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Peter Rona, born as Peter Rosenfeld (* 13. May 1871 in Budapest; † February or March 1945) was a Hungarian German Jewish physician and physiologist. | 1 | Applied and Interdisciplinary Chemistry |
Electron diffraction in a TEM exploits controlled electron beams using electron optics. Different types of diffraction experiments, for instance Figure 9, provide information such as lattice constants, symmetries, and sometimes to solve an unknown crystal structure.
It is common to combine it with other methods, for instance images using selected diffraction beams, high-resolution images showing the atomic structure, chemical analysis through energy-dispersive x-ray spectroscopy, investigations of electronic structure and bonding through electron energy loss spectroscopy, and studies of the electrostatic potential through electron holography; this list is not exhaustive. Compared to x-ray crystallography, TEM analysis is significantly more localized and can be used to obtain information from tens of thousands of atoms to just a few or even single atoms. | 0 | Theoretical and Fundamental Chemistry |
The E. Bright Wilson Award in Spectroscopy is awarded annually by the American Chemical Society to recognize outstanding accomplishments in fundamental or applied spectroscopy in chemistry. It was first awarded in 1997 and was named in honor of the American Physical Chemist and Spectroscopy pioneer, E. Bright Wilson. | 0 | Theoretical and Fundamental Chemistry |
1 g/cm is equivalent to:
: = 1000 g/L (exactly)
: = 1000 kg/m (exactly)
: ≈ (approximately)
: ≈ (approximately)
1 kg/m = 0.001 g/cm(exactly)
1 lb/cu ft ≈ (approximately)
1 oz/US gal ≈ (approximately) | 0 | Theoretical and Fundamental Chemistry |
A repeat polymorphism of cytosines and adenines (CA) was found to be near BCYRN1 and was used as a reference for mapping the gene. Linkage mapping and radiation hybrid mapping localized the BCYRN1 gene to chromosome 2p16.
As a long non-coding cytoplasmic RNA, BC200 RNA is a part of the largest group of non-coding transcripts in the human genome, which is more prevalent than protein coding genes. The 5' region (left arm) of monomeric Alu short interspersed repetitive elements (SINEs) allows for BC200 RNA transposition and has been evolutionarily conserved in other primates. Of this group of SINEs, BC200 is one of few that are transcriptionally active. In humans, it is found in neuropil areas which are composed of predominantly unmyelinated dendrites, axons, and glial cells.
Similarly, the functional analog of BC200 RNA in rodents (BC1 RNA) is expressed largely in somatodendritic domains of the nervous system, making it an ideal model for experimentation. One large difference is in origin; BC200 emerged from retrotransposed Alu domain, while BC1 originated from retrotransposed tRNA. Although they evolved separately, both are not usually expressed in non-neural somatic cells, with the exception of tumors. | 1 | Applied and Interdisciplinary Chemistry |
Position-specific isotope analysis, also called site-specific isotope analysis, is a branch of isotope analysis aimed at determining the isotopic composition of a particular atom position in a molecule. Isotopes are elemental variants with different numbers of neutrons in their nuclei, thereby having different atomic masses. Isotopes are found in varying natural abundances depending on the element; their abundances in specific compounds can vary from random distributions (i.e., stochastic distribution) due to environmental conditions that act on the mass variations differently. These differences in abundances are called "fractionations," which are characterized via stable isotope analysis.
Isotope abundances can vary across an entire substrate (i.e., “bulk” isotope variation), specific compounds within a substrate (i.e., compound-specific isotope variation), or across positions within specific molecules (i.e., position specific isotope variation). Isotope abundances can be measured in a variety of ways (e.g., isotope ratio mass spectrometry, laser spectrometry, NMR, ESI-MS). Early analyses varied in technique, but were commonly limited by their ability to only measure average isotope compositions over molecules or samples. While this allows isotope analysis of the bulk substrate, it eliminates the ability to distinguish variation between different sites of the same element within the molecule. The field of position-specific isotope biogeochemistry studies these intramolecular variations, known as “position-specific isotope” and “site-specific isotope” enrichments. It focuses on position-specific isotope fractionations in many contexts, development of technologies to measure these fractionations and the application of position-specific isotope enrichments to questions surrounding biogeochemistry, microbiology, enzymology, medicinal chemistry, and earth history.
Position-specific isotope enrichments can retain critical information about synthesis and source of the atoms in the molecule. Indeed, bulk isotope analysis averages site-specific isotope effects across the molecule, and so while all those values have an influence on the bulk value, signatures of specific processes may be diluted or indistinguishable. While the theory of position-specific isotope analysis has existed for decades, new technologies exist now to allow these methods to be much more common. The potential applications of this approach are widespread, such as understanding metabolism in biomolecules, environmental pollutants in air, inorganic reaction mechanisms, etc. Clumped isotope analysis, a subset of position-specific isotope analysis, has already proven useful in characterizing sources of methane, paleoenvironment, paleoaltimetry, among many other applications. More specific case studies of position-specific isotope fractionation are detailed below. | 0 | Theoretical and Fundamental Chemistry |
An RNA sequence that is complementary to an endogenous mRNA transcript is sometimes called "antisense RNA". In other words, it is a non-coding strand complementary to the coding sequence of RNA; this is similar to negative-sense viral RNA. When mRNA forms a duplex with a complementary antisense RNA sequence, translation is blocked. This process is related to RNA interference. Cells can produce antisense RNA molecules naturally, called microRNAs, which interact with complementary mRNA molecules and inhibit their expression. The concept has also been exploited as a molecular biology technique, by artificially introducing a transgene coding for antisense RNA in order to block the expression of a gene of interest. Radioactively or fluorescently labelled antisense RNA can be used to show the level of transcription of genes in various cell types.
Some alternative antisense structural types have been experimentally applied as antisense therapy. In the United States, the Food and Drug Administration (FDA) has approved the phosphorothioate antisense oligonucleotides fomivirsen (Vitravene) and mipomersen (Kynamro) for human therapeutic use. | 1 | Applied and Interdisciplinary Chemistry |
As in most PCR reactions, two primers—one for each end—are used per sequence. To splice two DNA molecules, special primers are used at the ends that are to be joined. For each molecule, the primer at the end to be joined is constructed such that it has a 5' overhang complementary to the end of the other molecule. Following annealing when replication occurs, the DNA is extended by a new sequence that is complementary to the molecule it is to be joined to. Once both DNA molecules are extended in such a manner, they are mixed and a PCR is carried out with only the primers for the far ends. The overlapping complementary sequences introduced will serve as primers and the two sequences will be fused. This method has an advantage over other gene splicing techniques in not requiring restriction sites.
To get higher yields, some primers are used in excess as in asymmetric PCR. | 1 | Applied and Interdisciplinary Chemistry |
The Institute for Chemistry and Biology of the Marine Environment of the Carl von Ossietzky University of Oldenburg (, abbreviated ICBM)
is one of the marine science institutes at the German coast and the only university-based marine research institute in Lower Saxony, Germany.
The ICBM is located on the campus Wechloy in Oldenburg, with locations in Wilhelmshaven and on the island of Spiekeroog (in relation to the national park centre Wittbülten on the area of the Hermann Lietz School). The ICBM operates the Wadden Sea time series station Spiekeroog (WSS) and several research vessels. | 0 | Theoretical and Fundamental Chemistry |
Electrical discharge machining (EDM), also known as spark machining, spark eroding, die sinking, wire burning or wire erosion, is a metal
fabrication process whereby a desired shape is obtained by using electrical discharges (sparks). Material is removed from the work piece by a series of rapidly recurring current discharges between two electrodes, separated by a dielectric liquid and subject to an electric voltage. One of the electrodes is called the tool-electrode, or simply the or , while the other is called the workpiece-electrode, or . The process depends upon the tool and work piece not making physical contact. Extremely hard materials like carbides, ceramics, titanium alloys and heat treated tool steels that are very difficult to machine using conventional machining can be precisely machined by EDM.
When the voltage between the two electrodes is increased, the intensity of the electric field in the volume between the electrodes becomes greater, causing dielectric break down of the liquid, and produces an electric arc. As a result, material is removed from the electrodes. Once the current stops (or is stopped, depending on the type of generator), new liquid dielectric is conveyed into the inter-electrode volume, enabling the solid particles (debris) to be carried away and the insulating properties of the dielectric to be restored. Adding new liquid dielectric in the inter-electrode volume is commonly referred to as . After a current flow, the voltage between the electrodes is restored to what it was before the breakdown, so that a new liquid dielectric breakdown can occur to repeat the cycle. | 1 | Applied and Interdisciplinary Chemistry |
The discovery that certain toxic chemicals administered in combination can cure certain cancers ranks as one of the greatest in modern medicine. Childhood ALL (Acute Lymphoblastic Leukemia), testicular cancer, and Hodgkins disease, previously universally fatal, are now generally curable diseases. They have also proved effective in the adjuvant setting, in reducing the risk of recurrence after surgery for high-risk breast cancer, colon cancer, and lung cancer, among others.
The overall impact of chemotherapy on cancer survival can be difficult to estimate, since improved cancer screening, prevention (e.g. anti-smoking campaigns), and detection all influence statistics on cancer incidence and mortality. In the United States, overall cancer incidence rates were stable from 1995 through 1999, while cancer death rates decreased steadily from 1993 through 1999. Again, this likely reflects the combined impact of improved screening, prevention, and treatment. Nonetheless, cancer remains a major cause of illness and death, and conventional cytotoxic chemotherapy has proved unable to cure most cancers after they have metastasized. | 1 | Applied and Interdisciplinary Chemistry |
p90 Rsk-1 is located at 1p.
p90 Rsk-2 is located at Xp22.2 and contains 22 exons. Mutations in this gene have been associated with Coffin–Lowry syndrome, a disease characterised by severe psychomotor retardation and other developmental abnormalities.
p90 Rsk-3 is located at 6q27. | 1 | Applied and Interdisciplinary Chemistry |
It is also possible to switch the charge state of the NV center (i.e. between NV, NV and NV) by applying a gate voltage. | 0 | Theoretical and Fundamental Chemistry |
Plasmids are autonomously replicating circular extra-chromosomal DNA. They are the standard cloning vectors and the ones most commonly used. Most general plasmids may be used to clone DNA inserts of up to 15 kb in size. One of the earliest commonly used cloning vectors is the pBR322 plasmid. Other cloning vectors include the pUC series of plasmids, and a large number of different cloning plasmid vectors are available. Many plasmids have high copy numbers, for example, pUC19 has a copy number of 500-700 copies per cell, and high copy number is useful as it produces greater yield of recombinant plasmid for subsequent manipulation. However low-copy-number plasmids may be preferably used in certain circumstances, for example, when the protein from the cloned gene is toxic to the cells.
Some plasmids contain an M13 bacteriophage origin of replication and may be used to generate single-stranded DNA. These are called phagemids, and examples are the pBluescript series of cloning vectors. | 1 | Applied and Interdisciplinary Chemistry |
The NOE developed from the theoretical work of American physicist Albert Overhauser who in 1953 proposed that nuclear spin polarization could be enhanced by the microwave irradiation of the conduction electrons in certain metals. The electron-nuclear enhancement predicted by Overhauser was experimentally demonstrated in Li metal by T. R. Carver and C. P. Slichter also in 1953. A general theoretical basis and experimental observation of an Overhauser effect involving only nuclear spins in the HF molecule was published by Ionel Solomon in 1955. Another early experimental observation of the NOE was used by Kaiser in 1963 to show how the NOE may be used to determine the relative signs of scalar coupling constants, and to assign spectral lines in NMR spectra to transitions between energy levels. In this study, the resonance of one population of protons (H) in an organic molecule was enhanced when a second distinct population of protons in the same organic molecule was saturated by RF irradiation. The application of the NOE was used by Anet and Bourn in 1965 to confirm the assignments of the NMR resonances for β,β-dimethylacrylic acid and dimethyl formamide, thereby showing that conformation and configuration information about organic molecules in solution can be obtained. Bell and Saunders reported direct correlation between NOE enhancements and internuclear distances in 1970 while quantitative measurements of internuclear distances in molecules with three or more spins was reported by Schirmer et al.
Richard R. Ernst was awarded the 1991 Nobel Prize in Chemistry for developing Fourier transform and two-dimensional NMR spectroscopy, which was soon adapted to the measurement of the NOE, particularly in large biological molecules. In 2002, Kurt Wuthrich won the Nobel Prize in Chemistry for the development of nuclear magnetic resonance spectroscopy for determining the three-dimensional structure of biological macromolecules in solution, demonstrating how the 2D NOE method (NOESY) can be used to constrain the three-dimensional structures of large biological macromolecules. Professor Anil Kumar was the first to apply the two-dimensional Nuclear Overhauser Effect (2D-NOE now known as NOESY) experiment to a biomolecule, which opened the field for the determination of three-dimensional structures of biomolecules in solution by NMR spectroscopy. | 0 | Theoretical and Fundamental Chemistry |
* Increase in the melting point, boiling point, solubility, and viscosity of many compounds can be explained by the concept of hydrogen bonding.
* Negative azeotropy of mixtures of HF and water.
* The fact that ice is less dense than liquid water is due to a crystal structure stabilized by hydrogen bonds.
* Dramatically higher boiling points of , , and HF compared to the heavier analogues , , and HCl, where hydrogen-bonding is absent.
* Viscosity of anhydrous phosphoric acid and of glycerol.
* Dimer formation in carboxylic acids and hexamer formation in hydrogen fluoride, which occur even in the gas phase, resulting in gross deviations from the ideal gas law.
* Pentamer formation of water and alcohols in apolar solvents. | 0 | Theoretical and Fundamental Chemistry |
R-410A cannot be used in R-22 service equipment because of higher operating pressures (approximately 40 to 70% higher).
While R-410A has negligible fractionation potential, it cannot be ignored when charging. | 1 | Applied and Interdisciplinary Chemistry |
A water sampler is a device for field collection of one or more samples of water for testing. There are many different designs of water samplers. Selection or a particular sampler type depends on the type of analysis to be performed (e.g. ambient water quality or wastewater), the type of water source (e.g. a lake or pond, small stream or large river, coastal waters or deep ocean) and other factors such as ambient environmental conditions (e.g. collection of stormwater during a rain event vs. ambient water sampling during dry weather). Some sampler devices are designed for manual collection (a grab sample). Composite samplers can be configured to collect multiple samples over a specified time period or flow regime. | 0 | Theoretical and Fundamental Chemistry |
While iron oxide used to make nanoparticles is biodegradable, the toxicity of magnetic nanoparticles is still under investigation. Some research has found no signs of damage to cells, while others claim that small (< 2 nm) nanoparticles can diffuse across cell membranes and disrupt organelles.
In addition, very high concentrations of iron oxide can disrupt homeostasis and lead to iron overload, which can damage or alter DNA, affect cellular responses, and kill cells. Lysosymes can also digest the nanoparticles and release free iron which can react with hydrogen peroxide to form free radicals, leading to cytotoxic, mutagenic, and carcinogenic effects. | 1 | Applied and Interdisciplinary Chemistry |
MAPs have been divided into several different categories and sub-categories. There are "structural" MAPs which bind along the microtubules and "+TIP" MAPs which bind to the growing end of the microtubules. Structural MAPs have been divided into MAP1, MAP2, MAP4, and Tau families. +TIP MAPs are motor proteins such as kinesin, dyneins, and other MAPs. | 1 | Applied and Interdisciplinary Chemistry |
Allyl- and vinylsilanes react with a variety of electrophiles under conditions of nucleophilic catalysis or Lewis acid promotion (often stoichiometric). The primary advantage of using Lewis acids versus fluoride catalysis is site selectivity—fluoride activation tends to generate allyl anions, which can then react at either the α or γ position. Use of Lewis-acid-activated electrophiles leads to reaction at only the γ position of allylsilanes. | 0 | Theoretical and Fundamental Chemistry |
In the late 1980s and early 1990s, the U.S. Department of Energy (DOE) began conducting a joint program with the industry and State agencies to demonstrate clean coal technologies large enough for commercial use. The program, called the Clean Coal Technology & Clean Coal Power Initiative (CCPI), has had a number of successes that have reduced emissions and waste from coal-based electricity generation. By 2000, the EPA and DOE made many basic systems required. The National Energy Technology Laboratory has administered three rounds of CCPI funding and the following projects were selected during each round:
* Round 1 CCPI Projects
** Advanced Multi-Product Coal Utilization By-Product Processing Plant
** Demonstration of Integrated Optimization Software at the Baldwin Energy Complex
** Gilberton Coal-to-Clean Fuels and Power Co-Production Project
** Increasing Power Plant Efficiency: Lignite Fuel Enhancement
** TOXECON Retrofit for Mercury and Multi-Pollutant Control on Three 90-MW Coal-Fired Boilers
** Western Greenbrier Co-Production Demonstration Project
** Commercial Demonstration of the Airborne Process
** Integration of Advanced Emission Controls to Produce Next-Generation Circulating Fluid Bed Coal Generating Unit
* Round 2 CCPI Projects
** Airborne Process Commercial Scale Demonstration Program
** Demonstration of a Coal-Based Transport Gasifier
** Mercury Species and Multi-Pollutant Control Project
** Mesaba Energy Project
* Round 3 CCPI Projects
** American Electric Power Project
** Antelope Valley Station Post-Combustion Project
** Hydrogen Energy California Project
** NRG Energy Project
** Southern Company Carbon Capture Kemper Project (switching to natural gas)
** Summit Texas Clean Energy Project
These programs have helped to meet regulatory challenges by incorporating pollution control technologies into a portfolio of cost-effective regulatory compliance options for conventional and developmental coal-fired power plants. This portfolio has positioned the U.S. as a top exporter of technologies such as those used for coal and mercury, and more recently for carbon capture, consistent with a goal of deploying advanced coal-based power systems in commercial service. The DOE continues its programs and initiatives through regional sequestration partnerships, a carbon sequestration leadership forum and the Carbon Sequestration Core Program, a CCS research and development program.
According to a 1999 report by the assistant secretary for fossil energy at the U.S. Department of Energy, clean coal technology has paid measurable dividends. Technological innovation introduced through the CCT Program now provides consumers cost-effective, clean, coal-based energy. By 2015, the estimated emissions per coal plant went down by 22%.
Proposed CCS sites are subjected to extensive investigation and monitoring to avoid potential hazards, which could include leakage of sequestered to the atmosphere, induced geological instability, or contamination of water sources such as oceans and aquifers used for drinking water supplies. As of 2021 the only demonstrator for CCS on a coal plant that stores the gas underground is part of the Boundary Dam Power Station. | 1 | Applied and Interdisciplinary Chemistry |
The bond angles in the table below are ideal angles from the simple VSEPR theory (pronounced "Vesper Theory"), followed by the actual angle for the example given in the following column where this differs. For many cases, such as trigonal pyramidal and bent, the actual angle for the example differs from the ideal angle, and examples differ by different amounts. For example, the angle in HS (92°) differs from the tetrahedral angle by much more than the angle for HO (104.48°) does. | 0 | Theoretical and Fundamental Chemistry |
Pretreatment is important when working nanofiltration membranes due to their spiral-wound design. The material is engineered to allow one-way flow. The design does not allow for backpulsing with water or air agitation to scour its surface and remove accumulated solids. Since material cannot be removed from the membrane surface, it is susceptible to fouling (loss of production capacity). Therefore, pretreatment is a necessity for any RO or nanofiltration system. Pretreatment has four major components:
* Screening solids: Solids must be removed and the water treated to prevent membrane fouling by particle or biological growth, and reduce the risk of damage to high-pressure components.
* Cartridge filtration: String-wound polypropylene filters are typically used to remove particles of 1–5 µm diameter.
* Dosing: Oxidizing biocides, such as chlorine, are added to kill bacteria, followed by bisulfite dosing to deactivate the chlorine that can destroy a thin-film composite membrane. Biofouling inhibitors do not kill bacteria, while preventing them from growing slime on the membrane surface and plant walls.
* Prefiltration pH adjustment: If the pH, hardness and the alkalinity in the feedwater result in scaling while concentrated in the reject stream, acid is dosed to maintain carbonates in their soluble carbonic acid form.
:CO + HO = HCO + HO
:HCO + HO = HCO + HO
* Carbonic acid cannot combine with calcium to form calcium carbonate scale. Calcium carbonate scaling tendency is estimated using the Langelier saturation index. Adding too much sulfuric acid to control carbonate scales may result in calcium sulfate, barium sulfate, or strontium sulfate scale formation on the membrane.
* Prefiltration antiscalants: Scale inhibitors (also known as antiscalants) prevent formation of more scales than acid, which can only prevent formation of calcium carbonate and calcium phosphate scales. In addition to inhibiting carbonate and phosphate scales, antiscalants inhibit sulfate and fluoride scales and disperse colloids and metal oxides. Despite claims that antiscalants can inhibit silica formation, no concrete evidence proves that silica polymerization is inhibited by antiscalants. Antiscalants can control acid-soluble scales at a fraction of the dosage required to control the same scale using sulfuric acid.
* Some small-scale desalination units use beach wells. These are usually drilled on the seashore. These intake facilities are relatively simple to build and the seawater they collect is pretreated via slow filtration through subsurface sand/seabed formations. Raw seawater collected using beach wells is often of better quality in terms of solids, silt, oil, grease, organic contamination, and microorganisms, compared to open seawater intakes. Beach intakes may also yield source water of lower salinity. | 0 | Theoretical and Fundamental Chemistry |
In organic chemistry, nitro compounds are organic compounds that contain one or more nitro functional groups (). The nitro group is one of the most common explosophores (functional group that makes a compound explosive) used globally. The nitro group is also strongly electron-withdrawing. Because of this property, bonds alpha (adjacent) to the nitro group can be acidic. For similar reasons, the presence of nitro groups in aromatic compounds retards electrophilic aromatic substitution but facilitates nucleophilic aromatic substitution. Nitro groups are rarely found in nature. They are almost invariably produced by nitration reactions starting with nitric acid. | 0 | Theoretical and Fundamental Chemistry |
Location of M receptors is not well known.
Like the M and M muscarinic receptor, M receptors are coupled with G proteins of class G that upregulate phospholipase C and, therefore, inositol trisphosphate and intracellular calcium as a signaling pathway. | 1 | Applied and Interdisciplinary Chemistry |
Quoted values sunlight-to-biomass efficiency
The following is a breakdown of the energetics of the photosynthesis process from Photosynthesis by Hall and Rao:
Starting with the solar spectrum falling on a leaf,
* 47% lost due to photons outside the 400–700 nm active range (chlorophyll uses photons between 400 and 700 nm, extracting the energy of one 700 nm photon from each one)
* 30% of the in-band photons are lost due to incomplete absorption or photons hitting components other than chloroplasts
* 24% of the absorbed photon energy is lost due to degrading short wavelength photons to the 700 nm energy level
* 68% of the used energy is lost in conversion into d-glucose
* 35–45% of the glucose is consumed by the leaf in the processes of dark and photo respiration
Stated another way:
* 100% sunlight → non-bioavailable photons waste is 47%, leaving
* 53% (in the 400–700 nm range) → 30% of photons are lost due to incomplete absorption, leaving
* 37% (absorbed photon energy) → 24% is lost due to wavelength-mismatch degradation to 700 nm energy, leaving
* 28.2% (sunlight energy collected by chlorophyll) → 68% is lost in conversion of ATP and NADPH to d-glucose, leaving
* 9% (collected as sugar) → 35–40% of sugar is recycled/consumed by the leaf in dark and photo-respiration, leaving
* 5.4% net leaf efficiency.
Many plants lose much of the remaining energy on growing roots. Most crop plants store ~0.25% to 0.5% of the sunlight in the product (corn kernels, potato starch, etc.).
Photosynthesis increases linearly with light intensity at low intensity, but at higher intensity this is no longer the case (see Photosynthesis-irradiance curve). Above about 10,000 lux or ~100 watts/square meter the rate no longer increases. Thus, most plants can only use ~10% of full mid-day sunlight intensity. This dramatically reduces average achieved photosynthetic efficiency in fields compared to peak laboratory results. However, real plants (as opposed to laboratory test samples) have many redundant, randomly oriented leaves. This helps to keep the average illumination of each leaf well below the mid-day peak enabling the plant to achieve a result closer to the expected laboratory test results using limited illumination.
Only if the light intensity is above a plant specific value, called the compensation point the plant assimilates more carbon and releases more oxygen by photosynthesis than it consumes by cellular respiration for its own current energy demand.<br>
Photosynthesis measurement systems are not designed to directly measure the amount of light absorbed by the leaf. Nevertheless, the light response curves that the class produces do allow comparisons in photosynthetic efficiency between plants. | 0 | Theoretical and Fundamental Chemistry |
As illustrated in Retrosynthetic Scheme I, Taxol was derived from diol 7.2 by an ester bond formation, according to the Ojima-Holton method. This diol comes from carbonate 6.3 by the addition of phenyllithium. The oxetane ring in compound 6.3 was obtained via an S2 reaction involving a mesylate derived from acetal 4.9. Ring B was closed via a McMurry reaction involving dialdehyde 4.8 which ultimately was derived from aldehyde 4.2 and hydrazone 3.6 using a Shapiro coupling reaction.
Retrosynthetic Scheme II indicates that both the aldehyde and the hydrazone used in the Shapiro coupling reaction were synthesized using Diels-Alder reactions. | 0 | Theoretical and Fundamental Chemistry |
Atropisomers are stereoisomers arising because of hindered rotation about a single bond, where energy differences due to steric strain or other contributors create a barrier to rotation that is high enough to allow for isolation of individual conformers.
They occur naturally and are important in pharmaceutical design. When the substituents are achiral, these conformers are enantiomers (atropoenantiomers), showing axial chirality; otherwise they are diastereomers (atropodiastereomers). | 0 | Theoretical and Fundamental Chemistry |
Gaia scientists see the participation of living organisms in the carbon cycle as one of the complex processes that maintain conditions suitable for life. The only significant natural source of atmospheric carbon dioxide (CO) is volcanic activity, while the only significant removal is through the precipitation of carbonate rocks. Carbon precipitation, solution and fixation are influenced by the bacteria and plant roots in soils, where they improve gaseous circulation, or in coral reefs, where calcium carbonate is deposited as a solid on the sea floor. Calcium carbonate is used by living organisms to manufacture carbonaceous tests and shells. Once dead, the living organisms' shells fall. Some arrive at the bottom of shallow seas where the heat and pressure of burial, and/or the forces of plate tectonics, eventually convert them to deposits of chalk and limestone. Much of the falling dead shells, however, redissolve into the ocean below the carbon compensation depth.
One of these organisms is Emiliania huxleyi, an abundant coccolithophore algae which may have a role in the formation of clouds. CO excess is compensated by an increase of coccolithophorid life, increasing the amount of CO locked in the ocean floor. Coccolithophorids, if the CLAW Hypothesis turns out to be supported (see "Regulation of Global Surface Temperature" above), could help increase the cloud cover, hence control the surface temperature, help cool the whole planet and favor precipitation necessary for terrestrial plants. Lately the atmospheric CO concentration has increased and there is some evidence that concentrations of ocean algal blooms are also increasing.
Lichen and other organisms accelerate the weathering of rocks in the surface, while the decomposition of rocks also happens faster in the soil, thanks to the activity of roots, fungi, bacteria and subterranean animals. The flow of carbon dioxide from the atmosphere to the soil is therefore regulated with the help of living organisms. When CO levels rise in the atmosphere the temperature increases and plants grow. This growth brings higher consumption of CO by the plants, who process it into the soil, removing it from the atmosphere. | 0 | Theoretical and Fundamental Chemistry |
Some ligands can bond to a metal center through the same atom but with a different number of lone pairs. The bond order of the metal ligand bond can be in part distinguished through the metal ligand bond angle (M−X−R). This bond angle is often referred to as being linear or bent with further discussion concerning the degree to which the angle is bent. For example, an imido ligand in the ionic form has three lone pairs. One lone pair is used as a sigma X donor, the other two lone pairs are available as L-type pi donors. If both lone pairs are used in pi bonds then the M−N−R geometry is linear. However, if one or both these lone pairs is nonbonding then the M−N−R bond is bent and the extent of the bend speaks to how much pi bonding there may be. η-Nitric oxide can coordinate to a metal center in linear or bent manner. | 0 | Theoretical and Fundamental Chemistry |
Glycinamide is a organic compound with the molecular formula HNCHC(O)NH. It is the amide derivative of the amino acid glycine. It is a water-soluble, white solid. Amino acid amides, such as glycinamide are prepared by treating the amino acid ester with ammonia.
It is a ligand for transition metals.
The hydrochloride salt of glycinamide, glycinamide hydrochloride, is one of Good's buffers with a pH in the physiological range. Glycinamide hydrochloride has a pKa near the physiological pH (8.20 at 20°C), making it useful in cell culture work. Its ΔpKa/°C is -0.029 and it has a solubility in water at 0 °C of 6.4 M.
Glycinamide is a reagent used in the synthesis of glycineamide ribonucleotide (an intermediate in de novo purine biosynthesis). | 1 | Applied and Interdisciplinary Chemistry |
This is found principally with soft metals. Two soft ligands in mutual trans position will have a destabilizing effect on each other. The effect is also found with borderline metals in the presence of high trans effect ligands. For example the selenocyanate ion trans to the soft carbon dioxide in trans-Rh(PPh)(CO)(NCSe) bonds via the nitrogen, the harder of its two donors. The phenomenon may be explained in terms of a trans influence: | 0 | Theoretical and Fundamental Chemistry |
The post-mortem interval is the time that has elapsed since death. There are several different methods that can be used to estimate the post-mortem interval. | 1 | Applied and Interdisciplinary Chemistry |
On this track, students are introduced to the fundamental reaction mechanisms in the field of chemical and biochemical engineering. | 1 | Applied and Interdisciplinary Chemistry |
* Ionic counting assumes unequal sharing of electrons in the bond. The more electronegative atom in the bond gains electron lost from the less electronegative atom.
* This method begins by calculating the number of electrons of the element, assuming an oxidation state.
:E.g. for a Fe has 6 electrons
:S has 8 electrons
* Two is added for every halide or other anionic ligand which binds to the metal through a sigma bond.
* Two is added for every lone pair bonding to the metal (e.g. each phosphine ligand can bind with a lone pair). Similarly Lewis and Bronsted acids (protons) contribute nothing.
* For unsaturated ligands such as alkenes, one electron is added for each carbon atom binding to the metal. | 0 | Theoretical and Fundamental Chemistry |
In contrast to retrotransposons, retroposons never encode reverse transcriptase (RT) (but see below). Therefore, they are non-autonomous elements with regard to transposition activity (as opposed to transposons).
Non-long terminal repeat (LTR) retrotransposons such as the human LINE1 elements are sometimes falsely referred to as retroposons. However, this depends on the author. For example, Howard Temin published the following definition: Retroposons encode RT but are devoid of long terminal repeats (LTRs), for example long interspersed elements (LINEs). Retrotransposons also feature LTRs and retroviruses, in addition, are packaged as viral particles (virions). Retrosequences are non-autonomous elements devoid of RT. They are retroposed with the aid of the machinery of autonomous elements, such as LINEs; examples are short interspersed nuclear elements (SINEs) or mRNA-derived retro(pseudo)genes. | 1 | Applied and Interdisciplinary Chemistry |
The Grotthuss–Draper law (also called the principle of photochemical activation) states that only that light which is absorbed by a system can bring about a photochemical change. Materials such as dyes and phosphors must be able to absorb "light" at optical frequencies. This law provides a basis for fluorescence and phosphorescence. The law was first proposed in 1817 by Theodor Grotthuss and in 1842, independently, by John William Draper.
This is considered to be one of the two basic laws of photochemistry. The second law is the Stark–Einstein law, which says that primary chemical or physical reactions occur with each photon absorbed. | 0 | Theoretical and Fundamental Chemistry |
Azeotropes consisting of two constituents are called binary azeotropes such as diethyl ether (33%) / halothane (66%) a mixture once commonly used in anesthesia. Azeotropes consisting of three constituents are called ternary azeotropes, e.g. acetone / methanol / chloroform. Azeotropes of more than three constituents are also known. | 1 | Applied and Interdisciplinary Chemistry |
Many transition-metal compounds violate this rule due to the formation of complex ions, a scenario not part of the equilibria that are involved in simple precipitation of salts from ionic solution. For example, copper(I) chloride is insoluble in water, but it dissolves when chloride ions are added, such as when hydrochloric acid is added. This is due to the formation of soluble CuCl complex ions. | 0 | Theoretical and Fundamental Chemistry |
With the control of all growth conditions such as temperature, bond strength, diffusion, and saturation level, desired morphology could be formed by choosing the right parameters. Following is the demonstration how to obtain some interesting surface features: | 0 | Theoretical and Fundamental Chemistry |
Oil analysis (OA) is the laboratory analysis of a lubricants properties, suspended contaminants, and wear debris. OA' is performed during routine predictive maintenance to provide meaningful and accurate information on lubricant and machine condition. By tracking oil analysis sample results over the life of a particular machine, trends can be established which can help eliminate costly repairs. The study of wear in machinery is called tribology. Tribologists often perform or interpret oil analysis data.
OA can be divided into three categories:
# analysis of oil properties including those of the base oil and its additives,
# analysis of contaminants,
# analysis of wear debris from machinery, | 0 | Theoretical and Fundamental Chemistry |
Many enzymes and proteins play a role in degrading mRNA. For example, in Escherichia coli there are three enzymes: RNase II, PNPase, and RNase R. RNase R is a 3’-5’ exoribonuclease that is recruited to degrade a defective mRNA. RNase R has two structural domains, an N-terminal putative helix-turn-helix (HTH) and a C-terminal lysine(K-rich) domain. These two domains are unique to RNase R, and are attributed as being the determining factors for the selectivity and specificity of the protein. Evidence has been shown that the K-rich domain is involved in the degradation of non-stop mRNA. These domains are not present in other RNases. Both RNase II and RNase R are members of RNR family, and they share a noteworthy similarity in primary sequence and domain architecture. However, RNase R has the ability to efficiently degrade mRNA, while RNase II has less efficiency in the degrading process. Nevertheless, the specific mechanics of degrading mRNA via RNase R has remained a mystery. | 1 | Applied and Interdisciplinary Chemistry |
Alzheimers disease involves the progressive degeneration of the brain, severely impacting mental faculties. Since the Ca hypothesis of Alzheimers was proposed in 1994, several studies have shown that disruptions in Ca signaling are the primary cause of Alzheimers disease. Familial Alzheimers disease has been strongly linked to mutations in the presenilin 1 (PS1), presenilin 2 (PS2), and amyloid precursor protein (APP) genes. All of the mutated forms of these genes observed to date have been found to cause abnormal Ca signaling in the ER. Mutations in PS1 have been shown to increase IP-mediated Ca release from the ER in several animal models. Calcium channel blockers have been used to treat Alzheimer's disease with some success, and the use of lithium to decrease IP turnover has also been suggested as a possible method of treatment. | 1 | Applied and Interdisciplinary Chemistry |
Numerous compounds that bind selectively to neuroreceptors of interest in biological psychiatry have been radiolabeled with C-11 or F-18. Radioligands that bind to dopamine receptors (D, D, reuptake transporter), serotonin receptors (5HT, 5HT, reuptake transporter), opioid receptors (mu and kappa), cholinergic receptors (nicotinic and muscarinic) and other sites have been used successfully in studies with human subjects. Studies have been performed examining the state of these receptors in patients compared to healthy controls in schizophrenia, substance abuse, mood disorders and other psychiatric conditions. | 1 | Applied and Interdisciplinary Chemistry |
The Central Pollution Control Board of India released the Air (Prevention and Control of Pollution) Act in 1981, amended in 1987, to address concerns about air pollution in India. While the document does not differentiate between VOCs and other air pollutants, the CPCB monitors "oxides of nitrogen (NO), sulphur dioxide (SO), fine particulate matter (PM10) and suspended particulate matter (SPM)". | 0 | Theoretical and Fundamental Chemistry |
NASBA was developed by J Compton in 1991, who defined it as "a primer-dependent technology that can be used for the continuous amplification of nucleic acids in a single mixture at one temperature". Immediately after the invention of NASBA it was used for the rapid diagnosis and quantification of HIV-1 in patient sera. Although RNA can also be amplified by PCR using a reverse transcriptase (in order to synthesize a complementary DNA strand as a template), NASBA's main advantage is that it works under isothermal conditions – usually at a constant temperature of 41 °C or two different temperatures, depending on the primers and enzymes used. Even when two different temperatures are applied, it is still considered isothermal, because it does not cycle back and forth between those temperatures. NASBA can be used in medical diagnostics as an alternative to PCR that is quicker and more sensitive in some circumstances. | 1 | Applied and Interdisciplinary Chemistry |
The disulfide chain allows the mono-BOC-cystamine to be easily cleaved, allowing removal of the tagging residue when desired.
Mono-BOC-cystamine is used as a crosslinker for the synthesis of cleavable photo-cross-linking reagent.
Mono-BOC-cystamine is used as a crosslinker for the synthesis of a biodegradable cystamine spacer in PGA-cystamine-Gd-DO3A, which shows improved MRI contrast for breast carcinoma imaging in mice. | 1 | Applied and Interdisciplinary Chemistry |
Silica gel is a chemically inert, non-toxic, polar and dimensionally stable (. It is prepared by the reaction between sodium silicate and acetic acid, which is followed by a series of after-treatment processes such as aging, pickling, etc. These after-treatment methods results in various pore size distributions.
Silica is used for drying of process air (e.g. oxygen, natural gas) and adsorption of heavy (polar) hydrocarbons from natural gas. | 0 | Theoretical and Fundamental Chemistry |
Proposed by Gottfried Leibniz over the period 1676–1689, the theory was controversial as it seemed to oppose the theory of conservation of quantity of motion advocated by René Descartes. Descartes quantity of motion was different from momentum, but Newton defined the quantity of motion as the conjunction of the quantity of matter and velocity in Definition II of his Principia. In Definition III, he defined the force that resists a change in motion as the vis inertia of Descartes. Newton’s Third Law of Motion (for every action there is an equal and opposite reaction) is also equivalent to the principle of conservation of momentum. Leibniz accepted the principle of conservation of momentum, but rejected the Cartesian version of it. The difference between these ideas was whether the quantity of motion was simply related to a bodys resistance to a change in velocity (vis inertia) or whether a body's amount of force due to its motion (vis viva) was related to the square of its velocity.
The theory was eventually absorbed into the modern theory of energy, though the term still survives in the context of celestial mechanics through the vis viva equation. The English equivalent "living force" was also used, for example by George William Hill.
The term is due to German Gottfried Wilhelm Leibniz, who was the first to attempt a mathematical formulation from 1676 to 1689. Leibniz noticed that in many mechanical systems (of several masses, m each with velocity v) the quantity
was conserved. He called this quantity the vis viva or "living force" of the system. The principle represented an accurate statement of the conservation of kinetic energy in elastic collisions that was independent of the conservation of momentum.
However, many physicists at the time were unaware of this fact and, instead, were influenced by the prestige of Sir Isaac Newton in England and of René Descartes in France, both of whom advanced the conservation of momentum as a guiding principle. Thus the momentum:
was held by the rival camp to be the conserved vis viva. It was largely engineers such as John Smeaton, Peter Ewart, Karl Holtzmann, Gustave-Adolphe Hirn and Marc Seguin who objected that conservation of momentum alone was not adequate for practical calculation and who made use of Leibniz's principle. The principle was also championed by some chemists such as William Hyde Wollaston.
The French mathematician Émilie du Châtelet, who had a sound grasp of Newtonian mechanics, developed Leibnizs concept and, combining it with the observations of Willem s Gravesande, showed that vis viva was dependent on the square of the velocities.
Members of the academic establishment such as John Playfair were quick to point out that kinetic energy is clearly not conserved. This is obvious to a modern analysis based on the second law of thermodynamics, but in the 18th and 19th centuries, the fate of the lost energy was still unknown. Gradually it came to be suspected that the heat inevitably generated by motion was another form of vis viva. In 1783, Antoine Lavoisier and Pierre-Simon Laplace reviewed the two competing theories of vis viva and caloric theory. Count Rumfords 1798 observations of heat generation during the boring of cannons added more weight to the view that mechanical motion could be converted into heat. Vis viva began to be known as energy' after Thomas Young first used the term in 1807.
The recalibration of vis viva to include the coefficient of a half, namely:
was largely the result of the work of Gaspard-Gustave Coriolis and Jean-Victor Poncelet over the period 1819–1839, although the present-day definition can occasionally be found earlier (e.g., in Daniel Bernoulli's texts).
The former called it the quantité de travail (quantity of work) and the latter, travail mécanique (mechanical work) and both championed its use in engineering calculation. | 0 | Theoretical and Fundamental Chemistry |
One year following the Woodward–Hoffmann and Longuet-Higgins–Abrahmson publications, it was noted by Zimmerman that both transition states and stable molecules sometimes involved a Möbius array of basis orbitals. The Möbius–Hückel treatment provides an alternative to the Woodward–Hoffmann one. In contrast to the Woodward–Hoffmann approach the Möbius–Hückel treatment is not dependent on symmetry and only requires counting the number of plus-minus sign inversions in proceeding around the cyclic array of orbitals. Where one has zero or an even number of sign inversions there is a Hückel array. Where an odd-number of sign inversions is found a Möbius array is determined to be present. Thus the approach goes beyond the geometric consideration of Edgar Heilbronner. In any case, symmetry may be present or may not.
Edgar Heilbronner had described twisted annulenes which had Möbius topology, but in including the twist of these systems, he concluded that Möbius systems could never be lower in energy than the Hückel counterparts. In contrast, the Möbius–Hückel concept considers systems with an equal twist for Hückel and Möbius systems. | 0 | Theoretical and Fundamental Chemistry |
Volatiles are the group of chemical elements and chemical compounds that can be readily vaporized. In contrast with volatiles, elements and compounds that are not readily vaporized are known as refractory substances.
On planet Earth, the term volatiles often refers to the volatile components of magma. In astrogeology volatiles are investigated in the crust or atmosphere of a planet or moon. Volatiles include nitrogen, carbon dioxide, ammonia, hydrogen, methane, sulfur dioxide, water and others. | 0 | Theoretical and Fundamental Chemistry |
Gene function can be investigated by systematically "knocking out" genes one by one. This is done by either deletion or disruption of function (such as by insertional mutagenesis) and the resulting organisms are screened for phenotypes that provide clues to the function of the disrupted gene. Knock-outs have been produced for whole genomes, i.e. by deleting all genes in a genome. For essential genes, this is not possible, so other techniques are used, e.g. deleting a gene while expressing the gene from a plasmid, using an inducible promoter, so that the level of gene product can be changed at will (and thus a "functional" deletion achieved). | 1 | Applied and Interdisciplinary Chemistry |
Rhyolitic magma is felsic and the most abundant in silica, potassium, and sodium but the lowest in iron, magnesium, and calcium. The silica composition of rhyolitic magma ranges from 65-75 wt.%. It forms in the lowest temperature range, from about 1200 °F to 1470 °F. Rhyolitic magma has the highest viscosity and gas content. It produces the most explosive volcanic eruptions, including the catastrophic eruption of Mount Vesuvius. It forms minerals such as orthoclase feldspar, sodium-rich plagioclase feldspar, quartz, mica, and amphibole. | 0 | Theoretical and Fundamental Chemistry |
Cucurbit[n]urils have similar size of γ-CD, which also behave similarly (e.g., 1 cucurbit[n]uril can thread onto 2 PEG chains). | 0 | Theoretical and Fundamental Chemistry |
HPLC detectors fall into two main categories: universal or selective. Universal detectors typically measure a bulk property (e.g., refractive index) by measuring a difference of a physical property between the mobile phase and mobile phase with solute while selective detectors measure a solute property (e.g., UV-Vis absorbance) by simply responding to the physical or chemical property of the solute. HPLC most commonly uses a UV-Vis absorbance detector; however, a wide range of other chromatography detectors can be used. A universal detector that complements UV-Vis absorbance detection is the charged aerosol detector (CAD). A kind of commonly utilized detector includes refractive index detectors, which provide readings by measuring the changes in the refractive index of the eluant as it moves through the flow cell. In certain cases, it is possible to use multiple detectors, for example LCMS normally combines UV-Vis with a mass spectrometer.
When used with an electrochemical detector (ECD) the HPLC-ECD selectively detects neurotransmitters such as: norepinephrine, dopamine, serotonin, glutamate, GABA, acetylcholine and others in neurochemical analysis research applications. The HPLC-ECD detects neurotransmitters to the femtomolar range. Other methods to detect neurotransmitters include liquid chromatography-mass spectrometry, ELISA, or radioimmunoassays. | 0 | Theoretical and Fundamental Chemistry |
Diethylaminosulfur trifluoride (DAST) is the organosulfur compound with the formula EtNSF. This liquid is a fluorinating reagent used for the synthesis of organofluorine compounds. The compound is colourless; older samples assume an orange colour. | 0 | Theoretical and Fundamental Chemistry |
:The symmetry of a crystalline material has profound impacts on its emergent properties, including electronic band structure, electromagnetic behavior, and mechanical properties . Crystal symmetry is described and categorized by the crystal system, lattice, and space group of the material. Determination of these attributes is an important aspect of crystallography.
:Precession electron diffraction enables much more direct determination of space group symmetries over other forms of electron diffraction. Because of the increased number of reflections in both the zero order Laue zone and higher order Laue zones, the geometric relationship between Laue zones is more readily determined. This provides three-dimensional information about the crystal structure that can be used to determine its space group. Furthermore, because the PED technique is insensitive to slight misorientation from the zone axis, it provides the practical benefit of more robust data collection. | 0 | Theoretical and Fundamental Chemistry |
In 2016, John Zhang and a mixed team of scientists from Mexico and New York used the spindle transfer technique to help a Jordanian woman to give birth to a baby boy. The mother had Leigh disease and already had four miscarriages and two children who had died of the disease. Valery Zukin, director of the Nadiya clinic in Kyiv, Ukraine, reported in June 2018 that doctors there had used the pronuclear transfer method of MRT to help four women give birth (three boys and a girl) and three women to become pregnant (one from Sweden); the team had 14 failed attempts. In January 2019 it was reported that seven babies had been born using MRT. The doctors had first gotten approval from an ethical committee and a review board of the Ukrainian Association of Reproductive Medicine and the Ukrainian Postgraduate Medical Academy, under the auspices of the Ukrainian Ministry of Healthcare; there was no law in the Ukraine against MRT. One of the first children, a boy, was born to a 34-year-old woman in January 2017, and genetic test results were reported as normal. In August and October 2017 the British HFEA authorized MRT for two women who had a genetic mutation in their mitichondria that causes myoclonic epilepsy with ragged red fibers. In January 2019, Embryotools, Barcelona, Spain announced that a 32-year-old Greek woman had become pregnant using the spindle transfer technique. MRT was not legal in Spain so they had performed the trial in Greece where there was no law against MRT. They were helped by the Institute of Life in Athens, Greece and had obtained approval from the Greek National Authority of Assisted Reproduction. The pregnant Greek woman had already had four failed IVF cycles and surgery twice for endometriosis.
In August 2017, in a letter to two clinics, including Zhang's, the FDA warned that the technique should not be marketed in the U.S. | 1 | Applied and Interdisciplinary Chemistry |
The Obukhov length is used to describe the effects of buoyancy on turbulent flows, particularly in the lower tenth of the atmospheric boundary layer. It was first defined by Alexander Obukhov in 1946. It is also known as the Monin–Obukhov length because of its important role in the similarity theory developed by Monin and Obukhov. A simple definition of the Monin-Obukhov length is that height at which turbulence is generated more by buoyancy than by wind shear.
The Obukhov length is defined by
where is the frictional velocity, is the mean virtual potential temperature, is the surface virtual potential temperature flux, k is the von Kármán constant. If not known, the virtual potential temperature flux can be apprioximated with:
where is potential temperature, and is mixing ratio.
By this definition, is usually negative in the daytime since is typically positive during the daytime over land, positive at night when is typically negative, and becomes infinite at dawn and dusk when passes through zero.
A physical interpretation of is given by the Monin–Obukhov similarity theory. During the day is the height at which the buoyant production of turbulence kinetic energy (TKE) is equal to that produced by the shearing action of the wind (shear production of TKE). | 1 | Applied and Interdisciplinary Chemistry |
Dorothy Martin was born on 18 September 1919 in Bacon Township, Vernon County, Missouri to Laudell M (née Flynn) (1892–1978) and Robert W. Martin.
She received her AB degree from Southwest Missouri State University where her father was head of the science department. There, she was the first graduate to achieve a perfect score (4.0 GPA). From there, she attended the University of Chicago for one year, before transferring to University of Illinois to become an assistant to a professor. She earned her PhD in physical chemistry in 1945 from the University of Illinois, with thesis work regarding radon. She married Sidney Simon, a fellow graduate student from the University of Chicago, in 1946 and took his surname. | 0 | Theoretical and Fundamental Chemistry |
A Bjerrum plot (named after Niels Bjerrum), sometimes also known as a Sillén diagram (after Lars Gunnar Sillén), or a Hägg diagram (after Gunnar Hägg) is a graph of the concentrations of the different species of a polyprotic acid in a solution, as a function of pH, when the solution is at equilibrium. Due to the many orders of magnitude spanned by the concentrations, they are commonly plotted on a logarithmic scale. Sometimes the ratios of the concentrations are plotted rather than the actual concentrations. Occasionally H and OH are also plotted.
Most often, the carbonate system is plotted, where the polyprotic acid is carbonic acid (a diprotic acid), and the different species are dissolved carbon dioxide, carbonic acid, bicarbonate, and carbonate. In acidic conditions, the dominant form is ; in basic (alkaline) conditions, the dominant form is ; and in between, the dominant form is . At every pH, the concentration of carbonic acid is assumed to be negligible compared to the concentration of dissolved , and so is often omitted from Bjerrum plots. These plots are very helpful in solution chemistry and natural water chemistry. In the example given here, it illustrates the response of seawater pH and carbonate speciation due to the input of man-made emission by the fossil fuel combustion.
The Bjerrum plots for other polyprotic acids, including silicic, boric, sulfuric and phosphoric acids, are other commonly used examples. | 0 | Theoretical and Fundamental Chemistry |
The barcoded DNA fragments are amplified using PCR to create a library of DNA fragments with identical barcodes. All the fragments derived from a given DNA molecule are tagged with the same barcode. This step increases the quantity of DNA for sequencing and reduces the chances of losing unique DNA fragments during sequencing. Droplets (or GEM) are later collected in a tube, and the emulsion is broken, releasing the amplified, barcoded DNA sequences.
Standard Illumina next-generation sequencing technology can be used to sequence libraries. During sequencing, the barcodes are read along with the DNA sequences, allowing researchers and scientists to group together DNA fragments that originate from the same DNA molecule. Even though each DNA fragment is typically not fully sequenced, the information from many overlapping fragments in the same genomic region can be combined to reconstruct the long stretches of the genome. Therefore, a genome can be easily assembled from scratch without any prior reference. | 1 | Applied and Interdisciplinary Chemistry |
The lateral expansion joint absorbs transverse and lateral movements. It consists of
* One or two metal bellows with an intermediate pipe
* Connectors on both sides and a hinged anchoring of these connectors for lateral movement in a single plane or for lateral movement in all planes
Normally, the anchoring consists of round anchors on spherical bearings. If high axial compressive forces occur, flat tie rods with pin or universal joints are used. The magnitude of the lateral movement increases with the bending angle of both metal bellows and with the length of the intermediate pipe. | 1 | Applied and Interdisciplinary Chemistry |
Dynamic light scattering provides insight into the dynamic properties of soft materials by measuring single scattering events, meaning that each detected photon has been scattered by the sample exactly once. In principle, the DLS measurements can be performed with the detector positioned at any angle. The choice of the best angle depends on the sample properties, such as turbidity and particle size. Back scattering detection (e.g., 173° or 175°) is particularly interesting for turbid and highly concentrated samples, which contain large particles. Side scattering detection (90°) is recommended for weakly scattering samples, including small particles and transparent samples. Finally, forward scattering detection (e.g., 13° or 15°) is suitable for detection of samples containing small particles with few large particles. Some DLS instruments in the market also allow automatic angle selection based on a continuous transmittance measurement.
At the lower end of the turbidity range, the Cavity Amplified Scattering Spectroscopy method makes use of an integrating cavity to elongate photon paths through quasi non-scattering samples. As opposed to conventional DLS instruments, this method is angle independent as it probes samples isotropically from all directions.
Even though the DLS measurement using a single-angle detection has been the most diffuse technique, the application to many systems of scientific and industrial relevance has been limited due to often-encountered multiple scattering, wherein photons are scattered multiple times by the sample before being detected. Accurate interpretation becomes exceedingly difficult for systems with non-negligible contributions from multiple scattering. Especially for larger particles and those with high refractive index contrast, this limits the technique to very low particle concentrations, and a large variety of systems are, therefore, excluded from investigations with dynamic light scattering. However, as shown by Schaetzel, it is possible to suppress multiple scattering in dynamic light scattering experiments via a cross-correlation approach. The general idea is to isolate singly scattered light and suppress undesired contributions from multiple scattering in a dynamic light scattering experiment. Different implementations of cross-correlation light scattering have been developed and applied. Currently, the most widely used scheme is the so-called 3D-dynamic light scattering method. The same method can also be used to correct static light scattering data for multiple scattering contributions. Alternatively, in the limit of strong multiple scattering, a variant of dynamic light scattering called diffusing-wave spectroscopy can be applied. | 0 | Theoretical and Fundamental Chemistry |
The agricultural industry is constantly striving to produce plant propagules or seedlings that are free of pathogens in order to prevent economic losses and safeguard health. Systems have been developed that allow detection of small amounts of the DNA of Phytophthora ramorum, an oomycete that kills oaks and other species, mixed in with the DNA of the host plant. Discrimination between the DNA of the pathogen and the plant is based on the amplification of ITS sequences, spacers located in ribosomal RNA gene's coding area, which are characteristic for each taxon. Field-based versions of this technique have also been developed for identifying the same pathogen. | 1 | Applied and Interdisciplinary Chemistry |
The proof of the scallop theorem can be represented in a mathematically elegant way. To do this, we must first understand the mathematical consequences of the linearity of Stokes equations. To summarize, the linearity of Stokes equations allows us to use the reciprocal theorem to relate the swimming velocity of the swimmer to the velocity field of the fluid around its surface (known as the swimming gait), which changes according to the periodic motion it exhibits. This relation allows us to conclude that locomotion is independent of swimming rate. Subsequently, this leads to the discovery that reversal of periodic motion is identical to the forward motion due to symmetry, allowing us to conclude that there can be no net displacement. | 1 | Applied and Interdisciplinary Chemistry |
The deformation gradient for a simple shear deformation has the form
where are reference orthonormal basis vectors in the plane of deformation and the shear deformation is given by
In matrix form, the deformation gradient and the left Cauchy–Green deformation tensor may then be expressed as
Therefore,
and the Cauchy stress is given by | 0 | Theoretical and Fundamental Chemistry |
For mutually soluble compounds, Raoult's law states that the partial pressure of a compound is equal to its vapor pressure times its mole fraction. This means that mutually soluble contaminants will volatilize slower than if there was only one compound present. | 1 | Applied and Interdisciplinary Chemistry |
The reactions best for temperature (geothermometers) are ones that have a large enthalpy of reaction, which means they release or consume a lot of heat. Higher temperatures allow the reaction to consume that heat while lower temperatures cause the reaction to release heat. Similarly to geobarometers, the proportion of minerals that are formed by releasing heat versus consuming heat can be used to calculate the temperature, as long as the reaction is calibrated. | 0 | Theoretical and Fundamental Chemistry |
m6A-LAIC-seq (m6A-level and isoform-characterization sequencing) is a high-throughput approach to quantify methylation status on a whole-transcriptome scale. Full-length RNA samples are used in this method. RNAs are first subjected to immunoprecipitation with an anti-m6A antibody. Excess antibody is added to the mixture to ensure all m6A-containing RNAs are pulled down. The mixture is separated into eluate (m6A+ RNAs) and supernatant (m6A- RNAs) pools. External RNA Controls Consortium (ERCC) spike ins are added to the eluate and supernatant, as well as an independent control arm consisting of just ERCC spike in. After antibody cleavage in the eluate pool, each of the three mixtures are sequenced on a next generation sequencing platform. The m6A levels per site or gene could be quantified by the ERCC-normalized RNA abundances in different pools. Since full-length RNA is used, it is possible to directly compare alternatively spliced isoforms between the m6A+ and m6A- fractions as well as comparing isoform abundance within the m6A+ portion.
Despite the advances in m6A-sequencing, several challenges still remain: (1) A method has yet to be developed that characterizes the stoichiometry between different sites in the same transcript; (2) Analysis results are heavily dependent on the bioinformatics algorithm used to call the peaks; (3) Current methods all use m6A-specific antibodies to tag m6A sites, but it has been reported that the antibodies contain intrinsic bias for RNA sequences. | 1 | Applied and Interdisciplinary Chemistry |
The 1958–1959 "Quartz Fibre Dosimeter Chargers, No. 1 and 2" were retained until the early 1990s, as they incorporate a simple, handle-driven generator and do not require batteries at all. A later British civil defence dosimeter charger was developed by R. A. Stephen Ltd and manufactured from 1967 to 1988, and uses a single 1.5 volt cell. It is similar to American dosimeter chargers. | 0 | Theoretical and Fundamental Chemistry |
Cholesterol 7 alpha-hydroxylase is the rate-limiting enzyme in the synthesis of bile acid from cholesterol via the classic pathway, catalyzing the formation of 7α-hydroxycholesterol. The unique detergent properties of bile acids are essential for the digestion and intestinal absorption of hydrophobic nutrients.
Bile acids have powerful toxic properties like membrane disruption and there are a wide range of mechanisms to restrict their accumulation in tissues and blood. The discovery of farnesoid X receptor (FXR) which is located in the liver, has opened new insights. Bile acid activation of FXR represses the expression of CYP7A1 via, raising the expression of small heterodimer partner (SHP, NR0B2), a non-DNA binding protein.
The increased abundance of SHP causes it to associate with liver receptor homolog (LRH)-1, an obligate factor required for the transcription of CYP7A1. Furthermore, there is an "FXR/SHP-independent" mechanism that also represses CYP7A1 expression. This "FXR/SHP-independent" pathway involves the interaction of bile acids with liver macrophages, which finally induces the expression and secretion of cytokines. These inflammatory cytokines, which include tumor necrosis factor alpha and interleukin-1beta, act upon the liver parenchymal cells causing a rapid repression of the CYP7A1 gene. | 1 | Applied and Interdisciplinary Chemistry |
This timeline of events related to per- and polyfluoroalkyl substances (PFASs) includes events related to the discovery, development, manufacture, marketing, uses, concerns, litigation, regulation, and legislation, involving the human-made PFASs. The timeline focuses on some perfluorinated compounds, particularly perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS) and on the companies that manufactured and marketed them, mainly DuPont and 3M. An example of PFAS is the fluorinated polymer polytetrafluoroethylene (PTFE), which has been produced and marketed by DuPont under its trademark Teflon. GenX chemicals and perfluorobutanesulfonic acid (PFBS) are organofluorine chemicals used as a replacement for PFOA and PFOS.
PFAS compounds and their derivatives are widely used in many products from water resistant textiles to fire-fighting foam. PFAS are commonly found in every American household in products as diverse as non-stick cookware, stain resistant furniture and carpets, wrinkle free and water repellant clothing, cosmetics, lubricants, paint, pizza boxes, popcorn bags and many other everyday products. | 1 | Applied and Interdisciplinary Chemistry |
If suitably designed, general ventilation can also be used as a control of airborne dust. General ventilation can often help reduce skin and clothing contamination, and dust deposition on surfaces. | 1 | Applied and Interdisciplinary Chemistry |
Phenethylamine (PEA) is an organic compound, natural monoamine alkaloid, and trace amine, which acts as a central nervous system stimulant in humans. In the brain, phenethylamine regulates monoamine neurotransmission by binding to trace amine-associated receptor 1 (TAAR1) and inhibiting vesicular monoamine transporter 2 (VMAT2) in monoamine neurons. To a lesser extent, it also acts as a neurotransmitter in the human central nervous system. In mammals, phenethylamine is produced from the amino acid L-phenylalanine by the enzyme aromatic L-amino acid decarboxylase via enzymatic decarboxylation. In addition to its presence in mammals, phenethylamine is found in many other organisms and foods, such as chocolate, especially after microbial fermentation.
Phenethylamine is sold as a dietary supplement for purported mood and weight loss-related therapeutic benefits; however, in orally ingested phenethylamine, a significant amount is metabolized in the small intestine by monoamine oxidase B (MAO-B) and then aldehyde dehydrogenase (ALDH), which converts it to phenylacetic acid. This means that for significant concentrations to reach the brain, the dosage must be higher than for other methods of administration. Some authors postulated its role in people's falling-in-love without substantiating it with any direct evidence.
Phenethylamines, or more properly, substituted phenethylamines, are the group of phenethylamine derivatives that contain phenethylamine as a "backbone"; in other words, this chemical class includes derivative compounds that are formed by replacing one or more hydrogen atoms in the phenethylamine core structure with substituents. The class of substituted phenethylamines includes all substituted amphetamines, and substituted methylenedioxyphenethylamines (MDxx), and contains many drugs which act as empathogens, stimulants, psychedelics, anorectics, bronchodilators, decongestants, and/or antidepressants, among others. | 1 | Applied and Interdisciplinary Chemistry |
Some molecular tweezers bind aromatic guests. These molecular tweezers consist of a pair of anthracene arms held at a distance that allows aromatic guests to gain π–π interactions from both (see Figure). Other molecular tweezers feature a pair of tethered porphyrins.
Yet another type of molecular tweezers bind fullerenes. Such "buckycatchers" are composed of two corannulene pincers that complement the surface of the convex fullerene guest (Figure 2). An association constant (K) of 8,600 M was calculated using H NMR spectroscopy.
Stoermer and co-workers described clefts capable of capturing cyclohexane or chloroform molecules. Intriguingly, pi interactions played key roles in guest capture as well as cleft formation rate.
Water-soluble phosphate-substituted molecular tweezers made of alternating phenyl and norbornenyl substituents bind to positively charged aliphatic side chains of basic amino acids, such as lysine and arginine (Figure 3). Similar compounds called "molecular clips", whose side walls are flat rather than convex, prefer to enclose flat pyridinium rings (for example the nicotinamide ring of NAD(P)+) between their plane naphthalene sidewalls (Figure 4). These mutually exclusive binding modes make these compounds valuable tools for probing critical biological interactions of basic amino acid side chains in peptides and proteins as well as of NAD(P) and similar cofactors. For example, both types of compounds inhibit the oxidation reactions of ethanol by alcohol dehydrogenase or of glucose-6-phosphate by glucose-6-phosphate dehydrogenase, respectively.
The molecular tweezers, but not the clips, efficiently inhibit the formation of toxic oligomers and aggregates by amyloidogenic proteins associated with different diseases. Examples include the proteins involved in Alzheimers disease – amyloid β-protein (Aβ) and tau; α-synuclein, which is thought to cause Parkinsons disease and other synucleinopathies and is involved in spinal-cord injury; mutant huntingtin, which causes Huntington's disease; islet amyloid polypeptide (amylin), which kills pancreatic β-cells in type-2 diabetes; transthyretin (TTR), which causes familial amyloid polyneuropathy, familial amyloid cardiomyopathy, and senile systemic amyloidosis; aggregation-prone mutants of the tumor-suppressor protein p53; and semen proteins whose aggregation enhances HIV infection. Importantly, the molecular tweezers have been found to be effective and safe not only in the test tube but also in animal models of different diseases, suggesting that they may be developed as drugs against diseases caused by abnormal protein aggregation, all of which currently have no cure. They were also shown to destroy the membranes of enveloped viruses, such as HIV, herpes, and hepatitis C, which makes them good candidates for development of microbicides.
The above examples show the potential reactivity and specificity of these molecules. The binding cavity between the side arms of the tweezer can evolve to bind to an appropriate guest with high specificity, depending on the configuration of the tweezer. That makes this overall class of macromolecule truly synthetic molecular receptors with important application to biology and medicine. | 0 | Theoretical and Fundamental Chemistry |
*Acids and bases
**Brønsted–Lowry acid–base theory
**Acid dissociation constants
**Lewis acids and bases
* Chemoselectivity
* Molecular structure
** Aromaticity
** Chemical bonding
*** Covalent bonding
*** Lewis model
*** Molecule shapes
*** Bond angles
*** Resonance structures
** Conjugated systems
**Functional groups
** Stereochemistry
*** Conformational isomerism
*** Diastereomer
*** Stereoisomerism
*** Chirality
*** Optical activity
*** Enantiomers
* Regioselectivity
* Stereoselectivity
* Spectroscopy
** Infrared spectroscopy
** Mass spectrometry
** NMR spectroscopy
**Ultraviolet–visible spectroscopy
* Organometallic chemistry | 0 | Theoretical and Fundamental Chemistry |
Over the decades huge number of precipitation reactions have been used to study the phenomenon, and it seems quite general. Chromates, metal hydroxides, carbonates, and sulfides, formed with lead, copper, silver, mercury and cobalt salts are sometimes favored by investigators, perhaps because of the pretty, colored precipitates formed.
The gels used are usually gelatin, agar or silicic acid gel.
The concentration ranges over which the rings form in a given gel for a precipitating system can usually be found for any system by a little systematic empirical experimentation in a few hours. Often the concentration of the component in the agar gel should be substantially less concentrated (perhaps an order of magnitude or more) than the one placed on top of the gel.
The first feature usually noted is that the bands which form farther away from the liquid-gel interface are generally farther apart. Some investigators measure this distance and report in some systems, at least, a systematic formula for the distance that they form at. The most frequent observation is that the distance apart that the rings form is proportional to the distance from the liquid-gel interface. This is by no means universal, however, and sometimes they form at essentially random, irreproducible distances.
Another feature often noted is that the bands themselves do not move with time, but rather form in place and stay there.
For very many systems the precipitate that forms is not the fine coagulant or flocs seen on mixing the two solutions in the absence of the gel, but rather coarse, crystalline dispersions. Sometimes the crystals are well separated from one another, and only a few form in each band.
The precipitate that forms a band is not always a binary insoluble compound, but may be even a pure metal. Water glass of density 1.06 made acidic by sufficient acetic acid to make it gel, with 0.05 N copper sulfate in it, covered by a 1 percent solution of hydroxylamine hydrochloride produces large tetrahedrons of metallic copper in the bands.
It is not possible to make any general statement of the effect of the composition of the gel. A system that forms nicely for one set of components, might fail altogether and require a different set of conditions if the gel is switched, say, from agar to gelatin. The essential feature of the gel required is that thermal convection in the tube be prevented altogether.
Most systems will form rings in the absence of the gelling system if the experiment is carried out in a capillary, where convection does not disturb their formation. In fact, the system does not have to even be liquid. A tube plugged with cotton with a little ammonium hydroxide at one end, and a solution of hydrochloric acid at the other will show rings of deposited ammonium chloride where the two gases meet, if the conditions are chosen correctly. Ring formation has also been observed in solid glasses containing a reducible species. For example, bands of silver have been generated by immersing silicate glass in molten AgNO for extended periods of time (Pask and Parmelee, 1943). | 0 | Theoretical and Fundamental Chemistry |
A Scuderi cycle is a thermodynamic cycle that is constructed out of the following series of thermodynamic processes:
* A-B and C-D (TOP and BOTTOM of the loop): a pair of quasi-parallel adiabatic processes
* D-A (LEFT side of the loop): a positively sloped, increasing pressure, increasing volume process
* B-C (RIGHT side of the loop): an isochoric process
The adiabatic processes are impermeable to heat: heat flows rapidly into the loop through the left expanding process, resulting in increasing pressure while volume is increasing; some of it flows back out through the right depressurizing process; the remaining heat does the work. | 0 | Theoretical and Fundamental Chemistry |
In the presence of two phases ( and ), the surface (surface phase) is located in between the phase and phase . Experimentally, it is difficult to determine the exact structure of an inhomogeneous surface phase that is in contact with a bulk liquid phase containing more than one solute. Inhomogeneity of the surface phase is a result of variation of mole ratios. A model proposed by Josiah Willard Gibbs proposed that the surface phase as an idealized model that had zero thickness. In reality, although the bulk regions of and phases are constant, the concentrations of components in the interfacial region will gradually vary from the bulk concentration of to the bulk concentration of over the distance x. This is in contrast to the idealized Gibbs model where the distance x takes on the value of zero. The diagram to the right illustrates the differences between the real and idealized models. | 0 | Theoretical and Fundamental Chemistry |
The CIPW Norm was developed in the early 1900s and named after its creators, the petrologists Charles Cross, Joseph Iddings, Louis Pirsson, and the geochemist Henry Washington. The CIPW normative mineralogy calculation is based on the typical minerals that may be precipitated from an anhydrous melt at low pressure, and simplifies the typical igneous geochemistry seen in nature with the following four constraints:
* The magma crystallizes under anhydrous conditions so that no hydrous minerals (hornblende, biotite) are formed.
* The ferromagnesian minerals are assumed to be free of AlO.
* The Fe/Mg ratio for all ferromagnesian minerals is assumed to be the same.
* Several minerals are assumed to be incompatible, thus nepheline and/or olivine never appear with quartz in the norm.
This is an artificial set of constraints, and therefore the results of the CIPW norm do not reflect the true course of igneous differentiation in nature.
The primary benefit of calculating a CIPW norm is determining what the ideal mineralogy of an aphanitic or porphyritic igneous rock is. Secondly, the degree of silica saturation of the melt that formed the rock can be assessed in the absence of diagnostic feldspathoid species.
The silica saturation of a rock varies not only with silica content but the proportion of the various alkalis and metal species within the melt. The silica saturation eutectic plane is thus different for various families of rocks and cannot be easily estimated, hence the requirement to calculate whether the rock is silica saturated or not.
This is achieved by assigning cations of the major elements within the rock to silica anions in modal proportion, to form solid solution minerals in the idealised mineral assemblage starting with phosphorus for apatite, chlorine and sodium for halite, sulfur and FeO into pyrite, FeO and CrO is allocated for chromite, FeO and equal molar amount of TiO for ilmenite, CaO and CO for calcite, to complete the most common non-silicate minerals.
From the remaining chemical constituents, AlO and KO are allocated with silica for orthoclase; sodium, aluminium and potassium for albite, and so on until either there is no silica left (in which case feldspathoids are calculated) or excess, in which case the rock contains normative quartz. | 0 | Theoretical and Fundamental Chemistry |
Electrolysis of water in a supercritical state, reduces the overpotentials found in other electrolysers, thereby improving the electrical efficiency of the production of oxygen and hydrogen.
Increased temperature reduces thermodynamic barriers and increases kinetics. No bubbles of oxygen or hydrogen are formed on the electrodes, therefore no insulating layer is formed between catalyst and water, reducing the ohmic losses. The gas-like properties provide rapid mass transfer. | 0 | Theoretical and Fundamental Chemistry |
Biotin carboxyl carrier protein (BCCP) refers to proteins containing a biotin attachment domain that carry biotin and carboxybiotin throughout the ATP-dependent carboxylation by biotin-dependent carboxylases. The biotin carboxyl carrier protein is an Acetyl CoA subunit that allows for Acetyl CoA to be catalyzed and converted to malonyl-CoA. More specifically, BCCP catalyzes the carboxylation of the carrier protein to form an intermediate. Then the carboxyl group is transferred by the transcacrboxylase to form the malonyl-CoA. This conversion is an essential step in the biosynthesis of fatty acids. In the case of E. coli Acetyl-CoA carboxylase, the BCCP is a separate protein known as accB (). On the other hand, in Haloferax mediterranei, propionyl-CoA carboxylase, the BCCP pccA () is fused with biotin carboxylase.
The biosynthesis of fatty acids in plants, such as triacylglycerol, is vital to the plant's overall health because it allows for accumulation of seed oil. The biosynthesis that is catalyzed by BCCP usually takes place in the chloroplast of plant cells. The biosynthesis performed by the BCCP protein allows for the transfer of CO within active sites of the cell.
The biotin carboxyl carrier protein carries approximately 1 mol of biotin per 22,000 g of protein.
There is not much research on BCCPs at the moment. However, a recent studyon plant genomics found that Brassica BCCPs might play a key role in abiotic and biotic stress responses. Meaning that these proteins may be relaying messages to the rest of the plant body after it has been exposed to extreme conditions that disrupt the plant's homeostasis. | 1 | Applied and Interdisciplinary Chemistry |
When a heat ray arrives at a body they may interact in three different ways:
# The body may absorb the heat
# The body may reflect the heat
# The heat may transmit through the body
Absorption and reflection are typically modeled as surface phenomena that occur within a fraction of a micrometer of the surface. For example, a highly polished piece of steel will be highly reflective, regardless of the material under the surface. Transmission on the other hand is a volumetric phenomena that is dependent on the properties of the entire thickness of the body. A glass window for instance must be translucent through its entire thickness for radiation to get through.
The term absorption is used to describe the change of heat into other forms of energy when it contacts particle or body. Only material particles can absorb heat rays, not elements of surfaces. For a given frequency of radiation, all mediums have a coefficient of absorption, that represents how much heat will be absorbed per unit distance through a medium. | 0 | Theoretical and Fundamental Chemistry |
We can use the above equations to derive some differential definitions of some thermodynamic parameters. If we define to stand for any of the thermodynamic potentials, then the above equations are of the form:
where and are conjugate pairs, and the are the natural variables of the potential . From the chain rule it follows that:
where is the set of all natural variables of except that are held as constants. This yields expressions for various thermodynamic parameters in terms of the derivatives of the potentials with respect to their natural variables. These equations are known as equations of state since they specify parameters of the thermodynamic state. If we restrict ourselves to the potentials (Internal energy), (Helmholtz energy), (Enthalpy) and (Gibbs energy), then we have the following equations of state (subscripts showing natural variables that are held as constants):
where, in the last equation, is any of the thermodynamic potentials (, , , or ), and are the set of natural variables for that potential, excluding . If we use all thermodynamic potentials, then we will have more equations of state such as
and so on. In all, if the thermodynamic space is dimensions, then there will be equations for each potential, resulting in a total of equations of state because thermodynamic potentials exist. If the equations of state for a particular potential are known, then the fundamental equation for that potential (i.e., the exact differential of the thermodynamic potential) can be determined. This means that all thermodynamic information about the system will be known because the fundamental equations for any other potential can be found via the Legendre transforms and the corresponding equations of state for each potential as partial derivatives of the potential can also be found. | 0 | Theoretical and Fundamental Chemistry |
AFM-IR has been used to characterise spectroscopically in detail chromosomes, bacteria and cells with nanoscale resolution. For example, in the case of infection of bacteria by viruses (Bacteriophages), and also the production of polyhydroxybutyrate (PHB) vesicles inside Rhodobacter capsulatus cells and triglycerides in Streptomyces bacteria (for biofuel applications). AFM-IR has also been used to evaluate and map mineral content, crystallinity, collagen maturity and acid phosphate content via ratiometric analysis of various absorption bands in bone. AFM-IR has also been used to perform spectroscopy and chemical mapping of structural lipids in human skin, cells and hair | 0 | Theoretical and Fundamental Chemistry |
A Daly detector is a gas-phase ion detector that consists of a metal "doorknob", a scintillator (phosphor screen) and a photomultiplier. It was named after its inventor Norman Richard Daly. Daly detectors are typically used in mass spectrometers. | 0 | Theoretical and Fundamental Chemistry |
This process is not 100% efficient. At the Lautenthal, Altenau, and Sankt Andreasberg smelting-works in the Upper Harz between 1857 and 1860 25% of the silver, 25.1% of the lead and 9.3% of the copper was lost. Some of this is lost in slag that is not worth reusing, some is lost by what is termed ‘burning’, and some of the silver is lost to the refined copper. It is clear therefore that a constant supply of lead was needed to make up for that lost at various stages. | 1 | Applied and Interdisciplinary Chemistry |
Solid carbon dioxide (dry ice) sublimes rapidly along the solid-gas boundary (sublimation point) below the triple point (e.g., at the temperature of −78.5 °C, at atmospheric pressure), whereas its melting into liquid CO can occur along the solid-liquid boundary (melting point) at pressures and temperatures above the triple point (i.e., 5.1 atm, −56.6 °C). | 0 | Theoretical and Fundamental Chemistry |
Hexamethylenetetramine is a versatile reagent in organic synthesis. It is used in the Duff reaction (formylation of arenes), the Sommelet reaction (converting benzyl halides to aldehydes), and in the Delepine reaction (synthesis of amines from alkyl halides). | 0 | Theoretical and Fundamental Chemistry |
1,3-Bisphosphoglyceric acid (1,3-Bisphosphoglycerate or 1,3BPG) is a 3-carbon organic molecule present in most, if not all, living organisms. It primarily exists as a metabolic intermediate in both glycolysis during respiration and the Calvin cycle during photosynthesis. 1,3BPG is a transitional stage between glycerate 3-phosphate and glyceraldehyde 3-phosphate during the fixation/reduction of CO. 1,3BPG is also a precursor to 2,3-bisphosphoglycerate which in turn is a reaction intermediate in the glycolytic pathway. | 0 | Theoretical and Fundamental Chemistry |
Early panel codes were developed in the late 1960s to early 1970s. Advanced panel codes, such as Panair (developed by Boeing), were first introduced in the late 1970s, and gained popularity as computing speed increased. Over time, panel codes were replaced with higher order panel methods and subsequently CFD (Computational Fluid Dynamics). However, panel codes are still used for preliminary aerodynamic analysis as the time required for an analysis run is significantly less due to a decreased number of elements. | 1 | Applied and Interdisciplinary Chemistry |
* Smirnov, Alex Sergeevich (b. 9 June 1963) – Russian businessman. Since 2005 – Vice president of JSC "Lukoil".
* Filatov, Anatoly Vasilievich (b. 28 May 1935) – the Russian metallurgist, the first general manager of the concern "Norilsk Nickel" (1989–1996). Federation Council member of I convocation (1993–1996). Hero of Socialist Labor. | 1 | Applied and Interdisciplinary Chemistry |
Applying line voltage across a pickled cucumber causes it to glow. A moist pickle contains salt as a result of the pickling process, which allows it to conduct electricity. Sodium (or other) ions within the pickle emit light as a result of atomic electron transitions, although it is not clear why the luminescence occurs at one end of the pickle.
The glowing pickle is used to demonstrate ionic conduction and atomic emission in chemistry classes, and also as a demonstration in lighting classes.
The first known fully documented demonstration was in a 1989 report from Digital Equipment Corporation. Although this was published as a full technical note and written up as a scientific paper, the publication date, April Fools' Day of that year, gives some indication as to the light-hearted nature of the document. | 1 | Applied and Interdisciplinary Chemistry |
Bacterial initiation factor 1 is a bacterial initiation factor.
IF1 associates with the 30S ribosomal subunit in the A site and prevents an aminoacyl-tRNA from entering. It modulates IF2 binding to the ribosome by increasing its affinity. It may also prevent the 50S subunit from binding, stopping the formation of the 70S subunit. It also contains a β-domain fold common for nucleic acid binding proteins.
IF1–IF3 may also perform ribosome recycling. | 1 | Applied and Interdisciplinary Chemistry |
All pharmaceuticals are derived from petroleum, albeit via mutlistep processes. Modern medicine depends on petroleum as a source of building blocks, reagents, and solvents. Similarly, virtually all pesticides - insecticides, herbicides, etc. - are derived from petroleum. Pesticides have profoundly affected life expectancies by controlling disease vectors and by increasing yields of crops. Like pharmaceuticals, pesticides are in essence petrochemicals. Virtually all plastics and synthetic polymers are derived from petroleum, which is the source of monomers. Alkenes (olefins) are one important class of these precursor molecules. | 0 | Theoretical and Fundamental Chemistry |
Brownrigg also produced a major treatise on salt manufacture. He hoped that improved domestic production could make Britain self-sufficient in this valuable resource thereby improving the fishing industry and economy both in Britain and America. Much of the best quality salt was bay salt produced in France and Spain; the two European powers with whom Britain was most likely to be at war with in the eighteenth century. When a paper based upon his book was read at the Royal Society in June 1748 (whilst the negotiations which were to lead to the peace treaty ending the War of the Austrian Succession were still under way), it was considered the most important paper read there in the last fifty years. | 1 | Applied and Interdisciplinary Chemistry |
Energy Manufacturing Co., Inc. is an American manufacturing company based in Monticello, Iowa. Established in 1944, the company produces a variety of hydraulic cylinders, hydraulic pumps, valves, and power systems. | 1 | Applied and Interdisciplinary Chemistry |
BIND has grown significantly since its conception; in fact, the database saw a 10 fold increase in entries between 2003 and 2004. By September 2004, there were over 100,000 interaction records by 2004 (including 58,266 protein-protein, 4,225 genetic, 874 protein-small molecule, 25,857 protein-DNA, and 19,348 biopolymer interactions). The database also contains sequence information for 31,972 proteins, 4560 DNA samples and 759 RNA samples. These entries have been collected from 11,649 publications; therefore, the database represents an important amalgamation of data. The organisms with entries in the database include: Saccharomyces cerevisiae, Drosophila melanogaster, Homo sapiens, Mus musculus, Caenorhabditis elegans, Helicobacter pylori, Bos taurus, HIV-1, Gallus gallus, Arabidopsis thaliana, as well as others. In total, 901 taxa were included by September 2004 and BIND has been split up into BIND-Metazoa, BIND-Fungi, and BIND-Taxroot.
Not only is the information contained within the database continually updated, the software itself has gone through several revisions. Version 1.0 of BIND was released in 1999 and based on user feedback it was modified to include additional detail on experimental conditions required for binding and a hierarchical description of cellular location of the interaction. Version 2.0 was released in 2001 and included the capability to link to information available in other databases. Version 3.0 (2002) expanded the database from physical/biochemical interactions to also include genetic interactions. Version 3.5 (2004) included a refined user-interface that aimed to simplify information retrieval. In 2006, BIND was incorporated into the Biomolecular Object Network Database (BOND) where it continues to be updated and improved. | 1 | Applied and Interdisciplinary Chemistry |
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