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Another aspect that ecosan systems are trying to address is the possible upcoming shortage of phosphorus. Phosphorus has an important role for plant growth, and therefore in fertilizer production, but is a limited mineral resource. The situation is similar for potassium. Known mineral phosphate rock reserves are becoming scarce and increasingly costly to extract – this is also called the "peak phosphorus" crisis. One review of global phosphate supply suggested that if collected, phosphate in urine could supply 22% of the total demand. | 1 | Applied and Interdisciplinary Chemistry |
Thyroids secretory capacity (G, also referred to as SPINA-GT) is the maximum stimulated amount of thyroxine the thyroid can produce in one second. G' is elevated in hyperthyroidism and reduced in hypothyroidism.
G is calculated with
or
: Dilution factor for T4 (reciprocal of apparent volume of distribution, 0.1 l)<br />
: Clearance exponent for T4 (1.1e-6 sec)<br />
K: Dissociation constant T4-TBG (2e10 L/mol)<br />
K: Dissociation constant T4-TBPA (2e8 L/mol)<br />
D: EC for TSH (2.75 mU/L) | 1 | Applied and Interdisciplinary Chemistry |
N(6)-Carboxymethyllysine (CML), also known as N-(carboxymethyl)lysine, is an advanced glycation endproduct (AGE). CML has been the most used marker for AGEs in food analysis.
Recently, it has been demonstrated that gut microbiota mediates an aging-associated decline in gut barrier function, allowing AGEs to leak into the bloodstream from the gut and impairing microglial function in the brain. It is suggested that the amount of CML in human blood samples may correlated with age.
A humanized monoclonal antibody which binds to N6 – carboxymethyl lysine shows considerable promise as a possible therapeutic agent for treating pancreatic cancer. | 1 | Applied and Interdisciplinary Chemistry |
Ravi Bhushan (born 12 April 1953, in Muzaffarnagar, India) was a Professor of Chemistry at Indian Institute of Technology Roorkee who worked in the areas of natural products chemistry, protein chemistry, and chiral analysis by liquid chromatography. | 0 | Theoretical and Fundamental Chemistry |
The European Bioanalysis Forum (EBF) is an organisation comprising bioanalytical scientists working within the pharmaceutical industry R&D. Scope of the EBF is on bioanalysis of small and large molecules with bioanalysis being defined as:
* Quantification of drugs and metabolites in body fluids and tissues
* Quantification of PD and safety biomarkers amenable to conventional bioanalytical techniques
* Bioanalytical characterization of NBEs
Members discuss on regulatory issues and aspects (new guidelines, interpretation of existing guidelines) and present their joint opinion towards regulatory bodies and their peers. Further, they share common practices on procedures, science, Laboratory Information Management Systems (LIMS), validation, quality (GLP) and discuss new developments in industry. | 0 | Theoretical and Fundamental Chemistry |
Solid phosphorus pentachloride is an ionic compound, formulated , that is, a salt containing the tetrachlorophosphonium cation. Dilute solutions dissociate according to the following equilibrium:
:PCl + Cl
Triphenylphosphine dichloride (PhPCl) exists both as the pentacoordinate phosphorane and as the chlorotriphenylphosphonium chloride, depending on the medium. The situation is similar to that of PCl. It is an ionic compound (PPhCl)Cl in polar solutions and a molecular species with trigonal bipyramidal molecular geometry in apolar solution. | 0 | Theoretical and Fundamental Chemistry |
He was born October 29, 1870. Owens was a graduate of the Industrial College of Johns Hopkins University and Columbia University.
On August 19, 1891 he was employed as an adjunct professor in electrical engineering in the newly formed school of Electrical Engineering at the University of Nebraska. After seven years of service he left the now-department in shape comparable to other universities of the time, in August 1898, Owens took a position as MacDonald Chair of Electrical Engineering at McGill University in Montreal.
During his time at Nebraska, Owens was involved in forming The Society of Electrical Engineers of the University of Nebraska in 1893, the body which is known today as the IEEE.
Owens served as an officer in World War I, alongside General John J. Pershing.
He died on November 3, 1940. | 1 | Applied and Interdisciplinary Chemistry |
As with all explosives, research into control yet simplicity has been a goal of research into nanoscale explosives. Some can be ignited with laser pulses.
MICs have been investigated as a possible replacement for lead (e.g. lead styphnate, lead azide) in percussion caps and electric matches. Compositions based on Al-BiO tend to be used. PETN may be optionally added.
Aluminium powder can be added to nano explosives. Aluminium has a relatively low combustion rate and a high enthalpy of combustion.
The products of a thermite reaction, resulting from ignition of the nano-thermitic mixture, are usually metal oxides and elemental metals. At the temperatures prevailing during the reaction, the products can be solid, liquid or gaseous, depending on the components of the mixture. | 0 | Theoretical and Fundamental Chemistry |
Thiomers are capable of forming disulfide bonds with cysteine substructures of the mucus gel layer covering mucosal membranes. Because of this property they exhibit up to 100-fold higher mucoadhesive properties in comparison to the corresponding unthiolated polymers. Because of their mucoadhesive properties, thiolated polymers are an effective tool in the treatment of diseases such as dry eye, dry mouth, and dry vagina syndrome where dry mucosal surfaces are involved. | 0 | Theoretical and Fundamental Chemistry |
In the eyes of a variety of modern esoteric and Neo-Hermetic practitioners, alchemy is primarily spiritual. In this interpretation, transmutation of lead into gold is presented as an analogy for personal transmutation, purification, and perfection.
According to this view, early alchemists such as Zosimos of Panopolis () highlighted the spiritual nature of the alchemical quest, symbolic of a religious regeneration of the human soul. This approach is held to have continued in the Middle Ages, as metaphysical aspects, substances, physical states, and material processes are supposed to have been used as metaphors for spiritual entities, spiritual states, and, ultimately, transformation. In this sense, the literal meanings of Alchemical Formulas hid a spiritual philosophy. In the Neo-Hermeticist interpretation, both the transmutation of common metals into gold and the universal panacea are held to symbolize evolution from an imperfect, diseased, corruptible, and ephemeral state toward a perfect, healthy, incorruptible, and everlasting state, so the philosopher's stone then represented a mystic key that would make this evolution possible. Applied to the alchemist, the twin goal symbolized their evolution from ignorance to enlightenment, and the stone represented a hidden spiritual truth or power that would lead to that goal. In texts that are believed to have been written according to this view, the cryptic alchemical symbols, diagrams, and textual imagery of late alchemical works are supposed to contain multiple layers of meanings, allegories, and references to other equally cryptic works; which must be laboriously decoded to discover their true meaning.
In his 1766 Alchemical Catechism, Théodore Henri de Tschudi suggested that the usage of the metals was symbolic: | 1 | Applied and Interdisciplinary Chemistry |
In systems that have a media with significant particulate content (i.e. flash or catalyst), a barrier of ceramic fiber can be utilized to prevent corrosion and restricted bellows flexibility resulting from the accumulation of the particulate. Purge connectors may also be utilized to perform this same function. Internal liners must also be included in the design if the expansion joint includes purge connectors or particulate barriers. | 1 | Applied and Interdisciplinary Chemistry |
The term is used in pathology, for example in calcareous conjunctivitis, and when referring to calcareous metastasis or calcareous deposits, which may both be removed surgically. | 0 | Theoretical and Fundamental Chemistry |
Four chemical processes contribute to industrial benzene production: catalytic reforming, toluene hydrodealkylation, toluene disproportionation, and steam cracking etc. According to the ATSDR Toxicological Profile for benzene, between 1978 and 1981, catalytic reformates accounted for approximately 44–50% of the total U.S. benzene production. | 1 | Applied and Interdisciplinary Chemistry |
The information available about the people of the Copper Age has not substantially increased along with the number of archaeological sites. Several ideas have been proffered, one of the most followed is that the metal itself did not bring abrupt transformation into the people's life, or even more that early copper does not produce anything useful at all, meaning with this that with the copper, they produced mainly jewellery and, overall, weapons that obviously were not within reach of the majority of the population but only to privileged individuals. In other words, the real importance of the metal is not utilitarian but social. This is a suitable explanation about the rising of Great Cultures of Metal such as Vinča culture (Ex-Yugoslavia) Tiszapolgar and Unetice culture (Central Europe), Remedello and Rinaldone (Italy), Montagne Noire (France), El Argar and Targas (Spain), etc.
As the period moved forward, especially around the 3rd millennium, new and complex realities would appear strongly linked to the metal, like the impressive fortified villages of Los Millares (Spain), Vila Nova de Sao Pedro (Portugal) or the more modest cairn next to Copa Hill in the United Kingdom destinated to control the centres of extraction, or the equally and generalized cultural phenomenons of Megalithism, Rock Art, Bell Beakers Vessels that are known from Scandinavia to the South of Spain and from Scotland to Turkey. | 1 | Applied and Interdisciplinary Chemistry |
The method of Fourier-transform spectroscopy can also be used for absorption spectroscopy. The primary example is "FTIR Spectroscopy", a common technique in chemistry.
In general, the goal of absorption spectroscopy is to measure how well a sample absorbs or transmits light at each different wavelength. Although absorption spectroscopy and emission spectroscopy are different in principle, they are closely related in practice; any technique for emission spectroscopy can also be used for absorption spectroscopy. First, the emission spectrum of a broadband lamp is measured (this is called the "background spectrum"). Second, the emission spectrum of the same lamp shining through the sample is measured (this is called the "sample spectrum"). The sample will absorb some of the light, causing the spectra to be different. The ratio of the "sample spectrum" to the "background spectrum" is directly related to the sample's absorption spectrum.
Accordingly, the technique of "Fourier-transform spectroscopy" can be used both for measuring emission spectra (for example, the emission spectrum of a star), and absorption spectra (for example, the absorption spectrum of a liquid). | 0 | Theoretical and Fundamental Chemistry |
Anumāna (inference) is one of the most important contributions of the Nyāya. It can be of two types: inference for oneself (Svarthanumana, where one does not need any formal procedure, and at the most the last three of their 5 steps), and inference for others (Parathanumana, which requires a systematic methodology of 5 steps). Inference can also be classified into 3 types: Purvavat (inferring an unperceived effect from a perceived cause), Sheshavat (inferring an unperceived cause from a perceived effect) and Samanyatodrishta (when inference is not based on causation but on uniformity of co-existence). A detailed analysis of error is also given, explaining when anumana could be false. | 1 | Applied and Interdisciplinary Chemistry |
Although the presence of carbon in the Earths core is well-constrained, recent studies suggest large inventories of carbon could be stored in this region. Shear (S) waves moving through the inner core travel at about fifty percent of the velocity expected for most iron-rich alloys. Considering the cores composition is widely believed to be an alloy of crystalline iron with a small amount of nickel, this seismographic anomaly points to another substances existence within the region. One theory postulates that such a phenomenon is the result of various light elements, including carbon, in the core. In fact, studies have utilised diamond anvil cells to replicate the conditions in the Earths core, the results of which indicate that iron carbide (FeC) matches the inner cores sound and density velocities considering its temperature and pressure profile. Hence, the iron carbide model could serve as evidence that the core holds as much as 67% of the Earths carbon. Furthermore, another study found that carbon dissolved in iron and formed a stable phase with the same FeC composition—albeit with a different structure than the one previously mentioned. Hence, although the amount of carbon potentially stored in the Earth's core is not known, recent research indicates that the presence of iron carbides could be consistent with geophysical observations. | 0 | Theoretical and Fundamental Chemistry |
* (mol/s)/(m·mol/m) = m/s
Note, the units will vary based upon which units the driving force is expressed in. The driving force shown here as is expressed in units of moles per unit of volume, but in some cases the driving force is represented by other measures of concentration with different units. For example, the driving force may be partial pressures when dealing with mass transfer in a gas phase and thus use units of pressure. | 1 | Applied and Interdisciplinary Chemistry |
The test had 85 multiple choice questions, each consisting of five answer choices, that were to be answered in one hour. Students received 1 point for every correct answer, lost ¼ of a point for each incorrect answer, and received 0 points for questions left blank. This score was then converted to a scaled score of 200-800. The mean score for the 2009 test administrations was 638, standard deviation 113. In 2011, the mean score was 648 with a standard deviation of 110. | 1 | Applied and Interdisciplinary Chemistry |
The earliest study on the relationship between contact angle and surface tensions for sessile droplets on flat surfaces was reported by Thomas Young in 1805. A century later Gibbs proposed a modification to Young's equation to account for the volumetric dependence of the contact angle. Gibbs postulated the existence of a line tension, which acts at the three-phase boundary and accounts for the excess energy at the confluence of the solid-liquid-gas phase interface, and is given as:
where is the line tension in Newtons and is the droplet radius in meters. Although experimental data validates an affine relationship between the cosine of the contact angle and the inverse line radius, it does not account for the correct sign of and overestimates its value by several orders of magnitude. | 0 | Theoretical and Fundamental Chemistry |
Using the technique of flash photolysis with the compound diazomethane,
Gerhard Herzberg and Jack Shoosmith
were the first to
produce and spectroscopically characterize the methylene molecule. In their work they obtained
the ultraviolet spectrum of gas phase methylene at around 141.5 nm. Their
analysis of the spectrum lead them to the conclusion that the ground electronic state was an
electronic triplet state and that the equilibrium structure was either linear, or else it had
a large bond angle of about 140°. It turns out that the latter is correct. The reactions of methylene were also studied around 1960, by infrared spectroscopy in frozen gas matrix isolation experiments.
Methylene can be prepared, under suitable conditions, by decomposition of compounds with a methylidene or methanediyl group, such as ketene (ethenone) (=CO), diazomethane (linear =), diazirine (cyclic [--N=N-]) and diiodomethane (I--I). The decomposition can be effected by photolysis, photosensitized reagents (such as benzophenone), or thermal decomposition.
The methylene molecule (CH) was mentioned for the first time by Donald Duck in a comic in 1944. | 0 | Theoretical and Fundamental Chemistry |
Despite its popularity, form-based restoration has been criticized by the scientific community. Common criticisms are that the scale at which form-based restoration is often much smaller than the spatial and temporal scales of the processes that cause the observed problems and that the target state is frequently influenced by the social conception of what a stream should look like and does not necessarily take into account the streams geomorphological context (e.g., meandering rivers tend to be viewed as more "natural" and more beautiful, whereas local conditions sometimes favour other patterns such as braided rivers). Numerous criticisms have also been directed at the NCD method by fluvial geomorphologists, who claim that the method is a "cookbook" approach sometimes used by practitioners that do not have sufficient knowledge of fluvial geomorphology, resulting in project failures. Another criticism is the importance given to channel stability in the NCD method (and with some other form-based restoration methods), which can limit the streams alluvial dynamic and adaptability to evolving conditions. The NCD method has been criticized for its improper application in the Washington, D.C. area to small-order, interior-forested, upper-headwater streams and wetlands, leading to loss of natural forest ecosystems. | 1 | Applied and Interdisciplinary Chemistry |
In chemical separation processes, an Energy separating agent (ESA) is the heat or shaft work added to facilitate the separation of two chemical species. It is contrasted with a mass separating agent, which is any chemical species added to the reaction that facilitates the reaction. ESAs are used in many common separation procedures.
Some important examples of procedures utilizing ESAs are vaporization (heat added), distillation (heat added), crystallization (heat evolved), and stripping (heat added). | 1 | Applied and Interdisciplinary Chemistry |
In 1969, one such method was performed by Mary Lou Pardue and Joseph G. Gall at the Yale University through radioactivity where it involved the hybridization of a radioactive test DNA in solution to the stationary DNA of a cytological preparation, which is identified as autoradiography. | 1 | Applied and Interdisciplinary Chemistry |
AKT is downstream to PI3K and is inhibited by Ipatasertib. Akt is an AGC-family kinase and a central, integral signaling node of the PAM pathway. There are three Akt isozymes, Akt1, Akt2 and Akt3. Small-molecule inhibitors of Akt1 could be especially useful to target tumors with a high prevalence of Akt1 E17K activating mutations, which is observed in 4–6% of breast cancers and 1–2% of colorectal cancer. Research towards Akt inhibition has focused on inhibition of two distinct binding sites:
* the allosteric pocket of the inactive enzyme, and
* the ATP binding site.
Allosteric Akt inhibitors, highlighted by MK-2206, have been extensively evaluated in a clinical setting; Recently, additional allosteric Akt inhibitors have been identified. ARQ-092, is a potent pan-Akt inhibitor which can inhibit tumor growth preclinically and is currently in Phase I clinical studies. | 1 | Applied and Interdisciplinary Chemistry |
1,2,3-Cyclohexatriene is an unstable chemical compound with the molecular formula . It is an unusual isomer of benzene in which the three double bonds are cumulated.
In 1990, 1,2,3-cyclohexatriene was first prepared by reacting a cyclohexadiene derivative with cesium fluoride. The product was too reactive to be isolated on its own, so its existence was confirmed by trapping via a cycloaddition reaction.
1,2,3-Cyclohexatriene and its derivatives undergo a variety of reactions including cycloadditions, nucleophilic additions, and σ-bond insertions, and therefore they can be versatile reagents for organic synthesis. | 0 | Theoretical and Fundamental Chemistry |
The above method is sufficient for finding the overall depth of rainfall during a storm. However, it is often useful from an engineering perspective to predict the intensity of rainfall during the storm, to allow structures such as drains and sewers to be designed with sufficient capacity for stormwater.
In general, the intensity of a storm is highest at the mid-duration point (known as the peak), and lowest at the start and end of the storm. Therefore, peaked profiles are applied to the storm data to provide a more realistic description of the rainfall intensity during the storm. | 1 | Applied and Interdisciplinary Chemistry |
Cyanosulfidic prebiotic synthesis is a proposed mechanism for the origin of the key chemical building blocks of life. It involves a systems chemistry approach to synthesize the precursors of amino acids, ribonucleotides, and lipids using the same starting reagents and largely the same plausible early Earth conditions. Cyanosulfidic prebotic synthesis was developed by John Sutherland and co-workers at the Laboratory of Molecular Biology in Cambridge, England. | 0 | Theoretical and Fundamental Chemistry |
The experimental set-up used to carry out UV-Vis absorption SEC measurements depends on the chosen configuration and the characteristics of the analyte. The experimental set-up is composed of a light source, a spectrometer, a potentiostat/galvanostat, a SEC cell, a three-electrode system, optical elements to conduct the light beam, and a computer for data collection and analysis. Currently, there are commercial devices that integrate all these elements in a single instrument, simplifying significantly the SEC experiments.
* Light source: provides the electromagnetic radiation that interacts with the sample while the electrochemical process is taking place. A specific source is required for the UV-Vis spectral region, being the most common the deuterium/halogen lamp.
* Spectrometer: instrument that allows measuring the properties of the light in a certain region of the electromagnetic spectrum. It uses a monochromator to separate the different spectral wavelengths of interest emitted by the light source. A diode-array detector can be used to obtain time-resolved spectra. For UV-Vis spectroelectrochemistry, spectrometer must be specific for UV-Vis spectral region.
* Potentiostat/Galvanostat: electronic device that allows controlling the working electrode potential regarding to the reference electrode or controlling the current that passes respect to the auxiliary electrode.
* Three electrode system: consists of a working electrode, a reference electrode and an auxiliary electrode. This system can be simplified by using screen-printed electrodes that include the three electrodes on a single holder.
* Spectroelectrochemical cell: device in which the solution and the system of three electrodes is located, avoiding possible interference in the optical path. It is the link between the electrochemistry and the UV-Vis absorption spectroscopy.
* Devices to conduct the radiation beam: lenses, mirrors and/or optical fibers. The last ones conduct electromagnetic radiation over great distances with hardly any losses. In addition, they simplify the optical configurations because they allow working with a small amount of solution. Optical fibers make easier to conduct and collect light near the electrode.
* Analysis and data collection devices: a computer collects the signals provided by the spectrometer and potentiostat that, using a suitable software, treats, analyzes and interprets the signals. | 0 | Theoretical and Fundamental Chemistry |
In eukaryotic somatic cells, the poly(A) tails of most mRNAs in the cytoplasm gradually get shorter, and mRNAs with shorter poly(A) tail are translated less and degraded sooner. However, it can take many hours before an mRNA is degraded. This deadenylation and degradation process can be accelerated by microRNAs complementary to the 3′ untranslated region of an mRNA. In immature egg cells, mRNAs with shortened poly(A) tails are not degraded, but are instead stored and translationally inactive. These short tailed mRNAs are activated by cytoplasmic polyadenylation after fertilisation, during egg activation.
In animals, poly(A) ribonuclease (PARN) can bind to the 5′ cap and remove nucleotides from the poly(A) tail. The level of access to the 5′ cap and poly(A) tail is important in controlling how soon the mRNA is degraded. PARN deadenylates less if the RNA is bound by the initiation factors 4E (at the 5′ cap) and 4G (at the poly(A) tail), which is why translation reduces deadenylation. The rate of deadenylation may also be regulated by RNA-binding proteins. Additionally, RNA triple helix structures and RNA motifs such as the poly(A) tail 3’ end binding pocket retard deadenylation process and inhibit poly(A) tail removal. Once the poly(A) tail is removed, the decapping complex removes the 5′ cap, leading to a degradation of the RNA. Several other proteins are involved in deadenylation in budding yeast and human cells, most notably the CCR4-Not complex. | 1 | Applied and Interdisciplinary Chemistry |
Many model organism, such as plants (Arabidopsis thaliana), yeast (Saccharomyces cerevisiae ), flies (Drosophila melanogaster) and worms (C. elegans), have been used to study small non coding RNA-directed Transcriptional gene silencing. In human cell, RNA-directed transcriptional gene silencing was observed a decade ago when exogenous siRNAs silenced a transgenic elongation factor 1 α promoter driving a Green Fluorescent Protein (GFP) reporter gene.
The main mechanisms of transcriptional gene silencing (TGS) involving the RNAi machinery include DNA methylation, histone post-translational modifications, and subsequent chromatin remodeling around the target gene into a heterochromatic state.
SiRNAs can be incorporated into a RNA-induced transcriptional silencing (RITS) complex. An active RITS complex will trigger the formation of heterochromatin around DNA matching the siRNA, effectively silencing the genes in that region of the DNA. | 1 | Applied and Interdisciplinary Chemistry |
The tables below present an example of an artificial seawater (35.00‰ of salinity) preparation devised by Kester, Duedall, Connors and Pytkowicz (1967). The recipe consists of two lists of mineral salts, the first of anhydrous salts that can be weighed out, the second of hydrous salts that should be added to the artificial seawater as a solution.
While all of the compounds listed in the recipe above are inorganic, mineral salts, some artificial seawater recipes, such as Goldman and McCarthy (1978), make use of trace solutions of vitamins or organic compounds. | 0 | Theoretical and Fundamental Chemistry |
The majority of rivers on the planet and many lakes have received or are receiving inputs from human-kind's activities. In the industrialised world, many rivers have been very seriously polluted, at least during the 19th and the first half of the 20th centuries. Although in general there has been much improvement in the developed world, there is still a great deal of river pollution apparent on the planet. | 1 | Applied and Interdisciplinary Chemistry |
A very rare type of ternary fission process is sometimes called "true ternary fission." It produces three nearly equal-sized charged fragments (Z ~ 30) but only happens in about 1 in 100 million fission events. In this type of fission, the product nuclei split the fission energy in three nearly equal parts and have kinetic energies of ~ 60 MeV. True ternary fission has so far only been observed in nuclei bombarded by heavy, high energy ions. | 0 | Theoretical and Fundamental Chemistry |
Neuromuscular blocking agents need to fit in a space close to 2 nanometres, which resembles the molecular length of decamethonium. Some molecules of decamethonium congeners may bind only to one receptive site. Flexible molecules have a greater chance of fitting receptive sites. However, the most populated conformation may not be the best-fitted one. Very flexible molecules are, in fact, weak neuromuscular inhibitors with flat dose-response curves. On the other hand, stiff or rigid molecules tend to fit well or not at all. If the lowest-energy conformation fits, the compound has high potency because there is a great concentration of molecules close to the lowest-energy conformation. Molecules can be thin but yet rigid. Decamethonium for example needs relatively high energy to change the N-N distance.
In general, molecular rigidity contributes to potency, while size affects whether a muscle relaxant shows a polarizing or a depolarizing effect. Cations must be able to flow through the trans-membrane tube of the ion-channel to depolarize the endplate. Small molecules may be rigid and potent but unable to occupy or block the area between the receptive sites. Large molecules, on the other hand, may bind to both receptive sites and hinder depolarizing cations independent of whether the ion-channel is open or closed below. Having a lipophilic surface pointed towards the synapse enhances this effect by repelling cations. The importance of this effect varies between different muscle relaxants and classifying depolarizing from non-depolarizing blocks is a complex issue. The onium heads are usually kept small and the chains connecting the heads usually keep the N-N distance at 10 N or O atoms. Keeping the distance in mind the structure of the chain can vary (double bonded, cyclohexyl, benzyl, etc.)
Succinylcholine has a 10-atom distance between its N atoms, like decamethonium. Yet it has been reported that it takes two molecules, as with acetylcholine, to open one nicotinic ion channel. The conformational explanation for this is that each acetylcholine moiety of succinylcholine prefers the gauche (bent, cis) state. The attraction between the N and O atoms is greater than the onium head repulsion. In this most populated state, the N-N distance is shorter than the optimal distance of ten carbon atoms and too short to occupy both receptive sites. This similarity between succinyl- and acetyl-choline also explains its acetylcholine-like side-effects.
Comparing molecular lengths, the pachycurares dimethyltubocurarine and d-tubocurarine both are very rigid and measure close to 1.8 nm in total length. Pancuronium and vecuronium measure 1.9 nm, whereas pipecuronium is 2.1 nm. The potency of these compounds follows the same rank of order as their length. Likewise, the leptocurares prefer a similar length. Decamethonium, which measures 2 nm, is the most potent in its category, whereas C11 is slightly too long. Gallamine despite having low bulk and rigidity is the most potent in its class, and it measures 1.9 nm. Based on this information one can conclude that the optimum length for neuromuscular blocking agents, depolarizing or not, should be 2 to 2.1 nm.
The CAR for long-chain bisquaternary tetrahydroisoquinolines like atracurium, cisatracurium, mivacurium, and doxacurium is hard to determine because of their bulky onium heads and large number of rotatable bonds and groups. These agents must follow the same receptive topology as others, which means that they do not fit between the receptive sites without bending. Mivacurium for example has a molecular length of 3.6 nm when stretched out, far from the 2 to 2.1 nm optimum. Mivacurium, atracurium, and doxacurium have greater N-N distance and molecular length than d-tubocurarine even when bent. To make them fit, they have flexible connections that give their onium heads a chance to position themselves beneficially. This bent N-N scenario probably does not apply to laudexium and decamethylene bisatropium, which prefer a straight conformation. | 1 | Applied and Interdisciplinary Chemistry |
In chemistry, recrystallization is a procedure for purifying compounds. The most typical situation is that a desired "compound A" is contaminated by a small amount of "impurity B". There are various methods of purification that may be attempted (see Separation process), recrystallization being one of them. There are also different recrystallization techniques that can be used such as: | 0 | Theoretical and Fundamental Chemistry |
Al-Rāzī mentions the following chemical processes: distillation, calcination, solution, evaporation, crystallization, sublimation, filtration, amalgamation, and ceration (a process for making solids pasty or fusible.) Some of these operations (calcination, solution, filtration, crystallization, sublimation and distillation) are also known to have been practiced by pre-Islamic Alexandrian alchemists.
In his Secretum secretorum, Al-Rāzī mentions the following equipment:
* Tools for melting substances (li-tadhwīb): hearth (kūr), bellows (minfākh or ziqq), crucible (bawtaqa), the būt bar būt (in Arabic, from Persian) or botus barbatus (in Latin), ladle (mighrafa or milʿaqa), tongs (māsik or kalbatān), scissors (miqṭaʿ), hammer (mukassir), file (mibrad).
* Tools for the preparation of drugs (li-tadbīr al-ʿaqāqīr): cucurbit and still with evacuation tube (qarʿ or anbīq dhū khatm), receiving matras (qābila), blind still (without evacuation tube) (al-anbīq al-aʿmā), aludel (al-uthāl), goblets (qadaḥ), flasks (qārūra, plural quwārīr), rosewater flasks (mā’ wardiyya), cauldron (marjal or tanjīr), earthenware pots varnished on the inside with their lids (qudūr and makabbāt), water bath or sand bath (qidr), oven (al-tannūr in Arabic, athanor in Latin), small cylindirical oven for heating aludel (mustawqid), funnels, sieves, filters, etc. | 1 | Applied and Interdisciplinary Chemistry |
Iimori translated "Isotope" into Japanese as "Doi-genso". Isotope is the concept delivered in Soddy's lecture at the London Chemical Conference in 1918. The lecture was introduced in 1919 at the meeting of chemical laboratory of Tokyo Imperial University, where Iimori proposed to translate the word as " doi genso" in Japanese and it was assented immediately. | 0 | Theoretical and Fundamental Chemistry |
There are broad general methodologies used to calculate the density of a liquid at specific conditions. In order to discuss a specific methodology, one must choose a liquid that holds sufficient interest to warrant a calculation specific to it. EOS 87.3 is a density calculation for seawater; API chapter 11 specifies calculations pertaining to oil, fuels and natural gas liquids. | 1 | Applied and Interdisciplinary Chemistry |
Diazenes may extrude nitrogen to provide discrete TMM intermediates. Generally, bridged diazenes are used to avoid competitive closure to MCPs and dimerization reactions. In combination with an alkenic acceptor, cyclization to either fused or bridged products takes place. Fused products are generally favored, unless the diazene precursor is substituted with electron-donating groups at the methylene carbon atom. The configuration of the alkene is maintained as long as the reaction is proceeding through a singlet TMM.
When stabilizing groups are present, MCPs may open to the corresponding zwitterionic TMMs. Acetal 1 has been used in this context, and provides cyclopentanes with the acetal functionality exo to the newly formed ring with high selectivity. This reaction is also stereospecific with respect to alkene geometry, and exhibits high selectivity for endo products in most cases.
MCPs lacking stabilizing groups may generate TMM synthons in the presence of palladium(0) or nickel(0) catalysts. Formal insertion of the catalyst into either of the two chemically distinct cyclopropane bonds (called "distal" and "proximal" to reflect their distance from the double bond) has the potential to generate isomeric products. Generally, palladium catalysts cause formal distal bond cleavage. This process is believed to occur through direct attack of the distal bond on the coordinated alkene. The reaction is stepwise and lacks stereospecificity under both palladium and nickel catalysis.
Silylated allylic acetates, carbonates and other substituted allyl compounds may form TMM synthons under palladium catalysis. The reaction is highly regioselective, providing only the substitution pattern shown below regardless of the position of the R' group on the starting allylic acetate. However, cyclization takes place in a stepwise fashion and does not exhibit stereospecificity. Rapid racemization of chiral pi-allyl palladium complexes occurs, and only moderate diastereoselectivity is observed in reactions of chiral allylic acetates. Chiral non-racemic alkenes, however, may exhibit moderate to high diastereoselectivity. | 0 | Theoretical and Fundamental Chemistry |
In electronic spectroscopy, constructing a Deslandres table is a useful method to assign vibronic transitions. In such a table, the frequencies of the lines seen in an electronic spectrum of a molecule are collected so that the differences in energy between adjacent columns or rows are all the same (within experimental error). Every line seen in the spectrum corresponds to a transition from the lower-lying electronic energy state to an excited electronic state (molecular electronic transition): associated with this, there are corresponding transitions between the vibrational levels of the two states, that give rise to many closely spaced lines. The intensity of the lines is governed by the Franck–Condon principle.
When a Deslandres table is filled correctly, the columns represent the vibrational energy levels of the lower electronic state (v), while the rows represent those for the upper electronic state (v). Clearly, the difference in energy between two successive rows (columns) must remain constant for any column (row) in the table because this represents the energy difference of two given vibrational levels within the same electronic state. Thus, by completing a Deslandres table it is easy to assign the correct vibrational quantum numbers v and v for the transition, allowing important molecular properties to be calculated, such as the dissociation energy. | 0 | Theoretical and Fundamental Chemistry |
Tetsuo Nozoe was born on 16 May 1902 in Sendai to Juichi Nozoe, a lawyer and one-time member of the National Diet, and Toyo Nozoe. Tetsuo's family was Buddhist except of his mother who was a devout Christian. Tetsuo had three sisters and seven brothers, and he was the sixth child in the family. He started doing chemical experiments at home since his junior high school days. Although his parents wanted him to become a medical doctor, and even sent him for premedical classes, he proceeded his education with chemistry. After graduating from high school in Sendai, he entered the Department of Chemistry at Tohoku Imperial University in 1920. In university, he studied organic chemistry under Riko Majima, a leading scientist in organic chemistry in Japan.
In 1926, after graduation he moved to Taihoku, Formosa , where he started working as a researcher at the Camphor Research Laboratories of the Monopoly Bureau and then at the Department of Chemical Industry of the Central Research Institute, both under Government-General of Taipei. In Formosa, Tetsuo was studying the structures of natural compounds, such as saponins, sapogins, sapogenins, triterpenoids and glycosides, especially in plants found locally. In 1937, with the help of ultraviolet–visible spectroscopy he predicted the correct structures for oleanolic acid and hederagenin, common sapogenins. In the same year he became a professor of chemistry at Taihoku Imperial University. The scope of his research in those times included also studying constituents of wool wax and those of other animal skin waxes. He discovered lanolinic acids and agnolinic acids, groups of unusual branched chain fatty acids.
One of the most popular works of Tesuo Nozoe was the research on the chemical constituents of taiwanhinoki (Chamaecyparis taiwanensis, Taiwan cypress), a coniferous tree native to Taiwan. The natural resistance of this and other tree species belonging to Cupressaceae family to fungal wood decay prompted Japanese researchers to study the chemical components of these trees. Nenokichi Hirao, a Japanese chemist, derived a dark-red pigment from hinoki oil and called hinokitin in 1926. Tetsos research led to discovery of a new series of chemical compounds, non-benzoniod aromatic compounds, including hinokitiol. He obtained hinokitiol from hinokitin, and showed that hinokitin is an iron complex of hinokitiol, (CHO)Fe. It was first published in 1936 in a special issue of the Bulletin of the Chemical Society of Japan. After three more years of work in Formosa following the World War II, Tetsuo returned to Japan. As a professor at Tohoku University, he continued his work on hinokitiol. Later in 1948, Holger Erdtman, a Scottish organic chemist, reported isolation of three isomeric monoterpenoids (α-, β-, and γ-thujaplicin) from Thuja plicata (Western red cedar) in his paper published in Nature. After correspondence, both Tetsuo and Holger found that hinokitiol is identical to β-thujaplicin and has a tropolone structure. Tetsuo Nozoe and Holger Erdtman became lifelong friends. In 1951, Nozoe got an opportunity to publish his work on hinokitiol and its derivatives in Nature'. He also studied chemical characteristics of tropones, tropolones, other troponoids, and azulenes. | 0 | Theoretical and Fundamental Chemistry |
In electrochemistry, a thermogalvanic cell is a kind of galvanic cell in which heat is employed to provide electrical power directly. These cells are electrochemical cells in which the two electrodes are deliberately maintained at different temperatures. This temperature difference generates a potential difference between the electrodes. The electrodes can be of identical composition and the electrolyte solution homogeneous. This is usually the case in these cells. This is in contrast to galvanic cells in which electrodes and/or solutions of different composition provide the electromotive potential. As long as there is a difference in temperature between the electrodes a current will flow through the circuit. A thermogalvanic cell can be seen as analogous to a concentration cell but instead of running on differences in the concentration/pressure of the reactants they make use of differences in the "concentrations" of thermal energy. The principal application of thermogalvanic cells is the production of electricity from low-temperature heat sources (waste heat and solar heat). Their energetic efficiency is low, in the range of 0.1% to 1% for conversion of heat into electricity. | 0 | Theoretical and Fundamental Chemistry |
Today, many different types of technologies exist in which splice sites can be located and analyzed for more information. The [http://www.umd.be/HSF3/ Human Splicing Finder] is an online database stemming from the Human Genome Project data. The genome database identifies thousands of mutations related to medical and health fields, as well as providing critical research information regarding splice site mutations. The tool specifically searches for pre-mRNA splicing errors, the calculation of potential splice sites using complex algorithms, and correlation with several other online genomic databases, such as the [http://www.ensembl.org/index.html Ensembl] genome browser. | 1 | Applied and Interdisciplinary Chemistry |
Prior to the 20th century, drugs were generally produced by small scale manufacturers with little regulatory control over manufacturing or claims of safety and efficacy. To the extent that such laws did exist, enforcement was lax. In the United States, increased regulation of vaccines and other biological drugs was spurred by tetanus outbreaks and deaths caused by the distribution of contaminated smallpox vaccine and diphtheria antitoxin. The Biologics Control Act of 1902 required that federal government grant premarket approval for every biological drug and for the process and facility producing such drugs. This was followed in 1906 by the Pure Food and Drugs Act, which forbade the interstate distribution of adulterated or misbranded foods and drugs. A drug was considered misbranded if it contained alcohol, morphine, opium, cocaine, or any of several other potentially dangerous or addictive drugs, and if its label failed to indicate the quantity or proportion of such drugs. The governments attempts to use the law to prosecute manufacturers for making unsupported claims of efficacy were undercut by a Supreme Court ruling restricting the federal governments enforcement powers to cases of incorrect specification of the drug's ingredients.
In 1937 over 100 people died after ingesting "Elixir Sulfanilamide" manufactured by S.E. Massengill Company of Tennessee. The product was formulated in diethylene glycol, a highly toxic solvent that is now widely used as antifreeze. Under the laws extant at that time, prosecution of the manufacturer was possible only under the technicality that the product had been called an "elixir", which literally implied a solution in ethanol. In response to this episode, the U.S. Congress passed the Federal Food, Drug, and Cosmetic Act of 1938, which for the first time required pre-market demonstration of safety before a drug could be sold, and explicitly prohibited false therapeutic claims. | 1 | Applied and Interdisciplinary Chemistry |
HDS systems are not maintenance-intensive, when compared with land-based BMP’s. Each manufactured system is different, therefore maintenance and inspection requirements should be looked at closely when purchasing an HDS system. Vacuum trucks are typically used for maintenance, so unobstructed access to accumulated pollutants for removal is critical. | 1 | Applied and Interdisciplinary Chemistry |
This branch of fluid dynamics augments the standard hydrodynamic equations with stochastic fluxes that model
thermal fluctuations.
As formulated by Landau and Lifshitz,
a white noise contribution obtained from the fluctuation-dissipation theorem of statistical mechanics
is added to the viscous stress tensor and heat flux. | 1 | Applied and Interdisciplinary Chemistry |
The carbon-phosphorus triple bond in phosphaalkynes represents an exception to the so-called "double bond rule", which would suggest that phosphorus tends not to form multiple bonds to carbon, and the nature of bonding within phosphaalkynes has therefore attracted much interest from synthetic and theoretical chemists. For simple phosphaalkynes such as H-C≡P and Me-C≡P, the carbon-phosphorus bond length is known by microwave spectroscopy, and for certain more complex phosphaalkynes, these bond lengths are known from single-crystal X-ray diffraction experiments. These bond lengths can be compared to the theoretical bond length for a carbon-phosphorus triple bond predicted by Pekka Pyykkö of 1.54 Å. By bond length metrics, most structurally characterized alkyl and aryl substituted phosphaalkynes contain triple bonds between carbon and phosphorus, as their bond lengths are either equal to or less than the theoretical bond distance.
The carbon-phosphorus bond order in phosphaalkynes has also been the subject of computational inquiry, where quantum chemical calculations have been utilized to determine the nature of bonding in these molecules from first principles. In this context, natural bond orbital (NBO) theory has provided valuable insight into the bonding within these molecules. Lucas and coworkers have investigated the electronic structure of various substituted phosphaalkynes, including the cyaphide anion (C≡P), using NBO, natural resonance theory (NRT), and quantum theory of atoms in molecules (QTAIM) in an attempt to better describe the bonding in these molecules. For the simplest systems, C≡P and H-C≡P, NBO analysis suggests that the only relevant resonance structure is that in which there is a triple bond between carbon and phosphorus. For more complex molecules, such as Me-C≡P and (Me)C-C≡P, the triple bonded resonance structure is still the most relevant, but accounts for only some of the overall electron density within the molecule (81.5% and 72.1%, respectively). This is due to interactions between the two carbon-phosphorus pi-bonds and the C-H or C-C sigma-bonds of the substituents, which can be visualized by inspecting the C-P pi-bonding molecular orbitals in these molecules. | 0 | Theoretical and Fundamental Chemistry |
A double-walled pipe is a secondary contained piping system. It is a pipe within a pipe, or encased in an outer covering, with an annulus (interstitial space) between the two diameters. The inner pipe is the primary or carrier pipe and the outer pipe is called the secondary or containment pipe. The great majority of double-walled piping applications involve wastewater, groundwater, and process safety. | 1 | Applied and Interdisciplinary Chemistry |
Factors other than straight pipe flow induce friction loss; these are known as "minor loss":
* Fittings, such as bends, couplings, valves, or transitions in hose or pipe diameter, or
* Objects intruded into the fluid flow.
For the purposes of calculating the total friction loss of a system, the sources of form friction are sometimes reduced to an equivalent length of pipe. | 1 | Applied and Interdisciplinary Chemistry |
As mentioned above, the CCE separates cells based on their sedimentation property but not specific features (e.g. surface protein, cell shape). It cannot separate different types of cells which have similar sedimentation properties. This means that previous purification needs to be done for mixed cell type sample. The CCE is also limited to cells which are able to be individually suspended in the buffer solution. Cells which always attach to something cannot be separated by the CCE. | 0 | Theoretical and Fundamental Chemistry |
When using RFLP, the theoretical risk of a coincidental match is 1 in 100 billion (100,000,000,000) although the practical risk is actually 1 in 1,000 because monozygotic twins are 0.2% of the human population. Moreover, the rate of laboratory error is almost certainly higher than that and actual laboratory procedures often do not reflect the theory under which the coincidence probabilities were computed. For example, coincidence probabilities may be calculated based on the probabilities that markers in two samples have bands in precisely the same location, but a laboratory worker may conclude that similar but not precisely-identical band patterns result from identical genetic samples with some imperfection in the agarose gel. However, in that case, the laboratory worker increases the coincidence risk by expanding the criteria for declaring a match. Studies conducted in the 2000s quoted relatively-high error rates, which may be cause for concern. In the early days of genetic fingerprinting, the necessary population data to compute a match probability accurately was sometimes unavailable. Between 1992 and 1996, arbitrary-low ceilings were controversially put on match probabilities used in RFLP analysis, rather than the higher theoretically computed ones. | 1 | Applied and Interdisciplinary Chemistry |
Plain RNAs may be poor immunogens, but antibodies can easily be created against RNA-protein complexes. Many autoimmune diseases see these types of antibodies. There haven't yet been reports of antibodies against siRNA bound to proteins. Some methods for siRNA delivery adjoin polyethylene glycol (PEG) to the oligonucleotide reducing excretion and improving circulating half-life. However recently a large Phase III trial of PEGylated RNA aptamer against factor IX had to be discontinued by Regado Biosciences because of a severe anaphylactic reaction to the PEG part of the RNA. This reaction led to death in some cases and raises significant concerns about siRNA delivery when PEGylated oligonucleotides are involved. | 1 | Applied and Interdisciplinary Chemistry |
The maximum pressure rating of a metering pump is actually the top of the discharge pressure range the pump is guaranteed to pump against at a reasonably controllable flow rate. The pump itself is a pressurizing device often capable of exceeding its pressure rating, although not guaranteed to. For this reason, if there is any stop valve downstream of the pump, a pressure relief valve should be placed in between to prevent overpressuring of the tubing or piping line in case the stop valve is inadvertently shut while the pump is running. The relief valve setting should be below the maximum pressure rating that the piping, tubing, or any other components there could withstand.
Liquids are only very slightly compressible. This property of liquids lets metering pumps discharge liquids at high pressure. Since a liquid can be only slightly compressed during a discharge stroke, it is forced out of the pump head. Gases are much more compressible. Metering pumps are not good at pumping gases. Sometimes, a metering or similar pump has to be primed before operation, i. e. the pump head filled with the liquid to be pumped. When gas bubbles enter a pump head, the compression motion compresses the gas but has a hard time forcing it out of the pump head. The pump may stop pumping liquid with gas bubbles in the pump head even though mechanically the pump is going through the motions, repeatedly compressing and decompressing the bubbles. To prevent this type of "vapor lock", chromatography solvents are often degassed before pumping.
If the pressure at the outlet is lower than the pressure at the inlet and remains that way in spite of the pumping, then this pressure difference opens both check valves simultaneously and the liquid flows through the pump head uncontrollably from inlet to outlet. This can happen whether the pump is working or not. This situation can be avoided by placing a correctly rated positive pressure differential check valve downstream of the pump. Such a valve will only open if a minimum rated pressure differential across the valve is exceeded, something which most high-pressure metering pumps can easily exceed. | 1 | Applied and Interdisciplinary Chemistry |
The first nearly complete human genomes sequenced were two Americans of predominantly Northwestern European ancestry in 2007 (J. Craig Venter at 7.5-fold coverage, and James Watson at 7.4-fold). This was followed in 2008 by sequencing of an anonymous Han Chinese man (at 36-fold), a Yoruban man from Nigeria (at 30-fold), a female clinical geneticist (Marjolein Kriek) from the Netherlands (at 7 to 8-fold), and a female leukemia patient in her mid-50s (at 33 and 14-fold coverage for tumor and normal tissues). Steve Jobs was among the first 20 people to have their whole genome sequenced, reportedly for the cost of $100,000. , there were 69 nearly complete human genomes publicly available. In November 2013, a Spanish family made their personal genomics data publicly available under a Creative Commons public domain license. The work was led by Manuel Corpas and the data obtained by direct-to-consumer genetic testing with 23andMe and the Beijing Genomics Institute. This is believed to be the first such Public Genomics dataset for a whole family. | 1 | Applied and Interdisciplinary Chemistry |
When a cell enters G1, Cyclin D- Cdk4/6 phosphorylates pRb at a single phosphorylation site. No progressive phosphorylation occurs because when HFF cells were exposed to sustained cyclin D- Cdk4/6 activity (and even deregulated activity) in early G1, only mono-phosphorylated pRb was detected. Furthermore, triple knockout, p16 addition, and Cdk 4/6 inhibitor addition experiments confirmed that Cyclin D- Cdk 4/6 is the sole phosphorylator of pRb.
Throughout early G1, mono-phosphorylated pRb exists as 14 different isoforms (the 15th phosphorylation site is not conserved in primates in which the experiments were performed). Together, these isoforms represent the “hypo-phosphorylated” active pRb state that was thought to exist. Each isoform has distinct preferences to associate with different exogenous expressed E2Fs.
A recent report showed that mono-phosphorylation controls pRb's association with other proteins and generates functional distinct forms of pRb. All different mono-phosphorylated pRb isoforms inhibit E2F transcriptional program and are able to arrest cells in G1-phase. Importantly, different mono-phosphorylated forms of pRb have distinct transcriptional outputs that are extended beyond E2F regulation. | 1 | Applied and Interdisciplinary Chemistry |
In organic chemistry, the Malaprade reaction or Malaprade oxidation is a glycol cleavage reaction in which a vicinal diol is oxidized by periodic acid or a periodate salt to give the corresponding carbonyl functional groups. The reaction was first reported by Léon Malaprade in 1928. Amino alcohols are also cleaved.
In terms of mechanism, the reaction is thought to proceed by a cyclic diester of iodine(VII). | 0 | Theoretical and Fundamental Chemistry |
Partial molar properties satisfy relations analogous to those of the extensive properties. For the internal energy U, enthalpy H, Helmholtz free energy A, and Gibbs free energy G, the following hold:
where is the pressure, the volume, the temperature, and the entropy. | 0 | Theoretical and Fundamental Chemistry |
As part of the remediation efforts to remove contamination from CFB Goose Bay, one of the waste dumps was transformed into an engineered wetland. | 1 | Applied and Interdisciplinary Chemistry |
In the two examples (on the right) the isoelectric point is shown by the green vertical line. In glycine the pK values are separated by nearly 7 units. Thus in the gas phase, the concentration of the neutral species, glycine (GlyH), is effectively 100% of the analytical glycine concentration. Glycine may exist as a zwitterion at the isoelectric point, but the equilibrium constant for the isomerization reaction in solution
is not known.
The other example, adenosine monophosphate is shown to illustrate the fact that a third species may, in principle, be involved. In fact the concentration of is negligible at the isoelectric point in this case.
If the pI is greater than the pH, the molecule will have a positive charge. | 0 | Theoretical and Fundamental Chemistry |
In very general terms, the viscous stresses in a fluid are defined as those resulting from the relative velocity of different fluid particles. As such, the viscous stresses must depend on spatial gradients of the flow velocity. If the velocity gradients are small, then to a first approximation the viscous stresses depend only on the first derivatives of the velocity. (For Newtonian fluids, this is also a linear dependence.) In Cartesian coordinates, the general relationship can then be written as
where is a viscosity tensor that maps the velocity gradient tensor onto the viscous stress tensor . Since the indices in this expression can vary from 1 to 3, there are 81 "viscosity coefficients" in total. However, assuming that the viscosity rank-2 tensor is isotropic reduces these 81 coefficients to three independent parameters , , :
and furthermore, it is assumed that no viscous forces may arise when the fluid is undergoing simple rigid-body rotation, thus , leaving only two independent parameters. The most usual decomposition is in terms of the standard (scalar) viscosity and the bulk viscosity such that and . In vector notation this appears as:
where is the unit tensor. This equation can be thought of as a generalized form of Newton's law of viscosity.
The bulk viscosity (also called volume viscosity) expresses a type of internal friction that resists the shearless compression or expansion of a fluid. Knowledge of is frequently not necessary in fluid dynamics problems. For example, an incompressible fluid satisfies and so the term containing drops out. Moreover, is often assumed to be negligible for gases since it is in a monatomic ideal gas. One situation in which can be important is the calculation of energy loss in sound and shock waves, described by Stokes' law of sound attenuation, since these phenomena involve rapid expansions and compressions.
The defining equations for viscosity are not fundamental laws of nature, so their usefulness, as well as methods for measuring or calculating the viscosity, must be established using separate means. A potential issue is that viscosity depends, in principle, on the full microscopic state of the fluid, which encompasses the positions and momenta of every particle in the system. Such highly detailed information is typically not available in realistic systems. However, under certain conditions most of this information can be shown to be negligible. In particular, for Newtonian fluids near equilibrium and far from boundaries (bulk state), the viscosity depends only space- and time-dependent macroscopic fields (such as temperature and density) defining local equilibrium.
Nevertheless, viscosity may still carry a non-negligible dependence on several system properties, such as temperature, pressure, and the amplitude and frequency of any external forcing. Therefore, precision measurements of viscosity are only defined
with respect to a specific fluid state. To standardize comparisons among experiments and theoretical models, viscosity data is sometimes extrapolated to ideal limiting cases, such as the zero shear limit, or (for gases) the zero density limit. | 1 | Applied and Interdisciplinary Chemistry |
Photopigments are unstable pigments that undergo a chemical change when they absorb light. The term is generally applied to the non-protein chromophore moiety of photosensitive chromoproteins, such as the pigments involved in photosynthesis and photoreception. In medical terminology, "photopigment" commonly refers to the photoreceptor proteins of the retina. | 1 | Applied and Interdisciplinary Chemistry |
Heat transfer fluids have distinct thermal and chemical properties which determine their suitability for various industrial applications. Key characteristics include:
* Thermal Stability: This refers to a fluids resistance to irreversible changes in its physical properties at varying temperatures. Fluids with high thermal stability have fewer degradation pathways, leading to longer service lifetimes and less maintenance. The determination of a fluids thermal stability is often based on tests such as ASTM D6743, which assess degradation products formed under thermal stress.
* Viscosity: The viscosity of a fluid affects its flow characteristics and pumping costs. Lower viscosity fluids are easier to pump and circulate within a system.
* Heat Capacity: A fluid’s heat capacity indicates how much thermal energy it can transport and store, impacting the efficiency of the heat transfer process.
* Thermal Conductivity and Thermal Diffusivity: These properties influence the rate at which heat is transferred through the fluid, affecting how quickly a system can respond to temperature changes.
* Corrosion Potential: The compatibility of a heat transfer fluid with system materials is crucial to minimize corrosion and extend the life of the equipment.
* Freezing and Boiling Points: Fluids should have high boiling and low freezing points to remain in the desired phase during the heat transfer process and to avoid phase change-related issues within the operating temperature range. | 1 | Applied and Interdisciplinary Chemistry |
Radial spokes are T-shaped structures present inside the axoneme. Each spoke consists of a "head" and a "stalk," while each of these sub-structures is itself made up of many protein subunits. In all, the radial spoke is known to contain at least seventeen proteins, five in the head and twelve in the stalk. The spoke stalk binds to the A-tubule of each microtubule outer doublet, and the spoke head faces in towards the center of the axoneme (see illustration at right). | 1 | Applied and Interdisciplinary Chemistry |
The asymmetric cyanohydrin reaction of benzaldehyde with trimethylsilylcyanide is made possible by employment of (R)-Binol at 1–10% catalyst loading. This ligand firsts reacts with a lithium alkoxy compound to form a lithium binaphtholate Complex.
The chemist Urech in 1872 was the first to synthesize cyanohydrins from ketones with alkali cyanides and acetic acid and therefore this reaction also goes by the name of Urech cyanohydrin method. | 0 | Theoretical and Fundamental Chemistry |
Drainage systems have been found in ancient cities over 5,000 years old, including Minoan, Indus, Persian, and Mesopotamian civilizations. These drainage systems focused mostly on reducing nuisances from localized flooding and waste water. Rudimentary systems made from brick or stone channels constituted the extent of urban drainage technologies for centuries. Cities in Ancient Rome also employed drainage systems to protect low-lying areas from excess rainfall. When builders began constructing aqueducts to import fresh water into cities, urban drainage systems became integrated into water supply infrastructure for the first time as a unified urban water cycle.
Modern drainage systems did not appear until the 19th century in Western Europe, although most of these systems were primarily built to deal with sewage issues rising from rapid urbanization. One such example is that of the London sewerage system, which was constructed to combat massive contamination of the River Thames. At the time, the River Thames was the primary component of Londons drainage system, with human waste concentrating in the waters adjacent to the densely populated urban center. As a result, several epidemics plagued Londons residents and even members of Parliament, including events known as the 1854 Broad Street cholera outbreak and the Great Stink of 1858. The concern for public health and quality of life launched several initiatives, which ultimately led to the creation of London's modern sewerage system designed by Joseph Bazalgette. This new system explicitly aimed to ensure waste water was redirected as far away from water supply sources as possible in order to reduce the threat of waterborne pathogens. Since then, most urban drainage systems have aimed for similar goals of preventing public health crises.
Within past decades, as climate change and urban flooding have become increasingly urgent challenges, drainage systems designed specifically for environmental sustainability have become more popular in both academia and practice. The first sustainable drainage system to utilize a full management train including source control in the UK was the Oxford services motorway station designed by SuDS specialists Robert Bray Associates Originally the term SUDS described the UK approach to sustainable urban drainage systems. These developments may not necessarily be in "urban" areas, and thus the "urban" part of SuDS is now usually dropped to reduce confusion. Other countries have similar approaches in place using a different terminology such as best management practice (BMP) and low-impact development in the United States, water-sensitive urban design (WSUD) in Australia, low impact urban design and development (LIUDD) in New Zealand, and comprehensive urban river basin management in Japan.
The National Research Council's definitive report on urban stormwater management described that urban drainage systems began in the United States after World War II. These structures were based on simple catch basins and pipes to transfer the water outside of the cities. Urban stormwater management started to evolve more in the 1970s when landscape architects focused more on low-impact development and began using practices such as infiltration channels. Parallel to this time, scientists started becoming concerned with other stormwater hazards surrounding pollution. Studies such as the Nationwide Urban Runoff Program showed that urban runoff contained pollutants like heavy metals, sediments, and pathogens, all of which water can pick up as it flows off of impermeable surfaces. It was at the beginning of the 21st century where stormwater infrastructure to allow runoff to infiltrate close to the source became popular. This was around the same time that the term green infrastructure was coined. | 1 | Applied and Interdisciplinary Chemistry |
In any clinical trial, the number of subjects, also called the sample size, has a large impact on the ability to reliably detect and measure the effects of the intervention. This ability is described as its "power", which must be calculated before initiating a study to figure out if the study is worth its costs. In general, a larger sample size increases the statistical power, also the cost.
The statistical power estimates the ability of a trial to detect a difference of a particular size (or larger) between the treatment and control groups. For example, a trial of a lipid-lowering drug versus placebo with 100 patients in each group might have a power of 0.90 to detect a difference between placebo and trial groups receiving dosage of 10 mg/dL or more, but only 0.70 to detect a difference of 6 mg/dL. | 1 | Applied and Interdisciplinary Chemistry |
Photosynthetic dinoflagellates contain membrane-bound light-harvesting complexes similar to those found in green plants. They additionally contain water-soluble protein-pigment complexes that exploit carotenoids such as peridinin to extend their photosynthetic capacity. Peridinin absorbs light in the blue-green wavelengths (470 to 550 nm) which are inaccessible to chlorophyll by itself; instead the PCP complex uses the geometry of the relative pigment orientations to effect extremely high-efficiency energy transfer from the peridinin molecules to their neighboring chlorophyll molecule. PCP has served as a common model system for spectroscopy and for theoretical calculations relating to the protein's photophysics.
PCP complexes are thought to occupy the thylakoid lumen. After energy transfer from the peridinin to the chlorophyll pigment, PCP complexes are believed to then transfer energy from the excited chlorophyll to membrane-bound light harvesting complexes. | 0 | Theoretical and Fundamental Chemistry |
Filling a clean bottle with river water is a very simple task, but a single sample is only representative of that point along the river the sample was taken from and at that point in time. Understanding the chemistry of a whole river, or even a significant tributary, requires prior investigation to understand how homogeneous or mixed the flow is and to determine if the quality changes during the course of a day and during the course of a year. Almost all natural rivers will have very significant patterns of change through the day and through the seasons. Water remote sensing offers a spatially continuous tool to improve understanding of spatial and temporal river water quality. Many rivers also have a very large flow that is unseen. This flows through underlying gravel and sand layers and is called hyporheic flow. How much mixing there is between the hyporheic zone and the water in the open channel will depend on a variety of factors, some of which relate to flows leaving aquifers which may have been storing water for many years. | 1 | Applied and Interdisciplinary Chemistry |
In ultraviolet (UV) methods there is no visible color change but the principle is exactly the same, i.e. the measurement of a change in the absorbance of the solution. UV methods usually measure the difference in absorbance at 340 nm wavelength between nicotinamide adenine dinucleotide (NAD) and its reduced form (NADH). | 0 | Theoretical and Fundamental Chemistry |
In addition to using TNP-ATP to determine whether a protein binds ATP, its binding affinity and dissociation constants, and number of binding sites, TNP-ATP can also be used in ligand binding studies. To do this, titrations of the protein are added to TNP-ATP. Then, ligand is added to displace the bound analog. This is measured by decreases in fluorescence. One can also do this by titrating protein with TNP-ATP in the presence and absence of varying concentrations of the ligand of interest. Using either experiment will allow the binding affinity of the ligand to protein to be measured.
TNP-ATP is also valuable fluorescence acceptor. This is because, as with any good acceptor, TNP-ATP absorbs over a wide wavelength range that corresponds to the range of emission of common FRET donors. Thus, TNP-ATP can be used to look at the conformational changes that proteins undergo. For example, Na+/K+ ATPase, the distance between the active site and Cys457 was shown to change from 25 Angstroms to 28 Angstroms in changing from the Na+ conformation to the K+ conformation.
In addition to fluorescent spectroscopy, TNP-ATP is very useful in fluorescent microscopy. This is because it greatly increases the sensitivity of the observations when bound to proteins—the enhanced fluorescence greatly reduces the problem of background fluorescence. This is especially true under epifluorescent illumation (illumination and light are both on the same side of the specimen).
TNP-ATP has also been used in X-ray crystallography because it can be used to determine binding constants of crystallized substrates. This technique also demonstrates the structure of proteins in the presence or absence of TNP-ATP, which may or may not correspond to the structure of proteins when they bind ATP. | 0 | Theoretical and Fundamental Chemistry |
The used nowadays are spectroscopic flames and electrothermal atomizers. Other atomizers, such as glow-discharge atomization, hydride atomization, or cold-vapor atomization, might be used for special purposes. | 0 | Theoretical and Fundamental Chemistry |
Australia and New Zealand published nutrient reference values including guidelines for dietary vitamin D intake in 2006. About a third of Australians have vitamin D deficiency. | 1 | Applied and Interdisciplinary Chemistry |
C3 carbon fixation is prone to photorespiration (PR) during dehydration, accumulating toxic glycolate products. In the 2000s scientists used computer simulation combined with an optimization algorithm to figure out what parts of the metabolic pathway may be tuned to improve photosynthesis. According to simulation, improving glycolate metabolism would help significantly to reduce photorespiration.
Instead of optimizing specific enzymes on the PR pathway for glycolate degradation, South et al. decided to bypass PR altogether. In 2019, they transferred Chlamydomonas reinhardtii glycolate dehydrogenase and Cucurbita maxima malate synthase into the chloroplast of tobacco (a model organism). These enzymes, plus the chloroplasts own, create a catabolic cycle: acetyl-CoA combines with glyoxylate to form malate, which is then split into pyruvate and CO; the former in turn splits into acetyl-CoA and CO. By forgoing all transport among organelles, all the CO released will go into increasing the CO concentration in the chloroplast, helping with refixation. The end result is 24% more biomass. An alternative using E. coli' glycerate pathway produced a smaller improvement of 13%. They are now working on moving this optimization into other crops like wheat. | 0 | Theoretical and Fundamental Chemistry |
The G equation has an exact expression for a simple slot burner. Consider a two-dimensional planar slot burner of slot width with a premixed reactant mixture is fed through the slot with constant velocity , where the coordinate is chosen such that lies at the center of the slot and lies at the location of the mouth of the slot. When the mixture is ignited, a flame develops from the mouth of the slot to certain height with a planar conical shape with cone angle . In the steady case, the G equation reduces to
If a separation of the form is introduced, the equation becomes
which upon integration gives
Without loss of generality choose the flame location to be at . Since the flame is attached to the mouth of the slot , the boundary condition is , which can be used to evaluate the constant . Thus the scalar field is
At the flame tip, we have , the flame height is easily determined as
and the flame angle is given by
Using the trigonometric identity , we have | 1 | Applied and Interdisciplinary Chemistry |
CSOs differ from sanitary sewer overflows in that the latter are caused by sewer system obstructions, damage, or flows in excess of sewer capacity (rather than treatment plant capacity.) Sanitary sewer overflows may occur at any low spot in the sewer system rather than at the CSO relief structures. Absence of a diversion outfall often causes sanitary sewer overflows to flood residential structures and/or flow over traveled road surfaces before reaching natural drainage channels. Sanitary sewer overflows may cause greater health risks and environmental damage than CSOs if they occur during dry weather when there is no precipitation runoff to dilute and flush away sewage pollutants. | 1 | Applied and Interdisciplinary Chemistry |
Drospirenone is an antimineralocorticoid with potassium-sparing properties, though in most cases no increase of potassium levels is to be expected. In women with mild or moderate chronic kidney disease, or in combination with chronic daily use of other potassium-sparing medications (ACE inhibitors, angiotensin II receptor antagonists, potassium-sparing diuretics, heparin, antimineralocorticoids, or nonsteroidal anti-inflammatory drugs), a potassium level should be checked after two weeks of use to test for hyperkalemia. Persistent hyperkalemia that required discontinuation occurred in 2 out of around 1,000 women (0.2%) with 4 mg/day drospirenone alone in clinical trials. | 0 | Theoretical and Fundamental Chemistry |
Dexmedetomidine may be useful for the treatment of the negative cardiovascular effects of acute amphetamines and cocaine intoxication and overdose. Dexmedetomidine has also been used as an adjunct to neuroaxial anesthesia for lower limb procedures. It has been successfully used to treat opioid withdrawal symptoms.
In 2022 it was approved by the FDA for the treatment of agitation in schizophrenia and bipolar disorder. | 0 | Theoretical and Fundamental Chemistry |
Sodium molybdate supports the biosynthesis of molybdoenzymes, which are found in all higher forms of life. The LC50 for freshwater fish ranges from 60 to 7630 mg/L. The toxicity of soluble molybdate to marine organisms has also been reported. | 0 | Theoretical and Fundamental Chemistry |
Polar substituent constants describe the way a substituent will influence a reaction through polar (inductive, field, and resonance) effects. To determine σ Taft studied the hydrolysis of methyl esters (RCOOMe). The use of ester hydrolysis rates to study polar effects was first suggested by Ingold in 1930. The hydrolysis of esters can occur through either acid and base catalyzed mechanisms, both of which proceed through a tetrahedral intermediate. In the base catalyzed mechanism the reactant goes from a neutral species to negatively charged intermediate in the rate determining (slow) step, while in the acid catalyzed mechanism a positively charged reactant goes to a positively charged intermediate.
Due to the similar tetrahedral intermediates, Taft proposed that under identical conditions any steric factors should be nearly the same for the two mechanisms and therefore would not influence the ratio of the rates. However, because of the difference in charge buildup in the rate determining steps it was proposed that polar effects would only influence the reaction rate of the base catalyzed reaction since a new charge was formed. He defined the polar substituent constant σ* as:
where log(k/k is the ratio of the rate of the base catalyzed reaction compared to the reference reaction, log(k/k is ratio of a rate of the acid catalyzed reaction compared to the reference reaction, and ρ* is a reaction constant that describes the sensitivity of the reaction series. For the definition reaction series, ρ* was set to 1 and R = methyl was defined as the reference reaction (σ* = zero). The factor of 1/2.48 is included to make σ* similar in magnitude to the Hammett σ values. | 0 | Theoretical and Fundamental Chemistry |
Results from Foldit have been included in a number of scientific publications.
Foldit players have been cited collectively as "Foldit players" or "Players, F." in some cases. Individual players have also been listed as authors on at least one paper, and on four related Protein Data Bank depositions.
*An August 2010 paper in the journal Nature credited Foldit's 57,000 players with providing useful results that matched or outperformed algorithmically computed solutions, stating "[p]layers working collaboratively develop a rich assortment of new strategies and algorithms; unlike computational approaches, they explore not only conformational space but also the space of possible search strategies".
*A November 2011 article in PNAS compared "recipes" developed by Foldit players to Rosetta scripts developed by members of the Baker Lab at the University of Washington. The player-developed "Blue Fuse" recipe compared favorably with the scientists' "Fast Relax" algorithm.
*In 2011, Foldit players helped decipher the crystal structure of a retroviral protease from Mason-Pfizer monkey virus (M-PMV), a monkey virus which causes HIV/AIDS-like symptoms, a scientific problem that had been unsolved for 15 years. While the puzzle was available for three weeks, players produced a 3D model of the enzyme in only ten days that is accurate enough for molecular replacement.
*In January 2012, Scientific American reported that Foldit gamers achieved the first crowdsourced redesign of a protein, an enzyme that catalysed the Diels–Alder reactions widely used in synthetic chemistry. A team including David Baker in the Center for Game Science at University of Washington in Seattle computationally designed the enzyme from scratch but found its potency needed improvement. Foldit players reengineered the enzyme by adding 13 amino acids, increasing its activity by more than 18 times.
*A September 2016 article in Nature Communications detailed a "crystallographic model-building competition between trained crystallographers, undergraduate students, Foldit players and automatic model-building algorithms" in which "a team of Foldit players achieved the most accurate structure" fitting a protein to the results of an X-ray crystallography experiment.
*A July 2018 article in Nature Communications reviewed the collaboration between Foldit players and teams in the WeFold consortium in biennial CASP competitions CASP11 and CASP12.
*A June 2019 letter in Nature described the analysis of proteins designed by Foldit players. Four player-designed proteins were successfully grown in E. coli and then "solved" via X-ray crystallography. The proteins were added to the Protein Data Bank as [https://www.rcsb.org/structure/6MRR 6MRR], [https://www.rcsb.org/structure/6MRS 6MRS], [https://www.rcsb.org/structure/6MSP 6MSP], and [https://www.rcsb.org/structure/6NUK 6NUK].
*In November 2019, an article in PLOS Biology reported how Foldit players were able to "build protein structures into crystallographic, high-resolution maps more accurately than expert crystallographers or automated model-building algorithms" using data from cryo EM experiments. | 1 | Applied and Interdisciplinary Chemistry |
Sialic acids are found at all cell surfaces of vertebrates and some invertebrates, and also at certain bacteria that interact with vertebrates.
Many viruses such as the Ad26 serotype of adenoviruses (Adenoviridae), rotaviruses (Reoviridae) and influenza viruses (Orthomyxoviridae) can use host-sialylated structures for binding to their target host cell. Sialic acids provide a good target for these viruses since they are highly conserved and are abundant in large numbers in virtually all cells. Unsurprisingly, sialic acids also play an important role in several human viral infections. The influenza viruses have hemagglutinin activity (HA) glycoproteins on their surfaces that bind to sialic acids found on the surface of human erythrocytes and on the cell membranes of the upper respiratory tract. This is the basis of hemagglutination when viruses are mixed with blood cells, and entry of the virus into cells of the upper respiratory tract. Widely used anti-influenza drugs (oseltamivir and zanamivir) are sialic acid analogs that interfere with release of newly generated viruses from infected cells by inhibiting the viral enzyme neuraminidase.
Some bacteria also use host-sialylated structures for binding and recognition. For example, evidence indicates that free sialic acids can behave as a signal to some specific bacteria, like Pneumococcus. Free sialic acid possibly can help the bacterium to recognize that it has reached a vertebrate environment suitable for its colonization. Modifications of Sias, such as the N-glycolyl group at the 5 position or O-acetyl groups on the side chain, may reduce the action of bacterial sialidases. | 0 | Theoretical and Fundamental Chemistry |
See the review of mechanical defenses by Lucas et al., 2000, which remains relevant and well regarded in the subject . Many plants have external structural defenses that discourage herbivory. Structural defenses can be described as morphological or physical traits that give the plant a fitness advantage by deterring herbivores from feeding. Depending on the herbivores physical characteristics (i.e. size and defensive armor), plant structural defenses on stems and leaves can deter, injure, or kill the grazer. Some defensive compounds are produced internally but are released onto the plants surface; for example, resins, lignins, silica, and wax cover the epidermis of terrestrial plants and alter the texture of the plant tissue. The leaves of holly plants, for instance, are very smooth and slippery making feeding difficult. Some plants produce gummosis or sap that traps insects. | 1 | Applied and Interdisciplinary Chemistry |
Homonuclear C-C coupling is normally only observed in samples that are enriched with C. The range for one-bond J(C,C) is 50–130 Hz. Two-bond J(C,C) are near 10 Hz.
The trends in J(H,C) and J(C,C) are similar, except that J(H,C are smaller owing to the modest value of the C nuclear magnetic moment. Values for J(H,C) range from 125 to 250 Hz. Values for J(H,C) are near 5 Hz and often are negative. | 0 | Theoretical and Fundamental Chemistry |
Ashish Arora is an Indian structural biologist and a senior scientist at Central Drug Research Institute. He did his postgraduate studies at Rajasthan University and post-doctoral work at the Max Planck Institute for Biophysical Chemistry, Goettingen, and University of Virginia, Charlottesville, VA, before joining the Central Drug Research Institute in 2002. He is known for his studies on Protein NMR Spectroscopy and the pathogenesis of diseases such as tuberculosis and visceral leishmaniasis, commonly known as Kala Azar and has delivered invited speeches at various seminars. The Department of Biotechnology of the Government of India awarded him the National Bioscience Award for Career Development, one of the highest Indian science awards, for his contributions to biosciences, in 2011. He is also a recipient of the 2010 Prof. B. K. Bachhawat Memorial Young Scientist Award of the National Academy of Sciences, India. | 1 | Applied and Interdisciplinary Chemistry |
Bioassay can be classified by how it is applied and how the response is recorded.
; Direct assay
: In a direct assay, the stimulus applied to the subject is specific and directly measurable, and the response to that stimulus is recorded. The variable of interest is the specific stimulus required to produce a response of interest (ex. death of the subject).
;Indirect assay
:In an indirect assay, the stimulus is fixed in advance and the response is measured in the subjects. The variable of interest in the experiment is the response to a fixed stimulus of interest.
;Quantitative response
:The measurement of the response to the stimulus is on a continuous scale (ex. blood sugar content, degree of color change in cell growth medium).
;Quantal response
:The response is binary; it is a determination of whether or not an event occurs (ex. death of the subject). | 1 | Applied and Interdisciplinary Chemistry |
The environment, health and safety aspects of gallium arsenide sources (such as trimethylgallium and arsine) and industrial hygiene monitoring studies of metalorganic precursors have been reported. California lists gallium arsenide as a carcinogen, as do IARC and ECA, and it is considered a known carcinogen in animals. On the other hand, a 2013 review (funded by industry) argued against these classifications, saying that when rats or mice inhale fine GaAs powders (as in previous studies), they get cancer from the resulting lung irritation and inflammation, rather than from a primary carcinogenic effect of the GaAs itself—and that, moreover, fine GaAs powders are unlikely to be created in the production or use of GaAs. | 0 | Theoretical and Fundamental Chemistry |
Enedithiols, with the exception of aromatic examples, are rare. The parent aromatic example is benzenedithiol. The dithiol of 1,3-dithiole-2-thione-4,5-dithiolate is also known. | 0 | Theoretical and Fundamental Chemistry |
A single hydrogen atom can participate in two hydrogen bonds. This type of bonding is called "bifurcated" (split in two or "two-forked"). It can exist, for instance, in complex organic molecules. It has been suggested that a bifurcated hydrogen atom is an essential step in water reorientation.
Acceptor-type hydrogen bonds (terminating on an oxygens lone pairs) are more likely to form bifurcation (it is called overcoordinated oxygen, OCO) than are donor-type hydrogen bonds, beginning on the same oxygens hydrogens. | 0 | Theoretical and Fundamental Chemistry |
ADP/ATP translocase is very specifically inhibited by two families of compounds. The first family, which includes atractyloside (ATR) and carboxyatractyloside (CATR), binds to the ADP/ATP translocase from the cytoplasmic side, locking it in a cytoplasmic side open conformation. In contrast, the second family, which includes bongkrekic acid (BA) and isobongkrekic acid (isoBA), binds the translocase from the matrix, locking it in a matrix side open conformation. The negatively charged groups of the inhibitors bind strongly to the positively charged residues deep within the binding pocket. The high affinity (K in the nanomolar range) makes each inhibitor a deadly poison by obstructing cellular respiration/energy transfer to the rest of the cell. There are structures available that show the translocator locked in a cytoplasmic state by the inhibitor carboxyatractyloside, or in the matrix state by the inhibitor bongkrekic acid. | 1 | Applied and Interdisciplinary Chemistry |
Samples that change their properties after dilution may not be analyzed via static light scattering in terms of the simple model presented here as the Zimm equation. A more sophisticated analysis known as composition-gradient static (or multi-angle) light scattering (CG-SLS or CG-MALS) is an important class of methods to investigate protein–protein interactions, colligative properties, and other macromolecular interactions as it yields, in addition to size and molecular weight, information on the affinity and stoichiometry of molecular complexes formed by one or more associating macromolecular/biomolecular species. In particular, static light scattering from a dilution series may be analyzed to quantify self-association, reversible oligomerization, and non-specific attraction or repulsion, while static light scattering from mixtures of species may be analyzed to quantify hetero-association. | 0 | Theoretical and Fundamental Chemistry |
The Borda–Carnot equation is applied to the flow through a sudden expansion of a horizontal pipe. At cross section 1, the mean flow velocity is equal to v, the pressure is p and the cross-sectional area is A. The corresponding flow quantities at cross section 2 – well behind the expansion (and regions of separated flow) – are v, p and A, respectively. At the expansion, the flow separates and there are turbulent recirculating flow zones with mechanical energy losses. The loss coefficient ξ for this sudden expansion is approximately equal to one: ξ ≈ 1.0. Due to mass conservation, assuming a constant fluid density ρ, the volumetric flow rate through both cross sections 1 and 2 has to be equal:
: so
Consequently – according to the Borda–Carnot equation – the mechanical energy loss in this sudden expansion is:
The corresponding loss of total head ΔH is:
For this case with ξ = 1, the total change in kinetic energy between the two cross sections is dissipated. As a result, the pressure change between both cross sections is (for this horizontal pipe without gravity effects):
and the change in hydraulic head h = z + p/(ρg):
The minus signs, in front of the right-hand sides, mean that the pressure (and hydraulic head) are larger after the pipe expansion.
That this change in the pressures (and hydraulic heads), just before and after the pipe expansion, corresponds with an energy loss becomes clear when comparing with the results of Bernoulli's principle. According to this dissipationless principle, a reduction in flow speed is associated with a much larger increase in pressure than found in the present case with mechanical energy losses. | 1 | Applied and Interdisciplinary Chemistry |
The precipitation of a second phase within the lattice of a material creates physical blockades through which a dislocation cannot pass. The result is that the dislocation must bend (which requires greater energy, or a greater stress to be applied) around the precipitates, which inevitably leaves residual dislocation loops encircling the second phase material and shortens the original dislocation. | 1 | Applied and Interdisciplinary Chemistry |
Water storage and distributed reservoirs are likely to displace people – a rehabilitation process that has attracted concern of sociologists and political groups. Further, the inter-link would create a path for aquatic ecosystems to be affected by movement of species from one river to another, which in turn may affect the livelihoods of people who rely on specific aquatic species for their income. Lakra et al., in their 2011 study, claim large dams, interbasin transfers and water withdrawal from rivers is likely to have negative as well as positive impacts on freshwater aquatic ecosystem. As regards to the impact on fish and aquatic biodiversity, there could be positive as well as negative impacts. | 1 | Applied and Interdisciplinary Chemistry |
It has been shown that survivin can heterodimerize individually with the two splice variants Survivin-2B and survivin-deltaEx3. Evidence of the heterodimerization of survivin splice variants with survivin was shown with co-immunoprecipitation experiments after cotransfection with the respective survivin variants with survivin. To determine the localization of exogenously expressed survivin-2B and survivin-deltaEx3, fusion constructs of the proteins were made with GFP and HcRed respectively and Daoy cells were transfected with the plasmid constructs. Survivin was also tagged with a fluorescent protein. The fusion of the survivin variants with the fluorescent molecules allows for simple detection of cellular location by fluorescence microscopy. Survivin-2B by itself, localized to both nuclear and cytoplasmic compartments whereas survivin-deltaEx3 localized only in the nucleus. The localization of the three variants (survivin, Survivin-2B, and survivin-deltaEx3) differ, however, when cotransfected together rather than individually.
To see which subcellular compartments contained the survivin splice variants complexes, fluorescent antibody markers for different organelles in the cell were employed. The assumption is that, under fluorescence microscopy, if the particular survivin complex is located in that particular cell compartment, one would observe an overlap from the fluorescence given off by the tagged survivin complex and the tagged compartment as well. Different color fluorescence is used to distinguish compartment from survivin.
* Endoplasmic reticulum and lyosomes: no colocalization
* Mitochondria and golgi: both survivin/survivin-2B and survivin/survivin-deltaEx3 colocalize
To verify these observations, they fractionated the subcellular compartments and performed western blot analysis to definitively say that survivin complexes did indeed localize at these compartments. | 1 | Applied and Interdisciplinary Chemistry |
Using a single colloidal crystal, phonon dispersion of the normal modes of vibration modes were investigated using photon correlation spectroscopy, or dynamic light scattering. This technique relies on the relaxation or decay of concentration (or density) fluctuations. These are often associated with longitudinal modes in the acoustic range. A distinctive increase in the sound wave velocity (and thus the elastic modulus) by a factor of 2.5 has been observed at the structural transition from colloidal liquid to colloidal solid, or point of ordering. | 0 | Theoretical and Fundamental Chemistry |
Ethyl chloroformate is an organic compound with the chemical formula . It is the ethyl ester of chloroformic acid. It is a colorless, corrosive and highly toxic liquid. It is a reagent used in organic synthesis for the introduction of the ethyl carbamate protecting group and for the formation of carboxylic anhydrides. | 0 | Theoretical and Fundamental Chemistry |
Amino acids from ingested food (or produced from catabolism of muscle protein) that are used for the synthesis of proteins and other biological substances can be oxidized by the body as an alternative source of energy, yielding urea and carbon dioxide. The oxidation pathway starts with the removal of the amino group by a transaminase; the amino group is then fed into the urea cycle. The first step in the conversion of amino acids into metabolic waste in the liver is removal of the alpha-amino nitrogen, which produces ammonia. Because ammonia is toxic, it is excreted immediately by fish, converted into uric acid by birds, and converted into urea by mammals.
Ammonia () is a common byproduct of the metabolism of nitrogenous compounds. Ammonia is smaller, more volatile, and more mobile than urea. If allowed to accumulate, ammonia would raise the pH in cells to toxic levels. Therefore, many organisms convert ammonia to urea, even though this synthesis has a net energy cost. Being practically neutral and highly soluble in water, urea is a safe vehicle for the body to transport and excrete excess nitrogen.
Urea is synthesized in the body of many organisms as part of the urea cycle, either from the oxidation of amino acids or from ammonia. In this cycle, amino groups donated by ammonia and -aspartate are converted to urea, while -ornithine, citrulline, -argininosuccinate, and -arginine act as intermediates. Urea production occurs in the liver and is regulated by N-acetylglutamate. Urea is then dissolved into the blood (in the reference range of 2.5 to 6.7 mmol/L) and further transported and excreted by the kidney as a component of urine. In addition, a small amount of urea is excreted (along with sodium chloride and water) in sweat.
In water, the amine groups undergo slow displacement by water molecules, producing ammonia, ammonium ions, and bicarbonate ions. For this reason, old, stale urine has a stronger odor than fresh urine. | 0 | Theoretical and Fundamental Chemistry |
The first type of photocyte granule has been found to contain between two and twelve microtubules. In addition, the matrix of the type I granule lacks a uniform shape or structure with ferritin distributed throughout. | 1 | Applied and Interdisciplinary Chemistry |
In 1969 the DESIGN program was first offered on the University Computing Company (UCC) time sharing services. The DISTILL column program was merged into DESIGN to create DESIGN 2000 in 1975, and in 1984 – REFINE column and crude feeds program were merged into DESIGN 2000 to create DESIGN II. In 1991 the Windows user interface was added to DESIGN II and DESIGN II for Windows was born. <br/>
WinSim Inc. has developed and marketed DESIGN II for Windows, a steady-state process simulator, since 1995 when the company purchased the rights to the program from ChemShare Corporation. <br />
<br />
Website: http://www.winsim.com/ | 1 | Applied and Interdisciplinary Chemistry |
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