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Diseases often caused by TEs include
* Hemophilia A and B
** LINE1 (L1) TEs that land on the human Factor VIII have been shown to cause haemophilia
* Severe combined immunodeficiency
** Insertion of L1 into the APC gene causes colon cancer, confirming that TEs play an important role in disease development.
* Porphyria
**Insertion of Alu element into the PBGD gene leads to interference with the coding region and leads to acute intermittent porphyria (AIP).
* Predisposition to cancer
**LINE1(L1) TE's and other retrotransposons have been linked to cancer because they cause genomic instability.
* Duchenne muscular dystrophy.
**Caused by SVA transposable element insertion in the fukutin (FKTN) gene which renders the gene inactive.
* Alzheimer's Disease and other Tauopathies
** Transposable element dysregulation can cause neuronal death, leading to neurodegenerative disorders | 1 | Applied and Interdisciplinary Chemistry |
Craig proposed three rules of thumb for interpretation of wettability from relative permeability curves. These rules are based on the value of interstitial water saturation, the water saturation at the crossover point of relative permeability curves (i.e., where relative permeabilities are equal to each other), and the normalized water permeability at residual oil saturation (i.e., normalized by the oil permeability at interstitial water saturation).
According to Craig's first rule of thumb, in water-wet rocks the relative permeability to water at residual oil saturation is generally less than 30%, whereas in oil-wet systems this is greater than 50% and approaching 100%. The second rule of thumb considers a system as water-wet, if saturation at the crossover point of relative permeability curves is greater than water saturation of 50%, otherwise oil-wet. The third rule of thumb states that in a water-wet rock the value of interstitial water saturation is usually greater than 20 to 25% pore volume, whereas this is generally less than 15% pore volume (frequently less than 10%) for an oil-wet porous medium. | 0 | Theoretical and Fundamental Chemistry |
Immunosequencing in its modern context started being discussed in scientific literature in the early 2010s with the advent of more powerful gene sequencing techniques. | 1 | Applied and Interdisciplinary Chemistry |
Some particulates occur naturally, originating from volcanoes, dust storms, forest and grassland fires, living vegetation and sea spray. Human activities, such as the burning of fossil fuels in vehicles, wood burning, stubble burning, power plants, road dust, wet cooling towers in cooling systems and various industrial processes, also generate significant amounts of particulates. Coal combustion in developing countries is the primary method for heating homes and supplying energy. Because salt spray over the oceans is the overwhelmingly most common form of particulate in the atmosphere, anthropogenic aerosols—those made by human activities—currently account for about 10 percent of the total mass of aerosols in our atmosphere.
Microplastics are an emerging source of atmospheric pollution, particularly fine plastic fibers that are light enough to be carried by the wind. Microplastics traveling in the air cannot be traced back to their specific original sources, as the wind can blow the infinitesimal particles thousands of miles from where they were originally shed. Microplastics are being found in very remote regions of the Earth, where there are no apparent nearby sources of plastic. A common source of airborne microplastic fibers is plastic textiles. While most atmospheric microplastics tend to come from land, microplastics are also entering the atmosphere through ocean and sea mist. | 1 | Applied and Interdisciplinary Chemistry |
Transcription factor TFA is a nuclear protein involved in the RNA polymerase II-dependent transcription of DNA. TFA is one of several general (basal) transcription factors (GTFs) that are required for all transcription events that use RNA polymerase II. Other GTFs include TFD, a complex composed of the TATA binding protein TBP and TBP-associated factors (TAFs), as well as the factors TFB, TFE, TFF, and TFH. Together, these factors are responsible for promoter recognition and the formation of a transcription preinitiation complex (PIC) capable of initiating RNA synthesis from a DNA template. | 1 | Applied and Interdisciplinary Chemistry |
Depending upon the sampling technique and the analytical conditions, thermal desorption can be used to reliably sample analytes ranging in volatility from ethane to about tetracontane (n-CH). Incompatible compounds include:
* Many inorganic gases (although NO, HS and SF can be monitored using TD)
* Methane
* Compounds that are thermally unstable
* Compounds heavier than n-CH, didecyl phthalate or 6-ring polycyclic aromatic hydrocarbons boiling above 525 °C. | 0 | Theoretical and Fundamental Chemistry |
Highly cationic metal ammine complexes such as [Pt(NH3)6]4+ spontaneously convert to the amido derivative:
:[Pt(NH)] )(NH)] + H
Transition metal amides are intermediates in the base-induced substitution of transition metal ammine complexes. Thus, the Sn1CB mechanism for the displacement of chloride from chloropentamminecobalt chloride by hydroxide proceeds via an amido intermediate:
:[Co(NH)Cl] + OH → [Co(NH)(NH)] + HO + Cl
:[Co(NH)NH] + HO → [Co(NH)OH] | 0 | Theoretical and Fundamental Chemistry |
Continuous flow microfluidics rely on the control of a steady state liquid flow through narrow channels or porous media predominantly by accelerating or hindering fluid flow in capillary elements. In paper based microfluidics, capillary elements can be achieved through the simple variation of section geometry. In general, the actuation of liquid flow is implemented either by external pressure sources, external mechanical pumps, integrated mechanical micropumps, or by combinations of capillary forces and electrokinetic mechanisms. Continuous-flow microfluidic operation is the mainstream approach because it is easy to implement and less sensitive to protein fouling problems. Continuous-flow devices are adequate for many well-defined and simple biochemical applications, and for certain tasks such as chemical separation, but they are less suitable for tasks requiring a high degree of flexibility or fluid manipulations. These closed-channel systems are inherently difficult to integrate and scale because the parameters that govern flow field vary along the flow path making the fluid flow at any one location dependent on the properties of the entire system. Permanently etched microstructures also lead to limited reconfigurability and poor fault tolerance capability. Computer-aided design automation approaches for continuous-flow microfluidics have been proposed in recent years to alleviate the design effort and to solve the scalability problems.
Process monitoring capabilities in continuous-flow systems can be achieved with highly sensitive microfluidic flow sensors based on MEMS technology, which offers resolutions down to the nanoliter range. | 1 | Applied and Interdisciplinary Chemistry |
The text written in Sanskrit, begins with an invocation:
The first verse of Tattvārthsūtra, "" summarizes the Jaina path to liberation. It means that the Ratnatraya (three jewels: right view, right knowledge and right conduct) collectively constitutes the path to liberation or moksha.
Its ten chapters are:
#Faith and Knowledge
#The Category of the Living
#The Lower World and the Middle World
#The Celestial Beings
#The Category of the Non-Living
#Influx of Karma
#The Five Vows
#Bondage of Karma
#Stoppage and Shedding of Karma
#Liberation
The first chapter deals with the process of cognition and details about different types of knowledge. The next three chapters deal with the Jīva (soul), lower worlds, naraka, and celestial abodes, devas. The fifth chapter discusses the Non-soul (ajīva). The next three chapters deal with the karmas and their manifestations and the influx, asrava, good and bad karma, shubha-ashubha karma and the bondage of the karmas. The ninth chapter describes the blocking, samvara and shedding of the karmas, nirjara. The final chapter discusses moksha or the liberation of the soul. | 1 | Applied and Interdisciplinary Chemistry |
A fine wire probe or other delivery mechanism is used to transmit radio waves to tissues near the probe. Molecules in the tissue are caused to vibrate, leading to a rapid increase in temperature, causing coagulation of the proteins in the tissue and effectively killing the tissue. At higher-powered applications, full desiccation of tissue is possible. | 1 | Applied and Interdisciplinary Chemistry |
In general, prehistoric extraction of metals, particularly copper, involved two fundamental stages: first, the smelting of copper ore at temperatures exceeding 700 °C is needed to separate the gangue from the copper; second, melting the copper, which requires temperatures exceeding its melting point of 1080 °C. Given the available technology at the time, accomplishing these extreme temperatures posed a significant challenge. Early smelters developed ways to effectively increase smelting temperatures by feeding the fire with forced flows of oxygen.
Copper extraction in particular is of great interest in archeometallurgical studies since it dominated other metals in Mesopotamia from the early Chalcolithic until the mid-to-late sixth century BC. There is a lack of consensus among archaeometallurgists on the origin of non-ferrous extractive metallurgy. Some scholars believe that extractive metallurgy may have been simultaneously or independently discovered in several parts of the world. The earliest known use of pyrometallurgical extraction of copper occurred in Belovode, eastern Serbia, from the late sixth to early fifth millennium BC. However, there is also evidence of copper smelting in Tal-i-Iblis, southeastern Iran, which dates back to around the same period. During this period, copper smelters used large in-grown pits filled with coal, or crucibles to extract copper, but by the fourth millennium BC this practice had begun to phase out in favor of the smelting furnace, which had a larger production capacity. From the third millennium onward, the invention of the reusable smelting furnace was crucial to the success of large-scale copper production and the robust expansion of the copper trade through the Bronze Age.
The earliest silver objects began appearing in the late fourth millennium BC in Anatolia, Turkey. Prehistoric silver extraction is strongly associated with the extraction of the less valuable metal, lead; although evidence of lead extraction technology predates silver by at least 3 millennia. Silver and lead extractions are also associated because the argentiferous (silver-bearing) ores used in the process often contains both elements.
In general, prehistoric silver recovery was broken down into three phases: First, the silver-lead ore is roasted to separate the silver and lead from the gangue. The metals are then melted at high temperature ( greater than 1100 °C) in the crucible while air is blown over the molten metal (cupellation). Finally, lead is oxidized to form lead monoxide (PbO) or is absorbed into the walls of the crucible, leaving the refined silver behind.
The silver-lead cupellation method was first used in Mesopotamia between 4000 and 3500 BC. Silver artifacts, dating around 3600 BC, were discovered in Naqada, Egypt. Some of these cast silver artifacts contained less than 0.5% lead, which strongly indicates cupellation. | 1 | Applied and Interdisciplinary Chemistry |
In optics, absorbance or decadic absorbance is the common logarithm of the ratio of incident to radiant power through a material, and spectral absorbance or spectral decadic absorbance is the common logarithm of the ratio of incident to spectral radiant power through a material. Absorbance is dimensionless, and in particular is not a length, though it is a monotonically increasing function of path length, and approaches zero as the path length approaches zero. | 0 | Theoretical and Fundamental Chemistry |
Perfluorocarbons or PFCs, are organofluorine compounds with the formula CF, meaning they contain only carbon and fluorine. The terminology is not strictly followed and many fluorine-containing organic compounds are also called fluorocarbons. Compounds with the prefix perfluoro- are hydrocarbons, including those with heteroatoms, wherein all C-H bonds have been replaced by C-F bonds. Fluorocarbons includes perfluoroalkanes, fluoroalkenes, fluoroalkynes, and perfluoroaromatic compounds. | 1 | Applied and Interdisciplinary Chemistry |
Pyruvate molecules produced by glycolysis are actively transported across the inner mitochondrial membrane, and into the matrix where they can either be oxidized and combined with coenzyme A to form CO, acetyl-CoA, and NADH, or they can be carboxylated (by pyruvate carboxylase) to form oxaloacetate. This latter reaction "fills up" the amount of oxaloacetate in the citric acid cycle and is therefore an anaplerotic reaction, increasing the cycles capacity to metabolize acetyl-CoA when the tissues energy needs (e.g., in muscle) are suddenly increased by activity.
In the citric acid cycle, all the intermediates (e.g. citrate, iso-citrate, alpha-ketoglutarate, succinate, fumarate, malate and oxaloacetate) are regenerated during each turn of the cycle. Adding more of any of these intermediates to the mitochondrion therefore means that the additional amount is retained within the cycle, increasing all the other intermediates as one is converted into the other. Hence, the addition of any one of them to the cycle has an anaplerotic effect, and its removal has a cataplerotic effect. These anaplerotic and cataplerotic reactions will, during the course of the cycle, increase or decrease the amount of oxaloacetate available to combine with acetyl-CoA to form citric acid. This in turn increases or decreases the rate of ATP production by the mitochondrion, and thus the availability of ATP to the cell.
Acetyl-CoA, on the other hand, derived from pyruvate oxidation, or from the beta-oxidation of fatty acids, is the only fuel to enter the citric acid cycle. With each turn of the cycle one molecule of acetyl-CoA is consumed for every molecule of oxaloacetate present in the mitochondrial matrix, and is never regenerated. It is the oxidation of the acetate portion of acetyl-CoA that produces CO and water, with the energy thus released captured in the form of ATP.
In the liver, the carboxylation of cytosolic pyruvate into intra-mitochondrial oxaloacetate is an early step in the gluconeogenic pathway, which converts lactate and de-aminated alanine into glucose, under the influence of high levels of glucagon and/or epinephrine in the blood. Here, the addition of oxaloacetate to the mitochondrion does not have a net anaplerotic effect, as another citric acid cycle intermediate (malate) is immediately removed from the mitochondrion to be converted to cytosolic oxaloacetate, and ultimately to glucose, in a process that is almost the reverse of glycolysis.
The enzymes of the citric acid cycle are located in the mitochondrial matrix, with the exception of succinate dehydrogenase, which is bound to the inner mitochondrial membrane as part of Complex II. The citric acid cycle oxidizes the acetyl-CoA to carbon dioxide, and, in the process, produces reduced cofactors (three molecules of NADH and one molecule of FADH) that are a source of electrons for the electron transport chain, and a molecule of GTP (which is readily converted to an ATP). | 1 | Applied and Interdisciplinary Chemistry |
Proteins perform several functions in living organisms, including catalytic reactions and transport of molecules or ions within the cells, the organs or the whole body. The understanding of the processes in human organisms, which are mainly driven by biochemical reactions and protein-protein interactions, depends to a great extent on the ability to isolate active proteins in biological samples for more detailed examination of chemical structure and physiological function. This essential information can imply an important indication of a patient's state of health.
As about 30–40% of all known proteins contain one or more metal ion cofactors (e.g., ceruloplasmin, ferritin, amyloid-beta precursor protein, matrix metalloproteinase, or metallochaperones), especially native and denatured metalloproteins have to be isolated, identified and quantified after liquid biopsy. Many of these cofactors (e.g., iron, copper, or zinc) play a key role in vital enzymatic catalytic processes or stabilize globular protein molecules. Therefore, the high-precision gel electrophoresis and comparable separation techniques are highly relevant as initial step of protein and trace metal speciation analysis, subsequently, followed by modern mass spectrometric and magnetic resonance methods for quantifying and identifying the soluble proteins of interest. | 0 | Theoretical and Fundamental Chemistry |
Classical Control theory is a field of mathematics that deals with the control of dynamical systems in engineered processes and machines. In 2004 Brian Ingalls published a paper that showed that classical control theory and metabolic control analysis were identical. The only difference was that metabolic control analysis was confined to zero frequency responses when cast in the frequency domain whereas classical control theory imposes no such restriction. The other significant difference is that classical control theory has no notion of stoichiometry and conservation of mass which makes it more cumbersome to use but also means it fails to recognize the structural properties inherent in stoichiometric networks which provide useful biological insights. | 1 | Applied and Interdisciplinary Chemistry |
* Domination of the vortex-shedding phenomenon;
* High deviations of airloads and large hysteresis;
* Extension of the viscous zone to the order of airfoil chord;
* Less sensitivity to airfoil geometry, reduced frequency and Mach number;
* Rapid overshoots of airloads after stall. | 1 | Applied and Interdisciplinary Chemistry |
Igor Volodymyrovych Komarov () is a Ukrainian synthetic organic chemist, specializing in medicinal chemistry and nanotechnology. He is the director of the Institute of High Technologies of Taras Shevchenko National University of Kyiv. He is also a scientific advisor of Enamine Ltd (Ukraine) and Lumobiotics GmbH (Germany). | 0 | Theoretical and Fundamental Chemistry |
Unlike in marine sediments, diagenesis does not pose a large threat to the integrity of the C/N ratio in lacustrine sediments. Though wood from living trees around lakes have consistently higher C/N ratios than wood buried in sediment, the change in elemental composition is not large enough to remove the vascular versus non-vascular plant signals due to the refractory nature of terrestrial organic matter. Abrupt shifts in the C/N ratio down-core can be interpreted as shifts in the organic source material.
For example, two separate studies on Mangrove Lake, Bermuda and Lake Yunoko, Japan show irregular, abrupt fluctuations between C/N around 11 to around 18. These fluctuations are attributed to shifts from mainly algal dominance to land-based vascular dominance. Results of studies that show abrupt shifts in algal dominance and vascular dominance often lead to conclusions about the state of the lake during these distinct periods of isotopic signatures. Times in which lakes are dominated by algal signals suggest the lake is a deep-water lake, while times in which lakes are dominated by vascular plant signals suggest the lake is shallow, dry, or marshy. Using the C/N ratio in conjunction with other sediment observations, such as physical variations, D/H isotopic analyses of fatty acids and alkanes, and δ13C analyses on similar biomarkers can lead to further regional climate interpretations that describe the larger phenomena at play. | 0 | Theoretical and Fundamental Chemistry |
Strong measurements (both classical and quantum) are certainly disturbing, causing asymmetry due to the second law of thermodynamics. However,
noninvasive measurements should not disturb the evolution, so they are expected to be time-symmetric. Surprisingly, it is true only in classical physics but not in quantum physics, even in a thermodynamically invariant equilibrium state. This type of asymmetry is independent of CPT symmetry but has not yet been confirmed experimentally due to extreme conditions of the checking proposal. | 0 | Theoretical and Fundamental Chemistry |
A recent international project has developed and determined the hydrogen, carbon, and nitrogen isotopic composition of 19 organic isotopic reference materials, now available from USGS, IAEA, and Indiana University. These reference materials span a large range of δH (-210.8‰ to +397.0‰), δC (-40.81‰ to +0.49‰), and δN (-5.21‰ to +61.53‰), and are amenable to a wide range of analytical techniques. The organic reference materials include caffeine, glycine, n-hexadecane, icosanoic acid methyl ester (C FAME), L-valine, methylheptadecanoate, polyethylene foil, polyethylene power, vacuum oil, and NBS-22.
The information in Table 7 comes directly from Table 2 of Schimmelmann et al. (2016). | 0 | Theoretical and Fundamental Chemistry |
That the Spanish colonials, not the British, were the first in North America to license a pharmacist (in 1769 in New Orleans) and were also the first to regulate pharmacy as a separate profession, points to the importance of non-British colonial governments and, indeed, settlers from mainland Europe throughout North America, in importing and translating the more modern pharmacy methods, standards and ways of organization and regulation—developing in Europe since at least the 1600s—for application in the infant United States.
"Franco-Spanish" Louisiana "more clearly reflected [pharmacys] development in Continental Europe." Influential milestones achieved in 18th-century Louisiana included the February 12th, 1770 edict from the governor in New Orleans, Don Alexandre OReilly, delineating the responsibilities and boundaries of medicine, surgery and pharmacy and marking the first legal recognition of pharmacy as a distinct discipline in the territories that would become the United States. Though the number of pharmacists licensed under this system in Spanish Louisiana never surpassed the single-digits, OReillys decree and its ethical code for pharmacists set an important precedent future developments would build upon. It also brought on-line an important independent pipeline of licensed druggists, albeit a small pipeline, to add to the scant supply of Old World apothecaries who had immigrated to set up shop in the colonies.
Of the few apothecaries imported from Europe, those of Jesuit training had a long-felt impact in both New Spain and New France; so great was Jesuit involvement in "care of the sick" in their foreign missions, in fact, they sought and received a papal exemption from the ban on clerics serving in medical roles. Two dedicated "pharmacopoles or apothecary brethren" Jesuits are listed under the heading "Missions of North America in New France" in Society of Jesus personnel records for the "Province of France at the End of the Year 1749." Jesuit contributions, especially in translating Native American ethnobotany into medicines for European use, were highly influential as pharmacy developed in North America. | 1 | Applied and Interdisciplinary Chemistry |
Thin-layer chromatography (TLC) is a chromatography technique that separates components in non-volatile mixtures.
It is performed on a TLC plate made up of a non-reactive solid coated with a thin layer of adsorbent material. This is called the stationary phase. The sample is deposited on the plate, which is eluted with a solvent or solvent mixture known as the mobile phase (or eluent). This solvent then moves up the plate via capillary action. As with all chromatography, some compounds are more attracted to the mobile phase, while others are more attracted to the stationary phase. Therefore, different compounds move up the TLC plate at different speeds and become separated. To visualize colourless compounds, the plate is viewed under UV light or is stained. Testing different stationary and mobile phases is often necessary to obtain well-defined and separated spots.
TLC is quick, simple, and gives high sensitivity for a relatively low cost. It can monitor reaction progress, identify compounds in a mixture, determine purity, or purify small amounts of compound. | 0 | Theoretical and Fundamental Chemistry |
The peak phase can be defined as period of time in which the intensity of the substance's effects are at its height. | 1 | Applied and Interdisciplinary Chemistry |
Complexes show a variety of possible reactivities:
* Electron transfers
*: Electron transfer (ET) between metal ions can occur via two distinct mechanisms, inner and outer sphere electron transfers. In an inner sphere reaction, a bridging ligand serves as a conduit for ET.
* (Degenerate) ligand exchange
*: One important indicator of reactivity is the rate of degenerate exchange of ligands. For example, the rate of interchange of coordinate water in [M(HO)] complexes varies over 20 orders of magnitude. Complexes where the ligands are released and rebound rapidly are classified as labile. Such labile complexes can be quite stable thermodynamically. Typical labile metal complexes either have low-charge (Na), electrons in d-orbitals that are antibonding with respect to the ligands (Zn), or lack covalency (Ln, where Ln is any lanthanide). The lability of a metal complex also depends on the high-spin vs. low-spin configurations when such is possible. Thus, high-spin Fe(II) and Co(III) form labile complexes, whereas low-spin analogues are inert. Cr(III) can exist only in the low-spin state (quartet), which is inert because of its high formal oxidation state, absence of electrons in orbitals that are M–L antibonding, plus some "ligand field stabilization" associated with the d configuration.
* Associative processes
*: Complexes that have unfilled or half-filled orbitals are often capable of reacting with substrates. Most substrates have a singlet ground-state; that is, they have lone electron pairs (e.g., water, amines, ethers), so these substrates need an empty orbital to be able to react with a metal centre. Some substrates (e.g., molecular oxygen) have a triplet ground state, which results that metals with half-filled orbitals have a tendency to react with such substrates (it must be said that the dioxygen molecule also has lone pairs, so it is also capable to react as a normal Lewis base).
If the ligands around the metal are carefully chosen, the metal can aid in (stoichiometric or catalytic) transformations of molecules or be used as a sensor. | 0 | Theoretical and Fundamental Chemistry |
Dielectric spectroscopy (which falls in a subcategory of impedance spectroscopy) measures the dielectric properties of a medium as a function of frequency. It is based on the interaction of an external field with the electric dipole moment of the sample, often expressed by permittivity.
It is also an experimental method of characterizing electrochemical systems. This technique measures the impedance of a system over a range of frequencies, and therefore the frequency response of the system, including the energy storage and dissipation properties, is revealed. Often, data obtained by electrochemical impedance spectroscopy (EIS) is expressed graphically in a Bode plot or a Nyquist plot.
Impedance is the opposition to the flow of alternating current (AC) in a complex system. A passive complex electrical system comprises both energy dissipater (resistor) and energy storage (capacitor) elements. If the system is purely resistive, then the opposition to AC or direct current (DC) is simply resistance. Materials or systems exhibiting multiple phases (such as composites or heterogeneous materials) commonly show a universal dielectric response, whereby dielectric spectroscopy reveals a power law relationship between the impedance (or the inverse term, admittance) and the frequency, ω, of the applied AC field.
Almost any physico-chemical system, such as electrochemical cells, mass-beam oscillators, and even biological tissue possesses energy storage and dissipation properties. EIS examines them.
This technique has grown tremendously in stature over the past few years and is now being widely employed in a wide variety of scientific fields such as fuel cell testing, biomolecular interaction, and microstructural characterization. Often, EIS reveals information about the reaction mechanism of an electrochemical process: different reaction steps will dominate at certain frequencies, and the frequency response shown by EIS can help identify the rate limiting step. | 0 | Theoretical and Fundamental Chemistry |
Hans Thacher Clarke (27 December 1887 – 21 October 1972) was a prominent biochemist during the first half of the twentieth century. He was born in England where he received his university training, but also studied in Germany and Ireland. He spent the remainder of his life in the United States. | 0 | Theoretical and Fundamental Chemistry |
::(Work on this section is continuously in progress)
*Building effects or downwash: When an air pollution plume flows over nearby buildings or other structures, turbulent eddies are formed in the downwind side of the building. Those eddies cause a plume from a stack source located within about five times the height of a nearby building or structure to be forced down to the ground much sooner than it would if a building or structure were not present. The effect can greatly increase the resulting near-by ground-level pollutant concentrations downstream of the building or structure. If the pollutants in the plume are subject to depletion by contact with the ground (particulates, for example), the concentration increase just downstream of the building or structure will decrease the concentrations further downstream.
*Deposition of the pollution plume components to the underlying surface can be defined as either dry or wet deposition:
**Dry deposition is the removal of gaseous or particulate material from the pollution plume by contact with the ground surface or vegetation (or even water surfaces) through transfer processes such as absorption and gravitational sedimentation. This may be calculated by means of a deposition velocity, which is related to the resistance of the underlying surface to the transfer.
**Wet deposition is the removal of pollution plume components by the action of rain. The wet deposition of radionuclides in a pollution plume by a burst of rain often forms so called hot spots of radioactivity on the underlying surface.
*Inversion layers: Normally, the air near the Earths surface is warmer than the air above it because the atmosphere is heated from below as solar radiation warms the Earths surface, which in turn then warms the layer of the atmosphere directly above it. Thus, the atmospheric temperature normally decreases with increasing altitude. However, under certain meteorological conditions, atmospheric layers may form in which the temperature increases with increasing altitude. Such layers are called inversion layers. When such a layer forms at the Earths surface, it is called a surface inversion. When an inversion layer forms at some distance above the earth, it is called an inversion aloft (sometimes referred to as a capping inversion'). The air within an inversion aloft is very stable with very little vertical motion. Any rising parcel of air within the inversion soon expands, thereby adiabatically cooling to a lower temperature than the surrounding air and the parcel stops rising. Any sinking parcel soon compresses adiabatically to a higher temperature than the surrounding air and the parcel stops sinking. Thus, any air pollution plume that enters an inversion aloft will undergo very little vertical mixing unless it has sufficient momentum to completely pass through the inversion aloft. That is one reason why an inversion aloft is sometimes called a capping inversion.
*Mixing height: When an inversion aloft is formed, the atmospheric layer between the Earths surface and the bottom of the inversion aloft is known as the mixing layer and the distance between the Earths surface and the bottom of inversion aloft is known as the mixing height. Any air pollution plume dispersing beneath an inversion aloft will be limited in vertical mixing to that which occurs beneath the bottom of the inversion aloft (sometimes called the lid). Even if the pollution plume penetrates the inversion, it will not undergo any further significant vertical mixing. As for a pollution plume passing completely through an inversion layer aloft, that rarely occurs unless the pollution plume's source stack is very tall and the inversion lid is fairly low. | 1 | Applied and Interdisciplinary Chemistry |
The Krafft temperature is the temperature at which the CMC can be achieved. This temperature determines the relative solubility of surfactant in an aqueous solution. This is the minimum temperature the solution must be at to allow the surfactant to precipitate into aggregates. Below this temperature no level of solubility will be sufficient to precipitate aggregates due to minimal movement of particles in solution. The Krafft Temperature (T) is based on the concentration of counter-ions (C). Counter-ions are typically in the form of salt. Because the T is fundamentally based on the C, which is controlled by surfactant and salt concentration, different combinations of the respective parameters can be altered. Although, the C will maintain the same value despite changes in concentration of surfactant and salt, therefore, thermodynamically speaking the Krafft temperature will remain constant. | 0 | Theoretical and Fundamental Chemistry |
After being produced, the stability and distribution of the different transcripts is regulated (post-transcriptional regulation) by means of RNA binding protein (RBP) that control the various steps and rates controlling events such as alternative splicing, nuclear degradation (exosome), processing, nuclear export (three alternative pathways), sequestration in P-bodies for storage or degradation and ultimately translation. These proteins achieve these events thanks to an RNA recognition motif (RRM) that binds a specific sequence or secondary structure of the transcripts, typically at the 5’ and 3’ UTR of the transcript. In short, the dsRNA sequences, which will be broken down into siRNA inside of the organism, will match up with the RNA to inhibit the gene expression in the cell.
Modulating the capping, splicing, addition of a Poly(A) tail, the sequence-specific nuclear export rates and in several contexts sequestration of the RNA transcript occurs in eukaryotes but not in prokaryotes. This modulation is a result of a protein or transcript which in turn is regulated and may have an affinity for certain sequences.
* Capping changes the five prime end of the mRNA to a three prime end by 5-5 linkage, which protects the mRNA from 5' exonuclease , which degrades foreign RNA. The cap also helps in ribosomal binding. In addition, it represents a unique mark for a correct gene. Therefore, it helps to select the mRNA that is going to be translated.
* RNA splicing removes the introns, noncoding regions that are transcribed into RNA, in order to make the mRNA able to create proteins. Cells do this by spliceosomes binding on either side of an intron, looping the intron into a circle and then cleaving it off. The two ends of the exons are then joined.
* Addition of poly(A) tail otherwise known as polyadenylation. That is, a stretch of RNA that is made solely of adenine bases is added to the 3 end, and acts as a buffer to the 3 exonuclease in order to increase the half-life of mRNA. In addition, a long poly(A) tail can increase translation. Poly(A)-binding protein (PABP) binds to a long poly(A) tail and mediates the interaction between EIF4E and EIF4G which encourages the initiation of translation.
* RNA editing is a process which results in sequence variation in the RNA molecule, and is catalyzed by enzymes. These enzymes include the adenosine deaminase acting on RNA (ADAR) enzymes, which convert specific adenosine residues to inosine in an mRNA molecule by hydrolytic deamination. Three ADAR enzymes have been cloned, ADAR1, ADAR2 and ADAR3, although only the first two subtypes have been shown to have RNA editing activity. Many mRNAs are vulnerable to the effects of RNA editing, including the glutamate receptor subunits GluR2, GluR3, GluR4, GluR5 and GluR6 (which are components of the AMPA and kainate receptors), the serotonin2C receptor, the GABA-alpha3 receptor subunit, the tryptophan hydroxylase enzyme TPH2, the hepatitis delta virus and more than 16% of microRNAs. In addition to ADAR enzymes, CDAR enzymes exist and these convert cytosines in specific RNA molecules, to uracil. These enzymes are termed APOBEC and have genetic loci at 22q13, a region close to the chromosomal deletion which occurs in velocardiofacial syndrome (22q11) and which is linked to psychosis. RNA editing is extensively studied in relation to infectious diseases, because the editing process alters viral function.
* mRNA Stability can be manipulated in order to control its half-life, and the poly(A) tail has some effect on this stability, as previously stated. Stable mRNA can have a half-life of up to a day or more which allows for the production of more protein product; unstable mRNA is used in regulation that must occur quickly. mRNA stability is an important factor that is based on mRNA degradation rates.
*Nuclear export. Only one-twentieth of the total amount of RNA leaves the nucleus to proceed with translation. The rest of the RNA molecules, usually excised introns and damaged RNAs, are kept in the nucleus where they are eventually degraded. mRNA only leaves the nucleus when it is ready to keep going, which means that nuclear export is delayed until the processing is complete. As an interesting fact, there are some mechanisms that attack this nuclear export process to regulate gene expression. An example of regulated nuclear transport of mRNA can be observed in HIV. | 1 | Applied and Interdisciplinary Chemistry |
William Wordsworth and Samuel Taylor Coleridge moved to the Lake District in 1800, and asked Davy to deal with the Bristol publishers of the Lyrical Ballads, Biggs & Cottle. Coleridge asked Davy to proofread the second edition, the first to contain Wordsworths "Preface to the Lyrical Ballads", in a letter dated 16 July 1800: "Will you be so kind as just to look over the sheets of the lyrical Ballads". Wordsworth subsequently wrote to Davy on 29 July 1800, sending him the first manuscript sheet of poems and asking him specifically to correct: "any thing you find amiss in the punctuation a business at which I am ashamed to say I am no adept". Wordsworth was ill in the autumn of 1800 and slow in sending poems for the second edition; the volume appeared on 26 January 1801 even though it was dated 1800. While it is impossible to know whether Davy was at fault, this edition of the Lyrical Ballads contained many errors, including the poem "Michael" being left incomplete. In a personal notebook marked on the front cover "Clifton 1800 From August to Novr", Davy wrote his own Lyrical Ballad: "As I was walking up the street". Wordsworth features in Davys poem as the recorder of ordinary lives in the line: "By poet Wordsworths Rymes" [sic]. | 1 | Applied and Interdisciplinary Chemistry |
The Early Iron Age at Norşuntepe (1150–800 BC) is characterized by a shift away from Hittite material culture, possibly as a result of the influx of immigrants such as the Mushki. The settlement seems to have been restricted to the south terrace and may have had a rural character. During its final occupation phases (800–600 BC), Norşuntepe was part of Urartu. A building with a large, columned hall was located on the mail hill, whereas a second large building, possibly a caravanserai, was excavated on the south terrace. A cemetery located on the hill top included a burial chamber where three horses together with gear and weapons were buried.
The hilltop was again used as a cemetery during the Medieval Period. | 1 | Applied and Interdisciplinary Chemistry |
In addition, channeling of ions can also be used to analyze a crystalline sample for lattice damage. If atoms within the target are displaced from their crystalline lattice site, this will result in a higher backscattering yield in relation to a perfect crystal. By comparing the spectrum from a sample being analyzed to that from a perfect crystal, and that obtained at a random (non-channeling) orientation (representative of a spectrum from an amorphous sample), it is possible to determine the extent of crystalline damage in terms of a fraction of displaced atoms. Multiplying this fraction by the density of the material when amorphous then also gives an estimate for the concentration of displaced atoms. The energy at which the increased backscattering occurs can also be used to determine the depth at which the displaced atoms are and a defect depth profile can be built up as a result. | 0 | Theoretical and Fundamental Chemistry |
Josette Garnier is a French biogeochemist. She is research director at the French National Centre for Scientific Research (CNRS). She won the 2016 Ruth Patrick Award. | 0 | Theoretical and Fundamental Chemistry |
The behavior of open-channel flow is governed by the effects of viscosity and gravity relative to the inertial forces of the flow. Surface tension has a minor contribution, but does not play a significant enough role in most circumstances to be a governing factor. Due to the presence of a free surface, gravity is generally the most significant driver of open-channel flow; therefore, the ratio of inertial to gravity forces is the most important dimensionless parameter. The parameter is known as the Froude number, and is defined as:where is the mean velocity, is the characteristic length scale for a channel's depth, and is the gravitational acceleration. Depending on the effect of viscosity relative to inertia, as represented by the Reynolds number, the flow can be either laminar, turbulent, or transitional. However, it is generally acceptable to assume that the Reynolds number is sufficiently large so that viscous forces may be neglected. | 1 | Applied and Interdisciplinary Chemistry |
The Great Work of Alchemy is often described as a series of four stages represented by colours.
*nigredo, a blackening or melanosis
*albedo, a whitening or leucosis
*citrinitas, a yellowing or xanthosis
*rubedo, a reddening, purpling, or iosis | 1 | Applied and Interdisciplinary Chemistry |
El-Sayed's research interests include the use of steady-state and ultra fast laser spectroscopy to understand relaxation, transport and conversion of energy in molecules, in solids, in photosynthetic systems, semiconductor quantum dots and metal nanostructures. The El-Sayed group has also been involved in the development of new techniques such as magnetophotonic selection, picosecond Raman spectroscopy and phosphorescence microwave double resonance spectroscopy. A major focus of his lab is currently on the optical and chemical properties of noble metal nanoparticles and their applications in nanocatalysis, nanophotonics and nanomedicine. His lab is known for the development of the gold nanorod technology. As of 2021, El-Sayed has produced over 1200 publications in refereed journals in the areas of spectroscopy, molecular dynamics and nanoscience, with over 130,000 citations. | 1 | Applied and Interdisciplinary Chemistry |
Beta attenuation monitoring (BAM) is a widely used air monitoring technique employing the absorption of beta radiation by solid particles extracted from air flow. This technique allows for the detection of PM and PM, which are monitored by most air pollution regulatory agencies. The main principle is based on a kind of Bouguer (Lambert–Beer) law: the amount by which the flow of beta radiation (electrons) is attenuated by a solid matter is exponentially dependent on its mass and not on any other feature (such as density, chemical composition or some optical or electrical properties) of this matter. So, the air is drawn from outside of the detector through an "infinite" (cycling) ribbon made from some filtering material so that the particles are collected on it. There are two sources of beta radiation placed one before and one after the region where air flow passes through the ribbon leaving particles on it; and there are also two detectors on the opposite side of the ribbon, facing the detectors. The sources intensity and detectors sensitivity being the same (or corrected with appropriate calibration lookup table), the intensity of beta rays detected by one of detectors is compared to that of the other. Thus one can deduce how much mass has the ribbon acquired upon being exposed to air flow; knowing the drain velocity, actual particle mass concentration in air could be assessed.
The radiation source can be a gas chamber, filled with Kr gas, or a pieces of C-rich polymer plastic, such as PMMA. Detector is simply a Geiger–Mueller counter. The particulate matter content measured is affected by the moisture content in the air, unfortunately.
To discriminate between particle of different sizes (e. g., between PM and PM), some preliminary separation could be accomplished, for example, by cyclone battery.
A similar method exists, where instead of beta particle flow an X-ray Fluorescence Spectroscopic monitoring is applied on the either side of air flow contact with the ribbon. This allows to obtain not only cumulative measurement of particle mass, but also to detect their average chemical composition (technique works for potassium and elements heavier than it). | 0 | Theoretical and Fundamental Chemistry |
The movement of adatoms across a surface can be described by the Burton, Cabrera and Frank (CBF) model. The model treats adatoms as a 2D gas on top of the surface. The adatoms diffuse with a diffusion constant D; they are desorbed back to the medium above with a rate of per atom and adsorbed with flux F.
The diffusion constant can be, when the concentration of particles is small, expressed as:
Where a is the hopping distance for the atom. E is the energy needed to pass the diffusion barrier. ν is the attempt frequency.
The CBF model obeys the following continuity equation:
Combining the steady states () with the following boundary conditions can lead to an expression for the velocity of the adatoms at each adsorption site.
The boundary conditions:
And: | 0 | Theoretical and Fundamental Chemistry |
When Tc is combined with a tin compound, it binds to red blood cells and can therefore be used to map circulatory system disorders. It is commonly used to detect gastrointestinal bleeding sites as well as ejection fraction, heart wall motion abnormalities, abnormal shunting, and to perform ventriculography. | 0 | Theoretical and Fundamental Chemistry |
Aluminium surface composites with enhanced surface properties can be fabricated using FSP. Aluminium surface composites fabricated with the optimum friction stir processing parameters show better mechanical properties and corrosion resistance. The processing parameters such as tool rotational speed and tool shoulder diameter affects the surface properties. Higher surface hardness is exhibited by the surface composites fabricated at higher tool rotational speed and lower tool shoulder diameter. The properties of the composite materials can be altered by changing the type of reinforcement. Reinforcement particles aids in the grain size refinement as well as the property enhancement in the processed materials. The surface composite properties can be varied by changing the reinforcement particles based on the end application. The reinforcement phases can be metallic, ceramic, or polymer materials. | 1 | Applied and Interdisciplinary Chemistry |
Another possible biosignature might be morphology since the shape and size of certain objects may potentially indicate the presence of past or present life. For example, microscopic magnetite crystals in the Martian meteorite ALH84001 are one of the longest-debated of several potential biosignatures in that specimen. The possible biomineral studied in the Martian ALH84001 meteorite includes putative microbial fossils, tiny rock-like structures whose shape was a potential biosignature because it resembled known bacteria. Most scientists ultimately concluded that these were far too small to be fossilized cells. A consensus that has emerged from these discussions, and is now seen as a critical requirement, is the demand for further lines of evidence in addition to any morphological data that supports such extraordinary claims. Currently, the scientific consensus is that "morphology alone cannot be used unambiguously as a tool for primitive life detection". Interpretation of morphology is notoriously subjective, and its use alone has led to numerous errors of interpretation. | 1 | Applied and Interdisciplinary Chemistry |
Base flipping was first observed in 1994 when researchers Klimasauskas, Kumar, Roberts, and Cheng used X-ray crystallography to view an intermediate step in the chemical reaction of a methyltransferase bound to DNA. The methyltransferase they used was the C5-cytosine methyltransferase from Haemophilus haemolyticus (M. HhaI). This enzyme recognizes a specific sequence of the DNA (5-GCGC-3) and methylates the first cytosine base of the sequence at its C5 location. Upon crystallization of the M. HhaI-DNA complex, they saw the target cytosine base was rotated completely out of the double helix and was positioned in the active site of the M. HhaI. It was held in place by numerous interactions between the M. HhaI and DNA.
The authors theorized that base flipping was a mechanism used by many other enzymes, such as helicases, recombination enzymes, RNA polymerases, DNA polymerases, and Type II topoisomerases. Much research has been done in the years subsequent to this discovery and it has been found that base flipping is a mechanism used in many of the biological processes the authors suggest. | 1 | Applied and Interdisciplinary Chemistry |
The feedwater must be specially treated to avoid problems in the boiler and downstream systems. Untreated boiler feed water can cause corrosion and fouling. | 1 | Applied and Interdisciplinary Chemistry |
Corrosion is a major issue with neural electrodes. Corrosion can occur because electrode metals are placed in an electrolytic solution, where the presence of current can either increase the rate of corrosion mechanisms or overcome limiting activation energies. Redox reactions are a mechanism of corrosion that can lead to dissolution of ions from the electrode surface. There is a base level of metal ions in tissue, however, when these levels increase beyond threshold values the ions become toxic and can cause severe health problems. In addition, the fidelity of the electrode system can be compromised. Knowing the impedance of an electrode is important whether the electrode is used for stimulation or recording. When degradation of the electrode surface occurs because of corrosion, the surface area increases with its roughness. Calculating a new electrode impedance to compensate for the change in surface area once implanted it is not easy. This computational flaw can skew data from recording or pose a dangerous obstacle limiting safe stimulation. | 0 | Theoretical and Fundamental Chemistry |
Common treatments used for toxic substance ingestions are ineffective, or are even harmful, when implemented in ingestions of caustic substances. Clinical attempts to empty the stomach can cause further injuries. Activated charcoal does not neutralize caustics and can also obscure endoscopic visualization. There is no known clinical benefit of neutralization of the caustic substances; neutralization releases heat as well as causing gaseous distention and vomiting, all of which can worsen injuries.
Signs of airway compromise including decreased level of consciousness, stridor, change in voice, inability to control oral secretions necessitate intubation and mechanical ventillation. IV fluids are often needed to maintain hydration and replace insensible water losses.
Endoscopy should be done within the first 24–48 hours of ingestion as subsequent wound softening increases the risk of perforation. Endoscopically inserted nasogastric tubes can serve as a stent to prevent esophageal strictures as well as allow tube feedings. A CT scan, often enhanced with contrast, can also be used to evaluate injuries.
The most common surgical methods of treatment in children include esophageal dilation and esophageal replacement as less commonly implantation of an esophageal stent. | 1 | Applied and Interdisciplinary Chemistry |
The types of systems vary greatly from a single impact sprinkler placed on a roof, systems installed during construction with sprays on all windows and doors, and small sprays damping gutters. Some are installed using copper piping and sprays while others use common PVC piping.
Usage depends on type of risk and belief of effectiveness. Copper piping is used to withstand high temperatures that may be experienced during a fire front or for higher reliability for in ceiling installations. External PVC piping is used where failure with exposure to high radiant heat is acceptable, as at the time the system is considered have "done its job". This is a matter of personal judgment. | 1 | Applied and Interdisciplinary Chemistry |
Thionyl chloride has a long shelf life, however "aged" samples develop a yellow hue, possibly due to the formation of disulfur dichloride. It slowly decomposes to SCl, SO and Cl at just above the boiling point. Thionyl chloride is susceptible to photolysis, which primarily proceeds via a radical mechanism. Samples showing signs of ageing can be purified by distillation under reduced pressure, to give a colourless liquid. | 0 | Theoretical and Fundamental Chemistry |
In order to terminate the integrated stress response, dephosphorylation of eIF2α is required. The protein phosphatase 1 complex (PP1) aids in the dephosphorylation of eIF2α. This complex contains a PP1 catalytic subunit as well as two regulatory subunits. This complex is negatively regulated by two proteins: growth arrest and DNA damage‐inducible protein (GADD34), also known as PPP1R15A, or constitutive repressor of eIF2α phosphorylation (CReP), also known as PPP1R15B. CReP acts to keep levels of eIF2α phosphorylation low in cells under normal conditions. GADD34 is produced in response to ATF4 and works to increase dephosphorylation of eIF2α. The dephosphorylation of eIF2α results in the return of normal protein synthesis and cellular function. However, dephosphorylation of eIF2α can also facilitate the production of death-inducing proteins in cases where the cell is so severely damaged that normal functioning cannot be restored. | 1 | Applied and Interdisciplinary Chemistry |
An economizer serves a similar purpose to a feedwater heater, but is technically different as it does not use cycle steam for heating. In fossil-fuel plants, the economizer uses the lowest-temperature flue gas from the furnace to heat the water before it enters the boiler proper. This allows for the heat transfer between the furnace and the feedwater to occur across a smaller average temperature gradient (for the steam generator as a whole). System efficiency is therefore further increased when viewed with respect to actual energy content of the fuel.
Most nuclear power plants do not have an economizer. However, the Combustion Engineering System 80+ nuclear plant design and its evolutionary successors, (e.g. Korea Electric Power Corporation's APR-1400) incorporate an integral feedwater economizer. This economizer preheats the steam generator feedwater at the steam generator inlet using the lowest-temperature primary coolant. | 1 | Applied and Interdisciplinary Chemistry |
Depending on the quality of the result produced, assays may be classified into:
# Qualitative assays, i.e. assays which generally give just a pass or fail, or positive or negative or some such sort of only small number of qualitative gradation rather than an exact quantity.
#Semi-quantitative assays, i.e. assays that give the read-out in an approximate fashion rather than an exact number for the quantity of the substance. Generally they have a few more gradations than just two outcomes, positive or negative, e.g. scoring on a scale of 1+ to 4+ as used for blood grouping tests based on RBC agglutination in response to grouping reagents (antibody against blood group antigens).
# Quantitative assays, i.e. assays that give accurate and exact numeric quantitative measure of the amount of a substance in a sample. An example of such an assay used in coagulation testing laboratories for the most common inherited bleeding disease - Von Willebrand disease is VWF antigen assay where the amount of VWF present in a blood sample is measured by an immunoassay.
# Functional assays, i.e. an assay that tries to quantify functioning of an active substance rather than just its quantity. The functional counterpart of the VWF antigen assay is Ristocetin Cofactor assay, which measures the functional activity of the VWF present in a patient's plasma by adding exogenous formalin-fixed platelets and gradually increasing quantities of drug named ristocetin while measuring agglutination of the fixed platelets. A similar assay but used for a different purpose is called Ristocetin Induced Platelet Aggregation or RIPA, which tests response of endogenous live platelets from a patient in response to Ristocetin (exogenous) & VWF (usually endogenous). | 1 | Applied and Interdisciplinary Chemistry |
Colloidal crystals are receiving increased attention, largely due to their mechanisms of ordering and self-assembly, cooperative motion, structures similar to those observed in condensed matter by both liquids and solids, and structural phase transitions. Phase equilibrium has been considered within the context of their physical similarities, with appropriate scaling, to elastic solids. Observations of the interparticle separation distance has shown a decrease on ordering. This led to a re-evaluation of Langmuir's beliefs about the existence of a long-range attractive component in the interparticle potential.
Colloidal crystals have found application in optics as photonic crystals. Photonics is the science of generating, controlling, and detecting photons (packets of light), particularly in the visible and near Infrared, but also extending to the Ultraviolet, Infrared and far IR portions of the electromagnetic spectrum. The science of photonics includes the emission, transmission, amplification, detection, modulation, and switching of lightwaves over a broad range of frequencies and wavelengths. Photonic devices include electro-optic components such as lasers (Light Amplification by Stimulated Emission of Radiation) and optical fiber. Applications include telecommunications, information processing, illumination, spectroscopy, holography, medicine (surgery, vision correction, endoscopy), military (guided missile) technology, agriculture and robotics.
Polycrystalline colloidal structures have been identified as the basic elements of submicrometre colloidal materials science.
Molecular self-assembly has been observed in various biological systems and underlies the formation of a wide variety of complex biological structures. This includes an emerging class of mechanically superior biomaterials based on microstructure features and designs found in nature.
The principal mechanical characteristics and structures of biological ceramics, polymer composites, elastomers, and cellular materials are being re-evaluated, with an emphasis on bioinspired materials and structures. Traditional approaches focus on design methods of biological materials using conventional synthetic materials. The uses have been identified in the synthesis of bioinspired materials through processes that are characteristic of biological systems in nature. This includes the nanoscale self-assembly of the components and the development of hierarchical structures. | 0 | Theoretical and Fundamental Chemistry |
A number of materials contract on heating within certain temperature ranges; this is usually called negative thermal expansion, rather than "thermal contraction". For example, the coefficient of thermal expansion of water drops to zero as it is cooled to 3.983 °C and then becomes negative below this temperature; this means that water has a maximum density at this temperature, and this leads to bodies of water maintaining this temperature at their lower depths during extended periods of sub-zero weather.
Other materials are also known to exhibit negative thermal expansion. Fairly pure silicon has a negative coefficient of thermal expansion for temperatures between about 18 and 120 kelvin. ALLVAR Alloy 30, a titanium alloy, exhibits anisotropic negative thermal expansion across a wide range of temperatures. | 0 | Theoretical and Fundamental Chemistry |
The Lyman-alpha transition in hydrogen in the presence of the spin–orbit interaction involves the transitions
: and
In the presence of an external magnetic field, the weak-field Zeeman effect splits the 1S and 2P levels into 2 states each () and the 2P level into 4 states (). The Landé g-factors for the three levels are:
: for (j=1/2, l=0)
: for (j=1/2, l=1)
: for (j=3/2, l=1).
Note in particular that the size of the energy splitting is different for the different orbitals, because the g values are different. On the left, fine structure splitting is depicted. This splitting occurs even in the absence of a magnetic field, as it is due to spin–orbit coupling. Depicted on the right is the additional Zeeman splitting, which occurs in the presence of magnetic fields. | 0 | Theoretical and Fundamental Chemistry |
The 3rd analytical group of cations includes ions which form hydroxides that are insoluble even at low concentrations.
Cations in the 3rd group are, among others: Fe, Fe, Al, and Cr.
The group is determined by making a solution of the salt in water and adding ammonium chloride and ammonium hydroxide. Ammonium chloride is added to ensure low concentration of hydroxide ions.
The formation of a reddish-brown precipitate indicates Fe; a gelatinous white precipitate indicates Al; and a green precipitate indicates Cr or Fe. These last two are distinguished by adding sodium hydroxide in excess to the green precipitate. If the precipitate dissolves, Cr is indicated; otherwise, Fe is present. | 0 | Theoretical and Fundamental Chemistry |
Three molecular stages are required for actively, enzymatically reprogramming the DNA methylome. Stage 1: Recruitment. The enzymes needed for reprogramming are recruited to genome sites that require demethylation or methylation. Stage 2: Implementation. The initial enzymatic reactions take place. In the case of methylation, this is a short step that results in the methylation of cytosine to 5-methylcytosine. Stage 3: Base excision DNA repair. The intermediate products of demethylation are catalysed by specific enzymes of the base excision DNA repair pathway that finally restore cystosine in the DNA sequence. | 1 | Applied and Interdisciplinary Chemistry |
At the beginning of the twentieth century, as steel production became more dependent on the use of electric arc furnace technology in mini-mill environments, the convenient transportation of scrap metal became a competitive advantage of manufacturers, so the availability of geographical resources was no longer the most significant driving force for iron-and-steel production growth. The Birmingham area began to invest in building the earliest mini-mills, and continued to have a strong foundry emphasis, attracting many large cast-iron pipe producers, such as American Cast Iron Pipe Company. Headquartered in Birmingham in 1905, American Cast Iron Pipe Company, with its 2,100 acre site and 2,400 employees at its operations, became the worlds largest iron pipe casting plant. With advanced expertise and the latest technological innovations, Birmingham furnaces produced millions of tons of pig iron from 1990s to 1970s. A half of the produced pig iron was used for steel production, and the other half was sold as foundry iron. This trend reflected that the regions iron ore was of poor quality, so manufacturers had difficulties in extracting it. This is a geological factor that limited the further development of Alabama's iron and steel industry, despite the help of advanced technology and innovative smelting practices. | 1 | Applied and Interdisciplinary Chemistry |
The time evolution of a single electronic wave function in an atom, is described by the Schrödinger equation (in atomic units):
where the light-matter interaction Hamiltonian, , can be expressed in the length gauge, within the dipole approximation, as:
where is the Coulomb potential of the atomic species considered; are the momentum and position operator, respectively; and is the total electric field evaluated in the neighbor of the atom.
The formal solution of the Schrödinger equation is given by the propagator formalism:
where , is the electron wave function at time .
This exact solution cannot be used for almost any practical purpose.
However, it can be proved, using Dyson's equations that the previous solution can also be written as:
where,
is the bounded Hamiltonian and
is the interaction Hamiltonian.
The formal solution of Eq. , which previously was simply written as Eq. , can now be regarded in Eq. as a superposition of different quantum paths (or quantum trajectory), each one of them with a peculiar interaction time with the electric field.
In other words, each quantum path is characterized by three steps:
# An initial evolution without the electromagnetic field. This is described by the left-hand side term in the integral.
# Then, a "kick" from the electromagnetic field, that "excite" the electron. This event occurs at an arbitrary time that uni-vocally characterizes the quantum path .
#A final evolution driven by both the field and the Coulomb potential, given by .
In parallel, you also have a quantum path that do not perceive the field at all, this trajectory is indicated by the right-hand side term in Eq. .
This process is entirely time-reversible, i.e. can also occur in the opposite order.
Equation is not straightforward to handle. However, physicists use it as the starting point for numerical calculation, more advanced discussion or several approximations.
For strong-field interaction problems, where ionization may occur, one can imagine to project Eq. in a certain continuum state (unbounded state or free state) , of momentum , so that:
where <math>|c_{\textbf{p}}(t)|^2
, the electron in the continuum states .
If this probability amplitude is greater than zero, the electron is photoionized.
For the majority of application, the second term in is not considered, and only the first one is used in discussions, hence:
Equation is also known as time reversed S-matrix amplitude and it gives the probability of photoionization by a generic time-varying electric field. | 0 | Theoretical and Fundamental Chemistry |
Carbon tetrachloride was briefly used as a volatile inhalation anaesthetic and analgesic for intense menstruation pains and headaches in the mid-19th century. Its anaesthetic effects were known as early as 1847 or 1848.
It was introduced as a safer alternative to Chloroform by Doctor Protheroe Smith in 1864. In December 1865, the Scottish obstetrician who discovered the anaesthetic effects of chloroform on humans, James Young Simpson, had experimented with carbon tetrachloride as an anaesthetic. Simpson named the compound "Chlorocarbon" for its similarity to chloroform. His experiments involved injecting carbon tetrachloride into two women's vaginas. Simpson orally consumed carbon tetrachloride and described it as having "the same effect as swallowing a capsule of chloroform".
Because of the higher amount of chlorine atoms (compared to chloroform) in its molecule, carbon tetrachloride has a stronger anaesthetic effect than chloroform and required a smaller amount. Its anaesthetic action was likened to ether, rather than the related chloroform. It is less volatile than chloroform, therefore it was more difficult to apply and needed warm water to evaporate. Its smell has been described as "fruity", quince-like and "more pleasant than chloroform", and had a "pleasant taste". Carbon tetrachloride for anaesthetic use was made by the chlorination of carbon disulfide. It was used on at least 50 patients, of which most were women in labour. During anaesthesia, carbon tetrachloride has caused violent muscular contractions and negative effects on the heart in some patients that it had to be substituted with chloroform or ether. Such use was experimental and the anaesthetic use of carbon tetrachloride never gained popularity due to its potential toxicity. | 1 | Applied and Interdisciplinary Chemistry |
Individual surfactant molecules that are in the system but are not part of a micelle are called "monomers". Micelles represent a molecular assembly, in which the individual components are thermodynamically in equilibrium with monomers of the same species in the surrounding medium. In water, the hydrophilic "heads" of surfactant molecules are always in contact with the solvent, regardless of whether the surfactants exist as monomers or as part of a micelle. However, the lipophilic "tails" of surfactant molecules have less contact with water when they are part of a micelle—this being the basis for the energetic drive for micelle formation. In a micelle, the hydrophobic tails of several surfactant molecules assemble into an oil-like core, the most stable form of which having no contact with water. By contrast, surfactant monomers are surrounded by water molecules that create a "cage" or solvation shell connected by hydrogen bonds. This water cage is similar to a clathrate and has an ice-like crystal structure and can be characterized according to the hydrophobic effect. The extent of lipid solubility is determined by the unfavorable entropy contribution due to the ordering of the water structure according to the hydrophobic effect.
Micelles composed of ionic surfactants have an electrostatic attraction to the ions that surround them in solution, the latter known as counterions. Although the closest counterions partially mask a charged micelle (by up to 92%), the effects of micelle charge affect the structure of the surrounding solvent at appreciable distances from the micelle. Ionic micelles influence many properties of the mixture, including its electrical conductivity. Adding salts to a colloid containing micelles can decrease the strength of electrostatic interactions and lead to the formation of larger ionic micelles. This is more accurately seen from the point of view of an effective charge in hydration of the system. | 0 | Theoretical and Fundamental Chemistry |
Albert Rakoto Ratsimamanga is considered one of Madagascars most renowned scholars. A commemorative stamp was issued in his memory in 2002, and the Institut de France minted a coin tribute to Ratsimamanga. Ratsimamangas legacy can be seen as a | 1 | Applied and Interdisciplinary Chemistry |
Reactions of organocopper reagents involve species containing copper-carbon bonds acting as nucleophiles in the presence of organic electrophiles. Organocopper reagents are now commonly used in organic synthesis as mild, selective nucleophiles for substitution and conjugate addition reactions.
Since the discovery that copper(I) halides catalyze the conjugate addition of Grignard reagents in 1941, organocopper reagents have emerged as weakly basic, nucleophilic reagents for substitution and addition reactions. The constitution of organocopper compounds depends on their method of preparation and the various kinds of organocopper reagents exhibit different reactivity profiles. As a result, the scope of reactions involving organocopper reagents is extremely broad.
* Organocopper complexes (RCu) are produced when a copper(I) halide and organolithium are combined. In conjunction with Lewis acidic additives such as boron trifluoride etherate, these reagents are used for conjugate addition reactions.
* Lower-order cuprates (RCuLi, also known as Gilman reagents) result when organocopper complexes are treated with an equivalent of organolithium. Alternatively, they may be formed by the treatment of a copper(I) halide with two equivalents of organolithium. They undergo substitution, conjugate addition, and carbocupration reactions in the presence of the appropriate organic substrates. Mixed Gilman reagents consist of two different R groups, one of which is typically a non-transferable "dummy" group.
* Lower-order cyanocuprates (RCu(CN)Li) are similarly derived from an organolithium compound and copper(I) cyanide; however, intermediate organocopper complexes do not form during this reaction and thus only a single equivalent of organolithium reagent is necessary. Cyanocuprates undergo S2' substitution in the presence of allyl electrophiles and conjugate addition reactions in the presence of enones.
* Higher-order cyanocuprates (RCu(CN)Li) are formed upon the reaction of two equivalents of organolithium with copper(I) cyanide. These reagents are more reactive towards substitution than the corresponding lower-order cyanocuprates. | 0 | Theoretical and Fundamental Chemistry |
The presence of these many allotropes makes machining plutonium very difficult, as it changes state very readily. For example, the α phase exists at room temperature in unalloyed plutonium. It has machining characteristics similar to cast iron but changes to the β phase (beta phase) at slightly higher temperatures. The reasons for the complicated phase diagram are not entirely understood; recent research has focused on constructing accurate computer models of the phase transitions. The α phase has a low-symmetry monoclinic structure, hence its poor conductivity, brittleness, strength and compressibility. | 0 | Theoretical and Fundamental Chemistry |
Pharmaceutical bioinformatics is a research field related to bioinformatics but with the focus on studying biological and chemical processes in the pharmaceutical area; to understand how xenobiotics interact with the human body and the drug discovery process. | 1 | Applied and Interdisciplinary Chemistry |
Hays test, also known as Hays sulphur powder test, is a chemical test used for detecting the presence of bile salts in urine. | 0 | Theoretical and Fundamental Chemistry |
Long noncoding RNAs (lncRNAs) are large transcripts (more than 200 nucleotides long) that have similar mechanism of synthesis as that of mRNAs but unlike mRNAs, lncRNAs are not translated to a protein. lncRNA contains interactor elements and structural elements. Interactor elements directly interact with other nucleic acids or proteins while the structural elements indicate the ability of some lncRNAs to form secondary and/or tertiary structures. This ability of the lncRNAs to interact with nucleic acids using its interactor elements and its ability to interact with protein using its secondary structures allows it to function in a more diverse manner than other ncRNAs such as miRNA (microRNA). LncRNA has been established to play a role in gene regulation by influencing the ability of specific regions of the gene to bind to transcriptional elements and different epigenetic modifications. One such example can be seen in the case X inactive specific transcript (XIST). In humans, 46,XX females carry an extra X chromosome (155Mb of DNA) compared to 46,XY males. To overcome this dosage imbalance, one X chromosome is randomly inactivated in human females at around the 2-8 cell stage of embryo development. This inactivation is very stable across cell divisions due to epigenetic contributions both during the initial silencing and the subsequent maintenance of the inactive X chromosome (Xi). This inactivation is carried by the lncRNA, XIST. XIST is produced in cis and inactivates the X-chromosome that it has been generated from. The inactive X chromosome can be observed as a condensed heterochromatin structure called “Barr Body”.
A study in 2013 utilized this ability of XIST as a potential therapeutic approach for treatment of trisomy 21. Trisomy 21 is commonly known as down syndrome and is caused due to presence of an additional copy of chromosome 21. The study was one of its kind as no other studies have been able to incorporate the XIST gene into a chromosome due to its large size. The study incorporated the XIST into one of the chromosomes 21 in the cells gathered from patients with down syndrome. The study was able to observe the inactivation of one of chromosome 21 in the form of a condensed heterochromatin and labeled it as a chromosome 21 barr body. Such experiments have shown to work in cells in the lab setting although no lncRNA based therapeutics are in clinical trials. The implications of such work can bring trisomy 21 and other chromosomal disorders in the realm of consideration for future gene therapy research. | 1 | Applied and Interdisciplinary Chemistry |
Two-component systems accomplish signal transduction through the phosphorylation of a response regulator (RR) by a histidine kinase (HK). Histidine kinases are typically homodimeric transmembrane proteins containing a histidine phosphotransfer domain and an ATP binding domain, though there are reported examples of histidine kinases in the atypical [http://pfam.xfam.org/family/PF07536 HWE] and [http://pfam.xfam.org/family/PF07568 HisKA2] families that are not homodimers. Response regulators may consist only of a receiver domain, but usually are multi-domain proteins with a receiver domain and at least one effector or output domain, often involved in DNA binding. Upon detecting a particular change in the extracellular environment, the HK performs an autophosphorylation reaction, transferring a phosphoryl group from adenosine triphosphate (ATP) to a specific histidine residue. The cognate response regulator (RR) then catalyzes the transfer of the phosphoryl group to an aspartate residue on the response regulators receiver domain. This typically triggers a conformational change that activates the RRs effector domain, which in turn produces the cellular response to the signal, usually by stimulating (or repressing) expression of target genes.
Many HKs are bifunctional and possess phosphatase activity against their cognate response regulators, so that their signaling output reflects a balance between their kinase and phosphatase activities. Many response regulators also auto-dephosphorylate, and the relatively labile phosphoaspartate can also be hydrolyzed non-enzymatically. The overall level of phosphorylation of the response regulator ultimately controls its activity. | 1 | Applied and Interdisciplinary Chemistry |
A Maclaurin spheroid is an oblate spheroid which arises when a self-gravitating fluid body of uniform density rotates with a constant angular velocity. This spheroid is named after the Scottish mathematician Colin Maclaurin, who formulated it for the shape of Earth in 1742. In fact the figure of the Earth is far less oblate than Maclaurin's formula suggests, since the Earth is not homogeneous, but has a dense iron core. The Maclaurin spheroid is considered to be the simplest model of rotating ellipsoidal figures in hydrostatic equilibrium since it assumes uniform density. | 1 | Applied and Interdisciplinary Chemistry |
Expanded bed adsorption (EBA) is a preparative chromatographic technique which makes processing of viscous and particulate liquids possible. | 1 | Applied and Interdisciplinary Chemistry |
Crystalloluminescence is the effect of luminescence produced during crystallization. The phenomenon was first reported in the 1800s from the rapid crystallization of potassium sulfate from an aqueous solution. | 0 | Theoretical and Fundamental Chemistry |
The paper used for fuel filters is a crêped paper with controlled porosity, which is pleated and wound to cartridges. The raw material for filter paper used in fuel filters are made of a mixture of hardwood and softwood fibres. The basis weight of the paper is 50–80 g/m. | 0 | Theoretical and Fundamental Chemistry |
In some very economically important flowers like roses, carnations and chrysanthemums despite a lot of efforts was not possible to breed the flowers with blue petals coloration. The lack of F35H enzyme and hence delphinidin type anthocyanin is the reason why blue flower colour was not possible to obtain. | 1 | Applied and Interdisciplinary Chemistry |
The second term on the right hand side of (3) is the structure factor.
For a given reciprocal lattice vector (corresponding to a family of lattice planes labeled by Miller indices ), the intensity of scattered particles is proportional to the square of the structure factor.
Buried in (6) are detailed aspects of the crystal structure that are worth distinguishing and discussing. | 0 | Theoretical and Fundamental Chemistry |
Ideally, the reference set in CAI is composed of highly expressed genes, so that CAI provides an indication of gene expression level under the assumption that there is translational selection to optimize gene sequences according to their expression levels. The rationale for this is dual: highly expressed genes need to compete for resources (i.e. ribosomes) in fast-growing organisms and it makes sense for them to be also more accurately translated. Both hypotheses lead to highly expressed genes using mostly codons for tRNA species that are abundant in the cell. | 1 | Applied and Interdisciplinary Chemistry |
From 1787 to 1802, it was determined by Jacques Charles (unpublished), John Dalton, and Joseph Louis Gay-Lussac that, at constant pressure, ideal gases expanded or contracted their volume linearly (Charless law) by about 1/273 parts per degree Celsius of temperatures change up or down, between 0° and 100 °C. This suggested that the volume of a gas cooled at about −273 °C would reach zero.
In October 1848, William Thomson, a 24 year old professor of Natural Philosophy at the University of Glasgow, published the paper On an Absolute Thermometric Scale.
In a footnote Thomson calculated that "infinite cold" (absolute zero) was equivalent to −273 °C (he called the temperature in °C as the "temperature of the air thermometers" of the time). This value of "−273" was considered to be the temperature at which the ideal gas volume reaches zero. By considering a thermal expansion linear with temperature (i.e. a constant coefficient of thermal expansion), the value of absolute zero was linearly extrapolated as the negative reciprocal of 0.366/100 °C – the accepted average coefficient of thermal expansion of an ideal gas in the temperature interval 0–100 °C, giving a remarkable consistency to the currently accepted value of −273.15 °C. | 0 | Theoretical and Fundamental Chemistry |
Inductively coupled plasma mass spectrometry (ICP-MS) is a type of mass spectrometry that uses an inductively coupled plasma to ionize the sample. It atomizes the sample and creates atomic and small polyatomic ions, which are then detected. It is known and used for its ability to detect metals and several non-metals in liquid samples at very low concentrations. It can detect different isotopes of the same element, which makes it a versatile tool in isotopic labeling.
Compared to atomic absorption spectroscopy, ICP-MS has greater speed, precision, and sensitivity. However, compared with other types of mass spectrometry, such as thermal ionization mass spectrometry (TIMS) and glow discharge mass spectrometry (GD-MS), ICP-MS introduces many interfering species: argon from the plasma, component gases of air that leak through the cone orifices, and contamination from glassware and the cones. | 0 | Theoretical and Fundamental Chemistry |
Organoberyllium chemistry is limited to academic research due to the cost and toxicity of beryllium.
Organoberyllium compounds consist of a beryllium atom with an organic group attached. There are very few reported case of Be(I) and Be(0) oxidation states. Instead, Be has a +2 oxidation state, and higher charge density than any other group 2 element. Organometallic beryllium compounds are highly reactive strong acids. Beryllium has a high electronegativity compare to other group 2 elements; thus the resulting C-Be bonds are less highly polarized than other C-M bonds, although the attached carbon still bears a negative dipole moment.
Lighter organoberyllium compounds are often considered covalent, but with some ionic bond characteristics. From this perspective, the C-Be bonds are much more ionic and highly polarized than other C-R bonds. This higher ionic character and bond polarization tends to produce high coordination numbers. Many compounds, particularly dialklys, are polymeric in solid or liquid states with highly complex structures in solution; in the gaseous state, they often revert to monomers. A good example is beryllium borohydride, which dimerizes to form three-center two-electron bonds.
Compounds such as these hydrides can coordinate with carbenes such as N-heterocyclic carbene to form crystals. The propensity for co-crystallization suggests applications in organocatalysis. | 0 | Theoretical and Fundamental Chemistry |
HOT was founded to understand the processes controlling the fluxes of carbon and associated bioelements in the ocean and to document changes in the physical structure of the water column. To achieve this, the HOT program has several specific goals:
:1. Quantify temporal (seasonal to decadal) changes in reservoirs and fluxes of carbon and associated bioelements (nitrogen, oxygen, phosphorus, and silicon).
:2. Identify processes controlling air-sea carbon exchange, rates of carbon transformation through the planktonic food web, and fluxes of carbon into the ocean.
:3. Form a multi-decadal baseline based on the gathered data that will allow researchers to decipher natural and anthropogenic influences on the NPSG ecosystem.
:4. Provide scientific and logistical support to other scientific programs that benefit from the research and services performed by the HOT program. This includes projects implementing, testing, and validating new methodologies, models, and transformative ocean sampling technologies.
The dissolved inorganic carbon data set that has been accumulated over the course of the HOT program shows the increase of carbon dioxide in the surface waters of the Pacific and subsequent acidification of the ocean. The data collected by these cruises are available online.
The 200th cruise of the HOT program was in 2008. HOT recently celebrated its 25th year in operation, with the 250th research cruise occurring in March 2013. | 0 | Theoretical and Fundamental Chemistry |
The sum activity of peripheral deiodinases (G, also referred to as SPINA-GD) is reduced in nonthyroidal illness with hypodeiodination.
G is obtained with
or
: Dilution factor for T3 (reciprocal of apparent volume of distribution, 0.026 L)<br />
: Clearance exponent for T3 (8e-6 sec)<br />
K: Dissociation constant of type-1-deiodinase (5e-7 mol/L)<br />
K: Dissociation constant T3-TBG (2e9 L/mol) | 1 | Applied and Interdisciplinary Chemistry |
Molten Oxide Electrolysis in steelmaking is utilizing electrons as the reducing agent instead of coke as in conventional blast furnace. For steel production, this method uses an inert anode (Carbon, Platinum, Iridium or Chromium-based alloy) and places iron ore in the cathode. The electrochemical reaction in this Molten Oxide cell can reach up to 1600 °C, a temperature that melts iron ore and electrolyte oxide. Then the molten iron ore decompose following this reaction.
The electrolysis reaction will produce molten pure iron as a main product and oxygen as its by-product. Because this process does not add coke in the process, no CO gas is produced. So no direct greenhouse gas emission. Moreover, if the electricity to run such cells comes from renewable sources, this process may have zero emissions. This technology also can be implemented for producing Nickel, Chromium, and Ferrochromium.
Currently Massachusetts-based Boston Metal company is in a process to scale up this technology to an industrial level. | 1 | Applied and Interdisciplinary Chemistry |
Healey and Woodall were not able to analyze any sediments underneath more than one meter (3.3 ft) of water because the particles were too fine for the Ekman dredge sifter that they used. In 2013 Sarah Shenstone-Harris, a University of Toronto undergraduate interning at the schools Centre for Global Climate Science, was able to analyze the sediments. She looked to the diatoms in them to try to see if climate change had played a role in the lakes decline. If so, she also asked, when did that change occur, and was it possible to restore the lake to a level of water quality comparable to what it had been prior to the establishment of Yellowknife?
Shenstone-Harris started from the observation that subarctic lakes generally had shown great sensitivity to climate change because of shifts in the amount of ice cover. Those stresses could be exacerbated for subarctic lakes in an urban area facing higher levels of pollution from a number of different sources, such as Frame. Her inquiry was a paleolimnological one, focusing on the algae species present in the lake at various times in the recent past. She took core samples of the sediment down to and dated them by the lead-210 levels. Once their age was established, she looked at the diatom remains, since the species of algae in the water can reflect environmental changes, and counted the ratio of chrysophyte stomatocysts to establish nutrient levels in the water at that time.
Due to diatom dissolution at the lowest level of the sediments taken, Shenstone-Harris was unable to establish data for any years earlier than 1943, making it impossible to set the desired baseline for a pre-settlement Frame Lake. However, she was able to establish that the lake had always been at a high trophic state, even before it became fully eutrophied by the mid- to late-1990s. That was preceded by a rapid replacement of epiphytic species with benthic ones around 1990.
It was not clear to Shenstone-Harris that that event had been the result of climate change. From 1956 to 1992, the last year records were kept, ice cover on the lake remained relatively stable throughout the winter, yet the amount of Cyclotella and Fragliaria, two genera whose species have been shown to be responsive to changing ice cover and warming climates, varied considerably. This suggested to her that while climate change may be a factor in the lakes decline, it is not the only one. Instead, the change in species around 1990 pointed to a change in littoral zone microhabitat, a loss of macrophytes and mosses, as bearing the primary responsibility for tipping the lake to its present eutrophic state. However, the lack of data on ice cover since 1992 and her inability to determine the lakes status prior to the establishment of Yellowknife qualified that conclusion. "Alternatively", she wrote, "Frame Lake may be a subarctic anomaly and was always high in nutrients".
In 2015 the Carleton team was able to examine the sediments. They found that the period between the late 1940s and 1970 added a half-meter () of sediment to the bottom of the lake, the most of any lake in the region. Above it, the of sediment postdating the causeway was "black, sulfurous smelling and characterized by very high levels of metals, particularly arsenic". These are consistent with the patches of sediment Mallon recalled from his youthful recreation on the lake in his 2015 article, noting that "I can still vividly feel the stuff's gloopy embrace on my feet" (although an accompanying sidebar by another reporter suggested that the sediments may be the result of sewage back-flushed from Niven Lake). | 1 | Applied and Interdisciplinary Chemistry |
Form-based stream restoration promotes the modification of a stream channel to improve stream conditions. Targeted outcomes can include improved water quality, enhanced fish habitat and abundance, as well as increased bank and channel stability. This approach is widely used worldwide, and is supported by various government agencies, including the United States Environmental Protection Agency (U.S. EPA).
Form-based restoration projects can be carried out at various scales, including the reach scale. They can include measures such as the installation of in-stream structures, bank stabilization and more significant channel reconfiguration efforts. Reconfiguration work may focus on channel shape (in terms of sinuosity and meander characteristics), cross-section or channel profile (slope along the channel bed). These alterations affect the dissipation of energy through a channel, which impacts flow velocity and turbulence, water-surface elevations, sediment transport, and scour, among other characteristics. | 1 | Applied and Interdisciplinary Chemistry |
Fibrin-based scaffolds contain fibrin which gives the keratinocytes stability. Moreover, they are simple to reproduce and handle. | 1 | Applied and Interdisciplinary Chemistry |
In chemistry, the tricapped trigonal prismatic molecular geometry describes the shape of compounds where nine atoms, groups of atoms, or ligands are arranged around a central atom, defining the vertices of a triaugmented triangular prism (a trigonal prism with an extra atom attached to each of its three rectangular faces).
It is very similar to the capped square antiprismatic molecular geometry, and there is some dispute over the specific geometry exhibited by certain molecules. | 0 | Theoretical and Fundamental Chemistry |
In molecular biology, a GC box, also known as a GSG box, is a distinct pattern of nucleotides found in the promoter region of some eukaryotic genes. The GC box is upstream of the TATA box, and approximately 110 bases upstream from the transcription initiation site. It has a consensus sequence GGGCGG which is position-dependent and orientation-independent. The GC elements are bound by transcription factors and have similar functions to enhancers. Some known GC box-binding proteins include Sp1, Krox/Egr, Wilms' tumor, MIGI, and CREA.
The GC box is commonly the binding site for zinc finger proteins. An alpha helix section of the protein corresponds with a major groove in the DNA. Zinc-fingers bind to triplet base pair sequences, with residue 21 binding to the first base pair, residue 18 binding to the second base pair, and residue 15 binding to the third base pair. The triplet base pairs can either be a GGG or a GCG. If residue 18 is a histidine, it will bind to a G, and if residue 18 is a glutamate, it will bind to a C. GC box-binding zinc fingers have between 2 and 4 fingers, making them interact with base pair sequences that are 6 to 8 base pairs in length. | 1 | Applied and Interdisciplinary Chemistry |
Katsonis joined the Centre National de la Recherche Scientifique (CNRS) in 2007 and started to work on light-responsive chiral liquid crystals. She was made a Group Leader at the University of Groningen and held a visiting position at KU Leuven. In 2012 she was awarded a Royal Society International Exchange grant to work with Steve Fletcher on light responsive polymers. Katsonis proposed the materials could be used for microfluidics or soft robotics. Her research is inspired by nature, where helical structures are often created for movement.
She moved to the University of Twente in 2013, and was promoted to Professor in 2016. She returned to the University of Groningen as Professor of Active Molecular Systems in 2020. Katsonis has worked on squishy light responsive materials, which can convert light energy into mechanical work. She demonstrated that it is possible to switch between left and right-handed helixes in cholesteric liquid crystals using light. She has also showed that it is possible to use twisted liquid crystals as organising templates to design self-assemblies of superparamagnetic nanoparticles. In 2017 she was awarded a European Research Council Consolidator Grant in nanotechnology. Her recent work has been concerned with unravelling the molecular origin of purposeful motion, both in space and time at the nanoscale. | 0 | Theoretical and Fundamental Chemistry |
An organic azide is an organic compound that contains an azide (–) functional group. Because of the hazards associated with their use, few azides are used commercially although they exhibit interesting reactivity for researchers. Low molecular weight azides are considered especially hazardous and are avoided. In the research laboratory, azides are precursors to amines. They are also popular for their participation in the "click reaction" between an azide and an alkyne and in Staudinger ligation. These two reactions are generally quite reliable, lending themselves to combinatorial chemistry. | 0 | Theoretical and Fundamental Chemistry |
Grain boundary engineering involves manipulating the grain boundary structure and energy to enhance mechanical properties. By controlling the interfacial energy, it is possible to engineer materials with desirable grain boundary characteristics, such as increased interfacial area, higher grain boundary density, or specific grain boundary types.
* Alloying
Introducing alloying elements into the material can alter the interfacial energy of grain boundaries. Alloying can result in segregation of solute atoms at the grain boundaries, which can modify the atomic arrangements and bonding, and thereby influence the interfacial energy.
* Surface Treatments and Coatings
Applying surface treatments or coatings can modify the interfacial energy of grain boundaries. Surface modification techniques, such as chemical treatments or deposition of thin films, can alter the surface energy and consequently affect the grain boundary energy.
* Heat Treatments and Annealing
Thermal treatments can be employed to modify the interfacial energy of grain boundaries. Annealing at specific temperatures and durations can induce atomic rearrangements, diffusion, and stress relaxation at the grain boundaries, leading to changes in the interfacial energy.
Once the interfacial energy is controlled, grain boundaries can be manipulated to enhance their strengthening effects.
* Severe Plastic Deformation
Applying severe plastic deformation techniques, such as equal-channel angular pressing (ECAP) or high-pressure torsion (HPT), can lead to grain refinement and the creation of new grain boundaries with tailored characteristics. These refined grain structures can exhibit a high density of grain boundaries, including high-angle boundaries, which can contribute to enhanced grain boundary strengthening.
* Thermomechanical Processing
Utilizing specific thermomechanical processing routes, such as rolling, forging, or extrusion, can result in the creation of a desired texture and the development of specific grain boundary structures. These processing routes can promote the formation of specific grain boundary types and orientations, leading to improved grain boundary strengthening. | 1 | Applied and Interdisciplinary Chemistry |
The bacteria are typically fed with broken down agricultural waste or undesired crops, such as water lettuce or sugar beet molasses. The high abundance of such waste ensures the stable food source for the bacteria and productively uses human-produced waste. In comparison with dark fermentation, photofermentation produces more hydrogen per reaction and avoids the acidic end products of dark fermentation. | 1 | Applied and Interdisciplinary Chemistry |
The system of colloids and depletants in solution is typically modeled by treating the large colloids and small depletants as dissimilarly sized hard spheres. Hard spheres are characterized as non-interacting and impenetrable spheres. These two fundamental properties of hard spheres are described mathematically by the hard-sphere potential. The hard-sphere potential imposes steric constraint around large spheres which in turn gives rise to excluded volume, that is, volume that is unavailable for small spheres to occupy. | 0 | Theoretical and Fundamental Chemistry |
Virodhamine (O-arachidonoyl ethanolamine; O-AEA) is an endocannabinoid and a nonclassic eicosanoid, derived from arachidonic acid. O-Arachidonoyl ethanolamine is arachidonic acid and ethanolamine joined by an ester linkage, the opposite of the amide linkage found in anandamide. Based on this opposite orientation, the molecule was named virodhamine from the Sanskrit word virodha, which means opposition. It acts as an antagonist of the CB receptor and agonist of the CB receptor. Concentrations of virodhamine in the human hippocampus are similar to those of anandamide, but they are 2- to 9-fold higher in peripheral tissues that express CB. Virodhamine lowers body temperature in mice, demonstrating cannabinoid activity in vivo. | 1 | Applied and Interdisciplinary Chemistry |
The partition coefficient, abbreviated P, is defined as a particular ratio of the concentrations of a solute between the two solvents (a biphase of liquid phases), specifically for un-ionized solutes, and the logarithm of the ratio is thus log P. When one of the solvents is water and the other is a non-polar solvent, then the log P value is a measure of lipophilicity or hydrophobicity. The defined precedent is for the lipophilic and hydrophilic phase types to always be in the numerator and denominator respectively; for example, in a biphasic system of n-octanol (hereafter simply "octanol") and water:
To a first approximation, the non-polar phase in such experiments is usually dominated by the un-ionized form of the solute, which is electrically neutral, though this may not be true for the aqueous phase. To measure the partition coefficient of ionizable solutes, the pH of the aqueous phase is adjusted such that the predominant form of the compound in solution is the un-ionized, or its measurement at another pH of interest requires consideration of all species, un-ionized and ionized (see following).
A corresponding partition coefficient for ionizable compounds, abbreviated log P , is derived for cases where there are dominant ionized forms of the molecule, such that one must consider partition of all forms, ionized and un-ionized, between the two phases (as well as the interaction of the two equilibria, partition and ionization). M is used to indicate the number of ionized forms; for the -th form () the logarithm of the corresponding partition coefficient, , is defined in the same manner as for the un-ionized form. For instance, for an octanol–water partition, it is
To distinguish between this and the standard, un-ionized, partition coefficient, the un-ionized is often assigned the symbol log P, such that the indexed expression for ionized solutes becomes simply an extension of this, into the range of values . | 0 | Theoretical and Fundamental Chemistry |
The Clyde cancer cluster (also known as the Sandusky County cancer cluster) is a childhood cancer cluster that has affected many families in Clyde, Ohio, and surrounding areas. PCBs were found in soil in a public park within the area of the cancer cluster.
In Akron, Ohio, soil was contaminated and noxious PCB-laden fumes had been put into the air by an electrical transformer deconstruction operation from the 1930s to the 1960s. | 1 | Applied and Interdisciplinary Chemistry |
Particles are characterized by their individual size and shape, and by the distribution of these properties in bulk quantities. The space between particles in bulk means that the bulk density is less than the density of individual particles. The way in which they move over each other or lock together determines stability or flowability, which is tested by the triaxial shear test. | 1 | Applied and Interdisciplinary Chemistry |
The division between prokaryotes and eukaryotes is usually considered the most important distinction or difference among organisms. The distinction is that eukaryotic cells have a "true" nucleus containing their DNA, whereas prokaryotic cells do not have a nucleus.
Both eukaryotes and prokaryotes contain large RNA/protein structures called ribosomes, which produce protein, but the ribosomes of prokaryotes are smaller than those of eukaryotes. Mitochondria and chloroplasts, two organelles found in many eukaryotic cells, contain ribosomes similar in size and makeup to those found in prokaryotes. This is one of many pieces of evidence that mitochondria and chloroplasts are descended from free-living bacteria. The endosymbiotic theory holds that early eukaryotic cells took in primitive prokaryotic cells by phagocytosis and adapted themselves to incorporate their structures, leading to the mitochondria and chloroplasts.
The genome in a prokaryote is held within a DNA/protein complex in the cytosol called the nucleoid, which lacks a nuclear envelope. The complex contains a single, cyclic, double-stranded molecule of stable chromosomal DNA, in contrast to the multiple linear, compact, highly organized chromosomes found in eukaryotic cells. In addition, many important genes of prokaryotes are stored in separate circular DNA structures called plasmids. Like Eukaryotes, prokaryotes may partially duplicate genetic material, and can have a haploid chromosomal composition that is partially replicated, a condition known as merodiploidy.
Prokaryotes lack mitochondria and chloroplasts. Instead, processes such as oxidative phosphorylation and photosynthesis take place across the prokaryotic cell membrane. However, prokaryotes do possess some internal structures, such as prokaryotic cytoskeletons. It has been suggested that the bacterial phylum Planctomycetota has a membrane around the nucleoid and contains other membrane-bound cellular structures. However, further investigation revealed that Planctomycetota cells are not compartmentalized or nucleated and, like other bacterial membrane systems, are interconnected.
Prokaryotic cells are usually much smaller than eukaryotic cells. Therefore, prokaryotes have a larger surface-area-to-volume ratio, giving them a higher metabolic rate, a higher growth rate, and as a consequence, a shorter generation time than eukaryotes.
There is increasing evidence that the roots of the eukaryotes are to be found in (or at least next to) the archaean asgard group, perhaps Heimdallarchaeota (an idea which is a modern version of the 1984 eocyte hypothesis, eocytes being an old synonym for Thermoproteota, a taxon to be found nearby the then-unknown Asgard group). For example, histones which usually package DNA in eukaryotic nuclei, have also been found in several archaean groups, giving evidence for homology. This idea might clarify the mysterious predecessor of eukaryotic cells (eucytes) which engulfed an alphaproteobacterium forming the first eucyte (LECA, last eukaryotic common ancestor) according to endosymbiotic theory. There might have been some additional support by viruses, called viral eukaryogenesis.
The non-bacterial group comprising archaea and eukaryota was called Neomura by Thomas Cavalier-Smith in 2002.
However, in a cladistic view, eukaryota are archaea in the same sense as birds are dinosaurs because they evolved from the maniraptora dinosaur group. In contrast, archaea without eukaryota appear to be a paraphyletic group, just like dinosaurs without birds. | 1 | Applied and Interdisciplinary Chemistry |
Classically, ILs consist of salts of unsymmetrical, flexible organic cations with symmetrical weakly coordinating anions. Both cationic and anionic components have been widely varied. | 0 | Theoretical and Fundamental Chemistry |
While FeAl is a B2 alloy, the observed yield strength anomaly in FeAl is due to another mechanism. If cross-slip were the mechanism, then the yield strength anomaly would be rate dependent, as expected for a thermally activated process. Instead, yield strength anomaly is state dependent, which is a property that is dependent on the state of the material. As a result, vacancy activated strengthening is the most widely-accepted mechanism. The vacancy formation energy is low for FeAl, allowing for an unusually high concentration of vacancies in FeAl at high temperatures (2.5% at 1000C for Fe-50Al). The vacancy formed in either aluminum-rich FeAl or through heating is an aluminum vacancy.
At low temperatures around 300K, the yield strength either decreases or does not change with temperature. At moderate temperatures (0.35-0.45 T), yield strength has been observed to increase with an increased vacancy concentration, providing further evidence for a vacancy driven strengthening mechanism. The increase in yield strength from increased vacancy concentration is believed to be the result of dislocations being pinned by vacancies on the slip plane, causing the dislocations to bow. Then, above the peak stress temperature, vacancies can migrate as vacancy migration is easier with elevated temperatures. At those temperatures, vacancies no longer hinder dislocation motion but rather aid climb. In the vacancy strengthening model, the increased strength below the peak stress temperature is approximated as proportional to the vacancy concentration to the one-half with the vacancy concentration estimated using Maxwell-Boltzmann statistics. Thus, the strength can be estimated as , with being the vacancy formation energy and T being the absolute temperature. Above the peak stress temperature, a diffusion-assisted deformation mechanism can be used to describe strength since vacancies are now mobile and assist dislocation motion. Above the peak, the yield strength is strain rate dependent and thus, the peak yield strength is rate dependent. As a result, the peak stress temperature increases with an increased strain rate. Note, this is different than the yield strength anomaly, which is the yield strength below the peak, being rate dependent. The peak yield strength is also dependent on percent aluminum in the FeAl alloy. As the percent aluminum increases, the peak yield strength occurs at lower temperatures.
The yield strength anomaly in FeAl alloys can be hidden if thermal vacancies are not minimized through a slow anneal at a relatively low temperature (~400 °C for ~5 days). Further, the yield strength anomaly is not present in systems that use a very low strain rate as the peak yield strength is strain rate dependent and thus, would occur at temperatures too low to observe the yield strength anomaly. Additionally, since the formation of vacancies requires time, the peak yield strength magnitude is dependent on how long the material is held at the peak stress temperature. Also, the peak yield strength has been found not to be dependent on crystal orientation.
Other mechanisms have been proposed including a cross slip mechanism similar to that for L1, dislocation decomposition into less mobile segments at jogs, dislocation pinning, climb-lock mechanism, and slip vector transition. The slip vector transition from MnAl is not dependent on strain rate and thus, may not follow the vacancy activated strengthening mechanism. Instead, there an order-strengthening mechanism has been proposed. | 1 | Applied and Interdisciplinary Chemistry |
The Fajans–Paneth–Hahn Law (also Fajans precipitation rule, Fajans-Peneth precipitation and adsorption rule, Hahn law of precipitation and adsorption, Fajans Law), in chemistry, is a rule governing how a small amount of one substance (tracer) is carried down to a precipitate of another substance present in much larger amount (carrier) by coprecipitation or adsorption.
The rule states that:
* the lower the solubility of the tracer cation with the anion of the carrier, the greater the amount of the tracer carried down by the carrier through co-precipitates or adsorption;
* when the tracer substance forms a mixed crystal, then the separation by co-precipitation only weakly depends on the conditions;
* the tracer will adsorb on the surface of the carrier precipitate if the precipitate acquired a surface charge opposite to that of the carrier ions in the solution; and then the separation strongly depends on the condition of precipitation.
The amount carried down is strongly affected by presence of complexing species regardless if it occurs by formation of mixed crystals or adsorption.
The law is named after chemists Kazimierz Fajans, Friedrich Paneth and Otto Hahn.
The Fajans-Paneth-Hahn law is essential for understanding the behaviour of minute amounts of substances (e.g., carrier-free radionuclides) in solutions. Note that the tracer is precipitated from the solution even when present at concentration far below its solubility limit. The law is also applied for separation of tracer substances by co-precipitation. | 0 | Theoretical and Fundamental Chemistry |
Thermal spraying techniques are another popular finishing option, and often have better high temperature properties than electroplated coatings. Thermal spraying, also known as a spray welding process, is an industrial coating process that consists of a heat source (flame or other) and a coating material that can be in a powder or wire form, which is melted then sprayed on the surface of the material being treated at a high velocity. The spray treating process is known by many different names such as HVOF (High Velocity Oxygen Fuel), plasma spray, flame spray, arc spray and metalizing. | 1 | Applied and Interdisciplinary Chemistry |
The Museum Weavers are housed in a barn, featuring more than 50 working looms for weaving. Members of this club meet weekly to learn and practice weaving, rug-making and rope-making. | 1 | Applied and Interdisciplinary Chemistry |
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