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There are many challenges for the successful translation of mRNA into drugs because mRNA is a very large and heavy molecule(10^5 ~ 10^6 Da). Moreover, mRNA is unstable and easily degraded by nucleases, and it also activates the immune systems. Furthermore, mRNA has a high negative charge density and it reduces the permeation of mRNA across cellular membranes. Due to these reasons, without the appropriate delivery system, mRNA is degraded easily and the half-life of mRNA without a delivery system is only around 7 hours. Even though some degrees of challenges could be overcome by chemical modifications, delivery of mRNA remains an obstacle. The methods that have been researched to improve the delivery system of mRNA are using microinjection, RNA patches (mRNA loaded in a dissolving micro-needle), gene gun, protamine condensation, RNA adjuvants, and encapsulating mRNA in nanoparticles with lipids.
Even though In Vitro Translated (IVT) mRNA with delivery agents showed improved resistance against degradation, it needs more studies on how to improve the efficiency of the delivery of naked mRNA in vivo. | 1 | Applied and Interdisciplinary Chemistry |
The earliest and most diverse finds of metal artifacts are from West Mexico stretching in a belt along the Pacific coast from Guerrero to Nayarit. This indicates that this region was a regional nucleus of metallurgy, from which elements of technique, form and style could have diffused throughout Mesoamerica. | 1 | Applied and Interdisciplinary Chemistry |
The research that appeared to spark an onslaught of modified applications was a gel permeation chromatography technique of fixing poly(isopropyl acrylate) (PIPA) strands to glass beads and separating a mixture of dextrans, which was developed by Gewehr et al. They found that between the temperatures of 25–32 °C, the elution time of dextrans at different molecular weights exhibited a dependence on the temperature. Dextrans of the highest molecular weight eluted first since the PIPA chains exhibit hydrophilicity at temperatures below the LCST. As the temperature of the elution increased, when the chains behave in a more hydrophobic manner, the elution times increased for each of the analytes for the given range. The trend generally applies over the entire temperature range, but there is a flattening of the curve before 25 °C and after 32 °C (the approximate LCST for this experiment). It is important to note that above the LCST, the PIPA acts as a typical nonpolar stationary phase that would be used in reverse-phased chromatography. There are also instances of the elution times increasing below 15 °C, which most likely can be attributed to the lower temperatures’ effects on mass transfer playing a more significant role on retention than the stationary phase behavior. This study showed that the resolution could essentially be tuned by adjusting the operating temperature. The scope of this study was limited to isothermal conditions and attaching polymer chains to glass beads. The results, however, were satisfying enough to inspire other investigations and modifications to create a more versatile stationary phase for the advancement of chromatography. | 0 | Theoretical and Fundamental Chemistry |
Alkylation of beryllium halide is another common method to react to make an organoberyllium compound such as this:
M is not limited to any main group and/or transition metal. is not limited to phenyl, methyl, methyl oxide, carbene etc. can be any halide such as fluoride, bromide, iodide, or chloride.
An example of such reaction is the synthesis of bis(cyclopentadienyl)beryllium () or beryllocene from and potassium cyclopentadienide: | 0 | Theoretical and Fundamental Chemistry |
Belt filter designs are crafted using manufacturer design and performance data, operating installations, pilot testing, surveys of similar plants and testing of the wastewater solids to obtain a desired dewatered solid percentage from the sludge or slurry to be processed.
Belt filters press have 4 main zones: preconditioning zone, gravity drainage zone, linear compression (low-pressure) zone and roller compression (high-pressure) zone. Preconditioned slurry, which is flocculated and/or coagulated depending on the feed and process, is thickened in the gravity drainage zone. The gravity drainage zone is a flat or inclined belt where gravity drainage of free water occurs The gravity drainage area is sized according to feed solid concentrations. The standard size can be used for solids concentrations of 1.5 percent or greater, but a setup with a longer drainage area or extended size should be used for 1.5 to 2.5 percent feed solids for more free water drainage before compression. For dilute sludge with feed solids of less than 1.5 percent, an independent gravity drainage belt can be used. This belt is used only in the gravity drainage area, not in the pressure zones. The pressure or wedge zones use two belts, upper and lower, to sandwich the feed together, but an independent gravity zone has its own separate belt, making the belt filter a three-belt system. Depending on the required conditions of the cake, belt filters can have added washing stages and, infrared, hot gas or even microwave drying stages.
Belt filters are very versatile and are made to suit the sludges, slurries or mashed fruit to be processed. For a feed or treatment process which produces unpleasant odours, volatile emissions, pathogens and hazardous gases like hydrogen sulphide the belt filter can include fume hoods or even be completely enclosed in a gas tight housing. Due to the reduced visibility and increased corrosion associated with enclosure, the belt filter process can also be automated. Large filtration areas, additional rollers and a variable belt speed can be found in advanced belt press filter designs. | 1 | Applied and Interdisciplinary Chemistry |
He has published over 400 papers and 25 books over the course of his career.
Notable publications include:
*Tamejiro Hiyama and Koichiro Oshima, “有機合成化学” [Organic Synthetic Chemistry], Tokyo Kagaku Dojin, 2012,
*G. S. Zweifel, M. H. Nantz, Tamejiro Hiyama, “最新有機合成法 設計と戦略 – Modern Organic Synthesis: An Introduction”, Kagaku Dojin, 2009,
*Tamejiro Hiyama, coedited by Kyoko Nozaki, “有機合成のための触媒反応103” [103 Catalytic Reactions for Organic Synthesis], Tokyo Kagaku Dojin, 2004,
*Tamejiro Hiyama, “Organofluorine Compounds: Chemistry and Applications”, Springer, 2000,
*Tamejiro Hiyama, coedited with Martin Oestreich, “Organosilicon Chemistry: Novel Approaches and Reactions”, Wiley-VCH, 2019,
*Tamejiro Hiyama, coedited by Kyoko Nozaki, Yoshiaki Nakao, and Koji Nakano, “有機合成のための新触媒反応101” [101 New Catalytic Reactions for Organic Synthesis], Tokyo Kagaku Dojin, 20021, | 0 | Theoretical and Fundamental Chemistry |
Transcriptional noise is a primary cause of the variability (noise) in gene expression occurring between cells in isogenic populations (see also cellular noise) . A proposed source of transcriptional noise is transcriptional bursting although other sources of heterogeneity, such as unequal separation of cell contents at mitosis are also likely to contribute considerably. Bursting transcription, as opposed to simple probabilistic models of transcription, reflects multiple states of gene activity, with fluctuations between states separated by irregular intervals, generating uneven protein expression between cells. Noise in gene expression can have tremendous consequences on cell behaviour, and must be mitigated or integrated. In certain contexts, such as establishment of viral latency, the survival of microbes in rapidly changing stressful environments, or several types of scattered differentiation, the variability may be essential. Variability also impacts upon the effectiveness of clinical treatment, with resistance of bacteria and yeast to antibiotics demonstrably caused by non-genetic differences. Variability in gene expression may also contribute to resistance of sub-populations of cancer cells to chemotherapy and appears to be a barrier to curing HIV. | 1 | Applied and Interdisciplinary Chemistry |
Also well studied are the mesoionic carbenes based on 1,2,3-triazole, referred to as 1,2,3-triazol-4(or 5)-ylidenes. The first triazolylidenes were reported by Albrecht in 2008. These carbenes are typically trisubstituted with alkyl groups in the N1 and N3 positions and an aryl group in the C4 or C5 position. Free carbenes as well as numerous transition metal complexes have been reported. Free carbenes that are alkylated at N3 tend to undergo decomposition reactions in which the alkyl group participates in a nucleophilic attack at the carbene position. If N3 is substituted with a bulky alkyl group or an aryl group, the stability of the carbene increases significantly. | 0 | Theoretical and Fundamental Chemistry |
In molecular biology, the single-domain protein SUI1 is a translation initiation factor often found in the fungus, Saccharomyces cerevisiae (Bakers yeast) but it is also found in other eukaryotes and prokaryotes as well as archaea. It is otherwise known as Eukaryotic translation initiation factor 1 (eIF1) in eukaryotes or YciH' in bacteria. | 1 | Applied and Interdisciplinary Chemistry |
As a measure of flow compressibility, the Mach number can be derived from an appropriate scaling of the continuity equation. The full continuity equation for a general fluid flow is:<math display="block">{\partial \rho\over{\partial t}} + \nabla\cdot(\rho {\bf u}) = 0
\equiv -{1\over{\rho}}{D\rho\over{Dt}} = \nabla \cdot {\bf u} is the material derivative, is the density, and is the flow velocity. For isentropic pressure-induced density changes, where is the speed of sound. Then the continuity equation may be slightly modified to account for this relation:The next step is to nondimensionalize the variables as such:where is the characteristic length scale, is the characteristic velocity scale, is the reference pressure, and is the reference density. Then the nondimensionalized form of the continuity equation may be written as:where the Mach number . In the limit that , the continuity equation reduces to — this is the standard requirement for incompressible flow. | 1 | Applied and Interdisciplinary Chemistry |
Adhesion G protein-coupled receptors (adhesion GPCRs) are a class of 33 human protein receptors with a broad distribution in embryonic and larval cells, cells of the reproductive tract, neurons, leukocytes, and a variety of tumours. Adhesion GPCRs are found throughout metazoans and are also found in single-celled colony forming choanoflagellates such as Monosiga brevicollis and unicellular organisms such as Filasterea. The defining feature of adhesion GPCRs that distinguishes them from other GPCRs is their hybrid molecular structure. The extracellular region of adhesion GPCRs can be exceptionally long and contain a variety of structural domains that are known for the ability to facilitate cell and matrix interactions. Their extracellular region contains the membrane proximal GAIN (GPCR-Autoproteolsis INducing) domain. Crystallographic and experimental data has shown this structurally conserved domain to mediate autocatalytic processing at a GPCR-proteolytic site (GPS) proximal to the first transmembrane helix. Autocatalytic processing gives rise to an extracellular (α) and a membrane-spanning (β) subunit, which are associated non-covalently, resulting in expression of a heterodimeric receptor at the cell surface.
Ligand profiles and in vitro studies have indicated a role for adhesion GPCRs in cell adhesion and migration. Work utilizing genetic models confined this concept by demonstrating that the primary function of adhesion GPCRs may relate to the proper positioning of cells in a variety of organ systems. Moreover, growing evidence implies a role of adhesion GPCRs in tumour cell metastasis. Formal G protein-coupled signalling has been demonstrated for a number for adhesion GPCRs, however, the orphan receptor status of many of the receptors still hampers full characterisation of potential signal transduction pathways. In 2011, the [http://www.adhesiongpcr.org/ adhesion GPCR consortium] was established to facilitate research of the physiological and pathological functions of adhesion GPCRs. | 1 | Applied and Interdisciplinary Chemistry |
Hydrophobic insecticides and herbicides tend to be more active. Hydrophobic agrochemicals in general have longer half-lives and therefore display increased risk of adverse environmental impact. | 0 | Theoretical and Fundamental Chemistry |
The sodium adsorption ratio (SAR) is an irrigation water quality parameter used in the management of sodium-affected soils. It is an indicator of the suitability of water for use in agricultural irrigation, as determined from the concentrations of the main alkaline and earth alkaline cations present in the water. It is also a standard diagnostic parameter for the sodicity hazard of a soil, as determined from analysis of pore water extracted from the soil.
The formula for calculating the sodium adsorption ratio (SAR) is:
where sodium, calcium, and magnesium concentrations are expressed in milliequivalents/liter.
SAR allows assessment of the state of flocculation or of dispersion of clay aggregates in a soil. Sodium and potassium ions facilitate the dispersion of clay particles while calcium and magnesium promote their flocculation. The behaviour of clay aggregates influences the soil structure and affects the permeability of the soil on which directly depends the water infiltration rate. It is important to accurately know the nature and the concentrations of cations at which the flocculation occurs: critical flocculation concentration (CFC). The SAR parameter is also used to determine the stability of colloids in suspension in water.
Although SAR is only one factor in determining the suitability of water for irrigation, in general, the higher the sodium adsorption ratio, the less suitable the water is for irrigation. Irrigation using water with high sodium adsorption ratio may require soil amendments to prevent long-term damage to the soil.
If irrigation water with a high SAR is applied to a soil for years, the sodium in the water can displace the calcium and magnesium in the soil. This will cause a decrease in the ability of the soil to form stable aggregates and a loss of soil structure and tilth. This will also lead to a decrease in infiltration and permeability of the soil to water, leading to problems with crop production. Sandy soils will have less problems, but fine-textured soils will have severe problems if SAR is greater than 9. When SAR is less than 3, there will not be a problem.
The concept of SAR addresses only the effects of sodium on the stability of soil aggregates. However, high K and Mg concentrations have also negative effects on soil permeability. The effect of potassium can be similarly treated by means of the potassium adsorption ratio (PAR). To take into account simultaneously all major cations present in water, a new irrigation water quality parameter was defined: the cation ratio of structural stability (CROSS), a generalization of SAR. | 0 | Theoretical and Fundamental Chemistry |
In most flows of liquids, and of gases at low Mach number, the density of a fluid parcel can be considered to be constant, regardless of pressure variations in the flow. Therefore, the fluid can be considered to be incompressible, and these flows are called incompressible flows. Bernoulli performed his experiments on liquids, so his equation in its original form is valid only for incompressible flow.
A common form of Bernoulli's equation is:
where:
* is the fluid flow speed at a point,
* is the acceleration due to gravity,
* is the elevation of the point above a reference plane, with the positive -direction pointing upward—so in the direction opposite to the gravitational acceleration,
* is the pressure at the chosen point, and
* is the density of the fluid at all points in the fluid.
Bernoullis equation and the Bernoulli constant are applicable throughout any region of flow where the energy per unit mass is uniform. Because the energy per unit mass of liquid in a well-mixed reservoir is uniform throughout, Bernoullis equation can be used to analyze the fluid flow everywhere in that reservoir (including pipes or flow fields that the reservoir feeds) except where viscous forces dominate and erode the energy per unit mass.
The following assumptions must be met for this Bernoulli equation to apply:
* the flow must be steady, that is, the flow parameters (velocity, density, etc.) at any point cannot change with time,
* the flow must be incompressible—even though pressure varies, the density must remain constant along a streamline;
* friction by viscous forces must be negligible.
For conservative force fields (not limited to the gravitational field), Bernoulli's equation can be generalized as:
where is the force potential at the point considered. For example, for the Earth's gravity .
By multiplying with the fluid density , equation () can be rewritten as:
or:
where
* is dynamic pressure,
* is the piezometric head or hydraulic head (the sum of the elevation and the pressure head) and
* is the stagnation pressure (the sum of the static pressure and dynamic pressure ).
The constant in the Bernoulli equation can be normalized. A common approach is in terms of total head or energy head :
The above equations suggest there is a flow speed at which pressure is zero, and at even higher speeds the pressure is negative. Most often, gases and liquids are not capable of negative absolute pressure, or even zero pressure, so clearly Bernoulli's equation ceases to be valid before zero pressure is reached. In liquids—when the pressure becomes too low—cavitation occurs. The above equations use a linear relationship between flow speed squared and pressure. At higher flow speeds in gases, or for sound waves in liquid, the changes in mass density become significant so that the assumption of constant density is invalid. | 1 | Applied and Interdisciplinary Chemistry |
Peak copper is the point in time at which the maximum global copper production rate is reached. Since copper is a finite resource, at some point in the future new production from mining will diminish, and at some earlier time production will reach a maximum. When this will occur is a matter of dispute. Unlike fossil fuels, copper is scrapped and reused, and it has been estimated that at least 80% of all copper ever mined is still available (having been repeatedly recycled).
Copper is among the most important industrial metals, ranking third after iron and aluminium in terms of quantity used. It is valued for its heat and electrical conductivities, ductility, malleability and resistance to corrosion. Electrical uses account for about three quarters of total copper consumption, including power cables, data cables and electrical equipment. It is also used in cooling and refrigeration tubing, heat exchangers, water pipes and consumer products.
Copper has been used by humans for at least 10,000 years. More than 97% of all copper ever mined and smelted has been extracted since 1900. The increased demand for copper due to the growing Indian and Chinese economies since 2006 has led to increased prices and an increase in copper theft. | 1 | Applied and Interdisciplinary Chemistry |
Chinese literary gardens are an example of a sustainable lawn that showcased natural beauty in suburban areas. These gardens, dating back to the Shang Dynasty (1600–1046 BC), were designed to allow native plant species to thrive in their natural conditions and appear untouched by humans. This created ecological havens within the city. | 1 | Applied and Interdisciplinary Chemistry |
ADP-ribosylation is the addition of one or more ADP-ribose moieties to a protein. It is a reversible post-translational modification that is involved in many cellular processes, including cell signaling, DNA repair, gene regulation and apoptosis.
Improper ADP-ribosylation has been implicated in some forms of cancer. It is also the basis for the toxicity of bacterial compounds such as cholera toxin, diphtheria toxin, and others. | 1 | Applied and Interdisciplinary Chemistry |
In chemistry, catalytic resonance theory was developed to describe the kinetics of reaction acceleration using dynamic catalyst surfaces. Catalytic reactions occurring on surfaces that undergo variation in surface binding energy and/or entropy exhibit overall increase in reaction rate when the surface binding energy frequencies are comparable to the natural frequencies of the surface reaction, adsorption, and desorption. | 0 | Theoretical and Fundamental Chemistry |
The most common optical system uses spherical collimators and thus contains optical aberrations that curve the field where the slit images come to focus, so that slits are sometimes curved instead of simply straight, to approximate the curvature of the image. This allows taller slits to be used, gathering more light, while still achieving high spectral resolution. Some designs take another approach and use toroidal collimating mirrors to correct the curvature instead, allowing higher straight slits without sacrificing resolution. | 0 | Theoretical and Fundamental Chemistry |
Unlike Q-FISH, Flow-FISH utilizes the quantitative properties of telomere specific PNA probe retention to quantify median fluorescence in a population of cells, via the use of a flow cytometer, instead of a fluorescence microscope. The primary advantage of this technique is that it eliminates the time required in Q-FISH to prepare metaphase spreads of cells of interest, and that flow cytometric analysis is also considerably faster than the methods required to acquire and analyze Q-FISH prepared slides. Flow-FISH thus allows for a higher throughput analysis of telomere length in blood leukocytes, which are a readily available form of human tissue sample. The most recent versions of the flow-FISH technique include an internal control population of cow thymocytes with a known telomere length detected by TRF or telomere restriction fragment analysis to which the fluorescence of a given unknown sample may be compared. Because cow thymocytes take up LDS751 dye to a lesser extent than their human counterparts, they may be reliably differentiated via plotting and gating the desired populations. Other cell types that have not in the past proven to be good candidates for flow-FISH can be analyzed via extraction of nuclei and performance of the technique on them directly. | 1 | Applied and Interdisciplinary Chemistry |
Materials can now be analysed through photoanalysis procedures. Unlike sieve analyses which can be time-consuming and inaccurate, taking a photo of a sample of the materials to be measured and using software to analyze the photo can result in rapid, accurate measurements. Another advantage is that the material can be analyzed without being handled. This is beneficial in the agricultural industry, as handling of food products can lead to contamination. Photoanalysis equipment and software is currently being used in mining, forestry and agricultural industries worldwide. | 0 | Theoretical and Fundamental Chemistry |
The embryo transfer procedure starts by placing a speculum in the vagina to visualize the cervix, which is cleansed with saline solution or culture media. A transfer catheter is loaded with the embryos and handed to the clinician after confirmation of the patient's identity. The catheter is inserted through the cervical canal and advanced into the uterine cavity. Several types of catheters are used for this process, however, there is good evidence that using a soft vs a hard transfer catheter can increase the chances of clinical pregnancy.
There is good and consistent evidence of benefit in ultrasound guidance, that is, making an abdominal ultrasound to ensure correct placement, which is 1–2 cm from the uterine fundus. There is evidence of a significant increase in clinical pregnancy using ultrasound guidance compared with only "clinical touch", as well as performing the transfer with hyaluronic acid enriched transfer media. Anesthesia is generally not required. Single embryo transfers in particular require accuracy and precision in placement within the uterine cavity. The optimal target for embryo placement, known as the maximal implantation potential (MIP) point, is identified using 3D/4D ultrasound. However, there is limited evidence that supports deposition of embryos in the midportion of the uterus.
After insertion of the catheter, the contents are expelled and the embryos are deposited. Limited evidence supports making trial transfers before performing the procedure with embryos. After expulsion, the duration that the catheter remains inside the uterus has no effect on pregnancy rates. Limited evidence suggests avoiding negative pressure from the catheter after expulsion. After withdrawal, the catheter is handed to the embryologist, who inspects it for retained embryos.
In the process of zygote intrafallopian transfer (ZIFT), eggs are removed from the woman, fertilised, and then placed in the woman's fallopian tubes rather than the uterus. | 1 | Applied and Interdisciplinary Chemistry |
*Neil Bartlett's demonstration of the first reaction of a noble gas at the University of British Columbia in 1962
*Modern baking powder, developed by Eben Horsford at the Rumford Chemical Works (now Clabber Girl) in 1869
*Tide, the first heavy-duty synthetic laundry detergent, developed by Procter & Gamble in 1946 | 1 | Applied and Interdisciplinary Chemistry |
After labeling of the surface with the selected F bioactives, the constructs will be present and oriented at the membrane surface. It is expected that the FSL will be highly mobile within the membrane and the choice of lipid tail will effect is relative partitioning within the membrane. The construct unless it has flip-flop behavior is expected to remain surface presented. However, the modification is not permanent in living cells and constructs will be lost (consumed) at a rate proportional to the activity at the membrane and division rate of the cell (with dead cells remaining highly labeled). Additionally, when present in vivo with serum lipids FSLs will elute from the membrane into the plasma at a rate of about 1% per hour. In fixed cells or inactive cells (e.g. red cells) stored in serum free media the constructs are retained normally.
Liposomes are easy koded by simply adding FSL Kode constructs into the preparation. Contacting koded liposomes with microplates or other surfaces can cause the labeling of the microplate surface. | 1 | Applied and Interdisciplinary Chemistry |
B cell - bacteria - bacterial conjugation - bacterial outer membrane protein - bacterial protein - bacteriorhodopsin - base (chemistry) - base pair - base sequence - basic fibroblast growth factor - Bcl-2 - bcr-abl fusion protein - benzene - benzene ring - beta-2 microglobulin - beta adrenergic receptor - beta sheet - beta-1 adrenergic receptor - beta-2 adrenergic receptor - beta-thromboglobulin - bioaccumulation - biochemistry - biodiversity - bioethics - biogenic amine receptor - bioinformatics - biological membrane - biologist - biology - biomechanics - biomedical model - biomolecule - biophysics - biopolymer - biosalinity - biotechnology - BLAST - blood proteins - boiling point - Boltzmann distribution - Boltzmann principle - bombesin - bombesin receptor - bone morphogenetic protein - bradykinin - bradykinin receptor - BRCA1 - buffer solution | 1 | Applied and Interdisciplinary Chemistry |
When heating iron above 912 °C (1,674 °F), its crystal structure changes to a face-centered cubic (fcc) crystalline structure. In this form it is called gamma iron (γ-Fe) or austenite. γ-iron can dissolve considerably more carbon (as much as 2.04% by mass at 1,146 °C). This γ form of carbon saturation is exhibited in austenitic stainless steel. | 1 | Applied and Interdisciplinary Chemistry |
The European Molecular Spectroscopy Group, which was constituted informally after the Second World War to bring together spectroscopists from across Europe, met for the first time in Konstanz in 1947. Reinhard Mecke was at the time working in temporary accommodation at Wallhausen, a small village on the shores of Lake Constance, and the meeting (initiated by invitation of Professors Jean Lecomte and Alfred Kastler from Paris) was attended by French, German and Austrian spectroscopists.
However, the meeting which has since become regarded as the first of the EUCMOS series was organised under the auspices of Ernst Miescher in Basel in 1951, followed every two years by conferences in Paris (1953), Oxford (1955), Freiburg (1957), Bologna (1959), Amsterdam (1961), Budapest (1963), Copenhagen (1965), Madrid (1967) and Liége (1969). The next meeting was not held until 1973 when it was organized in Tallinn. The 1975 meeting in Strasbourg was devoted to the molecular spectroscopy of dense phases. The biennial meetings were perturbed for the second time in 1991 when EUCMOS XX, which was due to be held in Zagreb, had to be cancelled because of the Civil war in Yugoslavia. The following meeting, in Vienna, was brought forward by a year and the meetings have since been held in the even years. At EUCMOS XXII held in Essen (1994), William James Orville-Thomas retired as President of the International Committee and Austin Barnes was elected to this post. During his mandate, 11 conferences of the series were held, included the one organized in Coimbra in the Year 2000 (EUCMOS XXV). In EUCMOS XXXIII (2016, Szeged) Barnes retired as President of the International Committee and Rui Fausto (vice-President since EUCMOS XXVII, in Cracow, together with Henryk Ratajczak) was elected to this position. The new President had already been chosen as the organizer of the following EUCMOS meeting in Coimbra, 2018 (EUCMOS XXXIV). Sylvia Turrel and Michael Schmitt are the current vice-Presidents of the International Committee.
EUCMOS gathered over the years (present and future) Nobel prize winners from all areas of molecular physics as plenary speakers. This starts in 1953 with Alfred Kastler in Paris (Nobel prize 1966) followed by Gerhard Herzberg 1989 in Leipzig (Nobel prize 1971), Harold Kroto 2000 in Coimbra (Nobel prize 1996) and Theodor W. Hänsch 2010 in Florence (Nobel prize 2005). | 0 | Theoretical and Fundamental Chemistry |
The first step in determining the configuration index is to assign a priority number to each coordinating ligand according to the Cahn-Ingold-Prelog priority rules, (CIP rules). The preferred ligand takes the lowest priority number. For example, of the ligands acetonitrile, chloride ion and pyridine thepriority number assigned are chloride, 1; acetonitrile,2; pyridene,3. Each coordination type has a different procedure for specifying the configuration index and these are outlined in below. | 0 | Theoretical and Fundamental Chemistry |
Corson also served on NACA"s Special Committee on Space Technology also called the Stever Committee, named after its chairman. It was a special steering committee that was formed with the mandate to coordinate various branches of the Federal government, private companies as well as universities within the United States with NACA's objectives and also harness their expertise in order to develop a space program. Dr. Corson therefore played a pivotal role in the process of establishing the nascent United States space program. | 1 | Applied and Interdisciplinary Chemistry |
Aggregation pheromones function in mate choice, overcoming host resistance by mass attack, and defense against predators. A group of individuals at one location is referred to as an aggregation, whether consisting of one sex or both sexes. Male-produced sex attractants have been called aggregation pheromones, because they usually result in the arrival of both sexes at a calling site and increase the density of conspecifics surrounding the pheromone source. Most sex pheromones are produced by the females; only a small percentage of sex attractants are produced by males. Aggregation pheromones have been found in members of the Coleoptera, Collembola, Diptera, Hemiptera, Dictyoptera, and Orthoptera. In recent decades, aggregation pheromones have proven useful in the management of many pests, such as the boll weevil (Anthonomus grandis), the pea and bean weevil (Sitona lineatus, and stored product weevils (e.g. Sitophilus zeamais, Sitophilus granarius, and Sitophilus oryzae). Aggregation pheromones are among the most ecologically selective pest suppression methods. They are non-toxic and effective at very low concentrations. | 1 | Applied and Interdisciplinary Chemistry |
An autoreceptor is a type of receptor located in the membranes of nerve cells. It serves as part of a negative feedback loop in signal transduction. It is only sensitive to the neurotransmitters or hormones released by the neuron on which the autoreceptor sits. Similarly, a heteroreceptor is sensitive to neurotransmitters and hormones that are not released by the cell on which it sits. A given receptor can act as either an autoreceptor or a heteroreceptor, depending upon the type of transmitter released by the cell on which it is embedded.
Autoreceptors may be located in any part of the cell membrane: in the dendrites, the cell body, the axon, or the axon terminals.
Canonically, a presynaptic neuron releases a neurotransmitter across a synaptic cleft to be detected by the receptors on a postsynaptic neuron. Autoreceptors on the presynaptic neuron will also detect this neurotransmitter and often function to control internal cell processes, typically inhibiting further release or synthesis of the neurotransmitter. Thus, release of neurotransmitter is regulated by negative feedback. Autoreceptors are usually G protein-coupled receptors (rather than transmitter-gated ion channels) and act via a second messenger. | 1 | Applied and Interdisciplinary Chemistry |
Because mechanisms that control the accumulation of damage through the lifetime of a cell are essential to longevity, it is logical that caretaker and gatekeeper genes play a significant role in cellular aging. Increased activity of caretaker genes postpones aging, increasing lifespan. This is because of the regulatory function associated with caretaker genes in maintaining the stability of the genome. The actions of caretaker genes contribute to increasing lifespan of the cell.
A specific purpose of caretaker genes has been outlined in chromosomal duplication. Caretakers have been identified as crucial to encoding products that maintain the telomeres. It is believed that degradation of telomeres, the ends of chromosomes, through repeated cell cycle divisions, is a main component of cellular aging and death.
It has been suggested that gatekeeper genes confer beneficial anti-cancer affects but may provide deleterious effects that increase aging. This is because young organisms experiencing times of rapid growth necessitate significant anti-cancer mechanisms. As the organism ages, however, these formerly beneficial pathways become deleterious by inducing apoptosis in cells of renewable tissues, causing degeneration of the structure. Studies have shown an increased expression of pro-apoptotic genes in age-related pathologies. This is because the products of gatekeeper genes are directly involved in coding for cellular growth and proliferation.
However, dysfunctional caretaker genes do not always lead to a cancerous phenotype. For example, defects in nucleotide excision repair pathways are associated with premature aging phenotypes in diseases such as Xeroderma pigmentosum and Trichothiodystrophy. These patients exhibit brittle hair, nails, scaly skin, and hearing loss – characteristics associated with simple human aging. This is important because the nucleotide excision repair pathway is a mechanism thought to be encoded by a caretaker gene. Geneticists studying these premature-aging syndromes propose that caretaker genes that determine cell fate also play a significant role in aging. Accumulation of DNA damage with age may be especially prevalent in the central nervous system because of low DNA repair capability in postmitotic brain tissue.
Similarly, gatekeeper genes have been identified as having a role in aging disorders that exhibit mutations in such genes without an increased susceptibility to cancer. Experiments with mice that have increased gatekeeper function in the p53 gene show reduced cancer incidence (due to the protective activities of products encoded by p53) but a faster rate of aging.
Cellular senescence, also encoded by a gatekeeper gene, is arrest of the cell cycle in the G1 phase. Qualitative differences have been found between senescent cells and normal cells, including differential expression of cytokines and other factors associated with inflammation. It is believed that this may contribute, in part, to cellular aging.
In sum, although mechanisms encoded by gatekeeper and caretaker genes to protect individuals from cancer early in life, namely induction of apoptosis or senescence, later in life these functions may promote the aging phenotype. | 1 | Applied and Interdisciplinary Chemistry |
Surfactants are chemical compounds that decrease the surface tension or interfacial tension between two liquids, a liquid and a gas, or a liquid and a solid. The word "surfactant" is a blend of surface-active agent, coined . As they consist of a water-repellent and a water-attracting part, they enable water and oil to mix; they can form foam and facilitate the detachment of dirt.
Surfactants are among the most widespread and commercially important chemicals. Private households as well as many industries use them in large quantities as detergents and cleaning agents, but also for example as emulsifiers, wetting agents, foaming agents, antistatic additives, or dispersants.
Surfactants occur naturally in traditional plant-based detergents, e.g. horse chestnuts or soap nuts; they can also be found in the secretions of some caterpillars. Today the most commonly used surfactants, above all anionic linear alkylbenzene sulfates (LAS), are produced from petroleum products. However, surfactants are (again) increasingly produced in whole or in part from renewable biomass, like sugar, fatty alcohol from vegetable oils, by-products of biofuel production, or other biogenic material. | 0 | Theoretical and Fundamental Chemistry |
Consider a body with fins on its outer surface, with air flowing around it.
The heat transfer rate depends on
* Shape and geometry of the external surface
* Surface area of the body
* Velocity of the wind (or any fluid in other cases)
* Temperature of surroundings
Modelling of the fins in this case involves, experimenting on this physical model and optimizing the number of fins and fin pitch for maximum performance.
One of the experimentally obtained equations for heat transfer coefficient for the fin surface for low wind velocities is:
where
k= Fin surface heat transfer coefficient [W/mK ]
a=fin length [mm]
v=wind velocity [km/h]
θ=fin pitch [mm]
Another equation for high fluid velocities, obtained from experiments conducted by Gibson, is
where
k=Fin surface heat transfer coefficient[W/mK ]
a=Fin length[mm]
θ=Fin pitch[mm]
v=Wind velocity[km/h]
A more accurate equation for fin surface heat transfer coefficient is:
where
k (avg)= Fin surface heat transfer coefficient[W/mK ]
θ=Fin pitch[mm]
v=Wind velocity[km/h]
All these equations can be used to evaluate average heat transfer coefficient for various fin designs. | 1 | Applied and Interdisciplinary Chemistry |
Geological deposits of arsenic may be released into rivers where deep ground-waters are exploited as in parts of Pakistan. Many metalloid ores such as lead, gold and copper contain traces of arsenic and poorly stored tailings may result in arsenic entering the hydrological cycle. | 1 | Applied and Interdisciplinary Chemistry |
From these values, we know that:
where
* CO = Cardiac Output
* C = Oxygen content of arterial blood
* C = Oxygen content of mixed venous blood
This allows us to say
and hence calculate cardiac output.
Note that (C – C) is also known as the arteriovenous oxygen difference. | 1 | Applied and Interdisciplinary Chemistry |
The veins are the vascular tissue of the leaf and are located in the spongy layer of the mesophyll. The pattern of the veins is called venation. In angiosperms the venation is typically parallel in monocotyledons and forms an interconnecting network in broad-leaved plants. They were once thought to be typical examples of pattern formation through ramification, but they may instead exemplify a pattern formed in a stress tensor field.
A vein is made up of a vascular bundle. At the core of each bundle are clusters of two
distinct types of conducting cells:
; Xylem: Cells that bring water and minerals from the roots into the leaf.
; Phloem: Cells that usually move sap, with dissolved sucrose (glucose to sucrose) produced by photosynthesis in the leaf, out of the leaf.
The xylem typically lies on the adaxial side of the vascular bundle and the phloem typically lies on the abaxial side. Both are embedded in a dense parenchyma tissue, called the sheath, which usually includes some structural collenchyma tissue. | 0 | Theoretical and Fundamental Chemistry |
There are five major reactions classed as anaplerotic, and it is estimated that the production of oxaloacetate from pyruvate has the most physiologic importance.
The malate is created by PEP carboxylase and malate dehydrogenase in the cytosol. Malate, in the mitochondrial matrix, can be used to make pyruvate (catalyzed by malic enzyme) or oxaloacetic acid, both of which can enter the citric acid cycle.
Glutamine can also be used to produce oxaloacetate during anaplerotic reactions in various cell types through "glutaminolysis", which is also seen in many c-Myc transformed cells. Anaplerotic enzymes mediate an alternative pathway to insulin secretion by aiding the production of cytosolic signal molecules. Pancreatic β-cells which regulate blood glucose level by secreting insulin,contain high a mounts of pyruvate carboxylase. A decrease in insulin secretion and anaplerotic activity has been found in β-cells that do not have hypoxia-inducible factor-1 beta | 1 | Applied and Interdisciplinary Chemistry |
The 43S is an important intermediate complex during cap-dependent translation initiation. In the canonical model of translation initiation, the 43S PIC is pre-formed as a stable complex and recruited to the 5 cap of eukaryotic messenger RNAs (mRNAs) by the eIF4F complex. The 43S PIC then "scans" in the 5 --> 3' direction along the mRNA in an ATP-dependent fashion (via eIF4A and/or other RNA helicases such as Ded1/DDX3 and DHX29) to locate the start codon. Start codon recognition occurs through base-pairing between the Met-tRNA and AUG in the ribosomal P-site and a number of associated changes, and is followed by joining of the large 60S ribosomal subunit to form the 80S ribosome. | 1 | Applied and Interdisciplinary Chemistry |
The Comparative Toxicogenomics Database (CTD) is a public website and research tool launched in November 2004 that curates scientific data describing relationships between chemicals/drugs, genes/proteins, diseases, taxa, phenotypes, GO annotations, pathways, and interaction modules.
The database is maintained by the Department of Biological Sciences at North Carolina State University. | 1 | Applied and Interdisciplinary Chemistry |
NBQX (2,3-dioxo-6-nitro-7-sulfamoyl-benzo[f]quinoxaline) is an antagonist of the AMPA receptor.
NBQX blocks AMPA receptors in micromolar concentrations (~10–20 μM) and also blocks kainate receptors. In experiments, it is used to counter glutamate excitotoxicity. NBQX was found to have anticonvulsant activity in rodent seizure models.
As the disodium salt, NBQX is soluble in water at high concentrations (at least up to 100 mM). | 1 | Applied and Interdisciplinary Chemistry |
First generation cephalosporins were the first cephalosporins on the market. They have good antimicrobial activity against gram-positive bacteria but limited activity against gram-negative species. The chemical structures of the first generation cephalosporins are fairly simple. As an example three drugs from this class (cefalexin, cefradine and cefadroxil) all have a single methyl group at position C-3. The common side groups at C-3 for first class cephalosporins are small uncharged groups like methyl. The methyl group at position C-3 gives low affinity for common PBP which can in part explain the relatively low activity of these first drugs. Cefaclor however has a Cl group at position C-3 which gives it better binding to PBP and thus better antimicrobial activity. There is not an agreement on classifying cefaclor as a first generation cephalosporin because of the Cl group at the C-3 position and therefore its improved activity, but it is often classified as such because of its C-7 side chain which is more related to the first generation than the second. All of the first generation cephalosporins have an α-amino group at position C-7. This structure makes them vulnerable to hydrolysis by β-lactamases. | 1 | Applied and Interdisciplinary Chemistry |
Diffuse correlation spectroscopy (DCS) is a type of medical imaging and optical technique that utilizes near-infrared light to directly and non-invasively measure tissue blood flow. The imaging modality was created by David Boas and Arjun Yodh in 1995.
Blood flow is one the most important factors affecting the delivery of oxygen and other nutrients to tissues. Abnormal blood flow is associated with many diseases such as stroke and cancer. Tumors from cancer can generate abnormal tumor blood flow compared to the surrounding tissue. Current treatments attempt to decrease blood flow to cancer cells. Therefore, there is an urgent need for a way to measure blood flow. However, blood flow is difficult to measure because of sensitivity and stability of the measurement as it depends on magnitude of flow, location, and the diameter of individual vessels.
Current imaging modalities used to measure blood flow include Doppler ultrasound, PET, and MRI. Doppler ultrasound is limited to large vessels. PET requires arterial blood sampling and exposure to ionizing radiation. MRI cannot be used for patients with pacemakers and those with metal implants. All together, these imaging modalities have large and costly instrumentation and are not conducive to continuous measurements.
With these considerations in mind, the first methodology used to measure blood flow is near-infrared spectroscopy (NIRS). It is based on a well known spectral window that exists in the near-infrared (NIR, 700-900 nm) where tissue absorption is relatively low so that light can penetrate into deep/thick volumes of tissue, up to several centimeters. It provides a fast and portable alternative to measure deep tissue hemodynamics. However, it has a poor spatial resolution and is a ‘static’ method. This means that it measures the relatively slow variation in tissue absorption and scattering. In other words, it measures the changes in the amount of scattering rather than the motion of the scatter.
This led to the ‘dynamic’ NIRS technique or Diffuse correlation spectroscopy. It measures the motions of the scatters while also maintaining the advantages of NIRS. The primary moving scatterers are red blood cells. The main advantages of this method is no ionizing radiation, no contrast agents, high temporal resolution, and large penetration depth. The utility of DCS technology has been demonstrated in tumors, brains, and skeletal muscles. The general approach with DCS is that the temporal statistics of the fluctuations of the scattered light within a speckle area or pixel is monitored. Then, the electric field temporal autocorrelation function is measured. A model for photon propagation through tissues, the measured autocorrelation signal is used to determine the motion of blood flow. | 0 | Theoretical and Fundamental Chemistry |
Factors that influence the reaction rate are the nature of the reaction, concentration, pressure, reaction order, temperature, solvent, electromagnetic radiation, catalyst, isotopes, surface area, stirring, and diffusion limit. Some reactions are naturally faster than others. The number of reacting species, their physical state (the particles that form solids move much more slowly than those of gases or those in solution), the complexity of the reaction and other factors can greatly influence the rate of a reaction.
Reaction rate increases with concentration, as described by the rate law and explained by collision theory. As reactant concentration increases, the frequency of collision increases. The rate of gaseous reactions increases with pressure, which is, in fact, equivalent to an increase in the concentration of the gas. The reaction rate increases in the direction where there are fewer moles of gas and decreases in the reverse direction. For condensed-phase reactions, the pressure dependence is weak.
The order of the reaction controls how the reactant concentration (or pressure) affects the reaction rate.
Usually conducting a reaction at a higher temperature delivers more energy into the system and increases the reaction rate by causing more collisions between particles, as explained by collision theory. However, the main reason that temperature increases the rate of reaction is that more of the colliding particles will have the necessary activation energy resulting in more successful collisions (when bonds are formed between reactants). The influence of temperature is described by the Arrhenius equation. For example, coal burns in a fireplace in the presence of oxygen, but it does not when it is stored at room temperature. The reaction is spontaneous at low and high temperatures but at room temperature, its rate is so slow that it is negligible. The increase in temperature, as created by a match, allows the reaction to start and then it heats itself because it is exothermic. That is valid for many other fuels, such as methane, butane, and hydrogen.
Reaction rates can be independent of temperature (non-Arrhenius) or decrease with increasing temperature (anti-Arrhenius). Reactions without an activation barrier (for example, some radical reactions), tend to have anti-Arrhenius temperature dependence: the rate constant decreases with increasing temperature.
Many reactions take place in solution and the properties of the solvent affect the reaction rate. The ionic strength also has an effect on the reaction rate.
Electromagnetic radiation is a form of energy. As such, it may speed up the rate or even make a reaction spontaneous as it provides the particles of the reactants with more energy. This energy is in one way or another stored in the reacting particles (it may break bonds, and promote molecules to electronically or vibrationally excited states...) creating intermediate species that react easily. As the intensity of light increases, the particles absorb more energy and hence the rate of reaction increases. For example, when methane reacts with chlorine in the dark, the reaction rate is slow. It can be sped up when the mixture is put under diffused light. In bright sunlight, the reaction is explosive.
The presence of a catalyst increases the reaction rate (in both the forward and reverse reactions) by providing an alternative pathway with a lower activation energy. For example, platinum catalyzes the combustion of hydrogen with oxygen at room temperature.
The kinetic isotope effect consists of a different reaction rate for the same molecule if it has different isotopes, usually hydrogen isotopes, because of the relative mass difference between hydrogen and deuterium.
In reactions on surfaces, which take place, for example, during heterogeneous catalysis, the rate of reaction increases as the surface area does. That is because more particles of the solid are exposed and can be hit by reactant molecules.
Stirring can have a strong effect on the rate of reaction for heterogeneous reactions.
Some reactions are limited by diffusion. All the factors that affect a reaction rate, except for concentration and reaction order, are taken into account in the reaction rate coefficient (the coefficient in the rate equation of the reaction). | 0 | Theoretical and Fundamental Chemistry |
For an incident plane wave at a single frequency (and the angular frequency ) on a crystal, the diffracted waves from the crystal can be thought as the sum of outgoing plane waves from the crystal. (In fact, any wave can be represented as the sum of plane waves, see Fourier Optics.) The incident wave and one of plane waves of the diffracted wave are represented as
where and are wave vectors for the incident and outgoing plane waves, is the position vector, and is a scalar representing time, and and are initial phases for the waves. For simplicity we take waves as scalars here, even though the main case of interest is an electromagnetic field, which is a vector. We can think these scalar waves as components of vector waves along a certain axis (x, y, or z axis) of the Cartesian coordinate system.
The incident and diffracted waves propagate through space independently, except at points of the lattice of the crystal, where they resonate with the oscillators, so the phases of these waves must coincide. At each point of the lattice , we have
or equivalently, we must have
for some integer , that depends on the point . Since this equation holds at , at some integer . So
(We still use instead of since both the notations essentially indicate some integer.) By rearranging terms, we get
Now, it is enough to check that this condition is satisfied at the primitive vectors (which is exactly what the Laue equations say), because, at any lattice point , we have
where is the integer . The claim that each parenthesis, e.g. , is to be a multiple of (that is each Laue equation) is justified since otherwise does not hold for any arbitrary integers .
This ensures that if the Laue equations are satisfied, then the incoming and outgoing (diffracted) wave have the same phase at each point of the crystal lattice, so the oscillations of atoms of the crystal, that follows the incoming wave, can at the same time generate the outgoing wave at the same phase of the incoming wave. | 0 | Theoretical and Fundamental Chemistry |
Aspirin is an NSAID used to treat inflammation and pain. Overdoses or treatments in conjunction with other NSAIDs can produce additive effects, which can lead to increased oxidative stress and ROS activity. Chronic exposure to aspirin can lead to CNS toxicity and eventually affect respiratory function. | 1 | Applied and Interdisciplinary Chemistry |
Krypton-85 (Kr) is a radioisotope of krypton.
Krypton-85 has a half-life of 10.756 years and a maximum decay energy of 687 keV. It decays into stable rubidium-85. Its most common decay (99.57%) is by beta particle emission with maximum energy of 687 keV and an average energy of 251 keV. The second most common decay (0.43%) is by beta particle emission (maximum energy of 173 keV) followed by gamma ray emission (energy of 514 keV). Other decay modes have very small probabilities and emit less energetic gamma rays. Krypton-85 is mostly synthetic, though it is produced naturally in trace quantities by cosmic ray spallation.
In terms of radiotoxicity, 440 Bq of Kr is equivalent to 1 Bq of radon-222, without considering the rest of the radon decay chain. | 0 | Theoretical and Fundamental Chemistry |
A simple container (U-tube) is filled with a solid or catalyst. This sample vessel is positioned in a furnace with temperature control equipment. A thermocouple is placed in the solid for temperature measurement. The air originally present in the container is flushed out with an inert gas (nitrogen, argon). Flow controllers are used to add hydrogen (for example, 10% hydrogen in nitrogen). The composition of the gaseous mixture is measured at the exit of the sample container with appropriate detectors (thermal conductivity detector, mass spectrometer). Now, the sample in the oven is heated up on predefined values. Heating rates are usually between 1 K/min and 20 K/min. If a reduction takes place at a certain temperature, hydrogen is consumed, which is recorded by the detector. In practice the production of water is a more accurate way of measuring the reduction. This is due to the potential for varying hydrogen concentrations at the inlet, so the decrease in this number may not be precise, however as the starting concentration of water will be zero, any increase can be measured more accurately. | 0 | Theoretical and Fundamental Chemistry |
Calculation of radiative heat transfer between groups of objects, including a cavity or surroundings requires solution of a set of simultaneous equations using the radiosity method. In these calculations, the geometrical configuration of the problem is distilled to a set of numbers called view factors, which give the proportion of radiation leaving any given surface that hits another specific surface. These calculations are important in the fields of solar thermal energy, boiler and furnace design and raytraced computer graphics.
The net radiative heat transfer from one surface to another is the radiation leaving the first surface for the other minus that arriving from the second surface.
Formulas for radiative heat transfer can be derived for more particular or more elaborate physical arrangements, such as between parallel plates, concentric spheres and the internal surfaces of a cylinder. | 0 | Theoretical and Fundamental Chemistry |
ρ: Actual particle density (g/cm)
ρ: Gas or sample matrix density (g/cm)
r: Least-squares coefficient of determination. The closer this value is to 1.0, the better the data fit to a hyperplane representing the relationship between the response variable and a set of covariate variables. A value equal to 1.0 indicates all data fit perfectly within the hyperplane.
λ: Gas mean free path (cm)
D: Mass-median-diameter (MMD). The log-normal distribution mass median diameter. The MMD is considered to be the average particle diameter by mass.
σ: Geometric standard deviation. This value is determined mathematically by the equation:
:σ = D/D = D/D
The value of σ determines the slope of the least-squares regression curve.
α: Relative standard deviation or degree of polydispersity. This value is also determined mathematically. For values less than 0.1, the particulate sample can be considered to be monodisperse.
:α = σ/D
Re : Particle Reynolds Number.
In contrast to the large numerical values noted for flow Reynolds number, particle Reynolds number for fine particles in gaseous mediums is typically less than 0.1.
Re : Flow Reynolds number.
Kn: Particle Knudsen number. | 0 | Theoretical and Fundamental Chemistry |
Size exclusion chromatography applications for separating macromolecules based on subtle differences in size typically use resins with large and varied pore sizes in long chromatography columns. However, for buffer exchange and desalting applications, it is mainly the maximum effective pore size (exclusion limit or molecular weight cut off (MWCO) of the resin) that determines the size of molecules that can be separated. Molecules that are significantly smaller than the MWCO penetrate into the pores of the resin, while molecules larger than the MWCO are unable to enter the pores and remain together in the void volume of the column. By passing samples through a column resin bed with sufficient length and volume, macromolecules can be fully separated from small molecules that travel a greater distance though the pores of the resin bed. No significant separation of molecules larger than the exclusion limit occurs.
In order for the desired macromolecules to remain in the void volume, resins with very small pores sizes must be utilized. For typical desalting and buffer exchange applications choosing a resin with a molecular weight cut off between 5 and 10KDa is usually best. For other applications, such as separating peptides from full-sized proteins, resins with larger exclusion limits may be necessary. The macromolecular components are recovered in the buffer used to pre-equilibrate the gel-filtration matrix, while the small molecules can be collected in a later fraction volume or be left trapped in the resin. One important feature to note when choosing a resin is that the small molecules targeted for removal must be several times smaller than the MWCO for proper separation. | 0 | Theoretical and Fundamental Chemistry |
Transcription-translation coupling is a mechanism of gene expression regulation in which synthesis of an mRNA (transcription) is affected by its concurrent decoding (translation). In prokaryotes, mRNAs are translated while they are transcribed. This allows communication between RNA polymerase, the multisubunit enzyme that catalyzes transcription, and the ribosome, which catalyzes translation. Coupling involves both direct physical interactions between RNA polymerase and the ribosome ("expressome" complexes), as well as ribosome-induced changes to the structure and accessibility of the intervening mRNA that affect transcription ("attenuation" and "polarity"). | 1 | Applied and Interdisciplinary Chemistry |
In physics, the Young–Laplace equation () is an algebraic equation that describes the capillary pressure difference sustained across the interface between two static fluids, such as water and air, due to the phenomenon of surface tension or wall tension, although use of the latter is only applicable if assuming that the wall is very thin. The Young–Laplace equation relates the pressure difference to the shape of the surface or wall and it is fundamentally important in the study of static capillary surfaces. It is a statement of normal stress balance for static fluids meeting at an interface, where the interface is treated as a surface (zero thickness):
where is the Laplace pressure, the pressure difference across the fluid interface (the exterior pressure minus the interior pressure), is the surface tension (or wall tension), is the unit normal pointing out of the surface, is the mean curvature, and and are the principal radii of curvature. Note that only normal stress is considered, because a static interface is possible only in the absence of tangential stress.
The equation is named after Thomas Young, who developed the qualitative theory of surface tension in 1805, and Pierre-Simon Laplace who completed the mathematical description in the following year. It is sometimes also called the Young–Laplace–Gauss equation, as Carl Friedrich Gauss unified the work of Young and Laplace in 1830, deriving both the differential equation and boundary conditions using Johann Bernoulli's virtual work principles. | 1 | Applied and Interdisciplinary Chemistry |
Cavendish inherited two fortunes that were so large that Jean Baptiste Biot called him "the richest of all the savants and the most knowledgeable of the rich". At his death, Cavendish was the largest depositor in the Bank of England. He was a shy man who was uncomfortable in society and avoided it when he could. He could speak to only one person at a time, and only if the person were known to him and male. He conversed little, always dressed in an old-fashioned suit, and developed no known deep personal attachments outside his family. Cavendish was taciturn and solitary and regarded by many as eccentric. He communicated with his female servants only by notes. By one account, Cavendish had a back staircase added to his house to avoid encountering his housekeeper, because he was especially shy of women. The contemporary accounts of his personality have led some modern commentators, such as Oliver Sacks, to speculate that he was autistic.
His only social outlet was the Royal Society Club, whose members dined together before weekly meetings. Cavendish seldom missed these meetings, and was profoundly respected by his contemporaries. However, his shyness made conversation difficult; guests were advised to wander close to him and then speak as if "into vacancy. If their remarks were scientifically worthy, they might receive a mumbled reply". Cavendish was more likely not to reply at all. Cavendishs religious views were also considered eccentric for his time. He was considered to be agnostic. As his biographer, George Wilson, comments, "As to Cavendishs religion, he was nothing at all."
The arrangement of his residence reserved only a fraction of space for personal comfort as his library was detached, the upper rooms and lawn were for astronomical observation and his drawing room was a laboratory with a forge in an adjoining room. He also enjoyed collecting fine furniture, exemplified by his purchase of a set of "ten inlaid satinwood chairs with matching cabriole legged sofa".
Because of his asocial and secretive behaviour, Cavendish often avoided publishing his work, and much of his findings were not told even to his fellow scientists. In the late nineteenth century, long after his death, James Clerk Maxwell looked through Cavendishs papers and found observations and results for which others had been given credit. Examples of what was included in Cavendishs discoveries or anticipations were Richters law of reciprocal proportions, Ohms law, Daltons law of partial pressures, principles of electrical conductivity (including Coulombs law), and Charles's Law of gases. A manuscript "Heat", tentatively dated between 1783 and 1790, describes a "mechanical theory of heat". Hitherto unknown, the manuscript was analysed in the early 21st century. Historian of science Russell McCormmach proposed that "Heat" is the only 18th-century work prefiguring thermodynamics. Theoretical physicist Dietrich Belitz concluded that in this work Cavendish "got the nature of heat essentially right".
As Cavendish performed his famous density of the Earth experiment in an outbuilding in the garden of his Clapham Common estate, his neighbours would point out the building and tell their children that it was where the world was weighed. In honour of Henry Cavendishs achievements and due to an endowment granted by Henrys relative William Cavendish, 7th Duke of Devonshire, the University of Cambridges physics laboratory was named the Cavendish Laboratory by Maxwell, the first Cavendish Professor of Physics and an admirer of Cavendishs work. | 1 | Applied and Interdisciplinary Chemistry |
Research in photocatalysis again paused until 1964, when V.N. Filimonov investigated isopropanol photooxidation from ZnO and ; while in 1965 Kato and Mashio, Doerffler and Hauffe, and Ikekawa et al. (1965) explored oxidation/photooxidation of and organic solvents from ZnO radiance. In 1970, Formenti et al. and Tanaka and Blyholde observed the oxidation of various alkenes and the photocatalytic decay of NO, respectively.
A breakthrough occurred in 1972, when Akira Fujishima and Kenichi Honda discovered that electrochemical photolysis of water occurred when a electrode irradiated with ultraviolet light was electrically connected to a platinum electrode. As the ultraviolet light was absorbed by the electrode, electrons flowed from the anode to the platinum cathode where hydrogen gas was produced. This was one of the first instances of hydrogen production from a clean and cost-effective source, as the majority of hydrogen production comes from natural gas reforming and gasification. Fujishimas and Hondas findings led to other advances. In 1977, Nozik discovered that the incorporation of a noble metal in the electrochemical photolysis process, such as platinum and gold, among others, could increase photoactivity, and that an external potential was not required. Wagner and Somorjai (1980) and Sakata and Kawai (1981) delineated hydrogen production on the surface of strontium titanate (SrTiO) via photogeneration, and the generation of hydrogen and methane from the illumination of and PtO in ethanol, respectively.
For many decades photocatalysis had not been developed for commercial purposes. However, in 2023 multiple patents were granted to a U.S. company, (Pure-Light Technologies, Inc.) that has developed various formulas and processes that allow for widespread commercialization for VOC reduction and germicidal action. Chu et al. (2017) assessed the future of electrochemical photolysis of water, discussing its major challenge of developing a cost-effective, energy-efficient photoelectrochemical (PEC) tandem cell, which would, “mimic natural photosynthesis". | 0 | Theoretical and Fundamental Chemistry |
Inhibitors of PSII are used as herbicides. There are two main chemical families, the triazines derived from cyanuric chloride of which atrazine and simazine are the most commonly used and the aryl ureas which include chlortoluron and diuron (DCMU). | 0 | Theoretical and Fundamental Chemistry |
The pH dependence is given by the factor −0.059m/n per pH unit, where m relates to the number of protons in the equation, and n the number of electrons exchanged. Electrons are always exchanged in electrochemistry, but not necessarily protons. If there is no proton exchange in the reaction equilibrium, the reaction is said to be pH-independent. This means that the values for the electrochemical potential rendered in a redox half-reaction, whereby the elements in question change oxidation states are the same whatever the pH conditions under which the procedure is carried out.
The Frost diagram is also a useful tool for comparing the trends of standard potentials (slope) of acidic and basic solutions. The pure, neutral element transitions to different compounds depending whether the species is in acidic and basic pHs. Though the value and amount of oxidation states remain unchanged, the free energies can vary greatly. The Frost diagram allows the superimposition of acidic and basic graphs for easy and convenient comparison. | 0 | Theoretical and Fundamental Chemistry |
Impellers in agitated tanks are used to mix fluids or slurry in the tank. This can be used to combine materials in the form of solids, liquids and gas. Mixing the fluids in a tank is very important if there are gradients in conditions such as temperature or concentration.
There are two types of impellers, depending on the flow regime created (see figure):
* Axial flow impeller
* Radial flow impeller
Radial flow impellers impose essentially shear stress to the fluid, and are used, for example, to mix immiscible liquids or in general when there is a deformable interface to break. Another application of radial flow impellers is the mixing of very viscous fluids.
Axial flow impellers impose essentially bulk motion and are used on homogenization processes, in which increased fluid volumetric flow rate is important.
Impellers can be further classified principally into three sub-types:
*Propeller
*Paddles
*Turbines | 1 | Applied and Interdisciplinary Chemistry |
The eastern blot, or eastern blotting, is a biochemical technique used to analyze protein post-translational modifications including the addition of lipids, phosphates, and glycoconjugates. It is most often used to detect carbohydrate epitopes. Thus, eastern blot can be considered an extension of the biochemical technique of western blot. Multiple techniques have been described by the term "eastern blot(ting)", most use phosphoprotein blotted from sodium dodecyl sulfate–polyacrylamide gel electrophoresis (SDS-PAGE) gel on to a polyvinylidene fluoride or nitrocellulose membrane. Transferred proteins are analyzed for post-translational modifications using probes that may detect lipids, carbohydrate, phosphorylation or any other protein modification. Eastern blotting should be used to refer to methods that detect their targets through specific interaction of the post-translational modifications and the probe, distinguishing them from a standard far-western blot. In principle, eastern blotting is similar to lectin blotting (i.e., detection of carbohydrate epitopes on proteins or lipids). | 0 | Theoretical and Fundamental Chemistry |
The mitochondria of many higher plants contain self-replicating, extra-chromosomal linear or circular DNA molecules which have been considered to be plasmids. These can range from 0.7 kb to 20 kb in size. The plasmids have been generally classified into two categories- circular and linear. Circular plasmids have been isolated and found in many different plants, with those in Vicia faba and Chenopodium album being the most studied and whose mechanism of replication is known. The circular plasmids can replicate using the θ model of replication (as in Vicia faba) and through rolling circle replication (as in C.album). Linear plasmids have been identified in some plant species such as Beta vulgaris, Brassica napus, Zea mays, etc. but are rarer than their circular counterparts.
The function and origin of these plasmids remains largely unknown. It has been suggested that the circular plasmids share a common ancestor, some genes in the mitochondrial plasmid have counterparts in the nuclear DNA suggesting inter-compartment exchange. Meanwhile, the linear plasmids share structural similarities such as invertrons with viral DNA and fungal plasmids, like fungal plasmids they also have low GC content, these observations have led to some hypothesizing that these linear plasmids have viral origins, or have ended up in plant mitochondria through horizontal gene transfer from pathogenic fungi. | 1 | Applied and Interdisciplinary Chemistry |
The SI unit of kerma is the gray (Gy) (or joule per kilogram), the same as the unit of absorbed dose. However, kerma can be different from absorbed dose, depending on the energies involved. This is because ionization energy is not accounted for. While kerma approximately equals absorbed dose at low energies, kerma is much higher than absorbed dose at higher energies, because some energy escapes from the absorbing volume in the form of bremsstrahlung (X-rays) or fast-moving electrons, and is not counted as absorbed dose. | 0 | Theoretical and Fundamental Chemistry |
The Chemical Society was a scientific society formed in 1841 (then named the Chemical Society of London) by 77 scientists as a result of increased interest in scientific matters. Chemist Robert Warington was the driving force behind its creation. | 1 | Applied and Interdisciplinary Chemistry |
Most countries have legislation or pressure vessel codes which requires vessels to be regularly tested, for example every two years (with a visual inspection annually) for high pressure gas cylinders and every five or ten years for lower pressure ones such as used in fire extinguishers. Gas cylinders which fail are normally destroyed as part of the testing protocol to avoid the dangers inherent in them being subsequently used.
These common US standard gas cylinders have the following requirements:
* DOT-3AL gas cylinders must be tested every 5 years and have an unlimited life.
* DOT-3HT gas cylinders must be tested every 3 years and have a 24-year life.
* DOT-3AA gas cylinders must be tested every 5 years and have an unlimited life. (Unless stamped with a star (*) in which case the cylinder meets certain specifications and can have a 10-year hydrostatic test life).
Typically organizations such as DOT PHMSA, ISO, ASTM and ASME specify the guidelines for the different types of pressure vessels. | 1 | Applied and Interdisciplinary Chemistry |
Walsh diagrams were first introduced by A.D. Walsh, a British chemistry professor at the University of Dundee, in a series of ten papers in one issue of the Journal of the Chemical Society. Here, he aimed to rationalize the shapes adopted by polyatomic molecules in the ground state as well as in excited states, by applying theoretical contributions made by Mulliken. Specifically, Walsh calculated and explained the effect of changes in the shape of a molecule on the energy of molecular orbitals. Walsh diagrams are an illustration of such dependency, and his conclusions are what are referred to as the "rules of Walsh."
In his publications, Walsh showed through multiple examples that the geometry adopted by a molecule in its ground state primarily depends on the number of its valence electrons. He himself acknowledged that this general concept was not novel, but explained that the new data available to him allowed the previous generalizations to be expanded upon and honed. He also noted that Mulliken had previously attempted to construct a correlation diagram for the possible orbitals of a polyatomic molecule in two different nuclear configurations, and had even tried to use this diagram to explain shapes and spectra of molecules in their ground and excited states. However, Mulliken was unable to explain the reasons for the rises and falls of certain curves with increases in angle, thus Walsh claimed "his diagram was either empirical or based upon unpublished computations." | 0 | Theoretical and Fundamental Chemistry |
A plasma arc furnace (PAF) uses plasma torches instead of graphite electrodes. Each of these torches has a casing with a nozzle and axial tubing for feeding a plasma-forming gas (either nitrogen or argon) and a burnable cylindrical graphite electrode within the tubing. Such furnaces can be called plasma arc melt (PAM) furnaces; they are used extensively in the titanium-melting industry and similar specialty metal industries. | 1 | Applied and Interdisciplinary Chemistry |
The first compound of the homolog row of nitriles, the nitrile of formic acid, hydrogen cyanide was first synthesized by C. W. Scheele in 1782. In 1811 J. L. Gay-Lussac was able to prepare the very toxic and volatile pure acid.
Around 1832 benzonitrile, the nitrile of benzoic acid, was prepared by Friedrich Wöhler and Justus von Liebig, but due to minimal yield of the synthesis neither physical nor chemical properties were determined nor a structure suggested. In 1834 Théophile-Jules Pelouze synthesized propionitrile, suggesting it to be an ether of propionic alcohol and hydrocyanic acid.
The synthesis of benzonitrile by Hermann Fehling in 1844 by heating ammonium benzoate was the first method yielding enough of the substance for chemical research.
Fehling determined the structure by comparing his results to the already known synthesis of hydrogen cyanide by heating ammonium formate. He coined the name "nitrile" for the newfound substance, which became the name for this group of compounds. | 0 | Theoretical and Fundamental Chemistry |
Particle Display produces higher yields of higher affinity aptamers in less rounds than conventional selection methods. In this method, libraries of aptamers are separated into aptamer particles and separated by fluorescence-activated cell sorting based on affinity. Only the highest affinity aptamer particles are isolated and sequenced into aptamers. This is an affinity-base selection process that is more efficient than selection methods such as SELEX. Particle display may be a reliable aptamer generation method for E-AB sensors due to the high affinity and specificity of target binding.
Researchers tackled the challenge of isolating high-affinity aptamers in conventional SELEX by introducing Particle Display System (PDS). Using parallel single-molecule emulsion polymerase chain reaction (PCR) for monoclonal aptamer screening, PDS employs emulsion PCR and droplet digital PCR to prevent by-product propagation and preserve rare high-affinity sequences. The one-particle-one-sequence nature of PDS transforms the DNA-target interaction into a particle-target interaction, enabling swift confirmation of aptamer candidate affinities through fluorescence-activated cell sorting or flow cytometry assays. Unlike conventional SELEX, PDS efficiently segregates aptamers, providing a streamlined and effective method for identifying and isolating high-affinity binders. PDS significantly enhances the efficiency of enriching high-affinity aptamers, achieving this in a single round of screening.
Particle display yields higher quantities of higher affinity aptamers in fewer rounds compared to conventional selection methods. This method separates aptamer libraries into aptamer particles and employs fluorescence-activated cell sorting to isolate particles based on affinity. Only the highest affinity aptamer particles are isolated and sequenced into aptamers. This affinity-based selection process is more efficient than methods such as SELEX. Particle display may be a reliable aptamer generation method for E-AB sensors due to the high affinity and specificity of target binding | 0 | Theoretical and Fundamental Chemistry |
The p-i concept represents an alternative explanation of immune stimulation by drugs in DHR. It implies that no formation of a new antigen (hapten-protein complex) is needed to elicit an immune activation: T cells are stimulated by the drug binding to immune receptors directly, which leads to conformational changes of HLA and/or TCR as well as to signalling by the TCR-CD3 complex: The p-i concept was created and formulated by Prof. emeritus Werner J. Pichler in early 2000, based on studies with drug specific T cell clones, derived from patients with DHR. The underlying investigations were performed by various PhD students in Pichler's research group at the Inselspital/University of Bern in Bern, Switzerland. The essential, initial finding was that T cells from patients with DH showed a specific reaction to the incriminated drug in vitro (proliferation, cytotoxicity, cytokine release), and that this drug dependent stimulation of immune cells relied on labile (=non-covalent) binding of drugs to cell surface proteins, namely on antigen presenting cells and T cells, which were present in the cell culture.
That a non-covalent, and drug binding was sufficient for T cell stimulation was shown by three main findings underlying the lability of drug bindings: washing the cells in the cell culture (APCs, T cells) effectively removed the drugs, and the cells could not be stimulated any longer; This means that the drug was binding in a labile way, which was possible with the inert, parent compound; Transformation to a reactive metabolite was not needed to elicit a reaction: blocking processing or metabolism by drugs did not interfere with reactivity and even fixing the antigen presenting cells by glutaraldehyde failed to eliminate T cell reactivity; And lastly by the speed of reaction: the reaction occurred within minutes, before metabolism could happen; addition of the drug to the cell culture containing drug reactive T cells resulted in a Ca influx in drug specific T cells within less than a minute.
Over the years this p-i concept could be confirmed by many functional and structural studies including crystallography which localized the precise region of the immune receptor (HLA-B*57:01, TCRVβ20, etc.), to which a particular drug binds. Since crucial and highly sensitive molecules of T cell activation are targeted, complex and highly variable immunological consequences can develop: different types of T cells are activated to a variable degree, leading in inflammatory consequences with a highly polymorphic clinical picture of acute symptoms, followed by different late appearing complications. | 1 | Applied and Interdisciplinary Chemistry |
I is not deliberately produced for any practical purposes. However, its long half-life and its relative mobility in the environment have made it useful for a variety of dating applications. These include identifying older groundwaters based on the amount of natural I (or its Xe decay product) present, as well as identifying younger groundwaters by the increased anthropogenic I levels since the 1960s. | 0 | Theoretical and Fundamental Chemistry |
F number is a correlation number used in the analysis of polycyclic aromatic hydrocarbons (PAHs) as a descriptor of their hydrophobicity and molecular size. It was proposed by Robert Hurtubise and co-workers in 1977. | 0 | Theoretical and Fundamental Chemistry |
Mixed liquor suspended solids (MLSS) is the concentration of suspended solids, in an aeration tank during the activated sludge process, which occurs during the treatment of waste water. The units MLSS is primarily measured in milligram per litre (mg/L), but for activated sludge its mostly measured in gram per litre [g/L] which is equal to kilogram per cubic metre [kg/m3]. Mixed liquor is a combination of raw or unsettled wastewater or pre-settled wastewater and activated sludge within an aeration tank. MLSS consists mostly of microorganisms and non-biodegradable suspended matter. MLSS is an important part of the activated sludge process to ensure that there is a sufficient quantity of active biomass available to consume the applied quantity of organic pollutant at any time. This is known as the food to microorganism ratio, more commonly notated as the F/M ratio. By maintaining this ratio at the appropriate level the biomass will consume high percentages of the food. This minimizes the loss of residual food in the treated effluent. In simple terms, the more the biomass consumes the lower the biochemical oxygen demand (BOD) will be in the discharge. It is important that MLSS removes COD and BOD in order to purify water for clean surface waters, and subsequently clean drinking water and hygiene. Raw sewage enters in the water treatment process with a concentration of sometimes several hundred mg/L of BOD. Upon being treated by screening, pre-settling, activated sludge processes or other methods of treatment, the concentration of BOD in water can be lowered to less than 2 mg/L, which is considered to be clean, safe to discharge to surface waters or to reuse water.
The total weight of MLSS within an aeration tank can be calculated by multiplying the concentration of MLSS (kg/m3) in the aeration tank by the tank volume (m3). | 0 | Theoretical and Fundamental Chemistry |
In its anionic form, the green chromophore has an absorption maxima at 506 nm and an emission maxima at 516 nm. It is formed autocatalytically from amino acids His-62, Tyr-63 and Gly-64. Immediately surrounding the chromophore there is a cluster of charged or polar amino acids as well as structural water molecules. Above the plane of the chromophore, there is a network of hydrogen bond interactions between Glu-144, His-194, Glu-212 and Gln-38. Arg-66 and Arg-91 participate in hydrogen bonding with the carbonyl oxygen of green Eos's imidazolinone moiety. The His-62 side chain lies in an unpolar environment. Conversion from the green to red form depends on the presence of a histidine in the first position of the tripeptide HYG that forms the chromophore. When this histidine residue is substituted with M, S, T or L, Eos only emits bright green light and no longer acts as a photoconvertible fluorescent protein. | 1 | Applied and Interdisciplinary Chemistry |
Iodine-129 (I) is a long-lived radioisotope of iodine that occurs naturally but is also of special interest in the monitoring and effects of man-made nuclear fission products, where it serves as both a tracer and a potential radiological contaminant. | 0 | Theoretical and Fundamental Chemistry |
An unnatural base pair (UBP) is a designed subunit (or nucleobase) of DNA that is created in a laboratory and does not occur in nature. In 2012, a group of American scientists led by Floyd Romesberg, a chemical biologist at the Scripps Research Institute in San Diego, California, published that his team had designed two unnatural base pairs
named d5SICS and dNaM. More technically, these artificial nucleotides bearing hydrophobic nucleobases feature two fused aromatic rings that form a d5SICS–dNaM complex or base pair in DNA. In 2014, the same team reported that they had synthesized a plasmid containing natural T-A and C-G base pairs along with the best-performing UBP Romesbergs laboratory had designed and inserted it into cells of the common bacterium E. coli, which successfully replicated the unnatural base pairs through multiple generations. This is the first known example of a living organism passing along an expanded genetic code to subsequent generations. This was in part achieved by the addition of a supportive algal gene that expresses a nucleotide triphosphate transporter which efficiently imports the triphosphates of both d5SICSTP and dNaMTP into E. coli' bacteria. Then, the natural bacterial replication pathways use them to accurately replicate the plasmid containing d5SICS–dNaM.
The successful incorporation of a third base pair is a significant breakthrough toward the goal of greatly expanding the number of amino acids which can be encoded by DNA, from the existing 20 amino acids to a theoretically possible 172, thereby expanding the potential for living organisms to produce novel proteins. Earlier, the artificial strings of DNA did not encode for anything, but scientists speculated they could be designed to manufacture new proteins which could have industrial or pharmaceutical uses. Transcription of DNA containing unnatural base pairs and translation of corresponding mRNA were actually achieved recently. In November 2017, the same team at the Scripps Research Institute that first introduced two extra nucleobases into bacterial DNA reported having constructed a semi-synthetic E. coli bacteria able to make proteins using such DNA. Its DNA contained six different nucleobases: four canonical and two artificially added, dNaM and dTPT3 (these two form a pair). The bacteria had two corresponding RNA bases included in two new codons, additional tRNAs recognizing these new codons (these tRNAs also contained two new RNA bases within their anticodons) and additional amino acids, enabling the bacteria to synthesize "unnatural" proteins.
Another demonstration of UBPs were achieved by Ichiro Hiraos group at RIKEN institute in Japan. In 2002, they developed an unnatural base pair between 2-amino-8-(2-thienyl)purine (s) and pyridine-2-one (y) that functions in vitro in transcription and translation, for the site-specific incorporation of non-standard amino acids into proteins. In 2006, they created 7-(2-thienyl)imidazo[4,5-b]pyridine (Ds) and pyrrole-2-carbaldehyde (Pa) as a third base pair for replication and transcription. Afterward, Ds and 4-[3-(6-aminohexanamido)-1-propynyl]-2-nitropyrrole (Px) was discovered as a high fidelity pair in PCR amplification. In 2013, they applied the Ds-Px pair to DNA aptamer generation by in vitro' selection (SELEX) and demonstrated the genetic alphabet expansion significantly augment DNA aptamer affinities to target proteins. | 1 | Applied and Interdisciplinary Chemistry |
As early as the 1920s, the concept of using hot water and alkali catalysts to produce oil out of biomass was proposed. In 1939, U.S. patent 2,177,557, described a two-stage process in which a mixture of water, wood chips, and calcium hydroxide is heated in the first stage at temperatures in a range of , with the pressure "higher than that of saturated steam at the temperature used." This produces "oils and alcohols" which are collected. The materials are then subjected in a second stage to what is called "dry distillation", which produces "oils and ketones". Temperatures and pressures for this second stage are not disclosed.
These processes were the foundation of later HTL technologies that attracted research interest especially during the 1970s oil embargo. It was around that time that a high-pressure (hydrothermal) liquefaction process was developed at the Pittsburgh Energy Research Center (PERC) and later demonstrated (at the 100 kg/h scale) at the Albany Biomass Liquefaction Experimental Facility at Albany, Oregon, US. In 1982, Shell Oil developed the HTU™ process in the Netherlands. Other organizations that have previously demonstrated HTL of biomass include Hochschule für Angewandte Wissenschaften Hamburg, Germany, SCF Technologies in Copenhagen, Denmark, EPA’s Water Engineering Research Laboratory, Cincinnati, Ohio, USA, and Changing World Technology Inc. (CWT), Philadelphia, Pennsylvania, USA. Today, technology companies such as [http://www.licella.com.au Licella/Ignite Energy Resources] (Australia), [https://arbiosbiotech.com Arbios Biotech], a Licella/Canfor joint venture, [http://altacaenergy.com Altaca Energy] (Turkey), [https://circlianordic.com/ Circlia Nordic] (Denmark), [http://steeperenergy.com/ Steeper Energy] (Denmark, Canada) continue to explore the commercialization of HTL. Construction has begun in Teesside, UK, for a catalytic hydrothermal liquefaction plant that aims to process 80,000 tonnes per year of mixed plastic waste by 2022. | 0 | Theoretical and Fundamental Chemistry |
Spigot and sockets involve a normal pipe end, the spigot, being inserted into the socket or bell of another pipe or fitting with a seal being made between the two within the socket. Normal spigot and socket joints do not allow direct metal to metal contact with all forces being transmitted through the elastomeric seal. They can consequently flex and allow some degree of rotation, allowing pipes to shift and relieve stresses imposed by soil movement. The corollary is that unrestrained spigot and socket joints transmit essentially no compression or tension along the axis of the pipe and little shear. Any bends, tees or valves therefore require either a restrained joint or, more commonly, thrust blocks, which transmit the forces as compression into the surrounding soil.
A large number of different socket and seals exist. The most modern is the "push-joint" or "slip-joint", whereby the socket and rubber seal is designed to allow the pipe spigot to be, after lubrication, simply pushed into the socket. Push joints remain proprietary designs. Also available are locking gasket systems. These locking gasket systems allow the pipe to be pushed together but do not allow the joint to come apart without using a special tool or torch on the gasket.
The earliest spigot and socket cast iron pipes were jointed by filling the socket with a mixture of water, sand, iron filings and sal-ammoniac (ammonium chloride.) A gasket ring was pushed into the socket round the spigot to contain the mixture which was pounded into the socket with a caulking tool and then pointed off. This took several weeks to set and produced a completely rigid joint. Such pipe systems are often to be seen in nineteenth century churches in the heating system. | 1 | Applied and Interdisciplinary Chemistry |
With non-covalent imprinting, interaction forces between template molecule and functional monomer are the same as the interaction forces between the polymer matrix and analyte. The forces involved in this procedure can include hydrogen bonds, dipole dipole interactions, and induced dipole forces. This method is the most widely used approach to create MIPs due to easy preparation and the wide variety of functional monomers that can be bound to the template molecule. Among the functional groups, methacrylic acid is the most commonly used compound due to its ability to interact with other functional groups. Another way to alternate the non-covalent interaction between the template molecule and polymer is through the technique ‘bite and switch’ developed by Professor Sergey A. Piletsk<nowiki/>y and Sreenath Subrahmanyam. In this process, functional groups first non-covalently bond with the binding site, but during the rebinding step, the polymer matrix forms irreversible covalent bonds with the target molecule. | 0 | Theoretical and Fundamental Chemistry |
Hydrophobic membranes are often polydimethylsiloxane based where the actual separation mechanism is based on the solution-diffusion model described above.
Hydrophilic membranes are more widely available. The commercially most successful pervaporation membrane system to date is based on polyvinyl alcohol. More recently also membranes based on polyimide have become available. To overcome the intrinsic disadvantages of polymeric membrane systems ceramic membranes have been developed over the last decade. These ceramic membranes consist of nanoporous layers on top of a macroporous support. The pores must be large enough to let water molecules pass through and retain any other solvents that have a larger molecular size such as ethanol. As a result, a molecular sieve with a pore size of about 4 Å is obtained. The most widely available member of this class of membranes is that based on zeolite A.
Alternatively to these crystalline materials, the porous structure of amorphous silica layers can be tailored towards molecular selectivity. These membranes are fabricated by sol-gel chemical processes. Research into novel hydrophilic ceramic membranes has been focused on titania or zirconia. Very recently a break-through in hydrothermal stability has been achieved through the development of an organic-inorganic hybrid material. | 0 | Theoretical and Fundamental Chemistry |
The squirmer is a model for a spherical microswimmer swimming in Stokes flow. The squirmer model was introduced by James Lighthill in 1952 and refined and used to model Paramecium by John Blake in 1971.
Blake used the squirmer model to describe the flow generated by a carpet of beating short filaments called cilia on the surface of Paramecium. Today, the squirmer is a standard model for the study of self-propelled particles, such as Janus particles, in Stokes flow. | 1 | Applied and Interdisciplinary Chemistry |
NRC produces certified reference materials of biological tissues, isotopic standards, natural waters, sediments, supplements, and natural health products. With the exception of the ORMS, the river water CRM with elevated mercury, all materials contain natural levels of analytes in their native matrix.
* Biological tissues
** DOLT, dogfish liver for trace metals
** DORM, fish protein for trace metals
** LUTS, non-defatted lobster hepatopancreas for trace metals
** TORT, lobster hepatopancreas for trace metals
* Isotopic materials
** NIMS, natural inorganic mercury standard
** EMMS, isotopic methylmercury standard
* Natural waters
** CASS, near-shore seawater for trace metals
** MOOS, seawater for nutrients
** NASS, seawater for trace metals
** ORMS, river water for mercury
** SLEW, estuarine water for trace metals
** SLRS, river water for trace metals
* Sediments
** HISS and MESS, marine sediment for trace metals and major constituents
** PACS and SOPH, marine sediment for trace metals and major constituents
* Supplements and natural health products
** CACB, calcium carbonate for lead and cadmium
** FEBS, otolith for trace metals
** SELM, selenium-enriched yeast for selenium | 1 | Applied and Interdisciplinary Chemistry |
In molecular spectroscopy, the Birge–Sponer method or Birge–Sponer plot is a way to calculate the dissociation energy of a molecule. By observing transitions between as many vibrational energy levels as possible, for example through electronic or infrared spectroscopy, the difference between the energy levels, can be calculated. This sum will have a maximum at , representing the point of bond dissociation; summing over all the differences up to this point gives the total energy required to dissociate the molecule, i.e. to promote it from the ground state to an unbound state. This can be written:
where is the dissociation energy. If a Morse potential is assumed, plotting against should give a straight line, from which it is easy to extract from the intercept with the x-axis. In practice, such plots often give curves because of unaccounted anharmonicity in the potential; furthermore, the low population of the higher states (or the Franck–Condon principle) makes it difficult to experimentally obtain data at high values of . Thus the extrapolation can be inaccurate and only an upper limit for the value of the dissociation energy can be obtained.
This method takes its name from Raymond Thayer Birge and Hertha Sponer, the two physical chemists that developed it.
A detailed example may be found here. | 0 | Theoretical and Fundamental Chemistry |
In 1930, Degussa ceded 42.5 percent ownership of Degesch to IG Farben and 15 percent to Th. Goldschmidt AG, in exchange for the right to market pesticide products of those two companies through Degesch. Degussa retained managerial control.
While Degesch owned the rights to the brand name Zyklon and the patent on the packaging system, the chemical formula was owned by Degussa. Schlempe GmbH, which was 52 percent owned by Degussa, owned the rights to a process to extract hydrogen cyanide from waste products of sugar beet processing. This process was performed under license by two companies, Dessauer Werke and Kaliwerke Kolin, who also combined the resulting hydrogen cyanide with stabilizer from IG Farben and a cautionary agent from Schering AG to form the final product, which was packaged using equipment, labels, and canisters provided by Degesch. The finished goods were sent to Degesch, who forwarded the product to two companies that acted as distributors: Heerdt-Linger GmbH (Heli) of Frankfurt and Tesch & Stabenow (Testa) of Hamburg. Their territory was split along the Elbe river, with Heli handling clients to the west and south, and Testa those to the east. Degesch owned 51 percent of the shares of Heli, and until 1942 owned 55 percent of Testa.
Prior to World War II Degesch derived most of its Zyklon B profits from overseas sales, particularly in the United States, where it was produced under license by Roessler & Hasslacher prior to 1931 and by American Cyanamid from 1931 to 1943. From 1929, the United States Public Health Service used Zyklon B to fumigate freight trains and clothes of Mexican immigrants entering the United States. Uses in Germany included delousing clothing (often using a portable sealed chamber invented by Degesch in the 1930s) and fumigating ships, warehouses, and trains. By 1943, sales of Zyklon B accounted for 65 percent of Degesch's sales revenue and 70 percent of its gross profits. | 1 | Applied and Interdisciplinary Chemistry |
* Storms, E. (2007). Science Of Low Energy Nuclear Reaction, The: A Comprehensive Compilation Of Evidence And Explanations About Cold Fusion. Singapore: World Scientific Publishing Company. | 0 | Theoretical and Fundamental Chemistry |
The presence of AU-rich elements in some mammalian mRNAs tends to destabilize those transcripts through the action of cellular proteins that bind these sequences and stimulate poly(A) tail removal. Loss of the poly(A) tail is thought to promote mRNA degradation by facilitating attack by both the exosome complex and the decapping complex. Rapid mRNA degradation via AU-rich elements is a critical mechanism for preventing the overproduction of potent cytokines such as tumor necrosis factor (TNF) and granulocyte-macrophage colony stimulating factor (GM-CSF). AU-rich elements also regulate the biosynthesis of proto-oncogenic transcription factors like c-Jun and c-Fos. | 1 | Applied and Interdisciplinary Chemistry |
A degradation stretch is a river section that by definition meets none of the criteria to be a beam origin nor a beam path. Transverse structures such as weirs or dams can be obstacles for aquatic organisms but also canalised (artificial) river sections possibly prohibit organism to drift and migrate. | 1 | Applied and Interdisciplinary Chemistry |
Multiple solar cells in an integrated group, all oriented in one plane, constitute a solar photovoltaic panel or module. Photovoltaic modules often have a sheet of glass on the sun-facing side, allowing light to pass while protecting the semiconductor wafers. Solar cells are usually connected in series creating additive voltage. Connecting cells in parallel yields a higher current.
However, problems in paralleled cells such as shadow effects can shut down the weaker (less illuminated) parallel string (a number of series connected cells) causing substantial power loss and possible damage because of the reverse bias applied to the shadowed cells by their illuminated partners.
Although modules can be interconnected to create an array with the desired peak DC voltage and loading current capacity, which can be done with or without using independent MPPTs (maximum power point trackers) or, specific to each module, with or without module level power electronic (MLPE) units such as microinverters or DC-DC optimizers. Shunt diodes can reduce shadowing power loss in arrays with series/parallel connected cells.
By 2020, the United States cost per watt for a utility scale system had declined to $0.94. | 0 | Theoretical and Fundamental Chemistry |
Numerous genes and/or proteins as well as other molecules have been identified that mediate plant defense signal transduction. Cytoskeleton and vesicle trafficking dynamics help to orient plant defense responses toward the point of pathogen attack. | 1 | Applied and Interdisciplinary Chemistry |
The structures of Co(SCN) and its hydrate Co(SCN)(HO) have been determined using X-ray crystallography. Co(SCN) forms infinite 2D sheets in the mercury(II) thiocyanate structure type, where as Co(SCN)(HO) consists of isolated tetrahedral Co(SCN)(HO) centers and one equivalent of water of crystallization.
The hydrate may be prepared by the salt metathesis reactions, such as the reaction of aqueous cobalt(II) sulfate and barium thiocyanate to produce a barium sulfate precipitate, leaving the hydrate of Co(SCN) in solution:
:CoSO + Ba(SCN) → BaSO + Co(SCN)
or the reaction of the hexakisacetonitrile cobalt(II) tetrafluoroborate and potassium thiocyanate, precipitating KBF
:[Co(NCMe)](BF) + 2KSCN → 2KBF + Co(SCN).
The anhydrate can then be prepared via addition of diethylether as an antisolvent. | 0 | Theoretical and Fundamental Chemistry |
In the 1960s the city of Sydney decided to build ocean sewage outfalls to discharge partially treated sewage 2–4 km offshore at a cost of US$300 million. In the late 1980s, however, the government promised to upgrade the coastal treatment plants so that sewage would be treated to at least secondary treatment standards before discharge into the ocean.
The submarine outfall in Cartagena, Colombia was financed with a loan by the World Bank. It was subsequently challenged by residents claiming that the wastewater caused damage to the marine environment and to fisheries. The case was taken up by the World Bank's Inspection Panel, which contracted two independent three-dimensional modeling efforts in 2006. Both "confirmed that the 2.85km long submarine outfall (was) adequate."
For disposal into the ocean, environmental treaty requirements have to met. As international treaties often manage water over countries' borders, wastewater disposal is easier in bodies of water found entirely under the jurisdiction of one country. | 1 | Applied and Interdisciplinary Chemistry |
Prismane is a colourless liquid at room temperature. The deviation of the carbon-carbon bond angle from 109° to 60° in a triangle leads to a high ring strain, reminiscent of that of cyclopropane but greater. The compound is explosive, which is unusual for a hydrocarbon. Due to this ring strain, the bonds have a low bond energy and break at a low activation energy, which makes synthesis of the molecule difficult; Woodward and Hoffmann noted that prismane's thermal rearrangement to benzene is symmetry-forbidden, comparing it to "an angry tiger unable to break out of a paper cage." On account of its strain energy and the aromatic stabilization of benzene, the molecule is estimated to be 90 kcal/mole less stable than benzene, but the activation of this highly exothermic transformation is a surprisingly high 33 kcal/mol, making it persistent at room temperature.
The substituted derivative hexamethylprismane (in which all six hydrogens are substituted by methyl groups) has a higher stability, and was synthesized by rearrangement reactions in 1966. | 0 | Theoretical and Fundamental Chemistry |
In addition to activating PKC, diacylglycerol has a number of other functions in the cell:
* a source for prostaglandins
* a precursor of the endocannabinoid 2-arachidonoylglycerol
* an activator of a subfamily of transient receptor potential canonical (TRPC) cation channels, TRPC3/6/7. | 1 | Applied and Interdisciplinary Chemistry |
In stereochemistry, diastereomers (sometimes called diastereoisomers) are a type of stereoisomer. Diastereomers are defined as non-mirror image, non-identical stereoisomers. Hence, they occur when two or more stereoisomers of a compound have different configurations at one or more (but not all) of the equivalent (related) stereocenters and are not mirror images of each other.
When two diastereoisomers differ from each other at only one stereocenter, they are epimers. Each stereocenter gives rise to two different configurations and thus typically increases the number of stereoisomers by a factor of two.
Diastereomers differ from enantiomers in that the latter are pairs of stereoisomers that differ in all stereocenters and are therefore mirror images of one another.
Enantiomers of a compound with more than one stereocenter are also diastereomers of the other stereoisomers of that compound that are not their mirror image (that is, excluding the opposing enantiomer).
Diastereomers have different physical properties (unlike most aspects of enantiomers) and often different chemical reactivity.
Diastereomers differ not only in physical properties but also in chemical reactivity — how a compound reacts with others. Glucose and galactose, for instance, are diastereomers. Even though they share the same molar weight, glucose is more stable than galactose. This difference in stability causes galactose to be absorbed slightly faster than glucose in human body.
Diastereoselectivity is the preference for the formation of one or more than one diastereomer over the other in an organic reaction. In general, stereoselectivity is attributed to torsional and steric interactions in the stereocenter resulting from electrophiles approaching the stereocenter in reaction. | 0 | Theoretical and Fundamental Chemistry |
Autoacceleration (gel effect, Trommsdorff–Norrish effect) is a dangerous reaction behavior that can occur in free-radical polymerization systems. It is due to the localized increases in viscosity of the polymerizing system that slow termination reactions. The removal of reaction obstacles therefore causes a rapid increase in the overall rate of reaction, leading to possible reaction runaway and altering the characteristics of the polymers produced. | 0 | Theoretical and Fundamental Chemistry |
Fluorescent proteins have had a substantial impact on bioimaging, which is why biliproteins have made suitable candidates for the application, due to their properties of fluorescence, light-harvesting, light-sensitivity and photoswitching (the latter occurring only in phytochromes). Phycobiliproteins, which are highly fluorescent, have been used in external applications of bioimaging since the early 1980s. That application requires the bilin chromophore to be synthesised from haem, after which a lyase is needed to covalently bond the bilin to its corresponding apoprotein. An alternative method of uses phytochromes instead; some phytochromes only require one enzyme, haem oxygenase, for synthesising chromophores. Another benefit of using phytochromes is that they bind to their bilins autocatalytically. While there are photochromic pigments with poor fluorescence, this problem has been alleviated by engineering protein variants that reduce photochemistry and enhance fluorescence. | 1 | Applied and Interdisciplinary Chemistry |
Self-assembly is an equilibrium process, i.e. the individual and assembled components exist in equilibrium. In addition, the flexibility and the lower free energy conformation is usually a result of a weaker intermolecular force between self-assembled moieties and is essentially enthalpic in nature.
The thermodynamics of the self-assembly process can be represented by a simple Gibbs free energy equation:
where if is negative, self-assembly is a spontaneous process. is the enthalpy change of the process and is largely determined by the potential energy/intermolecular forces between the assembling entities. is the change in entropy associated with the formation of the ordered arrangement. In general, the organization is accompanied by a decrease in entropy and in order for the assembly to be spontaneous the enthalpy term must be negative and in excess of the entropy term. This equation shows that as the value of approaches the value of and above a critical temperature, the self-assembly process will become progressively less likely to occur and spontaneous self-assembly will not happen.
The self-assembly is governed by the normal processes of nucleation and growth. Small assemblies are formed because of their increased lifetime as the attractive interactions between the components lower the Gibbs free energy. As the assembly grows, the Gibbs free energy continues to decrease until the assembly becomes stable enough to last for a long period of time. The necessity of the self-assembly to be an equilibrium process is defined by the organization of the structure which requires non-ideal arrangements to be formed before the lowest energy configuration is found.
Kinetics
The ultimate driving force in self-assembly is energy minimization and the corresponding evolution towards equilibrium, but kinetic effects can also play a very strong role. These kinetic effects, such as trapping in metastable states, slow coarsening kinetics, and pathway-dependent assembly, are often viewed as complications to be overcome in, for example, the formation of block copolymers.
Amphiphile self-assembly is an essential bottom-up approach of fabricating advanced functional materials. Self-assembled materials with desired structures are often obtained through thermodynamic control. Here, we demonstrate that the selection of kinetic pathways can lead to drastically different self-assembled structures, underlining the significance of kinetic control in self-assembly. | 0 | Theoretical and Fundamental Chemistry |
A reservoir is a thermodynamic system which controls the state of a system, usually by "imposing" itself upon the system being controlled. This means that the nature of its contact with the system can be controlled. A reservoir is so large that its thermodynamic state is not appreciably affected by the state of the system being controlled. The term "atmospheric pressure" in the below description of a theoretical thermometer is essentially a "pressure reservoir" which imposes atmospheric pressure upon the thermometer.
Some common reservoirs are:
* Pressure reservoir - by far the most common pressure reservoir is the Earth's atmosphere.
* Temperature reservoir - A large quantity of water at its triple point forms an effective temperature reservoir. | 0 | Theoretical and Fundamental Chemistry |
Myogenic hyperuricemia, as a result of the purine nucleotide cycle running when ATP reservoirs in muscle cells are low (ADP > ATP), is a common pathophysiologic feature of glycogenoses such as GSD-III, GSD-V and GSD-VII, as they are metabolic myopathies which impair the ability of ATP (energy) production within muscle cells. In these metabolic myopathies, myogenic hyperuricemia is exercise-induced; inosine, hypoxanthine and uric acid increase in plasma after exercise and decrease over hours with rest. Excess AMP (adenosine monophosphate) is converted into uric acid.
:AMP → IMP → Inosine → Hypoxanthine → Xanthine → Uric acid
Hyperammonemia is also seen post-exercise in McArdle disease (GSD-V) and phosphoglucomutase deficiency (PGM1-CDG, formerly GSD-XIV), due to the purine nucleotide cycle running when the ATP reservoir is low due to the glycolytic block.O + H → IMP + NH </blockquote> | 1 | Applied and Interdisciplinary Chemistry |
Separation systems are coupled with a detector, that allows the detection and identification of VOCs based on their molecular weight and chemical properties. The most used system for the analysis of floral scent samples is GC-MS (gas chromatography coupled with mass spectrometry). | 1 | Applied and Interdisciplinary Chemistry |
DEHPA can be used to extract lanthanides (rare earths) from aqeuous solutions, it is commonly used in the lanthanide sector as an extraction agent. In general the distribution ratio of the lanthanides increase as their atomic number increases due to the lanthanide contraction. It is possible by bringing a mixture of lanthanides in a counter current mixer settler bank into contact with a suitable concentration of nitric acid to selectively strip (back extract) some of the lanthanides while leaving the others still in the DEHPA based organic layer. In this way selective stripping of the lanthanides can be used to make a separation of a mixture of the lanthanides into mixtures containing fewer lanthanides. Under ideal conditions this can be used to obtain a single lanthanide from a mixture of many lanthanides.
It is common to use DEHPA in an aliphatic kerosene which is best considered to be a mixture of long chain alkanes and cycloalkanes. When used in an aromatic hydrocarbon diluent the lanthanide distribution ratios are lower. It has been shown that it is possible to use a second generation biodiesel which was made by the hydrotreatment of vegetable oil. It has been reported that Neste's HVO100 is a suitable diluent for DEHPA when calcium, lanthanum and neodymium are extracted from aqueous nitric acid | 0 | Theoretical and Fundamental Chemistry |
fMRS was developed as an extension of MRS in the early 1990s. Its potential as a research technology became obvious when it was applied to an important research problem where PET studies had been inconclusive, namely the mismatch between oxygen and glucose consumption during sustained visual stimulation. The H fMRS studies highlighted the important role of lactate in this process and significantly contributed to the research in brain energy metabolism during brain activation. It confirmed the hypothesis that lactate increases during sustained visual stimulation and allowed the generalization of findings based on visual stimulation to other types of stimulation, e.g., auditory stimulation, motor task and cognitive tasks.
H fMRS measurements were instrumental in achieving the current consensus among most researchers that lactate levels increase during the first minutes of intense brain activation. However, there are no consistent results about the magnitude of increase, and questions about the exact role of lactate in brain energy metabolism still remain unanswered and are the subject of continuing research.
C MRS is a special type of fMRS particularly suited for measuring important neurophysiological fluxes in vivo and in real time to assess metabolic activity both in healthy and diseased brains (e.g., in human tumor tissue ). These fluxes include TCA cycle, glutamate–glutamine cycle, glucose and oxygen consumption. C MRS can provide detailed quantitative information about glucose dynamics that can not be obtained with H fMRS, because of the low concentration of glucose in the brain and the spread of its resonances in several multiplets in the H MRS spectrum.
C MRSs have been crucial in recognizing that the awake nonstimulated (resting) human brain is highly active using 70%–80% of its energy for glucose oxidation to support signaling within cortical networks which is suggested to be necessary for consciousness. This finding has an important implication for the interpretation of BOLD fMRI data where this high baseline activity is generally ignored and response to the task is shown as independent of the baseline activity. C MRS studies indicate that this approach can misjudge and even completely miss the brain activity induced by the task.
C MRS findings together with other results from PET and fMRI studies have been combined in a model to explain the function of resting state activity called default mode network.
Another important benefit of C MRS is that it provides unique means for determining the time course of metabolite pools and measuring turnover rates of TCA and glutamate–glutamine cycles. As such, it has been proved to be important in aging research by revealing that mitochondrial metabolism is reduced with aging which may explain the decline in cognitive and sensory processes. | 0 | Theoretical and Fundamental Chemistry |
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