The chloride ion is the anion Cl−. It is formed when the element chlorine gains an electron or when a compound such as hydrogen chloride is dissolved in water or other polar solvents. Chloride salts such as sodium chloride are very soluble in water, it is an essential electrolyte located in all body fluids responsible for maintaining acid/base balance, transmitting nerve impulses and regulating fluid in and out of cells. Less the word chloride may form part of the "common" name of chemical compounds in which one or more chlorine atoms are covalently bonded. For example, methyl chloride, with the standard name chloromethane is an organic compound with a covalent C−Cl bond in which the chlorine is not an anion. A chloride ion is much larger than a chlorine atom, 99 pm, respectively; the ion is diamagnetic. In aqueous solution, it is soluble in most cases. In aqueous solution, chloride is bound by the protic end of the water molecules. Sea water contains 1.94% chloride. Some chloride-containing minerals include the chlorides of sodium and magnesium, hydrated MgCl2.
The concentration of chloride in the blood is called serum chloride, this concentration is regulated by the kidneys. A chloride ion is a structural component of e.g. it is present in the amylase enzyme. The chlor-alkali industry is a major consumer of the world's energy budget; this process converts sodium chloride into chlorine and sodium hydroxide, which are used to make many other materials and chemicals. The process involves two parallel reactions: 2 Cl− → Cl2 + 2 e− 2 H2O + 2 e− → H2 + 2 OH− Another major application involving chloride is desalination, which involves the energy intensive removal of chloride salts to give potable water. In the petroleum industry, the chlorides are a monitored constituent of the mud system. An increase of the chlorides in the mud system may be an indication of drilling into a high-pressure saltwater formation, its increase can indicate the poor quality of a target sand. Chloride is a useful and reliable chemical indicator of river / groundwater fecal contamination, as chloride is a non-reactive solute and ubiquitous to sewage & potable water.
Many water regulating companies around the world utilize chloride to check the contamination levels of the rivers and potable water sources. Chloride salts such as sodium chloride are used to preserve food; the presence of chlorides, e.g. in seawater aggravates the conditions for pitting corrosion of most metals by enhancing the formation and growth of the pits through an autocatalytic process. Chloride is an essential electrolyte, trafficking in and out of cells through chloride channels and playing a key role in maintaining cell homeostasis and transmitting action potentials in neurons. Characteristic concentrations of chloride in model organisms are: in both E. coli and budding yeast are 10-200mM, in mammalian cell 5-100mM and in blood plasma 100mM. Chloride can be oxidized but not reduced; the first oxidation, as employed in the chlor-alkali process, is conversion to chlorine gas. Chlorine can be further oxidized to other oxides and oxyanions including hypochlorite, chlorine dioxide and perchlorate.
In terms of its acid–base properties, chloride is a weak base as indicated by the negative value of the pKa of hydrochloric acid. Chloride can be protonated by strong acids, such as sulfuric acid: NaCl + H2SO4 → NaHSO4 + HClIonic chloride salts reaction with other salts to exchange anions; the presence of chloride is detected by its formation of an insoluble silver chloride upon treatment with silver ion: Cl− + Ag+ → AgClThe concentration of chloride in an assay can be determined using a chloridometer, which detects silver ions once all chloride in the assay has precipitated via this reaction. Chlorided silver electrodes are used in ex vivo electrophysiology. An example is table salt, sodium chloride with the chemical formula NaCl. In water, it dissociates into Na Cl − ions. Salts such as calcium chloride, magnesium chloride, potassium chloride have varied uses ranging from medical treatments to cement formation. Calcium chloride is a salt, marketed in pellet form for removing dampness from rooms.
Calcium chloride is used for maintaining unpaved roads and for fortifying roadbases for new construction. In addition, calcium chloride is used as a de-icer, since it is effective in lowering the melting point when applied to ice. Examples of covalently bonded chlorides are phosphorus trichloride, phosphorus pentachloride, thionyl chloride, all three of which are reactive chlorinating reagents that have been used in a laboratory. Chlorine can assume oxidation states of −1, +1, +3, +5, or +7. Several neutral chlorine oxides are known. Halide Renal chloride reabsorption
Bacteria are a type of biological cell. They constitute a large domain of prokaryotic microorganisms. A few micrometres in length, bacteria have a number of shapes, ranging from spheres to rods and spirals. Bacteria were among the first life forms to appear on Earth, are present in most of its habitats. Bacteria inhabit soil, acidic hot springs, radioactive waste, the deep portions of Earth's crust. Bacteria live in symbiotic and parasitic relationships with plants and animals. Most bacteria have not been characterised, only about half of the bacterial phyla have species that can be grown in the laboratory; the study of bacteria is known as a branch of microbiology. There are 40 million bacterial cells in a gram of soil and a million bacterial cells in a millilitre of fresh water. There are 5×1030 bacteria on Earth, forming a biomass which exceeds that of all plants and animals. Bacteria are vital in many stages of the nutrient cycle by recycling nutrients such as the fixation of nitrogen from the atmosphere.
The nutrient cycle includes the decomposition of dead bodies. In the biological communities surrounding hydrothermal vents and cold seeps, extremophile bacteria provide the nutrients needed to sustain life by converting dissolved compounds, such as hydrogen sulphide and methane, to energy. Data reported by researchers in October 2012 and published in March 2013 suggested that bacteria thrive in the Mariana Trench, with a depth of up to 11 kilometres, is the deepest known part of the oceans. Other researchers reported related studies that microbes thrive inside rocks up to 580 metres below the sea floor under 2.6 kilometres of ocean off the coast of the northwestern United States. According to one of the researchers, "You can find microbes everywhere—they're adaptable to conditions, survive wherever they are."The famous notion that bacterial cells in the human body outnumber human cells by a factor of 10:1 has been debunked. There are 39 trillion bacterial cells in the human microbiota as personified by a "reference" 70 kg male 170 cm tall, whereas there are 30 trillion human cells in the body.
This means that although they do have the upper hand in actual numbers, it is only by 30%, not 900%. The largest number exist in the gut flora, a large number on the skin; the vast majority of the bacteria in the body are rendered harmless by the protective effects of the immune system, though many are beneficial in the gut flora. However several species of bacteria are pathogenic and cause infectious diseases, including cholera, anthrax and bubonic plague; the most common fatal bacterial diseases are respiratory infections, with tuberculosis alone killing about 2 million people per year in sub-Saharan Africa. In developed countries, antibiotics are used to treat bacterial infections and are used in farming, making antibiotic resistance a growing problem. In industry, bacteria are important in sewage treatment and the breakdown of oil spills, the production of cheese and yogurt through fermentation, the recovery of gold, palladium and other metals in the mining sector, as well as in biotechnology, the manufacture of antibiotics and other chemicals.
Once regarded as plants constituting the class Schizomycetes, bacteria are now classified as prokaryotes. Unlike cells of animals and other eukaryotes, bacterial cells do not contain a nucleus and harbour membrane-bound organelles. Although the term bacteria traditionally included all prokaryotes, the scientific classification changed after the discovery in the 1990s that prokaryotes consist of two different groups of organisms that evolved from an ancient common ancestor; these evolutionary domains are called Archaea. The word bacteria is the plural of the New Latin bacterium, the latinisation of the Greek βακτήριον, the diminutive of βακτηρία, meaning "staff, cane", because the first ones to be discovered were rod-shaped; the ancestors of modern bacteria were unicellular microorganisms that were the first forms of life to appear on Earth, about 4 billion years ago. For about 3 billion years, most organisms were microscopic, bacteria and archaea were the dominant forms of life. Although bacterial fossils exist, such as stromatolites, their lack of distinctive morphology prevents them from being used to examine the history of bacterial evolution, or to date the time of origin of a particular bacterial species.
However, gene sequences can be used to reconstruct the bacterial phylogeny, these studies indicate that bacteria diverged first from the archaeal/eukaryotic lineage. The most recent common ancestor of bacteria and archaea was a hyperthermophile that lived about 2.5 billion–3.2 billion years ago. Bacteria were involved in the second great evolutionary divergence, that of the archaea and eukaryotes. Here, eukaryotes resulted from the entering of ancient bacteria into endosymbiotic associations with the ancestors of eukaryotic cells, which were themselves related to the Archaea; this involved the engulfment by proto-eukaryotic cells of alphaproteobacterial symbionts to form either mitochondria or hydrogenosomes, which are still found in all known Eukarya. Some eukaryotes that contained mitochondria engulfed cyanobacteria-like organisms, leading to the formation of chloroplasts in algae and plants; this is known as primary endosymbiosis. Bacteria display a wide diversity of sizes, called morphologies.
Bacterial cells are about one-tenth the size of eukaryotic cells
A chemical substance is a form of matter having constant chemical composition and characteristic properties. It cannot be separated into components by physical separation methods, i.e. without breaking chemical bonds. Chemical substances can be chemical compounds, or alloys. Chemical elements may not be included in the definition, depending on expert viewpoint. Chemical substances are called'pure' to set them apart from mixtures. A common example of a chemical substance is pure water. Other chemical substances encountered in pure form are diamond, table salt and refined sugar. However, in practice, no substance is pure, chemical purity is specified according to the intended use of the chemical. Chemical substances exist as solids, gases, or plasma, may change between these phases of matter with changes in temperature or pressure. Chemical substances may be converted to others by means of chemical reactions. Forms of energy, such as light and heat, are not matter, are thus not "substances" in this regard.
A chemical substance may well be defined as "any material with a definite chemical composition" in an introductory general chemistry textbook. According to this definition a chemical substance can either be a pure chemical element or a pure chemical compound. But, there are exceptions to this definition; the chemical substance index published by CAS includes several alloys of uncertain composition. Non-stoichiometric compounds are a special case that violates the law of constant composition, for them, it is sometimes difficult to draw the line between a mixture and a compound, as in the case of palladium hydride. Broader definitions of chemicals or chemical substances can be found, for example: "the term'chemical substance' means any organic or inorganic substance of a particular molecular identity, including – any combination of such substances occurring in whole or in part as a result of a chemical reaction or occurring in nature". In geology, substances of uniform composition are called minerals, while physical mixtures of several minerals are defined as rocks.
Many minerals, mutually dissolve into solid solutions, such that a single rock is a uniform substance despite being a mixture in stoichiometric terms. Feldspars are a common example: anorthoclase is an alkali aluminum silicate, where the alkali metal is interchangeably either sodium or potassium. In law, "chemical substances" may include both pure substances and mixtures with a defined composition or manufacturing process. For example, the EU regulation REACH defines "monoconstituent substances", "multiconstituent substances" and "substances of unknown or variable composition"; the latter two consist of multiple chemical substances. For example, charcoal is an complex polymeric mixture that can be defined by its manufacturing process. Therefore, although the exact chemical identity is unknown, identification can be made to a sufficient accuracy; the CAS index includes mixtures. Polymers always appear as mixtures of molecules of multiple molar masses, each of which could be considered a separate chemical substance.
However, the polymer may be defined by a known precursor or reaction and the molar mass distribution. For example, polyethylene is a mixture of long chains of -CH2- repeating units, is sold in several molar mass distributions, LDPE, MDPE, HDPE and UHMWPE; the concept of a "chemical substance" became established in the late eighteenth century after work by the chemist Joseph Proust on the composition of some pure chemical compounds such as basic copper carbonate. He deduced; this is now known as the law of constant composition. With the advancement of methods for chemical synthesis in the realm of organic chemistry. However, there are some controversies regarding this definition because the large number of chemical substances reported in chemistry literature need to be indexed. Isomerism caused much consternation to early researchers, since isomers have the same composition, but differ in configuration of the atoms. For example, there was much speculation for the chemical identity of benzene, until the correct structure was described by Friedrich August Kekulé.
The idea of stereoisomerism – that atoms have rigid three-dimensional structure and can thus form isomers that differ only in their three-dimensional arrangement – was another crucial step in understanding the concept of distinct chemical substances. For example, tartaric acid has three distinct isomers, a pair of diastereomers with one diastereomer forming two enantiomers. An element is a chemical substance made up of a particular kind of atom and hence cannot be broken down or transformed by a chemical reaction into a different element, though it can be transmuted into another element through a nuclear reaction; this is so, beca
Nines are an informal, yet common method of grading the purity of materials. Fine precious metals such as platinum and silver. Based on the system of millesimal fineness, a metal is said to be one nine or one nine fine if it is 900 fine, or 90% pure. A metal, 990 fine is described as two nines fine and one, 999 fine is described as three nines fine. Thus, nines are a logarithmic scale of purity for fine precious metals. Percentages ending in a 5 have conventional names, traditionally the number of nines "five", so 999.5 fine is "three nines five", abbreviated 3N5. The nines scale is sometimes used in describing the purity of bottled gases; the purity of gas is an indication of the amount of other gases. A high purity refers to a low amount of other gases. Gases of higher purity are considered to be of better quality and are more expensive; the purity of a gas is expressed as a grade prefixed with the letter N giving the "number of nines" in the percentage or decimal fraction. For gasses, the number of nines is written after the letter N, rather than before it.
An N2.0 gas is 99% pure, 1% impurities. An N6.0 gas is 99.9999% pure, with 1 part per million impurities. Intermediate values are formed using the common logarithm. For example, a gas, 99.97% pure would be described as N3.5, since log10 = −3.523. Nines are used in a similar manner to describe computer system availability. Parts-per notation 0.999
Fehling's solution is a chemical reagent used to differentiate between water-soluble carbohydrate and ketone functional groups, as a test for reducing sugars and non-reducing sugars, supplementary to the Tollens' reagent test. The test was developed by German chemist Hermann von Fehling in 1849. Fehling's solution is prepared by combining two separate solutions, known as Fehling's A and Fehling's B. Fehling's A is aqueous solution of copper sulphate, deep blue. Fehling's B is a colorless solution of aqueous potassium sodium tartrate made in a strong alkali with sodium hydroxide; the L-tartrate salt is used. The copper complex in Fehling's solution is the active reagent in the test; the deep blue active ingredient in Fehling's solution is the bis complex of Cu2+. The tartrate tetraanions serve as bidentate alkoxide ligands. Preparation of Fehling’s reagent: It is a mixture of copper sulphate solution and alkaline sodium-potassium tartrate solution; the solutions A and B are prepared as described below.'Solution A': Dissolve 34.65 g of copper sulphate in 400 ml of distilled water and make the final volume 500 ml with distilled water.
Solution B: Dissolve 125 g of KOH and 173 g of sodium-potassium tartrate in 400 ml of distilled water and make the final volume 500 ml with distilled water. Both solutions A & B are stored in rubber stoppered bottles. Whenever required, the Fehling’s reagent is prepared fresh by mixing equal volumes of solution A and B. Fehling's solution can be used to distinguish aldehyde vs ketone functional groups; the compound to be tested is added to the Fehling's solution and the mixture is heated. Aldehydes are oxidized, giving a positive result, but ketones do not react, unless they are alpha-hydroxy-ketones; the bistartratocuprate complex oxidizes the aldehyde to a carboxylate anion, in the process the copper ions of the complex are reduced to copper ions. Red copper oxide precipitates out of the reaction mixture, which indicates a positive result i.e. that redox has taken place. A negative result is the absence of the red precipitate. Fehling's test can be used as a generic test for other reducing sugars.
It will give a positive result for aldose monosaccharides but for ketose monosaccharides, as they are converted to aldoses by the base in the reagent, give a positive result. Fehling's can be used thus detecting diabetes. Another use is in the breakdown of starch to convert it to glucose syrup and maltodextrins in order to measure the amount of reducing sugar, thus revealing the dextrose equivalent of the starch sugar. Formic acid gives a positive Fehling's test result, as it does with Tollens' test and Benedict's test also; the positive tests are consistent with it being oxidizable to carbon dioxide. The net reaction between an aldehyde and the copper ions in Fehling's solution may be written as: RCHO + 2 Cu2+ + 5 OH− → RCOO− + Cu2O + 3 H2Oor with the tartrate included: RCHO + 2 Cu22− + 5 OH− → RCOO− + Cu2O + 4 C4H4O62− + 3 H2O Sodium hydroxide is corrosive. Tollens' reagent Benedict's reagent Barfoed's test "Fehling's Solution". Collier's New Encyclopedia. 1921
American Chemical Society
The American Chemical Society is a scientific society based in the United States that supports scientific inquiry in the field of chemistry. Founded in 1876 at New York University, the ACS has nearly 157,000 members at all degree levels and in all fields of chemistry, chemical engineering, related fields, it is the world's largest scientific society by membership. The ACS is a 501 non-profit organization and holds a congressional charter under Title 36 of the United States Code, its headquarters are located in Washington, D. C. and it has a large concentration of staff in Ohio. The ACS is a leading source of scientific information through its peer-reviewed scientific journals, national conferences, the Chemical Abstracts Service, its publications division produces 60 scholarly journals including the prestigious Journal of the American Chemical Society, as well as the weekly trade magazine Chemical & Engineering News. The ACS holds national meetings twice a year covering the complete field of chemistry and holds smaller conferences concentrating on specific chemical fields or geographic regions.
The primary source of income of the ACS is the Chemical Abstracts Service, a provider of chemical databases worldwide. The organization publishes textbooks, administers several national chemistry awards, provides grants for scientific research, supports various educational and outreach activities. In 1874, a group of American chemists gathered at the Joseph Priestley House to mark the 100th anniversary of Priestley's discovery of oxygen. Although there was an American scientific society at that time, the growth of chemistry in the U. S. prompted those assembled to consider founding a new society that would focus more directly on theoretical and applied chemistry. Two years on April 6, 1876, during a meeting of chemists at the University of the City of New York the American Chemical Society was founded; the society received its charter of incorporation from the State of New York in 1877. Charles F. Chandler, a professor of chemistry at Columbia University, instrumental in organizing the society said that such a body would “prove a powerful and healthy stimulus to original research, … would awaken and develop much talent now wasting in isolation, … members of the association into closer union, ensure a better appreciation of our science and its students on the part of the general public.”Although Chandler was a choice to become the society's first president because of his role in organizing the society, New York University chemistry professor John William Draper was elected as the first president of the society because of his national reputation.
Draper was a photochemist and pioneering photographer who had produced one of the first photographic portraits in 1840. Chandler would serve as president in 1881 and 1889. In the ACS logo designed in the early 20th century by Tiffany's Jewelers and used since 1909, a stylized symbol of a kaliapparat is used; the Journal of the American Chemical Society was founded in 1879 to publish original chemical research. It was the first journal published by ACS and is still the society's flagship peer-reviewed publication. In 1907, Chemical Abstracts was established as a separate journal, which became the Chemical Abstracts Service, a division of ACS that provides chemical information to researchers and others worldwide. Chemical & Engineering News is a weekly trade magazine, published by ACS since 1923; the society adopted a new constitution aimed at nationalizing the organization in 1890. In 1905, the American Chemical Society moved from New York City to Washington, D. C. ACS was reincorporated under a congressional charter in 1937.
It was granted by the U. S. Congress and signed by president Franklin D. Roosevelt. ACS's headquarters moved to its current location in downtown Washington in 1941. Notable Presidents of the American Chemical Society ACS first established technical divisions in 1908 to foster the exchange of information among scientists who work in particular fields of chemistry or professional interests. Divisional activities include organizing technical sessions at ACS meetings, publishing books and resources, administering awards and lectureships, conducting other events; the original five divisions were 1) organic chemistry, 2) industrial chemists and chemical engineers, 3) agricultural and food chemistry, 4) fertilizer chemistry, 5) physical and inorganic chemistry. As of 2016, there are 32 technical divisions of ACS; this is the largest division of the Society. It marked its 100th Anniversary in 2008; the first Chair of the Division was Edward Curtis Franklin. The Organic Division played a part in establishing Organic Syntheses, Inc. and Organic Reactions, Inc. and it maintains close ties to both organizations.
The Division's best known activities include organizing symposia at the biannual ACS National Meetings, for the purpose of recognizing promising Assistant Professors, talented young researchers, outstanding technical contributions from junior-level chemists, in the field of organic chemistry. The symposia honor national award winners, including the Arthur C. Cope Award, Cope Scholar Award, James Flack Norris Award in Physical Organic Chemistry, Herbert C. Brown Award for Creative Research in Synthetic Methods; the Division helps to organize symposia at the international meeting called Pacifichem, it organizes the biennial National Organic Chemistry Symposium which highlights recent advances in organic chemistry and hosts the Roger Adams Award address. The Division organizes corporate sponsorships to provide fellowships for Ph. D. stu
Monoclonal antibodies are antibodies that are made by identical immune cells that are all clones of a unique parent cell. Monoclonal antibodies can have monovalent affinity. In contrast, polyclonal antibodies bind to multiple epitopes and are made by several different plasma cell lineages. Bispecific monoclonal antibodies can be engineered, by increasing the therapeutic targets of one single monoclonal antibody to two epitopes. Given any substance, it is possible to produce monoclonal antibodies that bind to that substance; this has become an important tool in biochemistry, molecular biology, medicine. When used as medications, non-proprietary drug names end in -mab and many immunotherapy specialists use the word mab anacronymically; the idea of "magic bullets" was first proposed by Paul Ehrlich, who, at the beginning of the 20th century, postulated that, if a compound could be made that selectively targeted a disease-causing organism a toxin for that organism could be delivered along with the agent of selectivity.
He and Élie Metchnikoff received the 1908 Nobel Prize for Physiology or Medicine for this work, which led to an effective syphilis treatment by 1910. In the 1970s, the B-cell cancer multiple myeloma was known, it was understood. This was used to study the structure of antibodies, but it was not yet possible to produce identical antibodies specific to a given antigen. In 1975, Georges Köhler and César Milstein succeeded in making fusions of myeloma cell lines with B cells to create hybridomas that could produce antibodies, specific to known antigens and that were immortalized, they shared the Nobel Prize in Medicine in 1984 for the discovery. In 1988, Greg Winter and his team pioneered the techniques to humanize monoclonal antibodies, eliminating the reactions that many monoclonal antibodies caused in some patients. Much of the work behind production of monoclonal antibodies is rooted in the production of hybridomas, which involves identifying antigen-specific plasma/plasmablast cells that produce antibodies specific to an antigen of interest and fusing these cells with myeloma cells.
Rabbit B-cells can be used to form a rabbit hybridoma. Polyethylene glycol is used to fuse adjacent plasma membranes, but the success rate is low, so a selective medium in which only fused cells can grow is used; this is possible because myeloma cells have lost the ability to synthesize hypoxanthine-guanine-phosphoribosyl transferase, an enzyme necessary for the salvage synthesis of nucleic acids. The absence of HGPRT is not a problem for these cells unless the de novo purine synthesis pathway is disrupted. Exposing cells to aminopterin, makes them unable to use the de novo pathway and become auxotrophic for nucleic acids, thus requiring supplementation to survive; the selective culture medium is called HAT medium because it contains hypoxanthine and thymidine. This medium is selective for fused cells. Unfused myeloma cells cannot grow because they lack HGPRT and thus cannot replicate their DNA. Unfused spleen cells cannot grow indefinitely because of their limited life span. Only fused hybrid cells, referred to as hybridomas, are able to grow indefinitely in the medium because the spleen cell partner supplies HGPRT and the myeloma partner has traits that make it immortal.
This mixture of cells is diluted and clones are grown from single parent cells on microtitre wells. The antibodies secreted by the different clones are assayed for their ability to bind to the antigen or immuno-dot blot; the most productive and stable clone is selected for future use. The hybridomas can be grown indefinitely in a suitable cell culture medium, they can be injected into mice. There, they produce; the medium must be enriched during in vitro selection to further favour hybridoma growth. This can be achieved by the use of a layer of feeder fibrocyte cells or supplement medium such as briclone. Culture-media conditioned by macrophages can be used. Production in cell culture is preferred as the ascites technique is painful to the animal. Where alternate techniques exist, ascites is considered unethical. Several monoclonal antibody technologies had been developed such as phage display, single B cell culture, single cell amplification from various B cell populations and single plasma cell interrogation technologies.
Different from traditional hybridoma technology, the newer technologies use molecular biology techniques to amplify the heavy and light chains of the antibody genes by PCR and produce in either bacterial or mammalian systems with recombinant technology. One of the advantages of the new technologies is applicable to multiple animals, such as rabbit, llama and other common experimental animals in the laboratory. After obtaining either a media sample of cultured hybridomas or a sample of ascites fluid, the desired antibodies must be extracted. Cell culture sample contaminants consist of media components such as growth factors and transferrins. In contrast, the in vivo sample is to have host antibodies, nucleases, nucleic acids and viruses. In both cases, other secretions by the hybridomas such as cytokines may be present. There may be b