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A 2014 paper described how Mapp and its collaborators, including investigators at Public Health Agency of Canada, Kentucky BioProcessing, and the National Institute of Allergy and Infectious Diseases, first chimerized the three antibodies comprising ZMAb, then tested combinations of MB-003 and the chimeric ZMAb antibodies in guinea pigs and then primates to determine the best combination, which turned out to be c13C6 from MB-003 and two chimeric mAbs from ZMAb, c2G4 and c4G7. This is ZMapp.
In an experiment also published in the 2014 paper, 21 rhesus macaque primates were infected with the Kikwit Congolese variant of EBOV. Three primates in the control arm were given a non-functional antibody, and the 18 in the treatment arm were divided into three groups of six. All primates in the treatment arm received three doses of ZMapp, spaced 3 days apart. The first treatment group received its first dose on 3rd day after being infected; the second group on the 4th day after being infected, and the third group, on the 5th day after being infected. All three primates in the control group died; all 18 primates in the treatment arm survived. Mapp then went on to show that ZMapp inhibits replication of a Guinean strain of EBOV in cell cultures.
Mapp remains involved in the production of the drug through its contracts with Kentucky BioProcessing, a subsidiary of Reynolds American. To produce the drug, genes coding for the chimeric mAbs were inserted into viral vectors, and tobacco plants are infected with the viral vector encoding for the antibodies, using Agrobacterium cultures. Subsequently, antibodies are extracted and purified from the plants. Once the genes encoding the chimeric mAbs are in hand, the entire tobacco production cycle is believed to take a few months. The development of these production methods was funded by the U.S. Defense Advanced Research Projects Agency as part of its bio-defense efforts following the 9/11 terrorist attacks. | 1 | Applied and Interdisciplinary Chemistry |
; General
* Aitchison, Leslie. 1960. A History of Metals. London: Macdonald & Evans Ltd.
* Bayley, Justine; Butcher, Sarnia. 2004. Roman Brooches in Britain: A Technological and Typological Study based on the Richborough Collection. London: The Society of Antiquaries of London.
* Craddock, Paul T. 1995. Early Metal Mining and Production. Edinburgh: Edinburgh University Press.
* Craddock, Paul T. 1999. Paradigms of Metallurgical Innovation in Prehistoric Europe in Hauptmann, A., Ernst, P., Rehren, T., Yalcin, U. (eds). The Beginnings of Metallurgy: Proceedings of the International Conference “The Beginnings of Metallurgy”, Bochum 1995. Hamburg
* Davies, O. Roman Mines in Europe 1935., Oxford University Press
* Hughes, M. J. 1980 The Analysis of Roman Tin and Pewter Ingots in Ody, W. A. (ed) Aspects of Early Metallurgy. Occasional Paper No 17. British Museum Occasional Papers.
* Shepard, Robert. 1993. Ancient Mining. London: Elsevier Applied Science.
* Sim, David. 1998. Beyond the Bloom: Bloom Refining and Iron Artifact Production in the Roman World. Ridge, Isabel (ed). BAR International Series 725. Oxford: Archaeopress.
* Tylecote, R.F. 1962. Metallurgy in Archaeology: A Prehistory of Metallurgy in the British Isles. London: Edward Arnold (Publishers) Ltd.
* Zwicker, U., Greiner, H., Hofmann, K-H., Reithinger, M. 1985. Smelting, Refining and Alloying of Copper and Copper Alloys in Crucible Furnaces During Prehistoric up to Roman Times in Craddock, P.T., Hughes, M.J. (eds) Furnaces and Smelting Technology in Antiquity. Occasional Paper No 48. London: British Museum Occasional Papers.
* J. S., Hodgkinson. 2008. "The Wealden Iron Industry." (The History Press, Stroud).
* Cleere, Henry. 1981. The Iron Industry of Roman Britain. Wealden Iron Research Group.
; Output
* Callataÿ, François de (2005): "The Graeco-Roman Economy in the Super Long-Run: Lead, Copper, and Shipwrecks", Journal of Roman Archaeology, Vol. 18, pp. 361–372
* Cech, Brigitte (2010): Technik in der Antike, Wissenschaftliche Buchgesellschaft, Darmstadt,
* Cleere, H. & Crossley, D. (1995): The Iron industry of the Weald. 2nd edition, Merton Priory Press, Cardiff, : republishing the 1st edition (Leicester University Press 1985) with a supplement.
* Cleere, Henry. 1981. The Iron Industry of Roman Britain. Wealden Iron Research Group. p. 74-75
* Craddock, Paul T. (2008): "Mining and Metallurgy", in: Oleson, John Peter (ed.): The Oxford Handbook of Engineering and Technology in the Classical World, Oxford University Press, , pp. 93–120
* Healy, John F. (1978): Mining and Metallurgy in the Greek and Roman World, Thames and Hudson, London,
* Hong, Sungmin; Candelone, Jean-Pierre; Patterson, Clair C.; Boutron, Claude F. (1994): "Greenland Ice Evidence of Hemispheric Lead Pollution Two Millennia Ago by Greek and Roman Civilizations", Science, Vol. 265, No. 5180, pp. 1841–1843
* Hong, Sungmin; Candelone, Jean-Pierre; Patterson, Clair C.; Boutron, Claude F. (1996): "History of Ancient Copper Smelting Pollution During Roman and Medieval Times Recorded in Greenland Ice", Science, Vol. 272, No. 5259, pp. 246–249
* Patterson, Clair C. (1972): "Silver Stocks and Losses in Ancient and Medieval Times", The Economic History Review, Vol. 25, No. 2, pp. 205–235
* Lewis, P. R. and G. D. B. Jones, The Dolaucothi gold mines, I: the surface evidence, The Antiquaries Journal, 49, no. 2 (1969): 244-72.
* Lewis, P. R. and G. D. B. Jones, Roman gold-mining in north-west Spain, Journal of Roman Studies 60 (1970): 169-85.
* Lewis, P. R., The Ogofau Roman gold mines at Dolaucothi, The National Trust Year Book 1976-77 (1977).
* Settle, Dorothy M.; Patterson, Clair C. (1980): "Lead in Albacore: Guide to Lead Pollution in Americans", Science, Vol. 207, No. 4436, pp. 1167–1176
* Sim, David; Ridge, Isabel (2002): Iron for the Eagles. The Iron Industry of Roman Britain, Tempus, Stroud, Gloucestershire,
* Smith, A. H. V. (1997): "Provenance of Coals from Roman Sites in England and Wales", Britannia, Vol. 28, pp. 297–324
* Wilson, Andrew (2002): "Machines, Power and the Ancient Economy", The Journal of Roman Studies, Vol. 92, pp. 1–32 | 1 | Applied and Interdisciplinary Chemistry |
Since laser diffraction analysis is not the sole way of measuring particles it has been compared to the sieve-pipette method, which is a traditional technique for grain size analysis. When compared, results showed that laser diffraction analysis made fast calculations that were easy to recreate after a one-time analysis, did not need large sample sizes, and produced large amounts of data. Results can easily be manipulated because the data is on a digital surface. Both the sieve-pipette method and laser diffraction analysis are able to analyze minuscule objects, but laser diffraction analysis resulted in having better precision than its counterpart method of particle measurement. | 0 | Theoretical and Fundamental Chemistry |
Chemical decomposition, or chemical breakdown, is the process or effect of simplifying a single chemical entity (normal molecule, reaction intermediate, etc.) into two or more fragments. Chemical decomposition is usually regarded and defined as the exact opposite of chemical synthesis. In short, the chemical reaction in which two or more products are formed from a single reactant is called a decomposition reaction.
The details of a decomposition process are not always well defined. Nevertheless, some activation energy is generally needed to break the involved bonds and as such, higher temperatures generally accelerates decomposition. The net reaction can be an endothermic process, or in the case of spontaneous decompositions, an exothermic process.
The stability of a chemical compound is eventually limited when exposed to extreme environmental conditions such as heat, radiation, humidity, or the acidity of a solvent. Because of this chemical decomposition is often an undesired chemical reaction. However chemical decomposition can be desired, such as in various waste treatment processes.
For example, this method is employed for several analytical techniques, notably mass spectrometry, traditional gravimetric analysis, and thermogravimetric analysis. Additionally decomposition reactions are used today for a number of other reasons in the production of a wide variety of products. One of these is the explosive breakdown reaction of sodium azide [(NaN)] into nitrogen gas (N) and sodium (Na). It is this process which powers the life-saving airbags present in virtually all of today's automobiles.
Decomposition reactions can be generally classed into three categories; thermal, electrolytic, and photolytic decomposition reactions. | 0 | Theoretical and Fundamental Chemistry |
Hard metal cations, as classified by HSAB theory, tend to form N-bonded complexes (isothiocyanates), whereas class B or soft metal cations tend to form S-bonded thiocyanate complexes. For the isothiocyanates, the M-N-C angle is usually close to 180°. For the thiocyanates, the M-S-C angle is usually close to 100°. | 0 | Theoretical and Fundamental Chemistry |
The mechanism of phenoxymethylpenicillin is identical to that of all other penicillins. It exerts a bactericidal action against penicillin-sensitive microorganisms during the stage of active multiplication. It acts by inhibiting the biosynthesis of cell-wall peptidoglycan. | 0 | Theoretical and Fundamental Chemistry |
Examples of selectable markers include:
*Beta-lactamase which confers ampicillin resistance to bacterial hosts.
*Neo gene from Tn5, which confers resistance to kanamycin in bacteria and geneticin in eukaryotic cells
*Mutant FabI gene (mFabI) from E. coli genome, which confers triclosan resistance to the host.
*URA3, an orotidine-5 phosphate decarboxylase from yeast is a positive and negative selectable marker. It is required for uracil biosynthesis and can complement ura3 mutants that are auxotrophic for uracil (positive selection). The enzyme URA3 also converts 5-fluoroorotic acid (5FOA) into the toxic compound 5-fluorouracil, so any cells carrying the URA3' gene will be killed in the presence of 5FOA (negative selection). | 1 | Applied and Interdisciplinary Chemistry |
Human cells require iron in order to obtain energy as ATP from a multi-step process known as cellular respiration, more specifically from oxidative phosphorylation at the mitochondrial cristae. Iron is present in the iron–sulfur cluster and heme groups of the electron transport chain proteins that generate a proton gradient that allows ATP synthase to synthesize ATP (chemiosmosis).
Heme groups are part of hemoglobin, a protein found in red blood cells that serves to transport oxygen from the lungs to other tissues. Heme groups are also present in myoglobin to store and diffuse oxygen in muscle cells. | 1 | Applied and Interdisciplinary Chemistry |
The BioWatch program is funded and supervised by the Department of Homeland Security (DHS). The BioWatch program has three main components: sampling, analysis, and response. Each of these components is handled by three different agencies. The Environmental Protection Agency (EPA) handles the sampling component: the sensors that collect airborne particles. The Centers for Disease Control and Prevention (CDC) coordinates the analysis and laboratory testing of the samples. Local authorities are responsible for the public health response to positive findings. The Federal Bureau of Investigation (FBI) is designated as the lead agency for the law enforcement response if a bioterrorism event is detected. (Shea and Lister, 2003) | 0 | Theoretical and Fundamental Chemistry |
PetroSA, another South African company, operates a refinery with a 36,000 barrels a day plant that completed semi-commercial demonstration in 2011, paving the way to begin commercial preparation. The technology can be used to convert natural gas, biomass or coal into synthetic fuels. | 0 | Theoretical and Fundamental Chemistry |
Pockels used her sliding trough to evaluate the effect of small amounts of impurities on water. These impurities were typically household substances such as oils and soaps. With her apparatus, she measured the surface tension as the amount of force required to remove the disk from the surface of the water. Pockels found that small amounts of impurities could have a large effect on the surface tension of water, compared to pure water.
In particular, Pockels studied soapy water. Soaps are examples of surfactants, which are molecules which have a hydrophilic portion of the molecule, while the remainder is hydrophobic. These are insoluble in the water and tend to reside on the surface of the water. When placing small amounts of the surfactants in her sliding trough, Pockels found that the effect on surface tension was small. However, once the slider on the surface of the trough passed a certain point, the effect on surface tension was large. When she plotted the surface tension on one axis of a graph compared to the position of the slider on her sliding trough, the graphical representation was a compression isotherm.
Using her knowledge of chemistry, Pockels realized that the point of the compression isotherm at which the surface tension changes abruptly is the point at which a film of surfactant molecules that is continuous and one molecule thick is formed. This is a monolayer of the surfactant. Pockels further found that this threshold point is the same for a variety of surfactant soaps. Since she knew how much surfactant was in her sliding trough as well as the area covered by the monolayer film, she could calculate the area on the surface of the water occupied by single molecule. She calculated this area to be 20 square angstroms (20 Å). Later, as her investigations became known in the scientific community, this area determined by the sliding trough became known as the Pockels Point. | 0 | Theoretical and Fundamental Chemistry |
Heat conduction in a Newtonian context is modelled by the Fourier equation, namely a parabolic partial differential equation of the kind:
where θ is temperature, t is time, α = k/(ρ c) is thermal diffusivity, k is thermal conductivity, ρ is density, and c is specific heat capacity. The Laplace operator, , is defined in Cartesian coordinates as
This Fourier equation can be derived by substituting Fourier’s linear approximation of the heat flux vector, q, as a function of temperature gradient,
into the first law of thermodynamics
where the del operator, ∇, is defined in 3D as
It can be shown that this definition of the heat flux vector also satisfies the second law of thermodynamics,
where s is specific entropy and σ is entropy production. This mathematical model is inconsistent with special relativity: the Green function associated to the heat equation (also known as heat kernel) has support that extends outside the light-cone, leading to faster-than-light propagation of information. For example, consider a pulse of heat at the origin; then according to Fourier equation, it is felt (i.e. temperature changes) at any distant point, instantaneously. The speed of propagation of heat is faster than the speed of light in vacuum, which is inadmissible within the framework of relativity. | 0 | Theoretical and Fundamental Chemistry |
Materials may be used to control and manipulate light via a variety of mechanisms to produce useful effects involving color. For instance, a change of orientation of molecules to produce a visual effect as in liquid crystal displays. Other materials operate by producing a physical effect, by interference and diffraction as in lustre pigments and optically variable pigments, colloidal photonic crystals and in holography. Increasingly inspiration is coming from Nature, in the form of bioinspired structural colors. Molecular materials are also used to increase the intensity of light by modifying its movement through the materials by electrical means, so increasing its intensity as in organic lasers, or in modifying the transmission of light through materials, as in opto-electronics, or by purely by all optical means as in optical limiters. | 0 | Theoretical and Fundamental Chemistry |
Willard's research interests focused on analytical chemistry and quantitative analysis of inorganic substances. With student G. Frederick Smith, he was particularly productive in studying perchloric acid and periodic acid salts. In addition, he is credited with important work in determining precise atomic weights of chemical elements such as lithium, silver, and antimony, and with development of metal alloy techniques. | 0 | Theoretical and Fundamental Chemistry |
The process takes advantage of aerobic micro-organisms that can digest organic matter in sewage, and clump together by flocculation entrapping fine particulate matter as they do so. It thereby produces a liquid that is relatively free from suspended solids and organic material, and flocculated particles that will readily settle out and can be removed.
The general arrangement of an activated sludge process for removing carbonaceous pollution includes the following items:
* Aeration tank where air (or oxygen) is injected in the mixed liquor.
* Settling tank (usually referred to as "final clarifier" or "secondary settling tank") to allow the biological flocs (the sludge blanket) to settle, thus separating the biological sludge from the clear treated water.
Treatment of nitrogenous or phosphorous matter comprises the addition of an anoxic compartment inside the aeration tank in order to perform the nitrification-denitrification process more efficiently. First, ammonia is oxidized to nitrite, which is then converted into nitrate in aerobic conditions (aeration compartment). Facultative bacteria then reduce the nitrate to nitrogen gas in anoxic conditions (anoxic compartment). Moreover, the organisms used for the phosphorus uptake (Polyphosphate Accumulating Organisms) are more efficient under anoxic conditons. These microorganisms accumulate large amounts of phosphates in their cells and are settled in the secondary clarifier or removed as waste of activated sludge (WAS). The yield of PAOs (Polyphosphate Accumulating Organisms) is reduced between 70-80% under aerobic conditions. Even though the phosphorus can be removed upstream of the aeration tank by chemical precipitation (adding metal ions such as: calcium, aluminum or iron), the biological phophorus removal is more economic due to the saving of chemicals. | 1 | Applied and Interdisciplinary Chemistry |
Prigogine's theorem is a theorem of non-equilibrium thermodynamics, originally formulated by Ilya Prigogine.
The formulation of Prigogine's theorem is:
According to this theorem, the stationary state of a linear non-equilibrium system (under conditions that prevent the achievement of an equilibrium state) corresponds to the minimum entropy production. If there are no such obstacles, then the production of entropy reaches its absolute minimum - zero. A linear system means the fulfillment of linear phenomenological relationships between thermodynamic flows and driving forces. The coefficients of proportionality in the relationships between flows and driving forces are called phenomenological coefficients.
The theorem was proved by Prigogine in 1947 from the Onsager relations. Prigogines theorem is valid if the kinetic coefficients in the Onsager relations are constant (do not depend on driving forces and flows); for real systems, it is valid only approximately, so the minimum entropy production for a stationary state is not such a general principle as the maximum entropy for an equilibrium state. It has been experimentally established that Onsagers linear relations are valid in a fairly wide range of parameters for heat conduction and diffusion processes (for example, Fouriers law, Ficks law). For chemical reactions, the linear assumption is valid in a narrow region near the state of chemical equilibrium. The principle is also violated for systems odd with respect to time reversal. | 0 | Theoretical and Fundamental Chemistry |
Rutherford received significant recognition in his home country of New Zealand. In 1901, he earned a DSc from the University of New Zealand. In 1916, he was awarded the Hector Memorial Medal. In 1925, Rutherford called for the New Zealand Government to support education and research, which led to the formation of the Department of Scientific and Industrial Research (DSIR) in the following year. In 1933, Rutherford was one of the two inaugural recipients of the T. K. Sidey Medal, which was established by the Royal Society of New Zealand as an award for outstanding scientific research.
Additionally, Rutherford received a number of awards from the British Crown. He was knighted in 1914. He was appointed to the Order of Merit in the 1925 New Year Honours. Between 1925 and 1930, he served as President of the Royal Society, and later as president of the Academic Assistance Council which helped almost 1,000 university refugees from Germany. In 1931 was raised to the peerage as Baron Rutherford of Nelson, decorating his coat of arms with a kiwi and a Māori warrior. The title became extinct upon his unexpected death in 1937. | 1 | Applied and Interdisciplinary Chemistry |
The reaction can be under kinetic or thermodynamic control depending on the exact reaction conditions, catalyst, and substrate. Common rings, 5- through 7-membered cycloalkenes, have a high tendency for formation and are often under greater thermodynamic control due to the enthalpic favorability of the cyclic products, as shown by Illuminati and Mandolini on the formation of lactone rings. Smaller rings, between 5 and 8 atoms, are more thermodynamically favored over medium to large rings due to lower ring strain. Ring strain arises from abnormal bond angles resulting in a higher heat of combustion relative to the linear counterpart. If the RCM product contains a strained olefin, polymerization becomes preferable through ring-opening metathesis polymerization of the newly formed olefin. Medium rings in particular have greater ring strain, in part due to greater transannular interactions from opposing sides of the ring, but also the inability to orient the molecule in such a way to prevent penalizing gauche interactions. RCM may be considered to have a kinetic bias if the products cannot reenter the catalytic cycle or interconvert through an equilibrium. A kinetic product distribution could lead to mostly RCM products or may lead to oligomers and polymers, which are most often disfavored. | 0 | Theoretical and Fundamental Chemistry |
Sewage can be treated close to where the sewage is created, which may be called a decentralized system or even an on-site system (on-site sewage facility, septic tanks, etc.). Alternatively, sewage can be collected and transported by a network of pipes and pump stations to a municipal treatment plant. This is called a centralized system (see also sewerage and pipes and infrastructure).
A large number of sewage treatment technologies have been developed, mostly using biological treatment processes (see list of wastewater treatment technologies). Very broadly, they can be grouped into high tech (high cost) versus low tech (low cost) options, although some technologies might fall into either category. Other grouping classifications are intensive or mechanized systems (more compact, and frequently employing high tech options) versus extensive or natural or nature-based systems (usually using natural treatment processes and occupying larger areas) systems. This classification may be sometimes oversimplified, because a treatment plant may involve a combination of processes, and the interpretation of the concepts of high tech and low tech, intensive and extensive, mechanized and natural processes may vary from place to place. | 1 | Applied and Interdisciplinary Chemistry |
Electrode potential appears at the interface between an electrode and electrolyte due to the transfer of charged species across the interface, specific adsorption of ions at the interface, and specific adsorption/orientation of polar molecules, including those of the solvent.
In an electrochemical cell, the cathode and the anode have certain electrode potentials independently and the difference between them is the cell potential:
The electrode potential may be either that at equilibrium at the working electrode ("reversible potential"), or a potential with a non-zero net reaction on the working electrode but zero net current ("corrosion potential", "mixed potential"), or a potential with a non-zero net current on the working electrode (like in galvanic corrosion or voltammetry). Reversible potentials can be sometimes converted to the standard electrode potential for a given electroactive species by extrapolation of the measured values to the standard state.
The value of the electrode potential under non-equilibrium depends on the nature and composition of the contacting phases, and on the kinetics of electrode reactions at the interface (see Butler–Volmer equation).
An operational assumption for determinations of the electrode potentials with the standard hydrogen electrode involves this reference electrode with hydrogen ion in an ideal solution having is "zero potential at all temperatures" equivalently to standard enthalpy of formation of hydrogen ion is also "zero at all temperatures". | 0 | Theoretical and Fundamental Chemistry |
* [http://search.eb.com/eb/article-9110413 "Radioactivity"], Encyclopædia Britannica. 2006. Encyclopædia Britannica Online. December 18, 2006
* Radio-activity by Ernest Rutherford Phd, Encyclopædia Britannica Eleventh Edition | 0 | Theoretical and Fundamental Chemistry |
Ernst Otto Fischer (; 10 November 1918 – 23 July 2007) was a German chemist who won the Nobel Prize for pioneering work in the area of organometallic chemistry. | 0 | Theoretical and Fundamental Chemistry |
Mayers reagent is an alkaloidal precipitating reagent used for the detection of alkaloids in natural products. Mayers reagent is freshly prepared by dissolving a mixture of mercuric chloride (1.36 g) and of potassium iodide (5.00 g) in water (100.0 ml). Most alkaloids are precipitated from neutral or slightly acidic solution by Mayer's reagent (potassiomercuric iodide solution) to give a cream coloured precipitate. This test was invented by the German Chemist, Julius Robert Von Mayer (1814–1878). | 0 | Theoretical and Fundamental Chemistry |
Boyles law was perhaps the first expression of an equation of state. In 1662 Robert Boyle performed a series of experiments employing a J-shaped glass tube, which was sealed on one end. Mercury was added to the tube, trapping a fixed quantity of air in the short, sealed end of the tube. Then the volume of gas was carefully measured as additional mercury was added to the tube. The pressure of the gas could be determined by the difference between the mercury level in the short end of the tube and that in the long, open end. The image of Boyles equipment shows some of the exotic tools used by Boyle during his study of gases.
Through these experiments, Boyle noted that the pressure exerted by a gas held at a constant temperature varies inversely with the volume of the gas. For example, if the volume is halved, the pressure is doubled; and if the volume is doubled, the pressure is halved. Given the inverse relationship between pressure and volume, the product of pressure (P) and volume (V) is a constant (k) for a given mass of confined gas as long as the temperature is constant. Stated as a formula, thus is:
Because the before and after volumes and pressures of the fixed amount of gas, where the before and after temperatures are the same both equal the constant k, they can be related by the equation: | 0 | Theoretical and Fundamental Chemistry |
In polymer chemistry, a random coil is a conformation of polymers where the monomer subunits are oriented randomly while still being bonded to adjacent units. It is not one specific shape, but a statistical distribution of shapes for all the chains in a population of macromolecules. The conformation's name is derived from the idea that, in the absence of specific, stabilizing interactions, a polymer backbone will "sample" all possible conformations randomly. Many unbranched, linear homopolymers — in solution, or above their melting temperatures — assume (approximate) random coils. | 0 | Theoretical and Fundamental Chemistry |
The first approach of bioprinting is called biomimicry. The main goal of this approach is to create fabricated structures that are identical to the natural structure that are found in the tissues and organs in the human body. Biomimicry requires duplication of the shape, framework, and the microenvironment of the organs and tissues. The application of biomimicry in bioprinting involves creating both identical cellular and extracellular parts of organs. For this approach to be successful, the tissues must be replicated on a micro scale. Therefore, it is necessary to understand the microenvironment, the nature of the biological forces in this microenvironment, the precise organization of functional and supporting cell types, solubility factors, and the composition of extracellular matrix. | 1 | Applied and Interdisciplinary Chemistry |
In general, hemoglobin can be saturated with oxygen molecules (oxyhemoglobin), or desaturated with oxygen molecules (deoxyhemoglobin). | 0 | Theoretical and Fundamental Chemistry |
In organometallic chemistry, alpha elimination refers to reactions of this type (other spectator ligands omitted):
:X-M-CHR → M=CHR + HX
Well studied case are found in organotantalum chemistry leading to an alkylidene derivatives. Specifically, tetraalkyl-monochloro-tantalum complex undergoes α-hydrogen elimination, followed by alkylation of the remaining chloride to give a derivative with a Ta=C bond.
Alpha elimination contrasts with β-hydride elimination, whereby an alkyl group bonded to a metal centre is converted into the corresponding metal-bonded hydride and an alkene.
Both α- and β-eliminations proceed via agostic intermediates. | 0 | Theoretical and Fundamental Chemistry |
In the 17th century, copper miners in Saxony, Germany, began to experience irritation caused by a "dark red ore". Since the substance, which would later be called nickel, led to many ailments, they believed it to be protected by "goblins", and called it "Goblin's Copper". Josef Jadassohn described the first case of metal contact dermatitis in 1895, to a mercury-based therapeutic cream, and confirmed the cause by epi-cutaneous patch testing. In the next century nickel began to be mass-produced for jewelry worldwide due to its cheap cost, resistance to corrosion and high supply.
In 1979 a large comprehensive study of healthy US volunteers found that 9% had been unknowingly sensitized to nickel. , that number has tripled. Most importantly, nickel allergy among children is increasing, with an estimated 250,000 children sensitized to nickel.
Published literature shows an exponential increase in reported nickel allergy cases. The North American Contact Dermatitis Group (NACDG) patch tested 5,085 adults, presenting with eczema-like symptoms, showing 19.5% had a positive reaction to nickel. Nickel allergy is also more prevalent in women (17.1%) than men (3%), possibly due to cultural norms related to jewelry and ear piercings and therefore increased exposure to nickel. In order to investigate the current prevalence of nickel, Loma Linda University, Nickel Allergy Alliance, and Dermatitis Academy, are conducting a self-reporting nickel allergy-dermatitis survey. | 1 | Applied and Interdisciplinary Chemistry |
During a hydroelectric plant project, in the southern foothills of the Central Highlands, Samanalawewa, in Sri Lanka, a wind-driven furnace was found in an excavation site. Such furnaces were powered by the monsoon winds and have been dated to 300 BC using radiocarbon-dating techniques. These ancient Lankan furnaces might have produced the best-quality steel for legendary Damascus swords as referred in earlier Syrian records. Field trials using replica furnaces confirmed that this furnace type uses a wind-based air-supply principle that is distinct from either forced or natural draught, and show also that they are capable of producing high-carbon steel.
Wrought iron was used in the construction of monuments such as the iron pillar of Delhi, built in the third century AD during the Gupta Empire. The latter was built using a towering series of disc-shaped iron blooms. Similar to China, high-carbon steel was eventually used in India, although cast iron was not used for architecture until modern times. | 1 | Applied and Interdisciplinary Chemistry |
The 3-D particle tracking velocimetry (PTV) belongs to the class of whole-field velocimetry techniques used in the study of turbulent flows, allowing the determination of instantaneous velocity and vorticity distributions over two or three spatial dimensions. 3-D PTV yields a time series of instantaneous 3-component velocity vectors in the form of fluid element trajectories. At any instant, the data density can easily exceed 10 velocity vectors per cubic centimeter. The method is based on stereoscopic imaging (using 2 to 4 cameras) and synchronous recording of the motion of flow tracers, i.e. small particles suspended in the flow, illuminated by a strobed light source. The 3-D particle coordinates as a function of time are then derived by use of image and photogrammetric analysis of each stereoscopic set of frames. The 3-D particle positions are tracked in the time domain to derive the particle trajectories. The ability to follow (track) a spatially dense set of individual particles for a sufficiently long period of time, and to perform statistical analysis of their properties, permits a Lagrangian description of the turbulent flow process. This is a unique advantage of the 3-D PTV method.
A typical implementation of the 3D-PTV consists of two, three or four digital cameras, installed in an angular configuration and synchronously recording the diffracted or fluorescent light from the flow tracers seeded in the flow. The flow is illuminated by a collimated laser beam, or by another source of light that is often strobed, synchronously with the camera frame rate, to reduce the effective exposure time of the moving optical targets and "freeze" their position on each frame. There is no restriction on the light to be coherent or monochromatic; only its illuminance has to be sufficient for imaging the tracer particles in the observational volume. Particles or tracers could be fluorescent, diffractive, tracked through as many consecutive frames as possible, and on as many cameras as possible to maximize positioning accuracy. In principle, two cameras in a stereoscopic configuration are sufficient in order to determine the three coordinates of a particle in space, but in most practical situations three or four cameras are used to reach a satisfactory 3-D positioning accuracy, as well as increase the trajectory yield when studying fully turbulent flows. | 1 | Applied and Interdisciplinary Chemistry |
The first genes discovered in a mutagenesis screen for mutants unable to produce rhamnolipids were rhlA and rhlB. They are arranged in an operon, adjacent to rhlRI, a master regulator of quorum sensing in Pseudomonas aeruginosa. The proteins encoded by rhlA and rhlB; RhlA and RhlB respectively, are expected to form a complex because of the operonic nature of the genes which encode these two proteins and because both proteins are necessary for production of rhamnolipids. Furthermore, it was supposed that the role of RhlA was to stabilise RhlB in the cell membrane and thus the RhlAB complex was labelled as the enzyme Rhamnosyltransferase 1 and is frequently cited as such although there is no biochemical evidence for this and RhlA has been shown to be monomeric in solution. RhlA was subsequently shown to be involved in the production of the precursor to RHLs, HAAs. RhlB adds a rhamnose group to the HAA precursor to form mono-rhamnolipid. Therefore, the products of the rhlAB operon, RhlA and RhlB, catalyse the formation of HAAs and mono-rhamnolipids respectively.
RhlA is an α, β hydrolase (analysis by Fugue structural prediction programme). This fold is a common structural motif in fatty acid synthetic proteins and RhlA shows homology to transacylases. It has been shown using enzyme assays that the substrate for RhlA is hydroxyacyl-ACP rather than hydroxyacyl-CoA suggesting that it catalyses the formation of HAAs directly from the type II fatty acid synthase pathway (FASII). Furthermore, RhlA preferentially interacts with hydroxyacyl-ACP with an acyl chain length of ten carbon residues. The hydroxyacyl-ACP substrate of RhlA is the product of FabG, a protein which encodes the NADPH-dependent β-keto-acyl-ACP reductase required for fatty acid synthesis. It is a member of the FASII cycle along with FabI and FabA, which synthesise the precursors utilised by FabG.
Another gene necessary for synthesis of di-rhamnolipids, rhlC, has also been identified. RhlC catalyses the addition of the second rhamnose moiety to mono-rhamnolipids forming di-rhamnolipids, hence is often labelled rhamnosyltransferase 2. Like rhlA and rhlB, rhlC is thought to be an ancestral gene controlled by the same quorum sensing system as rhlA and rhlB. The rhamnose moiety for mono- and di-rhamnolipids is derived from AlgC activity and the RmlABCD pathway, encoded on the rmlBCAD operon. AlgC produces sugar precursors directly for alginate and lipopolysaccharide (LPS) as well as rhamnolipids. In rhamnose synthesis, AlgC produces glucose-1-phosphate (G1P) which is converted to dTDP-D-glucose by RmlA followed by conversion to dTDP-6-deoxy-D-4-hexulose and then dTDP-6-deoxy-L-lyxo-4-hexulose by RmlB and RmlC respectively. Finally, dTDP-6-deoxy-L-lyxo-4-hexulose is converted to dTDP-L-rhamnose by RmlD. The rhamnose can then be used in the synthesis of rhamnolipids by RhlB and RhlC.
The complete pathway of biosynthesis of rhamnolipids has not been confirmed. In summary, mono- and di- rhamnolipids are produced by sequential rhamnosyltransferase reactions catalysed by RhlB and RhlC respectively. The substrate for RhlB is the fatty acid moiety of the detergent, produced by RhlA. | 0 | Theoretical and Fundamental Chemistry |
Detention basins are storm water best management practices that provide general flood protection and can also control extreme floods such as a 1 in 100-year storm event. The basins are typically built during the construction of new land development projects including residential subdivisions or shopping centers. The ponds help manage the excess urban runoff generated by newly constructed impervious surfaces such as roads, parking lots and rooftops.
A basin functions by allowing large flows of water to enter but limits the outflow by having a small opening at the lowest point of the structure. The size of this opening is determined by the capacity of underground and downstream culverts and washes to handle the release of the contained water.
Frequently the inflow area is constructed to protect the structure from some types of damage. Offset concrete blocks in the entrance spillways are used to reduce the speed of entering flood water. These structures may also have debris drop vaults to collect large rocks. These vaults are deep holes under the entrance to the structure. The holes are wide enough to allow large rocks and other debris to fall into the holes before they can damage the rest of the structure. These vaults must be emptied after each storm event.
Research has shown that detention basins built with real-time control of the outflow from the basin are significantly more effective at retaining total suspended solids and associated contaminants, such as heavy metals, when compared to basins without control. | 1 | Applied and Interdisciplinary Chemistry |
Cholesterol 7 alpha hydroxylase consists of 491 amino acids, which on folding forms 23 alpha helices and 26 beta sheets. | 1 | Applied and Interdisciplinary Chemistry |
Reflectance difference spectroscopy (RDS) is a spectroscopic technique which measures the difference in reflectance of two beams of light that are shone in normal incident on a surface with different linear polarizations. It is also known as reflectance anisotropy spectroscopy (RAS).
It is calculated as:
and are the reflectance in two different polarizations.
The method was introduced in 1985 for the study optical properties of the cubic semiconductors silicon and germanium. Due to its high surface sensitivity and independence of ultra-high vacuum, its use has been expanded to in situ monitoring of epitaxial growth or the interaction of surfaces with adsorbates. To assign specific features in the signal to their origin in morphology and electronic structure, theoretical modelling by density functional theory is required. | 0 | Theoretical and Fundamental Chemistry |
Systems pharmacology is the application of systems biology principles to the field of pharmacology. It seeks to understand how drugs affect the human body as a single complex biological system.
Instead of considering the effect of a drug to be the result of one specific drug-protein interaction, systems pharmacology considers the effect of a drug to be the outcome of the network of interactions a drug may have. In 1992, an article on systems medicine and pharmacology was published in China. Networks of interaction may include chemical-protein, protein–protein, genetic, signalling and physiological (at cellular, tissue, organ and whole body levels). Systems pharmacology uses bioinformatics and statistics techniques to integrate and interpret these networks.
Systems pharmacology can be applied to drug safety studies as a complement to pharmacoepidemiology. | 1 | Applied and Interdisciplinary Chemistry |
Although CoQ has been used to treat purported muscle-related side effects of statin medications, a 2015 meta-analysis found that CoQ had no effect on statin myopathy. A 2018 meta-analysis concluded that there was preliminary evidence for oral CoQ reducing statin-associated muscle symptoms, including muscle pain, muscle weakness, muscle cramps and muscle tiredness. | 1 | Applied and Interdisciplinary Chemistry |
The decrease in the Racah parameter B indicates that in a complex there is less repulsion between the two electrons in a given doubly occupied metal d-orbital than there is in the respective M gaseous metal ion, which in turn implies that the size of the orbital is larger in the complex. This electron cloud expansion effect may occur for one (or both) of two reasons. One is that the effective positive charge on the metal has decreased. Because the positive charge of the metal is reduced by any negative charge on the ligands, the d-orbitals can expand slightly. The second is the act of overlapping with ligand orbitals and forming covalent bonds increases orbital size, because the resulting molecular orbital is formed from two atomic orbitals.
The reduction of B from its free ion value is normally reported in terms of the nephelauxetic parameter β:
Experimentally, it is observed that size of the nephelauxetic parameter always follows a certain trend with respect to the nature of the ligands present. | 0 | Theoretical and Fundamental Chemistry |
In surface science, an instrument called a contact angle goniometer or tensiometer measures the static contact angle, advancing and receding contact angles, and sometimes surface tension. The first contact angle goniometer was designed by William Zisman of the United States Naval Research Laboratory in Washington, D.C. and manufactured by ramé-hart (now ramé-hart instrument company), New Jersey, USA. The original manual contact angle goniometer used an eyepiece with a microscope. Today's contact angle goniometer uses a camera and software to capture and analyze the drop shape, and is better suited for dynamic and advanced studies. | 0 | Theoretical and Fundamental Chemistry |
The viscosity of a fluid is a measure of its resistance to deformation at a given rate. For liquids, it corresponds to the informal concept of "thickness": for example, syrup has a higher viscosity than water. Viscosity is defined scientifically as a force multiplied by a time divided by an area. Thus its SI units are newton-seconds per square meter, or pascal-seconds.
Viscosity quantifies the internal frictional force between adjacent layers of fluid that are in relative motion. For instance, when a viscous fluid is forced through a tube, it flows more quickly near the tubes axis than near its walls. Experiments show that some stress (such as a pressure difference between the two ends of the tube) is needed to sustain the flow. This is because a force is required to overcome the friction between the layers of the fluid which are in relative motion. For a tube with a constant rate of flow, the strength of the compensating force is proportional to the fluids viscosity.
In general, viscosity depends on a fluid's state, such as its temperature, pressure, and rate of deformation. However, the dependence on some of these properties is negligible in certain cases. For example, the viscosity of a Newtonian fluid does not vary significantly with the rate of deformation.
Zero viscosity (no resistance to shear stress) is observed only at very low temperatures in superfluids; otherwise, the second law of thermodynamics requires all fluids to have positive viscosity. A fluid that has zero viscosity (non-viscous) is called ideal or inviscid. | 1 | Applied and Interdisciplinary Chemistry |
Carbocations are formed in two major alkene addition reactions. In an HX addition reaction, the pi bond of an alkene acts as a nucleophile and bonds with the proton of an HX molecule, where the X is a halogen atom. This forms a carbocation intermediate, and the X then bonds to the positive carbon that is available, as in the following two-step reaction.
Similarly, in an addition reaction, the pi bond of an alkene acts as a nucleophile and bonds with the proton of an molecule. This forms a carbocation intermediate (and an atom); the oxygen atom of then bonds with the positive carbon of the intermediate. The oxygen finally deprotonates to form a final alcohol product, as follows. | 0 | Theoretical and Fundamental Chemistry |
An external water spray system (EWSS) is a domestic external fire sprinkler system designed to protect homes from bushfires and wildfires. While external spray systems have long been used in fire protection for buildings and facilities, EWSS refers to domestic bushfire/wildfire systems. | 1 | Applied and Interdisciplinary Chemistry |
A spot assay or spot test can also refer to a specific test in microbiology. This test is often used to check the growth rate of bacterial or yeast cells on different media or to perform serial dilution tests of micro-organisms. Usually a 96-pinner (often called frogger) is used to perform these spot assay.
Another application is high-throughput screening, whichoften uses spot assays to determine the growth of eg. mated cells or to check for protein-protein interactions in a yeast two-hybrid test. This is often done with a robot. | 0 | Theoretical and Fundamental Chemistry |
Steroid 11β-hydroxylase, also known as steroid 11β-monooxygenase, is a steroid hydroxylase found in the zona glomerulosa and zona fasciculata of the adrenal cortex. Named officially the cytochrome P450 11B1, mitochondrial, it is a protein that in humans is encoded by the CYP11B1 gene. The enzyme is involved in the biosynthesis of adrenal corticosteroids by catalyzing the addition of hydroxyl groups during oxidation reactions. | 1 | Applied and Interdisciplinary Chemistry |
Bay mud consists of thick deposits of soft, unconsolidated silty clay, which is saturated with water; these soil layers are situated at the bottom of certain estuaries, which are normally in temperate regions that have experienced cyclical glacial cycles.
Example locations are Cape Cod Bay, Chongming Dongtan Reserve in Shanghai, China, Banc d'Arguinpreserve in Mauritania, The Bristol Channel in the United Kingdom, Mandø Island in the Wadden Sea in Denmark, Florida Bay, San Francisco Bay, Bay of Fundy, Casco Bay, Penobscot Bay, and Morro Bay.
Bay mud manifests low shear strength, high compressibility and low permeability, making it hazardous to build upon in seismically active regions like the San Francisco Bay Area.
Typical bulk density of bay mud is approximately 1.3 grams per cubic centimetre.
Bay muds often have a high organic content, consisting of decayed organisms at lower depths, but may also contain living creatures when they occur at the upper soil layer and become exposed by low tides; then, they are called mudflats, an important ecological zone for shorebirds and many types of marine organisms. Great attention was not given to the incidence of deeper bay muds until the 1960s and 1970s when development encroachment on certain North American bays intensified, requiring geotechnical design of foundations.
Bay mud has its own official geological abbreviation: the designation for Quaternary older bay mud is Qobm and the acronym for Quaternary younger bay mud is Qybm. An alluvial layer is often found overlying the older bay mud.
In relation to shipping channels, it is often necessary to dredge bay bottoms and barge the excavated material to an alternate location. In this case chemical analyses are usually performed on the bay mud to determine whether there are elevated levels of heavy metals, PCBs or other toxic substances known to accumulate in a benthic environment. It is not uncommon to dredge the same channel repeatedly (over a span of ten to thirty years) since further settling sediments are prone to redeposit on an open estuarine valley floor. | 1 | Applied and Interdisciplinary Chemistry |
Another example of a demethylase is protein-glutamate methylesterase, also known as CheB protein (EC 3.1.1.61), which demethylates MCPs (methyl-accepting chemotaxis proteins) through hydrolysis of carboxylic ester bonds. The association of a chemotaxis receptor with an agonist leads to the phosphorylation of CheB. Phosphorylation of CheB protein enhances its catalytic MCP demethylating activity resulting in adaption of the cell to environmental stimuli. MCPs respond to extracellular attractants and repellents in bacteria like E. coli in chemotaxis regulation. CheB is more specifically termed a methylesterase, as it removes methyl groups from methylglutamate residues located on the MCPs through hydrolysis, producing glutamate accompanied by the release of methanol.
CheB is of particular interest to researchers as it may be a therapeutic target for mitigating the spread of bacterial infections. | 1 | Applied and Interdisciplinary Chemistry |
Allison Hubel is an American mechanical engineer and cryobiologist who applies her expertise in heat transfer to study the cryopreservation of biological tissue. She is a professor of mechanical engineering at the University of Minnesota, where she directs the Biopreservation Core Resource and the Technological Leadership Institute, and is president-elect of the Society for Cryobiology. | 1 | Applied and Interdisciplinary Chemistry |
The ideal gas law can also be derived from first principles using the kinetic theory of gases, in which several simplifying assumptions are made, chief among which are that the molecules, or atoms, of the gas are point masses, possessing mass but no significant volume, and undergo only elastic collisions with each other and the sides of the container in which both linear momentum and kinetic energy are conserved.
First we show that the fundamental assumptions of the kinetic theory of gases imply that
Consider a container in the Cartesian coordinate system. For simplicity, we assume that a third of the molecules moves parallel to the -axis, a third moves parallel to the -axis and a third moves parallel to the -axis. Next we temporarily assume that all molecules with the same velocity . We choose an area on a wall of the container, perpendicular to the -axis. When time elapses, all molecules in the volume moving in the positive direction of the -axis will hit the area. There are molecules in a part of volume of the container, but only one sixth (i.e. a half of a third) of them moves in the positive direction of the -axis. Therefore, the number of molecules that will hit the area when the time elapses is .
When a molecule bounces off the wall of the container, it changes its momentum to . Hence the magnitude of change of the momentum of one molecule is . The magnitude of the change of momentum of all molecules that bounce off the area when time elapses is then . From and we get
We supposed that all molecules move with the same velocity , but in fact they move with different velocities, so we replace in the equation by the arithmetic mean of all squares of all velocities of the molecules, i.e. by Therefore
which gives the desired formula.
Using the Maxwell–Boltzmann distribution, the fraction of molecules that have a speed in the range to is , where
and denotes the Boltzmann constant. The root-mean-square speed can be calculated by
Using the integration formula
it follows that
from which we get the ideal gas law: | 0 | Theoretical and Fundamental Chemistry |
Fred Hoyle (1915-2001), a prominent astronomer at the Institute of Astronomy at Cambridge, is most well known for his theory of how chemical elements heavier than helium in our universe are manufactured within stars. However, he is also remembered for his scientifically plausible fiction novels, the first of which “The Black Cloud” was published in 1957. This novel describes the interaction of Earth scientists with an intelligent life form, an immense black cloud of gas that moves directly towards the solar system and temporarily obscures the sun. When the black cloud detects radio signals from earth, it is surprised to discover that intelligent life can also exist on the surface of planets. Although Fred Hoyle characterizes this novel as a “frolic,” he also notes that there is little in the novel that could not conceivably happen. This novel is notable for raising, and providing a scientific rationale for the concept that the existence of “life” may not be constrained by the conditions that are ordinarily considered to be essential based on the singular example of life on earth. | 1 | Applied and Interdisciplinary Chemistry |
In organic chemistry, episulfides are a class of organic compounds that contain a saturated, heterocyclic ring consisting of two carbon atoms and one sulfur atom. It is the sulfur analogue of an epoxide or aziridine. They are also known as thiiranes, olefin sulfides, thioalkylene oxides, and thiacyclopropanes. Episulfides are less common and generally less stable than epoxides. The most common derivative is ethylene sulfide (). | 0 | Theoretical and Fundamental Chemistry |
* The Career Achievement Award is aimed towards a recognition of individuals who have made outstanding contributions to the field of TERM and have carried out most of their career in the TERMIS-EU geographical area.
* The Mid Terms Career Award has been established in 2020 to recognize individuals that are within 10–20 years after obtaining their PhD, with a successful research group and clear evidence of outstanding performance.
* The Robert Brown Early Career Principal Investigator Award recognizes individuals that are within 2–10 years after obtaining their PhD, with clear evidence of a growing profile. | 1 | Applied and Interdisciplinary Chemistry |
Depletion gilding is a method for producing a layer of nearly pure gold on an object made of gold alloy by removing the other metals from its surface. It is sometimes referred to as a "surface enrichment" process. | 1 | Applied and Interdisciplinary Chemistry |
The exact mechanism for the reduction is unknown, although there are two hypothesized pathways. The first pathway is the transferral of electrons from one electron reduced ETF one at a time to the lower potential FAD center. One electron is transferred from the reduced FAD to the iron cluster, resulting in a two electron reduced state with one electron each on the FAD and cluster domains. Then, the bound ubiquinone is reduced to ubiquinol, at least transiently forming the singly reduced semiubiquinone. The second pathway involves the donation of electrons from ETF to the iron cluster, followed by internal transitions between the two electron centers. After equilibration, the rest of the pathway follows as above. | 1 | Applied and Interdisciplinary Chemistry |
Algae has shown selectivity for strontium in studies, where most plants used in bioremediation have not shown selectivity between calcium and strontium, often becoming saturated with calcium, which is greater in quantity and also present in nuclear waste.
Researchers have looked at the bioaccumulation of strontium by Scenedesmus spinosus (algae) in simulated wastewater. The study claims a highly selective biosorption capacity for strontium of S. spinosus, suggesting that it may be appropriate for use of nuclear wastewater.
A study of the pond alga Closterium moniliferum using stable strontium found that varying the ratio of barium to strontium in water improved strontium selectivity. | 0 | Theoretical and Fundamental Chemistry |
Ever since the discovery that monoclonal antibodies could be generated, scientists have targeted the creation of fully human products to reduce the side effects of humanised or chimeric antibodies. Several successful approaches have been proposed: transgenic mice, phage display and single B cell cloning. | 1 | Applied and Interdisciplinary Chemistry |
Carboranes (or carbaboranes) are electron-delocalized (non-classically bonded) clusters composed of boron, carbon and hydrogen atoms. Like many of the related boron hydrides, these clusters are polyhedra or fragments of polyhedra. Carboranes are one class of heteroboranes.
In terms of scope, carboranes can have as few as 5 and as many as 14 atoms in the cage framework. The majority have two cage carbon atoms. The corresponding C-alkyl and B-alkyl analogues are also known in a few cases. | 0 | Theoretical and Fundamental Chemistry |
Lead-zinc deposits are generally accompanied by silver, hosted within the lead sulfide mineral galena or within the zinc sulfide mineral sphalerite.
Lead and zinc deposits are formed by discharge of deep sedimentary brine onto the sea floor (termed sedimentary exhalative or SEDEX), or by replacement of limestone, in skarn deposits, some associated with submarine volcanoes (called volcanogenic massive sulfide ore deposits or VMS), or in the aureole of subvolcanic intrusions of granite. The vast majority of SEDEX lead and zinc deposits are Proterozoic in age, although there are significant Jurassic examples in Canada and Alaska.
The carbonate replacement type deposit is exemplified by the Mississippi valley type (MVT) ore deposits. MVT and similar styles occur by replacement and degradation of carbonate sequences by hydrocarbons, which are thought important for transporting lead. | 0 | Theoretical and Fundamental Chemistry |
The sea hare A californica is a model organism in neurobiology to study among others the molecular mechanisms of long-term memory. To study interactions, important in neurology, in a more native environment a two-hybrid system has been developed in A californica neurons. A GAL4 AD and BD are used in this system. | 1 | Applied and Interdisciplinary Chemistry |
Nanoparticles used as carriers for nucleic acids are mostly iron oxides. These iron oxides can be generated by precipitation from acidic iron-salt solutions upon addition of appropriate bases. The magnetic nanoparticles have an approximate size of 100 nm and are additionally coated with biological polymers to allow loading of nucleic acids. Particles and nucleic acids form complexes by ionic interaction of the negatively charged nucleic acid and the positively charged surface of the magnetic nanoparticle. | 1 | Applied and Interdisciplinary Chemistry |
* Goldman, Steven J., Jackson, Katharine & Bursztynsky, Taras A. Erosion & Sediment Control Handbook McGraw-Hill (1986) | 1 | Applied and Interdisciplinary Chemistry |
ChemSeer project, funded by the National Science Foundation, is a public integrated digital library, database, and search engine for scientific papers in chemistry. It is being developed by a multidisciplinary team of researchers at the Pennsylvania State University. ChemSeer was conceived by Dr. Prasenjit Mitra, Dr. Lee Giles and Dr. Karl Mueller as a way to integrate the chemical scientific literature with experimental, analytical, and simulation data from different types of experimental systems. The goal of the project is to create an intelligent search and database which will provide access to relevant data to a diverse community of users who have a need for chemical information. It is hosted on the World Wide Web at the College of Information Sciences and Technology, The Pennsylvania State University. | 1 | Applied and Interdisciplinary Chemistry |
The sample mass and size distribution requirements are dictated by the kind of mathematical model that will be used to simulate the process plant, and the test work required to provide the appropriate model parameters. Flotation testing usually requires several kg of sample and grinding/hardness testing can required between 2 and 300 kg.
The sample selection procedure is performed to optimize granularity, sample support, and cost. Samples are usually core samples composited over the height of the mining bench. For hardness parameters, the variogram often increases rapidly near the origin and can reach the sill at distances significantly smaller than the typical drill hole collar spacing. For this reason the incremental model precision due to additional test work is often simply a consequence of the central limit theorem, and secondary correlations are sought to increase the precision without incurring additional sampling and testing costs. These secondary correlations can involve multi-variable regression analysis with other, non-metallurgical, ore parameters and/or domaining by rock type, lithology, alteration, mineralogy, or structural domains. | 1 | Applied and Interdisciplinary Chemistry |
The certification of isotopic reference materials is relatively complex. Like most aspects of reporting isotopic compositions it reflects a combination of historical artifacts and modern institutions. As a result, the details surrounding the certification of isotopic reference materials varies by element and chemical compound. As a general guideline, the isotopic composition of primary and original calibration reference materials were used to define the isotopic scales and so have no associated uncertainty. Updated calibration materials are generally certified by IAEA and important reference materials for two-point isotopic scales (SLAP, LSVEC) were reached through interlaboratory comparison. The isotopic composition of additional reference materials are either established through individual analytical facilities or through interlaboratory comparisons but often lack an official IAEA certification. There are certified values for most of the materials listed in Table 1, about half of the materials listed in Tables 2–7, and few of the materials in Table 8. | 0 | Theoretical and Fundamental Chemistry |
Total synthesis is the complete chemical synthesis of a complex molecule, often a natural product, from simple, commercially-available precursors. It usually refers to a process not involving the aid of biological processes, which distinguishes it from semisynthesis. Syntheses may sometimes conclude at a precursor with further known synthetic pathways to a target molecule, in which case it is known as a formal synthesis. Total synthesis target molecules can be natural products, medicinally-important active ingredients, known intermediates, or molecules of theoretical interest. Total synthesis targets can also be organometallic or inorganic, though these are rarely encountered. Total synthesis projects often require a wide diversity of reactions and reagents, and subsequently requires broad chemical knowledge and training to be successful.
Often, the aim is to discover a new route of synthesis for a target molecule for which there already exist known routes. Sometimes, however, no route exists, and chemists wish to find a viable route for the first time. Total synthesis is particularly important for the discovery of new chemical reactions and new chemical reagents, as well as establishing synthetic routes for medicinally important compounds. | 0 | Theoretical and Fundamental Chemistry |
While Lavoisier is commonly known for his contributions to the sciences, he also dedicated a significant portion of his fortune and work toward benefitting the public. Lavoisier was a humanitarian—he cared deeply about the people in his country and often concerned himself with improving the livelihood of the population by agriculture, industry, and the sciences. The first instance of this occurred in 1765, when he submitted an essay on improving urban street lighting to the French Academy of Sciences.
Three years later in 1768, he focused on a new project to design an aqueduct. The goal was to bring water from the river Yvette into Paris so that the citizens could have clean drinking water. But, since the construction never commenced, he instead turned his focus to purifying the water from the Seine. This was the project that interested Lavoisier in the chemistry of water and public sanitation duties.
Additionally, he was interested in air quality and spent some time studying the health risks associated with gunpowder's effect on the air. In 1772, he performed a study on how to reconstruct the Hôtel-Dieu hospital, after it had been damaged by fire, in a way that would allow proper ventilation and clean air throughout.
At the time, the prisons in Paris were known to be largely unlivable and the prisoners' treatment inhumane. Lavoisier took part in investigations in 1780 (and again in 1791) on the hygiene in prisons and had made suggestions to improve living conditions, suggestions which were largely ignored.
Once a part of the Academy, Lavoisier also held his own competitions to push the direction of research towards bettering the public and his own work. | 1 | Applied and Interdisciplinary Chemistry |
In 1943, he defended his Ph.D. thesis on “Obtaining Hexamethylenetetramine (urotropine) from Natural Gas”. In 1945, the Synthesis of Additives Laboratory was organized in Azerbaijan Scientific-Research Institute of Oil-Processing. Guliyev headed this laboratory. As a result of experiments by him and his team, lubricating additives, Az.SRI depressor and Az.SRI -4 were applied in industry for the first time in the Soviet Union. In 1948 and 1951, Guliyev and his team of were awarded two Stalin Prizes (later renamed to The USSR State Prize) for these developments. | 0 | Theoretical and Fundamental Chemistry |
Halogenation of saturated hydrocarbons is a substitution reaction. The reaction typically requires free radical pathways. The regiochemistry of the halogenation of alkanes is largely determined by the relative weakness of the C–H bonds. This trend is reflected by the faster reaction at tertiary and secondary positions.
Fluorinations with elemental fluorine () are particularly exothermic, so much so that highly specialised conditions and apparatus are required. The method electrochemical fluorination generates small amounts of elemental fluorine in situ from hydrogen fluoride. The method avoids the hazards of handling fluorine gas. Many commercially important organic compounds are fluorinated using this technology. Aside from and its electrochemically generated equivalent, cobalt(III) fluoride is used as sources of fluorine radicals.
Free radical chlorination is used for the industrial production of some solvents:
Naturally-occurring organobromine compounds are usually produced by free radical pathway catalyzed by the enzyme bromoperoxidase. The reaction requires bromide in combination with oxygen as an oxidant. The oceans are estimated to release 1–2 million tons of bromoform and 56,000 tons of bromomethane annually.
The iodoform reaction, which involves degradation of methyl ketones, proceeds by the free radical iodination. | 0 | Theoretical and Fundamental Chemistry |
Recent advance in LFV made it possible for metering flow velocity of media which has very low electroconductivity, particularly by varying parameters as well as using some state-of-art force measurement devices enable to measure flow velocity of electrolyte solutions with conductivity that is 10 times smaller than that for the liquid metals. There are variety of industrial and scientific applications where noncontact flow measurement through opaque walls or in opaque liquids is desirable. Such applications include flow metering of chemicals, food, beverages, blood, aqueous solutions in the pharmaceutical industry, molten salts in solar thermal power plants, and high temperature reactors as well as glass melts for high-precision optics.
A noncontact flowmeter is a device that is neither in mechanical contact with the liquid nor with the wall of the pipe in which the liquid flows. Noncontact flowmeters are equally useful when walls are contaminated like in the processing of radioactive materials, when pipes are strongly vibrating or in cases when portable flowmeters are to be developed. If the liquid and the wall of the pipe are transparent and the liquid contains tracer particles, optical measurement techniques, are effective enough tool to perform noncontact measurements. However, if either the wall or the liquid are opaque as is often the case in food production, chemical engineering, glass making, and metallurgy, very few possibilities for noncontact flow measurement exist.
The force measurement system is an important part of the Lorentz force velocimetry. With high resolution force measurement system makes the measurement of even lower conductivity possible. Up to date has the force measurement system continually being developed. At first the pendulum-like setups was used (Figure 5). One of the experimental facilities consists of two high power (410 mT) magnets made of NdFeB suspended by thin wires on both side of channel thereby creating magnetic field perpendicular to the fluid flow, here deflection is measured by interferometer system,. The second setup consists of state-of-art weighting balance system (Figure 6) from which is being hanged optimized magnets on the base of Halbach array system. While the total mass of both magnet systems are equal (1 kg), this system induces 3 times higher system response due to arrangement of individual elements in the array and its interaction with predefined fluid profile. Here use of very sensitive force measuring devices is desirable, since flow velocity is being converted from the very tiny detected Lorentz Force. This force in combination with unavoidable dead weight of the magnet () is around . After that, the method of differential force measurement was developed. With this method two balance were used, one with magnet and the other is with same-weight-dummy. In this way the influence of environment would be reduced. Recently, it have been reported that the flow measurements by this method is possible for saltwater flows whose electrical conductivity is as small as 0.06 S/m (range of electrical conductivity of the regular water from tap). | 1 | Applied and Interdisciplinary Chemistry |
Protocols for conducting biosurveys of water resources have been published by state government agencies and the U.S. Environmental Protection Agency (EPA). Agencies use these protocols to implement the Clean Water Act. Similar protocols have been published by volunteer organizations. | 1 | Applied and Interdisciplinary Chemistry |
The behavior of fluids and their control in open microchannels was pioneered around 2005 and applied in air-to-liquid sample collection and chromatography. In open microfluidics, at least one boundary of the system is removed, exposing the fluid to air or another interface (i.e. liquid). Advantages of open microfluidics include accessibility to the flowing liquid for intervention, larger liquid-gas surface area, and minimized bubble formation. Another advantage of open microfluidics is the ability to integrate open systems with surface-tension driven fluid flow, which eliminates the need for external pumping methods such as peristaltic or syringe pumps. Open microfluidic devices are also easy and inexpensive to fabricate by milling, thermoforming, and hot embossing. In addition, open microfluidics eliminates the need to glue or bond a cover for devices, which could be detrimental to capillary flows. Examples of open microfluidics include open-channel microfluidics, rail-based microfluidics, paper-based, and thread-based microfluidics. Disadvantages to open systems include susceptibility to evaporation, contamination, and limited flow rate. | 1 | Applied and Interdisciplinary Chemistry |
Natural sources of iodine include many marine organisms, such as kelp and certain seafood products, as well as plants grown on iodine-rich soil. Iodized salt is fortified with iodine. According to a Food Fortification Initiative 2016 report, 130 countries have mandatory iodine fortification of salt and an additional 10 have voluntary fortification. | 1 | Applied and Interdisciplinary Chemistry |
Laser schlieren deflectometry (LSD) is a method for a high-speed measurement of the gas temperature in microscopic dimensions, in particular for temperature peaks under dynamic conditions at atmospheric pressure. The principle of LSD is derived from schlieren photography: a narrow laser beam is used to scan an area in a gas where changes in properties are associated with characteristic changes of refractive index. Laser schlieren deflectometry is claimed to overcome limitations of other methods regarding temporal and spatial resolution.
The theory of the method is analogous to the scattering experiment of Ernest Rutherford from 1911. However, instead of alpha particles scattered by gold atoms, here an optical ray is deflected by hot spots with unknown temperature.
A general equation of LSD describes the dependence of the measured maximum deflection of the ray δ on the local maximum of the neutral gas temperature in the hot spot T:
where T is ambient temperature and δ is a calibration constant depending on the configuration of the experiment.
Laser schlieren deflectometry has been used for investigation of the temperature dynamics, heat transfer and energy balance in a miniaturized kind of atmospheric-pressure plasma. | 0 | Theoretical and Fundamental Chemistry |
* Ionizing radiations such as X-rays, gamma rays and alpha particles cause DNA breakage and other damages. The most common lab sources include cobalt-60 and cesium-137.
* Ultraviolet radiations with wavelength above 260 nm are absorbed strongly by bases, producing pyrimidine dimers, which can cause error in replication if left uncorrected.
* Radioactive decay, such as C in DNA which decays into nitrogen. | 0 | Theoretical and Fundamental Chemistry |
Molecular motors are natural (biological) or artificial molecular machines that are the essential agents of movement in living organisms. In general terms, a motor is a device that consumes energy in one form and converts it into motion or mechanical work; for example, many protein-based molecular motors harness the chemical free energy released by the hydrolysis of ATP in order to perform mechanical work. In terms of energetic efficiency, this type of motor can be superior to currently available man-made motors. One important difference between molecular motors and macroscopic motors is that molecular motors operate in the thermal bath, an environment in which the fluctuations due to thermal noise are significant. | 0 | Theoretical and Fundamental Chemistry |
High photon intensity experiments can involve multiphoton processes with the absorption of integer multiples of the photon energy. In experiments that involve a multiphoton resonance, the intermediate is often a Rydberg state, and the final state is often an ion. The initial state of the system, photon energy, angular momentum and other selection rules can help in determining the nature of the intermediate state. This approach is exploited in resonance enhanced multiphoton ionization spectroscopy (REMPI). An advantage of this spectroscopic technique is that the ions can be detected with almost complete efficiency and even resolved for their mass. It is also possible to gain additional information by performing experiments to look at the energy of the liberated photoelectron in these experiments. (Compton and Johnson pioneered the development of REMPI) | 0 | Theoretical and Fundamental Chemistry |
The diffuse series limit is the same as the sharp series limit. In the late 1800s these two were termed supplementary series.
Spectral lines of the diffuse series are split into three lines in what is called fine structure. These lines cause the overall line to look diffuse. The reason this happens is that both the P and D levels are split into two closely spaced energies. P is split into . D is split into . Only three of the possible four transitions can take place because the angular momentum change cannot have a magnitude greater than one.
In 1896 Arthur Schuster stated his law: "If we subtract the frequency of the fundamental vibration from the convergence frequency of the principal series , we obtain the convergence frequency of the supplementary series". But in the next issue of the journal he realised that Rydberg had published the idea a few months earlier.
Rydberg Schuster Law: Using wave numbers, the difference between the diffuse and sharp series limits and principal series limit is the same as the first transition in the principal series.
This difference is the lowest P level.
Runge's Law: Using wave numbers the difference between the diffuse series limit and fundamental series limit is the same as the first transition in the diffuse series.
This difference is the lowest D level energy. | 0 | Theoretical and Fundamental Chemistry |
In vertebrates, vigorously contracting skeletal muscles (during weightlifting or sprinting, for example) do not receive enough oxygen to meet the energy demand, and so they shift to anaerobic metabolism, converting glucose to lactate.
The combination of glucose from noncarbohydrates origin, such as fat and proteins. This only happens when glycogen supplies in the liver are worn out. The pathway is a crucial reversal of glycolysis from pyruvate to glucose and can use many sources like amino acids, glycerol and Krebs Cycle. Large scale protein and fat catabolism usually occur when those suffer from starvation or certain endocrine disorders. The liver regenerates the glucose, using a process called gluconeogenesis. This process is not quite the opposite of glycolysis, and actually requires three times the amount of energy gained from glycolysis (six molecules of ATP are used, compared to the two gained in glycolysis). Analogous to the above reactions, the glucose produced can then undergo glycolysis in tissues that need energy, be stored as glycogen (or starch in plants), or be converted to other monosaccharides or joined into di- or oligosaccharides. The combined pathways of glycolysis during exercise, lactate's crossing via the bloodstream to the liver, subsequent gluconeogenesis and release of glucose into the bloodstream is called the Cori cycle. | 1 | Applied and Interdisciplinary Chemistry |
Polycyclic aromatic hydrocarbons (PAH) are the most common and abundant polyatomic molecules in the observable universe, and are a major store of carbon. They seem to have formed shortly after the Big Bang, and are associated with new stars and exoplanets. They are a likely constituent of Earth's primordial sea. PAHs have been detected in nebulae, and in the interstellar medium, in comets, and in meteorites.
The PAH world hypothesis posits PAHs as precursors to the RNA world. A star, HH 46-IR, resembling the sun early in its life, is surrounded by a disk of material which contains molecules including cyanide compounds, hydrocarbons, and carbon monoxide. PAHs in the interstellar medium can be transformed through hydrogenation, oxygenation, and hydroxylation to more complex organic compounds used in living cells. | 0 | Theoretical and Fundamental Chemistry |
DRESS/SJS/TEN (severe DHR) and HLA-linked DHR are p-i. Initially it was thought that p-i reactions were the exception while the hapten mechanism represented the main cause of systemic T cell mediated DHR. Conversely it seems to be the opposite as p-i appears to be the main mechanism in T cell mediated DHR: Whenever the mechanism was investigated how drugs cause severe DHR (DRESS, SJS/TEN), it was always found to be due to p-i.
It is unclear whether the majority of severe MPE is due to p-i. As the in vitro analysis of amoxicillin induced MPE (analysis of >150 amoxicillin induced MPE) regularly reveals high secretions of IL-5, IL-13, IFNg, granzyme B and granulysin upon drug exposure (very similar to DRESS cases), the in vitro drug stimulation in MPE is often strong and includes the secretion of Th1, Th2, and cytotoxic cytokines simultaneously. It is actually often stronger and broader than the cytokine secretion upon tetanus control, and is reminiscent of an in vitro mixed leukocyte reaction (MLR). Further work is needed, but most MPE appear to be mediated by p-i.
Importantly, all drugs which develop DHR and have a strong HLA-linkage (e.g. allopurinol/oxypurinol and B*58:01) stimulate via p-i. Protein reactions are not HLA restricted: A protein is large and is processed into various small peptides. These peptides (including the hapten-modified peptides) fit into different HLA alleles and not in only one HLA like observed with drugs. Thus, the DHR-HLA linkage seen with certain drugs can only be explained by direct drug binding to an allele-typic region of the HLA-molecule. This was also confirmed in structural and computational studies. Importantly, if a drug can be stimulatory by p-i or by hapten mechanism (SMX/SMX-NO, beta-lactams), the severe T cell mediated symptoms are mediated by p-i and are HLA-allele restricted, while the hapten-reactions are not. Thus, the list of drugs acting via p-i and causing DHR is now longer than the list of hapten-like drugs (table).
First hapten, then non covalent drug binding: A strong argument for a hapten-mechanism underlying DHR was the ability of the drug to cause all, namely IgG, IgE and T cell mediated DHR, since these different immune reactions required the immunogenic presentation of the drug in various ways. This is best achieved using hapten (and thus antigenic) features of a drug. Indeed, the classical hapten-drugs beta-lactam antibiotics, SMX-NO, or PPI are able to induce all forms of Gell and Coombs immune stimulations, while e.g. classical and exclusive p-i drugs like carbamazepine or abacavir induce only T cell reactions, but never anaphylaxis. Importantly, an ability to act as hapten does not rule out that non-covalent binding like in p-i plays a role in DHR. Actually, during a DHR the type of drug-protein binding may change: A drug may act as hapten in the induction phase causing asymptomatic immunity, but the effector mechanism of immunoglobulin-reactions and some severe T-cell mediated DHR may actually be due to non-covalent drug bindings. Thus, beta-lactam antibiotics – the classical hapten-drugs - are the main elicitor for "fake antigen" reactions, drug induced immune thrombocytopenia (DITP) and p-i stimulations, which are all based on non-covalent drug-protein interactions and are not antigen induced.
The polyclonal T cells response stemming from the memory T cell pool includes T cells which are primed by prior immune responses. An important role play herpes viruses (HHV6, CMV, EBV, Herpes simplex I), where a relatively large amount of T cells are involved in the control of these herpes viruses. Indeed, herpes virus reactivation is so common, that it is part of the Japanese definition of DRESS. Since the precursor frequency of such herpes virus specific T cells is high (up to 10% of the CD8+ T cells in the elderly can be devoted to herpes virus control, symptoms due to such T cells appear already after ca. 2–6 weeks. | 1 | Applied and Interdisciplinary Chemistry |
Free convection is caused by a change in density of a fluid due to a temperature change or gradient. Usually the density decreases due to an increase in temperature and causes the fluid to rise. This motion is caused by the buoyancy force. The major force that resists the motion is the viscous force. The Grashof number is a way to quantify the opposing forces.
The Grashof number is:
: for vertical flat plates
: for pipes and bluff bodies
where:
* is gravitational acceleration due to Earth
* is the coefficient of volume expansion (equal to approximately for ideal gases)
* is the surface temperature
* is the bulk temperature
* is the vertical length
* is the diameter
* is the kinematic viscosity.
The and subscripts indicate the length scale basis for the Grashof number.
The transition to turbulent flow occurs in the range for natural convection from vertical flat plates. At higher Grashof numbers, the boundary layer is turbulent; at lower Grashof numbers, the boundary layer is laminar, that is, in the range . | 1 | Applied and Interdisciplinary Chemistry |
The target vector is linearized and cut with a blunt-end restriction enzyme. This vector is then tailed with dideoxythymidine triphosphate (ddTTP) using terminal transferase. It is important to use ddTTP to ensure the addition of only one T residue. This tailing leaves the vector with a single 3'-overhanging thymine residue on each blunt end. Manufacturers commonly sell TA Cloning "kits" with a wide range of prepared vectors that have already been linearized and tagged with an overhanging thymine. | 1 | Applied and Interdisciplinary Chemistry |
Biocatalysis underpins some of the oldest chemical transformations known to humans, for brewing predates recorded history. The oldest records of brewing are about 6000 years old and refer to the Sumerians.
The employment of enzymes and whole cells have been important for many industries for centuries. The most obvious uses have been in the food and drink businesses where the production of wine, beer, cheese etc. is dependent on the effects of the microorganisms.
More than one hundred years ago, biocatalysis was employed to do chemical transformations on non-natural man-made organic compounds, with the last 30 years seeing a substantial increase in the application of biocatalysis to produce fine chemicals, especially for the pharmaceutical industry.
Since biocatalysis deals with enzymes and microorganisms, it is historically classified separately from "homogeneous catalysis" and "heterogeneous catalysis". However, mechanistically speaking, biocatalysis is simply a special case of heterogeneous catalysis. | 0 | Theoretical and Fundamental Chemistry |
Carboxypeptidase E is found in brain and throughout the neuroendocrine system, including the endocrine pancreas, pituitary, and adrenal gland chromaffin cells. Within cells, carboxypeptidase E is present in the secretory granules along with its peptide substrates and products. Carboxypeptidase E is a glycoprotein that exists in both membrane-associated and soluble forms. The membrane-binding is due to an amphiphilic α-helix within the C-terminal region of the protein. | 1 | Applied and Interdisciplinary Chemistry |
eIF1 and eIF1A both bind to the 40S ribosome subunit-mRNA complex. Together they induce an "open" conformation of the mRNA binding channel, which is crucial for scanning, tRNA delivery, and start codon recognition. In particular, eIF1 dissociation from the 40S subunit is considered to be a key step in start codon recognition.
eIF1 and eIF1A are small proteins (13 and 16 kDa, respectively in humans) and are both components of the 43S PIC. eIF1 binds near the ribosomal P-site, while eIF1A binds near the A-site, in a manner similar to the structurally and functionally related bacterial counterparts IF3 and IF1, respectively. | 1 | Applied and Interdisciplinary Chemistry |
Because of the double-stranded nature of DNA, essentially all of the nucleotides take the form of Watson–Crick base pairs between nucleotides on the two complementary strands of the double helix.
In contrast, both RNA and proteins are normally single-stranded. Therefore, they are not constrained by the regular geometry of the DNA double helix, and so fold into complex three-dimensional shapes dependent on their sequence. These different shapes are responsible for many of the common properties of RNA and proteins, including the formation of specific binding pockets, and the ability to catalyse biochemical reactions. | 0 | Theoretical and Fundamental Chemistry |
Because of the large quantity of data produced by these techniques and the desire to find biologically meaningful patterns, bioinformatics is crucial to analysis of functional genomics data. Examples of techniques in this class are data clustering or principal component analysis for unsupervised machine learning (class detection) as well as artificial neural networks or support vector machines for supervised machine learning (class prediction, classification). Functional enrichment analysis is used to determine the extent of over- or under-expression (positive- or negative- regulators in case of RNAi screens) of functional categories relative to a background sets. Gene ontology based enrichment analysis are provided by DAVID and gene set enrichment analysis (GSEA), pathway based analysis by Ingenuity and Pathway studio and protein complex based analysis by COMPLEAT.
New computational methods have been developed for understanding the results of a deep mutational scanning experiment. phydms compares the result of a deep mutational scanning experiment to a phylogenetic tree. This allows the user to infer if the selection process in nature applies similar constraints on a protein as the results of the deep mutational scan indicate. This may allow an experimenter to choose between different experimental conditions based on how well they reflect nature. Deep mutational scanning has also been used to infer protein-protein interactions. The authors used a thermodynamic model to predict the effects of mutations in different parts of a dimer. Deep mutational structure can also be used to infer protein structure. Strong positive epistasis between two mutations in a deep mutational scan can be indicative of two parts of the protein that are close to each other in 3-D space. This information can then be used to infer protein structure. A proof of principle of this approach was shown by two groups using the protein GB1.
Results from MPRA experiments have required machine learning approaches to interpret the data. A gapped k-mer SVM model has been used to infer the kmers that are enriched within cis-regulatory sequences with high activity compared to sequences with lower activity. These models provide high predictive power. Deep learning and random forest approaches have also been used to interpret the results of these high-dimensional experiments. These models are beginning to help develop a better understanding of non-coding DNA function towards gene-regulation. | 1 | Applied and Interdisciplinary Chemistry |
Wells studied at The Queens College, University of Oxford and obtained his BA and MA in 1934 and 1937, respectively. He then moved to University of Cambridge, where he obtained his PhD in X-ray crystallography in 1939, under the supervision of J. D. Bernal. His PhD thesis was titled The Crystal Structures of Certain Complex Metallic Compounds'. He worked as research scientist at Cambridge from 1937 to 1940 and at University of Birmingham from 1940 till 1944. He moved to the industry afterwards, working as a senior research associate at Imperial Chemical Industries from 1944 to 1968. Wells was not interested in senior administrative jobs offer to him in the industry, he moved back to academia and became a professor of chemistry at University of Connecticut in the US from 1968 until his retirement in 1980. | 0 | Theoretical and Fundamental Chemistry |
Perilipin is part of a gene family with six currently-known members. In vertebrates, closely related genes include adipophilin (also known as adipose differentiation-related protein or Perilipin 2), TIP47 (Perilipin 3), Perilipin 4 and Perilipin 5 (also called MLDP, LSDP5, or OXPAT). Insects express related proteins, LSD1 and LSD2, in fat bodies. The yeast Saccharomyces cerevisiae expresses PLN1 (formerly PET10), that stabilizes lipid droplets and aids in their assembly. | 1 | Applied and Interdisciplinary Chemistry |
The simplest gas centrifuge is the concurrent centrifuge, where separative effect is produced by the centrifugal effects of the rotor's rotation. In these centrifuges, the heavy fraction is collected at the periphery of the rotor, and the light fraction from nearer the axis of rotation.
Inducing a countercurrent flow uses countercurrent multiplication to enhance the separative effect. A vertical circulating current is set up, with the gas flowing axially along the rotor walls in one direction, and a return flow closer to the center of the rotor. The centrifugal separation continues as before (heavier molecules preferentially moving outwards), which means that the heavier molecules are collected by the wall flow, and the lighter fraction collects at the other end. In a centrifuge with downward wall flow, the heavier molecules collect at the bottom. The outlet scoops are then placed at the ends of the rotor cavity, with the feed mixture injected along the axis of the cavity (ideally, the injection point is at the point where the mixture in the rotor is equal to the feed).
This countercurrent flow can be induced mechanically or thermally, or a combination. In mechanically induced countercurrent flow, the arrangement of the (stationary) scoops and internal rotor structures are used to generate the flow. A scoop interacts with the gas by slowing it, which tends to draw it into the centre of the rotor. The scoops at each end induce opposing currents, so one scoop is protected from the flow by a "baffle": a perforated disc within the rotor which rotates along with the gas—at this end of the rotor, the flow will be outwards, towards the rotor wall. Thus, in a centrifuge with a baffled top scoop, the wall flow is downwards, and heavier molecules are collected at the bottom.
Thermally induced convection currents can be created by heating the bottom of the centrifuge and/or cooling the top end. | 0 | Theoretical and Fundamental Chemistry |
Neutron activation analysis (NAA) is a nuclear process used for determining the concentrations of elements in many materials. NAA allows discrete sampling of elements as it disregards the chemical form of a sample, and focuses solely on atomic nuclei. The method is based on neutron activation and thus requires a neutron source. The sample is bombarded with neutrons, causing its constituent elements to form radioactive isotopes. The radioactive emissions and radioactive decay paths for each element have long been studied and determined. Using this information, it is possible to study spectra of the emissions of the radioactive sample, and determine the concentrations of the various elements within it. A particular advantage of this technique is that it does not destroy the sample, and thus has been used for the analysis of works of art and historical artifacts. NAA can also be used to determine the activity of a radioactive sample.
If NAA is conducted directly on irradiated samples it is termed instrumental neutron activation analysis (INAA). In some cases, irradiated samples are subjected to chemical separation to remove interfering species or to concentrate the radioisotope of interest; this technique is known as radiochemical neutron activation analysis (RNAA).
NAA can perform non-destructive analyses on solids, liquids, suspensions, slurries, and gases with no or minimal preparation. Due to the penetrating nature of incident neutrons and resultant gamma rays, the technique provides a true bulk analysis. As different radioisotopes have different half-lives, counting can be delayed to allow interfering species to decay eliminating interference. Until the introduction of ICP-AES and PIXE, NAA was the standard analytical method for performing multi-element analyses with minimum detection limits in the sub-ppm range. Accuracy of NAA is in the region of 5%, and relative precision is often better than 0.1%. There are two noteworthy drawbacks to the use of NAA; even though the technique is essentially non-destructive, the irradiated sample will remain radioactive for many years after the initial analysis, requiring handling and disposal protocols for low-level to medium-level radioactive material; also, the number of suitable activation nuclear reactors is declining; with a lack of irradiation facilities, the technique has declined in popularity and become more expensive. | 0 | Theoretical and Fundamental Chemistry |
A carbon-to-nitrogen ratio (C/N ratio or C:N ratio) is a ratio of the mass of carbon to the mass of nitrogen in organic residues. It can, amongst other things, be used in analysing sediments and soil including soil organic matter and soil amendments such as compost. | 0 | Theoretical and Fundamental Chemistry |
He is credited with writing the following episodes:
*"How Hermes Requisitioned His Groove Back" (2000)
*"A Tale of Two Santas" (2001)
*"Insane in the Mainframe" (2001)
*"Kif Gets Knocked Up a Notch" (2003)
*"The Farnsworth Parabox" (2003) | 0 | Theoretical and Fundamental Chemistry |
Nuclear fuel is material used in nuclear power stations to produce heat to power turbines. Heat is created when nuclear fuel undergoes nuclear fission.
Most nuclear fuels contain heavy fissile actinide elements that are capable of undergoing and sustaining nuclear fission. The three most relevant fissile isotopes are uranium-233, uranium-235 and plutonium-239. When the unstable nuclei of these atoms are hit by a slow-moving neutron, they frequently split, creating two daughter nuclei and two or three more neutrons. In that case, the neutrons released go on to split more nuclei. This creates a self-sustaining chain reaction that is controlled in a nuclear reactor, or uncontrolled in a nuclear weapon. Alternatively, if the nucleus absorbs the neutron without splitting, it creates a heavier nucleus with one additional neutron.
The processes involved in mining, refining, purifying, using, and disposing of nuclear fuel are collectively known as the nuclear fuel cycle.
Not all types of nuclear fuels create power from nuclear fission; plutonium-238 and some other isotopes are used to produce small amounts of nuclear power by radioactive decay in radioisotope thermoelectric generators and other types of atomic batteries.
Nuclear fuel has the highest energy density of all practical fuel sources. | 0 | Theoretical and Fundamental Chemistry |
Smith was born on September 25, 1916, in Long Beach, California, and he grew up in Long Beach and Fontana, California. He attended Pomona College, graduating in 1938, and was a member of the Phi Beta Kappa honors society. While as a student at Pomona, Smith authored two papers with his chemistry professor, Wesley G. Leighton. After leaving Pomona, Smith went to Stanford University to work under Leighton's brother Philip A. Leighton and was awarded an M.A. and Ph.D. in 1940 and 1942 respectively. | 0 | Theoretical and Fundamental Chemistry |
Sensor-based ore sorting is in comparison to other coarse particle separation technologies relatively cheap. While the costs for the equipment itself are relatively high in capital expenditure and operating costs, the absence of extensive infrastructure in a system results in operating costs that are to be compared to jigging. The specific costs are very much depending on the average particle size of the feed and on the ease of the separation. Coarser particles imply higher capacity and thus less costs. Detailed costing can be conducted after the mini-bulk stage in the technical feasibility evaluation.
Prejudice against waste rejection with sensor-based sorting widely spread, that the loss of valuables, thus the recovery penalty of this process, supersedes the potential downstream cost savings and is therefore economically not viable. It must be noted that for waste rejection the aim for the separation with sensor-based ore sorting must be put onto maximum recovery, which means that only low grade or barren waste is rejected because the financial feasibility is very much sensitive to that factor. Nevertheless, through the rejection of waste before comminution and concentration steps, recovery can be often increased in the downstream process, meaning that the overall recovery is equal or even higher than the one in the base case, meaning that instead of losing product, additional product can be produced, which adds the additional revenue to the cost savings on the positive side in the cash flow.
If the rejected material is replaced with additional higher grade material, the main economic benefit unfolds through the additional production. It implies, that in conjunction with sensor-based ore sorting, the capacity of the crushing station is increased, to allow for the additional mass-flow that is subsequently taken out by the sensor-based ore sorters as waste. | 0 | Theoretical and Fundamental Chemistry |
Formate is produced by the cleavage of pyruvate. This reaction is catalysed by the enzyme pyruvate-formate lyase (PFL), which plays an important role in regulating anaerobic fermentation in E. coli.
pyruvate + CoA → acetyl-CoA + formate | 1 | Applied and Interdisciplinary Chemistry |
Single-cell proteins (SCP) or microbial proteins refer to edible unicellular microorganisms. The biomass or protein extract from pure or mixed cultures of algae, yeasts, fungi or bacteria may be used as an ingredient or a substitute for protein-rich foods, and is suitable for human consumption or as animal feeds. Industrial agriculture is marked by a high water footprint, high land use, biodiversity destruction, general environmental degradation and contributes to climate change by emission of a third of all greenhouse gases; production of SCP does not necessarily exhibit any of these serious drawbacks. As of today, SCP is commonly grown on agricultural waste products, and as such inherits the ecological footprint and water footprint of industrial agriculture. However, SCP may also be produced entirely independent of agricultural waste products through autotrophic growth. Thanks to the high diversity of microbial metabolism, autotrophic SCP provides several different modes of growth, versatile options of nutrients recycling, and a substantially increased efficiency compared to crops. A 2021 publication showed that photovoltaic-driven microbial protein production could use 10 times less land for an equivalent amount of protein compared to soybean cultivation.
With the world population reaching 9 billion by 2050, there is strong evidence that agriculture will not be able to meet demand and that there is serious risk of food shortage. Autotrophic SCP represents options of fail-safe mass food-production which can produce food reliably even under harsh climate conditions. | 1 | Applied and Interdisciplinary Chemistry |
Using either Pd–Cu or Cu catalysts Yang et al. reported the first example of decarboxylative C–P cross-coupling. | 0 | Theoretical and Fundamental Chemistry |
Geoksyur Oasis, located in the foothills of the Kopetdag, to the east of Altyndepe, is in the center of a cluster of tepes in the desert region on the northern Iranian border. It extends over an area of 12 ha. It is to the east of the city of Tedzhen. Even though in the Aneolithic Period (4th – early 3rd century BC), the space between houses was used for burials, the settlement was not a cemetery but rather a settlement which was affected by shifting sand dunes and scarcity of water. Geoksyr was revealed to contain "adobe multi-room houses and group burial chambers". Ceramics were also found with dichromatic paintings and many female terracotta figurines. The culture of Geoksyurtepe was correlated with an eastern Anau group of tribes linked to Elam and Mesopotamia. | 1 | Applied and Interdisciplinary Chemistry |
Wootz steel, also known as Seric steel, is a crucible steel characterized by a pattern of bands and high carbon content. These bands are formed by sheets of microscopic carbides within a tempered martensite or pearlite matrix in higher-carbon steel, or by ferrite and pearlite banding in lower-carbon steels. It was a pioneering steel alloy developed in southern India in the mid-1st millennium BC and exported globally. | 1 | Applied and Interdisciplinary Chemistry |
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