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Several factors led to the first chemical revolution. First, there were the forms of gravimetric analysis that emerged from alchemy and new kinds of instruments that were developed in medical and industrial contexts. In these settings, chemists increasingly challenged hypotheses that had already been presented by the ancient Greeks. For example, chemists began to assert that all structures were composed of more than the four elements of the Greeks or the eight elements of the medieval alchemists. The Irish alchemist, Robert Boyle, laid the foundations for the Chemical Revolution, with his mechanical corpuscular philosophy, which in turn relied heavily on the alchemical corpuscular theory and experimental method dating back to pseudo-Geber.
Earlier works by chemists such as Jan Baptist van Helmont helped to shift the belief in theory that air existed as a single element to that of one in which air existed as a composition of a mixture of distinct kinds of gasses. Van Helmont's data analysis also suggests that he had a general understanding of the law of conservation of mass in the 17th century. Furthermore, work by Jean Rey in the early 17th century with metals like tin and lead and their oxidation in the presence of air and water helped pinpoint the contribution and existence of oxygen in the oxidation process.
Other factors included new experimental techniques and the discovery of fixed air (carbon dioxide) by Joseph Black in the middle of the 18th century. This discovery was particularly important because it empirically proved that air did not consist of only one substance and because it established gas as an important experimental substance. Nearer the end of the 18th century, the experiments by Henry Cavendish and Joseph Priestley further proved that air is not an element and is instead composed of several different gases. Lavoisier also translated the names of chemical substance into a new nomenclatural language more appealing to scientists of the nineteenth century. Such changes took place in an atmosphere in which the industrial revolution increased public interest in learning and practicing chemistry. When describing the task of reinventing chemical nomenclature, Lavoisier attempted to harness the new centrality of chemistry by making the rather hyperbolic claim that: | 1 | Applied and Interdisciplinary Chemistry |
All data in T3DB is non-proprietary or is derived from a non-proprietary source. It is freely accessible and available to anyone. In addition, nearly every data item is fully traceable and explicitly referenced to the original source. T3DB data is available through a public web interface and downloads. | 1 | Applied and Interdisciplinary Chemistry |
An automated read-across tool called Generalized Read-Across (GenRA) is integrated into The Chemicals Dashboard. GenRA is designed to keep the expert consideration inherent in the read-across method, but automate the chemical selection process to help predict toxicity.
The Dashboard also has the capability to search existing scientific literature sources such as PubMed, via a web-based version of the "Abstract Sifter", Google Scholar and reports from EPA's Provisional Peer Reviewed Toxicity Values ([https://www.epa.gov/pprtv/provisional-peer-reviewed-toxicity-values-pprtvs-assessments PPRTV]) and the EPA Integrated Risk Information System ([https://www.epa.gov/iris IRIS]).
Real-time QSAR prediction for multiple physicochemical property and toxicity endpoints is available through the [https://comptox.epa.gov/dashboard/predictions/index predictions tab]. | 1 | Applied and Interdisciplinary Chemistry |
The ÄKTA explorer was the first high end FPLC (Fast Protein Liquid Chromatography) system that was developed for Life Science research by the Swedish company Pharmacia in 1994. Its purpose was to simplify and automatize protein purification. It was followed by a line of similar devices (the "Äkta" line). The product line name was transferred together with the sale of Pharmacia first to Amersham and then to GE Healthcare. Although protein purification is possible with a large range of chromatographic devices, the Äkta line represents together with BioRad's NGC line the only devices that were specifically designed for this purpose both from the hardware and software perspective. Main users of these devices are the pharmaceutical industry and academic researchers. | 0 | Theoretical and Fundamental Chemistry |
At constant temperature, the reversibility of polymerization can be determined using the Gibbs free energy equation:
where is the change of entropy during polymerization. The change of enthalpy during polymerization, , is also known as the heat of polymerization, which is defined by
where and denote the activation energies for polymerization and depolymerization, respectively, on the assumption that depolymerization occurs by the reverse mechanism of polymerization.
Entropy is the measure of randomness or chaos. A system has a lower entropy when there are few objects in the system and has a higher entropy when there are many objects in the system. Because the process of depolymerization involves a polymer being broken down into its monomers, depolymerization increases entropy. In the Gibbs free energy equation, the entropy term is negative. Enthalpy drives polymerizations. At low temperatures, the enthalpy term is greater than the term, which allows polymerization to occur. At the ceiling temperature, the enthalpy term and the entropy term are equal, so that the rates of polymerization and depolymerization become equal and the net polymerization rate becomes zero. Above the ceiling temperature, the rate of depolymerization is greater than the rate of polymerization, which inhibits the formation of the given polymer. The ceiling temperature can be defined by | 0 | Theoretical and Fundamental Chemistry |
Olson remained at the Flory group for a post doc research, after which she became a Damon Runyon Cancer Research Foundation Postdoctoral Fellow with geneticist Charles R. Cantor at Columbia University.
In 1972, Olson became an assistant professor at Rutgers University and full professor in 1979.
During her time at Rutgers, she was a visiting professor at the University of Basel in Switzerland (1979–1980) and at the Polymer Chemistry Department of the Jilin University in Changchun, China (1981).
Wilma Olson was involved in setting up the nucleic acid database, in collaboration with Helen M. Berman. | 1 | Applied and Interdisciplinary Chemistry |
The Scythians emerged as a people prior to the 7th Century BC, when they were first mentioned in historical records. The Scythian civilization consisted of a number of distinct tribal groups scattered across the Pontic Steppes, Caucasus, and Central Asia. Though primarily a nomadic people, the Scythians established a number of settlements across their territory; these establishments in turn allowed for the development of a sedentary society and the accompanying development of trade skills, including metalworking.
Scythian knowledge of metalworking likely originated with the peoples of Iran and China, with this knowledge spreading along trade routes and arriving in the steppes from the 2nd to 1st Millennium BC. Early Scythian metallurgy was centered around bronzeworking, as these skills had already been widely adopted by the Scythians neighbors. The Minusinsk Basin of Siberia has been speculated as the origin point for the raw materials used in Bronze-age Scythian metallurgy, and Scythian access to this region fueled the peoples later centuries of expansion. During the 8th Century BC Scythians were often employed by nations in the Near East and these returning soldiers may have brought knowledge of iron-working back to their homeland, and by the start of the 6th-century BC the practice was widespread in the Pontic steppes. In addition to bronze and iron working, gold and copper-working were also present in Scythian society; in his commentary on the Scythian people, Greek historian Herodotus remarked on their fondness for making things from gold and copper.
Metallurgy held a major place in Scythian society as metalworkers were needed to produce material goods to support the Scythian way of life. As a nomadic society with broad borders, the Scythians often raided neighboring peoples and as such required metal weaponry - particularly iron swords and bronze arrowheads. It has been speculated that the Scythian's use of stylized metal adornments may have been copied from their opponents during these conflicts. In addition, jewelry and other adornment was in demand among all classes of society, as can be seen with the discovery of metal adornments in the burial tombs attributed to the Scythians. One notable aspect of Scythian clothing was the widespread use of metal belts.
Other signs of Scythian metalworking can be found throughout sites attributed to the people. Several notable Scythian archeological sites contain the remnants of metalworking operations; at one settlement along the Dnieper, remnants of blast furnaces and slag have been found, implying the existence of a large metallurgical center. Studies of other Scythian sites have also led to the remains of metal workshops and tools being found, further supporting the theory that the Scythians were organized craftspeople. Scythian metalworkers were particularly renowned for the high quality of their copper crafting. During war, portable molds were brought to forge arrowheads for the Scythian cavalry. Scythian metallurgy also influenced the metallurgy of the Koban people of the North Caucasus. | 1 | Applied and Interdisciplinary Chemistry |
A clinical trial in cardiac arrest patients showed that hypothermia improved neurological outcome and reduced mortality. A retrospective study of the use of hypothermia for cardiac arrest patients showed favorable neurological outcome and survival. Osborn waves on electrocardiogram (ECG) are frequent during TTM after cardiac arrest, particularly in patients treated with 33 °C. Osborn waves are not associated with increased risk of ventricular arrhythmia, and may be considered a benign physiological phenomenon, associated with lower mortality in univariable analyses. | 1 | Applied and Interdisciplinary Chemistry |
The Curtin–Hammett principle applies to systems in which different products are formed from two substrates in equilibrium with one another. The rapidly interconverting reactants can have any relationship between themselves (stereoisomers, constitutional isomers, conformational isomers, etc.). Product formation must be irreversible, and the different products must be unable to interconvert.
For example, given species A and B that equilibrate rapidly while A turns irreversibly into C, and B turns irreversibly into D:
K is the equilibrium constant between A and B, and k and k are the rate constants for the formation of C and D, respectively. When the rate of interconversion between A and B is much faster than either k or k, then the Curtin–Hammett principle tells us that the C:D product ratio is not equal to the equilibrium A:B reactant ratio, but is instead determined by the relative energies of the transition states (i.e., difference in the absolute energies of the transition states). If reactants A and B were at identical energies, the product ratio would depend only on the activation barriers of the reactions leading to each respective product. However, in a real-world scenario, the two reactants are likely at somewhat different energy levels, although the barrier to their interconversion must be low for the Curtin–Hammett scenario to apply. In this case, the product distribution depends both on the equilibrium ratio of A to B and on the relative activation barriers going to the corresponding products C and D. Both factors are taken into account by the difference in the energies of the transition states (ΔΔG in the figure below).
The reaction coordinate free energy profile of a typical reaction under Curtin-Hammett control is represented by the following figure:
The ratio of products only depends on the value labeled ΔΔG in the figure: C will be the major product, because the energy of TS1 is lower than the energy of TS2. A common but false assertion is that the product distribution does not in any way reflect the relative free energies of substrates A and B; in fact, it reflects the relative free energies of the substrates and the relative activation energies. This misunderstanding may stem from failing to appreciate the distinction between "the difference of energies of activation" and "the difference in transition state energies". Although these quantities may at first appear synonymous, the latter takes into account the equilibrium constant for interconversion of A and B, while the former does not.
Mathematically, the product ratio can be expressed as a function of K, k, and k or in terms of the corresponding energies ΔG°, ΔG, and ΔG. By combining terms, the product ratio can be rewritten in terms of the quantity ΔΔG alone, where ΔΔG = (ΔG – ΔG) + ΔG°. Inspection of the energy diagram (shown above) makes it apparent that ΔΔG is precisely the difference in transition state energies. | 0 | Theoretical and Fundamental Chemistry |
In a recent study, the production of pyoverdine (PVD), a type of siderophore, in the bacterium Pseudomonas aeruginosa has been explored. This study focused on the construction, modeling, and dynamic simulation of PVD biosynthesis, a virulence factor, through a systemic approach. This approach considers that the metabolic pathway of PVD synthesis is regulated by the phenomenon of quorum-sensing (QS), a cellular communication system that allows bacteria to coordinate their behavior based on their population density.
The study showed that as bacterial growth increases, so does the extracellular concentration of QS signaling molecules, thus emulating the natural behavior of P. aeruginosa PAO1. To carry out this study, a metabolic network model of P. aeruginosa was built based on the iMO1056 model, the genomic annotation of the P. aeruginosa PAO1 strain, and the metabolic pathway of PVD synthesis. This model included the synthesis of PVD, transport reactions, exchange, and QS signaling molecules.
The resulting model, called CCBM1146, showed that the QS phenomenon directly influences the metabolism of P. aeruginosa towards the biosynthesis of PVD as a function of the change in QS signal intensity. This work is the first in silico report of an integrative model that comprises the QS gene regulatory network and the metabolic network of P. aeruginosa, providing a detailed view of how the production of pyoverdine and siderophores in Pseudomonas aeruginosa are influenced by the quorum-sensing phenomenon | 1 | Applied and Interdisciplinary Chemistry |
This method, also called Free energy perturbation (or FEP), involves sampling from state A only. It requires that all the high probability configurations of super state B are contained in high probability configurations of super state A, which is a much more stringent requirement than the overlap condition stated above. | 0 | Theoretical and Fundamental Chemistry |
* 1.B.1 General bacterial porin family
* 1.B.2 Chlamydial porin (CP) family
* 1.B.3 Sugar porin (SP) family
* 1.B.4 Brucella-Rhizobium porin (BRP) family
* 1.B.5 Pseudomonas OprP porin (POP) family
* 1.B.6 OmpA-OmpF porin (OOP) family
* 1.B.7 Rhodobacter PorCa porin (RPP) family
* 1.B.8 Mitochondrial and plastid porin (MPP) family
* 1.B.9 FadL outer membrane protein (FadL) family
* 1.B.10 Nucleoside-specific channel-forming outer membrane porin (Tsx) family
* 1.B.11 Outer membrane fimbrial usher porin (FUP) family
* 1.B.12 Autotransporter-1 (AT-1) family
* 1.B.13 Alginate export porin (AEP) family
* 1.B.14 Outer membrane receptor (OMR) family
* 1.B.15 Raffinose porin (RafY) family
* 1.B.16 Short chain amide and urea porin (SAP) family
* 1.B.17 Outer membrane factor (OMF) family
* 1.B.18 Outer membrane auxiliary (OMA) protein family
* 1.B.19 Glucose-selective OprB porin (OprB) family
* 1.B.20 Two-partner secretion (TPS) family
* 1.B.21 OmpG porin (OmpG) family
* 1.B.22 Outer bacterial membrane secretin (secretin) family
* 1.B.23 Cyanobacterial porin (CBP) family
* 1.B.24 Mycobacterial porin
* 1.B.25 Outer membrane porin (Opr) family
* 1.B.26 Cyclodextrin porin (CDP) family
* 1.B.31 Campylobacter jejuni major outer membrane porin (MomP) family
* 1.B.32 Fusobacterial outer membrane porin (FomP) family
* 1.B.33 Outer membrane protein insertion porin (Bam complex) (OmpIP) family
* 1.B.34 Corynebacterial porins
* 1.B.35 Oligogalacturonate-specific porin (KdgM) family
* 1.B.39 Bacterial porin, OmpW (OmpW) family
* 1.B.42 Outer membrane lipopolysaccharide export porin (LPS-EP) family
* 1.B.43 Coxiella porin P1 (CPP1) family
* 1.B.44 Probable protein translocating porphyromonas gingivalis porin (PorT) family
* 1.B.49 Anaplasma P44 (A-P44) porin family
* 1.B.48 Curli-like transporters
* 1.B.54 Intimin/Invasin (Int/Inv) or Autotransporter-3 family
* 1.B.55 Poly-acetyl-D-glucosamine porin (PgaA) family
* 1.B.57 Legionella major-outer membrane protein (LM-OMP) family
* 1.B.60 Omp50 porin (Omp50 Porin) family
* 1.B.61 Delta-proteobacterial porin (Delta-porin) family
* 1.B.62 Putative bacterial porin (PBP) family
* 1.B.66 Putative beta-barrel porin-2 (BBP2) family
* 1.B.67 Putative beta barrel porin-4 (BBP4) family
* 1.B.68 Putative beta barrel porin-5 (BBP5) superfamily
* 1.B.70 Outer membrane channel (OMC) family
* 1.B.71 Proteobacterial/verrucomicrobial porin (PVP) family
* 1.B.72 Protochlamydial outer membrane porin (PomS/T) family
* 1.B.73 Capsule biogenesis/assembly (CBA) family
* 1.B.78 DUF3374 electron transport-associated porin (ETPorin) family | 1 | Applied and Interdisciplinary Chemistry |
Further modifications on N-myristoylated proteins can add another level of regulation for myristoylated protein. Dual acylation can facilitate more tightly regulated protein localization, specifically targeting proteins to lipid rafts at membranes or allowing dissociation of myristoylated proteins from membranes.
Myristoylation and palmitoylation are commonly coupled modifications. Myristoylation alone can promote transient membrane interactions that enable proteins to anchor to membranes but dissociate easily. Further palmitoylation allows for tighter anchoring and slower dissociation from membranes when required by the cell. This specific dual modification is important for G protein-coupled receptor pathways and is referred to as the dual fatty acylation switch.
Myristoylation is often followed by phosphorylation of nearby residues. Additional phosphorylation of the same protein can decrease the electrostatic affinity of the myristoylated protein for the membrane, causing translocation of that protein to the cytoplasm following dissociation from the membrane. | 1 | Applied and Interdisciplinary Chemistry |
Related to η-O-bonded complexes of aldehydes and ketones are metal acetylacetonates and related species, which can be viewed as a combination of ketone and enolate ligands. | 0 | Theoretical and Fundamental Chemistry |
The following procedure is typically followed when performing an acid-base extraction for a mixture containing an acidic and/or basic compound:
#The mixture of compounds is dissolved in a suitable organic solvent, such as dichloromethane or diethyl ether.
# The solution is added to a separatory funnel. If the desired compound is basic, the solution will be washed with aqueous acid (e.g. 5% HCl); if it is acidic, the solution is washed with aqueous base (e.g. 5% NaOH).
# The fractions are then shaken and the two phases are separated. The separatory funnel must be vented frequently to alleviate pressure build-up, especially when containing aqueous solutions that evolve carbon dioxide gas upon neutralization (such as sodium bicarbonate).
# The fraction containing the analyte of interest is then collected. Typically, this is the aqueous layer, as addition of acid or base has caused the analyte to become charged and highly soluble in the aqueous layer. The identity of the aqueous layer depends critically on the organic solvent's density. Organic solvents with a density greater than 1.00 g/mL (e.g. dichloromethane) cause the aqueous layer to float to the top, while solvents with a density lower than 1.00 g/mL (e.g. ether) cause the aqueous layer to sink to the bottom.
# The organic fraction is added to the separatory funnel again, and steps 2-4 are repeated twice more to maximize the yield of the extraction. On the final rinse, a brine solution drives any remaining aqueous solution out of the organic layer.
# If the remaining organic layer contains no analytes of interest, it is discarded; otherwise, the solvent is dried over a suitable drying agent (such as anhydrous sodium sulfate), filtered, then evaporated under reduced pressure to yield the pure compound. If the aqueous layer contains the analyte of interest, it is adjusted to the opposite pH (e.g. basic to acidic). Steps 1-4 are repeated with this fraction using an aqueous solution of opposite pH (e.g. NaOH to HCl). This circular procedure is performed since it is typically much easier to remove organic solvent via rotary evaporation than aqueous solvent. | 0 | Theoretical and Fundamental Chemistry |
A similar but denser material, consisting of an electrodeposited nanocrystalline nickel layer over a polymeric rapid-prototyped truss, was created by researchers at the University of Toronto in 2008. In 2012, German researchers created a carbon foam known as aerographite, with an even lower density than a metallic microlattice. In 2013, Chinese scientists developed a carbon-based aerogel which was claimed to be lighter still.
Nanolattices like tube-based nanostructures are similar structures on a smaller scale. | 0 | Theoretical and Fundamental Chemistry |
The graphs below show the behaviour of fractional derivatives calculated by different algorithms for ferrocene in acetonitrile at 100mV/s, the reference electrode is 0.1M Ag/Ag in acetonitrile (+0.04V vs. Fc). | 0 | Theoretical and Fundamental Chemistry |
The Knight shift (first reported in 1949) and Shoolery's rule are observed with pure metals and methylene groups, respectively. The NMR chemical shift in its present-day meaning first appeared in journals in 1950. Chemical shifts with a different meaning appear in X-ray photoelectron spectroscopy as the shift in atomic core-level energy due to a specific chemical environment. The term is also used in Mössbauer spectroscopy, where similarly to NMR it refers to a shift in peak position due to the local chemical bonding environment. As is the case for NMR the chemical shift reflects the electron density at the atomic nucleus. | 0 | Theoretical and Fundamental Chemistry |
Specific uses for phenoxymethylpenicillin include:
* Infections caused by Streptococcus pyogenes
** Tonsillitis
** Pharyngitis
** Skin infections
* Anthrax (mild uncomplicated infections)
* Lyme disease (early stage in pregnant women or young children)
* Rheumatic fever (primary and secondary prophylaxis)
* Streptococcal skin infections
* Spleen disorders (pneumococcal infection prophylaxis)
* Initial treatment for dental abscesses
* Moderate-to-severe gingivitis (with metronidazole)
* Avulsion injuries of teeth (as an alternative to tetracycline)
* Blood infection prophylaxis in children with sickle cell disease.
Penicillin V is sometimes used in the treatment of odontogenic infections.
It is less active than benzylpenicillin (penicillin G) against Gram-negative bacteria. Phenoxymethylpenicillin has a range of antimicrobial activity against Gram-positive bacteria that is similar to that of benzylpenicillin and a similar mode of action, but it is substantially less active than benzylpenicillin against Gram-negative bacteria.
Phenoxymethylpenicillin is more acid-stable than benzylpenicillin, which allows it to be given orally.
Phenoxymethylpenicillin is usually used only for the treatment of mild to moderate infections, and not for severe or deep-seated infections since absorption can be unpredictable. Except for the treatment or prevention of infection with Streptococcus pyogenes (which is uniformly sensitive to penicillin), therapy should be guided by bacteriological studies (including sensitivity tests) and by clinical response. People treated initially with parenteral benzylpenicillin may continue treatment with phenoxymethylpenicillin by mouth once a satisfactory response has been obtained.
It is not active against beta-lactamase-producing bacteria, which include many strains of Staphylococci. | 0 | Theoretical and Fundamental Chemistry |
After his fathers death, Hatchett largely gave up his activities as a chemist. He inherited his fathers coach-making business and pursued interests in collecting books (including a First Folio) manuscripts, paintings, and musical instruments. His loss was lamented by colleagues such as Thomas Thomson (1773–1852), who wrote that Hatchett "was an active chemist…but unfortunately this most amiable and accomplished man has been lost to science for more than a quarter of a century; the baneful effects of wealth, and cares of a lucrative and extensive business, having completely waned him from scientific pursuits".
Hatchett lived at Mount Clare, Roehampton from 1807 to 1819.
It has been described as "a little estate built in a fine Italian style" with nearby "a very well-equipped laboratory". The house was designed by Sir Robert Taylor for George Clive, with modifications by the Italian architect Placido Columbani in 1780. The gardens were laid out by Capability Brown in 1774.
In 1818 Hatchett either bought back or chose to no longer lease out the house that had been built by his father in 1771, Belle Vue, 92 Cheyne Walk, in Chelsea, London. A grade II listed building, it has a large central portion with bay windows back and front, and two wings. It overlooks gardens and the River Thames. He lived there for the rest of his life. Elizabeth, his wife, predeceased him in 1837.
Hatchett himself died at Belle Vue House in 1847, and is buried at St Laurence's Church, Upton-cum-Chalvey, Slough,
the same church where his friend William Herschel is interred. | 1 | Applied and Interdisciplinary Chemistry |
Because radiopharmeuticals require special licenses and handling techniques, they are often kept in local centers for medical radioisotope storage, often known as radiopharmacies. A radiopharmacist may dispense them from there, to local centers where they are handled at the practical medicine facility. | 1 | Applied and Interdisciplinary Chemistry |
David Dye is a Professor of Metallurgy at Imperial College London. Dye specialises in fatigue and micromechanics of aerospace and nuclear materials, mainly Ni/Co superalloys, titanium, TWIP steel, and Zirconium alloys. | 1 | Applied and Interdisciplinary Chemistry |
The Taiwan Typhoon and Flood Research Institute (TTFRI) was a research institute which is part of the National Applied Research Laboratories of Taiwan. It was merged into the National Science and Technology Center for Disaster Reduction in 2018. | 1 | Applied and Interdisciplinary Chemistry |
For multicomponent solutions, apparent molar properties can be defined in several ways. For the volume of a ternary (3-component) solution with one solvent and two solutes as an example, there would still be only one equation , which is insufficient to determine the two apparent volumes. (This is in contrast to partial molar properties, which are well-defined intensive properties of the materials and therefore unambiguously defined in multicomponent systems. For example, partial molar volume is defined for each component i as .)
One description of ternary aqueous solutions considers only the weighted mean apparent molar volume of the solutes, defined as
where is the solution volume and the volume of pure water.
This method can be extended for mixtures with more than 3 components.
The sum of products molalities – apparent molar volumes of solutes in their binary solutions equals the product between the sum of molalities of solutes and apparent molar volume in ternary of multicomponent solution mentioned above.
Another method is to treat the ternary system as pseudobinary and define the apparent molar volume of each solute with reference to a binary system containing both other components: water and the other solute. The apparent molar volumes of each of the two solutes are then
: and
The apparent molar volume of the solvent is:
However, this is an unsatisfactory description of volumetric properties.
The apparent molar volume of two components or solutes considered as one pseudocomponent or is not to be confused with volumes of partial binary mixtures with one common component V, V which mixed in a certain mixing ratio form a certain ternary mixture V or V.
Of course the complement volume of a component in respect to other components of the mixture can be defined as a difference between the volume of the mixture and the volume of a binary submixture of a given composition like:
There are situations when there is no rigorous way to define which is solvent and which is solute like in the case of liquid mixtures (say water and ethanol) that can dissolve or not a solid like sugar or salt. In these cases apparent molar properties can and must be ascribed to all components of the mixture. | 0 | Theoretical and Fundamental Chemistry |
Nuclear reaction analysis (NRA) is a nuclear method of nuclear spectroscopy in materials science to obtain concentration vs. depth distributions for certain target chemical elements in a solid thin film. | 0 | Theoretical and Fundamental Chemistry |
SOLID was designed for automatic in situ detection and identification of substances from liquid and crushed samples under the conditions of outer space. The system uses hundreds of carefully selected antibodies to detect lipids, proteins, polysaccharides, and nucleic acids. These are complex biological polymers that could only be synthesized by life forms, and are therefore strong indicators —biosignatures— of past or present life.
SOLID consists of two separate functional units: a Sample Preparation Unit (SPU) for extractions by ultrasonication, and a Sample Analysis Unit (SAU), for fluorescent immunoassays. The antibody microarrays are separated in hundreds of small compartments inside a biochip only a few square centimeters in size.
SOLID instrument is able to perform both "sandwich" and competitive immunoassays using hundreds of well characterized and highly specific antibodies. The technique called "sandwich immunoassay" is a non-competitive immunoassay in which the analyte (compound of interest in the unknown sample) is captured by an immobilized antibody, then a labeled antibody is bound to the analyte to reveal its presence. In other words, the "sandwich" quantify antigens (i.e. biomolecules) between two layers of antibodies (i.e. capture and detection antibody). For the competitive assay technique, unlabeled analyte displaces bound labelled analyte, which is then detected or measured.
An optical system is set up so that a laser beam excites the fluorochrome label and a CCD detector captures an image of the microarray that can be measured.
The instrument is able to detect a broad range of molecular size compounds, from the amino acid size, peptides, proteins, to whole cells and spores, with sensitivities at 1–2 ppb (ng/mL) for biomolecules and 104 to 103 spores per milliliter. Some compartments in the microarray are reserved for samples of known nature and concentrations, that are used as controls for reference and comparison. SOLID instrument concept avoids the high-temperature treatments of other techniques that may destroy organic matter in the presence of Martian oxidants such as perchlorates. | 1 | Applied and Interdisciplinary Chemistry |
DiProDB is a database designed to collect and analyse thermodynamic, structural and other dinucleotide properties. | 0 | Theoretical and Fundamental Chemistry |
The purpose of FuseNet is to coordinate and facilitate fusion education, to share best practices, to jointly develop educational tools, to organize educational events. The members of FuseNet have jointly established academic criteria for the award of European Fusion Doctorate and Master Certificates. These criteria are set to stimulate a high level of fusion education throughout Europe. | 0 | Theoretical and Fundamental Chemistry |
Ultraviolet–visible spectroscopy (UV–vis) can distinguish between enantiomers by showing a distinct Cotton effect for each isomer. UV–vis spectroscopy sees only chromophores, so other molecules must be prepared for analysis by chemical addition of a chromophore such as anthracene. Two methods are reported: the octant rule and the exciton chirality method.
The octant rule was introduced in 1961 by William Moffitt, R. B. Woodward, A. Moscowitz, William Klyne and Carl Djerassi. This empirical rule allows the prediction of the sign of the Cotton effect by analysing relative orientation of substituents in three dimensions and in this way the absolute configuration of an enantiomer. | 0 | Theoretical and Fundamental Chemistry |
Toxicity can be measured by its effects on the target (organism, organ, tissue or cell). Because individuals typically have different levels of response to the same dose of a toxic substance, a population-level measure of toxicity is often used which relates the probabilities of an outcome for a given individual in a population. One such measure is the . When such data does not exist, estimates are made by comparison to known similar toxic things, or to similar exposures in similar organisms. Then, "safety factors" are added to account for uncertainties in data and evaluation processes. For example, if a dose of a toxic substance is safe for a laboratory rat, one might assume that one-tenth that dose would be safe for a human, allowing a safety factor of 10 to allow for interspecies differences between two mammals; if the data are from fish, one might use a factor of 100 to account for the greater difference between two chordate classes (fish and mammals). Similarly, an extra protection factor may be used for individuals believed to be more susceptible to toxic effects such as in pregnancy or with certain diseases. Or, a newly synthesized and previously unstudied chemical that is believed to be very similar in effect to another compound could be assigned an additional protection factor of 10 to account for possible differences in effects that are probably much smaller. This approach is very approximate, but such protection factors are deliberately very conservative, and the method has been found to be useful in a deep variety of applications.
Assessing all aspects of the toxicity of cancer-causing agents involves additional issues, since it is not certain if there is a minimal effective dose for carcinogens, or whether the risk is just too small to see. In addition, it is possible that a single cell transformed into a cancer cell is all it takes to develop the full effect (the "one hit" theory).
It is more difficult to determine the toxicity of chemical mixtures than a pure chemical because each component displays its own toxicity, and components may interact to produce enhanced or diminished effects. Common mixtures include gasoline, cigarette smoke, and industrial waste. Even more complex are situations with more than one type of toxic entity, such as the discharge from a malfunctioning sewage treatment plant, with both chemical and biological agents.
The preclinical toxicity testing on various biological systems reveals the species-, organ- and dose-specific toxic effects of an investigational product. The toxicity of substances can be observed by (a) studying the accidental exposures to a substance (b) in vitro studies using cells/ cell lines (c) in vivo exposure on experimental animals. Toxicity tests are mostly used to examine specific adverse events or specific endpoints such as cancer, cardiotoxicity, and skin/eye irritation. Toxicity testing also helps calculate the No Observed Adverse Effect Level (NOAEL) dose and is helpful for clinical studies. | 1 | Applied and Interdisciplinary Chemistry |
For DNB type of boiling crisis, the flow is characterized by creeping vapor fluid between liquid and the wall. On top of the convective heat transfer, radiation heat transfer contributes to the heat transfer. After the dryout, the flow regime is shifted from an inverted annular to mist flow. | 0 | Theoretical and Fundamental Chemistry |
Most molybdenum is excreted from the human body as molybdate in the urine. Furthermore, urinary excretion of molybdenum increases as dietary molybdenum intake increases. Small amounts of molybdenum are excreted from the body in the feces by way of the bile; small amounts also can be lost in sweat and in hair. | 1 | Applied and Interdisciplinary Chemistry |
In other instances, molecular interactions between gas molecules previously adsorbed on a solid surface form significant interactions with gas molecules in the gaseous phases. Hence, adsorption of gas molecules to the surface is more likely to occur around gas molecules that are already present on the solid surface, rendering the Langmuir adsorption isotherm ineffective for the purposes of modelling. This effect was studied in a system where nitrogen was the adsorbate and tungsten was the adsorbent by Paul Kisliuk (1922–2008) in 1957. To compensate for the increased probability of adsorption occurring around molecules present on the substrate surface, Kisliuk developed the precursor state theory, whereby molecules would enter a precursor state at the interface between the solid adsorbent and adsorbate in the gaseous phase. From here, adsorbate molecules would either adsorb to the adsorbent or desorb into the gaseous phase. The probability of adsorption occurring from the precursor state is dependent on the adsorbates proximity to other adsorbate molecules that have already been adsorbed. If the adsorbate molecule in the precursor state is in close proximity to an adsorbate molecule that has already formed on the surface, it has a sticking probability reflected by the size of the S constant and will either be adsorbed from the precursor state at a rate of k or will desorb into the gaseous phase at a rate of k'. If an adsorbate molecule enters the precursor state at a location that is remote from any other previously adsorbed adsorbate molecules, the sticking probability is reflected by the size of the S constant.
These factors were included as part of a single constant termed a "sticking coefficient", k, described below:
As S is dictated by factors that are taken into account by the Langmuir model, S can be assumed to be the adsorption rate constant. However, the rate constant for the Kisliuk model (R’) is different from that of the Langmuir model, as R’ is used to represent the impact of diffusion on monolayer formation and is proportional to the square root of the systems diffusion coefficient. The Kisliuk adsorption isotherm is written as follows, where θ is fractional coverage of the adsorbent with adsorbate, and t' is immersion time:
Solving for θ yields: | 0 | Theoretical and Fundamental Chemistry |
* A regularly updated repository of hundreds of computational analysis modules that support data preprocessing, gene expression analysis, proteomics, single nucleotide polymorphism (SNP) analysis, flow cytometry, and short-read sequencing.
* A programmatic interface that makes analysis modules available to computational biologists and developers from Python, Java, MATLAB, and R.
* The GenePattern Notebook Environment: Built on the Jupyter Notebook environment, GenePattern Notebook allows researchers to run GenePattern analyses within notebooks that interleave text, graphics, and executable code, creating a single "research narrative."
* GParc: Repository and community for GenePattern users to share and discuss their own GenePattern modules | 1 | Applied and Interdisciplinary Chemistry |
While a person's home may not be a purpose-made shelter, it could be thought of as one if measures are taken to improve the degree of fallout protection. | 0 | Theoretical and Fundamental Chemistry |
Exemestane is metabolized by the liver enzyme CYP3A4. While the CYP3A4 inhibitor ketoconazole had no significant effect on exemestane levels in a clinical trial, the strong CYP3A4 inductor rifampicin significantly cut exemenstane levels about in half (AUC −54%, C −41% for a single dose), potentially compromising its effectiveness. Other 3A4 inductors such as carbamazepine and St John's Wort are expected to have similar effects. The clinical relevance of this effect has not been investigated.
Estrogens probably reduce exemestane effectiveness: It would usually be counter-productive to reduce the body's estrogen synthesis with exemestane and then substitute estrogen with pharmaceuticals. | 0 | Theoretical and Fundamental Chemistry |
Niobium anodizes in a similar fashion to titanium with a range of attractive colors being formed by interference at different film thicknesses. Again the film thickness is dependent on the anodizing voltage. Uses include jewelry and commemorative coins. | 1 | Applied and Interdisciplinary Chemistry |
Fluorescent biomaterials are a possible way of using external factors to observe a pathway more visibly. The method involves fluorescently labeling peptide molecules that would alter an organisms natural pathway. When this peptide is inserted into the organisms cell, it can induce a different reaction. This method can be used, for example to treat a patient and then visibly see the treatment's outcome. | 1 | Applied and Interdisciplinary Chemistry |
In the following example, elemental aluminium reduces the oxide of another metal, in this common example iron oxide, because aluminium forms stronger and more stable bonds with oxygen than iron:
: FeO + 2 Al → 2 Fe + AlO
The products are aluminium oxide, elemental iron, and a large amount of heat. The reactants are commonly powdered and mixed with a binder to keep the material solid and prevent separation.
Other metal oxides can be used, such as chromium oxide, to generate the given metal in its elemental form. For example, a copper thermite reaction using copper oxide and elemental aluminium can be used for creating electric joints in a process called cadwelding, that produces elemental copper (it may react violently):
: 3 CuO + 2 Al → 3 Cu + AlO
Thermites with nanosized particles are described by a variety of terms, such as metastable intermolecular composites, super-thermite, nano-thermite, and nanocomposite energetic materials. | 0 | Theoretical and Fundamental Chemistry |
If a gaseous emission sample is analyzed and found to contain water vapor and a pollutant concentration of say 40 ppmv, then 40 ppmv should be designated as the "wet basis" pollutant concentration. The following equation can be used to correct the measured "wet basis" concentration to a "dry basis" concentration:
Thus, a wet basis concentration of 40 ppmv in a gas having 10 volume percent water vapor would have a dry basis concentration = 40 ÷ ( 1 - 0.10 ) = 44.44 ppmv. | 1 | Applied and Interdisciplinary Chemistry |
DNA transfer between prokaryotic cells occurs in bacteria and archaea, although it has been mainly studied in bacteria. In bacteria, gene transfer occurs by three processes. These are (1) bacterial virus (bacteriophage)-mediated transduction, (2) plasmid-mediated conjugation, and (3) natural transformation. Transduction of bacterial genes by bacteriophage appears to reflect an occasional error during intracellular assembly of virus particles, rather than an adaptation of the host bacteria. The transfer of bacterial DNA is under the control of the bacteriophages genes rather than bacterial genes. Conjugation in the well-studied E. coli' system is controlled by plasmid genes, and is an adaptation for distributing copies of a plasmid from one bacterial host to another. Infrequently during this process, a plasmid may integrate into the host bacterial chromosome, and subsequently transfer part of the host bacterial DNA to another bacterium. Plasmid mediated transfer of host bacterial DNA (conjugation) also appears to be an accidental process rather than a bacterial adaptation.
Natural bacterial transformation involves the transfer of DNA from one bacterium to another through the intervening medium. Unlike transduction and conjugation, transformation is clearly a bacterial adaptation for DNA transfer, because it depends on numerous bacterial gene products that specifically interact to perform this complex process. For a bacterium to bind, take up and recombine donor DNA into its own chromosome, it must first enter a special physiological state called competence. About 40 genes are required in Bacillus subtilis for the development of competence. The length of DNA transferred during B. subtilis transformation can be as much as a third to the whole chromosome. Transformation is a common mode of DNA transfer, and 67 prokaryotic species are thus far known to be naturally competent for transformation.
Among archaea, Halobacterium volcanii forms cytoplasmic bridges between cells that appear to be used for transfer of DNA from one cell to another. Another archaeon, Sulfolobus solfataricus, transfers DNA between cells by direct contact. Frols et al. (2008) found that exposure of S. solfataricus to DNA damaging agents induces cellular aggregation, and suggested that cellular aggregation may enhance DNA transfer among cells to provide increased repair of damaged DNA via homologous recombination. | 1 | Applied and Interdisciplinary Chemistry |
The strong H-H homonuclear dipolar interactions associated with broad NMR lines and short T relaxation time effectively relegate proton for bimolecular NMR. Recent developments of faster MAS, and reduction of dipolar interactions by deuteration have made proton ssNMR as versatile as in solution. This includes spectral dispersion in multi-dimensional experiments as well as structurally valuable restraints and parameters important for studying material dynamics.
Ultra-fast NMR and the associated sharpening of the NMR lines enables NMR pulse sequences to capitalize on proton-detection to improve the sensitivity of the experiments compared to the direct detection of a spin-1/2 system (X). Such enhancement factor is given by:
where are the gyromagnetic ratios, represent the NMR line widths, and represent the quality factor of the probe resonances. | 0 | Theoretical and Fundamental Chemistry |
Depending on the ore and plant size, a furnace can daily output 250 to 800 tons of pre-reduced iron ore. The biggest furnaces, up to 5 meters in diameter and 110 meters long, can process 950 to 1,000 tons of ore daily, excluding fuel. A properly operated plant typically runs for around 300 days per year. The internal refractory typically lasts 7 to 8 months in the most exposed part of the furnace and for 2 years elsewhere. In 1960, a Krupp-Renn furnace using low-grade ore yielded 100 kilotons of iron annually, while a contemporaneous modern blast furnace produced ten times as much cast iron.
Direct reduction processes employing rotary furnaces frequently face a significant challenge due to the localized formation of iron and slag rings, which sinter together and gradually obstruct the furnace. Understanding the mechanism of lining formation is a complex process involving mineralogy, chemical reactions, and ore preparation. The formation of the lining ring, which progressively grows and poisons the furnace, is caused by a few elements in minute quantities. To remedy this, increasing the supply of combustion air or interrupting the furnace charging process are effective solutions. Otherwise, it may be necessary to adjust the grain size of the charged ore or the chemical composition of the mineral blend.
In 1958, Krupp constructed a plant that could generate 420,000 tons per year of pre-reduced iron ore (consisting of six furnaces) which had an estimated value of 90 million Deutsche Mark, or 21.4 million dollars. By contrast, the plant erected in Salzgitter-Watenstedt in 1956–1957, which was well-integrated with an existing steelworks, only cost 33 million Deutsche Mark. At that time, a Krupp-Renn plant presented itself as a feasible substitute to the established blast furnace process, considering its investment and operating costs: initial investment cost per ton produced was nearly half and operating costs were roughly two and a half times greater.
The slag, a glassy silica, can be effortlessly employed as an additive for constructing road surfaces or concrete. However, the method does not produce a recoverable gas similar to blast furnace gas, decreasing its profitability in most cases. Nevertheless, it also solves the issue regarding gas recovery. | 1 | Applied and Interdisciplinary Chemistry |
Infinite Energy is a bi-monthly magazine published in New Hampshire that details theories and experiments concerning alternative energy, new science and new physics. The magazine was founded by the late Eugene Mallove, and is owned by the non-profit New Energy Foundation. It was established in 1994 as Cold Fusion magazine and changed its name in March 1995.
Topics of interest include "new hydrogen physics," also called cold fusion; vacuum energy, or zero point energy; and so-called "environmental energy" which they define as the attempt to violate the Second Law of Thermodynamics, for example with a [http://www.infinite-energy.com/resources/faq.html#Q40 perpetual motion machine]. This is done in pursuit of the founder's commitment to "unearthing new sources of energy and new paradigms in science." The magazine has also published articles and book reviews that are critical of the Big Bang theory that describes the origin of the universe.
The magazine has a print run of 3,000, and is available on U.S. newsstands. The issues range in size from 48 to 100 pages. | 0 | Theoretical and Fundamental Chemistry |
Genuine alternative splicing occurs in both protein-coding genes and non-coding genes to produce multiple products (proteins or non-coding RNAs). External information is needed in order to decide which product is made, given a DNA sequence and the initial transcript. Since the methods of regulation are inherited, this provides novel ways for mutations to affect gene expression.
Alternative splicing may provide evolutionary flexibility. A single point mutation may cause a given exon to be occasionally excluded or included from a transcript during splicing, allowing production of a new protein isoform without loss of the original protein. Studies have identified intrinsically disordered regions (see Intrinsically unstructured proteins) as enriched in the non-constitutive exons suggesting that protein isoforms may display functional diversity due to the alteration of functional modules within these regions. Such functional diversity achieved by isoforms is reflected by their expression patterns and can be predicted by machine learning approaches. Comparative studies indicate that alternative splicing preceded multicellularity in evolution, and suggest that this mechanism might have been co-opted to assist in the development of multicellular organisms.
Research based on the Human Genome Project and other genome sequencing has shown that humans have only about 30% more genes than the roundworm Caenorhabditis elegans, and only about twice as many as the fly Drosophila melanogaster. This finding led to speculation that the perceived greater complexity of humans, or vertebrates generally, might be due to higher rates of alternative splicing in humans than are found in invertebrates. However, a study on samples of 100,000 expressed sequence tags (EST) each from human, mouse, rat, cow, fly (D. melanogaster), worm (C. elegans), and the plant Arabidopsis thaliana found no large differences in frequency of alternatively spliced genes among humans and any of the other animals tested. Another study, however, proposed that these results were an artifact of the different numbers of ESTs available for the various organisms. When they compared alternative splicing frequencies in random subsets of genes from each organism, the authors concluded that vertebrates do have higher rates of alternative splicing than invertebrates. | 1 | Applied and Interdisciplinary Chemistry |
If the cylinder oscillates in the axial direction with velocity , then the velocity field is
where is the modified Bessel function of the second kind. | 1 | Applied and Interdisciplinary Chemistry |
* The term on the left-hand side is the material derivative of the vorticity vector . It describes the rate of change of vorticity of the moving fluid particle. This change can be attributed to unsteadiness in the flow (, the unsteady term) or due to the motion of the fluid particle as it moves from one point to another (, the convection term).
* The term on the right-hand side describes the stretching or tilting of vorticity due to the flow velocity gradients. Note that is a vector quantity, as is a scalar differential operator, while is a nine-element tensor quantity.
* The term describes stretching of vorticity due to flow compressibility. It follows from the Navier-Stokes equation for continuity, namely where is the specific volume of the fluid element. One can think of as a measure of flow compressibility. Sometimes the negative sign is included in the term.
* The term is the baroclinic term. It accounts for the changes in the vorticity due to the intersection of density and pressure surfaces.
* The term , accounts for the diffusion of vorticity due to the viscous effects.
* The term provides for changes due to external body forces. These are forces that are spread over a three-dimensional region of the fluid, such as gravity or electromagnetic forces. (As opposed to forces that act only over a surface (like drag on a wall) or a line (like surface tension around a meniscus). | 1 | Applied and Interdisciplinary Chemistry |
Polymers with identical composition but different molecular weights may exhibit different physical properties. In general, increasing degree of polymerization correlates with higher melting temperature and higher mechanical strength. | 0 | Theoretical and Fundamental Chemistry |
Crimped or pressed connections to use special fittings permanently attached to tubing with a powered crimper. The fittings, manufactured with a pre-installed sealant or O-ring, slide over the tubing to be connected. High pressure is used to deform the fitting and compress the sealant against the inner tubing, creating a leakproof seal.
The advantages of this method are durability, speed, neatness, and safety. The connection can be made even when the tubing is wet. Crimped fittings are suitable for drinking water pipes and other hot-and-cold systems (including central heating). They are more expensive than sweated fittings.
Press fittings with either V and M profile (or contour) in stainless steel, carbon steel, and copper are trendy in Europe, and several manufacturers such as Viega, Geberit, Swiss Fittings, and ISOTUBI, distribute proprietary systems of press fittings. Compared to other connection types, press fittings have the advantages of installation speed and safety. Pressing a stainless steel fitting can be completed within five seconds with the correct equipment. Primary pressing of fittings to pipes or other fittings is performed using electrically powered press equipment, but mechanically driven press equipment is also available.
Press fittings of some major brands carry a plastic slip around the sleeves on each end of the fitting which falls of when the fitting has been compressed. This allows for a simple identification whether a press fitting has securely been installed.
Press fittings with appropriate and region-specific certification may be used for gas lines. Stainless steel and carbon steel press fittings can withstand up to 16 bars of pressure.
A disadvantage of press fittings is the dead space between the pipe and the fitting, which can possibly rule out use for beverage and food applications. | 1 | Applied and Interdisciplinary Chemistry |
Previous studies have used compatibility of trace elements to see the effect it would have on the melt structure of the peridotite solidus. In such studies, partition coefficients of specific elements were examined and the magnitude of these values gave researchers some indication about the degree of polymerization of the melt. A study conducted in East China in 1998 looked at the chemical composition of various elements found in the crust in China. One of the parameters used to characterize and describe the crustal structure in this region was compatibility of various element pairs. Essentially, studies like this showed how compatibility of certain elements can change and be affected by the chemical compositions and conditions of Earth's interior.
Oceanic volcanism is another topic that commonly incorporates the use of compatibility. Since the 1960s, the structure of Earths mantle started being studied by geochemists. The oceanic crust, which is rich in basalts from volcanic activity, show distinct components that provides information about the evolution of the Earths interior over the geologic timescale. Incompatible trace elements become depleted when mantle melts and become enriched in oceanic or continental crust through volcanic activity. Other times, volcanism can produce enriched mantle melt onto the crust. These phenomena can be quantified by looking at radioactive decay records of isotopes in these basalts, which is a valuable tool for mantle geochemists. More specifically, the geochemistry of serpentinites along the ocean floor, specifically subduction zones, can be examined using compatibility of specific trace elements. The compatibility of lead (Pb) into zircons under different environments can also be an indication of zircons in rocks. When observing levels of non-radiogenic lead in zircons, this can be a useful tool for radiometric dating of zircons. | 0 | Theoretical and Fundamental Chemistry |
The existence of nonradioactive isotopes of lighter elements had been suspected in studies of neon as early as 1913, and proven by mass spectrometry of light elements in 1920. At that time the neutron had not yet been discovered, and the prevailing theory was that isotopes of an element differ by the existence of additional protons in the nucleus accompanied by an equal number of nuclear electrons. In this theory, the deuterium nucleus with mass two and charge one would contain two protons and one nuclear electron. However, it was expected that the element hydrogen with a measured average atomic mass very close to , the known mass of the proton, always has a nucleus composed of a single proton (a known particle), and could not contain a second proton. Thus, hydrogen was thought to have no heavy isotopes. | 0 | Theoretical and Fundamental Chemistry |
Electrically charged particles (such as fuel ions) will follow magnetic field lines (see Guiding centre). The fusion fuel can therefore be trapped using a strong magnetic field. A variety of magnetic configurations exist, including the toroidal geometries of tokamaks and stellarators and open-ended mirror confinement systems. | 0 | Theoretical and Fundamental Chemistry |
All chain-growth polymerization reactions must include chain initiation and chain propagation. Chain transfer and chain termination steps also occur in many but not all chain-growth polymerizations. | 0 | Theoretical and Fundamental Chemistry |
For bottom-up proteomics, the proteins can be separated by two-dimensional gel electrophoresis and analyzed by matrix-assisted laser desorption/ionization (MALDI) or electrospray ionization mass spectrometry for relative quantification or by inductively coupled plasma mass spectrometry for absolute quantification. For top-down proteomics, the undigested labeled proteins are analyzed. | 0 | Theoretical and Fundamental Chemistry |
These newly cooked strange quarks find their way into a multitude of different final particles that emerge as the hot quark–gluon plasma fireball breaks up, see the scheme of different processes in figure. Given the ready supply of antiquarks in the "fireball", one also finds a multitude of antimatter particles containing more than one strange quark. On the other hand, in a system involving a cascade of nucleon–nucleon collisions, multi-strange antimatter are produced less frequently considering that several relatively improbable events must occur in the same collision process. For this reason one expects that the yield of multi-strange antimatter particles produced in the presence of quark matter is enhanced compared to conventional series of reactions. Strange quarks also bind with the heavier charm and bottom quarks which also like to bind with each other. Thus, in the presence of a large number of these quarks, quite unusually abundant exotic particles can be produced; some of which have never been observed before. This should be the case in the forthcoming exploration at the new Large Hadron Collider at CERN of the particles that have charm and strange quarks, and even bottom quarks, as components. | 0 | Theoretical and Fundamental Chemistry |
The most important as well as most difficult to measure aspects of flow measurement are flow conditions within a pipe upstream of a meter. Flow conditions mainly refer to the flow velocity profile, irregularities in the profile, varying turbulence levels within the flow velocity or turbulence intensity profile, swirl and any other fluid flow characteristics which will cause the meter to register flow different than that expected. It will change the value from the original calibration state referred to as reference conditions that are free of installation effects. | 1 | Applied and Interdisciplinary Chemistry |
Dry ice sublimates at and is a cryogenic hazard. Proper PPE, including appropriate gloves, goggles, and apron are required when handling, and contact with bare skin should be avoided. Dry ice will naturally sublimate away in ambient air, but should always be kept in a well-ventilated area to prevent hazardous buildup of carbon dioxide gas or displacement of oxygen. Symptoms of carbon dioxide overexposure include dizziness, headache, shortness of breath, hyperventilation, anxiety, and in certain individuals, panic attacks. | 1 | Applied and Interdisciplinary Chemistry |
Anabaseine (3,4,5,6-tetrahydro-2,3′-bipyridine) is an alkaloid toxin produced by Nemertines and Aphaenogaster ants. It is structurally similar to nicotine and anabasine. Similarly, it has been shown to act as an agonist on most nicotinic acetylcholine receptors in the central nervous system and peripheral nervous system. | 1 | Applied and Interdisciplinary Chemistry |
Bloch remained in European academia, working on superconductivity with Wolfgang Pauli in Zürich; with Hans Kramers and Adriaan Fokker in Holland; with Heisenberg on ferromagnetism, where he developed a description of boundaries between magnetic domains, now known as "Bloch walls", and theoretically proposed a concept of spin waves, excitations of magnetic structure; with Niels Bohr in Copenhagen, where he worked on a theoretical description of the stopping of charged particles traveling through matter; and with Enrico Fermi in Rome. In 1932, Bloch returned to Leipzig to assume a position as "Privatdozent" (lecturer). In 1933, immediately after Hitler came to power, he left Germany because he was Jewish, returning to Zürich, before traveling to Paris to lecture at the Institut Henri Poincaré.
In 1934, the chairman of Stanford Physics invited Bloch to join the faculty. Bloch accepted the offer and emigrated to the United States. In the fall of 1938, Bloch began working with the 37 inch cyclotron at the University of California, Berkeley to determine the magnetic moment of the neutron. Bloch went on to become the first professor for theoretical physics at Stanford. In 1939, he became a naturalized citizen of the United States.
During WWII, Bloch briefly worked on the atomic bomb project at Los Alamos. Disliking the military atmosphere of the laboratory and uninterested in the theoretical work there, Bloch left to join the radar project at Harvard University.
After the war, he concentrated on investigations into nuclear induction and nuclear magnetic resonance, which are the underlying principles of MRI. In 1946 he proposed the Bloch equations which determine the time evolution of nuclear magnetization. He was elected to the United States National Academy of Sciences in 1948. Along with Edward Purcell, Bloch was awarded the 1952 Nobel Prize in Physics for his work on nuclear magnetic induction.
When CERN was being set up in the early 1950s, its founders were searching for someone of stature and international prestige to head the fledgling international laboratory, and in 1954 Professor Bloch became CERN's first director-general, at the time when construction was getting under way on the present Meyrin site and plans for the first machines were being drawn up. After leaving CERN, he returned to Stanford University, where he in 1961 was made Max Stein Professor of Physics.
In 1964, he was elected a foreign member of the Royal Netherlands Academy of Arts and Sciences. He was also a member of the American Academy of Arts and Sciences and the American Philosophical Society.
Bloch died in Zürich in 1983. | 0 | Theoretical and Fundamental Chemistry |
Barium chlorate can be produced through a double replacement reaction between solutions of barium chloride and sodium chlorate:
:BaCl + 2 NaClO → Ba(ClO) + 2 NaCl
On concentrating and chilling the resulting mixture, barium chlorate precipitates. This is perhaps the most common preparation, exploiting the lower solubility of barium chlorate compared to sodium chlorate.
The above method does result in some sodium contamination, which is undesirable for pyrotechnic purposes, where the strong yellow of sodium can easily overpower the green of barium. Sodium-free barium chlorate can be produced directly through electrolysis:
:BaCl + 6 HO → Ba(ClO) + 6 H
It can also be produced by the reaction of barium carbonate with boiling ammonium chlorate solution:
:2 NHClO + BaCO + Q → Ba(ClO) + 2 NH + HO + CO
The reaction initially produces barium chlorate and ammonium carbonate; boiling the solution decomposes the ammonium carbonate and drives off the resulting ammonia and carbon dioxide, leaving only barium chlorate in solution. | 0 | Theoretical and Fundamental Chemistry |
A structurally complete leaf of an angiosperm consists of a petiole (leaf stalk), a lamina (leaf blade), stipules (small structures located to either side of the base of the petiole) and a sheath. Not every species produces leaves with all of these structural components. The proximal stalk or petiole is called a stipe in ferns. The lamina is the expanded, flat component of the leaf which contains the chloroplasts. The sheath is a structure, typically at the base that fully or partially clasps the stem above the node, where the leaf is attached. Leaf sheathes typically occur in Poaceae (grasses) and Apiaceae (umbellifers). Between the sheath and the lamina, there may be a pseudopetiole, a petiole like structure. Pseudopetioles occur in some monocotyledons including bananas, palms and bamboos. Stipules may be conspicuous (e.g. beans and roses), soon falling or otherwise not obvious as in Moraceae or absent altogether as in the Magnoliaceae. A petiole may be absent (apetiolate), or the blade may not be laminar (flattened). The petiole mechanically links the leaf to the plant and provides the route for transfer of water and sugars to and from the leaf. The lamina is typically the location of the majority of photosynthesis. The upper (adaxial) angle between a leaf and a stem is known as the axil of the leaf. It is often the location of a bud. Structures located there are called "axillary".
External leaf characteristics, such as shape, margin, hairs, the petiole, and the presence of stipules and glands, are frequently important for identifying plants to family, genus or species levels, and botanists have developed a rich terminology for describing leaf characteristics. Leaves almost always have determinate growth. They grow to a specific pattern and shape and then stop. Other plant parts like stems or roots have non-determinate growth, and will usually continue to grow as long as they have the resources to do so.
The type of leaf is usually characteristic of a species (monomorphic), although some species produce more than one type of leaf (dimorphic or polymorphic). The longest leaves are those of the Raffia palm, R. regalis which may be up to long and wide. The terminology associated with the description of leaf morphology is presented, in illustrated form, at Wikibooks.
Where leaves are basal, and lie on the ground, they are referred to as prostrate. | 0 | Theoretical and Fundamental Chemistry |
Adenosine triphosphate (ATP) is a nucleotide that provides energy to drive and support many processes in living cells, such as muscle contraction, nerve impulse propagation, condensate dissolution, and chemical synthesis. Found in all known forms of life, it is often referred to as the "molecular unit of currency" of intracellular energy transfer.
When consumed in a metabolic processes, ATP converts either to adenosine diphosphate (ADP) or to adenosine monophosphate (AMP). Other processes regenerate ATP. It is also a precursor to DNA and RNA, and is used as a coenzyme. An average human adult processes around 50 kilograms daily.
From the perspective of biochemistry, ATP is classified as a nucleoside triphosphate, which indicates that it consists of three components: a nitrogenous base (adenine), the sugar ribose, and the triphosphate. | 1 | Applied and Interdisciplinary Chemistry |
The decline of European alchemy was brought about by the rise of modern science with its emphasis on rigorous quantitative experimentation and its disdain for "ancient wisdom". Although the seeds of these events were planted as early as the 17th century, alchemy still flourished for some two hundred years, and in fact may have reached its peak in the 18th century. As late as 1781 James Price claimed to have produced a powder that could transmute mercury into silver or gold. Early modern European alchemy continued to exhibit a diversity of theories, practices, and purposes: "Scholastic and anti-Aristotelian, Paracelsian and anti-Paracelsian, Hermetic, Neoplatonic, mechanistic, vitalistic, and more—plus virtually every combination and compromise thereof."
Robert Boyle (1627–1691) pioneered the scientific method in chemical investigations. He assumed nothing in his experiments and compiled every piece of relevant data. Boyle would note the place in which the experiment was carried out, the wind characteristics, the position of the Sun and Moon, and the barometer reading, all just in case they proved to be relevant. This approach eventually led to the founding of modern chemistry in the 18th and 19th centuries, based on revolutionary discoveries and ideas of Lavoisier and John Dalton.
Beginning around 1720, a rigid distinction began to be drawn for the first time between "alchemy" and "chemistry". By the 1740s, "alchemy" was now restricted to the realm of gold making, leading to the popular belief that alchemists were charlatans, and the tradition itself nothing more than a fraud. In order to protect the developing science of modern chemistry from the negative censure to which alchemy was being subjected, academic writers during the 18th-century scientific Enlightenment attempted to divorce and separate the "new" chemistry from the "old" practices of alchemy. This move was mostly successful, and the consequences of this continued into the 19th, 20th and 21st centuries.
During the occult revival of the early 19th century, alchemy received new attention as an occult science. The esoteric or occultist school that arose during the 19th century held the view that the substances and operations mentioned in alchemical literature are to be interpreted in a spiritual sense, less than as a practical tradition or protoscience. This interpretation claimed that the obscure language of the alchemical texts, which 19th century practitioners were not always able to decipher, were an allegorical guise for spiritual, moral or mystical processes.
Two seminal figures during this period were Mary Anne Atwood and Ethan Allen Hitchcock, who independently published similar works regarding spiritual alchemy. Both rebuffed the growing successes of chemistry, developing a completely esoteric view of alchemy. Atwood wrote: "No modern art or chemistry, notwithstanding all its surreptitious claims, has any thing in common with Alchemy." Atwoods work influenced subsequent authors of the occult revival including Eliphas Levi, Arthur Edward Waite, and Rudolf Steiner. Hitchcock, in his Remarks Upon Alchymists' (1855) attempted to make a case for his spiritual interpretation with his claim that the alchemists wrote about a spiritual discipline under a materialistic guise in order to avoid accusations of blasphemy from the church and state. In 1845, Baron Carl Reichenbach, published his studies on Odic force, a concept with some similarities to alchemy, but his research did not enter the mainstream of scientific discussion.
In 1946, Louis Cattiaux published the Message Retrouvé, a work that was at once philosophical, mystical and highly influenced by alchemy. In his lineage, many researchers, including Emmanuel and Charles d'Hooghvorst, are updating alchemical studies in France and Belgium. | 1 | Applied and Interdisciplinary Chemistry |
The ability of a soapy solution to act as a detergent has been recognized for centuries. However, it was only at the beginning of the twentieth century that the constitution of such solutions was scientifically studied. Pioneering work in this area was carried out by James William McBain at the University of Bristol. As early as 1913, he postulated the existence of "colloidal ions" to explain the good electrolytic conductivity of sodium palmitate solutions. These highly mobile, spontaneously formed clusters came to be called micelles, a term borrowed from biology and popularized by G.S. Hartley in his classic book Paraffin Chain Salts: A Study in Micelle Formation. The term micelle was coined in nineteenth century scientific literature as the elle diminutive of the Latin word (particle), conveying a new word for "tiny particle". | 0 | Theoretical and Fundamental Chemistry |
, along with many substituted derivatives like the alkoxy-methyl derivative , can be deposited as a thin film with intrinsic semiconductor properties; said properties arise due to its radical nature and its low reduction potential compared to other metal phthalocyanines. This initially green film exhibits electrochromism; the oxidized form is red, whereas the reduced form is blue and the next two reduced forms are dark blue and violet, respectively. The green/red oxidation cycle can be repeated over 10,000 times in aqueous solution with dissolved alkali metal halides, before it is degraded by hydroxide ions; the green/blue redox degrades faster in water. | 0 | Theoretical and Fundamental Chemistry |
The iron pillar of Dhar was originally longer than the iron pillar of Delhi. After the Muslim conquest of Dhar, it broke into at least two pieces. The smaller piece was planted at the Dilawar Khan's Mosque in Mandu. The larger piece was erected in front of the Lat Masjid constructed by Dilawar Khan in 1405.
In 1531 CE, Dhar came under the control of Bahadur Shah, the Sultan of Gujarat. He made an attempt to carry the large piece to Gujarat. In this process, this part of the pillar toppled and fragmented into two pieces.
Now, three fragments of the pillar are placed horizontally on a platform near Lat Masjid. These fragments were moved by ASI to their present position in 1980. The combined height of the three fragments is , and their total weight is estimated at . Thus, the original pillar must have been almost twice as high and at least heavier than the iron pillar of Delhi. At the time of its erection, it was probably the tallest and the largest forge-welded iron pillar in the world. | 1 | Applied and Interdisciplinary Chemistry |
The technical merits make redox flow batteries a well-suited option for large-scale energy storage. Flow batteries are normally considered for relatively large (1 kWh – 10 MWh) stationary applications with multi-hour charge-discharge cycles. Flow batteries are not cost-efficient for shorter charge/discharge times. Some examples of flow battery market niches are:
* Grid energy storage - short and/or long-term energy storage for use by the grid
** Load balancing – where the battery is attached to an electrical grid to store excess electrical power during off-peak hours and release electrical power during peak demand periods. The common problem limiting the use of most flow battery chemistries in this application is their low areal power (operating current density) which translates into a high cost of power.
** Shifting energy from intermittent sources such as wind or solar for use during periods of peak demand.
** Peak shaving, where spikes of demand are met by the battery.
* UPS, where the battery is used if the main power fails to provide an uninterrupted supply.
* Power conversion – Because all cells share the same electrolyte(s), the electrolytes may be charged using a given number of cells and discharged with a different number. As battery voltage is proportional to the number of cells used the battery can therefore act as a very powerful DC–DC converter. In addition, if the number of cells is continuously changed (on the input and/or output side) power conversion can also be AC/DC, AC/AC, or DC–AC with the frequency limited by that of the switching gear.
* Electric vehicles – Because flow batteries can be rapidly "recharged" by replacing the electrolyte, they can be used for applications where the vehicle needs to take on energy as fast as a combustion engined vehicle. A common problem found with most RFB chemistries in the EV applications is their low energy density which translated into a short driving range. Zinc-chlorine batteries and batteries with highly soluble halates are a notable exception.
* Stand-alone power system – An example of this is in cellphone base stations where no grid power is available. The battery can be used alongside solar or wind power sources to compensate for their fluctuating power levels and alongside a generator to make the most efficient use of it to save fuel. | 0 | Theoretical and Fundamental Chemistry |
Metalloprotein is a generic term for a protein that contains a metal ion cofactor. A large proportion of all proteins are part of this category. For instance, at least 1000 human proteins (out of ~20,000) contain zinc-binding protein domains although there may be up to 3000 human zinc metalloproteins. | 1 | Applied and Interdisciplinary Chemistry |
Cyanobacteria possess carboxysomes, which increase the concentration of around RuBisCO to increase the rate of photosynthesis. An enzyme, carbonic anhydrase, located within the carboxysome, releases CO from dissolved hydrocarbonate ions (HCO). Before the CO can diffuse out outside the cell by another carbonic anhydrase and are actively pumped into the cell by a membrane protein. They cannot cross the membrane as they are charged, and within the cytosol they turn back into CO very slowly without the help of carbonic anhydrase. This causes the HCO ions to accumulate within the cell from where they diffuse into the carboxysomes. Pyrenoids in algae and hornworts also act to concentrate around RuBisCO. | 0 | Theoretical and Fundamental Chemistry |
The Bottom-blown Oxygen Converter or BBOC is a smelting furnace developed by the staff at Britannia Refined Metals Limited (“BRM”), a British subsidiary of MIM Holdings Limited (which is now part of the Glencore group of companies). The furnace is currently marketed by Glencore Technology. It is a sealed, flat-bottomed furnace mounted on a tilting frame that is used in the recovery of precious metals. A key feature is the use of a shrouded lance to inject oxygen through the bottom of the furnace, directly into the precious metals contained in the furnace, to oxidize base metals or other impurities as part of their removal as slag. | 1 | Applied and Interdisciplinary Chemistry |
An electron transport chain (ETC) is a series of protein complexes and other molecules that transfer electrons from electron donors to electron acceptors via redox reactions (both reduction and oxidation occurring simultaneously) and couples this electron transfer with the transfer of protons (H ions) across a membrane. Many of the enzymes in the electron transport chain are embedded within the membrane.
The flow of electrons through the electron transport chain is an exergonic process. The energy from the redox reactions creates an electrochemical proton gradient that drives the synthesis of adenosine triphosphate (ATP). In aerobic respiration, the flow of electrons terminates with molecular oxygen as the final electron acceptor. In anaerobic respiration, other electron acceptors are used, such as sulfate.
In an electron transport chain, the redox reactions are driven by the difference in the Gibbs free energy of reactants and products. The free energy released when a higher-energy electron donor and acceptor convert to lower-energy products, while electrons are transferred from a lower to a higher redox potential, is used by the complexes in the electron transport chain to create an electrochemical gradient of ions. It is this electrochemical gradient that drives the synthesis of ATP via coupling with oxidative phosphorylation with ATP synthase.
In eukaryotic organisms, the electron transport chain, and site of oxidative phosphorylation, is found on the inner mitochondrial membrane. The energy released by reactions of oxygen and reduced compounds such as cytochrome c and (indirectly) NADH and FADH2 is used by the electron transport chain to pump protons into the intermembrane space, generating the electrochemical gradient over the inner mitochondrial membrane. In photosynthetic eukaryotes, the electron transport chain is found on the thylakoid membrane. Here, light energy drives electron transport through a proton pump and the resulting proton gradient causes subsequent synthesis of ATP. In bacteria, the electron transport chain can vary between species but it always constitutes a set of redox reactions that are coupled to the synthesis of ATP through the generation of an electrochemical gradient and oxidative phosphorylation through ATP synthase. | 1 | Applied and Interdisciplinary Chemistry |
The unit processes involved in wastewater treatment include physical processes such as settlement or flotation and biological processes such oxidation or anaerobic treatment. Some wastewaters require specialized treatment methods. At the simplest level, treatment of most wastewaters is carried out through separation of solids from liquids, usually by sedimentation. By progressively converting dissolved material into solids, usually a biological floc or biofilm, which is then settled out or separated, an effluent stream of increasing purity is produced. | 1 | Applied and Interdisciplinary Chemistry |
A proper rotation refers to simple rotation about an axis. Such operations are denoted by where is a rotation of or performed times. The superscript is omitted if it is equal to one. is a rotation through 360°, where . It is equivalent to the Identity () operation. is a rotation of 180°, as is a rotation of 120°, as and so on.
Here the molecule can be rotated into equivalent positions around an axis. An example of a molecule with symmetry is the water () molecule. If the molecule is rotated by 180° about an axis passing through the oxygen atom, no detectable difference before and after the operation is observed.
Order of an axis can be regarded as a number of times that, for the least rotation which gives an equivalent configuration, that rotation must be repeated to give a configuration identical to the original structure (i.e. a 360° or 2 rotation). An example of this is proper rotation, which rotates by represents the first rotation around the axis by is the rotation by while is the rotation by is the identical configuration because it gives the original structure, and it is called an identity element (). Therefore, is an order of three, and is often referred to as a threefold axis. | 0 | Theoretical and Fundamental Chemistry |
There are a total of four classes that categorize Histone Deacetylases (HDACs). Class I includes HDACs 1, 2, 3, and 8. Class II is divided into two subgroups, Class IIA and Class IIB. Class IIA includes HDACs 4, 5, 7, and 9 while Class IIB includes HDACs 6 and 10. Class III contains the Sirtuins and Class IV contains only HDAC11. Classes of HDAC proteins are divided and grouped together based on the comparison to the sequence homologies of Rpd3, Hos1 and Hos2 for Class I HDACs, HDA1 and Hos3 for the Class II HDACs and the sirtuins for Class III HDACs. | 0 | Theoretical and Fundamental Chemistry |
Voyager 1 and Voyager 2 spacecraft launched in August and September 1977 required multi-hundred-watt (MHW) RTG containing plutonium oxide fuel spheres for an operational life appropriate for exploration of Jupiter, Saturn, Uranus, and Neptune. Conversion of the decay heat of the plutonium to electrical power was accomplished through 312 silicon-germanium (SiGe) thermoelectric couples. A hot junction temperature of 1273 K (1832 °F) with a cold junction temperature of 573 K (572 °F) compose the temperature gradient in the thermoelectric couple in the RTG. This mechanism provided the total electrical power to operate the spacecrafts instruments, communications and other power demands. The RTG on Voyager will produce adequate electrical power for spacecraft operation until about the year 2020. Similar MHW-RTG models are also used on the two U.S. Air Force communications Lincoln Experimental Satellites 8 and 9 (LES-8/9'). | 0 | Theoretical and Fundamental Chemistry |
The duration of adjustment depends on the strength of the negative feedback to the initial shock. The principle is typically used to describe closed negative-feedback systems, but applies, in general, to thermodynamically closed and isolated systems in nature, since the second law of thermodynamics ensures that the disequilibrium caused by an instantaneous shock is eventually followed by a new equilibrium.
While well rooted in chemical equilibrium, Le Chateliers principle can also be used in describing mechanical systems in that a system put under stress will respond in such a way as to reduce or minimize that stress. Moreover, the response will generally be via the mechanism that most easily relieves that stress. Shear pins and other such sacrificial devices are design elements that protect systems against stress applied in undesired manners to relieve it so as to prevent more extensive damage to the entire system, a practical engineering application of Le Chateliers principle. | 0 | Theoretical and Fundamental Chemistry |
Thermodynamics defines the statistical behaviour of large numbers of entities, whose exact behavior is given by more specific laws. While the fundamental theoretical laws of physics are all time-reversible, experimentally the probability of real reversibility is low and the former state of system and surroundings is recovered only to certain extent (see: uncertainty principle). The reversibility of thermodynamics must be statistical in nature; that is, it must be merely highly unlikely, but not impossible, that a system will lower in entropy. In other words, time reversibility is fulfilled if the process happens the same way if time were to flow in reverse or the order of states in the process is reversed (the last state becomes the first and vice versa). | 0 | Theoretical and Fundamental Chemistry |
Resistance to fluoroquinolones is common in staphylococcus and pseudomonas. Resistance occurs in multiple ways. One mechanism is by an alteration in topoisomerase IV enzyme. A double mutant form of S. pneumoniae Gyr A + Par C bearing Ser-81-->Phe and Ser-79-->Phe mutations were eight to sixteen times less responsive to ciprofloxacin. | 0 | Theoretical and Fundamental Chemistry |
Recent developments in heterogeneous catalysis enabled the use of metal oxide materials such as cuprous oxide nanocatalysts in flow processing technologies, which can enable the economical production of active pharmaceutical ingredients and various other fine chemicals. | 0 | Theoretical and Fundamental Chemistry |
As a "non-contact" process, the effect differs from traditional electrochemical processes where carrier flow through the surface is achieved by connection to a current source with highly conductive materials such as copper wire. It is well known that materials contacted to an anode can be modified in a variety of ways including anodizing and electropolishing. Electrochemistry was quickly recognized as an important related field in the popular press once the first synthetic diamonds were made. However, the use of an induced field created by remote electrodes allows discontinuous areas on an insulating substrate to be cleaned, modified, or etched (similar to electroetching), greatly expanding the role of electrochemical methods.
The mechanism is presumed to be due to the induced field but little in the way of exhaustive analysis has been done, as the actual processes do not appear to differ from traditional approaches. For example, "identified as the ‘Marchywka Effect’ in the literature. The etching may be due to the galvanic coupling of diamond and non-diamond carbon". The applied field apparently creates directed surface modifications on polished diamond surfaces with little or no actual removal of material. This may be desirable for making various devices, or simply studying the properties of the diamond surface. The induced field deposits or replaces a single layer of some molecule and this could be thought of as a monolayer electroplating method. It has been elucidated in more fully in many works. | 0 | Theoretical and Fundamental Chemistry |
As the concentration of particles in a suspension is increased, a point is reached where particles are so close together that they no longer settle independently of one another and the velocity fields of the fluid displaced by adjacent particles, overlap. There is also a net upward flow of liquid displaced by the settling particles. This results in a reduced particle-settling velocity and the effect is known as hindered settling.
There is a common case for hindered settling occurs. the whole suspension tends to settle as a ‘blanket’ due to its extremely high particle concentration. This is known as zone settling, because it is easy to make a distinction between several different zones which separated by concentration discontinuities. Fig. 3 represents a typical batch-settling column tests on a suspension exhibiting zone-settling characteristics. There is a clear interface near the top of the column would be formed to separating the settling sludge mass from the clarified supernatant as long as leaving such a suspension to stand in a settling column. As the suspension settles, this interface will move down at the same speed. At the same time, there is an interface near the bottom between that settled suspension and the suspended blanket. After settling of suspension is complete, the bottom interface would move upwards and meet the top interface which moves downwards. | 0 | Theoretical and Fundamental Chemistry |
Concretes are produced from natural plant materials—mainly flowers. Some of the most popular natural flowers used are rose, lavender, jasmine, tuberose, jonquil, and ylang-ylang. | 0 | Theoretical and Fundamental Chemistry |
The solution been used in veterinary medicine to treat chronic diseases of the skin and as a folk remedy. It was used during the 19th century to treat lepra vulgaris and psoriasis in humans, taken internally. | 0 | Theoretical and Fundamental Chemistry |
HTIR-TC offers a breakthrough in measuring high-temperature processes. Its characteristics are: durable and reliable at high temperatures, up to at least 1700 °C; resistant to irradiation; moderately priced; available in a variety of configurations - adaptable to each application; easily installed. Originally developed for use in nuclear test reactors, HTIR-TC may enhance the safety of operations in future reactors. This thermocouple was developed by researchers at the Idaho National Laboratory (INL). | 1 | Applied and Interdisciplinary Chemistry |
Eastern meadow voles are active year-round and day or night, with no clear 24-hour rhythm in many areas. Most changes in activity are imposed by season, habitat, cover, temperature, and other factors. Eastern meadow voles have to eat frequently, and their active periods (every two to three hours) are associated with food digestion. In Canada, eastern meadow voles are active the first few hours after dawn and during the two- to four-hour period before sunset. Most of the inactive period is spent in the nest. | 1 | Applied and Interdisciplinary Chemistry |
Thermodynamic diagrams are diagrams used to represent the thermodynamic states of a material (typically fluid) and the consequences of manipulating this material. For instance, a temperature–entropy diagram (T–s diagram) may be used to demonstrate the behavior of a fluid as it is changed by a compressor. | 0 | Theoretical and Fundamental Chemistry |
In the 9th century, Banū Mūsā brothers Book of Ingenious Devices' described a number of early automatic controls in fluid mechanics. Two-step level controls for fluids, an early form of discontinuous variable structure controls, was developed by the Banu Musa brothers. They also described an early feedback controller for fluids. According to Donald Routledge Hill, the Banu Musa brothers were "masters in the exploitation of small variations" in hydrostatic pressures and in using conical valves as "in-line" components in flow systems, "the first known use of conical valves as automatic controllers." They also described the use of other valves, including a plug valve, float valve and tap. The Banu Musa also developed an early fail-safe system where "one can withdraw small quantities of liquid repeatedly, but if one withdraws a large quantity, no further extractions are possible." The double-concentric siphon and the funnel with bent end for pouring in different liquids, neither of which appear in any earlier Greek works, were also original inventions by the Banu Musa brothers. Some of the other mechanisms they described include a float chamber and an early differential pressure.
In 1206, Al-Jazaris Book of Knowledge of Ingenious Mechanical Devices described many hydraulic machines. Of particular importance were his water-raising pumps. The first known use of a crankshaft in a chain pump was in one of al-Jazaris saqiya machines. The concept of minimizing intermittent working is also first implied in one of al-Jazari's saqiya chain pumps, which was for the purpose of maximising the efficiency of the saqiya chain pump. Al-Jazari also invented a twin-cylinder reciprocating piston suction pump, which included the first suction pipes, suction pumping, double-action pumping, and made early uses of valves and a crankshaft-connecting rod mechanism. This pump is remarkable for three reasons: the first known use of a true suction pipe (which sucks fluids into a partial vacuum) in a pump, the first application of the double-acting principle, and the conversion of rotary to reciprocating motion, via the crankshaft-connecting rod mechanism. | 1 | Applied and Interdisciplinary Chemistry |
A quark–gluon plasma (QGP) or quark soup is a state of matter in quantum chromodynamics (QCD) which exists at extremely high temperature and/or density. This state is thought to consist of asymptotically free strong-interacting quarks and gluons, which are ordinarily confined by color confinement inside atomic nuclei or other hadrons. This is in analogy with the conventional plasma where nuclei and electrons, confined inside atoms by electrostatic forces at ambient conditions, can move freely. Experiments to create artificial quark matter started at CERN in 1986/87, resulting in first claims that were published in 1991. It took several years before the idea became accepted in the community of particle and nuclear physicists. Formation of a new state of matter in Pb–Pb collisions was officially announced at CERN in view of the convincing experimental results presented by the CERN SPS WA97 experiment in 1999, and later elaborated by Brookhaven National Laboratory's Relativistic Heavy Ion Collider. Quark matter can only be produced in minute quantities and is unstable and impossible to contain, and will radioactively decay within a fraction of a second into stable particles through hadronization; the produced hadrons or their decay products and gamma rays can then be detected. In the quark matter phase diagram, QGP is placed in the high-temperature, high-density regime, whereas ordinary matter is a cold and rarefied mixture of nuclei and vacuum, and the hypothetical quark stars would consist of relatively cold, but dense quark matter. It is believed that up to a few microseconds (10 to 10 seconds) after the Big Bang, known as the quark epoch, the Universe was in a quark–gluon plasma state.
The strength of the color force means that unlike the gas-like plasma, quark–gluon plasma behaves as a near-ideal Fermi liquid, although research on flow characteristics is ongoing. Liquid or even near-perfect liquid flow with almost no frictional resistance or viscosity was claimed by research teams at RHIC and LHC's Compact Muon Solenoid detector. QGP differs from a "free" collision event by several features; for example, its particle content is indicative of a temporary chemical equilibrium producing an excess of middle-energy strange quarks vs. a nonequilibrium distribution mixing light and heavy quarks ("strangeness production"), and it does not allow particle jets to pass through ("jet quenching").
Experiments at CERNs Super Proton Synchrotron (SPS) begun experiments to create QGP in the 1980s and 1990s: the results led CERN to announce evidence for a "new state of matter" in 2000. Scientists at Brookhaven National Laboratorys Relativistic Heavy Ion Collider announced they had created quark–gluon plasma by colliding gold ions at nearly the speed of light, reaching temperatures of 4 trillion degrees Celsius. Current experiments (2017) at the Brookhaven National Laboratorys Relativistic Heavy Ion Collider (RHIC) on Long Island (New York, USA) and at CERNs recent Large Hadron Collider near Geneva (Switzerland) are continuing this effort, by colliding relativistically accelerated gold and other ion species (at RHIC) or lead (at LHC) with each other or with protons. Three experiments running on CERN's Large Hadron Collider (LHC), on the spectrometers ALICE, ATLAS and CMS, have continued studying the properties of QGP. CERN temporarily ceased colliding protons, and began colliding lead ions for the ALICE experiment in 2011, in order to create a QGP. A new record breaking temperature was set by ALICE: A Large Ion Collider Experiment at CERN in August 2012 in the ranges of 5.5 trillion () kelvin as claimed in their Nature PR.
The formation of a quark–gluon plasma occurs as a result of a strong interaction between the partons (quarks, gluons) that make up the nucleons of the colliding heavy nuclei called heavy ions. Therefore, experiments are referred to as relativistic heavy ion collision experiments. Theoretical and experimental works show that the formation of a quark–gluon plasma occurs at the temperature of T ≈ 150–160 MeV, the Hagedorn temperature, and an energy density of ≈ 0.4–1 GeV / fm. While at first a phase transition was expected, present day theoretical interpretations propose a phase transformation similar to the process of ionisation of normal matter into ionic and electron plasma. | 0 | Theoretical and Fundamental Chemistry |
Various polysulfides - are components of liver of sulfur. Polysulfides, like sulfides, can induce stress corrosion cracking in carbon steel and stainless steel. | 0 | Theoretical and Fundamental Chemistry |
Actinic lights are also common in the reef aquarium industry. They are used to promote coral and invertebrate growth. They are also used to accentuate the fluorescence of fluorescent fish.
Actinic lighting is also used to limit algae growth in the aquarium. Since algae (like many other plants), flourish in shallower warm water, algae cannot effectively photosynthesize from blue and violet light, thus actinic light minimizes its photosynthetic benefit.
Actinic lighting is also a great alternative to black lights as it provides a "night environment" for the fish, while still allowing enough light for coral and other marine life to grow. Aesthetically, they make fluorescent coral "pop" to the eye, but in some cases also to promote the growth of deeper-water coral adapted to photosynthesis in regions of the ocean dominated by blue light. | 0 | Theoretical and Fundamental Chemistry |
The Institute had its genesis in 1893 with the formation in Adelaide of the Australasian Institute of Mining Engineers drawing its inspiration from the success of the American Institute of Mining Engineers, and some impetus from the Mine Managers Association of Broken Hill. Office-holders were equally from South Australia and "The Hill", where the Institute established its headquarters.
This approach to the foundation of a federal organization was welcomed in mining districts of other Australian colonies. and branches were formed in Broken Hill, the Thames Goldfield (New Zealand), Ballarat, and elsewhere. Succeeding annual conferences were held at Ballarat, Hobart, Broken Hill and other mining centres. The 1926 conference was held in Otago, New Zealand.
In 1896 its headquarters were removed from Broken Hill to Melbourne, and in June 1919 adopted its present name.
In 1954 the institute applied for a royal charter, granted 1955.
The AusIMM represents more than 15 500 members drawn from all sections of the industry and supported by a network of branches and societies in Australasia and internationally. | 1 | Applied and Interdisciplinary Chemistry |
The International Energy Agency reports the following typical higher heating values per Standard cubic metre of gas:
* Algeria: 39.57MJ/Sm
* Bangladesh: 36.00MJ/Sm
* Canada: 39.00MJ/Sm
* China: 38.93MJ/Sm
* Indonesia: 40.60MJ/Sm
* Iran: 39.36MJ/Sm
* Netherlands: 33.32MJ/Sm
* Norway: 39.24MJ/Sm
* Pakistan: 34.90MJ/Sm
* Qatar: 41.40MJ/Sm
* Russia: 38.23MJ/Sm
* Saudi Arabia: 38.00MJ/Sm
* Turkmenistan: 37.89MJ/Sm
* United Kingdom: 39.71MJ/Sm
* United States: 38.42MJ/Sm
* Uzbekistan: 37.89MJ/Sm
The lower heating value of natural gas is normally about 90% of its higher heating value. This table is in Standard cubic metres (1atm, 15°C), to convert to values per Normal cubic metre (1atm, 0°C), multiply above table by 1.0549. | 0 | Theoretical and Fundamental Chemistry |
The dominant material for contact lenses are acrylate-siloxane hydrogels. They have replaced hard contact lenses. One of their most attractive properties is oxygen permeability, which is required since the cornea lacks vasculature. | 0 | Theoretical and Fundamental Chemistry |
The polar surface area (PSA) or topological polar surface area (TPSA) of a molecule is defined as the surface sum over all polar atoms or molecules, primarily oxygen and nitrogen, also including their attached hydrogen atoms.
PSA is a commonly used medicinal chemistry metric for the optimization of a drug's ability to permeate cells. Molecules with a polar surface area of greater than 140 angstroms squared (Å) tend to be poor at permeating cell membranes. For molecules to penetrate the blood–brain barrier (and thus act on receptors in the central nervous system), a PSA less than 90 Å is usually needed.
TPSA is a valuable tool in drug discovery and development. By analyzing a drug candidates TPSA, scientists can predict its potential for oral bioavailability and ability to reach target sites within the body. This prediction hinges on a drugs ability to permeate biological barriers.
Permeating these barriers, such as the Blood-Brain Barrier (BBB), the Placental Barrier (PB), and the Blood-Mammary Barrier (BM), is crucial for many drugs to reach their intended targets.
The BBB, for example, protects the brain from harmful substances. Drugs with a lower TPSA (generally below 90 Ų) tend to permeate the BBB more easily, allowing them to reach the brain and exert their therapeutic effects (Shityakov et al., 2013).
Similarly, for drugs intended to treat the fetus, a lower TPSA (below 60 Ų) is preferred to ensure they can pass through the placenta (Augustiño-Roubina et al., 2019).
Breastfeeding mothers also need consideration. Here, an optimal TPSA for a drug is around 60-80 Ų to allow it to reach the breast tissue for milk production, while drugs exceeding 90 Ų are less likely to permeate the Blood-Mammary Barrier. | 1 | Applied and Interdisciplinary Chemistry |
In 2021, calcium was the 243rd most commonly prescribed medication in the United States, with more than 1million prescriptions. | 1 | Applied and Interdisciplinary Chemistry |
One model proposes that loss of the GTP-cap causes the GDP-containing protofilaments to shrink. Based on this GTP-cap model, catastrophe happens randomly. The model proposes that an increase in microtubule growth will correlate with a decrease in random catastrophe frequency or vice versa. The discovery of microtubule-associated proteins that change the rate of catastrophe while not impacting the rate of microtubule growth challenges this model of stochastic growth and shrinkage. | 1 | Applied and Interdisciplinary Chemistry |
Post-translational modification is the chemical modification of a protein after its translation. It is one of the later steps in protein biosynthesis for many proteins. | 1 | Applied and Interdisciplinary Chemistry |
Spatially resolve acoustic spectroscopy (SRAS) is an optical technique that uses optically generated high frequency surface acoustic waves to probe
the direction elastic parameters of the surface and, as such, it can vividly reveal the surface microstructure of metals.
It can also image the crystallographic orientation and determine the single crystal elasticity matrix of the material. | 1 | Applied and Interdisciplinary Chemistry |
The Dortmund Data Bank is distributed by DDBST GmbH as in-house software. Many parts of the Dortmund Data Bank are also distributed as part of the DETHERM data bank which is also available online. | 0 | Theoretical and Fundamental Chemistry |
Salmonella encodes a LuxR homolog, SdiA, but does not encode an AHL synthase. SdiA detects AHLs produced by other species of bacteria including Aeromonas hydrophila, Hafnia alvei, and Yersinia enterocolitica. When AHL is detected, SdiA regulates the rck operon on the Salmonella virulence plasmid (pefI-srgD-srgA-srgB-rck-srgC) and a single gene horizontal acquisition in the chromosome srgE. Salmonella does not detect AHL when passing through the gastrointestinal tracts of several animal species, suggesting that the normal microbiota does not produce AHLs. However, SdiA does become activated when Salmonella transits through turtles colonized with Aeromonas hydrophila or mice infected with Yersinia enterocolitica. Therefore, Salmonella appears to use SdiA to detect the AHL production of other pathogens rather than the normal gut flora. | 1 | Applied and Interdisciplinary Chemistry |
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