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FSL Kode constructs have been used for research and development, diagnostic products, and are currently being investigated as potential therapeutic agents. | 1 | Applied and Interdisciplinary Chemistry |
Ampicillin is in the penicillin group of beta-lactam antibiotics and is part of the aminopenicillin family. It is roughly equivalent to amoxicillin in terms of activity. Ampicillin is able to penetrate gram-positive and some gram-negative bacteria. It differs from penicillin G, or benzylpenicillin, only by the presence of an amino group. This amino group, present on both ampicillin and amoxicillin, helps these antibiotics pass through the pores of the outer membrane of gram-negative bacteria, such as Escherichia coli, Proteus mirabilis, Salmonella enterica, and Shigella.
Ampicillin acts as an irreversible inhibitor of the enzyme transpeptidase, which is needed by bacteria to make the cell wall. It inhibits the third and final stage of bacterial cell wall synthesis in binary fission, which ultimately leads to cell lysis; therefore, ampicillin is usually bacteriolytic. | 0 | Theoretical and Fundamental Chemistry |
Applying the S&S technology platform in modern clinical genomics research hasadvance diagnosis and treatment of human diseases.
In the modern era of Next Generation Sequencing (NGS) technology, S&S is applied in clinical practice extensively. Clinicians and molecular diagnostic laboratories apply S&S using various computational tools including HSF, SSF, and Alamut. It is aiding in the discovery of genes and mutations in patients whose disease are stratified or when the disease in a patient is unknown based on clinical investigations.
In this context, S&S has been applied on cohorts of patients in different ethnic groups with various cancers and inherited disorders. A few examples are given below. | 1 | Applied and Interdisciplinary Chemistry |
If a mixture of gases is being considered, and each gas has its own (attraction between molecules) and (volume occupied by molecules) values, then and for the mixture can be calculated as
: = total number of moles of gas present,
: for each , = number of moles of gas present, and
: or
: or
and the rule of adding partial pressures becomes invalid if the numerical result of the equation is significantly different from the ideal gas equation . | 0 | Theoretical and Fundamental Chemistry |
For an introduction to the theory of electron diffraction, see part 2 of Williams and Carter's Transmission Electron Microscopy text
While it is clear that precession reduces many of the dynamical diffraction effects that plague other forms of electron diffraction, the resulting patterns cannot be considered purely kinematical in general. There are models that attempt to introduce corrections to convert measured PED patterns into true kinematical patterns that can be used for more accurate direct methods calculations, with varying degrees of success. Here, the most basic corrections are discussed. In purely kinematical diffraction, the intensities of various reflections, , are related to the square of the amplitude of the structure factor, by the equation:
where g is the reciprocal space magnitude of the reflection in question and R is the radius of the Laue circle, usually taken to be equal to φ. While this correction accounts for the integration over the excitation error, it takes no account for the dynamical effects that are ever-present in electron diffraction. This has been accounted for using a two-beam correction following the form of the Blackman correction originally developed for powder x-ray diffraction. Combining this with the aforementioned Lorentz correction yields:
where , is the sample thickness, and is the wave-vector of the electron beam. is the Bessel function of zeroeth order.
This form seeks to correct for both geometric and dynamical effects, but is still only an approximation that often fails to significantly improve the kinematic quality of the diffraction pattern (sometimes even worsening it). More complete and accurate treatments of these theoretical correction factors have been shown to adjust measured intensities into better agreement with kinematical patterns. For details, see Chapter 4 of reference.
Only by considering the full dynamical model through multislice calculations can the diffraction patterns generated by PED be simulated. However, this requires the crystal potential to be known, and thus is most valuable in refining the crystal potentials suggested through direct methods approaches. The theory of precession electron diffraction is still an active area of research, and efforts to improve on the ability to correct measured intensities without a priori knowledge are ongoing. | 0 | Theoretical and Fundamental Chemistry |
Similar to the CD V-715, the CD V-720 is a fixed-position ionization chamber survey meter. Unlike any other survey meter, however, this unit has a movable beta shield on the bottom of the unit for detecting high levels of beta radiation. When slid to the open position, beta particles are allowed to directly penetrate the ionization chamber. With the beta shield closed, only gamma rays can penetrate both the shield and ionization chamber. This meter reads from 1 R/h to 500 R/h (×1, ×10 and ×100 scales). The CD V-720 was produced in 4 models (1, 2, 3, and 3A), Chatham made the model 1, Landeds Fray and Clark made the model 3 (along with Victoreen Instruments), and Victoreen Instruments made all other models. All but the Victoreen model 3 and model 3A used a combination of D and 22.5 volt B batteries, while the Victoreen models 3 and 3A just used 2 D batteries. By 1962 113,231 had been procured, but in September 1985 FEMA declared all models except the Victoreen model 3 and model 3A obsolete. | 0 | Theoretical and Fundamental Chemistry |
In a chemical structural formula, an organic substituent such as methyl, ethyl, or aryl can be written as R (or R, R, etc.) It is a generic placeholder, the R derived from radical or rest, which may replace any portion of the formula as the author finds convenient. The first to use this symbol was Charles Frédéric Gerhardt in 1844.
The symbol X is often used to denote electronegative substituents such as the halides. | 0 | Theoretical and Fundamental Chemistry |
In chemical thermodynamics, the reaction quotient (Q or just Q) is a dimensionless quantity that provides a measurement of the relative amounts of products and reactants present in a reaction mixture for a reaction with well-defined overall stoichiometry at a particular point in time. Mathematically, it is defined as the ratio of the activities (or molar concentrations) of the product species over those of the reactant species involved in the chemical reaction, taking stoichiometric coefficients of the reaction into account as exponents of the concentrations. In equilibrium, the reaction quotient is constant over time and is equal to the equilibrium constant.
A general chemical reaction in which α moles of a reactant A and β moles of a reactant B react to give ρ moles of a product R and σ moles of a product S can be written as
The reaction is written as an equilibrium even though, in many cases, it may appear that all of the reactants on one side have been converted to the other side. When any initial mixture of A, B, R, and S is made, and the reaction is allowed to proceed (either in the forward or reverse direction), the reaction quotient Q, as a function of time t, is defined as
where {X} denotes the instantaneous activity of a species X at time t.
A compact general definition is
where П denotes the product across all j-indexed variables, a(t) is the activity of species j at time t, and ν is the stoichiometric number (the stoichiometric coefficient multiplied by +1 for products and –1 for starting materials). | 0 | Theoretical and Fundamental Chemistry |
The position of equilibrium in both cyclic and acyclic systems may be predicted from the structures of the two equilibrating epoxides. In acyclic systems, these rules have been established:
* Greater substitution on the epoxide ring is favored.
* Among disubstituted epoxides, trans isomers are favored over cis isomers.
* Isomers with primary hydroxyl groups are favored.
* Electron-donating substituents on the epoxide are stabilizing and electron-withdrawing substituents are destabilizing.
Pyranosides are the most heavily studied cyclic systems. Studies of epoxide migration in pyranosides and other cyclic epoxy alcohols have revealed three generalizations:
* As in acyclic systems, greater substitution on the epoxide ring is favored.
* The favored isomer is the one with more pseudoequatorial substituents.
* Intramolecular hydrogen bonding and other through-space interactions do not play a role in equilibrium ratios.
Conformationally locked pyranosides reveal the thermodynamic preference of cyclic substrates for more pseudoequatorial groups.
Under aprotic conditions, nucleophilic opening of epoxide isomers can be achieved with hydrides or organocuprates. Nucleophilic attack generally takes place at the least substituted carbon, yielding the more substituted diol product.
Under protic conditions, opening at the least substituted position is also usually favored. Nucleophiles that may be used under protic conditions include phenols, secondary amines, azide anion, and sulfides.
Intermolecular nucleophilic trapping of a single epoxide isomer is difficult, as reaction of the epoxy alcohol with the electrophile is typically faster than migration. However, intramolecular electrophies are often effective for trapping a single epoxide isomer. For instance, a second nearby epoxide in the starting material of equation (9) is trapped by a single epoxide isomer, leading to a tetrahydrofuran. | 0 | Theoretical and Fundamental Chemistry |
Forests are generally carbon dioxide sinks when they are high in diversity, density or area. However, they can also be carbon sources if diversity, density or area decreases due to deforestation, selective logging, climate change, wildfires or diseases. One study in 2020 found that 32 tracked Brazilian non-Amazon seasonal tropical forests declined from a carbon sink to a carbon source in 2013 and concludes that "policies are needed to mitigate the emission of greenhouse gases and to restore and protect tropical seasonal forests". In 2019 forests took up a third less carbon than they did in the 1990s, due to higher temperatures, droughts and deforestation. The typical tropical forest may become a carbon source by the 2060s.
An assessment of European forests found early signs of carbon sink saturation, after decades of increasing strength. The Intergovernmental Panel on Climate Change (IPCC) concluded that a combination of measures aimed at increasing forest carbon stocks, andsustainable timber offtake will generate the largest carbon sequestration benefit.
Life expectancy of forests varies throughout the world, influenced by tree species, site conditions and natural disturbance patterns. In some forests, carbon may be stored for centuries, while in other forests, carbon is released with frequent stand replacing fires. Forests that are harvested prior to stand replacing events allow for the retention of carbon in manufactured forest products such as lumber. However, only a portion of the carbon removed from logged forests ends up as durable goods and buildings. The remainder ends up as sawmill by-products such as pulp, paper and pallets, which often end with incineration (resulting in carbon release into the atmosphere) at the end of their lifecycle. For instance, of the 1,692 megatonnes of carbon harvested from forests in Oregon and Washington from 1900 to 1992, only 23% is in long-term storage in forest products.
The Food and Agriculure Organization (FAO) reported that: "The total carbon stock in forests decreased from 668 gigatonnes in 1990 to 662 gigatonnes in 2020". However, another study finds that the leaf area index has increased globally since 1981, which was responsible for 12.4% of the accumulated terrestrial carbon sink from 1981 to 2016. The CO fertilization effect, on the other hand, was responsible for 47% of the sink, while climate change reduced the sink by 28.6%. In Canada's boreal forests as much as 80% of the total carbon is stored in the soils as dead organic matter.
Carbon offset programs are planting millions of fast-growing trees per year to reforest tropical lands, for as little as $0.10 per tree. Over their typical 40-year lifetime, one million of these trees can sequester up to one million tons of carbon dioxide. | 0 | Theoretical and Fundamental Chemistry |
Traumatic brain injury is defined as a “direct physical impact or trauma to
the head followed by a dynamic series of injury and repair events”. Recently, neuroproteomics have been applied to studying the disability that over 5.4 million Americans live with. In addition to physically injuring the brain tissue, traumatic brain injury induces the release of glutamate that interacts with ionotropic glutamate receptors (iGluRs). These glutamate receptors acidify the surrounding intracranial fluid, causing further injury on the molecular level to nearby neurons. The death of the surrounding neurons is induced through normal apoptosis mechanisms, and it is this cycle that is being studied with neuroproteomics. Three different cysteine protease derivatives are involved in the apoptotic pathway induced by the acidic environment triggered by glutamate. These cysteine proteases include calpain, caspase, and cathepsin. These three proteins are examples of detectable signs of traumatic brain injury that are much more specific than temperature, oxygen level, or intracranial pressure.
Proteomics thus also offers a tracking mechanism by which researchers can monitor the progression of traumatic brain injury, or a chronic disease such as Alzheimer’s or Parkinson’s. Especially in Parkinson’s, in which neurotransmitters play a large role, recent proteomic research has involved the study of synaptotagmin. Synaptotagmin is involved in the calcium-induced budding of vesicle containing neurotransmitters from the presynaptic membrane. By studying the intracellular mechanisms involved in neural apoptosis after traumatic brain injury, researchers can create a map that genetic changes can follow later on. | 1 | Applied and Interdisciplinary Chemistry |
A differential refractometer (DRI), or refractive index detector (RI or RID) is a detector that measures the refractive index of an analyte relative to the solvent. They are often used as detectors for high-performance liquid chromatography and size exclusion chromatography. They are considered to be universal detectors because they can detect anything with a refractive index different from the solvent, but they have low sensitivity. | 0 | Theoretical and Fundamental Chemistry |
Green rust compounds were identified in green corrosion crusts that form on iron and steel surfaces, in alternating aerobic and anaerobic conditions, by water containing anions such as chloride, sulfate, carbonate, or bicarbonate. They are believed to be intermediates in the oxidative corrosion of iron to form iron(III) oxyhydroxides (ordinary brown rust). The green rust may be formed either directly from metallic iron or from iron(II) hydroxide () . | 1 | Applied and Interdisciplinary Chemistry |
Magnesium is essential as part of the process that generates adenosine triphosphate.
Mitochondria are often referred to as the "powerhouses of the cell" because their primary role is generating energy for cellular processes. They achieve this by breaking down nutrients, primarily glucose, through a series of chemical reactions known as cellular respiration. This process ultimately produces adenosine triphosphate (ATP), the cell's main energy currency. | 1 | Applied and Interdisciplinary Chemistry |
Source:
According to Claude Louis Berthollet, "What has long been called fixed, or fixible air, being really an acid in the state of gas, has of late received several new denominations. It has been called aerial acid, as existing very readily in the state of air, or more properly of gas, and plentifully in the atmosphere. The chalky acid, as procurable in large quantities from chalk, or other mild calcareous substances. The name given to it in this essay is derived from the knowledge of its composition, as lately ascertained by the French Chemists to consist of the elementary part of charcoal, named charbone, or char, united with oxygen, or the acidifying principle. Hence it is called, with strict propriety, carbonic acid in general; carbonic acid gas when in the aerial form; and carbonic acid liquor when combined with or dissolved in water."
By French Chemists, Berthollet is generally referring to Lavoisiers oxidation discoveries. The name oxygen is derived from Greek with oxy meaning acid, and gene to mean forming/expression, therefore carbonic acid is simply the union of carbon with oxygen (Laviosiers original degrees of oxidation could not fit the concept of carbon monoxide as it was based on diamond, graphite, coal and carbonic acid) | 1 | Applied and Interdisciplinary Chemistry |
The cycle comprises three enzyme-catalysed reactions. The first stage is the deamination of the purine nucleotide adenosine monophosphate (AMP) to form inosine monophosphate (IMP), catalysed by the enzyme AMP deaminase:
:AMP + HO + H → IMP + NH
The second stage is the formation of adenylosuccinate from IMP and the amino acid aspartate, which is coupled to the energetically favourable hydrolysis of GTP, and catalysed by the enzyme adenylosuccinate synthetase:
:Aspartate + IMP + GTP → Adenylosuccinate + GDP + P
Finally, adenylosuccinate is cleaved by the enzyme adenylosuccinate lyase to release fumarate and regenerate the starting material of AMP:
:Adenylosuccinate → AMP + Fumarate
A recent study showed that activation of HIF-1α allows cardiomyocytes to sustain mitochondrial membrane potential during anoxic stress by utilizing fumarate produced by adenylosuccinate lyase as an alternate terminal electron acceptor in place of oxygen. This mechanism should help provide protection in the ischemic heart. | 1 | Applied and Interdisciplinary Chemistry |
Removal of a halogen atom from an organohalide generates a radical. Such reactions are difficult to achieve and, when they can be achieved, these processes often lead to complicated mixtures. When a pair of halides are mutually adjacent (vicinal), their removal is favored. Such reactions give alkenes in the case of vicinal alkyl dihalides:
Most desirable from the perspective of remediation are dehalogenations by hydrogenolysis, i.e. the replacement of a bond by a bond. Such reactions are amenable to catalysis:
The rate of dehalogenation depends on the strength of the bond between the carbon and halogen atom. The bond dissociation energies of carbon-halogen bonds are described as: (234 kJ/mol), (293 kJ/mol), (351 kJ/mol), and (452 kJ/mol). Thus, for the same structures the bond dissociation rate for dehalogenation will be: . Additionally, the rate of dehalogenation for alkyl halide also varies with steric environment and follows this trend: halides. | 0 | Theoretical and Fundamental Chemistry |
The Tishchenko reaction is an organic chemical reaction that involves disproportionation of an aldehyde in the presence of an alkoxide. The reaction is named after Russian organic chemist Vyacheslav Tishchenko, who discovered that aluminium alkoxides are effective catalysts for the reaction.
In the related Cannizzaro reaction, the base is sodium hydroxide and then the oxidation product is a carboxylic acid and the reduction product is an alcohol. | 0 | Theoretical and Fundamental Chemistry |
Antifreeze proteins (AFPs) or ice structuring proteins refer to a class of polypeptides produced by certain animals, plants, fungi and bacteria that permit their survival in temperatures below the freezing point of water. AFPs bind to small ice crystals to inhibit the growth and recrystallization of ice that would otherwise be fatal. There is also increasing evidence that AFPs interact with mammalian cell membranes to protect them from cold damage. This work suggests the involvement of AFPs in cold acclimatization. | 1 | Applied and Interdisciplinary Chemistry |
As mentioned above the E and C parameters are obtained from enthalpies of adduct formation in which the bond between the acid and base is a σ interaction and adducts that have no steric repulsion between the acid and base.
As a result, E and C parameters can be used to glean information about pi bonding. When pi bonding contributes to the measured enthalpy, the enthalpy calculated from the E and C parameters will be less than the measured enthalpy and the difference provides a measure of the extent of the pi bonding contribution.
The ᐃH calculated for the reaction of MeB with MeN is larger than the observed. This discrepancy is attributed to steric repulsion between the methyl groups on the B and N. The difference between the calculated and observed values can then be taken as the amount of the steric effect, a value otherwise not attainable. Steric effects have also been identified with (CH)SnCl and with Cu(HFacac).
The use of E and C parameters have been extended to analyze spectroscopic changes occurring during adduct formation. For example, the shift of the phenol OH stretching frequency, , that occurs upon adduct formation has been analyzed using the following equation:
where asterisks on the E and C for phenol indicate that the acceptor is held constant and the frequency shift is measured as the base is varied. The asterisks also indicate that the phenol parameters are those for frequency shifts and not those for enthalpies. An analysis like this provides a basis for using E and C parameters as a reference scale of donor strengths for frequency shifts. This type analysis has also been applied to other spectroscopic shifts (NMR, EPR, UV-vis, IR, etc.) accompanying adduct formation. Any physicochemical property, , that is dominated by σ donor-acceptor interaction can be correlated with the enthalpy-derived E and C parameters.
The ECW equations enables one to correlate and predict the enthalpies of adduct formation of neutral donor-acceptor interactions for which the electron-transfer is limited. For gas-phase reactions between cations and neutral donors, there is significant electron-transfer. The extension of the ECW model to cation-neutral Lewis base interactions has led to the ECT model. Others have concluded that the ECW model "is generally found helpful in many fields of solution chemistry and biochemistry". | 0 | Theoretical and Fundamental Chemistry |
An active ingredient is any ingredient that provides biologically active or other direct effect in the diagnosis, cure, mitigation, treatment, or prevention of disease or to affect the structure or any function of the body of humans or animals.
The similar terms active pharmaceutical ingredient (abbreviated as API) and bulk active are also used in medicine. The term active substance may be used for natural products.
Some medication products can contain more than one active ingredient. The traditional word for the active pharmaceutical agent is pharmacon or pharmakon (from , adapted from pharmacos) which originally denoted a magical substance or drug.
The terms active constituent or active principle are often chosen when referring to the active substance of interest in a plant (such as salicylic acid in willow bark or arecoline in areca nuts), since the word "ingredient" can be taken to connote a sense of human agency (that is, something that a person combines with other substances), whereas the natural products present in plants were not added by any human agency but rather occurred naturally ("a plant doesn't have ingredients").
In contrast with the active ingredients, the inactive ingredients are usually called excipients in pharmaceutical contexts. The main excipient that serves as a medium for conveying the active ingredient is usually called the vehicle. For example, petrolatum and mineral oil are common vehicles. The term inactive should not, however, be misconstrued as meaning inert. | 1 | Applied and Interdisciplinary Chemistry |
Bhaskar Dattatraya Kulkarni (5 May 1949 – 14 January 2019), popularly known as B. D. among his friends and colleagues, was an Indian chemical reaction engineer and a Distinguished Scientist of Chemical Engineering and Process Development at the National Chemical Laboratory, Pune. An INSA Senior Scientist and a J. C. Bose fellow, he was known for his work on fluidized bed reactors and chemical reactors. He is an elected fellow of the Indian Academy of Sciences, Indian National Science Academy, The World Academy of Sciences and the Indian National Academy of Engineering. The Council of Scientific and Industrial Research, the apex agency of the Government of India for scientific research, awarded him the Shanti Swarup Bhatnagar Prize for Science and Technology, one of the highest Indian science awards for his contributions to Engineering Sciences in 1988. | 1 | Applied and Interdisciplinary Chemistry |
Even remote substituents on the benzene ring can affect the electron density on the aromatic ring and in turn influence the selectivity. In the hydrogenation of ketones using CBS catalysts, the ketone coordinates to the boron atom with the lone pair on the oxygen atom. In the following example, the inductive influence of the substituents can lead to differentiation of the two sp lone pairs on the oxygen atom.
The relevant stereoelectronic interaction in the starting material is the n → σ*(C–C) interaction. The electron-withdrawing substituent on the benzene ring depletes the electron density on the aromatic ring and thus makes the σ*(C–C) orbital a better acceptor than σ*(C–C). These two stereoelectronic interactions use different lone pairs on the oxygen atom (the one antiperiplanar to the σ* in question for each), leading to lone pairs with different electron densities. In particular, the enhanced depletion of electron density from the lone pair antiperiplanar to the 4-nitrophenyl group leads to weakened ability for that lone pair to coordinate to boron. This in turn results in the lone pair antiperiplanar to the 4-methoxyphenyl binding preferentially to the catalyst, leading to well-defined facial selectivity. Under optimized conditions, the product is formed with excellent levels of enantioselectivity (95% ee). | 0 | Theoretical and Fundamental Chemistry |
Early thermonuclear weapon designs such as the Joe-4, the Soviet "Layer Cake" ("Sloika", ), used large amounts of fusion to induce fission in the uranium-238 atoms that make up depleted uranium. These weapons had a fissile core surrounded by a layer of lithium-6 deuteride, in turn surrounded by a layer of depleted uranium. Some designs (including the layer cake) had several alternate layers of these materials. The Soviet Layer Cake was similar to the American Alarm Clock design, which was never built, and the British Green Bamboo design, which was built but never tested.
When this type of bomb explodes, the fission of the highly enriched uranium or plutonium core creates neutrons, some of which escape and strike atoms of lithium-6, creating tritium. At the temperature created by fission in the core, tritium and deuterium can undergo thermonuclear fusion without a high level of compression. The fusion of tritium and deuterium produces a neutron with an energy of 14 MeV—a much higher energy than the 1 MeV of the neutron that began the reaction. This creation of high-energy neutrons, rather than energy yield, is the main purpose of fusion in this kind of weapon. This 14 MeV neutron then strikes an atom of uranium-238, causing fission: without this fusion stage, the original 1 MeV neutron hitting an atom of uranium-238 would probably have just been absorbed. This fission then releases energy and also neutrons, which then create more tritium from the remaining lithium-6, and so on, in a continuous cycle. Energy from fission of uranium-238 is useful in weapons: both because depleted uranium is much cheaper than highly enriched uranium and because it cannot go critical and is therefore less likely to be involved in a catastrophic accident.
This kind of thermonuclear weapon can produce up to 20% of its yield from fusion, with the rest coming from fission, and is limited in yield to less than one megaton of TNT (4 PJ) equivalent. Joe-4 yielded 400 kilotons of TNT (1.7 PJ). In comparison, a "true" hydrogen bomb can produce up to 97% of its yield from fusion, and its explosive yield is limited only by device size. | 0 | Theoretical and Fundamental Chemistry |
In condensed phases (solutions), adsorption to a solid surface is a competitive process between the solvent (A) and the solute (B) to occupy the binding site. The thermodynamic equilibrium is described as
: Solvent (bound) + Solute (free) ↔ Solvent (free) + Solute (bound).
If we designate the solvent by the subscript "1" and the solute by "2", and the bound state by the superscript "s" (surface/bound) and the free state by the "b" (bulk solution / free), then the equilibrium constant can be written as a ratio between the activities of products over reactants:
For dilute solutions the activity of the solvent in bulk solution and the activity coefficients () are also assumed to ideal on the surface. Thus, , and where are mole fractions.
Re-writing the equilibrium constant and solving for yields
Note that the concentration of the solute adsorbate can be used instead of the activity coefficient. However, the equilibrium constant will no longer be dimensionless and will have units of reciprocal concentration instead. The difference between the kinetic and thermodynamic derivations of the Langmuir model is that the thermodynamic uses activities as a starting point while the kinetic derivation uses rates of reaction. The thermodynamic derivation allows for the activity coefficients of adsorbates in their bound and free states to be included. The thermodynamic derivation is usually referred to as the "Langmuir-like equation". | 0 | Theoretical and Fundamental Chemistry |
An expression cassette is a distinct component of vector DNA consisting of a gene and regulatory sequence to be expressed by a transfected cell. In each successful transformation, the expression cassette directs the cell's machinery to make RNA and protein(s). Some expression cassettes are designed for modular cloning of protein-encoding sequences so that the same cassette can easily be altered to make different proteins.
An expression cassette is composed of one or more genes and the sequences controlling their expression. An expression cassette comprises three components: a promoter sequence, an open reading frame, and a 3' untranslated region that, in eukaryotes, usually contains a polyadenylation site.
Different expression cassettes can be transfected into different organisms including bacteria, yeast, plants, and mammalian cells as long as the correct regulatory sequences are used. | 1 | Applied and Interdisciplinary Chemistry |
scRNA-Seq is becoming widely used across biological disciplines including Development, Neurology, Oncology, Autoimmune disease, and Infectious disease.
scRNA-Seq has provided considerable insight into the development of embryos and organisms, including the worm Caenorhabditis elegans, and the regenerative planarian Schmidtea mediterranea. The first vertebrate animals to be mapped in this way were Zebrafish and Xenopus laevis. In each case multiple stages of the embryo were studied, allowing the entire process of development to be mapped on a cell-by-cell basis. Science recognized these advances as the 2018 Breakthrough of the Year. | 1 | Applied and Interdisciplinary Chemistry |
Another type of innovative neutron generator is the inertial electrostatic confinement fusion device. This neutron generator avoids using a solid target which will be sputter eroded causing metalization of insulating surfaces. Depletion of the reactant gas within the solid target is also avoided. Far greater operational lifetime is achieved. Originally called a fusor, it was invented by Philo Farnsworth, the inventor of electronic television. | 0 | Theoretical and Fundamental Chemistry |
Diisopinocampheylborane is an organoborane that is useful for asymmetric synthesis. This colourless solid is the precursor to a range of related reagents. The compound was reported in 1961 by Zweifel and Brown in a pioneering demonstration of asymmetric synthesis using boranes. The reagent is mainly used for the synthesis of chiral secondary alcohols. The reagent is often depicted as a monomer but like most hydroboranes, it is dimeric with B-H-B bridges. | 0 | Theoretical and Fundamental Chemistry |
The rate of a reaction is the concentration of substrate disappearing (or product produced) per unit time (mol L s).
The % purity is 100% × (specific activity of enzyme sample / specific activity of pure enzyme). The impure sample has lower specific activity because some of the mass is not actually enzyme. If the specific activity of 100% pure enzyme is known, then an impure sample will have a lower specific activity, allowing purity to be calculated and then getting a clear result. | 1 | Applied and Interdisciplinary Chemistry |
The second approach (the constraint method), chooses one of the objective functions as the single objective, and the other objective functions are treated as constraints with a limited value. However, the optimal solution depends on the pre-defined constraint limits. | 1 | Applied and Interdisciplinary Chemistry |
A pyrophosphate ion with Tc adheres to calcium deposits in damaged heart muscle, making it useful to gauge damage after a heart attack. | 0 | Theoretical and Fundamental Chemistry |
Survivin is known to be expressed during fetal development and across most tumour cell types, but is rarely present in normal, non-malignant adult cells. Tamm et al. showed that survivin was expressed in all 60 different human tumour lines used in the National Cancer Institute's cancer drug-screening program, with the highest levels of expression in breast and lung cancer lines and the lowest levels in renal cancers. Knowing the relative expression levels of survivin in different tumour types may prove helpful as survivin-related therapy may be administered depending on the expression level and reliance of the tumour type on survivin for resistance to apoptosis. | 1 | Applied and Interdisciplinary Chemistry |
In 1972, Atalla filed for a remote PIN verification system, which utilized encryption techniques to assure telephone link security while entering personal ID information, which would be transmitted as encrypted data over telecommunications networks to a remote location for verification. This was a precursor to telephone banking, Internet security and e-commerce.
At the National Association of Mutual Savings Banks (NAMSB) conference in January 1976, Atalla announced an upgrade to its Identikey system, called the Interchange Identikey. It added the capabilities of processing online transactions and dealing with network security. Designed with the focus of taking bank transactions online, the Identikey system was extended to shared-facility operations. It was consistent and compatible with various switching networks, and was capable of resetting itself electronically to any one of 64,000 irreversible nonlinear algorithms as directed by card data information. The Interchange Identikey device was released in March 1976. It was one of the first products designed to deal with online transactions, along with Bunker Ramo Corporation products unveiled at the same NAMSB conference. In 1979, Atalla introduced the first network security processor (NSP).
In 1987, Atalla Corporation merged with Tandem Computers. Atalla went into retirement in 1990.
As of 2013, 250million card transactions are protected by Atalla products every day. | 0 | Theoretical and Fundamental Chemistry |
Rare-earth complexes incorporating TRISOX ligands have been found to be highly effective catalysts for the polymerisation of α-alkenes and are notable for producing polyolefins with very high tacticities. Computational modelling of the polymerisation mechanism indicates that kinetic factors likely account for the high tacticity. | 0 | Theoretical and Fundamental Chemistry |
Volumetric method was used in the early days of adsorption studies by Langmuir, Dubinin and others. It basically comprises a gas expansion process from a storage vessel (reference cell) to an adsorption chamber including adsorbent (adsorption cell) through a controlling valve C, as schematically shown in Figure 1. The reference cell with volume is kept at a constant temperature . The value of includes the volume of the tube between the reference cell and valve C. The adsorption cell is kept at the specified equilibrium temperature . The volume of the connecting tube between the adsorption cell and valve is divided into two parts: one part with volume with same temperature as the reference cell. The other part is buried in an atmosphere of temperature . Its volume is added to the volume of adsorption cell .
The amount adsorbed can be calculated from the pressure readings before and after opening valve C based on the p-V-T relationship of real gases. A dry and degassed adsorbent sample of known weight was enclosed in the adsorption cell. An amount of gas is let into to maintain a pressure . The moles of gas confined in are calculated as:
The pressure drops to after opening valve C. The amount of gas maintained in , , and are respectively:
The amount adsorbed or the excess adsorption N is then obtained:
where and are the moles of the gas remaining in and before opening valve C. All of the compressibility factor values are calculated by a proper equation of state, which can generate appropriate z values for temperatures not close to the critical zone.
The main advantages of this method are simplicity in procedure, commercial availability of instruments, and the large ranges of pressure and temperature in which this method can be realized. The disadvantage of volumetric measurements is the considerable amount of adsorbent sample needed to overcome adsorption effects on the walls of the vessels. However, this may be a positive aspect if the sample is adequate. A larger amount of sample results in considerable adsorption and usually provides a larger void space in the adsorption cell, rendering the effect of uncertainty in “dead space” to a minimum. | 0 | Theoretical and Fundamental Chemistry |
In medieval universities there were, however, expressions of atomism. For example, in the 14th century Nicholas of Autrecourt considered that matter, space, and time were all made up of indivisible atoms, points, and instants and that all generation and corruption took place by the rearrangement of material atoms. The similarities of his ideas with those of al-Ghazali suggest that Nicholas may have been familiar with Ghazalis work, perhaps through Averroes refutation of it. | 1 | Applied and Interdisciplinary Chemistry |
The activity of SINEs however has genetic vestiges which do not seem to play a significant role, positive or negative, and manifest themselves in the genome as pseudogenes. SINEs however should not be mistaken as RNA pseudogenes. In general, pseudogenes are generated when processed mRNAs of protein-coding genes are reverse-transcribed and incorporated back into the genome (RNA pseudogenes are reverse transcribed RNA genes). Pseudogenes are generally functionless as they descend from processed RNAs independent of their evolutionary-context which includes introns and different regulatory elements which enable transcription and processing. These pseudogenes, though non-functional may in some cases still possess promoters, CpG islands, and other features which enable transcription; they thus can still be transcribed and may possess a role in the regulation of gene expression (like SINEs and other non-coding elements). Pseudogenes thus differ from SINEs in that they are derived from transcribed- functional RNA whereas SINEs are DNA elements which retrotranspose by co-opting RNA genes transcriptional machinery. However, there are studies which suggest that retro-transposable elements such as short-interspersed nuclear elements are not only capable of copying themselves in alternate regions in the genome but are also able to do so for random genes too. Thus SINEs can be playing a vital role in the generation of pseudogenes, which themselves are known to be involved in regulatory networks. This is perhaps another means by which SINEs have been able to influence and contribute to gene-regulation. | 1 | Applied and Interdisciplinary Chemistry |
In production engineering, metallurgy is concerned with the production of metallic components for use in consumer or engineering products. This involves production of alloys, shaping, heat treatment and surface treatment of product. The task of the metallurgist is to achieve balance between material properties, such as cost, weight, strength, toughness, hardness, corrosion, fatigue resistance and performance in temperature extremes. To achieve this goal, the operating environment must be carefully considered.
Determining the hardness of the metal using the Rockwell, Vickers, and Brinell hardness scales is a commonly used practice that helps better understand the metal's elasticity and plasticity for different applications and production processes. In a saltwater environment, most ferrous metals and some non-ferrous alloys corrode quickly. Metals exposed to cold or cryogenic conditions may undergo a ductile to brittle transition and lose their toughness, becoming more brittle and prone to cracking. Metals under continual cyclic loading can suffer from metal fatigue. Metals under constant stress at elevated temperatures can creep. | 1 | Applied and Interdisciplinary Chemistry |
Due to the very small electrical fields produced by neurons, mathematical models are often used in order to test a number of manipulations. Cable theory is one of the most important mathematical equations in neuroscience. It calculates electric current using capacitance and resistance as variables and has been the main basis for many predictions about ephaptic coupling in neurons. However, many authors have worked to create more refined models in order to more accurately represent the environments of the nervous system. For example, many authors have proposed models for cardiac tissue that includes additional variables that account for the unique structure and geometry of cardiac cells varying scales of size, or three-dimensional electrodiffusion. | 1 | Applied and Interdisciplinary Chemistry |
Spectroscopic notation provides a way to specify atomic ionization states, atomic orbitals, and molecular orbitals. | 0 | Theoretical and Fundamental Chemistry |
The book is divided into three basic sections, named Momentum Transport, Energy Transport and Mass Transport:
*Momentum Transport
**Viscosity and the Mechanisms of Momentum Transport
**Momentum Balances and Velocity Distributions in Laminar Flow
**The Equations of Change for Isothermal Systems
**Velocity Distributions in Turbulent Flow
**Interphase Transport in Isothermal Systems
**Macroscopic Balances for Isothermal Flow Systems
*Energy Transport
**Thermal Conductivity and the Mechanisms of Energy Transport
**Energy Balances and Temperature Distributions in Solids and Laminar Flow
**The Equations of Change for Nonisothermal Systems
**Temperature Distributions in Turbulent Flow
**Interphase Transport in Nonisothermal Systems
**Macroscopic Balances for Nonisothermal Systems
*Mass transport
**Diffusivity and the Mechanisms of Mass Transport
**Concentration Distributions in Solids and Laminar Flow
**Equations of Change for Multicomponent Systems
**Concentration Distributions in Turbulent Flow
**Interphase Transport in Nonisothermal Mixtures
**Macroscopic Balances for Multicomponent Systems
**Other Mechanisms for Mass Transport | 1 | Applied and Interdisciplinary Chemistry |
Plastic pipe is a tubular section, or hollow cylinder, made of plastic. It is usually, but not necessarily, of circular cross-section, used mainly to convey substances which can flow—liquids and gases (fluids), slurries, powders and masses of small solids. It can also be used for structural applications; hollow pipes are far stiffer per unit weight than solid members.
Plastic pipework is used for the conveyance of drinking water, waste water, chemicals, heating fluid and cooling fluids, foodstuffs, ultra-pure liquids, slurries, gases, compressed air, irrigation, plastic pressure pipe systems, and vacuum system applications. | 1 | Applied and Interdisciplinary Chemistry |
The Van 't Hoff isotherm can be used to determine the temperature dependence of the Gibbs free energy of reaction for non-standard state reactions at a constant temperature:
where is the Gibbs free energy of reaction under non-standard states at temperature , is the Gibbs free energy for the reaction at , is the extent of reaction, and is the thermodynamic reaction quotient. Since , the temperature dependence of both terms can be described by Van tHoff equations as a function of T'. This finds applications in the field of electrochemistry. particularly in the study of the temperature dependence of voltaic cells.
The isotherm can also be used at fixed temperature to describe the Law of Mass Action. When a reaction is at equilibrium, and . Otherwise, the Van 't Hoff isotherm predicts the direction that the system must shift in order to achieve equilibrium; when , the reaction moves in the forward direction, whereas when , the reaction moves in the backwards direction. See Chemical equilibrium. | 0 | Theoretical and Fundamental Chemistry |
The Merv Oasis had been extensively explored in 1904 by an American team; however, the reports published were of a preliminary nature. During the period 1940–50, the Asian Republics started establishing archaeological institutions in their respective countries. Among them, the South Turkmenistan Complex Archaeological Expedition was established in 1946 by Masson under the aegis of the Turkmenistan Academy of Sciences to carry out explorations at several locations. These explorations included:
* 1947-1952: exploration by Alexey Okladnikov of mesolithic sites
* 1940s and 1950s: Eneolithic and Bronze Age excavations by Boris Kuftin
* 1955-62: excavations by V.M. Masson, I.N. Khlopin, and Viktor Sarianidi of neolithic sites at many locations, including Jietun at the Geoksur Oasis
* Since 1965: Bronze Age excavations by Masson covering, among others, the site at Altyndepe
* Excavations by G. N. Lisitsyna to investigate the prehistoric economies and irrigation systems.
* 1977-92: explorations by Khlopin in the Sumbar Valley
Since 1992, excavations have been carried out by a joint project titled “Turkmen-British-Merv Project”. This has yielded historical data on fortifications and a residential complex of the Hellenistic, Parthina and Sassanian period. | 1 | Applied and Interdisciplinary Chemistry |
The method of continued fractions is a method developed specifically for solution of integral equations of quantum scattering theory like Lippmann–Schwinger equation or Faddeev equations. It was invented by Horáček and Sasakawa in 1983. The goal of the method is to solve the integral equation
iteratively and to construct convergent continued fraction for the T-matrix
The method has two variants. In the first one (denoted as MCFV) we construct approximations of the potential energy operator in the form of separable function of rank 1, 2, 3 ... The second variant (MCFG method) constructs the finite rank approximations to Green's operator. The approximations are constructed within Krylov subspace constructed from vector with action of the operator . The method can thus be understood as resummation of (in general divergent) Born series by Padé approximants. It is also closely related to Schwinger variational principle.
In general the method requires similar amount of numerical work as calculation of terms of Born series, but it provides much faster convergence of the results. | 0 | Theoretical and Fundamental Chemistry |
For discrete probability distributions and defined on the same sample space, the relative entropy from to is defined to be
which is equivalent to
In other words, it is the expectation of the logarithmic difference between the probabilities and , where the expectation is taken using the probabilities .
Relative entropy is only defined in this way if, for all , implies (absolute continuity). Otherwise, it is often defined as but the value is possible even if everywhere, provided that is infinite in extent. Analogous comments apply to the continuous and general measure cases defined below.
Whenever is zero the contribution of the corresponding term is interpreted as zero because
For distributions and of a continuous random variable, relative entropy is defined to be the integral
where and denote the probability densities of and .
More generally, if and are probability measures on a measurable space and is absolutely continuous with respect to , then the relative entropy from to is defined as
where is the Radon–Nikodym derivative of with respect to , i.e. the unique almost everywhere defined function on such that which exists because is absolutely continuous with respect to . Also we assume the expression on the right-hand side exists. Equivalently (by the chain rule), this can be written as
which is the entropy of relative to . Continuing in this case, if is any measure on for which densities and with and exist (meaning that and are both absolutely continuous with respect to ), then the relative entropy from to is given as
Note that such a measure for which densities can be defined always exists, since one can take although in practice it will usually be one that in the context like counting measure for discrete distributions, or Lebesgue measure or a convenient variant thereof like Gaussian measure or the uniform measure on the sphere, Haar measure on a Lie group etc. for continuous distributions.
The logarithms in these formulae are usually taken to base 2 if information is measured in units of bits, or to base if information is measured in nats. Most formulas involving relative entropy hold regardless of the base of the logarithm.
Various conventions exist for referring to in words. Often it is referred to as the divergence between and , but this fails to convey the fundamental asymmetry in the relation. Sometimes, as in this article, it may be described as the divergence of from or as the divergence from to . This reflects the asymmetry in Bayesian inference, which starts from a prior and updates to the posterior . Another common way to refer to is as the relative entropy of with respect to or the information gain from over . | 0 | Theoretical and Fundamental Chemistry |
Rates of reaction can be affected by the size of rings. Essentially each reaction should be studied on a case-by-case basis but some general trends have been seen. Molecular mechanics calculations of strain energy differences SI between a sp2 and sp3 state in cycloalkanes show linear correlations with rates ( as logk ) of many reactions involving the transition between sp2 and sp3 states, such as ketone reduction, alcohol oxidation or nucleophilic substitution, the contribution of transannular strain is below 3 %.
Rings with transannular strain have faster S1, S2, and free radical reactions compared to most smaller and normal sized rings. Five membered rings show an exception to this trend. On the other hand, some nucleophilic addition reactions involving addition to a carbonyl group in general show the opposite trend. Smaller and normal rings, with five membered rings being the anomaly, have faster reaction rates while those with transannular strain are slower.
One specific example of a study of rates of reactions for an S1 reaction is shown on the right. Various sized rings, ranging from four to seventeen members, were used to compare the relative rates and better understand the effect of transannular strain on this reaction. The solvolysis reaction in acetic acid involved the formation of a carbocation as the chloride ion leaves the cyclic molecule. This study fits the general trend seen above that rings with transannular strain show increased reactions rates compared to smaller rings in S1 reactions. | 0 | Theoretical and Fundamental Chemistry |
The turtapede (Mawup in Navi) is a Pandoran creature that resembles a cross between a turtle, a platypus and a starfish. With its large dorsal fin and long tail, the turtapede is agile underwater. When emerging from the water, mesmerizing colors start to shimmer in the translucent area on its shell. They first appear in the musical Toruk – The First Flight'. | 1 | Applied and Interdisciplinary Chemistry |
A mononuclidic element or monotopic element is one of the 21 chemical elements that is found naturally on Earth essentially as a single nuclide (which may, or may not, be a stable nuclide). This single nuclide will have a characteristic atomic mass. Thus, the element's natural isotopic abundance is dominated by one isotope that is either stable or very long-lived. There are 19 elements in the first category (which are both monoisotopic and mononuclidic), and 2 (bismuth and protactinium) in the second category (mononuclidic but not monoisotopic, since they have zero, not one, stable nuclides). A list of the 21 mononuclidic elements is given at the end of this article.
Of the 26 monoisotopic elements that, by definition, have only one stable isotope, seven are not considered mononuclidic, due to the presence of a significant fraction of a very long-lived (primordial) radioisotope. These elements are vanadium, rubidium, indium, lanthanum, europium, lutetium, and rhenium. | 0 | Theoretical and Fundamental Chemistry |
The Pathway Interaction Database (PID) is a free biomedical database of human cellular signaling pathways. The database contains information about the molecular interactions and reactions that take place in cells, with a particular focus on processes that might be relevant to cancer research and treatment. The database was established as collaboration between the U.S. National Cancer Institute, NIH and Nature Publishing Group in 2005 and was launched in November 2006. In September 2012, active curation was stopped and the PID data are now available in the [http://www.ndexbio.org/#/user/301a91c6-a37b-11e4-bda0-000c29202374 Network Data Exchange, NDEx]. | 1 | Applied and Interdisciplinary Chemistry |
Solid is one of the four fundamental states of matter along with liquid, gas, and plasma. The molecules in a solid are closely packed together and contain the least amount of kinetic energy. A solid is characterized by structural rigidity (as in rigid bodies) and resistance to a force applied to the surface. Unlike a liquid, a solid object does not flow to take on the shape of its container, nor does it expand to fill the entire available volume like a gas. The atoms in a solid are bound to each other, either in a regular geometric lattice (crystalline solids, which include metals and ordinary ice), or irregularly (an amorphous solid such as common window glass). Solids cannot be compressed with little pressure whereas gases can be compressed with little pressure because the molecules in a gas are loosely packed.
The branch of physics that deals with solids is called solid-state physics, and is the main branch of condensed matter physics (which also includes liquids). Materials science is primarily concerned with the physical and chemical properties of solids. Solid-state chemistry is especially concerned with the synthesis of novel materials, as well as the science of identification and chemical composition. | 0 | Theoretical and Fundamental Chemistry |
Station ALOHA is a deep water (~4,800 m) location approximately 100 km north of the Hawaiian Island of Oahu. Thus, the region is far enough from land to be free of coastal ocean dynamics and terrestrial inputs, but close enough to a major port (Honolulu) to make relatively short duration (less than five days) near-monthly cruises logistically and financially feasible. Sampling at this site occurs within a 10 km radius around the center of the station.
Each HOT cruise begins with a stop at a coastal station south of the island of Oahu, approximately 10 km off Kahe Point (21° 20.6N, 158° 16.4W) in 1500 m of water. Station Kahe (termed Station 1) is used to test equipment and train new personnel before departing for Station ALOHA. Since August 2004, Station ALOHA has also been home to a surface mooring outfitted for meteorological and upper ocean measurements; this mooring, named WHOTS (also termed Station 50), is a collaborative project between Woods Hole Oceanographic Institution and HOT. WHOTS provides long-term, high-quality air-sea fluxes as a coordinated part of HOT, contributing to the program’s goals of observing heat, fresh water and chemical fluxes. In 2011, the ALOHA Cabled Observatory (ACO) became operational. This instrumented fiber optic cabled observatory provides power and communications to the seabed (4728 m). The ACO is currently configured with an array of thermistors, current meters, conductivity sensors, two hydrophones, and a video camera. | 0 | Theoretical and Fundamental Chemistry |
Zeba was married to Toufiq M Seraj, a Bangladeshi businessman who was the founder and managing director of Sheltech. They have two daughters. | 1 | Applied and Interdisciplinary Chemistry |
The U.S. Institute of Medicine (IOM) updated Estimated Average Requirements (EARs) and Recommended Dietary Allowances (RDAs) for minerals in 2001. For manganese there was not sufficient information to set EARs and RDAs, so needs are described as estimates for Adequate Intakes (AIs). As for safety, the IOM sets Tolerable upper intake levels (ULs) for vitamins and minerals when evidence is sufficient. In the case of manganese the adult UL is set at 11 mg/day. Collectively the EARs, RDAs, AIs and ULs are referred to as Dietary Reference Intakes (DRIs). Manganese deficiency is rare.
The European Food Safety Authority (EFSA) refers to the collective set of information as Dietary Reference Values, with Population Reference Intake (PRI) instead of RDA, and Average Requirement instead of EAR. AI and UL defined the same as in United States. For people ages 15 and older the AI is set at 3.0 mg/day. AIs for pregnancy and lactation is 3.0 mg/day. For children ages 1–14 years the AIs increase with age from 0.5 to 2.0 mg/day. The adult AIs are higher than the U.S. RDAs. The EFSA reviewed the same safety question and decided that there was insufficient information to set a UL.
For U.S. food and dietary supplement labeling purposes the amount in a serving is expressed as a percent of Daily Value (%DV). For manganese labeling purposes 100% of the Daily Value was 2.0 mg, but as of 27 May 2016 it was revised to 2.3 mg to bring it into agreement with the RDA. A table of the old and new adult daily values is provided at Reference Daily Intake. | 1 | Applied and Interdisciplinary Chemistry |
The Chézy Formula is a semi-empirical resistance equation which estimates mean flow velocity in open channel conduits. The relationship was conceptualized and developed in 1768 by French physicist and engineer Antoine de Chézy (1718–1798) while designing Pariss water canal system. Chézy discovered a similarity parameter that could be used for estimating flow characteristics in one channel based on the measurements of another. The Chézy formula is a pioneering formula in the field of fluid mechanics which relates the flow of water through an open channel with the channels dimensions and slope. It was expanded and modified by Irish Engineer Robert Manning in 1889. Manning's modifications to the Chézy formula allowed the entire similarity parameter to be calculated by channel characteristics rather than by experimental measurements. Today, the Chézy and Manning equations continue to accurately estimate open channel fluid flow and are standard formulas in various fields related to fluid mechanics and hydraulics, including physics, mechanical engineering and civil engineering. | 1 | Applied and Interdisciplinary Chemistry |
In heat balance calorimetry, the cooling/heating jacket controls the temperature of the process. Heat is measured by monitoring the heat gained or lost by the heat transfer fluid.
where
: = process heating (or cooling) power (W)
: = mass flow of heat transfer fluid (kg/s)
: = specific heat of heat transfer fluid (J/(kg K))
: = inlet temperature of heat transfer fluid (K)
: = outlet temperature of heat transfer fluid (K)
Heat balance calorimetry is, in principle, the ideal method of measuring heat since the heat entering and leaving the system through the heating/cooling jacket is measured from the heat transfer fluid (which has known properties). This eliminates most of the calibration problems encountered by heat flow and power compensation calorimetry. Unfortunately, the method does not work well in traditional batch vessels since the process heat signal is obscured by large heat shifts in the cooling/heating jacket. | 1 | Applied and Interdisciplinary Chemistry |
The history of mediaeval medicine started roughly around the year 1000 with the school of medicine in Salerno, which combined elements of Latin, Greek, Arabic, and Jewish medicine. Galen and Dioscorides (who had used the Graeco-Roman weight system) were among the most important authorities, but also Arabic physicians, whose works were systematically translated into Latin.
According to , a famous 13th-century text that exists in numerous variations and is often ascribed to Dino di Garbo, the system of weights used in Salerno was different from the systems used in Padua and Bologna. As can be seen from the table, it was also different from the Roman weight system used by Galenus and Dioscorides and from all modern apothecaries' systems: The ounce was divided into 9 drachms, rather than 8 drachms.
Centuries later, the region around Salerno was the only exception to the rule that (except for skipping units that had regionally fallen out of use) the apothecaries' ounce was subdivided down to the scruple in exactly the same way as in the Roman system: It divided the ounce into 10 drachms. | 1 | Applied and Interdisciplinary Chemistry |
2-(Morpholinothio)benzothiazole is used as an accelerator/stabilizer for vulcanization, or the manufacture of rubber products. It is the precursor to NMOR in the vulcanization process, as it is nitrosated by ambient sources of the nitro group present in the manufacturing process. As such, workers and others exposed to the rubber industry or its byproducts are exposed to higher levels of NMOR than the general population, raising their risk of cancer. | 0 | Theoretical and Fundamental Chemistry |
Hydrous oxides are inorganic compounds of a metal, hydroxide, and weakly bound water. Some examples include:
* Hydrous ferric oxide (HFO)
* Hydrous cupric oxide
* Hydrous thorium oxide (THO) and hydrous titanium oxide (TiHO)
* Hydrous aluminum oxide (HAO)
Some of them, such as HFO and HAO, are precipitated in highly porous poorly crystalline or amorphous forms and therefore are good adsorbents used for example in water treatment.
Some others are gels.
Hydrous oxide films may be used an various applications such as electrocatalysis, supercapacitors, and sensors.
HFO and HAO may also result from oxidative weathering of rocks to produce iron an aluminum hydrous oxide clay soils. | 0 | Theoretical and Fundamental Chemistry |
Transamination is mediated by several types of aminotransferase enzymes. An aminotransferase may be specific for an individual amino acid, or it may be able to process any member of a group of similar ones, for example the branched-chain amino acids, which comprises valine, isoleucine, and leucine. The two common types of aminotransferases are alanine aminotransferase (ALT) and aspartate aminotransferase (AST). | 0 | Theoretical and Fundamental Chemistry |
Sucrose esters are mainly manufactured by using interesterification, the transfer of fatty acid from one ester to another. In this case, it means that the fatty acids used for the synthesis of sucrose esters are themselves in the esterified form. There are three processes that have been developed. | 0 | Theoretical and Fundamental Chemistry |
Moving bed biofilm reactor (MBBR) is a type of wastewater treatment process that was first invented by Professor Hallvard Ødegaard at Norwegian University of Science and Technology in the late 1980s. The process takes place in an aeration tank with plastic carriers that a biofilm can grow on. The compact size and cheap wastewater treatment costs offers many advantages for the system. The main objective of using MBBR being water reuse and nutrient removal or recovery. In theory, wastewater will be no longer considered waste, it can be considered a resource. | 1 | Applied and Interdisciplinary Chemistry |
Despite current understanding of 3′-UTRs, they are still relative mysteries. Since mRNAs usually contain several overlapping control elements, it is often difficult to specify the identity and function of each 3′-UTR element, let alone the regulatory factors that may bind at these sites. Additionally, each 3′-UTR contains many alternative AU-rich elements and polyadenylation signals. These cis- and trans-acting elements, along with miRNAs, offer a virtually limitless range of control possibilities within a single mRNA. Future research through the increased use of deep-sequencing based ribosome profiling will reveal more regulatory subtleties as well as new control elements and AUBPs. | 1 | Applied and Interdisciplinary Chemistry |
The far-eastern blot is for the detection of lipid-linked oligosaccharides. High-performance thin-layer chromatography is first used to separate the lipids by physical and chemical characteristics, then transferred to a blotting matrix before the oligosaccharides are detected by a specific binding protein (i.e. antibodies or lectins). | 1 | Applied and Interdisciplinary Chemistry |
It was determined that each Chapter would have its own Council, the overall activities being determined by the Governing Board, on which each Council was represented, and an executive committee. | 1 | Applied and Interdisciplinary Chemistry |
Sulfidic (or euxinic) conditions, which exist today in many water bodies from ponds to various land-surrounded mediterranean seas such as the Black Sea, were particularly prevalent in the Cretaceous Atlantic but also characterised other parts of the world ocean. In an ice-free sea of these supposed super-greenhouse worlds, oceanic waters were as much as higher, in some eras. During the timespans in question, the continental plates are believed to have been well separated, and the mountains as they are known today were (mostly) future tectonic events—meaning the overall landscapes were generally much lower— and even the half super-greenhouse climates would have been eras of highly expedited water erosion carrying massive amounts of nutrients into the world oceans fuelling an overall explosive population of microorganisms and their predator species in the oxygenated upper layers.
Detailed stratigraphic studies of Cretaceous black shales from many parts of the world have indicated that two oceanic anoxic events (OAEs) were particularly significant in terms of their impact on the chemistry of the oceans, one in the early Aptian (~120 Ma), sometimes called the Selli Event (or OAE 1a) after the Italian geologist Raimondo Selli (1916–1983), and another at the Cenomanian–Turonian boundary (~93 Ma), also called the Bonarelli Event (or OAE2) after the Italian geologist Guido Bonarelli (1871–1951). OAE1a lasted for ~1.0 to 1.3 Myr. The duration of OAE2 is estimated to be ~820 kyr based on a high-resolution study of the significantly expanded OAE2 interval in southern Tibet, China.
* Insofar as the Cretaceous OAEs can be represented by type localities, it is the striking outcrops of laminated black shales within the vari-coloured claystones and pink and white limestones near the town of Gubbio in the Italian Apennines that are the best candidates.
* The 1-metre thick black shale at the Cenomanian–Turonian boundary that crops out near Gubbio is termed the Livello Bonarelli after the scientist who first described it in 1891.
More minor oceanic anoxic events have been proposed for other intervals in the Cretaceous (in the Valanginian, Hauterivian, Albian and Coniacian–Santonian stages), but their sedimentary record, as represented by organic-rich black shales, appears more parochial, being dominantly represented in the Atlantic and neighbouring areas, and some researchers relate them to particular local conditions rather than being forced by global change. | 0 | Theoretical and Fundamental Chemistry |
Throughout this section, the reduced Planck constant for convenience.
The product operator formalism is usually applied to sets of spin-1/2 particles, since the fact that the individual operators satisfy , where is the identity operator, makes the commutation relations of product operators particularly simple. In principle the formalism could be extended to higher spins, but in practice the general irreducible spherical tensor treatment is more often used. As such, we consider only the spin-1/2 case below.
The main idea of the formalism is to make it easier to follow the system density operator , which evolves under a Hamiltonian according to the Liouville-von Neumann equation as
For a time-independent Hamiltonian, the density operator inherits its solutions from the Schrödinger time-evolution operator as | 0 | Theoretical and Fundamental Chemistry |
The leuco form of malachite green was first prepared by Hermann Fischer in 1877 by condensing benzaldehyde and dimethylaniline in the molecular ratio 1:2 in the presence of sulfuric acid. | 0 | Theoretical and Fundamental Chemistry |
On the basis of experimental and computational studies, the stabilization arising from an agostic interaction is estimated to be 10–15 kcal/mol. Recent calculations using compliance constants point to a weaker stabilisation (<10 kcal/mol). Thus, agostic interactions are stronger than most hydrogen bonds. Agostic bonds sometimes play a role in catalysis by increasing rigidity in transition states. For instance, in Ziegler–Natta catalysis the highly electrophilic metal center has agostic interactions with the growing polymer chain. This increased rigidity influences the stereoselectivity of the polymerization process. | 0 | Theoretical and Fundamental Chemistry |
The following manufacturers have been involved in the development, design and planning of waste gas purification systems for a wide range of industries: Global manufacture of turnkey systems.
* American Fabrication and Supply, LLC | 1 | Applied and Interdisciplinary Chemistry |
Although the targets of CK2 are predominantly nucleus-based the protein itself is localized to both the nucleus and cytoplasm. Casein kinase 2 activity has been reported to be activated following Wnt signaling pathway activation. A Pertussis toxin-sensitive G protein and Dishevelled appear to be an intermediary between Wnt-mediated activation of the Frizzled receptor and activation of CK2. Further studies need to be done on the regulation of this protein due to the complexity of CK2 function and localization.
Phosphorylation of CK2α T344 has been shown to inhibit its proteasomal degradation and support binding to Pin1. O-GlcNAcylation at S347 antagonizes this phosphorylation and accelerates CK2α degradation. O-GlcNAcylation of CK2α has also been shown to alter the phosphoproteome, notably including many chromatin regulators such as HDAC1, HDAC2, and HCFC1. | 1 | Applied and Interdisciplinary Chemistry |
The asymptotic behavior of the central region can be investigated by taking the limit . From the figure, it can be observed that the density falls to zero very rapidly behind the shock wave. The entire mass of the gas which was initially spread out uniformly in a sphere of radius is now contained in a thin layer behind the shock wave, that is to say, all the mass is driven outwards by the acceleration imparted by the shock wave. Thus, most of the region is basically empty. The pressure ratio also drops rapidly to attain the constant value . The temperature ratio follows from the ideal gas law; since density ratio decays to zero and the pressure ratio is constant, the temperature ratio must become infinite. The limiting form for the density is given as follows
Remember that the density is time-independent whereas which means that the actual pressure is in fact time dependent. It becomes clear if the above forms are rewritten in dimensional units,
The velocity ratio has the linear behavior in the central region,
whereas the behavior of the velocity itself is given by | 1 | Applied and Interdisciplinary Chemistry |
In addition to books, technical reports, and conferences proceedings, WEF publishes the peer-reviewed journal, Water Environment Research, and the magazine, Water Environment Technology. WEF sponsors local and national speciality meetings, as well as the world's largest annual water conference: WEFTEC - Water Environment Federation Technical Exposition and Conference. | 1 | Applied and Interdisciplinary Chemistry |
The final STQ-77/FET framework classifies temperament traits and their neurochemical biomarkers into 12 components: nine components regulating the formal functional aspects of behaviour (energetic, dynamic and orientational) each assessed in three domains (intellectual, physical and social-verbal); also three components related to emotionality (Neuroticism, Impulsivity and Satisfaction (Self-Confidence)) (see Figure)
The FET framework summarized existing literature showing the nine non-emotionality traits are regulated by the monoamines (MA) (noradrenalin, dopamine, serotonin), acetylcholine and neuropeptide systems, whereas the three emotionality-related traits emerge as a dysregulation of opioid receptors systems that have direct control over MA systems. Importantly, the FET model suggests that there is no one-to-one correspondence between the neurotransmitter systems underlying temperament traits (or mental disorders) but instead specific ensemble relationships between these systems emerge as temperament traits. The FET framework is based only on the strongest consensus points in the research studying the role of neurotransmitter in behavioural regulation and the components of temperament; it doesn't list more controversial links between these multiple systems.
Neurotransmitter systems: 5-HT: serotonin; DA: dopamine; NE: noradrenalin; ACh: acetylcholine; Glu: glutamate; OXY: oxytocin; VSP: vasopressin; NP: Neuropeptides; KOR, MOR, DOR: kappa-, mu- and delta-opioid receptors correspondingly; sANS - sympathetic autonomic nervous system; HPA - hypothalamic–pituitary–adrenal axis.
The FET points out that opioid receptor systems are involved not only in regulation of emotional dispositions but also amplify three non-emotionality aspects of behaviour (KOR for orientation, DOR for integration of actions and MOR of approval-maintenance of behaviour). This involvement was confirmed for MOR systems that bind endorphins: experiments show that MOR overstimulation influences hypothalamic serotonin and Brain-derived neurotrophic factor release and affecting endurance aspects of behaviour. The interplay within hormonal systems and its interaction with serotonin also appeared to be a factor is social emotions, such as shame and guilt | 1 | Applied and Interdisciplinary Chemistry |
Polymer-protein hybrids are a class of nanostructure composed of protein-polymer conjugates (i.e. complexes composed of one protein attached to one or more polymer chains). The protein component generally gives the advantages of biocompatibility and biodegradability, as many proteins are produced naturally by the body and are therefore well tolerated and metabolized. Although proteins are used as targeted therapy drugs, the main limitations—the lack of stability and insufficient circulation times still remain. Therefore, protein-polymer conjugates have been investigated to further enhance pharmacologic behavior and stability. By adjusting the chemical structure of the protein-polymer conjugates, polymer-protein particles with unique structures and functions, such as stimulus responsiveness, enrichment in specific tissue types, and enzyme activity, can be synthesized. Polymer-protein particles have been the focus of much research recently because they possess potential uses including bioseparations, imaging, biosensing, gene and drug delivery. | 1 | Applied and Interdisciplinary Chemistry |
The incompressible Navier–Stokes equations in the absence of body force, and in two spatial dimensions, are given by
The first of the above equation represents the continuity equation and the other two represent the momentum equations. | 1 | Applied and Interdisciplinary Chemistry |
T cell - T-cell antigen receptors - tachykinin - tachykinin receptor - talin protein - tandem repeat sequence - taste bud - TATA box - tax gene product - taxonomy - telophase - tertiary structure - tetrodotoxin - thermochemistry - thermometer - thiamin - thioredoxin - threonine - thrombin - thrombin receptor - thrombomodulin - thromboxane receptor - thylakoid - thyroid hormone receptor - thyrotropin - thyrotropin receptor - thyrotropin-releasing hormone receptor - thyroxine - timeline of biology and organic chemistry - titration - tobacco mosaic virus - topoisomerase - toxin - trans-activator - transcription factor - transcription factor AP-1 - transducin - transformation - transforming growth factor - transforming growth factor alpha - transforming growth factor beta - transforming growth factor beta receptor - transient receptor potential - translation (biology) - transmembrane ATPase - transmembrane helix - transmembrane protein - transmembrane receptor - transport protein - transport vesicle - triiodothyronine - trinucleotide repeat - triose - tropomyosin - troponin - tryptophan - tubulin - tumor necrosis factors - tumor necrosis factor receptor - tyrosine - tyrosine 3-monooxygenase | 1 | Applied and Interdisciplinary Chemistry |
A nonsense mutation in one gene of an operon prevents the translation of subsequent genes in the unit. This effect is called mutational polarity. A common cause is the absence of the mRNA corresponding to the subsequent (distal) parts of the unit. Suppose that there are Rho-dependent terminators within the transcription unit, that is, before the terminator that usually is used. Normally these earlier terminators are not used, because the ribosome prevents Rho from reaching RNA polymerase. But a nonsense mutation releases the ribosome, so that Rho is free to attach to and/or move along the RNA, enabling it to act on RNA polymerase at the terminator. As a result, the enzyme is released, and the distal regions of the transcription unit are never transcribed. | 1 | Applied and Interdisciplinary Chemistry |
Dichroic glass has one or several coatings in the nanometer-range (for example metals, metal oxides, or nitrides) which give the glass dichroic optical properties. Also the blue appearance of some automobile windshields is caused by dichroism. | 0 | Theoretical and Fundamental Chemistry |
SIN3B has been shown to interact with HDAC1, Zinc finger and BTB domain-containing protein 16, SUDS3 and IKZF1. | 1 | Applied and Interdisciplinary Chemistry |
Antibodies coating paramagnetic beads will bind to antigens present on the surface of cells thus capturing the cells and facilitate the concentration of these bead-attached cells. The concentration process is created by a magnet placed on the side of the test tube bringing the beads to it.
MACS systems (Magnetic Cell Separation system):
Through the usage of smaller super paramagnetic beads (<100 nm), which requires a stronger magnetic field to separate cells. Cells are labeled with primary antibodies and then MACS beads are coated with specific- specific antibodies. These labeled cell suspension is then put into a separation column in a strong magnetic field. The labeled cells are contained, magnetized, while in the magnetic field and the unlabeled cells are suspended, un-magnetized, to be collected. Once removed from magnetic field positive cells are eluted. These MACS beads are then incorporated by the cells allowing them to remain in the column because they do not intrude with the cell attachment to the culture surface to cell-cell interactions. A bead removal reagent is then applied to have an enzymatically release of the MACS beads allowing those cells to become relabeled with some other marker, which then is sorted. | 1 | Applied and Interdisciplinary Chemistry |
Whenever there is a balance between a bulk elastic energy contribution and a surface energy term, surface stresses can be important. Surface contributions are more important at small sizes, so surface stress effects are often important at the nanoscale. | 0 | Theoretical and Fundamental Chemistry |
Mediator is a multiprotein complex that functions as a transcriptional coactivator. The Mediator complex is required for the successful transcription of nearly all class II gene promoters in yeast. It works in the same manner in mammals.
The mediator functions as a coactivator and binds to the C-terminal domain (CTD) of RNA polymerase II holoenzyme, acting as a bridge between this enzyme and transcription factors. | 1 | Applied and Interdisciplinary Chemistry |
In the final synthetic steps (scheme 8) the amide tail 62 was added to ABCD ring 52 in an esterification catalysed by o,o'-di(2-pyridyl) thiocarbonate (DPTC) and DMAP forming ester 63. The Bn protecting group was removed by hydrogenation using palladium hydroxide on carbon (64) and finally the TES group was removed by HF and pyridine to yield Taxol 65. | 0 | Theoretical and Fundamental Chemistry |
Screening tools for the development of new cancer therapies are in high demand worldwide and often require the determination of enzyme kinetics. The high sensitivity of lanthanide luminescence, particularly of time-resolved luminescence has revealed to be an ideal candidate for this purpose. There are several ways of conducting this analysis by the use of fluorogenic enzyme substrates, substrates bearing donor/acceptor groups allowing fluorescence resonance energy transfer (FRET) and immunoassays. For example, guanine nucleotide binding proteins consist of several subunits, one of which comprises those of the Ras subfamily. Ras GTPases act as binary switches by converting guadenosine triphosphate (GTP) into guadenosine diphosphate (GDP). Luminescence of the Tb(III) complex with norfloxacin is sensitive to determine the concentration of phosphate released by the GTP to GDP transformation. | 1 | Applied and Interdisciplinary Chemistry |
The oil and gas industry uses media filters for various purposes in both upstream and downstream operations. Nut shell filters are commonly used as a tertiary oil removal step for treatment of produced water. Sand filters are often used to remove fine solids following biological treatment and clarification of oil refinery wastewater. Multi-media filters are used for removing suspended solids from both produced water and refinery wastewater. The materials commonly used in multi-media filters are gravel, sand, garnet, and anthracite. | 1 | Applied and Interdisciplinary Chemistry |
The term ramogen refers to a biological factor, typically a growth factor or other protein, that causes a developing biological cell or tissue to branch in a tree-like manner. Ramogenic molecules are branch promoting molecules found throughout the human body,.
Brief History
The term was first coined (from the Latin ramus = branch and the Greek genesis = creation) in an article about kidney development by Davies and Davey (Pediatr Nephrol. 1999 Aug;13(6):535-41). In the article, Davies and Davy describe the existence of "ramogens" in the kidney as glial cell line-derived neurotrophic factors, neurturin and persephin. The term has now passed into general use in the technical literature concerned with branching of biological structures.
Function
A ramogen is a biochemical signal that enables the creation of a physiological branch. The signal can be in the form of a growth factor or a hormone that makes a tube branch. One specific example would be the hormone that forms the simple tube through which the mammary glands begin to form causing the formation of a highly branched “tree” of milk ducts in females.
Types of Ramogens
Mesenchyme-derived ramogens are found throughout the body and serve as chemoattractants to branching tissues.
An example of how this works is found through a study on a bead soaked in the renal ramogen GDNF. When this ramogen was placed next to a kidney sample in culture, the nearby uteric parts branch and grow toward it.
Another example of a ramogen in use was found in the lungs. The existence of Sprouty2 in the body is demonstrated in response to the signaling of the ramogen FGF10, serving as an inhibitor of branching.
The following table is a list of Key Ramogens in Branching Organs of a mouse species.
Studies involving Ramogens
The physiological capabilities of ramogens are still being postulated in medical studies involving kidney functions on mice.
In development maturing nephrons and stroma in the body may cease to produce ramogens and may begin to secrete anti-ramogenic factors, such as Bmp2 and Tgfβ.
The pattern of branching and the rate of cell proliferation can contribute to the shape of different organs. As such, the use of the glial-cell-line neurotrophic factor (GDNF) has been found to contribute to uterine tissues.
The implication of this is that the introduction of ramogens to the body can cause cell repair through the creation of side branches introduced through ramogenic signals in the body ).
This is evidenced through studies demonstrating that uterine stalks were capable of forming new tips if provided with fresh mesenchyme or with a Matrigel artificially loaded with ramogens, such as GDNF and FGF1. The ramogens used in this study were manufactured with fresh mesenchyme. | 1 | Applied and Interdisciplinary Chemistry |
In June 2023, astronomers detected, for the first time outside the Solar System, methyl cation, CH (and/or carbon cation, C), the known basic ingredients of life, in interstellar space. | 0 | Theoretical and Fundamental Chemistry |
The major ARCHER subsystem components include:
* advanced hyperspectral imaging (HSI) system with a resolution of one square meter per pixel.
* panchromatic high-resolution imaging (HRI) camera with a resolution of per pixel.
* global positioning system (GPS) integrated with an inertial navigation system (INS) | 0 | Theoretical and Fundamental Chemistry |
The CTCF insulator appears to have enhancer blocking activity via its 3D structure and have no direct connection with barrier activity. Vertebrates in particular appear to rely heavily on the CTCF insulator, however there are many different insulator sequences identified. Insulated neighborhoods formed by physical interaction between two CTCF-bound DNA loci contain the interactions between enhancers and their target genes. | 1 | Applied and Interdisciplinary Chemistry |
Oxalosuccinic acid is a substrate of the citric acid cycle. It is acted upon by isocitrate dehydrogenase. Salts and esters of oxalosuccinic acid are known as oxalosuccinates.
Oxalosuccinic acid/oxalosuccinate is an unstable 6-carbon intermediate in the tricarboxylic acid cycle. It's a keto acid, formed during the oxidative decarboxylation of isocitrate to alpha-ketoglutarate, which is catalyzed by the enzyme isocitrate dehydrogenase. Isocitrate is first oxidized by coenzyme NAD+ to form oxalosuccinic acid/oxalosuccinate. Oxalosuccinic acid is both an alpha-keto and a beta-keto acid (an unstable compound) and it is the beta-ketoic property that allows the loss of carbon dioxide in the enzymatic reaction in conversion to the five-carbon molecule 2-oxoglutarate. | 1 | Applied and Interdisciplinary Chemistry |
Auxiliary metabolic genes (AMGs) are found in many bacteriophages but originated in bacterial cells. AMGs modulate host cell metabolism during infection so that the phage can replicate more efficiently. For instance, bacteriophages that infect the abundant marine cyanobacteria Synechococcus and Prochlorococcus (cyanophages) carry AMGs that have been acquired from their immediate host as well as more distantly-related bacteria. Cyanophage AMGs support a variety of functions including photosynthesis, carbon metabolism, nucleic acid synthesis and metabolism. AMGs also have broader ecological impacts beyond their host including their influence on biogeochemical cycling. | 1 | Applied and Interdisciplinary Chemistry |
Spatial particle-based methods differ from the methods described above by their explicit representation of space.
One example of a particle-based simulator that allows for a representation of cellular compartments is SRSim. SRSim is integrated in the LAMMPS molecular dynamics simulator and allows the user to specify the model in BNGL. SRSim allows users to specify the geometry of the particles in the simulation, as well as interaction sites. It is therefore especially good at simulating the assembly and structure of complex biomolecular complexes, as evidenced by a recent model of the inner kinetochore.
MCell allows individual molecules to be traced in arbitrarily complex geometric environments which are defined by the user. This allows for simulations of biomolecules in realistic reconstructions of living cells, including cells with complex geometries like those of neurons. The reaction compartment is a reconstruction of a dendritic spine.
MCell uses an ad-hoc formalism within MCell itself to specify a multi-state model: In MCell, it is possible to assign "slots" to any molecular species. Each slot stands for a particular modification, and any number of slots can be assigned to a molecule. Each slot can be occupied by a particular state. The states are not necessarily binary. For instance, a slot describing binding of a particular ligand to a protein of interest could take the states "unbound", "partially bound", and "fully bound".
The slot-and-state syntax in MCell can also be used to model multimeric proteins or macromolecular complexes. When used in this way, a slot is a placeholder for a subunit or a molecular component of a complex, and the state of the slot will indicate whether a specific protein component is absent or present in the complex. A way to think about this is that MCell macromolecules can have several dimensions: A "state dimension" and one or more "spatial dimensions". The "state dimension" is used to describe the multiple possible states making up a multi-state protein, while the spatial dimension(s) describe topological relationships between neighboring subunits or members of a macromolecular complex. One drawback of this method for representing protein complexes, compared to Meredys, is that MCell does not allow for the diffusion of complexes, and hence, of multi-state molecules. This can in some cases be circumvented by adjusting the diffusion constants of ligands that interact with the complex, by using checkpointing functions or by combining simulations at different levels. | 1 | Applied and Interdisciplinary Chemistry |
Oncometabolites are metabolites whose abundance increases markedly in cancer cells through loss-of-function or gain-of-function mutations in specific enzymes involved in their production, the accumulation of these endogenous metabolites initiates or sustains tumor growth and metastasis. Cancer cells rely on aerobic glycolysis, which is reached through defects in enzymes involved in normal cell metabolism, this allows the cancer cells to meet their energy needs and divert acetyl-CoA from the TCA cycle to build essential biomolecules such as amino acids and lipids. These defects cause an overabundance of endogenous metabolites, which are frequently involved in critical epigenetic changes and signaling pathways that have a direct impact on cancer cell metabolism. | 1 | Applied and Interdisciplinary Chemistry |
Butanol can be made from algae or diatoms using only a solar powered biorefinery. This fuel has an energy density 10% less than gasoline, and greater than that of either ethanol or methanol. In most gasoline engines, butanol can be used in place of gasoline with no modifications. In several tests, butanol consumption is similar to that of gasoline, and when blended with gasoline, provides better performance and corrosion resistance than that of ethanol or E85.
The green waste left over from the algae oil extraction can be used to produce butanol. In addition, it has been shown that macroalgae (seaweeds) can be fermented by bacteria of genus Clostridia to butanol and other solvents. Transesterification of seaweed oil (into biodiesel) is also possible with species such as Chaetomorpha linum, Ulva lactuca, and Enteromorpha compressa (Ulva).
The following species are being investigated as suitable species from which to produce ethanol and/or butanol:
* Alaria esculenta
* Laminaria saccharina
* Palmaria palmata | 1 | Applied and Interdisciplinary Chemistry |
Precession electron diffraction is typically conducted using accelerating voltages between 100-400 kV. Patterns can be formed under parallel or convergent beam conditions. Most modern TEMs can achieve a tilt angle, φ, ranging from 0-3°. Precession frequencies can be varied from Hz to kHz, but in standard cases 60 Hz has been used. In choosing a precession rate, it is important to ensure that many revolutions of the beam occur over the relevant exposure time used to record the diffraction pattern. This ensures adequate averaging over the excitation error of each reflection. Beam sensitive samples may dictate shorter exposure times and thus, motivate the use of higher precession frequencies.
One of the most significant parameters affecting the diffraction pattern obtained is the precession angle, φ. In general, larger precession angles result in more kinematical diffraction patterns, but both the capabilities of the beam tilt coils in the microscope and the requirements on the probe size limit how large this angle can become in practice. Because PED takes the beam off of the optic axis by design, it accentuates the effect of the spherical aberrations within the probe forming lens. For a given spherical aberration, C, the probe diameter, d, varies with convergence angle, α, and precession angle, φ, as
Thus, if the specimen of interest is quite small, the maximum precession angle will be restrained. This is most significant for conditions of convergent beam illumination. 50 nm is a general lower limit on probe size for standard TEMs operating at high precession angles (>30 mrad), but can be surpassed in C corrected instruments. In principle the minimum precessed probe can reach approximately the full-width-half-max (FWHM) of the converged un-precessed probe in any instrument, however in practice the effective precessed probe is typically ~10-50x larger due to uncontrolled aberrations present at high angles of tilt. For example, a 2 nm precessed probe with >40 mrad precession angle was demonstrated in an aberration-corrected Nion UltraSTEM with native sub-Å probe (aberrations corrected to ~35 mrad half-angle).
If the precession angle is made too large, further complications due to the overlap of the ZOLZ and HOLZ reflections in the projected pattern can occur. This complicates the indexing of the diffraction pattern and can corrupt the measured intensities of reflections near the overlap region, thereby reducing the effectiveness of the collected pattern for direct methods calculations. | 0 | Theoretical and Fundamental Chemistry |
The stereochemical outcome of a glycosylation reaction may in certain cases be affected by the type of protecting group employed at position 2 of the glycosyl donor. A participating group, typically one with a carboxyl group present, will predominantly result in the formation of a β-glycoside. Whereas a non-participating group, a group usually without a carboxyl group, will often result in an α-glycoside.
Below it can be seen that having an acetyl protecting group at position 2 allows for the formation for an acetoxonium ion intermediate that blocks attack to the bottom face of the ring therefore allowing for the formation of the β-glycoside predominantly.
Alternatively, the absence of a participating group at position 2 allows for either attack from the bottom or top face. Since the α-glycoside product will be favoured by the anomeric effect, the α-glycoside usually predominates. | 0 | Theoretical and Fundamental Chemistry |
Deprotonation of enolizable ketones, aromatic alcohols, aldehydes, and esters gives enolates. With strong bases, the deprotonation is quantitative. Typically enolates are generated from using lithium diisopropylamide (LDA).
Often, as in conventional Claisen condensations, Mannich reactions, and aldol condensations, enolates are generated in low concentrations with alkoxide bases. Under such conditions, they exist in low concentrations, but they still undergo reactions with electrophiles. Many factors affect the behavior of enolates, especially the solvent, additives (e.g. diamines), and the countercation (Li vs Na, etc.). For unsymmetrical ketones, methods exist to control the regiochemistry of the deprotonation.
The deprotonation of carbon acids can proceed with either kinetic or thermodynamic reaction control. For example, in the case of phenylacetone, deprotonation can produce two different enolates. LDA has been shown to deprotonate the methyl group, which is the kinetic course of the deprotonation. To ensure the production of the kinetic product, a slight excess (1.1 equiv) of lithium diisopropylamide is used, and the ketone is added to the base at −78 °C. Because the ketone is quickly and quantitatively converted to the enolate and base is present in excess at all times, the ketone is unable to act as a proton shuttle to catalyze the gradual formation of the thermodynamic product. A weaker base such as an alkoxide, which reversibly deprotonates the substrate, affords the more thermodynamically stable benzylic enolate.
Enolates can be trapped by acylation and silylation, which occur at oxygen. Silyl enol ethers are common reagents in organic synthesis as illustrated by the Mukaiyama aldol reaction: | 0 | Theoretical and Fundamental Chemistry |
Bacteriophage derived proteins are used for detection and removal of bacteria and bacterial components (especially endotoxin contaminations) in pharmaceutical and biological products, human diagnostics, food, and decolonization of bacteria causing nosocomial infections (e.g. MRSA).
Protein modifications allow the biotechnological adaption to specific requirements. | 1 | Applied and Interdisciplinary Chemistry |
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