1.
Jmol
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Jmol is computer software for molecular modelling chemical structures in 3-dimensions. Jmol returns a 3D representation of a molecule that may be used as a teaching tool and it is written in the programming language Java, so it can run on the operating systems Windows, macOS, Linux, and Unix, if Java is installed. It is free and open-source software released under a GNU Lesser General Public License version 2.0, a standalone application and a software development kit exist that can be integrated into other Java applications, such as Bioclipse and Taverna. A popular feature is an applet that can be integrated into web pages to display molecules in a variety of ways, for example, molecules can be displayed as ball-and-stick models, space-filling models, ribbon diagrams, etc. Jmol supports a range of chemical file formats, including Protein Data Bank, Crystallographic Information File, MDL Molfile. There is also a JavaScript-only version, JSmol, that can be used on computers with no Java, the Jmol applet, among other abilities, offers an alternative to the Chime plug-in, which is no longer under active development. While Jmol has many features that Chime lacks, it does not claim to reproduce all Chime functions, most notably, Chime requires plug-in installation and Internet Explorer 6.0 or Firefox 2.0 on Microsoft Windows, or Netscape Communicator 4.8 on Mac OS9. Jmol requires Java installation and operates on a variety of platforms. For example, Jmol is fully functional in Mozilla Firefox, Internet Explorer, Opera, Google Chrome, fast and Scriptable Molecular Graphics in Web Browsers without Java3D
2.
ChEMBL
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ChEMBL or ChEMBLdb is a manually curated chemical database of bioactive molecules with drug-like properties. It is maintained by the European Bioinformatics Institute, of the European Molecular Biology Laboratory, based at the Wellcome Trust Genome Campus, Hinxton, the database, originally known as StARlite, was developed by a biotechnology company called Inpharmatica Ltd. later acquired by Galapagos NV. The data was acquired for EMBL in 2008 with an award from The Wellcome Trust, resulting in the creation of the ChEMBL chemogenomics group at EMBL-EBI, the ChEMBL database contains compound bioactivity data against drug targets. Bioactivity is reported in Ki, Kd, IC50, and EC50, data can be filtered and analyzed to develop compound screening libraries for lead identification during drug discovery. ChEMBL version 2 was launched in January 2010, including 2.4 million bioassay measurements covering 622,824 compounds and this was obtained from curating over 34,000 publications across twelve medicinal chemistry journals. ChEMBLs coverage of available bioactivity data has grown to become the most comprehensive ever seen in a public database, in October 2010 ChEMBL version 8 was launched, with over 2.97 million bioassay measurements covering 636,269 compounds. ChEMBL_10 saw the addition of the PubChem confirmatory assays, in order to integrate data that is comparable to the type, ChEMBLdb can be accessed via a web interface or downloaded by File Transfer Protocol. It is formatted in a manner amenable to computerized data mining, ChEMBL is also integrated into other large-scale chemistry resources, including PubChem and the ChemSpider system of the Royal Society of Chemistry. In addition to the database, the ChEMBL group have developed tools and these include Kinase SARfari, an integrated chemogenomics workbench focussed on kinases. The system incorporates and links sequence, structure, compounds and screening data, the primary purpose of ChEMBL-NTD is to provide a freely accessible and permanent archive and distribution centre for deposited data. July 2012 saw the release of a new data service, sponsored by the Medicines for Malaria Venture. The data in this service includes compounds from the Malaria Box screening set, myChEMBL, the ChEMBL virtual machine, was released in October 2013 to allow users to access a complete and free, easy-to-install cheminformatics infrastructure. In December 2013, the operations of the SureChem patent informatics database were transferred to EMBL-EBI, in a portmanteau, SureChem was renamed SureChEMBL. 2014 saw the introduction of the new resource ADME SARfari - a tool for predicting and comparing cross-species ADME targets
3.
ChemSpider
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ChemSpider is a database of chemicals. ChemSpider is owned by the Royal Society of Chemistry, the database contains information on more than 50 million molecules from over 500 data sources including, Each chemical is given a unique identifier, which forms part of a corresponding URL. This is an approach to develop an online chemistry database. The search can be used to widen or restrict already found results, structure searching on mobile devices can be done using free apps for iOS and for the Android. The ChemSpider database has been used in combination with text mining as the basis of document markup. The result is a system between chemistry documents and information look-up via ChemSpider into over 150 data sources. ChemSpider was acquired by the Royal Society of Chemistry in May,2009, prior to the acquisition by RSC, ChemSpider was controlled by a private corporation, ChemZoo Inc. The system was first launched in March 2007 in a release form. ChemSpider has expanded the generic support of a database to include support of the Wikipedia chemical structure collection via their WiChempedia implementation. A number of services are available online. SyntheticPages is an interactive database of synthetic chemistry procedures operated by the Royal Society of Chemistry. Users submit synthetic procedures which they have conducted themselves for publication on the site and these procedures may be original works, but they are more often based on literature reactions. Citations to the published procedure are made where appropriate. They are checked by an editor before posting. The pages do not undergo formal peer-review like a journal article. The comments are moderated by scientific editors. The intention is to collect practical experience of how to conduct useful chemical synthesis in the lab, while experimental methods published in an ordinary academic journal are listed formally and concisely, the procedures in ChemSpider SyntheticPages are given with more practical detail. Comments by submitters are included as well, other publications with comparable amounts of detail include Organic Syntheses and Inorganic Syntheses
4.
European Chemicals Agency
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ECHA is the driving force among regulatory authorities in implementing the EUs chemicals legislation. ECHA helps companies to comply with the legislation, advances the safe use of chemicals, provides information on chemicals and it is located in Helsinki, Finland. The Agency, headed by Executive Director Geert Dancet, started working on 1 June 2007, the REACH Regulation requires companies to provide information on the hazards, risks and safe use of chemical substances that they manufacture or import. Companies register this information with ECHA and it is freely available on their website. So far, thousands of the most hazardous and the most commonly used substances have been registered, the information is technical but gives detail on the impact of each chemical on people and the environment. This also gives European consumers the right to ask whether the goods they buy contain dangerous substances. The Classification, Labelling and Packaging Regulation introduces a globally harmonised system for classifying and labelling chemicals into the EU. This worldwide system makes it easier for workers and consumers to know the effects of chemicals, companies need to notify ECHA of the classification and labelling of their chemicals. So far, ECHA has received over 5 million notifications for more than 100000 substances, the information is freely available on their website. Consumers can check chemicals in the products they use, Biocidal products include, for example, insect repellents and disinfectants used in hospitals. The Biocidal Products Regulation ensures that there is information about these products so that consumers can use them safely. ECHA is responsible for implementing the regulation, the law on Prior Informed Consent sets guidelines for the export and import of hazardous chemicals. Through this mechanism, countries due to hazardous chemicals are informed in advance and have the possibility of rejecting their import. Substances that may have effects on human health and the environment are identified as Substances of Very High Concern 1. These are mainly substances which cause cancer, mutation or are toxic to reproduction as well as substances which persist in the body or the environment, other substances considered as SVHCs include, for example, endocrine disrupting chemicals. Companies manufacturing or importing articles containing these substances in a concentration above 0 and they are required to inform users about the presence of the substance and therefore how to use it safely. Consumers have the right to ask the retailer whether these substances are present in the products they buy, once a substance has been officially identified in the EU as being of very high concern, it will be added to a list. This list is available on ECHA’s website and shows consumers and industry which chemicals are identified as SVHCs, Substances placed on the Candidate List can then move to another list
5.
E number
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E numbers are codes for substances that are permitted to be used as food additives for use within the European Union and Switzerland. Commonly found on labels, their safety assessment and approval are the responsibility of the European Food Safety Authority. Having a single unified list for food additives was first agreed upon in 1962 with food colouring, in 1964, the directives for preservatives were added,1970 for antioxidants and 1974 for the emulsifiers, stabilisers, thickeners and gelling agents. They are increasingly, though rarely, found on North American packaging. In some European countries, E number is used informally as a pejorative term for artificial food additives. This is incorrect, because many components of foods have E numbers, e. g. vitamin C. NB, Not all examples of a fall into the given numeric range. Moreover, many chemicals, particularly in the E400–499 range, have a variety of purposes, the list shows all components that have or had an E-number assigned. Not all additives listed are still allowed in the EU, but are listed as they used to have an E-number, for an overview of currently allowed additives see here. Includes Lists of authorised food additives Food additives database
6.
PubChem
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PubChem is a database of chemical molecules and their activities against biological assays. The system is maintained by the National Center for Biotechnology Information, a component of the National Library of Medicine, PubChem can be accessed for free through a web user interface. Millions of compound structures and descriptive datasets can be downloaded via FTP. PubChem contains substance descriptions and small molecules with fewer than 1000 atoms and 1000 bonds, more than 80 database vendors contribute to the growing PubChem database. PubChem consists of three dynamically growing primary databases, as of 28 January 2016, Compounds,82.6 million entries, contains pure and characterized chemical compounds. Substances,198 million entries, contains also mixtures, extracts, complexes, bioAssay, bioactivity results from 1.1 million high-throughput screening programs with several million values. PubChem contains its own online molecule editor with SMILES/SMARTS and InChI support that allows the import and export of all common chemical file formats to search for structures and fragments. In the text search form the database fields can be searched by adding the name in square brackets to the search term. A numeric range is represented by two separated by a colon. The search terms and field names are case-insensitive, parentheses and the logical operators AND, OR, and NOT can be used. AND is assumed if no operator is used, example,0,5000,50,10 -5,5 PubChem was released in 2004. The American Chemical Society has raised concerns about the publicly supported PubChem database and they have a strong interest in the issue since the Chemical Abstracts Service generates a large percentage of the societys revenue. To advocate their position against the PubChem database, ACS has actively lobbied the US Congress, soon after PubChems creation, the American Chemical Society lobbied U. S. Congress to restrict the operation of PubChem, which they asserted competes with their Chemical Abstracts Service
7.
International Chemical Identifier
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Initially developed by IUPAC and NIST from 2000 to 2005, the format and algorithms are non-proprietary. The continuing development of the standard has supported since 2010 by the not-for-profit InChI Trust. The current version is 1.04 and was released in September 2011, prior to 1.04, the software was freely available under the open source LGPL license, but it now uses a custom license called IUPAC-InChI Trust License. Not all layers have to be provided, for instance, the layer can be omitted if that type of information is not relevant to the particular application. InChIs can thus be seen as akin to a general and extremely formalized version of IUPAC names and they can express more information than the simpler SMILES notation and differ in that every structure has a unique InChI string, which is important in database applications. Information about the 3-dimensional coordinates of atoms is not represented in InChI, the InChI algorithm converts input structural information into a unique InChI identifier in a three-step process, normalization, canonicalization, and serialization. The InChIKey, sometimes referred to as a hashed InChI, is a fixed length condensed digital representation of the InChI that is not human-understandable. The InChIKey specification was released in September 2007 in order to facilitate web searches for chemical compounds and it should be noted that, unlike the InChI, the InChIKey is not unique, though collisions can be calculated to be very rare, they happen. In January 2009 the final 1.02 version of the InChI software was released and this provided a means to generate so called standard InChI, which does not allow for user selectable options in dealing with the stereochemistry and tautomeric layers of the InChI string. The standard InChIKey is then the hashed version of the standard InChI string, the standard InChI will simplify comparison of InChI strings and keys generated by different groups, and subsequently accessed via diverse sources such as databases and web resources. Every InChI starts with the string InChI= followed by the version number and this is followed by the letter S for standard InChIs. The remaining information is structured as a sequence of layers and sub-layers, the layers and sub-layers are separated by the delimiter / and start with a characteristic prefix letter. The six layers with important sublayers are, Main layer Chemical formula and this is the only sublayer that must occur in every InChI. The atoms in the formula are numbered in sequence, this sublayer describes which atoms are connected by bonds to which other ones. Describes how many hydrogen atoms are connected to each of the other atoms, the condensed,27 character standard InChIKey is a hashed version of the full standard InChI, designed to allow for easy web searches of chemical compounds. Most chemical structures on the Web up to 2007 have been represented as GIF files, the full InChI turned out to be too lengthy for easy searching, and therefore the InChIKey was developed. With all databases currently having below 50 million structures, such duplication appears unlikely at present, a recent study more extensively studies the collision rate finding that the experimental collision rate is in agreement with the theoretical expectations. Example, Morphine has the structure shown on the right, as the InChI cannot be reconstructed from the InChIKey, an InChIKey always needs to be linked to the original InChI to get back to the original structure
8.
Simplified molecular-input line-entry system
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The simplified molecular-input line-entry system is a specification in form of a line notation for describing the structure of chemical species using short ASCII strings. SMILES strings can be imported by most molecule editors for conversion back into two-dimensional drawings or three-dimensional models of the molecules, the original SMILES specification was initiated in the 1980s. It has since modified and extended. In 2007, a standard called OpenSMILES was developed in the open-source chemistry community. Other linear notations include the Wiswesser Line Notation, ROSDAL and SLN, the original SMILES specification was initiated by David Weininger at the USEPA Mid-Continent Ecology Division Laboratory in Duluth in the 1980s. The Environmental Protection Agency funded the project to develop SMILES. It has since modified and extended by others, most notably by Daylight Chemical Information Systems. In 2007, a standard called OpenSMILES was developed by the Blue Obelisk open-source chemistry community. Other linear notations include the Wiswesser Line Notation, ROSDAL and SLN, in July 2006, the IUPAC introduced the InChI as a standard for formula representation. SMILES is generally considered to have the advantage of being slightly more human-readable than InChI, the term SMILES refers to a line notation for encoding molecular structures and specific instances should strictly be called SMILES strings. However, the term SMILES is also used to refer to both a single SMILES string and a number of SMILES strings, the exact meaning is usually apparent from the context. The terms canonical and isomeric can lead to confusion when applied to SMILES. The terms describe different attributes of SMILES strings and are not mutually exclusive, typically, a number of equally valid SMILES strings can be written for a molecule. For example, CCO, OCC and CC all specify the structure of ethanol, algorithms have been developed to generate the same SMILES string for a given molecule, of the many possible strings, these algorithms choose only one of them. This SMILES is unique for each structure, although dependent on the algorithm used to generate it. These algorithms first convert the SMILES to a representation of the molecular structure. A common application of canonical SMILES is indexing and ensuring uniqueness of molecules in a database, there is currently no systematic comparison across commercial software to test if such flaws exist in those packages. SMILES notation allows the specification of configuration at tetrahedral centers, and these are structural features that cannot be specified by connectivity alone and SMILES which encode this information are termed isomeric SMILES
9.
Chemical formula
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These are limited to a single typographic line of symbols, which may include subscripts and superscripts. A chemical formula is not a name, and it contains no words. Although a chemical formula may imply certain simple chemical structures, it is not the same as a full chemical structural formula. Chemical formulas can fully specify the structure of only the simplest of molecules and chemical substances, the simplest types of chemical formulas are called empirical formulas, which use letters and numbers indicating the numerical proportions of atoms of each type. Molecular formulas indicate the numbers of each type of atom in a molecule. For example, the formula for glucose is CH2O, while its molecular formula is C6H12O6. This is possible if the relevant bonding is easy to show in one dimension, an example is the condensed molecular/chemical formula for ethanol, which is CH3-CH2-OH or CH3CH2OH. For reasons of structural complexity, there is no condensed chemical formula that specifies glucose, chemical formulas may be used in chemical equations to describe chemical reactions and other chemical transformations, such as the dissolving of ionic compounds into solution. A chemical formula identifies each constituent element by its chemical symbol, in empirical formulas, these proportions begin with a key element and then assign numbers of atoms of the other elements in the compound, as ratios to the key element. For molecular compounds, these numbers can all be expressed as whole numbers. For example, the formula of ethanol may be written C2H6O because the molecules of ethanol all contain two carbon atoms, six hydrogen atoms, and one oxygen atom. Some types of compounds, however, cannot be written with entirely whole-number empirical formulas. An example is boron carbide, whose formula of CBn is a variable non-whole number ratio with n ranging from over 4 to more than 6.5. When the chemical compound of the consists of simple molecules. These types of formulas are known as molecular formulas and condensed formulas. A molecular formula enumerates the number of atoms to reflect those in the molecule, so that the formula for glucose is C6H12O6 rather than the glucose empirical formula. However, except for very simple substances, molecular chemical formulas lack needed structural information, for simple molecules, a condensed formula is a type of chemical formula that may fully imply a correct structural formula. For example, ethanol may be represented by the chemical formula CH3CH2OH
10.
Density
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The density, or more precisely, the volumetric mass density, of a substance is its mass per unit volume. The symbol most often used for density is ρ, although the Latin letter D can also be used. Mathematically, density is defined as mass divided by volume, ρ = m V, where ρ is the density, m is the mass, and V is the volume. In some cases, density is defined as its weight per unit volume. For a pure substance the density has the numerical value as its mass concentration. Different materials usually have different densities, and density may be relevant to buoyancy, purity, osmium and iridium are the densest known elements at standard conditions for temperature and pressure but certain chemical compounds may be denser. Thus a relative density less than one means that the floats in water. The density of a material varies with temperature and pressure and this variation is typically small for solids and liquids but much greater for gases. Increasing the pressure on an object decreases the volume of the object, increasing the temperature of a substance decreases its density by increasing its volume. In most materials, heating the bottom of a results in convection of the heat from the bottom to the top. This causes it to rise relative to more dense unheated material, the reciprocal of the density of a substance is occasionally called its specific volume, a term sometimes used in thermodynamics. Density is a property in that increasing the amount of a substance does not increase its density. Archimedes knew that the irregularly shaped wreath could be crushed into a cube whose volume could be calculated easily and compared with the mass, upon this discovery, he leapt from his bath and ran naked through the streets shouting, Eureka. As a result, the term eureka entered common parlance and is used today to indicate a moment of enlightenment, the story first appeared in written form in Vitruvius books of architecture, two centuries after it supposedly took place. Some scholars have doubted the accuracy of this tale, saying among other things that the method would have required precise measurements that would have been difficult to make at the time, from the equation for density, mass density has units of mass divided by volume. As there are units of mass and volume covering many different magnitudes there are a large number of units for mass density in use. The SI unit of kilogram per metre and the cgs unit of gram per cubic centimetre are probably the most commonly used units for density.1,000 kg/m3 equals 1 g/cm3. In industry, other larger or smaller units of mass and or volume are often more practical, see below for a list of some of the most common units of density
11.
Melting point
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The melting point of a solid is the temperature at which it changes state from solid to liquid at atmospheric pressure. At the melting point the solid and liquid phase exist in equilibrium, the melting point of a substance depends on pressure and is usually specified at standard pressure. When considered as the temperature of the change from liquid to solid. Because of the ability of some substances to supercool, the point is not considered as a characteristic property of a substance. For most substances, melting and freezing points are approximately equal, for example, the melting point and freezing point of mercury is 234.32 kelvins. However, certain substances possess differing solid-liquid transition temperatures, for example, agar melts at 85 °C and solidifies from 31 °C to 40 °C, such direction dependence is known as hysteresis. The melting point of ice at 1 atmosphere of pressure is close to 0 °C. In the presence of nucleating substances the freezing point of water is the same as the melting point, the chemical element with the highest melting point is tungsten, at 3687 K, this property makes tungsten excellent for use as filaments in light bulbs. Many laboratory techniques exist for the determination of melting points, a Kofler bench is a metal strip with a temperature gradient. Any substance can be placed on a section of the strip revealing its thermal behaviour at the temperature at that point, differential scanning calorimetry gives information on melting point together with its enthalpy of fusion. A basic melting point apparatus for the analysis of crystalline solids consists of an oil bath with a transparent window, the several grains of a solid are placed in a thin glass tube and partially immersed in the oil bath. The oil bath is heated and with the aid of the melting of the individual crystals at a certain temperature can be observed. In large/small devices, the sample is placed in a heating block, the measurement can also be made continuously with an operating process. For instance, oil refineries measure the point of diesel fuel online, meaning that the sample is taken from the process. This allows for more frequent measurements as the sample does not have to be manually collected, for refractory materials the extremely high melting point may be determined by heating the material in a black body furnace and measuring the black-body temperature with an optical pyrometer. For the highest melting materials, this may require extrapolation by several hundred degrees, the spectral radiance from an incandescent body is known to be a function of its temperature. An optical pyrometer matches the radiance of a body under study to the radiance of a source that has been previously calibrated as a function of temperature, in this way, the measurement of the absolute magnitude of the intensity of radiation is unnecessary. However, known temperatures must be used to determine the calibration of the pyrometer, for temperatures above the calibration range of the source, an extrapolation technique must be employed
12.
Boiling point
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The boiling point of a substance is the temperature at which the vapor pressure of the liquid equals the pressure surrounding the liquid and the liquid changes into a vapor. The boiling point of a liquid varies depending upon the environmental pressure. A liquid in a vacuum has a lower boiling point than when that liquid is at atmospheric pressure. A liquid at high pressure has a boiling point than when that liquid is at atmospheric pressure. For a given pressure, different liquids boil at different temperatures, for example, water boils at 100 °C at sea level, but at 93.4 °C at 2,000 metres altitude. The normal boiling point of a liquid is the case in which the vapor pressure of the liquid equals the defined atmospheric pressure at sea level,1 atmosphere. At that temperature, the pressure of the liquid becomes sufficient to overcome atmospheric pressure. The standard boiling point has been defined by IUPAC since 1982 as the temperature at which boiling occurs under a pressure of 1 bar, the heat of vaporization is the energy required to transform a given quantity of a substance from a liquid into a gas at a given pressure. Liquids may change to a vapor at temperatures below their boiling points through the process of evaporation, evaporation is a surface phenomenon in which molecules located near the liquids edge, not contained by enough liquid pressure on that side, escape into the surroundings as vapor. On the other hand, boiling is a process in which molecules anywhere in the liquid escape, a saturated liquid contains as much thermal energy as it can without boiling. The saturation temperature is the temperature for a corresponding saturation pressure at which a liquid boils into its vapor phase, the liquid can be said to be saturated with thermal energy. Any addition of energy results in a phase transition. If the pressure in a system remains constant, a vapor at saturation temperature will begin to condense into its liquid phase as thermal energy is removed, similarly, a liquid at saturation temperature and pressure will boil into its vapor phase as additional thermal energy is applied. The boiling point corresponds to the temperature at which the pressure of the liquid equals the surrounding environmental pressure. Thus, the point is dependent on the pressure. Boiling points may be published with respect to the NIST, USA standard pressure of 101.325 kPa, at higher elevations, where the atmospheric pressure is much lower, the boiling point is also lower. The boiling point increases with increased pressure up to the critical point, the boiling point cannot be increased beyond the critical point. Likewise, the point decreases with decreasing pressure until the triple point is reached
13.
Aqueous solution
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An aqueous solution is a solution in which the solvent is water. It is usually shown in chemical equations by appending to the relevant chemical formula, for example, a solution of table salt, or sodium chloride, in water would be represented as Na+ + Cl−. The word aqueous means pertaining to, related to, similar to, as water is an excellent solvent and is also naturally abundant, it is a ubiquitous solvent in chemistry. Substances that are hydrophobic often do not dissolve well in water, an example of a hydrophilic substance is sodium chloride. Acids and bases are aqueous solutions, as part of their Arrhenius definitions, the ability of a substance to dissolve in water is determined by whether the substance can match or exceed the strong attractive forces that water molecules generate between themselves. If the substance lacks the ability to dissolve in water the molecules form a precipitate, reactions in aqueous solutions are usually metathesis reactions. Metathesis reactions are another term for double-displacement, that is, when a cation displaces to form a bond with the other anion. The cation bonded with the latter anion will dissociate and bond with the other anion, aqueous solutions that conduct electric current efficiently contain strong electrolytes, while ones that conduct poorly are considered to have weak electrolytes. Those strong electrolytes are substances that are ionized in water. Nonelectrolytes are substances that dissolve in water yet maintain their molecular integrity, examples include sugar, urea, glycerol, and methylsulfonylmethane. When writing the equations of reactions, it is essential to determine the precipitate. To determine the precipitate, one must consult a chart of solubility, soluble compounds are aqueous, while insoluble compounds are the precipitate. Remember that there may not always be a precipitate, when performing calculations regarding the reacting of one or more aqueous solutions, in general one must know the concentration, or molarity, of the aqueous solutions. Solution concentration is given in terms of the form of the prior to it dissolving. Metal ions in aqueous solution Solubility Dissociation Acid-base reaction theories Properties of water Zumdahl S.1997, 4th ed. Boston, Houghton Mifflin Company
14.
Alkane
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In organic chemistry, an alkane, or paraffin, is an acyclic saturated hydrocarbon. In other words, an alkane consists of hydrogen and carbon atoms arranged in a structure in which all the carbon-carbon bonds are single. Alkanes have the chemical formula CnH2n+2. The alkanes range in complexity from the simplest case of methane, CH4 where n =1, in an alkane, each carbon atom has 4 bonds, and each hydrogen atom is joined to one of the carbon atoms. The longest series of linked carbon atoms in a molecule is known as its skeleton or carbon backbone. The number of atoms may be thought of as the size of the alkane. One group of the alkanes are waxes, solids at standard ambient temperature and pressure. They can be viewed as molecular trees upon which can be hung the more functional groups of biological molecules. The alkanes have two main sources, petroleum and natural gas. Saturated hydrocarbons are hydrocarbons having only single covalent bonds between their carbons, according to the definition by IUPAC, the former two are alkanes, whereas the third group is called cycloalkanes. Saturated hydrocarbons can also combine any of the linear, cyclic and branching structures, the formula is CnH 2n−2k+2. Alkanes are the ones, corresponding to k =0. Alkanes with more than three carbon atoms can be arranged in different ways, forming structural isomers. The simplest isomer of an alkane is the one in which the atoms are arranged in a single chain with no branches. This isomer is called the n-isomer. However the chain of atoms may also be branched at one or more points. The number of possible isomers increases rapidly with the number of carbon atoms, for example, 3-methylhexane and its higher homologues are chiral due to their stereogenic center at carbon atom number 3. In addition to the alkane isomers, the chain of atoms may form one or more loops
15.
Sugar alcohol
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Sugar alcohols are organic compounds, typically derived from sugars, that comprise a class of polyols. Contrary to what the name may suggest, an alcohol is neither a sugar nor an alcoholic beverage. They are white, water-soluble solids that can occur naturally or be produced industrially from sugars and they are used widely in the food industry as thickeners and sweeteners. In commercial foodstuffs, sugar alcohols are used in place of table sugar. Xylitol is perhaps the most popular sugar alcohol due to its similarity to sucrose in visual appearance, sugar alcohols have the general formula HOCH2nCH2OH. In contrast, sugars have two hydrogen atoms, for example HOCH2nCHO or HOCH2n−1CCH2OH. The sugar alcohols differ in chain length, most have five- or six-carbon chains, because they are derived from pentoses and hexoses, respectively. They have one OH group attached to each carbon and they are further differentiated by the relative orientation of these OH groups. Unlike sugars, which tend to exist as rings, sugar alcohols do not and they can however be dehydrated to give cyclic ethers, e. g. sorbitol can be dehydrated to isosorbide. Sugar alcohols occur naturally and at one time, mannitol was obtained from natural sources, today, they are often obtained by hydrogenation of sugars, using Raney nickel catalysts. The conversion of glucose and mannose to sorbitol and mannitol is given, xylitol and lacticol are obtained similarly. Erythritol on the hand is obtained by fermentation of glucose and sucrose. Sugar alcohols do not contribute to tooth decay, consumption of sugar alcohols affects blood sugar levels, although less than of sucrose. Sugar alcohols, with the exception of erythritol, may cause bloating. The simplest sugar alcohol, ethylene glycol, is sweet but notoriously toxic, the more complex sugar alcohols are for the most part nontoxic. As a group, sugar alcohols are not as sweet as sucrose and their flavor is like sucrose, and they can be used to mask the unpleasant aftertastes of some high intensity sweeteners. Sugar alcohols are not metabolized by bacteria, and so they do not contribute to tooth decay. They do not brown or caramelize when heated, in addition to their sweetness, some sugar alcohols can produce a noticeable cooling sensation in the mouth when highly concentrated, for instance in sugar-free hard candy or chewing gum
16.
Ancient Greek
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Ancient Greek includes the forms of Greek used in ancient Greece and the ancient world from around the 9th century BC to the 6th century AD. It is often divided into the Archaic period, Classical period. It is antedated in the second millennium BC by Mycenaean Greek, the language of the Hellenistic phase is known as Koine. Koine is regarded as a historical stage of its own, although in its earliest form it closely resembled Attic Greek. Prior to the Koine period, Greek of the classic and earlier periods included several regional dialects, Ancient Greek was the language of Homer and of fifth-century Athenian historians, playwrights, and philosophers. It has contributed many words to English vocabulary and has been a subject of study in educational institutions of the Western world since the Renaissance. This article primarily contains information about the Epic and Classical phases of the language, Ancient Greek was a pluricentric language, divided into many dialects. The main dialect groups are Attic and Ionic, Aeolic, Arcadocypriot, some dialects are found in standardized literary forms used in literature, while others are attested only in inscriptions. There are also several historical forms, homeric Greek is a literary form of Archaic Greek used in the epic poems, the Iliad and Odyssey, and in later poems by other authors. Homeric Greek had significant differences in grammar and pronunciation from Classical Attic, the origins, early form and development of the Hellenic language family are not well understood because of a lack of contemporaneous evidence. Several theories exist about what Hellenic dialect groups may have existed between the divergence of early Greek-like speech from the common Proto-Indo-European language and the Classical period and they have the same general outline, but differ in some of the detail. The invasion would not be Dorian unless the invaders had some relationship to the historical Dorians. The invasion is known to have displaced population to the later Attic-Ionic regions, the Greeks of this period believed there were three major divisions of all Greek people—Dorians, Aeolians, and Ionians, each with their own defining and distinctive dialects. Often non-west is called East Greek, Arcadocypriot apparently descended more closely from the Mycenaean Greek of the Bronze Age. Boeotian had come under a strong Northwest Greek influence, and can in some respects be considered a transitional dialect, thessalian likewise had come under Northwest Greek influence, though to a lesser degree. Most of the dialect sub-groups listed above had further subdivisions, generally equivalent to a city-state and its surrounding territory, Doric notably had several intermediate divisions as well, into Island Doric, Southern Peloponnesus Doric, and Northern Peloponnesus Doric. The Lesbian dialect was Aeolic Greek and this dialect slowly replaced most of the older dialects, although Doric dialect has survived in the Tsakonian language, which is spoken in the region of modern Sparta. Doric has also passed down its aorist terminations into most verbs of Demotic Greek, by about the 6th century AD, the Koine had slowly metamorphosized into Medieval Greek
17.
Chirality (chemistry)
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Chirality /kaɪˈrælɪti/ is a geometric property of some molecules and ions. A chiral molecule/ion is non-superposable on its mirror image, the presence of an asymmetric carbon center is one of several structural features that induce chirality in organic and inorganic molecules. The term chirality is derived from the Greek word for hand, the mirror images of a chiral molecule/ion are called enantiomers or optical isomers. Individual enantiomers are often designated as either right- or left-handed, Chirality is an essential consideration when discussing the stereochemistry in organic and inorganic chemistry. The concept is of practical importance because most biomolecules and pharmaceuticals are chiral. Chirality is based on molecular symmetry elements, specifically, a chiral compound can contain no improper axis of rotation, which includes planes of symmetry and inversion center. Chiral molecules are always dissymmetric but not always asymmetric, in general, chiral molecules have point chirality at a single stereogenic atom, which has four different substituents. The two enantiomers of such compounds are said to have different absolute configurations at this center, the stereogenic atom is usually carbon, as in many biological molecules. However chirality can exist in any atom, including metals, phosphorus, Chiral nitrogen is equally possible, although the effects of nitrogen inversion can make many of these compounds impossible to isolate. While the presence of a stereogenic atom describes the great majority of cases, for instance it is not necessary for the chiral substance to have a stereogenic atom. Examples include 1-bromo-1-chloro-1-fluoroadamantane, methylethylphenyltetrahedrane, certain calixarenes and fullerenes, which have inherent chirality, the C2-symmetric species 1, 1-bi-2-naphthol,1, 3-dichloro-allene have axial chirality. -cyclooctene and many ferrocenes have planar chirality, when the optical rotation for an enantiomer is too low for practical measurement, the species is said to exhibit cryptochirality. Even isotopic differences must be considered when examining chirality, illustrative is the derivative of benzyl alcohol PhCHDOH is chiral. The S enantiomer has D = +0. 715°, many biologically active molecules are chiral, including the naturally occurring amino acids and sugars. In biological systems, most of these compounds are of the chirality, most amino acids are levorotatory. Typical naturally occurring proteins, made of L amino acids, are known as left-handed proteins, d-amino acids are very rare in nature and have only been found in small peptides attached to bacteria cell walls. The origin of this homochirality in biology is the subject of much debate, however, there is some suggestion that early amino acids could have formed in comet dust. Enzymes, which are chiral, often distinguish between the two enantiomers of a chiral substrate, one could imagine an enzyme as having a glove-like cavity that binds a substrate
18.
Isomer
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An isomer is a molecule with the same molecular formula as another molecule, but with a different chemical structure. That is, isomers contain the number of atoms of each element. Isomers do not necessarily share similar properties, unless they also have the functional groups. There are two forms of isomerism, structural isomerism and stereoisomerism. In structural isomers, sometimes referred to as constitutional isomers, the atoms, Structural isomers have different IUPAC names and may or may not belong to the same functional group. For example, two position isomers would be 2-fluoropropane and 1-fluoropropane, illustrated on the side of the diagram above. In skeletal isomers the main chain is different between the two isomers. This type of isomerism is most identifiable in secondary and tertiary alcohol isomers, tautomers are structural isomers that spontaneously interconvert with each other, even when pure. They have different chemical properties and, as a consequence, distinct reactions characteristic to each form are observed, if the interconversion reaction is fast enough, tautomers cannot be isolated from each other. An example is when they differ by the position of a proton, such as in keto/enol tautomerism, there is, however, another isomer of C3H8O that has significantly different properties, methoxyethane. Unlike the isomers of propanol, methoxyethane has an oxygen connected to two carbons rather than to one carbon and one hydrogen. Methoxyethane is an ether, not an alcohol, because it lacks a hydroxyl group, propadiene and propyne are examples of isomers containing different bond types. Propadiene contains two double bonds, whereas propyne contains one triple bond, in stereoisomers the bond structure is the same, but the geometrical positioning of atoms and functional groups in space differs. This class includes enantiomers which are non-superposable mirror-images of each other, and diastereomers, enantiomers always contain chiral centers and diastereomers often do, but there are some diastereomers that neither are chiral nor contain chiral centers. Another type of isomer, conformational isomers, may be rotamers, diastereomers, for example, ortho- position-locked biphenyl systems have enantiomers. E/Z isomers, which have restricted rotation at a bond, are configurational isomers. They are classified as diastereomers, whether or not they contain any chiral centers, e/Z notation depicts absolute stereochemistry, which is an unambiguous descriptor based on CIP priorities. Cis–trans isomers are used to describe any molecules with restricted rotation in the molecule, for molecules with C=C double bonds, these descriptors describe relative stereochemistry only based on group bulkiness or principal carbon chain, and so can be ambiguous
19.
Xylan
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Xylan is a group of hemicelluloses that are found in plant cell walls and some algae. Xylans are polysaccharides made from units of xylose, xylans are almost as ubiquitous as cellulose in plant cell walls and contain predominantly β-D-xylose units linked as in cellulose. Typically the content of xylans in hardwoods are 10 -35 % of the hemicelluloses, the main xylan component in hardwoods is O-acetyl-4-O-methylglucuronoxylan and in softwoods the main xylan components are arabino-4-O-methylglucuronoxylans. In general softwood xylans differ from hardwood xylans by the lack of acetyl groups, some macrophytic green algae contain xylan especially those within the Codium and Bryopsis genera where it replaces cellulose in the cell wall matrix. Similarly, it replaces the inner fibrillar cell-wall layer of cellulose in some red algae, xylan is one of the foremost anti-nutritional factors in common use feedstuff raw materials. Xylooligosaccharides produced from xylan are considered as food or dietary fibers. New enzymes from yeast are discovered which exclusively converts xylan into only xylooligosaccharides-DP-3 to 7
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Hemicellulose
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A hemicellulose is any of several heteropolymers, such as arabinoxylans, present along with cellulose in almost all plant cell walls. While cellulose is crystalline, strong, and resistant to hydrolysis, hemicellulose has a random and it is easily hydrolyzed by dilute acid or base as well as myriad hemicellulase enzymes. Hemicelluloses include xylan, glucuronoxylan, arabinoxylan, glucomannan, and xyloglucan and these polysaccharides contain many different sugar monomers. In contrast, cellulose contains only anhydrous glucose, for instance, besides glucose, sugar monomers in hemicellulose can include xylose, mannose, galactose, rhamnose, and arabinose. Hemicelluloses contain most of the D-pentose sugars, and occasionally small amounts of L-sugars as well, xylose is in most cases the sugar monomer present in the largest amount, although in softwoods mannose can be the most abundant sugar. Not only regular sugars can be found in hemicellulose, but also their acidified form, for instance glucuronic acid, Hemicellulose is often associated with cellulose, but it has different composition. Unlike cellulose, hemicellulose consists of shorter chains – 500–3,000 sugar units as opposed to 7, 000–15,000 glucose molecules per polymer, in addition, hemicellulose is a branched polymer, while cellulose is unbranched. Hemicelluloses are embedded in the walls of plants, sometimes in chains that form a ground - they bind with pectin to cellulose to form a network of cross-linked fibres. Hemicelluloses are synthesised from sugar nucleotides in the cells Golgi apparatus, after synthesis, hemicelluloses are transported to the plasma membrane via Golgi vesicles. As percent content of hemicellulose increases in animal feed, the voluntary feed intake decreases, Hemicellulose is represented by the difference between neutral detergent fiber and acid detergent fiber. Microfibrils are cross-linked together by hemicellulose homopolymers, lignins assist and strengthen the attachment of hemicelluloses to microfibrils. Hemicellulose found in trees is predominantly xylan with some glucomannan, while in softwoods it is mainly rich in galactoglucomannan. The average molecular weight is lower than that of cellulose at less than 30,000, cellulose Lignin Pectin Structure and Properties of Hemicellulose /David Wang’s Wood Chemistry Class
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Hardwood
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Hardwood is wood from dicot angiosperm trees. The term may also be used for the trees from which the wood is derived, in temperate and boreal latitudes they are mostly deciduous, but in tropics and subtropics mostly evergreen. Hardwood should not be confused with the heartwood, which can be from hardwood or softwood. Hardwoods are produced by trees that reproduce by flowers, and have broad leaves. Hardwood from deciduous species, such as oak, normally shows annual growth rings, hardwoods have a more complex structure than softwoods and are often much slower growing as a result. The dominant feature separating hardwoods from softwoods is the presence of pores, the vessels may show considerable variation in size, shape of perforation plates, and structure of cell wall, such as spiral thickenings. As the name suggests, the wood from trees is generally harder than that of softwoods. Solid hardwood joinery tends to be compared to softwood. In the past, tropical hardwoods were easily available, but the supply of some species, such as Burma teak, cheaper hardwood doors, for instance, now consist of a thin veneer bonded to a core of softwood, plywood or medium-density fibreboard. Hardwoods may be used in a variety of objects, but are most frequently seen in furniture or musical instruments because of their density which adds to durability, appearance, different species of hardwood lend themselves to different end uses or construction processes. This is due to the variety of characteristics apparent in different timbers, including density, grain, pore size, growth and fibre pattern, flexibility and ability to be steam bent. For example, the grain of elm wood makes it suitable for the making of chair seats where the driving in of legs. There is a correlation between density and calories/volume, list of woods Hardwood flooring Softwood Janka hardness test Brinell scale Schweingruber, F. H. Anatomie europäischer Hölzer—Anatomy of European woods. Eidgenössische Forschungsanstalt für Wald, Schnee und Landscaft, Birmensdorf, finnish Museum of Natural History, University of Helsinki. The Anatomy of Wood, Its Diversity and variability
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Xylose
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Xylose is a sugar first isolated from wood, and named for it. Xylose is classified as a monosaccharide of the type, which means that it contains five carbon atoms. It is derived from hemicellulose, one of the constituents of biomass. Like most sugars, it can adopt several structures depending on conditions, with its free carbonyl group, it is a reducing sugar. The acyclic form of xylose has chemical formula HOCH23CHO, the cyclic hemiacetal isomers are more prevalent in solution and are of two types, the pyranoses, which feature six-membered C5O rings, and the furanoses, which feature five-membered C4O rings. Each of these subject to further isomerism, depending on the relative orientation of the anomeric hydroxy group. The dextrorotary form, D-xylose, is the one that usually occurs endogenously in living things, a levorotary form, L-xylose, can be synthesized. Xylose is the building block for the hemicellulose xylan, which comprises about 30% of some plants. Xylose is otherwise pervasive, being found in the embryos of most edible plants and it was first isolated from wood by Finnish scientist, Koch, in 1881, but first became commercially viable, with a price close to sucrose, in 1930. The acid-catalysed degradation of hemicellulose gives furfural, a specialty solvent in industry, Xylose is metabolised by humans, though it is not a major human nutrient and largely excreted by the kidneys. Humans must obtain xylose from their diet, an oxido-reductase pathway is present in eukaryotic microorganisms. Humans have enzymes called protein xylosyltransferases, which transfers xylose from UDP to a serine in the protein of proteoglycans. Xylose contains 0 calories per gram, in animal medicine, xylose is used to test for malabsorption by administration in water to the patient after fasting. If xylose is detected in blood and/or urine within the few hours. In 2014 a low-temperature 50 °C, atmospheric-pressure enzyme-driven process to convert xylose into hydrogen with nearly 100% of the yield was announced. The process employs 13 enzymes, including a novel polyphosphate xylulokinase, reduction of xylose by catalytic hydrogenation produces the sugar substitute xylitol. Saccharophagus degradans Xylonic acid Xylose metabolism
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Hydrogenation
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Hydrogenation – to treat with hydrogen – is a chemical reaction between molecular hydrogen and another compound or element, usually in the presence of a catalyst such as nickel, palladium or platinum. The process is employed to reduce or saturate organic compounds. Hydrogenation typically constitutes the addition of pairs of atoms to a molecule. Catalysts are required for the reaction to be usable, non-catalytic hydrogenation takes place only at high temperatures. Hydrogenation reduces double and triple bonds in hydrocarbons and it has three components, the unsaturated substrate, the hydrogen and, invariably, a catalyst. The reduction reaction is carried out at different temperatures and pressures depending upon the substrate, the same catalysts and conditions that are used for hydrogenation reactions can also lead to isomerization of the alkenes from cis to trans. This process is of great interest because hydrogenation technology generates most of the fat in foods. A reaction where bonds are broken while hydrogen is added is called hydrogenolysis, some hydrogenations of polar bonds are accompanied by hydrogenolysis. For hydrogenation, the source of hydrogen is H2 gas itself. The hydrogenation process often uses greater than 1 atmosphere of H2, usually conveyed from the cylinders, gaseous hydrogen is produced industrially from hydrocarbons by the process known as steam reforming. For many applications, hydrogen is transferred from donor molecules such as acid, isopropanol. These hydrogen donors undergo dehydrogenation to, respectively, carbon dioxide, acetone and these processes are called transfer hydrogenations. Typical substrates are listed in the table With rare exceptions, H2 is unreactive toward organic compounds in the absence of metal catalysts, the unsaturated substrate is chemisorbed onto the catalyst, with most sites covered by the substrate. In heterogeneous catalysts, hydrogen forms surface hydrides from which hydrogens can be transferred to the chemisorbed substrate, platinum, palladium, rhodium, and ruthenium form highly active catalysts, which operate at lower temperatures and lower pressures of H2. Non-precious metal catalysts, especially based on nickel have also been developed as economical alternatives. The trade-off is activity vs. cost of the catalyst and cost of the apparatus required for use of high pressures, notice that the Raney-nickel catalysed hydrogenations require high pressures, Catalysts are usually classified into two broad classes, homogeneous catalysts and heterogeneous catalysts. Homogeneous catalysts dissolve in the solvent that contains the unsaturated substrate, heterogeneous catalysts are solids that are suspended in the same solvent with the substrate or are treated with gaseous substrate. Some well known homogeneous catalysts are indicated below and these are coordination complexes that activate both the unsaturated substrate and the H2
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Aldehyde
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The group—without R—is the aldehyde group, also known as the formyl group. Aldehydes are common in organic chemistry, Aldehydes feature an sp2-hybridized, planar carbon center that is connected by a double bond to oxygen and a single bond to hydrogen. The C–H bond is not ordinarily acidic, because of resonance stabilization of the conjugate base, an α-hydrogen in an aldehyde is far more acidic, with a pKa near 15, compared to the acidity of a typical alkane. This acidification is attributed to the quality of the formyl center and the fact that the conjugate base. Related to, the group is somewhat polar. Aldehydes can exist in either the keto or the enol tautomer, keto-enol tautomerism is catalyzed by either acid or base. Usually the enol is the minority tautomer, but it is more reactive, the common names for aldehydes do not strictly follow official guidelines, such as those recommended by IUPAC, but these rules are useful. IUPAC prescribes the following nomenclature for aldehydes, Acyclic aliphatic aldehydes are named as derivatives of the longest carbon chain containing the aldehyde group, thus, HCHO is named as a derivative of methane, and CH3CH2CH2CHO is named as a derivative of butane. The name is formed by changing the suffix -e of the parent alkane to -al, so that HCHO is named methanal, in other cases, such as when a -CHO group is attached to a ring, the suffix -carbaldehyde may be used. Thus, C6H11CHO is known as cyclohexanecarbaldehyde, if the presence of another functional group demands the use of a suffix, the aldehyde group is named with the prefix formyl-. This prefix is preferred to methanoyl-, the word aldehyde was coined by Justus von Liebig as a contraction of the Latin alcohol dehydrogenatus. In the past, aldehydes were sometimes named after the corresponding alcohols, for example, the term formyl group is derived from the Latin word formica ant. This word can be recognized in the simplest aldehyde, formaldehyde, Aldehydes have properties that are diverse and that depend on the remainder of the molecule. Smaller aldehydes are more soluble in water, formaldehyde and acetaldehyde completely so, the volatile aldehydes have pungent odors. Aldehydes degrade in air via the process of autoxidation, the two aldehydes of greatest importance in industry, formaldehyde and acetaldehyde, have complicated behavior because of their tendency to oligomerize or polymerize. They also tend to hydrate, forming the geminal diol, the oligomers/polymers and the hydrates exist in equilibrium with the parent aldehyde. Aldehydes are readily identified by spectroscopic methods, using IR spectroscopy, they display a strong νCO band near 1700 cm−1. In their 1H NMR spectra, the formyl hydrogen center absorbs near δH =9 and this signal shows the characteristic coupling to any protons on the alpha carbon
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Primary alcohol
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A primary alcohol is an alcohol which has the hydroxyl group connected to a primary carbon atom. It can also be defined as a molecule containing a “–CH2OH” group, in contrast, a secondary alcohol has a formula “–CHROH” and a tertiary alcohol has a formula “–CR2OH”, where “R” indicates a carbon-containing group. Examples of primary alcohols include ethanol and butanol, some sources include methanol as a primary alcohol, including the 1911 edition of the Encyclopædia Britannica, but this interpretation is less common in modern texts. Alcohol Oxidation of primary alcohols to carboxylic acids
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Candida tropicalis
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Candida tropicalis is a species of yeast in the genus Candida. It is a pathogen in neutropaenic hosts, in whom it may spread through the bloodstream to peripheral organs. For invasive disease, treatments include amphotericin B, echinocandins, or extended-spectrum triazole antifungals, recent research suggests that Candida tropicalis, working synergistically with Escherichia coli and Serratia marcescens, may cause or contribute to Crohns disease. Candida tropicalis can be used to produce biodiesel from olive trees, cellulosic ethanol C. tropicalis at NCBI Taxonomy browser
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Kilojoule
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The joule, symbol J, is a derived unit of energy in the International System of Units. It is equal to the transferred to an object when a force of one newton acts on that object in the direction of its motion through a distance of one metre. It is also the energy dissipated as heat when a current of one ampere passes through a resistance of one ohm for one second. It is named after the English physicist James Prescott Joule, one joule can also be defined as, The work required to move an electric charge of one coulomb through an electrical potential difference of one volt, or one coulomb volt. This relationship can be used to define the volt, the work required to produce one watt of power for one second, or one watt second. This relationship can be used to define the watt and this SI unit is named after James Prescott Joule. As with every International System of Units unit named for a person, note that degree Celsius conforms to this rule because the d is lowercase. — Based on The International System of Units, section 5.2. The CGPM has given the unit of energy the name Joule, the use of newton metres for torque and joules for energy is helpful to avoid misunderstandings and miscommunications. The distinction may be also in the fact that energy is a scalar – the dot product of a vector force. By contrast, torque is a vector – the cross product of a distance vector, torque and energy are related to one another by the equation E = τ θ, where E is energy, τ is torque, and θ is the angle swept. Since radians are dimensionless, it follows that torque and energy have the same dimensions, one joule in everyday life represents approximately, The energy required to lift a medium-size tomato 1 m vertically from the surface of the Earth. The energy released when that same tomato falls back down to the ground, the energy required to accelerate a 1 kg mass at 1 m·s−2 through a 1 m distance in space. The heat required to raise the temperature of 1 g of water by 0.24 °C, the typical energy released as heat by a person at rest every 1/60 s. The kinetic energy of a 50 kg human moving very slowly, the kinetic energy of a 56 g tennis ball moving at 6 m/s. The kinetic energy of an object with mass 1 kg moving at √2 ≈1.4 m/s, the amount of electricity required to light a 1 W LED for 1 s. Since the joule is also a watt-second and the unit for electricity sales to homes is the kW·h. For additional examples, see, Orders of magnitude The zeptojoule is equal to one sextillionth of one joule,160 zeptojoules is equivalent to one electronvolt. The nanojoule is equal to one billionth of one joule, one nanojoule is about 1/160 of the kinetic energy of a flying mosquito
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Sugar
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Sugar is the generic name for sweet, soluble carbohydrates, many of which are used in food. There are various types of derived from different sources. Simple sugars are called monosaccharides and include glucose, fructose, the table sugar or granulated sugar most customarily used as food is sucrose, a disaccharide of glucose and fructose. Sugar is used in prepared foods and it is added to some foods, in the body, sucrose is hydrolysed into the simple sugars fructose and glucose. Other disaccharides include maltose from malted grain, and lactose from milk, longer chains of sugars are called oligosaccharides or polysaccharides. Some other chemical substances, such as glycerol may also have a sweet taste, low-calorie food substitutes for sugar, described as artificial sweeteners, include aspartame and sucralose, a chlorinated derivative of sucrose. Sugars are found in the tissues of most plants and are present in sufficient concentrations for efficient commercial extraction in sugarcane, the world production of sugar in 2011 was about 168 million tonnes. The average person consumes about 24 kilograms of sugar each year, equivalent to over 260 food calories per person, since the latter part of the twentieth century, it has been questioned whether a diet high in sugars, especially refined sugars, is good for human health. Sugar has been linked to obesity, and suspected of, or fully implicated as a cause in the occurrence of diabetes, cardiovascular disease, dementia, macular degeneration, the etymology reflects the spread of the commodity. The English word sugar ultimately originates from the Sanskrit शर्करा, via Arabic سكر as granular or candied sugar, the contemporary Italian word is zucchero, whereas the Spanish and Portuguese words, azúcar and açúcar, respectively, have kept a trace of the Arabic definite article. The Old French word is zuchre and the contemporary French, sucre, the earliest Greek word attested is σάκχαρις. The English word jaggery, a brown sugar made from date palm sap or sugarcane juice, has a similar etymological origin – Portuguese jagara from the Sanskrit शर्करा. Sugar has been produced in the Indian subcontinent since ancient times and it was not plentiful or cheap in early times and honey was more often used for sweetening in most parts of the world. Originally, people chewed raw sugarcane to extract its sweetness, sugarcane was a native of tropical South Asia and Southeast Asia. Different species seem to have originated from different locations with Saccharum barberi originating in India and S. edule, one of the earliest historical references to sugarcane is in Chinese manuscripts dating back to 8th century BC that state that the use of sugarcane originated in India. Sugar was found in Europe by the 1st century AD, but only as an imported medicine and it is a kind of honey found in cane, white as gum, and it crunches between the teeth. It comes in lumps the size of a hazelnut, sugar is used only for medical purposes. Sugar remained relatively unimportant until the Indians discovered methods of turning sugarcane juice into granulated crystals that were easier to store, crystallized sugar was discovered by the time of the Imperial Guptas, around the 5th century AD
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Glycemic index
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The glycemic index or glycaemic index is a number associated with a particular type of food that indicates the foods effect on a persons blood glucose level. A value of 100 represents the standard, an equivalent amount of pure glucose, the GI represents the rise in a persons blood sugar level two hours after consumption of the food. The GI is useful for understanding how the body breaks down carbohydrates, the glycemic index is usually applied in the context of the quantity of the food and the amount of carbohydrate in the food that is actually consumed. A related measure, the load, factors this in by multiplying the glycemic index of the food in question by the carbohydrate content of the actual serving. Watermelon has a glycemic index, but a low glycemic load for the quantity typically consumed. Fructose, by contrast, has a low glycemic index, GI tables are available that list many types of foods and their GIs. Some tables also include the size and the glycemic load of the food per serving. A practical limitation of the index is that it does not measure insulin production due to rises in blood sugar. As a result, two foods could have the same index, but produce different amounts of insulin. Likewise, two foods could have the same load, but cause different insulin responses. Furthermore, both the index and glycemic load measurements are defined by the carbohydrate content of food. But because it contains no carbohydrate itself, steak cannot have a glycemic index, for some food comparisons, the insulin index may be more useful. Glycemic index charts often give one value per food, but variations are possible due to variety, ripeness, cooking methods, processing. Potatoes are an example, ranging from moderate to very high GI even within the same variety. The glycemic response is different from one person to another, and also in the person from day to day, depending on blood glucose levels, insulin resistance. The glycemic index does not show the impact on glucose levels after two hours, some people with diabetes can have elevated levels after four hours. The concept was developed by Dr. David J. Jenkins, a lower glycemic response usually equates to a lower insulin demand but not always, and can improve long-term blood glucose control and blood lipids. The insulin index is useful for providing a direct measure of the insulin response to a food
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Gastrointestinal tract
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Gastrointestinal is an adjective meaning of or pertaining to the stomach and intestines. A tract is a collection of related anatomic structures or a series of connected body organs, the mouth, oesophagus, stomach, and intestines are part of the human alimentary canal. All bilaterians have a gastrointestinal tract, also called a gut or an alimentary canal and this is a tube that transfers food to the organs of digestion. In large bilaterians, the gastrointestinal tract generally also has an exit, some small bilaterians have no anus and dispose of solid wastes by other means. The gastrointestinal tract contains thousands of different bacteria in their gut flora, the human gastrointestinal tract consists of the esophagus, stomach, and intestines, and is divided into the upper and lower gastrointestinal tracts. In contrast, the digestive system comprises the gastrointestinal tract plus the accessory organs of digestion. The tract may also be divided into foregut, midgut, and hindgut, the whole human GI tract is about nine metres long at autopsy. The GI tract releases hormones from enzymes to help regulate the digestive process, the structure and function can be described both as gross anatomy and as microscopic anatomy or histology. The tract itself is divided into upper and lower tracts, the upper gastrointestinal tract consists of the buccal cavity, pharynx, esophagus, stomach, and duodenum. The exact demarcation between the upper and lower tracts is the muscle of the duodenum. Upon dissection, the duodenum may appear to be an organ, but it is divided into four segments based upon function, location. The four segments of the duodenum are as follows, bulb, descending, horizontal, the suspensory muscle attaches the superior border of the ascending duodenum to the diaphragm. The suspensory muscle is an important anatomical landmark which shows the division between the duodenum and the jejunum, the first and second parts of the small intestine. This is a muscle which is derived from the embryonic mesoderm. The lower gastrointestinal tract includes most of the intestine and all of the large intestine. In humans, the intestine is further subdivided into the duodenum, jejunum and ileum while the large intestine is subdivided into the cecum, colon, rectum. The small intestine begins at the duodenum, which receives food from the stomach and it is a tubular structure, usually between 6 and 7 m long. The area of the human, adult small intestinal mucosa is about 30 m2 and its main function is to absorb the products of digestion into the bloodstream
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Drug
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A drug is any substance that, when inhaled, injected, smoked, consumed, absorbed via a patch on the skin, or dissolved under the tongue, causes a physiological change in the body. In pharmacology, a drug, also called a medication or medicine, is a chemical substance used to treat, cure, prevent. Traditionally drugs were obtained through extraction from plants, but more recently also by organic synthesis. Pharmaceutical drugs may be used for a duration, or on a regular basis for chronic disorders. Another major classification system is the Biopharmaceutics Classification System and this classifies drugs according to their solubility and permeability or absorption properties. Psychoactive drugs are chemical substances that affect the function of the nervous system, altering perception. They include alcohol, a depressant, and the nicotine and caffeine. These three are the most widely consumed psychoactive drugs worldwide and are also considered recreational drugs since they are used for rather than medicinal purposes. Other recreational drugs include hallucinogens, opiates and amphetamines and some of these are used in spiritual or religious settings. Some drugs can cause addiction and all drugs can have side effects, excessive use of stimulants can promote stimulant psychosis. Many recreational drugs are illicit and international such as the Single Convention on Narcotic Drugs exist for the purpose of their prohibition. The transitive verb to drug arose later and invokes the psychoactive rather than properties of a substance. A medication or medicine is a drug taken to cure or ameliorate any symptoms of an illness or medical condition, the use may also be as preventive medicine that has future benefits but does not treat any existing or pre-existing diseases or symptoms. In the United Kingdom, behind-the-counter medicines are called pharmacy medicines which can only be sold in registered pharmacies and these medications are designated by the letter P on the label. The range of medicines available without a prescription varies from country to country, medications are typically produced by pharmaceutical companies and are often patented to give the developer exclusive rights to produce them. Those that are not patented are called generic drugs since they can be produced by other companies without restrictions or licenses from the patent holder, pharmaceutical drugs are usually categorised into drug classes. A group of drugs will share a chemical structure, or have the same mechanism of action. Another major classification system is the Biopharmaceutics Classification System and this groups drugs according to their solubility and permeability or absorption properties
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Dietary supplement
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A dietary supplement is intended to provide nutrients that may otherwise not be consumed in sufficient quantities. Supplements as generally understood include vitamins, minerals, fiber, fatty acids, or amino acids, U. S. authorities define dietary supplements as foods, while elsewhere they may be classified as drugs or other products. There are more than 50,000 dietary supplements available, more than half of the U. S. adult population consume dietary supplements with most common ones being multivitamins. These products are not intended to prevent or treat any disease and in some circumstances are dangerous, for those who fail to consume a balanced diet, the agency says that certain supplements may have value. Most supplements should be avoided, and usually people should not eat micronutrients except people with clearly shown deficiency and those people should first consult a doctor. An exception is vitamin D, which is recommended in Nordic countries due to weak sunlight, the product is labeled as a dietary supplement. In the United States, the FDA has different monitoring procedures for substances depending on whether they are presented as drugs, food additives, food, or dietary supplements. Dietary supplements are eaten or taken by mouth, and are regulated in United States law as a type of rather than a type of drug. The intended use of dietary supplements is to ensure that a person gets enough essential nutrients, Dietary supplements should not be used to treat any disease or as preventive healthcare. An exception to this recommendation is the use of vitamins. Supplements may create harm in several ways, including over-consumption, particularly of minerals, the products may also cause harm related to their rapid absorption in a short period of time, quality issues such as contamination, or by adverse interactions with other foods and medications. There are many types of dietary supplements, Vitamin is an organic compound required by an organism as a vital nutrient in limited amounts. An organic chemical compound is called a vitamin when it cannot be synthesized in sufficient quantities by an organism, thus, the term is conditional both on the circumstances and on the particular organism. For example, ascorbic acid is a vitamin for humans, supplementation is important for the treatment of certain health problems but there is little evidence of benefit when used by those who are otherwise healthy. Amino acids are biologically important organic compounds composed of amine and carboxylic acid functional groups, the key elements of an amino acid are carbon, hydrogen, oxygen, and nitrogen, though other elements are found in the side-chains of certain amino acids. Amino acids can be divided into three categories, essential amino acids, non-essential amino acids, and conditional amino acids, essential amino acids cannot be made by the body, and must be supplied by food. Non-essential amino acids are made by the body from essential amino acids or in the breakdown of proteins. Conditional amino acids are not essential, except in times of illness, stress
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Confectionery
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Confectionery, also called sweets or candy, is sweet food. The term varies among English-speaking countries, in general, though, confectionery is divided into two broad and somewhat overlapping categories, bakers confections and sugar confections. Bakers confectionery, also called flour confections, includes principally sweet pastries, cakes, in the Middle East and Asia, flour-based confections are more dominant. Sugar confectionery includes sweets, candied nuts, chocolates, chewing gum and bubblegum, sweetmeats, pastillage, in some cases, chocolate confections are treated as a separate category, as are sugar-free versions of sugar confections. The words candy, sweets, and lollies are common words for the most common varieties of sugar confectionery, the confectionery industry also includes specialized training schools and extensive historical records. Traditional confectionery goes back to ancient times, and continued to be eaten through the Middle Ages into the modern era, generally, confections are low in micronutrients and protein but high in calories. They may be fat-free foods, although some confections, especially fried doughs, are high-fat foods, many confections are considered empty calories. Specially formulated chocolate has been manufactured in the past for use as a high-density food energy source. Confections are defined by the presence of sweeteners and these are usually sugars, but it is possible to buy sugar-free sweets, such as sugar-free peppermints. The most common sweetener for cooking is table sugar, which is chemically a disaccharide containing both glucose and fructose. Hydrolysis of sucrose gives a mixture called invert sugar, which is sweeter and is also a commercial ingredient. Finally confections, especially commercial ones, are sweetened by a variety of syrups obtained by hydrolysis of starch and these sweeteners include all types of corn syrup. Bakers confectionery includes sweet baked goods, especially those that are served for the dessert course, bakers confections are sweet foods that feature flour as a main ingredient and are baked. Major categories include cakes, sweet pastries, doughnuts, scones, Sugar confections include sweet, sugar-based foods, which are usually eaten as snack food. This includes sugar candies, chocolates, candied fruits and nuts, chewing gum, in the European Union, the Statistical Classification of Economic Activities in the European Community scheme matches the UN classification, under code number 10.82. Ice cream and sorbet are classified with dairy products under ISIC1050, NACE10.52, different dialects of English use regional terms for sugar confections, In Britain, Ireland, and some Commonwealth countries, sweets or, more colloquially, sweeties. In Australia and New Zealand, lollies, chewy and Chuddy are Australian slang for chewing gum. In North America, candy, although this generally refers to a specific range of confectionery
34.
Toothpaste
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Toothpaste is a paste or gel dentifrice used with a toothbrush as an accessory to clean and maintain the aesthetics and health of teeth. Salt and sodium bicarbonate are among materials that can be substituted for commercial toothpaste, in addition to 20–42% water, toothpastes are derived from a variety of components, the three main ones being abrasives, fluoride, and detergents. Abrasives constitute at least 50% of a typical toothpaste and these insoluble particles help remove plaque from the teeth. The removal of plaque and calculus helps minimize cavities and periodontal disease, representative abrasives include particles of aluminum hydroxide, calcium carbonate, various calcium hydrogen phosphates, various silicas and zeolites, and hydroxyapatite. Abrasives, like the dental polishing agents used in dentists offices, some brands contain powdered white mica, which acts as a mild abrasive, and also adds a cosmetically pleasing glittery shimmer to the paste. The polishing of teeth removes stains from tooth surfaces, but has not been shown to improve dental health over and above the effects of the removal of plaque, the abrasive effect of toothpaste is indicated by its RDA value. Too high RDA values should be considered critical, and some dentists recommend toothpaste of an RDA value no higher than 50 for daily use, Fluoride in various forms is the most popular active ingredient in toothpaste to prevent cavities. Fluoride occurs in small amounts in plants, animals, and some water sources. The additional fluoride in toothpaste has beneficial effects on the formation of dental enamel, sodium fluoride is the most common source of fluoride, but stannous fluoride, olaflur, and sodium monofluorophosphate are also used. Stannous fluoride has been shown to be effective than sodium fluoride in reducing the incidence of dental caries and controlling gingivitis. Much of the toothpaste sold in the United States has 1,000 to 1,100 parts per million fluoride, in European countries, such as the UK or Greece, the fluoride content is often higher, a NaF content of 0. 312% w/w is common. Many, although not all, toothpastes contain sodium lauryl sulfate or related surfactants, SLS is found in many other personal care products, as well, such as shampoo, and is mainly a foaming agent, which enables uniform distribution of toothpaste, improving its cleansing power. Despite the different ingredients included in the toothpaste, recent study indicates that brushing with or without toothpaste has no impact on the level of plaque removal, triclosan, an antibacterial agent, is a common toothpaste ingredient in the United Kingdom. Triclosan or zinc chloride prevent gingivitis and, according to the American Dental Association, helps reduce tartar, a 2006 review of clinical research concluded there was evidence for the effectiveness of 0. 30% triclosan in reducing plaque and gingivitis. Toothpaste comes in a variety of colors, and flavors intended to use of the product. Three most common flavorants are peppermint, spearmint, and wintergreen, Toothpaste flavored with peppermint-anise oil is popular in the Mediterranean region. These flavors are provided by the oils, e. g. peppermint oil. More exotic flavors include Anethole anise, apricot, bubblegum, cinnamon, fennel, lavender, neem, ginger, vanilla, lemon, orange, hydroxyapatite nanocrystals and a variety of calcium phosphates are included in formulations for remineralization, i. e. the reformation of enamel
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Chewing gum
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Chewing gum is a soft, cohesive substance designed to be chewed without being swallowed. Modern chewing gum is composed of gum base, sweeteners, softeners/ plasticizers, flavors, colors, and, typically, a hard or powdered polyol coating. The cultural tradition of chewing gum seems to have developed through a convergent evolution process, each of the early precursors to chewing gum were derived from natural growths local to the region and were chewed purely out the instinctual desire to masticate. Early chewers did not necessarily desire to derive benefits from their chewable substances. Chewing gum in many forms has existed since the Neolithic period,6, 000-year-old chewing gum made from birch bark tar, with tooth imprints, has been found in Kierikki in Finland. The tar from which the gums were made is believed to have antiseptic properties and it is chemically similar to petroleum tar and is in this way different from most other early gum. The Aztecs, as the ancient Mayans before them, used chicle, forms of chewing gums were also chewed in Ancient Greece. The Ancient Greeks chewed mastic gum, made from the resin of the mastic tree, mastic gum, like birch bark tar, has antiseptic properties and is believed to have been used to maintain oral health. Both chicle and mastic are tree resins, many other cultures have chewed gum-like substances made from plants, grasses, and resins. Although chewing gum can be traced back to civilizations around the world, the American Indians chewed resin made from the sap of spruce trees. The New England settlers picked up this practice, and in 1848, John B. Curtis developed, in this way, the industrializing West, having forgotten about tree gums, rediscovered chewing gum through the First Americans. Around 1850 a gum made from wax, which is a petroleum product, was developed. To sweeten these early gums the chewer would often use of a plate of powdered sugar. William Semple filed a patent on chewing gum, patent number 98,304. The first flavored chewing gum was created in the 1860s by John Colgan, Colgan mixed with powdered sugar the aromatic flavoring tolu, a powder obtained from an extract of the balsam tree, creating small sticks of flavored chewing gum he named Taffy Tolu. Colgan also lead the way in the manufacturing and packaging of chicle-based chewing gum, derived from Manilkara chicle, chicle did not succeed as a replacement for rubber, but as a gum, which was cut into strips and marketed as Adams New York Chewing Gum in 1871. Black Jack, which is flavored with licorice, Chiclets, Chewing gum gained worldwide popularity through American GIs in WWII, who were supplied chewing gum as a ration and traded it with locals. Synthetic gums were first introduced to the U. S. after chicle no longer satisfied the needs of making chewing gum
36.
Insulin
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Insulin is a peptide hormone produced by beta cells of the pancreatic islets. It regulates the metabolism of carbohydrates, fats and protein by promoting the absorption of, especially, glucose from the blood into fat, liver and skeletal muscle cells. In these tissues the absorbed glucose is converted into either glycogen via glycogenesis or fats via lipogenesis, or, in the case of the liver, Glucose production by the liver is strongly inhibited by high concentrations of insulin in the blood. Circulating insulin also affects the synthesis of proteins in a variety of tissues. It is therefore an anabolic hormone, promoting the conversion of small molecules in the blood into large molecules inside the cells, low insulin levels in the blood have the opposite effect by promoting widespread catabolism. Pancreatic beta cells are known to be sensitive to concentrations in the blood. When glucose concentrations in the blood are high, the pancreatic β cells secrete insulin into the blood, glucagon, through stimulating the liver to release glucose by glycogenolysis and gluconeogenesis, has the opposite effect of insulin. If pancreatic beta cells are destroyed by an reaction, insulin can no longer be synthesized or be secreted into the blood. This results in type 1 diabetes mellitus, which is characterized by high blood glucose concentrations. In type 2 diabetes mellitus the destruction of cells is less pronounced than in type 1 diabetes. Instead there is an accumulation of amyloid in the pancreatic islets, Type 2 diabetes is characterized by high rates of glucagon secretion into the blood which are unaffected by, and unresponsive to the concentration of glucose in the blood glucose. Insulin is still secreted into the blood in response to the blood glucose, as a result, the insulin levels, even when the blood sugar level is normal, are much higher than they are in healthy persons. There are a variety of treatment regimens, none of which is entirely satisfactory, when the pancreas’s capacity to secrete insulin can no longer keep the blood sugar level within normal bounds, insulin injections are given. The human insulin protein is composed of 51 amino acids, and has a mass of 5808 Da. It is a dimer of an A-chain and a B-chain, which are linked together by disulfide bonds, insulins structure varies slightly between species of animals. Insulin from animal sources differs somewhat in effectiveness from human insulin because of these variations, porcine insulin is especially close to the human version, and was widely used to treat type 1 diabetics before human insulin could be produced in large quantities by recombinant DNA technologies. The crystal structure of insulin in the state was determined by Dorothy Hodgkin. It is on the WHO Model List of Essential Medicines, the most important medications needed in a health system
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Blood sugar level
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The blood sugar concentration or blood glucose level is the amount of glucose present in the blood of a human or animal. The body naturally tightly regulates blood glucose levels as a part of metabolic homeostasis, with some exceptions, glucose is the primary source of energy for the bodys cells, and blood lipids are primarily a compact energy store. Glucose levels are usually lowest in the morning, before the first meal of the day, Blood sugar levels outside the normal range may be an indicator of a medical condition. A persistently high level is referred to as hyperglycemia, low levels are referred to as hypoglycemia, Diabetes mellitus is characterized by persistent hyperglycemia from any of several causes, and is the most prominent disease related to failure of blood sugar regulation. Intake of alcohol causes a surge in blood sugar. Also, certain drugs can increase or decrease glucose levels, the international standard way of measuring blood glucose levels are in terms of a molar concentration, measured in mmol/L. In the United States, West-Germany and other countries mass concentration is measured in mg/dL, since the molecular weight of glucose C6H12O6 is 180, the difference between the two units is a factor of 18, so that 1 mmol/L of glucose is equivalent to 18 mg/dL. Normal value ranges may vary slightly among different laboratories, many factors affect a persons blood sugar level. A bodys homeostatic mechanism, when operating normally, restores the blood sugar level to a range of about 4.4 to 6.1 mmol/L. The normal blood level for non-diabetics, should be between 3.9 and 5.5 mmol/L. The mean normal blood glucose level in humans is about 5.5 mmol/L, however, Blood sugar levels for those without diabetes and who are not fasting should be below 6.9 mmol/L. The blood glucose target range for diabetics, according to the American Diabetes Association, should be 5. 0–7.2 mmol/l before meals, and less than 10 mmol/L after meals. Despite widely variable intervals between meals or the consumption of meals with a substantial carbohydrate load, human blood glucose levels tend to remain within the normal range. However, shortly after eating, the glucose level may rise, in non-diabetics. The actual amount of glucose in the blood and body fluids is very small. In a healthy adult male of 75 kg with a volume of 5 liters. Part of the reason why this amount is so small is that, to maintain an influx of glucose into cells, in general, ranges of blood sugar in common domestic ruminants are lower than in many monogastric mammals. However this generalization does not extend to wild ruminants or camelids, a 90 percent reference interval for serum glucose of 26 to 181 mg/dL has been reported for captured mountain goats, where no effects of the pursuit and capture on measured levels were evident
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