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Berberine bridge enzyme-like (BBE-like enzymes) form a subgroup of the superfamily of FAD-linked oxidases (SCOPe d.58.32), structurally characterized by a typical fold observed initially for vanillyl-alcohol oxidase (VAO). This proteins are part of a multigene family (PF08031) that can be found in plants, fungi and bacteria.
BBE-like enzymes family form a large subgroup that have a special C-terminal structural element adjacent to the substrate binding region. An homonym of this family is the (S)-reticuline oxidase or berberine bridge enzyme from California poppy (Eschscholzia californica), the responsible of catalyzing the conversion of (S)-reticuline to (S)-scoulerine. This conversion is made by an oxidative ring closure reaction. The product of this reaction is the C-C bond and is referred to as the berberine bridge. Also, marks a branch point in the biosynthesis of benzylisoquinoline alkaloids.
As mentioned above, BBE-like enzymes are in the large family of FAD-linked oxidases. Regarding the structure of this particular family, they have a FAD binding module formed by the N- and C- terminal parts of the protein. There is a substrate binding module that, in collaboration with isoalloxazine ring of FAD, disposes the environment for efficient substrate binding and oxidation. | 1 | Applied and Interdisciplinary Chemistry |
A typical experiment, consists of a glass tube of volume V, and of cross-section A, which is open on one of its end. A ball (or sometimes a piston) of mass m with the same cross-section, creating an air-tight seal, is allowed to fall under gravity g. The entrapped gas is first compressed by the weight of the piston, which leads to an increase in temperature. In the course of the piston falling, a gas cushion is created, and the piston bounces. Harmonic oscillation occurs, which slowly damps. The result is a rapid sequence of expansion and compression of the gas. The picture shows a revised version of the original Rüchardt setup: the sphere oscillating inside the tube is here replaced by a "breast-pump" which acts as an oscillating glass-piston; in this new setup three sensors allow to measure in real-time the piston oscillations as well as the pressure and temperature oscillations of the air inside the bottle (more details may be found in )
According to Figure 1, the piston inside the tube is in equilibrium if the pressure P inside the glass bottle is equal to the sum of the atmospheric pressure P and the pressure increase due to the piston weight :
When the piston moves beyond the equilibrium by a distance dx, the pressure changes by dp. A force F will be exerted on the piston, equal to
According to Newtons second law of motion, this force will create an acceleration a' equal to
As this process is adiabatic, the equation for ideal gas (Poisson's equation) is:
It follows using differentiation from the equation above that:
If the piston moves by a distance in the glass tube, the corresponding change in volume will be
By substituting equation into equation , we can rewrite as follows:
Solving this equation and rearranging terms yields the differential equation of a harmonic oscillation from which the angular frequency ω can be deduced:
From this, the period T of harmonic oscillation performed by the ball is:
Measuring the period of oscillation T and the relative pressure P in the tube yields the equation for the adiabatic exponent: | 0 | Theoretical and Fundamental Chemistry |
Some reports have been published on the pharmacokinetics of CoQ. The plasma peak can be observed 6-8 hours after oral administration when taken as a pharmacological substance. In some studies, a second plasma peak also was observed at approximately 24 hours after administration, probably due to both enterohepatic recycling and redistribution from the liver to circulation.
Deuterium-labeled crystalline CoQ was used to investigate pharmacokinetics in humans to determine an elimination half-time of 33 hours. | 1 | Applied and Interdisciplinary Chemistry |
Various estimates for the efficiency of quantum reflection of waves from ridged mirror were discussed in the literature. All the estimates explicitly use the de Broglie theory about wave properties of reflected atoms. | 0 | Theoretical and Fundamental Chemistry |
Source: [http://www.asbmb.org/awards/cohn/ American Society for Biochemistry and Molecular Biology]
*2020 - Carol Fierke
*2019 - Angela Gronenborn
*2018 – Leemor Joshua-Tor
*2017 – Wei Yang
*2016 – Eva Nogales
*2015 – Judith P. Klinman
*2014 – Lila M. Gierasch
*2013 – Jennifer A. Doudna | 1 | Applied and Interdisciplinary Chemistry |
Electrofiltration is a technique for separation and concentration of colloidal substances – for instance biopolymers. The principle of electrofiltration is based on overlaying electric field on a standard dead-end filtration. Thus the created polarity facilitates electrophoretic force which is opposite to the resistance force of the filtrate flow and directs the charged biopolymers. This provides extreme decrease in the film formation on the micro- or ultra-filtration membranes and the reduction of filtration time from several hours by standard filtration to a few minutes by electrofiltration. In comparison to cross-flow filtration electrofiltration exhibits not only increased permeate flow but also guarantees reduced shear force stress which qualifies it as particularly mild technique for separation of biopolymers that are usually unstable.
The promising application in purification of biotechnological products is based on the fact that biopolymers are difficult for filtration but on the other hand they are usually charged as a result of the presence of amino and carboxyl groups. The objective of electrofiltration is to prevent the formation of filter cake and to improve the filtration kinetic of products difficult to filtrate.
The electrophoresis of the particles and the electro-osmosis become essential when the filtration process is overlaid with electric field. By electrofiltration the conventional filtration is overlaid with an electric field (DC) which works parallel with the filtrate’s flow direction. When the electrophoretic force F, oppositely directed to flow, overruns the hydrodynamic resistance force F, the charged particles migrate from the filter medium, thus reducing significantly the thickness of the filter cake on the membrane.
When the solid particles, subject to separation, are negatively charged they migrate towards the anode (positive pole) and deposit on the filter cloth situated there. As a result, on the cathode side’s membrane (negative pole) there is only a very thin film allowing nearly the whole filtrate to efflux through this membrane.
Figure 1 presents schematic description of electrofiltration chamber with flushing electrodes. For the flushing circulation a buffer solution is used. This approach has been patented. | 0 | Theoretical and Fundamental Chemistry |
Rickets, a childhood disease, is characterized by impeded growth and soft, weak, deformed long bones that bend and bow under their weight as children start to walk. Rickets typically appears between 3 and 18 months of age. Cases continue to be reported in North American and other Western Countries and is primarily seen in breastfed infants and those with darker skin complexions. This condition is characterized by bow legs, which can be caused by calcium or phosphorus deficiency, as well as a lack of vitamin D; in the 21st century, it is largely found in low-income countries in Africa, Asia, or the Middle East and in those with genetic disorders such as pseudo-vitamin-D-deficiency rickets.
Maternal vitamin D deficiency may cause overt bone disease from before birth and impairment of bone quality after birth. Nutritional rickets exists in countries with intense year-round sunlight such as Nigeria and can occur without vitamin D deficiency.
Although rickets and osteomalacia are now rare in the United Kingdom, outbreaks have happened in some immigrant communities in which people with osteomalacia included women with seemingly adequate daylight outdoor exposure wearing Western clothing. Having darker skin and reduced exposure to sunshine did not produce rickets unless the diet deviated from a Western omnivore pattern characterized by high intakes of meat, fish, and eggs. The dietary risk factors for rickets include abstaining from animal foods.
Vitamin D deficiency remains the main cause of rickets among young infants in most countries because breast milk is low in vitamin D and social customs and climatic conditions can prevent adequate sun exposure. In sunny countries such as Nigeria, South Africa, and Bangladesh, where rickets occurs among older toddlers and children, it has been attributed to low dietary calcium intakes, which are characteristic of cereal-based diets with limited access to dairy products.
Rickets was formerly a major public health problem among the US population. In Denver, almost two-thirds of 500 children had mild rickets in the late 1920s. An increase in the proportion of animal protein in the 20th century American diet coupled with increased consumption of milk fortified with relatively small quantities of vitamin D coincided with a dramatic decline in the number of rickets cases. Also, in the United States and Canada, vitamin D-fortified milk, infant vitamin supplements, and vitamin supplements have helped to eradicate the majority of cases of rickets for children with fat malabsorption conditions. | 1 | Applied and Interdisciplinary Chemistry |
As indicated in the table below, many hydrates of metal chlorides are molecular complexes. These compounds are often important commercial sources of transition metal chlorides. Several hydrated metal chlorides are not molecular and thus are not included in this tabulation. For example the dihydrates of manganese(II) chloride, nickel(II) chloride, copper(II) chloride, iron(II) chloride, and cobalt(II) chloride are coordination polymers. | 0 | Theoretical and Fundamental Chemistry |
In plant physiology, the Warburg effect is the decrease in the rate of photosynthesis due to high oxygen concentrations. Oxygen is a competitive inhibitor of carbon dioxide fixation by RuBisCO which initiates photosynthesis. Furthermore, oxygen stimulates photorespiration which reduces photosynthetic output. These two mechanisms working together are responsible for the Warburg effect. | 0 | Theoretical and Fundamental Chemistry |
Flutamide has been found to be effective in the treatment of acne and seborrhea in women in a number of studies. In a long-term study of 230 women with acne, 211 of whom also had seborrhea, very-low-dose flutamide alone or in combination with an oral contraceptive caused a marked decrease in acne and seborrhea after 6 months of treatment, with maximal effect by 1 year of treatment and benefits maintained in the years thereafter. In the study, 97% of the women reported satisfaction with the control of their acne with flutamide. In another study, flutamide decreased acne and seborrhea scores by 80% in only 3 months. In contrast, spironolactone decreased symptoms by only 40% in the same time period, suggesting superior effectiveness for flutamide for these indications. Flutamide has, in general, been found to reduce symptoms of acne by as much as 90% even at low doses, with several studies showing complete acne clearance. | 0 | Theoretical and Fundamental Chemistry |
All jet engines are reaction engines that generate thrust by emitting a jet of fluid rearwards at relatively high speed. The forces on the inside of the engine needed to create this jet give a strong thrust on the engine which pushes the craft forwards.
Jet engines make their jet from propellant stored in tanks that are attached to the engine (as in a rocket) as well as in duct engines (those commonly used on aircraft) by ingesting an external fluid (very typically air) and expelling it at higher speed. | 1 | Applied and Interdisciplinary Chemistry |
Ribosomal frameshifting may be controlled by mechanisms found in the mRNA sequence (cis-acting). This generally refers to a slippery sequence, a RNA secondary structure, or both. A −1 frameshift signal consists of both elements separated by a spacer region typically 5–9 nucleotides long. Frameshifting may also be induced by other molecules which interact with the ribosome or the mRNA (trans-acting). | 1 | Applied and Interdisciplinary Chemistry |
In this method, plant nuclei are isolated by physically grinding tissues and reconstituting the intact nuclei in a unique Nuclear Isolation Buffer (NIB). The plastid DNAs are released from organelles and eliminated with an osmotic buffer by washing and centrifugation. The purified nuclei are then lysed and further cleaned by organic extraction, and the genomic DNA is precipitated with a high concentration of CTAB. The highly pure, high molecular weight gDNA is extracted from the nuclei, dissolved in a high pH buffer, allowing for stable long-term storage. | 1 | Applied and Interdisciplinary Chemistry |
MDI is commonly used in the manufacture of rigid foams and surface coating. Polyurethane foam boards are used in construction for insulation. TDI is commonly used in applications where flexible foams are used, such as furniture and bedding. Both MDI and TDI are used in the making of adhesives and sealants due to weather-resistant properties. Isocyanates, both MDI and TDI are widely used in as spraying applications of insulation due to the speed and flexibility of applications. Foams can be sprayed into structures and harden in place or retain some flexibility as required by the application. HDI is commonly utilized in high-performance surface-coating applications, including automotive paints. | 0 | Theoretical and Fundamental Chemistry |
The methodology of inference involves a combination of induction and deduction by moving from particular to particular via generality. It has five steps, as in the example shown:
* There is fire on the hill (called Pratijñā, required to be proved)
* Because there is smoke there (called Hetu, reason)
* Wherever there is smoke, there is fire, e.g. in a kitchen (called Udāhārana, example of vyāpti)
* The hill has smoke that is pervaded by fire (called Upanaya, reaffirmation or application)
* Therefore, there is fire on the hill (called Nigamana, conclusion)
In Nyāya terminology for this example, the hill would be the paksha (minor term), the fire is the sādhya (major term), the smoke is hetu, and the relationship between the smoke and the fire is vyapti(middle term).
Hetu further has five characteristics
* It must be present in the Paksha (the case under consideration),
* It must be present in all positive instances (sapaksha, or homologues),
* It must be absent in all negative instances
* It must not be incompatible with an established truth, (abādhitatva)
* Absence of another evidence for the opposite thesis (asatpratipakshitva)
The fallacies in Anumana (hetvābhasa) may occur due to the following
#Asiddha: It is the unproved hetu that results in this fallacy.
#*Ashrayasiddha: If Paksha [minor term] itself is unreal, then there cannot be locus of the hetu. e.g. The sky-lotus is fragrant, because it is a lotus like any other lotus.
#*Svarupasiddha: Hetu cannot exist in paksa at all. E.g. Sound is a quality, because it is visible.
#*Vyapyatvasiddha: Conditional hetu. `Wherever there is fire, there is smoke'. The presence of smoke is due to wet fuel.
#Savyabhichara: This is the fallacy of irregular hetu.
#*Sadharana: The hetu is too wide. It is present in both sapaksa and vipaksa. `The hill has fire because it is knowable'.
#*Asadharana: The hetu is too narrow. It is only present in the Paksha, it is not present in the Sapaksa and in the Vipaksha. `Sound is eternal because it is audible'.
#*Anupasamhari: Here the hetu is non-exclusive. The hetu is all-inclusive and leaves nothing by way of sapaksha or vipaksha. e.g. All things are non-ternal, because they are knowable.
#Satpratipaksa: Here the hetu is contradicted by another hetu. If both have equal force, then nothing follows. Sound is eternal, because it is audible, and Sound is non-eternal, because it is produced. Here audible is counterbalanced by produced and both are of equal force.
#Badhita: When another proof (as by perception) definitely contradicts and disproves the middle term (hetu). Fire is cold because it is a substance.
#Viruddha: Instead of proving something it is proving the opposite. Sound is eternal because it is produced. | 1 | Applied and Interdisciplinary Chemistry |
The two-dimensional stagnation-point flow belongs to the case . The flow field is described as follows
where we let . This flow field is investigated as early as 1934 by G. I. Taylor. In the laboratory, this flow field is created using a four-mill apparatus, although these flow fields are ubiquitous in turbulent flows. | 1 | Applied and Interdisciplinary Chemistry |
In a solid, shear stress is a function of strain, but in a fluid, shear stress is a function of strain rate. A consequence of this behavior is Pascals law which describes the role of pressure in characterizing a fluids state.
The behavior of fluids can be described by the Navier–Stokes equations—a set of partial differential equations which are based on:
* continuity (conservation of mass),
* conservation of linear momentum,
* conservation of angular momentum,
* conservation of energy.
The study of fluids is fluid mechanics, which is subdivided into fluid dynamics and fluid statics depending on whether the fluid is in motion. | 1 | Applied and Interdisciplinary Chemistry |
The stability of individual atropisomers is conferred by the repulsive interactions that inhibit rotation. Both the steric bulk and, in principle, the length and rigidity of the bond connecting the two subunits contribute. Commonly, atropisomerism is studied by dynamic nuclear magnetic resonance spectroscopy, since atropisomerism is a form of fluxionality. Inferences from theory and results of reaction outcomes and yields also contribute.
Atropisomers exhibit axial chirality (planar chirality). When the barrier to racemization is high, as illustrated by the BINAP ligands, the phenomenon becomes of practical value in asymmetric synthesis. Methaqualone, the anxiolytic and hypnotic-sedative, is a classical example of a drug molecule that exhibits the phenomenon of atropisomerism. | 0 | Theoretical and Fundamental Chemistry |
A colorimeter is a device used in colorimetry that measures the absorbance of particular wavelengths of light by a specific solution. It is commonly used to determine the concentration of a known solute in a given solution by the application of the Beer–Lambert law, which states that the concentration of a solute is proportional to the absorbance. | 0 | Theoretical and Fundamental Chemistry |
The International Maritime Organization (IMO) has adopted guidelines on the approval, installation and use of exhaust gas scrubbers (exhaust gas cleaning systems) on board ships to ensure compliance with the sulphur regulation of MARPOL Annex VI. Flag States must approve such systems and port States can (as part of their port state control) ensure that such systems are functioning correctly. If a scrubber system is not functioning properly (and the IMO procedures for such malfunctions are not adhered to), port States can sanction the ship. The United Nations Convention on the Law Of the Sea also bestows port States with a right to regulate (and even ban) the use of open loop scrubber systems within ports and internal waters. | 1 | Applied and Interdisciplinary Chemistry |
Alison Butler is a Distinguished Professor in the Department of Chemistry and Biochemistry at the University of California, Santa Barbara. She works on bioinorganic chemistry and metallobiochemistry. She is a Fellow of the American Association for the Advancement of Science (1997), the American Chemical Society (2012), the American Academy of Arts and Sciences (2019), and the Royal Society of Chemistry (2019). She was elected a member of the National Academy of Sciences in 2022. | 0 | Theoretical and Fundamental Chemistry |
One measure of air pollution used in air quality standards is the atmospheric concentration of particulate matter. This measure is usually expressed in μg/m (micrograms per cubic metre). In the current EU emission norms for cars, vans, and trucks and in the upcoming EU emission norm for non-road mobile machinery, particle number measurements and limits are defined, commonly referred to as PN, with units [#/km] or [#/kWh]. In this case, PN expresses a quantity of particles per unit distance (or work). | 0 | Theoretical and Fundamental Chemistry |
A ternary complex is a protein complex containing three different molecules that are bound together. In structural biology, ternary complex can also be used to describe a crystal containing a protein with two small molecules bound, such as a cofactor and a substrate; or a complex formed between two proteins and a single substrate. In Immunology, ternary complex can refer to the MHC–peptide–T-cell-receptor complex formed when T cells recognize epitopes of an antigen.
Another important example is the ternary complex formed during eukaryotic translation, in which ternary complex composed of eIF2 + GTP + Met-tRNA is formed.
A ternary complex can be a complex formed between two substrate molecules and an enzyme. This is seen in multi-substrate enzyme-catalyzed reactions where two substrates and two products can be formed. The ternary complex is an intermediate species in this type of enzyme-catalyzed reaction. An example for a ternary complex is seen in the random-order mechanism or the compulsory-order mechanism of enzyme catalysis for multiple substrates.
The term ternary complex can also refer to a polymer formed by electrostatic interactions. | 1 | Applied and Interdisciplinary Chemistry |
In the early history of thermodynamics, a positive amount of work done by the system on the surroundings leads to energy being lost from the system. This historical sign convention has been used in many physics textbooks and is used in the present article.
According to the first law of thermodynamics for a closed system, any net change in the internal energy U must be fully accounted for, in terms of heat Q entering the system and work W done by the system:
An alternate sign convention is to consider the work performed on the system by its surroundings as positive. This leads to a change in sign of the work, so that . This convention has historically been used in chemistry, and has been adopted by most physics textbooks.
This equation reflects the fact that the heat transferred and the work done are not properties of the state of the system. Given only the initial state and the final state of the system, one can only say what the total change in internal energy was, not how much of the energy went out as heat, and how much as work. This can be summarized by saying that heat and work are not state functions of the system. This is in contrast to classical mechanics, where net work exerted by a particle is a state function. | 0 | Theoretical and Fundamental Chemistry |
Boric acid is used to treat or prevent boron deficiencies in plants. It is also used in preservation of grains such as rice and wheat. | 0 | Theoretical and Fundamental Chemistry |
The traditional way to analyze the ascorbic acid content is the process of titration with an oxidizing agent, and several procedures have been developed.
The popular iodometry approach uses iodine in the presence of a starch indicator. Iodine is reduced by ascorbic acid, and, when all the ascorbic acid has reacted, the iodine is then in excess, forming a blue-black complex with the starch indicator. This indicates the end-point of the titration.
As an alternative, ascorbic acid can be treated with iodine in excess, followed by back titration with sodium thiosulfate using starch as an indicator.
This iodometric method has been revised to exploit reaction of ascorbic acid with iodate and iodide in acid solution. Electrolyzing the solution of potassium iodide produces iodine, which reacts with ascorbic acid. The end of process is determined by potentiometric titration in a manner similar to Karl Fischer titration. The amount of ascorbic acid can be calculated by Faraday's law.
Another alternative uses N-bromosuccinimide (NBS) as the oxidizing agent, in the presence of potassium iodide and starch. The NBS first oxidizes the ascorbic acid; when the latter is exhausted, the NBS liberates the iodine from the potassium iodide, which then forms the blue-black complex with starch. | 1 | Applied and Interdisciplinary Chemistry |
Prior to the discovery of rasagiline, a closely related analog called [https://pubchem.ncbi.nlm.nih.gov/compound/SU-11739 SU-11739] (AGN 1133) was patented. At first, the N-methyl was necessary for the agent to be considered a ring cyclized analog of pargyline with ca. twenty-times the potency. However, the N-methyl compound was a non-selective MAOI.
Racemic rasagiline was discovered and patented by Aspro Nicholas in the 1970s as a drug candidate for treatment of hypertension.
Moussa B. H. Youdim, a biochemist, had been involved in developing selegiline as a drug for Parkinsons, in collaboration with Peter Reiderer. He wanted to find a similar compound that would have fewer side effects, and around 1977, at about the same time he moved from London to Haifa to join the faculty of Technion, he noticed that rasagiline could potentially be such a compound. He called that compound, AGN 1135.
In 1996 Youdim, in collaboration with scientists from Technion and the US National Institutes of Health, and using compounds developed with Teva Pharmaceuticals, published a paper in which the authors wrote that they were inspired by the racemic nature of deprenyl and the greater activity of one of its stereoisomers, L-deprenyl, which became selegiline, to explore the qualities of the isomers of the Aspro compound, and they found that the R-isomer had almost all the activity; this is the compound that became rasagiline. They called the mesylate salt of the R-isomer TVP-1012 and the hydrochloride salt, TVP-101.
Teva and Technion filed patent applications for this racemically pure compound, methods to make it, and methods to use it to treat Parkinsons and other disorders, and Technion eventually assigned its rights to Teva.
Teva began development of rasagiline, and by 1999 was in Phase III trials, and entered into a partnership with Lundbeck in which Lundbeck agreed to share the costs and obtained the joint right to market the drug in Europe. In 2003 Teva partnered with Eisai, giving Eisai the right to jointly market the drug for Parkinson's in the US, and to co-develop and co-market the drug for Alzheimers and other neurological diseases.
It was approved by the European Medicines Agency for Parkinson's in 2005 and in the US in 2006. | 0 | Theoretical and Fundamental Chemistry |
Larive has received a number of awards, including the National Science Foundation CAREER Award in 1995.
She received the American Chemical Society Analytical Division's J. Calvin Giddings Award for Excellence in Education in 2007 and served as chair of the Analytical Division in 2013. In 2015, Larive received the Award for Volunteer Service to the American Chemical Society. In 2018, the Analytical Chemistry Division of the American Chemical Society honored Larive with the Award for Distinguished Service to the Field of Analytical Chemistry.
Larive is a Fellow of the American Association for the Advancement of Science (AAAS) (2008), the International Union of Pure and Applied Chemistry (IUPAC) (2004) and the American Chemical Society (ACS) (2011). | 0 | Theoretical and Fundamental Chemistry |
For flows in pipes, if flow is turbulent then the laminar sublayer caused by the pipe wall is so thin that it is negligible. Plug flow will be achieved if the sublayer thickness is much less than the pipe diameter (<<D).
where is the Darcy friction factor (from the above equation or the Moody Chart), is the sublayer thickness, is the pipe diameter, is the density, is the friction velocity (not an actual velocity of the fluid), is the average velocity of the plug (in the pipe), is the shear on the wall, and is the pressure loss down the length of the pipe. is the relative roughness of the pipe.
In this regime the pressure drop is a result of inertia-dominated turbulent shear stress rather than viscosity-dominated laminar shear stress. | 1 | Applied and Interdisciplinary Chemistry |
In 1964, Gofman raised questions about a lack of data on low-level radiation and also proposed a wide-ranging study of exposure in medicine and the workplace at a symposium for nuclear scientists and engineers. This helped start a national inquiry into the safety of atomic power. With his colleague Dr. Arthur R. Tamplin, Dr. Gofman then looked at health studies of the survivors of Hiroshima and Nagasaki, as well as other epidemiological studies, and conducted research on radiations influences on human chromosomes. The two scientists suggested that federal safety guidelines for low-level exposures be reduced by 90 percent in 1969. The Atomic Energy Commission contested the findings, and "the furor made Dr. Gofman a reluctant figurehead of the anti-nuclear movement" according to The New York Times'. In 1970, he testified in favor of a bill to ban commercial nuclear reactors in New York City and told the City Council that a reactor in an urban environment would be "equal in the opposite direction to all the medical advances put together in the last 25 years." | 0 | Theoretical and Fundamental Chemistry |
Spectrophotometry is an important technique used in many biochemical experiments that involve DNA, RNA, and protein isolation, enzyme kinetics and biochemical analyses. Since samples in these applications are not readily available in large quantities, they are especially suited to be analyzed in this non-destructive technique. In addition, precious sample can be saved by utilizing a micro-volume platform where as little as 1uL of sample is required for complete analyses.
A brief explanation of the procedure of spectrophotometry includes comparing the absorbency of a blank sample that does not contain a colored compound to a sample that contains a colored compound. This coloring can be accomplished by either a dye such as Coomassie Brilliant Blue G-250 dye measured at 595 nm or by an enzymatic reaction as seen between β-galactosidase and ONPG (turns sample yellow) measured at 420 nm. The spectrophotometer is used to measure colored compounds in the visible region of light (between 350 nm and 800 nm), thus it can be used to find more information about the substance being studied.
In biochemical experiments, a chemical and/or physical property is chosen and the procedure that is used is specific to that property to derive more information about the sample, such as the quantity, purity, enzyme activity, etc.
Spectrophotometry can be used for a number of techniques such as determining optimal wavelength absorbance of samples, determining optimal pH for absorbance of samples, determining concentrations of unknown samples, and determining the pKa of various samples. Spectrophotometry is also a helpful process for protein purification and can also be used as a method to create optical assays of a compound. Spectrophotometric data can also be used in conjunction with the Beer–Lambert Equation, , to determine various relationships between transmittance and concentration, and absorbance and concentration. Because a spectrophotometer measures the wavelength of a compound through its color, a dye-binding substance can be added so that it can undergo a color change and be measured. It is possible to know the concentrations of a two-component mixture using the absorption spectra of the standard solutions of each component. To do this, it is necessary to know the extinction coefficient of this mixture at two wavelengths and the extinction coefficients of solutions that contain the known weights of the two components. In addition to the traditional Beer-Lamberts law model, cuvette based label free spectroscopy can be used, which add an optical filter in the pathways of the light, enabling the spectrophotometer to quantify concentration, size and refractive index of samples following the hands law. Spectrophotometers have been developed and improved over decades and have been widely used among chemists. Additionally, Spectrophotometers are specialized to measure either UV or Visible light wavelength absorbance values. It is considered to be a highly accurate instrument that is also very sensitive and therefore extremely precise, especially in determining color change. This method is also convenient for use in laboratory experiments because it is an inexpensive and relatively simple process. | 0 | Theoretical and Fundamental Chemistry |
It is possible to perform a CD4 co-receptor blockade, using antibodies, in order to lower T cell activation and counteract autoimmune disorders. This blockade appears to elicit a "dominant" effect, that is to say, once blocked, the T cells do not regain their ability to become active. This effect then spreads to native T cells which then switch to a CD4+CD25+GITR+FoxP3+ T regulatory phenotype. | 1 | Applied and Interdisciplinary Chemistry |
The hydrolysis of ATP into ADP and inorganic phosphate
:ATP(aq) + (l) = ADP(aq) + HPO(aq) + H(aq)
releases of enthalpy. This may differ under physiological conditions if the reactant and products are not exactly in these ionization states. The values of the free energy released by cleaving either a phosphate (P) or a pyrophosphate (PP) unit from ATP at standard state concentrations of 1 mol/L at pH 7 are:
:ATP + → ADP + P ΔG°' = −30.5 kJ/mol (−7.3 kcal/mol)
:ATP + → AMP + PP ΔG°' = −45.6 kJ/mol (−10.9 kcal/mol)
These abbreviated equations at a pH near 7 can be written more explicitly (R = adenosyl):
:[RO-P(O)-O-P(O)-O-PO] + → [RO-P(O)-O-PO] + [HPO] + H
:[RO-P(O)-O-P(O)-O-PO] + → [RO-PO] + [HOP-O-PO] + H
At cytoplasmic conditions, where the ADP/ATP ratio is 10 orders of magnitude from equilibrium, the ΔG is around −57 kJ/mol.
Along with pH, the free energy change of ATP hydrolysis is also associated with Mg concentration, from ΔG° = −35.7 kJ/mol at a Mg concentration of zero, to ΔG° = −31 kJ/mol at [Mg] = 5 mM. Higher concentrations of Mg decrease free energy released in the reaction due to binding of Mg ions to negatively charged oxygen atoms of ATP at pH 7. | 1 | Applied and Interdisciplinary Chemistry |
CPT can be used to detect specific DNA sequences and by extension specific genotypes. For example, CPT can be used to distinguish GMO produce from non-GMO produce. Clinically, CPT can be used as an alternative to cell culturing in order to detect antibacterial resistance of a pathogen.
CPT, at its core, detects whether a specific sequence is present in a sample. But because cleaved probes accumulate following linear rate kinetics, the amount of target DNA can be quantified. Consequently, CPT has been used to quantify the number of non-coding repeats in organisms.
CPT can be used in conjunction with other technologies, like molecular beacons and qPCR. | 1 | Applied and Interdisciplinary Chemistry |
In fluid dynamics, the Ursell number indicates the nonlinearity of long surface gravity waves on a fluid layer. This dimensionless parameter is named after Fritz Ursell, who discussed its significance in 1953.
The Ursell number is derived from the Stokes wave expansion, a perturbation series for nonlinear periodic waves, in the long-wave limit of shallow water – when the wavelength is much larger than the water depth. Then the Ursell number U is defined as:
which is, apart from a constant 3 / (32 π), the ratio of the amplitudes of the second-order to the first-order term in the free surface elevation.
The used parameters are:
* H : the wave height, i.e. the difference between the elevations of the wave crest and trough,
* h : the mean water depth, and
* λ : the wavelength, which has to be large compared to the depth, λ ≫ h.
So the Ursell parameter U is the relative wave height H / h times the relative wavelength λ / h squared.
For long waves (λ ≫ h) with small Ursell number, U ≪ 32 π / 3 ≈ 100, linear wave theory is applicable. Otherwise (and most often) a non-linear theory for fairly long waves (λ > 7 h) – like the Korteweg–de Vries equation or Boussinesq equations – has to be used.
The parameter, with different normalisation, was already introduced by George Gabriel Stokes in his historical paper on surface gravity waves of 1847. | 1 | Applied and Interdisciplinary Chemistry |
In the human genome, STAT6 protein is encoded by the STAT6 gene, located on the chromosome 12q13.3-q14.1. The gene encompasses over 19 kb and consists of 23 exons. STAT6 shares structural similarity with the other STAT proteins and is composed of the N-terminal domain, DNA binding domain, SH3- like domain, SH2 domain and transactivation domain (TAD).
STAT proteins are activated by the Janus family (JAKs) tyrosine kinases in response to cytokine exposure. STAT6 is activated by cytokines interleukin-4 (IL-4), and interleukin-13 (IL-13) with their receptors that both contain the α subunit of the IL-4 receptor (IL-4Rα). Tyrosine phosporylation of STAT6 after stimulation by IL-4 results in the formation of STAT6 homodimers that bind specific DNA elements via a DNA-binding domain. | 1 | Applied and Interdisciplinary Chemistry |
In the early 1950s, divers found the remains of a shipwreck in Cape Gelidonya, off the coast of Turkey. The remains included a substantial amount of copper oxhide ingot material: 34 in full, five in half, 12 corners, and of random fragments. Twenty-four full copper oxhide ingots have stamps on their centers—usually of a circle containing intersecting lines. These stamps were likely made when the metal was soft. In addition, the ship contained numerous complete and incomplete copper bun-shaped ingots, rectangular tin bars, and Cypriot agricultural tools made of scrap bronze. Radiocarbon dating of brushwood from the ship gives an approximate date of 1200 BC. | 1 | Applied and Interdisciplinary Chemistry |
The most important factor in influencing homoaromatic character is the addition of a single homoconjugate linkage into the parent aromatic compound. The location of the homoconjugate bond is not important as all homoaromatic species can be derived from aromatic compounds that possess symmetry and equal bond order between all carbons. The insertion of a homoconjugate linkage perturbs the π-electron density an amount δβ, which depending on the ring size, must be greater than 0 and less than 1, where 0 represents no perturbation and 1 represents total loss of aromaticity (destabilization equivalent to the open chain form). It is believed that with increasing ring size, the resonance stabilization of homoaromaticity is offset by the strain in forming the homoconjugate bridge. In fact, the maximum ring size for homoaromaticity is fairly low as a 16-membered annulene ring favours the formation of the aromatic dication over the strained bridged homocation. | 0 | Theoretical and Fundamental Chemistry |
When heated, n-BuLi, analogously to other alkyllithium reagents with "β-hydrogens", undergoes β-hydride elimination to produce 1-butene and lithium hydride (LiH):
: CHLi → LiH + CHCHCH=CH | 0 | Theoretical and Fundamental Chemistry |
In synaptic vesicles, some neurochemists have suggested that vesicles occasionally may not completely fuse with presynaptic membranes in neurotransmitter release into the synaptic cleft. The controversy lies in whether or not endocytosis always occurs in vesicle reforming after release of the neurotransmitter. Another proposed mechanism for release of vesicle contents into extracellular fluid is called kiss-and-run fusion.
There is some indication that vesicles may only form a small pore in the presynaptic membrane allowing contents to be released by standard diffusion for a short while before retreating back into the presynaptic cell. This mechanism may be a way around clathrin-mediated endocytosis. It is also proposed that the vesicle does not need to return to an endosome to refill, though it is not thoroughly understood by which mechanism it would refill. This does not exclude full vesicle fusion, but only states that both mechanisms may operate in synaptic clefts.
"Kiss and run" has been shown to occur in endocrine cells, though it has not been directly witnessed in synaptic gaps. | 1 | Applied and Interdisciplinary Chemistry |
is produced by the chloride process, which involves the reduction of titanium oxide ores, typically ilmenite (), with carbon under flowing chlorine at 900 °C. Impurities are removed by distillation.
The coproduction of Iron(III) chloride| is undesirable, which has motivated the development of alternative technologies. Instead of directly using ilmenite, "rutile slag" is used. This material, an impure form of , is derived from ilmenite by removal of iron, either using carbon reduction or extraction with sulfuric acid. Crude contains a variety of other volatile halides, including vanadyl chloride (), silicon tetrachloride (), and tin tetrachloride (), which must be separated. | 0 | Theoretical and Fundamental Chemistry |
The earliest electrical application of SiC was as a surge protection in lightning arresters in electric power systems. These devices must exhibit high resistance until the voltage across them reaches a certain threshold V at which point their resistance must drop to a lower level and maintain this level until the applied voltage drops below V flushing current into the ground.
It was recognized early on that SiC had such a voltage-dependent resistance, and so columns of SiC pellets were connected between high-voltage power lines and the earth. When a lightning strike to the line raises the line voltage sufficiently, the SiC column will conduct, allowing strike current to pass harmlessly to the earth instead of along the power line. The SiC columns proved to conduct significantly at normal power-line operating voltages and thus had to be placed in series with a spark gap. This spark gap is ionized and rendered conductive when lightning raises the voltage of the power line conductor, thus effectively connecting the SiC column between the power conductor and the earth. Spark gaps used in lightning arresters are unreliable, either failing to strike an arc when needed or failing to turn off afterwards, in the latter case due to material failure or contamination by dust or salt. Usage of SiC columns was originally intended to eliminate the need for the spark gap in lightning arresters. Gapped SiC arresters were used for lightning-protection and sold under the GE and Westinghouse brand names, among others. The gapped SiC arrester has been largely displaced by no-gap varistors that use columns of zinc oxide pellets. | 1 | Applied and Interdisciplinary Chemistry |
Duke University did a study where they dosed a loblolly pine plantation with elevated levels of . The studies showed that the pines did indeed grow faster and stronger. They were also less prone to damage during ice storms, which is a factor that limits loblolly growth farther north. The forest did relatively better during dry years. The hypothesis is that the limiting factors in the growth of the pines are nutrients such as nitrogen, which is in deficit on much of the pine land in the Southeast. In dry years, however, the trees do not bump up against those factors since they are growing more slowly because water is the limiting factor. When rain is plentiful trees reach the limits of the site's nutrients and the extra is not beneficial. Most forest soils in Southeastern region are deficient in nitrogen and phosphorus as well as trace minerals. Pine forests often sit on land that was used for cotton, corn or tobacco. Since these crops depleted originally shallow and infertile soils, tree farmers must work to improve soils. | 1 | Applied and Interdisciplinary Chemistry |
At standard ambient temperature and pressure, trifluoroperacetic acid is a colourless liquid with a boiling point of 162 °C. It is soluble in acetonitrile, dichloromethane, diethyl ether, and sulfolane, and readily reacts with water. Like all peroxy acids, it is potentially explosive and requires careful handling. It is not commercially available, but can be made in the lab and stored for up to several weeks at −20 °C. Some preparative methods result in mixtures containing residual hydrogen peroxide and trifluoroacetic acid, and heating such a mixture is extremely hazardous; the hydrogen peroxide can be decomposed using manganese dioxide for safety before heating. | 0 | Theoretical and Fundamental Chemistry |
In stem cell biology, a heterologous transplant refers to cells from a mixed population of donor cells. This is in contrast to an autologous transplant where the cells are derived from the same individual or an allogenic transplant where the donor cells are HLA matched to the recipient. A heterologous source of therapeutic cells will have a much greater availability than either autologous or allogenic cellular therapies. | 1 | Applied and Interdisciplinary Chemistry |
The Reynolds Analogy is popularly known to relate turbulent momentum and heat transfer. That is because in a turbulent flow (in a pipe or in a boundary layer) the transport of momentum and the transport of heat largely depends on the same turbulent eddies: the velocity and the temperature profiles have the same shape.
The is that heat flux q/A in a turbulent system is analogous to momentum flux τ, which suggests that the ratio τ/(q/A) must be constant for all radial positions.
The complete Reynolds analogy* is:
Experimental data for gas streams agree approximately with above equation if the Schmidt and Prandtl numbers are near 1.0 and only skin friction is present in flow past a flat plate or inside a pipe. When liquids are present and/or form drag is present, the analogy is conventionally known to be invalid.
In 2008, the qualitative form of validity of Reynolds analogy was re-visited for laminar flow of incompressible fluid with variable dynamic viscosity (μ). It was shown that the inverse dependence of Reynolds number (Re) and skin friction coefficient(c) is the basis for validity of the Reynolds’ analogy, in laminar convective flows with constant & variable μ. For μ = const. it reduces to the popular form of Stanton number (St) increasing with increasing Re, whereas for variable μ it reduces to St increasing with decreasing Re. Consequently, the Chilton-Colburn analogy of St•Pr increasing with increasing c' is qualitatively valid whenever the
Reynolds’ analogy is valid. Further, the validity of the Reynolds’ analogy is linked to the applicability of Prigogines Theorem of Minimum Entropy Production. Thus, Reynolds analogy is valid for flows that are close to developed, for whom, changes in the gradients of field variables (velocity & temperature) along the flow are small. | 1 | Applied and Interdisciplinary Chemistry |
The term kagome lattice was coined by Japanese physicist Kôdi Husimi, and first appeared in a 1951 paper by his assistant Ichirō Shōji.
The kagome lattice in this sense consists of the vertices and edges of the trihexagonal tiling.
Despite the name, these crossing points do not form a mathematical lattice.
A related three dimensional structure formed by the vertices and edges of the quarter cubic honeycomb, filling space by regular tetrahedra and truncated tetrahedra, has been called a hyper-kagome lattice. It is represented by the vertices and edges of the quarter cubic honeycomb, filling space by regular tetrahedra and truncated tetrahedra. It contains four sets of parallel planes of points and lines, each plane being a two dimensional kagome lattice. A second expression in three dimensions has parallel layers of two dimensional lattices and is called an orthorhombic-kagome lattice. The trihexagonal prismatic honeycomb represents its edges and vertices.
Some minerals, namely jarosites and herbertsmithite, contain two-dimensional layers or three-dimensional kagome lattice arrangement of atoms in their crystal structure. These minerals display novel physical properties connected with geometrically frustrated magnetism. For instance, the spin arrangement of the magnetic ions in CoVO rests in a kagome lattice which exhibits fascinating magnetic behavior at low temperatures. Quantum magnets realized on Kagome metals have been discovered to exhibit many unexpected electronic and magnetic phenomena. It is also proposed that SYK behavior can be observed in two dimensional kagome lattice with impurities.
The term is much in use nowadays in the scientific literature, especially by theorists studying the magnetic properties of a theoretical kagome lattice.
See also: Kagome crests. | 0 | Theoretical and Fundamental Chemistry |
A pH indicator is a halochromic chemical compound added in small amounts to a solution so the pH (acidity or basicity) of the solution can be determined visually or spectroscopically by changes in absorption and/or emission properties. Hence, a pH indicator is a chemical detector for hydronium ions (HO) or hydrogen ions (H) in the Arrhenius model.
Normally, the indicator causes the color of the solution to change depending on the pH. Indicators can also show change in other physical properties; for example, olfactory indicators show change in their odor. The pH value of a neutral solution is 7.0 at 25°C (standard laboratory conditions). Solutions with a pH value below 7.0 are considered acidic and solutions with pH value above 7.0 are basic. Since most naturally occurring organic compounds are weak electrolytes, such as carboxylic acids and amines, pH indicators find many applications in biology and analytical chemistry. Moreover, pH indicators form one of the three main types of indicator compounds used in chemical analysis. For the quantitative analysis of metal cations, the use of complexometric indicators is preferred, whereas the third compound class, the redox indicators, are used in redox titrations (titrations involving one or more redox reactions as the basis of chemical analysis). | 0 | Theoretical and Fundamental Chemistry |
Hammond's postulate can be used to examine the structure of the transition states of a SN1 reaction. In particular, the dissociation of the leaving group is the first transition state in a S1 reaction. The stabilities of the carbocations formed by this dissociation are known to follow the trend tertiary > secondary > primary > methyl.
Therefore, since the tertiary carbocation is relatively stable and therefore close in energy to the R-X reactant, then the tertiary transition state will have a structure that is fairly similar to the R-X reactant. In terms of the graph of reaction coordinate versus energy, this is shown by the fact that the tertiary transition state is further to the left than the other transition states. In contrast, the energy of a methyl carbocation is very high, and therefore the structure of the transition state is more similar to the intermediate carbocation than to the R-X reactant. Accordingly, the methyl transition state is very far to the right. | 0 | Theoretical and Fundamental Chemistry |
Autologous grafts are used to transfer tissue from one site to another on the same body. The use of autologous grafts prevents transplantation rejection reactions.
Grafts used for oral reconstruction are preferably taken from the oral cavity itself (such as gingival and palatal grafts). However, their limited availability and small size leads to the use of either skin transplants or intestinal mucosa to be able to cover bigger defects.
Other than tissue shortage, donor site morbidity is a common problem that may occur when using autologous grafts. When tissue is obtained from somewhere other than the oral cavity (such as the intestine or skin) there is a risk of the graft not being able to lose its original donor tissue characteristics. For example, skin grafts are often taken from the radial forearm or lateral upper arm when covering more extensive defects. A positive aspect of using skin grafts is the large availability of skin. However, skin grafts differ from oral mucosa in: consistency, color and keratinization pattern. The transplanted skin graft often continues to grow hair in the oral cavity. | 1 | Applied and Interdisciplinary Chemistry |
The Krupp–Renn process was a direct reduction steelmaking process used from the 1930s to the 1970s. It used a rotary furnace and was one of the few technically and commercially successful direct reduction processes in the world, acting as an alternative to blast furnaces due to their coke consumption. The Krupp-Renn process consumed mainly hard coal and had the unique characteristic of partially melting the charge. This method is beneficial for processing low-quality or non-melting ores, as their waste material forms a protective layer that can be easily separated from the iron. It generates Luppen, nodules of pre-reduced iron ore, which can be easily melted down.
The first industrial furnaces emerged in the 1930s, firstly in Nazi Germany and then in the Japanese Empire. During the 1950s, new facilities were constructed, notably in Czechoslovakia and West Germany. The process was discontinued in the early 1970s, with a few nuances.
It was unproductive, intricate to master, and only pertinent to certain ores. In the beginning of the 21st century, Japan modernized the process to manufacture ferronickel, which is the sole surviving variant. | 1 | Applied and Interdisciplinary Chemistry |
Negative hyperconjugation is a theorized phenomenon in organosilicon compounds, in which hyperconjugation stabilizes or destabilizes certain accumulations of positive charge. The phenomenon explains corresponding peculiarities in the stereochemistry and rate of hydrolysis.
Second-row elements generally stabilize adjacent carbanions more effectively than their first-row congeners; conversely they destabilize adjacent carbocations, and these effects reverse one atom over. For phosphorus and later elements, these phenomena are easily ascribed to the element's greater electronegativity than carbon. However, Si has lower electronegativity than carbon, polarizing the electron density onto carbon.
The continued presence of second-row type stability in certain organosilicon compounds is known as the silicon α and β effects, after the corresponding locants. These stabilities occur because of a partial overlap between the C–Si σ orbital and the σ* antibonding orbital at the β position, lowering the S reaction transition state's energy. This hyperconjugation requires an antiperiplanar relationship between the Si group and the leaving group to maximize orbital overlap.
Moreover, there is also another kind of silicon α effect, which is mainly about the hydrolysis on the silicon atom. | 0 | Theoretical and Fundamental Chemistry |
After being scattered by the sample, the profile of the diffracted beam needs to be detected by a two-dimensionally resolving X-ray detector. The classical "detector" is X-ray sensitive film, with nuclear plates as a traditional alternative. The first step beyond these "offline" detectors were the so-called image plates, although limited in readout speed and spatial resolution. Since about the mid-1990s, CCD cameras have emerged as a practical alternative, offering many advantages such as fast online readout and the possibility to record entire image series in place. X-ray sensitive CCD cameras, especially those with spatial resolution in the micrometer range, are now well established as electronic detectors for topography. A promising further option for the future may be pixel detectors, although their limited spatial resolution may restrict their usefulness for topography.
General criteria for judging the practical usefulness of detectors for topography applications include spatial resolution, sensitivity, dynamic range ("color depth", in black-white mode), readout speed, weight (important for mounting on diffractometer arms), and price. | 0 | Theoretical and Fundamental Chemistry |
As an innovation value chain processes and management specialist, Anim-Mensah was featured on the VOA NightLife Africa Radio on the subject of "How Effectively Harnessing of African Ideas is The Bedrock of African Industrialization". He was featured on "Africa Must Industrialize Now: The Urgency for Value Addition to Africa Products" Webinar by AfCFTA Policy Network which featured Thomas Mensah (engineer) of Ghana, and Alvin Alexander, System Engineer and Founder at Orion Applied Science & Technology OrionAST. The Doctor cofounded two NGOs all in Ghana with some like-minded colleagues, as a way of giving back to especially support the youths as part of his public educational activities to support them to take their ideas to make positive globe impacts. Among others, he serves on several boards and holds membership in organizations including serving as an External Advisory Board Member at the University of Cincinnati's Chemical and Environmental Engineering Program; and is on the board member of SAYeTECH Co. LLC, a small agriculture equipment business in Ghana | 1 | Applied and Interdisciplinary Chemistry |
The basic structure of [https://web.archive.org/web/20110720035915/http://metpetdb.rpi.edu/ MetPetDB] is based on a geologic sample and derivative subsamples. Geochemical data are linked to subsamples and the minerals within them, while image data can relate to samples or subsamples. MetPetDB is designed to store the distinct spatial/textural context of mineral analysis that is a crucial to petrologic interpretation. A web-based user interface allows a user to become members and download their search results. Approved members may become contributors and upload data to catalogue and share with the public. More information about the data model and the design of the database is available on the MetPetDB Support Wiki. | 0 | Theoretical and Fundamental Chemistry |
The Cariaco Basin in Venezuela has been used to study the cycle of organic material in euxinic marine environments. An increase in productivity coincident with post glacial nutrient loading probably caused a transition from oxic to anoxic and subsequently euxinic conditions around 14.5 thousand years ago. High productivity at the surface produces a rain of particulate organic matter to the sub surface where anoxic, sulfidic conditions persist. The organic matter in this region is oxidized with sulfate, producing reduced sulfur (HS) as a waste product. Free sulfur exists deep in the water column and up to 6m in depth in the sediment. | 0 | Theoretical and Fundamental Chemistry |
Hubel was elected as an ASME Fellow in 2008, and a Fellow of the American Institute for Medical and Biological Engineering in 2012. She was named a Cryofellow of the Society for Cryobiology in 2021. | 1 | Applied and Interdisciplinary Chemistry |
The adsorption/bio-oxidation process was applied at the Krefeld plant (800 000 P.E.) in 1985 for the first time. The plant was expanded and modified and currently treats municipal and industrial wastewater of 1 200 000 P.E.
Currently adsorption/bio-oxidation process is applied at the municipal treatment plants in Germany, the Netherlands (WWTP Dokhaven (Rotterdam), WWTP Utrecht, WWTP Garmerwolde (Groningen) etc.), Austria (WWTP Salzburg, WWTP Strass etc.), Spain, US, China etc.
Adsorption/bio-oxidation process is a part of innovative wastewater treatment concept WaterSchoon, realized in the Netherlands. 250 apartments in the new district Noorderhoek (Sneek, the Netherlands) are equipped with separate collection systems for toilet wastewater and the rest of the household wastewater (or so-called greywater). Both streams are treated separately in order to maximize recovery of resources from wastewater. Adsorption/bio-oxidation process is used for grey water treatment to increase sludge production. Sludge, produced in both stages of the process, is digested together with toilet wastewater in the UASB reactor to maximize energy recovery. | 1 | Applied and Interdisciplinary Chemistry |
Wastewater treatment is a process which removes and eliminates contaminants from wastewater and converts this into an effluent that can be returned to the water cycle. Once returned to the water cycle, the effluent creates an acceptable impact on the environment or is reused for various purposes (called water reclamation). The treatment process takes place in a wastewater treatment plant. There are several kinds of wastewater which are treated at the appropriate type of wastewater treatment plant. For domestic wastewater (also called municipal wastewater or sewage), the treatment plant is called a Sewage Treatment. For industrial wastewater, treatment either takes place in a separate Industrial wastewater treatment, or in a sewage treatment plant (usually after some form of pre-treatment). Further types of wastewater treatment plants include Agricultural wastewater treatment and leachate treatment plants.
Processes commonly used in wastewater treatment include phase separation (such as sedimentation), biological and chemical processes (such as oxidation) or polishing. The main by-product from wastewater treatment plants is a type of sludge that is usually treated in the same or another wastewater treatment plant. Biogas can be another by-product if anaerobic treatment processes are used. Treated wastewater can be reused as reclaimed water. The main purpose of wastewater treatment is for the treated wastewater to be able to be disposed or reused safely. However, before it is treated, the options for disposal or reuse must be considered so the correct treatment process is used on the wastewater. Bangladesh has officially inaugurated the largest single sewage treatment plant (STP) in South Asia, located in the Khilgaon area of the city. With a capacity to treat five million sewage per day, the STP marks a significant step towards addressing the country's wastewater management challenges.
The term "wastewater treatment" is often used to mean "sewage treatment". | 1 | Applied and Interdisciplinary Chemistry |
Cleaning surfaces in environments without water has been a challenge. Electric curtain devices were designed to remove particles by creating electric fields on the surface and carrying away particles due to their charged nature. It has been used in solar panels as well as 3D printers. | 0 | Theoretical and Fundamental Chemistry |
Lipotoxicity is a metabolic syndrome that results from the accumulation of lipid intermediates in non-adipose tissue, leading to cellular dysfunction and death. The tissues normally affected include the kidneys, liver, heart and skeletal muscle. Lipotoxicity is believed to have a role in heart failure, obesity, and diabetes, and is estimated to affect approximately 25% of the adult American population. | 1 | Applied and Interdisciplinary Chemistry |
In biology, depolarization or hypopolarization is a change within a cell, during which the cell undergoes a shift in electric charge distribution, resulting in less negative charge inside the cell compared to the outside. Depolarization is essential to the function of many cells, communication between cells, and the overall physiology of an organism.
Most cells in higher organisms maintain an internal environment that is negatively charged relative to the cells exterior. This difference in charge is called the cells membrane potential. In the process of depolarization, the negative internal charge of the cell temporarily becomes more positive (less negative). This shift from a negative to a more positive membrane potential occurs during several processes, including an action potential. During an action potential, the depolarization is so large that the potential difference across the cell membrane briefly reverses polarity, with the inside of the cell becoming positively charged.
The change in charge typically occurs due to an influx of sodium ions into a cell, although it can be mediated by an influx of any kind of cation or efflux of any kind of anion. The opposite of a depolarization is called a hyperpolarization.
Usage of the term "depolarization" in biology differs from its use in physics, where it refers to situations in which any form of polarity (i.e. the presence of any electrical charge, whether positive or negative) changes to a value of zero.
Depolarization is sometimes referred to as "hypopolarization" (as opposed to hyperpolarization). | 0 | Theoretical and Fundamental Chemistry |
Hammond married Marian Reese in 1945, and had five children with her. The couple divorced in 1975, and he was remarried soon after to Eve Menger. He had two children with Eve. | 0 | Theoretical and Fundamental Chemistry |
The invention and widespread application of hydraulic mining, namely hushing and ground-sluicing, aided by the ability of the Romans to plan and execute mining operations on a large scale, allowed various base and precious metals to be extracted on a proto-industrial scale only rarely matched until the Industrial Revolution.
The most common fuel by far for smelting and forging operations, as well as heating purposes, was wood and particularly charcoal, which is nearly twice as efficient. In addition, coal was mined in some regions to a fairly large extent: almost all major coalfields in Roman Britain were exploited by the late 2nd century AD, and a lively trade along the English North Sea coast developed, which extended to the continental Rhineland, where bituminous coal was already used for the smelting of iron ore. The annual iron production at Populonia alone accounted for an estimated 2,000 to 10,000 tons. | 1 | Applied and Interdisciplinary Chemistry |
The most common synthesis method of gold(III) bromide is heating gold and excess liquid bromine at 140 °C:
Alternatively, the halide-exchange reaction of gold(III) chloride with hydrobromic acid has also been proven successful in synthesizing gold(III) bromide:
This reaction is driven by the production of the relatively more stable hydrochloric acid compared with hydrobromic acid. | 0 | Theoretical and Fundamental Chemistry |
PFOA and PFOS have been shown to significantly alter immune and inflammatory responses in human and animal species. In particular, IgA, IgE (in females only) and C-reactive protein have been shown to decrease whereas antinuclear antibodies increase as PFOA serum concentrations increase. These cytokine variations allude to immune response aberrations resulting in autoimmunity. One proposed mechanism is a shift towards anti-inflammatory M2 macrophages and/or (TH2) response in intestinal epithelial tissue which allows sulfate-reducing bacteria to flourish. Elevated levels of hydrogen sulfide result, which reduce beta-oxidation and nutrient production, leading to a breakdown of the colonic epithelial barrier. | 0 | Theoretical and Fundamental Chemistry |
Moody's team used the available data (including that of Nikuradse) to show that fluid flow in rough pipes could be described by four dimensionless quantities: Reynolds number, pressure loss coefficient, diameter ratio of the pipe and the relative roughness of the pipe. They then produced a single plot which showed that all of these collapsed onto a series of lines, now known as the Moody chart. This dimensionless chart is used to work out pressure drop, (Pa) (or head loss, (m)) and flow rate through pipes. Head loss can be calculated using the Darcy–Weisbach equation in which the Darcy friction factor appears :
Pressure drop can then be evaluated as:
or directly from
where is the density of the fluid, is the average velocity in the pipe, is the friction factor from the Moody chart, is the length of the pipe and is the pipe diameter.
The chart plots Darcy–Weisbach friction factor against Reynolds number Re for a variety of relative roughnesses, the ratio of the mean height of roughness of the pipe to the pipe diameter or .
The Moody chart can be divided into two regimes of flow: laminar and turbulent. For the laminar flow regime (was determined analytically by Poiseuille:
For the turbulent flow regime, the relationship between the friction factor the Reynolds number Re, and the relative roughness is more complex. One model for this relationship is the Colebrook equation (which is an implicit equation in ): | 1 | Applied and Interdisciplinary Chemistry |
Non-equilibrium thermodynamics is a branch of thermodynamics that deals with systems that are not in thermodynamic equilibrium. Most systems found in nature are not in thermodynamic equilibrium because they are not in stationary states, and are continuously and discontinuously subject to flux of matter and energy to and from other systems. The thermodynamic study of non-equilibrium systems requires more general concepts than are dealt with by equilibrium thermodynamics. Many natural systems still today remain beyond the scope of currently known macroscopic thermodynamic methods. | 0 | Theoretical and Fundamental Chemistry |
The term "paucimannose" (occasionally spelled as "pauci-mannose") was coined in the early 1990s glycobiology literature Paucimannose utilises the prefix "pauci" meaning few or small in Latin and the suffix "mannose" indicating glycans involving mannose-terminating glycans.
The phrases protein paucimannosylation and paucimannosidic proteins are commonly used in the literature to describe paucimannose-modified glycoproteins displaying intact structural and functional integrity. In contrast, the oligosaccharides themselves are often referred to as paucimannosidic, low mannose, and truncated glycans or other less conventional nomenclature.
A simple shorthand nomenclature has been proposed as a convenient way to name the individual paucimannosidic glycan structures, e.g. M3F denotes ManGlcNAcFuc. | 1 | Applied and Interdisciplinary Chemistry |
Cerevisterol was first discovered in 1928 as a component of crude yeast (Saccharomyces cerevisiae) sterols remaining from the manufacture of the related ergosterol. Chemists Edna M. Honeywell and Charles E. Bills purified the compound and reported some of its properties in a 1932 publication. They noted its high melting point (265.3 °C) relative to other sterols, and insolubility in the organic solvent hexane. These characteristics facilitated its purification, and they were able to obtain of cerevisterol from of dry yeast. The following year, they determined its chemical formula to be CHO, with two double bonds, and with two of the oxygen molecules occurring in hydroxyl groups.
Its structure was determined in 1954 by comparison with a sample that was chemically synthesized from ergosterol. Purified cerevisterol has the form of a white amorphous solid. When crystallized in ethyl alcohol, it forms elongated prisms, while crystallization in acetone or ethyl acetate produces broad hexagonal prisms. Its UV absorption spectrum shows a maximum at about 248 nm. Cerevisterol is a stable molecule, showing no discoloration or change in melting point even after several weeks of exposure to light and air. | 1 | Applied and Interdisciplinary Chemistry |
There are notable similarities in the commonly used approximate differential equations for momentum, heat, and mass transfer. The molecular transfer equations of Newtons law for fluid momentum at low Reynolds number (Stokes flow), Fouriers law for heat, and Fick's law for mass are very similar, since they are all linear approximations to transport of conserved quantities in a flow field.
At higher Reynolds number, the analogy between mass and heat transfer and momentum transfer becomes less useful due to the nonlinearity of the Navier-Stokes equation (or more fundamentally, the general momentum conservation equation), but the analogy between heat and mass transfer remains good. A great deal of effort has been devoted to developing analogies among these three transport processes so as to allow prediction of one from any of the others. | 1 | Applied and Interdisciplinary Chemistry |
Peramivir is developed by structure-based drug design. After the influenza NA inhibitor activity of α/β-6-acetyl-amino-3,6-dideoxy -D-glycero-altro-2-nonulofuranosonic acid was reported by Yamamoto et al., the cyclopentane derivatives was designed with a guanidino group replacing C4-hydroxyl position of DANA in the active site, similar to Zanamivir. Babu et al. found that the addition of n-butyl side chain makes the compound fit better to the hydrophobic region of the enzyme. However, the conformation of the n-butyl group was found to be different when bound to influenza virus A from its conformation when bound to influenza virus B.
Since the compound processed similar binding interaction with active site of NA to zanamivir and due to the mutation in some zanamivir-resistance strains, the position of guanidino group was altered and the n-butyl group was replaced in order to change its active site interaction. | 1 | Applied and Interdisciplinary Chemistry |
*Mathematics (Calculus, differential equations, statistics)
*Physics
*Chemistry
*Engineering Mechanics (Statics, Dynamics, Solids Mechanics)
*Fluid Mechanics
*Thermodynamics | 1 | Applied and Interdisciplinary Chemistry |
Viral transformation can impose characteristically determinable features upon a cell. Typical phenotypic changes include high saturation density, anchorage-independent growth, loss of contact inhibition, loss of orientated growth, immortalization, disruption of the cell's cytoskeleton. | 1 | Applied and Interdisciplinary Chemistry |
A modern steel plant employs very few people per tonne, compared to the past. In South Korea, Posco employs 29,648 people to produce 28 million tonnes.
During the period 1974 to 1999, the steel industry had drastically reduced employment all around the world. In the US, it was down from 521,000 to 153,000. In Japan, from 459,000 to 208,000; Germany from 232,000 to 78,000; UK from 197,000 to 31,000; Brazil from 118,000 to 59,000; South Africa from 100,000 to 54,000. South Korea already had a low figure. It was only 58,000 in 1999. The steel industry had reduced its employment around the world by more than 1,500,000 in 25 years. | 1 | Applied and Interdisciplinary Chemistry |
Dimitra Markovitsi's areas of research interest include photophysics and photochemistry in the condensed phase, time-resolved optical spectroscopy (absorption, fluorescence), excited states, energy, and charge transfer, charge separation, ionization, radical formation, photodamage, UV-induced primary processes in DNA (excited states, intrinsic fluorescence, electron ejection, oxidative damage) and G-quadruplexes.
Markovitsi studied the dimensionality of excitation transport in columnar phases. She discussed the effect of orientational disorder on the electronic excited states and introduced a model based on the exciton theory and quantum chemistry computations.
She published the first studies investigating the effect of structural disorder on the excited states of double helices and guanine quadruplexes. Simultaneously, she explored the behavior of the intrinsic DNA fluorescence from femtoseconds to nanoseconds. She provided evidence of the occurrence of excitation transport between nucleobases and the collective nature of Franck-Condon states. She reported the first spectroscopic investigation on DNA excited states in the UVA region; despite their very poor absorption, such excited states may contribute to the deterioration of the genetic code by solar light, whose UVA intensity is greater than that of UVB and UVC.
She identified an unanticipated phenomenon: low-energy UV radiation can ionize DNA multimers (but not their monomeric components), generating electron holes in the nucleobases. The latter radical species are precursors of oxidative damage and provide promise for nanodevices based on photoconductivity. She demonstrated that the photoionization of guanine quadruplexes can be adjusted by varying their structural parameters.
Markovitsi also investigated DNA reaction dynamics on nanosecond to millisecond timescales. This work focuses on the dimerization of nucleobases and the deprotonation and tautomerization of the guanine radical. Her research revealed the anisotropic character of such events, which are highly dependent on the local DNA environment, rendering the conventional models of chemical kinetics inadequate for describing them.
Markovitsi’s work has been published in collective books, including the “Handbook of Organic Photochemistry and Photobiology. | 0 | Theoretical and Fundamental Chemistry |
Xylomannan is an antifreeze molecule, found in the freeze-tolerant Alaskan beetle Upis ceramboides. Unlike antifreeze proteins, xylomannan is not a protein. Instead, it is a combination of a sugar (saccharide) and a fatty acid that is found in cell membranes. As such is expected to work in a different manner than AFPs. It is believed to work by incorporating itself directly into the cell membrane and preventing the freezing of water molecules within the cell.
Xylomannan is also found in the red seaweed Nothogenia fastigiata (Scinaiaceae family). Fraction F6 of a sulphated xylomannan from Nothogenia fastigiata was found to inhibit replication of a variety of viruses, including Herpes simplex virus types 1 and 2 (HSV-1, HSV-2), Human cytomegalovirus (HCMV, HHV-5), Respiratory syncytial virus (RSV), Influenzavirus A, Influenzavirus B, Junin and Tacaribe virus, Simian immunodeficiency virus, and (weakly) Human immunodeficiency virus types 1 and 2. | 1 | Applied and Interdisciplinary Chemistry |
As one of ASCEs flagship journals which began publication in 1956, this journals origin goes back to the publication of the first volume of Transactions of the American Society of Civil Engineers in 1892. Established originally as Journal of the Sanitary Engineering Division and renamed Journal of the Environmental Engineering Division in 1973, it acquired its current name in 1983. | 1 | Applied and Interdisciplinary Chemistry |
In the Mayr–Patz equation (1994):
The second order reaction rate constant k at 20 °C for a reaction is related to a nucleophilicity parameter N, an electrophilicity parameter E, and a nucleophile-dependent slope parameter s. The constant s is defined as 1 with 2-methyl-1-pentene as the nucleophile.
Many of the constants have been derived from reaction of so-called benzhydrylium ions as the electrophiles:
and a diverse collection of π-nucleophiles:
Typical E values are +6.2 for R = chlorine, +5.90 for R = hydrogen, 0 for R = methoxy and −7.02 for R = dimethylamine.
Typical N values with s in parentheses are −4.47 (1.32) for electrophilic aromatic substitution to toluene (1), −0.41 (1.12) for electrophilic addition to 1-phenyl-2-propene (2), and 0.96 (1) for addition to 2-methyl-1-pentene (3), −0.13 (1.21) for reaction with triphenylallylsilane (4), 3.61 (1.11) for reaction with 2-methylfuran (5), +7.48 (0.89) for reaction with isobutenyltributylstannane (6) and +13.36 (0.81) for reaction with the enamine 7.
The range of organic reactions also include SN2 reactions:
With E = −9.15 for the S-methyldibenzothiophenium ion, typical nucleophile values N (s) are 15.63 (0.64) for piperidine, 10.49 (0.68) for methoxide, and 5.20 (0.89) for water. In short, nucleophilicities towards sp or sp centers follow the same pattern. | 0 | Theoretical and Fundamental Chemistry |
Luminol's use in a crime scene investigation is somewhat hampered by the fact that it reacts to iron- and copper-containing compounds, bleaches, horseradish, fecal matter, or cigarette smoke residue. Application of luminol to a piece of evidence may prevent other tests from being performed on it; however DNA has been successfully extracted from samples exposed to luminol. | 0 | Theoretical and Fundamental Chemistry |
A pipe wrench is any of several types of wrench that are designed to turn threaded pipe and pipe fittings for assembly (tightening) or disassembly (loosening). The Stillson wrench, or Stillson-pattern wrench, is the usual form of pipe wrench, especially in the US. The Stillson name is that of the original patent holder, who licensed the design to a number of manufacturers; the patent has since expired decades ago. A different type of wrench with compound leverage often used on pipes, the plumber wrench, is also called a "pipe wrench" in some places. | 1 | Applied and Interdisciplinary Chemistry |
Monomers capable of forming single, double, triple or quadruple hydrogen bonding has been utilized for making supramolecular polymers, and increased association of monomers obviously possible when monomers have maximum number of hydrogen bonding donor/acceptor motifs. For instance, ureidopyrimidinone-based monomer with self-complementary quadruple hydrogen bonding termini polymerized in solution, accordingly with the theory of conventional polymers and displayed a distinct viscoelastic nature at ambient temperatures. | 0 | Theoretical and Fundamental Chemistry |
The Rayleigh number, shown below, is a dimensionless number that characterizes convection problems in heat transfer. A critical value exists for the Rayleigh number, above which fluid motion occurs.
The ratio of the Grashof number to the square of the Reynolds number may be used to determine if forced or free convection may be neglected for a system, or if there's a combination of the two. This characteristic ratio is known as the Richardson number (). If the ratio is much less than one, then free convection may be ignored. If the ratio is much greater than one, forced convection may be ignored. Otherwise, the regime is combined forced and free convection. | 1 | Applied and Interdisciplinary Chemistry |
Both sexual and asexual reproductions are implemented. Asexual reproduction is implemented as producing the offsprings genome (the gene network) by directly copying the parents genome. Sexual reproduction is implemented as the recombination of the two parents' genomes. | 1 | Applied and Interdisciplinary Chemistry |
Ketones and aldehydes with electron-withdrawing substituents react more readily with diazoalkanes than those bearing electron-donating substituents (Table 2). In addition to accelerating the reaction, electron-withdrawing substituents typically increase the amount of epoxide produced (Table 2).
The effects of substituents on the diazoalkanes is reversed relative to the carbonyl reactants: electron-withdrawing substituents decrease the rate of reaction while electron-donating substituents accelerate it. For example, diazomethane is significantly more reactive than ethyl diazoacetate, though less reactive than its higher alkyl homologs (e.g. diazoethane). Reaction conditions may also affect the yields of carbonyl product and epoxide product. In the reactions of o-nitrobenzaldehyde, p-nitrobenzaldehyde, and phenylacetaldehyde with diazomethane, the ratio of epoxide to carbonyl is increased by the inclusion of methanol in the reaction mixture. The opposite influence has also been observed in the reaction of piperonal with diazomethane, which exhibits increased carbonyl yield in the presence of methanol. | 0 | Theoretical and Fundamental Chemistry |
NMR Cryoporometry (NMRC) is a recent technique for measuring total porosity and pore size distributions. It makes use of the Gibbs-Thomson effect : small crystals of a liquid in the pores melt at a lower temperature than the bulk liquid : The melting point depression is inversely proportional to the pore size. The technique is closely related to that of the use of gas adsorption to measure pore sizes (Kelvin equation). Both techniques are particular cases of the Gibbs Equations (Josiah Willard Gibbs): the Kelvin Equation is the constant temperature case, and the Gibbs-Thomson Equation is the constant pressure case.
To make a Cryoporometry measurement, a liquid is imbibed into the porous sample, the sample cooled until all the liquid is frozen, and then warmed slowly while measuring the quantity of the liquid that has melted. Thus it is similar to DSC thermoporosimetry, but has higher resolution, as the signal detection does not rely on transient heat flows, and the measurement can be made arbitrarily slowly. It is suitable for measuring pore diameters in the range 2 nm–2 μm.
Nuclear Magnetic Resonance (NMR) may be used as a convenient method of measuring the quantity of liquid that has melted, as a function of temperature, making use of the fact that the relaxation time in a frozen material is usually much shorter than that in a mobile liquid. The technique was developed at the University of Kent in the UK.
It is also possible to adapt the basic NMRC experiment to provide structural resolution in spatially dependent pore size distributions, or to provide behavioural information about the confined liquid. | 0 | Theoretical and Fundamental Chemistry |
Because of the large size of the α-pinenyl substituents, diisopinocampheylborane only hydroborates unhindered alkenes. These reactions proceed with high enantioselectivity. 2-Butene, 2-pentene, 3-hexene are converted to the respective chiral alcohols in high ees. Norbornene under the same conditions gave an 83% ee. Heterocycles (dihydrofuran, dihydrothiophene, dihydropyrrole, tetrahydropyran) give the alcohols in ≥99% ee; the high ees reflect their constrained conformations.
It adds to alkynes to form the corresponding vinyldiisopinocampheylboranes
In a highly stereoselective reaction, allyldiisopinocampheylboranes converts aldehydes to the homologated alcohols, rapidly even at -100 °C. The alkyldiisopinocampheylboranes, which result from the addition to alkenes, usefully react with a range of different reagents. Hydroxylamine-O-sulfonic acid provides 3-pinanamine.
Also useful is the reaction of diisopinocampheylborane with an aldehyde (RCHO) to give the chiral boronic ester, (isopinocampheyl)BOCH(R), which can be further used is a number of reactions e.g. Suzuki reaction. | 0 | Theoretical and Fundamental Chemistry |
A warming climate increases surface temperatures of waters which affects multiple aspects of euxinic water formation. As waters warm, the solubility of oxygen decreases, allowing for deep anoxic waters to form more readily. Additionally, the warmer water causes increased respiration of organic matter leading to further oxygen depletion. Higher temperatures enhance the hydrologic cycle, increasing evaporation from bodies of water, resulting in increased precipitation. This causes higher rates of weathering of rocks and therefore higher nutrient concentrations in river outflows. The nutrients allow for more productivity resulting in more marine snow and subsequently lower oxygen in deep waters due to increased respiration.
Volcanism has also been proposed as a factor in creating euxinic conditions. The carbon dioxide (CO) released during volcanic outgassing causes global warming which has cascading effects on the formation of euxinic conditions. | 0 | Theoretical and Fundamental Chemistry |
Contrary to the usual fundamental soliton that can maintain its profile unchanged during propagation, the Peregrine soliton presents a double spatio-temporal localization. Therefore, starting from a weak oscillation on a continuous background, the Peregrine soliton develops undergoing a progressive increase of its amplitude and a narrowing of its temporal duration. At the point of maximum compression, the amplitude is three times the level of the continuous background (and if one considers the intensity as it is relevant in optics, there is a factor 9 between the peak intensity and the surrounding background). After this point of maximal compression, the wave's amplitude decreases and its width increases.
These features of the Peregrine soliton are fully consistent with the quantitative criteria usually used in order to qualify a wave as a rogue wave. Therefore, the Peregrine soliton is an attractive hypothesis to explain the formation of those waves which have a high amplitude and may appear from nowhere and disappear without a trace. | 1 | Applied and Interdisciplinary Chemistry |
The basic room purge equation can be used only for purge scenarios. In a scenario where a liquid continuously evaporates from a container in a ventilated room, a differential equation has to be used:
where the ventilation rate has been adjusted by a mixing factor K:
*C = concentration of a gas
*G = generation rate
*V = room volume
*Q′ = adjusted ventilation rate of the volume | 0 | Theoretical and Fundamental Chemistry |
After the insertion of Okazaki fragments, the RNA primers are removed (the mechanism of removal differs between prokaryotes and eukaryotes) and replaced with new deoxyribonucleotides that fill the gaps where the RNA primer was present. DNA ligase then joins the fragmented strands together, completing the synthesis of the lagging strand.
In prokaryotes, DNA polymerase I synthesizes the Okazaki fragment until it reaches the previous RNA primer. Then the enzyme simultaneously acts as a 5′→3′ exonuclease, removing primer ribonucleotides in front and adding deoxyribonucleotides behind. Both the activities of polymerization and excision of the RNA primer occur in the 5′→3′ direction, and polymerase I can do these activities simultaneously; this is known as “Nick Translation”. Nick translation refers to the synchronized activity of polymerase I in removing the RNA primer and adding deoxyribonucleotides. Later, a gap between the strands is formed called a nick, which is sealed using a DNA ligase.
In eukaryotes the removal of RNA primers in the lagging strand is essential for the completion of replication. Thus, as the lagging strand being synthesized by DNA polymerase δ in 5′→3′ direction, Okazaki fragments are formed, which are discontinuous strands of DNA. Then, when the DNA polymerase reaches to the 5’ end of the RNA primer from the previous Okazaki fragment, it displaces the 5′ end of the primer into a single-stranded RNA flap which is removed by nuclease cleavage. Cleavage of the RNA flaps involves three methods of primer removal. The first possibility of primer removal is by creating a short flap that is directly removed by flap structure-specific endonuclease 1 (FEN-1), which cleaves the 5’ overhanging flap. This method is known as the short flap pathway of RNA primer removal. The second way to cleave a RNA primer is by degrading the RNA strand using a RNase, in eukaryotes it’s known as the RNase H2. This enzyme degrades most of the annealed RNA primer, except the nucleotides close to the 5’ end of the primer. Thus, the remaining nucleotides are displayed into a flap that is cleaved off using FEN-1. The last possible method of removing RNA primer is known as the long flap pathway. In this pathway several enzymes are recruited to elongate the RNA primer and then cleave it off. The flaps are elongated by a 5’ to 3’ helicase, known as Pif1. After the addition of nucleotides to the flap by Pif1, the long flap is stabilized by the replication protein A (RPA). The RPA-bound DNA inhibits the activity or recruitment of FEN1, as a result another nuclease must be recruited to cleave the flap. This second nuclease is DNA2 nuclease , which has a helicase-nuclease activity, that cleaves the long flap of RNA primer, which then leaves behind a couple of nucleotides that are cleaved by FEN1. At the end, when all the RNA primers have been removed, nicks form between the Okazaki fragments that are filled-in with deoxyribonucleotides using an enzyme known as ligase1, through a process called ligation. | 1 | Applied and Interdisciplinary Chemistry |
Diazo compounds are used as precursors to carbenes, which are generated by thermolysis or photolysis, for example in the Wolff rearrangement. As such they are used in cyclopropanation for example in the reaction of ethyl diazoacetate with styrene. Certain diazo compounds can couple to form alkenes in a formal carbene dimerization reaction.
Diazo compounds are intermediates in the Bamford-Stevens reaction of tosylhydrazones to alkenes, again with a carbene intermediate:
In the Doyle-Kirmse reaction certain diazo compounds react with allyl sulfides to the homoallyl sulfide. Intramolecular reactions of diazocarbonyl compounds provide access to cyclopropanes. In the Buchner ring expansion diazo compounds react with aromatic rings with ring-expansion. | 0 | Theoretical and Fundamental Chemistry |
Trimethoprim-Halotag (TMP-HTag) is a small molecule chemical linker developed for the rapid and reversible control of protein localization in living cells (Ballister). TMP is an dihydrofolate reductase (DHFR) inhibitor chosen for its specificity in binding to the bacterial form of DHFR. The other half of the linker is a Halotag, a self labelling bacterial globular protein ligand that can bind covalently and irreversibly to the chloroalkane group of a Haloenzyme. Positioned between the TMP group and HaloTag is a flexible linker that can be modified to optimize protein linking efficiency. The modular structure of TMP-HaloTag makes it an ideal heterobifunctional tool for use in chemically induced dimerization (CID). Additionally, TMP- HTag can be modified to include photo-cleavable groups that allow for the control of CID using light. | 0 | Theoretical and Fundamental Chemistry |
NANOG is highly expressed in cancer stem cells and may thus function as an oncogene to promote carcinogenesis. High expression of NANOG correlates with poor survival in cancer patients.
Recent research has shown that the localization of NANOG and other transcription factors have potential consequences on cellular function. Experimental evidence has shown that the level of NANOG p8 expression is elevated specially in cancer cells, which mean that NANOG p8 gene is a critical member in (CSCs) Cancer stem cells, so knocking it down could reduce the cancer malignancy. | 1 | Applied and Interdisciplinary Chemistry |
2D correlation analysis originated from 2D NMR spectroscopy. Isao Noda developed perturbation based 2D spectroscopy in the 1980s. This technique required sinusoidal perturbations to the chemical system under investigation. This specific type of the applied perturbation severely limited its possible applications. Following research done by several groups of scientists, perturbation based 2D spectroscopy could be developed to a more extended and generalized broader base. Since the development of generalized 2D correlation analysis in 1993 based on Fourier transformation of the data, 2D correlation analysis gained widespread use. Alternative techniques that were simpler to calculate, for example the disrelation spectrum, were also developed simultaneously. Because of its computational efficiency and simplicity, the Hilbert transform is nowadays used for the calculation of the 2D spectra. To date, 2D correlation analysis is used for the interpretation of many types of spectroscopic data (including XRF, UV/VIS spectroscopy, fluorescence, infrared, and Raman spectra), although its application is not limited to spectroscopy. | 0 | Theoretical and Fundamental Chemistry |
When bacterial cells run out of nutrients, they enter stationary phase and downregulate protein synthesis. Several processes mediate this transition. For instance, in E. coli, 70S ribosomes form 90S dimers upon binding with a small 6.5 kDa protein, ribosome modulation factor RMF. These intermediate ribosome dimers can subsequently bind a hibernation promotion factor (the 10.8 kDa protein, HPF) molecule to form a mature 100S ribosomal particle, in which the dimerization interface is made by the two 30S subunits of the two participating ribosomes. The ribosome dimers represent a hibernation state and are translationally inactive. A third protein that can bind to ribosomes when E. coli cells enter the stationary phase is YfiA (previously known as RaiA). HPF and YfiA are structurally similar, and both proteins can bind to the catalytic A- and P-sites of the ribosome. RMF blocks ribosome binding to mRNA by preventing interaction of the messenger with 16S rRNA. When bound to the ribosomes the C-terminal tail of E. coli YfiA interferes with the binding of RMF, thus preventing dimerization and resulting in the formation of translationally inactive monomeric 70S ribosomes.
In addition to ribosome dimerization, the joining of the two ribosomal subunits can be blocked by RsfS (formerly called RsfA or YbeB). RsfS binds to L14, a protein of the large ribosomal subunit, and thereby blocks joining of the small subunit to form a functional 70S ribosome, slowing down or blocking translation entirely. RsfS proteins are found in almost all eubacteria (but not archaea) and homologs are present in mitochondria and chloroplasts (where they are called C7orf30 and iojap, respectively). However, it is not known yet how the expression or activity of RsfS is regulated.
Another ribosome-dissociation factor in Escherichia coli is HflX, previously a GTPase of unknown function. Zhang et al. (2015) showed that HflX is a heat shock–induced ribosome-splitting factor capable of dissociating vacant as well as mRNA-associated ribosomes. The N-terminal effector domain of HflX binds to the peptidyl transferase center in a strikingly similar manner as that of the class I release factors and induces dramatic conformational changes in central intersubunit bridges, thus promoting subunit dissociation. Accordingly, loss of HflX results in an increase in stalled ribosomes upon heat shock and possibly other stress conditions. | 1 | Applied and Interdisciplinary Chemistry |
* International Symposium on the Origin of Life on the Earth (held at Moscow, 19–24 August 1957)
* Proceedings of the SPIE held at San Jose, California, 22–24 January 2001
* Proceedings of the SPIE held at San Diego, California, 31 July–2 August 2005 | 0 | Theoretical and Fundamental Chemistry |
Virilization or masculinization is the biological development of adult male characteristics in young males or females. Most of the changes of virilization are produced by androgens.
Virilization is a medical term commonly used in three medical and biology of sex contexts: prenatal biological sexual differentiation, the postnatal changes of typical chromosomal male (46, XY) puberty, and excessive androgen effects in typical chromosomal females (46, XX). It is also the intended result of androgen replacement therapy in males with delayed puberty and low testosterone. | 1 | Applied and Interdisciplinary Chemistry |
Between two phases in equilibrium there is a narrow region where the properties are not that of either phase. Although this region may be very thin, it can have significant and easily observable effects, such as causing a liquid to exhibit surface tension. In mixtures, some components may preferentially move toward the interface. In terms of modeling, describing, or understanding the behavior of a particular system, it may be efficacious to treat the interfacial region as a separate phase. | 0 | Theoretical and Fundamental Chemistry |
Histamine N-methyltransferase is encoded by a single gene, called HNMT, which has been mapped to chromosome 2 in humans.
Three transcript variants have been identified for this gene in humans, which produce different protein isoforms due to alternative splicing, which allows a single gene to code for multiple proteins by including or excluding particular exons of a gene in the final mRNA produced from that gene. Of those isoforms, only one has histamine-methylating activity.
In the human genome, six exons from the 50-kb HNMT contribute to forming a unique mRNA species, approximately 1.6 kb in size. This mRNA is then translated into the cytosolic enzyme histamine N-methyltransferase, comprising 292 amino acids, of which 130 amino acids are a conserved sequence. HNMT does not have promoter cis-elements, such as TATA and CAAT boxes. | 1 | Applied and Interdisciplinary Chemistry |
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