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Carbon monoxide for FT catalysis is derived from hydrocarbons. In gas to liquids (GTL) technology, the hydrocarbons are low molecular weight materials that often would be discarded or flared. Stranded gas provides relatively cheap gas. For GTL to be commercially viable, gas must remain relatively cheaper than oil.
Several reactions are required to obtain the gaseous reactants required for FT catalysis. First, reactant gases entering a reactor must be desulfurized. Otherwise, sulfur-containing impurities deactivate ("poison") the catalysts required for FT reactions.
Several reactions are employed to adjust the H:CO ratio. Most important is the water-gas shift reaction, which provides a source of hydrogen at the expense of carbon monoxide:
For FT plants that use methane as the feedstock, another important reaction is dry reforming, which converts the methane into CO and H: | 0 | Theoretical and Fundamental Chemistry |
Solid-state NMR has also been successfully used to study biomaterials such as bone, teeth, hair, silk, wood, as well as viruses, plants, cells, biopsies, and even live animals. | 0 | Theoretical and Fundamental Chemistry |
Radon concentration in open air varies between 1 and 100 Bq m. Radon can be found in some spring waters and hot springs. The towns of Misasa, Japan, and Bad Kreuznach, Germany boast radium-rich springs which emit radon, as does Radium Springs, New Mexico.
Radon exhausts naturally from the ground, particularly in certain regions, especially but not only regions with granitic soils. Not all granitic regions are prone to high emissions of radon, for instance while the rock which Aberdeen is on is very radium rich the rock lacks the cracks required for the radon to migrate. In other nearby areas of Scotland (to the north of Aberdeen) and in Cornwall/Devon the radon is very much able to leave the rock.
Radon is a decay product of radium which in turn is a decay product of uranium. Maps of average radon levels in houses are available, to assist in planning mitigation measures.
While high uranium in the soil/rock under a house does not always lead to a high radon level in air, a positive correlation between the uranium content of the soil and the radon level in air can be seen. | 0 | Theoretical and Fundamental Chemistry |
Jerry Pasker moved to South Cedar Street in Monticello, Iowa and was introduced to Harold Sovereign, who sold John Deere tractors and equipment. Pasker and Sovereign formed a partnership known as Industrious Farmer Equipment Company, and moved the business to the vacant second floor of Sovereigns dealership on South Cedar Street. In 1946 the business again outgrew its facility. To accommodate the expansion, Pasker purchased the property of an auto dealership on Main Street. During that time the company manufactured hydraulic components, wagon hoists, truck hoists, valves and hydraulic cylinders. In 1948 the companys name was changed to Energy Farm Equipment Company. In 1962 the business incorporated to become Energy Manufacturing Company, Inc., by which it is still known.
Jerry Pasker was killed in a 22 July 1964 airplane crash in Winnipeg, Manitoba, Canada; the company presidency then passed to LaVon Pasker. | 1 | Applied and Interdisciplinary Chemistry |
Caldoramide is a pentapeptide isolated from the cyanobacteria Caldora penicillata. It has cytotoxic effects on cancer cells and has been the subject of extensive oncological research. It is structurally analogous to belamide A and dolastatin 15. Its appearance is that of a powdery, white, substance. | 1 | Applied and Interdisciplinary Chemistry |
Pyridine has a flash point of 20 °C and is therefore highly flammable. Combustion produces toxic fumes which can include bipyridines, nitrogen oxides, and carbon monoxide. | 0 | Theoretical and Fundamental Chemistry |
Many processes contribute to soil acidification. These include:
* Rainfall: Average rainfall has a pH of 5.6 and is moderately acidic due to dissolved atmospheric carbon dioxide () that combines with water to form carbonic acid (). When this water flows through the soil it results in the leaching of basic cations as bicarbonates; this increases the percentage of and relative to other cations.
* Root respiration and decomposition of organic matter by microorganisms release which increases the carbonic acid () concentration and subsequent leaching.
* Plant growth: Plants take up nutrients in the form of ions (e.g. , , , ), and they often take up more cations than anions. However, plants must maintain a neutral charge in their roots. In order to compensate for the extra positive charge, they will release ions from the root. Some plants also exude organic acids into the soil to acidify the zone around their roots to help solubilize metal nutrients that are insoluble at neutral pH, such as iron (Fe).
* Fertilizer use: Ammonium () fertilizers react in the soil by the process of nitrification to form nitrate (), and in the process release ions.
* Acid rain: The burning of fossil fuels releases oxides of sulfur and nitrogen into the atmosphere. These react with water in the atmosphere to form sulfuric and nitric acid in rain.
* Oxidative weathering: Oxidation of some primary minerals, especially sulfides and those containing , generate acidity. This process is often accelerated by human activity:
** Mine spoil: Severely acidic conditions can form in soils near some mine spoils due to the oxidation of pyrite.
** Acid sulfate soils formed naturally in waterlogged coastal and estuarine environments can become highly acidic when drained or excavated. | 0 | Theoretical and Fundamental Chemistry |
Some of the oldest known examples of the lost-wax technique are the objects discovered in the Nahal Mishmar hoard in southern Land of Israel, and which belong to the Chalcolithic period (4500–3500 BC). Conservative Carbon-14 estimates date the items to around 3700 BC, making them more than 5700 years old. | 1 | Applied and Interdisciplinary Chemistry |
In the 1960s, thalidomide was successfully marketed as a safer alternative to barbiturates. Due to a successful marketing campaign, thalidomide was widely used by pregnant women during the first trimester of pregnancy. However, thalidomide is a teratogenic substance, and a proportion of children born during the 1960s had thalidomide embryopathy (TE). Of these babies born with TE, "about 40% of them died before their first birthday". The surviving individuals are now middle-aged and they report experiencing challenges (physical, psychological, and socioeconomic) related to TE.
Individuals born with TE frequently experience a wide variety of health problems secondary to their TE. These health conditions include both physical and psychological conditions. When compared to individuals of similar demographic profiles, those born with TE report less satisfaction with their quality of life and their overall health. Access to health care services can also be a challenge for these people, and women in particular have experienced difficulty in locating healthcare professionals who can understand and embrace their needs. | 0 | Theoretical and Fundamental Chemistry |
The AFM consists of a cantilever with a sharp tip (probe) at its end that is used to scan the specimen surface. The cantilever is typically silicon or silicon nitride with a tip radius of curvature on the order of nanometers. When the tip is brought into proximity of a sample surface, forces between the tip and the sample lead to a deflection of the cantilever according to Hooke's law. Depending on the situation, forces that are measured in AFM include mechanical contact force, van der Waals forces, capillary forces, chemical bonding, electrostatic forces, magnetic forces (see magnetic force microscope, MFM), Casimir forces, solvation forces, etc. Along with force, additional quantities may simultaneously be measured through the use of specialized types of probes (see scanning thermal microscopy, scanning joule expansion microscopy, photothermal microspectroscopy, etc.).
The AFM can be operated in a number of modes, depending on the application. In general, possible imaging modes are divided into static (also called contact) modes and a variety of dynamic (non-contact or "tapping") modes where the cantilever is vibrated or oscillated at a given frequency. | 0 | Theoretical and Fundamental Chemistry |
S1P is present at high concentrations in plasma and secreted locally at elevated concentrations at sites of inflammation. It is formed by the regulated phosphorylation of sphingosine. It acts through five dedicated high-affinity G-protein coupled receptors, S1P1 - S1P5. Targeted deletion of S1P1 results in lethality in mice and deletion of S1P2 results in seizures and deafness. Additionally, a mere 3- to 5-fold elevation in serum S1P concentrations induces sudden cardiac death by an S1P3-receptor specific mechanism. | 1 | Applied and Interdisciplinary Chemistry |
Failure of safety-critical polymer components can cause serious accidents, such as fire in the case of cracked and degraded polymer fuel lines. Chlorine-induced cracking of acetal resin plumbing joints and polybutylene pipes has caused many serious floods in domestic properties, especially in the US in the 1990s. Traces of chlorine in the water supply attacked polymers present in the plumbing, a problem which occurs faster if any of the parts have been poorly extruded or injection molded. Attack of the acetal joint occurred because of faulty molding, leading to cracking along the threads of the fitting where there is stress concentration.
Polymer oxidation has caused accidents involving medical devices. One of the oldest known failure modes is ozone cracking caused by chain scission when ozone gas attacks susceptible elastomers, such as natural rubber and nitrile rubber. They possess double bonds in their repeat units which are cleaved during ozonolysis. Cracks in fuel lines can penetrate the bore of the tube and cause fuel leakage. If cracking occurs in the engine compartment, electric sparks can ignite the gasoline and can cause a serious fire. In medical use degradation of polymers can lead to changes of physical and chemical characteristics of implantable devices.
Nylon 66 is susceptible to acid hydrolysis, and in one accident, a fractured fuel line led to a spillage of diesel into the road. If diesel fuel leaks onto the road, accidents to following cars can be caused by the slippery nature of the deposit, which is like black ice. Furthermore, the asphalt concrete road surface will suffer damage as a result of the diesel fuel dissolving the asphaltenes from the composite material, this resulting in the degradation of the asphalt surface and structural integrity of the road. | 0 | Theoretical and Fundamental Chemistry |
Absorbance is a number that measures the attenuation of the transmitted radiant power in a material. Attenuation can be caused by the physical process of "absorption", but also reflection, scattering, and other physical processes. Absorbance of a material is approximately equal to its attenuance when both the absorbance is much less than 1 and the emittance of that material (not to be confused with radiant exitance or emissivity) is much less than the absorbance. Indeed,
where
* is the radiant power transmitted by that material,
* is the radiant power attenuated by that material,
* is the radiant power received by that material, and
* is the radiant power emitted by that material.
This is equivalent to
where
* is the transmittance of that material,
* is the of that material,
* is the emittance of that material.
According to the Beer–Lambert law, , so
and finally | 0 | Theoretical and Fundamental Chemistry |
Oxidation of phosphinites gives phosphinates:
:2 P(OR)R + O → 2 OP(OR)R
Phosphinites are ligands, giving derivatives similar to metal phosphine complexes. They are stronger pi-acceptors than typical phosphine ligands. | 0 | Theoretical and Fundamental Chemistry |
GLD-2 is a common and abundant, but yet quite unknown protein that has already been found in each of the five kingdoms. In the animal kingdom, it has been specially detected in Homo sapiens, Drosophila, Xenopus and Mus musculus. However, there has also been noticed the presence of GLD-2 in Arabidopsis thaliana which belongs in the plants kingdom; Escherichia Coli in monera and Candida albicans in fungi.
In human beings it is mostly expressed in the brain and within it, in the cerebellum, hippocampus and medulla. We can also find them in some other source tissues are the fibroblast, HeLa cell, MCF-7 cell, melanoma cell line and thymus. Inside those cells, it can be located in the nucleus and mitochondrion since its main function is related with DNA polyadenilation and these cell organelles are the only ones were DNA can be found. However, there are also GLD-2 in a soluble way in the cytosol, although the reason why they are there is still unsure.
In Escherichia Coli, this enzymatic protein can be found in the cell membrane and in the cytosol, whereas in Drosophila melanogaster, it predominates in the brains nucleus and cytoplasm, oocyte, ovary and testis’ cells. Finally, in the Arabidopsis thaliana, it is located in the flowers nucleus, root, stem and leaf cells. | 1 | Applied and Interdisciplinary Chemistry |
A supersonic expansion fan, technically known as Prandtl–Meyer expansion fan, a two-dimensional simple wave, is a centered expansion process that occurs when a supersonic flow turns around a convex corner. The fan consists of an infinite number of Mach waves, diverging from a sharp corner. When a flow turns around a smooth and circular corner, these waves can be extended backwards to meet at a point.
Each wave in the expansion fan turns the flow gradually (in small steps). It is physically impossible for the flow to turn through a single "shock" wave because this would violate the second law of thermodynamics.
Across the expansion fan, the flow accelerates (velocity increases) and the Mach number increases, while the static pressure, temperature and density decrease. Since the process is isentropic, the stagnation properties (e.g. the total pressure and total temperature) remain constant across the fan.
The theory was described by Theodor Meyer on his thesis dissertation in 1908, along with his advisor Ludwig Prandtl, who had already discussed the problem a year before. | 1 | Applied and Interdisciplinary Chemistry |
In 1954, Oesper received the 5th annual Eminent Chemist award by the American Chemical Society. In 1956 he received the first Dexter Award for Outstanding Achievement in the History of Chemistry from the American Chemical Society. In 1966 he was awarded an honorary doctorate by the University of Cincinnati.
Oesper was a member of the editorial boards of the Journal of Chemical Education, Chymia, Mikrochemie, and Microchimica Acta.
Oesper bequeathed his extensive library to the University of Cincinnati. This included a financial endowment to fund projects on the history of chemistry. The University of Cincinnati with the Cincinnati section of the American Chemical Society present an annual Oesper Award and Symposium series, named in Ralph Oesper's honor. | 1 | Applied and Interdisciplinary Chemistry |
Francesco Selmi (7 April 1817 – 13 August 1881) was an Italian chemist and patriot, one of the founders of colloid chemistry.
Selmi was born in Vignola, then part of the Duchy of Modena and Reggio. He became head of a chemistry laboratory in Modena in 1840, and a professor of chemical pharmacology and toxicology at the University of Bologna in 1867. He published the first systematic study of inorganic colloids, in particular silver chloride, Prussian blue, and sulfur, in the period 1845–50.
He died in Vignola on 13 August 1881. | 0 | Theoretical and Fundamental Chemistry |
If the catalyst is a moderate base such as hydroxide ion or an alkoxide, the aldol reaction occurs via nucleophilic attack by the resonance-stabilized enolate on the carbonyl group of another molecule. The product is the alkoxide salt of the aldol product. Then aldol, the aldol addition product itself is then formed.
After which it may undergo dehydration to give a unsaturated carbonyl compound, the aldol condensation product. The scheme shows a simple mechanism for the base-catalyzed aldol reaction of an aldehyde with itself.
Base-catalyzed aldol reaction
Base-catalyzed dehydration
Although only a catalytic amount of base is required in some cases, the more usual procedure is to use a stoichiometric amount of a strong base such as LDA or NaHMDS. In this case, enolate formation is irreversible, and the aldol product is not formed until the metal alkoxide of the aldol product is protonated in a separate workup step. | 0 | Theoretical and Fundamental Chemistry |
The copper is of high purity, although earlier examples are sometimes composed of arsenical copper. Tylecote suggested that they are not primary smelting products and instead were refined and recast. The macrostructure of a half section example from Gillan, Cornwall shows a columnar structure that probably indicates slow cooling in a reheating furnace or a warm mold, rather than from pouring into a cold mold. | 1 | Applied and Interdisciplinary Chemistry |
Meibom obtained a PhD in physics at the University of Southern Denmark in 1997. He then pursued a two-and-a-half-year postdoc at the Hawaii Institute for Geophysics and Planetology where he studied the mineralogy of primitive chondrotic meteorites. In 2000, he moved to Stanford University as a research associate in the Stanford-USGS ion microprobe laboratory, department of geological and environmental sciences. In 2005, he was appointed as an associate professor at the Museum National d’Histoire Naturelle in Paris, where he was promoted to full professor in 2007. From 2006 to 2011, he served as the director of the French National NanoSIMS analytical facility. In 2012, he was named full professor at the EPFL (École Polytechnique Fédérale de Lausanne) in the School of Architecture, Civil and Environmental Engineering (ENAC). He has also been full professor ad personam at the University of Lausanne since 2014. From 2015 to 2017, he was the director of the Institute of Environmental Engineering at EPFL.
In 2019, Meibom founded the Transnational Red Sea Center (TRSC), an initiative for scientific diplomacy supported by the Swiss Federal Department of Foreign Affairs and which aims to promote scientific collaboration in a politically unstable region endowed with fundamental ecological stakes. | 0 | Theoretical and Fundamental Chemistry |
Criteria for EBSP selection can be one or a mixture of:
* Selecting from points with low GND density or low Kernel average misorientation (KAM) based on the Hough measured local grain misorientations;
* Selecting from points with high image quality (IQ), which may have a low defect density within its electron interaction volume, is therefore assumed to be a low-strained region of a polycrystalline material. However, IQ does not carry a clear physical meaning, and the magnitudes of the measured relative lattice distortion are insensitive to the IQ of EBSP;
* EBSP can also be manually selected to be far from potential stress concentrations such as grain boundaries, inclusions, or cracks using subjective criteria;
* Selecting an EBSP after examining the empirical relationship between the cross-correlation parameter and angular error, used in an iterative algorithm to identify the optimal reference pattern that maximises the precision of HR-EBSD.
These criteria assume these parameters can indicate the strain conditions at the reference point, which can produce an accurate measurements of up to 3.2×10 elastic strain. However, experimental measurements point to the inaccuracy of HR-EBSD in determining the out-of-plane shear strain components distribution and magnitude. | 0 | Theoretical and Fundamental Chemistry |
Particle advection and Finite-Time Lyapunov Exponent calculation:
* ManGen ([https://web.archive.org/web/20141001004042/http://homepages.ulb.ac.be/~lekien/mangen-1.4.4.zip source code])
* LCS MATLAB Kit ([http://dabiri.caltech.edu/software/LMK23.zip source code])
* FlowVC ([https://github.com/FlowPhysics/flowVC source code])
* cuda_ftle ([https://github.com/elehcim/cuda_ftle source code])
* CTRAJ
* Newman ([https://github.com/Shibabrat/Newman source code])
* FlowTK ([//github.com/FlowPhysics/FlowTK source code]) | 1 | Applied and Interdisciplinary Chemistry |
Though the ropB protein has 7 histidines (H12, H81, H93, H144, H265, H266, and H277) structurally present, the ropB histidine switch primarily operates with a single functionally involved histidine (H144) conveniently placed to associate with ropB sidechains (Y176 and E185) that near each other upon the addition of a hydrogen ion to H144 in acidic conditions. Only one histidine (H12) is located on the N-domain while the rest lie in the C-terminal domain. | 1 | Applied and Interdisciplinary Chemistry |
* In hot, humid climates, unconditioned ventilation air can daily deliver approximately 260 milliliters of water for each cubic meters per hour (m/h) of outdoor air (or one pound of water each day for each cubic feet per minute of outdoor air per day), annual average. This is a great deal of moisture and can create serious indoor moisture and mold problems. For example, given a 150 m building with an airflow of 180 m/h this could result in about 47 liters of water accumulated per day.
* Ventilation efficiency is determined by design and layout, and is dependent upon the placement and proximity of diffusers and return air outlets. If they are located closely together, supply air may mix with stale air, decreasing the efficiency of the HVAC system, and creating air quality problems.
* System imbalances occur when components of the HVAC system are improperly adjusted or installed and can create pressure differences (too much-circulating air creating a draft or too little circulating air creating stagnancy).
* Cross-contamination occurs when pressure differences arise, forcing potentially contaminated air from one zone to an uncontaminated zone. This often involves undesired odors or VOCs.
* Re-entry of exhaust air occurs when exhaust outlets and fresh air intakes are either too close, prevailing winds change exhaust patterns or infiltration between intake and exhaust air flows.
* Entrainment of contaminated outdoor air through intake flows will result in indoor air contamination. There are a variety of contaminated air sources, ranging from industrial effluent to VOCs put off by nearby construction work. | 1 | Applied and Interdisciplinary Chemistry |
Water oxidation is a more complex chemical reaction than proton reduction. In nature, the oxygen-evolving complex performs this reaction by accumulating reducing equivalents (electrons) in a manganese-calcium cluster within photosystem II (PS II), then delivering them to water molecules, with the resulting production of molecular oxygen and protons:
:2 HO → O + 4 H + 4e
Without a catalyst (natural or artificial), this reaction is very endothermic, requiring high temperatures (at least 2500 K).
The exact structure of the oxygen-evolving complex has been hard to determine experimentally. As of 2011, the most detailed model was from a 1.9 Å resolution crystal structure of photosystem II. The complex is a cluster containing four manganese and one calcium ions, but the exact location and mechanism of water oxidation within the cluster is unknown. Nevertheless, bio-inspired manganese and manganese-calcium complexes have been synthesized, such as [MnO] cubane-type clusters, some with catalytic activity.
Some ruthenium complexes, such as the dinuclear µ-oxo-bridged "blue dimer" (the first of its kind to be synthesized), are capable of light-driven water oxidation, thanks to being able to form high valence states. In this case, the ruthenium complex acts as both photosensitizer and catalyst. This complexes and other molecular catalysts still attract researchers in the field, having different advantages such as clear structure, active site, and easy to study mechanism. One of the main challenges to overcome is their short-term stability and their effective heterogenization for applications in artificial photosynthesis devices.
Many metal oxides have been found to have water oxidation catalytic activity, including ruthenium(IV) oxide (RuO), iridium(IV) oxide (IrO), cobalt oxides (including nickel-doped CoO), manganese oxide (including layered MnO (birnessite), MnO), and a mix of MnO with CaMnO. Oxides are easier to obtain than molecular catalysts, especially those from relatively abundant transition metals (cobalt and manganese), but suffer from low turnover frequency and slow electron transfer properties, and their mechanism of action is hard to decipher and, therefore, to adjust. | 0 | Theoretical and Fundamental Chemistry |
* Advantages
** Some advantages to Biological and bio-hybrid drug carriers include but are not limited to offering compatibility with the human immune system, having the potential to be genetically modified, and having the capacity to hold drugs. Moreover, an essential advantage is their natural property of homing to inflammation and tumor sites. This natural property of homing to inflammation and tumor sites can enhance the targeted delivery of drugs, minimizing the risk of off-target effects and reducing the required dosage. Additionally, these systems have the potential to increase drug stability and prolong circulation time in the body, improving drug efficacy and reducing the frequency of dosing. Overall, these advantages make biological and bio-hybrid drug carriers promising for developing more effective and targeted drug delivery systems.
* Limitations
** One limitation of Biological and bio-hybrid drug carriers, especially leukocytes, is that they have a low drug-carrying capacity. A limit in the carrying capacity of a carrier means that researchers will have to use more medication to achieve the desired therapeutic effect, increasing the risk of adverse side effects and the cost of the treatment. Moreover, the short lifespan can limit their potential use for long-term drug delivery applications [35]. Coupling this aspect with an inability to penetrate deep into tumors and the potential for genetic mutations can pose significant challenges for future drug delivery systems. Therefore, despite their advantages, further research and development are needed to address current limitations and improve their clinical feasibility. | 1 | Applied and Interdisciplinary Chemistry |
<div style="text-align: center;"><gallery mode="packed" caption="Many familiar bumblebees are Müllerian mimics, with effective stings and similar warning coloration">
File:Bombus terrestris (Buff-tailed bumblebee) - queen - Flickr - S. Rae.jpg|Bombus terrestris
File:Bombus lucorum - Centaurea scabiosa - Keila.JPG|Bombus lucorum
File:Bombus hortorum queen - Echium vulgare - Keila.jpg|Bombus hortorum
File:Tree bumblebee (RLs) (34742598795).jpg|Bombus hypnorum
Müllerian mimicry often occurs in clusters of multiple species called rings. Müllerian mimicry is not limited to butterflies, where rings are common; mimicry rings occur among Hymenoptera, such as bumblebees, and other insects, and among vertebrates including fish and coral snakes. Bumblebees Bombus are all aposematically coloured in combinations, often stripes, of black, white, yellow, and red; and all their females have stings, so they are certainly unprofitable to predators. There is evidence that several species of bumblebees in each of several areas of the world, namely the American West and East coasts, Western Europe, and Kashmir, have converged or adverged on mutually mimetic coloration patterns. Each of these areas has one to four mimicry rings, with patterns different from those in other areas.
The relationships among mimics can become complex. For example, the poison fangblenny Meiacanthus spp. have hollow canines and poison glands, and are avoided by predatory fish. The blenny Plagiotremus townsendi resembles Meiacanthus and is eaten by a variety of predators, so it is a Batesian mimic in their case: but it is avoided by the lionfish, Pterois volitans, making it also a Müllerian mimic.
Sets of associated rings are called complexes. Large complexes are known among the North American velvet ants in the genus Dasymutilla. Out of 351 species examined in one study, 336 had morphological similarities, apparently forming 8 distinct mimetic rings; 65 species in another study appeared to form six rings separable by both morphology and geography. | 1 | Applied and Interdisciplinary Chemistry |
NASAs announcement of a news conference "that will impact the search for evidence of extraterrestrial life" was criticized as sensationalistic and misleading; an editorial in New Scientist' commented "although the discovery of alien life, if it ever happens, would be one of the biggest stories imaginable, this was light-years from that".
In addition, many experts who have evaluated the paper have concluded that the reported studies do not provide enough evidence to support the claims made by the authors. In an online article on Slate, science writer Carl Zimmer discussed the skepticism of several scientists: "I reached out to a dozen experts ... Almost unanimously, they think the NASA scientists have failed to make their case". Chemist Steven A. Benner has expressed doubts that arsenate has replaced phosphate in the DNA of this organism. He suggested that the trace contaminants in the growth medium used by Wolfe-Simon in her laboratory cultures are sufficient to supply the phosphorus needed for the cells DNA. He believes that it is more likely that arsenic is being sequestered elsewhere in the cells. University of British Columbia microbiologist Rosemary Redfield said that the paper "doesnt present any convincing evidence that arsenic has been incorporated into DNA or any other biological molecule", and suggests that the experiments lacked the washing steps and controls necessary to properly validate their conclusions. Harvard microbiologist Alex Bradley said that arsenic-containing DNA would be so unstable in water it could not have survived the analysis procedure.
On 8 December 2010, Science published a response by Wolfe-Simon, in which she stated that criticism of the research was expected. In response, a "Frequently Asked Questions" page to improve understanding of the work was posted on 16 December 2010. The team plans to deposit the GFAJ-1 strain in the ATCC and DSMZ culture collections to allow widespread distribution. In late May 2011 the strain was made available upon request directly from the laboratory of the authors. Science has made the article freely available. The article was published in print six months after acceptance in the 3 June 2011 issue of Science. The publication was accompanied by eight technical comments addressing various concerns regarding the articles experimental procedure and conclusion, as well as a response by the authors to these concerns. The editor in chief Bruce Alberts has indicated that some issues remain and that their resolution is likely to be a long process. A review by Rosen et al., in the March 2011 issue of the journal BioEssays discusses the technical issues with the Science' paper, provides alternative explanations, and highlights known biochemistry of other arsenic resistant and arsenic utilizing microbes.
On 27 May 2011, Wolfe-Simon and her team responded to the criticism in a follow-up Science journal publication. Then in January 2012 a group of researchers led by Rosie Redfield at the University of British Columbia analyzed the DNA of GFAJ-1 using liquid chromatography–mass spectrometry and could not detect any arsenic, which Redfield calls a "clear refutation" of the original paper's findings. Following the publication of the analysis, Wolfe-Simon stated that she and her colleagues "expect to publish new information in the next few months", but as of 2024 has not submitted any new publications since 2011.
A simple explanation for the GFAJ-1 growth in medium supplied with arsenate instead of phosphate was provided by a team of researchers at the University of Miami in Florida. After labeling the ribosomes of a laboratory strain of Escherichia coli with radioactive isotopes (forming a radioactive tracer), they followed bacterial growth in medium containing arsenate but no phosphate. They found that arsenate induces massive degradation of ribosomes, thus providing sufficient phosphate for the slow growth of arsenate tolerant bacteria. Similarly, they suggest, GFAJ-1 cells grow by recycling phosphate from degraded ribosomes, rather than by replacing it with arsenate.
Following the publication of the articles challenging the conclusions of the original Science article first describing GFAJ-1, the website Retraction Watch argued that the original article should be retracted because of misrepresentation of critical data. , the paper had not been retracted. | 1 | Applied and Interdisciplinary Chemistry |
* [https://www.sciencehistory.org/scientists-you-must-know Scientists You Must Know: Pioneering steroid researcher George Rosenkranzh], Video, from the Scientists You Must Know Film Series, Science History Institute, Philadelphia, PA | 0 | Theoretical and Fundamental Chemistry |
Thermal hydrolysis is a two-stage process combining high-pressure boiling of waste or sludge followed by a rapid decompression. This combined action sterilizes the sludge and makes it more biodegradable, which improves digestion performance. Sterilization destroys pathogens in the sludge resulting in it exceeding the stringent requirements for land application (agriculture).
In addition, the treatment adjusts the rheology to such an extent that loading rates to sludge anaerobic digesters can be doubled, and also dewaterability of the sludge is significantly improved. The first full-scale application of this process for sewage sludge was installed in Hamar, Norway in 1996. Since then, there have been over 30 additional installations globally. | 0 | Theoretical and Fundamental Chemistry |
During 1773 Lavoisier determined to review thoroughly the literature on air, particularly "fixed air," and to repeat many of the experiments of other workers in the field. He published an account of this review in 1774 in a book entitled Opuscules physiques et chimiques (Physical and Chemical Essays). In the course of this review, he made his first full study of the work of Joseph Black, the Scottish chemist who had carried out a series of classic quantitative experiments on the mild and caustic alkalies. Black had shown that the difference between a mild alkali, for example, chalk (CaCO), and the caustic form, for example, quicklime (CaO), lay in the fact that the former contained "fixed air," not common air fixed in the chalk, but a distinct chemical species, now understood to be carbon dioxide (CO), which was a constituent of the atmosphere. Lavoisier recognized that Blacks fixed air was identical with the air evolved when metal calces were reduced with charcoal and even suggested that the air which combined with metals on calcination and increased the weight might be Blacks fixed air, that is, CO. | 1 | Applied and Interdisciplinary Chemistry |
Good tilth shares a balanced relation between soil-aggregate tensile strength and friability, in which it has a stable mixture of aggregate soil particles that can be readily broken up by shallow non-abrasive tilling. A high tensile strength will result in large cemented clods of compacted soil with low friability. Proper management of agricultural soils can positively impact soil aggregation and improve tilth quality.
Aggregation is positively associated with tilth. With finer-textured soils, aggregates may in turn be made up of smaller aggregates. Aggregation implies substantial pores between individual aggregates.
Aggregation is important in the subsoil, the layer below tillage. Such aggregates involve larger (2- to 6-inch) blocks of soil that are more angular and not as distinctive. These aggregates are less impacted by biological activity than the tillage layer. Subsurface aggregates are important for root growth deep into the profile. Deep roots allow greater access to moisture, which helps in drought periods. Subsoil aggregates can also be compacted, mainly by heavy equipment on wet soil. Another significant source of subsoil compaction is the practice of plowing with tractor wheels in the open furrow. | 0 | Theoretical and Fundamental Chemistry |
In 1927 Hitchins moved to Kenya, to join other members of her family who had emigrated there. Frederick Soddy wrote to the British Colonial Office, recommending her for a government position. Hitchins was employed as a Government Assayer and Chemist in the Mining and Geological Department of the Colonial Government until 1946. After her retirement, the department's annual report said of her that "she filled the post of Chemist and Assayer gaining an outstanding reputation for accuracy and complete reliability, and her loss was keenly felt by the mining industry."
In 1946, Hitchins married a farmer, John Ross Stephens (also spelled Rees).
Hitchins died in Bristol, England, on January 4, 1972. | 0 | Theoretical and Fundamental Chemistry |
Some capillary techniques provide also a chamber like arrangement, however, there is no filter between the cells and the test substance. Quantitative results are gained by the multiwell type of this probe using 4-8-12-channel pipettes. Accuracy of the pipette and increased number of the parallel running samples is the great advantage of this test.
Counting of cells: positive responder cells are count from the lower chamber (long incubation time) or from the filter (short incubation time). For detection of cells general staining techniques (e.g. trypan blue) or special probes (e.g. mt-dehydrogenase detection with MTT assay) are used. Labelled (e.g. fluorochromes) cells are also used, in some assays cells get labelled during transmigration the filter. | 1 | Applied and Interdisciplinary Chemistry |
Phorbol is a natural, plant-derived organic compound. It is a member of the tigliane family of diterpenes. Phorbol was first isolated in 1934 as the hydrolysis product of croton oil, which is derived from the seeds of the purging croton, Croton tiglium. The structure of phorbol was determined in 1967.
Various esters of phorbol have important biological properties, the most notable of which is the capacity to act as tumor promoters through activation of protein kinase C. They mimic diacylglycerols, glycerol derivatives in which two hydroxyl groups have reacted with fatty acids to form esters. The most common and potent phorbol ester is 12-O-tetradecanoylphorbol-13-acetate (TPA), also called phorbol-12-myristate-13-acetate (PMA), which is used as a biomedical research tool in contexts such as models of carcinogenesis. | 0 | Theoretical and Fundamental Chemistry |
One of the most common erroneous explanations of aerodynamic lift asserts that the air must traverse the upper and lower surfaces of a wing in the same amount of time, implying that since the upper surface presents a longer path the air must be moving over the top of the wing faster than over the bottom. Bernoulli's principle is then cited to conclude that the pressure on top of the wing must be lower than on the bottom.
However, there is no physical principle that requires the air to traverse the upper and lower surfaces in the same amount of time. In fact, theory predicts and experiments confirm that the air traverses the top surface in a shorter time than it traverses the bottom surface, and this explanation based on equal transit time is false. While this explanation is false, it is not the Bernoulli principle that is false, because this principle is well established; Bernoulli's equation is used correctly in common mathematical treatments of aerodynamic lift. | 1 | Applied and Interdisciplinary Chemistry |
Local exhaust ventilation (LEV) systems rely on air pulled with a suction force through piping systems from the point of dust formation to a waste disposal unit. They consist of four elements: dust hoods at the point of dust formation, ventilation ducts, an air cleaning device (waste separator or dust collector) and an air moving device (a fan, otherwise known as an impeller). The air, containing dust and chips from the woodworking operation, is sucked by an impeller. The impeller is usually built into, or placed close to, the waste disposal unit, or dust collector.
Guidelines of performance for woodworking LEV systems exist, and these tie into occupational air quality regulations that exist in many countries. The LEV guidelines often referred to are those set by the ACIAH. | 1 | Applied and Interdisciplinary Chemistry |
In some cases of natural phenols, they are present in vegetative foliage to discourage herbivory, such as in the case of Western poison oak. | 0 | Theoretical and Fundamental Chemistry |
A shape resonance is a metastable state in which an electron is trapped due to the shape of a potential barrier.
Altunata describes a state as being a shape resonance if, "the internal state of the system remains unchanged upon disintegration of the quasi-bound level."
A more general discussion of resonances and their taxonomies in molecular system can be found in the review article by Schulz,; for the discovery of the Fano resonance line-shape and for the Majorana pioneering work in this field by Antonio Bianconi; and for
a mathematical review by Combes et al. | 0 | Theoretical and Fundamental Chemistry |
As a consequence, the structure of any brush can be derived from the brush density profile . Indeed, the free end distribution is simply a convolution of the density profile with the free end distribution of a dry brush:
Correspondingly, the brush elastic free energy is given by:
This method has been used to derive wetting properties of polymer melts on polymer brushes of the same species and to understand fine interpenetration asymmetries between copolymer lamellae that may yield very unusual non-centrosymmetric lamellar structures. | 0 | Theoretical and Fundamental Chemistry |
According to the IUPAC definition, in RRC(OH)OR R and R may or may not be a hydrogen. In a hemiketal, neither R-group can be a hydrogen. Hemiketals are regarded as hemiacetals where none of the R-groups are H, and are therefore a subclass of the hemiacetals. The Greek prefix hèmi means half, refers to the fact that a single alcohol has been added to the carbonyl group, in contrast to acetals or ketals, which are formed when a second alkoxy group has been added to the structure.
Cyclic hemiacetals and hemiketals are sometimes called lactols. They often form readily, especially when they are 5- and 6-membered rings. In this case an intramolecular OH group reacts with the carbonyl group. Glucose and many other aldoses exist as cyclic hemiacetals whereas fructose and similar ketoses exist as cyclic hemiketals. | 0 | Theoretical and Fundamental Chemistry |
Glycomimetic is a term used to refer to molecules that have structures similar to carbohydrates, but with some variation. This will normally result in modified biological properties. | 1 | Applied and Interdisciplinary Chemistry |
Coordination isomerism is a form of structural isomerism in which the composition of the coordination complex ion varies. In a coordination isomer the total ratio of ligand to metal remains the same, but the ligands attached to a specific metal ion change. Examples of a complete series of coordination isomers require at least two metal ions and sometimes more.
For example, a solution containing ([Co(NH)] and [Cr(CN)]) is a coordination isomer with a solution containing [Cr(NH)] and [Co(CN)]. | 0 | Theoretical and Fundamental Chemistry |
Modulation of neurotransmitter release by G-protein-coupled receptors (GPCRs) is a prominent presynaptic mechanism for regulation of synaptic transmission. The activation of GPCRs located at the presynaptic terminal, can decrease the probability of neurotransmitter release. This presynaptic depression involves activation of Gi/o-type G-proteins that mediate different inhibitory mechanisms, including inhibition of voltage-gated calcium channels, activation of potassium channels, and direct inhibition of the vesicle fusion process. Endocannabinoids, synthesized in and released from postsynaptic neuronal elements, and their cognate receptors, including the (GPCR) CB1 receptor, located at the presynaptic terminal, are involved in this modulation by a retrograde signaling process, in which these compounds are synthesized in and released from postsynaptic neuronal elements, and travel back to the presynaptic terminal to act on the CB1 receptor for short-term or long-term synaptic depression, that cause a short or long lasting decrease in neurotransmitter release. | 1 | Applied and Interdisciplinary Chemistry |
Tartaric acid has been known to winemakers for centuries. However, the chemical process for extraction was developed in 1769 by the Swedish chemist Carl Wilhelm Scheele.
Tartaric acid played an important role in the discovery of chemical chirality. This property of tartaric acid was first observed in 1832 by Jean Baptiste Biot, who observed its ability to rotate polarized light. Louis Pasteur continued this research in 1847 by investigating the shapes of sodium ammonium tartrate crystals, which he found to be chiral. By manually sorting the differently shaped crystals, Pasteur was the first to produce a pure sample of levotartaric acid. | 0 | Theoretical and Fundamental Chemistry |
Clay minerals are common weathering products (including weathering of feldspar) and low-temperature hydrothermal alteration products. Clay minerals are very common in soils, in fine-grained sedimentary rocks such as shale, mudstone, and siltstone and in fine-grained metamorphic slate and phyllite.
Given the requirement of water, clay minerals are relatively rare in the Solar System, though they occur extensively on Earth where water has interacted with other minerals and organic matter. Clay minerals have been detected at several locations on Mars, including Echus Chasma, Mawrth Vallis, the Memnonia quadrangle and the Elysium quadrangle. Spectrography has confirmed their presence on celestial bodies including the dwarf planet Ceres, asteroid 101955 Bennu, and comet Tempel 1, as well as Jupiter's moon Europa. | 0 | Theoretical and Fundamental Chemistry |
The carbonyl groups of reducing sugars react with the amino groups of amino acids in the Maillard reaction, a complex series of reactions that occurs when cooking food. Maillard reaction products (MRPs) are diverse; some are beneficial to human health, while others are toxic. However, the overall effect of the Maillard reaction is to decrease the nutritional value of food. One example of a toxic product of the Maillard reaction is acrylamide, a neurotoxin and possible carcinogen that is formed from free asparagine and reducing sugars when cooking starchy foods at high temperatures (above 120 °C). However, evidence from epidemiological studies suggest that dietary acrylamide is unlikely to raise the risk of people developing cancer. | 0 | Theoretical and Fundamental Chemistry |
Potassium tert-butoxide (or potassium t-butoxide) is a chemical compound with the formula [(CH)COK] (abbr. KOtBu). This colourless solid is a strong base (pKa of conjugate acid around 17), which is useful in organic synthesis. The compound is often depicted as a salt, and it often behaves as such, but its ionization depends on the solvent. | 0 | Theoretical and Fundamental Chemistry |
Salimuzzaman Siddiqui, ( ; 19 October 1897 – 14 April 1994) was a Pakistani organic chemist specialising in natural products, and a professor of chemistry at the University of Karachi.
Siddiqui studied philosophy at Aligarh Muslim University and later studied chemistry at Frankfurt University, where he received his PhD in 1927. On return to British India, he worked at the Tibbia College Delhi and the Indian Council for Scientific and Industrial Research. He later moved to Pakistan and worked in the Pakistan Council of Scientific and Industrial Research. He went on to establish the Pakistan National Science Council and was appointed its first chairman in 1961. In the same year he became a Fellow of the Royal Society. He later co-founded the Pakistan Academy of Sciences, and after retirement from the government, he founded the Hussain Ebrahim Jamal Research Institute of Chemistry.
Siddiqui is credited with pioneering the isolation of unique chemical compounds from the Neem (Azadirachta indica), Rauvolfia, and various other flora. As the founder director of H.E.J. Research Institute of Chemistry, he revolutionised research of the pharmacology of various domestic plants found in South Asia to extract novel chemical substances of medicinal importance. During his career, Siddiqui published more than 300 research papers and obtained 40 patents mainly from the field of natural product chemistry. In addition to his scientific talents, Siddiqui was also an avid painter, poet, and a great connoisseur of Western music. His paintings were exhibited in the United States, Germany, India, and Pakistan. | 0 | Theoretical and Fundamental Chemistry |
Lampe-Önnerud considered careers in opera singing and medicine and was offered a scholarship for an 8-year program for a medical doctorate degree but turned it down her senior year of high school. After high school, Lampe-Önnerud accepted a Fulbright scholarship to attend Elmira College in New York. At Elmira college she studied English literature, business, and the sciences while working in a chemistry laboratory as a lab assistant.
With encouragement from her father to pursue a career in a STEM field and her growing interest in the sciences, Lampe-Önnerud returned to Sweden and obtained a BSc in Chemistry and a PhD in inorganic chemistry from Uppsala University in Sweden. In her masters program at Uppsala, Lampe-Önnerud studied copper deposition on semiconductor wafers, and for her PhD she focused on analyzing cathode materials for lithium-polymer batteries while working with a Denmark battery producer, Danionics, who later patented some of the materials Lampe- Önnerud studied.
Lampe-Önnerud then held a postdoctoral appointment at MIT in Cambridge, MA working for Quantum Energy Technologies. This was sponsored by the American Chemical Society. | 0 | Theoretical and Fundamental Chemistry |
Cupellation is a refining process in metallurgy in which ores or alloyed metals are treated under very high temperatures and subjected to controlled operations to separate noble metals, like gold and silver, from base metals, like lead, copper, zinc, arsenic, antimony, or bismuth, present in the ore. The process is based on the principle that precious metals typically oxidise or react chemically at much higher temperatures than base metals. When they are heated at high temperatures, the precious metals remain apart, and the others react, forming slags or other compounds.
Since the Early Bronze Age, the process was used to obtain silver from smelted lead ores. By the Middle Ages and the Renaissance, cupellation was one of the most common processes for refining precious metals. By then, fire assays were used for assaying minerals: testing fresh metals such as lead and recycled metals to determine their purity for jewellery and coin making. Cupellation is still in use today. | 1 | Applied and Interdisciplinary Chemistry |
Cargo scanning or non-intrusive inspection (NII) refers to non-destructive methods of inspecting and identifying goods in transportation systems. It is often used for scanning of intermodal freight shipping containers. In the US it is spearheaded by the Department of Homeland Security and its Container Security Initiative (CSI) trying to achieve one hundred percent cargo scanning by 2012 as required by the US Congress and recommended by the 9/11 Commission. In the US the main purpose of scanning is to detect special nuclear materials (SNMs), with the added bonus of detecting other types of suspicious cargo. In other countries the emphasis is on manifest verification, tariff collection and the identification of contraband. In February 2009, approximately 80% of US incoming containers were scanned. To bring that number to 100% researchers are evaluating numerous technologies, described in the following sections. | 0 | Theoretical and Fundamental Chemistry |
Coordination via the oxygen atom is favoured by hard, highly electropositive centres. This is due to the fact that oxygen is a more electronegative atom and thus prefers to bind via more ionic interactions. Examples of this type of coordination were presented in the work of Arnold et al. from 2015. The group found that actinide complexes of PCO involving uranium and thorium both coordinated through the oxygen. This is the result of the contracted nature of the actinide orbitals which makes the metal centres more core-like thus favouring ionic interactions. | 0 | Theoretical and Fundamental Chemistry |
Mass spectrometry provides information about the structure and composition of the complexes. Spectra for metal polycarbonyls are often easily interpretable, because the dominant fragmentation process is the loss of carbonyl ligands (m/z = 28).
: → + CO
Electron ionization is the most common technique for characterizing the neutral metal carbonyls. Neutral metal carbonyls can be converted to charged species by derivatization, which enables the use of electrospray ionization (ESI), instrumentation for which is often widely available. For example, treatment of a metal carbonyl with alkoxide generates an anionic metallaformate that is amenable to analysis by ESI-MS:
:LM(CO) + RO → [LM−C(=O)OR]
Some metal carbonyls react with azide to give isocyanato complexes with release of nitrogen. By adjusting the cone voltage or temperature, the degree of fragmentation can be controlled. The molar mass of the parent complex can be determined, as well as information about structural rearrangements involving loss of carbonyl ligands under ESI-MS conditions.
Mass spectrometry combined with infrared photodissociation spectroscopy can provide vibrational informations for ionic carbonyl complexes in gas phase. | 0 | Theoretical and Fundamental Chemistry |
Functionally, AR NTD plays the primary role in regulating target gene transcription activation and mediating various receptor-protein and intra-receptor N-terminal and C-terminal interactions. Therefore, modulation of NTD function is considered an efficient strategy to target AR action. Among various functional domains in different nuclear receptors, NTD is the least conserved and so could maybe become the best target site for NTD antagonists to achieve AR specificity. However the structural features of the NTD are undetermined due to a high degree of flexibility in its conformation. Both biochemical and circular dichroism spectroscopy analysis suggest that AR NTD is highly disordered under native conditions, making it a difficult target for drug discovery.
In 2008 there were reports of a chlorinated peptide, sintokamide A, isolated from marine sponges that effectively inhibits AR N-terminal domain-activated reporter gene transcription, see figure 8. The evidence presented was not sufficient to support the conclusion that sintokamide A directly inhibits the function of AR NTD, and the mechanism of action needs further investigation. | 1 | Applied and Interdisciplinary Chemistry |
Humans are affected by the HAB species by ingesting improperly harvested shellfish, breathing in aerosolized brevetoxins (i.e. PbTx or Ptychodiscus toxins) and in some cases skin contact. The brevetoxins bind to voltage-gated sodium channels, important structures of cell membranes. Binding results in persistent activation of nerve cells, which interferes with neural transmission leading to health problems. These toxins are created within the unicellular organism, or as a metabolic product. The two major types of brevetoxin compounds have similar but distinct backbone structures. PbTx-2 is the primary intracellular brevetoxin produced by K. brevis blooms. However, over time, the PbTx-2 brevetoxin can be converted to PbTx-3 through metabolic changes. Researchers found that PbTx-2 has been the primary intracellular brevetoxin that converts over time into PbTx-3.
In the U.S., the seafood consumed by humans is tested regularly for toxins by the USDA to ensure safe consumption. Such testing is common in other nations. However, improper harvesting of shellfish can cause paralytic shellfish poisoning and neurotoxic shellfish poisoning in humans. Some symptoms include drowsiness, diarrhea, nausea, loss of motor control, tingling, numbing or aching of extremities, incoherence, and respiratory paralysis. Reports of skin irritation after swimming in the ocean during a HAB are common.
When the HAB cells rupture, they release extracellular brevetoxins into the environment. Some of those stay in the ocean, while other particles get aerosolized. During onshore winds, brevetoxins can become aerosolized by bubble-mediated transport, causing respiratory irritation, bronchoconstriction, coughing, and wheezing, among other symptoms.
It is recommended to avoid contact with wind-blown aerosolized toxin. Some individuals report a decrease in respiratory function after only 1 hour of exposure to a K. brevis red-tide beach and these symptoms may last for days. People with severe or persistent respiratory conditions (such as chronic lung disease or asthma) may experience stronger adverse reactions.
The National Oceanic and Atmospheric Administration's National Ocean Service provides a public conditions report identifying possible respiratory irritation impacts in areas affected by HABs. | 0 | Theoretical and Fundamental Chemistry |
Brownrigg was a businessman as well as a doctor and scientist. He went into partnership with Anthony Bacon from Whitehaven in 1765 to develop the iron industry in Wales which led to the expansion of Merthyr Tydfil, particularly the Cyfarthfa Ironworks. He also inherited a share of John Speddings ropery and invested in the Keswick Turnpike Trust.
With his retirement to Ormathwaite, he became interested in improving the local agriculture, made a study of minerals, and encouraged Thomas West to write A Guide to the Lakes, the first guide book to the Lake District. He had several society positions including magistrate, Patent searcher at Port Carlisle and Receiver General of Government Taxes for Cumberland and Westmorland.
Brownrigg died in 1800 and was buried at Crosthwaite church where his coffin was carried by three baronets and other local gentry. His friend and biographer Joshua Dixon felt that his importance and abilities had been overlooked due to his modesty and reluctance to leave his home county of Cumberland in later life. | 1 | Applied and Interdisciplinary Chemistry |
AMGs have a large impact on biogeochemical cycles in multiple environments through nutrient degradation, mineralization, transportation, assimilation, and transformation. By enhancing the metabolic capabilities of their hosts, bacteriophages contribute to the recycling of organic matter, influencing the availability of nutrients for other organisms in the ecosystem. Lytic viruses in particular have been shown to increase ammonium oxidation, nitric oxide reduction, nitrification, and denitrification to balance nutrient levels in nitrogen polluted environments. Nutrient-enriched wetlands contain AMGs related to sulfur transport and metabolism. AMG modification of host processes is another means other than the viral shunt by which viruses can directly impact biogeochemical cycles. | 1 | Applied and Interdisciplinary Chemistry |
The first real collections of crystal models were produced by Romé de lIsle. He actually offered sets of small (ca 3 cm) models made of "terra cotta" in order to stimulate the sales of the expensive four-volume set of his book "Cristallographie'" (1783). The models were manufactured by his co-workers Arnould Carangeot, Lhermina and Swebach-Desfontaines, who produced numerous large sets (up to 448 models in each set). In order to exactly transfer interplanar angles from natural crystals to the terra cotta models, Carangeot invented and designed a prototype of a contact goniometer. This instrument, that proved to be an invaluable tool in geometric crystallography, enabled the measurement of interplanar angles with a precision of about half a degree.
Teylers Museum in Haarlem has a complete set of these terracotta models that were bought in Paris (in 1785) by Martin van Marum, the first director of the museum. After over 200 years, this collection is still complete and in perfect condition at Teylers Museum. | 0 | Theoretical and Fundamental Chemistry |
Because most HERVs have no function, are selectively neutral, and are very abundant in primate genomes, they easily serve as phylogenetic markers for linkage analysis. They can be exploited by comparing the integration site polymorphisms or the evolving, proviral, nucleotide sequences of orthologs. To estimate when integration occurred, researchers used distances from each phylogenetic tree to find the rate of molecular evolution at each particular locus. It is also useful that ERVs are rich in many species genomes (i.e. plants, insects, mollusks, fish, rodents, domestic pets, and livestock) because its application can be used to answer a variety of phylogenetic questions. | 1 | Applied and Interdisciplinary Chemistry |
Photoactive catalysts have been introduced over the last decade, such as and ZnO nano rodes. Most suffer from the fact that they can only perform under UV irradiation due to their band structure. Other photocatalysts, including a graphene-ZnO nanocompound counter this problem. | 0 | Theoretical and Fundamental Chemistry |
The Peregrine soliton is a solution of the one-dimensional nonlinear Schrödinger equation that can be written in normalized units as follows :
with the spatial coordinate and the temporal coordinate. being the envelope of a surface wave in deep water. The dispersion is anomalous and the nonlinearity is self-focusing (note that similar results could be obtained for a normally dispersive medium combined with a defocusing nonlinearity).
The Peregrine analytical expression is:
so that the temporal and spatial maxima are obtained for and . | 1 | Applied and Interdisciplinary Chemistry |
The parallel configuration or long optical path-length arrangement only provides information about the spectral changes that occur in the solution adjacent to the working electrode surface, improving the sensitivity to soluble compounds because the length of the optical pathway can be as longer as the length of the electrode.
The light beam travels parallel to the working electrode surface, sampling the first micrometers of the solution adjacent to the working electrode surface, and collecting the information on the spectrometer.
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Usually, aligning light beams has been a difficult task. However, simple alternatives have been developed to perform measurements in parallel configuration. There are several advantages in this configuration respect to the normal one: better sensitivity, lower detection limits; optically transparent electrodes are not required; and the spectral changes are related only to the diffusion layer. | 0 | Theoretical and Fundamental Chemistry |
NETA is used as a hormonal contraceptive in combination with estrogen, in the treatment of gynecological disorders such as abnormal uterine bleeding, and as a component of menopausal hormone therapy for the treatment of menopausal symptoms. | 1 | Applied and Interdisciplinary Chemistry |
Calcareous sinter is a freshwater calcium carbonate deposit, also known as calc-sinter. Deposits are characterised by low porosity and well-developed lamination, often forming crusts or sedimentary rock layers. Calcareous sinter should not be confused with siliceous sinter, which the term sinter more frequently refers to. It has been suggested that the term "sinter" should be restricted to siliceous spring deposits and be dropped for calcareous deposits entirely. | 0 | Theoretical and Fundamental Chemistry |
Catalytic hydrogenation yields sulfolane, a solvent used in the petrochemical industry for the extraction of aromatics from hydrocarbon streams. The hydrogenation of 3-sulfolene over Raney nickel at approx. 20 bar and 60 °C gives sulfolane in yields of up to 65% only because of the poisoning of the catalyst by sulfur compounds. | 0 | Theoretical and Fundamental Chemistry |
Cities that installed their sewage collection systems before the 1930s typically used single piping systems to transport both urban runoff and sewage. This type of collection system is referred to as a combined sewer system (CSS). The cities rationale when combined sewers were built was that it would be cheaper to build just a single system. In these systems a sudden large rainfall that exceeds sewage treatment capacity is allowed to overflow directly from storm drains into receiving waters via structures called combined sewer overflows'.
Storm drains are typically installed at shallower depths than combined sewers. This is because combined sewers were designed to accept sewage flows from buildings with basements, in addition to receiving surface runoff from streets.
About 860 communities in the US have combined sewer systems, serving about 40 million people. New York City, Washington, D.C., Seattle and other cities with combined systems have this problem due to a large influx of storm water after every heavy rain event. Some cities have dealt with this by adding large storage tanks or ponds to hold the water until it can be treated. Chicago has a system of tunnels, collectively called the Deep Tunnel, underneath the city for storing its stormwater. Many areas require detention tanks or roof detention systems that temporarily hold runoff in heavy rains and restrict outlet flow to the public sewer. This lessens the risk of overwhelming the public sewer in heavy rain. An overflow outlet may also connect higher on the outlet side of the detention tank. This overflow prevents the detention tank from completely filling. By restricting the flow of water in this way and temporarily holding the water in a detention vault or tank or by rooftop detention, public sewers are less likely to overflow. | 1 | Applied and Interdisciplinary Chemistry |
Complex fluids are mixtures that have a coexistence between two phases: solid–liquid (suspensions or solutions of macromolecules such as polymers), solid–gas (granular), liquid–gas (foams) or liquid–liquid (emulsions). They exhibit unusual mechanical responses to applied stress or strain due to the geometrical constraints that the phase coexistence imposes. The mechanical response includes transitions between solid-like and fluid-like behavior as well as fluctuations. Their mechanical properties can be attributed to characteristics such as high disorder, caging, and clustering on multiple length scales. | 1 | Applied and Interdisciplinary Chemistry |
Enzyme activity is a measure of the quantity of active enzyme present and is thus dependent on various physical conditions, which should be specified.
It is calculated using the following formula:
where
: = Enzyme activity
: = Moles of substrate converted per unit time
: = Rate of the reaction
: = Reaction volume
The SI unit is the katal, 1 katal = 1 mol s (mole per second), but this is an excessively large unit. A more practical and commonly used value is enzyme unit (U) = 1 μmol min (micromole per minute). 1 U corresponds to 16.67 nanokatals.
Enzyme activity as given in katal generally refers to that of the assumed natural target substrate of the enzyme. Enzyme activity can also be given as that of certain standardized substrates, such as gelatin, then measured in gelatin digesting units (GDU), or milk proteins, then measured in milk clotting units (MCU). The units GDU and MCU are based on how fast one gram of the enzyme will digest gelatin or milk proteins, respectively. 1 GDU approximately equals 1.5 MCU.
An increased amount of substrate will increase the rate of reaction with enzymes, however once past a certain point, the rate of reaction will level out because the amount of active sites available has stayed constant. | 1 | Applied and Interdisciplinary Chemistry |
Benzoyl peroxide and hydrogen peroxide are used as bleaching and "maturing" agents for treating flour to make its grain release gluten more easily; the alternative is letting the flour slowly oxidize by air, which is too slow for the industrialized era. Benzoyl peroxide is an effective topical medication for treating most forms of acne. | 0 | Theoretical and Fundamental Chemistry |
The ASTM D5511-12 and ASTM D5526-12 are testing methods that comply with international standards such as the ISO DIS 15985 for the biodegradability of plastic. | 0 | Theoretical and Fundamental Chemistry |
G-protein coupled receptors' usage and chemogenetics are nowadays the targets for many of the pharmaceutical companies to cure and alleviate symptoms of diseases that involve all tissues of the body. More specifically, DREADDs have been used to explore treatment options for various neurodegenerative and psychological conditions such as Parkinson’s disease, depression, anxiety, and addiction. These aforementioned conditions involve processes that occur within and outside of the nervous system involving neurotransmitters such as gamma-aminobutyric acid and glutamate. Chemogenetics has therefore been used in pharmacology to adjust the levels of such neurotransmitters in specific neuron while minimizing the side effects of treatment. To treat and relieve the symptoms of any disease using the DREADDs, these receptors are delivered to the area of interest via viral transduction.
Recently some studies have considered using a new method called retro DREADDs. This method allows specific neuronal pathways to be studied under cellular resolution. Unlike classic DREADDs, this method is usually used in wild type animals, and these receptors are given to the targeted cells via injection of two viral vectors. | 1 | Applied and Interdisciplinary Chemistry |
Methods for the synthesis of aromatic, organofluorine, heterocyclic and heteroatomic compounds. Study of properties and formation of organic, hybrid and polymer materials. Study of pharmacological properties and mechanisms of action of biologically active agents of natural and synthetic origin etc. | 0 | Theoretical and Fundamental Chemistry |
In chemistry, vinylidenes are compounds with the functional group C=CH. An example is 1,1-dichloroethene (CCl=CH) commonly called vinylidene chloride. It and vinylidene fluoride are precursors to commercially useful polymers. | 0 | Theoretical and Fundamental Chemistry |
FSL constructs have a wide range of uses and they have been used to modify the following:
* Cells – blood cells, culture lines, embryos, spermatozoa
* Viruses – influenza, measles, varicella
* Organisms – parasites, microbes, zebrafish
* Liposomes – also micelles, lipid particles
* Surfaces/fibres – hydrophobic or hydrophilic membranes/fibres, paper, nitrocellulose, cotton, silk, glass, Teflon, silica, magnetic beads (microspheres) etc.
* Solutions – saline, plasma/serum, culture media | 1 | Applied and Interdisciplinary Chemistry |
The techniques and manufacturing processes have changed over the years from those described in the first papers, journal articles and patents that were published. There are a number of techniques available depending on what type of species is required. An ion may be formed which can be an anion thus forming an anionic PUD or a cation may be formed forming a cationic PUD. Also, it is possible to synthesize a non-ionic PUD. This involves using materials that will produce an ethylene oxide backbone, or similar, or a water-soluble chain pendant from the main polymer backbone.
Anionic PUDs are by far the most common available commercially. To produce these, initially a polyurethane prepolymer is manufactured in the usual way but instead of just using isocyanate and polyol, a modifier is included in the polymer backbone chain or pendant from the main backbone. This modifier is/was mainly dimethylol propionic acid (DMPA). This molecule contains two hydroxy groups and a carboxylic acid group. The OH groups react with the isocyanate groups to produce an NCO terminated prepolymer but with a pendant COOH group. This is now dispersed under shear in water with a suitable neutralizing agent such as triethylamine. This reacts with the carboxylic acid forming a salt which is water soluble. Usually, a diamine chain extender is then added to produce a polyurethane dispersed in water with no free NCO groups but with polyurethane and polyurea segments. Dytek A is commonly used as the chain extender. Various papers and patents show that an amine chain extender with more than two functionalities such as a triamine may be used too. Chain extender studies have been carried out.
There is also a push to have a synthesis strategy that is non-isocyanate based. When blocked isocyanates are used there is no isocyanate (NCO) functionality and hence the water reaction producing carbon dioxide so dispersion is easier. Modifiers other than DMPA have been researched.
It is also possible to introduce hydrophilicity into the polymeric molecule by using a modified chain extender rather than doing so in the polymer backbone or a pendant chain. Lower viscosity materials are often the result, as well as higher solids. A variation on this technique is to incorporate sulfonate groups. PUD/polyacrylate blends can be prepared this way also utilizing internal emulsifiers.
Cationic PUD also introduce hydrophilic components when synthesized. This includes phosphonium entities. Techniques have and are being researched to improve the performance and water resistance properties by various techniques. This includes introducing star-branched polydimethylsiloxane.
Research has been done and published that shows it is not the dispersion speed, mechanical agitation or high shear mixing that has the biggest effect on properties, but rather the chemical makeup. However, particle size distribution can be controlled by this to some extent. | 0 | Theoretical and Fundamental Chemistry |
Sargeson was born at Armidale, New South Wales, Australia. He was educated at the University of Sydney and received his Ph.D. supervised by Francis Patrick Dwyer also at Sydney in 1956. | 0 | Theoretical and Fundamental Chemistry |
Hope was elected a Fellow of the Royal Society of Edinburgh in 1788 and served as its vice president from 1822 to 1833.
In 1791 following the death of his uncle, Alexander Stevenson, Hope succeeded him in his uncle's role as Professor of Medicine at Glasgow University.
In 1795 Hope was selected by Joseph Black as his assistant (1795–1799) and eventual successor to the professorship of medicine and chemistry (1799–1843) at the University of Edinburgh. Hope’s goal was to more fully combine the practice of medicine with his chemical instruction.
In 1796 Hope was elected a member of the Harveian Society of Edinburgh and served as President in 1800 and 1816.
In 1800 Hope won the annual Edinburgh Arrow archery competition.
In 1804 he became a member of the Highland Society.
In 1805 he was elected a member of the Aesculapian Club.
In May 1810 he was elected a Fellow of the Royal Society of London.
From 1815 to 1819 he served as President of the Royal College of Physicians of Edinburgh.
Between 1824–40 Hope worked with scientists based in Poissy, France. With the town's major, Jean-François Senincourt, he tried to establish a university in the town. Within a few years their aims began to be realised as medical students crowded his lectures.
In 1828 he gave £800 to found a chemistry prize at the University of Edinburgh.
In the 1830s he is listed as living at 31 Moray Place, a large townhouse in the Moray Estate on the western edge of Edinburgh's New Town.
In 1843 he resigned the professorship. He died at his home, 31 Moray Place in Edinburgh's West End in 1844.
He is buried in Greyfriars Kirkyard in central Edinburgh. The grave lies against the western wall of the original churchyard, towards the north-west corner. | 1 | Applied and Interdisciplinary Chemistry |
A thiophosphonate group is a functional group related to phosphonate by substitution of an oxygen atom for a sulphur. They are a reactive component of many pesticides and nerve agents. Substituted thiophosphonates can have 2 main structural isomers bonding though either O or S groups to give thione and thiol forms respectively. This is a property they share with related functional groups such as thiocarboxylic acids and organothiophosphates. | 0 | Theoretical and Fundamental Chemistry |
Cation–pi interactions involve the positive charge of a cation interacting with the electrons in a π-system of a molecule. This interaction is surprisingly strong (as strong or stronger than H-bonding in some contexts), and has many potential applications in chemical sensors. For example, the sodium ion can easily sit atop the π cloud of a benzene molecule, with C symmetry (See figure 4).
Anion–π interactions are very similar to cation–π interactions, but reversed. In this case, an anion sits atop an electron-poor π-system, usually established by the placement of electron-withdrawing substituents on the conjugated molecule | 0 | Theoretical and Fundamental Chemistry |
Researchers have achieved controlled growth of diverse foods in the dark . It may become a way to increase energy efficiency of food production and reduce its environmental impacts. However, it is unclear if food production mechanisms based on the experimental process are viable and can be scaled. | 0 | Theoretical and Fundamental Chemistry |
The premier example of a complex with an unsupported metal–metal bond is dimanganese decacarbonyl, Mn(CO). Many metal clusters contain several unsupported M–M bonds. Some examples are M(CO) (M = Ru, Os) and Ir(CO).
A subclass of unsupported metal–metal bonded arrays are linear chain compounds. In such cases the M–M bonding is weak as signaled by longer M–M bonds and the tendency of such compounds to dissociate in solution. | 0 | Theoretical and Fundamental Chemistry |
Hartinger studied chemistry at the University of Vienna, earning his MSc in 1999 and his PhD in 2001 under Bernhard Keppler. He was an Erwin Schrödinger Fellow with Paul Dyson at the École Polytechnique Fédérale de Lausanne from 2006 to 2008 and obtained his habilitation at the University of Vienna in 2009. In 2011, Hartinger was appointed the position of associate professor at Waipapa Taumata Rau, where he currently serves and in 2015 was promoted to professor.
Hartinger's research interests are in bioinorganic chemistry, medicinal chemistry, and bioanalytical chemistry, where he uses an interdisciplinary approach in drug discovery. He is specially interested in the development of metal-centred anticancer agents, particularly ruthenium anticancer drugs, and using analytical methods to characterise their behaviour in the presence of biomolecules.
Hartinger has now published over 169 publications and has an h-index of 69.
In 2022 Hartinger was elected a Fellow of the Royal Society Te Apārangi. The society said his "innovative approaches have established new directions in metallodrug research, and his developed methodologies continue to have far-reaching impact in the community. His findings challenge paradigms about the reactivity of metal compounds towards biomolecules and thereby inform the design of novel biomaterials". | 0 | Theoretical and Fundamental Chemistry |
The problem of close-packing of spheres was first mathematically analyzed by Thomas Harriot around 1587, after a question on piling cannonballs on ships was posed to him by Sir Walter Raleigh on their expedition to America.
Cannonballs were usually piled in a rectangular or triangular wooden frame, forming a three-sided or four-sided pyramid. Both arrangements produce a face-centered cubic lattice – with different orientation to the ground. Hexagonal close-packing would result in a six-sided pyramid with a hexagonal base.
The cannonball problem asks which flat square arrangements of cannonballs can be stacked into a square pyramid. Édouard Lucas formulated the problem as the Diophantine equation or and conjectured that the only solutions are and . Here is the number of layers in the pyramidal stacking arrangement and is the number of cannonballs along an edge in the flat square arrangement. | 0 | Theoretical and Fundamental Chemistry |
*[https://web.archive.org/web/20110516054351/http://www.aerocomfittings.com/AEROCOM%20Aerospace%20Fluid%20Connectors.pdf PDF illustrating assorted adapters] | 1 | Applied and Interdisciplinary Chemistry |
Austenite is only stable above in bulk metal form. However, fcc transition metals can be grown on a face-centered cubic (fcc) or diamond cubic. The epitaxial growth of austenite on the diamond (100) face is feasible because of the close lattice match and the symmetry of the diamond (100) face is fcc. More than a monolayer of γ-iron can be grown because the critical thickness for the strained multilayer is greater than a monolayer. The determined critical thickness is in close agreement with theoretical prediction. | 1 | Applied and Interdisciplinary Chemistry |
Microorganisms can be used as indicators of aquatic or terrestrial ecosystem health. Found in large quantities, microorganisms are easier to sample than other organisms. Some microorganisms will produce new proteins, called stress proteins, when exposed to contaminants such as cadmium and benzene. These stress proteins can be used as an early warning system to detect changes in levels of pollution. | 1 | Applied and Interdisciplinary Chemistry |
The presence of fecal coliform in aquatic environments may indicate that the water has been contaminated with the fecal material of humans or other animals. Fecal coliform bacteria can enter rivers through direct discharge of waste from mammals and birds, from agricultural and storm runoff, and from human sewage. However, their presence may also be the result of plant material, and pulp or paper mill effluent. | 0 | Theoretical and Fundamental Chemistry |
Stormwater management BMPs are control measures taken to mitigate changes to both quantity and quality of urban runoff caused through changes to land use. Generally BMPs focus on water quality problems caused by increased impervious surfaces from land development. BMPs are designed to reduce stormwater volume, peak flows, and/or nonpoint source pollution through evapotranspiration, infiltration, detention, and filtration or biological and chemical actions. BMPs also can improve receiving-water quality by extending the duration of outflows in comparison to inflow duration (known as hydrograph extension), which dilutes the stormwater discharged into a larger volume of upstream flow.Although structural BMPs can be effective for reducing stormwater loads to receiving waters, studies indicate that they cannot improve in-stream water quality where receiving-water quality is poor.
Stormwater BMPs can be classified as "structural" (i.e., devices installed or constructed on a site such as silt fences, rock filter dams, fiber rolls (also called erosion control logs or excelsior wattles), sediment traps and numerous other proprietary products) or "non-structural" (procedures, such as modified landscaping practices, soil disturbing activity scheduling, or street sweeping). There are a variety of BMPs available; selection typically depends on site characteristics and pollutant removal objectives. EPA has published a series of stormwater BMP fact sheets for use by local governments, builders and property owners.
Stormwater management BMPs can be also categorized into four basic types:
# Storage practices: ponds; recovery; green infrastructure design.
# Vegetative practices: buffers; channels; green roofs; wetlands; functional art; stormwater wetland park design; wetland park engineering & design.
# Filtration/Infiltration practices: filtering; infiltration; rain gardens; porous pavement; civic infrastructure and design; functional stormwater design.
# Water sensitive development: better site design (revisions of local land development rules); open space site design; low impact development. | 1 | Applied and Interdisciplinary Chemistry |
When the boundary layer separates, its remnants form a shear layer and the presence of a separated flow region between the shear layer and surface modifies the outside potential flow and pressure field. In the case of airfoils, the pressure field modification results in an increase in pressure drag, and if severe enough will also result in stall and loss of lift, all of which are undesirable. For internal flows, flow separation produces an increase in the flow losses, and stall-type phenomena such as compressor surge, both undesirable phenomena.
Another effect of boundary layer separation is regular shedding vortices, known as a Kármán vortex street. Vortices shed from the bluff downstream surface of a structure at a frequency depending on the speed of the flow. Vortex shedding produces an alternating force which can lead to vibrations in the structure. If the shedding frequency coincides with a resonance frequency of the structure, it can cause structural failure. These vibrations could be established and reflected at different frequencies based on their origin in adjacent solid or fluid bodies and could either damp or amplify the resonance. | 1 | Applied and Interdisciplinary Chemistry |
So-called "butane honey oil" was available briefly in the 1970s. This product was made in Kabul, Afghanistan, and smuggled into the United States by The Brotherhood of Eternal Love. Production is thought to have ceased when the facility was destroyed in an explosion.
Traditional ice water-separated hashish production utilizes water and filter bags to separate plant material from resin, though this method still leaves much residual plant matter and is therefore poorly suited for full vaporization. Gold described the use of alcohol and activated charcoal in honey oil production by 1989, and Michael Starks further detailed procedures and various solvents by 1990.
Large cannabis vaporizers gained popularity in the twentieth century for their ability to vaporize the cannabinoids in cannabis and extracts without burning plant material, using temperature controlled vaporization.
Colorado and Washington began licensing hash oil extraction operations in 2014.
Small portable vape pens saw a dramatic increase in popularity in 2017. | 0 | Theoretical and Fundamental Chemistry |
Amyloid-beta precursor protein (APP) is an integral membrane protein expressed in many tissues and concentrated in the synapses of neurons. It functions as a cell surface receptor and has been implicated as a regulator of synapse formation, neural plasticity, antimicrobial activity, and iron export. It is coded for by the gene APP and regulated by substrate presentation. APP is best known as the precursor molecule whose proteolysis generates amyloid beta (Aβ), a polypeptide containing 37 to 49 amino acid residues, whose amyloid fibrillar form is the primary component of amyloid plaques found in the brains of Alzheimer's disease patients. | 1 | Applied and Interdisciplinary Chemistry |
The synthesis of pyrethrin I involves the esterification of (+)-trans-chrysanthemic acid with (S)-(Z)-pyrethrolone. One synthetic method for each of these is shown in the images below. Sobti and Dev of the Malti-Chem Research Centre in Nadesari, vadodara, India published this method for chrysanthemic acid in 1974. The starting material for the synthesis uses commercially available (+)-3α, 4α-epoxycarane (1). A lactone is eventually formed and the ring is opened by the use of a Grignard reagent to give (+)-trans-chrysanthemic acid. The preparation of (S)-pyrethrolone is essentially a 2 step synthesis. The starting material (S)-4-hydroxy-3-methyl-2-(2-propynyl)-2-cyclopenten-1-one (7) is also commercially available as the alcohol moiety of ETOC. Tetrakis(triphenylphosphine)palladium(0), copper(I) iodide, triethylamine, and vinyl bromide are added to (7) to add two more carbons and form (8). The final step is the addition of an activated zinc compound to reduce the triple carbon bond to form the cis product, (S)-pyrethrolone (9). Although no journal articles specify the combining of the alcohol and acid moieties of pyrethrin I, they could be combined through an esterification process to form the wanted product. | 0 | Theoretical and Fundamental Chemistry |
Hydrotropes are in use industrially and commercially in cleaning and personal care product formulations to allow more concentrated formulations of surfactants. About 29,000 metric tons are produced (i.e., manufactured and imported) annually in the US. Annual production (plus importation) in Europe and Australia is approximately 17,000 and 1,100 metric tons, respectively.
Common products containing hydrotropes include laundry detergents, surface cleaners, dishwashing detergents, liquid soaps, shampoos and conditioners. They are coupling agents, used at concentrations from 0.1 to 15% to stabilize the formula, modify viscosity and cloud-point, reduce phase separation in low temperatures, and limit foaming.
Adenosine triphosphate (ATP) has been shown to prevent aggregation of proteins at normal physiologic concentrations and to be approximately an order of magnitude more effective than sodium xylene sulfonate in a classic hydrotrope assay. The hydrotrope activity of ATP was shown to be independent of its activity as an "energy currency" in cells. Additionally, ATP function as biological hydrotope has been shown proteome-wide under near native conditions. In a recent study, however, the hydrotropic capabilities of ATP have been questioned as it has severe salting-out characteristics due to its triphosphate moiety. | 0 | Theoretical and Fundamental Chemistry |
A macromolecule is a very large molecule important to biological processes, such as a protein or nucleic acid. It is composed of thousands of covalently bonded atoms. Many macromolecules are polymers of smaller molecules called monomers. The most common macromolecules in biochemistry are biopolymers (nucleic acids, proteins, and carbohydrates) and large non-polymeric molecules such as lipids, nanogels and macrocycles. Synthetic fibers and experimental materials such as carbon nanotubes are also examples of macromolecules. | 0 | Theoretical and Fundamental Chemistry |
In the majority of energy applications, energy is required in multiple forms. These energy forms typically include some combination of: heating, ventilation, and air conditioning, mechanical energy and electric power. Often, these additional forms of energy are produced by a heat engine, running on a source of high-temperature heat. A heat engine can never have perfect efficiency, according to the second law of thermodynamics, therefore a heat engine will always produce a surplus of low-temperature heat. This is commonly referred to as waste heat or "secondary heat", or "low-grade heat". This heat is useful for the majority of heating applications, however, it is sometimes not practical to transport heat energy over long distances, unlike electricity or fuel energy. The largest proportions of total waste heat are from power stations and vehicle engines. The largest single sources are power stations and industrial plants such as oil refineries and steelmaking plants. | 0 | Theoretical and Fundamental Chemistry |
Harriet Brooks observed a radioactive recoil in 1904, but interpreted it wrongly. Hahn and Meitner succeeded in demonstrating the radioactive recoil incident to alpha particle emission and interpreted it correctly. Hahn pursued a report by Stefan Meyer and Egon Schweidler of a decay product of actinium with a half-life of about 11.8 days. Hahn determined that it was actinium X (radium-223). Moreover, he discovered that at the moment when a radioactinium (thorium-227) atom emits an alpha particle, it does so with great force, and the actinium X experiences a recoil. This is enough to free it from chemical bonds, and it has a positive charge, and can be collected at a negative electrode. Hahn was thinking only of actinium, but on reading his paper, Meitner told him that he had found a new way of detecting radioactive substances. They set up some tests, and soon found actinium C (thallium-207) and thorium C (thallium-208). The physicist Walther Gerlach described radioactive recoil as "a profoundly significant discovery in physics with far-reaching consequences".
In 1910, Hahn was appointed professor by the Prussian Minister of Culture and Education, August von Trott zu Solz. Two years later, Hahn became head of the Radioactivity Department of the newly founded Kaiser Wilhelm Institute for Chemistry in Berlin-Dahlem (in what is today the Hahn-Meitner-Building of the Free University of Berlin). This came with an annual salary of 5,000 marks. In addition, he received 66,000 marks in 1914 (of which he gave 10 per cent to Meitner) from Knöfler for the mesothorium process. The new institute was inaugurated on 23 October 1912 in a ceremony presided over by Kaiser Wilhelm II. The Kaiser was shown glowing radioactive substances in a dark room.
The move to new accommodation was fortuitous, as the wood shop had become thoroughly contaminated by radioactive liquids that had been spilt, and radioactive gases that had vented and then decayed and settled as radioactive dust, making sensitive measurements impossible. To ensure that their clean new laboratories stayed that way, Hahn and Meitner instituted strict procedures. Chemical and physical measurements were conducted in different rooms, people handling radioactive substances had to follow protocols that included not shaking hands, and rolls of toilet paper were hung next to every telephone and door handle. Strongly radioactive substances were stored in the old wood shop, and later in a purpose-built radium house on the institute grounds. | 0 | Theoretical and Fundamental Chemistry |
*[http://pid.nci.nih.gov/PID/2006/061114/full/pid.2006.001.shtml An Introduction to the NCI-Nature Pathway Interaction Database]
*[http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0000425 Identification of Key Processes Underlying Cancer Phenotypes Using Biologic Pathway Analysis] | 1 | Applied and Interdisciplinary Chemistry |
In the original Nègre air engine, one piston compresses air from the atmosphere to mix with the stored compressed air (which will cool drastically as it expands). This mixture drives the second piston, providing the actual engine power. MDIs engine works with constant torque, and the only way to change the torque to the wheels is to use a pulley transmission of constant variation, losing some efficiency. When vehicle is stopped, MDIs engine had to be on and working, losing energy. In 2001–2004 MDI switched to a design similar to that described in Regusci's patents (see below), which date back to 1990.
It has been reported in 2008 that Indian car manufacturer Tata was looking at an MDI compressed-air engine as an option on its low priced Nano automobiles. Tata announced in 2009 that the compressed-air car was proving difficult to develop due to its low range and problems with low engine temperatures. | 1 | Applied and Interdisciplinary Chemistry |
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