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*2012 German Urban Planning Award – BUGA Koblenz, Germany
*2012 President's Design Award – Bishan-Ang Mo Kio Park, Singapore
*2012 WAF Landscape of the Year – Kallang River Bishan-Ang Mo Kio Park, Singapore
*2011 Green Dot Award Ecological City – Arkadien Winnenden, Germany
*2011 LivCom Environmental Best Practice Eco Quartier – Pfaffenhofen, Germany
*2011 LivCom Award for Liveable Communities – Pfaffenhofen, Germany
*2011 BCA Greenmark “Platinum” Award for New Parks – JTC CleanTech Park, Singapore
*2011 DGNB Silver Sustainable City District – Berlin Potsdamer Platz, Germany
*2002 ASLA Merit Award – Chicago City Hall Green Roof, USA
*2001 Earth Society Foundation “Environmental Award” – Solar City Linz, Austria
*1989 United Nations “Best Practice Award” – Solar City Linz, Austria | 1 | Applied and Interdisciplinary Chemistry |
*Abundance in weight: spectroscopic nucleic acid quantitation
*Absolute abundance in number: real-time polymerase chain reaction (quantitative PCR)
*High-throughput relative abundance: DNA microarray
*High-throughput absolute abundance: serial analysis of gene expression (SAGE)
*Size: gel electrophoresis | 1 | Applied and Interdisciplinary Chemistry |
The Magnus effect explains commonly observed deviations from the typical trajectories or paths of spinning balls in sport, notably association football, table tennis, tennis, volleyball, golf, baseball, and cricket.
The curved path of a golf ball known as slice or hook is largely due to the ball's spin axis being tilted away from the horizontal due to the combined effects of club face angle and swing path, causing the Magnus effect to act at an angle, moving the ball away from a straight line in its trajectory. Backspin (upper surface rotating backwards from the direction of movement) on a golf ball causes a vertical force that counteracts the force of gravity slightly, and enables the ball to remain airborne a little longer than it would were the ball not spinning: this allows the ball to travel farther than a ball not spinning about its horizontal axis.
In table tennis, the Magnus effect is easily observed, because of the small mass and low density of the ball. An experienced player can place a wide variety of spins on the ball. Table tennis rackets usually have a surface made of rubber to give the racket maximum grip on the ball to impart a spin.
In cricket, the Magnus effect contributes to the types of motion known as drift, dip and lift in spin bowling, depending on the axis of rotation of the spin applied to the ball. The Magnus effect is not responsible for the movement seen in conventional swing bowling, in which the pressure gradient is not caused by the ball's spin, but rather by its raised seam, and the asymmetric roughness or smoothness of its two halves; however, the Magnus effect may be responsible for so-called "Malinga Swing", as observed in the bowling of the swing bowler Lasith Malinga.
In airsoft, a system known as hop-up is used to create a backspin on a fired BB, which greatly increases its range, using the Magnus effect in a similar manner as in golf.
In baseball, pitchers often impart different spins on the ball, causing it to curve in the desired direction due to the Magnus effect. The PITCHf/x system measures the change in trajectory caused by Magnus in all pitches thrown in Major League Baseball.
The match ball for the 2010 FIFA World Cup has been criticised for the different Magnus effect from previous match balls. The ball was described as having less Magnus effect and as a result flies farther but with less controllable swerve. | 1 | Applied and Interdisciplinary Chemistry |
Malachite green is classified in the dyestuff industry as a triarylmethane dye and also using in pigment industry. Formally, malachite green refers to the chloride salt , although the term malachite green is used loosely and often just refers to the colored cation. The oxalate salt is also marketed. The anions have no effect on the color. The intense green color of the cation results from a strong absorption band at 621 nm (extinction coefficient of ).
Malachite green is prepared by the condensation of benzaldehyde and dimethylaniline to give leuco malachite green (LMG):
Second, this colorless leuco compound, a relative of triphenylmethane, is oxidized to the cation that is MG:
A typical oxidizing agent is manganese dioxide.
Hydrolysis of MG gives an alcohol:
This alcohol is important because it, not MG, traverses cell membranes. Once inside the cell, it is metabolized into LMG. Only the cation MG is deeply colored, whereas the leuco and alcohol derivatives are not. This difference arises because only the cationic form has extended pi-delocalization, which allows the molecule to absorb visible light. | 0 | Theoretical and Fundamental Chemistry |
The compressor flow and pressure range is shown with a carpet plot of engine constant rpm and constant torque lines superimposed on the map. OpenCourseWare material shows a carpet plot of engine speed and load for the airflow requirements of 4-stroke truck engine. Shahed shows lines of constant engine speed and engine BMEP for a heavy-duty diesel engine. Woollenweber shows engine airflow requirements at different engine speeds and load/fuelling/torque. Hiereth et al. show operating lines for various applications such as a full-load operating line for a passenger car engine, the effect of an uncontrolled turbocharger on a truck diesel engine and wastegate control on passenger diesel and gasoline engines, and the effect of altitude on a compressor operating line. | 0 | Theoretical and Fundamental Chemistry |
Oligosaccharides are carbohydrates that are composed of several monosaccharide residues joined through glycosidic linkage, which can be hydrolyzed by enzymes or acid to give the constituent monosaccharide units. While a strict definition of an oligosaccharide is not established, it is generally agreed that a carbohydrate consisting of two to ten monosaccharide residues with a defined structure is an oligosaccharide.
Some oligosaccharides, for example maltose, sucrose, and lactose, were trivially named before their chemical constitution was determined, and these names are still used today.
Trivial names, however, are not useful for most other oligosaccharides and, as such, systematic rules for the nomenclature of carbohydrates have been developed. To fully understand oligosaccharide and polysaccharide nomenclature, one must understand how monosaccharides are named.
An oligosaccharide has both a reducing and a non-reducing end. The reducing end of an oligosaccharide is the monosaccharide residue with hemiacetal functionality, thereby capable of reducing the Tollens’ reagent, while the non-reducing end is the monosaccharide residue in acetal form, thus incapable of reducing the Tollens’ reagent. The reducing and non-reducing ends of an oligosaccharide are conventionally drawn with the reducing-end monosaccharide residue furthest to the right and the non-reducing (or terminal) end furthest to the left.
Naming of oligosaccharides proceeds from left to right (from the non-reducing end to the reducing end) as glycosyl [glycosyl] glycoses or glycosyl [glycosyl] glycosides, depending on whether or not the reducing end is a free hemiacetal group. In parentheses, between the names of the monosaccharide residues, the number of the anomeric carbon atom, an arrow symbol, and the number of the carbon atom bearing the connecting oxygen of the next monosaccharide unit are listed. Appropriate symbols are used to indicate the stereochemistry of the glycosidic bonds (α or β), the configuration of the monosaccharide residue ( or), and the substitutions at oxygen atoms (O). Maltose and a derivative of sucrose illustrate these concepts:
-Glucopyranosyl-(1→4)-β--glucopyranose</div>
-galactopyranosyl-(1→4)-2,3,6-tri-O-acetyl-β--glucopyranoside</div>
In the case of branched oligosaccharides, meaning that the structure contains at least one monosaccharide residue linked to more than two other monosaccharide residues, terms designating the branches should be listed in square brackets, with the longest linear chain (the parent chain) written without square brackets. The following example will help illustrate this concept:
-fucopyranosyl-(1→3)-[α--galactopyranosyl-(1→4)]-α--glucopyranosyl-(1→3)-α--galactopyranoside</div>
These systematic names are quite useful in that they provide information about the structure of the oligosaccharide. They do require a lot of space, however, so abbreviated forms are used when possible. In these abbreviated forms, the names of the monosaccharide units are shortened to their corresponding three-letter abbreviations, followed by p for pyranose or f for furanose ring structures, with the abbreviated aglyconic alcohol placed at the end of the name. Using this system, the previous example would have the abbreviated name α--Fucp-(1→3)-[α--Galp-(1→4)]-α--Glcp-(1→3)-α--GalpOAll.General Formula_Cn+1(H2o)n.. Structure Formula..C12H22O11. | 0 | Theoretical and Fundamental Chemistry |
Within the θ-β-M equation, a maximum corner angle, θ, exists for any upstream Mach number. When θ > θ, the oblique shock wave is no longer attached to the corner and is replaced by a detached bow shock. A θ-β-M diagram, common in most compressible flow textbooks, shows a series of curves that will indicate θ for each Mach number. The θ-β-M relationship will produce two β angles for a given θ and M, with the larger angle called a strong shock and the smaller called a weak shock. The weak shock is almost always seen experimentally.
The rise in pressure, density, and temperature after an oblique shock can be calculated as follows:
M is solved for as follows: | 1 | Applied and Interdisciplinary Chemistry |
*[https://archive.org/details/ElementosDeOrictognosiaODelConocimientoDeLosFosilesDispuestosSegun_165 Elementos de Orictognesia o del conocimiento de los fósiles], prepared for use in the Real Seminario de Mineria de México, 1795.
*Analyse des deux nouvelles espéces minérales composées de séléniure de zinc et de sulfure de mercure. Annales des Mines, Paris, 5, 1829.
*Découverte de liodure de mercure au Mexique'. Annales des Mines, Paris, 5, 1829.
*Elementos de Orictognesia, o del conocimiento de los fósiles según el sistema de Bercelio; y según los principios de Abraham Góttlob Wérner, con la sinonimia inglesa, alemana y francesa, para uso del Seminario Nacional de Minería de México. Philadelphia, 1832, . | 1 | Applied and Interdisciplinary Chemistry |
After collection, sperm must be processed for storage. According to the Sperm Bank of California, sperm banks and clinics can use the unwashed or wash method to process sperm samples. The wash method includes removing unwanted particles and adding buffer solutions to preserve viable sperm. However, this approach can contribute to further stress on the sperm cells and decrease the survival of sperm after freezing. The unwashed approach allows for more flexibility to freeze the semen sample and increases the number of sperm survival. One sample can produce 1–20 vials or straws, depending on the quantity of the ejaculate and whether the sample is washed or unwashed. Unwashed samples are used for intracervical insemination (ICI) treatments, and washed samples are used in intrauterine insemination (IUI) and for in-vitro fertilization (IVF) or assisted reproduction technologies (ART) procedures.
A cryoprotectant semen extender is conducted if the semen sample is placed in the freezer for storage. Semen extenders play a key factor in protecting sperm sample from freeze and osmotic shock, oxidative stress, and cell injury due to the formation of ice crystal during frozen storage. The collection of semen is preserved by stabilizing the properties of the sperm cells such as the membrane, motility, and DNA integrity in order to create a sustainable viable environment. There are two common forms of medium for sperm cyropreservation, one containing of egg yolk from hens and glycerol, and the other containing just glycerol. One study compared media supplemented with egg yolk and media supplemented with soy lecithin, finding that there was no significance between sperm motility, morphology, chromatin decondensation, or binding between the two, indicating that soy lecithin may be a viable alternative to egg yolk. | 1 | Applied and Interdisciplinary Chemistry |
While capillary sequencing was the first approach to successfully sequence a nearly full human genome, it is still too expensive and takes too long for commercial purposes. Since 2005 capillary sequencing has been progressively displaced by high-throughput (formerly "next-generation") sequencing technologies such as Illumina dye sequencing, pyrosequencing, and SMRT sequencing. All of these technologies continue to employ the basic shotgun strategy, namely, parallelization and template generation via genome fragmentation.
Other technologies have emerged, including Nanopore technology. Though the sequencing accuracy of Nanopore technology is lower than those above, its read length is on average much longer. This generation of long reads is valuable especially in de novo whole-genome sequencing applications. | 1 | Applied and Interdisciplinary Chemistry |
An impeller, or impellor, is a driven rotor used to increase the pressure and flow of a fluid. It is the opposite of a turbine, which extracts energy from, and reduces the pressure of, a flowing fluid.
Strictly speaking, propellers are a sub-class of impellers where the flow both enters and leaves axially, but in many contexts the term "impeller" is reserved for non-propeller rotors where the flow enters axially and leaves radially, especially when creating suction in a pump or compressor. | 1 | Applied and Interdisciplinary Chemistry |
For transcription to take place, the enzyme that synthesizes RNA, known as RNA polymerase, must attach to the DNA near a gene. Promoters contain specific DNA sequences such as response elements that provide a secure initial binding site for RNA polymerase and for proteins called transcription factors that recruit RNA polymerase. These transcription factors have specific activator or repressor sequences of corresponding nucleotides that attach to specific promoters and regulate gene expression.
;In bacteria: The promoter is recognized by RNA polymerase and an associated sigma factor, which in turn are often brought to the promoter DNA by an activator protein's binding to its own DNA binding site nearby.
;In eukaryotes: The process is more complicated, and at least seven different factors are necessary for the binding of an RNA polymerase II to the promoter.
Promoters represent critical elements that can work in concert with other regulatory regions (enhancers, silencers, boundary elements/insulators) to direct the level of transcription of a given gene.
A promoter is induced in response to changes in abundance or conformation of regulatory proteins in a cell, which enable activating transcription factors to recruit RNA polymerase. | 1 | Applied and Interdisciplinary Chemistry |
Both chemoenzymatic glycorandomization and neoglycorandomization use free reducing sugars and unprotected aglycons and are thereby a notable advance over classical glycosylation methods. A notable advantage of the enzymatic approach is the use of the corresponding genes encoding for the permissive kinases, nucleotidyltransferases and/or glycosyltransferases for in vivo synthetic biology applications to afford in vivo glycorandomization. However, it is important to note the enzymatic platform is dependent upon the permissivity of the enzymes employed. In contrast, the main hurdle to chemoselective neoglycorandomization is installation of the alkoxylamine handle. Unlike the enzymatic approach, the anomeric stereoselectivity of the chemoselective method depends upon the reducing sugar used and can, in some cases, lead to anomeric mixtures. | 0 | Theoretical and Fundamental Chemistry |
In pharmacology and medicine, vectorization of drugs refers to (intracellular) targeting with plastic, noble metal or silicon nanoparticles or liposomes to which pharmacologically active substances are reversibly bound or attached by adsorption.
CNRS researchers have devised a way to overcome the problem of multidrug resistance using polyalkyl cyanoacrylate (PACA) nanoparticles as "vectors".
As a developing concept, drug nanocarriers are expected to play a major role in delivering multiple drugs to tumor tissues by overcoming semi-permeable membranes and biological barriers such as the blood–brain barrier. | 1 | Applied and Interdisciplinary Chemistry |
The one-step Stöber process may be modified to manufacture porous silica by adding a surfactant template to the reaction mixture and calcining the resulting particles. Surfactants that have been used include cetrimonium bromide, cetyltrimethylammonium chloride, and glycerol. The surfactant forms micelles, small near-spherical balls with a hydrophobic interior and a hydrophilic surface, around which the silica network grows, producing particles with surfactant- and solvent-filled channels. Calcining the solid leads to removal of the surfactant and solvent molecules by combustion and/or evaporation, leaving mesopore voids throughout the structure, as seen in the illustration at right.
Varying the surfactant concentration allows control over the diameter and volume of pores, and thus of the surface area of the product material. Increasing the amount of surfactant leads to increases in total pore volume and hence particle surface area, but with individual pore diameters remaining unchanged. Altering the pore diameter can be achieved by varying the amount of ammonia used relative to surfactant concentration; additional ammonia leads to pores with greater diameters, but with a corresponding decrease in total pore volume and particle surface area. The time allowed for the reaction to proceed also influences porosity, with greater reaction times leading to increases in total pore volume and particle surface area. Longer reaction times also lead to increases in overall silica particle size and related decreases in the uniformity of the size distribution. | 0 | Theoretical and Fundamental Chemistry |
Arnold Adolph Berthold was a German physiologist and zoologist, who, in 1849, had a question about the function of the testes. He noticed in castrated roosters that they did not have the same sexual behaviors as roosters with their testes intact. He decided to run an experiment on male roosters to examine this phenomenon. He kept a group of roosters with their testes intact, and saw that they had normal sized wattles and combs (secondary sexual organs), a normal crow, and normal sexual and aggressive behaviors. He also had a group with their testes surgically removed, and noticed that their secondary sexual organs were decreased in size, had a weak crow, did not have sexual attraction towards females, and were not aggressive. He realized that this organ was essential for these behaviors, but he did not know how. To test this further, he removed one testis and placed it in the abdominal cavity. The roosters acted and had normal physical anatomy. He was able to see that location of the testes does not matter. He then wanted to see if it was a genetic factor that was involved in the testes that provided these functions. He transplanted a testis from another rooster to a rooster with one testis removed, and saw that they had normal behavior and physical anatomy as well. Berthold determined that the location or genetic factors of the testes do not matter in relation to sexual organs and behaviors, but that some chemical in the testes being secreted is causing this phenomenon. It was later identified that this factor was the hormone testosterone. | 1 | Applied and Interdisciplinary Chemistry |
A submitochondrial particle (SMP) is an artificial vesicle made from the inner mitochondrial membrane. They can be formed by subjecting isolated mitochondria to sonication, freezing and thawing, high pressure, or osmotic shock. SMPs can be used to study the electron transport chain in a cell-free context.
The process of SMP formation forces the inner mitochondrial membrane inside out, meaning that the matrix-facing leaflet becomes the outer surface of the SMP, and the intermembrane space-facing leaflet faces the lumen of the SMP. As a consequence, the F particles which normally face the matrix are exposed. Chaotropic agents can destabilize F particles and cause them to dissociate from the membrane, thereby uncoupling the final step of oxidative phosphorylation from the rest of the electron transport chain. | 1 | Applied and Interdisciplinary Chemistry |
In general, most hydroamination catalysts require elevated temperatures to function efficiently, and as such, only the thermodynamic product is observed. The isolation and characterization of the rarer and more synthetically valuable kinetic allyl amine product was reported when allenes was used at the unsaturated substrate. One system utilized temperatures of 80 °C with a rhodium catalyst and aniline derivatives as the amine. The other reported system utilized a palladium catalyst at room temperature with a wide range of primary and secondary cyclic and acyclic amines. Both systems produced the desired allyl amines in high yield, which contain an alkene that can be further functionalized through traditional organic reactions. | 0 | Theoretical and Fundamental Chemistry |
The Eli Lilly natural products group found that alkaloids of the Madagascar periwinkle (Vinca rosea), originally discovered in a screen for anti-diabetic drugs, blocked proliferation of tumour cells. The antitumour effect of the vinca alkaloids (e.g. vincristine) was later shown to be due to their ability to inhibit microtubule polymerization alkaloys, and therefore cell division. | 1 | Applied and Interdisciplinary Chemistry |
Researchers believe that RNA and proteins encoded for by HERV genes should continue to be explored for putative function in cell physiology and in pathological conditions. This would make sense to examine in order to more deeply define the biological significance of the proteins synthesized. | 1 | Applied and Interdisciplinary Chemistry |
Many antagonists are reversible antagonists that, like most agonists, will bind and unbind a receptor at rates determined by receptor-ligand kinetics.
Irreversible antagonists covalently bind to the receptor target and, in general, cannot be removed; inactivating the receptor for the duration of the antagonist effects is determined by the rate of receptor turnover, the rate of synthesis of new receptors. Phenoxybenzamine is an example of an irreversible alpha blocker—it permanently binds to α adrenergic receptors, preventing adrenaline and noradrenaline from binding. Inactivation of receptors normally results in a depression of the maximal response of agonist dose-response curves and a right shift in the curve occurs where there is a receptor reserve similar to non-competitive antagonists. A washout step in the assay will usually distinguish between non-competitive and irreversible antagonist drugs, as effects of non-competitive antagonists are reversible and activity of agonist will be restored.
Irreversible competitive antagonists also involve competition between the agonist and antagonist of the receptor, but the rate of covalent bonding differs and depends on affinity and reactivity of the antagonist. For some antagonists, there may be a distinct period during which they behave competitively (regardless of basal efficacy), and freely associate to and dissociate from the receptor, determined by receptor-ligand kinetics. But, once irreversible bonding has taken place, the receptor is deactivated and degraded. As for non-competitive antagonists and irreversible antagonists in functional assays with irreversible competitive antagonist drugs, there may be a shift in the log concentration–effect curve to the right, but, in general, both a decrease in slope and a reduced maximum are obtained. | 1 | Applied and Interdisciplinary Chemistry |
* Stress corrosion cracking (SCC) is the embrittlement caused by exposure to aqueous, corrosive materials. It relies on both a corrosive environment and the presence of tensile (not compressive) stress.
* Sulfide stress cracking is the embrittlement caused by absorption of hydrogen sulfide.
* Adsorption embrittlement is the embrittlement caused by wetting.
* Liquid metal embrittlement (LME) is the embrittlement caused by liquid metals.
* Metal-induced embrittlement (MIE) is the embrittlement caused by diffusion of atoms of metal, either solid or liquid, into the material. For example, cadmium coating on high-strength steel, which was originally done to prevent corrosion.
* Grain boundary segregation can cause brittle intergranular fracture. During solidification the grain boundaries end up as the repository for the impurities in the alloy by segregation. This grain boundary segregation can create a network of low-toughness paths through the material.
* The primary embrittlement mechanism of plastics is gradual loss of plasticizers, usually by overheating or aging.
* The primary embrittlement mechanism of asphalt is by oxidation, which is most severe in warmer climates. Asphalt pavement embrittlement (aka crocodile cracking) can lead to various forms of cracking patterns, including longitudinal, transverse, and block (hexagonal). Asphalt oxidation is related to polymer degradation, as these materials bear similarities in their chemical composition. | 1 | Applied and Interdisciplinary Chemistry |
A breakthrough curve in adsorption is the course of the effluent adsorptive concentration at the outlet of a fixed bed adsorber. Breakthrough curves are important for adsorptive separation technologies and for the characterization of porous materials. | 0 | Theoretical and Fundamental Chemistry |
Discontinuous assays are when samples are taken from an enzyme reaction at intervals and the amount of product production or substrate consumption is measured in these samples. | 1 | Applied and Interdisciplinary Chemistry |
Compartmentalization was important in the origin of life. Membranes form enclosed compartments that are separate from the external environment, thus providing the cell with functionally specialized aqueous spaces. As the lipid bilayer of membranes is impermeable to most hydrophilic molecules (dissolved by water), modern cells have membrane transport-systems that achieve nutrient uptake as well as the export of waste. Prior to the development of these molecular assemblies, protocells likely employed vesicle dynamics that are relevant to cellular functions, such as membrane trafficking and self-reproduction, using amphiphilic molecules. On the primitive Earth, numerous chemical reactions of organic compounds produced the ingredients of life. Of these substances, amphiphilic molecules might be the first player in the evolution from molecular assembly to cellular life. Vesicle dynamics could progress towards protocells with the development of self-replication coupled with early metabolism. It is possible that protocells might have had a primitive metabolic system (Wood-Ljungdahl pathway) at alkaline hydrothermal vents or other geological environments like impact crater lakes from meteorites, which are known to be composed of elements found in the Wood-Ljungdahl pathway.
Another conceptual model of a protocell relates to the term "chemoton" (short for chemical automaton) which refers to the fundamental unit of life introduced by Hungarian theoretical biologist Tibor Gánti. It is the oldest known computational abstract of a protocell. Gánti conceived the basic idea in 1952 and formulated the concept in 1971 in his book The Principles of Life (originally written in Hungarian, and translated to English only in 2003). He surmised the chemoton as the original ancestor of all organisms, or the last universal common ancestor.
The basic assumption of the chemoton model is that life should fundamentally and essentially have three properties: metabolism, self-replication, and a bilipid membrane. The metabolic and replication functions together form an autocatalytic subsystem necessary for the basic functions of life, and a membrane encloses this subsystem to separate it from the surrounding environment. Therefore, any system having such properties may be regarded as alive, and will contain self sustaining cellular information that is subject to natural selection. Some consider this model a significant contribution to origin of life as it provides a philosophy of evolutionary units. | 0 | Theoretical and Fundamental Chemistry |
Waste of the by-product heat is reduced if a cogeneration system is used, also known as a Combined Heat and Power (CHP) system. Limitations to the use of by-product heat arise primarily from the engineering cost/efficiency challenges in effectively exploiting small temperature differences to generate other forms of energy. Applications utilizing waste heat include swimming pool heating and paper mills. In some cases, cooling can also be produced by the use of absorption refrigerators for example, in this case it's called trigeneration or CCHP (combined cooling, heat and power). | 0 | Theoretical and Fundamental Chemistry |
In the nuclear plant field, steam generator refers to a specific type of large heat exchanger used in a pressurized water reactor (PWR) to thermally connect the primary (reactor plant) and secondary (steam plant) systems, which generates steam. In a boiling water reactor (BWR), no separate steam generator is used and water boils in the reactor core.
In some industrial settings, there can also be steam-producing heat exchangers called heat recovery steam generators (HRSG) which utilize heat from some industrial process, most commonly utilizing hot exhaust from a gas turbine. The steam generating boiler has to produce steam at the high purity, pressure and temperature required for the steam turbine that drives the electrical generator.
Geothermal plants do not need boilers because they use naturally occurring steam sources. Heat exchangers may be used where the geothermal steam is very corrosive or contains excessive suspended solids.
A fossil fuel steam generator includes an economizer, a steam drum, and the furnace with its steam generating tubes and superheater coils. Necessary safety valves are located at suitable points to protect against excessive boiler pressure. The air and flue gas path equipment include: forced draft (FD) fan, air preheater (AP), boiler furnace, induced draft (ID) fan, fly ash collectors (electrostatic precipitator or baghouse), and the flue-gas stack. | 1 | Applied and Interdisciplinary Chemistry |
Ethylene binds to it specific transmembrane receptor present on the cell membrane of endoplasmic reticulum. There are different ethylene receptor isoforms. Five isoforms are known in Arabidopsis thaliana which are named ethylene response/receptor 1 (ETR1), ethylene response sensor 1 (ERS1), ETR2, ERS2, and ethylene insensitive 4 (EIN4). The ETR1 is similar (conserved sequence) in different plants but with slight amino acid differences. A. thaliana receptors are classified into two subfamilies based on genetic relationship and common structural features, namely subfamily 1 that includes ETR1 and ERS1, and subfamily 2 that consists of ETR2, ERS2, and EIN4. In tomato there are seven types of ethylene receptors named SlETR1, SlETR2, SlETR3, SlETR4, SlETR5, SlETR6, and SlETR7 (Sl for Solanum lycopersicum, the scientific of tomato).
All ethylene receptors have similar organisation: a short N-terminal domain, three conserved transmembrane domains towards the N-terminus, followed by a GAF domain of unknown function, and then signal output motifs in the C-terminal region. The N-terminus is exposed on the lumen of the endoplasmic reticulum, and the C-terminus that is exposed to the cytoplasm of the cell. The N-terminus contains the sites for binding of ethylene, dimerization and membrane localization. Two similar receptors combine to form a homodimer through a disulfide bridge forming a cysteine-cysteine interaction. However, the main membrane localization is done by the transmembrane domain, which can also bind ethylene with the help of copper as a cofactor. Copper ion is supplied by a transmembrane protein responsive-to-antagonist 1 (RAN1) from antioxidant protein 1 (ATX1) via tiplin, or directly by copper transport protein.
Although the receptors are functionally active as dimers, only one copper ion binds to such dimer, indicating that one receptor dimer binds only one ethylene molecule. Mutations in the binding sites stop ethylene binding and also make plants insensitive to ethylene. Cys-65 in the protein helix 2 is particularly important as the binding site of copper ion as mutation in it stops copper and ethylene binding. The C-terminus is basically a bacterial two-component system with kinase activity and response regulator. ETR1 has histidine kinase activity, whereas ETR2, ERS2, and EIN4 have serine/threonine kinase activity, and ERS1 has both. The histidine kinase in ETR1 is not required for ethylene signaling. | 1 | Applied and Interdisciplinary Chemistry |
The use of optoelectronics tells us that previous optoelectronic structures were used to check the thermal efficiency of certain materials that were composite and inserted into the detection unit as a liner. This technique depends on the coupled fluid thickness scanning process (TWRC method). Two special composites were chosen for this study: (I) Liquid: Nanofluid based on water and containing gold nanoparticles (ii) More solid type: Urea - Fumaric acid eutectic in a ratio of 1:1. It has been found that the thermal effusivity is independent upon the volume and concentration in the gold particles. Considering the eutectic characterized by urea-fumaric acid, it can be reasonably concluded that the value of the heat permeable compound is quite different from that of the pure raw material. This illustrates the production of compounds.
Self-consistence photopyroelectric calorimetry for liquids
This photopyroelectric also demonstrate that the front photopyroelectric (FPPE)structure is also important. In addition, it clearly explains the Thermal Wave Resonator Cavity (TWRC) method, which is designed to check the thermal mobility and diffusivity of liquids. It has demonstrated that the same type of technology is capable of producing a variety of static and dynamic thermal parameters. In addition, two of these parameters are checked and calculated in a straightforward manner, while the other two are still calculated indirectly. This method shows the principle of sustainability in that it studies certain liquids such as various oils, water, glycerin, ethylene glycol and the like. | 0 | Theoretical and Fundamental Chemistry |
Chan is a founding member of the Democratic Party. He was elected as chairman of the New Territories East Branch in 1999, and later became the party's minister of organization affairs and central committee member. He ran for the chairmanship election in 2004 but lost to Lee Wing-tat. He was then elected vice-chairman of the party. He also served as a part-time member of Central Policy Unit of the Hong Kong Government between 2004 and 2006.
He ran again for the chairmanship in December 2006, but lost to Albert Ho. He did not seek to run for the vice-chairmanship in the 2006 election. In 2010, the Democratic Party decided to support the government's proposal of the political reform package to expand the numbers of legislative council members from 30 to 35 in Geographical Constituency and 30 to 35 of Functional Constituency by adopting the idea of the "Super-district Councillors" which will be voted across the territory after nominations by District Councillors. Younger members of the Democratic Party including Chan believed that such proposal could not provide any significant progress towards democratic development in local political agenda.
In December 2010, Chan quit the party due to the electoral reform to found the Neo Democrats and is the incumbent convenor of the party. The Neo Democrats campaigned in the 2011 District Council election and won a total of 8 seats. | 1 | Applied and Interdisciplinary Chemistry |
Nyāya (Sanskrit:न्यायः, nyāya), literally meaning "justice", "rules", "method" or "judgment", is one of the six orthodox (Āstika) schools of Hindu philosophy that affirm the Vedas. Nyāyas most significant contributions to Indian philosophy were systematic development of the theory of logic, methodology, and its treatises on epistemology.
Nyāya schools epistemology accepts four out of six Pramanas as reliable means of gaining knowledge – Pratyakṣa (perception), Anumāṇa (inference), Upamāna (comparison and analogy) and Śabda (word, testimony of past or present reliable experts). In its metaphysics, Nyāya school is closer to the Vaisheshika school of Hinduism than others. It holds that human suffering results from mistakes/defects produced by activity under wrong knowledge (notions and ignorance). Moksha (liberation), it states, is gained through right knowledge. This premise led Nyāya to concern itself with epistemology, that is the reliable means to gain correct knowledge and to remove wrong notions. False knowledge is not merely ignorance to Naiyyayikas, it includes delusion. Correct knowledge is discovering and overcoming ones delusions, and understanding true nature of soul, self and reality.
Naiyyayika scholars approached philosophy as a form of direct realism, stating that anything that really exists is in principle humanly knowable. To them, correct knowledge and understanding is different from simple, reflexive cognition; it requires Anuvyavasaya (अनुव्यवसाय, cross-examination of cognition, reflective cognition of what one thinks one knows). An influential collection of texts on logic and reason is the Nyāya Sūtras, attributed to Aksapada Gautama, variously estimated to have been composed between 6th-century BCE and 2nd-century CE.
Nyāya school shares some of its methodology and human suffering foundations with Buddhism; however, a key difference between the two is that Buddhism believes that there is neither a soul nor self; Nyāya school like some other schools of Hinduism such as Dvaita and Viśiṣṭādvaita believes that there is a soul and self, with liberation (mokṣa) as a state of removal of ignorance, wrong knowledge, the gain of correct knowledge, and unimpeded continuation of self. | 1 | Applied and Interdisciplinary Chemistry |
Metal chelate compounds are common components of fertilizers to provide micronutrients. These micronutrients (manganese, iron, zinc, copper) are required for the health of the plants. Most fertilizers contain phosphate salts that, in the absence of chelating agents, typically convert these metal ions into insoluble solids that are of no nutritional value to the plants. EDTA is the typical chelating agent that keeps these metal ions in a soluble form. | 0 | Theoretical and Fundamental Chemistry |
1,3,5-Triheptylbenzene (also called sym-triheptylbenzene) is an aromatic organic compound with a chemical formula and molar mass 372.67 g/mol. It can be prepared by the hydrogenation reduction reaction of 1,1,1-(benzene-1,3,5-triyl)tris(heptan-1-one). Alternatively, 1-nonyne trimerizes to 1,3,5-triheptylbenzene when catalyzed by rhodium trichloride. | 0 | Theoretical and Fundamental Chemistry |
Principle : the pixel values along the field lines are strongly correlated, but orthogonally to them almost uncorrelated. As a result, the field lines stand out visually from the background and become visible.
Intuition:
* throwing paint in a river
* visualisation of magnetic field lines using randomly distributed iron filings
* "emulates what happens when a rectangular area of massless fine sand is blown by strong wind"
Intuitively, the flow of a vector field in some domain is visualized by adding a static random pattern of dark and light paint sources. As the flow passes by the sources, each parcel of fluid picks up some of the source color, averaging it with the color it has already acquired in a manner similar to throwing paint in a river. The result is a random striped texture where points along the same streamline tend to have similar color. | 1 | Applied and Interdisciplinary Chemistry |
In aqueous solution 3-hydroxypropionaldehyde exists in equilibrium with its hydrate (1,1,3-propanetriol), in which the aldehyde group converts to a geminal diol:
:HOCHCHCHO + HO → HOCHCHCH(OH)
The hydrate is also in equilibrium with its dimer (2-(2-hydroxyethyl)-4-hydroxy-1,3-dioxane), which dominates at high concentrations. These three components - the aldehyde, its dimer, and the hydrate are therefore in a dynamic equilibrium.
Besides, 3-hydroxypropionaldehyde suffers an spontaneous dehydration in aqueous solution, and the resulting molecule is called acrolein.
In fact, the term reuterin is the name given to the dynamic system formed by 3-hydroxypropionaldehyde, its hydrate, the dimer, and acrolein. This last molecule, acrolein, was recently included in reuterin definition. | 1 | Applied and Interdisciplinary Chemistry |
A DNA walker is a class of nucleic acid nanomachines where a nucleic acid "walker" is able to move along a nucleic acid "track". The concept of a DNA walker was first defined and named by John H. Reif in 2003.
A nonautonomous DNA walker requires external changes for each step, whereas an autonomous DNA walker progresses without any external changes. Various nonautonomous DNA walkers were developed, for example Shin controlled the motion of DNA walker by using control strands which needed to be manually added in a specific order according to the template's sequence in order to get the desired path of motion.
In 2004 the first autonomous DNA walker, which did not require external changes for each step, was experimentally demonstrated by the Reif group.
DNA walkers have functional properties such as a range of motion extending from linear to 2 and 3-dimensional, the ability to pick up and drop off molecular cargo, performing DNA-templated synthesis, and increased velocity of motion. DNA walkers have potential applications ranging from nanomedicine to nanorobotics. Many different fuel options have been studied including DNA hybridization, hydrolysis of DNA or ATP, and light. The DNA walker's function is similar to that of the proteins dynein and kinesin. | 0 | Theoretical and Fundamental Chemistry |
A meso compound or meso isomer is an optically inactive isomer in a set of stereoisomers, at least two of which are optically active. This means that despite containing two or more stereocenters, the molecule is not chiral. A meso compound is superposable on its mirror image (not to be confused with superimposable, as any two objects can be superimposed over one another regardless of whether they are the same). Two objects can be superposed if all aspects of the objects coincide and it does not produce a "(+)" or "(-)" reading when analyzed with a polarimeter. The name is derived from the Greek mésos meaning “middle”.
For example, tartaric acid can exist as any of three stereoisomers depicted below in a Fischer projection. Of the four colored pictures at the top of the diagram, the first two represent the meso compound (the 2R,3S and 2S,3R isomers are equivalent), followed by the optically active pair of levotartaric acid (L-(R,R)-(+)-tartaric acid) and dextrotartaric acid (D-(S,S)-(-)-tartaric acid). The meso compound is bisected by an internal plane of symmetry that is not present for the non-meso isomers (indicated by an X). That is, on reflecting the meso compound through a mirror plane perpendicular to the screen, the same stereochemistry is obtained; this is not the case for the non-meso tartaric acid, which generates the other enantiomer. The meso compound must not be confused with a 50:50 racemic mixture of the two optically-active compounds, although neither will rotate light in a polarimeter.
It is a requirement for two of the stereocenters in a meso compound to have at least two substituents in common (although having this characteristic does not necessarily mean that the compound is meso). For example, in 2,4-pentanediol, both the second and fourth carbon atoms, which are stereocenters, have all four substituents in common.
Since a meso isomer has a superposable mirror image, a compound with a total of n chiral centers cannot attain the theoretical maximum of 2 stereoisomers if one of the stereoisomers is meso.
A meso isomer need not have a mirror plane. It may have an inversion or a rotoreflexion symmetry such as S. For example, there are two meso isomers of 1,4-difluoro-2,5-dichlorocyclohexane but neither has a mirror plane, and there are two meso isomers of 1,2,3,4-tetrafluorospiropentane (see figure). | 0 | Theoretical and Fundamental Chemistry |
Natural streams, rivers and lakes have their own in-built purification system which consists of natural slopes, stones for biological growth and complex food web help in the purification process. This food web is nothing but utilization of one's waste by another as its own food. Nature has her own living machinery of detritivorous microbes and other living species to consume wastes. These principles have been harnessed in the treatment of polluted streams.
Green bridges are developed using fibrous material with stones. All the floatable and suspended solids are trapped in this biological bridge and the turbidity of flowing water is reduced. Green plants on the bridges increase the DO level in water, which in turn facilitates the growth of aerobic organisms, which degrade organic pollutants. Sandeep Joshi, director, SERI (Shrishti Eco-Research Institute) has developed this technology and has received a patent for it. | 1 | Applied and Interdisciplinary Chemistry |
* geWorkbench is open-source software that can be downloaded and installed locally. A zip file of the released version Java source is also available.
* Prepackaged installer versions also exist for Windows, Macintosh, and Linux. | 1 | Applied and Interdisciplinary Chemistry |
Gamma radiation as well as neutron radiation can cause RPMs to trigger an alarm procedure. Alarms caused by statistical fluctuations of detection rates are referred to as false alarms. Alarms caused by benign radioactive sources are referred to as nuisance alarms. Causes of nuisance alarms can be broken up into several large categories:
*Naturally occurring radioactive materials (NORM) and technically enhanced NORM (TENORM)
**Ceramic, tiles, porcelain, pottery, granite, clay, and other rock and clay based products contain elevated levels of naturally occurring potassium-40 and to a smaller degree thorium-232 and other isotopes.
**Propane gas tankers, full or empty, contain elevated levels of radium-226.
**Many fertilizers and potash contain elevated levels of potassium-40.
**Cat litter contains elevated levels of thorium-232.
*Medical isotope alarms constitute the majority of alarms in privately owned vehicle lanes at land borders and are usually due to medical treatment of the driver or passengers, mostly due to technetium-99m and thallium-201 and iodine-131. | 0 | Theoretical and Fundamental Chemistry |
In the partial wave expansion the scattering amplitude is represented as a sum over the partial waves,
where is the partial scattering amplitude and are the Legendre polynomials. The partial amplitude can be expressed via the partial wave S-matrix element () and the scattering phase shift as
Then the total cross section
can be expanded as
is the partial cross section. The total cross section is also equal to due to optical theorem.
For , we can write | 0 | Theoretical and Fundamental Chemistry |
The Streeter–Phelps equation is used in the study of water pollution as a water quality modelling tool. The model describes how dissolved oxygen (DO) decreases in a river or stream along a certain distance by degradation of biochemical oxygen demand (BOD). The equation was derived by H. W. Streeter, a sanitary engineer, and Earle B. Phelps, a consultant for the U.S. Public Health Service, in 1925, based on field data from the Ohio River. The equation is also known as the DO sag equation. | 1 | Applied and Interdisciplinary Chemistry |
The recommended intravenous dosage in adults is 500 mg iv every 6 hours or 1000 mg every 12 hours, with modification to achieve a therapeutic range as needed. The recommended oral dosage in the treatment of antibiotic-induced pseudomembranous enterocolitis is 125 to 500 mg every 6 hours for 7 to 10 days.
Dose optimization and target attainment of vancomycin in children involves adjusting the dosage of the antibiotic to maximize its effectiveness while minimizing the risk of adverse effects, specifically acute kidney injury. Dose optimization is achieved through therapeutic drug monitoring (TDM), which allows to measure vancomycin levels in the blood and tailor the dosage accordingly. TDM using area under the curve (AUC)-guided dosing, preferably with Bayesian forecasting, is recommended to ensure that the AUC0-24h/minimal inhibitory concentration (MIC) ratio is maintained above a certain threshold (400-600) associated with optimal efficacy. | 0 | Theoretical and Fundamental Chemistry |
A defining advantage of COFs is the exceptional porosity that results from the substitution of analogous SBUs of varying sizes. Pore sizes range from 7-23 Å and feature a diverse range of shapes and dimensionalities that remain stable during the evacuation of solvent. The rigid scaffold of the COF structure enables the material to be evacuated of solvent and retain its structure, resulting in high surface areas as seen by the Brunauer–Emmett–Teller analysis. This high surface area to volume ratio and incredible stability enables the COF structure to serve as exceptional materials for gas storage and separation. | 0 | Theoretical and Fundamental Chemistry |
Radioisotopic labeling is a technique for tracking the passage of a sample of substance through a system. The substance is "labeled" by including radionuclides in its chemical composition. When these decay, their presence can be determined by detecting the radiation emitted by them. Radioisotopic labeling is a special case of isotopic labeling.
For these purposes, a particularly useful type of radioactive decay is positron emission. When a positron collides with an electron, it releases two high-energy photons traveling in diametrically opposite directions. If the positron is produced within a solid object, it is likely to do this before traveling more than a millimeter. If both of these photons can be detected, the location of the decay event can be determined very precisely.
Strictly speaking, radioisotopic labeling includes only cases where radioactivity is artificially introduced by experimenters, but some natural phenomena allow similar analysis to be performed. In particular, radiometric dating uses a closely related principle. | 0 | Theoretical and Fundamental Chemistry |
When nascent hydrogen is produced by anaerobic corrosion of iron by the protons of water, the atomic hydrogen can diffuse into the metal crystal lattice because of the existing concentration gradient. After diffusion, hydrogen atoms can recombine into molecular hydrogen giving rise to the formation of high-pressure micro-bubbles of H in the metallic lattice. The trends to expansion of H bubbles and the resulting tensile stress can generate cracks in the metallic alloys sensitive to this effect also known as hydrogen embrittlement. Several recent studies (Turnbull, 2009; King, 2008; King and Kolar, 2009) address this question in the frame of the radioactive waste disposal in Switzerland and Canada. | 1 | Applied and Interdisciplinary Chemistry |
Metal-nitrosyls are assumed to be intermediates in catalytic converters, which reduce the emission of from internal combustion engines. This application has been described as "one of the most successful stories in the development of catalysts."
Metal-catalyzed reactions of NO are not often useful in organic chemistry. In biology and medicine, nitric oxide is however an important signalling molecule in nature and this fact is the basis of the most important applications of metal nitrosyls. The nitroprusside anion, [Fe(CN)NO], a mixed nitrosyl cyano complex, has pharmaceutical applications as a slow release agent for NO. The signalling function of NO is effected via its complexation to haeme proteins, where it binds in the bent geometry. Nitric oxide also attacks iron-sulfur proteins giving dinitrosyl iron complexes. | 0 | Theoretical and Fundamental Chemistry |
* Phenol: The phenol used for biochemistry comes as a water-saturated solution with Tris buffer, as a Tris-buffered 50% phenol, 50% chloroform solution, or as a Tris-buffered 50% phenol, 48% chloroform, 2% isoamyl alcohol solution (sometimes called "25:24:1"). Phenol is naturally somewhat water-soluble, and gives a fuzzy interface, which is sharpened by the presence of chloroform, and the isoamyl alcohol reduces foaming. Most solutions also have an antioxidant, as oxidized phenol damages the nucleic acids. For RNA purification, the pH is kept at around 4, which retains RNA in the aqueous phase preferentially. For DNA purification, the pH is usually near 7, at which point all nucleic acids are found in the aqueous phase.
* Chloroform: Chloroform is stabilized with small quantities of amylene or ethanol, because exposure of pure chloroform to oxygen and ultraviolet light produces phosgene gas. Some chloroform solutions come as pre-made a 96% chloroform, 4% isoamyl alcohol mixture that can be mixed with an equal volume of phenol to obtain the 25:24:1 solution.
* Isoamyl alcohol: Isoamyl alcohol may reduce foaming and ensure deactivation of RNases. | 1 | Applied and Interdisciplinary Chemistry |
It has been discovered that over 60 variations of INSTI mutations cause in vivo and in vitro resistance. Due to these mutations and development of resistance the inhibitors are less effective against the virus.
Resistance of INI corresponds to those of other ARV drugs. First IN resistance is caused by primary mutations that decrease INI sensitivity in combination with secondary mutations that further reduce virus sensitivity and/or repair decreased fitness of the virus. Secondly there is a genetic barrier to INI resistance, defined by the number of mutations required for the loss of clinical INI activity. Thirdly there is extensive but incomplete cross-resistance among the INIs.
A loop containing amino acid residues 140–149 is located in the catalytic-core domain and is important for IN function as mentioned before. This loop is flexible and even though its role is not quite known it is thought to be important and its functions critical for DNA binding. This resistance appears within mutations in this IN-coding region.
The resistance to raltegravir and elvitegravir is primarily due to the same two mutation pathways but other primary mutations are also involved for each of the drugs. Some mutations increase resistance to the drugs to a large extent than others. For example, one of the most common mutation pathway increases the resistance to raltegravir up to 100 times more than the second most common one.
Resistance to Integrase Inhibitor S/GSK1349572 is still being developed and the resistance has not been fully characterized. When it was assessed alongside the primary mutations of raltegravir and elvitegravir it did not show cross-resistance which means that it could be useful against drug resistant viruses.
Raltegravir has limited intestinal absorption and thus resistance cannot be overcome by prescribing higher doses. Newer drugs are warranted to overcome this pharmacological disadvantage and gain plasma concentrations high enough to target raltegravir-resistant viruses. | 1 | Applied and Interdisciplinary Chemistry |
The eIF4F complex is composed of three subunits: eIF4A, eIF4E, and eIF4G. Each subunit has multiple human isoforms and there exist additional eIF4 proteins: eIF4B and eIF4H.
eIF4G is a 175.5-kDa scaffolding protein that interacts with eIF3 and the Poly(A)-binding protein (PABP), as well as the other members of the eIF4F complex. eIF4E recognizes and binds to the 5' cap structure of mRNA, while eIF4G binds PABP, which binds the poly(A) tail, potentially circularizing and activating the bound mRNA. eIF4Aa DEAD box RNA helicaseis important for resolving mRNA secondary structures.
eIF4B contains two RNA-binding domainsone non-specifically interacts with mRNA, whereas the second specifically binds the 18S portion of the small ribosomal subunit. It acts as an anchor, as well as a critical co-factor for eIF4A. It is also a substrate of S6K, and when phosphorylated, it promotes the formation of the pre-initiation complex. In vertebrates, eIF4H is an additional initiation factor with similar function to eIF4B. | 1 | Applied and Interdisciplinary Chemistry |
Amino acid biosynthesis is the set of biochemical processes (metabolic pathways) by which the amino acids are produced. The substrates for these processes are various compounds in the organism's diet or growth media. Not all organisms are able to synthesize all amino acids. For example, humans can synthesize 11 of the 20 standard amino acids. These 11 are called the non-essential amino acids). | 1 | Applied and Interdisciplinary Chemistry |
Chromosome III is the third smallest chromosome in S. cerevisiae; its size was estimated from pulsed-field gel electro- phoresis studies to be 300–360 kb
This chromosome has been the subject of intensive study, not least because it contains the three genetic loci involved in mating-type control: MAT, HML and HMR.
In March 2014, Jef Boeke of the Langone Medical Centre at New York University, published that his team has synthesized one of the S. cerevisiae 16 yeast chromosomes, the chromosome III, that he named synIII. The procedure involved replacing the genes in the original chromosome with synthetic versions and the finished synthesized chromosome was then integrated into a yeast cell. It required designing and creating 273,871 base pairs of DNA - fewer than the 316,667 pairs in the original chromosome. | 1 | Applied and Interdisciplinary Chemistry |
A hand boiler functions similar to the "drinking bird" toy: The upper and lower bulbs of the device are at different temperatures, and therefore the vapor pressure in the two bulbs is different. Since the lower bulb is warmer, the vapor pressure in it is higher. The difference in vapor pressure forces the liquid from the lower bulb to the upper bulb. Thus:
where:<br>
= the height of the column of fluid above the fluid's level in the lower bulb<br>
= the difference in vapor pressure between the two bulbs (which can be determined via the Antoine equation)<br>
= the density of the liquid<br>
= the acceleration of gravity at the Earth's surface
The liquid inside a hand boiler (ethanol) does not actually boil. The "boiling" is caused by the relationship between the temperature and pressure of a gas. As the temperature of a gas in a closed container rises, the pressure also rises. There must be a temperature (and pressure) difference between the two large chambers for the liquid to move. When held upright (with the smaller bulb on top), the liquid will move from the bulb with the higher pressure to the bulb with lower pressure. As the gas continues to expand, the gas will then bubble through the liquid, making it appear to boil. The fact that the liquid is volatile (easily vaporized) makes the hand boiler more effective. Adding heat to the liquid produces more gas, also increasing pressure in the closed container.
Sometimes a hand boiler is used to show properties of distillation. Since the liquid both evaporates and condenses at relatively cool temperatures while in an enclosed system, the boiler can be turned upside down, and the top end can be placed in ice water. The gaseous form of the liquid will condense in the cooled chamber. Since the liquid is often colored with dye, but the dye does not evaporate or condense at the same temperature, the liquid that condenses in the cooled chamber is colorless, leaving the pigment behind. | 0 | Theoretical and Fundamental Chemistry |
The site was occupied by the pre-Roman Britons, likely as part of an iron working industry. It was continually occupied throughout the Roman era, and the scale of industrial activity increased over the period. It is clear that there was a focus of settlement activity near Bromsash, but the area appears to some archaeologists to have contained dispersed centres of activity and settlement rather than a Roman town. Ariconiums only documented significance is as a station on Iter XIII of the Iter Britanniarum', with the single mention there being its only mention in classical history.
It seems to have been abandoned shortly after 360. Its sudden abandonment is consistent with a violent end, and may be related to the collapse of authority and widespread marauding at that time, as reported by Ammianus, a situation that lasted for almost a decade, and from which parts of Roman Britain never recovered. Evidence of later occupation of the site has not been found. | 1 | Applied and Interdisciplinary Chemistry |
Many methods in ester synthesis can also be applied to that of lactones. Lactonization competes with polymerization for longer hydroxy acids, or the strained βlactones. γLactones, on the other hand, are so stable that 4-hydroxy acids (R-CH(OH)-(CH)-COH) spontaneously cyclise.
In one industrial synthesis of oxandrolone the key lactone-forming step is an organic reaction - esterification.
In halolactonization, an alkene is attacked by a halogen via electrophilic addition with the cationic intermediate captured intramolecularly by an adjacent carboxylic acid.
Specific methods include Yamaguchi esterification, Shiina macrolactonization, Corey-Nicolaou macrolactonization, Baeyer–Villiger oxidation and nucleophilic abstraction.
The γ-lactones γ-octalactone, γ-nonalactone, γ-decalactone, γ-undecalactone can be prepared in good yield in a one-step process by radical addition of primary fatty alcohols to acrylic acid, using di-tert-butyl peroxide as a catalyst.
An alternative radical reaction yielding γ-lactones is the manganese-mediated coupling. | 0 | Theoretical and Fundamental Chemistry |
In Saxon settlements such as one identified in Northumberland as Bedes Ad Gefrin (now called Yeavering) the buildings were shown by an excavators reconstruction to have opposed entries. In barns a draught created by the use of these opposed doorways was used in winnowing.
The technique developed by the Chinese was not adopted in Europe until the 18th century when winnowing machines used a sail fan. The rotary winnowing fan was exported to Europe, brought there by Dutch sailors between 1700 and 1720. Apparently, they had obtained them from the Dutch settlement of Batavia in Java, Dutch East Indies. The Swedes imported some from south China at about the same time and Jesuits had taken several to France from China by 1720. Until the beginning of the 18th century, no rotary winnowing fans existed in the West. | 0 | Theoretical and Fundamental Chemistry |
Although fluorescent dyes may not have the same sensitivity as radioactive probes, they are able to show real-time activity of molecules in action. Moreover, radiation and appropriate handling is no longer a concern.
With the development of fluorescent tagging, fluorescence microscopy has allowed the visualization of specific proteins in both fixed and live cell images. Localization of specific proteins has led to important concepts in cellular biology such as the functions of distinct groups of proteins in cellular membranes and organelles. In live cell imaging, fluorescent tags enable movements of proteins and their interactions to be monitored.
Latest advances in methods involving fluorescent tags have led to the visualization of mRNA and its localization within various organisms. Live cell imaging of RNA can be achieved by introducing synthesized RNA that is chemically coupled with a fluorescent tag into living cells by microinjection. This technique was used to show how the oskar mRNA in the Drosophila embryo localizes to the posterior region of the oocyte. | 1 | Applied and Interdisciplinary Chemistry |
IPCs are finding applications in pharmaceutics in the design of novel dosage forms. They also are increasingly used to form various coatings using layer-by-layer deposition approach. Some IPCs were proposed for application as membranes and films. They also have been used for structuring of soils to protect from erosion. Other applications include encapsulation technologies. | 0 | Theoretical and Fundamental Chemistry |
Upon irradiation with UV light, diazirines form reactive carbene species. The carbene may exist in the singlet form, in which the two free electrons occupy the same orbital, or the triplet form, with two unpaired electrons in different orbitals. | 0 | Theoretical and Fundamental Chemistry |
Davy's lectures included spectacular and sometimes dangerous chemical demonstrations along with scientific information, and were presented with considerable showmanship by the young and handsome man.
Davy also included both poetic and religious commentary in his lectures, emphasizing that Gods design was revealed by chemical investigations. Religious commentary was in part an attempt to appeal to women in his audiences. Davy, like many of his enlightenment contemporaries, supported female education and womens involvement in scientific pursuits, even proposing that women be admitted to evening events at the Royal Society.
Davy acquired a large female following around London. In a satirical cartoon by Gillray, nearly half of the attendees pictured are female. His support of women caused Davy to be subjected to considerable gossip and innuendo, and to be criticised as unmanly. | 1 | Applied and Interdisciplinary Chemistry |
The Bernoulli equation for unsteady potential flow is used in the theory of ocean surface waves and acoustics. For an irrotational flow, the flow velocity can be described as the gradient of a velocity potential . In that case, and for a constant density , the momentum equations of the Euler equations can be integrated to:
which is a Bernoulli equation valid also for unsteady—or time dependent—flows. Here denotes the partial derivative of the velocity potential with respect to time , and is the flow speed. The function depends only on time and not on position in the fluid. As a result, the Bernoulli equation at some moment applies in the whole fluid domain. This is also true for the special case of a steady irrotational flow, in which case and are constants so equation () can be applied in every point of the fluid domain. Further can be made equal to zero by incorporating it into the velocity potential using the transformation:
resulting in:
Note that the relation of the potential to the flow velocity is unaffected by this transformation: .
The Bernoulli equation for unsteady potential flow also appears to play a central role in Luke's variational principle, a variational description of free-surface flows using the Lagrangian mechanics. | 1 | Applied and Interdisciplinary Chemistry |
Halothane, sold under the brand name Fluothane among others, is a general anaesthetic. It can be used to induce or maintain anaesthesia. One of its benefits is that it does not increase the production of saliva, which can be particularly useful in those who are difficult to intubate. It is given by inhalation.
Side effects include an irregular heartbeat, respiratory depression, and hepatotoxicity. Like all volatile anesthetics, it should not be used in people with a personal or family history of malignant hyperthermia. It appears to be safe in porphyria. It is unclear whether its usage during pregnancy is harmful to the fetus, and its use during a C-section is generally discouraged. Halothane is a chiral molecule that is used as a racemic mixture.
Halothane was discovered in 1951. It was approved for medical use in the United States in 1958. It is on the World Health Organization's List of Essential Medicines. Its use in developed countries has been mostly replaced by newer anesthetic agents such as sevoflurane. It is no longer commercially available in the United States. Halothane also contributes to ozone depletion. | 0 | Theoretical and Fundamental Chemistry |
For buffers in acid regions, the pH may be adjusted to a desired value by adding a strong acid such as hydrochloric acid to the particular buffering agent. For alkaline buffers, a strong base such as sodium hydroxide may be added. Alternatively, a buffer mixture can be made from a mixture of an acid and its conjugate base. For example, an acetate buffer can be made from a mixture of acetic acid and sodium acetate. Similarly, an alkaline buffer can be made from a mixture of the base and its conjugate acid. | 0 | Theoretical and Fundamental Chemistry |
The space groups in three dimensions are made from combinations of the 32 crystallographic point groups with the 14 Bravais lattices, each of the latter belonging to one of 7 lattice systems. What this means is that the action of any element of a given space group can be expressed as the action of an element of the appropriate point group followed optionally by a translation. A space group is thus some combination of the translational symmetry of a unit cell (including lattice centering), the point group symmetry operations of reflection, rotation and improper rotation (also called rotoinversion), and the screw axis and glide plane symmetry operations. The combination of all these symmetry operations results in a total of 230 different space groups describing all possible crystal symmetries.
The number of replicates of the asymmetric unit in a unit cell is thus the number of lattice points in the cell times the order of the point group. This ranges from 1 in the case of space group P1 to 192 for a space group like Fmm, the NaCl structure. | 0 | Theoretical and Fundamental Chemistry |
After postdoctoral fellowships with P. J. Bailey at the University of Edinburgh, Keith Izod at Newcastle University as the Wilfred Hall Research Fellow, and Polly Arnold at the University of Nottingham, Liddle began his independent academic career at the University of Nottingham with a Royal Society University Research Fellowship (2007–2015) held with a proleptic Lectureship. He was promoted to Associate Professor and Reader in 2010 and Professor of Inorganic Chemistry in 2013.
He moved to the University of Manchester in 2015 as Head of Inorganic Chemistry and Co-Director of the Centre for Radiochemistry Research. He held an Engineering and Physical Sciences Research Council Established Career Fellowship (2015–2021).
He was Chairman of COST Action CM1006, a 22 country, research network of over 120 research groups in f-block chemistry (2011–2015), is an advisor to the Commonwealth Scholarship Commission (2013–), and was an elected category 3 member of Senate, the University of Manchester (2016–2019).
Liddle's research is focused on synthetic inorganic chemistry, particularly making early transition metal, lanthanide, and actinide complexes to explore their structure, bonding, reactivity, and magnetism. In 2011 he reported a single-molecule magnet based on depleted uranium. In 2012 his research group was the first to synthesize a molecular terminal uranium(V) nitride.
In 2013 he reported the isolation of a terminal uranium(VI) nitride akin to examples previously restricted to cryogenic matrix isolation experiments. Also in 2013, his research group disclosed the first f-element cyclobutadienyl complexes. In 2015 he reported a uranium(IV)-arsenido complex containing uranium-arsenic triple bonds. In 2019 his research group isolated a uranium(V)-dinitrogen complex. In 2021, Liddle reported a tri-thorium cluster featuring σ-aromatic actinide metal-metal bonding. Before the synthesis of this complex, examples of actinide-actinide bonding had been restricted to matrix isolation experiments and fullerene-encapsulated species.
In 2022, he reported a terminal neptunium(V)-mono(oxo) complex. Before the synthesis of this complex all transuranium-ligand multiple bond complexes required two or more metal-ligand multiple bonds to be stable. | 0 | Theoretical and Fundamental Chemistry |
In vertebrate biology, iodine's primary function is as a constituent of the thyroid hormones, thyroxine (T4) and triiodothyronine (T3). These molecules are made from addition-condensation products of the amino acid tyrosine, and are stored prior to release in an iodine-containing protein called thyroglobulin. T4 and T3 contain four and three atoms of iodine per molecule, respectively; iodine accounts for 65% of the molecular weight of T4 and 59% of T3. The thyroid gland actively absorbs iodine from the blood to produce and release these hormones into the blood, actions which are regulated by a second hormone, called thyroid-stimulating hormone (TSH), which is produced by the pituitary gland. Thyroid hormones are phylogenetically very old molecules which are synthesized by most multicellular organisms, and which even have some effect on unicellular organisms.
Thyroid hormones play a fundamental role in biology, acting upon gene transcription mechanisms to regulate the basal metabolic rate. T3 acts on small intestine cells and adipocytes to increase carbohydrate absorption and fatty acid release, respectively. A deficiency of thyroid hormones can reduce basal metabolic rate up to 50%, while an excessive production of thyroid hormones can increase the basal metabolic rate by 100%. T4 acts largely as a precursor to T3, which is (with minor exceptions) the biologically active hormone.
Via the thyroid hormones, iodine has a nutritional relationship with selenium. A family of selenium-dependent enzymes called deiodinases converts T4 to T3 (the active hormone) by removing an iodine atom from the outer tyrosine ring. These enzymes also convert T4 to reverse T3 (rT3) by removing an inner ring iodine atom, and also convert T3 to 3,3'-Diiodothyronine (T2) by removing an inner ring atom. Both of the latter products are inactivated hormones which have essentially no biological effects and are quickly prepared for disposal. A family of non-selenium-dependent enzymes then further deiodinates the products of these reactions.
The total amount of iodine in the human body is still controversial, and in 2001, M.T. Hays published in Thyroid that "it is surprising that the total iodine content of the human body remains uncertain after many years of interest in iodine metabolism. Only the iodine content of the thyroid gland has been measured accurately by fluorescent scanning, and it is now well estimate of 5–15 mg in the normal human thyroid. But similar methods are not available for other tissues and for the extrathyroidal organs. Many researchers reported different numbers of 10–50 mg of the total iodine content in human body".
Selenium also plays a very important role in the production of glutathione, the body's most powerful antioxidant. During the production of the thyroid hormones, hydrogen peroxide is produced in large quantities, and therefore high iodine in the absence of selenium can destroy the thyroid gland (often described as a sore throat feeling); the peroxides are neutralized through the production of glutathione from selenium. In turn, an excess of selenium increases demand for iodine, and deficiency will result when a diet is high in selenium and low in iodine. | 1 | Applied and Interdisciplinary Chemistry |
Acid chlorides are useful for the preparation of amides, esters, anhydrides. These reactions generate chloride, which can be undesirable. Acyl chlorides hydrolyze, yielding the carboxylic acid:
This hydrolysis is usually a nuisance rather than intentional. Acyl chlorides are used to prepare acid anhydrides, amides and esters, by reacting acid chlorides with: a salt of a carboxylic acid, an amine, or an alcohol, respectively. | 0 | Theoretical and Fundamental Chemistry |
Polysaccharides with unprotected vicinal diols or amino sugars (where some hydroxyl groups are replaced with amines) give a positive periodic acid-Schiff stain (PAS). The list of polysaccharides that stain with PAS is long. Although mucins of epithelial origins stain with PAS, mucins of connective tissue origin have so many acidic substitutions that they do not have enough glycol or amino-alcohol groups left to react with PAS. | 0 | Theoretical and Fundamental Chemistry |
The terms northern, western and eastern blotting are derived from what initially was a molecular biology joke that played on the term Southern blotting, after the technique described by Edwin Southern for the hybridisation of blotted DNA. Patricia Thomas, developer of the RNA blot which then became known as the northern blot, actually did not use the term. | 1 | Applied and Interdisciplinary Chemistry |
Although as a general rule, dietary supplement labeling and marketing are not allowed to make disease prevention or treatment claims, the FDA has for some foods and dietary supplements reviewed the science, concluded that there is significant scientific agreement, and published specifically worded allowed health claims. An initial ruling allowing a health claim for calcium dietary supplements and osteoporosis was later amended to include calcium and vitamin D supplements, effective January 1, 2010. Examples of allowed wording are shown below. In order to qualify for the calcium health claim, a dietary supplement must contain at least 20% of the Reference Dietary Intake, which for calcium means at least 260 mg/serving.
*"Adequate calcium throughout life, as part of a well-balanced diet, may reduce the risk of osteoporosis."
*"Adequate calcium as part of a healthful diet, along with physical activity, may reduce the risk of osteoporosis in later life."
*"Adequate calcium and vitamin D throughout life, as part of a well-balanced diet, may reduce the risk of osteoporosis."
*"Adequate calcium and vitamin D as part of a healthful diet, along with physical activity, may reduce the risk of osteoporosis in later life."
In 2005 the FDA approved a Qualified Health Claim for calcium and hypertension, with suggested wording "Some scientific evidence suggests that calcium supplements may reduce the risk of hypertension. However, FDA has determined that the evidence is inconsistent and not conclusive." Evidence for pregnancy-induced hypertension and preeclampsia was considered inconclusive. The same year the FDA approved a QHC for calcium and colon cancer, with suggested wording "Some evidence suggests that calcium supplements may reduce the risk of colon/rectal cancer, however, FDA has determined that this evidence is limited and not conclusive." Evidence for breast cancer and prostate cancer was considered inconclusive. Proposals for QHCs for calcium as protective against kidney stones or against menstrual disorders or pain were rejected.
The European Food Safety Authority (EFSA) concluded that "Calcium contributes to the normal development of bones." The EFSA rejected a claim that a cause-and-effect relationship existed between the dietary intake of calcium and potassium and maintenance of normal acid-base balance. The EFSA also rejected claims for calcium and nails, hair, blood lipids, premenstrual syndrome and body weight maintenance. | 1 | Applied and Interdisciplinary Chemistry |
In 1997 France became the first country to ban minors from indoor tanning. Under-18s are similarly prohibited in Austria, Belgium, Germany, Ireland, Portugal, Spain, Poland and the United Kingdom. In addition, Ireland prohibits salons from offering "happy hour" discounts. Netherlands also forbid the usage of a tanning bed below the age of 18. | 0 | Theoretical and Fundamental Chemistry |
The shape of a micelle is directly dependent on the packing parameter of the surfactant. Surfactants with a packing parameter of ≤ 1/3 appear to have a cone-like shape which will pack together to form spherical micelles when in an aqueous environment (top in figure). Surfactants with a packing parameter of 1/3 ≤ 1/2 appear to have a wedge-like shape and will aggregate together in an aqueous environment to form cylindrical micelles (bottom in figure). Surfactants with a packing parameter of > 1/2 appear to have a cylindrical shape and pack together to form a bilayer in an aqueous environment (middle in figure). | 0 | Theoretical and Fundamental Chemistry |
Recognizing the habit can aid in mineral identification and description, as the crystal habit is an external representation of the internal ordered atomic arrangement. Most natural crystals, however, do not display ideal habits and are commonly malformed. Hence, it is also important to describe the quality of the shape of a mineral specimen:
* Euhedral: a crystal that is completely bounded by its characteristic faces, well-formed. Synonymous terms: idiomorphic, automorphic;
* Subhedral: a crystal partially bounded by its characteristic faces and partially by irregular surfaces. Synonymous terms: hypidiomorphic, hypautomorphic;
* Anhedral: a crystal that lacks any of its characteristic faces, completely malformed. Synonymous terms: allotriomorphic, xenomorphic. | 0 | Theoretical and Fundamental Chemistry |
Although the phenomenon we now call dielectrophoresis was described in passing as far back as the early 20th century, it was only subject to serious study, named and first understood by Herbert Pohl in the 1950s. Recently, dielectrophoresis has been revived due to its potential in the manipulation of microparticles, nanoparticles and cells.
Dielectrophoresis occurs when a polarizable particle is suspended in a non-uniform electric field. The electric field polarizes the particle, and the poles then experience a force along the field lines, which can be either attractive or repulsive according to the orientation on the dipole. Since the field is non-uniform, the pole experiencing the greatest electric field will dominate over the other, and the particle will move. The orientation of the dipole is dependent on the relative polarizability of the particle and medium, in accordance with Maxwell–Wagner–Sillars polarization. Since the direction of the force is dependent on field gradient rather than field direction, DEP will occur in AC as well as DC electric fields; polarization (and hence the direction of the force) will depend on the relative polarizabilities of particle and medium. If the particle moves in the direction of increasing electric field, the behavior is referred to as positive DEP (sometime pDEP), if acting to move the particle away from high field regions, it is known as negative DEP (or nDEP). As the relative polarizabilities of the particle and medium are frequency-dependent, varying the energizing signal and measuring the way in which the force changes can be used to determine the electrical properties of particles; this also allows the elimination of electrophoretic motion of particles due to inherent particle charge.
Phenomena associated with dielectrophoresis are electrorotation and traveling wave dielectrophoresis (TWDEP). These require complex signal generation equipment in order to create the required rotating or traveling electric fields, and as a result of this complexity have found less favor among researchers than conventional dielectrophoresis. | 0 | Theoretical and Fundamental Chemistry |
n-BuLi exists as a cluster both in the solid state and in a solution. The tendency to aggregate is common for organolithium compounds. The aggregates are held together by delocalized covalent bonds between lithium and the terminal carbon of the butyl chain. In the case of n-BuLi, the clusters are tetrameric (in ether) or hexameric (in cyclohexane). The cluster is a distorted cubane-type cluster with Li and CHR groups at alternating vertices. An equivalent description describes the tetramer as a Li tetrahedron interpenetrated with a tetrahedron [CHR]. Bonding within the cluster is related to that used to describe diborane, but more complex since eight atoms are involved. Reflecting its electron-rich character, n-butyllithium is highly reactive toward Lewis acids.
Due to the large difference between the electronegativities of carbon (2.55) and lithium (0.98), the C−Li bond is highly polarized. The charge separation has been estimated to be 55–95%. For practical purposes, n-BuLi can often be considered to react as the butyl anion, n-Bu, and a lithium cation, Li. | 0 | Theoretical and Fundamental Chemistry |
RiAFP refers to an antifreeze protein (AFP) produced by the Rhagium inquisitor longhorned beetle. It is a type V antifreeze protein with a molecular weight of 12.8 kDa; this type of AFP is noted for its hyperactivity. R. inquisitor is a freeze-avoidant species, meaning that, due to its AFP, R. inquisitor prevents its body fluids from freezing altogether. This contrasts with freeze-tolerant species, whose AFPs simply depress levels of ice crystal formation in low temperatures. Whereas most insect antifreeze proteins contain cysteines at least every sixth residue, as well as varying numbers of 12- or 13-mer repeats of 8.3-12.5kDa, RiAFP is notable for containing only one disulfide bridge. This property of RiAFP makes it particularly attractive for recombinant expression and biotechnological applications. | 1 | Applied and Interdisciplinary Chemistry |
Depending on the gas flow characteristics in the system there are two states that can be matter of simulation:
* Steady state – the simulation does not take into account the gas flow characteristics' variations over time and described by the system of algebraic equations, in general nonlinear ones.
* Unsteady state (transient flow analysis) – described either by a partial differential equation or a system of such equations. Gas flow characteristics are mainly functions of time. | 1 | Applied and Interdisciplinary Chemistry |
A chemical glycosylation reaction involves the coupling of a glycosyl donor, to a glycosyl acceptor forming a glycoside. If both the donor and acceptor are sugars, then the product is an oligosaccharide. The reaction requires activation with a suitable activating reagent. The reactions often result in a mixture of products due to the creation of a new stereogenic centre at the anomeric position of the glycosyl donor. The formation of a glycosidic linkage allows for the synthesis of complex polysaccharides which may play important roles in biological processes and pathogenesis and therefore having synthetic analogs of these molecules allows for further studies with respect to their biological importance. | 0 | Theoretical and Fundamental Chemistry |
Raoults law was first observed empirically and led François-Marie Raoult to postulate that the vapor pressure above an ideal mixture of liquids is equal to the sum of the vapor pressures of each component multiplied by its mole fraction. Taking compliance with Raoults Law as a defining characteristic of ideality in a solution, it is possible to deduce that the chemical potential of each component of the liquid is given by
where is the chemical potential in the pure state and is the mole fraction of component in the ideal solution. From this equation, other thermodynamic properties of an ideal solution may be determined. If the assumption that the vapor follows the ideal gas law is added, Raoult's law may be derived as follows.
If the system is ideal, then, at equilibrium, the chemical potential of each component must be the same in the liquid and gas states. That is,
Substituting the formula for chemical potential gives
as the gas-phase mole fraction depends on its fugacity, , as a fraction of the pressure in the reference state, .
The corresponding equation when the system consists purely of component in equilibrium with its vapor is
Subtracting these equations and re-arranging leads to the result
For the ideal gas, pressure and fugacity are equal, so introducing simple pressures to this result yields Raoult's law: | 0 | Theoretical and Fundamental Chemistry |
Exposure of concrete structures to neutrons and gamma radiation in nuclear power plants, and high-flux material testing reactors, can induce radiation damage to their concrete structural components. Paramagnetic defects and optical centers are easily formed, but very high fluxes are necessary to displace a sufficiently high number of atoms in the crystal lattice of the minerals present in concrete before significant mechanical damage is observed.
However, neutron irradiation with a very high neutron fluence (number of neutrons per unit of cross-section area: neutron/cm) is known to render amorphous a fraction of the quartz present in some concrete aggregates. This amorphization process is also called metamictization. Metamict quartz with its disordered lattice structure is prone to alkali–silica reaction and can thus be responsible of harmful chemical expansion in the concrete of nuclear containment structures. | 1 | Applied and Interdisciplinary Chemistry |
In contrast to traditional combinatorial synthesis where a library of catalysts were first generated and later screened (as in the two above approaches), dynamic combinatorial library approach utilizes a mixture of multicomponent building blocks that reversibly form library of catalysts. With out a template, the library consists of a roughly equal mixture of different combination of building blocks. In the presence of a template which is either a starting material or a TSA, the combination that provides the best binding to the template is thermodynamically favorable and thus that combination is more prevalent than other library members. The biased ratio of the desired catalyst to other combinatorial products could then be frozen by terminating the reversibility of the equilibrium by means such as change in temperature, pH, or radiation to yield the optimal catalyst. For example, Lehn et al. used this method to create a dynamic combinatorial library of imine inhibitor from a set of amines and a set of aldehydes. After some time, the equilibrium was terminated by an addition of NaBHCN to afford the desired catalyst. | 0 | Theoretical and Fundamental Chemistry |
Poolman was born in 1959 as the first son of Jelto Poolman and Neeltje Prinsse. In 1983 he married Heleen Stevenson (1959), with whom he has four children. | 0 | Theoretical and Fundamental Chemistry |
Oral levels in mice and rats are 3547–2545 mg/kg body weight (male and female) and 474–365 (male and female), respectively. | 0 | Theoretical and Fundamental Chemistry |
Synthesis of thalidomide has usually been performed as seen in scheme 1. This synthesis is a reasonably simplistic three step process. The downside of this process however is that the last step requires a high-temperature melt reaction which demands multiple recrystallizations and is not compliant with standard equipment.
Scheme 2 is the newer synthesis route which was designed to make the reaction more direct and to produce better yields. This route uses -glutamine rather than -glutamic acid as a starting material and by letting it react with N-carbethoxyphthalimide gives N-phthaloyl--glutamine (4), with 50–70% yield. The substance 4 is then stirred in a mixture with carbonyldiimidazole (CDI) with enough 4-dimethylaminopyridine (DMAP) in tetrahydrofuran (THF) to catalyze the reaction and heated to reflux for 15–18 hours. During the reflux thalidomide crystallizes out of the mixture. The final step gives 85–93% yield of thalidomide, bringing the total yield to 43–63%. | 1 | Applied and Interdisciplinary Chemistry |
One of the most widely used tools for probing glycan-protein interactions is glycan arrays. A glycan array usually is an NHS- or epoxy-activated glass slides on which various glycans were printed using robotic printing. These commercially available arrays may contain up to 600 different glycans, specificity of which has been extensively studied.
Glycan-protein interactions may be detected by testing proteins of interest (or libraries of those) that bear fluorescent tags. The structure of the glycan-binding protein may be deciphered by several analytical methods based on mass-spectrometry, including MALDI-MS, LC-MS, tandem MS-MS, and/or 2D NMR. | 1 | Applied and Interdisciplinary Chemistry |
Acid–base extraction is a subclass of liquid–liquid extractions and involves the separation of chemical species from other acidic or basic compounds. It is typically performed during the work-up step following a chemical synthesis to purify crude compounds and results in the product being largely free of acidic or basic impurities. A separatory funnel is commonly used to perform an acid-base extraction.
Acid-base extraction utilizes the difference in solubility of a compound in its acid or base form to induce separation. Typically, the desired compound is changed into its charged acid or base form, causing it to become soluble in aqueous solution and thus be extracted from the non-aqueous (organic) layer. Acid-base extraction is a simple alternative to more complex methods like chromatography. It is not possible to separate chemically similar acids or bases using this simple method. | 0 | Theoretical and Fundamental Chemistry |
In the European Union, 0.8% of total energy consumption goes to wastewater treatment facilities. The European Union needs to make extra investments of €90 billion in the water and waste sector to meet its 2030 climate and energy goals.
In October 2021, British Members of Parliament voted to continue allowing untreated sewage from combined sewer overflows to be released into waterways. | 1 | Applied and Interdisciplinary Chemistry |
Levetiracetam is effective as single-drug treatment for newly diagnosed focal epilepsy in adults. It reduces focal seizures by 50% or more as an add-on medication. | 0 | Theoretical and Fundamental Chemistry |
Both carburetors and fuel injector components of internal combustion engines benefit from detergents in the fuels to prevent fouling. Concentrations are about 300 ppm. Typical detergents are long-chain amines and amides such as polyisobuteneamine and polyisobuteneamide/succinimide. | 0 | Theoretical and Fundamental Chemistry |
Fenton's reagent is used as a sewage treatment agent.
Fenton's reagent can be used in different chemical procesess that supply hydroxyl ion or oxidize certain compounds:
* The first stage of Fenton’s reaction (oxidation of Fe with hydrogen peroxide) is used in Haber–Weiss reaction
* Fenton's reagent can be used in organic synthesis reactions: e.g. hydroxylation of arenes via a free radical substitution
* Conversion of benzene into phenol by using Fenton's reagent
* Oxidation of barbituric acid into alloxan.
* Coupling reactions of alkanes | 1 | Applied and Interdisciplinary Chemistry |
dPCR rose out of an approach first published in 1988 by Cetus Corporation when researchers showed that a single copy of the β-globin gene could be detected and amplified by PCR. This was achieved by diluting DNA samples from a normal human cell line with DNA from a mutant line having a homozygous deletion of the β-globin gene, until it was no longer present in the reaction. In 1989, Peter Simmonds, AJ Brown et al. used this concept to quantify a molecule for the first time. Alex Morley and Pamela Sykes formally established the method as a quantitative technique in 1992.
In 1999, Bert Vogelstein and Kenneth Kinzler coined the term “digital PCR” and showed that the technique could be used to find rare cancer mutations. However, dPCR was difficult to perform; it was labor intensive, required a lot of training to do properly, and was difficult to do in large quantities. In 2003, Kinzler and Vogelstein continued to refine dPCR and created an improved method that they called BEAMing technology, an acronym for “beads, emulsion, amplification and magnetics.” The new protocol used emulsion to compartmentalize amplification reactions in a single tube. This change made it possible for scientists to scale the method to thousands of reactions in a single run.
Companies developing commercial dPCR systems have integrated technologies like automated partitioning of samples, digital counting of nucleic acid targets, and increasing droplet count that can help the process be more efficient. In recent years, scientists have developed and commercialized dPCR-based diagnostics for several conditions, including non-small cell lung cancer and Down’s Syndrome. The first dPCR system for clinical use was CE-marked in 2017 and cleared by the US Food and Drug Administration in 2019, for diagnosing chronic myeloid leukemia. | 1 | Applied and Interdisciplinary Chemistry |
While the chlorophyll concentration decreases, leaves have more leaf mass per unit leaf area, and as a result the chlorophyll content per unit leaf area is relatively unaffected. This is also true for the light absorptance of a leaf. Leaf light reflectance goes up and leaf light transmittance goes down. Per unit leaf area there is more RuBisCO and a higher photosynthetic rate under light-saturated conditions. Expressed per unit leaf dry mass, however, photosynthetic capacity decreases. | 0 | Theoretical and Fundamental Chemistry |
Application of solar cells as an alternative energy source for vehicular applications is a growing industry. Electric vehicles that operate off of solar energy and/or sunlight are commonly referred to as solar cars. These vehicles use solar panels to convert absorbed light into electrical energy that is then stored in batteries. There are multiple input factors that affect the output power of solar cells such as temperature, material properties, weather conditions, solar irradiance and more.
The first instance of photovoltaic cells within vehicular applications was around midway through the second half of the 1900's. In an effort to increase publicity and awareness in solar powered transportation Hans Tholstrup decided to set up the first edition of the World Solar Challenge in 1987. It was a 3000 km race across the Australian outback where competitors from industry research groups and top universities around the globe were invited to compete. General Motors ended up winning the event by a significant margin with their Sunraycer vehicle that achieved speeds of over 40 mph. Contrary to popular belief however solar powered cars are one of the oldest alternative energy vehicles.
Current solar vehicles harness energy from the Sun via Solar panels which are a collected group of solar cells working in tandem towards a common goal. These solid-state devices use quantum mechanical transitions in order to convert a given amount of solar power into electrical power. The electricity produced as a result is then stored in the vehicle's battery in order to run the motor of the vehicle. Batteries in solar-powered vehicles differ from those in standard ICE cars because they are fashioned in a way to impart more power towards the electrical components of the vehicle for a longer duration. | 0 | Theoretical and Fundamental Chemistry |
Some can be useful in measuring rates of metabolic processes (for example, 3,4-dihydroxyphenylacetic acid or 3-aminoisobutyrate).
Because they can represent unnatural points of entry into natural metabolic pathways, some (such as AICA ribonucleotide) are of interest to researchers in developing new therapies. | 1 | Applied and Interdisciplinary Chemistry |
Possible biomedical-oriented applications of this technique are related to the study of the myelin and myelopathies. Myelin is a highly ordered structure, in which many lipid-
enriched, densely compacted phospholipid bilayers are spirally rolled up around the
cylindrical axons. The linear acyl chains of the phospholipid molecules present a
perpendicular orientation with respect to the myelin surface. Therefore, in a myelinated nerve
fiber, a large number of molecular bonds are ordered around a radial axis of symmetry. Such a
strong molecular anisotropy and azimuthal symmetry make RP-CARS a suitable tool to investigate
neural white matter. | 0 | Theoretical and Fundamental Chemistry |
A chemical library or compound library is a collection of stored chemicals usually used ultimately in high-throughput screening or industrial manufacture. The chemical library can consist in simple terms of a series of stored chemicals. Each chemical has associated information stored in some kind of database with information such as the chemical structure, purity, quantity, and physiochemical characteristics of the compound. | 1 | Applied and Interdisciplinary Chemistry |
Dendrosomes have been explored as vectors in gene delivery and genetic immunization.
Poly (propyleneimine) dendrosome based genetic immunization against Hepatitis B was found to be highly effective as compared to Dendrimer-Plasmid DNA complex. It has been postulated that in dendrosomes, the poly (propyleneimine) dendrimer–DNA complex is largely protected by multilamelarity of the vesicles. Moreover, it has been hypothesized that the lipoidal layers of the dendrosomes modifies the release pattern of the poly (propyleneimine) dendrimer –DNA complex, while some of the larger vesicles remain at the site of injection following their degradation by tissue phospholipases, the smaller ones delivering and transfecting efficiently the antigen-presenting cells (APC) in the draining lymph nodes. Dendrosomes have also been explored for the delivery of s10siRNA targeting E6/E7 oncogenes in cervical cancer. It has been reported that polyamidoamine dendrimer based dendrosomes are efficient systems for the delivery of siRNA for effective management of cervical cancer. | 0 | Theoretical and Fundamental Chemistry |
Nitrite is detected and analyzed by the formation of a red pink colour upon treatment of a nitrite-containing sample with the Griess reagent, which consists of two components in an acidic solution: an aniline derivative and a coupling agent. The most common arrangements use sulfanilamide and N-(1-naphthyl)ethylenediamine: a typical commercial Griess reagent contains 0.2% N-(1-naphthyl)ethylenediamine dihydrochloride, and 2% sulfanilamide in 5% phosphoric acid. This diamine is used in place of the simpler and cheaper 1-naphthylamine because the latter is a potent carcinogen and moreover the diamine forms a more polar and hence a much more soluble dye in acidic aqueous medium. Other aniline derivatives that have been used include sulfanilic acid, nitroaniline, and p-aminoacetophenone.
The Griess test involves two subsequent reactions. When sulfanilamide is added, the nitrite ion reacts with it in the Griess diazotization reaction to form a diazonium salt, which then reacts with N-(1-naphthyl)ethylenediamine in an azo coupling reaction, forming a pink-red azo dye.
Using a spectrophotometer, it is possible to quantitatively determine the nitrite concentration. The detection limit of the Griess test generally ranges between 0.02 and 2 μM, depending on the exact details of the specific components used in the Griess reagent. | 0 | Theoretical and Fundamental Chemistry |
An example of an autocrine agent is the cytokine interleukin-1 in monocytes. When interleukin-1 is produced in response to external stimuli, it can bind to cell-surface receptors on the same cell that produced it.
Another example occurs in activated T cell lymphocytes, i.e., when a T cell is induced to mature by binding to a peptide:MHC complex on a professional antigen-presenting cell and by the B7:CD28 costimulatory signal. Upon activation, "low-affinity" IL-2 receptors are replaced by "high-affinity" IL-2 receptors consisting of α, β, and γ chains. The cell then releases IL-2, which binds to its own new IL-2 receptors, causing self-stimulation and ultimately a monoclonal population of T cells. These T cells can then go on to perform effector functions such as macrophage activation, B cell activation, and cell-mediated cytoxicity. | 1 | Applied and Interdisciplinary Chemistry |
Optoelectrowetting (OEW) is a method of liquid droplet manipulation used in microfluidics applications. This technique builds on the principle of electrowetting, which has proven useful in liquid actuation due to fast switching response times and low power consumption. Where traditional electrowetting runs into challenges, however, such as in the simultaneous manipulation of multiple droplets, OEW presents a lucrative alternative that is both simpler and cheaper to produce. OEW surfaces are easy to fabricate, since they require no lithography, and have real-time, reconfigurable, large-scale manipulation control, due to its reaction to light intensity. | 1 | Applied and Interdisciplinary Chemistry |
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