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Keene P. Dimick Award in Chromatography, Third International Symposium on Supercritical Fluid Chromatography Award for Pioneering Work in the Development of SFC; Marcel J.E. Golay Award and Medal, International Symposium on Capillary Chromatography; American Chemical Society Award in Separation Science and Technology; American Chemical Society Exceptional Achievement Award as a Capillary Gas Chromatography Short Course Instructor; R&D 100 Award for technologically significant new product: -PAGE Polyacrylamide Gel-filled Capillaries for Capillary Electrophoresis”; Jan E. Purkynje Memorial Medal of the Czech Academy of Sciences; R&D Magazine Scientist of the Year Award; M.S. Tswett Memorial Medal of the Russian Academy of Sciences; A.J.P. Martin Gold Medal of the Chromatographic Society of Great Britain; Theophilus Redwood Award, The Royal Society of Chemistry, Great Britain; Distinguished Teaching and Mentoring Award of the University Graduate School, Indiana University; Elected as a Foreign Member of the Royal Society of Sciences (Sweden); College of Arts & Sciences Distinguished Faculty Award, Indiana University. | 0 | Theoretical and Fundamental Chemistry |
Difluoroethane is an intoxicant with abuse potential. It appears to act primarily through GABA and glutamate receptors. Fatalities linked to difluoroethane abuse include actress Skye McCole Bartusiak, singer Aaron Carter and wrestler Mike Bell. Bitterants, added voluntarily to some brands to deter purposeful inhalation, are often not legally required; they do not negate or counteract difluoroethane's intoxicating effects. | 1 | Applied and Interdisciplinary Chemistry |
Fine chemicals are used as starting materials for specialty chemicals. The latter are obtained either by direct formulation or after chemical/biochemical transformation of intermediates to active substances. Life sciences, primarily pharmaceutical, agrochemical and food and feed industries are the main consumers of fine chemicals. | 0 | Theoretical and Fundamental Chemistry |
Boric acid, more specifically orthoboric acid, is a compound of boron, oxygen, and hydrogen with formula . It may also be called hydrogen orthoborate, trihydroxidoboron or boracic acid. It is usually encountered as colorless crystals or a white powder, that dissolves in water, and occurs in nature as the mineral sassolite. It is a weak acid that yields various borate anions and salts, and can react with alcohols to form borate esters.
Boric acid is often used as an antiseptic, insecticide, flame retardant, neutron absorber, or precursor to other boron compounds.
The term "boric acid" is also used generically for any oxoacid of boron, such as metaboric acid and tetraboric acid . | 0 | Theoretical and Fundamental Chemistry |
Foldit's developers wanted to attract as many people as possible to the cause of protein folding. So, rather than only building a useful science tool, they used gamification (the inclusion of gaming elements) to make Foldit appealing and engaging to the general public.
As a protein structure is modified, a score is calculated based on how well-folded the protein is, and a list of high scores for each puzzle is maintained. Foldit users may create and join groups, and members of groups can share puzzle solutions. Groups have been found to be useful in training new players. A separate list of group high scores is maintained. | 1 | Applied and Interdisciplinary Chemistry |
Chiral amide bases may be used in catalytic amounts to isomerize meso epoxides to chiral allylic alcohols with high enantioselectivity. | 0 | Theoretical and Fundamental Chemistry |
A primary alcohol is an alcohol in which the hydroxy group is bonded to a primary carbon atom. It can also be defined as a molecule containing a “–CHOH” group.
In contrast, a secondary alcohol has a formula “–CHROH” and a tertiary alcohol has a formula “–CROH”, where “R” indicates a carbon-containing group.
Examples of primary alcohols include ethanol and 1-butanol.
Methanol is also generally regarded as a primary alcohol, including by the 1911 edition of the Encyclopædia Britannica. | 0 | Theoretical and Fundamental Chemistry |
PBMCs were separated from blood on Ficoll-Paque by differential centrifugation and were suspended in 24-well tissue culture plates culture medium. Different dilutions of PBMCs were incubated at 37 °C with 5% . Culture supernatants were collected at 24, 48, 72, and 96 h after incubation and the supernatants were test against BCG or PPD by ELISA. The ELISA titer indicate the positive or negative result. | 1 | Applied and Interdisciplinary Chemistry |
A dienone is a class of organic compounds that are formally "derived from diene compounds by conversion of a –CH2– groups into –C(=O)– group .", resulting in "a conjugated structure". The class includes some heterocyclic compounds. | 0 | Theoretical and Fundamental Chemistry |
In the early 1940s, Seaborg moved to Chicago to work on the Manhattan Project. He invited Ghiorso to join him, and for the next four years Ghiorso developed sensitive instruments for detecting the radiation associated with nuclear decay, including spontaneous fission. One of Ghiorso's breakthrough instruments was a 48-channel pulse height analyzer, which enabled him to identify the energy, and therefore the source, of the radiation. During this time they discovered two new elements (95, americium and 96, curium), although publication was withheld until after the war. | 1 | Applied and Interdisciplinary Chemistry |
In the future, radioligand therapy may expand to include more α-emitter based treatments. Currently, β radioligand therapies are more commonly used in oncology. Clinical trials of α-emitters are underway due to their higher potency and ability to induce double-strand DNA breaks. There are multiple Actinium-225 based PSMA studies that will be launched in 2024. If these prove successful, there is potential for further studies and clinical trials to be done using α-emitters. Additionally, there is potential for the future use of radioligand therapy in patients with malignant brain tumors. Finally, there have been recent developments in diagnostic tracers using radioligands, as well as with radioligand-based imaging techniques and in the field of theranostics. | 1 | Applied and Interdisciplinary Chemistry |
Via the process of hydrogenation, unsaturated N-containing functional groups are reduced to amines using hydrogen in the presence of a nickel catalyst. Suitable groups include nitriles, azides, imines including oximes, amides, and nitro. In the case of nitriles, reactions are sensitive to acidic or alkaline conditions, which can cause hydrolysis of the group. Lithium aluminium hydride| is more commonly employed for the reduction of these same groups on the laboratory scale.
Many amines are produced from aldehydes and ketones via reductive amination, which can either proceed catalytically or stoichiometrically.
Aniline () and its derivatives are prepared by reduction of the nitroaromatics. In industry, hydrogen is the preferred reductant, whereas, in the laboratory, tin and iron are often employed. | 0 | Theoretical and Fundamental Chemistry |
Diglycerides, generally in a mix with monoglycerides (E471), are common food additives largely used as emulsifiers. The values given in the nutritional labels for total fat, saturated fat, and trans fat do not include those present in mono- and diglycerides. They often are included in bakery products, beverages, ice cream, peanut butter, chewing gum, shortening, whipped toppings, margarine, confections, and some snack products, such as Pringles. | 1 | Applied and Interdisciplinary Chemistry |
Hydraulic head or piezometric head is a specific measurement of liquid pressure above a vertical datum.
It is usually measured as a liquid surface elevation, expressed in units of length, at the entrance (or bottom) of a piezometer. In an aquifer, it can be calculated from the depth to water in a piezometric well (a specialized water well), and given information of the piezometers elevation and screen depth. Hydraulic head can similarly be measured in a column of water using a standpipe piezometer by measuring the height of the water surface in the tube relative to a common datum. The hydraulic head can be used to determine a hydraulic gradient' between two or more points. | 1 | Applied and Interdisciplinary Chemistry |
Applications of the Kuramoto–Sivashinsky equation extend beyond its original context of flame propagation and reaction–diffusion systems. These additional applications include flows in pipes and at interfaces, plasmas, chemical reaction dynamics, and models of ion-sputtered surfaces. | 1 | Applied and Interdisciplinary Chemistry |
In monometallic complexes, aldehydes and ketones can bind to metals in either of two modes, η-O-bonded and η-C,O-bonded. These bonding modes are sometimes referred to sigma- and pi-bonded. These forms may sometimes interconvert.
The sigma bonding mode is more common for higher valence, Lewis-acidic metal centers (e.g., Zn). The pi-bonded mode is observed for low valence, electron-rich metal centers (e.g., Fe(0) and Os(0)).
For the purpose of electron-counting, O-bonded ligands count as 2-electron "L ligands": they are Lewis bases. η-C,O ligands are described as analogues of alkene ligands, i.e. the Dewar-Chatt-Duncanson model.
η-C,O ketones and aldehydes can function as bridging ligands, utilizing a lone pair of electrons on oxygen. One such complex is , which features a ring. | 0 | Theoretical and Fundamental Chemistry |
Elasticities coefficient can also be computed numerically, something that is often done in simulation software.
For example, a small change (say 5%) can be made to the chosen reactant concentration, and the change in the reaction rate recorded. To illustrate this, assume that the reference reaction rate is , and the reference reactant concentration, . If we increase the reactant concentration by and record the new reaction rate as , then the elasticity can be estimated by using Newton's difference quotient:
A much better estimate for the elasticity can be obtained by doing two separate perturbations in . One perturbation to increase and another to decrease . In each case, the new reaction rate is recorded; this is called the two-point estimation method. For example, if is the reaction rate
when we increase , and is the reaction rate when we decrease , then
we can use the following two-point formula to estimate the elasticity: | 0 | Theoretical and Fundamental Chemistry |
DNA can have mutations that cause a base in the DNA strand to be damaged. To ensure genetic integrity of the DNA, enzymes need to repair any damage. There are many types of DNA repair. Base excision repair utilizes base flipping to flip the damaged base out of the double helix and into the specificity pocket of a glycosylase which hydrolyzes the glycosidic bond and removes the base. DNA glycosylases interact with DNA, flipping bases to determine a mismatch. An example of base excision repair occurs when a cytosine base is deaminated and becomes a uracil base. This causes a U:G mispair which is detected by Uracil DNA glycosylase. The uracil base is flipped out into the glycosylase active pocket where it is removed from the DNA strand. Base flipping is used to repair mutations such as 8-Oxoguanine (oxoG) and thymine dimers created by UV radiation. | 1 | Applied and Interdisciplinary Chemistry |
An internal wave can readily be observed in the kitchen by slowly tilting back and forth a bottle of salad dressing - the waves exist at the interface between oil and vinegar.
Atmospheric internal waves can be visualized by wave clouds: at the wave crests air rises and cools in the relatively lower pressure, which can result in water vapor condensation if the relative humidity is close to 100%. Clouds that reveal internal waves launched by flow over hills are called lenticular clouds because of their lens-like appearance. Less dramatically, a train of internal waves can be visualized by rippled cloud patterns described as herringbone sky or mackerel sky. The outflow of cold air from a thunderstorm can launch large amplitude internal solitary waves at an atmospheric inversion. In northern Australia, these result in Morning Glory clouds, used by some daredevils to glide along like a surfer riding an ocean wave. Satellites over Australia and elsewhere reveal these waves can span many hundreds of kilometers.
Undulations of the oceanic thermocline can be visualized by satellite because the waves increase the surface roughness where the horizontal flow converges, and this increases the scattering of sunlight (as in the image at the top of this page showing of waves generated by tidal flow through the Strait of Gibraltar). | 1 | Applied and Interdisciplinary Chemistry |
MCD can be used as an optical technique for the detection of electronic structure of both the ground states and excited states. It is also a strong addition to the more commonly used absorption spectroscopy, and there are two reasons that explain this. First, a transition buried under a stronger transition can appear in MCD if the first derivative of the absorption is much larger for the weaker transition or it is of the opposite sign. Second, MCD will be found where no absorption is detected at all if ΔA > (ΔA) but A , where (ΔA) and A are the minimum of ΔA and A that are detectable. Typically, (ΔA) and A are of the magnitudes around 10 and 10 respectively. So, a transition can only be detected in MCD, not in the absorption spectroscopy, if ΔA/A > 10. This happens in paramagnetic systems that are at lower temperature or that have sharp lines in the spectroscopy.
In biology, metalloproteins are the most likely candidates for MCD measurements, as the presence of metals with degenerate energy levels leads to strong MCD signals. In the case of ferric heme proteins, MCD is capable of determining both oxidation and spin state to a remarkably exquisite degree. In regular proteins, MCD is capable of stoichiometrically measuring the tryptophan content of proteins, assuming there are no other competing absorbers in the spectroscopic system.
In addition, the application of MCD spectroscopy greatly improved the level of understanding in the ferrous non-heme systems because of the direct observation of the d–d transitions, which generally can not be obtained in optical absorption spectroscopy owing to the weak extinction coefficients and are often electron paramagnetic resonance silent due to relatively large ground-state sublevel splittings and fast relaxation times. | 0 | Theoretical and Fundamental Chemistry |
A retrovirus is a type of virus that inserts a DNA copy of its RNA genome into the DNA of a host cell that it invades, thus changing the genome of that cell. After invading a host cells cytoplasm, the virus uses its own reverse transcriptase enzyme to produce DNA from its RNA genome, the reverse of the usual pattern, thus retro (backwards). The new DNA is then incorporated into the host cell genome by an integrase enzyme, at which point the retroviral DNA is referred to as a provirus. The host cell then treats the viral DNA as part of its own genome, transcribing and translating the viral genes along with the cells own genes, producing the proteins required to assemble new copies of the virus. Many retroviruses cause serious diseases in humans, other mammals, and birds.
Retroviruses have many subfamilies in three basic groups.
* Oncoretroviruses (cancer-causing retroviruses) include human T-lymphotropic virus (HTLV) causing a type of leukemia in humans, and murine leukemia viruses (MLVs) in mice.
* Lentiviruses (slow viruses) include HIV-1 and HIV-2, the cause of acquired immune deficiency syndrome (AIDS) in humans.
* Spumaviruses (foamy viruses) are benign and not linked to any disease in humans or animals.
The specialized DNA-infiltration enzymes in retroviruses make them valuable research tools in molecular biology, and they have been used successfully in gene delivery systems.
Evidence from endogenous retroviruses (inherited provirus DNA in animal genomes) suggests that retroviruses have been infecting vertebrates for at least 450 million years. | 1 | Applied and Interdisciplinary Chemistry |
The theory presents simple mechanistic rules that describe the uptake and allocation of energy (and nutrients) and the consequences for physiological organization throughout an organism's life cycle, including the relationships of energetics with aging and effects of toxicants. Assumptions of the DEB theory are delineated in an explicit way, the approach clearly distinguishes mechanisms associated with intra‐ and interspecific variation in metabolic rates, and equations for energy flows are mathematically derived following the principles of physics and simplicity.
Cornerstones of the theory are:
* conservation of mass, energy and time,
* relationships between surface area and volume
* stoichiometric constraints on production
* organizational uncoupling of metabolic modules (assimilation, dissipation, growth)
* strong and weak homeostasis (composition of compartments is constant; composition of the organism is constant when the food is constant)
* substrate(s) from the environment is/are first converted to reserve(s) before being used for further metabolism
The theory specifies that an organism is made up two main compartments: (energy) reserve and structure. Assimilation of energy is proportional to surface area of the structure, and maintenance is proportional to its volume. Reserve does not require maintenance. Energy mobilization will depend on the relative amount of the energy reserve, and on the interface between reserve and structure. Once mobilized, the energy is split into two branches:
* a fixed proportion (termed kappa, κ) is allocated to growth (increase of structural mass) and maintenance of structure, while
* the remaining proportion (1- κ) is allocated to processes of maturation (increase in complexity, installation of regulation systems, preparation for reproduction) and maintaining the level of attained maturity (including, e.g., maintenance of defense systems).
The κ-rule therefore states that the processes of growth and maturation do not directly compete. Maintenance needs to be paid before allocating energy to other processes.
In the context of energy acquisition and allocation, the theory recognizes three main developmental stages: embryo, which does not feed or reproduce, juvenile, which feeds but does not reproduce, and adult, which both feeds and is allocating energy to reproduction. Transitions between these life stages occur at events specified as birth and puberty, which are reached when energy invested into maturation (tracked as level of maturity<nowiki/>) reaches a certain threshold. Maturity does not increase in the adult stage, and maturity maintenance is proportional to maturity.
Biochemical composition of reserve and structure is considered to be that of generalised compounds, and is constant (the assumption of strong homeostasis) but not necessarily identical. Biochemical transformation from food to reserve (assimilation), and from reserve to structure (growth) include overhead costs. These overheads, together with processes of somatic and maturity maintenance and reproduction overheads (inefficiencies in transformation from reserve to reproductive material), all contribute to the consumption of oxygen and production of carbon dioxide, i.e. metabolism. | 1 | Applied and Interdisciplinary Chemistry |
When a photon is the incident particle, there is an inelastic scattering process called Raman scattering. In this scattering process, the incident photon interacts with matter (gas, liquid, and solid) and the frequency of the photon is shifted towards red or blue. A red shift can be observed when part of the energy of the photon is transferred to the interacting matter, where it adds to its internal energy in a process called Stokes Raman scattering. The blue shift can be observed when internal energy of the matter is transferred to the photon; this process is called anti-Stokes Raman scattering.
Inelastic scattering is seen in the interaction between an electron and a photon. When a high-energy photon collides with a free electron (more precisely, weakly bound since a free electron cannot participate in inelastic scattering with a photon) and transfers energy, the process is called Compton scattering. Furthermore, when an electron with relativistic energy collides with an infrared or visible photon, the electron gives energy to the photon. This process is called inverse Compton scattering. | 0 | Theoretical and Fundamental Chemistry |
If homopolymer repeats of the same nucleotide (e.g. ) are present on the template strand (strand to be sequenced) then multiple introduced nucleotides are incorporated and more hydrogen ions are released in a single cycle. This results in a greater pH change and a proportionally greater electronic signal. This is a limitation of the system in that it is difficult to enumerate long repeats. This limitation is shared by other techniques that detect single nucleotide additions such as pyrosequencing. Signals generated from a high repeat number are difficult to differentiate from repeats of a similar but different number; e.g., homorepeats of length 7 are difficult to differentiate from those of length 8.
Another limitation of this system is the short read length compared to other sequencing methods such as Sanger sequencing or pyrosequencing. Longer read lengths are beneficial for de novo genome assembly. Ion Torrent semiconductor sequencers produce an average read length of approximately 400 nucleotides per read.
The throughput is currently lower than that of other high-throughput sequencing technologies, although the developers hope to change this by increasing the density of the chip. | 1 | Applied and Interdisciplinary Chemistry |
AFPs work through an interaction with small ice crystals that is similar to an enzyme-ligand binding mechanism which inhibits recrystallization of ice. This explanation of the interruption of the ice crystal structure by the AFP has come to be known as the adsorption-inhibition hypothesis.
According to this hypothesis, AFPs disrupt the thermodynamically favourable growth of an ice crystal via kinetic inhibition of contact between solid ice and liquid water. In this manner, the nucleation sites of the ice crystal lattice are blocked by the AFP, inhibiting the rapid growth of the crystal that could be fatal for the organism. In physical chemistry terms, the AFPs adsorbed onto the exposed ice crystal force the growth of the ice crystal in a convex fashion as the temperature drops, which elevates the ice vapour pressure at the nucleation sites. Ice vapour pressure continues to increase until it reaches equilibrium with the surrounding solution (water), at which point the growth of the ice crystal stops.
The aforementioned effect of AFPs on ice crystal nucleation is lost at the thermal hysteresis point. At a certain low temperature, the maximum convexity of the ice nucleation site is reached. Any further cooling will actually result in a "spreading" of the nucleation site away from this convex region, causing rapid, uncontrollable nucleation of the ice crystal. The temperature at which this phenomenon occurs is the thermal hysteresis point.<br>
The adsorption-inhibition hypothesis is further supported by the observation that antifreeze activity increases with increasing AFP concentration – the more AFPs adsorb onto the forming ice crystal, the more crowded these proteins become, making ice crystal nucleation less favourable.
In the R. inquisitor beetle, AFPs are found in the haemolymph, a fluid that bathes all the cells of the beetle and fills a cavity called the haemocoel. The presence of AFPs in R. inquisitor allows the tissues and fluids within the beetle to withstand freezing up to -30 °C (the thermal hysteresis point for this AFP). This strategy provides an obvious survival benefit to these beetles, who are endemic to cold climates, such as Scandinavia, Siberia, and Alaska. | 1 | Applied and Interdisciplinary Chemistry |
The following assumptions are made in order to simplify the Rankine–Hugoniot equations. The mixture is assumed to obey the ideal gas law, so that relation between the downstream and upstream equation of state can be written as
where is the universal gas constant and the mean molecular weight is assumed to be constant (otherwise, would depend on the mass fraction of the all species). If one assumes that the specific heat at constant pressure is also constant across the wave, the change in enthalpies (calorific equation of state) can be simply written as
where the first term in the above expression represents the amount of heat released per unit mass of the upstream mixture by the wave and the second term represents the sensible heating. Eliminating temperature using the equation of state and substituting the above expression for the change in enthalpies into the Hugoniot equation, one obtains an Hugoniot equation expressed only in terms of pressure and densities,
where is the specific heat ratio, which for ordinary room temperature air (298 KELVIN) = 1.40. An Hugoniot curve without heat release () is often called a "shock Hugoniot", or simply a(n) "Hugoniot". Along with the Rayleigh line equation, the above equation completely determines the state of the system. These two equations can be written compactly by introducing the following non-dimensional scales,
The Rayleigh line equation and the Hugoniot equation then simplifies to
Given the upstream conditions, the intersection of above two equations in the - plane determine the downstream conditions; in the - plane, the upstream condition correspond to the point . If no heat release occurs, for example, shock waves without chemical reaction, then . The Hugoniot curves asymptote to the lines and , which are depicted as dashed lines in the figure. As mentioned in the figure, only the white region bounded by these two asymptotes are allowed so that is positive. Shock waves and detonations correspond to the top-left white region wherein and , that is to say, the pressure increases and the specific volume decreases across the wave (the Chapman–Jouguet condition for detonation is where Rayleigh line is tangent to the Hugoniot curve). Deflagrations, on the other hand, correspond to the bottom-right white region wherein and , that is to say, the pressure decreases and the specific volume increases across the wave; the pressure decrease a flame is typically very small which is seldom considered when studying deflagrations.
For shock waves and detonations, the pressure increase across the wave can take any values between ; the steeper the slope of the Rayleigh line, the stronger is the wave. On the contrary, here the specific volume ratio is restricted to the finite interval (the upper bound is derived for the case because pressure cannot take negative values). If (diatomic gas without the vibrational mode excitation), the interval is , in other words, the shock wave can increase the density at most by a factor of 6. For monatomic gas, , the allowed interval is . For diatomic gases with vibrational mode excited, we have leading to the interval . In reality, the specific heat ratio is not constant in the shock wave due to molecular dissociation and ionization, but even in these cases, density ratio in general do not exceed a factor of about . | 1 | Applied and Interdisciplinary Chemistry |
One potential application of ARS involves the rapid and nondestructive identification of drug tablet verification. Currently, there are no unfailing methods to eliminate contaminated or mislabeled products, a process which sometimes results in millions of pills having to be recalled. More studies need to be completed to determine if ARS could be used as a process analytical technique in industry to prevent problems with pills before they are shipped. ARS may also be useful for quantifying the active ingredient in pharmaceutical ointments and gels. | 0 | Theoretical and Fundamental Chemistry |
The Pneumatic Quasiturbine engine is a compressed-air pistonless rotary engine using a rhomboidal-shaped rotor whose sides are hinged at the vertices.
The Quasiturbine has demonstrated as a pneumatic engine using stored compressed air.
It can also take advantage of the energy amplification possible from using available external heat, such as solar energy.
The Quasiturbine rotates from pressure as low as 0.1 atm (1.47psi).
Since the Quasiturbine is a pure expansion engine, while the Wankel and most other rotary engines are not, it is well-suited as a compressed fluid engine, air engine or air motor. | 1 | Applied and Interdisciplinary Chemistry |
Quantum logic spectroscopy (QLS) is an ion control scheme that maps quantum information between two co-trapped ion species. Quantum logic operations allow desirable properties of each ion species to be utilized simultaneously. This enables work with ions and molecular ions that have complex internal energy level structures which preclude laser cooling and direct manipulation of state. QLS was first demonstrated by NIST in 2005. QLS was first applied to state detection in diatomic molecules in 2016 by Wolf et al, and later applied to state manipulation and detection of diatomic molecules by the Liebfried group at NIST in 2017 | 0 | Theoretical and Fundamental Chemistry |
Adverse effects are typically mild to moderate. However, severe, disabling, and potentially irreversible adverse effects sometimes occur, and for this reason it is recommended that use of fluoroquinolones be limited.
Prominent among these are adverse effects that became the subject of a black box warning by the FDA in 2016. The FDA wrote: "An FDA safety review has shown that fluoroquinolones when used systemically (i.e. tablets, capsules, and injectable) are associated with disabling and potentially permanent serious adverse effects that can occur together. These adverse effects can involve the tendons, muscles, joints, nerves, and central nervous system." Rarely, tendinitis or tendon rupture may occur due to fluoroquinolone antibiotics, including levofloxacin. Such injuries, including tendon rupture, has been observed up to 6 months after cessation of treatment; higher doses of fluoroquinolones, being elderly, transplant patients, and those with a current or historical corticosteroid use are at elevated risk. The U.S. label for levofloxacin also contains a black box warning for the exacerbation of the symptoms of the neurological disease myasthenia gravis. Similarly, the UK Medicines and Healthcare Products Regulatory Agency recommendations warn of rare but disabling and potentially irreversible adverse effects, and to recommend limiting use of these drugs. Increasing age and corticosteroid use appears to increase the risk of musculoskeletal complications.
A wide variety of other uncommon but serious adverse events have been associated with fluoroquinolone use, with varying degrees of evidence supporting causation. These include anaphylaxis, hepatotoxicity, central nervous system effects including seizures and psychiatric effects, prolongation of the QT interval, blood glucose disturbances, and photosensitivity, among others. Levofloxacin may produce fewer of these rare serious adverse effects than other fluoroquinolones.
There is some disagreement in the medical literature regarding whether and to what extent levofloxacin and other fluoroquinolones produce serious adverse effects more frequently than other broad spectrum antibacterial drugs.
With regard to more usual adverse effects, in pooled results from 7537 patients exposed to levofloxacin in 29 clinical trials, 4.3% discontinued treatment due to adverse drug reactions. The most common adverse reactions leading to discontinuation were gastrointestinal, including nausea, vomiting, and constipation. Overall, 7% of patients experienced nausea, 6% headache, 5% diarrhea, 4% insomnia, along with other adverse reactions experienced at lower rates.
Administration of levofloxacin or other broad spectrum antibiotics is associated with Clostridium difficile associated diarrhea which may range in severity from mild diarrhea to fatal colitis. Fluoroquinoline administration may be associated with the acquisition and outgrowth of a particularly virulent Clostridium strain.
More research is needed to determine the best dose and length of treatment. | 0 | Theoretical and Fundamental Chemistry |
Pall rings are the most common form of random packing. They are similar to Lessing rings and were developed from the Raschig ring. Pall rings have similar cylindrical dimensions but has rows of windows which increase performance by increasing the surface area. They are suited for low pressure drop and high capacity applications. They have a degree of randomness and a relatively high liquid hold up, promoting a high absorption, especially when the rate of reaction is slow. The cross structure of the Pall ring makes it mechanically robust and suitable for use in deep packed beds. | 1 | Applied and Interdisciplinary Chemistry |
Lecoq de Boisbaudran's early investigations focused on understanding the phenomenon of supersaturation, in which substances can exist in solution in higher concentrations than is possible under normal conditions. He showed that contact of supersaturated solutions with crystals of an isomorphous salt causes the substance to precipitate from the solution. He further showed that many anhydrous salts can be dissolved to create a supersaturated solution. These investigations were carried out from 1866 to 1869.
In 1874 Lecoq de Boisbaudran found that certain crystal faces dissolve more rapidly than other crystal faces. Specifically, he found that octahedral faces are less readily soluble than cubic faces in the case of ammonium alum crystals.
Lecoq de Boisbaudran made major contributions to the then-new science of spectroscopy, which relates to the interaction of light and matter. He applied spectroscopy to characterize elements, particularly the rare-earth elements. He developed a theoretical framework of spectroscopy, based on molecular vibrations. Theorizing that spectral frequencies relate to the atomic weight of an element, he recognized spectral trends based upon atomic masses.
Boisbaudran developed new experimental apparatus and used these to carry out spectral analyses of various chemical elements. Through systematic experimentation, he analysed spectra of 35 elements, using the Bunsen burner, electric spark or both to induce luminescence of samples of the elements. The results of his early investigations were published in his Spectres lumineux : spectres prismatiques et en longueurs dondes destinés aux recherches de chimie minérale' (1874).
To observe spark spectra in his experimental protocols, he typically placed a solution of a salt in a sealed glass tube, with a platinum wire in the solution as a negative pole, and another platinum wire above the surface of the liquid as a positive pole. In 1885, he experimented with reversing the polarity of the electric current. In this way, he obtained phosphorescent bands in the spectra providing further insight into the spectral characteristics of various chemical elements. Using this apparatus, he discovered the lanthanides samarium (1880), dysprosium (1886) and europium (1890). In 1885, he also spectroscopically characterized gadolinium in 1885, an element previously discovered in 1880 by J. C. Galissard de Marignac. | 1 | Applied and Interdisciplinary Chemistry |
Genome-wide association studies (GWAS) identify linkages between alleles and observable traits such as phenotypes and diseases. Most of the associations are between single-nucleotide polymorphisms (SNPs) and the trait being examined and most of these SNPs are located in non-functional DNA. The association establishes a linkage that helps map the DNA region responsible for the trait but it does not necessarily identify the mutations causing the disease or phenotypic difference.
SNPs that are tightly linked to traits are the ones most likely to identify a causal mutation. (The association is referred to as tight linkage disequilibrium.) About 12% of these polymorphisms are found in coding regions; about 40% are located in introns; and most of the rest are found in intergenic regions, including regulatory sequences. | 1 | Applied and Interdisciplinary Chemistry |
Effector triggered immunity (ETI) is activated by the presence of pathogen effectors. The ETI response is reliant on R genes, and is activated by specific pathogen strains. Plant ETI often causes an apoptotic hypersensitive response. | 1 | Applied and Interdisciplinary Chemistry |
Molecular dynamics methods of calculating pK values make it possible to include full flexibility of the titrated molecule.
Molecular dynamics based methods are typically much more computationally expensive, and not necessarily more accurate, ways to predict pK values than approaches based on the Poisson–Boltzmann equation. Limited conformational flexibility can also be realized within a continuum electrostatics approach, e.g., for considering multiple amino acid sidechain rotamers. In addition, current commonly used molecular force fields do not take electronic polarizability into account, which could be an important property in determining protonation energies. | 0 | Theoretical and Fundamental Chemistry |
This is not the usual form in which the equation is used. Instead, the equation is set to zero, meaning , indicating we are at equilibrium and the concentrations and are now equilibrium concentrations, hence:
Rearranging this gives the so-called Haldane relationship:
The advantage of this is that one of the four constants can be eliminated and replaced with the equilibrium constant which is more likely to be known. In addition, it allows one to make a useful interpretation in terms of the thermodynamic and saturation effects (see next section). Most often the reverse maximum rate is eliminated to yield the final equation: | 0 | Theoretical and Fundamental Chemistry |
Reihlen and Flohr demonstrated that Wolffram’s salt could be prepared directly by mixing aqueous solutions of the colorless [[Pt(etn)4Cl2|[Pt(etn)]Cl]] and its yellow analogue, [Pt(etn)Cl]Cl, where etn = NHCHCH, leading to the most probable conclusion of the double salt formula, [Pt(CHNH)Cl] [Pt(CHNH)]Cl·4HO, compared with concurrently postulated explanations of tervalent platinum. | 0 | Theoretical and Fundamental Chemistry |
The term gerontoplast was first introduced in 1977 to define the unique features of the plastid formed during leaf senescence. The process of senescence brings about regulated dismantling of cellular organelles involved in photosynthesis. Chloroplasts responsible for gas exchange in stomata are the last organelles to degrade during senescence, and give plants the green color. The formation of gerontoplasts from chloroplasts during senescence involves extensive structural modifications of the thylakoid membrane with the concomitant formation of a large number of plastoglobuli with lipophilic materials. The envelope of the plastid, however, remains intact. | 0 | Theoretical and Fundamental Chemistry |
EPS is found in the matrix of other microbial biofilms such as microalgal biofilms. The formation of biofilm and structure of EPS share a lot of similarities with bacterial ones. The formation of biofilm starts with reversible absorption of floating cells to the surface. Followed by production of EPS, the adsorption will get irreversible. EPS will colonize the cells at the surface with hydrogen bonding. Replication of early colonizers will be facilitated by the presence of organic molecules in the matrix which will provide nutrients to the algal cells. As the colonizers are reproducing, the biofilm grows and becomes a 3-dimensional structure. Microalgal biofilms consist of 90% EPS and 10% algal cells. Algal EPS has similar components to the bacterial one; it is made up of proteins, phospholipids, polysaccharides, nucleic acids, humic substances, uronic acids and some functional groups, such as phosphoric, carboxylic, hydroxyl and amino groups. Algal cells consume EPS as their source of energy and carbon. Furthermore, EPS protects them from dehydration and reinforces the adhesion of the cells to the surface. In algal biofilms, EPS has two sub-categories; soluble EPS (sEPS) and the bounded EPS (bEPS) with former being distributed in the medium and the latter being attached to the algal cells. Bounded EPS can be further subdivided to tightly bounded EPS (TB-EPS) and loosely bounded EPS (LB-EPS). Several factors contribute to the composition of EPS including species, substrate type, nutrient availability, temperature, pH and light intensity. | 1 | Applied and Interdisciplinary Chemistry |
A glass ionomer cement (GIC) is a dental restorative material used in dentistry as a filling material and luting cement, including for orthodontic bracket attachment. Glass-ionomer cements are based on the reaction of silicate glass-powder (calciumaluminofluorosilicate glass) and polyacrylic acid, an ionomer. Occasionally water is used instead of an acid, altering the properties of the material and its uses. This reaction produces a powdered cement of glass particles surrounded by matrix of fluoride elements and is known chemically as glass polyalkenoate. There are other forms of similar reactions which can take place, for example, when using an aqueous solution of acrylic/itaconic copolymer with tartaric acid, this results in a glass-ionomer in liquid form. An aqueous solution of maleic acid polymer or maleic/acrylic copolymer with tartaric acid can also be used to form a glass-ionomer in liquid form. Tartaric acid plays a significant part in controlling the setting characteristics of the material. Glass-ionomer based hybrids incorporate another dental material, for example resin-modified glass ionomer cements (RMGIC) and compomers (or modified composites).
Non-destructive neutron scattering has evidenced GIC setting reactions to be non-monotonic, with eventual fracture toughness dictated by changing atomic cohesion, fluctuating interfacial configurations and interfacial terahertz (THz) dynamics.
It is on the World Health Organization's List of Essential Medicines. | 0 | Theoretical and Fundamental Chemistry |
Chemical potential was first described by the American engineer, chemist and mathematical physicist Josiah Willard Gibbs. He defined it as follows:
Gibbs later noted also that for the purposes of this definition, any chemical element or combination of elements in given proportions may be considered a substance, whether capable or not of existing by itself as a homogeneous body. This freedom to choose the boundary of the system allows the chemical potential to be applied to a huge range of systems. The term can be used in thermodynamics and physics for any system undergoing change. Chemical potential is also referred to as partial molar Gibbs energy (see also partial molar property). Chemical potential is measured in units of energy/particle or, equivalently, energy/mole.
In his 1873 paper A Method of Geometrical Representation of the Thermodynamic Properties of Substances by Means of Surfaces, Gibbs introduced the preliminary outline of the principles of his new equation able to predict or estimate the tendencies of various natural processes to ensue when bodies or systems are brought into contact. By studying the interactions of homogeneous substances in contact, i.e. bodies, being in composition part solid, part liquid, and part vapor, and by using a three-dimensional volume–entropy–internal energy graph, Gibbs was able to determine three states of equilibrium, i.e. "necessarily stable", "neutral", and "unstable", and whether or not changes will ensue. In 1876, Gibbs built on this framework by introducing the concept of chemical potential so to take into account chemical reactions and states of bodies that are chemically different from each other. In his own words from the aforementioned paper, Gibbs states:
In this description, as used by Gibbs, ε refers to the internal energy of the body, η refers to the entropy of the body, and ν is the volume of the body. | 0 | Theoretical and Fundamental Chemistry |
A nominal oxidation state is a general term with two different definitions:
* Electrochemical oxidation state represents a molecule or ion in the Latimer diagram or Frost diagram for its redox-active element. An example is the Latimer diagram for sulfur at pH 0 where the electrochemical oxidation state +2 for sulfur puts thiosulfate| between S and HSO:
* Systematic oxidation state is chosen from close alternatives as a pedagogical description. An example is the oxidation state of phosphorus in HPO (structurally diprotic HPO(OH)) taken nominally as +3, while Allen electronegativities of phosphorus and hydrogen suggest +5 by a narrow margin that makes the two alternatives almost equivalent:
:Both alternative oxidation numbers for phosphorus make chemical sense, depending on which chemical property or reaction is emphasized. By contrast, a calculated alternative, such as the average (+4) does not. | 0 | Theoretical and Fundamental Chemistry |
Transcriptomics studies generate large amounts of data that have potential applications far beyond the original aims of an experiment. As such, raw or processed data may be deposited in public databases to ensure their utility for the broader scientific community. For example, as of 2018, the Gene Expression Omnibus contained millions of experiments. | 1 | Applied and Interdisciplinary Chemistry |
Tailings do not have to be stored in ponds or sent as slurries into oceans, rivers or streams. There is a growing use of the practice of dewatering tailings using vacuum or pressure filters so the tailings can then be stacked. This saves water which potentially reduces the impacts on the environment in terms of a reduction in the potential seepage rates, space used, leaves the tailings in a dense and stable arrangement and eliminates the long-term liability that ponds leave after mining is finished. However although there are potential merits to dry stacked tailings these systems are often cost prohibitive due to increased capital cost to purchase and install the filter systems and the increase in operating costs (generally associated electricity consumption and consumables such as filter cloth) of such systems. | 1 | Applied and Interdisciplinary Chemistry |
*1972–1975 – Associate Member, Viking Lander Science Team, NASA
*1979–1982 – – Member, Committee on Response Strategies to Unusual Chemical Hazards, Assembly of Life Sciences, National Research Council
*1982 – U.S. Coordinator, U.S.-Japan Joint Seminar on “Microcolumn Separation Methods and their Ancillary Techniques,” Honolulu, Hawaii
*1980–1984 – Member, Advisory Committee to the Analytical Chemistry Division, Oak Ridge National Laboratory
*1986 – Instructor, ACS Short Course on Supercritical Fluid Chromatography
*1988, 1990 – Organizing Committee, International Symposium, “Microcolumn Separation Methods,” Bloomington, IN and Aronberg, Sweden
*1988, 1991 – Scientific Committee, International Symposium, “HPLC 88” and “HPLC 92”
*1977–Pres. – Instructor, ACS Short Course on Capillary Gas Chromatography
*1978–Pres. – ACS Lecture Tour Speaker
*1990–Pres. – Scientific Committee, International Symposia on Capillary Chromatography
*1994 – Scientific Committee, Glycobiology: Analytical Methods
*2003 – Member of the Center for the Integrative Study of Animal Behavior, Indiana University
*2004 – Member of the Indiana University Cancer Center, IU School of Medicine | 0 | Theoretical and Fundamental Chemistry |
These increasing nitrogen and phosphorus nutrient inputs exert eutrophication pressures on coastal zones. These pressures vary geographically depending on the catchment activities and associated nutrient load. The geographical setting of the coastal zone is another important factor as it controls dilution of the nutrient load and oxygen exchange with the atmosphere. The effects of these eutrophication pressures can be seen in several different ways:
# There is evidence from satellite monitoring that the amounts of chlorophyll as a measure of overall phytoplankton activity are increasing in many coastal areas worldwide due to increased nutrient inputs.
# The phytoplankton species composition may change due to increased nutrient loadings and changes in the proportions of key nutrients. In particular the increases in nitrogen and phosphorus inputs, along with much smaller changes in silicon inputs, create changes in the ratio of nitrogen and phosphorus to silicon. These changing nutrient ratios drive changes in phytoplankton species composition, particularly disadvantaging silica rich phytoplankton species like diatoms compared to other species. This process leads to the development of nuisance algal blooms in areas such as the North Sea (see also OSPAR Convention) and the Black Sea. In some cases nutrient enrichment can lead to harmful algal blooms (HABs). Such blooms can occur naturally, but there is good evidence that these are increasing as a result of nutrient enrichment, although the causal linkage between nutrient enrichment and HABs is not straightforward.
# Oxygen depletion has existed in some coastal seas such as the Baltic for thousands of years. In such areas the density structure of the water column severely restricts water column mixing and associated oxygenation of deep water. However, increases in the inputs of bacterially degradable organic matter to such isolated deep waters can exacerbate such oxygen depletion in oceans. These areas of lower dissolved oxygen have increased globally in recent decades. They are usually connected with nutrient enrichment and resulting algal blooms. Climate change will generally tend to increase water column stratification and so exacerbate this oxygen depletion problem. An example of such coastal oxygen depletion is in the Gulf of Mexico where an area of seasonal anoxia more than 5000 square miles in area has developed since the 1950s. The increased primary production driving this anoxia is fueled by nutrients supplied by the Mississippi river. A similar process has been documented in the Black Sea.
# Hypolimnetic oxygen depletion can lead to summer "kills". During summer stratification, inputs or organic matter and sedimentation of primary producers can increase rates of respiration in the hypolimnion. If oxygen depletion becomes extreme, aerobic organisms (such as fish) may die, resulting in what is known as a "summer kill". | 1 | Applied and Interdisciplinary Chemistry |
In cell biology, protein kinase A (PKA) is a family of serine-threonine kinase whose activity is dependent on cellular levels of cyclic AMP (cAMP). PKA is also known as cAMP-dependent protein kinase (). PKA has several functions in the cell, including regulation of glycogen, sugar, and lipid metabolism. It should not be confused with 5'-AMP-activated protein kinase (AMP-activated protein kinase). | 1 | Applied and Interdisciplinary Chemistry |
Sensor-based sorting is a coarse particle separation technology applied in mining for the dry separation of bulk materials. The functional principle does not limit the technology to any kind of segment or mineral application but makes the technical viability mainly depend on the liberation characteristics at the size range , which is usually sorted. If physical liberation is present there is a good potential that one of the sensors available on industrial scale sorting machines can differentiate between valuable and non-valuable particles.
The separation is based on features measured with a detection technology that are used to derive a yes/no decision for actuation of usually pneumatic impulses. Sensor-based sorting is a disruptive technology in the mining industry which is universally applicable for all commodities. A comprehensive study examines both the technologys potential and its limitations, whilst providing a framework for application development and evaluation. All relevant aspects, from sampling to plant design and integration into mining and mineral processing systems, are covered. Other terminologies used in the industry include ore sorting, automated sorting, electronic sorting, and optical sorting'. | 0 | Theoretical and Fundamental Chemistry |
* Willard Libby's discovery of radiocarbon dating at the University of Chicago.
* Merck & Co.'s research on The Vitamin B Complex
* The discovery of Ivermectin | 1 | Applied and Interdisciplinary Chemistry |
In these cases, a plasmid is constructed in which the genes to be transferred are flanked by viral sequences that are used by viral proteins to recognize and package the viral genome into viral particles. This plasmid is inserted (usually by transfection) into a producer cell together with other plasmids (DNA constructs) that carry the viral genes required for the formation of infectious virions. In these producer cells, the viral proteins expressed by these packaging constructs bind the sequences on the DNA/RNA (depending on the type of viral vector) to be transferred and insert it into viral particles. For safety, none of the plasmids used contains all the sequences required for virus formation, so that simultaneous transfection of multiple plasmids is required to get infectious virions. Moreover, only the plasmid carrying the sequences to be transferred contains signals that allow the genetic materials to be packaged in virions so that none of the genes encoding viral proteins are packaged. Viruses collected from these cells are then applied to the cells to be altered. The initial stages of these infections mimic infection with natural viruses and lead to expression of the genes transferred and (in the case of lentivirus/retrovirus vectors) insertion of the DNA to be transferred into the cellular genome. However, since the transferred genetic material does not encode any of the viral genes, these infections do not generate new viruses (the viruses are "replication-deficient").
Some enhancers have been used to improve transduction efficiency such as polybrene, protamine sulfate, retronectin, and DEAE Dextran. | 1 | Applied and Interdisciplinary Chemistry |
In the special case where one hydrogen is replaced by deuterium (D) and another hydrogen by tritium (T), the methyl substituent becomes chiral. Methods exist to produce optically pure methyl compounds, e.g., chiral acetic acid (deuterotritoacetic acid ). Through the use of chiral methyl groups, the stereochemical course of several biochemical transformations have been analyzed. | 0 | Theoretical and Fundamental Chemistry |
* The remaining CGN codons are rare in Saccharomyces cerevisiae and absent in Candida glabrata.
* The AUA codon is common in the gene var1 coding for the single mitochondrial ribosomal protein, but rare in genes encoding the enzymes.
* The coding assignments of the AUA (Met or Ile) and CUU (possibly Leu, not Thr) are uncertain in Hansenula saturnus.
* The coding assignment of Thr to CUN is uncertain in Kluyveromyces thermotolerans. | 1 | Applied and Interdisciplinary Chemistry |
Journal of Photochemistry and Photobiology C: Photochemistry Reviews focusses on photochemistry literature reviews. It is the official journal of the Japanese Photochemistry Association and is published quarterly. The editor-in-chief is Noboru Kitamura. | 0 | Theoretical and Fundamental Chemistry |
Martin Albrecht (born December 12, 1971) is a Swiss chemist. He is Professor of Inorganic Chemistry at the Department of Chemistry, Biochemistry and Pharmacy at the University of Bern. He is known for his contribution to carbene chemistry, particularly with his work on 1,2,3-triazolylidene mesoionic carbene. | 0 | Theoretical and Fundamental Chemistry |
Many stationary phases are porous to provide greater surface area. Small pores provide greater surface area while larger pore size has better kinetics, especially for larger analytes. For example, a protein which is only slightly smaller than a pore might enter the pore but does not easily leave once inside. | 0 | Theoretical and Fundamental Chemistry |
In cellular biology, inclusions are diverse intracellular non-living substances (ergastic substances) that are not bound by membranes. Inclusions are stored nutrients/deutoplasmic substances, secretory products, and pigment granules. Examples of inclusions are glycogen granules in the liver and muscle cells, lipid droplets in fat cells, pigment granules in certain cells of skin and hair, and crystals of various types. Cytoplasmic inclusions are an example of a biomolecular condensate arising by liquid-solid, liquid-gel or liquid-liquid phase separation.
These structures were first observed by O. F. Müller in 1786. | 1 | Applied and Interdisciplinary Chemistry |
The drinking bird has been used in many fictional contexts to automatically press buttons. In The Simpsons episode "King-Size Homer", Homer used one to repeatedly press a key on a computer keyboard. Herb Powell also showed one to Homer as part of a demonstration regarding inventions in the episode "Brother, Can You Spare Two Dimes?". Two of them were used in the 1990 film Darkman to set off explosions. Drinking birds have appeared as part of a Rube Goldberg machine in the film Pee-wees Big Adventure and the Family Guy episode "8 Simple Rules for Buying My Teenage Daughter". In Bojack Horseman' an Alcoholics Anonymous attendee resembles a Drinking Bird.
Drinking birds have been featured as plot elements in the 1951 Merrie Melodies cartoon Putty Tat Trouble and the 1968 science fiction thriller The Power. They have also had minor appearances in several movies and TV shows, including mission briefings in two episodes of TVs original Mission: Impossible, the Woody Allen movie Sleeper, the 1979 science fiction film Alien (also referenced in Alien 3 and Alien: Covenant), the 1989 comedy When Harry Met Sally..., the 2005 film Robots, the 2008 film Max Payne, the 2010 film Megamind, the 2021 film Fortress',
and episodes of the American TV shows The Simpsons, Mad Men and Ed, Edd n Eddy. Episode 508 of Mystery Science Theater 3000 features a spoof of the drinking bird called the Bobbing Buzzard, which runs on carrion instead of water. In S4E11 of the comedy series Arrested Development, a delusional character hears the voice of God speaking through a drinking bird. In Episode 7 of Season 2, Headspace, of Ted Lasso on AppleTV, a non-functioning drinking bird is prominently displayed on the desk of the team psychologist.
Among video games, the drinking bird appeared as the "dunkin dragon" in the Sierra game Quest for Glory (1989) and in the Gremlin Interactive game Normality (1996). Porygon2, a Pokémon introduced in Generation II (Pokémon Gold and Silver), resembles a drinking bird, and in 3D Pokémon games, it moves its head in a "dipping" motion. More recently, in the game Quantum Conundrum (2012), one of the main gameplay mechanics is a drinking bird that is used as a timer to press buttons. In the 2014 Creative Assembly video game Alien: Isolation, drinking birds are frequently seen on desks across the games main setting, Sevastopol Station.
In Australian contemporary playwright John Romerils play The Floating World, drinking birds are a symbolic prop which represent the progression of Les insanity. They are referred to as "dippy birds" and are perhaps used to symbolize insanity due to Romeril's opinion that they are insane for their uselessness and repeatability. | 0 | Theoretical and Fundamental Chemistry |
Throughout the years, Alvero-Al Mahdi has been recognized in various awards from both the Philippines; as well as, the UAE.
* Adamson University Most Outstanding Alumna 2008 (Dubai Chapter)
* Emirates Businesswoman Awardee Professional Category 2008 (UAE)
* Adamson University Most Outstanding Alumna 2009
* Woman of Substance 2009 Honoree
* Professional Regulation Commission Most Distinguished Chemical Engineer 2009
* Kuwentong Diyerto "Bida sa Negosyo" Awardee 2009
* Blas F. Ople Awardee 2009
* Bagong Bayani Most Outstanding Employee Awardee 2009
* Most Outstanding Adamsonian Award 2012
* Presidential Award for Filipinos Overseas, Pamana ng Pilipino Award 2012
* Emirates Woman, Woman of the Year Award, Visionary Category 2013
* "100 Most Influential Filipina Around the World, Thought and Innovation Leaders Category 2013
* Gr8t Women Awards in the Middle East, Special Mention in the Field of Geoscience 2014 | 1 | Applied and Interdisciplinary Chemistry |
The Swedish Lancashire hearth consisted of a rectangular closed furnace with a chimney (8 metres high) at one end and a working arch in front of the hearth proper at the other. Pig iron was charged through a door at the foot of the chimney and stacked on an iron-clad bridge so that it could be heated by the waste gases from the hearth. The hearth was blown through a single water-cooled tuyere with pre-heated air. The hearth consisted of a rectangular box of iron plates, the bottom plate being water-cooled. Surplus slag was removed with a shovel between finings, but some was left to help the process. Pig stacked on the bridge at the back of the hearth was then pulled forward with a hook and charcoal added. The blast was then turned on and fining began.
When the pigs began to melt, rabelling began (as in the Walloon process) using two bars of iron one to stir the iron and the other to lift it back into the blast. Periodically the tuyere had to be cleaned of matter adhering to it with a third bar. Finally, the iron was gathered into a loop which was lifted out of the hearth with a heavier bar and tongs, and taken to the shingling hammer.
The process was more fuel-efficient and more productive than its predecessors. | 1 | Applied and Interdisciplinary Chemistry |
The practice of cut-and-fill was widely utilized to construct tracks along rolling terrain across the British Isles. It was later applied in the construction of new dwellings for returning veterans in Ireland at the end of World War II. This application was developed by Irish railway engineer Lachlan J. Boland, who saw the benefits of introducing railway practices to residential construction. | 1 | Applied and Interdisciplinary Chemistry |
To correctly solve the -phase momentum equation, a feasible set of closure relations must be considered to include all the possible interactions between the phases, expressed as a momentum transfer per unit volume at the phase interface. Interfacial momentum forces are added as a source term in the momentum equation and can be divided into drag and non-drag forces. The drag force has a dominant role and can be considered as the most important contribution in bubbly flows. It reflects the resistance opposing bubble motion relative to the surrounding fluid.
The non drag forces are the lift, turbulent dispersion, wall lubrication and virtual mass forces:
* Lift force: force perpendicular to bubble motion. It results from the pressure and stress acting on the bubble surface. Experimental and numerical studies show that the lift force change sign depending on the bubble diameter. For small bubbles, the lift force acts in the direction of decreasing liquid velocity, which is, in the case of batch or co-current mode, toward the pipe wall. Conversely, when large bubbles are considered, the lift force pushes the bubbles toward the center of the column. The change in sign of the lift force occurs at a bubble diameter of approximately 5.8 mm.
* Turbulent dispersion: it accounts for the fluctuation in the liquid velocity that affects the dispersed phase by scattering it. The turbulent eddies redistribute the bubbles in the lateral direction from the high-concentration to the low-concentration bubble region. The turbulent dispersion force modulates the peaks of small bubbles near the wall pipes and spreads out large bubbles.
* Wall lubrication: force due to the surface tension. It prevents the bubbles from touching the walls, ensuring zero presence of bubbles near vertical walls (found experimentally).
* Virtual mass force: it arises from the relative acceleration of an immersed moving object to its surrounding fluid. Its effect is significant when the liquid phase density is much higher than the gas phase.
All the interfacial forces can be added to the numerical model using suitable correlations derived from experimental studies. | 1 | Applied and Interdisciplinary Chemistry |
Certain constituents of volcanic gases may show very early signs of changing conditions at depth, making them a powerful tool to predict imminent unrest. Used in conjunction with monitoring data on seismicity and deformation, correlative monitoring gains great efficiency. Volcanic gas monitoring is a standard tool of any volcano observatory. Unfortunately, the most precise compositional data still require dangerous field sampling campaigns. However, remote sensing techniques have advanced tremendously through the 1990s. The Deep Earth Carbon Degassing Project is employing Multi-GAS remote sensing to monitor 9 volcanoes on a continuous basis. | 1 | Applied and Interdisciplinary Chemistry |
In thermodynamics, the Gibbs free energy or Helmholtz free energy is essentially the energy of a chemical reaction "free" or available to do external work. Historically, the "free energy" is a more advanced and accurate replacement for the thermochemistry term “affinity” used by chemists of olden days to describe the “force” that caused chemical reactions. The term dates back to at least the time of Albertus Magnus in 1250.
According to Nobelist and chemical engineering professor Ilya Prigogine: “as motion was explained by the Newtonian concept of force, chemists wanted a similar concept of ‘driving force’ for chemical change? Why do chemical reactions occur, and why do they stop at certain points? Chemists called the ‘force’ that caused chemical reactions affinity, but it lacked a clear definition.
During the entire 18th century, the dominant view in regard to heat and light was that put forward by Isaac Newton, called the “Newtonian hypothesis”, which stated that light and heat are forms of matter attracted or repelled by other forms of matter, with forces analogous to gravitation or to chemical affinity.
In the 19th century, the French chemist Marcellin Berthelot and the Danish chemist Julius Thomsen had attempted to quantify chemical affinity using heats of reaction. In 1875, after quantifying the heats of reaction for a large number of compounds, Berthelot proposed the “principle of maximum work” in which all chemical changes occurring without intervention of outside energy tend toward the production of bodies or of a system of bodies which liberate heat. | 0 | Theoretical and Fundamental Chemistry |
Observed values of viscosity vary over several orders of magnitude, even for common substances (see the order of magnitude table below). For instance, a 70% sucrose (sugar) solution has a viscosity over 400 times that of water, and 26,000 times that of air. More dramatically, pitch has been estimated to have a viscosity 230 billion times that of water. | 1 | Applied and Interdisciplinary Chemistry |
The compound crystallizes in the monoclinic system, cell parameters a = 3.400 Å, b = 5.156 Å, c = 9.055 Å, β = 95.60°, Z = 4.
Lithium oxalate decomposes when heated at : | 0 | Theoretical and Fundamental Chemistry |
The mechanism of the Boekelheide reaction begins by an acyl transfer from the trifluoroacetic anhydride to the N-oxide oxygen. The α-methyl carbon is then deprotonated by the trifluoroacetate anion. This sets the molecule up for a [3.3]-sigmatropic rearrangement which furnishes the trifluoroacetylated methylpyridine. Hydrolysis of the trifluoroacetate releases the hydroxymethylpyridine. | 0 | Theoretical and Fundamental Chemistry |
Although it is estimated that about 35 primordial nuclides are radioactive (list below), it becomes very difficult to determine the exact total number of radioactive primordials, because the total number of stable nuclides is uncertain. There exist many extremely long-lived nuclides whose half-lives are still unknown, in fact, all nuclides heavier than dysprosium-164 are theoretically radioactive. For example, it is predicted theoretically that all isotopes of tungsten, including those indicated by even the most modern empirical methods to be stable, must be radioactive and can decay by alpha emission, but this could only be measured experimentally for . Similarly, all four primordial isotopes of lead are expected to decay to mercury, but the predicted half-lives are so long (some exceeding 10 years) that such decays could hardly be observed in the near future. Nevertheless, the number of nuclides with half-lives so long that they cannot be measured with present instruments—and are considered from this viewpoint to be stable nuclides—is limited. Even when a "stable" nuclide is found to be radioactive, it merely moves from the stable to the unstable list of primordial nuclides, and the total number of primordial nuclides remains unchanged. For practical purposes, these nuclides may be considered stable for all purposes outside specialized research. | 0 | Theoretical and Fundamental Chemistry |
Following on from ferrocene—the first sandwich compound with a central Fe atom coordinated to two parallel cyclopentadienyl rings—names for compounds with similar structures such as osmocene and vanadocene are in common usage. The recommendation is that the name-ending ocene should be restricted to compounds where there are discrete molecules of bis(η-cyclopentadienyl)metal (and ring-substituted analogues), where the cyclopentadienyl rings are essentially parallel, and the metal is in the d-block. The terminology does NOT apply to compounds of the s- or p-block elements such as Ba(CH) or Sn(CH).
Examples of compounds that meet the criteria are:
* vanadocene, [V(η-CH)]
* chromocene, [Cr(η-CH)]
* cobaltocene, [Co(η-CH)]
* rhodocene, [Rh(η-CH)]
* nickelocene, [Ni(η-CH)]
* ruthenocene, [Ru(η-CH)]
* osmocene, [Os(η-CH)]
* manganocene, [Mn(η-CH)]
* rhenocene, [Re(η-CH)].
Examples of compounds that should not be named as metallocenes are:
* CHTi
* [Ti(η-CH)Cl] is properly named dichloridobis(η-cyclopentadienyl)titanium NOT titanocene dichloride | 0 | Theoretical and Fundamental Chemistry |
Vanillin is an organic compound with the molecular formula . It is a phenolic aldehyde. Its functional groups include aldehyde, hydroxyl, and ether. It is the primary component of the extract of the vanilla bean. Synthetic vanillin is now used more often than natural vanilla extract as a flavoring in foods, beverages, and pharmaceuticals.
Vanillin and ethylvanillin are used by the food industry; ethylvanillin is more expensive, but has a stronger note. It differs from vanillin by having an ethoxy group (−O−CHCH) instead of a methoxy group (−O−CH).
Natural vanilla extract is a mixture of several hundred different compounds in addition to vanillin. Artificial vanilla flavoring is often a solution of pure vanillin, usually of synthetic origin. Because of the scarcity and expense of natural vanilla extract, synthetic preparation of its predominant component has long been of interest. The first commercial synthesis of vanillin began with the more readily available natural compound eugenol (4-allyl-2-methoxyphenol). Today, artificial vanillin is made either from guaiacol or lignin.
Lignin-based artificial vanilla flavoring is alleged to have a richer flavor profile than that from guiacol-based artificial vanilla; the difference is due to the presence of acetovanillone, a minor component in the lignin-derived product that is not found in vanillin synthesized from guaiacol. | 0 | Theoretical and Fundamental Chemistry |
The analysis of ratios of carbon-13 to carbon-12 along the length of a single elephant hair led Cerling and his crew to understand the elephants' diet. During the wet season, after the grass had grown long enough for elephants to grab with their trunks, their tail hair showed the presence of different form of carbon, indicating a high amount of high-protein grass. On the other hand, during the dry season, the results obtained by the analysis of the hair pointed out how elephants had switched over to shrubs and trees. | 0 | Theoretical and Fundamental Chemistry |
Thomas Anderson (2 July 1819 – 2 November 1874) was a 19th-century Scottish chemist. In 1853 his work on alkaloids led him to discover the correct formula/composition for codeine. In 1868 he discovered pyridine and related organic compounds such as picoline through studies on the distillation of bone oil and other animal matter.
As well as his work on organic chemistry, Anderson made important contributions to agricultural chemistry, writing over 130 reports on soils, fertilisers and plant diseases. He kept abreast of all areas of science, and was able to advise his colleague Joseph Lister on Pasteur's germ theory and the use of carbolic acid as an antiseptic. | 0 | Theoretical and Fundamental Chemistry |
In spatial scanning, each two-dimensional (2-D) sensor output represents a full slit spectrum (x, λ). Hyperspectral imaging (HSI) devices for spatial scanning obtain slit spectra by projecting a strip of the scene onto a slit and dispersing the slit image with a prism or a grating. These systems have the drawback of having the image analyzed per lines (with a push broom scanner) and also having some mechanical parts integrated into the optical train. With these line-scan cameras, the spatial dimension is collected through platform movement or scanning. This requires stabilized mounts or accurate pointing information to reconstruct the image. Nonetheless, line-scan systems are particularly common in remote sensing, where it is sensible to use mobile platforms. Line-scan systems are also used to scan materials moving by on a conveyor belt. A special case of line scanning is point scanning (with a whisk broom scanner), where a point-like aperture is used instead of a slit, and the sensor is essentially one-dimensional instead of 2-D. | 0 | Theoretical and Fundamental Chemistry |
By the early 1950s it was known from metabolic labeling studies using radioactive phosphate that phosphate groups attached to phosphoproteins inside cells can sometimes undergo rapid exchange of new phosphate for old. In order to perform experiments that would allow isolation and characterization of the enzymes involved in attaching and removing phosphate from proteins, there was a need for convenient substrates for protein kinases and protein phosphatases. Casein has been used as a substrate since the earliest days of research on protein phosphorylation. By the late 1960s, cyclic AMP-dependent protein kinase had been purified, and most attention was centered on kinases and phosphatases that could regulate the activity of important enzymes. Casein kinase activity associated with the endoplasmic reticulum of mammary glands was first characterized in 1974, and its activity was shown to not depend on cyclic AMP. | 1 | Applied and Interdisciplinary Chemistry |
The main parts of the most usual type of valve are the body and the bonnet. These two parts form the casing that holds the fluid going through the valve. | 1 | Applied and Interdisciplinary Chemistry |
Galvanization or galvanizing (also spelled galvanisation or galvanising) is the process of applying a protective zinc coating to steel or iron, to prevent rusting. The most common method is hot-dip galvanizing, in which the parts are coated by submerging them in a bath of hot, molten zinc. | 1 | Applied and Interdisciplinary Chemistry |
Henry Cavendish, despite not being the first to replace water in the trough with mercury, was among the first to observe that fixed air was insoluble over mercury and therefore could be collected more efficiently using the adapted instrument. He also characterized fixed air (CO) and inflammable air (H). Inflammable air was one of the first gases isolated and discovered using the pneumatic trough. However, he did not exploit his own idea to its limit, and therefore did not use the mercury pneumatic trough to its full extent. Cavendish is credited with nearly correctly analyzing the content of gases in the atmosphere. Cavendish also showed that inflammable air and atmospheric air could be combined and heated to produce water in 1784. | 1 | Applied and Interdisciplinary Chemistry |
The images above give an indication of the compositions and scale (dimensions) associated with MAs, though these just begin to touch on the complexity of the structures; in principle, each living cell is composed of MAs, but is itself an MA as well. In the examples and other such complexes and assemblies, MAs are each often millions of daltons in molecular weight (megadaltons, i.e., millions of times the weight of a single, simple atom), though still having measurable component ratios (stoichiometries) at some level of precision. As alluded to in the image legends, when properly prepared, MAs or component subcomplexes of MAs can often be crystallized for study by protein crystallography and related methods, or studied by other physical methods (e.g., spectroscopy, microscopy).
Virus structures were among the first studied MAs; other biologic examples include ribosomes (partial image above), proteasomes, and translation complexes (with protein and nucleic acid components), procaryotic and eukaryotic transcription complexes, and nuclear and other biological pores that allow material passage between cells and cellular compartments. Biomembranes are also generally considered MAs, though the requirement for structural and spatial definition is modified to accommodate the inherent molecular dynamics of membrane lipids, and of proteins within lipid bilayers. | 1 | Applied and Interdisciplinary Chemistry |
In electrochemistry, and more generally in solution chemistry, a Pourbaix diagram, also known as a potential/pH diagram, E–pH diagram or a pE/pH diagram, is a plot of possible thermodynamically stable phases (i.e., at chemical equilibrium) of an aqueous electrochemical system. Boundaries (50 %/50 %) between the predominant chemical species (aqueous ions in solution, or solid phases) are represented by lines. As such a Pourbaix diagram can be read much like a standard phase diagram with a different set of axes. Similarly to phase diagrams, they do not allow for reaction rate or kinetic effects. Beside potential and pH, the equilibrium concentrations are also dependent upon, e.g., temperature, pressure, and concentration. Pourbaix diagrams are commonly given at room temperature, atmospheric pressure, and molar concentrations of 10 and changing any of these parameters will yield a different diagram.
The diagrams are named after Marcel Pourbaix (1904–1998), the Russian-born Belgian chemist who invented them. | 0 | Theoretical and Fundamental Chemistry |
The most obvious way to maintain the ecosystem services that peatland provides is conservation of intact peatlands. This is even more true given the limited success of restoration projects especially in tropical peatlands. The conserved peatland still holds value for humans and hence provides a number of ecosystem services e.g. carbon storage, water storage and discharge. Conserving peatlands also avoids costly investments. Conservation is suggested to be a very cost-effective management practice for peatlands. The most obvious ecosystem services that the conservation management provides - i.e. carbon storage and water storage - are not easily priced on the market. Therefore, peatland conservation may need to be subsidised.
To rewet peatland and thereby restore the water table level is the first step in the restoration. The intention is to recreate the hydrological function and processes of the peatland. This takes a longer time than may be expected. Studies have found that rewetted previously drained peatland had the hydrological functions - e.g. water storage and discharge capacity - somewhere between a drained and an intact peatland six years after the restoration.
Undrained peatlands are recommended to be left for conservation and not used for paludiculture. Drained peatlands, on the other hand, can be rewetted and used for paludiculture often using traditional knowledge together with new science. However local communities, especially in the tropics, maintain their livelihood by draining and using the peatland in various ways e.g. agriculture, grazing, and peat mining. Paludiculture can be a way to restore degraded and drained peatlands as well as maintaining an outcome for the local community. For example, studies of Sphagnum cultivation on re-wetted peat bogs in Germany shows a significant decrease of greenhouse gas emission compared to a control with irrigated ditches. The economic feasibility of Sphagnum cultivation on peat bogs are however still unclear. The basis for paludiculture is however very different in the south, among other things because of higher population and economic pressure on peatland. | 1 | Applied and Interdisciplinary Chemistry |
Atomic force microscopy (AFM) or scanning force microscopy (SFM) is a very-high-resolution type of scanning probe microscopy (SPM), with demonstrated resolution on the order of fractions of a nanometer, more than 1000 times better than the optical diffraction limit. | 0 | Theoretical and Fundamental Chemistry |
Compounds with disphenoidal (see-saw) geometry have two types of ligands: axial and equatorial. The axial pair lie along a common bond axis so that are related by a bond angle of 180°. The equatorial pair of ligands is situated in a plane orthogonal to the axis of the axial pair. Typically the bond distance to the axial ligands is longer than to the equatorial ligands. The ideal angle between the axial ligands and the equatorial ligands is 90°; whereas the ideal angle between the two equatorial ligands themselves is 120°.
Disphenoidal molecules, like trigonal bipyramidal ones, are subject to Berry pseudorotation in which the axial ligands move to equatorial positions and vice versa. This exchange of positions results in similar time-averaged environments for the two types of ligands. Thus, the F NMR spectrum of SF (like that of PF) consists of single resonance near room temperature. The four atoms in motion act as a lever about the central atom; for example, the four fluorine atoms of sulfur tetrafluoride rotate around the sulfur atom. | 0 | Theoretical and Fundamental Chemistry |
The formulation of a coating depends primarily on the function required of the coating and also on aesthetics required such as color and gloss. The four primary ingredients are the resin (or binder), solvent which maybe water (or solventless), pigment(s) and additives. Research is ongoing to remove heavy metals from coating formulations completely.
For example on the basis of experimental and epidemiological evidence, it has been classified by the IARC (International Agency for Research on Cancer) as a human carcinogen by inhalation (class I) ([https://www.sicurezza.com/ispesl ISPESL], 2008). | 1 | Applied and Interdisciplinary Chemistry |
Caesium-137 has a half-life of about 30.05 years.
About 94.6% decays by beta emission to a metastable nuclear isomer of barium: barium-137m (Ba, Ba-137m). The remainder directly populates the ground state of Ba, which is stable. Barium-137m has a half-life of about 153 seconds, and is responsible for all of the gamma ray emissions in samples of Cs. Barium-137m decays to the ground state by emission of photons having energy 0.6617 MeV. A total of 85.1% of Cs decay generates gamma ray emission in this manner. One gram of Cs has an activity of 3.215 terabecquerel (TBq). | 0 | Theoretical and Fundamental Chemistry |
The Sun has a large , of order 10. Dissipative affects are generally small, and there is no difficulty in maintaining a magnetic field against diffusion.
For the Earth, is estimated to be of order 10
Dissipation is more significant, but a magnetic field is supported by motion in the liquid iron outer core. There are other bodies in the solar system that have working dynamos, e.g. Jupiter, Saturn, and Mercury, and others that do not, e.g. Mars, Venus and the Moon.
The human length scale is very small so that typically . The generation of magnetic field by the motion of a conducting fluid has been achieved in only a handful of large experiments using mercury or liquid sodium. | 1 | Applied and Interdisciplinary Chemistry |
In many magnetic ferrous alloys, the Curie point, the temperature at which magnetic materials cease to behave magnetically, occurs at nearly the same temperature as the austenite transformation. This behavior is attributed to the paramagnetic nature of austenite, while both martensite and ferrite are strongly ferromagnetic. | 1 | Applied and Interdisciplinary Chemistry |
The mass absorption coefficient is equal to the molar absorption coefficient divided by the molar mass of the absorbing species.
where
* = Mass absorption coefficient
* = Molar absorption coefficient
* = Molar mass of the absorbing species | 0 | Theoretical and Fundamental Chemistry |
STAT2 has been shown to interact with:
* CREB-binding protein,
* IFNAR1
* IFNAR2,
* IRF9,
* MED14,
* SMARCA4, and
* STAT1. | 1 | Applied and Interdisciplinary Chemistry |
Sticking coefficient is the term used in surface physics to describe the ratio of the number of adsorbate atoms (or molecules) that adsorb, or "stick", to a surface to the total number of atoms that impinge upon that surface during the same period of time. Sometimes the symbol S is used to denote this coefficient, and its value is between 1 (all impinging atoms stick) and 0 (no atoms stick). The coefficient is a function of surface temperature, surface coverage (θ) and structural details as well as the kinetic energy of the impinging particles. The original formulation was for molecules adsorbing from the gas phase and the equation was later extended to adsorption from the liquid phase by comparison with molecular dynamics simulations. For use in adsorption from liquids the equation is expressed based on solute density (molecules per volume) rather than the pressure. | 0 | Theoretical and Fundamental Chemistry |
Even though enamines are more nucleophilic than their enol counterparts, they can still react selectively, rendering them useful for alkylation reactions. The enamine nucleophile can attack haloalkanes to form the alkylated iminium salt intermediate which then hydrolyzes to regenerate a ketone (a starting material in enamine synthesis). This reaction was pioneered by Gilbert Stork, and is sometimes referred to by the name of its inventor (the Stork enamine alkylation). Analogously, this reaction can be used as an effective means of acylation. A variety of alkylating and acylating agents including benzylic, allylic halides can be used in this reaction. | 0 | Theoretical and Fundamental Chemistry |
Liquefaction of gases is physical conversion of a gas into a liquid state (condensation). The liquefaction of gases is a complicated process that uses various compressions and expansions to achieve high pressures and very low temperatures, using, for example, turboexpanders. | 0 | Theoretical and Fundamental Chemistry |
* The burning of long-buried fossil fuels releases containing carbon of different isotopic ratios to those of living plants, enabling distinction between natural and human-caused contributions to concentration.
* There are higher atmospheric concentrations in the Northern Hemisphere, where most of the world's population lives (and emissions originate from), compared to the southern hemisphere. This difference has increased as anthropogenic emissions have increased.
* Atmospheric O levels are decreasing in Earth's atmosphere as it reacts with the carbon in fossil fuels to form . | 1 | Applied and Interdisciplinary Chemistry |
Piperacillin irreversibly binds to the enzyme penicillin-binding proteins, inhibiting the biosynthesis of bacterial cell walls. | 0 | Theoretical and Fundamental Chemistry |
The way bacteriorhodopsin generates a proton gradient in Archaea is through a proton pump. The proton pump relies on proton carriers to drive protons from the side of the membrane with a low H concentration to the side of the membrane with a high H concentration. In bacteriorhodopsin, the proton pump is activated by absorption of photons of 568nm wavelength, which leads to isomerization of the Schiff base (SB) in retinal forming the K state. This moves SB away from Asp85 and Asp212, causing H transfer from the SB to Asp85 forming the M1 state. The protein then shifts to the M2 state by separating Glu204 from Glu194 which releases a proton from Glu204 into the external medium. The SB is reprotonated by Asp96 which forms the N state. It is important that the second proton comes from Asp96 since its deprotonated state is unstable and rapidly reprotonated with a proton from the cytosol. The protonation of Asp85 and Asp96 causes re-isomerization of the SB, forming the O state. Finally, bacteriorhodopsin returns to its resting state when Asp85 releases its proton to Glu204. | 0 | Theoretical and Fundamental Chemistry |
When the transition involves more than one charged particle, the transition dipole moment is defined in an analogous way to an electric dipole moment: The sum of the positions, weighted by charge. If the ith particle has charge q and position operator r, then the transition dipole moment is: | 0 | Theoretical and Fundamental Chemistry |
Metal carbonyls are used in several industrial processes. Perhaps the earliest application was the extraction and purification of nickel via nickel tetracarbonyl by the Mond process (see also carbonyl metallurgy).
By a similar process carbonyl iron, a highly pure metal powder, is prepared by thermal decomposition of iron pentacarbonyl. Carbonyl iron is used inter alia for the preparation of inductors, pigments, as dietary supplements, in the production of radar-absorbing materials in the stealth technology, and in thermal spraying. | 0 | Theoretical and Fundamental Chemistry |
Boiling systems are those in which liquid coolant absorbs energy from a heated solid surface and undergoes a change in phase. In flow boiling systems, the saturated fluid progresses through a series of flow regimes as vapor quality is increased. In systems that utilize boiling, the heat transfer rate is significantly higher than if the fluid were a single phase (i.e. all liquid or all vapor). The more efficient heat transfer from the heated surface is due to heat of vaporization and sensible heat. Therefore, boiling heat transfer has played an important role in industrial heat transfer processes such as macroscopic heat transfer exchangers in nuclear and fossil power plants, and in microscopic heat transfer devices such as heat pipes and microchannels for cooling electronic chips.
The use of boiling as a means of heat removal is limited by a condition called critical heat flux (CHF). The most serious problem that can occur around CHF is that the temperature of the heated surface may increase dramatically due to significant reduction in heat transfer. In industrial applications such as electronics cooling or instrumentation in space, the sudden increase in temperature may possibly compromise the integrity of the device. | 0 | Theoretical and Fundamental Chemistry |
Moissan contributed to the development of the electric arc furnace, which opened several paths to developing and preparing new compounds, and attempted to use pressure to produce synthetic diamonds from the more common form of carbon. He also used the furnace to synthesize the borides and carbides of numerous elements. Calcium carbide was a noticeable accomplishment as this paved the way for the development of the chemistry of acetylene. In 1893, Moissan began studying fragments of a meteorite found in Meteor Crater near Diablo Canyon in Arizona. In these fragments he discovered minute quantities of a new mineral and, after extensive research, Moissan concluded that this mineral was made of silicon carbide. In 1905, this mineral was named moissanite, in his honor. In 1903 Moissan was elected member of the International Atomic Weights Committee where he served until his death. | 0 | Theoretical and Fundamental Chemistry |
For efficient ridged mirrors, both estimates above should predict high reflectivity. This implies reduction of both, width, of the ridges and the period, . The width of the ridges cannot be smaller than the size of an atom; this sets the limit of performance of the ridged mirrors. | 0 | Theoretical and Fundamental Chemistry |
The secular dipolar coupling Hamiltonian of two spins, and is given by:
where
* is the reduced Planck constant.
* and are the gyromagnetic ratios of spin and spin respectively.
* is the inter-spin distance.
* is the angle between the inter-spin vector and the external magnetic field.
* and are vectors of spin operators.
The above equation can be rewritten in the following form:
where
In isotropic solution molecular tumbling reduces the average value of to zero. We thus observe no dipolar coupling. If the solution is not isotropic then the average value of may be different from zero, and one may observe residual couplings.
RDC can be positive or negative, depending on the range of angles that are sampled.
In addition to static distance and angular information, RDCs may contain information about a molecule's internal motion. To each atom in a molecule one can associate a motion tensor B, that may be computed from RDCs according to the following relation:
where A is the molecular alignment tensor.
The rows of B contain the motion tensors for each atom. The motion tensors also have five degrees of freedom. From each motion tensor, 5 parameters of interest can be computed. The variables S, η, α, β and γ are used to denote these 5 parameters for atom i. S is the magnitude of atom i’s motion; η is a measure of the anisotropy of atom i’s motion; α and β are related to the polar coordinates of the bond vector expressed in the initial arbitrary reference frame (i.e., the PDB frame). If the motion of the atom is anisotropic (i.e., η = 0), the final parameter, γ measures the principal orientation of the motion.
Note that the RDC-derived motion parameters are local measurements. | 0 | Theoretical and Fundamental Chemistry |
Exposure to MAM before birth increases susceptibility to epileptic seizures caused by flurothyl. Prenatal MAM exposure in rats results in a model of brain malformation. In some MAM animals, video-EEG monitoring has documented the presence of spontaneous electrographic seizure activity In some epilepsy rat models, MAM is administered at the fifteenth gestational day. Previous studies have found impaired cognitive function in GD15 MAM rats, and a reduced seizure threshold. At the cellular level, dysplastic hippocampal neurons in the MAM model were shown to have reduced potassium current function and expression for the Kv4.2 channel subunit These findings may contribute to the spontaneous seizures and reduced seizure thresholds seen in this model. | 1 | Applied and Interdisciplinary Chemistry |
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