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.
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
6.
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
7.
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
8.
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
9.
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
10.
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
11.
Chemical compound
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A chemical compound is an entity consisting of two or more atoms, at least two from different elements, which associate via chemical bonds. Many chemical compounds have a numerical identifier assigned by the Chemical Abstracts Service. For example, water is composed of two atoms bonded to one oxygen atom, the chemical formula is H2O. A compound can be converted to a different chemical composition by interaction with a chemical compound via a chemical reaction. In this process, bonds between atoms are broken in both of the compounds, and then bonds are reformed so that new associations are made between atoms. Schematically, this reaction could be described as AB + CD → AC + BD, where A, B, C, and D are each unique atoms, and AB, CD, AC, and BD are each unique compounds. A chemical element bonded to a chemical element is not a chemical compound since only one element. Examples are the diatomic hydrogen and the polyatomic molecule sulfur. Chemical compounds have a unique and defined chemical structure held together in a spatial arrangement by chemical bonds. Pure chemical elements are not considered chemical compounds, failing the two or more atom requirement, though they often consist of molecules composed of multiple atoms. There is varying and sometimes inconsistent nomenclature differentiating substances, which include truly non-stoichiometric examples, from chemical compounds, other compounds regarded as chemically identical may have varying amounts of heavy or light isotopes of the constituent elements, which changes the ratio of elements by mass slightly. Characteristic properties of compounds include that elements in a compound are present in a definite proportion, for example, the molecule of the compound water is composed of hydrogen and oxygen in a ratio of 2,1. In addition, compounds have a set of properties. The physical and chemical properties of compounds differ from those of their constituent elements, however, mixtures can be created by mechanical means alone, but a compound can be created only by a chemical reaction. Some mixtures are so combined that they have some properties similar to compounds. Other examples of compound-like mixtures include intermetallic compounds and solutions of metals in a liquid form of ammonia. Compounds may be described using formulas in various formats, for compounds that exist as molecules, the formula for the molecular unit is shown. For polymeric materials, such as minerals and many metal oxides, the elements in a chemical formula are normally listed in a specific order, called the Hill system
12.
Alkaloid
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Alkaloids are a group of naturally occurring chemical compounds that mostly contain basic nitrogen atoms. This group also includes some related compounds with neutral and even weakly acidic properties, some synthetic compounds of similar structure are also termed alkaloids. In addition to carbon, hydrogen and nitrogen, alkaloids may also contain oxygen, sulfur and, more rarely, other such as chlorine, bromine. Alkaloids are produced by a variety of organisms including bacteria, fungi, plants. They can be purified from crude extracts of these organisms by acid-base extraction, many have found use in traditional or modern medicine, or as starting points for drug discovery. Other alkaloids possess psychotropic and stimulant activities, and have used in entheogenic rituals or as recreational drugs. Although alkaloids act on a diversity of systems in humans and other animals. The boundary between alkaloids and other nitrogen-containing natural compounds is not clear-cut, Compounds like amino acid peptides, proteins, nucleotides, nucleic acid, amines, and antibiotics are usually not called alkaloids. Natural compounds containing nitrogen in the position are usually classified as amines rather than as alkaloids. Some authors, however, consider alkaloids a special case of amines, the name alkaloids was introduced in 1819 by the German chemist Carl Friedrich Wilhelm Meißner, and is derived from late Latin root Latin, alkali and the suffix Greek, -οειδής – like. However, the term came into use only after the publication of a review article by Oscar Jacobsen in the chemical dictionary of Albert Ladenburg in the 1880s. There is no method of naming alkaloids. Many individual names are formed by adding the suffix ine to the species or genus name, for example, atropine is isolated from the plant Atropa belladonna, strychnine is obtained from the seed of Strychnine tree. If several alkaloids are extracted from one plant then their names often contain suffixes idine, anine, aline, inine etc. There are also at least 86 alkaloids whose names contain the root vin because they are extracted from plants such as Vinca rosea. Alkaloid-containing plants have been used by humans since ancient times for therapeutic, for example, medicinal plants have been known in the Mesopotamia at least around 2000 BC. The Odyssey of Homer referred to a given to Helen by the Egyptian queen. It is believed that the gift was an opium-containing drug, a Chinese book on houseplants written in 1st–3rd centuries BC mentioned a medical use of Ephedra and opium poppies
13.
Conium maculatum
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Conium maculatum is a highly poisonous biennial herbaceous flowering plant in the carrot family Apiaceae, native to Europe and North Africa. A hardy plant capable of living in a variety of environments, Hemlock has been introduced to other locations outside its range. Conium maculatum is known by common names. In addition to the English poison hemlock, the Australian Carrot Fern, and the Irish devils bread or devils porridge, poison parsley, spotted corobane, and spotted hemlock are used. The plant should not be confused with the coniferous tree Tsuga, the dried stems are sometimes called kecksies or kex. Conium comes from the Greek konas, in reference to vertigo, conium maculatum is a herbaceous biennial flowering plant in Apiaceae, the carrot family, that is native to Europe and North Africa. It grows to 1. 5–2.5 m tall, with a smooth, green, hollow stem, usually spotted or streaked with red or purple on the lower half of the stem. All parts of the plant are hairless, the leaves are two- to four-pinnate, finely divided and lacy, overall triangular in shape, the flowers are small, white, clustered in umbels up to 10–15 cm across. When crushed, the leaves and root emit a rank, unpleasant odor often compared to that of parsnips and it produces a large number of seeds that allow the plant to form thick stands in modified soils. Conium maculatum is native in temperate regions of Europe, West Asia and it has been introduced and naturalised in many other areas, including Asia, North America, Australia, and New Zealand. It is often found on poorly drained soils, particularly streams, ditches. It also appears on roadsides, edges of cultivated fields, and it is considered an invasive species in 12 U. S. states. Conium maculatum grows in areas, but also on drier rough grassland, roadsides. It is used as a plant by the larvae of some Lepidoptera species. Poison hemlock flourishes in the spring, when most other forage is gone, all plant parts are poisonous, but once the plant is dried, the poison is greatly reduced, although not gone completely. Conium contains the piperidine alkaloids coniine, N-methylconiine, conhydrine, pseudoconhydrine, and gamma-coniceine, coniine has a chemical structure and pharmacological properties similar to nicotine, and disrupts the workings of the central nervous system through action on nicotinic acetylcholine receptors. In high enough concentrations, coniine can be dangerous to humans, due to high potency, the ingestion of seemingly small doses can easily result in respiratory collapse and death. Death can be prevented by artificial ventilation until the effects have worn off 48–72 hours later, for an adult, the ingestion of more than 100 mg of coniine may be fatal
14.
Sarracenia flava
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Sarracenia flava, the yellow pitcherplant, is a carnivorous plant in the family Sarraceniaceae. Like all the Sarraceniaceae, it is native to the New World and its range extends from southern Alabama, through Florida and Georgia, to the coastal plains of southern Virginia, North Carolina and South Carolina. Populations also exist in the Piedmont and mountains of North Carolina, like other members of the genus Sarracenia, the yellow pitcher plant traps insects using a rolled leaf, which in this species is a vibrant yellow in color, and up to over a meter in height. The uppermost part of the leaf is flared into a lid, the opening of the pitcher tube is retroflexed into a nectar roll or peristome, whose surface is studded with nectar-secreting glands. The nectar contains not only sugars, but also the alkaloid coniine, prey entering the tube find that their footing is made extremely uncertain by the smooth, waxy secretions found on the surfaces of the upper portion of the tube. Insects losing their footing on this surface plummet to the bottom of the tube, some large insects have been reported to escape from the pitchers on occasion, by chewing their way out through the wall of the tube. In spring, the plant produces flowers with 5-fold symmetry. The yellow petals are long and strap-like, and dangle over the style of the flower. The stigma of the flower are found at the tips of the spokes of this umbrella, the pollinators generally exit the flower, having been dusted with the plants own pollen, by lifting a petal. This one-way system helps to cross pollination. In late summer and autumn, the plant stops producing carnivorous leaves and this is probably an adaptation to low light levels and insect scarcity during the winter months, and shows clearly the cost of carnivory. The yellow pitcher plant is easy to cultivate, and is one of the most popular plants in horticulture. The yellow pitcher plant readily hybridises with other members of the genus Sarracenia, X catesbaei and S. moorei are found in the wild, and are also popular amongst collectors. Isolation of insect paralyzing agent coniine from Sarracenia flava, cellular and Molecular Life Sciences 32, 829–830. Doi,10. 1007/BF02003710 N. C. State reference Schnell, D. Catling, P. Folkerts, G. Frost, IUCN Red List of Threatened Species. International Union for Conservation of Nature, about Sarracenia Flava Botanical Society of America, Sarracenia - the Pitcher Plants
15.
Aethusa cynapium
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Aethusa cynapium is an annual herb in the plant family Apiaceae, native to Europe, western Asia, and northwest Africa. It is the member of the genus Aethusa. It is related to Hemlock and Water-dropwort, and like them it is poisonous and it has been introduced into many other parts of the world and is a common weed in cultivated ground. Since some toxins are destroyed by drying, hay containing the plant is not poisonous, media related to Aethusa cynapium at Wikimedia Commons Parsley, Fools
16.
Biosynthesis
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Biosynthesis is a multi-step, enzyme-catalyzed process where substrates are converted into more complex products in living organisms. In biosynthesis, simple compounds are modified, converted into other compounds and this process often consists of metabolic pathways. Some of these pathways are located within a single cellular organelle, while others involve enzymes that are located within multiple cellular organelles. Examples of these pathways include the production of lipid membrane components. The prerequisite elements for biosynthesis include, precursor compounds, chemical energy and these elements create monomers, the building blocks for macromolecules. Biosynthesis occurs due to a series of chemical reactions, for these reactions to take place, the following elements are necessary, Precursor compounds, these compounds are the starting molecules or substrates in a reaction. These may also be viewed as the reactants in a chemical process. Chemical energy, chemical energy can be found in the form of high energy molecules and these molecules are required for energetically unfavorable reactions. Furthermore, the hydrolysis of these compounds drives a reaction forward, high energy molecules, such as ATP, have three phosphates. Often, the phosphate is split off during hydrolysis and transferred to another molecule. Catalytic enzymes, these molecules are special proteins that catalyze a reaction by increasing the rate of the reaction, coenzymes or cofactors, cofactors are molecules that assist in chemical reactions. These may be metal ions, vitamin derivatives such as NADH and acetyl CoA, in the case of NADH, the molecule transfers a hydrogen, whereas acetyl CoA transfers an acetyl group, and ATP transfers a phosphate. Two examples of type of reaction occur during the formation of nucleic acids. For some of these steps, chemical energy is required, Precursor molecule + ATP ↽ − − ⇀ product AMP + PP i Simple compounds that are converted into other compounds with the assistance of cofactors. For example, the synthesis of phospholipids requires acetyl CoA, while the synthesis of another component, shingolipids. The general equation for these examples is, Precursor molecule + Cofactor → e n z y m e macromolecule Simple compounds that join together to create a macromolecule, for example, fatty acids join together to form phopspholipids. In turn, phospholipids and cholesterol interact noncovalently in order to form the lipid bilayer and this reaction may be depicted as follows, Molecule 1 + Molecule 2 ⟶ macromolecule Many intricate macromolecules are synthesized in a pattern of simple, repeated structures. For example, the simplest structures of lipids are fatty acids, fatty acids are hydrocarbon derivatives, they contain a carboxyl group “head” and a hydrocarbon chain “tail. ”These fatty acids create larger components, which in turn incorporate noncovalent interactions to form the lipid bilayer
17.
Enzyme
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Enzymes /ˈɛnzaɪmz/ are macromolecular biological catalysts. Enzymes accelerate, or catalyze, chemical reactions, the molecules at the beginning of the process upon which enzymes may act are called substrates and the enzyme converts these into different molecules, called products. Almost all metabolic processes in the cell need enzymes in order to occur at rates fast enough to sustain life, the set of enzymes made in a cell determines which metabolic pathways occur in that cell. The study of enzymes is called enzymology, enzymes are known to catalyze more than 5,000 biochemical reaction types. Most enzymes are proteins, although a few are catalytic RNA molecules, enzymes specificity comes from their unique three-dimensional structures. Like all catalysts, enzymes increase the rate of a reaction by lowering its activation energy, some enzymes can make their conversion of substrate to product occur many millions of times faster. An extreme example is orotidine 5-phosphate decarboxylase, which allows a reaction that would take millions of years to occur in milliseconds. Chemically, enzymes are like any catalyst and are not consumed in chemical reactions, enzymes differ from most other catalysts by being much more specific. Enzyme activity can be affected by other molecules, inhibitors are molecules that decrease enzyme activity, many drugs and poisons are enzyme inhibitors. An enzymes activity decreases markedly outside its optimal temperature and pH, some enzymes are used commercially, for example, in the synthesis of antibiotics. French chemist Anselme Payen was the first to discover an enzyme, diastase and he wrote that alcoholic fermentation is an act correlated with the life and organization of the yeast cells, not with the death or putrefaction of the cells. In 1877, German physiologist Wilhelm Kühne first used the term enzyme, the word enzyme was used later to refer to nonliving substances such as pepsin, and the word ferment was used to refer to chemical activity produced by living organisms. Eduard Buchner submitted his first paper on the study of yeast extracts in 1897, in a series of experiments at the University of Berlin, he found that sugar was fermented by yeast extracts even when there were no living yeast cells in the mixture. He named the enzyme that brought about the fermentation of sucrose zymase, in 1907, he received the Nobel Prize in Chemistry for his discovery of cell-free fermentation. Following Buchners example, enzymes are usually named according to the reaction they carry out, the biochemical identity of enzymes was still unknown in the early 1900s. Sumner showed that the enzyme urease was a protein and crystallized it. These three scientists were awarded the 1946 Nobel Prize in Chemistry, the discovery that enzymes could be crystallized eventually allowed their structures to be solved by x-ray crystallography. This high-resolution structure of lysozyme marked the beginning of the field of structural biology, an enzymes name is often derived from its substrate or the chemical reaction it catalyzes, with the word ending in -ase
18.
Schiff base
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A Schiff base is a compound with the general structure R2C=NR. They can be considered a sub-class of imines, being either secondary ketimines or secondary depending on their structure. The term is synonymous with azomethine which refers specifically to secondary aldimines. A number of naming systems exist for these compounds. For instance a Schiff base derived from an aniline, where R3 is a phenyl or a substituted phenyl, can be called an anil, the term Schiff base is normally applied to these compounds when they are being used as ligands to form coordination complexes with metal ions. Such complexes do occur naturally, for instance in Corrin, but the majority of Schiff bases are artificial and are used to form many important catalysts, such as Jacobsens catalyst. Schiff bases can be synthesized from an aliphatic or aromatic amine, the common enzyme cofactor PLP forms a Schiff base with a lysine residue and is transaldiminated to the substrate. Similarly, the cofactor retinal forms a Schiff base in rhodopsins, including human rhodopsin, an example where the substrate forms a Schiff base to the enzyme is in the fructose 1, 6-bisphosphate aldolase catalyzed reaction during glycolysis and in the metabolism of amino acids. Schiff bases are common ligands in coordination chemistry, the imine nitrogen is basic and exhibits pi-acceptor properties. The ligands are derived from alkyl diamines and aromatic aldehydes. Chiral Schiff bases were one of the first ligands used for asymmetric catalysis, in 1968 Ryōji Noyori developed a copper-Schiff base complex for the metal-carbenoid cyclopropanation of styrene. For this work he was awarded a share of the 2001 Nobel Prize in Chemistry. Their simple and clean chemistry make them a candidate as a low cost alternative to currently used conjugated materials. Schiff base chemistry is used to prepare covalent organic framework
19.
Cyclic compound
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A cyclic compound is a term for a compound in the field of chemistry in which one or more series of atoms in the compound is connected to form a ring. Rings may vary in size from three to many atoms, and include examples where all the atoms are carbon, none of the atoms are carbon, cyclic compound examples, All-carbon and more complex natural cyclic compounds. Indeed, the development of important chemical concept arose, historically. A cyclic compound or ring compound is a compound at least some of whose atoms are connected to form a ring, rings vary in size from 3 to many tens or even hundreds of atoms. Examples of ring compounds readily include cases where, all the atoms are carbon, none of the atoms are carbon, common atoms can form varying numbers of bonds, and many common atoms readily form rings. As a consequence of the variability that is thermodynamically possible in cyclic structures. IUPAC nomenclature has extensive rules to cover the naming of cyclic structures, the term macrocycle is used when a ring-containing compound has a ring of 8 or more atoms. The term polycyclic is used more than one ring appears in a single molecule. Naphthalene is formally a polycyclic, but is specifically named as a bicyclic compound. Several examples of macrocyclic and polycyclic structures are given in the gallery below. The atoms that are part of the structure are called annular atoms. The vast majority of compounds are organic, and of these. Inorganic atoms form cyclic compounds as well, examples include sulfur, silicon, phosphorus, and boron. Hantzsch–Widman nomenclature is recommended by the IUPAC for naming heterocycles, cyclic compounds may or may not exhibit aromaticity, benzene is an example of an aromatic cyclic compound, while cyclohexane is non-aromatic. As a result of their stability, it is difficult to cause aromatic molecules to break apart. Organic compounds that are not aromatic are classified as aliphatic compounds—they might be cyclic, nevertheless, many non-benzene aromatic compounds exist. In living organisms, for example, the most common aromatic rings are the bases in RNA and DNA. A functional group or other substituent that is aromatic is called an aryl group, the earliest use of the term “aromatic” was in an article by August Wilhelm Hofmann in 1855
20.
Stereoisomerism
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Stereoisomers are isomeric molecules that have the same molecular formula and sequence of bonded atoms, but differ in the three-dimensional orientations of their atoms in space. This contrasts with structural isomers, which share the same molecular formula, by definition, molecules that are stereoisomers of each other represent the same structural isomer. Enantiomers, also known as optical isomers, are two stereoisomers that are related to other by a reflection, They are mirror images of each other that are non-superimposable. Human hands are an analog of stereoisomerism. Every stereogenic center in one has the configuration in the other. As a result, different enantiomers of a compound may have different biological effects. Pure enantiomers also exhibit the phenomenon of optical activity and can be separated only with the use of a chiral agent, in nature, only one enantiomer of most chiral biological compounds, such as amino acids, is present. Diastereomers are stereoisomers not related through a reflection operation and they are not mirror images of each other. These include meso compounds, cis–trans isomers, and non-enantiomeric optical isomers, diastereomers seldom have the same physical properties. In the example shown below, the form of tartaric acid forms a diastereomeric pair with both levo and dextro tartaric acids, which form an enantiomeric pair. Please refer to Chirality for more regarding the D- and L- labels. Stereoisomerism about double bonds arises because rotation about the bond is restricted. The simplest examples of cis-trans isomerism are the 1, 2-disubstituted ethenes, molecule I is cis-1, 2-dichloroethene and molecule II is trans-1, 2-dichloroethene. Due to occasional ambiguity, IUPAC adopted a rigorous system wherein the substituents at each end of the double bond are assigned priority based on their atomic number. If the high-priority substituents are on the side of the bond. If they are on sides, it is E. Since chlorine has an atomic number than hydrogen, it is the highest-priority group. Using this notation to name the above pictured molecules, molecule I is -1, 2-dichloroethene and molecule II is -1 and it is not the case that Z and cis or E and trans are always interchangeable
21.
Organic chemistry
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Study of structure includes many physical and chemical methods to determine the chemical composition and the chemical constitution of organic compounds and materials. In the modern era, the range extends further into the table, with main group elements, including, Group 1 and 2 organometallic compounds. They either form the basis of, or are important constituents of, many products including pharmaceuticals, petrochemicals and products made from them, plastics, fuels and explosives. Before the nineteenth century, chemists generally believed that compounds obtained from living organisms were endowed with a force that distinguished them from inorganic compounds. According to the concept of vitalism, organic matter was endowed with a vital force, during the first half of the nineteenth century, some of the first systematic studies of organic compounds were reported. Around 1816 Michel Chevreul started a study of soaps made from various fats and he separated the different acids that, in combination with the alkali, produced the soap. Since these were all compounds, he demonstrated that it was possible to make a chemical change in various fats, producing new compounds. In 1828 Friedrich Wöhler produced the chemical urea, a constituent of urine, from inorganic starting materials. The event is now accepted as indeed disproving the doctrine of vitalism. In 1856 William Henry Perkin, while trying to manufacture quinine accidentally produced the organic dye now known as Perkins mauve and his discovery, made widely known through its financial success, greatly increased interest in organic chemistry. A crucial breakthrough for organic chemistry was the concept of chemical structure, ehrlich popularized the concepts of magic bullet drugs and of systematically improving drug therapies. His laboratory made decisive contributions to developing antiserum for diphtheria and standardizing therapeutic serums, early examples of organic reactions and applications were often found because of a combination of luck and preparation for unexpected observations. The latter half of the 19th century however witnessed systematic studies of organic compounds, the development of synthetic indigo is illustrative. The production of indigo from plant sources dropped from 19,000 tons in 1897 to 1,000 tons by 1914 thanks to the methods developed by Adolf von Baeyer. In 2002,17,000 tons of indigo were produced from petrochemicals. In the early part of the 20th Century, polymers and enzymes were shown to be large organic molecules, the multiple-step synthesis of complex organic compounds is called total synthesis. Total synthesis of natural compounds increased in complexity to glucose. For example, cholesterol-related compounds have opened ways to synthesize complex human hormones, since the start of the 20th century, complexity of total syntheses has been increased to include molecules of high complexity such as lysergic acid and vitamin B12
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Albert Ladenburg
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Albert Ladenburg was a German chemist. Ladenburg was a member of the well-known Jewish Ladenburg family in Mannheim and he was educated at a Realgymnasium at Mannheim and then, after the age of 15, at the technical school of Karlsruhe, where he studied mathematics and modern languages. He then proceeded to the University of Heidelberg where he studied Chemistry and he also studied physics in Berlin. He got his Ph. D. in Heidelberg, in Ghent, Ladenburg worked for 6 months with Kekulé who introduced him to structural theory. They worked on the structure of Benzene, ladenburgs theory that benzene was a prismatic molecule turned out to be wrong. His proposed structure was eventually realised in 1973 in the molecule prismane, Ladenburg visited England, and then went on to work for 18 months in Paris with Charles-Adolphe Wurtz and Charles Friedel on organosilicon compounds and tin compounds. He then returned to Heidelberg to teach, in 1873, Ladenburg went to Kiel as professor of chemistry and director of the laboratory, remaining there until 1889 when he went to the University of Breslau in the same capacity. He was made a member of the Pharmaceutical Society of Great Britain in 1886. Ladenburg isolated hyoscine, also known as scopolamine for the first time in 1880, in 1900 Ladenburg founded the Chemische Gesellschaft Breslau, which he managed until 1910. He was also awarded the prestigious Davy Medal in 1905 for his researches in organic chemistry, Ladenburg also addressed the relation of religion and science in a book he published in 1904, where he dealt with the topics of Science and spiritual life and Christianity. Entwicklungsgeschichte der Chemie von Lavoisier bis zur Gegenwart Vorträge über die Entwicklungsgeschichte der Chemie in den letzten hundert Jahren, Digital edition of the University and State Library Düsseldorf. Handwörterbuch der Chemie Religion und Naturwissenschaft, eine Antwort an Professor Ladenburg Vortraege ueber die Entwicklungsgeschichte der Chemie von Lavoisier bis zur Gegenwart, vieweg, Braunschweig 4th ed.1907 Digital edition of the University and State Library Düsseldorf Lebenserinnerungen His son, Rudolf, became an atomic physicist. Guide to the Albert Ladenburg Family Collection at the Leo Baeck Institute, New York Dr. Leopold Ladenburg, Stammtafel der Familie Ladenburg, Verlag J. Ph. Walther, Albert Ladenburg, Lebenserinnerungen, Trewendt & Granier, Breslau,1912
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Socrates
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Socrates was a classical Greek philosopher credited as one of the founders of Western philosophy. He is a figure known chiefly through the accounts of classical writers, especially the writings of his students Plato and Xenophon. Platos dialogues are among the most comprehensive accounts of Socrates to survive from antiquity, though it is unclear the degree to which Socrates himself is hidden behind his best disciple, nothing written by Socrates remains extant. As a result, information about him and his philosophies depends upon secondary sources, furthermore, close comparison between the contents of these sources reveals contradictions, thus creating concerns about the possibility of knowing in-depth the real Socrates. This issue is known as the Socratic problem, or the Socratic question, to understand Socrates and his thought, one must turn primarily to the works of Plato, whose dialogues are thought the most informative source about Socrates life and philosophy, and also Xenophon. These writings are the Sokratikoi logoi, or Socratic dialogues, which consist of reports of conversations apparently involving Socrates, as for discovering the real-life Socrates, the difficulty is that ancient sources are mostly philosophical or dramatic texts, apart from Xenophon. There are no straightforward histories, contemporary with Socrates, that dealt with his own time, a corollary of this is that sources that do mention Socrates do not necessarily claim to be historically accurate, and are often partisan. For instance, those who prosecuted and convicted Socrates have left no testament, historians therefore face the challenge of reconciling the various evidence from the extant texts in order to attempt an accurate and consistent account of Socrates life and work. The result of such an effort is not necessarily realistic, even if consistent, amid all the disagreement resulting from differences within sources, two factors emerge from all sources pertaining to Socrates. It would seem, therefore, that he was ugly, also, Xenophon, being an historian, is a more reliable witness to the historical Socrates. It is a matter of debate over which Socrates it is whom Plato is describing at any given point—the historical figure. As British philosopher Martin Cohen has put it, Plato, the idealist, offers an idol, a Saint, a prophet of the Sun-God, a teacher condemned for his teachings as a heretic. It is also clear from other writings and historical artefacts, that Socrates was not simply a character, nor an invention, the testimony of Xenophon and Aristotle, alongside some of Aristophanes work, is useful in fleshing out a perception of Socrates beyond Platos work. The problem with discerning Socrates philosophical views stems from the perception of contradictions in statements made by the Socrates in the different dialogues of Plato and these contradictions produce doubt as to the actual philosophical doctrines of Socrates, within his milieu and as recorded by other individuals. Aristotle, in his Magna Moralia, refers to Socrates in words which make it patent that the virtue is knowledge was held by Socrates. Within the Metaphysics, he states Socrates was occupied with the search for moral virtues, however, in The Clouds, Aristophanes portrays Socrates as accepting payment for teaching and running a sophist school with Chaerephon. Also, in Platos Apology and Symposium, as well as in Xenophons accounts, more specifically, in the Apology, Socrates cites his poverty as proof that he is not a teacher. Two fragments are extant of the writings by Timon of Phlius pertaining to Socrates, although Timon is known to have written to ridicule, details about the life of Socrates can be derived from three contemporary sources, the dialogues of Plato and Xenophon, and the plays of Aristophanes
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Toxic
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Toxicity is the degree to which a substance can damage an organism. Toxicity can refer to the effect on an organism, such as an animal, bacterium, or plant, as well as the effect on a substructure of the organism. By extension, the word may be used to describe toxic effects on larger and more complex groups. Sometimes the word is more or less synonymous with poisoning in everyday usage, toxicity is species-specific, making cross-species analysis problematic. Newer paradigms and metrics are evolving to bypass animal testing, while maintaining the concept of toxicity endpoints, disease-causing microorganisms and parasites are toxic in a broad sense, but are generally called pathogens rather than toxicants. The biological toxicity of pathogens can be difficult to measure because the dose may be a single organism. Theoretically one virus, bacterium or worm can reproduce to cause a serious infection, in some cases, e. g. cholera, the disease is chiefly caused by a nonliving substance secreted by the organism, rather than the organism itself. Such nonliving biological toxicants are generally called toxins if produced by a microorganism, plant, or fungus, Physical toxicants are substances that, due to their physical nature, interfere with biological processes. Examples include coal dust, asbestos fibers or finely divided silicon dioxide, corrosive chemicals possess physical toxicity because they destroy tissues, but theyre not directly poisonous unless they interfere directly with biological activity. Water can act as a physical toxicant if taken in high doses because the concentration of vital ions decreases dramatically if theres too much water in the body. Asphyxiant gases can be considered physical toxicants because they act by displacing oxygen in the environment but they are inert, as already mentioned, radiation can have a toxic effect on organisms. Toxicity can be measured by its effects on the target, one such measure is the LD50. When such data does not exist, estimates are made by comparison to known similar toxic things, then, safety factors are added to account for uncertainties in data and evaluation processes. Similarly, an extra protection factor may be used for individuals believed to be susceptible to toxic effects such as in pregnancy or with certain diseases. Obviously, this approach is approximate, but such protection factors are deliberately very conservative. In addition, it is possible that a single cell transformed into a cell is all it takes to develop the full effect. Common mixtures include gasoline, cigarette smoke, and industrial waste, even more complex are situations with more than one type of toxic entity, such as the discharge from a malfunctioning sewage treatment plant, with both chemical and biological agents. The preclinical toxicity testing on various biological systems reveals the species-, organ-, the toxicity of substances can be observed by studying the accidental exposures to a substance in vitro studies using cells/ cell lines in vivo exposure on experimental animals
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Poison
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In biology, poisons are substances that cause disturbances in organisms, usually by chemical reaction or other activity on the molecular scale, when an organism absorbs a sufficient quantity. The fields of medicine and zoology often distinguish a poison from a toxin, toxins are poisons produced by organisms in nature, and venoms are toxins injected by a bite or sting. The difference between venom and other poisons is the delivery method, industry, agriculture, and other sectors use poisons for reasons other than their toxicity. Pesticides are one group of substances whose toxicity to various insects, in 2013,3.3 million cases of unintentional poisonings occurred. This resulted in 98,000 deaths worldwide, down from 120,000 deaths in 1990, the use of poison as an adjective dates from the 1520s. Using the word poison with plant names dates from the 18th century, the term poison ivy, for example, was first used in 1784 and the term poison oak was first used in 1743. The term poison gas was first used in 1915, paracelsus, the father of toxicology, once wrote, Everything is poison, there is poison in everything. Only the dose makes a thing not a poison, the term poison is also used in a figurative sense, His brothers presence poisoned the atmosphere at the party. The law defines poison more strictly, substances not legally required to carry the label poison can also cause a medical condition of poisoning. Some poisons are also toxins, which is any poison produced by animals, vegetables or bacterium, such as the proteins that cause tetanus. A distinction between the two terms is not always observed, even among scientists, the derivative forms toxic and poisonous are synonymous. Animal poisons delivered subcutaneously are also called venom, in normal usage, a poisonous organism is one that is harmful to consume, but a venomous organism uses venom to kill its prey or defend itself while still alive. A single organism can be poisonous and venomous, but that is rare. Human antimicrobial peptides which are toxic to viruses, fungi, bacteria, in nuclear physics, a poison is a substance that obstructs or inhibits a nuclear reaction. For an example, see nuclear poison, environmentally hazardous substances are not necessarily poisons, and vice versa. Biologically speaking, any substance, if given in large amounts, is poisonous. For instance, several kilograms worth of water would constitute a lethal dose, many substances used as medications—such as fentanyl—have an LD50 only one order of magnitude greater than the ED50. An alternative classification distinguishes between lethal substances that provide a value and those that do not
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Biennial plant
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A biennial plant is a flowering plant that takes two years to complete its biological lifecycle. In the first year, the plant grows leaves, stems, usually the stem remains very short and the leaves are low to the ground, forming a rosette. Many biennials require a treatment, or vernalization, before they will flower. During the next spring or summer, the stem of the biennial plant elongates greatly and this typically makes biennial vegetables such as spinach, fennel and lettuce unusable as food. The plant then flowers, producing fruits and seeds before it finally dies, there are far fewer biennials than either perennial plants or annual plants. Under extreme climatic conditions, a plant may complete its life cycle rapidly. This is quite common in vegetable or flower seedlings that were vernalized before they were planted in the ground and this behavior leads to many normally biennial plants being treated as annuals in some areas. From a gardeners perspective, a status as annual, biennial. Biennials grown for flowers, fruits, or seeds need to be grown for two years, biennials that are grown for edible leaves or roots are grown for just one year. Plant breeders have produced annual cultivars of several biennials that will flower the first year from seed, for example, foxglove and stock
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Daucus carota
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Domesticated carrots are cultivars of a subspecies, Daucus carota subsp. The wild carrot is a herbaceous, somewhat variable plant that grows between 30 and 60 cm tall, and is roughly hairy, with a stiff, solid stem. The leaves are tripinnate, finely divided and lacy, and overall triangular in shape, the leaves are bristly and alternate in a pinnate pattern that separates into thin segments. The flowers are small and dull white, clustered in flat, the flowers are terminal and approximately 3-4 inches wide. They may be pink in bud and may have a reddish or purple flower in the centre of the umbel, the lower bracts are three-forked or pinnate, which distinguishes the plant from other white-flowered umbellifers. As the seeds develop, the umbel curls up at the edges, becomes more congested, the fruits are oval and flattened, with short styles and hooked spines. The fruit is small, dry and bumpy with protective hairs surrounding it, the fruit of Daucus Carota has 2 mericarp, or bicarpellate. The endosperm of the fruit grows before the embryo, the dried umbels detach from the plant, becoming tumbleweeds. The function of the red flower, coloured by anthocyanin, is to attract insects. Wild carrot blooms in summer and fall and it thrives best in sun to partial shade. Daucus Carota is commonly found along roadsides and in unused fields, similar in appearance to the deadly poison hemlock, D. Like the cultivated carrot, the D. carota root is edible while young, the flowers are sometimes battered and fried. The leaves are also edible except in large quantities, extra caution should be used when collecting D. carota because it bears a close resemblance to poison hemlock. In addition, the leaves of the wild carrot may cause phytophotodermatitis and it has been used as a method of contraception and an abortifacient for centuries. If used as a dyestuff, the give an creamy. D. carota, when cut, will draw or change color depending on the color of the water in which it is held. This effect is visible on the head or flower of the plant. This occurrence is a popular demonstration in primary grade school
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Europe
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Europe is a continent that comprises the westernmost part of Eurasia. Europe is bordered by the Arctic Ocean to the north, the Atlantic Ocean to the west, yet the non-oceanic borders of Europe—a concept dating back to classical antiquity—are arbitrary. Europe covers about 10,180,000 square kilometres, or 2% of the Earths surface, politically, Europe is divided into about fifty sovereign states of which the Russian Federation is the largest and most populous, spanning 39% of the continent and comprising 15% of its population. Europe had a population of about 740 million as of 2015. Further from the sea, seasonal differences are more noticeable than close to the coast, Europe, in particular ancient Greece, was the birthplace of Western civilization. The fall of the Western Roman Empire, during the period, marked the end of ancient history. Renaissance humanism, exploration, art, and science led to the modern era, from the Age of Discovery onwards, Europe played a predominant role in global affairs. Between the 16th and 20th centuries, European powers controlled at times the Americas, most of Africa, Oceania. The Industrial Revolution, which began in Great Britain at the end of the 18th century, gave rise to economic, cultural, and social change in Western Europe. During the Cold War, Europe was divided along the Iron Curtain between NATO in the west and the Warsaw Pact in the east, until the revolutions of 1989 and fall of the Berlin Wall. In 1955, the Council of Europe was formed following a speech by Sir Winston Churchill and it includes all states except for Belarus, Kazakhstan and Vatican City. Further European integration by some states led to the formation of the European Union, the EU originated in Western Europe but has been expanding eastward since the fall of the Soviet Union in 1991. The European Anthem is Ode to Joy and states celebrate peace, in classical Greek mythology, Europa is the name of either a Phoenician princess or of a queen of Crete. The name contains the elements εὐρύς, wide, broad and ὤψ eye, broad has been an epithet of Earth herself in the reconstructed Proto-Indo-European religion and the poetry devoted to it. For the second part also the divine attributes of grey-eyed Athena or ox-eyed Hera. The same naming motive according to cartographic convention appears in Greek Ανατολή, Martin Litchfield West stated that phonologically, the match between Europas name and any form of the Semitic word is very poor. Next to these there is also a Proto-Indo-European root *h1regʷos, meaning darkness. Most major world languages use words derived from Eurṓpē or Europa to refer to the continent, in some Turkic languages the originally Persian name Frangistan is used casually in referring to much of Europe, besides official names such as Avrupa or Evropa
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Mediterranean region
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As a rule of thumb, the Mediterranean Basin is the Old World region where olive trees grow. The Mediterranean basin covers portions of three continents Africa, Asia, and Europe and it has a varied and contrasting topography. Contrary to the sandy beach images portrayed in most tourist brochures. Mountains can be seen from almost anywhere, the Mediterranean Basin extends into Western Asia, covering the western and southern portions of the peninsula of Turkey, excluding the temperate-climate mountains of central Turkey. It includes the Mediterranean climate Levant at the end of the Mediterranean, bounded on the east and south by the Syrian. The northern portion of the Maghreb region of northwestern Africa has a Mediterranean climate, separated from the Sahara Desert, Europe lies to the north, and three large Southern European peninsulas, the Iberian Peninsula, Italian Peninsula, and the Balkan Peninsula, extend into the Mediterranean-climate zone. The Mediterranean Basin was shaped by the ancient collision of the northward-moving African-Arabian continent with the stable Eurasian continent, as Africa-Arabia moved north, it closed the former Tethys Sea, which formerly separated Eurasia from the ancient super continent of Gondwana, of which Africa was part. At about the time,170 mya in the Jurassic period. The collision pushed up a vast system of mountains, extending from the Pyrenees in Spain to the Zagros Mountains in Iran and this episode of mountain building, known as the Alpine orogeny, occurred mostly during the Oligocene and Miocene epochs. The Neotethys became larger during these collisions and associated folding and subduction, about 6 mya during the late Miocene, the Mediterranean was closed at its western end by drifting Africa, which caused the entire sea to evaporate. There followed several episodes of sea drawdown and re-flooding known as the Messinian Salinity Crisis, recent studies, however, show that repeated desiccation and re-flooding is unlikely from a geodynamic point of view. The end of the Miocene also marked a change in the Mediterranean Basins climate, fossil evidence shows that the Mediterranean Basin had a relatively humid subtropical climate with summer rainfall during the Miocene, which supported laurel forests. The shift to a Mediterranean climate occurred within the last 3. 2–2.8 million years, during the Pliocene epoch, much of these forests and shrublands have been altered beyond recognition by thousands of years of human habitation. There are now very few relatively intact natural areas in what was once a wooded region. The Mediterranean Region was first proposed by German botanist August Grisebach in the late 19th century, drosophyllaceae, recently segregated from Droseraceae, is the only plant family endemic to the region. Among the endemic plant genera are, The genera Aubrieta, Sesamoides, Cynara, Dracunculus, moreover, many plant taxa are shared with one of the four neighboring floristic regions only. The Mediterranean Basin is the largest of the worlds five Mediterranean forests, woodlands and it is home to a number of plant communities, which vary with rainfall, elevation, latitude, and soils. Scrublands occur in the driest areas, especially areas near the seacoast where wind, low, soft-leaved scrublands around the Mediterranean are known as garrigar in Catalan, garrigue in French, phrygana in Greek, tomillares in Spanish, and batha in Hebrew
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Antarctica
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It contains the geographic South Pole and is situated in the Antarctic region of the Southern Hemisphere, almost entirely south of the Antarctic Circle, and is surrounded by the Southern Ocean. At 14,000,000 square kilometres, it is the fifth-largest continent, for comparison, Antarctica is nearly twice the size of Australia. About 98% of Antarctica is covered by ice that averages 1.9 km in thickness, Antarctica, on average, is the coldest, driest, and windiest continent, and has the highest average elevation of all the continents. Antarctica is a desert, with precipitation of only 200 mm along the coast. The temperature in Antarctica has reached −89.2 °C, though the average for the quarter is −63 °C. Anywhere from 1,000 to 5,000 people reside throughout the year at the research stations scattered across the continent. Organisms native to Antarctica include many types of algae, bacteria, fungi, plants, protista, vegetation, where it occurs, is tundra. The continent, however, remained neglected for the rest of the 19th century because of its hostile environment, lack of easily accessible resources. In 1895, the first confirmed landing was conducted by a team of Norwegians, Antarctica is a de facto condominium, governed by parties to the Antarctic Treaty System that have consulting status. Twelve countries signed the Antarctic Treaty in 1959, and thirty-eight have signed it since then, the treaty prohibits military activities and mineral mining, prohibits nuclear explosions and nuclear waste disposal, supports scientific research, and protects the continents ecozone. Ongoing experiments are conducted by more than 4,000 scientists from many nations, the name Antarctica is the romanised version of the Greek compound word ἀνταρκτική, feminine of ἀνταρκτικός, meaning opposite to the Arctic, opposite to the north. Aristotle wrote in his book Meteorology about an Antarctic region in c.350 B. C, marinus of Tyre reportedly used the name in his unpreserved world map from the 2nd century A. D. Before acquiring its present geographical connotations, the term was used for locations that could be defined as opposite to the north. For example, the short-lived French colony established in Brazil in the 16th century was called France Antarctique, the first formal use of the name Antarctica as a continental name in the 1890s is attributed to the Scottish cartographer John George Bartholomew. Antarctica has no population and there is no evidence that it was seen by humans until the 19th century. Explorer Matthew Flinders, in particular, has credited with popularising the transfer of the name Terra Australis to Australia. Cook came within about 120 km of the Antarctic coast before retreating in the face of ice in January 1773. The first confirmed sighting of Antarctica can be narrowed down to the crews of ships captained by three individuals, according to various organisations, ships captained by three men sighted Antarctica or its ice shelf in 1820, von Bellingshausen, Edward Bransfield, and Nathaniel Palmer
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Carnivorous plant
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Carnivorous plants are plants that derive some or most of their nutrients from trapping and consuming animals or protozoans, typically insects and other arthropods. Carnivorous plants have adapted to grow in places where the soil is thin or poor in nutrients, especially nitrogen, such as acidic bogs, charles Darwin wrote Insectivorous Plants, the first well-known treatise on carnivorous plants, in 1875. True carnivory is thought to have evolved independently nine times in five different orders of flowering plants and this classification includes at least 583 species that attract, trap and kill prey, absorbing the resulting available nutrients. Additionally, over 300 protocarnivorous plant species in several genera show some, five basic trapping mechanisms are found in carnivorous plants. Pitfall traps trap prey in a leaf that contains a pool of digestive enzymes or bacteria. Flypaper traps use a sticky mucilage, snap traps utilize rapid leaf movements. Bladder traps suck in prey with a bladder that generates an internal vacuum, lobster-pots, also known as eel traps, force prey to move towards a digestive organ with inward-pointing hairs. These traps may be active or passive, depending on whether movement aids the capture of prey, for example, Triphyophyllum is a passive flypaper that secretes mucilage, but whose leaves do not grow or move in response to prey capture. Meanwhile, sundews are active flypaper traps whose leaves undergo rapid acid growth, the rapid acid growth allows the sundew tentacles to bend, aiding in the retention and digestion of prey. The sundew species Drosera glanduligera employs a unique trapping mechanism with features of both flypaper and snap traps, this has been termed a catapult-flypaper trap, characterized by an internal chamber, pitfall traps are thought to have evolved independently at least six times. This particular adaptation is found within the families Sarraceniaceae, Nepenthaceae, Cephalotaceae, within the family Bromeliaceae, pitcher morphology and carnivory evolved twice. Because these families do not share an ancestor who also had pitfall trap morphology. A passive trap, pitfall traps attract prey with nectar bribes secreted by the peristome, the linings of most pitcher plants are covered in a loose coating of waxy flakes which are slippery for insects, causing them to fall into the pitcher. Once within the structure, digestive enzymes or mutualistic species break down the prey into an absorbable form for the plant. Water can become trapped within the pitcher, making a habitat for other flora and this type of water body is called a Phytotelma. The simplest pitcher plants are probably those of Heliamphora, the pitcher plant. In this genus, the traps are derived from a simple rolled leaf whose margins have sealed together. These plants live in areas of rainfall in South America such as Mount Roraima
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Pitcher (container)
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In US English, a pitcher is a container with a spout used for storing and pouring contents which are liquid in form. In English speaking countries outside North America, a jug is any container with a handle, generally a pitcher also has a handle, which makes pouring easier. A ewer is a pitcher, often decorated, with a base. An example of a ewer is the Americas Cup given to the winner of the Americas Cup sailing regatta match, the word pitcher comes from the 13th century Middle English word picher, which means earthen jug. The word picher is linked to the Old French word pichier which is the version of the word bichier. The pitcher’s origin goes as far back to the Medieval Latin word bicarium from the Greek word bikos, compare with Dutch beker, German Becher and English beaker. An early mention of a pitcher was when the Biblical Book of Genesis mentions of Rebekah coming to Abrahams servant bearing a vessel with water. Another excerpt from the Bible mentions empty pitchers with lamps given by Gideon to three hundred men divided into three companies, in the Book of Judges. Other religions have been known to use such water vessels, one of which is the notable Pitcher of Marwan Ibn Mohammad which predates 8th century AD. The artifact was acquired and unearthed by archeologists on May 15,1930, currently it is on display at the Museum of Islamic Art in Cairo, ewers were also popular works of art during the Tang Dynasty in China. These items once coveted by the classes of China became commonplace artifacts regardless of socioeconomic status. Little pitchers have big ears is a proverb, the phrase depicts a child as the pitcher with ears hearing what people around them say or do, which is stored inside. The adults are also cautioned that the children not be as naïve as they are perceived to be. Amphora Aquamanile Bridge spouted vessel Hydria Jar Jug Oenochoe Porron
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Ancient Greece
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Ancient Greece was a civilization belonging to a period of Greek history from the Greek Dark Ages of the 12th-9th centuries BC to the end of antiquity. Immediately following this period was the beginning of the Early Middle Ages and this was followed by the period of Classical Greece, an era that began with the Greco-Persian Wars, lasting from the 5th to 4th centuries BC. Due to the conquests by Alexander the Great of Macedonia, Hellenistic civilization flourished from Central Asia to the end of the Mediterranean Sea. Classical Greek culture, especially philosophy, had a influence on ancient Rome. For this reason Classical Greece is generally considered to be the culture which provided the foundation of modern Western culture and is considered the cradle of Western civilization. Classical Antiquity in the Mediterranean region is considered to have begun in the 8th century BC. Classical Antiquity in Greece is preceded by the Greek Dark Ages and this period is succeeded, around the 8th century BC, by the Orientalizing Period during which a strong influence of Syro-Hittite, Jewish, Assyrian, Phoenician and Egyptian cultures becomes apparent. The end of the Dark Ages is also dated to 776 BC. The Archaic period gives way to the Classical period around 500 BC, Ancient Periods Astronomical year numbering Dates are approximate, consult particular article for details The history of Greece during Classical Antiquity may be subdivided into five major periods. The earliest of these is the Archaic period, in which artists made larger free-standing sculptures in stiff, the Archaic period is often taken to end with the overthrow of the last tyrant of Athens and the start of Athenian Democracy in 508 BC. It was followed by the Classical period, characterized by a style which was considered by observers to be exemplary, i. e. classical, as shown in the Parthenon. This period saw the Greco-Persian Wars and the Rise of Macedon, following the Classical period was the Hellenistic period, during which Greek culture and power expanded into the Near and Middle East. This period begins with the death of Alexander and ends with the Roman conquest, Herodotus is widely known as the father of history, his Histories are eponymous of the entire field. Herodotus was succeeded by authors such as Thucydides, Xenophon, Demosthenes, Plato, most of these authors were either Athenian or pro-Athenian, which is why far more is known about the history and politics of Athens than those of many other cities. Their scope is limited by a focus on political, military and diplomatic history, ignoring economic. In the 8th century BC, Greece began to emerge from the Dark Ages which followed the fall of the Mycenaean civilization, literacy had been lost and Mycenaean script forgotten, but the Greeks adopted the Phoenician alphabet, modifying it to create the Greek alphabet. The Lelantine War is the earliest documented war of the ancient Greek period and it was fought between the important poleis of Chalcis and Eretria over the fertile Lelantine plain of Euboea. Both cities seem to have suffered a decline as result of the long war, a mercantile class arose in the first half of the 7th century BC, shown by the introduction of coinage in about 680 BC
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Middle Ages
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In the history of Europe, the Middle Ages or Medieval Period lasted from the 5th to the 15th century. It began with the fall of the Western Roman Empire and merged into the Renaissance, the Middle Ages is the middle period of the three traditional divisions of Western history, classical antiquity, the medieval period, and the modern period. The medieval period is subdivided into the Early, High. Population decline, counterurbanisation, invasion, and movement of peoples, the large-scale movements of the Migration Period, including various Germanic peoples, formed new kingdoms in what remained of the Western Roman Empire. In the seventh century, North Africa and the Middle East—once part of the Byzantine Empire—came under the rule of the Umayyad Caliphate, although there were substantial changes in society and political structures, the break with classical antiquity was not complete. The still-sizeable Byzantine Empire survived in the east and remained a major power, the empires law code, the Corpus Juris Civilis or Code of Justinian, was rediscovered in Northern Italy in 1070 and became widely admired later in the Middle Ages. In the West, most kingdoms incorporated the few extant Roman institutions, monasteries were founded as campaigns to Christianise pagan Europe continued. The Franks, under the Carolingian dynasty, briefly established the Carolingian Empire during the later 8th, the Crusades, first preached in 1095, were military attempts by Western European Christians to regain control of the Holy Land from Muslims. Kings became the heads of centralised nation states, reducing crime and violence, intellectual life was marked by scholasticism, a philosophy that emphasised joining faith to reason, and by the founding of universities. Controversy, heresy, and the Western Schism within the Catholic Church paralleled the conflict, civil strife. Cultural and technological developments transformed European society, concluding the Late Middle Ages, the Middle Ages is one of the three major periods in the most enduring scheme for analysing European history, classical civilisation, or Antiquity, the Middle Ages, and the Modern Period. Medieval writers divided history into periods such as the Six Ages or the Four Empires, when referring to their own times, they spoke of them as being modern. In the 1330s, the humanist and poet Petrarch referred to pre-Christian times as antiqua, leonardo Bruni was the first historian to use tripartite periodisation in his History of the Florentine People. Bruni and later argued that Italy had recovered since Petrarchs time. The Middle Ages first appears in Latin in 1469 as media tempestas or middle season, in early usage, there were many variants, including medium aevum, or middle age, first recorded in 1604, and media saecula, or middle ages, first recorded in 1625. The alternative term medieval derives from medium aevum, tripartite periodisation became standard after the German 17th-century historian Christoph Cellarius divided history into three periods, Ancient, Medieval, and Modern. The most commonly given starting point for the Middle Ages is 476, for Europe as a whole,1500 is often considered to be the end of the Middle Ages, but there is no universally agreed upon end date. English historians often use the Battle of Bosworth Field in 1485 to mark the end of the period
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Flying ointment
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Flying ointment, also known as witches flying ointment, green ointment, magic salve and lycanthropic ointment, is a hallucinogenic ointment said to be used by witches in the Early Modern period. The ointment contains a fatty base and various herbal extracts, usually including solanaceous herbs that contain the alkaloids atropine, hyoscyamine and scopolamine, the herbs essential oils are extracted when heated in the base. These oils are poisonous when ingested, when applied to the skin, typical ingredients in alleged recipes include hemlock, deadly nightshade, wolfsbane, and henbane, usually in a base of animal fat. It was said that witches were able to fly to the Sabbath on their brooms with help of the ointment, some sources have claimed that the ointment is absorbed best through mucous membranes, and that it was possibly applied to a special dildo that was inserted in the vagina. This is discussed by Alexander Kuklin in his book, How Do Witches Fly. This antagonism was utilized by the movement of Eclectic medicine, the interaction between belladonna and poppy was made use of in the so-called twilight sleep that was provided for women during childbirth beginning in the Edwardian era. A version is manufactured for use as the injectable compound Omnopon. There is no indication of the proportions of solanaceous herbs vs. poppy used in flying ointments. The use by witches of flying ointments was first described, according to known sources and it was also described by the Spanish theologian Alfonso Tostado in Super Genesis Commentaria, whose commentary tended to accredit the thesis of the reality of the Witches Sabbath. In Mikhail Bulgakovs The Master and Margarita, Margarita, after agreeing to act as hostess at Dr Wolands ball, uses the ointment to become a witch, 2-Babys fat, juice of cowbane, aconite, cinquefoil, deadly nightshade and soot. In the movie serial Warlock, the villain kills a boy to get this Flying Ointment. In Jodi Picoults Salem Falls, a group of four girls practicing witchcraft ingest a flying ointment made of belladonna, in the book Calling on Dragons, the witch Morwen uses a flying potion on a straw basket and a broomstick, not on herself. In E. L. Konigsburgs Jennifer, Hecate, Macbeth, William McKinley, the Swedish symphonic metal band Therion has a song called Unguentum Sabbati on the album Sitra Ahra. A witch kills an infant child and makes flying ointment out of his corpse in the 2015 horror film The Witch
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Indigenous peoples of the Americas
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The indigenous peoples of the Americas are the pre-Columbian peoples of the Americas and their descendants. The term Amerindian is used in Quebec, the Guianas, Indigenous peoples of the United States are commonly known as Native Americans or American Indians, and Alaska Natives. Application of the term Indian originated with Christopher Columbus, who, in his search for Asia, eventually, the Americas came to be known as the West Indies, a name still used to refer to the islands of the Caribbean Sea. This led to the blanket term Indies and Indians for the indigenous inhabitants, although some indigenous peoples of the Americas were traditionally hunter-gatherers—and many, especially in the Amazon basin, still are—many groups practiced aquaculture and agriculture. The impact of their agricultural endowment to the world is a testament to their time, although some societies depended heavily on agriculture, others practiced a mix of farming, hunting, and gathering. In some regions the indigenous peoples created monumental architecture, large-scale organized cities, chiefdoms, states, and empires. Many parts of the Americas are still populated by peoples, some countries have sizable populations, especially Belize, Bolivia, Chile, Ecuador, Greenland, Guatemala, Mexico. At least a different indigenous languages are spoken in the Americas. Some, such as the Quechuan languages, Aymara, Guaraní, Mayan languages, many also maintain aspects of indigenous cultural practices to varying degrees, including religion, social organization, and subsistence practices. Like most cultures, over time, cultures specific to many indigenous peoples have evolved to incorporate traditional aspects, some indigenous peoples still live in relative isolation from Western culture and a few are still counted as uncontacted peoples. The specifics of Paleo-Indian migration to and throughout the Americas, including the dates and routes traveled, are the subject of ongoing research. According to archaeological and genetic evidence, North and South America were the last continents in the world with human habitation. During the Wisconsin glaciation, 50–17,000 years ago, falling sea levels allowed people to move across the bridge of Beringia that joined Siberia to northwest North America. Alaska was a glacial refugium because it had low snowfall, allowing a small population to exist, the Laurentide Ice Sheet covered most of North America, blocking nomadic inhabitants and confining them to Alaska for thousands of years. Indigenous genetic studies suggest that the first inhabitants of the Americas share a single population, one that developed in isolation. The isolation of these peoples in Beringia might have lasted 10–20,000 years, around 16,500 years ago, the glaciers began melting, allowing people to move south and east into Canada and beyond. These people are believed to have followed herds of now-extinct Pleistocene megafauna along ice-free corridors that stretched between the Laurentide and Cordilleran Ice Sheets. Another route proposed involves migration - either on foot or using primitive boats - along the Pacific Northwest coast to the south, archeological evidence of the latter would have been covered by the sea level rise of more than 120 meters since the last ice age
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Arrow poison
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Arrow poisons are used to poison arrow heads or darts for the purposes of hunting and warfare. They have been used by indigenous peoples worldwide and are still in use in areas of South America, Africa and Asia. Notable examples are the poisons secreted from the skin of the dart frog, and curare. Poisoned arrows have featured in mythology, notably the Greek story of Heracles slaying the centaur Nessus using arrows poisoned with the blood of the Lernaean Hydra, the Greek hero Odysseus poisons his arrows with hellebore in Homers Odyssey. Poisoned arrows also figure in Homers epic about the Trojan War, baldrs death in the Norse myths features poison arrows. The modern terms toxic and toxin derive from the ancient Greek word for bow, toxon, from Old Persian *taxa-, poison arrows were used by real peoples in the ancient world, including the Gauls, ancient Romans, and the nomadic Scythians and Soanes. Ancient Greek and Roman historians describe recipes for poisoning projectiles and historical battles in which arrows were used. The use of poisoned arrows in hunting and warfare by some Native Americans has also been documented, over the ages, Chinese warfare has included projectiles poisoned with various toxic substances. Arrow poisons around the world are created from many sources, Curare is a term for arrow poisons that contain tubocurarine, curarine, quinine, protocurarine. Most frequently it is derived from the bark of Strychnos toxifera, S. guianensis, Curare is a competitive antagonist that blocks nicotinic acetylcholine receptors on the post synaptic membrane of the neuromuscular junction. It is a muscle relaxant that causes death by paralyzing the respiratory system, in Africa arrow poisons are made from plants that contain cardiac glycosides, such as Acokanthera, oleander, milkweeds, or Strophanthus, all of which are in the Apocynaceae family. Inee or onaye is a made from Strophanthus hispidus, which contains the cardiac glycoside strophanthin. It is used in sub-Saharan West Africa, particularly in the areas of Togo, poisoned arrows are used widely in the jungle areas of Assam, Burma and Malaysia. The main plant sources for the poisons are members of the Antiaris, Strychnos, Antiaris toxicaria for example, a tree of the mulberry and breadfruit family, is commonly used on Java and its neighbouring islands. The sap or juice of the seeds is smeared on the arrowhead on its own or mixed with plant extracts. The fast-acting active ingredient attacks the nervous system causing paralysis, convulsions. Several species of Aconitum or aconite have been used as arrow poisons, the Minaro in Ladakh use A. napellus on their arrows to hunt Siberian ibex, they were in use recently near lake Issyk Kul in Kyrgyzstan. The Ainus in Japan used a species of Aconitum to hunt brown bear and it was also used by the Butias and Lepchas in Sikkim and Assam
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Nicotinic acetylcholine receptor
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Nicotinic acetylcholine receptors, or nAChRs, are receptor proteins that respond to the neurotransmitter acetylcholine. Nicotinic receptors also respond to drugs, including the nicotinic receptor agonist nicotine, nicotinic receptors are also found in other creatures. In insects, the system is limited to the central nervous system. The nicotinic receptors are considered cholinergic receptors, since they respond to acetylcholine, nicotinic receptors get their name from nicotine, which does not stimulate the muscarinic acetylcholine receptor, but instead selectively binds to the nicotinic receptor. The muscarinic acetylcholine receptor likewise gets its name from a chemical that selectively attaches to that receptor -- muscarine, acetylcholine itself binds to both muscarinic and nicotinic acetylcholine receptors. As ionotropic receptors, nAChRs are directly linked to ion channels, nicotinic acetylcholine receptors are the best-studied of the ionotropic receptors. Thus, for example, nicotinic receptor antagonists interfere with the baroreflex that normally corrects changes in pressure by sympathetic and parasympathetic stimulation of the heart. Nicotinic receptors, with a mass of 290 kDa, are made up of five subunits. Each subunit comprises four transmembrane domains with both the N- and C-terminus located extracellularly and they possess similarities with GABAA receptors, glycine receptors, and the type 3 serotonin receptors, or the signature Cys-loop proteins. In vertebrates, nicotinic receptors are classified into two subtypes based on their primary sites of expression, muscle-type nicotinic receptors and neuronal-type nicotinic receptors. The neuronal subtypes are various homomeric or heteromeric combinations of twelve different nicotinic receptor subunits, α2−α10, examples of the neuronal subtypes include,32,23, and 5. In both muscle-type and neuronal-type receptors, the subunits are similar to one another, especially in the hydrophobic regions. As with all ligand-gated ion channels, opening of the channel pore requires the binding of a chemical messenger. Several different terms are used to refer to the molecules that bind receptors, as well as the endogenous agonist acetylcholine, agonists of the nAChR are nicotine, epibatidine, and choline. Nicotinic antagonists that block the receptor include hexamethonium, in muscle-type nAChRs, the acetylcholine binding sites are located at the α and either ε or δ subunits interface in the extracellular domain near the N terminus. When an agonist binds to the site, all present subunits undergo a change and the channel is opened. Nicotinic AChRs may exist in different interconvertible conformational states, binding of an agonist stabilises the open and desensitised states. Opening of the channel allows positively charged ions to move across it, in particular, sodium enters the cell, the net flow of positively charged ions is inward