"found to Bartholomew Gosnold (1571–1607) indicating that the use of a sextant for nautical navigation predates Hadley's implementation. In 1922, it was modified for aeronautical navigation by Portuguese navigator and naval officer . This section discusses navigators' sextants. Most of what is said about these specific sextants applies equally to other types of sextants. Navigators' sextants were primarily used for ocean navigation. Like the Davis quadrant, the sextant allows celestial objects to be measured relative to the horizon, rather than relative to the instrument. This allows excellent precision. However, unlike the backstaff, the sextant allows direct observations of stars. This"
"that degrade this polysaccharide, such as ""Bacillus"", ""Corynebacterium"" and ""Paenibacillus"" species. Xanthan is used in industry as a thickening agent in foods and drinks, as a stabilizing agent for foams, as a means of enhancing oil recovery and in the manufacture of good such as paints, cosmetics and explosives. The use of xanthan lyase as a means of altering the physical properties of xanthans is an area of current research in biotechnology. As of late 2007, 7 structures have been solved for this class of enzymes, with PDB accession codes , , , , , , and . The enzyme"
"Xanthate Xanthate usually refers to a salt with the formula (R = alkyl; M = Na, K), thus O-esters of dithiocarbonate. The name ""xanthates"" is derived from Greek ""xanthos"", meaning “yellowish, golden”, and indeed most xanthate salts are yellow. They were discovered and named in 1823 by Danish chemist William Christopher Zeise. These organosulfur compounds are important in two areas: the production of cellophane and related polymers from cellulose and (in mining) for extraction of certain ores. They are also versatile intermediates in organic synthesis. Xanthates also refer to esters of xanthic acid. These esters have the structure ROC(=S)SR′. Xanthate"
"Xanthan gum Xanthan gum () is a polysaccharide with many industrial uses, including as a common food additive. It is an effective thickening agent and stabilizer to prevent ingredients from separating. It can be produced from simple sugars using a fermentation process, and derives its name from the species of bacteria used, ""Xanthomonas campestris"". Xanthan gum was discovered by Allene Rosalind Jeanes and her research team at the United States Department of Agriculture, and brought into commercial production under the trade name Kelzan in the early 1960s. It was approved for use in foods in 1968 and is accepted as"
"2011. There was no further information available as of October 2016. Hexavalent chromium Hexavalent chromium (chromium(VI), Cr(VI), ""'chromium 6"" ,cancer causing chromium-6') is any chemical compound that contains the element chromium in the +6 oxidation state (thus hexavalent). Virtually all chromium ore is processed via hexavalent chromium, specifically the salt sodium dichromate. Approximately of hexavalent chromium were produced in 1985. Additional hexavalent chromium compounds are chromium trioxide and various salts of chromate and dichromate, among others. Hexavalent chromium is used in textile dyes, wood preservation, anti-corrosion products, chromate conversion coatings, and a variety of niche uses. Industrial uses of hexavalent"
"a means for deoxygenation of alcohols. They can be oxidized to the so-called dixanthogens: Xanthates bind to transition metal cations as bidentate ligands. The charge-neutral complexes are soluble in organic solvents. Cellulose reacts with carbon disulfide (CS) in presence of sodium hydroxide (NaOH) to produces sodium cellulose xanthate, which upon neutralization with sulfuric acid (HSO) gives viscose rayon or cellophane paper (Sellotape or Scotch Tape). Certain xanthate salts and bisxanthates (e.g. Dixanthogen) are used as flotation agents in mineral processing. They are intermediates in the Chugaev elimination process and are used to control radical polymerisation under the RAFT process, also"
"in the presence of magnesium. If it is not in the presence of magnesium, strontium carbonate has been found to be a better option to produce an even greater effect. Strontium oxalate Strontium oxalate is a compound with the chemical formula SrCO. Strontium oxalate can exist either in a hydrated form (SrCO•HO) or as the acidic salt of strontium oxalate (SrCO•HCO•HO). With the addition of heat, strontium oxalate will decompose based on the following reaction: Strontium oxalate is a good agent for use in pyrotechnics since it decomposes readily with the addition of heat. When it decomposes into strontium oxide,"
"as allergy or sensitization, could result. Instances of this occurring are, however, extremely rare and xanthan gum is not listed as a known allergen or sensitizer for the general public. In fact, xanthan gum is notably used to replace grains or other sensitizers in products intended for individuals with sensitivities or allergies to grains. Xanthan gum is a ""highly efficient laxative,"" according to a study that fed 15 g/day for 10 days to 18 normal volunteers. This is not a dosage that would be encountered in normal consumption of foodstuffs. This study set out to examine the use of xanthan"
"significantly better than using glycolic acid alone. As a divalent ion with an ionic radius similar to that of Ca (1.13 vs. 0.99 A, respectively), Sr ions resembles calcium's ability to traverse calcium-selective ion channels and trigger neurotransmitter release from nerve endings. It is thus used in electrophysiology experiments. In his short story ""A Germ Destroyer"", Rudyard Kipling refers to strontium nitrate as the main ingredient of the titular fumigant. Strontium nitrate Strontium nitrate is an inorganic compound made of the elements strontium and nitrogen with the formula Sr(NO). This colorless solid is used as a red colorant and oxidizer"
"perxenate compounds are used as oxidizing agents in analytical chemistry. Xenon difluoride is used as an etchant for silicon, particularly in the production of microelectromechanical systems (MEMS). The anticancer drug 5-fluorouracil can be produced by reacting xenon difluoride with uracil. Xenon is also used in protein crystallography. Applied at pressures from 0.5 to 5 MPa (5 to 50 atm) to a protein crystal, xenon atoms bind in predominantly hydrophobic cavities, often creating a high-quality, isomorphous, heavy-atom derivative that can be used for solving the phase problem. Because they are strongly oxidative, many oxygen-xenon compounds are toxic; they are also explosive"
"of lead nitrate. There are also several electrochemical detection methods, which can be combined with some of the above chemical techniques. Sodium ethyl xanthate is predominantly used in the mining industry as flotation agent for recovery of metals, such as copper, nickel, silver or gold, as well as solid metal sulfides or oxides from ore slurries. This application was introduced by Cornelius H. Keller in 1925. Other applications include defoliant, herbicide and an additive to rubber to protect it against oxygen and ozone. The mechanism of flotation enhancement is as follows. The polar part of xanthate molecule attaches to the"
"Sodium ethyl xanthate Sodium ethyl xanthate (SEX) is an organosulfur compound with the chemical formula CHCHOCSNa. It is a pale yellow powder, which is usually obtained as the dihydrate. Sodium ethyl xanthate is used in the mining industry as a flotation agent. A closely related potassium ethyl xanthate (KEX) is obtained as the anhydrous salt. As with most xanthates, sodium ethyl xanthate can be prepared by treating sodium ethoxide with carbon disulfide: Sodium ethyl xanthate is a pale yellow powder. It is relatively stable in water at high pH if not heated. It rapidly hydrolyses at pH <9 at 25"
"spectrometers. Other taggants in use are ethylene glycol dinitrate, known as EGDN and used to mark Semtex, ortho-mononitrotoluene (o-MNT), and para-mononitrotoluene (p-MNT). These have been considered for introduction in industrial explosives so that the manufacturer and batch number can be determined if they are used illegally. The taggant must survive the detonation of the product and not be contaminated by the environment afterwards. Several different technologies have been considered, but the most common are microscopic polymer/metallic particles. Taggant evidence was crucial in the 1980 conviction of James L. McFillin in Maryland for the 1979 truck bombing murder of Nathan A."
"Chelation Chelation (, ) is a type of bonding of ions and molecules to metal ions. It involves the formation or presence of two or more separate coordinate bonds between a polydentate (multiple bonded) ligand and a single central atom. These ligands are called chelants, chelators, chelating agents, or sequestering agents. They are usually organic compounds. Chelation is useful in applications such as providing nutritional supplements, in chelation therapy to remove toxic metals from the body, as contrast agents in MRI scanning, in manufacturing using homogeneous catalysts, in chemical water treatment to assist in the removal of metals, and in"
"Bitterant A bitterant (or bittering agent) is a chemical that is added to a product to make it smell or taste bitter. Bitterants are commonly used as aversive agents to discourage the inhalation or ingestion of toxic substances. The threshold for stimulation of bitter taste by quinine averages a concentration of 8 μM (8 micromolar). The taste thresholds of other bitter substances are rated relative to quinine, which is thus given a reference index of 1. For example, Brucine has an index of 11, is thus perceived as intensely more bitter than quinine, and is detected at a much lower"
"Hexavalent chromium Hexavalent chromium (chromium(VI), Cr(VI), ""'chromium 6"" ,cancer causing chromium-6') is any chemical compound that contains the element chromium in the +6 oxidation state (thus hexavalent). Virtually all chromium ore is processed via hexavalent chromium, specifically the salt sodium dichromate. Approximately of hexavalent chromium were produced in 1985. Additional hexavalent chromium compounds are chromium trioxide and various salts of chromate and dichromate, among others. Hexavalent chromium is used in textile dyes, wood preservation, anti-corrosion products, chromate conversion coatings, and a variety of niche uses. Industrial uses of hexavalent chromium compounds include chromate pigments in dyes, paints, inks, and plastics;"
"Mordant A mordant or dye fixative is a substance used to set (i.e. bind) dyes on fabrics by forming a coordination complex with the dye, which then attaches to the fabric (or tissue). It may be used for dyeing fabrics or for intensifying stains in cell or tissue preparations. As applied to textiles, mordants are mainly of historical interest because the use of mordant dyes was largely displaced by directs. The term mordant comes from the Latin ""mordere"", ""to bite"". In the past, it was thought that a mordant helped the dye bite onto the fiber so that it would"
"to convert blood components into energy and for the bacteria to be virulent. Such bacteria would starve without this enzyme. As such, the role of the Oxantel as a fumarate reductase inhibitor would be to kill the bacteria responsible for periodontal disease. Oxantel Oxantel is an anthelmintic. It has typically been used human and animal use as a standard treatment for intestinal worms. Oxantel is currently being experimented with for the treatment of periodontal disease by the Cooperative Research Centre for Oral Health Science (CRC). Laureate Professor Eric Reynolds AO (former head of the Melbourne Dental School at The University"
"not suffice because they do not remain bound to Gd in solution. Ligands with higher coordination numbers therefore are required. The obvious candidate is EDTA, ethylenediaminetetraacetate, which is a commonly employed hexadentate ligand used to complex to transition metals. In lanthanides, however, exhibit coordination numbers greater than six, so still larger aminocarboxylates are employed. One representative chelating agent is HDTPA, diethylenetriaminepentaacetic acid. Chelation to the conjugate base of this ligand increases the solubility of the Gd at the body's neutral pH ""and"" still allows for the paramagnetic effect required for an MRI contrast agent. The DTPA ligand binds to Gd"
"Australia, one resulted in evacuation of 100 people and hospitalization of 6 workers who were exposed to the fumes. In another accident, residents of the spillage area complained of headache, dizziness and nausea. Consequently, during high-risk sodium ethyl xanthate handling operations, workers are required by the Australian regulations to be equipped with protective clothing, anti-static gloves, boots and full-face respirators or self-contained breathing apparatus. Sodium ethyl xanthate Sodium ethyl xanthate (SEX) is an organosulfur compound with the chemical formula CHCHOCSNa. It is a pale yellow powder, which is usually obtained as the dihydrate. Sodium ethyl xanthate is used in the"
"Xanthone Xanthone is an organic compound with the molecular formula CHO. It can be prepared by the heating of phenyl salicylate. In 1939, xanthone was introduced as an insecticide and it currently finds uses as ovicide for codling moth eggs and as a larvicide. Xanthone is also used in the preparation of xanthydrol, which is used in the determination of urea levels in the blood. It can also be used as a photocatalyst. The chemical structure of xanthone forms the central core of a variety of naturally occurring organic compounds, such as mangostin, which are sometimes collectively referred to as"
"solid particles, such as spices. Xanthan gum helps create the desired texture in many ice creams. Toothpaste often contains xanthan gum as a binder to keep the product uniform. Xanthan gum also helps thicken commercial egg substitutes made from egg whites, to replace the fat and emulsifiers found in yolks. It is also a preferred method of thickening liquids for those with swallowing disorders, since it does not change the color or flavor of foods or beverages at typical use levels. In gluten-free baking, xanthan gum is used to give the dough or batter the stickiness that would otherwise be"
"commonly used as reducing agents in myriad organic and inorganic reactions. They can also act as antioxidants for fatty acids. In the synthesis of nylon 6, cyclohexanone (1) is first converted to its oxime (2); treatment of this oxime with acid induces the Beckmann rearrangement to give caprolactam (3): The nitrate salt, hydroxylammonium nitrate, is being researched as a rocket propellant, both in water solution as a monopropellant and in its solid form as a solid propellant. This has also been used in the past by biologists to introduce random mutations by switching base pairs from G to A, or"
"Pertechnetate The pertechnetate ion is an oxoanion with the chemical formula . It is often used as a convenient water-soluble source of isotopes of the radioactive element technetium (Tc). In particular it is used to carry the Tc isotope (half-life 6 hours) which is commonly used in nuclear medicine in several nuclear scanning procedures. A technetate(VII) salt is a compound containing this ion. Pertechnetate compounds are salts of technetic(VII) acid. Pertechnetate is analogous to permanganate but it has little oxidizing power. Pertechnetate has higher oxidation power than perrhenate. Understanding pertechnate is important in understanding technetium contamination in the environment and"
"detergents. A significant use for sodium hexametaphosphate is as a deflocculant in the production of clay-based ceramic particles. It is also used as a dispersing agent to break down clay and other soil types for soil texture assessment. It is used as an active ingredient in toothpastes as an anti-staining and tartar prevention ingredient. As a food additive, SHMP is used as an emulsifier. Artificial maple syrup, canned milk, cheese powders and dips, imitation cheese, whipped topping, packaged egg whites, roast beef, fish fillets, fruit jelly, frozen desserts, salad dressing, herring, breakfast cereal, ice cream, beer, and bottled beverages, among"
"unpleasant tastes or smells. In liquid and gel formulations, the bulk excipient that serves as a medium for conveying the active ingredient is usually called the vehicle. Petrolatum, dimethyl sulfoxide and mineral oil are common vehicles. Excipient An excipient is a substance formulated alongside the active ingredient of a medication, included for the purpose of long-term stabilization, bulking up solid formulations that contain potent active ingredients in small amounts (thus often referred to as ""bulking agents"", ""fillers"", or ""diluents""), or to confer a therapeutic enhancement on the active ingredient in the final dosage form, such as facilitating drug absorption, reducing"
"Oxantel Oxantel is an anthelmintic. It has typically been used human and animal use as a standard treatment for intestinal worms. Oxantel is currently being experimented with for the treatment of periodontal disease by the Cooperative Research Centre for Oral Health Science (CRC). Laureate Professor Eric Reynolds AO (former head of the Melbourne Dental School at The University of Melbourne, Australia) and Associate Professor Stuart Dashper are currently testing its ability as a Fumarate reductase inhibitor. Fumarate reductase is an enzyme that has been found in the pathogenic bacteria in the biofilm in periodontal pockets. This bacteria has the ability"
"xylitol in chewing gum was insufficient to determine if it is effective at preventing caries. The use of dental sealants is a means of prevention. A sealant is a thin plastic-like coating applied to the chewing surfaces of the molars to prevent food from being trapped inside pits and fissures. This deprives resident plaque bacteria of carbohydrate, preventing the formation of pit and fissure caries. Sealants are usually applied on the teeth of children, as soon as the teeth erupt but adults are receiving them if not previously performed. Sealants can wear out and fail to prevent access of food"
"60-100 IBU or more. Bitterant A bitterant (or bittering agent) is a chemical that is added to a product to make it smell or taste bitter. Bitterants are commonly used as aversive agents to discourage the inhalation or ingestion of toxic substances. The threshold for stimulation of bitter taste by quinine averages a concentration of 8 μM (8 micromolar). The taste thresholds of other bitter substances are rated relative to quinine, which is thus given a reference index of 1. For example, Brucine has an index of 11, is thus perceived as intensely more bitter than quinine, and is detected"
"certain metallic oxides. It has some properties similar to barium carbonate. It is also used in the manufacturing of strontium ferrites for permanent magnets which are used in Loudspeakers and door magnets. Strontium carbonate is also used for making some superconductors such as BSCCO and also for electroluminescent materials where it is first calcined into SrO and then mixed with sulphur to make SrS:x where x is typically europium. This is the famous ""blue/green"" phosphor which is sensitive to frequency and changes from lime green to blue . Other dopants can also be used such as gallium, or yttrium to"
"Sexercise Sexercise (it is referred to by some as eroticise) is physical exercise performed in preparation for sexual activity and designed to tone, build, and strengthen muscles. Sexercises are often performed as part of a sex diet lifestyle, which seeks to maximize the health benefits of regular sexual activity. Exercise is known to improve and quicken the flow of oxygenated blood, in higher and consistent amounts, along with other beneficial chemical compounds, to the genitalia, which is important for fertility and important during intercourse. Sexercises range from Kegel exercise to aerobic and cardiovascular routines. Flexibility for performing contortion specifically for"
"menthone. It is used as a flavoring for toothpaste and confectionery, and is sometimes added to shampoos and soaps. Spearmint has been used traditionally as medicines for minor ailments such as fevers, and digestive disorders. There is research on spearmint extracts in the treatment of gout and as an antiemetic. There is research on the possible cytotoxic effects of spearmint on leukemia cells. Spearmint essential oil has had success as a larvicide against mosquitos. Using spearmint as a larvicide would be a greener alternative to synthetic insecticides due to their toxicity and negative affect to the environment. Used as a"
"imaging (MRI). This technique exploits the fact that Gd has an electronic configuration of f. Seven is the largest number of unpaired electron spins possible for an atom, so Gd is a key component in the design of highly paramagnetic complexes. To generate the relaxation agents, Gd sources such as GdCl∙6HO are converted to coordination complexes. GdCl∙6HO can not be used as an MRI contrasting agent due to its low solubility in water at the body's near neutral pH. ""Free"" gadolinium(III), e.g. [GdCl(HO)], is toxic, so chelating agents are essential for biomedical applications. Simple monodentate or even bidentate ligands will"