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Initiation in archaea is governed by TATA-binding protein (TBP), Archaeal transcription factor B (TFB), and Archaeal transcription factor E (TFE) that are homologous to eukaryotic TBP, TFIIB, and TFIIE respectively. These factors recognize the promoter core sequence (TATA box, B recognition element) upstream of the coding region and recruits the RNAP to form a closed transcription preinitiation complex (PIC).
The PIC is turned into an open state with the local DNA helix "melting" to load the template strand of DNA. The RNAP undergoes "abortive initiation": it makes and releases many short (2-15nt) segments before generating a transcript of significant length. This continues until it moves past the promoter (promoter escape), loosening TBP's grasp on the DNA, and swapping TFE out for elongation factors Spt4/5. How this escape happens exactly remains to be studied. | 1 | Applied and Interdisciplinary Chemistry |
Each of the functional regions of TFIIB interacts with different parts of RNA polymerase II. The amino terminal B ribbon is located on dock domain of RNA polymerase II and extends in to the cleft towards the active site. Extending the B ribbon is the B reader that extends via the RNA exit tunnel to the binding site of the DNA-RNA hybrid and towards the active site. The B linker is the region between the B reader and the B core that is found in the cleft of RNA polymerase II and continues by the rudder and the clamp coiled-coil until it reaches the C terminal B core that is found above the wall of RNA polymerase II.
The B reader and the B linker consist of highly conserved residues that are positioned through the RNA polymerase II tunnel towards the active site and ensure tight binding, without these key residues dissociation would occur. These two domains are also thought to adjust the position of some of the more flexible areas of RNA polymerase II to allow for the precise positioning of the DNA and allowing the addition of the new NTPs onto the nascent RNA chain.
Upon binding RNA polymerase II, the B reader and B linker cause slight repositioning of the protrusion domain of RNA polymerase II which allows an essential second magnesium ion to bind in the active site. It forms a beta sheet and an ordered loop that helps with the stability of the structure when transcription is initiated. | 1 | Applied and Interdisciplinary Chemistry |
In 1850, Clausius, responding to Joule's experimental demonstrations of heat production by friction, rejected the caloric doctrine of conservation of heat, writing:
:::::If we assume that heat, like matter, cannot be lessened in quantity, we must also assume that it cannot be increased; but it is almost impossible to explain the ascension of temperature brought about by friction otherwise than by assuming an actual increase of heat. The careful experiments of Joule, who developed heat in various ways by the application of mechanical force, establish almost to a certainty, not only the possibility of increasing the quantity of heat, but also the fact that the newly-produced heat is proportional to the work expended in its production. It may be remarked further, that many facts have lately transpired which tend to overthrow the hypothesis that heat is itself a body, and to prove that it consists in a motion of the ultimate particles of bodies.
The process function was introduced by Rudolf Clausius in 1850.
Clausius described it with the German compound Wärmemenge, translated as "amount of heat". | 0 | Theoretical and Fundamental Chemistry |
Organic peroxides are classified (i) by the presence or absence of a hydroxyl (-OH) terminus and (ii) by the presence of alkyl vs acyl substituents.
One gap in the classes of organic peroxides is diphenyl peroxide. Quantum chemical calculations predict that it undergoes a nearly barrierless reaction akin to the benzidine rearrangement. | 0 | Theoretical and Fundamental Chemistry |
Scrubbers are material washers used to break down and disperse clays in order to prepare mineral ores or construction aggregates for further processing. Sepro Tyre Drive Scrubbers are manufactured up to 3.6m in diameter and are capable of processing up to 1500 tonnes per hour of material. Shell supported Scrubbers such as the Sepro PTD Scrubber minimize stress on the shell by spreading the power drive over the full length of the washing drum. These scrubbers operate in many applications on feeds with high clay content, and are commonly used for difficult ore and stone washing duties. A few specified applications of Sepro Scrubbers include removal of gold “robbing” carboniferous material and other contaminants from gold ores, the processing of bauxite ores for aluminum production, the washing of laterites (gold, nickel, cobalt) to liberate fine metals for gravity recovery, and the washing of crushed aggregate, gravel and sand to remove clay contamination. | 1 | Applied and Interdisciplinary Chemistry |
A ligand is a molecule utilized for cell-signaling that binds to a target tissue for cellular communication. There are many different types of ligands including: internal receptors, cell-surface receptors, Ion-channel receptors, G-Protein Coupled Receptors (GPCRs), and enzyme-linked receptors. Ligands can be divided into two categories, agonists or antagonists. Agonists behave similarly to natural ligands, while antagonists are inhibitors and block the binding of the natural ligand. There are many different subtypes of agonists, including endogenous agonists, super agonist, full agonist, inverse agonist, and irreversible agonist.
Radioligands are made up of the radioisotope, linker, and ligand. This structure allows the compound to identify and bind to the target tissue while retaining the ability to be tracked and imaged clinically. When a radioligand binds to its target, it alters the microenvironment of the receptor and surrounding tissue, partially due to the structure of the radioligand itself. Without both the high affinity ligand and the radioisotope, the efficiency of this process is lost. | 1 | Applied and Interdisciplinary Chemistry |
* First - 1699
* Second - 1722
* Third - 1735
* Fourth - 1744
* Fifth - 1756
* Sixth - 1774
* Seventh - 1783
* Eighth - 1792
* Ninth - 1803
* Revised Ninth - 1805
* Tenth - 1817
* Eleventh (first in English) - 1839
* Twelfth (second in English) - 1841 | 1 | Applied and Interdisciplinary Chemistry |
He married Catherine Connelly (also a biochemist) in Holyoke, Massachusetts, On September 16, 1961. He raised a family of four children: Miguel Luis, Juan Ignacio, Jorge Eduardo and Maria Amparo and has 13 grandchildren.
With his wife, Catherine Connelly, he was on sabbatical at the University of California at San Diego, when the 1973 coup in Chile took place. He returned to Chile in May 1974 and was one of the main defenders of the University of Chile's autonomy, endangered by the military intervention in academic life. In December 1975 he co-signed, with other academics, a letter entitled "University under surveillance" opposing military intervention in the University of Chile. The letter was written by philosopher Jorge Millas and published in the newspaper "El Mercurio". The letter was the first appearance of a public statement by a group of academics who criticized the handling of the University of Chile by the military government. | 1 | Applied and Interdisciplinary Chemistry |
MG-RAST, an open-source web application server, facilitates automatic phylogenetic and functional analysis of metagenomes. It stands as one of the largest repositories for metagenomic data, employing the acronym for Metagenomic Rapid Annotations using Subsystems Technology (MG-RAST). This platform utilizes a pipeline that automatically assigns functions to metagenomic sequences, conducting sequence comparisons at both nucleotide and amino acid levels. Users benefit from phylogenetic and functional insights into the analyzed metagenomes, along with tools for comparing different datasets. MG-RAST also offers a RESTful API for programmatic access.
Argonne National Laboratory from the University of Chicago created and maintains this server. As of December 29, 2016, MG-RAST had analyzed a substantial 60 terabase-pairs of data from over 150,000 datasets. Notably, more than 23,000 of these datasets are publicly available. Computational resources are currently sourced from the DOE Magellan cloud at Argonne National Laboratory, Amazon EC2 Web services, and various traditional clusters. | 1 | Applied and Interdisciplinary Chemistry |
Joule heating is caused by interactions between charge carriers (usually electrons) and the body of the conductor.
A potential difference (voltage) between two points of a conductor creates an electric field that accelerates charge carriers in the direction of the electric field, giving them kinetic energy. When the charged particles collide with the quasi-particles in the conductor (i.e. the canonically quantized, ionic lattice oscillations in the harmonic approximation of a crystal), energy is being transferred from the electrons to the lattice (by the creation of further lattice oscillations). The oscillations of the ions are the origin of the radiation ("thermal energy") that one measures in a typical experiment. | 0 | Theoretical and Fundamental Chemistry |
Lateral manipulation means moving an adsorbate on the surface by making a temporary chemical or physical bond between the STM tip and the adsorbate. A typical lateral manipulation sequence begins by positioning the tip close to the adsorbate, bringing the tip close to the surface by increasing the tunneling current setpoint, moving the tip along a desired route and finally retracting the tip to normal scanning height. Lateral manipulation is typically applied to strongly bound adsorbates, such as metal adatoms on metal surfaces. The probability that the surface adsorbate moves the same distance traveled by the tip is strongly dependent on the tip conditions.
Depending on the tip apex and the surface/adsorbate system, the lateral motion can occur by pushing, pulling or sliding of the adsorbate. These modes result in distinct tunneling current signals during the lateral motion. For example, periodic steps in the tunneling current indicate that the adsorbate is “jumping” between adsorption sites while following the tip: this means the tip pushes or pulls the adsorbate. | 0 | Theoretical and Fundamental Chemistry |
The puddling furnace is a metalmaking technology used to create wrought iron or steel from the pig iron produced in a blast furnace. The furnace is constructed to pull the hot air over the iron without the fuel coming into direct contact with the iron, a system generally known as a reverberatory furnace or open hearth furnace. The major advantage of this system is keeping the impurities of the fuel separated from the charge.
The hearth is where the iron is charged, melted and puddled. The hearth's shape is usually elliptical; in length and wide. If the furnace is designed to puddle white iron then the hearth depth is never more than . If the furnace is designed to boil gray iron then the average hearth depth is . Due to the great heat required to melt the charge the grate had to be cooled, lest it melt with the charge. This was done by running a constant flow of cool air on it, or by throwing water on the bottom of the grate.
The fireplace, where the fuel is burned, used a cast iron grate which varied in size depending on the fuel used. If bituminous coal is used then an average grate size is and is loaded with of coal. If anthracite coal is used then the grate is and is loaded with of coal.
A double puddling furnace is similar to a single puddling furnace, with the major difference being there are two work doors allowing two puddlers to work the furnace at the same time. The biggest advantage of this setup is that it produces twice as much wrought iron. It is also more economical and fuel efficient compared to a single furnace. | 1 | Applied and Interdisciplinary Chemistry |
Phillips obtained his bachelor's degree in Biochemistry and Chemistry from Rice University in 1974 and followed it with a Ph.D. in biochemistry from the same institution in 1976. He also held a Robert A. Welch Predoctoral Fellowship from 1974 to 1976 and received a Postdoctoral Fellowship from the National Institutes of Health in 1977 as well as a Research Fellowship from the Medical Foundation in 1980. | 1 | Applied and Interdisciplinary Chemistry |
In chemistry, a (redox) non-innocent ligand is a ligand in a metal complex where the oxidation state is not
clear. Typically, complexes containing non-innocent ligands are redox active at mild potentials. The concept assumes that redox reactions in metal complexes are either metal or ligand localized, which is a simplification, albeit a useful one.
C.K. Jørgensen first described ligands as "innocent" and "suspect": "Ligands are innocent when they allow oxidation states of the central atoms to be defined. The simplest case of a suspect ligand is NO..." | 0 | Theoretical and Fundamental Chemistry |
Stereocontrol for cyclohexane rings is well established in organic chemistry, in large part due to the axial/equatorial preferential positioning of substituents on the ring. Macrocyclic stereocontrol models the substitution and reactions of medium and large rings in organic chemistry, with remote stereogenic elements providing enough conformational influence to direct the outcome of a reaction.
Early assumptions towards macrocycles in synthetic chemistry considered them far too floppy to provide any degree of stereochemical or regiochemical control in a reaction. The experiments of W. Clark Still in the late 1970s and 1980s challenged this assumption, while several others found crystallographic data and NMR data that suggested macrocyclic rings were not the floppy, conformationally ill-defined species many assumed.
The degree to which a macrocyclic ring is either rigid or floppy depends significantly on the substitution of the ring and the overall size. Significantly, even small conformational preferences, such as those envisioned in floppy macrocycles, can profoundly influence the ground state of a given reaction, providing stereocontrol such as in the synthesis of miyakolide. Computational modeling can predict conformations of medium rings with reasonable accuracy, as Still used molecular mechanics modeling computations to predict ring conformations to determine potential reactivity and stereochemical outcomes.
Reaction classes used in synthesis of natural products under the macrocyclic stereocontrol model for obtaining a desired stereochemistry include: hydrogenations such as in neopeltolide and (±)-methynolide, epoxidations such as in (±)-periplanone B and lonomycin A, hydroborations such as in 9-dihydroerythronolide B, enolate alkylations such as in (±)-3-deoxyrosaranolide, dihydroxylations such as in cladiell-11-ene-3,6,7-triol, and reductions such as in eucannabinolide. | 0 | Theoretical and Fundamental Chemistry |
*POLR1C
*POLR1D
*POLR1E
*POLR2A
*POLR2B
*POLR2C
*POLR2D
*POLR2E
*POLR2F
*POLR2G
*POLR2H
*POLR2I
*POLR2J
*POLR2K
*POLR2L
*POLR3C
*POLR3E
*POLR3GL
*POLR3K | 1 | Applied and Interdisciplinary Chemistry |
Electrometallurgy is the field concerned with the processes of metal electrodeposition. There are seven categories of these processes:
*Electrolysis
*Electrowinning, the extraction of metal from ores
*Electrorefining, the purification of metals. Metal powder production by electrodeposition is included in this category, or sometimes electrowinning, or a separate category depending on application.
*Electroplating, the deposition of a layer of one metal on another
*Electroforming, the manufacture of, usually thin, metal parts through electroplating
*Electropolishing, the removal of material from a metallic workpiece
*Etching, industrially known to Wikipedia as chemical milling | 1 | Applied and Interdisciplinary Chemistry |
The relationship between genes can be measured by comparing the sequences of their DNA. If the level of similarity exceeds a minimum value, one can conclude that the genes descend from a common ancestor; they are homologous. Genes that are related by direct descent from a common ancestor are orthologous genes - they are usually found at the same locus in different species. Genes that are related as a result of a gene duplication event are parologous genes.
It is often assumed that the functions of orthologous genes are more similar than those of paralogous genes, although the difference is minimal. | 1 | Applied and Interdisciplinary Chemistry |
Transitions between redox species Cu and Cu fractionate Cu isotopes. Cu is preferentially reduced over Cu, leaving the residual Cu enriched in Cu. The equilibrium fractionation factor for speciation between Cu and Cu (α) is 1.00403 (i.e., dissolved Cu is enriched in Cu by ~+4‰ relative to Cu). | 0 | Theoretical and Fundamental Chemistry |
International Organization for Standardization (ISO) is a non-governmental institution (established under the aegis of the UN) bridging public and private sectors. ISO is an international standard setter for “business, government and society,” through its pursuit of voluntary standards. These standards range from those dealing with size, clarity, and weights measures to the systems businesses ought to put in place to enhance customer satisfaction. Its work thus has an intimate impact on daily life by shaping and molding the way in which commerce is conducted, the operating procedures of business, and the way in which consumers engage with markets.
Some of this standard setting was the result of government and business agreement on product development; others were the consequence of commercial battles fought out over the most appropriate format. The organization boasts having developed more than 17,000 international standards in its 60-year history and claims that it is engaged in producing an additional 1,100 standards each year. ISO are usually put in consideration in lifecycle assessment of products.
The ISO 81.040 contains the international standards for glass. It's divided in four chapters.
* 81.040.01 Glass in general.
* 81.040.10 raw materials and raw glass.
* 81.040.20 Glass in building.
* 81.040.30 Glass products.
Other related ISO:
* 55.100 Bottles, pots, jars.
* 71.040.20 Laboratory glassware. | 0 | Theoretical and Fundamental Chemistry |
In principle, the M-NX group could be pyramidal or planar. The pyramidal geometry is not observed.
In many complexes, the amido is a bridging ligand. Some examples have both bridging and terminal amido ligands. Bulky amide ligands have a lesser tendency to bridge. Amide ligands may participate in metal-ligand π-bonding giving a complex with the metal center being co-planar with the nitrogen and substituents. Metal bis(trimethylsilyl)amides form a significant subcategory of metal amide compounds. These compounds tend to be discrete and soluble in organic solvents. | 0 | Theoretical and Fundamental Chemistry |
Volatilization methods can be either direct or indirect. Water eliminated in a quantitative manner from many inorganic substances by ignition is an example of a direct determination. It is collected on a solid desiccant and its mass determined by the gain in mass of the desiccant.
Another direct volatilization method involves carbonates which generally decompose to release carbon dioxide when acids are used. Because carbon dioxide is easily evolved when heat is applied, its mass is directly established by the measured increase in the mass of the absorbent solid used.
Determination of the amount of water by measuring the loss in mass of the sample during heating is an example of an indirect method. It is well known that changes in mass occur due to decomposition of many substances when heat is applied, regardless of the presence or absence of water. Because one must make the assumption that water was the only component lost, this method is less satisfactory than direct methods.
This often faulty and misleading assumption has proven to be wrong on more than a few occasions. There are many substances other than water loss that can lead to loss of mass with the addition of heat, as well as a number of other factors that may contribute to it. The widened margin of error created by this all-too-often false assumption is not one to be lightly disregarded as the consequences could be far-reaching.
Nevertheless, the indirect method, although less reliable than direct, is still widely used in commerce. For example, it's used to measure the moisture content of cereals, where a number of imprecise and inaccurate instruments are available for this purpose. | 0 | Theoretical and Fundamental Chemistry |
Phenol is readily alkylated at the ortho positions using alkenes in the presence of a Lewis acid such as aluminium phenoxide:
: CH=CR + CHOH → RCHCH-2-CHOH
More than 100,000 tons of tert-butyl phenols are produced annually (year: 2000) in this way, using isobutylene (CH=CMe) as the alkylating agent. Especially important is 2,6-ditert-butylphenol, a versatile antioxidant. | 0 | Theoretical and Fundamental Chemistry |
Lattice confinement fusion (LCF) is a type of nuclear fusion in which deuteron-saturated metals are exposed to gamma radiation or ion beams, such as in an IEC fusor, avoiding the confined high-temperature plasmas used in other methods of fusion. | 0 | Theoretical and Fundamental Chemistry |
* Fred Morrison Scholarship (1994)
* Thieme Journal Award (2012)
* American Chemical Society Young Academic Investigator Award (2013)
* Boston University Ignition Award (2013)
* Boston University Materials Science and Engineering Innovation Award (2013)
* National Science Foundation CAREER Award (2013)
* Alfred P. Sloan Fellowship (2013)
* Boston University Innovation Professorship (2013)
* Camille Dreyfus Teacher-Scholar Award (2014) | 0 | Theoretical and Fundamental Chemistry |
Outside and far from the tube, the liquid reaches a ground level in contact with the atmosphere. Liquids in communicating vessels have the same pressures at the same heights, so a point , inside the tube, at the same liquid level as outside, would have the same pressure . Yet the pressure at this point follows a vertical pressure variation as
where is the gravitational acceleration and the density of the liquid. This equation means that the pressure at point is the pressure at the interface plus the pressure due to the weight of the liquid column of height . In this way, we can calculate the pressure at the convex interface | 1 | Applied and Interdisciplinary Chemistry |
Single-molecule fluorescence spectroscopy uses the fluorescence of a molecule for obtaining information on its environment, structure, and position. The technique affords the ability of obtaining information otherwise not available due to ensemble averaging (that is, a signal obtained when recording many molecules at the same time represents an average property of the molecules' dynamics). The results in many experiments of individual molecules are two-state trajectories. | 0 | Theoretical and Fundamental Chemistry |
The complex is a large integral membrane protein composed of several metal prosthetic sites and 14 protein subunits in mammals. In mammals, eleven subunits are nuclear in origin, and three are synthesized in the mitochondria. The complex contains two hemes, a cytochrome a and cytochrome a, and two copper centers, the Cu and Cu centers. In fact, the cytochrome a and Cu form a binuclear center that is the site of oxygen reduction. Cytochrome c, which is reduced by the preceding component of the respiratory chain (cytochrome bc1 complex, Complex III), docks near the Cu binuclear center and passes an electron to it, being oxidized back to cytochrome c containing Fe. The reduced Cu binuclear center now passes an electron on to cytochrome a, which in turn passes an electron on to the cytochrome a>-Cu binuclear center. The two metal ions in this binuclear center are 4.5 Å apart and coordinate a hydroxide ion in the fully oxidized state.
Crystallographic studies of cytochrome c oxidase show an unusual post-translational modification, linking C6 of Tyr(244) and the ε-N of His(240) (bovine enzyme numbering). It plays a vital role in enabling the cytochrome a- Cu binuclear center to accept four electrons in reducing molecular oxygen and four protons to water. The mechanism of reduction was formerly thought to involve a peroxide intermediate, which was believed to lead to superoxide production. However, the currently accepted mechanism involves a rapid four-electron reduction involving immediate oxygenoxygen bond cleavage, avoiding any intermediate likely to form superoxide. | 1 | Applied and Interdisciplinary Chemistry |
Change in physical interactions can be utilized for the solidification process, and the fibrous state is usually achieved outside of the extrusion nozzle. Due to the reversibility of those physical interactions, subsequent crosslinking is traditionally required. | 0 | Theoretical and Fundamental Chemistry |
Liu was born on 1925 in Anyuan District of Pingxiang to Liu Shaoqi and He Baozhen. When he was two years old, he was sent back to Liu Shaoqi's hometown in Ningxiang County, Hunan for foster care. In 1934, his mother was executed while in captivity by the Kuomintang.
In July 1938, the Chinese Communist Party brought Liu to Yanan to reunite with his father. In the autumn of the same year, at the age of 13, Liu started studying at Yanan Education Primary School. | 0 | Theoretical and Fundamental Chemistry |
The notion of energy quality was also recognised in the economic sciences. In the context of biophysical economics energy quality was measured by the amount of economic output generated per unit of energy input (C.J. Cleveland et al. 2000). The estimation of energy quality in an economic context is also associated with embodied energy methodologies. Another example of the economic relevance of the energy quality concept is given by Brian Fleay. Fleay says that the "Energy Profit Ratio (EPR) is one measure of energy quality and a pivotal index for assessing the economic performance of fuels. Both the direct and indirect energy inputs embodied in goods and services must be included in the denominator." (2006; p. 10) Fley calculates the EPR as the energy output/energy input. | 0 | Theoretical and Fundamental Chemistry |
is stable to air. It is, however, unstable in the thermodynamic sense with a positive enthalpy of formation of +460 kJ/mol. This endothermic enthalpy of formation originates in the difference in energy of compared to its highly stable decomposition products:
Because one of its decomposition products is a gas, can be used as an explosive. Purer samples tend to be more explosive. Small samples can be detonated by striking with a hammer. is thermochromic, changing from pale yellow below −30 °C to orange at room temperature to deep red above 100 °C. | 0 | Theoretical and Fundamental Chemistry |
For a transition where a single charged particle changes state from to , the transition dipole moment is
where q is the particles charge, r is its position, and the integral is over all space ( is shorthand for ). The transition dipole moment is a vector; for example its x'-component is
In other words, the transition dipole moment can be viewed as an off-diagonal matrix element of the position operator, multiplied by the particle's charge. | 0 | Theoretical and Fundamental Chemistry |
Research on thyroid cancer has elucidated the theory that paracrine signaling may aid in creating tumor microenvironments. Chemokine transcription is upregulated when Ras is in the GTP-bound state. The chemokines are then released from the cell, free to bind to another nearby cell. Paracrine signaling between neighboring cells creates this positive feedback loop. Thus, the constitutive transcription of upregulated proteins form ideal environments for tumors to arise. Effectively, multiple bindings of ligands to the RTK receptors overstimulates the Ras-Raf-MAPK pathway, which overexpresses the mitogenic and invasive capacity of cells. | 1 | Applied and Interdisciplinary Chemistry |
Self-assembled monolayers (SAMs) are formed by chemisorbing reactive reagents with metal surfaces. A famous example involves thiols (RS-H) adsorbing onto the surface of gold. This process forms strong Au-SR bonds and releases H. The densely packed SR groups protect the surface. | 0 | Theoretical and Fundamental Chemistry |
Moureu was widely respected for his research work. As part of his research on acrylic acid and its derivatives, he was the first to synthesize acrylonitrile in 1893.
In addition, he studied acetylene compounds, phenolic compounds, plant essences, and rare gases found in wells and mines.
During the war, Moureu researched acrolein and sulfur mustard gas, working with his student Charles Dufraisse.
Acrolein was an extremely unstable compound, which tended to polymerize on contact with air. Already familiar with the preparation of acrolein, Moureu and Dufraisse were able to develop a way to stabilize it after carefully studying the processes by which it altered. Their work led to the use of acrolein and later benzyl iodide in weapons.
Their research also had great impact and long-lasting significance after the war. It was first published in the Bulletin of the Chemical Society of France in 1922.
The autoxidation reactions that Moureu and Dufraisse described occur spontaneously in most organic products in the presence of oxygen from the air and certain catalysts. Autoxidation affects virtually all living organisms. Moureu identified catalysts that could trigger such reactions, and other compounds that could slow or inhibit such reactions. He called the inhibitors "antioxygens", now known as "antioxidants".
Moureu is best known for this pioneering research. It has led to the use of antioxidants in the rubber and vegetable oil industries,
and to widespread applications in foods and medicines. Antioxidants are added to slow the spoiling of foods and the aging of rubber.
Moureu's work with sulfur mustard also became important after the war, as later researchers realized that some of the chemicals that were in mustard gas could be used as anti-cancer drugs, suppressing the division and proliferation of blood and bone marrow cells in leukaemia and lymphatic tumours.
With Adolphe Lepape, Moureu studied rare gases including krypton and xenon.
He developed methods for analyzing the gaseous components of mineral springs, and carried out comparative analyses of at least 108 springs. | 0 | Theoretical and Fundamental Chemistry |
If the crystal diffracts to high resolution (<1.2 Å), the initial phases can be estimated using direct methods. Direct methods can be used in x-ray crystallography, neutron crystallography, and electron crystallography.
A number of initial phases are tested and selected by this method. The other is the Patterson method, which directly determines the positions of heavy atoms. The Patterson function gives a large value in a position which corresponds to interatomic vectors. This method can be applied only when the crystal contains heavy atoms or when a significant fraction of the structure is already known.
For molecules whose crystals provide reflections in the sub-Ångström range, it is possible to determine phases by brute force methods, testing a series of phase values until spherical structures are observed in the resultant electron density map. This works because atoms have a characteristic structure when viewed in the sub-Ångström range. The technique is limited by processing power and data quality. For practical purposes, it is limited to "small molecules" and peptides because they consistently provide high-quality diffraction with very few reflections. | 0 | Theoretical and Fundamental Chemistry |
Long-distance athletes, such as marathon runners, cross-country skiers, and cyclists, often experience glycogen depletion, where almost all of the athlete's glycogen stores are depleted after long periods of exertion without sufficient carbohydrate consumption. This phenomenon is referred to as "hitting the wall" in running and "bonking" in cycling.
Glycogen depletion can be forestalled in three possible ways:
* First, during exercise, carbohydrates with the highest possible rate of conversion to blood glucose (high glycemic index) are ingested continuously. The best possible outcome of this strategy replaces about 35% of glucose consumed at heart rates above about 80% of maximum.
* Second, through endurance training adaptations and specialized regimens (e.g. fasting, low-intensity endurance training), the body can condition type I muscle fibers to improve both fuel use efficiency and workload capacity to increase the percentage of fatty acids used as fuel, sparing carbohydrate use from all sources.
* Third, by consuming large quantities of carbohydrates after depleting glycogen stores as a result of exercise or diet, the body can increase storage capacity of intramuscular glycogen stores. This process is known as carbohydrate loading. In general, glycemic index of carbohydrate source does not matter since muscular insulin sensitivity is increased as a result of temporary glycogen depletion.
When athletes ingest both carbohydrate and caffeine following exhaustive exercise, their glycogen stores tend to be replenished more rapidly; however, the minimum dose of caffeine at which there is a clinically significant effect on glycogen repletion has not been established. | 1 | Applied and Interdisciplinary Chemistry |
The hydraulic diameter, , is a commonly used term when handling flow in non-circular tubes and channels. Using this term, one can calculate many things in the same way as for a round tube. When the cross-section is uniform along the tube or channel length, it is defined as
where
: is the cross-sectional area of the flow,
: is the wetted perimeter of the cross-section.
More intuitively, the hydraulic diameter can be understood as a function of the hydraulic radius , which is defined as the cross-sectional area of the channel divided by the wetted perimeter. Here, the wetted perimeter includes all surfaces acted upon by shear stress from the fluid.
Note that for the case of a circular pipe,
The need for the hydraulic diameter arises due to the use of a single dimension in the case of a dimensionless quantity such as the Reynolds number, which prefers a single variable for flow analysis rather than the set of variables as listed in the table below. The Manning formula contains a quantity called the hydraulic radius. Despite what the name may suggest, the hydraulic diameter is not twice the hydraulic radius, but four times larger.
Hydraulic diameter is mainly used for calculations involving turbulent flow. Secondary flows can be observed in non-circular ducts as a result of turbulent shear stress in the turbulent flow. Hydraulic diameter is also used in calculation of heat transfer in internal-flow problems. | 1 | Applied and Interdisciplinary Chemistry |
In the study of plants' photorespiration, the labeling of atmosphere by oxygen-18 allows for the measurement of oxygen uptake by the photorespiration pathway. Labeling by gives the unidirectional flux of uptake, while there is a net photosynthetic evolution. It was demonstrated that, under preindustrial atmosphere, most plants reabsorb, by photorespiration, half of the oxygen produced by photosynthesis. Then, the yield of photosynthesis was halved by the presence of oxygen in atmosphere. | 0 | Theoretical and Fundamental Chemistry |
*Rutherford Memorial Medal (2009)
*OMCOS Award (2009)
*Sloan Research Fellowship (2008)
*Merck Process Award (2008)
*Eli Lilly Grantee (2007–2009)
*NSERC Discovery Accelerator Supplement Award (2007–2009)
*Amgen Young Investigator's Award (2007)
*Astra Zeneca Award for Chemistry (2007)
*University of Ottawa Research Chair in Novel Catalytic Transformations (2007–2012)
*Merck Process Research Award (2007)
*University of Ottawa Young Researcher of the Year (2006)
*Ichikizaki Travel Grant Award (2006)
*Boehringer Ingelheim Young Investigator Award in Organic Chemistry (2005)
*Cottrell Scholar Award (2005)
*Ichikizaki Travel Grant Award (2005)
*Premier's Research Excellence Award (2003)
*John C. Polanyi Award in Chemistry (2003) | 0 | Theoretical and Fundamental Chemistry |
Anthocyanins have been used in organic solar cells because of their ability to convert light energy into electrical energy. The many benefits to using dye-sensitized solar cells instead of traditional p-n junction silicon cells, include lower purity requirements and abundance of component materials, as well as the fact that they may be produced on flexible substrates, making them amenable to roll-to-roll printing processes. | 0 | Theoretical and Fundamental Chemistry |
Thomas Gilbert Henry Jones (1895–1970) was an Australian organic chemist and academic, notable for his pioneering work in the field of essential oils from Queensland flora natural products. | 0 | Theoretical and Fundamental Chemistry |
Pierre Sinaÿ's scientific work focuses on the chemistry of carbohydrates and the understanding of the role of oligosaccharides in the living world. In the mid-1970s, Pierre Sinaÿ discovered and developed an effective method for oligosaccharide synthesis known as imidate glycosylation. This, by now allowing access to increasingly complex carbohydrate structures, is not unrelated to the development of glycobiology, the aim of which is to decode the meaning of this third alphabet of saccharides, which is in addition to that of proteins and nucleic acids. He synthesized the antigenic determinants of substances in human blood groups and then synthesized a complexly structured pentasaccharide representing the active site of heparin responsible for its antithrombotic effect. This last achievement demonstrates for the first time, without any ambiguity, the molecular basis of such an activity, commonly used in hospital medicine. This breakthrough in glyco-chemistry has led to the concept of conformational flexibility, which is crucial in heparinology. First materialized by the use of nuclear magnetic resonance, this concept was studied in detail using the chemical synthesis of constrained sugars adopting unconventional conformations. Pierre Sinaÿ has also discovered and developed a whole series of conceptually new reactions. Selective examples include the synthesis of spiroorthoesters by using selenium chemistry, the development of organometallic chemistry of anomeric carbon, the pioneering synthesis of C-disaccharides, electrochemical glycosylation and, more recently, a novel functionalization of cyclodextrins through a kind of molecular microsurgery in which aluminium derivatives are said to be the scalpel. For the first time, the existence of the glycosyl cation, an intermediate conventionally postulated during glycosylation reactions, could be formally demonstrated through chemistry in a superacid environment. A 4-volume book covers many aspects of carbohydrate chemistry and biology. | 0 | Theoretical and Fundamental Chemistry |
Distribution of stop codons within the genome of an organism is non-random and can correlate with GC-content. For example, the E. coli K-12 genome contains 2705 TAA (63%), 1257 TGA (29%), and 326 TAG (8%) stop codons (GC content 50.8%). Also the substrates for the stop codons release factor 1 or release factor 2 are strongly correlated to the abundance of stop codons. Large scale study of bacteria with a broad range of GC-contents shows that while the frequency of occurrence of TAA is negatively correlated to the GC-content and the frequency of occurrence of TGA is positively correlated to the GC-content, the frequency of occurrence of the TAG stop codon, which is often the minimally used stop codon in a genome, is not influenced by the GC-content. | 1 | Applied and Interdisciplinary Chemistry |
Tyres, sometimes called riding rings, usually consist of a single annular steel casting, machined to a smooth cylindrical surface, which attach loosely to the kiln shell through a variety of "chair" arrangements. These require some ingenuity of design, since the tyre must fit the shell snugly, but also allow thermal movement. The tyre rides on pairs of steel rollers, also machined to a smooth cylindrical surface, and set about half a kiln-diameter apart. The rollers must support the kiln, and allow rotation that is as nearly frictionless as possible. A well-engineered kiln, when the power is cut off, will swing pendulum-like many times before coming to rest. The mass of a typical 6 x 60 m kiln, including refractories and feed, is around 1100 tonnes, and would be carried on three tyres and sets of rollers, spaced along the length of the kiln. The longest kilns may have 8 sets of rollers, while very short and small kilns may have none. Kilns usually rotate at 0.5 to 2 rpm. The Kilns of modern cement plants are running at 4 to 5 rpm. The bearings of the rollers must be capable of withstanding the large static and live loads involved and must be carefully protected from the heat of the kiln and the ingress of dust. Since the kiln is at an angle, it also needs support to prevent it from walking off the support rollers. Usually upper and lower "retaining (or thrust) rollers" bearing against the side of tyres prevent the kiln from walking off the support rollers. | 1 | Applied and Interdisciplinary Chemistry |
Hahn and Strassmann isolated the three radium isotopes (verified by their half-lives) and used fractional crystallisation to separate it from its barium carrier by adding barium bromide crystals in four steps. Since radium precipitates preferentially in a solution of barium bromide, at each step the fraction drawn off would contain less radium than the one before. However, they found no difference between each of the fractions. In case their process was faulty in some way, they verified it with known isotopes of radium; the process was fine. On 19 December, Hahn wrote to Meitner, informing her that the radium isotopes behaved chemically like barium. Anxious to finish up before the Christmas break, Hahn and Strassmann submitted their findings to Naturwissenschaften on 22 December without waiting for Meitner to reply. Hahn concluded the paper with: "As chemists... we should substitute the symbols Ba, La, Ce for Ra, Ac, Th. As nuclear chemists fairly close to physics we cannot yet bring ourselves to take this step which contradicts all previous experience in physics."
Frisch normally celebrated Christmas with Meitner in Berlin, but in 1938 she accepted an invitation from Eva von Bahr to spend it with her family at Kungälv, and Meitner asked Frisch to join her there. Meitner received the letter from Hahn describing his chemical proof that some of the product of the bombardment of uranium with neutrons was barium. Barium had an atomic mass 40% less than uranium, and no previously known methods of radioactive decay could account for such a large difference in the mass of the nucleus. Nonetheless, she had immediately written back to Hahn to say: "At the moment the assumption of such a thoroughgoing breakup seems very difficult to me, but in nuclear physics we have experienced so many surprises, that one cannot unconditionally say: It is impossible."
According to Frisch:
Meitner and Frisch had correctly interpreted Hahns results to mean that the nucleus of uranium had split roughly in half. The first two reactions that the Berlin group had observed were light elements created by the breakup of uranium nuclei; the third, the 23-minute one, was a decay into the real element 93. On returning to Copenhagen, Frisch informed Bohr, who slapped his forehead and exclaimed "What idiots we have been!" Bohr promised not to say anything until they had a paper ready for publication. To speed the process, they decided to submit a one-page note to Nature'. At this point, the only evidence that they had was the barium. Logically, if barium was formed, the other element must be krypton, although Hahn mistakenly believed that the atomic masses had to add up to 239 rather than the atomic numbers adding up to 92, and thought it was masurium (technetium), and so did not check for it:
: + n → + + some n
Over a series of long-distance phone calls, Meitner and Frisch came up with a simple experiment to bolster their claim: to measure the recoil of the fission fragments, using a Geiger counter with the threshold set above that of the alpha particles. Frisch conducted the experiment on 13 January, and found the pulses caused by the reaction just as they had predicted. He decided he needed a name for the newly discovered nuclear process. He spoke to William A. Arnold, an American biologist working with de Hevesy, and asked him what biologists called the process by which living cells divided into two cells. Arnold told him that biologists called it fission. Frisch then applied that name to the nuclear process in his paper. Frisch mailed both papers to Nature on 16 January; the jointly-authored note appeared in print on 11 February and Frisch's paper on recoil on 18 February.
These three reports, the first Hahn-Strassmann publications of 6 January and 10 February 1939, and the Frisch-Meitner publication of 11 February 1939, had electrifying effects on the scientific community. In 1940 Frisch and Rudolf Peierls produced the Frisch–Peierls memorandum, which established that an atomic explosion could be generated. | 1 | Applied and Interdisciplinary Chemistry |
Biodiesel is a diesel fuel derived from animal or plant lipids (oils and fats). Studies have shown that some species of algae can produce 60% or more of their dry weight in the form of oil. Because the cells grow in aqueous suspension, where they have more efficient access to water, and dissolved nutrients, microalgae are capable of producing large amounts of biomass and usable oil in either high rate algal ponds or photobioreactors. This oil can then be turned into biodiesel which could be sold for use in automobiles. Regional production of microalgae and processing into biofuels will provide economic benefits to rural communities.
As they do not have to produce structural compounds such as cellulose for leaves, stems, or roots, and because they can be grown floating in a rich nutritional medium, microalgae can have faster growth rates than terrestrial crops. Also, they can convert a much higher fraction of their biomass to oil than conventional crops, e.g. 60% versus 2-3% for soybeans. The per unit area yield of oil from algae is estimated to be from 58,700 to 136,900 L/ha/year, depending on lipid content, which is 10 to 23 times as high as the next highest yielding crop, oil palm, at 5 950 L/ha/year.
The U.S. Department of Energy's Aquatic Species Program, 1978–1996, focused on biodiesel from microalgae. The final report suggested that biodiesel could be the only viable method by which to produce enough fuel to replace current world diesel usage. If algae-derived biodiesel were to replace the annual global production of 1.1bn tons of conventional diesel then a land mass of 57.3 million hectares would be required, which would be highly favorable compared to other biofuels. | 1 | Applied and Interdisciplinary Chemistry |
The usual definition of a splash zone is the area just above and just below the average water level of a body of water. It also includes areas that may be subject to water spray and mist.
A significant amount of corrosion of fences is due to landscaper tools scratching fence coatings and irrigation sprinklers spraying these damaged fences. Recycled water typically has a higher salt content than potable drinking water, meaning that it is more corrosive than regular tap water. The same risk from damage and water spray exists for above ground piping and backflow preventers. Fiberglass covers, cages, and concrete footings have worked well to keep tools at an arms length. Even the location where a roof drain splashes down can matter. Drainage from a homes roof valley can fall directly down onto a gas meter causing its piping to corrode at an accelerated rate reaching 50% wall thickness within 4 years. It is the same effect as a splash zone in the ocean, or in a pool with lot of oxygen and agitation that removes material as it corrodes.
Tanks or structural tubing such as bench seat supports or amusement park rides can accumulate water and moisture if the structure does not allow for drainage. This humid environment can then lead to internal corrosion of the structure affecting the structural integrity. The same can happen in tropical environments leading to external corrosion. This would include Corrosion in ballast tanks on ships. | 1 | Applied and Interdisciplinary Chemistry |
The Systems Biology Pathway Exchange (SBPAX) allows SBO terms to be added to Biological Pathway Exchange (BioPAX). This links BioPAX to information useful for modelling, especially by adding quantitative descriptions described by SBO. | 1 | Applied and Interdisciplinary Chemistry |
Mesophillic Thermoproteota were recently placed into a new phylum of Archaea called the Nitrososphaerota (formerly Thaumarchaeota). However there are very few molecular markers that can distinguish this group of archaea from the phylum Thermoproteota (formerly Crenarchaeota). A detailed phylogenetic study using the CSI approach was conducted to distinguish these phyla in molecular terms. 6 CSIs were uniquely found in various Nitrososphaerota, namely Cenarchaeum symbiosum, Nitrosopumilus maritimus and a number of uncultured marine Thermoproteota. 3 CSIs were found that were commonly shared between species belonging to Nitrososphaerota and Thermoproteota. Additionally, a number of CSIs were found that are specific for different orders of Thermoproteota—3 CSIs for Sulfolobales, 5 CSIs for Thermoproteales, lastly 2 CSIs common for Sulfolobales and Desulfurococcales. The signatures described provide novel means for distinguishing Thermoproteota and Nitrososphaerota, additionally they could be used as a tool for the classification and identification of related species. | 1 | Applied and Interdisciplinary Chemistry |
Aqueous zinc chloride reacts with zinc oxide to form an amorphous cement that was first investigated in 1855 by Stanislas Sorel. Sorel later went on to investigate the related magnesium oxychloride cement, which bears his name. | 0 | Theoretical and Fundamental Chemistry |
The time-of-flight principle can be applied for mass spectrometry. Ions are accelerated by an electric field of known strength. This acceleration results in an ion having the same kinetic energy as any other ion that has the same charge. The velocity of the ion depends on the mass-to-charge ratio. The time that it subsequently takes for the particle to reach a detector at a known distance is measured. This time will depend on the mass-to-charge ratio of the particle (heavier particles reach lower speeds). From this time and the known experimental parameters one can find the mass-to-charge ratio of the ion. The elapsed time from the instant a particle leaves a source to the instant it reaches a detector. | 0 | Theoretical and Fundamental Chemistry |
Vaporization (from liquid to gas) is divided into two types: vaporization on the surface of the liquid is called evaporation, and vaporization at the boiling point with formation of bubbles in the interior of the liquid is called boiling. However there is no such distinction for the solid-to-gas transition, which is always called sublimation in both corresponding cases. | 0 | Theoretical and Fundamental Chemistry |
The chemical garden relies on most transition metal silicates being insoluble in water and colored.
When a metal salt, such as cobalt chloride, is added to a sodium silicate solution, it will start to dissolve. It will then form insoluble cobalt silicate by a double displacement reaction. This cobalt silicate is a semipermeable membrane. Because the ionic strength of the cobalt solution inside the membrane is higher than the sodium silicate solution's, which forms the bulk of the tank contents, osmotic effects will increase the pressure within the membrane. This will cause the membrane to tear, forming a hole. The cobalt cations will react with the silicate anions at this tear to form a new solid. In this way, growths will form in the tanks; they will be colored (according to the metal cation) and may look like plant-like structures.
The usual upward direction of growth depends on the density of the fluid inside the semi-permeable membrane of the "plant" being lower than that of the surrounding waterglass solution. If one uses a metal salt that produces a very dense fluid inside the membrane, the growth is downward. For example, a green solution of trivalent chromium sulfate or chloride refuses to crystallize without slowly changing into the violet form, even if boiled until it concentrates into a tarry mass. That tar, if suspended in the waterglass solution, forms downward twig-like growths. This is because all the fluid inside the membrane is too dense to float and thereby exerts a downward force. The concentration of sodium silicate becomes important in growth rate.
After the growth has ceased, the sodium silicate solution can be removed by a continuous addition of water at a very slow rate. This prolongs the life of the garden.
In one specific experimental variation, researchers produced the chemical garden with a single growth "tube". | 1 | Applied and Interdisciplinary Chemistry |
By the outbreak of World War I in 1914, Bayer was facing competition in all its major markets from local ASA producers as well as other German drug firms (particularly Heyden and Hoechst). The British market was immediately closed to the German companies, but British manufacturing could not meet the demand—especially with phenol supplies, necessary for ASA synthesis, largely being used for explosives manufacture. On 5 February 1915, Bayers UK trademarks were voided, so that any company could use the term aspirin. The Australian market was taken over by Aspro, after the makers of Nicholas-Aspirin lost a short-lived exclusive right to the aspirin' name there. In the United States, Bayer was still under German control—though the war disrupted the links between the American Bayer plant and the German Bayer headquarters—but phenol shortage threatened to reduce aspirin production to a trickle, and imports across the Atlantic Ocean were blocked by the Royal Navy. | 1 | Applied and Interdisciplinary Chemistry |
Firstly, Ca-looping offers greater cost advantage compared to conventional amine-scrubbing technologies. The cost/metric ton for CO captured through Ca-looping is ~$23.70 whereas that for CO captured through amine scrubbing is about $35–$96. This can be attributed to the high availability and low cost of the CaO sorbent (derived from limestone) as compared to MEA. Also, Ca-looping imposes a lower energy penalty than amine scrubbing, resulting in lower energy costs. The amine scrubbing process is energy intensive, with approximately 67% of the operating costs going into steam requirements for solvent regeneration. A more detailed comparison of Ca-looping and amine scrubbing is shown below. | 1 | Applied and Interdisciplinary Chemistry |
Ella Jones (born 1955) is an American chromatographer, pastor, and politician who serves as the 12th mayor of Ferguson, Missouri. A former member of the Ferguson City Council, Jones is the first African-American and woman elected mayor of the city. | 0 | Theoretical and Fundamental Chemistry |
In context of x-rays, opacifiers are additives with high absorption of x-rays; typically these are particles or compounds of lead, barium (often barium sulfate), tungsten, or other high atomic weight elements. Sometimes opacifiers are added to medical implants to make them visible under X-ray imaging. This is especially true in the case of most polymers which are often unrecognizable in the body when viewed using X-rays. | 0 | Theoretical and Fundamental Chemistry |
Rosenthal's reagent can be prepared by reduction of titanocene or zirconocene dichloride with magnesium in the presence of bis(trimethylsilyl)acetylene in THF. The illustrated product for a titanocene complex can be represented by the resonance structures A and B. If zirconium is used as central atom, additional ligands (e.g. pyridine) are necessary for stabilization. | 0 | Theoretical and Fundamental Chemistry |
The common trend in all examples of protein adsorption in the food industry is that of adsorption to minerals adsorbed to the surface first. This phenomenon has been studied but it is not well understood. Spectroscopy of proteins adsorbed onto clay-like minerals show variations in the C=O and N-H bond stretches, meaning that these bonds are involved in the protein binding. | 1 | Applied and Interdisciplinary Chemistry |
Bolaamphiphiles (also known as bolaform surfactants,
bolaphiles, or alpha-omega-type surfactants) are amphiphilic molecules that have hydrophilic groups at both ends of a sufficiently long hydrophobic hydrocarbon chain. Compared to single-headed amphiphiles, the introduction of a second head-group generally induces a higher solubility in water, an increase in the critical micelle concentration (cmc), and a decrease in aggregation number. The aggregate morphologies of bolaamphiphiles include spheres, cylinders, disks, and vesicles. Bolaamphiphiles are also known to form helical structures that can form monolayer microtubular self-assemblies. | 0 | Theoretical and Fundamental Chemistry |
In aircraft (other than lighter-than-air balloons and blimps), the added mass is not usually taken into account because the density of the air is so small. | 1 | Applied and Interdisciplinary Chemistry |
Diphenylamine is an organic compound with the formula (CH)NH. The compound is a derivative of aniline, consisting of an amine bound to two phenyl groups. The compound is a colorless solid, but commercial samples are often yellow due to oxidized impurities. Diphenylamine dissolves well in many common organic solvents, and is moderately soluble in water. It is used mainly for its antioxidant properties. Diphenylamine is widely used as an industrial antioxidant, dye mordant and reagent and is also employed in agriculture as a fungicide and antihelmintic. | 0 | Theoretical and Fundamental Chemistry |
Nahal Mishmar (Hebrew:נחל משמר) or Wadi Mahras (Arabic:مَحْرَس) is a small seasonal stream in the Judean Desert in Israel. A hoard of rare Chalcolithic artifacts (the Nahal Mishmar hoard) was discovered in a cave near the stream bed which was dubbed the "Treasure Cave". | 1 | Applied and Interdisciplinary Chemistry |
The process for developing a pharmacophore model generally involves the following steps:
# Select a training set of ligands – Choose a structurally diverse set of molecules that will be used for developing the pharmacophore model. As a pharmacophore model should be able to discriminate between molecules with and without bioactivity, the set of molecules should include both active and inactive compounds.
# Conformational analysis – Generate a set of low energy conformations that is likely to contain the bioactive conformation for each of the selected molecules.
#Molecular superimposition – Superimpose ("fit") all combinations of the low-energy conformations of the molecules. Similar (bioisosteric) functional groups common to all molecules in the set might be fitted (e.g., phenyl rings or carboxylic acid groups). The set of conformations (one conformation from each active molecule) that results in the best fit is presumed to be the active conformation.
#Abstraction – Transform the superimposed molecules into an abstract representation. For example, superimposed phenyl rings might be referred to more conceptually as an aromatic ring pharmacophore element. Likewise, hydroxy groups could be designated as a hydrogen-bond donor/acceptor pharmacophore element.
# Validation – A pharmacophore model is a hypothesis accounting for the observed biological activities of a set of molecules that bind to a common biological target. The model is only valid insofar as it is able to account for differences in biological activity of a range of molecules.
As the biological activities of new molecules become available, the pharmacophore model can be updated to further refine it. | 1 | Applied and Interdisciplinary Chemistry |
Micro RNAs are involved in regulating the expression of many proteins. Med1 is targeted by miR-1, which is important in gene regulation in cancers. The tumor suppressor miR-137 also regulates MED1. | 1 | Applied and Interdisciplinary Chemistry |
As reagents in organic chemistry, organocerium compounds are typically prepared in situ by treatment of cerium trichloride with organolithium or Grignard reagent. Reagents are derived from alkyl, alkynyl, and alkenyl organometallic reagents as well as enolates have been described. The most common cerium source for this purpose is cerium (III) chloride, which can be obtained in anhydrous form via dehydration of the commercially available heptahydrate. Precomplexation with tetrahydrofuran is important for the success of the transmetallation, with most procedures involving "vigorous stirring for a period of no less than 2 hours". The structures depicted (as below) for organocerium reagent, however are highly simplified.
These reagents add 1,2 to conjugated ketones and aldehydes. This preference for direct addition is attributed to the oxophilicity of the cerium reagent, which activates the carbonyl for nucleophilic attack. | 0 | Theoretical and Fundamental Chemistry |
*PSMA1 NM_002786
*PSMA2 NM_002787
*PSMA3 NM_002788
*PSMA4 NM_002789
*PSMA5 NM_002790
*PSMA6 NM_002791
*PSMA7 NM_002792 Homo sapiens proteasome (prosome, macropain) subunit, alpha type, 7 (PSMA7),
*PSMB1 NM_002793 Homo sapiens proteasome (prosome, macropain) subunit, beta type, 1 (PSMB1), mRNA
*PSMB2 NM_002794 Homo sapiens proteasome (prosome, macropain) subunit, beta type, 2 (PSMB2), mRNA
*PSMB3 NM_002795
*PSMB4 NM_002796 Homo sapiens proteasome (prosome, macropain) subunit, beta type, 4 (PSMB4), mRNA
*PSMB5 NM_002797
*PSMB6 NM_002798
*PSMB7 NM_002799 Homo sapiens proteasome (prosome, macropain) subunit, beta type, 7 (PSMB7), mRNA
*PSMC2 NM_002803
*PSMC3 NM_002804
*PSMC4 NM_006503
*PSMC5 NM_002805
*PSMC6 NM_002806
*PSMD1 NM_002807
*PSMD10 NM_002814
*PSMD11 NM_002815 Homo sapiens proteasome (prosome, macropain) 26S subunit, non-ATPase, 11
*PSMD12 NM_002816
*PSMD13 NM_002817
*PSMD14 NM_005805
*PSMD2 NM_002808
*PSMD3 NM_002809
*PSMD4 NM_002810
*PSMD5 NM_005047
*PSMD6 NM_014814
*PSMD7 NM_002811
*PSMD8 NM_002812 Homo sapiens proteasome (prosome, macropain) 26S subunit, non-ATPase, 8 (PSMD8),
*PSMD9 NM_002813
*PSME2 NM_002818 Homo sapiens proteasome (prosome, macropain) activator subunit 2 (PA28 beta)
*PSME3 NM_005789
*PSMF1 NM_006814
*PSMG2 NM_020232
*PSMG3 NM_032302
*PSMG4 NM_001128591
*UBA1 NM_003334 Homo sapiens ubiquitin-activating enzyme E1 (A1S9T and BN75 temperature
*UBA2 NM_005499
*UBA3 NM_003968
*UBA5 NM_024818
*UBA52 NM_003333
*UBAC2 NM_177967
*UBALD1 NM_145253
*UBAP1 NM_016525
*UBAP2L NM_014847
*UBB NM_018955 Homo sapiens ubiquitin B (UBB), mRNA
*UBC NM_021009 Homo sapiens ubiquitin C (UBC), mRNA
*UBE2A NM_003336
*UBE2B NM_003337
*UBE2D2 NM_003339 Homo sapiens ubiquitin-conjugating enzyme E2D 2 (UBC4/5 homolog, yeast)
*UBE2D3 NM_003340
*UBE2D4 NM_015983
*UBE2E1 NM_003341
*UBE2E2 NM_152653
*UBE2E3 NM_006357
*UBE2F NM_080678
*UBE2G2 NM_003343
*UBE2H NM_003344
*UBE2I NM_003345 Homo sapiens ubiquitin-conjugating enzyme E2I (UBC9 homolog, yeast) (UBE2I),
*UBE2J1 NM_016021
*UBE2J2 NM_058167
*UBE2K NM_005339
*UBE2L3 NM_003347
*UBE2M NM_003969 Homo sapiens ubiquitin-conjugating enzyme E2M (UBC12 homolog, yeast) (UBE2M),
*UBE2N NM_003348
*UBE2NL NM_001012989
*UBE2Q1 NM_017582
*UBE2R2 NM_017811
*UBE2V1 NM_021988
*UBE2V2 NM_003350
*UBE2W NM_018299
*UBE2Z NM_023079
*UBE3A NM_000462
*UBE3B NM_130466
*UBE3C NM_014671
*UBE4A NM_004788
*UBE4B NM_006048
*USP10 NM_005153
*USP14 NM_005151
*USP16 NM_006447
*USP19 NM_006677
*USP22 NM_015276
*USP25 NM_013396
*USP27X NM_001145073
*USP33 NM_015017
*USP38 NM_032557
*USP39 NM_006590
*USP4 NM_003363
*USP47 NM_017944
*USP5 NM_003481
*USP7 NM_003470
*USP8 NM_005154
*USP9X NM_001039590 | 1 | Applied and Interdisciplinary Chemistry |
Müllerian mimicry was proposed by the German zoologist and naturalist Fritz Müller (1821–1897). An early proponent of evolution, Müller offered the first explanation for resemblance between certain butterflies that had puzzled the English naturalist Henry Walter Bates in 1862. Bates, like Müller, spent a significant part of his life in Brazil, as described in his book The Naturalist on the River Amazons. Bates conjectured that these abundant and distasteful butterflies might have been caused to resemble each other by their physical environment. Müller had also seen these butterflies first hand, and like Bates had collected specimens, and he proposed a variety of other explanations. One was sexual selection, namely that individuals would choose to mate with partners with frequently-seen coloration, such as those resembling other species. However, if as is usual, females are the choosers, then mimicry would be seen in males, but in sexually dimorphic species, females are more often mimetic. Another was, as Müller wrote in 1878, that "defended species may evolve a similar appearance so as to share the costs of predator education." | 1 | Applied and Interdisciplinary Chemistry |
A river siphon occurs when part of the water flow passes under a submerged object like a rock or tree trunk. The water flowing under the obstruction can be very powerful, and as such can be very dangerous for kayaking, canyoning, and other river-based watersports. | 1 | Applied and Interdisciplinary Chemistry |
Cells are very sensitive to nanotopographical features, so optimization of surfaces in tissue engineering has pushed towards implantation. Under appropriate conditions, a carefully crafted 3-dimensional scaffold is used to direct cell seeds toward artificial organ growth. The 3-D scaffold incorporates various nanoscale factors that control the environment for optimal and appropriate functionality. The scaffold is an analog of the in vivo extracellular matrix in vitro, allowing for successful artificial organ growth by providing the necessary, complex biological factors in vitro. | 0 | Theoretical and Fundamental Chemistry |
Bottromycins contain a C-terminal decarboxylated thiazole in addition to a macrocyclic amidine.
There are currently six known bottromycin compounds, which differ in the extent of side chain methylation, an additional characteristic of the bottromycin class. The total synthesis of bottromycin A2 was required to definitively determine the structure of the first bottromycin.
Thus far, gene clusters predicted to produce bottromycins have been identified in the genus Streptomyces. Bottromycins differ from other RiPPs in that there is no N-terminal leader peptide. Rather, the precursor peptide has a C-terminal extension of 35-37 amino acids, hypothesized to act as a recognition sequence for posttranslational machinery. | 1 | Applied and Interdisciplinary Chemistry |
Yttrium is found in most rare-earth minerals, it is found in some uranium ores, but is never found in the Earths crust as a free element. About 31 ppm of the Earths crust is yttrium, making it the 43rd most abundant element. Yttrium is found in soil in concentrations between 10 and 150 ppm (dry weight average of 23 ppm) and in sea water at 9 ppt. Lunar rock samples collected during the American Apollo Project have a relatively high content of yttrium.
Yttrium has no known biological role, though it is found in most, if not all, organisms and tends to concentrate in the liver, kidney, spleen, lungs, and bones of humans. Normally, as little as is found in the entire human body; human breast milk contains 4 ppm. Yttrium can be found in edible plants in concentrations between 20 ppm and 100 ppm (fresh weight), with cabbage having the largest amount. With as much as 700 ppm, the seeds of woody plants have the highest known concentrations.
there are reports of the discovery of very large reserves of rare-earth elements in the deep seabed several hundred kilometers from the tiny Japanese island of Minami-Torishima Island, also known as Marcus Island. This location is described as having "tremendous potential" for rare-earth elements and yttrium (REY), according to a study published in Scientific Reports. "This REY-rich mud has great potential as a rare-earth metal resource because of the enormous amount available and its advantageous mineralogical features," the study reads. The study shows that more than of rare-earth elements could be "exploited in the near future." As well as yttrium (Y), which is used in products like camera lenses and mobile phone screens, the rare-earth elements found are europium (Eu), terbium (Tb), and dysprosium (Dy). | 1 | Applied and Interdisciplinary Chemistry |
Light alone does not rapidly degrade methyl violet, but the process is accelerated upon the addition of large band-gap semiconductors, TiO or ZnO. | 0 | Theoretical and Fundamental Chemistry |
Copper is almost non-existent for most of the interior of East Africa, with a few exceptions particularly Kilwa and medieval sites in Nubia and Fostat, and there is not enough information yet to reconstruct copper on the Swahili Coast. | 1 | Applied and Interdisciplinary Chemistry |
Although this page is devoted to genes that should be ubiquitously expressed, this section is for genes whose current name reflects their relative upregulation in testes
*SPAG7
*SRM Spermidine synthase
*TEGT Bax-1 inhibitor
*DAZAP2 Deleted in azoospermia
*MEA1 Male enhanced antigen | 1 | Applied and Interdisciplinary Chemistry |
Beevers–Lipson strips were a computational aid for early crystallographers in calculating Fourier transforms to determine the structure of crystals from crystallographic data, enabling the creation of models for complex molecules. They were used from the 1930s until computers with enough power became generally available in the 1960s.
The technique was developed by C. Arnold Beevers (1908–2001), reader in crystallography at the University of Edinburgh, and Henry Lipson CBE FRS (1910–1991), Professor of Physics at the University of Manchester Institute of Science and Technology. The approach converted the sizable calculations of multi-dimensional Fourier summations needed in crystallography analysis into sums of more manageable one-dimensional values. The folded card strips with numbers were typically stored in two wooden boxes, one for sines and one for cosines. Previously it was necessary to consult sine/cosine tables, a time-consuming process. The approach was used by the Nobel Prize winner Dorothy Hodgkin OM FRS (1910–1994). The technique is still used in modern computer programs. | 1 | Applied and Interdisciplinary Chemistry |
Thymidine monophosphate (TMP), also known as thymidylic acid (conjugate base thymidylate), deoxythymidine monophosphate (dTMP), or deoxythymidylic acid (conjugate base deoxythymidylate), is a nucleotide that is used as a monomer in DNA. It is an ester of phosphoric acid with the nucleoside thymidine. dTMP consists of a phosphate group, the pentose sugar deoxyribose, and the nucleobase thymine. Unlike the other deoxyribonucleotides, thymidine monophosphate often does not contain the "deoxy" prefix in its name; nevertheless, its symbol often includes a "d" ("dTMP"). Dorland’s Illustrated Medical Dictionary provides an explanation of the nomenclature variation at its entry for thymidine.
As a substituent, it is called by the prefix thymidylyl-. | 0 | Theoretical and Fundamental Chemistry |
The affinity of an antagonist for its binding site (K), i.e. its ability to bind to a receptor, will determine the duration of inhibition of agonist activity. The affinity of an antagonist can be determined experimentally using Schild regression or for competitive antagonists in radioligand binding studies using the Cheng-Prusoff equation. Schild regression can be used to determine the nature of antagonism as beginning either competitive or non-competitive and K determination is independent of the affinity, efficacy or concentration of the agonist used. However, it is important that equilibrium has been reached. The effects of receptor desensitization on reaching equilibrium must also be taken into account. The affinity constant of antagonists exhibiting two or more effects, such as in competitive neuromuscular-blocking agents that also block ion channels as well as antagonising agonist binding, cannot be analyzed using Schild regression. Schild regression involves comparing the change in the dose ratio, the ratio of the EC of an agonist alone compared to the EC in the presence of a competitive antagonist as determined on a dose response curve. Altering the amount of antagonist used in the assay can alter the dose ratio. In Schild regression, a plot is made of the log (dose ratio-1) versus the log concentration of antagonist for a range of antagonist concentrations. The affinity or K is where the line cuts the x-axis on the regression plot. Whereas, with Schild regression, antagonist concentration is varied in experiments used to derive K values from the Cheng-Prusoff equation, agonist concentrations are varied. Affinity for competitive agonists and antagonists is related by the Cheng-Prusoff factor used to calculate the K (affinity constant for an antagonist) from the shift in IC that occurs during competitive inhibition. The Cheng-Prusoff factor takes into account the effect of altering agonist concentration and agonist affinity for the receptor on inhibition produced by competitive antagonists. | 1 | Applied and Interdisciplinary Chemistry |
Keller's reagent can refer to either of two different mixtures of acids.
In metallurgy, Keller's reagent is a mixture of nitric acid, hydrochloric acid, and hydrofluoric acid, used to etch aluminum alloys to reveal their grain boundaries and orientations. It is also sometimes called Dix–Keller reagent, after E. H. Dix, Jr., and Fred Keller of the Aluminum Corporation of America, who pioneered the use of this technique in the late 1920s and early 1930s.
In organic chemistry, Kellers reagent is a mixture of anhydrous (glacial) acetic acid, concentrated sulfuric acid, and small amounts of ferric chloride, used to detect alkaloids. Kellers reagent can also be used to detect other kinds of alkaloids via reactions in which it produces products with a wide range of colors. Cohn describes its use to detect the principal components of digitalis. The reaction with this reagent is also known as the Keller–Kiliani reaction, after C. C. Keller and H. Kiliani, who both used it to study digitalis in the late 19th century. | 0 | Theoretical and Fundamental Chemistry |
* Liquid–liquid extraction
** Acid-base extraction
** Supercritical fluid extraction
* Solid-liquid extraction
** Solid-phase extraction
** Maceration
** Ultrasound-assisted extraction
** Microwave-assisted extraction
** Heat reflux extraction
** Instant controlled pressure drop extraction (Détente instantanée contrôlée)
* Perstraction | 0 | Theoretical and Fundamental Chemistry |
Another way to find the capillary length is using different pressure points inside a sessile droplet, with each point having a radius of curvature, and equate them to the Laplace pressure equation. This time the equation is solved for the height of the meniscus level which again can be used to give the capillary length.
The shape of a sessile droplet is directly proportional to whether the radius is greater than or less than the capillary length. Microdrops are droplets with radius smaller than the capillary length, and their shape is governed solely by surface tension, forming a spherical cap shape. If a droplet has a radius larger than the capillary length, they are known as macrodrops and the gravitational forces will dominate. Macrodrops will be flattened by gravity and the height of the droplet will be reduced. | 1 | Applied and Interdisciplinary Chemistry |
Aldol reactions may proceed by two distinct mechanisms. Carbonyl compounds, such as aldehydes and ketones, can be converted to enols or enol ethers. These species, being nucleophilic at the α-carbon, can attack especially reactive protonated carbonyls such as protonated aldehydes. This is the enol mechanism. Carbonyl compounds, being carbon acids, can also be deprotonated to form enolates, which are much more nucleophilic than enols or enol ethers and can attack electrophiles directly. The usual electrophile is an aldehyde, since ketones are much less reactive. This is the enolate mechanism.
Despite the attractiveness of the aldol manifold, there are several problems that need to be addressed to render the process catalytic and effective. The first problem is a thermodynamic one: most aldol reactions are reversible. Furthermore, the equilibrium is also just barely on the side of the products in the case of simple aldehyde–ketone aldol reactions. If the conditions are particularly harsh (e.g.: NaOMe/MeOH/reflux), condensation may occur. However if an Aldol addition is desired, this can usually be avoided with mild reagents and low temperatures (e.g., LDA (a strong base), THF, −78 °C). Although aldol addition usually proceeds to near completion under irreversible conditions, the isolated aldol adducts are sensitive to base-induced retro-aldol cleavage to return starting materials. In contrast, retro-aldol condensations are rare, but possible. This is the basis of the catalytic strategy of class I aldolases in nature, as well as numerous small-molecule amine catalysts. | 0 | Theoretical and Fundamental Chemistry |
Researchers at BI discovered that using a buty-2-nyl group resulted in a potent candidate, called BI-1356 (Figure 10). In 2008 BI-1356 was undergoing phase III clinical trials; it was released as linagliptin in May 2011. X-ray crystallography has shown that that xanthine type binds the DPP-4 complex in a different way than other inhibitors:
1. The amino group also interacts with the Glu205, Glu206 and Tyr662
2. The buty-2-nyl group occupies the S1-pocket
3. The uracil group undergoes a π-stacking interaction with the Tyr547 residue
4. The quinazoline group undergoes a π-stacking interaction with the Trp629 residue | 1 | Applied and Interdisciplinary Chemistry |
Cold fusion researchers were for many years unable to get papers accepted at scientific meetings, prompting the creation of their own conferences. The International Conference on Cold Fusion (ICCF) was first held in 1990 and has met every 12 to 18 months since. Attendees at some of the early conferences were described as offering no criticism to papers and presentations for fear of giving ammunition to external critics, thus allowing the proliferation of crackpots and hampering the conduct of serious science. Critics and skeptics stopped attending these conferences, with the notable exception of Douglas Morrison, who died in 2001. With the founding in 2004 of the International Society for Condensed Matter Nuclear Science (ISCMNS), the conference was renamed the International Conference on Condensed Matter Nuclear Science—for reasons that are detailed in the subsequent research section above—but reverted to the old name in 2008. Cold fusion research is often referenced by proponents as "low-energy nuclear reactions", or LENR, but according to sociologist Bart Simon the "cold fusion" label continues to serve a social function in creating a collective identity for the field.
Since 2006, the American Physical Society (APS) has included cold fusion sessions at their semiannual meetings, clarifying that this does not imply a softening of skepticism. Since 2007, the American Chemical Society (ACS) meetings also include "invited symposium(s)" on cold fusion. An ACS program chair, Gopal Coimbatore, said that without a proper forum the matter would never be discussed and, "with the world facing an energy crisis, it is worth exploring all possibilities."
On 22–25 March 2009, the American Chemical Society meeting included a four-day symposium in conjunction with the 20th anniversary of the announcement of cold fusion. Researchers working at the U.S. Navys Space and Naval Warfare Systems Center (SPAWAR) reported detection of energetic neutrons using a heavy water electrolysis setup and a CR-39 detector, a result previously published in Naturwissenschaften'. The authors claim that these neutrons are indicative of nuclear reactions. Without quantitative analysis of the number, energy, and timing of the neutrons and exclusion of other potential sources, this interpretation is unlikely to find acceptance by the wider scientific community. | 0 | Theoretical and Fundamental Chemistry |
Sodium–potassium alloy, colloquially called NaK (commonly pronounced ), is an alloy of the alkali metals sodium (Na, atomic number 11) and potassium (K, atomic number 19) that is normally liquid at room temperature. Various commercial grades are available. NaK is highly reactive with water (like its constituent elements) and may catch fire when exposed to air, so must be handled with special precautions. | 1 | Applied and Interdisciplinary Chemistry |
Ocean acidification can also lead to increased sea surface temperature. An increase of about 1 or 2 °C can cause the collapse of the relationship between coral and zooxanthellae, possibly leading to bleaching. The average sea surface temperature in the Great Barrier Reef is predicted to increase between 1 and 3 °C by 2100. Bleaching occurs when the zooxanthellae and coralline algae leave the coral skeleton behind due to stresses in the water. This causes the coral to lose its colour because the previous organisms sustained on the coral skeleton vacate, leaving a white skeleton. The bleached coral can no longer complete photosynthesis, and so it slowly dies. The acidity of the water will slowly dissolve the leftover coral skeletons, essentially damaging the structural integrity of the coral reef. There are many organisms that also rely on the algae and zooxanthellae for their main source of food. Therefore, organisms in the bleached coral reef are forced to leave in search of new food sources. Since zooxanthellae and algae grow very slowly, restoring the coral reef to its original form will take a very long time. This breakdown of the relationship between the coral and the zooxanthellae occurs when Photosystem II is damaged, either due to a reaction with the D1 protein or a lack of carbon dioxide fixation; these result in a lack of photosynthesis and can lead to bleaching. | 0 | Theoretical and Fundamental Chemistry |
All of the derivations given treat the initial binding step in terms of the law of mass action, which assumes free diffusion through the solution. However, in the environment of a living cell where there is a high concentration of proteins, the cytoplasm often behaves more like a viscous gel than a free-flowing liquid, limiting molecular movements by diffusion and altering reaction rates. Note, however that although this gel-like structure severely restricts large molecules like proteins its effect on small molecules, like many of the metabolites that participate in central metabolism, is very much smaller. In practice, therefore, treating the movement of substrates in terms of diffusion is not likely to produce major errors. Nonetheless, Schnell and Turner consider that is more appropriate to model the cytoplasm as a fractal, in order to capture its limited-mobility kinetics. | 0 | Theoretical and Fundamental Chemistry |
The use of the depth–slope product — in computing the bed shear-stress — specifically refers to two assumptions that are widely applicable to natural river channels: that the angle of the channel from horizontal is small enough that it can be approximated as the slope by the small-angle formula, and that the channel is much wider than it is deep, and sidewall effects can be ignored. Although it is a simplistic approach to find the shear stress in what can often be a locally unsteady fluvial system, when averaged over distances of kilometers, these local variations average and the depth–slope product becomes a useful tool to understand shear stress in open channels such as rivers. | 1 | Applied and Interdisciplinary Chemistry |
The site was opened in 1931 by the Lindsay Light and Chemical Company. It processed ores like monazite to produce elements, including thorium and uranium. It also made gaslight mantles, and during World War II, hydrofluoric acid.
In 1958, it became owned by American Potash and Chemical Company (AMPOT), which at one point had a Lindsay Chemical Division.
In 1967, AMPOT, and thus the facility, were bought by Kerr-McGee. The Rare Earths Facility were closed by Kerr-McGee in 1973.
In 2005, KMCC was spun off from Kerr-McGee as Tronox, shortly before Kerr-McGee was acquired by Anadarko Petroleum. Tronox inherited responsibility for the Rare Earths Facility and other sites. Tronox went bankrupt in 2009 and shareholders sued Anadarko Petroleum, partly for having misled investors in Tronox about its environmental debts. | 1 | Applied and Interdisciplinary Chemistry |
AOAC International, informally the AOAC, was founded September 8, 1884, as the Association of Official Agricultural Chemists, by the United States Department of Agriculture (USDA), to establish uniform chemical analysis methods for analyzing fertilizers. In 1927, sponsorship was moved to the newly formed Food, Drug and Insecticide organization which become the Food and Drug Administration (FDA) in 1930.
From its initial scope of analyzing fertilizer, the organization expanded the contents of its methods book to cover dairy products, pesticides, microbiological contamination and animal feeds, among others. In 1965, due to its increasing area of focus for analytical work, the name was changed to the Association of Official Analytical Chemists. The name was changed again to the Association of Analytical Communities to reflect the growing international involvement, and then in 1991 it became AOAC International, with AOAC no longer having any legal meaning. Control of the organization remained with the FDA until 1979 when it became completely independent, although it still has close links to both the FDA and the USDA.
Full membership was limited to government analytical chemists until 1987 when membership was extended to industrial scientists. As well as government agencies, members, volunteers and partners now also include people from academia, other international organizations, private laboratories, contract research organizations, instrument manufacturers and rapid assay developers. | 0 | Theoretical and Fundamental Chemistry |
The adsorption process can be characterized by determining what amount of the ions or molecules are adsorbed to the surface. This amount can be determined experimentally by the construction of an adsorption isotherm. An adsorption isotherm is a graph of Γ(P,T) versus partial pressure of the adsorbate(P/P) for a given constant temperature, where Γ(P,T) is the number of molecules adsorbed per surface area. As the partial pressure of the adsorbate increases, the number of molecules per area also increases. | 0 | Theoretical and Fundamental Chemistry |
It is possible to write down relativistic quantum Boltzmann equations for relativistic quantum systems in which the number of particles is not conserved in collisions. This has several applications in physical cosmology, including the formation of the light elements in Big Bang nucleosynthesis, the production of dark matter and baryogenesis. It is not a priori clear that the state of a quantum system can be characterized by a classical phase space density f. However, for a wide class of applications a well-defined generalization of f exists which is the solution of an effective Boltzmann equation that can be derived from first principles of quantum field theory. | 1 | Applied and Interdisciplinary Chemistry |
Adriaan "Ad" Bax (born 1956) is a Dutch-American molecular biophysicist. He was born in the Netherlands and is the Chief of the Section on Biophysical NMR Spectroscopy at the National Institutes of Health. He is known for his work on the methodology of biomolecular NMR spectroscopy. | 0 | Theoretical and Fundamental Chemistry |
One ancient process for extracting the silver from lead was cupellation. Lead was melted in a bone ash test or cupel and air blown across the surface. This oxidised the lead to litharge, and also oxidised other base metals present, the silver (and gold if present) remaining unoxidised.
In the 18th century, the process was carried on using a kind of reverberatory furnace, but differing from the usual kind in that air was blown over the surface of the molten lead from bellows or (in the 19th century) blowing cylinders. | 1 | Applied and Interdisciplinary Chemistry |
It is possible to combine the summation with the connectivity theorems to obtain closed expressions that relate the control coefficients to the elasticity coefficients. For example, consider the simplest non-trivial pathway:
We assume that and are fixed boundary species so that the pathway can reach a steady state. Let the first step have a rate and the second step . Focusing on the flux control coefficients, we can write one summation and one connectivity theorem for this simple pathway:
Using these two equations we can solve for the flux control coefficients to yield
Using these equations we can look at some simple extreme behaviors. For example, let us assume that the first step is completely insensitive to its product (i.e. not reacting with it), S, then . In this case, the control coefficients reduce to
That is all the control (or sensitivity) is on the first step. This situation represents the classic rate-limiting step that is frequently mentioned in textbooks. The flux through the pathway is completely dependent on the first step. Under these conditions, no other step in the pathway can affect the flux. The effect is however dependent on the complete insensitivity of the first step to its product. Such a situation is likely to be rare in real pathways. In fact the classic rate limiting step has almost never been observed experimentally. Instead, a range of limitingness is observed, with some steps having more limitingness (control) than others.
We can also derive the concentration control coefficients for the simple two step pathway: | 1 | Applied and Interdisciplinary Chemistry |
Hypophosphorous acid (and its salts) are used to reduce metal salts back into bulk metals. It is effective for various transition metals ions (i.e. those of: Co, Cu, Ag, Mn, Pt) but is most commonly used to reduce nickel. This forms the basis of electroless nickel plating (Ni–P), which is the single largest industrial application of hypophosphites. For this application it is principally used as a salt (sodium hypophosphite). | 0 | Theoretical and Fundamental Chemistry |
Some scientists have used the evidence of alarm-calling behaviour to challenge the theory that "evolution works only/primarily at the level of the gene and of the genes interest' in passing itself along to future generations." If alarm-calling is truly an example of altruism, then human understanding of natural selection becomes more complicated than simply "survival of the fittest gene".
Other researchers, generally those who support the selfish gene theory, question the authenticity of this "altruistic" behaviour. For instance, it has been observed that vervets sometimes emit calls in the presence of a predator, and sometimes do not. Studies show that these vervets may call more often when they are surrounded by their own offspring and by other relatives who share many of their genes. Other researchers have shown that some forms of alarm calling, for example, "aerial predator whistles" produced by Belding's ground squirrels, do not increase the chances that a caller will get eaten by a predator; the alarm call is advantageous to both caller and recipient by frightening and warding off the predator. | 1 | Applied and Interdisciplinary Chemistry |
Because of the non-covalent host-guest interaction, the polymer backbone can have enough flexibility to diffuse. If a crack exists in the materials, after compressing the two materials around the crack, because of the fast exchange of the host-guest molecular structure, the crack will rejoin again revealing good self-healing properties. Harada et al reported a self-healing hydrogel constructed by vinyl-group-modified cyclodextrin and adamantane. Another strategy is to use the interaction between the polymer backbone and host molecule (host molecule threading onto the polymer). If the threading process is fast enough, self-healing can also be achieved. | 0 | Theoretical and Fundamental Chemistry |
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