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Pepper spray There are also pepper spray projectiles available, which can be fired from a paintball gun. It has been used for years against demonstrators. Many such canisters also contain dyes, either visible or UV-reactive, to mark an attacker's skin or clothing to enhance identification by police. is banned for use i... | https://en.wikipedia.org/wiki?curid=157302 |
Pepper spray Any similar canister with the labels reading "dog spray" or "bear spray" is regulated under the "Pest Control Products Act"—while legal to be carried by anyone, it is against the law if its use causes "a risk of imminent death or serious bodily harm to another person" or harming the environment and carries... | https://en.wikipedia.org/wiki?curid=157302 |
Pepper spray Before that law, pepper spray was controlled by the Army and could only be used by security forces. In June 2002, West Australian resident Rob Hall was convicted for using a canister of pepper spray to break up an altercation between two guests at his home in Midland. Despite being sentenced to a good beha... | https://en.wikipedia.org/wiki?curid=157302 |
Electrochemical potential In electrochemistry, the electrochemical potential (ECP), "", is a thermodynamic measure of chemical potential that does not omit the energy contribution of electrostatics. is expressed in the unit of J/mol. Each chemical species (for example, "water molecules", "sodium ions", "electrons", etc... | https://en.wikipedia.org/wiki?curid=157620 |
Electrochemical potential These two examples show that an electrical potential and a chemical potential can both give the same result: A redistribution of the chemical species. Therefore, it makes sense to combine them into a single "potential", the "electrochemical potential", which can directly give the "net" redistr... | https://en.wikipedia.org/wiki?curid=157620 |
Electrochemical potential This energy, which can sometimes be harnessed (a simple example is a concentration cell), and the free-energy per mole is exactly equal to the electrochemical potential difference between the two regions. It is common in electrochemistry and solid-state physics to discuss both the chemical pot... | https://en.wikipedia.org/wiki?curid=157620 |
Electrochemical potential is important in biological processes that involve molecular diffusion across membranes, in electroanalytical chemistry, and industrial applications such as batteries and fuel cells. It represents one of the many interchangeable forms of potential energy through which energy may be conserved. I... | https://en.wikipedia.org/wiki?curid=157620 |
Boron deficiency (plant disorder) Boron deficiency is a common deficiency of the micronutrient boron in plants. It is the most widespread micronutrient deficiency around the world and causes large losses in crop production and crop quality. Boron deficiency affects vegetative and reproductive growth of plants, resultin... | https://en.wikipedia.org/wiki?curid=157870 |
Boron deficiency (plant disorder) Boron deficiency is also observed in basic soils with a high pH because in basic conditions boric acid exists in an undissociated form which the plant is unable to absorb. Soils with low organic matter content (<1.5%) are also susceptible to boron deficiency. Highly leached sandy soils... | https://en.wikipedia.org/wiki?curid=157870 |
Boron deficiency (plant disorder) While boron may be sprayed on leaves, excess will cause plant damage. Application of boron may not correct boron deficiency in alkaline soils because even with the addition of boron, it may remain unavailable for plant absorption. Continued application of boron may be necessary in soil... | https://en.wikipedia.org/wiki?curid=157870 |
Boron deficiency (plant disorder) The B requirement is much higher for reproductive growth than for vegetative growth in most plant species. Boron increases flower production and retention, pollen tube elongation and germination, and seed and fruit development. A deficiency of B can cause incomplete pollination of corn... | https://en.wikipedia.org/wiki?curid=157870 |
Calcium deficiency (plant disorder) Calcium (Ca) deficiency is a plant disorder that can be caused by insufficient level of biologically available calcium in the growing medium, but is more frequently a product of low transpiration of the whole plant or more commonly the affected tissue. Plants are susceptible to such ... | https://en.wikipedia.org/wiki?curid=157877 |
Calcium deficiency (plant disorder) The mature leaves are rarely if ever affected because calcium accumulates to high concentrations in older leaves. Calcium deficiencies in plants are associated with reduced height, fewer nodes, and less leaf area. Crop-specific symptoms include: Calcium deficiency can sometimes be re... | https://en.wikipedia.org/wiki?curid=157877 |
Iron deficiency (plant disorder) Iron (Fe) deficiency is a plant disorder also known as "lime-induced chlorosis". It can be confused with manganese deficiency. Soil iron concentration is high, but can become unavailable for absorption if soil pH is higher than 6.5. Also, iron deficiency can develop if the soil is too w... | https://en.wikipedia.org/wiki?curid=157879 |
Iron deficiency (plant disorder) 5 - 7 range. Remediation includes: i) adding compost, manure, peat or similar organic matter (warning. Some retail blends of manure and compost have pH in the range 7 - 8 because of added lime. Read the MSDS if available. Beware of herbicide residues in manure. Source manure from a cert... | https://en.wikipedia.org/wiki?curid=157879 |
Exhaust gas recirculation In internal combustion engines, exhaust gas recirculation (EGR) is a nitrogen oxide () emissions reduction technique used in petrol/gasoline and diesel engines. EGR works by recirculating a portion of an engine's exhaust gas back to the engine cylinders. This dilutes the in the incoming air st... | https://en.wikipedia.org/wiki?curid=158740 |
Exhaust gas recirculation Gases re-introduced from EGR systems will also contain near equilibrium concentrations of and CO; the small fraction initially within the combustion chamber inhibits the total net production of these and other pollutants when sampled on a time average. Chemical properties of different fuels li... | https://en.wikipedia.org/wiki?curid=158740 |
Exhaust gas recirculation Later, backpressure transducers were added to the EGR valve control to further tailor EGR flow to engine load conditions. Most modern engines now need exhaust gas recirculation to meet emissions standards. However, recent innovations have led to the development of engines that do not require t... | https://en.wikipedia.org/wiki?curid=158740 |
Exhaust gas recirculation Since the EGR system recirculates a portion of exhaust gases, over time the valve can become clogged with carbon deposits that prevent it from operating properly. Clogged EGR valves can sometimes be cleaned, but replacement is necessary if the valve is faulty. In modern diesel engines, the EGR... | https://en.wikipedia.org/wiki?curid=158740 |
Exhaust gas recirculation Stricter regulations on particulate matter (PM) call for further emission controls to be introduced to compensate for the PM emission increases caused by EGR. The most common is a diesel particulate filter (DPF) in the exhaust system which cleans the exhaust but causes a constant minor reducti... | https://en.wikipedia.org/wiki?curid=158740 |
Exhaust gas recirculation Diesel EGR also increases soot production, though this was masked in the US by the simultaneous introduction of DPFs. EGR systems can also add abrasive contaminants and increase engine oil acidity, which in turn can reduce engine longevity. Though engine manufacturers have refused to release d... | https://en.wikipedia.org/wiki?curid=158740 |
Carbonyl group In organic chemistry, a carbonyl group is a functional group composed of a carbon atom double-bonded to an oxygen atom: C=O. It is common to several classes of organic compounds, as part of many larger functional groups. A compound containing a carbonyl group is often referred to as a carbonyl compound. ... | https://en.wikipedia.org/wiki?curid=158788 |
Carbonyl group This relative electronegativity draws electron density away from carbon, increasing the bond's polarity, therefore making carbon an electrophile (i.e. slightly positive). Carbon can then be attacked by nucleophiles (e.g. negatively charged ions, like the cyanide ion) or a negatively charged part of anoth... | https://en.wikipedia.org/wiki?curid=158788 |
Carbonyl group Carbonyl groups can be reduced by reaction with hydride reagents such as NaBH and LiAlH, with baker's yeast, or by catalytic hydrogenation. Ketones give secondary alcohols while aldehydes, esters and carboxylic acids give primary alcohols. Carbonyls can be alkylated in nucleophilic addition reactions usi... | https://en.wikipedia.org/wiki?curid=158788 |
Carbonyl group Of course, other effects can play a role in this selectivity process, including electronic effects, steric effects, and thermodynamic versus kinetic reaction control. Other important reactions include: α,β-Unsaturated carbonyl compounds are an important class of carbonyl compounds with the general struct... | https://en.wikipedia.org/wiki?curid=158788 |
Carbonyl group However, the endogenous scavenger compound glutathione naturally protects from toxic electrophiles in the body. Some drugs (amifostine, "N"-acetylcysteine) containing thiol groups may protect biomolecules from such harmful alkylation. | https://en.wikipedia.org/wiki?curid=158788 |
Shock (mechanics) A mechanical or physical shock is a sudden acceleration caused, for example, by impact, drop, kick, earthquake, or explosion. Shock is a transient physical excitation. Shock describes matter subject to extreme rates of force with respect to time. Shock is a vector that has units of an acceleration (ra... | https://en.wikipedia.org/wiki?curid=159081 |
Shock (mechanics) 6 indicates: "at least three times in both directions along each of three orthogonal axes". Shock testing typically falls into two categories, classical shock testing and pyroshock or ballistic shock testing. Classical shock testing consists of the following shock impulses: half sine, haversine, sawto... | https://en.wikipedia.org/wiki?curid=159081 |
Chemical composition refers to the identity and relative number of the chemical elements that make up any particular compound. The chemical composition of a pure substance corresponds to the relative amounts of the elements that constitute the substance itself. It can be expressed with a chemical formula, such as an em... | https://en.wikipedia.org/wiki?curid=159151 |
Gene expression is the process by which information from a gene is used in the synthesis of a functional gene product. These products are often proteins, but in non-protein-coding genes such as transfer RNA (tRNA) or small nuclear RNA (snRNA) genes, the product is a functional RNA. is summarized in the Central Dogma fi... | https://en.wikipedia.org/wiki?curid=159266 |
Gene expression Regulation of gene expression gives control over the timing, location, and amount of a given gene product (protein or ncRNA) present in a cell and can have a profound effect on the cellular structure and function. Regulation of gene expression is the basis for cellular differentiation, development, morp... | https://en.wikipedia.org/wiki?curid=159266 |
Gene expression RNA polymerase III transcribes 5S rRNA, transfer RNA (tRNA) genes, and some small non-coding RNAs ("e.g.", 7SK). Transcription ends when the polymerase encounters a sequence called the terminator. While transcription of prokaryotic protein-coding genes creates messenger RNA (mRNA) that is ready for tran... | https://en.wikipedia.org/wiki?curid=159266 |
Gene expression The poly(A) tail is bound by multiple poly(A)-binding proteins (PABPs) necessary for mRNA export and translation re-initiation. In the inverse process of deadenylation, poly(A) tails are shortened by the CCR4-Not 3′-5′ exonuclease, which often leads to full transcript decay. A very important modificatio... | https://en.wikipedia.org/wiki?curid=159266 |
Gene expression In the case of ribosomal RNAs (rRNA), they are often transcribed as a pre-rRNA that contains one or more rRNAs. The pre-rRNA is cleaved and modified (2′-O-methylation and pseudouridine formation) at specific sites by approximately 150 different small nucleolus-restricted RNA species, called snoRNAs. Sno... | https://en.wikipedia.org/wiki?curid=159266 |
Gene expression This is done either in the nucleoplasm or in the specialized compartments called Cajal bodies. Their bases are methylated or pseudouridinilated by a group of small Cajal body-specific RNAs (scaRNAs), which are structurally similar to snoRNAs. In eukaryotes most mature RNA must be exported to the cytopla... | https://en.wikipedia.org/wiki?curid=159266 |
Gene expression The coding region carries information for protein synthesis encoded by the genetic code to form triplets. Each triplet of nucleotides of the coding region is called a codon and corresponds to a binding site complementary to an anticodon triplet in transfer RNA. Transfer RNAs with the same anticodon sequ... | https://en.wikipedia.org/wiki?curid=159266 |
Gene expression This is governed by the signal recognition particle—a protein that binds to the ribosome and directs it to the endoplasmic reticulum when it finds a signal peptide on the growing (nascent) amino acid chain. Each protein exists as an unfolded polypeptide or random coil when translated from a sequence of ... | https://en.wikipedia.org/wiki?curid=159266 |
Gene expression Similarly, RNA chaperones help RNAs attain their functional shapes. Assisting protein folding is one of the main roles of the endoplasmic reticulum in eukaryotes. Secretory proteins of eukaryotes or prokaryotes must be translocated to enter the secretory pathway. Newly synthesized proteins are directed ... | https://en.wikipedia.org/wiki?curid=159266 |
Gene expression Control of expression is vital to allow a cell to produce the gene products it needs when it needs them; in turn, this gives cells the flexibility to adapt to a variable environment, external signals, damage to the cell, and other stimuli. More generally, gene regulation gives the cell control over all ... | https://en.wikipedia.org/wiki?curid=159266 |
Gene expression Genes often have several protein binding sites around the coding region with the specific function of regulating transcription. There are many classes of regulatory DNA binding sites known as enhancers, insulators and silencers. The mechanisms for regulating transcription are very varied, from blocking ... | https://en.wikipedia.org/wiki?curid=159266 |
Gene expression In general epigenetic effects alter the accessibility of DNA to proteins and so modulate transcription. DNA methylation is a widespread mechanism for epigenetic influence on gene expression and is seen in bacteria and eukaryotes and has roles in heritable transcription silencing and transcription regula... | https://en.wikipedia.org/wiki?curid=159266 |
Gene expression In eukaryotes, where export of RNA is required before translation is possible, nuclear export is thought to provide additional control over gene expression. All transport in and out of the nucleus is via the nuclear pore and transport is controlled by a wide range of importin and exportin proteins. Expr... | https://en.wikipedia.org/wiki?curid=159266 |
Gene expression By binding to specific sites within the 3'-UTR, miRNAs can decrease gene expression of various mRNAs by either inhibiting translation or directly causing degradation of the transcript. The 3'-UTR also may have silencer regions that bind repressor proteins that inhibit the expression of a mRNA. The 3'-UT... | https://en.wikipedia.org/wiki?curid=159266 |
Gene expression For instance, in gastrointestinal cancers, nine miRNAs have been identified as epigenetically altered and effective in down regulating DNA repair enzymes. The effects of miRNA dysregulation of gene expression also seem to be important in neuropsychiatric disorders, such as schizophrenia, bipolar disorde... | https://en.wikipedia.org/wiki?curid=159266 |
Gene expression They can also be seen in the immune system, where glycosylation plays a key role. One type of PTM can initiate another type of PTM, as can be seen in how ubiquitination tags proteins for degradation through proteolysis. Proteolysis, other than being involved in breaking down proteins, is also important ... | https://en.wikipedia.org/wiki?curid=159266 |
Gene expression The radiolabeled RNA is then detected by an autoradiograph. Because the use of radioactive reagents makes the procedure time consuming and potentially dangerous, alternative labeling and detection methods, such as digoxigenin and biotin chemistries, have been developed. Perceived disadvantages of Northe... | https://en.wikipedia.org/wiki?curid=159266 |
Gene expression qPCR is very sensitive (detection of a single mRNA molecule is theoretically possible), but can be expensive depending on the type of reporter used; fluorescently labeled oligonucleotide probes are more expensive than non-specific intercalating fluorescent dyes. For expression profiling, or high-through... | https://en.wikipedia.org/wiki?curid=159266 |
Gene expression They are generated by organizations such as the Genomics Institute of the Novartis Research Foundation and the European Bioinformatics Institute. Additional information can be found by searching their databases (for an example of the GLUT4 transporter pictured here, see citation). These profiles indicat... | https://en.wikipedia.org/wiki?curid=159266 |
Gene expression The question of how well protein levels correlate with their corresponding transcript levels is highly debated and depends on multiple factors. Regulation on each step of gene expression can impact the correlation, as shown for regulation of translation or protein stability. Post-translational factors, ... | https://en.wikipedia.org/wiki?curid=159266 |
Gene expression The enzyme-linked immunosorbent assay works by using antibodies immobilised on a microtiter plate to capture proteins of interest from samples added to the well. Using a detection antibody conjugated to an enzyme or fluorophore the quantity of bound protein can be accurately measured by fluorometric or ... | https://en.wikipedia.org/wiki?curid=159266 |
Gene expression In addition to these biological tools, certain naturally observed configurations of DNA (genes, promoters, enhancers, repressors) and the associated machinery itself are referred to as an expression system. This term is normally used in the case where a gene or set of genes is switched on under well def... | https://en.wikipedia.org/wiki?curid=159266 |
Gene expression There are several ways to construct gene expression networks, but one common approach is to compute a matrix of all pair-wise correlations of expression across conditions, time points, or individuals and convert the matrix (after thresholding at some cut-off value) into a graphical representation in whi... | https://en.wikipedia.org/wiki?curid=159266 |
Type metal In printing, type metal (sometimes called hot metal) refers to the metal alloys used in traditional typefounding and hot metal typesetting. Historically, type metal was an alloy of lead, tin and antimony in different proportions depending on the application, be it individual character mechanical casting for ... | https://en.wikipedia.org/wiki?curid=159441 |
Type metal (His other contributions were the creation of inks that would adhere to metal type and a method of softening handmade printing paper so that it would take the impression well.) Cheap, plentifully available as galena and easily workable, lead has many of the ideal characteristics, but on its own it lacks the ... | https://en.wikipedia.org/wiki?curid=159441 |
Type metal is an alloy of lead, tin and antimony in different proportions depending on the application, be it individual character mechanical casting for hand setting, mechanical line casting or individual character mechanical typesetting and stereo plate casting. The proportions used are in the range: lead 50‒86%, ant... | https://en.wikipedia.org/wiki?curid=159441 |
Type metal Printers had sometimes their own preferences about the quality of particular alloys. The Lanston Monotype Corporation in the United Kingdom had a whole range of alloys listed in their manuals. Most mechanical typesetting is divided basically into two different competing technologies: line casting (Linotype a... | https://en.wikipedia.org/wiki?curid=159441 |
Type metal Every time type metal is remelted, tin and antimony oxidise. These oxides form on the surface of the crucible and must be removed. After stirring the molten metal, grey powder forms on the surface, the dross, needing to be skimmed. Dross contains recoverable amounts of tin and antimony. Dross must be process... | https://en.wikipedia.org/wiki?curid=159441 |
Type metal Using a 10% antimony, 90% lead mixture delays lead crystal formation until approximately 260 °C. Using a 12% antimony, 88% lead mixture prevents crystal formation entirely, becoming a "eutectic". This alloy has a clear melting point, at 252 °C. Increasing the antimony content beyond 12% will lead to predomin... | https://en.wikipedia.org/wiki?curid=159441 |
Type metal The fierce competition between the different mechanical typecasting systems like Linotype and Monotype has given rise to some lasting fairy tales about typemetal. Linotype users looked down on Monotype and vice versa. Monotype machines however can utilize a wide range of different alloys; maintaining a const... | https://en.wikipedia.org/wiki?curid=159441 |
Type metal Copper has been used for hardening type metal; this metal easily forms mixed crystals with tin when the alloy cools down. These crystals will grow just below the exit opening of the nozzle in Monotype machines, resulting in a total blockage after some time. These nozzles are very difficult to clean, because ... | https://en.wikipedia.org/wiki?curid=159441 |
Type metal In this way ferro-sulfide was formed, that would evaporate with all the fumes. The mixture of stibnite and nails was heated red hot in an open-air furnace, until all is molten and finished. The resulting metal can contain up to 9% of iron. Further purification can be done by mixing the hot melt with kitchen-... | https://en.wikipedia.org/wiki?curid=159441 |
Permethrin Permethrin, sold under the brand name Nix among others, is a medication and insecticide. As a medication, it is used to treat scabies and lice. It is applied to the skin as a cream or lotion. As an insecticide, it can be sprayed on clothing or mosquito nets to kill the insects that touch them. Side effects i... | https://en.wikipedia.org/wiki?curid=656936 |
Permethrin In agriculture, permethrin is mainly used on cotton, wheat, maize, and alfalfa crops. Its use is controversial because, as a broad-spectrum chemical, it kills indiscriminately; as well as the intended pests, it can harm beneficial insects, including honey bees, and aquatic life. kills ticks and mosquitoes on... | https://en.wikipedia.org/wiki?curid=656936 |
Permethrin Animal studies have shown no effects on fertility or teratogenicity, but studies in humans have not been performed. The excretion of permethrin in breastmilk is unknown, and breastfeeding is recommended to be temporarily discontinued during treatment. Skin reactions are uncommon. Excessive exposure to permet... | https://en.wikipedia.org/wiki?curid=656936 |
Permethrin Metabolism of permethrin occurs mainly in the liver, where the molecule undergoes oxidation by the cytochrome P450 system, as well as hydrolysis, into metabolites. Elimination of these metabolites occurs via urinary excretion. has four stereoisomers (two enantiomeric pairs), arising from the two stereocenter... | https://en.wikipedia.org/wiki?curid=656936 |
Permethrin In Nordic countries and North America, a permethrin formulation for lice treatment is marketed under trade name Nix, available over the counter. Johnson & Johnson's UK brand Lyclear covers an assortment of different products, mostly non-insecticidal, but a few of which are based on permethrin. Stronger conce... | https://en.wikipedia.org/wiki?curid=656936 |
Permethrin This intolerance is due to a defect in glucuronosyltransferase, a common detoxification enzyme in other mammals, that also makes the cat intolerant to paracetamol. The use of any external parasiticides based on permethrin is contraindicated for cats (cat ecotoxicology: cutaneous 100 mg/kg – oral 200 mg/kg). | https://en.wikipedia.org/wiki?curid=656936 |
Polymer chemistry is a sub-discipline of chemistry that focuses on the chemical synthesis, structure, chemical and physical properties of polymers and macromolecules. The principles and methods used within polymer chemistry are also applicable through a wide range of other chemistry sub-disciplines like organic chemist... | https://en.wikipedia.org/wiki?curid=656965 |
Polymer chemistry In 1884 Hilaire de Chardonnet started the first artificial fiber plant based on regenerated cellulose, or viscose rayon, as a substitute for silk, but it was very flammable. In 1907 Leo Baekeland invented the first polymer made independent of the products of organisms, a thermosetting phenol-formaldeh... | https://en.wikipedia.org/wiki?curid=656965 |
Polymer chemistry Wallace Carothers invented the first synthetic rubber called neoprene in 1931, the first polyester, and went on to invent nylon, a true silk replacement, in 1935. Paul Flory was awarded the Nobel Prize in Chemistry in 1974 for his work on polymer random coil configurations in solution in the 1950s. St... | https://en.wikipedia.org/wiki?curid=656965 |
Polymer chemistry A polymer can be described in many ways: its degree of polymerisation, molar mass distribution, tacticity, copolymer distribution, the degree of branching, by its end-groups, crosslinks, crystallinity and thermal properties such as its glass transition temperature and melting temperature. Polymers in ... | https://en.wikipedia.org/wiki?curid=656965 |
Polymer chemistry Synthetic polymers are the structural materials manifested in plastics, synthetic fibers, paints, building materials, furniture, mechanical parts, and adhesives. Synthetic polymers may be divided into thermoplastic polymers and thermoset plastics. Thermoplastic polymers include polyethylene, teflon, p... | https://en.wikipedia.org/wiki?curid=656965 |
Environmental chemistry is the scientific study of the chemical and biochemical phenomena that occur in natural places. It should not be confused with green chemistry, which seeks to reduce potential pollution at its source. It can be defined as the study of the sources, reactions, transport, effects, and fates of chem... | https://en.wikipedia.org/wiki?curid=656979 |
Environmental chemistry The term contaminant is often used interchangeably with "pollutant", which is a substance that has a detrimental impact on the surrounding environment. Whilst a contaminant is sometimes defined as a substance present in the environment as a result of human activity, but without harmful effects, ... | https://en.wikipedia.org/wiki?curid=656979 |
Environmental chemistry Common analytical techniques used for quantitative determinations in environmental chemistry include classical wet chemistry, such as gravimetric, titrimetric and electrochemical methods. More sophisticated approaches are used in the determination of trace metals and organic compounds. Metals ar... | https://en.wikipedia.org/wiki?curid=656979 |
Environmental chemistry Polymerase Chain Reaction PCR is able to identify species of bacteria and other organisms through specific DNA and RNA gene isolation and amplification and is showing promise as a valuable technique for identifying environmental microbial contamination. Peer-reviewed test methods have been publi... | https://en.wikipedia.org/wiki?curid=656979 |
Water mass An oceanographic water mass is an identifiable body of water with a common formation history which has physical properties distinct from surrounding water. Properties include temperature, salinity, chemical - isotopic ratios, and other physical quantities. Water masses are generally distinguished not only by... | https://en.wikipedia.org/wiki?curid=657988 |
Process control Automatic process control in continuous production processes is a combination of control engineering and chemical engineering disciplines that uses industrial control systems to achieve a production level of consistency, economy and safety which could not be achieved purely by human manual control. It i... | https://en.wikipedia.org/wiki?curid=658183 |
Process control In 1681, Denis Papin discovered the pressure inside a vessel could be regulated by placing weights on top of the vessel lid. In 1745, Edmund Lee created the fantail to improve windmill efficiency; a fantail was a smaller windmill placed 90° of the larger fans to keep the face of the windmill pointed dir... | https://en.wikipedia.org/wiki?curid=658183 |
Process control While proportional control provided stability against small disturbances, it was insufficient for dealing with a steady disturbance, notably a stiff gale (due to steady-state error), which required adding the integral term. Finally, the derivative term was added to improve stability and control. of larg... | https://en.wikipedia.org/wiki?curid=658183 |
Process control These could be distributed around plant, and communicate with the graphic display in the control room or rooms. The distributed control system was born. The introduction of DCSs allowed easy interconnection and re-configuration of plant controls such as cascaded loops and interlocks, and easy interfacin... | https://en.wikipedia.org/wiki?curid=658183 |
Process control To determine the fundamental model for any process, the inputs and outputs of the system are defined differently than for other chemical processes. The balance equations are defined by the control inputs and outputs rather than the material inputs. The control model is a set of equations used to predict... | https://en.wikipedia.org/wiki?curid=658183 |
Process control One example is the production of adhesives and glues, which normally require the mixing of raw materials in a heated vessel for a period of time to form a quantity of end product. Other important examples are the production of food, beverages and medicine. Batch processes are generally used to produce a... | https://en.wikipedia.org/wiki?curid=658183 |
Process control Some large systems may have several hundreds or thousands of control loops. In complex processes the loops are interactive, so that the operation of one loop may affect the operation of another. The system diagram for representing control loops is a Piping and instrumentation diagram. Commonly used cont... | https://en.wikipedia.org/wiki?curid=658183 |
Process control Process efficiency can be enhanced by reducing the margins necessary to ensure product specifications are met. This can be done by improving the control of the process to minimize the effect of disturbances on the process. The efficiency is improved in a two step method of narrowing the variance and shi... | https://en.wikipedia.org/wiki?curid=658183 |
Sinistral and dextral Sinistral and dextral, in some scientific fields, are the two types of chirality ("handedness") or relative direction. The terms are derived from the Latin words for "left" ("sinister") and "right" ("dexter"). Other disciplines use different terms (such as dextro- and laevo-rotary in chemistry, or... | https://en.wikipedia.org/wiki?curid=658686 |
Sinistral and dextral A very few species show an even mixture of dextral and sinistral individuals (for example, "Amphidromus perversus"). The most obvious characteristic of flatfish, other than their flatness, is their asymmetrical morphology: both eyes are on the same side of the head in the adult fish. In some famil... | https://en.wikipedia.org/wiki?curid=658686 |
Mass number The mass number (symbol "A", from the German word "Atomgewicht" [atomic weight]), also called atomic mass number or nucleon number, is the total number of protons and neutrons (together known as nucleons) in an atomic nucleus. It is approximately equal to the "atomic" (also known as "isotopic") mass of the ... | https://en.wikipedia.org/wiki?curid=659068 |
Mass number Thus the atomic number and the number of neutrons each decrease by 2 ("Z": 92 → 90, "N": 146 → 144), so that the mass number decreases by 4 ("A" = 238 → 234); the result is an atom of thorium-234 and an alpha particle (): On the other hand, carbon-14 decays by beta decay, whereby one neutron is transmuted i... | https://en.wikipedia.org/wiki?curid=659068 |
Mass number For example, Cl (17 protons and 18 neutrons) has a mass number of 35 and an isotopic mass of 34.96885. The difference between mass number of an atom and its isotopic mass is known as the mass excess. Mass excess should not be confused with mass defect which is the difference between the mass of an atom and ... | https://en.wikipedia.org/wiki?curid=659068 |
Mass number For example, bromine has only two stable isotopes, Br and Br, naturally present in approximately equal fractions, which leads to the standard atomic mass of bromine close to 80 (79.904 g/mol), even though the isotope Br with such mass is unstable. | https://en.wikipedia.org/wiki?curid=659068 |
Gold fingerprinting is a method of identifying an item made of gold based on the impurities or trace elements it contains. This technique has been used to lay claim to stolen or relocated gold, including gold that has undergone salting can be identified by its multiple sources. also assists in understanding the origins... | https://en.wikipedia.org/wiki?curid=659597 |
Gold fingerprinting Laser ablation allows for high spatial resolution sampling while the inductively coupled plasma mass spectrometry provides high sensitivity to identify extremely small amounts of trace elements within the gold. This method can also be conducted outside of a lab with the assistance of a portable devi... | https://en.wikipedia.org/wiki?curid=659597 |
Gold fingerprinting has limitations including elemental fractionation (the non-sample related analyte) and calibration requires matrix-matched standards. A few other problems exist that limit actual sourcing or provencancing of gold in relation to manufactured art objects. These problems include: a lack of an extensive... | https://en.wikipedia.org/wiki?curid=659597 |
Gravimetric analysis describes a set of methods used in analytical chemistry for the quantitative determination of an analyte (the ion being analyzed) based on its mass. The principle of this type of analysis is that once an ion's mass has been determined as a unique compound, that known measurement can then be used to... | https://en.wikipedia.org/wiki?curid=659899 |
Gravimetric analysis The reaction is pure calcium oxide formed CaCO → CaO + CO+ CO The pure precipitate is cooled, then measured by weighing, and the difference in weights before and after reveals the mass of analyte lost, in this case calcium oxide. That number can then be used to calculate the amount, or the percent ... | https://en.wikipedia.org/wiki?curid=659899 |
Gravimetric analysis It then passes a mixture of the drying agent "and" sodium hydroxide which lays on asbestos or "Ascarite II", a non-fibrous silicate containing sodium hydroxide The mass of the carbon dioxide is obtained by measuring the increase in mass of this absorbent. This is performed by measuring the differen... | https://en.wikipedia.org/wiki?curid=659899 |
Gravimetric analysis Determination of the amount of water by measuring the loss in mass of the sample during heating is an example of an indirect method. It is well known that changes in mass occur due to decomposition of many substances when heat is applied, regardless of the presence or absence of water. Because one ... | https://en.wikipedia.org/wiki?curid=659899 |
Gravimetric analysis In fact, gravimetric analysis was used to determine the atomic masses of many elements in the periodic table to six figure accuracy. Gravimetry provides very little room for instrumental error and does not require a series of standards for calculation of an unknown. Also, methods often do not requi... | https://en.wikipedia.org/wiki?curid=659899 |
Gravimetric analysis After appropriate dissolution of the sample the following steps should be followed for successful gravimetric procedure: 1. Preparation of the Solution: This may involve several steps including adjustment of the pH of the solution in order for the precipitate to occur quantitatively and get a preci... | https://en.wikipedia.org/wiki?curid=659899 |
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