by the muzzle loading wrought iron "great general cannon" (大將軍炮) which weighed up to 360 kilograms and could fire a 4.8 kilogram lead ball. Its heavier variant, the "great divine cannon" (大神銃), could weigh up to 600 kilograms and was capable of firing several iron balls and upward of a hundred iron shots at once. The great general and divine cannons were the last indigenous Chinese cannon designs prior to the incorporation of European models in the 16th century.
The lack of larger siege weapons in China unlike the rest of the world where cannons grew larger and more potent has been attributed to the immense thickness of traditional Chinese walls, which Tonio Andrade suggests provided no incentive for creating larger cannons, since even industrial artillery had trouble overcoming them. Asianist Kenneth Chase also argues that larger guns were not particularly useful against China's traditional enemies: horse nomads. | 1 | Applied and Interdisciplinary Chemistry |
The phomoxanthones are a loosely defined class of natural products. The two founding members of this class are phomoxanthone A and phomoxanthone B. Other compounds were later also classified as phomoxanthones, although a unifying nomenclature has not yet been established. The structure of all phomoxanthones is derived from a dimer of two covalently linked tetrahydroxanthones, and they differ mainly in the position of this link as well as in the acetylation status of their hydroxy groups. The phomoxanthones are structurally closely related to other tetrahydroxanthone dimers such as the secalonic acids and the eumitrins. While most phomoxanthones were discovered in fungi of the genus Phomopsis, most notably in the species Phomopsis longicolla, some have also been found in Penicillium sp. | 1 | Applied and Interdisciplinary Chemistry |
Crystallographic image processing (CIP) is traditionally understood as being a set of key steps in the determination of the atomic structure of crystalline matter from high-resolution electron microscopy (HREM) images obtained in a transmission electron microscope (TEM) that is run in the parallel illumination mode. The term was created in the research group of [http://www.fos.su.se/~svenh/index.html Sven Hovmöller] at Stockholm University during the early 1980s and became rapidly a label for the "3D crystal structure from 2D transmission/projection images" approach. Since the late 1990s, analogous and complementary image processing techniques that are directed towards the achieving of goals with are either complementary or entirely beyond the scope of the original inception of CIP have been developed independently by members of the computational symmetry/geometry, scanning transmission electron microscopy, scanning probe microscopy communities, and applied crystallography communities. | 0 | Theoretical and Fundamental Chemistry |
In electrochemistry, protein film voltammetry (or protein film electrochemistry, or direct electrochemistry of proteins) is a technique for examining the behavior of proteins immobilized (either adsorbed or covalently attached) on an electrode. The technique is applicable to proteins and enzymes that engage in electron transfer reactions and it is part of the methods available to study enzyme kinetics.
Provided that it makes suitable contact with the electrode surface (electron transfer between the electrode and the protein is direct) and provided that it is not denatured, the protein can be fruitfully interrogated by monitoring current as a function of electrode potential and other experimental parameters.
Various electrode materials can be used. Special electrode designs are required to address membrane-bound proteins. | 0 | Theoretical and Fundamental Chemistry |
Trimethylboroxine is used in the methylation of various aryl halides through palladium-catalyzed Suzuki-Miyaura coupling reactions:
Another form of the Suzuki-Miyaura coupling reaction exhibits selectivity to aryl chlorides:
Boroxines have also been examined as precursors to monomeric oxoborane, HB≡O. This compound quickly converts back to the cyclic boroxine, even at low temperatures. | 0 | Theoretical and Fundamental Chemistry |
An extension of the anomeric effect, the exo anomeric effect is the preference of substituents coming off a ring to adopt the gauche conformation, while sterics would suggest an antiperiplanar conformation would be preferred.
An example of this is 2-methoxytetrahydropyran. As the anomeric effect predicts, the methoxy substituent shows an increased preference for the axial conformation. However, there is actually more than one possible axial conformation due to rotation about the C-O bond between the methoxy substituent and the ring. When one applies the principles of the reverse anomeric effect, it can be predicted that the gauche conformer is preferred, suggesting the top left conformation is best in the figure above. This prediction is supported by experimental evidence. Furthermore, this preference for the gauche position is still seen in the equatorial conformation. | 0 | Theoretical and Fundamental Chemistry |
Guy Bertrand, born on July 17, 1952, at Limoges is a chemistry professor at the University of California, San Diego.
Bertrand obtained his B.Sc. from the University of Montpellier in 1975 and his Ph.D. from the Paul Sabatier University, Toulouse, in 1979. He was a postdoctoral researcher at Sanofi Research, France, in 1981.
The research interests of Bertrand and his co-workers lie mainly in the chemistry of with main group elements from group 13 to 16, at the border between organic, organometallic and inorganic chemistry; especially their use in stabilizing carbenes, nitrenes, phosphinidenes, radicals and biradicals, 1,3-dipoles, anti-aromatic heterocycles, and more. He has directed the synthesis of some original persistent carbenes, including bis(diisopropylamino)cyclopropenylidene, the first example of a carbene with all-carbon environment that is stable at room-temperature.
Guy Bertrand is an honorific member or fellow of several scientific societies, such as the AAAS (2006), the French Academy of Sciences (2004), the European Academy of Sciences (2003), Academia Europaea (2002), and the recipient of various prizes and awards. | 0 | Theoretical and Fundamental Chemistry |
The mechanical bond can reduce the kinetic reactivity of the products, this is ascribed to the increased steric hindrance. Because of this effect hydrogenation of an alkene on the thread of a rotaxane is significantly slower as compared to the equivalent non interlocked thread. This effect has allowed for the isolation of otherwise reactive intermediates.
The ability to alter reactivity without altering covalent structure has led to MIMAs being investigated for a number of technological applications. | 0 | Theoretical and Fundamental Chemistry |
In the study of partial differential equations, the MUSCL scheme is a finite volume method that can provide highly accurate numerical solutions for a given system, even in cases where the solutions exhibit shocks, discontinuities, or large gradients. MUSCL stands for Monotonic Upstream-centered Scheme for Conservation Laws (van Leer, 1979), and the term was introduced in a seminal paper by Bram van Leer (van Leer, 1979). In this paper he constructed the first high-order, total variation diminishing (TVD) scheme where he obtained second order spatial accuracy.
The idea is to replace the piecewise constant approximation of Godunovs scheme by reconstructed states, derived from cell-averaged states obtained from the previous time-step. For each cell, slope limited, reconstructed left and right states are obtained and used to calculate fluxes at the cell boundaries (edges). These fluxes can, in turn, be used as input to a Riemann solver, following which the solutions are averaged and used to advance the solution in time. Alternatively, the fluxes can be used in Riemann-solver-free' schemes, which are basically Rusanov-like schemes. | 1 | Applied and Interdisciplinary Chemistry |
Synthesis of diacylglycerol begins with glycerol-3-phosphate, which is derived primarily from dihydroxyacetone phosphate, a product of glycolysis (usually in the cytoplasm of liver or adipose tissue cells). Glycerol-3-phosphate is first acylated with acyl-coenzyme A (acyl-CoA) to form lysophosphatidic acid, which is then acylated with another molecule of acyl-CoA to yield phosphatidic acid. Phosphatidic acid is then de-phosphorylated to form diacylglycerol.
Dietary fat is mainly composed of triglycerides. Because triglycerides cannot be absorbed by the digestive system, triglycerides must first be enzymatically digested into monoacylglycerol, diacylglycerol, or free fatty acids. Diacylglycerol is a precursor to triacylglycerol (triglyceride), which is formed in the addition of a third fatty acid to the diacylglycerol under the catalysis of diglyceride acyltransferase.
Since diacylglycerol is synthesized via phosphatidic acid, it will usually contain a saturated fatty acid at the C-1 position on the glycerol moiety and an unsaturated fatty acid at the C-2 position.
Diacylglycerol can be phosphorylated to phosphatidic acid by diacylglycerol kinase. | 1 | Applied and Interdisciplinary Chemistry |
Droplet countercurrent chromatography (DCCC) was introduced in 1970 by Tanimura, Pisano, Ito, and Bowman. DCCC uses only gravity to move the mobile phase through the stationary phase which is held in long vertical tubes connected in series. In the descending mode, droplets of the denser mobile phase and sample are allowed to fall through the columns of the lighter stationary phase using only gravity. If a less-dense mobile phase is used it will rise through the stationary phase; this is called ascending mode. The eluent from one column is transferred to another; the more columns that are used, the more theoretical plates can be achieved. DCCC enjoyed some success with natural product separations but was largely eclipsed by the rapid development of high-speed countercurrent chromatography. The main limitation of DCCC is that flow rates are low, and poor mixing is achieved for most binary solvent systems. | 0 | Theoretical and Fundamental Chemistry |
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