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* 1990 – French Anderson et al. performed the first approved gene therapy on a human patient
* 1990 – Napoli, Lemieux and Jorgensen discovered RNA interference (1990) during experiments aimed at the color of petunias.
* 1990 – Wolfgang Krätschmer, Lowell Lamb, Konstantinos Fostiropoulos, and Donald Huffman discovered that Buckminsterfullerene can be separated from soot because it is soluble in benzene.
* 1995 – Publication of the first complete genome of a free-living organism.
* 1995 - Symbion pandora, the first known species from the phylum Cycliophora is described by Reinhardt Kristensen and Peter Funch.
* 1996 – Dolly the sheep was first clone of an adult mammal.
* 1998 – Mello and Fire publish their work on RNAi in c.elegans, for which they shared the 2006 Nobel Prize in Physiology or Medicine.
* 1999 – Researchers at the Institute for Human Gene Therapy at the University of Pennsylvania accidentally kill Jesse Gelsinger during a clinical trial of a gene therapy technique, leading the FDA to halt further gene therapy trials at the institute.
* 2000 - Reinhardt Kristensen and Peter Funch describe Limnognathia maerski, the first known species from the phylum Micrognathozoa.
* 2001 - First insects from the suborder Mantophasmatodea are discovered.
* 2001 – Publication of the first drafts of the complete human genome (see Craig Venter).
* 2002 – First virus produced from scratch, an artificial polio virus that paralyzes and kills mice.
* 2007 – Commercialization of Illumina Next generation Sequencing tools. This has become the most popular high-throughput sequencing system.
* 2012 – Use of CRISPR-Cas9 as a DNA-editing biotechnology tool. | 1 | Applied and Interdisciplinary Chemistry |
*Tetramethyl­phosphonium fluoride (CH)PF forms stable acetonitrile solutions. It is prepared from the ylide and potassium bifluoride:
:(CH)P=CH + KHF → (CH)PF + KF
:Gaseous tetramethylphosphonium fluoride exists as the phosphorane but autoionizes in acetonitrile solution. A more elaborate phosphazenium salt ([(CH)N)P]NF) is also known.
*Anhydrous Tetrabutylammonium fluoride has been prepared by the reaction of hexafluorobenzene and tetrabutylammonium cyanide. | 0 | Theoretical and Fundamental Chemistry |
Advantages:
* Process controllability - Unlike a traditional electric or gas furnace the induction system requires no pre-heat cycle or controlled shutdown. The heat is available on demand. In addition to the benefits of rapid availability in the event of a downstream interruption to production, the power can be switched off thus saving energy.
* Energy efficiency - Due to the heat being generated within the component energy transfer is extremely efficient. The induction heater heats only the part not the atmosphere around it.
* Process consistency - The induction heating process produces extremely uniform consistent heat this often allows less heat to be used for a given process.
* No naked flame - This allows induction heating to be used in a wide variety of applications in volatile environments in particular in petrochemical applications.
The main disadvantage of this process is that, in general, it is limited to components which have a cylindrical shape. | 1 | Applied and Interdisciplinary Chemistry |
Lens epithelial derived growth factor (LEDGF/p75) is a host protein that binds to integrase and is crucial for viral replication. The mechanism of action is not precisely known but evidence suggest that LEDGF/p75 guides integrase to insert viral DNA into transcriptionally active sites of the host genome. Inhibitors of this protein are already being developed and patented. They are likely to be highly target specific and less prone to the development of resistance. | 1 | Applied and Interdisciplinary Chemistry |
Leukocyte-promoting factor, more commonly known as leukopoietin, is a category of substances produced by neutrophils when they encounter a foreign antigen. Leukopoietin stimulates the bone marrow to increase the rate of leukopoiesis in order to replace the neutrophils that will inevitably be lost when they begin to phagocytose the foreign antigens.
Leukocyte-promoting factors include colony stimulating factors (CSFs) (produced by monocytes and T lymphocytes), interleukins (produced by monocytes, macrophages, and endothelial cells), prostaglandins, and lactoferrin. | 1 | Applied and Interdisciplinary Chemistry |
Symbiotic and kleptoplastic organisms excluded:
*The glaucophytes and the red and green algae—clade Archaeplastida (uni- and multicellular)
*The cryptophytes—clade Cryptista (unicellular)
*The haptophytes—clade Haptista (unicellular)
*The dinoflagellates and chromerids in the superphylum Myzozoa, and Pseudoblepharisma in the phylum Ciliophora—clade Alveolata (unicellular)
*The ochrophytes—clade Stramenopila (uni- and multicellular)
*The chlorarachniophytes and three species of Paulinella in the phylum Cercozoa—clade Rhizaria (unicellular)
*The euglenids—clade Excavata (unicellular)
Except for the euglenids, which are found within the Excavata, all of these belong to the Diaphoretickes. Archaeplastida and the photosynthetic Paulinella got their plastids, which are surrounded by two membranes, through primary endosymbiosis in two separate events, by engulfing a cyanobacterium. The plastids in all the other groups have either a red or green algal origin, and are referred to as the "red lineages" and the "green lineages". The only known exception is the ciliate Pseudoblepharisma tenue, which in addition to its plastids that originated from green algae also has a purple sulfur bacterium as symbiont. In dinoflagellates and euglenids the plastids are surrounded by three membranes, and in the remaining lines by four. A nucleomorph, remnants of the original algal nucleus located between the inner and outer membranes of the plastid, is present in the cryptophytes (from a red alga) and chlorarachniophytes (from a green alga).
Some dinoflagellates that lost their photosynthetic ability later regained it again through new endosymbiotic events with different algae.
While able to perform photosynthesis, many of these eukaryotic groups are mixotrophs and practice heterotrophy to various degrees. | 0 | Theoretical and Fundamental Chemistry |
Fatty acid synthase (FAS) is an enzyme that in humans is encoded by the FASN gene.
Fatty acid synthase is a multi-enzyme protein that catalyzes fatty acid synthesis. It is not a single enzyme but a whole enzymatic system composed of two identical 272 kDa multifunctional polypeptides, in which substrates are handed from one functional domain to the next.
Its main function is to catalyze the synthesis of palmitate (C16:0, a long-chain saturated fatty acid) from acetyl-CoA and malonyl-CoA, in the presence of NADPH.
The fatty acids are synthesized by a series of decarboxylative Claisen condensation reactions from acetyl-CoA and malonyl-CoA. Following each round of elongation the beta keto group is reduced to the fully saturated carbon chain by the sequential action of a ketoreductase (KR), dehydratase (DH), and enoyl reductase (ER). The growing fatty acid chain is carried between these active sites while attached covalently to the phosphopantetheine prosthetic group of an acyl carrier protein (ACP), and is released by the action of a thioesterase (TE) upon reaching a carbon chain length of 16 (palmitic acid). | 1 | Applied and Interdisciplinary Chemistry |
*Children
*Pregnancy
*Lactation
*Situations where a patient has a history of hypersensitivity
*Kidney failure | 0 | Theoretical and Fundamental Chemistry |
A future way to reduce waste accumulation is to phase out current reactors in favor of Generation IV reactors, which output less waste per power generated. Fast reactors such as BN-800 in Russia are also able to consume MOX fuel that is manufactured from recycled spent fuel from traditional reactors.
The UK's Nuclear Decommissioning Authority published a position paper in 2014 on the progress on approaches to the management of separated plutonium, which summarises the conclusions of the work that NDA shared with UK government. | 0 | Theoretical and Fundamental Chemistry |
In this process molten metal is poured in the mold and allowed to solidify while the mold is rotating. Metal is poured into the center of the mold at its axis of rotation. Due to inertial force, the liquid metal is thrown out toward the periphery.
Centrifugal casting is both gravity and pressure independent since it creates its own force feed using a temporary sand mold held in a spinning chamber. Lead time varies with the application. Semi- and true-centrifugal processing permit 30–50 pieces/hr-mold to be produced, with a practical limit for batch processing of approximately 9000 kg total mass with a typical per-item limit of 2.3–4.5 kg.
Industrially, the centrifugal casting of railway wheels was an early application of the method developed by the German industrial company Krupp and this capability enabled the rapid growth of the enterprise.
Small art pieces such as jewelry are often cast by this method using the lost wax process, as the forces enable the rather viscous liquid metals to flow through very small passages and into fine details such as leaves and petals. This effect is similar to the benefits from vacuum casting, also applied to jewelry casting. | 1 | Applied and Interdisciplinary Chemistry |
The processes involved in glass disease can reduce the transparency of the glass or even threaten the integrity of the structure. Glass disease causes a complex disintegration of the glass which can be identified through a variety of symptoms, including weeping, crizzling, spalling, cracking and fragmentation. | 0 | Theoretical and Fundamental Chemistry |
In statistical mechanics, the entropy of an isolated system at thermodynamic equilibrium is defined as the natural logarithm of , the number of distinct microscopic states available to the system given the macroscopic constraints (such as a fixed total energy ):
This equation, which relates the microscopic details, or microstates, of the system (via ) to its macroscopic state (via the entropy ), is the central idea of statistical mechanics. Such is its importance that it is inscribed on Boltzmann's tombstone.
The constant of proportionality serves to make the statistical mechanical entropy equal to the classical thermodynamic entropy of Clausius:
One could choose instead a rescaled dimensionless entropy in microscopic terms such that
This is a more natural form and this rescaled entropy exactly corresponds to Shannon's subsequent information entropy.
The characteristic energy is thus the energy required to increase the rescaled entropy by one nat. | 0 | Theoretical and Fundamental Chemistry |
Oxygen-18 (, Ω) is a natural, stable isotope of oxygen and one of the environmental isotopes.
is an important precursor for the production of fluorodeoxyglucose (FDG) used in positron emission tomography (PET). Generally, in the radiopharmaceutical industry, enriched water () is bombarded with hydrogen ions in either a cyclotron or linear accelerator, producing fluorine-18. This is then synthesized into FDG and injected into a patient. It can also be used to make an extremely heavy version of water when combined with tritium (hydrogen-3): or . This compound has a density almost 30% greater than that of natural water.
The accurate measurements of rely on proper procedures of analysis, sample preparation and storage. | 0 | Theoretical and Fundamental Chemistry |
There are three modes of formation of twinned crystals.
* Growth twins are the result of an interruption or change in the lattice during formation or growth due to a possible deformation from a larger substituting ion. Parallel growth describes a form of crystal growth that produces the appearance of a cluster of aligned crystals. Close examination reveals that the cluster is actually a single crystal. This is not twinning, since the crystal lattice is continuous throughout the cluster. Parallel growth likely takes place because it reduces system energy.
* Annealing or transformation twins are the result of a change in crystal system during cooling as one form becomes unstable and the crystal structure must re-organize or transform into another more stable form.
* Deformation or gliding twins are the result of stress on the crystal after the crystal has formed. Because growth twins are formed during the initial growth of the crystal, they are described as primary, whereas transformation or deformation twins are formed in an existing crystal and are described as secondary. | 0 | Theoretical and Fundamental Chemistry |
The vast majority of cyclic compounds are organic, and of these, a significant and conceptually important portion are composed of rings made only of carbon atoms (i.e., they are carbocycles). | 0 | Theoretical and Fundamental Chemistry |
In fluid dynamics, flow separation or boundary layer separation is the detachment of a boundary layer from a surface into a wake.
A boundary layer exists whenever there is relative movement between a fluid and a solid surface with viscous forces present in the layer of fluid close to the surface. The flow can be externally, around a body, or internally, in an enclosed passage. Boundary layers can be either laminar or turbulent. A reasonable assessment of whether the boundary layer will be laminar or turbulent can be made by calculating the Reynolds number of the local flow conditions.
Separation occurs in flow that is slowing down, with pressure increasing, after passing the thickest part of a streamline body or passing through a widening passage, for example.
Flowing against an increasing pressure is known as flowing in an adverse pressure gradient. The boundary layer separates when it has travelled far enough in an adverse pressure gradient that the speed of the boundary layer relative to the surface has stopped and reversed direction. The flow becomes detached from the surface, and instead takes the forms of eddies and vortices. The fluid exerts a constant pressure on the surface once it has separated instead of a continually increasing pressure if still attached. In aerodynamics, flow separation results in reduced lift and increased pressure drag, caused by the pressure differential between the front and rear surfaces of the object. It causes buffeting of aircraft structures and control surfaces. In internal passages separation causes stalling and vibrations in machinery blading and increased losses (lower efficiency) in inlets and compressors. Much effort and research has gone into the design of aerodynamic and hydrodynamic surface contours and added features which delay flow separation and keep the flow attached for as long as possible. Examples include the fur on a tennis ball, dimples on a golf ball, turbulators on a glider, which induce an early transition to turbulent flow; vortex generators on aircraft. | 1 | Applied and Interdisciplinary Chemistry |
Big gastrin (G-34) is a form of gastrin with 34 amino acids in its sequence. Big gastrin is a hormone produced by G cells and can be found inside of the stomach. G-34 promotes the secretion of gastric acid in dogs. In dogs, the half life of this peptide is between 14.7 and 16.8 minutes. In humans, an over production of this hormone by gastrinomas leads to Zollinger-Ellison Syndrome.
Big Gastrin Responses to Foods:
Big gastrin (G34) is one form of gastrin predominate in circulation after a meal, another major form is called little gastrin (G17). Both forms of gastrin have been isolated from human gastrinoma and hog antral mucosa. G34 is carboxy-amidated and can be sulphated or unsulphated at the tyrosine residues. Binding of gastrin to the receptors in stomach can cause the secretion of hydrochloric acids (HCl), the gastric acid. Duodenal ulcer patients tend to have higher than normal basal and maximal rate of gastric acid secretion, while gastric ulcer patients have lower than normal basal and maximal of gastric acid output. Comparing G34 in normal and peptic ulcer subjects by using radioimmunoassay in fasting serum and after feeding, basal G34 was found similar in normal and duodenal ulcer but raised in gastric ulcer before meal. After a meal, the concentration of G34 was increased in both duodenal ulcer patients and gastric ulcer patients, which significantly higher than normal people. | 1 | Applied and Interdisciplinary Chemistry |
Founded as the Association of Clinical Biochemists, the association has evolved as biochemistry has changed with advances in laboratory medicine. Recognizing an increasing number of medical members, the name was changed in 2005 to Association for Clinical Biochemistry. In 2007 the "Association of Clinical Scientists in Immunology" merged with the ACB. The membership expanded in 2010 with the merger with the "Association of Clinical Microbiologists". The broader nature of the membership contributed to the renaming of the ACB to its current name at the annual meeting in 2013. | 1 | Applied and Interdisciplinary Chemistry |
Hydrogenated MDI (HMDI or 4,4′-diisocyanato dicyclohexylmethane) is an organic compound in the class known as isocyanates. More specifically, it is an aliphatic diisocyanate. It is a water white liquid at room temperature and is manufactured in relatively small quantities. It is also known as 4,4'-methylenedi(cyclohexyl isocyanate) or methylene bis(4-cyclohexylisocyanate) and has the formula CH[(CH)NCO]. | 0 | Theoretical and Fundamental Chemistry |
In pre-modern medicine, the confection of hyacinth had nearly the same virtues with that of alkermes; but, beside that, was frequently used as an astringent. It consisted of nearly triple the number of drugs; of which the precious stone, called hyacinth, was the base. The other chief ingredients were red coral, bole armoniac, terra sigillata, myrrh, the santals, burnt hartshorn, camphor, sapphire, emerald, topaz, uranium, and most of the ingredients of the confection of alkermes. | 1 | Applied and Interdisciplinary Chemistry |
Not all compounds with alternating double and single bonds are aromatic. Cyclooctatetraene, for example, possesses alternating single and double bonds. The molecule typically adopts a "tub" conformation. Because the p orbitals of the molecule do not align themselves well in this non-planar molecule, the π bonds are essentially isolated and not conjugated. The lack of conjugation allows the 8 π electron molecule to avoid antiaromaticity, a destabilizing effect associated with cyclic, conjugated systems containing 4n π (n = 0, 1, 2, ...) electrons. This effect is due to the placement of two electrons into two degenerate nonbonding (or nearly nonbonding) orbitals of the molecule, which, in addition to drastically reducing the thermodynamic stabilization of delocalization, would either force the molecule to take on triplet diradical character, or cause it to undergo Jahn-Teller distortion to relieve the degeneracy. This has the effect of greatly increasing the kinetic reactivity of the molecule. Because of the lack of long-range interactions, cyclooctatetraene takes on a nonplanar conformation and is nonaromatic in character, behaving as a typical alkene. In contrast, derivatives of the cyclooctatetraene dication and dianion have been found to be planar experimentally, in accord with the prediction that they are stabilized aromatic systems with 6 and 10 π electrons, respectively. Because antiaromaticity is a property that molecules try to avoid whenever possible, only a few experimentally observed species are believed to be antiaromatic. Cyclobutadiene and cyclopentadienyl cation are commonly cited as examples of antiaromatic systems. | 0 | Theoretical and Fundamental Chemistry |
If particles of a second phase which are insoluble in the matrix phase are added to the powder in the form of a much finer powder, then this will decrease grain boundary movement. When the grain boundary tries to move past the inclusion diffusion of atoms from one grain to the other, it will be hindered by the insoluble particle. This is because it is beneficial for particles to reside in the grain boundaries and they exert a force in opposite direction compared to grain boundary migration. This effect is called the Zener effect after the man who estimated this drag force to
where r is the radius of the particle and λ the interfacial energy of the boundary if there are N particles per unit volume their volume fraction f is
assuming they are randomly distributed. A boundary of unit area will intersect all particles within a volume of 2r which is 2Nr particles. So the number of particles n intersecting a unit area of grain boundary is:
Now, assuming that the grains only grow due to the influence of curvature, the driving force of growth is where (for homogeneous grain structure) R approximates to the mean diameter of the grains. With this the critical diameter that has to be reached before the grains ceases to grow:
This can be reduced to
so the critical diameter of the grains is dependent on the size and volume fraction of the particles at the grain boundaries.
It has also been shown that small bubbles or cavities can act as inclusion
More complicated interactions which slow grain boundary motion include interactions of the surface energies of the two grains and the inclusion and are discussed in detail by C.S. Smith. | 1 | Applied and Interdisciplinary Chemistry |
The following are examples of topics in food physical chemistry that are of interest to both the food industry and food science:
* Water in foods
** Local structure in liquid water
** Micro-crystallization in ice cream emulsions
* Dispersion and surface-adsorption processes in foods
* Water and protein activities
* Food hydration and shelf-life
* Hydrophobic interactions in foods
* Hydrogen bonding and ionic interactions in foods
* Disulfide bond breaking and formation in foods
* Food dispersions
* Structure-functionality in foods
* Food micro- and nano- structure
* Food gels and gelling mechanisms
* Cross-linking in foods
* Starch gelatinization and retrogradation
* Physico-chemical modification of carbohydrates
* Physico-chemical interactions in food formulations
* Freezing effects on foods and freeze concentration of liquids
* Glass transition in wheat gluten and wheat doughs
* Drying of foods and crops
* Rheology of wheat doughs, cheese and meat
* Rheology of extrusion processes
* Food enzyme kinetics
* Immobilized enzymes and cells
* Microencapsulation
* Carbohydrates structure and interactions with water and proteins
* Maillard browning reactions
* Lipids structures and interactions with water and food proteins
* Food proteins structure, hydration and functionality in foods
* Food protein denaturation
* Food enzymes and reaction mechanisms
* Vitamin interactions and preservation during food processing
* Interaction of salts and minerals with food proteins and water
* Color determinations and food grade coloring
* Flavors and sensorial perception of foods
* Properties of food additives | 0 | Theoretical and Fundamental Chemistry |
Schwartz's reagent reduces amides to aldehydes.
Vinylation of ketones in high yields is a possible use of Schwartz's reagent.
Schwartz's reagent has been used in the synthesis of some macrolide antibiotics, (−)-motuporin, and antitumor agents. | 0 | Theoretical and Fundamental Chemistry |
Isaac Lewis Pulvermacher was a physicist and inventor originally concerned with the electric telegraph. He first published details of his chain in August 1850 in German and in the winter of that same year came to Britain to demonstrate the machine to notable physicians. He visited London and Edinburgh on this trip. He gives his residence as Breslau, Kingdom of Prussia in his 1853 US patent. Prior to this, however, he had arrived in Britain from Vienna and all the British sources of the time describe him as "of Vienna". | 0 | Theoretical and Fundamental Chemistry |
Metabolic intermediates are molecules that are the precursors or metabolites of biologically significant molecules.
Although these intermediates are of relatively minor direct importance to cellular function, they can play important roles in the allosteric regulation of enzymes. | 1 | Applied and Interdisciplinary Chemistry |
Alternatives to the above closed-channel continuous-flow systems include novel open structures, where discrete, independently controllable droplets
are manipulated on a substrate using electrowetting. Following the analogy of digital microelectronics, this approach is referred to as digital microfluidics. Le Pesant et al. pioneered the use of electrocapillary forces to move droplets on a digital track. The "fluid transistor" pioneered by Cytonix also played a role. The technology was subsequently commercialised by Duke University. By using discrete unit-volume droplets, a microfluidic function can be reduced to a set of repeated basic operations, i.e., moving one unit of fluid over one unit of distance. This "digitisation" method facilitates the use of a hierarchical and cell-based approach for microfluidic biochip design. Therefore, digital microfluidics offers a flexible and scalable system architecture as well as high fault-tolerance capability. Moreover, because each droplet can be controlled independently, these systems also have dynamic reconfigurability, whereby groups of unit cells in a microfluidic array can be reconfigured to change their functionality during the concurrent execution of a set of bioassays. Although droplets are manipulated in confined microfluidic channels, since the control on droplets is not independent, it should not be confused as "digital microfluidics". One common actuation method for digital microfluidics is electrowetting-on-dielectric (EWOD). Many lab-on-a-chip applications have been demonstrated within the digital microfluidics paradigm using electrowetting. However, recently other techniques for droplet manipulation have also been demonstrated using magnetic force, surface acoustic waves, optoelectrowetting, mechanical actuation, etc. | 1 | Applied and Interdisciplinary Chemistry |
In the field of biology, the biotechnology revolution in the 1980s grew from the development of reagents that could be used to identify and manipulate the chemical matter in and on cells. These reagents included antibodies (polyclonal and monoclonal), oligomers, all sorts of model organisms and immortalised cell lines, reagents and methods for molecular cloning and DNA replication, and many others. | 0 | Theoretical and Fundamental Chemistry |
R-407C is a mixture of hydrofluorocarbons used as a refrigerant. It is a zeotropic blend of difluoromethane (R-32), pentafluoroethane (R-125), and 1,1,1,2-tetrafluoroethane (R-134a). Difluoromethane serves to provide the heat capacity, pentafluoroethane decreases flammability, tetrafluoroethane reduces pressure. R-407C cylinders are colored burnt orange.
This refrigerant is intended as a replacement for R-22. R-22 production will be phased out by 2020 as per the Montreal Protocol. | 1 | Applied and Interdisciplinary Chemistry |
Mini-Reviews in Medicinal Chemistry employs peer review, however, several scientists have raised concerns about whether it is a predatory journal after being invited to review articles or serve as an editor in areas where they have no scientific expertise. | 1 | Applied and Interdisciplinary Chemistry |
The non-linear mobility of DNA in gel can be further controlled by embedding in the SCODA gel DNA oligonucleotides complementary to DNA fragments in the sample. This then results in highly specific non-linear velocities for the sample DNA that matches the gel-embedded DNA. This artificial specific non-linearity is then used to selectively concentrate only sequences of interest while rejecting all other DNA sequences in the sample. Over 1,000,000-fold enrichment of single nucleotide variants over wild-type have been demonstrated.
An application of this technique is the detection of rare tumour-derived DNA (ctDNA) from blood samples. | 1 | Applied and Interdisciplinary Chemistry |
* 2020 - ACS Earle B Barnes Award in Chemical Management
* 2020 - Wake Forest Distinguished Alumni Award
* 2018 - ACS Fellow
* 2018 - William S. Johnson Symposium, Stanford University
* 2017 - Elected Chair of ACS Medicinal Chemistry Division
* 2015 - "Most Influential Woman of 2015" - San Francisco Business Times
* 1995 - American Cancer Society Postdoctoral Fellowship
* 1993 - H.W. Dodds Top Thesis Award, Princeton University | 1 | Applied and Interdisciplinary Chemistry |
In the final days of the 1800s, J. J. Thomson established that electrons carry a negative charge opposite but the same size as that of a hydrogen ion while having a mass over one thousand times less. Many such electrons were known to be associated with every atom. | 1 | Applied and Interdisciplinary Chemistry |
Although PDE5 inhibitors main use has been for erectile dysfunction there has been a great interest in PDE5 inhibitors as a promising new therapeutic agents for treatment of other diseases, such as Alzheimer's disease. Elevation of cGMP levels through inhibition of PDE5 provides a way of improving memory and learning.
PDE5 has also been considered as a potential therapeutic agent for parasitic disease such as African sleeping sickness. Strategic changes were made to the structure of sildenafil so the molecule could project into a parasite-specific pocket (the p-pocket). Similar approach has been used to design therapeutic agents Plasmodium falciparum. | 1 | Applied and Interdisciplinary Chemistry |
SOFIA has been used to rapidly detect the abnormal form of the prion protein (PrP) in samples of bodily fluids, such as blood or urine. PrP is the marker protein used in diagnostics for transmissible spongiform encephalopathies (TSEs), examples of which include bovine spongiform encephalopathy in cattle (i.e. “mad cow” disease), scrapie in sheep, and Creutzfeldt–Jakob disease in humans. Currently, no rapid means exists for the ante mortem detection of PrP in the dilute quantities in which it usually appears in bodily fluids. SOFIA has the advantages of requiring little sample preparation, and allowing for electronic diagnostic equipment to be placed outside the containment area. | 1 | Applied and Interdisciplinary Chemistry |
Dimethyldioxirane (DMDO) is the organic compound with the formula . It is the dioxirane derived from acetone and can be considered as a monomer of acetone peroxide. It is a powerful selective oxidizing agent that finds some use in organic synthesis. It is known only in the form of a dilute solution, usually in acetone, and hence the properties of the pure material are largely unknown. | 0 | Theoretical and Fundamental Chemistry |
Due to the increasing importance of bubble column reactors in most industrial sectors, the study of their hydrodynamics acquired significant relevance in recent years. The design of bubble columns depends on the quantification of three main phenomena: (1) mixing characteristics, (2) heat and mass transfer properties, (3) chemical kinetics in case of reactants systems.
As a consequence, the correct design and operation relies on the precise knowledge of the fluid dynamics phenomena on different scales: (1) molecular scale, (2) bubble scale, (3) reactor scale, and (4) industrial scale. The fluid dynamics properties in bubble columns depend on the interaction between the gas and liquid phases, which are related to the prevailing flow regime.
The description of the hydrodynamics of bubble columns required the definition of some parameters. The superficial gas and liquid velocities are defined as the ratio between the volumetric flow rate of the gas and liquid, respectively, divided by the column cross-sectional area. Although the superficial velocity concept is based on a simple one-dimensional flow assumption, it can be used to characterize and determine the hydrodynamics in bubble columns since an increase in its value can determine a flow regime transition.
Concerning global flow properties, a fundamental aspect which is helpful in describing the bubble column design process is the global gas holdup. It is defined as the ratio of the volume occupied by the gas phase and the sum of the volume occupied by the gas and liquid phases:
Where:
* is the volume occupied by the gas phase.
* is the volume occupied by the liquid phase.
The gas holdup provides information about the mean residence time of bubbles inside the column. Combined with bubble dimensions ( a fundamental local flow property), it determines the interfacial area for the heat and mass transfer rate between the phases. | 1 | Applied and Interdisciplinary Chemistry |
The information on this page is partially translated from the equivalent page in French :fr:Alain Berton (Chimiste) licensed under the Creative Commons/Attribution Sharealike [https://creativecommons.org/licenses/by-sa/3.0/]. History of contributions can be checked here:[https://fr.wikipedia.org/w/index.php?title=Alain_Berton_%28chimiste%29&action=history] | 0 | Theoretical and Fundamental Chemistry |
Copolymerization is used to modify the properties of manufactured plastics to meet specific needs, for example to reduce crystallinity, modify glass transition temperature, control wetting properties or to improve solubility. It is a way of improving mechanical properties, in a technique known as rubber toughening. Elastomeric phases within a rigid matrix act as crack arrestors, and so increase the energy absorption when the material is impacted for example. Acrylonitrile butadiene styrene is a common example. | 0 | Theoretical and Fundamental Chemistry |
Toxic metals can be present in the aqueous environment at trace or ultra-trace concentrations, yet still be toxicologically significant and thus cause harm to humans or the environment. Because these concentrations are so low, they would fall beyond the detection limits of most analytical instruments if the media had been sampled using traditional grab samples. Using SLMDs to passively collect metals over an extended period of time allows for trace metals to accumulate to detectable levels, which can give more accurate estimate of aquatic chemistry and contamination. SLMDs also have the advantage of being able to capture pulses of metal contamination that might otherwise go undetected when using grab samples.
SLMDs are limited to the assessment of labile metals, and cannot be used to monitor for organic contaminants. Further, while the ability of SLMDs to sample copper, zinc, nickel, lead, and cadmium has been repeatedly demonstrated, there has been little laboratory research on their ability to reliably uptake other toxic metals. Still, while laboratory studies on the effectiveness of SLMDs have only investigated copper, zinc, nickel, lead, and cadmium, SLMDs have been used with success in field studies to assess a wider range of metals. | 0 | Theoretical and Fundamental Chemistry |
The creeping flow results can be applied in order to study the settling of sediments near the ocean bottom and the fall of moisture drops in the atmosphere. The principle is also applied in the falling sphere viscometer, an experimental device used to measure the viscosity of highly viscous fluids, for example oil, paraffin, tar etc. | 1 | Applied and Interdisciplinary Chemistry |
All members of Group VI use virally encoded reverse transcriptase, an RNA-dependent DNA polymerase, to produce DNA from the initial virion RNA genome. This DNA is often integrated into the host genome, as in the case of retroviruses and pseudoviruses, where it is replicated and transcribed by the host.
Group VI includes:
* Order Ortervirales
** Family Belpaoviridae
** Family Metaviridae
** Family Pseudoviridae
** Family Retroviridae – Retroviruses, e.g. HIV
** Family Caulimoviridae – a VII group virus family (see below)
The family Retroviridae was previously divided into three subfamilies (Oncovirinae, Lentivirinae, and Spumavirinae), but are now divided into two: Orthoretrovirinae and Spumaretrovirinae. The term oncovirus is now commonly used to describe a cancer-causing virus. This family now includes the following genera:
* Subfamily Orthoretrovirinae:
** Genus Alpharetrovirus; including Avian leukosis virus and Rous sarcoma virus
** Genus Betaretrovirus; including Mouse mammary tumour virus
** Genus Gammaretrovirus; including Murine leukemia virus and Feline leukemia virus
** Genus Deltaretrovirus; including Bovine leukemia virus and the cancer-causing Human T-lymphotropic virus
** Genus Epsilonretrovirus
** Genus Lentivirus; including Human immunodeficiency virus 1 and Simian and Feline immunodeficiency viruses
* Subfamily Spumaretrovirinae:
** Genus Bovispumavirus
** Genus Equispumavirus
** Genus Felispumavirus
** Genus Prosimiispumavirus
** Genus Simiispumavirus
Note that according to ICTV 2017, genus Spumavirus has been divided into five genera, and its former type species Simian foamy virus is now upgraded to genus Simiispumavirus with not less than 14 species, including new type species Eastern chimpanzee simian foamy virus. | 1 | Applied and Interdisciplinary Chemistry |
At this point, the lipoate-thioester functionality is translocated into the dihydrolipoyl transacetylase (E2) active site, where a transacylation reaction transfers the acetyl from the "swinging arm" of lipoyl to the thiol of coenzyme A. This produces acetyl-CoA, which is released from the enzyme complex and subsequently enters the citric acid cycle. E2 can also be known as lipoamide reductase-transacetylase. | 1 | Applied and Interdisciplinary Chemistry |
A carboxypeptidase (EC number 3.4.16 - 3.4.18) is a protease enzyme that hydrolyzes (cleaves) a peptide bond at the carboxy-terminal (C-terminal) end of a protein or peptide. This is in contrast to an aminopeptidases, which cleave peptide bonds at the N-terminus of proteins. Humans, animals, bacteria and plants contain several types of carboxypeptidases that have diverse functions ranging from catabolism to protein maturation. At least two mechanisms have been discussed. | 1 | Applied and Interdisciplinary Chemistry |
A phosphite anion or phosphite in inorganic chemistry usually refers to [HPO] but includes [HPO] ([HPO(OH)]). These anions are the conjugate bases of phosphorous acid (HPO). The corresponding salts, e.g. sodium phosphite (NaHPO) are reducing in character. | 0 | Theoretical and Fundamental Chemistry |
Roberts is a inventor or co-inventor on over 100 issued patents. He has received the E.B. Hershberg award and induction into the MEDI Hall of Fame in 2021. He has also been involved in the commercialization of some of his research, contributing to the establishment of biotech companies such as Receptos Pharmaceuticals and BlackThorn Pharmaceuticals. He is a member of the Royal Society of Chemistry, the Royal Society of Medicine, and the Medicinal Chemistry division of the American Chemical Society. | 0 | Theoretical and Fundamental Chemistry |
Sulfolene, or butadiene sulfone is a cyclic organic chemical with a sulfone functional group. It is a white, odorless, crystalline, indefinitely storable solid, which dissolves in water and many organic solvents. The compound is used as a source of butadiene. | 0 | Theoretical and Fundamental Chemistry |
A secondary kinetic isotope effect is observed when no bond to the isotopically labeled atom in the reactant is broken or formed. Secondary kinetic isotope effects tend to be much smaller than primary kinetic isotope effects; however, secondary deuterium isotope effects can be as large as 1.4 per deuterium atom, and techniques have been developed to measure heavy-element isotope effects to very high precision, so secondary kinetic isotope effects are still very useful for elucidating reaction mechanisms.
For the aforementioned nucleophilic substitution reactions, secondary hydrogen kinetic isotope effects at the α-carbon provide a direct means to distinguish between S1 and S2 reactions. It has been found that S1 reactions typically lead to large secondary kinetic isotope effects, approaching to their theoretical maximum at about 1.22, while S2 reactions typically yield secondary kinetic isotope effects that are very close to or less than unity. Kinetic isotope effects that are greater than 1 are referred to as normal kinetic isotope effects, while kinetic isotope effects that are less than one are referred to as inverse kinetic isotope effects. In general, smaller force constants in the transition state are expected to yield a normal kinetic isotope effect, and larger force constants in the transition state are expected to yield an inverse kinetic isotope effect when stretching vibrational contributions dominate the kinetic isotope effect.
The magnitudes of such secondary isotope effects at the α-carbon atom are largely determined by the C-H(D) vibrations. For an S1 reaction, since the carbon atom is converted into an sp hybridized carbenium ion during the transition state for the rate-determining step with an increase in C-H(D) bond order, an inverse kinetic isotope effect would be expected if only the stretching vibrations were important. The observed large normal kinetic isotope effects are found to be caused by significant out-of-plane bending vibrational contributions when going from the reactants to the transition state of carbenium ion formation. For S2 reactions, bending vibrations still play an important role for the kinetic isotope effect, but stretching vibrational contributions are of more comparable magnitude, and the resulting kinetic isotope effect may be normal or inverse depending on the specific contributions of the respective vibrations. | 0 | Theoretical and Fundamental Chemistry |
Silicon carbide is used in carborundum printmaking – a collagraph printmaking technique. Carborundum grit is applied in a paste to the surface of an aluminium plate. When the paste is dry, ink is applied and trapped in its granular surface, then wiped from the bare areas of the plate. The ink plate is then printed onto paper in a rolling-bed press used for intaglio printmaking. The result is a print of painted marks embossed into the paper.
Carborundum grit is also used in stone Lithography. Its uniform particle size allows it to be used to "Grain" a stone which removes the previous image. In a similar process to sanding, coarser grit Carborundum is applied to the stone and worked with a Levigator, typically a round plate eccentric on a perpendicular shaft, then gradually finer and finer grit is applied until the stone is clean. This creates a grease sensitive surface. | 1 | Applied and Interdisciplinary Chemistry |
Fluo-4 is used to measure calcium (Ca) concentrations inside living cells, and is often used for high-throughput screening of receptor ligands and calcium permeable ion channels.
The green-fluorescent calcium indicator, Fluo-4, is an improved version of the calcium indicator, Fluo-3. It is commonly used as the non-fluorescent acetoxymethyl ester (Fluo-4 AM) which is cleaved inside the cell to give the free, fluorescent Fluo-4. It loads faster, is brighter at equivalent concentrations and is well-excited by the 488 nm line of the argon-ion laser which is often used in biological research laboratories. Fluo-4 and its cell-permeable AM ester are available from a few commercial vendors. | 1 | Applied and Interdisciplinary Chemistry |
Let be an orientation-preserving rigid motion of R. The set of these transformations is a subgroup of Euclidean motions known as the special Euclidean group SE(3). These rigid motions are defined by transformations of x in R given by
consisting of a three-dimensional rotation A followed by a translation by the vector d.
A three-dimensional rotation A has a unique axis that defines a line L. Let the unit vector along this line be S so that the translation vector d can be resolved into a sum of two vectors, one parallel and one perpendicular to the axis L, that is,
In this case, the rigid motion takes the form
Now, the orientation preserving rigid motion D* = A(x) + d transforms all the points of R so that they remain in planes perpendicular to L. For a rigid motion of this type there is a unique point c in the plane P perpendicular to L through 0, such that
The point C can be calculated as
because d does not have a component in the direction of the axis of A.
A rigid motion D* with a fixed point must be a rotation of around the axis L through the point c. Therefore, the rigid motion
consists of a rotation about the line L followed by a translation by the vector d in the direction of the line L.
Conclusion: every rigid motion of R is the result of a rotation of R about a line L followed by a translation in the direction of the line. The combination of a rotation about a line and translation along the line is called a screw motion. | 0 | Theoretical and Fundamental Chemistry |
Find the depth of rainfall from a storm of duration 6 hours and return period 10 years on a catchment of 5 km in Sheffield.
#From the FSR maps, the M5-60 minutes rainfall is 20.5mm, and "r" = 0.4.
#Divide 20.5mm by 0.4 to get 51.3mm, which is the M5-2 days rainfall depth.
#Factor Z1 = 0.64, so multiply 51.3mm by 0.64 to get 32.8mm.
#Factor Z2 = 1.16, so multiply 32.8mm by 1.16 to get 38.1mm.
#The ARF is 0.96, so multiply 38.1mm by 0.96 to get 36.6mm.
Therefore the expected depth of rainfall from the storm is 36.6mm. The mean intensity of rainfall is given by 36.6mm divided by 6 hours, which is 6.1mm/hour. | 1 | Applied and Interdisciplinary Chemistry |
Atomic-force microscopy (AFM) is a powerful microscopy technique used for studying samples at a nanoscale and is often used to image protein distribution on a surface. It consists of a cantilever with a tip to scan over the surface. It is a valuable tool for measuring protein-protein and protein-surface interaction. However, the limiting factor of many AFM studies is that imaging is often performed after drying the surface which might affect protein folding and the structure of the protein layer. Moreover, the cantilever tip can dislodge a protein or corrugate the protein layer. | 1 | Applied and Interdisciplinary Chemistry |
The murexide test is an analytical technique to identify the presence of caffeine and other purine derivatives in a sample. These compounds do not respond to the common alkaloid identification tests such as Dragendorff's reagent. In this test, crude drugs (to be identified) are mixed with a tiny amount of potassium chlorate and a drop of hydrochloric acid. The sample is then evaporated to dryness and the resulting residue is exposed to ammonia vapour. Purine alkaloids produce a pinkish-purple color in this test due to formation of murexide (ammonium purpurate; appears purple in pure state), which the test is named after.
In pure form, murexide appears purple, but when it is produced by reaction of acidified solutions of purines and ammonia, various shades of purple and pink are produced. | 0 | Theoretical and Fundamental Chemistry |
The gating system serves many purposes, the most important being conveying the liquid material to the mold, but also controlling shrinkage, the speed of the liquid, turbulence, and trapping dross. The gates are usually attached to the thickest part of the casting to assist in controlling shrinkage. In especially large castings multiple gates or runners may be required to introduce metal to more than one point in the mold cavity. The speed of the material is important because if the material is traveling too slowly it can cool before completely filling, leading to misruns and cold shuts. If the material is moving too fast then the liquid material can erode the mold and contaminate the final casting. The shape and length of the gating system can also control how quickly the material cools; short round or square channels minimize heat loss.
The gating system may be designed to minimize turbulence, depending on the material being cast. For example, steel, cast iron, and most copper alloys are turbulent insensitive, but aluminium and magnesium alloys are turbulent sensitive. The turbulent insensitive materials usually have a short and open gating system to fill the mold as quickly as possible. However, for turbulent sensitive materials short sprues are used to minimize the distance the material must fall when entering the mold. Rectangular pouring cups and tapered sprues are used to prevent the formation of a vortex as the material flows into the mold; these vortices tend to suck gas and oxides into the mold. A large sprue well is used to dissipate the kinetic energy of the liquid material as it falls down the sprue, decreasing turbulence. The choke, which is the smallest cross-sectional area in the gating system used to control flow, can be placed near the sprue well to slow down and smooth out the flow. Note that on some molds the choke is still placed on the gates to make separation of the part easier, but induces extreme turbulence. The gates are usually attached to the bottom of the casting to minimize turbulence and splashing.
The gating system may also be designed to trap dross. One method is to take advantage of the fact that some dross has a lower density than the base material so it floats to the top of the gating system. Therefore, long flat runners with gates that exit from the bottom of the runners can trap dross in the runners; note that long flat runners will cool the material more rapidly than round or square runners. For materials where the dross is a similar density to the base material, such as aluminium, runner extensions and runner wells can be advantageous. These take advantage of the fact that the dross is usually located at the beginning of the pour, therefore the runner is extended past the last gate(s) and the contaminates are contained in the wells. Screens or filters may also be used to trap contaminates.
It is important to keep the size of the gating system small, because it all must be cut from the casting and remelted to be reused. The efficiency, or , of a casting system can be calculated by dividing the weight of the casting by the weight of the metal poured. Therefore, the higher the number the more efficient the gating system/risers. | 1 | Applied and Interdisciplinary Chemistry |
The first of preparation of a phosphaalkyne was achieved in 1961 when Thurman Gier produced phosphaethyne by passing phosphine gas at low pressure over an electric arc produced between two carbon electrodes. Condensation of the gaseous products in a –196 °C (–321 °F) trap revealed that the reaction had produced acetylene, ethylene, phosphaethyne, which was identified by infrared spectroscopy. | 0 | Theoretical and Fundamental Chemistry |
An example of modest stereoselectivity is the dehydrohalogenation of 2-iodobutane which yields 60% trans-2-butene and 20% cis-2-butene. Since alkene geometric isomers are also classified as diastereomers, this reaction would also be called diastereoselective.
Cram's rule predicts the major diastereomer resulting from the diastereoselective nucleophilic addition to a carbonyl group next to a chiral center. The chiral center need not be optically pure, as the relative stereochemistry will be the same for both enantiomers. In the example below the (S)-aldehyde reacts with a thiazole to form the (S,S) diastereomer but only a small amount of the (S,R) diastereomer:
The Sharpless epoxidation is an example of an enantioselective process, in which an achiral allylic alcohol substrate is transformed into an optically active epoxyalcohol. In the case of chiral allylic alcohols, kinetic resolution results. Another example is Sharpless asymmetric dihydroxylation. In the example below the achiral alkene yields only one of the possible 4 stereoisomers.
With a stereogenic center next to the carbocation the substitution can be stereoselective in inter- and intramolecular reactions. In the reaction depicted below the nucleophile (furan) can approach the carbocation formed from the least shielded side away from the bulky t-butyl group resulting in high facial diastereoselectivity: | 0 | Theoretical and Fundamental Chemistry |
Nevertheless, it was known that yeast extracts can ferment sugar even in the absence of living yeast cells. While studying this process in 1897, the German chemist and zymologist Eduard Buchner of Humboldt University of Berlin, Germany, found that sugar was fermented even when there were no living yeast cells in the mixture, by an enzyme complex secreted by yeast that he termed zymase. In 1907 he received the Nobel Prize in Chemistry for his research and discovery of "cell-free fermentation".
One year earlier, in 1906, ethanol fermentation studies led to the early discovery of oxidized nicotinamide adenine dinucleotide (NAD). | 1 | Applied and Interdisciplinary Chemistry |
In terms of applications, a popular allyl complex is allyl palladium chloride.
The reactivity of allyl ligands depends on the overall complex, although the influence of the metal center can be roughly summarized as
:(more reactive) Fe ≫ Pd > Mo > W (less reactive)
Such complexes are usually electrophilic (i.e., react with nucleophiles), but nickel allyl complexes are usually nucleophilic (resp. with electrophiles). In the former case, the addition may occur at unusual locations, and can be useful in organic synthesis. | 0 | Theoretical and Fundamental Chemistry |
Kulkarnis researches were mainly in the fields of Chemical Reaction Engineering, Applied Mathematics and Transport phenomena and he is known for his work on fluidized bed reactors and chemical reactors. He is credited with introducing an integer-solution approach and novel ideas on noise-induced transitions and his work on Artificial Intelligence-based evolutionary formalisms is reported to have assisted in a better understanding of reacting and reactor systems. His work spanned from conventional chemical reaction engineering in gas-liquid and gas-solid catalytic reactions to reactor stability to stochastic analysis of chemically reacting systems as well as inter-disciplinary fields. A model reaction system termed Encillator, an analytical approach for the solving model equations based on arithmetics, use of initial value formalism for modelling fluidized-bed reactors, introduction of normal form theory, evolutionary algorithms and stochastic approximation in analysing reactor behavior and performance are some of the contributions made by him. He holds US and Indian patents for several processes he has developed which include Method and an Apparatus for the Identification and/or Separation of Complex Composite Signals into its Deterministic and Noisy Components, Process for preparation of pure alkyl esters from alkali metal salt of carboxylic acid, and Enantioselective resolution process for arylpropionic acid drugs from the racemic mixture'.
Kulakrnis researches have been documented in several peer-reviewed articles; and the online article repository of Indian Academy of Sciences has listed 250 of them. Besides, he has contributed chapters to books edited by others and has published seven edited or authored texts, including Recent Trends in Chemical Reaction Engineering, Advances in Transport Processes, The Analysis of Chemically Reacting Systems: A Stochastic Approach and Transport processes in fluidized bed reactors. He has guided several masters and doctoral scholars in their studies and has conducted training for students on mathematical modelling. He also serves as one of the directors of Hitech Bio Sciences India Limited, a probiotics and nutraceuticals manufacturer based in Pune and is a member of the advisory committee of the International Conference on Sustainable Development for Energy and Environment (ICSDEE 2017). | 1 | Applied and Interdisciplinary Chemistry |
The Swain equation relates the kinetic isotope effect for the protium/tritium combination with that of the protium/deuterium combination according to:
where k are the reaction rate constants for the protonated, deuterated and tritiated reactants respectively. | 0 | Theoretical and Fundamental Chemistry |
Arsenic in the solid state can be found as gray, black, or yellow allotropes. These various forms feature diverse structural motifs, with yellow arsenic enabling the widest range of reactivity. In particular, reaction of yellow arsenic with main group and transition metal elements results in compounds with wide-ranging structural motifs, with butterfly, sandwich and realgar-type moieties featuring most prominently. | 0 | Theoretical and Fundamental Chemistry |
Unlike the widely used automotive antifreeze, ethylene glycol, AFPs do not lower freezing point in proportion to concentration. Rather, they work in a noncolligative manner. This phenomenon allows them to act as an antifreeze at concentrations 1/300th to 1/500th of those of other dissolved solutes. Their low concentration minimizes their effect on osmotic pressure. The unusual properties of AFPs are attributed to their selective affinity for specific crystalline ice forms and the resulting blockade of the ice-nucleation process. | 1 | Applied and Interdisciplinary Chemistry |
Pyrometallurgy is a branch of extractive metallurgy. It consists of the thermal treatment of minerals and metallurgical ores and concentrates to bring about physical and chemical transformations in the materials to enable recovery of valuable metals. Pyrometallurgical treatment may produce products able to be sold such as pure metals, or intermediate compounds or alloys, suitable as feed for further processing. Examples of elements extracted by pyrometallurgical processes include the oxides of less reactive elements like iron, copper, zinc, chromium, tin, and manganese.
Pyrometallurgical processes are generally grouped into one or more of the following categories:
* calcining,
* roasting,
* smelting,
* refining.
Most pyrometallurgical processes require energy input to sustain the temperature at which the process takes place. The energy is usually provided in the form of combustion or from electrical heat. When sufficient material is present in the feed to sustain the process temperature solely by exothermic reaction (i.e. without the addition of fuel or electrical heat), the process is said to be "autogenous". Processing of some sulfide ores exploit the exothermicity of their combustion | 1 | Applied and Interdisciplinary Chemistry |
Cottonseed meal is the byproduct remaining after cotton is ginned, the oil extracted, and the seeds crushed. Cottonseed meal is usually used for animal feed and in organic fertilizers.
Cottonseed meal is about 40 percent protein by weight. Compared to cellulose and lignin, proteins decompose rapidly and release nitrogen. Unweathered, light-colored plant material such as hay, autumn tree leaves, sawdust, straw, woodchips, and wood shavings are nitrogen deficient, and do not decompose easily. Cottonseed meal, which is rich in nitrogen, is often mixed with these types of materials to improve decomposition speed.
Whole cottonseed should not be fed to poultry and to ruminants like cattle, goats, and sheep. Cottonseed meal also contains gossypol and cyclopropenoid fatty acids. Cottonseed meal should only be fed to adult ruminants, as immature animals have less well-developed digestive systems. Gossypol is also highly toxic to monogastrics. Cyclopropenoid fatty acids can have a number of effects, some adverse, such as reduced fertility in laying hens; alterations in the composition of fatty acids in blood plasma, the heart, the liver, and the ovaries; the slowing of growth in young animals; and B vitamin deficiency. The protein in cottonseed meal is also low in lysine.
Glandless cottonseed was developed in the early 1960s. Cottonseed meal derived from glandless cottonseed contains almost no gossypol. | 0 | Theoretical and Fundamental Chemistry |
Historically, the calculation of glass properties is directly related to the founding of glass science. At the end of the 19th century the physicist Ernst Abbe developed equations that allow calculating the design of optimized optical microscopes in Jena, Germany, stimulated by co-operation with the optical workshop of Carl Zeiss. Before Ernst Abbe's time the building of microscopes was mainly a work of art and experienced craftsmanship, resulting in very expensive optical microscopes with variable quality. Now Ernst Abbe knew exactly how to construct an excellent microscope, but unfortunately, the required lenses and prisms with specific ratios of refractive index and dispersion did not exist. Ernst Abbe was not able to find answers to his needs from glass artists and engineers; glass making was not based on science at this time.
In 1879 the young glass engineer Otto Schott sent Abbe glass samples with a special composition (lithium silicate glass) that he had prepared himself and that he hoped to show special optical properties. Following measurements by Ernst Abbe, Schott's glass samples did not have the desired properties, and they were also not as homogeneous as desired. Nevertheless, Ernst Abbe invited Otto Schott to work on the problem further and to evaluate all possible glass components systematically. Finally, Schott succeeded in producing homogeneous glass samples, and he invented borosilicate glass with the optical properties Abbe needed. These inventions gave rise to the well-known companies Zeiss and Schott Glass (see also Timeline of microscope technology). Systematic glass research was born. In 1908, Eugene Sullivan founded glass research also in the United States (Corning, New York).
At the beginning of glass research it was most important to know the relation between the glass composition and its properties. For this purpose Otto Schott introduced the additivity principle in several publications for calculation of glass properties. This principle implies that the relation between the glass composition and a specific property is linear to all glass component concentrations, assuming an ideal mixture, with C and b representing specific glass component concentrations and related coefficients respectively in the equation below. The additivity principle is a simplification and only valid within narrow composition ranges as seen in the displayed diagrams for the refractive index and the viscosity. Nevertheless, the application of the additivity principle lead the way to many of Schotts inventions, including optical glasses, glasses with low thermal expansion for cooking and laboratory ware (Duran), and glasses with reduced freezing point depression for mercury thermometers. Subsequently, English and Gehlhoff et al. published similar additive glass property calculation models. Schotts additivity principle is still widely in use today in glass research and technology.
:Additivity Principle: | 0 | Theoretical and Fundamental Chemistry |
The electrodes in an electrochemical cell are each classified as either an anode or a cathode. An anode is an electrode at which electrons leave the cell and oxidation occurs, while a cathode is an electrode at which electrons enter the cell and reduction occurs. Each electrode may become either an anode or a cathode depending on the voltage applied to the cell.
Each deionization cell consists of an electrode and an electrolyte with ions that undergo either oxidation or reduction. Because they commonly consist of ions in solution, the electrolytes are often known as "ionic solutions", but molten and solid electrolytes are also possible.
Water passes between an anode and a cathode. Ion-selective membranes allow positive ions to separate from the water toward the negative electrode and negative ions toward the positive electrode. As a result, the ions cannot escape the cell and deionized water is produced.
When using a current that is higher than necessary for the movement of the ions, a portion of the incident water will be split, forming hydroxide (OH) anions and hydrogen (H) cations. These species will replace the impurity anions and cations in the resin. This process is called "in situ regeneration" of the resin. Because this replacement occurs alongside the deionization process it allows for continuous purification, as opposed to deionization techniques that require a pause in operation to chemically regenerate ion exchange resins.
The purpose of the ion exchange resin is to maintain a stable conductance across the feedwater. Without the resin, ions could be removed initially, but the conductance would drop dramatically as the concentration of ions decreases. With lower conductance, the electrodes would become less able to efficiently direct the flow of electrons across the cell, whereas with the addition of resin and thus a steady conductance, electron flow remains steady and ensures a steady rate of ion removal. With a resin, therefore, the final remaining ion concentrations in the processed water can be lower by orders of magnitude. | 0 | Theoretical and Fundamental Chemistry |
In organic chemistry, a methylidyne group or just methylidyne is a neutral part of a molecule (a substituent or functional group) with formula , consisting of a carbon atom bonded to a hydrogen atom by one single bond and to the rest of the molecule by one triple bond. For example, a methylidyne group is present in n-methylidyne-1-hexanaminium, .
The name "methylidyne" is also used for the methylidyne radical (carbyne) , the same two atoms not bound to any other atom. | 0 | Theoretical and Fundamental Chemistry |
The relation of thermal equilibrium is an instance of equilibrium between two bodies, which means that it refers to transfer through a selectively permeable partition of matter or work; it is called a diathermal connection. According to Lieb and Yngvason, the essential meaning of the relation of thermal equilibrium includes that it is reflexive and symmetric. It is not included in the essential meaning whether it is or is not transitive. After discussing the semantics of the definition, they postulate a substantial physical axiom, that they call the "zeroth law of thermodynamics", that thermal equilibrium is a transitive relation. They comment that the equivalence classes of systems so established are called isotherms. | 0 | Theoretical and Fundamental Chemistry |
Nondepolarizing NMBAs can be used to induce muscle relaxation that improves surgical conditions, including laparoscopic, robotic, abdominal and thoracic procedures. It can reduce patient movement, muscle tone, breathing or coughing against ventilator and allow lower insufflation pressure during laparoscopy. Administration of NMBAs should be individualized according to patient’s parameters. However, many operations can be performed without the need to apply any NMBAs as adequate anesthesia during surgery can achieve many of the theoretical benefits of neuromuscular blockage. | 1 | Applied and Interdisciplinary Chemistry |
Barium chloride, along with other water-soluble barium salts, is highly toxic. It irritates eyes and skin, causing redness and pain. It damages kidneys. Fatal dose of barium chloride for a human has been reported to be about 0.8-0.9 g. Systemic effects of acute barium chloride toxicity include abdominal pain, diarrhea, nausea, vomiting, cardiac arrhythmia, muscular paralysis, and death. The ions compete with the ions, causing the muscle fibers to be electrically unexcitable, thus causing weakness and paralysis of the body. Sodium sulfate and magnesium sulfate are potential antidotes because they form barium sulfate BaSO, which is relatively non-toxic because of its insolubility in water.
Barium chloride is not classified as a human carcinogen. | 0 | Theoretical and Fundamental Chemistry |
The energy levels needed to overcome the coulomb barrier, about 100 keV for D-T fuel, corresponds to millions of degrees, but is within the energy range that can be provided by even the smallest particle accelerators. For instance, the very first cyclotron, built in 1932, was capable of producing 4.8 MeV in a device that fit on a tabletop.
The original earthbound fusion reactions were created by such a device at the Cavendish Laboratory at Cambridge University. In 1934, Mark Oliphant, Paul Harteck and Ernest Rutherford used a new type of power supply to power a device not unlike an electron gun to shoot deuterium nuclei into a metal foil infused with deuterium, lithium or other light elements. This apparatus allowed them to study the nuclear cross section of the various reactions, and it was their work that produced the 100 keV figure.
The chance that any given deuteron will hit one of the deuterium atoms in the metal foil is vanishingly small. The experiment only succeeded because it ran for extended periods, and the rare reactions that did occur were so powerful that they could not be missed. But as the basis of a system for power production it simply wouldn't work; the vast majority of the accelerated deuterons goes right through the foil without undergoing a collision, and all the energy put into accelerating it is lost. The small number of reactions that do occur give off far less energy that what is fed into the accelerator.
A somewhat related concept was explored by Stanislaw Ulam and Jim Tuck at Los Alamos shortly after World War II. In this system, deuterium was infused into metal like the Cavendish experiments, but then formed into a cone and inserted into shaped charge warheads. Two such warheads were aimed at each other and fired, forming rapidly moving jets of deuterized metal that collided. These experiments were carried out in 1946 but failed to turn up any evidence of fusion reactions. | 0 | Theoretical and Fundamental Chemistry |
Entomopathogens are another group of organisms that are influenced by plants. The extent of the influence largely depends on the evolutionary history shared between the two and the pathogens' method of infection and survival duration outside of a host. Different insect host plants contain compounds that cause modulate insect mortality when certain entomopathogens are simultaneously injected. Increases in mortality of up to 50-fold have been recorded. However, certain plants influence entomopathogens in negative ways, reducing their efficacy.
It is primarily the leaf surface of the plant that influences the entomopathogen; plants can release various exudates, phytochemicals, and alleolochemicals through their leaves, some of which have the ability to inactivate certain entomopathogens. In contrast, in other plant species, leaf characteristics can increase the efficacy of entomopathogens. For example, the mortality of pea aphids was higher in the group of aphids that were found on plants with fewer wax exudates than in those on plants with more wax exudates. This reduced waxiness increases the transmission of Pandora neoaphidus conidia from the plant to the aphids.
Feeding-induced volatiles emitted by different plants increase the amount of spores released by certain entomopathogenic fungi, increasing the likelihood of infection of some herbivores but not others. Plants can also influence pathogen efficacy indirectly, and this typically occurs either by increasing the susceptibility of the herbivore hosts or by changing their behavior. This influence can often take the form of altered growth rates, herbivore physiology, or feeding habits. Thus, there are various ways that host plant species can influence entomopathogenic interactions.
In one study, brassicas were found to defend themselves by acting as a vector for entomopathogens. Virus-infected aphids feeding on the plants introduce a virus into the phloem. The virus is passively transported in the phloem and carried throughout the plant. This causes aphids feeding apart from the infected aphids to become infected as well. This finding offers the possibility of injecting crops with compatible entomopathogenic viruses to defend against susceptible insect pests. | 1 | Applied and Interdisciplinary Chemistry |
Studies published in 1992 and 1997 indicate that the level of aerobic fitness of an individual does not have any correlation with the level of resting metabolism. Both studies find that aerobic fitness levels do not improve the predictive power of fat free mass for resting metabolic rate.
However, recent research from the Journal of Applied Physiology, published in 2012, compared resistance training and aerobic training on body mass and fat mass in overweight adults (STRRIDE AT/RT). When you consider time commitments against health benefits, aerobic training is the optimal mode of exercise for reducing fat mass and body mass as a primary consideration, resistance training is good as a secondary factor when aging and lean mass are a concern. Resistance training causes injuries at a much higher rate than aerobic training. Compared to resistance training, it was found that aerobic training resulted in a significantly more pronounced reduction of body weight by enhancing the cardiovascular system which is what is the principal factor in metabolic utilization of fat substrates. Resistance training if time is available is also helpful in post-exercise metabolism, but it is an adjunctive factor because the body needs to heal sufficiently between resistance training episodes, whereas with aerobic training, the body can accept this every day. RMR and BMR are measurements of daily consumption of calories. The majority of studies that are published on this topic look at aerobic exercise because of its efficacy for health and weight management.
Anaerobic exercise, such as weight lifting, builds additional muscle mass. Muscle contributes to the fat-free mass of an individual and therefore effective results from anaerobic exercise will increase BMR. However, the actual effect on BMR is controversial and difficult to enumerate. Various studies suggest that the resting metabolic rate of trained muscle is around 55 kJ/kg per day. Even a substantial increase in muscle mass, say 5 kg, would make only a minor impact on BMR. | 1 | Applied and Interdisciplinary Chemistry |
Nearly all research in algal biofuels has focused on culturing single species, or monocultures, of microalgae. However, ecological theory and empirical studies have demonstrated that plant and algae polycultures, i.e. groups of multiple species, tend to produce larger yields than monocultures. Experiments have also shown that more diverse aquatic microbial communities tend to be more stable through time than less diverse communities. Recent studies found that polycultures of microalgae produced significantly higher lipid yields than monocultures. Polycultures also tend to be more resistant to pest and disease outbreaks, as well as invasion by other plants or algae. Thus culturing microalgae in polyculture may not only increase yields and stability of yields of biofuel, but also reduce the environmental impact of an algal biofuel industry. | 1 | Applied and Interdisciplinary Chemistry |
The captive bubble method is a method for measuring contact angle between a liquid and a solid, by using drop shape analysis. In this method, a bubble of air is injected beneath a solid, the surface of which is located in the liquid, instead of placing a drop on the solid as in the case of the sessile drop technique.
The method is particularly suitable for solids with high surface free energy on which liquids spread out. Hydrogels, such as those that comprise soft contact lenses, are inaccessible to the standard arrangement; so the captive bubble method is also used in such cases. A contact angle is formed on a smooth, periodically heterogeneous solid surface. Above the solid surface, a liquid drop is submerged to the solid in a fluid. The measurement of contact angles usually contributes to the measurement of the surface energy of solids in the industry. Different from other methods of measuring the contact angle, such as the sessile drop technique, the system utilized in the captive bubble method has the fluid bubble attached from below to the solid surface, such that both the liquid bubble and the solid interact with a fluid. | 0 | Theoretical and Fundamental Chemistry |
, where is the enthalpy of the liquid and is the enthalpy of the vapour
By substituting the mass balance equation in above equation we get the following expression: | 0 | Theoretical and Fundamental Chemistry |
At 15 GPa graphite changes to a hard transparent form, that is not diamond. Diamond is very resistant to pressure, but at about 1 TPa (1000 GPa) transforms to a BC-8 form. | 0 | Theoretical and Fundamental Chemistry |
In 1989, after Fleischmann and Pons had made their claims, many research groups tried to reproduce the Fleischmann-Pons experiment, without success. A few other research groups, however, reported successful reproductions of cold fusion during this time. In July 1989, an Indian group from the Bhabha Atomic Research Centre (P. K. Iyengar and M. Srinivasan) and in October 1989, John Bockris' group from Texas A&M University reported on the creation of tritium. In December 1990, professor Richard Oriani of the University of Minnesota reported excess heat.
Groups that did report successes found that some of their cells were producing the effect, while other cells that were built exactly the same and used the same materials were not producing the effect. Researchers that continued to work on the topic have claimed that over the years many successful replications have been made, but still have problems getting reliable replications. Reproducibility is one of the main principles of the scientific method, and its lack led most physicists to believe that the few positive reports could be attributed to experimental error. The DOE 2004 report said among its conclusions and recommendations: | 0 | Theoretical and Fundamental Chemistry |
The Oddy test has gone through many changes and refinements over time. Whereas Andrew Oddy proposed to place each metal coupon in a separate glass container with the material to be tested, Bamberger et al. proposed a "three-in-one" test, where all three metal coupons shared one container, simplifying the procedure. Robinett and Thickett (2003) refined the "three-in-one" test by stabilizing the metal coupons.
One of the main issues with the Oddy test is that there is some subjectivity to the interpretation of the results, since it is primarily a visual determination. Some proposals have been made to use objective quantification methods for assessment of the results of the Oddy test.
Institutions that use the Oddy test in their research are mainly art museums such as The J. Paul Getty Museum, The Nelson-Atkins Museum of Art, and the Metropolitan Museum of Art. | 1 | Applied and Interdisciplinary Chemistry |
The most significant fraction of electron–positron annihilations results in two 511 keV gamma photons being emitted at almost 180 degrees to each other. Hence, it is possible to localize their source along a straight line of coincidence (also called the line of response, or LOR). In practice, the LOR has a non-zero width as the emitted photons are not exactly 180 degrees apart. If the resolving time of the detectors is less than 500 picoseconds rather than about 10 nanoseconds, it is possible to localize the event to a segment of a chord, whose length is determined by the detector timing resolution. As the timing resolution improves, the signal-to-noise ratio (SNR) of the image will improve, requiring fewer events to achieve the same image quality. This technology is not yet common, but it is available on some new systems. | 1 | Applied and Interdisciplinary Chemistry |
Common applications of force spectroscopy are measurements of polymer elasticity, especially biopolymers such as RNA and DNA. Another biophysical application of polymer force spectroscopy is on protein unfolding. Modular proteins can be adsorbed to a gold or (more rarely) mica surface and then stretched. The sequential unfolding of modules is observed as a very characteristic sawtooth pattern of the force vs elongation graph; every tooth corresponds to the unfolding of a single protein module (apart from the last that is generally the detachment of the protein molecule from the tip). Much information about protein elasticity and protein unfolding can be obtained by this technique. Many proteins in the living cell must face mechanical stress.
Moreover, force spectroscopy can be used to investigate the enzymatic activity of proteins involved in DNA replication, transcription, organization and repair. This is achieved by measuring the position of a bead attached to a DNA-protein complex stalled on a DNA tether that has one end attached to a surface, while keeping the force constant. This technique has been used, for example, to study transcription elongation inhibition by Klebsidin and Acinetodin.
The other main application of force spectroscopy is the study of mechanical resistance of chemical bonds. In this case, generally the tip is functionalized with a ligand that binds to another molecule bound to the surface. The tip is pushed on the surface, allowing for contact between the two molecules, and then retracted until the newly formed bond breaks up. The force at which the bond breaks up is measured. Since mechanical breaking is a kinetic, stochastic process, the breaking force is not an absolute parameter, but it is a function of both temperature and pulling speed. Low temperatures and high pulling speeds correspond to higher breaking forces. By careful analysis of the breaking force at various pulling speeds, it is possible to map the energy landscape of the chemical bond under mechanical force. This is leading to interesting results in the study of antibody-antigen, protein-protein, protein-living cell interaction and catch bonds.
Recently this technique has been used in cell biology to measure the aggregative stochastic forces created by motor proteins that influence the motion of particles within the cytoplasm. In this way, force spectrum microscopy may be used better to understand the many cellular processes that require the motion of particles within cytoplasm. | 0 | Theoretical and Fundamental Chemistry |
:V09HA01 Technetium (Tc) human immunoglobulin
:V09HA02 Technetium (Tc) exametazime labelled cells
:V09HA03 Technetium (Tc) antigranulocyte antibody
:V09HA04 Technetium (Tc) sulesomab | 1 | Applied and Interdisciplinary Chemistry |
Turner angle is usually discussed when researching ocean stratification and double diffusion.
Turner angle assesses the vertical stability, indicating the density of the water column changes with depth. The density is generally related to potential temperature and salinity profile: the cooler and saltier the water is, the denser it is. As the light water overlays on the dense water, the water column is called stable stratification. The buoyancy force preserves stable stratification. One characteristic of stability is that the Brunt-Vaisala frequency N>0, which includes three situations of doubly stable, thermal diffusion, and salt fingering. Considering the density attribute to both temperature and salinity, a "double stable" status, where the temperature decreases with depth (∂θ/∂z>0) and salinity increases with depth (∂S/∂z<0), is the most ideal stable water column, which means the water column is stably stratified with respect to both θ and S.
The water column can maintain stability even though one attribute does not agree. In one case of heat diffusion dominant, diffusive double-diffusion is possible when the salinity structure is stable while the temperature structure is unstable (∂θ/∂z<0, ∂S/∂z<0). In the other case, salt fingering can be expected when relatively warm, salty water overlies relatively colder, fresher water (∂θ/∂z>0, ∂S/∂z>0). Both these cases lead to turbulence and mixing on the vertical structure of the water column.
Since Turner angle can indicate the thermal and haline properties of the water column, it is used to discuss water thermal and haline structures, and demonstrated benefits of localizing the boundaries of the subarctic front. | 1 | Applied and Interdisciplinary Chemistry |
Centrifugal partition chromatography has been extensively used for isolation and purification of natural products for 40 years. Due to the ability to get very high selectivity, and the ability to tolerate samples containing particulated matter, it is possible to work with direct extracts of biomass, opposed to traditional liquid chromatography, where impurities degrade the solid stationary phase so that separation become impossible.
There are numerous laboratory scale centrifugal partition chromatography manufacturers around the world, like Gilson (Armen Instrument), Kromaton (Rousselet Robatel), and AECS-QUIKPREP. These instruments operate at flow rates of 1–500 mL/min. with stationary phase retentions of 40–80%. | 0 | Theoretical and Fundamental Chemistry |
One of the more interesting applications of hydrogenases is to produce hydrogen, due its capacity to catalyze its redox reaction:
In the field of hydrogen production, the incorporation of chemical compounds in electrochemical devices to produce molecular hydrogen has been a topic of huge interest in the recent years due to the possibility of using hydrogen as a replacement of the fossil fuels as an energetic carrier. This approach of using materials inspired by natural models to do the same function as their natural counterparts is called bio-mimetic approach. Nowadays this approach has received a big impulse due to the availability of high-resolution crystal structures of several hydrogenases obtained with different techniques. The technical details of these hydrogenases are stored in electronic databases at disposition to who may be interested.
This information has allowed scientists to determine the important parts of the enzyme necessary to catalyze the reaction and determine the pathway of the reaction in a very detailed way. Which allow to have a very good comprehension of what is necessary to catalyze the same reaction using artificial components. | 1 | Applied and Interdisciplinary Chemistry |
Nuclear receptor interacting protein 1 (NRIP1) is a nuclear protein that specifically interacts with the hormone-dependent activation domain AF2 of nuclear receptors. Also known as RIP140, this protein is a key regulator which modulates transcriptional activity of a variety of transcription factors, including the estrogen receptor.
RIP140 has an important role in regulating lipid and glucose metabolism, and regulates gene expression in metabolic tissues including heart, skeletal muscle, and liver. A major role for RIP140 in adipose tissue is to block the expression of genes involved in energy dissipation and mitochondrial uncoupling, including uncoupling protein 1 and carnitine palmitoyltransferase 1b.
Estrogen-related receptor alpha (ERRa) can activate RIP140 during adipogenesis, by means of directly binding to an estrogen receptor element/ERR element and indirectly through Sp1 binding to the proximal promoter.
RIP140 suppresses the expression of mitochondrial proteins succinate dehydrogenase complex b and CoxVb and acts as a negative regulator of glucose uptake in mice. | 1 | Applied and Interdisciplinary Chemistry |
While water acts as a catalyst in the reaction, other catalysts can be added to the reaction vessel to optimize the conversion. Previously used catalysts include water-soluble inorganic compounds and salts, including KOH and NaCO, as well as transition metal catalysts using nickel, palladium, platinum and ruthenium supported on either carbon, silica or alumina. The addition of these catalysts can lead to an oil yield increase of 20% or greater, due to the catalysts converting the protein, cellulose, and hemicellulose into oil. This ability for catalysts to convert biomaterials other than fats and oils to bio-oil allows for a wider range of feedstock to be used. | 0 | Theoretical and Fundamental Chemistry |
The residual sodium carbonate (RSC) index of irrigation water or soil water is used to indicate the alkalinity hazard for soil. The RSC index is used to find the suitability of the water for irrigation in clay soils which have a high cation exchange capacity. When dissolved sodium in comparison with dissolved calcium and magnesium is high in water, clay soil swells or undergoes dispersion which drastically reduces its infiltration capacity.
In the dispersed soil structure, the plant roots are unable to spread deeper into the soil due to lack of moisture. However, high RSC index water does not enhance the osmotic pressure to impede the off take of water by the plant roots unlike high salinity water. Clay soils irrigation with high RSC index water leads to fallow alkali soils formation. | 0 | Theoretical and Fundamental Chemistry |
* Carbon steel is often divided into two main categories: low-carbon steel and high-carbon steel.
* Carbon steel may also contain other elements, such as manganese, phosphorus, sulfur, and silicon, which can affect its properties.
* Carbon steel can be easily machined and welded, making it versatile for various applications. It can also be heat treated to improve its strength, Hardness, and durability.
* Carbon steel is susceptible to rust and corrosion, especially in environments with high moisture levels and/or salt.
* Carbon steel can be shielded from corrosion by coating it with paint, varnish, or other protective material.
* Alternatively, it can be made from a stainless steel alloy that contains chromium, which provides excellent corrosion resistance.
* Carbon steel is sometimes alloyed with other elements to improve its properties, such as adding chromium and/or nickel to improve its resistance to corrosion and oxidation or adding molybdenum to improve its strength and toughness at high temperatures.
* Carbon steel is an environmentally friendly material, as it is easily recyclable and can be reused in various applications. It is also energy-efficient to produce, as it requires less energy than other metals such as aluminium and copper. | 1 | Applied and Interdisciplinary Chemistry |
The action potential in a normal skeletal muscle cell is similar to the action potential in neurons. Action potentials result from the depolarization of the cell membrane (the sarcolemma), which opens voltage-sensitive sodium channels; these become inactivated and the membrane is repolarized through the outward current of potassium ions. The resting potential prior to the action potential is typically −90mV, somewhat more negative than typical neurons. The muscle action potential lasts roughly 2–4 ms, the absolute refractory period is roughly 1–3 ms, and the conduction velocity along the muscle is roughly 5 m/s. The action potential releases calcium ions that free up the tropomyosin and allow the muscle to contract. Muscle action potentials are provoked by the arrival of a pre-synaptic neuronal action potential at the neuromuscular junction, which is a common target for neurotoxins. | 0 | Theoretical and Fundamental Chemistry |
An overdose of modafinil can lead to a range of symptoms and complications. Psychiatric symptoms may include psychosis, mania, hallucinations, and suicidal ideation, which can occur even in individuals without a history of mental illness and may persist after discontinuation of the drug. Neurological complications, such as seizures, tremors, dystonia, and dyskinesia, may arise from modafinil's interaction with various neurotransmitter systems.
Allergic reactions such as rash, angioedema, anaphylaxis, and Stevens–Johnson syndrome may be triggered by an immunological response to modafinil or its metabolites. Cardiovascular complications like hypertension, tachycardia, chest pain, and arrhythmias may also be observed due to modafinil's sympathomimetic action.
In animal studies, the median lethal dose (LD) of modafinil varies among species and depends on the route of administration. In mice and rats, the LD is approximately if administered via an injection, but the oral LD for rats is . The LD value for humans have not been established. Human clinical trials have involved total daily doses up to for 7–21 days. Acute one-time total overdoses up to have not been life-threatening but resulted in symptoms like agitation, insomnia, tremor, palpitations, and gastrointestinal disturbances.
The management of modafinil overdose involves supportive care, monitoring of vital signs, and treatment of specific complications. In cases of recent consumption, activated charcoal, gastric lavage, or hemodialysis may be used. There is no specific antidote for modafinil overdose. The main way to deal with modafinil overdose is supportive care, which includes sedating the patient and stabilizing their blood pressure, and muscle activity in case of manifestations such as agitation or tremor. | 0 | Theoretical and Fundamental Chemistry |
However, it is clear that in a general case the behaviour of Bose–Einstein condensate can be described by coupled evolution equations for condensate density, superfluid velocity and distribution function of elementary excitations. This problem was solved in 1977 by Peletminskii et al. in microscopical approach. The Peletminskii equations are valid for any finite temperatures below the critical point. Years after, in 1985, Kirkpatrick and Dorfman obtained similar equations using another microscopical approach. The Peletminskii equations also reproduce Khalatnikov hydrodynamical equations for superfluid as a limiting case. | 0 | Theoretical and Fundamental Chemistry |
3-Azidocoumarin is an organic compound that is used in the area of bioconjugation. It is a derivative of coumarin, a natural product and precursor for the widely used Coumadin. Azidocoumarin has emerged as a widely applicable labeling agent in diverse biological systems. In particular, it participates in the aptly named click reaction with alkynes. Bioconjugation involves the labeling of certain cellular components and is applicable to fields such a proteomics and functional genomics with a detachable, fluorescent tag. | 1 | Applied and Interdisciplinary Chemistry |
Dry regions such as western Asia, north Africa, Australia and the southwestern United States are ideal for PDRC application due to the relative lack of humidity and cloud cover in both winter and summer. The cooling potential for desert regions has been estimated at "in the higher range of 80–110 W/m2," as per Aili et al. and 120 W/m2 as per Yin et al. The Sahara Desert and western Asia is the largest area on Earth with a high cooling potential in both winter and summer.
The cooling potential of desert regions risks being relatively unfulfilled due to very low population densities, which may lower interest in applying PDRCs for local cooling. However, in the event of global implementation, lowly populated or unpopulated desert climates may be an important "land surface contribution to the planetary albedo" which could "reduce air temperature near the surface, if not the whole atmosphere." | 0 | Theoretical and Fundamental Chemistry |
Proper explanation of optical trapping behavior depends upon the size of the trapped particle relative to the wavelength of light used to trap it. In cases where the dimensions of the particle are much greater than the wavelength, a simple ray optics treatment is sufficient. If the wavelength of light far exceeds the particle dimensions, the particles can be treated as electric dipoles in an electric field. For optical trapping of dielectric objects of dimensions within an order of magnitude of the trapping beam wavelength, the only accurate models involve the treatment of either time dependent or time harmonic Maxwell equations using appropriate boundary conditions. | 1 | Applied and Interdisciplinary Chemistry |
In polymer chemistry, the kinetic chain length () of a polymer is the average number of units called monomers added to a growing chain during chain-growth polymerization. During this process, a polymer chain is formed when monomers are bonded together to form long chains known as polymers. Kinetic chain length is defined as the average number of monomers that react with an active center such as a radical from initiation to termination.
This definition is a special case of the concept of chain length in chemical kinetics. For any chemical chain reaction, the chain length is defined as the average number of times that the closed cycle of chain propagation steps is repeated. It is equal to the rate of the overall reaction divided by the rate of the initiation step in which the chain carriers are formed. For example, the decomposition of ozone in water is a chain reaction which has been described in terms of its chain length.
In chain-growth polymerization the propagation step is the addition of a monomer to the growing chain. The word kinetic is added to chain length in order to distinguish the number of reaction steps in the kinetic chain from the number of monomers in the final macromolecule, a quantity named the degree of polymerization. In fact the kinetic chain length is one factor which influences the average degree of polymerization, but there are other factors as described below. The kinetic chain length and therefore the degree of polymerization can influence certain physical properties of the polymer, including chain mobility, glass-transition temperature, and modulus of elasticity. | 0 | Theoretical and Fundamental Chemistry |
The p-toluene-sulfinyl imines have been used for the highly diastereoselective asymmetric synthesis of α-amino acids, β-amino acids, syn- and anti-2,3-diamino esters, α-amino aldehydes and ketones, β-amino ketones, α-amino phosphonates, aziridine 2-carboxylates, and aziridine 2-phosphonates. Many of these same transformations can be carried out with tert-butylsulfinyl imines. For the asymmetric synthesis of amines, tert-butylsulfinyl imines are required as lithium and Grignard reagents react at the sulfinyl sulfur in p-toluene-sulfinyl imines. Mild acid treatment readily removes the N-sulfinyl group in the sulfinamide products affording the free amine derivatives. An advantage of tert-butylsulfinyl imines is that acid treatment of the corresponding sulfinamides leads to easily removal by-products | 0 | Theoretical and Fundamental Chemistry |
Acid–base titration plays a crucial role in environmental monitoring by providing a quantitative analytical method for assessing the acidity or alkalinity of water samples. The measurement of parameters such as pH, total alkalinity, and acidity is essential in evaluating the environmental impact of industrial discharges, agricultural runoff, and other sources of water contamination.
Acid–base titration allows for the determination of the buffering capacity of natural water systems, aiding in the assessment of their ability to resist changes in pH. Monitoring pH levels is important for preserving aquatic ecosystems and ensuring compliance with environmental regulations.
Acid–base titration is also utilized in the analysis of acid rain effects on soil and water bodies, contributing to the overall understanding and management of environmental quality. The method's prevision and reliability make it a valuable tool in safeguarding ecosystems and assessing the impact of human activities on natural water resources. | 0 | Theoretical and Fundamental Chemistry |
When a synonymous or silent mutation occurs, the change is often assumed to be neutral, meaning that it does not affect the fitness of the individual carrying the new gene to survive and reproduce.
Synonymous changes may not be neutral because certain codons are translated more efficiently (faster and/or more accurately) than others. For example, when a handful of synonymous changes in the fruit fly alcohol dehydrogenase gene were introduced, changing several codons to sub-optimal synonyms, production of the encoded enzyme was reduced and the adult flies showed lower ethanol tolerance.
Many organisms, from bacteria through animals, display biased use of certain synonymous codons. Such codon usage bias may arise for different reasons, some selective, and some neutral. In Saccharomyces cerevisiae synonymous codon usage has been shown to influence mRNA folding stability, with mRNA encoding different protein secondary structure preferring different codons.
Another reason why synonymous changes are not always neutral is the fact that exon sequences close to exon-intron borders function as RNA splicing signals. When the splicing signal is destroyed by a synonymous mutation, the exon does not appear in the final protein. This results in a truncated protein. One study found that about a quarter of synonymous variations affecting exon 12 of the cystic fibrosis transmembrane conductance regulator gene result in that exon being skipped. | 1 | Applied and Interdisciplinary Chemistry |
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