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the lining of milk ducts and the lobules that supply these ducts with milk. Cancers developing from the ducts are known as ductal carcinomas, while those developing from lobules are known as lobular carcinomas. There are more than 18 other sub-types of breast cancer. Some, such as ductal carcinoma in situ, develop from pre-invasive lesions. The diagnosis of breast cancer is confirmed by taking a biopsy of the concerning tissue. Once the diagnosis is made, further tests are carried out to determine if the cancer has spread beyond the breast and which treatments are most likely to be effective. == Breastfeeding == The primary function of the breasts, as mammary glands, is the nourishing of an infant with breast milk. Milk is produced in milk-secreting cells in the alveoli. When the breasts are stimulated by the suckling of her baby, the mother's brain secretes oxytocin. High levels of oxytocin trigger the contraction of muscle cells surrounding the alveoli, causing milk to flow along the ducts that connect the alveoli to the nipple. Full-term newborns have an instinct and a need to suck on a nipple, and breastfed babies nurse for both nutrition and for comfort. Breast milk provides all necessary nutrients for the first six months of life, and then remains an important source of nutrition, alongside solid foods, until at least one or two years of age. == Exercise == Biomechanical studies have demonstrated that, depending on the activity and the size of a woman's breast, when she walks or runs braless, her breasts may move up and down by 4 to 18 centimetres (1.6 to 7.1 in) or more, and also oscillate side to side. Researchers have also found that as women's breast size increased, they took part in less physical activity, especially vigorous exercise. Few very-large-breasted women
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jogged, for example. To avoid exercise-related discomfort and pain, medical experts suggest women wear a well-fitted sports bra during activity. == Clinical significance == The breast is susceptible to numerous benign and malignant conditions. The most frequent benign conditions are puerperal mastitis, fibrocystic breast changes and mastalgia. Lactation unrelated to pregnancy is known as galactorrhea. It can be caused by certain drugs (such as antipsychotic medications), extreme physical stress, or endocrine disorders. Lactation in newborns is caused by hormones from the mother that crossed into the baby's bloodstream during pregnancy. === Breast cancer === Breast cancer is the most common cause of cancer death among women and it is one of the leading causes of death among women. Factors that appear to be implicated in decreasing the risk of breast cancer are regular breast examinations by health care professionals, regular mammograms, self-examination of breasts, healthy diet, exercise to decrease excess body fat, and breastfeeding. === Male breasts === Both females and males develop breasts from the same embryological tissues. Anatomically, male breasts do not normally contain lobules and acini that are present in females. In rare instances, it is possible for very few lobules to be present; this makes it possible for some men to develop lobular carcinoma of the breast. Normally, males produce lower levels of estrogens and higher levels of androgens, namely testosterone, which suppress the effects of estrogens in developing excessive breast tissue. In boys and men, abnormal breast development is manifested as gynecomastia, the consequence of a biochemical imbalance between the normal levels of estrogen and testosterone in the male body. Around 70% of boys temporarily develop breast tissue during adolescence. The condition usually resolves by itself within two years. When male lactation occurs, it is considered a symptom of a disorder of the pituitary gland.
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=== Plastic surgery === Plastic surgery can be performed to augment or reduce the size of breasts, or to reconstruct the breast in cases of deformative disease, such as breast cancer. Breast augmentation and breast lift (mastopexy) procedures are done only for cosmetic reasons, whereas breast reduction is sometimes medically indicated. In cases where a woman's breasts are severely asymmetrical, surgery can be performed to either enlarge the smaller breast, reduce the size of the larger breast, or both. Breast augmentation surgery generally does not interfere with future ability to breastfeed. Breast reduction surgery more frequently leads to decreased sensation in the nipple-areola complex, and to low milk supply in women who choose to breastfeed. Implants can interfere with mammography (breast x-ray images). == Society and culture == === General === In Christian iconography, some works of art depict women with their breasts in their hands or on a platter, signifying that they died as a martyr by having their breasts severed; one example of this is Saint Agatha of Sicily. Femen is a feminist activist group which uses topless protests as part of their campaigns against sex tourism religious institutions, sexism, and homophobia. Femen activists have been regularly detained by police in response to their protests. There is a long history of female breasts being used by comedians as a subject for comedy fodder (e.g., British comic Benny Hill's burlesque/slapstick routines). === Art history === In European pre-historic societies, sculptures of female figures with pronounced or highly exaggerated breasts were common. A typical example is the so-called Venus of Willendorf, one of many Paleolithic Venus figurines with ample hips and bosom. Artifacts such as bowls, rock carvings and sacred statues with breasts have been recorded from 15,000 BC up to late antiquity all across Europe, North Africa and the
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Middle East. Many female deities representing love and fertility were associated with breasts and breast milk. Figures of the Phoenician goddess Astarte were represented as pillars studded with breasts. Isis, an Egyptian goddess who represented, among many other things, ideal motherhood, was often portrayed as suckling pharaohs, thereby confirming their divine status as rulers. Even certain male deities representing regeneration and fertility were occasionally depicted with breast-like appendices, such as the river god Hapy who was considered to be responsible for the annual overflowing of the Nile. Female breasts were also prominent in Minoan art in the form of the famous Snake Goddess statuettes, and a few other pieces, though most female breasts are covered. In Ancient Greece there were several cults worshipping the "Kourotrophos", the suckling mother, represented by goddesses such as Gaia, Hera and Artemis. The worship of deities symbolized by the female breast in Greece became less common during the first millennium. The popular adoration of female goddesses decreased significantly during the rise of the Greek city states, a legacy which was passed on to the later Roman Empire. During the middle of the first millennium BC, Greek culture experienced a gradual change in the perception of female breasts. Women in art were covered in clothing from the neck down, including female goddesses like Athena, the patron of Athens who represented heroic endeavor. There were exceptions: Aphrodite, the goddess of love, was more frequently portrayed fully nude, though in postures that were intended to portray shyness or modesty, a portrayal that has been compared to modern pin ups by historian Marilyn Yalom. Although nude men were depicted standing upright, most depictions of female nudity in Greek art occurred "usually with drapery near at hand and with a forward-bending, self-protecting posture". A popular legend at the time was
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of the Amazons, a tribe of fierce female warriors who socialized with men only for procreation and even removed one breast to become better warriors (the idea being that the right breast would interfere with the operation of a bow and arrow). The legend was a popular motif in art during Greek and Roman antiquity and served as an antithetical cautionary tale. === Body image === Many women regard their breasts as important to their sexual attractiveness, as a sign of femininity that is important to their sense of self. A woman with smaller breasts may regard her breasts as less attractive. === Clothing === Because breasts are mostly fatty tissue, their shape canβwithin limitsβbe molded by clothing, such as foundation garments. Bras are commonly worn by about 90% of Western women, and are often worn for support. The social norm in most Western cultures is to cover breasts in public, though the extent of coverage varies depending on the social context. Some religions ascribe a special status to the female breast, either in formal teachings or through symbolism. Islam forbids free women from exposing their breasts in public. Many cultures, including Western cultures in North America, associate breasts with sexuality and tend to regard bare breasts as immodest or indecent. In some cultures, like the Himba in northern Namibia, bare-breasted women are normal. In some African cultures, for example, the thigh is regarded as highly sexualized and never exposed in public, but breast exposure is not taboo. In a few Western countries and regions female toplessness at a beach is acceptable, although it may not be acceptable in the town center. Social attitudes and laws regarding breastfeeding in public vary widely. In many countries, breastfeeding in public is common, legally protected, and generally not regarded as an issue. However,
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even though the practice may be legal or socially accepted, some mothers may nevertheless be reluctant to expose a breast in public to breastfeed due to actual or potential objections by other people, negative comments, or harassment. It is estimated that around 63% of mothers across the world have publicly breast-fed. Bare-breasted women are legal and culturally acceptable at public beaches in Australia and much of Europe. Filmmaker Lina Esco made a film entitled Free the Nipple, which is about "...laws against female toplessness or restrictions on images of female, but not male, nipples", which Esco states is an example of sexism in society. Breast binding, also known as chest binding, is the flattening and hiding of breasts with constrictive materials such as cloth strips or purpose-built undergarments. Binders may also be used as alternatives to bras or for reasons of propriety. People who bind include women, trans men, non-binary people, and cisgender men with gynecomastia. === Sexual characteristic === In some cultures, breasts play a role in human sexual activity. Breasts and especially the nipples are among the various human erogenous zones. They are sensitive to the touch as they have many nerve endings; and it is common to press or massage them with hands or orally before or during sexual activity. During sexual arousal, breast size increases, venous patterns across the breasts become more visible, and nipples harden. Compared to other primates, human breasts are proportionately large throughout adult females' lives. Some writers have suggested that they may have evolved as a visual signal of sexual maturity and fertility. In Patterns of Sexual Behavior, a 1951 analysis of 191 traditional cultures, the researchers noted that stimulation of the female breast by a male sexual partner "seemed absent in all subhuman forms, although it is common among the members
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of many different human societies." Many people regard bare female breasts to be aesthetically pleasing or erotic, and they can elicit heightened sexual desires in men in many cultures. In the ancient Indian work the Kama Sutra, light scratching of the breasts with nails and biting with teeth are considered erotic. Some people show a sexual interest in female breasts distinct from that of the person, which may be regarded as a breast fetish. A number of Western fashions include clothing which accentuate the breasts, such as the use of push-up bras and decollete (plunging neckline) gowns and blouses which show cleavage. While U.S. culture prefers breasts that are youthful and upright, some cultures venerate women with drooping breasts, indicating mothering and the wisdom of experience. Research conducted at the Victoria University of Wellington showed that breasts are often the first thing men look at, and for a longer time than other body parts. The writers of the study had initially speculated that the reason for this is due to endocrinology with larger breasts indicating higher levels of estrogen and a sign of greater fertility, but the researchers said that "Men may be looking more often at the breasts because they are simply aesthetically pleasing, regardless of the size." Some women report achieving an orgasm from nipple stimulation, but this is rare. Research suggests that the orgasms are genital orgasms, and may also be directly linked to "the genital area of the brain". In these cases, it seems that sensation from the nipples travels to the same part of the brain as sensations from the vagina, clitoris and cervix. Nipple stimulation may trigger uterine contractions, which then produce a sensation in the genital area of the brain. === Anthropomorphic geography === There are many mountains named after the breast because
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they resemble it in appearance and so are objects of religious and ancestral veneration as a fertility symbol and of well-being. In Asia, there was "Breast Mountain", which had a cave where the Buddhist monk Bodhidharma (Da Mo) spent much time in meditation. Other such breast mountains are Mount Elgon on the UgandaβKenya border; Beinn ChΓ¬ochan and the Maiden Paps in Scotland; the Bundok ng Susong Dalaga ('Maiden's breast mountains') in Talim Island, Philippines, the twin hills known as the Paps of Anu (DΓ‘ ChΓch Anann or 'the breasts of Anu'), near Killarney in Ireland; the 2,086 m high Tetica de Bacares or La Tetica in the Sierra de Los Filabres, Spain; Khao Nom Sao in Thailand, Cerro Las Tetas in Puerto Rico; and the Breasts of Aphrodite in Mykonos, among many others. In the United States, the Teton Range is named after the French word for 'nipple'. == Measurement == The maturation and size of the breasts can be measured by a variety of different methods. These include Tanner staging, bra cup size, breast volume, breastβchest difference, the breast unit, breast hemicircumference, and breast circumference, among other measures. == See also == Udder == Notes == == References == === Bibliography === Hollander, Anne (1993). Seeing through clothes. Berkeley: University of California Press. ISBN 978-0-520-08231-1. Morris, Desmond The Naked Ape: a zoologist's study of the human animal Bantam Books, Canada. 1967 Yalom, Marilyn (1998). A history of the breast. London: Pandora. ISBN 978-0-86358-400-8. Venes, Donald (2013). Taber's cyclopedic medical dictionary. Philadelphia: F.A. Davis. ISBN 978-0-8036-2977-6. Lawrence, Ruth (2016). Breastfeeding : a guide for the medical profession, 8th edition. Philadelphia, PA: Elsevier. ISBN 978-0-323-35776-0. == External links == "Are Women Evolutionary Sex Objects?: Why Women Have Breasts". Archived from the original on 2 December 2011.
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The Buell dryer, also known as the "turbo shelf" dryer, is an indirectly-heated industrial dryer once widely used in the Cornwall and Devon china clay mining industry. The Buell dryer was introduced to the china clay industry by English Clays Lovering Pochin & Co. Ltd for their china clay drying plants in Cornwall and Devon, as part of the mechanization and modernization of the industry, which up to that point had been using the same primitive processing methods for almost 100 years. == History == The industry's first attempt to mechanize its drying process, an oil-fired rotary dryer installed at Rockhill near Stenalees in 1939, had been halted before it could be commissioned by the outbreak of war, with the Board of Trade exercising its wartime powers to place restrictions on the industry, rationing in particular the use of oil and steel. To circumvent these restrictions, in 1944 a Buell dryer was purchased second hand from a fluorspar mine in Derbyshire, and was installed in an existing building at ECLP's Drinnick site in Nanpean, heated by exhaust steam from Drinnick power plant. As such, it became the first operating mechanical dryer in the Cornish china clay industry, despite not being the first to be constructed. A 1948 Board Of Trade Working Party report into the China Clay industry concluded that restrictions on the industry should be relaxed to allow mechanization to begin. The 1948 report led to Parliament ordering an end to Board Of Trade restrictions on the china clay industry, leading to a period of rapid mechanization. In the 25 years that followed, additional Buell dryers were constructed at Kernick, Drinnick, Rocks, Blackpool near Burngullow, Marsh Mills, Parkandillack, Par Harbour, and Goonvean & Rostowrack Ltd's Trelavour site. The Drinnick dryer site was also expanded to include several more steam-heated
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dryers. == Construction == The dryer itself is composed of a large upright cylindrical chamber, inside of which are 25 to 30 layers of trays or "hearths". Indirectly-heated air from an oil-fired (latterly natural gas-fired) furnace or steam heater is distributed throughout the dryer by a series of fans and ducts. At the center of the dryer is a rotating column, to which the trays are attached and positioned radially within the dryer. Material enters the top of the dryer and lands on one of the top trays. As the central column rotates, fixed arms push the material off the tray, dropping it down onto the one below it. Gradually the material works its way down through the dryer in this manner, and after 45 minutes, clay exits the bottom of the dryer onto conveyor belts. The material to be dried usually enters the top of the dryer with a moisture content of around 18%, and exit at around 8-10%. Generally, these figures all depend on the dewatering processes employed before the material reaches the dryer. Commonly, the Buell dryer handled shredded filter press cakes from standard square plate filter presses, although these were later replaced by a circular-plate filter press capable of operating at much higher pressure. After being shredded, these press cakes were brought by conveyor belt to a paddle mixer in which the cakes were back-mixed with dried clay. The back-mixed clay could then either be extruded into pellets and fed directly to the dryer or, depending on the grade of clay to be produced, might go through an additional stage of pug milling. == External links == Versatile Portable Dryer
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Plantae Delavayanae: Plants from China collected in Yunnan by Father Delavay. is a book by Adrien René Franchet and Père Jean Marie Delavay, with Franchet describing and establishing the taxonomy for flora found by Delavay in Yunnan. == Background == Père Jean Marie Delavay was a missionary sent to China for Missions Etrangères de Paris (Foreign Missions of Paris) on an extended assignment in Yunnan. While in France in 1881, he met Père Armand David, a natural history collector and fellow missionary, and was persuaded to take up David's role of collecting plant specimens in China for the Paris Museum of Natural History. His meticulous methodology led to a prolific collection of plants, which included 200,000 specimens of 4,000 distinct species of flora. As Delavay did not have extensive training on botany, he would collect specimen with even the most minor of differences, which led to the discovery of 1,500 new species of plants within his collections. His work was only slowed when he contracted the bubonic plague in 1888, from which he only partially recovered. Much of Delavay's collections that were sent to the Paris Museum of Natural History were processed by Adrien René Franchet. Franchet was a trained botanist focused on the authorship of taxonomy for the plant specimens arriving at the museum. Franchet primarily worked on the taxonomy of the collections from French missionaries in China and Japan, including Delavay, David, Paul Guillaume Farges, and Jean-André Soulié. Franchet published much of his taxonomy work in academic journals, including "Les Primula du Yun-nan" for Bulletin de la Société botanique de France in 1885. == Description == From 1889 to 1890, Franchet would publish Plantae Delavayanae. Plantes de Chine recueillies au Yun-nan par l'abbé Delavay. "Plantae Delavayanae: Plants from China collected in Yunnan by Father Delavay" is a book
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"title": "Plantae Delavayanae"
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focused on the taxonomy of Père Jean Marie Delavay's flora collection. The text is written in Latin. The book consists of 240 pages of text and 45 plates of illustrations. The original copy consisted of three fascicles, with pages 1-80 and plates 1-15 released in 1889; pages 81-160 and plates 16-30 later released in 1889; and pages 161-240 and plates 31-45 released in 1890. The book provided considerable credibility to Delavay's work in the field of botany. The International Plant Names Index acknowledges that 142 plant names were originally published in the "Pl. Delavay". == References == == External links == Full Scan of the Original Book, including illustrations: https://www.biodiversitylibrary.org/item/41440#page/234/mode/1up
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{
"page_id": 69341579,
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Biology β The natural science that studies life. Areas of focus include structure, function, growth, origin, evolution, distribution, and taxonomy. == History of biology == History of anatomy History of biochemistry History of biotechnology History of botany History of ecology History of genetics History of evolutionary thought: Darwinism Eclipse of Darwinism (Lamarckism, Orthogenesis, Structuralism, and Mutationism) Modern (evolutionary) synthesis History of molecular evolution History of speciation History of marine biology History of medicine History of model organisms History of molecular biology Natural history History of neuroscience History of plant systematics History of pathology History of virology History of zoology == Overview == Biology Science Life Properties: Adaptation β Energy processing β Growth β Order β Regulation β Reproduction β Response to environment Biological organization: atom β molecule β cell β tissue β organ β organ system β organism β population β community β ecosystem β biosphere Approach: Reductionism β emergent property β mechanistic Biology as a science: Natural science Scientific method: observation β research question β hypothesis β testability β prediction β experiment β data β statistics Scientific theory β scientific law Research method List of research methods in biology Scientific literature List of biology journals: peer review == Chemical basis == Outline of biochemistry Atoms and molecules matter β element β atom β proton β neutron β electronβ Bohr model β isotope β chemical bond β ionic bond β ions β covalent bond β hydrogen bond β molecule Water: properties of water β solvent β cohesion β adhesion β surface tension β pH Organic compounds: carbon β carbon-carbon bonds β hydrocarbon β monosaccharide β amino acids β nucleotide β functional group β monomer β adenosine triphosphate (ATP) β lipids β oil β sugar β vitamins β neurotransmitter β wax Macromolecules: polysaccharide: cellulose β carbohydrate β chitin β glycogen β
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starch proteins: primary structure β secondary structure β tertiary structure β conformation β native state β protein folding β enzyme β receptor β transmembrane receptor β ion channel β membrane transporter β collagen β pigments: chlorophyll β carotenoid β xanthophyll β melanin β prion lipids: cell membrane β fats β phospholipids nucleic acids: DNA β RNA == Cells == Outline of cell biology Cell structure: Cell coined by Robert Hooke Techniques: cell culture β flow cytometry β microscope β light microscope β electron microscopy β SEM β TEM β live cell imaging Organelles: Cytoplasm β Vacuole β Peroxisome β Plastid Cell nucleus Nucleoplasm β Nucleolus β Chromatin β Chromosome Endomembrane system Nuclear envelope β Endoplasmic reticulum β Golgi apparatus β Vesicles β Lysosome Energy creators: Mitochondrion and Chloroplast Biological membranes: Plasma membrane β Mitochondrial membrane β Chloroplast membrane Other subcellular features: Cell wall β pseudopod β cytoskeleton β mitotic spindle β flagellum β cilium Cell transport: Diffusion β Osmosis β isotonic β active transport β phagocytosis Cellular reproduction: cytokinesis β centromere β meiosis Nuclear reproduction: mitosis β interphase β prophase β metaphase β anaphase β telophase programmed cell death β apoptosis β cell senescence Metabolism: enzyme - activation energy - proteolysis β cooperativity Cellular respiration Glycolysis β Pyruvate dehydrogenase complex β Citric acid cycle β electron transport chain β fermentation Photosynthesis light-dependent reactions β Calvin cycle Cell cycle mitosis β chromosome β haploid β diploid β polyploidy β prophase β metaphase β anaphase β telophase β cytokinesis β meiosis == Genetics == Outline of Genetics Inheritance heredity β Mendelian inheritance β gene β locus β trait β allele β polymorphism β homozygote β heterozygote β hybrid β hybridization β dihybrid cross β Punnett square β inbreeding genotypeβphenotype distinction β genotype β phenotype β dominant gene β recessive gene genetic interactions
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β Mendel's law of segregation β genetic mosaic β maternal effect β penetrance β complementation β suppression β epistasis β genetic linkage Model organisms: Drosophila β Arabidopsis β Caenorhabditis elegans β mouse β Saccharomyces cerevisiae β Escherichia coli β Lambda phage β Xenopus β chicken β zebrafish β Ciona intestinalis β amphioxus Techniques: genetic screen β linkage map β genetic map DNA Nucleic acid double helix Nucleobase: adenine (A) β cytosine (C) β guanine (G) β thymine (T) β uracil (U) DNA replication β mutation β mutation rate β proofreading β DNA mismatch repair β point mutation β crossover β recombination β plasmid β transposon Gene expression Central dogma of molecular biology: nucleosome β genetic code β codon β transcription factor β transcription β translation β RNA β histone β telomere heterochromatin β promoter β RNA polymerase Protein biosynthesis β ribosomes Gene regulation operon β activator β repressor β corepressor β enhancer β alternative splicing Genomes DNA sequencing β high throughput sequencing β bioinformatics Proteome β proteomics β metabolome β metabolomics DNA paternity testing Biotechnology (see also Outline of biochemical techniques and Molecular biology): DNA fingerprinting β genetic fingerprint β microsatellite β gene knockout β imprinting β RNA interference Genomics β computational biology β bioinformatics β gel electrophoresis β transformation β PCR β PCR mutagenesis β primer β chromosome walking β RFLP β restriction enzyme β sequencing β shotgun sequencing β cloning β culture β DNA microarray β electrophoresis β protein tag β affinity chromatography β x-ray diffraction β proteomics β mass spectrometry β CRISPR β gene therapy Genes, development, and evolution Apoptosis French flag model Pattern formation Evo-devo gene toolkit Transcription factor == Evolution == Outline of evolution (see also evolutionary biology) Evolutionary processes evolution microevolution: adaptation β selection β natural selection β directional selection β sexual selection β
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genetic drift β sexual reproduction β asexual reproduction β colony β allele frequency β neutral theory of molecular evolution β population genetics β HardyβWeinberg principle Speciation Species Phylogeny Lineage (evolution) β evolutionary tree β cladistics β species β taxon β clade β monophyletic β polyphyly β paraphyly β heredity β phenotypic trait β nucleic acid sequence β synapomorphy β homology β molecular clock β outgroup (cladistics) β maximum parsimony (phylogenetics) β Computational phylogenetics Linnaean taxonomy: Carl Linnaeus β domain (biology) β kingdom (biology) β phylum β class (biology) β order (biology) β family (biology) β genus β species Three-domain system: archaea β bacteria β eukaryote β protist β fungi β plant β animal Binomial nomenclature: scientific classification β Homo sapiens History of life Origin of life β hierarchy of life β MillerβUrey experiment Macroevolution: adaptive radiation β convergent evolution β extinction β mass extinction β fossil β taphonomy β geologic time β plate tectonics β continental drift β vicariance β Gondwana β Pangaea β endosymbiosis == Diversity == Bacteria and Archaea Protists Plant diversity Green algae Chlorophyta Charophyta Bryophytes Marchantiophyta Anthocerotophyta Moss Pteridophytes Lycopodiophyta Polypodiophyta Seed plants Cycadophyta Ginkgophyta Pinophyta Gnetophyta Magnoliophyta Fungi Yeast β mold (fungus) β mushroom Animal diversity Invertebrates: sponge β cnidarian β coral β jellyfish β Hydra (genus) β sea anemone flatworms β nematodes arthropods: crustacean β chelicerata β myriapoda β arachnids β insects β annelids β molluscs Vertebrates: fishes: β agnatha β chondrichthyes β osteichthyes Tiktaalik tetrapods amphibians reptiles birds flightless birds β Neognathae β dinosaurs mammals placental: primates marsupial monotreme Viruses DNA viruses β RNA viruses β retroviruses == Plant form and function == Plant body Organ systems: root β shoot β stem β leaf β flower Plant nutrition and transport Vascular tissue β bark (botany) β Casparian strip β turgor pressure β xylem
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β phloem β transpiration β wood β trunk (botany) Plant development tropism β taxis seed β cotyledon β meristem β apical meristem β vascular cambium β cork cambium alternation of generations β gametophyte β antheridium β archegonium β sporophyte β spore β sporangium Plant reproduction angiosperms β flower β reproduction β sperm β pollination β self-pollination β cross-pollination β nectar β pollen Plant responses Plant hormone β ripening β fruit β Ethylene as a plant hormone β toxin β pollinator β phototropism β skototropism β phototropin β phytochrome β auxin β photoperiodism β gravity == Animal form and function == General features: morphology (biology) β anatomy β physiology β biological tissues β organ (biology) β organ systems Water and salt balance Body fluids: osmotic pressure β ionic composition β volume Diffusion β osmosis) β Tonicity β sodium β potassium β calcium β chloride Excretion Nutrition and digestion Digestive system: stomach β intestine β liver β nutrition β primary nutritional groups metabolism β kidney β excretion Breathing Respiratory system: lungs Circulation Circulatory system: heart β artery β vein β capillary β Blood β blood cell Lymphatic system: lymph node Muscle and movement Skeletal system: bone β cartilage β joint β tendon Muscular system: muscle β actin β myosin β reflex Nervous system Neuron β dendrite β axon β nerve β electrochemical gradient β electrophysiology β action potential β signal transduction β synapse β receptor β Central nervous system: brain β spinal cord limbic system β memory β vestibular system Peripheral nervous system Sensory nervous system: eye β vision β audition β proprioception β olfaction β Integumentary system: skin cell Hormonal control Endocrine system: hormone Animal reproduction Reproductive system: testes β ovary β pregnancy Fish#Reproductive system Mammalian reproductive system Human reproductive system Mammalian penis Os penis Penile spines Genitalia of bottlenose dolphins
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Genitalia of marsupials Equine reproductive system Even-toed ungulate#Genitourinary system Bull#Reproductive anatomy Carnivora#Reproductive system Fossa (animal)#External genitalia Female genitalia of spotted hyenas Cat anatomy#Genitalia Genitalia of dogs Canine penis Bulbus glandis Animal development stem cell β blastula β gastrula β egg (biology) β fetus β placenta - gamete β spermatid β ovum β zygote β embryo β cellular differentiation β morphogenesis β homeobox Immune system antibody β host β vaccine β immune cell β AIDS β T cell β leucocyte Animal behavior Behavior: mating β animal communication β seek shelter β migration (ecology) Fixed action pattern Altruism (biology) == Ecology == Outline of ecology Ecosystems: Ecology β Biodiversity β habitat β plankton β thermocline β saprobe Abiotic component: water β light β radiation β temperature β humidity β atmosphere β acidity Microbe β biomass β organic matter β decomposer β decomposition β carbon β nutrient cycling β solar energy β topography β tilt β Windward and leeward β precipitation Temperature β biome Populations Population ecology: organism β geographical area β sexual reproduction β population density β population growth β birth rate β death Rate β immigration rate β exponential growth β carrying capacity β logistic function β natural environment β competition (biology) β mating β biological dispersal β endemic (ecology) β growth curve (biology) β habitat β drinking water β resource β human population β technology β Green revolution Communities Community (ecology) β ecological niche β keystone species β mimicry β symbiosis β pollination β mutualism β commensalism β parasitism β predation β invasive species β environmental heterogeneity β edge effect Consumerβresource interactions: food chain β food web β autotroph β heterotrophs β herbivore β carnivore β trophic level Biosphere lithosphere β atmosphere β hydrosphere biogeochemical cycle: nitrogen cycle β carbon cycle β water cycle Climate change: Fossil fuel β coal
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β oil β natural gas β World energy consumption β Climate change feedback β Albedo β water vapor Carbon sink Conservation Biodiversity β habitats β Ecosystem services β biodiversity loss β extinction β Sustainability β Holocene extinction β bioremediation == Branches == Anatomy β study of form in animals, plants and other organisms, or specifically in humans. Simply, the study of internal structure of living organisms. Physiology β study of the internal workings of organisms and the functions of anatomical structures. Comparative anatomy β the study of evolution of species through similarities and differences in their anatomy. Gross anatomy β study of anatomy at the macroscopic level Histology β also known as microscopic anatomy or microanatomy, the branch of biology which studies the microscopic anatomy of biological tissues. Neuroanatomy β the study of the nervous system. Osteology β study of bones. Radiographic anatomy β study of anatomy through radiography Surface anatomy β study of external features of a body Biochemistry β study of the chemical reactions required for life to exist and function, usually a focus on the cellular level. Biophysics β study of biological processes through the methods traditionally used in the physical sciences. Biomechanics β the study of the mechanics of living beings. Cellular biophysics β study of physical principles underlying cell function Neurophysics β study of the development of the nervous system on a molecular level. Molecular biophysics β study of physical properties of biomolecules at the molecular level Quantum biology β application of quantum mechanics and theoretical chemistry to biological objects and problems. Virophysics β study of mechanics and dynamics driving the interactions between virus and cells. Biotechnology β new and sometimes controversial branch of biology that studies the manipulation of living matter, including genetic modification and synthetic biology. Bioinformatics β use of information technology for
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the study, collection, and storage of genomic and other biological data. Bioengineering β study of biology through the means of engineering with an emphasis on applied knowledge and especially related to biotechnology. Synthetic biology β research integrating biology and engineering; construction of biological functions not found in nature. Botany β study of plants. Economic botany β study of relationship between people and plants, including the practical uses of plants Ethnobotany β study of a region's plants and their usage by people Photobiology β scientific study of the interactions of light (technically, non-ionizing radiation) and living organisms. The field includes the study of photosynthesis, photomorphogenesis, visual processing, circadian rhythms, bioluminescence, and ultraviolet radiation effects. Phycology β scientific study of algae. Plant anatomy β study of internal structure of plants Plant ecology β study of how plants interact with each other and their environment Plant genetics β study of heredity and variation in plants Plant pathology β study of plant diseases Plant physiology β subdiscipline of botany concerned with the functioning, or physiology, of plants. Cell biology β study of the cell as a complete unit, and the molecular and chemical interactions that occur within a living cell. Histology β study of the anatomy of cells and tissues of plants and animals using microscopy. Chronobiology β field of biology that examines periodic (cyclic) phenomena in living organisms and their adaptation to solar- and lunar-related rhythms. Dendrochronology β study of tree rings, using them to date the exact year they were formed in order to analyze atmospheric conditions during different periods in natural history. Developmental biology β study of the processes through which an organism forms, from zygote to full structure Embryology β study of the development of embryo (from fecundation to birth). Gerontology β study of aging processes. Ecology β study of
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the interactions of living organisms with one another and with the non-living elements of their environment. Behavioral ecology β the study of the evolutionary basis for animal behavior due to ecological pressure Ecosystem ecology β study of biotic and abiotic components of ecosystems and their interactions within an ecosystem Landscape ecology β study of relationships between ecological processes in the environment and particular ecosystems Microbial ecology β study of the relationships between microorganisms and their environments Population ecology β study of dynamics of species populations and how these populations interact with the environment Urban ecology β study of the relationships between living organisms with each other and their urban environment. Biogeography β study of the distribution of species spatially and temporally. Evolutionary biology β study of the origin and descent of species over time. Evolutionary developmental biology β field of biology that compares the developmental processes of different organisms to determine the ancestral relationship between them, and to discover how developmental processes evolved. Paleobiology β discipline which combines the methods and findings of the life sciences with the methods and findings of the earth science, paleontology. Paleoanthropology β the study of fossil evidence for human evolution, mainly using remains from extinct hominin and other primate species to determine the morphological and behavioral changes in the human lineage, as well as the environment in which human evolution occurred. Paleobotany β study of fossil plants. Paleontology β study of fossils and sometimes geographic evidence of prehistoric life. Paleopathology β the study of pathogenic conditions observable in bones or mummified soft tissue, and on nutritional disorders, variation in stature or morphology of bones over time, evidence of physical trauma, or evidence of occupationally derived biomechanic stress. Genetics β study of genes and heredity. Molecular genetics β study of the bimolecular mechanisms behind the
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structure and function of DNA Quantitative genetics β study of phenotypes that vary continuously (in characters such as height or mass)βas opposed to discretely identifiable phenotypes and gene-products (such as eye-colour, or the presence of a particular biochemical). Marine biology β study of ocean ecosystems, plants, animals, and other living beings. Microbiology β study of microscopic organisms (microorganisms) and their interactions with other living things. Bacteriology β study of bacteria Immunology β study of immune systems in all organisms. Mycology β study of fungi Parasitology β study of parasites and parasitism. Virology β study of viruses Biochemistry Molecular biology β study of biology and biological functions at the molecular level, with some cross over from biochemistry. Structural biology β a branch of molecular biology, biochemistry, and biophysics concerned with the molecular structure of biological macromolecules. Health sciences and human biology β biology of humans. Medicine β Diagnosis, treatment, and prevention of illness. Endocrinology β study of the endocrine system. Oncology β study of cancer processes, including virus or mutation, oncogenesis, angiogenesis, and tissues remoldings. Pharmacology β study of medication and drugs Epidemiology β major component of public health research, studying factors affecting the health of populations. Neuroscience β study of the nervous system, including anatomy, physiology and emergent proprieties. Behavioral neuroscience β study of physiological, genetic, and developmental mechanisms of behavior in humans and other animals. Cellular neuroscience β study of neurons at a cellular level. Cognitive neuroscience β study of biological substrates underlying cognition, with a focus on the neural substrates of mental processes. Computational neuroscience β study of the information processing functions of the nervous system, and the use of digital computers to study the nervous system. Developmental neuroscience β study of the cellular basis of brain development and addresses the underlying mechanisms. Molecular neuroscience β studies the
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biology of the nervous system with molecular biology, molecular genetics, protein chemistry and related methodologies. Neuroanatomy β study of the anatomy of nervous tissue and neural structures of the nervous system. Neuroendocrinology β studies the interaction between the nervous system and the endocrine system, that is how the brain regulates the hormonal activity in the body. Neuroethology β study of animal behavior and its underlying mechanistic control by the nervous system. Neuroimmunology β study of the nervous system, and immunology, the study of the immune system. Neuropharmacology β study of how drugs affect cellular function in the nervous system. Neurophysiology β study of the function (as opposed to structure) of the nervous system. Systems neuroscience β studies the function of neural circuits and systems. Theoretical Biology β the mathematical modeling of biological phenomena. Systems biology β computational modeling of biological systems. Zoology β study of animals, including classification, physiology, development, and behavior. Subbranches include: Arthropodology β biological discipline concerned with the study of arthropods, a phylum of animals that include the insects, arachnids, crustaceans and others that are characterized by the possession of jointed limbs. Acarology β study of the taxon of arachnids that contains mites and ticks. Arachnology β scientific study of spiders and related animals such as scorpions, pseudoscorpions, harvestmen, collectively called arachnids. Entomology β study of insects. Coleopterology β study of beetles. Lepidopterology β study of a large order of insects that includes moths and butterflies (called lepidopterans). Myrmecology β scientific study of ants. Carcinology β study of crustaceans. Myriapodology β study of centipedes, millipedes, and other myriapods. Ethology β scientific study of animal behavior, usually with a focus on behavior under natural conditions. Helminthology β study of worms, especially parasitic worms. Herpetology β study of amphibians (including frogs, toads, salamanders, newts, and gymnophiona) and reptiles (including
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snakes, lizards, amphisbaenids, turtles, terrapins, tortoises, crocodilians, and the tuataras). Batrachology β subdiscipline of herpetology concerned with the study of amphibians alone. Ichthyology β study of fishes. This includes bony fishes (Osteichthyes), cartilaginous fishes (Chondrichthyes), and jawless fishes (Agnatha). Malacology β branch of invertebrate zoology which deals with the study of the Mollusca (mollusks or molluscs), the second-largest phylum of animals in terms of described species after the arthropods. Teuthology β branch of Malacology which deals with the study of cephalopods. Mammalogy β study of mammals, a class of vertebrates with characteristics such as homeothermic metabolism, fur, four-chambered hearts, and complex nervous systems. Mammalogy has also been known as "mastology," "theriology," and "therology." There are about 4,200 different species of animals which are considered mammals. Cetology β branch of marine mammal science that studies the approximately eighty species of whales, dolphins, and porpoise in the scientific order Cetacea. Primatology β scientific study of primates Human biology β interdisciplinary field studying the range of humans and human populations via biology/life sciences, anthropology/social sciences, applied/medical sciences Biological anthropology β subfield of anthropology that studies the physical morphology, genetics and behavior of the human genus, other hominins and hominids across their evolutionary development Human behavioral ecology β the study of behavioral adaptations (foraging, reproduction, ontogeny) from the evolutionary and ecologic perspectives (see behavioral ecology). It focuses on human adaptive responses (physiological, developmental, genetic) to environmental stresses. Nematology β scientific discipline concerned with the study of nematodes, or roundworms. Ornithology β scientific study of birds. Interdisciplinary fields Astrobiology β study of potential life outside of Earth. Bioarchaeology β study of human and animal remains from archaeological sites. Geobiology β study of the interactions between the physical Earth and the biosphere. Biolinguistics β biological study of language. Biological anthropology β study of the development of
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the human species. == Biologists == Lists of notable biologists List of notable biologists List of Nobel Prize winners in physiology or medicine Lists of biologists by author abbreviation List of authors of names published under the ICZN Lists of biologists by subject List of biochemists List of ecologists List of neuroscientists List of physiologists == See also == Bibliography of biology Earliest known life forms Invasion biology terminology List of omics topics in biology Related outlines Outline of life forms Outline of zoology Outline of engineering Outline of technology List of social sciences Journals Biology journals == References == == External links == OSU's Phylocode The Tree of Life: A multi-authored, distributed Internet project containing information about phylogeny and biodiversity. MIT video lecture series on biology A wiki site for protocol sharing run from MIT. Biology and Bioethics. Biology online wiki dictionary. Biology Video Sharing Community. What is Biotechnology Archived 19 April 2012 at the Wayback Machine : a voluntary program as Biotech for Beginners.
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Biotechnology is a multidisciplinary field that involves the integration of natural sciences and engineering sciences in order to achieve the application of organisms and parts thereof for products and services. Specialists in the field are known as biotechnologists. The term biotechnology was first used by KΓ‘roly Ereky in 1919 to refer to the production of products from raw materials with the aid of living organisms. The core principle of biotechnology involves harnessing biological systems and organisms, such as bacteria, yeast, and plants, to perform specific tasks or produce valuable substances. Biotechnology had a significant impact on many areas of society, from medicine to agriculture to environmental science. One of the key techniques used in biotechnology is genetic engineering, which allows scientists to modify the genetic makeup of organisms to achieve desired outcomes. This can involve inserting genes from one organism into another, and consequently, create new traits or modifying existing ones. Other important techniques used in biotechnology include tissue culture, which allows researchers to grow cells and tissues in the lab for research and medical purposes, and fermentation, which is used to produce a wide range of products such as beer, wine, and cheese. The applications of biotechnology are diverse and have led to the development of products like life-saving drugs, biofuels, genetically modified crops, and innovative materials. It has also been used to address environmental challenges, such as developing biodegradable plastics and using microorganisms to clean up contaminated sites. Biotechnology is a rapidly evolving field with significant potential to address pressing global challenges and improve the quality of life for people around the world; however, despite its numerous benefits, it also poses ethical and societal challenges, such as questions around genetic modification and intellectual property rights. As a result, there is ongoing debate and regulation surrounding the use and
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application of biotechnology in various industries and fields. == Definition == The concept of biotechnology encompasses a wide range of procedures for modifying living organisms for human purposes, going back to domestication of animals, cultivation of plants, and "improvements" to these through breeding programs that employ artificial selection and hybridization. Modern usage also includes genetic engineering, as well as cell and tissue culture technologies. The American Chemical Society defines biotechnology as the application of biological organisms, systems, or processes by various industries to learning about the science of life and the improvement of the value of materials and organisms, such as pharmaceuticals, crops, and livestock. As per the European Federation of Biotechnology, biotechnology is the integration of natural science and organisms, cells, parts thereof, and molecular analogues for products and services. Biotechnology is based on the basic biological sciences (e.g., molecular biology, biochemistry, cell biology, embryology, genetics, microbiology) and conversely provides methods to support and perform basic research in biology. Biotechnology is the research and development in the laboratory using bioinformatics for exploration, extraction, exploitation, and production from any living organisms and any source of biomass by means of biochemical engineering where high value-added products could be planned (reproduced by biosynthesis, for example), forecasted, formulated, developed, manufactured, and marketed for the purpose of sustainable operations (for the return from bottomless initial investment on R & D) and gaining durable patents rights (for exclusives rights for sales, and prior to this to receive national and international approval from the results on animal experiment and human experiment, especially on the pharmaceutical branch of biotechnology to prevent any undetected side-effects or safety concerns by using the products). The utilization of biological processes, organisms or systems to produce products that are anticipated to improve human lives is termed biotechnology. By contrast, bioengineering is generally
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thought of as a related field that more heavily emphasizes higher systems approaches (not necessarily the altering or using of biological materials directly) for interfacing with and utilizing living things. Bioengineering is the application of the principles of engineering and natural sciences to tissues, cells, and molecules. This can be considered as the use of knowledge from working with and manipulating biology to achieve a result that can improve functions in plants and animals. Relatedly, biomedical engineering is an overlapping field that often draws upon and applies biotechnology (by various definitions), especially in certain sub-fields of biomedical or chemical engineering such as tissue engineering, biopharmaceutical engineering, and genetic engineering. == History == Although not normally what first comes to mind, many forms of human-derived agriculture clearly fit the broad definition of "utilizing a biotechnological system to make products". Indeed, the cultivation of plants may be viewed as the earliest biotechnological enterprise. Agriculture has been theorized to have become the dominant way of producing food since the Neolithic Revolution. Through early biotechnology, the earliest farmers selected and bred the best-suited crops (e.g., those with the highest yields) to produce enough food to support a growing population. As crops and fields became increasingly large and difficult to maintain, it was discovered that specific organisms and their by-products could effectively fertilize, restore nitrogen, and control pests. Throughout the history of agriculture, farmers have inadvertently altered the genetics of their crops through introducing them to new environments and breeding them with other plants β one of the first forms of biotechnology. These processes also were included in early fermentation of beer. These processes were introduced in early Mesopotamia, Egypt, China and India, and still use the same basic biological methods. In brewing, malted grains (containing enzymes) convert starch from grains into sugar and then
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adding specific yeasts to produce beer. In this process, carbohydrates in the grains broke down into alcohols, such as ethanol. Later, other cultures produced the process of lactic acid fermentation, which produced other preserved foods, such as soy sauce. Fermentation was also used in this time period to produce leavened bread. Although the process of fermentation was not fully understood until Louis Pasteur's work in 1857, it is still the first use of biotechnology to convert a food source into another form. Before the time of Charles Darwin's work and life, animal and plant scientists had already used selective breeding. Darwin added to that body of work with his scientific observations about the ability of science to change species. These accounts contributed to Darwin's theory of natural selection. For thousands of years, humans have used selective breeding to improve the production of crops and livestock to use them for food. In selective breeding, organisms with desirable characteristics are mated to produce offspring with the same characteristics. For example, this technique was used with corn to produce the largest and sweetest crops. In the early twentieth century scientists gained a greater understanding of microbiology and explored ways of manufacturing specific products. In 1917, Chaim Weizmann first used a pure microbiological culture in an industrial process, that of manufacturing corn starch using Clostridium acetobutylicum, to produce acetone, which the United Kingdom desperately needed to manufacture explosives during World War I. Biotechnology has also led to the development of antibiotics. In 1928, Alexander Fleming discovered the mold Penicillium. His work led to the purification of the antibiotic formed by the mold by Howard Florey, Ernst Boris Chain and Norman Heatley β to form what we today know as penicillin. In 1940, penicillin became available for medicinal use to treat bacterial infections in humans.
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The field of modern biotechnology is generally thought of as having been born in 1971 when Paul Berg's (Stanford) experiments in gene splicing had early success. Herbert W. Boyer (Univ. Calif. at San Francisco) and Stanley N. Cohen (Stanford) significantly advanced the new technology in 1972 by transferring genetic material into a bacterium, such that the imported material would be reproduced. The commercial viability of a biotechnology industry was significantly expanded on June 16, 1980, when the United States Supreme Court ruled that a genetically modified microorganism could be patented in the case of Diamond v. Chakrabarty. Indian-born Ananda Chakrabarty, working for General Electric, had modified a bacterium (of the genus Pseudomonas) capable of breaking down crude oil, which he proposed to use in treating oil spills. (Chakrabarty's work did not involve gene manipulation but rather the transfer of entire organelles between strains of the Pseudomonas bacterium). The MOSFET invented at Bell Labs between 1955 and 1960, Two years later, Leland C. Clark and Champ Lyons invented the first biosensor in 1962. Biosensor MOSFETs were later developed, and they have since been widely used to measure physical, chemical, biological and environmental parameters. The first BioFET was the ion-sensitive field-effect transistor (ISFET), invented by Piet Bergveld in 1970. It is a special type of MOSFET, where the metal gate is replaced by an ion-sensitive membrane, electrolyte solution and reference electrode. The ISFET is widely used in biomedical applications, such as the detection of DNA hybridization, biomarker detection from blood, antibody detection, glucose measurement, pH sensing, and genetic technology. By the mid-1980s, other BioFETs had been developed, including the gas sensor FET (GASFET), pressure sensor FET (PRESSFET), chemical field-effect transistor (ChemFET), reference ISFET (REFET), enzyme-modified FET (ENFET) and immunologically modified FET (IMFET). By the early 2000s, BioFETs such as the DNA field-effect
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transistor (DNAFET), gene-modified FET (GenFET) and cell-potential BioFET (CPFET) had been developed. A factor influencing the biotechnology sector's success is improved intellectual property rights legislationβand enforcementβworldwide, as well as strengthened demand for medical and pharmaceutical products. Rising demand for biofuels is expected to be good news for the biotechnology sector, with the Department of Energy estimating ethanol usage could reduce U.S. petroleum-derived fuel consumption by up to 30% by 2030. The biotechnology sector has allowed the U.S. farming industry to rapidly increase its supply of corn and soybeansβthe main inputs into biofuelsβby developing genetically modified seeds that resist pests and drought. By increasing farm productivity, biotechnology boosts biofuel production. == Examples == Biotechnology has applications in four major industrial areas, including health care (medical), crop production and agriculture, non-food (industrial) uses of crops and other products (e.g., biodegradable plastics, vegetable oil, biofuels), and environmental uses. For example, one application of biotechnology is the directed use of microorganisms for the manufacture of organic products (examples include beer and milk products). Another example is using naturally present bacteria by the mining industry in bioleaching. Biotechnology is also used to recycle, treat waste, clean up sites contaminated by industrial activities (bioremediation), and also to produce biological weapons. A series of derived terms have been coined to identify several branches of biotechnology, for example: Bioinformatics (or "gold biotechnology") is an interdisciplinary field that addresses biological problems using computational techniques, and makes the rapid organization as well as analysis of biological data possible. The field may also be referred to as computational biology, and can be defined as, "conceptualizing biology in terms of molecules and then applying informatics techniques to understand and organize the information associated with these molecules, on a large scale". Bioinformatics plays a key role in various areas, such as functional genomics,
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structural genomics, and proteomics, and forms a key component in the biotechnology and pharmaceutical sector. Blue biotechnology is based on the exploitation of sea resources to create products and industrial applications. This branch of biotechnology is the most used for the industries of refining and combustion principally on the production of bio-oils with photosynthetic micro-algae. Green biotechnology is biotechnology applied to agricultural processes. An example would be the selection and domestication of plants via micropropagation. Another example is the designing of transgenic plants to grow under specific environments in the presence (or absence) of chemicals. One hope is that green biotechnology might produce more environmentally friendly solutions than traditional industrial agriculture. An example of this is the engineering of a plant to express a pesticide, thereby ending the need of external application of pesticides. An example of this would be Bt corn. Whether or not green biotechnology products such as this are ultimately more environmentally friendly is a topic of considerable debate. It is commonly considered as the next phase of green revolution, which can be seen as a platform to eradicate world hunger by using technologies which enable the production of more fertile and resistant, towards biotic and abiotic stress, plants and ensures application of environmentally friendly fertilizers and the use of biopesticides, it is mainly focused on the development of agriculture. On the other hand, some of the uses of green biotechnology involve microorganisms to clean and reduce waste. Red biotechnology is the use of biotechnology in the medical and pharmaceutical industries, and health preservation. This branch involves the production of vaccines and antibiotics, regenerative therapies, creation of artificial organs and new diagnostics of diseases. As well as the development of hormones, stem cells, antibodies, siRNA and diagnostic tests. White biotechnology, also known as industrial biotechnology, is biotechnology
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applied to industrial processes. An example is the designing of an organism to produce a useful chemical. Another example is the using of enzymes as industrial catalysts to either produce valuable chemicals or destroy hazardous/polluting chemicals. White biotechnology tends to consume less in resources than traditional processes used to produce industrial goods. Yellow biotechnology refers to the use of biotechnology in food production (food industry), for example in making wine (winemaking), cheese (cheesemaking), and beer (brewing) by fermentation. It has also been used to refer to biotechnology applied to insects. This includes biotechnology-based approaches for the control of harmful insects, the characterisation and utilisation of active ingredients or genes of insects for research, or application in agriculture and medicine and various other approaches. Gray biotechnology is dedicated to environmental applications, and focused on the maintenance of biodiversity and the remotion of pollutants. Brown biotechnology is related to the management of arid lands and deserts. One application is the creation of enhanced seeds that resist extreme environmental conditions of arid regions, which is related to the innovation, creation of agriculture techniques and management of resources. Violet biotechnology is related to law, ethical and philosophical issues around biotechnology. Microbial biotechnology has been proposed for the rapidly emerging area of biotechnology applications in space and microgravity (space bioeconomy) Dark biotechnology is the color associated with bioterrorism or biological weapons and biowarfare which uses microorganisms, and toxins to cause diseases and death in humans, livestock and crops. === Medicine === In medicine, modern biotechnology has many applications in areas such as pharmaceutical drug discoveries and production, pharmacogenomics, and genetic testing (or genetic screening). In 2021, nearly 40% of the total company value of pharmaceutical biotech companies worldwide were active in Oncology with Neurology and Rare Diseases being the other two big applications. Pharmacogenomics (a
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combination of pharmacology and genomics) is the technology that analyses how genetic makeup affects an individual's response to drugs. Researchers in the field investigate the influence of genetic variation on drug responses in patients by correlating gene expression or single-nucleotide polymorphisms with a drug's efficacy or toxicity. The purpose of pharmacogenomics is to develop rational means to optimize drug therapy, with respect to the patients' genotype, to ensure maximum efficacy with minimal adverse effects. Such approaches promise the advent of "personalized medicine"; in which drugs and drug combinations are optimized for each individual's unique genetic makeup. Biotechnology has contributed to the discovery and manufacturing of traditional small molecule pharmaceutical drugs as well as drugs that are the product of biotechnology β biopharmaceutics. Modern biotechnology can be used to manufacture existing medicines relatively easily and cheaply. The first genetically engineered products were medicines designed to treat human diseases. To cite one example, in 1978 Genentech developed synthetic humanized insulin by joining its gene with a plasmid vector inserted into the bacterium Escherichia coli. Insulin, widely used for the treatment of diabetes, was previously extracted from the pancreas of abattoir animals (cattle or pigs). The genetically engineered bacteria are able to produce large quantities of synthetic human insulin at relatively low cost. Biotechnology has also enabled emerging therapeutics like gene therapy. The application of biotechnology to basic science (for example through the Human Genome Project) has also dramatically improved our understanding of biology and as our scientific knowledge of normal and disease biology has increased, our ability to develop new medicines to treat previously untreatable diseases has increased as well. Genetic testing allows the genetic diagnosis of vulnerabilities to inherited diseases, and can also be used to determine a child's parentage (genetic mother and father) or in general a person's ancestry. In
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addition to studying chromosomes to the level of individual genes, genetic testing in a broader sense includes biochemical tests for the possible presence of genetic diseases, or mutant forms of genes associated with increased risk of developing genetic disorders. Genetic testing identifies changes in chromosomes, genes, or proteins. Most of the time, testing is used to find changes that are associated with inherited disorders. The results of a genetic test can confirm or rule out a suspected genetic condition or help determine a person's chance of developing or passing on a genetic disorder. As of 2011 several hundred genetic tests were in use. Since genetic testing may open up ethical or psychological problems, genetic testing is often accompanied by genetic counseling. === Agriculture === Genetically modified crops ("GM crops", or "biotech crops") are plants used in agriculture, the DNA of which has been modified with genetic engineering techniques. In most cases, the main aim is to introduce a new trait that does not occur naturally in the species. Biotechnology firms can contribute to future food security by improving the nutrition and viability of urban agriculture. Furthermore, the protection of intellectual property rights encourages private sector investment in agrobiotechnology. Examples in food crops include resistance to certain pests, diseases, stressful environmental conditions, resistance to chemical treatments (e.g. resistance to a herbicide), reduction of spoilage, or improving the nutrient profile of the crop. Examples in non-food crops include production of pharmaceutical agents, biofuels, and other industrially useful goods, as well as for bioremediation. Farmers have widely adopted GM technology. Between 1996 and 2011, the total surface area of land cultivated with GM crops had increased by a factor of 94, from 17,000 to 1,600,000 square kilometers (4,200,000 to 395,400,000 acres). 10% of the world's crop lands were planted with GM crops in
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2010. As of 2011, 11 different transgenic crops were grown commercially on 395 million acres (160 million hectares) in 29 countries such as the US, Brazil, Argentina, India, Canada, China, Paraguay, Pakistan, South Africa, Uruguay, Bolivia, Australia, Philippines, Myanmar, Burkina Faso, Mexico and Spain. Genetically modified foods are foods produced from organisms that have had specific changes introduced into their DNA with the methods of genetic engineering. These techniques have allowed for the introduction of new crop traits as well as a far greater control over a food's genetic structure than previously afforded by methods such as selective breeding and mutation breeding. Commercial sale of genetically modified foods began in 1994, when Calgene first marketed its Flavr Savr delayed ripening tomato. To date most genetic modification of foods have primarily focused on cash crops in high demand by farmers such as soybean, corn, canola, and cotton seed oil. These have been engineered for resistance to pathogens and herbicides and better nutrient profiles. GM livestock have also been experimentally developed; in November 2013 none were available on the market, but in 2015 the FDA approved the first GM salmon for commercial production and consumption. There is a scientific consensus that currently available food derived from GM crops poses no greater risk to human health than conventional food, but that each GM food needs to be tested on a case-by-case basis before introduction. Nonetheless, members of the public are much less likely than scientists to perceive GM foods as safe. The legal and regulatory status of GM foods varies by country, with some nations banning or restricting them, and others permitting them with widely differing degrees of regulation. GM crops also provide a number of ecological benefits, if not used in excess. Insect-resistant crops have proven to lower pesticide usage, therefore reducing
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the environmental impact of pesticides as a whole. However, opponents have objected to GM crops per se on several grounds, including environmental concerns, whether food produced from GM crops is safe, whether GM crops are needed to address the world's food needs, and economic concerns raised by the fact these organisms are subject to intellectual property law. Biotechnology has several applications in the realm of food security. Crops like Golden rice are engineered to have higher nutritional content, and there is potential for food products with longer shelf lives. Though not a form of agricultural biotechnology, vaccines can help prevent diseases found in animal agriculture. Additionally, agricultural biotechnology can expedite breeding processes in order to yield faster results and provide greater quantities of food. Transgenic biofortification in cereals has been considered as a promising method to combat malnutrition in India and other countries. === Industrial === Industrial biotechnology (known mainly in Europe as white biotechnology) is the application of biotechnology for industrial purposes, including industrial fermentation. It includes the practice of using cells such as microorganisms, or components of cells like enzymes, to generate industrially useful products in sectors such as chemicals, food and feed, detergents, paper and pulp, textiles and biofuels. In the current decades, significant progress has been done in creating genetically modified organisms (GMOs) that enhance the diversity of applications and economical viability of industrial biotechnology. By using renewable raw materials to produce a variety of chemicals and fuels, industrial biotechnology is actively advancing towards lowering greenhouse gas emissions and moving away from a petrochemical-based economy. Synthetic biology is considered one of the essential cornerstones in industrial biotechnology due to its financial and sustainable contribution to the manufacturing sector. Jointly biotechnology and synthetic biology play a crucial role in generating cost-effective products with nature-friendly features by using
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bio-based production instead of fossil-based. Synthetic biology can be used to engineer model microorganisms, such as Escherichia coli, by genome editing tools to enhance their ability to produce bio-based products, such as bioproduction of medicines and biofuels. For instance, E. coli and Saccharomyces cerevisiae in a consortium could be used as industrial microbes to produce precursors of the chemotherapeutic agent paclitaxel by applying the metabolic engineering in a co-culture approach to exploit the benefits from the two microbes. Another example of synthetic biology applications in industrial biotechnology is the re-engineering of the metabolic pathways of E. coli by CRISPR and CRISPRi systems toward the production of a chemical known as 1,4-butanediol, which is used in fiber manufacturing. In order to produce 1,4-butanediol, the authors alter the metabolic regulation of the Escherichia coli by CRISPR to induce point mutation in the gltA gene, knockout of the sad gene, and knock-in six genes (cat1, sucD, 4hbd, cat2, bld, and bdh). Whereas CRISPRi system used to knockdown the three competing genes (gabD, ybgC, and tesB) that affect the biosynthesis pathway of 1,4-butanediol. Consequently, the yield of 1,4-butanediol significantly increased from 0.9 to 1.8 g/L. === Environmental === Environmental biotechnology includes various disciplines that play an essential role in reducing environmental waste and providing environmentally safe processes, such as biofiltration and biodegradation. The environment can be affected by biotechnologies, both positively and adversely. Vallero and others have argued that the difference between beneficial biotechnology (e.g., bioremediation is to clean up an oil spill or hazard chemical leak) versus the adverse effects stemming from biotechnological enterprises (e.g., flow of genetic material from transgenic organisms into wild strains) can be seen as applications and implications, respectively. Cleaning up environmental wastes is an example of an application of environmental biotechnology; whereas loss of biodiversity or loss of
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{
"page_id": 4502,
"source": null,
"title": "Biotechnology"
}
|
containment of a harmful microbe are examples of environmental implications of biotechnology. Many cities have installed CityTrees, which use biotechnology to filter pollutants from urban atmospheres. === Regulation === The regulation of genetic engineering concerns approaches taken by governments to assess and manage the risks associated with the use of genetic engineering technology, and the development and release of genetically modified organisms (GMO), including genetically modified crops and genetically modified fish. There are differences in the regulation of GMOs between countries, with some of the most marked differences occurring between the US and Europe. Regulation varies in a given country depending on the intended use of the products of the genetic engineering. For example, a crop not intended for food use is generally not reviewed by authorities responsible for food safety. The European Union differentiates between approval for cultivation within the EU and approval for import and processing. While only a few GMOs have been approved for cultivation in the EU a number of GMOs have been approved for import and processing. The cultivation of GMOs has triggered a debate about the coexistence of GM and non-GM crops. Depending on the coexistence regulations, incentives for the cultivation of GM crops differ. === Database for the GMOs used in the EU === The EUginius (European GMO Initiative for a Unified Database System) database is intended to help companies, interested private users and competent authorities to find precise information on the presence, detection and identification of GMOs used in the European Union. The information is provided in English. == Learning == In 1988, after prompting from the United States Congress, the National Institute of General Medical Sciences (National Institutes of Health) (NIGMS) instituted a funding mechanism for biotechnology training. Universities nationwide compete for these funds to establish Biotechnology Training Programs (BTPs). Each
|
{
"page_id": 4502,
"source": null,
"title": "Biotechnology"
}
|
successful application is generally funded for five years then must be competitively renewed. Graduate students in turn compete for acceptance into a BTP; if accepted, then stipend, tuition and health insurance support are provided for two or three years during the course of their PhD thesis work. Nineteen institutions offer NIGMS supported BTPs. Biotechnology training is also offered at the undergraduate level and in community colleges. == References and notes == == External links == What is Biotechnology? β A curated collection of resources about the people, places and technologies that have enabled biotechnology
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{
"page_id": 4502,
"source": null,
"title": "Biotechnology"
}
|
Chromium acetate may refer to: Chromium(II) acetate Chromium(III) acetate
|
{
"page_id": 7541142,
"source": null,
"title": "Chromium acetate"
}
|
The Gamow factor, Sommerfeld factor or GamowβSommerfeld factor, named after physicists George Gamow or after Arnold Sommerfeld, is a probability factor for two nuclear particles' chance of overcoming the Coulomb barrier in order to undergo nuclear reactions, for example in nuclear fusion. By classical physics, there is almost no possibility for protons to fuse by crossing each other's Coulomb barrier at temperatures commonly observed to cause fusion, such as those found in the Sun. In 1927 it was discovered that there is a significant chance for nuclear fusion due to quantum tunnelling. While the probability of overcoming the Coulomb barrier increases rapidly with increasing particle energy, for a given temperature, the probability of a particle having such an energy falls off very fast, as described by the MaxwellβBoltzmann distribution. Gamow found that, taken together, these effects mean that for any given temperature, the particles that fuse are mostly in a temperature-dependent narrow range of energies known as the Gamow window. The maximum of the distribution is called the Gamow peak. == Description == The probability of two nuclear particles overcoming their electrostatic barriers is given by the following factor: P G ( E ) = e β E G / E , {\displaystyle P_{\text{G}}(E)=e^{-{\sqrt {{E_{\text{G}}}/{E}}}},} where E G {\displaystyle E_{\text{G}}} is the Gamow energy E G β‘ 2 ΞΌ c 2 ( Ο Ξ± Z a Z b ) 2 , {\displaystyle E_{\text{G}}\equiv 2\mu c^{2}(\pi \alpha Z_{\text{a}}Z_{\text{b}})^{2},} where ΞΌ = m a m b m a + m b {\displaystyle \mu ={\frac {m_{\text{a}}m_{\text{b}}}{m_{\text{a}}+m_{\text{b}}}}} is the reduced mass of the two particles. The constant Ξ± {\displaystyle \alpha } is the fine-structure constant, c {\displaystyle c} is the speed of light, and Z a {\displaystyle Z_{\text{a}}} and Z b {\displaystyle Z_{\text{b}}} are the respective atomic numbers of each particle. It is sometimes
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"page_id": 14356889,
"source": null,
"title": "Gamow factor"
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|
rewritten using the Sommerfeld parameter Ξ·, such that P G ( E ) = e β 2 Ο Ξ· , {\displaystyle P_{\text{G}}(E)=e^{-2\pi \eta },} where Ξ· is a dimensionless quantity used in nuclear astrophysics in the calculation of reaction rates between two nuclei and it also appears in the definition of the astrophysical S-factor. It is defined as Ξ· = Z a Z b e 2 4 Ο Ο΅ 0 β v = Ξ± Z 1 Z 2 ΞΌ c 2 2 E , {\displaystyle \eta ={\frac {Z_{a}Z_{b}e^{2}}{4\pi \epsilon _{0}\hbar v}}=\alpha Z_{1}Z_{2}{\sqrt {\frac {\mu c^{2}}{2E}}},} where e is the elementary charge, v is the magnitude of the relative incident velocity in the centre-of-mass frame. == Derivation == === 1D problem === The derivation consists in the one-dimensional case of quantum tunnelling using the WKB approximation. Considering a wave function of a particle of mass m, we take area 1 to be where a wave is emitted, area 2 the potential barrier which has height V and width l (at 0 < x < l {\textstyle 0<x<l} ), and area 3 its other side, where the wave is arriving, partly transmitted and partly reflected. For wave numbers k [m-1] and energy E we get: Ξ¨ 1 = A e i ( k x + Ξ± ) e β i E t / β {\displaystyle \Psi _{1}=Ae^{i(kx+\alpha )}e^{-i{Et}/{\hbar }}} Ξ¨ 2 = B 1 e β k β² x + B 2 e k β² x {\displaystyle \Psi _{2}=B_{1}e^{-k'x}+B_{2}e^{k'x}} Ξ¨ 3 = ( C 1 e β i ( k x + Ξ² ) + C 2 e i ( k x + Ξ² β² ) ) β
e β i E t / β {\displaystyle \Psi _{3}=(C_{1}e^{-i(kx+\beta )}+C_{2}e^{i(kx+\beta ')})\cdot e^{-i{Et}/{\hbar }}} where k = 2 m E / β 2 {\displaystyle
|
{
"page_id": 14356889,
"source": null,
"title": "Gamow factor"
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|
k={\sqrt {2mE/\hbar ^{2}}}} and k β² = 2 m ( V β E ) / β 2 , {\textstyle k'={\sqrt {2m(V-E)/\hbar ^{2}}},} both in [1/m]. This is solved for given A and phase Ξ± by taking the boundary conditions at the barrier edges, at x = 0 {\displaystyle x=0} and x = l {\displaystyle x=l} : there Ξ¨ 1 , 3 ( t ) {\textstyle \Psi _{1,3}(t)} and its derivatives must be equal on both sides. For k β² l β« 1 {\displaystyle k'l\gg 1} , this is easily solved by ignoring the time exponential and considering the real part alone (the imaginary part has the same behaviour). We get, up to factors depending on the Ξ² phases which are typically of order 1, and of the order of k / k β² = E / ( V β E ) {\textstyle {k}/{k'}={\sqrt {{E}/{(V-E)}}}} (assumed not very large, since V is greater than E (not marginally)): Ξ¨ 1 = A e i ( k x + Ξ± ) , Ξ¨ 3 = C 1 e β i ( k x + Ξ² ) + C 2 e i ( k x + Ξ² β² ) , {\displaystyle \Psi _{1}=Ae^{i(kx+\alpha )},\Psi _{3}=C_{1}e^{-i(kx+\beta )}+C_{2}e^{i(kx+\beta ')},} Ξ¨ 2 β A e β k β² x + A e k β² x : B 1 , B 2 β A {\displaystyle \Psi _{2}\approx Ae^{-k'x}+Ae^{k'x}:B_{1},B_{2}\approx A} and C 1 , C 2 β 1 2 A k β² k e k β² l . {\displaystyle C_{1},C_{2}\approx {\frac {1}{2}}A{\frac {k'}{k}}e^{k'l}.} Next, the alpha decay can be modelled as a symmetric one-dimensional problem, with a standing wave between two symmetric potential barriers at q 0 < x < q 0 + l {\displaystyle q_{0}<x<q_{0}+l} and β ( q 0 + l ) < x < β q
|
{
"page_id": 14356889,
"source": null,
"title": "Gamow factor"
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0 {\displaystyle -(q_{0}+l)<x<-q_{0}} , and emitting waves at both outer sides of the barriers. Solving this can in principle be done by taking the solution of the first problem, translating it by q 0 {\displaystyle q_{0}} and gluing it to an identical solution reflected around x = 0 {\displaystyle x=0} . Due to the symmetry of the problem, the emitting waves on both sides must have equal amplitudes (A), but their phases (Ξ±) may be different. This gives a single extra parameter; however, gluing the two solutions at x = 0 {\textstyle x=0} requires two boundary conditions (for both the wave function and its derivative), so in general there is no solution. In particular, re-writing Ξ¨ 3 {\textstyle \Psi _{3}} (after translation by q 0 {\textstyle q_{0}} ) as a sum of a cosine and a sine of k x {\displaystyle kx} , each having a different factor that depends on k and Ξ²; the factor of the sine must vanish, so that the solution can be glued symmetrically to its reflection. Since the factor is in general complex (hence its vanishing imposes two constraints, representing the two boundary conditions), this can in general be solved by adding an imaginary part of k, which gives the extra parameter needed. Thus E will have an imaginary part as well. The physical meaning of this is that the standing wave in the middle decays; the waves newly emitted have therefore smaller amplitudes, so that their amplitude decays in time but grows with distance. The decay constant, denoted Ξ» [1/s], is assumed small compared to E / β {\textstyle E/\hbar } . Ξ» can be estimated without solving explicitly, by noting its effect on the probability current conservation law. Since the probability flows from the middle to the sides, we have: β β
|
{
"page_id": 14356889,
"source": null,
"title": "Gamow factor"
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|
t β« β ( q 0 + l ) ( q 0 + l ) Ξ¨ β Ξ¨ d x = 2 β 2 m i ( Ξ¨ 1 β β Ξ¨ 1 β x β Ξ¨ 1 β Ξ¨ 1 β β x ) , {\displaystyle {\frac {\partial }{\partial t}}\int _{-(q_{0}+l)}^{(q_{0}+l)}\Psi ^{*}\Psi \ dx=2{\frac {\hbar }{2mi}}\left(\Psi _{1}^{*}{\frac {\partial \Psi _{1}}{\partial x}}-\Psi _{1}{\frac {\partial \Psi _{1}^{*}}{\partial x}}\right),} note the factor of 2 is due to having two emitted waves. Taking Ξ¨ βΌ e β Ξ» t {\displaystyle \Psi \sim e^{-\lambda t}} , this gives: Ξ» 2 4 ( q 0 + l ) ( A k β² k ) 2 e 2 k β² l β 2 β m A 2 k . {\displaystyle \lambda {\frac {2}{4}}(q_{0}+l)\left(A{\frac {k'}{k}}\right)^{2}e^{2k'l}\approx 2{\frac {\hbar }{m}}A^{2}k.} Since the quadratic dependence on k β² l {\displaystyle k'l} is negligible relative to its exponential dependence, we may write: Ξ» β 4 β k m ( q 0 + l ) k 2 k β² 2 β
e β 2 k β² l . {\displaystyle \lambda \approx 4{\frac {\hbar k}{m(q_{0}+l)}}{\frac {k^{2}}{k'^{2}}}\cdot e^{-2k'l}.} Remembering the imaginary part added to k is much smaller than the real part, we may now neglect it and get: Ξ» β 4 β k m ( q 0 + l ) β
E V β E β
e β 2 2 m ( V β E ) l / β . {\displaystyle \lambda \approx 4{\frac {\hbar k}{m(q_{0}+l)}}\cdot {\frac {E}{V-E}}\cdot e^{-2{\sqrt {2m(V-E)}}l/\hbar }.} Note that β k m = 2 E / m {\textstyle {\frac {\hbar k}{m}}={\sqrt {2E/m}}} is the particle velocity, so the first factor is the classical rate by which the particle trapped between the barriers ( 2 q 0 {\textstyle 2q_{0}} apart) hits them. === 3D problem === Finally, moving to the
|
{
"page_id": 14356889,
"source": null,
"title": "Gamow factor"
}
|
three-dimensional problem, the spherically symmetric SchrΓΆdinger equation reads (expanding the wave function Ο ( r , ΞΈ , Ο ) = Ο ( r ) u ( ΞΈ , Ο ) {\displaystyle \psi (r,\theta ,\phi )=\chi (r)u(\theta ,\phi )} in spherical harmonics and looking at the l-th term): β 2 2 m ( d 2 Ο d r 2 + 2 r d Ο d r ) = ( V ( r ) + β 2 2 m β ( β + 1 ) r 2 β E ) Ο . {\displaystyle {\frac {\hbar ^{2}}{2m}}\left({\frac {d^{2}\chi }{dr^{2}}}+{\frac {2}{r}}{\frac {d\chi }{dr}}\right)=\left(V(r)+{\frac {\hbar ^{2}}{2m}}{\frac {\ell (\ell +1)}{r^{2}}}-E\right)\chi .} Since β > 0 {\displaystyle \ell >0} amounts to enlarging the potential, and therefore substantially reducing the decay rate (given its exponential dependence on V β E {\textstyle {\sqrt {V-E}}} ): we focus on β = 0 {\displaystyle \ell =0} , and get a very similar problem to the previous one with Ο ( r ) = Ξ¨ ( r ) / r {\displaystyle \chi (r)=\Psi (r)/r} , except that now the potential as a function of r is not a step function. In short β 2 2 m ( Ο Β¨ + 2 r Ο Λ ) = ( V ( r ) β E ) Ο . {\textstyle {\frac {\hbar ^{2}}{2m}}\left({\ddot {\chi }}+{\frac {2}{r}}{\dot {\chi }}\right)=\left(V(r)-E\right)\chi .} The main effect of this on the amplitudes is that we must replace the argument in the exponent, taking an integral of 2 2 m ( V β E ) / β {\textstyle 2{\sqrt {2m(V-E)}}/\hbar } over the distance where V ( r ) > E {\displaystyle V(r)>E} rather than multiplying by width l. We take the Coulomb potential: V ( r ) = z ( Z β z ) e 2 4 Ο Ξ΅
|
{
"page_id": 14356889,
"source": null,
"title": "Gamow factor"
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0 r {\displaystyle V(r)={\frac {z(Z-z)e^{2}}{4\pi \varepsilon _{0}r}}} where Ξ΅ 0 {\displaystyle \varepsilon _{0}} is the vacuum electric permittivity, e the electron charge, z = 2 is the charge number of the alpha particle and Z the charge number of the nucleus (Zβz after emitting the particle). The integration limits are then: r 2 = z ( Z β z ) e 2 4 Ο Ξ΅ 0 E , {\displaystyle r_{2}={\frac {z(Z-z)e^{2}}{4\pi \varepsilon _{0}E}},} where we assume the nuclear potential energy is still relatively small, and r 1 {\displaystyle r_{1}} , which is where the nuclear negative potential energy is large enough so that the overall potential is smaller than E. Thus, the argument of the exponent in Ξ» is: 2 2 m E β β« r 1 r 2 V ( r ) E β 1 d r = 2 2 m E β β« r 1 r 2 r 2 r β 1 d r . {\displaystyle 2{\frac {\sqrt {2mE}}{\hbar }}\int _{r_{1}}^{r_{2}}{\sqrt {{\frac {V(r)}{E}}-1}}\,dr=2{\frac {\sqrt {2mE}}{\hbar }}\int _{r_{1}}^{r_{2}}{\sqrt {{\frac {r_{2}}{r}}-1}}\,dr.} This can be solved by substituting t = r / r 2 {\textstyle t={\sqrt {r/r_{2}}}} and then t = cos β‘ ( ΞΈ ) {\textstyle t=\cos(\theta )} and solving for ΞΈ, giving: 2 r 2 2 m E β [ cos β 1 β‘ ( x ) β x 1 β x ] = 2 2 m z ( Z β z ) e 2 4 Ο Ξ΅ 0 β E [ cos β 1 β‘ ( x ) β x 1 β x ] {\displaystyle 2r_{2}{\frac {\sqrt {2mE}}{\hbar }}[\cos ^{-1}({\sqrt {x}})-{\sqrt {x}}{\sqrt {1-x}}]=2{\frac {{\sqrt {2m}}z(Z-z)e^{2}}{4\pi \varepsilon _{0}\hbar {\sqrt {E}}}}\left[\cos ^{-1}({\sqrt {x}})-{\sqrt {x}}{\sqrt {1-x}}\right]} where x = r 1 / r 2 {\displaystyle x=r_{1}/r_{2}} . Since x is small, the x-dependent factor is of the order 1. Assuming x
|
{
"page_id": 14356889,
"source": null,
"title": "Gamow factor"
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|
βͺ 1 {\textstyle x\ll 1} , the x-dependent factor can be replaced by arccos β‘ 0 = Ο / 2 , {\textstyle \arccos 0=\pi /2,} giving: Ξ» β e β E G / E {\displaystyle \lambda \approx e^{-{\sqrt {{E_{\mathrm {G} }}/{E}}}}} with E G = Ο 2 m / 2 [ z ( Z β z ) e 2 ] 2 ( 4 Ο Ξ΅ 0 β ) 2 . {\displaystyle E_{\mathrm {G} }={\frac {\pi ^{2}m/2\left[z(Z-z)e^{2}\right]^{2}}{(4\pi \varepsilon _{0}\hbar )^{2}}}.} Which is the same as the formula given in the beginning of the article with Z a = z {\textstyle Z_{\text{a}}=z} , Z b = Z β z {\textstyle Z_{\text{b}}=Z-z} and the fine-structure constant Ξ± = e 2 4 Ο Ξ΅ 0 β c : E G = m / 2 / ( 4 Ο΅ 0 β ) [ Z a e Z b e ] . {\textstyle \alpha ={\frac {e^{2}}{4\pi \varepsilon _{0}\hbar c}}:{\sqrt {E_{\rm {G}}}}={\sqrt {m/2}}/(4\epsilon _{0}\hbar )[Z_{a}eZ_{b}e].} For a radium alpha decay, Z = 88, z = 2 and m β 4mp, EG is approximately 50 GeV. Gamow calculated the slope of log β‘ ( Ξ» ) {\textstyle \log(\lambda )} with respect to E at an energy of 5 MeV to be ~ 1014 Jβ1, compared to the experimental value of 0.7Γ1014 Jβ1. == Gamow peak == For an ideal gas, the MaxwellβBoltzmann distribution is proportional to P MB ( E ) β e β m β¨ v 2 β© / 2 k B T = e β E / k B T {\displaystyle P_{\text{MB}}(E)\propto e^{-m\langle v^{2}\rangle /2k_{\rm {B}}T}=e^{-E/k_{\rm {B}}T}} where β¨ v 2 β© {\displaystyle \langle v^{2}\rangle } is the average squared speed of all particles, k B {\textstyle k_{\rm {B}}} is the Boltzmann constant and T is absolute temperature. The fusion probability is the product of the
|
{
"page_id": 14356889,
"source": null,
"title": "Gamow factor"
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MaxwellβBoltzmann distribution factor and the Gamow factor P fusion ( E ) = P MB ( E ) β
P G ( E ) = exp β‘ ( β E k B T β E G E ) {\displaystyle P_{\text{fusion}}(E)=P_{\text{MB}}(E)\cdot P_{\text{G}}(E)=\exp \left(-{\frac {E}{k_{\mathrm {B} }T}}-{\sqrt {\frac {E_{\rm {G}}}{E}}}\right)} The maximum of the fusion probability is given by β P fusion / β E = 0 , {\textstyle \partial P_{\text{fusion}}/\partial E=0,} which yields E m a x = [ E G ( k B T 2 ) 2 ] 1 / 3 . {\displaystyle E_{\rm {max}}=\left[E_{\rm {G}}\left({\frac {k_{\rm {B}}T}{2}}\right)^{2}\right]^{1/3}.} This quantity is known as the Gamow peak. Expanding P fusion {\displaystyle P_{\text{fusion}}} around E m a x {\displaystyle E_{\rm {max}}} gives: P fusion ( E ) β P fusion ( E max ) β
[ 1 + ( E β E m a x 2 Ξ ) 2 + β― ] , {\displaystyle P_{\text{fusion}}(E)\approx P_{\text{fusion}}(E_{\text{max}})\cdot \left[1+\left({\frac {E-E_{\rm {max}}}{2\Delta }}\right)^{2}+\cdots \right],} where (in joule) Ξ ( T ) = 4 E m a x k B T 3 = 2 5 / 3 3 [ E G ( k B T ) 5 ] 1 / 6 {\displaystyle \Delta (T)=4{\sqrt {\frac {E_{\rm {max}}k_{\rm {B}}T}{3}}}={\frac {2^{5/3}}{\sqrt {3}}}[E_{\rm {G}}^{}(k_{\rm {B}}T)^{5}]^{1/6}} is the Gamow window. == History == In 1927, Ernest Rutherford published an article in Philosophical Magazine on a problem related to Hans Geiger's 1921 experiment of scattering alpha particles from uranium. Previous experiments with thorium C' (now called polonium-262) confirmed that uranium has a Coulomb barrier of 8.57 MeV, however uranium emitted alpha particles of 4.2 MeV. The emitted energy was too low to overcome the barrier. On 29 July 1928, George Gamow, and independently the next day Ronald Wilfred Gurney and Edward Condon submitted their solution based on quantum tunnelling to the
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{
"page_id": 14356889,
"source": null,
"title": "Gamow factor"
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journal Zeitschrift fΓΌr Physik. Their work was based on previous work on tunnelling by J. Robert Oppenheimer, Gregor Wentzel, Lothar Wolfgang Nordheim, and Ralph H. Fowler. Gurney and Condon cited also Friedrich Hund. In 1931, Arnold Sommerfeld introduced a similar factor (a Gaunt factor) for the discussion of bremsstrahlung. Gamow popularized his personal version of the discovery in his 1970's book, My World Line: An Informal Autobiography. == See also == Stellar_nucleosynthesis#Reaction_rate == Notes == == References == == External links == Modeling Alpha Half-life (Georgia State University) hyperphysics.phy-astr.gsu.edu
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"page_id": 14356889,
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In physics, phenomenology is the application of theoretical physics to experimental data by making quantitative predictions based upon known theories. It is related to the philosophical notion of the same name in that these predictions describe anticipated behaviors for the phenomena in reality. Phenomenology stands in contrast with experimentation in the scientific method, in which the goal of the experiment is to test a scientific hypothesis instead of making predictions. Phenomenology is commonly applied to the field of particle physics, where it forms a bridge between the mathematical models of theoretical physics (such as quantum field theories and theories of the structure of space-time) and the results of the high-energy particle experiments. It is sometimes used in other fields such as in condensed matter physics and plasma physics, when there are no existing theories for the observed experimental data. == Applications in particle physics == === Standard Model consequences === Within the well-tested and generally accepted Standard Model, phenomenology is the calculating of detailed predictions for experiments, usually at high precision (e.g., including radiative corrections). Examples include: Next-to-leading order calculations of particle production rates and distributions. Monte Carlo simulation studies of physics processes at colliders. Extraction of parton distribution functions from data. ==== CKM matrix calculations ==== The CKM matrix is useful in these predictions: Application of heavy quark effective field theory to extract CKM matrix elements. Using lattice QCD to extract quark masses and CKM matrix elements from experiment. === Theoretical models === In Physics beyond the Standard Model, phenomenology addresses the experimental consequences of new models: how their new particles could be searched for, how the model parameters could be measured, and how the model could be distinguished from other, competing models. ==== Phenomenological analysis ==== Phenomenological analyses, in which one studies the experimental consequences of adding the
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{
"page_id": 2757018,
"source": null,
"title": "Phenomenology (physics)"
}
|
most general set of beyond-the-Standard-Model effects in a given sector of the Standard Model, usually parameterized in terms of anomalous couplings and higher-dimensional operators. In this case, the term "phenomenological" is being used more in its philosophy of science sense. == See also == Effective theory Phenomenological model Phenomenological quantum gravity == References == == External links == Papers on phenomenology are available on the hep-ph archive of the ArXiv.org e-print archive List of topics on phenomenology from IPPP, the Institute for Particle Physics Phenomenology at University of Durham, UK Collider Phenomenology: Basic knowledge and techniques, lectures by Tao Han Pheno '08 Symposium on particle physics phenomenology, including slides from the talks linked from the symposium program.
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{
"page_id": 2757018,
"source": null,
"title": "Phenomenology (physics)"
}
|
Cell proliferation is the process by which a cell grows and divides to produce two daughter cells. Cell proliferation leads to an exponential increase in cell number and is therefore a rapid mechanism of tissue growth. Cell proliferation requires both cell growth and cell division to occur at the same time, such that the average size of cells remains constant in the population. Cell division can occur without cell growth, producing many progressively smaller cells (as in cleavage of the zygote), while cell growth can occur without cell division to produce a single larger cell (as in growth of neurons). Thus, cell proliferation is not synonymous with either cell growth or cell division, despite these terms sometimes being used interchangeably. Stem cells undergo cell proliferation to produce proliferating "transit amplifying" daughter cells that later differentiate to construct tissues during normal development and tissue growth, during tissue regeneration after damage, or in cancer. The total number of cells in a population is determined by the rate of cell proliferation minus the rate of cell death. Cell size depends on both cell growth and cell division, with a disproportionate increase in the rate of cell growth leading to production of larger cells and a disproportionate increase in the rate of cell division leading to production of many smaller cells. Cell proliferation typically involves balanced cell growth and cell division rates that maintain a roughly constant cell size in the exponentially proliferating population of cells. Cell proliferation occurs by combining cell growth with regular "G1-S-G2-M" cell cycles to produce many diploid cell progeny. In single-celled organisms, cell proliferation is largely responsive to the availability of nutrients in the environment (or laboratory growth medium). In multicellular organisms, the process of cell proliferation is tightly controlled by gene regulatory networks encoded in the genome and
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{
"page_id": 594336,
"source": null,
"title": "Cell proliferation"
}
|
executed mainly by transcription factors including those regulated by signal transduction pathways elicited by growth factors during cellβcell communication in development. Recently it has been also demonstrated that cellular bicarbonate metabolism, which is responsible for cell proliferation, can be regulated by mTORC1 signaling. In addition, intake of nutrients in animals can induce circulating hormones of the Insulin/IGF-1 family, which are also considered growth factors, and that function to promote cell proliferation in cells throughout the body that are capable of doing so. Uncontrolled cell proliferation, leading to an increased proliferation rate, or a failure of cells to arrest their proliferation at the normal time, is a cause of cancer. == References ==
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{
"page_id": 594336,
"source": null,
"title": "Cell proliferation"
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Menstruation is the shedding of the uterine lining (endometrium). It occurs on a regular basis in uninseminated sexually reproductive-age females of certain mammal species. Although there is some disagreement in definitions between sources, menstruation is generally considered to be limited to primates. It is common in simians (Old World monkeys, New World monkeys, and apes), but completely lacking in strepsirrhine primates and possibly weakly present in tarsiers. Beyond primates, it is known only in bats, the elephant shrew, and the spiny mouse species Acomys cahirinus. Overt menstruation (where there is bleeding from the uterus through the vagina) is found primarily in humans and close relatives such as chimpanzees. Females of other species of placental mammals undergo estrous cycles, in which the endometrium is completely reabsorbed by the animal (covert menstruation) at the end of its reproductive cycle. Many zoologists regard this as different from a "true" menstrual cycle. Female domestic animals used for breedingβfor example dogs, pigs, cattle, or horsesβare monitored for physical signs of an estrous cycle period, which indicates that the animal is ready for insemination. == Estrus and menstruation == Females of most mammal species advertise fertility to males with visual behavioral cues, pheromones, or both. This period of advertised fertility is known as oestrus, "estrus" or heat. In species that experience estrus, females are generally only receptive to copulation while they are in heat (dolphins are an exception). In the estrous cycles of most placentals, if no fertilization takes place, the uterus reabsorbs the endometrium. This breakdown of the endometrium without vaginal discharge is sometimes called covert menstruation. Overt menstruation (where there is blood flow from the vagina) occurs primarily in humans and close evolutionary relatives such as chimpanzees. Some species, such as domestic dogs, experience small amounts of vaginal bleeding while approaching heat; this discharge
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{
"page_id": 33100194,
"source": null,
"title": "Menstruation (mammal)"
}
|
has a different physiologic cause than menstruation. === Concealed ovulation === A few mammals do not experience obvious, visible signs of fertility (concealed ovulation). In humans, studies show that both males and females can detect the fertility of females through hormonal signaling and alterations in scent (fertility awareness), but some research suggests that behavioral clues may be needed to consciously assess fertility. Orangutans also lack visible signs of impending ovulation. Also, it has been said that the extended estrus period of the bonobo (reproductive-age females are in heat for 75% of their menstrual cycle) has a similar effect to the lack of a "heat" in human females. === Evolution === Most female mammals have an estrous cycle, yet only ten primate species, four bat species, the elephant shrew, and one known species of spiny mouse have a menstrual cycle. As these groups are not closely related, it is likely that four distinct evolutionary events have caused menstruation to arise. There are varying views on evolution of overt menstruation in humans and related species, and the evolutionary advantages in losing blood associated with dismantling the uterine lining rather than absorbing it, as most mammals do. The reason is likely related to differences in the ovulation process. Most female placentals have a uterine lining that builds up when the animal begins ovulation, and later further increases in thickness and blood flow after a fertilized egg has successfully implanted. This final process of thickening is known as decidualization, and is usually triggered by hormones released by the embryo. In humans, decidualization happens spontaneously at the beginning of each menstrual cycle, triggered by hormonal signals from the ovaries. For this reason, the human uterine lining becomes fully thickened during each cycle as a defense to trophoblast penetration of the endometrial wall, regardless of whether
|
{
"page_id": 33100194,
"source": null,
"title": "Menstruation (mammal)"
}
|
an egg becomes fertilized or successfully implants in the uterus. This produces more unneeded material per cycle than in non-menstruating mammals, which may explain why the extra material is not simply reabsorbed as done by those species. In essence, menstruating animals treat every cycle as a possible pregnancy by thickening the protective layer around the endometrial wall, while non-menstruating placental mammals do not begin the pregnancy process until a fertilized egg has implanted in the uterine wall. For this reason, it is speculated that menstruation is a side effect of spontaneous decidualization, which evolved in some placental mammals due to its advantages over non-spontaneous decidualization. Spontaneous decidualization allows for more maternal control in the maternal-fetal conflict by increasing selectivity over the implanted embryo. This may be necessary in humans and other primates, due to the abnormally large number of genetic disorders in these species. Since most aneuploidy events result in stillbirth or miscarriage, there is an evolutionary advantage to ending the pregnancy early, rather than nurturing a fetus that will later miscarry. There is evidence to show that some abnormalities in the developing embryo can be detected by endometrial stromal cells in the uterus, but only upon differentiation into decidual cells. This triggers epigenetic changes that prevent formation of the placenta, which prevents the embryo from implanting and leaves it to be removed in the next menstruation. This failsafe mode is not possible in species where decidualization is controlled by hormonal triggers from the embryo. This is sometimes referred to as the choosy uterus theory, and it is theorized that this positive outweighs the negative impacts of menstruation in species with high aneuploidy rates and hence a high number of 'doomed' embryos. == Animal estrous cycles == The female will ovulate spontaneously and be receptive to the male for breeding
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{
"page_id": 33100194,
"source": null,
"title": "Menstruation (mammal)"
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(express estrus) at regular biologically defined intervals. The female is receptive to males only while experiencing estrus. For breeding livestock, there are a number of advantages to be gained by finding methods to induce ovulation on a planned schedule, and thus synchronize the estrus cycle between many female animals. If animals can be bred on the same schedule, it increases convenience for the livestock owner, since the young animals will be at the same stage of development. Also, if artificial insemination (AI) is used for breeding, the AI technician's time can be used more efficiently, by breeding several females at the same time. In order to induce estrus, a variety of techniques have been tried in recent years, involving both more natural, and more hormonal based methods. Different ways of injecting or feeding hormones to livestock are costly, and have variable success rates. Average length (days) of estrus and estrous cycles: == See also == Estrous cycle Breeding pair Reproduction Animal husbandry == References == == External links == Rasby, Rick; Vinton, Rosemary. "Estrous Cycle Learning Module". Mottershead, Jos. "The Mare's Estrous Cycle". May, Jerry; Bates, Ron. "Managing the Sow and Gilt Estrous Cycle".
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{
"page_id": 33100194,
"source": null,
"title": "Menstruation (mammal)"
}
|
Mechanistic models for niche apportionment are biological models used to explain relative species abundance distributions. These niche apportionment models describe how species break up resource pool in multi-dimensional space, determining the distribution of abundances of individuals among species. The relative abundances of species are usually expressed as a Whittaker plot, or rank abundance plot, where species are ranked by number of individuals on the x-axis, plotted against the log relative abundance of each species on the y-axis. The relative abundance can be measured as the relative number of individuals within species or the relative biomass of individuals within species. == History == Niche apportionment models were developed because ecologists sought biological explanations for relative species abundance distributions. MacArthur (1957, 1961), was one of the earliest to express dissatisfaction with purely statistical models, presenting instead 3 mechanistic niche apportionment models. MacArthur believed that ecological niches within a resource pool could be broken up like a stick, with each piece of the stick representing niches occupied in the community. With contributions from Sugihara (1980), Tokeshi (1990, 1993, 1996) expanded upon the broken stick model, when he generated roughly 7 mechanistic niche apportionment models. These mechanistic models provide a useful starting point for describing the species composition of communities. == Description == A niche apportionment model can be used in situations where one resource pool is either sequentially or simultaneously broken up into smaller niches by colonizing species or by speciation (clarification on resource use: species within a guild use same resources, while species within a community may not). These models describe how species that draw from the same resource pool (e.g. a guild (ecology)) partition their niche. The resource pool is broken either sequentially or simultaneously, and the two components of the process of fragmentation of the niche include which fragment is
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chosen and the size of the resulting fragment (Figure 2). Niche apportionment models have been used in the primary literature to explain, and describe changes in the relative abundance distributions of a diverse array of taxa including, freshwater insects, fish, bryophytes beetles, hymenopteran parasites, plankton assemblages and salt marsh grass. == Assumptions == The mechanistic models that describe these plots work under the assumption that rank abundance plots are based on a rigorous estimate of the abundances of individuals within species and that these measures represent the actual species abundance distribution. Furthermore, whether using the number of individuals as the abundance measure or the biomass of individuals, these models assume that this quantity is directly proportional to the size of the niche occupied by an organism. One suggestion is that abundance measured as the numbers of individuals, may exhibit lower variances than those using biomass. Thus, some studies using abundance as a proxy for niche allocation may overestimate the evenness of a community. This happens because there is not a clear distinction of the relationship between body size, abundance (ecology), and resource use. Often studies fail to incorporate size structure or biomass estimates into measures of actual abundance, and these measure can create a higher variance around the niche apportionment models than abundance measured strictly as the number of individuals. == Tokeshi's mechanistic models of niche apportionment == Seven mechanistic models that describe niche apportionment are described below. The models are presented in the order of increasing evenness, from least even, the Dominance Pre-emption model to the most even the Dominance Decay and MacArthur Fraction models. === Dominance preemption === This model describes a situation where after initial colonization (or speciation) each new species pre-empts more than 50% of the smallest remaining niche. In a Dominance preemption model of niche
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{
"page_id": 22417827,
"source": null,
"title": "Niche apportionment models"
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apportionment the species colonize random portion between 50 and 100% of the smallest remaining niche, making this model stochastic in nature. A closely related model, the Geometric Series, is a deterministic version of the Dominance pre-emption model, wherein the percentage of remaining niche space that the new species occupies (k) is always the same. In fact, the dominance pre-emption and geometric series models are conceptually similar and will produce the same relative abundance distribution when the proportion of the smaller niche filled is always 0.75. The dominance pre-emption model is the best fit to the relative abundance distributions of some stream fish communities in Texas, including some taxonomic groupings, and specific functional groupings. The Geometric (k=0.75) P i = k ( 1 β k ) i β 1 {\displaystyle Pi=k(1-k)^{i-1}} === Random assortment === In the random assortment model the resource pool is divided at random among simultaneously or sequentially colonizing species. This pattern could arise because the abundance measure does not scale with the amount of niche occupied by a species or because temporal-variation in species abundance or niche breadth causes discontinuity in niche apportionment over time and thus species appear to have no relationship between extent of occupancy and their niche. Tokeshi (1993) explained that this model, in many ways, is similar to Caswell's neutral theory of biodiversity, mainly because species appear to act independently of each other. === Random fraction === The random fraction model describes a process where niche size is chosen at random by sequentially colonizing species. The initial species chooses a random portion of the total niche and subsequent colonizing species also choose a random portion of the total niche and divide it randomly until all species have colonized. Tokeshi (1990) found this model to be compatible with some epiphytic Chiromonid shrimp communities, and
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"page_id": 22417827,
"source": null,
"title": "Niche apportionment models"
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more recently it has been used to explain the relative abundance distributions of phytoplankton communities, salt meadow vegetation, some communities of insects in the order Diptera, some ground beetle communities, functional and taxonomic groupings of stream fish in Texas bio-regions, and ichneumonid parasitoids. A similar model was developed by Sugihara in an attempt to provide a biological explanation for the log normal distribution of Preston (1948). Sugihara's (1980) Fixed Division Model was similar to the random fraction model, but the randomness of the model is drawn from a triangular distribution with a mean of 0.75 rather that a normal distribution with a mean of 0.5 used in the random fraction. Sugihara used a triangular distribution to draw the random variables because the randomness of some natural populations matches a triangular distribution with a mean of 0.75. === Power fraction === This model can explain a relative abundance distribution when the probability of colonization an existing niche in a resource pool is positively related to the size of that niche (measured as abundance, biomass etc.). The probability with which a portion of the niche colonized is dependent on the relative sizes of the established niches, and is scaled by an exponent k. k can take a value between 0 and 1 and if k>0 there is always a slightly higher probability that the larger niche will be colonized. This model is toted as being more biologically realistic because one can imagine many cases where the niche with the larger proportion of resources is more likely to be invaded because that niche has more resource space, and thus more opportunity for acquisition. The random fraction model of niche apportionment is an extreme of the power fraction model where k=0, and the other extreme of the power fraction, when k=1 resembles the MacArthur
|
{
"page_id": 22417827,
"source": null,
"title": "Niche apportionment models"
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|
Fraction model where the probability of colonization is directly proportion to niche size. === MacArthur fraction === This model requires that the initial niche is broken at random and the successive niches are chosen with a probability proportional to their size. In this model the largest niche always has a greater probability of being broken relative to the smaller niches in the resource pool. This model can lead to a more even distribution where larger niches are more likely to be broken facilitating co-existence between species in equivalent sized niches. The basis for the MacArthur Fraction model is the Broken Stick, developed by MacArthur (1957). These models produce similar results, but one of the main conceptual differences is that niches are filled simultaneously in Broken Stick model rather than sequentially as in the MacArthur Fraction. Tokeshi (1993) argues that sequentially invading a resource pool is more biologically realistic than simultaneously breaking the niche space. When the abundance of fish from all bio-regions in Texas were combined the distribution resembled the broken stick model of niche apportionment, suggesting a relatively even distribution of freshwater fish species in Texas. === Dominance decay === This model can be thought of as the inverse to the Dominance pre-emption model. First, the initial resource pool is colonized randomly and the remaining, subsequent colonizers always colonize the largest niche, whether or not it is already colonized. This model generates the most even community relative to the niche apportionment models described above because the largest niche is always broken into two smaller fragments that are more likely to be equivalent to the size of the smaller niche that was not broken. Communities of this βlevelβ of evenness seem to be rare in natural systems. However, one such community includes the relative abundance distribution of filter feeders in
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{
"page_id": 22417827,
"source": null,
"title": "Niche apportionment models"
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one site within the River Danube in Austria. === Composite === A composite model exists when a combination of niche apportionment models are acting in different portions of the resource pool. Fesl (2002). shows how a composite model might appear in a study of freshwater Diptera, in that different niche apportionment models fit different functional groups of the data. Another example by Higgins and Strauss (2008), modeling fish assemblages, found that fish communities from different habitats and with different species compositions conform to different niche apportionment models, thus the entire species assemblage was a combination of models in different regions of the species range. == Fitting mechanistic models of niche apportionment to empirical data == Mechanistic models of niche apportionment are intended to describe communities. Researchers have used these models in many ways to investigate the temporal and geographic trends in species abundance. For many years the fit of niche apportionment models was conducted by eye and graphs of the models were compared with empirical data. More recently statistical tests of the fit of niche apportionment models to empirical data have been developed. The later method (Etienne and Ollf 2005) uses a Bayesian simulation of the models to test their fit to empirical data. The former method, which is still commonly used, simulates the expected relative abundances, from a normal distribution, of each model given the same number of species as the empirical data. Each model is simulated multiple times, and mean and standard deviation can be calculated to assign confidence intervals around each relative abundance distribution. The confidence around each rank can be tested against empirical data for each model to determine model fit. The confidence intervals are calculated as follows. For more information on the simulation of niche apportionment models the website [1], which explains the program Power
|
{
"page_id": 22417827,
"source": null,
"title": "Niche apportionment models"
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Niche. R ( x i ) = ΞΌ i Β± r Ο i n {\displaystyle R(x_{i})=\mu _{i}\pm {\frac {r\sigma _{i}}{\sqrt {n}}}} r=confidence limit of simulated data Ο=standard deviation of simulated data n=number of replicates of empirical sample == References ==
|
{
"page_id": 22417827,
"source": null,
"title": "Niche apportionment models"
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Cell Communication and Signaling is a peer-reviewed and open access scientific journal that publishes original research, reviews and commentaries with a focus on cellular signaling research. It was established in 2003 and is currently published by the London-based publisher BioMed Central. Raymond Birge (Center for Cell Signaling, Rutgers Biomedical and Health Sciences, U Rutgers, The State University of New Jersey) has been the editor-in-chief of Cell Communication and Signaling since January 2017. In June 2012, Cell Communication and Signaling received its first impact factor. == References ==
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{
"page_id": 36639138,
"source": null,
"title": "Cell Communication and Signaling"
}
|
Cressdnaviricota is a phylum of viruses with small, circular single-stranded DNA genomes and encoding rolling circle replication-initiation proteins with the N-terminal HUH endonuclease and C-terminal superfamily 3 helicase domains. While the replication-associated proteins are homologous among viruses within the phylum, the capsid proteins are very diverse and have presumably been acquired from RNA viruses on multiple independent occasions. Nevertheless, all cressdnaviruses for which structural information is available appear to contain the jelly-roll fold. == Taxonomy == The following classes are recognized: Arfiviricetes Repensiviricetes == References == == External links == Media related to Cressdnaviricota at Wikimedia Commons
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{
"page_id": 63771045,
"source": null,
"title": "Cressdnaviricota"
}
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Chemistry education (or chemical education) is the study of teaching and learning chemistry. It is one subset of STEM education or discipline-based education research (DBER). Topics in chemistry education include understanding how students learn chemistry and determining the most efficient methods to teach chemistry. There is a constant need to improve chemistry curricula and learning outcomes based on findings of chemistry education research (CER). Chemistry education can be improved by changing teaching methods and providing appropriate training to chemistry instructors, within many modes, including classroom lectures, demonstrations, and laboratory activities. == Importance == Chemistry education is important because the field of chemistry is fundamental to our world. The universe is subject to the laws of chemistry, while human beings depend on the orderly progress of chemical reactions within their bodies. Described as the central science, chemistry connects physical sciences with the life sciences and applied sciences. Chemistry has applications in food, medicine, industry, the environment, and other areas. Learning chemistry allows students to learn about the scientific method and gain skills in critical thinking, deductive reasoning, problem-solving, and communication. Teaching chemistry to students at a young age can increase student interest in STEM careers. Chemistry also provides students with many transferable skills that can be applied to any career. == Teaching strategies == The most common method of teaching chemistry is lecture with a laboratory component. Laboratory courses became a central part of the chemistry curriculum towards the end of the 19th century. The German scientist Justus von Liebig plays a major role in shifting the model of lecture with demonstrations to one that includes a laboratory component. Liebig was one of the first chemists to conduct a laboratory and his methodology became widespread in the United States due to the efforts of Eben Horsford and Charles W. Eliot. After
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"page_id": 4133285,
"source": null,
"title": "Chemistry education"
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working in Liebig's laboratory, Horsford returned to the United States and helped establish the Lawrence Scientific School at Harvard University. The school was modeled after Liebig's methodology and established the first chemistry laboratory course. Two years later, Charles W. Eliot started to volunteer at the laboratory. Eliot's interests in the laboratory grew, and he eventually took charge of it. Eliot was later elected as Harvard's president in 1869. Eliot also served other powerful roles in education, which allowed him to influence the widespread adoption of laboratory methods. Today, the American Chemical Society on Professional Training requires students to gain 400 hours of laboratory experience, outside of introductory chemistry, to get a bachelor's degree. Similarly, the Royal Society of Chemistry requires students to gain 300 hours of laboratory experience to get a bachelor's degree. However, since the twenty-first century, the role of laboratory courses in the chemistry curriculum has been questioned in major journals. The main argument against laboratory courses is that there is little evidence for their impact on student learning. Researchers are asking questions such as "why do we have laboratory work in the curriculum? What is distinctive about laboratory work that cannot be met elsewhere in the curriculum?" Researchers are asking for evidence that the investment of space, time and resources in chemistry laboratories provides value to student learning. == Theories of education == There are several different philosophical perspectives that describe how the work in chemistry education is carried out. === Practitioner's Perspective === The first is what one might call a practitioner's perspective, wherein the individuals who are responsible for teaching chemistry (teachers, instructors, professors) are the ones who ultimately define chemistry education by their actions. === Perspective of chemical educators === A second perspective is defined by a self-identified group of chemical educators, faculty members
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{
"page_id": 4133285,
"source": null,
"title": "Chemistry education"
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and instructors who, as opposed to declaring their primary interest in a typical area of laboratory research (organic, inorganic, biochemistry, etc.), take on an interest in contributing suggestions, essays, observations, and other descriptive reports of practice into the public domain, through journal publications, books, and presentations. Dr. Robert L. Lichter, then-Executive Director of the Camille and Henry Dreyfus Foundation, speaking in a plenary session at the 16th Biennial Conference on Chemical Education (recent BCCE meetings: [1],[2]), posed the question of why do terms like 'chemical educator' even exist in higher education, when there is a perfectly respectable term for this activity, namely, 'chemistry professor.' One criticism of this view is that few professors bring any formal preparation in or background about education to their jobs, and so lack any professional perspective on the teaching and learning enterprise, particularly discoveries made about effective teaching and how students learn. === Chemistry education research (CER) === A third perspective is chemistry education research (CER). CER is a type of discipline-based education research (DBER) focusing on the teaching and learning of chemistry. An overarching goal for chemistry education researchers is to help students develop 'expert-like' (coherent and useful) knowledge of chemistry. Thus, the field of CER involves investigating: how students construct their understanding of chemical phenomena and develop practical skills relevant to the discipline; how CER findings can inform curriculum design, e.g. by suggesting certain learning objectives and instructional approaches; and developing instruments to measure the above. Following the example of physics education research (PER), CER tends to take the theories and methods developed in pre-college science education research, which generally takes place in Schools of Education, and applies them to understanding comparable problems in post-secondary settings (in addition to pre-college settings). Like science education researchers, CER practitioners tend to study the teaching practices
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{
"page_id": 4133285,
"source": null,
"title": "Chemistry education"
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of others as opposed to focusing on their own classroom practices. Chemistry education research is typically carried out in situ using human subjects from secondary and post-secondary schools. Chemistry education research utilizes both quantitative and qualitative data collection methods. Quantitative methods typically involve collecting data that can then be analyzed using various statistical methods. Qualitative methods include interviews, observations, document analysis, journaling, and other methods common to social science research. === The Scholarship of Teaching and Learning (SoTL) === There is also an emergent perspective called The Scholarship of Teaching and Learning (SoTL). Although there is debate on how to best define SoTL, one of the primary practices is for mainstream faculty members (organic, inorganic, biochemistry, etc.) to develop a more informed view of their practices, how to carry out research and reflection on their own teaching, and about what constitutes deep understanding in student learning. === Systems thinking approach === In 2017, the Systems Thinking Into Chemistry Education (STICE) project proposed a systems thinking approach for (post)-secondary education in general chemistry education. Chemistry education has largely relied on a reductionist approach, which involves studying a complex topic as the sum of its parts. A reductionist approach is beneficial in increasing our knowledge of the natural world, however, it is insufficient in tackling global issuesβsustainability, climate change, pollution, poverty, etc. Due to the limitations of a reductionist approach, researchers are suggesting a complementary systems thinking approach in chemistry education. A systems thinking approach involves learning concepts with a holistic perspective, allowing chemistry students to think critically about how chemistry relates to larger, societal issues. Researchers believe that a reductionist approach, complemented by a systems thinking approach, can produce global-minded chemists. == Academic journals == Several journals publish papers related to chemistry education. Some journals focus on particular education levels (schools
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"page_id": 4133285,
"source": null,
"title": "Chemistry education"
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|
vs. universities) while others cover all education levels. Journal articles range from reports on classroom and laboratory practices to educational research. Australian Journal of Education in Chemistry: Published by the Royal Australian Chemical Institute. Covers both school and university education. Chemical Education Journal (CEJ): Covers all areas of chemical education. Chemistry Education Research and Practice (CERP): Published by the Royal Society of Chemistry (RSC). Publishes theoretical perspectives, literature reviews, and empirical papers, including systematic evaluations of innovative practice. Education in Chemistry (EiC): Published by the Royal Society of Chemistry. Covers all areas of chemical education. (EiC is the RSC's educational magazine, whereas CERP is a peer-reviewed research journal). Foundations of Chemistry (FOCH): Published by Springer. Covers philosophical and historical aspects of chemical education. Journal of Chemical Education: Published by the Chemical Education Division of the American Chemical Society. Covers both school and university education. The Chemical Educator: Published by Springer-Verlag from 1996 to 2002. Covers all areas of chemical education. List of scientific journals in chemistry Research in chemistry education is also published in journals in the wider science education field. == Degrees offered in chemistry == The U.S. offers chemistry education degrees at the undergraduate and graduate levels. The following degrees are offered: Bachelor of Science in Chemistry Education Master of Science in Chemistry Education PhD in Chemistry Education Additionally, colleges and universities offer chemistry degrees with a specialization in chemistry education. Some examples are: Bachelor of Science in Chemistry with Specialization in Chemical Education - University of Virginia Masters of Art in Chemistry with an Emphasis in Chemical Education - University of California Santa Barbara A compendium of graduate programs in chemistry that award M.S. and Ph.D. degrees for research on teaching and learning of chemistry can be found at https://sites.google.com/miamioh.edu/bretzsl/cer-resources/cer-graduate-programs Undergraduate students who are interested in chemistry
|
{
"page_id": 4133285,
"source": null,
"title": "Chemistry education"
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|
can major in the following areas: Chemistry Chemical engineering Biochemistry Environmental Chemistry Analytical chemistry Forensic Chemistry == See also == Advancing Chemistry by Enhancing Learning in the Laboratory Constructivism in science education == References == == External links == Media related to Chemistry education at Wikimedia Commons
|
{
"page_id": 4133285,
"source": null,
"title": "Chemistry education"
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Parental (paternal and maternal) haplarithms are the outputs of haplarithmisis process. For instance, paternal haplarithm represents chromosome specific profile illuminating paternal haplotype of that chromosome (including homologous recombination between the two paternal homologous chromosomes) and the amount of those haplotypes. Importantly, the haplarithm signatures allow tracing back the genomic aberration to meiosis and/or mitosis. == References ==
|
{
"page_id": 51646890,
"source": null,
"title": "Haplarithm"
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In biology, a substrate is the surface on which an organism (such as a plant, fungus, or animal) lives. A substrate can include biotic or abiotic materials and animals. For example, encrusting algae that lives on a rock (its substrate) can be itself a substrate for an animal that lives on top of the algae. Inert substrates are used as growing support materials in the hydroponic cultivation of plants. In biology substrates are often activated by the nanoscopic process of substrate presentation. == In agriculture and horticulture == Cellulose substrate Expanded clay aggregate (LECA) Rock wool Potting soil Soil == In animal biotechnology == === Requirements for animal cell and tissue culture === Requirements for animal cell and tissue culture are the same as described for plant cell, tissue and organ culture (In Vitro Culture Techniques: The Biotechnological Principles). Desirable requirements are (i) air conditioning of a room, (ii) hot room with temperature recorder, (iii) microscope room for carrying out microscopic work where different types of microscopes should be installed, (iv) dark room, (v) service room, (vi) sterilization room for sterilization of glassware and culture media, and (vii) preparation room for media preparation, etc. In addition the storage areas should be such where following should be kept properly : (i) liquids-ambient (4β20 Β°C), (ii) glassware-shelving, (iii) plastics-shelving, (iv) small items-drawers, (v) specialized equipments-cupboard, slow turnover, (vi) chemicals-sidled containers. === For cell growth === There are many types of vertebrate cells that require support for their growth in vitro otherwise they will not grow properly. Such cells are called anchorage-dependent cells. Therefore, many substrates which may be adhesive (e.g. plastic, glass, palladium, metallic surfaces, etc.) or non-adhesive (e.g. agar, agarose, etc.) types may be used as discussed below: Plastic as a substrate. Disposable plastics are cheaper substrate as they are commonly
|
{
"page_id": 8327598,
"source": null,
"title": "Substrate (biology)"
}
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made up of polystyrene. After use they should be disposed of properly. Before use they are treated with gamma radiation or electric arc simply to develop charges on the surface of substrate. After cell growth its rate of proliferation should be measured. In addition, the other plastic materials used as substrate are teflon or polytetrafluoroethylene (PTFE), thermamox (TPX), polyvinylchloride (PVC), polycarbonate, etc. Monolayer of cell must be grown. Moreover, plastic beads of polystyrene, sephadex and polyacrylamide are also available for cell growth in suspension culture. Glass as a substrate. Glass is an important substrate used in laboratory in several forms such as test tubes, slides, coverslips, pipettes, flasks, rods, bottles, Petri dishes, several apparatus, etc. These are sterilized by using chemicals, radiations, dry heat (in oven) and moist heat (in autoclave). Palladium as a substrate. For the first time palladium deposited on agarose was used as a substrate for growth of fibroblast and glia. == See also == Substrate (aquatic environment) for the specific substrate in aquatic habitats == References == == External links == "Micro-vegetable growing" using abiotic substrates at home
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{
"page_id": 8327598,
"source": null,
"title": "Substrate (biology)"
}
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Cobalt is a chemical element; it has symbol Co and atomic number 27. As with nickel, cobalt is found in the Earth's crust only in a chemically combined form, save for small deposits found in alloys of natural meteoric iron. The free element, produced by reductive smelting, is a hard, lustrous, somewhat brittle, gray metal. Cobalt-based blue pigments (cobalt blue) have been used since antiquity for jewelry and paints, and to impart a distinctive blue tint to glass. The color was long thought to be due to the metal bismuth. Miners had long used the name kobold ore (German for goblin ore) for some of the blue pigment-producing minerals. They were so named because they were poor in known metals and gave off poisonous arsenic-containing fumes when smelted. In 1735, such ores were found to be reducible to a new metal (the first discovered since ancient times), which was ultimately named for the kobold. Today, some cobalt is produced specifically from one of a number of metallic-lustered ores, such as cobaltite (CoAsS). The element is more usually produced as a by-product of copper and nickel mining. The Copperbelt in the Democratic Republic of the Congo (DRC) and Zambia yields most of the global cobalt production. World production in 2016 was 116,000 tonnes (114,000 long tons; 128,000 short tons) according to Natural Resources Canada, and the DRC alone accounted for more than 50%. In 2024, production exceeded 300,000 tons, of which DRC accounted for more than 80%. Cobalt is primarily used in lithium-ion batteries, and in the manufacture of magnetic, wear-resistant and high-strength alloys. The compounds cobalt silicate and cobalt(II) aluminate (CoAl2O4, cobalt blue) give a distinctive deep blue color to glass, ceramics, inks, paints and varnishes. Cobalt occurs naturally as only one stable isotope, cobalt-59. Cobalt-60 is a commercially important
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{
"page_id": 24580536,
"source": null,
"title": "Cobalt"
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radioisotope, used as a radioactive tracer and for the production of high-energy gamma rays. Cobalt is also used in the petroleum industry as a catalyst when refining crude oil. This is to purge it of sulfur, which is very polluting when burned and causes acid rain. Cobalt is the active center of a group of coenzymes called cobalamins. Vitamin B12, the best-known example of the type, is an essential vitamin for all animals. Cobalt in inorganic form is also a micronutrient for bacteria, algae, and fungi. The name cobalt derives from a type of ore considered a nuisance by 16th century German silver miners, which in turn may have been named from a spirit or goblin held superstitiously responsible for it; this spirit is considered equitable to the kobold (a household spirit) by some, or, categorized as a gnome (mine spirit) by others. == Characteristics == Cobalt is a ferromagnetic metal with a specific gravity of 8.9. The Curie temperature is 1,115 Β°C (2,039 Β°F) and the magnetic moment is 1.6β1.7 Bohr magnetons per atom. Cobalt has a relative permeability two-thirds that of iron. Metallic cobalt occurs as two crystallographic structures: hcp and fcc. The ideal transition temperature between the hcp and fcc structures is 450 Β°C (842 Β°F), but in practice the energy difference between them is so small that random intergrowth of the two is common. Cobalt is a weakly reducing metal that is protected from oxidation by a passivating oxide film. It is attacked by halogens and sulfur. Heating in oxygen produces Co3O4 which loses oxygen at 900 Β°C (1,650 Β°F) to give the monoxide CoO. The metal reacts with fluorine (F2) at 520 K to give CoF3; with chlorine (Cl2), bromine (Br2) and iodine (I2), producing equivalent binary halides. It does not react with hydrogen gas
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(H2) or nitrogen gas (N2) even when heated, but it does react with boron, carbon, phosphorus, arsenic and sulfur. At ordinary temperatures, it reacts slowly with mineral acids, and very slowly with moist, but not dry, air. == Compounds == Common oxidation states of cobalt include +2 and +3, although compounds with oxidation states ranging from β3 to +5 are also known. A common oxidation state for simple compounds is +2 (cobalt(II)). These salts form the pink-colored metal aquo complex [Co(H2O)6]2+ in water. Addition of chloride gives the intensely blue [CoCl4]2β. In a borax bead flame test, cobalt shows deep blue in both oxidizing and reducing flames. === Oxygen and chalcogen compounds === Several oxides of cobalt are known. Green cobalt(II) oxide (CoO) has rocksalt structure. It is readily oxidized with water and oxygen to brown cobalt(III) hydroxide (Co(OH)3). At temperatures of 600β700 Β°C, CoO oxidizes to the blue cobalt(II,III) oxide (Co3O4), which has a spinel structure. Black cobalt(III) oxide (Co2O3) is also known. Cobalt oxides are antiferromagnetic at low temperature: CoO (NΓ©el temperature 291 K) and Co3O4 (NΓ©el temperature: 40 K), which is analogous to magnetite (Fe3O4), with a mixture of +2 and +3 oxidation states. The principal chalcogenides of cobalt are the black cobalt(II) sulfides, CoS2 (pyrite structure), Co2S3 (spinel structure), and CoS (nickel arsenide structure).: 1118 === Halides === Four dihalides of cobalt(II) are known: cobalt(II) fluoride (CoF2, pink), cobalt(II) chloride (CoCl2, blue), cobalt(II) bromide (CoBr2, green), cobalt(II) iodide (CoI2, blue-black). These halides exist in anhydrous and hydrated forms. Whereas the anhydrous dichloride is blue, the hydrate is red. The reduction potential for the reaction Co3+ + eβ β Co2+ is +1.92 V, beyond that for chlorine to chloride, +1.36 V. Consequently, cobalt(III) chloride would spontaneously reduce to cobalt(II) chloride and chlorine. Because the reduction potential for
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fluorine to fluoride is so high, +2.87 V, cobalt(III) fluoride is one of the few simple stable cobalt(III) compounds. Cobalt(III) fluoride, which is used in some fluorination reactions, reacts vigorously with water. === Coordination compounds === The inventory of complexes is very large. Starting with higher oxidation states, complexes of Co(IV) and Co(V) are rare. Examples are found in caesium hexafluorocobaltate(IV) (Cs2CoF6) and potassium percobaltate (K3CoO4). Cobalt(III) forms a wide variety of coordination complexes with ammonia and amines, which are called ammine complexes. Examples include [Co(NH3)6]3+, [Co(NH3)5Cl]2+ (chloropentamminecobalt(III)), and cis- and trans-[Co(NH3)4Cl2]+. The corresponding ethylenediamine complexes are also well known. Analogues are known where the halides are replaced by nitrite, hydroxide, carbonate, etc. Alfred Werner worked extensively on these complexes in his Nobel-prize winning work. The robustness of these complexes is demonstrated by the optical resolution of tris(ethylenediamine)cobalt(III) ([Co(en)3]3+). Cobalt(II) forms a wide variety of complexes, but mainly with weakly basic ligands. The pink-colored cation hexaaquocobalt(II) [Co(H2O)6]2+ is found in several routine cobalt salts such as the nitrate and sulfate. Upon addition of excess chloride, solutions of the hexaaquo complex converts to the deep blue CoCl2β4, which is tetrahedral. Softer ligands like triphenylphosphine form complexes with Co(II) and Co(I), examples being bis- and tris(triphenylphosphine)cobalt(I) chloride, CoCl2(PPh3)2 and CoCl(PPh3)3. These Co(I) and Co(II) complexes represent a link to the organometallic complexes described below. === Organometallic compounds === Cobaltocene is a structural analog to ferrocene, with cobalt in place of iron. Cobaltocene is much more sensitive to oxidation than ferrocene. Cobalt carbonyl (Co2(CO)8) is a catalyst in carbonylation and hydrosilylation reactions. Vitamin B12 (see below) is an organometallic compound found in nature and is the only vitamin that contains a metal atom. An example of an alkylcobalt complex in the otherwise uncommon +4 oxidation state of cobalt is the homoleptic complex tetrakis(1-norbornyl)cobalt(IV)
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(Co(1-norb)4), a transition metal-alkyl complex that is notable for its resistance to Ξ²-hydrogen elimination, in accord with Bredt's rule. The cobalt(III) and cobalt(V) complexes [Li(THF)4]+[Co(1-norb)4]β and [Co(1-norb)4]+[BF4]β are also known. == Isotopes == 59Co is the only stable cobalt isotope and the only isotope that exists naturally on Earth. Twenty-two radioisotopes have been characterized: the most stable, 60Co, has a half-life of 5.2714 years; 57Co has a half-life of 271.8 days; 56Co has a half-life of 77.27 days; and 58Co has a half-life of 70.86 days. All the other radioactive isotopes of cobalt have half-lives shorter than 18 hours, and in most cases shorter than 1 second. This element also has 4 meta states, all of which have half-lives shorter than 15 minutes. The isotopes of cobalt range in atomic weight from 50 u (50Co) to 73 u (73Co). The primary decay mode for isotopes with atomic mass unit values less than that of the only stable isotope, 59Co, is electron capture and the primary mode of decay in isotopes with atomic mass greater than 59 atomic mass units is beta decay. The primary decay products below 59Co are element 26 (iron) isotopes; above that the decay products are element 28 (nickel) isotopes. Because 59Co is a nucleus of spin 7/2 and 100% abundancy, it is possible to detect it using nuclear magnetic resonance spectroscopy. The nucleus has a magnetic quadrupole moment. Among all NMR active nuclei, 59Co has the largest chemical shift range and the chemical shift can be correlated with the spectrochemical series. Resonances are observed over a range of 20000 ppm, the width of the signals being up to 20 kHz. A widely used standard is potassium hexacyanocobaltate (0.1M K3Co(CN)6 in D2O), which, due to its high symmetry, has a rather small line width. Systems of low
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symmetry can yield broadened signals to an extent that renders the signals unobservable in fluid phase NMR, but still observable in solid state NMR. == Etymology == Many different stories about the origin of the word "cobalt" have been proposed. In one version the element cobalt was named after "kobelt", the name which 16th century German silver miners had given to a nuisance type of ore which occurred that was corrosive and issued poisonous gas. Although such ores had been used for blue pigmentation since antiquity, the Germans at that time did not have the technology to smelt the ore into metal (cf. Β§ History below). The authority on such kobelt ore (Latinized as cobaltum or cadmia) at the time was Georgius Agricola. He was also the oft-quoted authority on the mine spirits called "kobel" (Latinized as cobalus or pl. cobali) in a separate work. Agricola did not make a connection between the similarly named ore and spirit. However, a causal connection (ore blamed on "kobel") was made by a contemporary, and a word origin connection (word "formed" from cobalus) made by a late 18th century writer. Later, Grimms' dictionary (1868) noted the kobalt/kobelt ore was blamed on the mountain spirit (BergmΓ€nnchen) which was also held responsible for "stealing the silver and putting out an ore that caused poor mining atmosphere (Wetter) and other health hazards". Grimms' dictionary entries equated the word "kobel" with "kobold", and listed it as a mere variant diminutive, but the latter is defined in it as a household spirit. Whereas some of the more recent commentators prefer to characterize the ore's namesake kobelt (rectΓ© kobel) as a gnome. The early 20th century Oxford English Dictionary (1st edition, 1908) had upheld Grimm's etymology. However, by around the same time in Germany, the alternate etymology not endorsed
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by Grimm (kob/kof "house, chamber" + walt "power, ruler") was being proposed as more convincing. Somewhat later, Paul Kretschmer (1928) explained that while this "house ruler" etymology was the proper one that backed the original meaning of kobold as household spirit, a corruption later occurred introducing the idea of "mine demon" to it. The present edition of the Etymologisches WΓΆrterbuch (25th ed., 2012) under "kobold" lists the latter, not Grimm's etymology, but still persists, under its entry for "kobalt", that while the cobalt ore may have got its name from "a type of mine spirit/demon" (daemon metallicus) while stating that this is "apparently" the kobold. Joseph William Mellor (1935) also stated that cobalt may derive from kobalos (ΞΊΟβαλοΟ), though other theories had been suggested. === Alternate theories === Several alternative etymologies that have been suggested, which may not involve a spirit (kobel or kobold) at all. Karl MΓΌller-Fraureuth conjectured that kobelt derived from KΓΌbel, a bucket used in mining, frequently mentioned by Agricola, namely the kobel/kΓΆbel (Latinized as modulus). Another theory given by the Etymologisches WΓΆrterbuch derives the term from kΕbathium or rather cobathia (ΞΊΟβάθια, "arsenic sulfide") which occurs as noxious fumes. An etymology from Slavonic kowalti was suggested by Emanuel Merck (1902). W. W. Skeat and J. Berendes construed ΞΊΟΞ²Ξ±Ξ»ΞΏΟ as "parasite", i.e. as an ore parasitic to nickel, but this explanation is faulted for its anachronism since nickel was not discovered until 1751. == History == Cobalt compounds have been used for centuries to impart a rich blue color to glass, glazes, and ceramics. Cobalt has been detected in Egyptian sculpture, Persian jewelry from the third millennium BC, in the ruins of Pompeii, destroyed in 79 AD, and in China, dating from the Tang dynasty (618β907 AD) and the Ming dynasty (1368β1644 AD). Cobalt has been used to
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color glass since the Bronze Age. The excavation of the Uluburun shipwreck yielded an ingot of blue glass, cast during the 14th century BC. Blue glass from Egypt was either colored with copper, iron, or cobalt. The oldest cobalt-colored glass is from the eighteenth dynasty of Egypt (1550β1292 BC). The source for the cobalt the Egyptians used is not known. The word cobalt is derived from the 16th century German "kobelt", a type of ore, as aforementioned. The first attempts to smelt those ores for copper or silver failed, yielding simply powder (cobalt(II) oxide) instead. Because the primary ores of cobalt always contain arsenic, smelting the ore oxidized the arsenic into the highly toxic and volatile arsenic oxide, adding to the notoriety of the ore. Paracelsus, Georgius Agricola, and Basil Valentine all referred to such silicates as "cobalt". Swedish chemist Georg Brandt (1694β1768) is credited with discovering cobalt c. 1735, showing it to be a previously unknown element, distinct from bismuth and other traditional metals. Brandt called it a new "semi-metal", naming it for the mineral from which he had extracted it.: 153 He showed that compounds of cobalt metal were the source of the blue color in glass, which previously had been attributed to the bismuth found with cobalt. Cobalt became the first metal to be discovered since the pre-historical period. All previously known metals (iron, copper, silver, gold, zinc, mercury, tin, lead and bismuth) had no recorded discoverers. During the 19th century, a significant part of the world's production of cobalt blue (a pigment made with cobalt compounds and alumina) and smalt (cobalt glass powdered for use for pigment purposes in ceramics and painting) was carried out at the Norwegian BlaafarvevΓ¦rket. The first mines for the production of smalt in the 16th century were located in Norway, Sweden,
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Saxony and Hungary. With the discovery of cobalt ore in New Caledonia in 1864, the mining of cobalt in Europe declined. With the discovery of ore deposits in Ontario, Canada, in 1904 and the discovery of even larger deposits in the Katanga Province in the Congo in 1914, mining operations shifted again. When the Shaba conflict started in 1978, the copper mines of Katanga Province nearly stopped production. The impact on the world cobalt economy from this conflict was smaller than expected: cobalt is a rare metal, the pigment is highly toxic, and the industry had already established effective ways for recycling cobalt materials. In some cases, industry was able to change to cobalt-free alternatives. In 1938, John Livingood and Glenn T. Seaborg discovered the radioisotope cobalt-60. This isotope was famously used at Columbia University in the 1950s to establish parity violation in radioactive beta decay. After World War II, the US wanted to guarantee the supply of cobalt ore for military uses (as the Germans had been doing) and prospected for cobalt within the US. High purity cobalt was highly sought after for its use in jet engines and gas turbines. An adequate supply of the ore was found in Idaho near Blackbird canyon. Calera Mining Company started production at the site. Cobalt demand has further accelerated in the 21st century as an essential constituent of materials used in rechargeable batteries, superalloys, and catalysts. It has been argued that cobalt will be one of the main objects of geopolitical competition in a world running on renewable energy and dependent on batteries, but this perspective has also been criticised for underestimating the power of economic incentives for expanded production. == Occurrence == The stable form of cobalt is produced in supernovae through the r-process. It comprises 0.0029% of the Earth's
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crust. Except as recently delivered in meteoric iron, free cobalt (the native metal) is not found on Earth's surface because of its tendency to react with oxygen in the atmosphere. Small amounts of cobalt compounds are found in most rocks, soils, plants, and animals. In the ocean cobalt typically reacts with chlorine. In nature, cobalt is frequently associated with nickel. Both are characteristic components of meteoric iron, though cobalt is much less abundant in iron meteorites than nickel. As with nickel, cobalt in meteoric iron alloys may have been well enough protected from oxygen and moisture to remain as the free (but alloyed) metal. Cobalt in compound form occurs in copper and nickel minerals. It is the major metallic component that combines with sulfur and arsenic in the sulfidic cobaltite (CoAsS), safflorite (CoAs2), glaucodot ((Co,Fe)AsS), and skutterudite (CoAs3) minerals. The mineral cattierite is similar to pyrite and occurs together with vaesite in the copper deposits of Katanga Province. When it reaches the atmosphere, weathering occurs; the sulfide minerals oxidize and form pink erythrite ("cobalt glance": Co3(AsO4)2Β·8H2O) and spherocobaltite (CoCO3). Cobalt is also a constituent of tobacco smoke. The tobacco plant readily absorbs and accumulates heavy metals like cobalt from the surrounding soil in its leaves. These are subsequently inhaled during tobacco smoking. == Production == The main ores of cobalt are cobaltite, erythrite, glaucodot and skutterudite (see above), but most cobalt is obtained by reducing the cobalt by-products of nickel and copper mining and smelting. Since cobalt is generally produced as a by-product, the supply of cobalt depends to a great extent on the economic feasibility of copper and nickel mining in a given market. Demand for cobalt was projected to grow 6% in 2017. Primary cobalt deposits are rare, such as those occurring in hydrothermal deposits, associated with ultramafic
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rocks, typified by the Bou-Azzer district of Morocco. At such locations, cobalt ores are mined exclusively, albeit at a lower concentration, and thus require more downstream processing for cobalt extraction. Several methods exist to separate cobalt from copper and nickel, depending on the concentration of cobalt and the exact composition of the used ore. One method is froth flotation, in which surfactants bind to ore components, leading to an enrichment of cobalt ores. Subsequent roasting converts the ores to cobalt sulfate, and the copper and the iron are oxidized to the oxide. Leaching with water extracts the sulfate together with the arsenates. The residues are further leached with sulfuric acid, yielding a solution of copper sulfate. Cobalt can also be leached from the slag of copper smelting. The products of the above-mentioned processes are transformed into the cobalt oxide (Co3O4). This oxide is reduced to metal by the aluminothermic reaction or reduction with carbon in a blast furnace. == Extraction == The United States Geological Survey estimates world reserves of cobalt at 7,100,000 metric tons. The Democratic Republic of the Congo (DRC) currently produces 63% of the world's cobalt. This market share may reach 73% by 2025 if planned expansions by mining producers like Glencore Plc take place as expected. Bloomberg New Energy Finance has estimated that by 2030, global demand for cobalt could be 47 times more than it was in 2017. === Democratic Republic of the Congo === Changes that Congo made to mining laws in 2002 attracted new investments in Congolese copper and cobalt projects. In 2005, the top producer of cobalt was the copper deposits in the Democratic Republic of the Congo's Katanga Province. Formerly Shaba province, the area had almost 40% of global reserves, reported the British Geological Survey in 2009. The Mukondo Mountain project,
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operated by the Central African Mining and Exploration Company (CAMEC) in Katanga Province, may be the richest cobalt reserve in the world. It produced an estimated one-third of the total global cobalt production in 2008. In July 2009, CAMEC announced a long-term agreement to deliver its entire annual production of cobalt concentrate from Mukondo Mountain to Zhejiang Galico Cobalt & Nickel Materials of China. In 2016, Chinese ownership of cobalt production in the Congo was estimated at over 10% of global cobalt supply, forming a key input to the Chinese cobalt refining industry and granting China substantial influence over the global cobalt supply chain. Chinese control of Congolese cobalt has raised concern in Western nations which have sought to reduce supply chain reliance upon China and have expressed concern regarding labor and human rights violations in cobalt mines in the DRC. Glencore's Mutanda Mine shipped 24,500 tons of cobalt in 2016, 40% of Congo DRC's output and nearly a quarter of global production. After oversupply, Glencore closed Mutanda for two years in late 2019. Glencore's Katanga Mining project is resuming as well and should produce 300,000 tons of copper and 20,000 tons of cobalt by 2019, according to Glencore. In February 2018, global asset management firm AllianceBernstein defined the DRC as economically "the Saudi Arabia of the electric vehicle age", due to its cobalt resources, as essential to the lithium-ion batteries that drive electric vehicles. On 9 March 2018, President Joseph Kabila updated the 2002 mining code, increasing royalty charges and declaring cobalt and coltan "strategic metals". The 2002 mining code was effectively updated on 4 December 2018. In February 2025, the DRC implemented a four-month suspension of cobalt exports, citing an oversupply of the metal amid a price decline to its lowest level in 21 years. Cobalt, a key
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byproduct of copper mining, is an essential material in battery technology. The DRC accounts for approximately 75 percent of the global supply. Within the country, the China Molybdenum Company (CMOC) dominates the industry, contributing roughly 40 percent of the world's cobalt production. Over the past year, CMOC has significantly increased its output, doubling production from two of its mines in the DRC from 56,000 tonnes to 114,000 tonnes. ==== Labor conditions ==== Artisanal mining supplied 17% to 40% of the DRC production as of 2016. Some 100,000 cobalt miners in Congo DRC use hand tools to dig hundreds of feet, with little planning and fewer safety measures, say workers and government and NGO officials, as well as The Washington Post reporters' observations on visits to isolated mines. The lack of safety precautions frequently causes injuries or death. Mining pollutes the vicinity and exposes local wildlife and indigenous communities to toxic metals thought to cause birth defects and breathing difficulties, according to health officials. Child labor is used in mining cobalt from African artisanal mines. Human rights activists have highlighted this and investigative journalism reporting has confirmed it. This revelation prompted cell phone maker Apple Inc., on 3 March 2017, to stop buying ore from suppliers such as Zhejiang Huayou Cobalt who source from artisanal mines in the DRC, and begin using only suppliers that are verified to meet its workplace standards. In 2023, Apple announced it would convert to using recycled cobalt by 2025. There is a push globally by the EU and major car manufacturers (OEM) for global production of cobalt to be sourced and βproduced sustainably, responsibly and traceability of the supply chain. Mining companies are adopting and practising ESG initiatives in line with OECD Guidance and putting in place evidence of zero to low carbon footprint activities
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in the supply chain production of lithium-ion batteries. These initiatives are already taking place with major mining companies, artisanal and small-scale mining companies (ASM). Car manufacturers and battery manufacturer supply chains: Tesla, VW, BMW, BASF and Glencore are participating in several initiatives, such as the Responsible Cobalt Initiative and Cobalt for Development study. In 2018 BMW Group in partnership with BASF, Samsung SDI and Samsung Electronics have launched a pilot project in the DRC over one pilot mine, to improve conditions and address challenges for artisanal miners and the surrounding communities. The political and ethnic dynamics of the region have in the past caused outbreaks of violence and years of armed conflict and displaced populations. This instability affected the price of cobalt and also created perverse incentives for the combatants in the First and Second Congo Wars to prolong the fighting, since access to diamond mines and other valuable resources helped to finance their military goalsβwhich frequently amounted to genocideβand also enriched the fighters themselves. While DR Congo has in the 2010s not recently been invaded by neighboring military forces, some of the richest mineral deposits adjoin areas where Tutsis and Hutus still frequently clash, unrest continues although on a smaller scale and refugees still flee outbreaks of violence. Cobalt extracted from small Congolese artisanal mining endeavors in 2007 supplied a single Chinese company, Congo DongFang International Mining. A subsidiary of Zhejiang Huayou Cobalt, one of the world's largest cobalt producers, Congo DongFang supplied cobalt to some of the world's largest battery manufacturers, who produced batteries for ubiquitous products like the Apple iPhones. Because of accused labour violations and environmental concerns, LG Chem subsequently audited Congo DongFang in accordance with OECD guidelines. LG Chem, which also produces battery materials for car companies, imposed a code of conduct on all suppliers
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that it inspects. In December 2019, International Rights Advocates, a human rights NGO, filed a landmark lawsuit against Apple, Tesla, Dell, Microsoft and Google company Alphabet for "knowingly benefiting from and aiding and abetting the cruel and brutal use of young children" in mining cobalt. The companies in question denied their involvement in child labour. In 2024 the court ruled that the suppliers facilitate force labor but the US tech companies are not liable because they don't operate as a shared enterprise with the suppliers and that the "alleged injuries are not fairly traceable" to any of the defendants' conduct. The book Cobalt Red alleges that workers including children suffer injuries, amputations, and death as the result of the hazardous working conditions and mine tunnel collapses during artisanal mining of cobalt in the DRC. Since child and slave labor have been repeatedly reported in cobalt mining, primarily in the artisanal mines of DR Congo, technology companies seeking an ethical supply chain have faced shortages of this raw material and the price of cobalt metal reached a nine-year high in October 2017, more than US$30 a pound, versus US$10 in late 2015. After oversupply, the price dropped to a more normal $15 in 2019. As a reaction to the issues with artisanal cobalt mining in DR Congo a number of cobalt suppliers and their customers have formed the Fair Cobalt Alliance (FCA) which aims to end the use of child labor and to improve the working conditions of cobalt mining and processing in the DR Congo. Members of FCA include Zhejiang Huayou Cobalt, Sono Motors, the Responsible Cobalt Initiative, Fairphone, Glencore and Tesla, Inc. === Canada === In 2017, some exploration companies were planning to survey old silver and cobalt mines in the area of Cobalt, Ontario, where significant deposits are
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believed to lie. Cobalt mined in Canada is a by-product of nickel mining. Even so, in 2023 the country produced more than 5,000 tons of cobalt (43% is mined in Newfoundland and Labrador, the rest in Ontario, Manitoba and Quebec). Exports of cobalt and cobalt products totaled $568 million in 2023. === Cuba === Canada's Sherritt International processes cobalt ores in nickel deposits from the Moa mines in Cuba, and the island has several others mines in MayarΓ, CamagΓΌey, and Pinar del RΓo. Continued investments by Sherritt International in Cuban nickel and cobalt production while acquiring mining rights for 17β20 years made the communist country third for cobalt reserves in 2019, before Canada itself. === Indonesia === Starting from smaller amounts in 2021, Indonesia began producing cobalt as a byproduct of nickel production. By 2022, the country had become the world's second-largest cobalt producer, with Benchmark Mineral Intelligence forecasting Indonesian output to make up 20 percent of global production by 2030. Cobalt production increased from 1,300 tons to 20,500 tons between 2015 and 2024 due to the Indonesian government's strategic initiative to develop a robust domestic supply chain for electric vehicles. An export ban in 2020 has ensured an influx of foreign investment in nickel and cobalt processing in the country. == Applications == In 2016, 116,000 tonnes (128,000 short tons) of cobalt was used. Cobalt has been used in the production of high-performance alloys. It is also used in some rechargeable batteries. === Alloys === Cobalt-based superalloys have historically consumed most of the cobalt produced. The temperature stability of these alloys makes them suitable for turbine blades for gas turbines and aircraft jet engines, although nickel-based single-crystal alloys surpass them in performance. Cobalt-based alloys are also corrosion- and wear-resistant, making them, like titanium, useful for making orthopedic implants that
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do not wear down over time. The development of wear-resistant cobalt alloys started in the first decade of the 20th century with the stellite alloys, containing chromium with varying quantities of tungsten and carbon. Alloys with chromium and tungsten carbides are very hard and wear-resistant. Special cobalt-chromium-molybdenum alloys like Vitallium are used for prosthetic parts (hip and knee replacements). Cobalt alloys are also used for dental prosthetics as a useful substitute for nickel, which may be allergenic. Some high-speed steels also contain cobalt for increased heat and wear resistance. The special alloys of aluminium, nickel, cobalt and iron, known as Alnico, and of samarium and cobalt (samariumβcobalt magnet) are used in permanent magnets. It is also alloyed with 95% platinum for jewelry, yielding an alloy suitable for fine casting, which is also slightly magnetic. === Batteries === Lithium cobalt oxide (LiCoO2, aka "LCO"), first sold commercially in 1991 by Sony, was widely used in lithium-ion battery cathodes until the 2010s. The material is composed of cobalt oxide layers with the lithium intercalated. These LCO batteries continue to dominate the market for consumer electronics. Batteries for electric cars however have shifted to lower cobalt technologies. In 2018 most cobalt in batteries was used in a mobile device, a more recent application for cobalt is rechargeable batteries for electric cars. This industry increased five-fold in its demand for cobalt from 2016 to 2020, which made it urgent to find new raw materials in more stable areas of the world. Demand is expected to continue or increase as the prevalence of electric vehicles increases. Exploration in 2016β2017 included the area around Cobalt, Ontario, an area where many silver mines ceased operation decades ago. Cobalt for electric vehicles increased 81% from the first half of 2018 to 7,200 tonnes in the first half of
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2019, for a battery capacity of 46.3 GWh. As of August 2020 battery makers have gradually reduced the cathode cobalt content from 1/3 (NMC 111) to 1/5 (NMC 442) to currently 1/10 (NMC 811) and have also introduced the cobalt free lithium iron phosphate cathode into the battery packs of electric cars such as the Tesla Model 3. Research was also conducted by the European Union into the possibility of eliminating cobalt requirements in lithium-ion battery production. In September 2020, Tesla outlined their plans to make their own, cobalt-free battery cells. Nickelβcadmium (NiCd) and nickel metal hydride (NiMH) batteries also included cobalt to improve the oxidation of nickel in the battery. Lithium iron phosphate batteries officially surpassed ternary cobalt batteries in 2021 with 52% of installed capacity. Analysts estimate that its market share will exceed 60% in 2024. === Catalysts === Several cobalt compounds are oxidation catalysts. Cobalt acetate is used to convert xylene to terephthalic acid, the precursor of the bulk polymer polyethylene terephthalate. Typical catalysts are the cobalt carboxylates (known as cobalt soaps). They are also used in paints, varnishes, and inks as "drying agents" through the oxidation of drying oils. However, their use is being phased out due to toxicity concerns. The same carboxylates are used to improve the adhesion between steel and rubber in steel-belted radial tires. In addition they are used as accelerators in polyester resin systems. Cobalt-based catalysts are used in reactions involving carbon monoxide. Cobalt is also a catalyst in the FischerβTropsch process for the hydrogenation of carbon monoxide into liquid fuels. Hydroformylation of alkenes often uses cobalt octacarbonyl as a catalyst. The hydrodesulfurization of petroleum uses a catalyst derived from cobalt and molybdenum. This process helps to clean petroleum of sulfur impurities that interfere with the refining of liquid fuels. === Pigments
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and coloring === Before the 19th century, cobalt was predominantly used as a pigment. It has been used since the Middle Ages to make smalt, a blue-colored glass. Smalt is produced by melting a mixture of roasted mineral smaltite, quartz and potassium carbonate, which yields a dark blue silicate glass, which is finely ground after the production. Smalt was widely used to color glass and as pigment for paintings. In 1780, Sven Rinman discovered cobalt green, and in 1802 Louis Jacques ThΓ©nard discovered cobalt blue. Cobalt pigments such as cobalt blue (cobalt aluminate), cerulean blue (cobalt(II) stannate), various hues of cobalt green (a mixture of cobalt(II) oxide and zinc oxide), and cobalt violet (cobalt phosphate) are used as artist's pigments because of their superior chromatic stability. === Radioisotopes === Cobalt-60 (Co-60 or 60Co) is useful as a gamma-ray source because it can be produced in predictable amounts with high activity by bombarding cobalt with neutrons. It produces gamma rays with energies of 1.17 and 1.33 MeV. Cobalt is used in external beam radiotherapy, sterilization of medical supplies and medical waste, radiation treatment of foods for sterilization (cold pasteurization), industrial radiography (e.g. weld integrity radiographs), density measurements (e.g. concrete density measurements), and tank fill height switches. The metal has the unfortunate property of producing a fine dust, causing problems with radiation protection. Cobalt from radiotherapy machines has been a serious hazard when not discarded properly, and one of the worst radiation contamination accidents in North America occurred in 1984, when a discarded radiotherapy unit containing cobalt-60 was mistakenly disassembled in a junkyard in Juarez, Mexico. Cobalt-60 has a radioactive half-life of 5.27 years. Loss of potency requires periodic replacement of the source in radiotherapy and is one reason why cobalt machines have been largely replaced by linear accelerators in modern radiation
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}
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therapy. Cobalt-57 (Co-57 or 57Co) is a cobalt radioisotope most often used in medical tests, as a radiolabel for vitamin B12 uptake, and for the Schilling test. Cobalt-57 is used as a source in MΓΆssbauer spectroscopy and is one of several possible sources in X-ray fluorescence devices. Nuclear weapon designs could intentionally incorporate 59Co, some of which would be activated in a nuclear explosion to produce 60Co. The 60Co, dispersed as nuclear fallout, is sometimes called a cobalt bomb. === Magnetic materials === Due to the ferromagnetic properties of cobalt, it is used in the production of various magnetic materials. It is used in creating permanent magnets like Alnico magnets, known for their strong magnetic properties used in electric motors, sensors, and MRI machines. It is also used in production of magnetic alloys like cobalt steel, widely used in magnetic recording media such as hard disks and tapes. Cobalt's ability to maintain magnetic properties at high temperatures makes it valuable in magnetic recording applications, ensuring reliable data storage devices. Cobalt also contributes to specialized magnets such as samarium-cobalt and neodymium-iron-boron magnets, which are vital in electronics for components like sensors and actuators. === Other uses === Cobalt is used in electroplating for its attractive appearance, hardness, and resistance to oxidation. It is also used as a base primer coat for porcelain enamels. == Biological role == Cobalt is essential to the metabolism of all animals. It is a key constituent of cobalamin, also known as vitamin B12, the primary biological reservoir of cobalt as an ultratrace element. Bacteria in the stomachs of ruminant animals convert cobalt salts into vitamin B12, a compound which can only be produced by bacteria or archaea. A minimal presence of cobalt in soils therefore markedly improves the health of grazing animals, and an uptake of
|
{
"page_id": 24580536,
"source": null,
"title": "Cobalt"
}
|
0.20 mg/kg a day is recommended, because they have no other source of vitamin B12. Proteins based on cobalamin use corrin to hold the cobalt. Coenzyme B12 features a reactive C-Co bond that participates in the reactions. In humans, B12 has two types of alkyl ligand: methyl and adenosyl. MeB12 promotes methyl (βCH3) group transfers. The adenosyl version of B12 catalyzes rearrangements in which a hydrogen atom is directly transferred between two adjacent atoms with concomitant exchange of the second substituent, X, which may be a carbon atom with substituents, an oxygen atom of an alcohol, or an amine. Methylmalonyl coenzyme A mutase (MUT) converts MMl-CoA to Su-CoA, an important step in the extraction of energy from proteins and fats. Although far less common than other metalloproteins (e.g. those of zinc and iron), other cobaltoproteins are known besides B12. These proteins include methionine aminopeptidase 2, an enzyme that occurs in humans and other mammals that does not use the corrin ring of B12, but binds cobalt directly. Another non-corrin cobalt enzyme is nitrile hydratase, an enzyme in bacteria that metabolizes nitriles. === Cobalt deficiency === In humans, consumption of cobalt-containing vitamin B12 meets all needs for cobalt. For cattle and sheep, which meet vitamin B12 needs via synthesis by resident bacteria in the rumen, there is a function for inorganic cobalt. In the early 20th century, during the development of farming on the North Island Volcanic Plateau of New Zealand, cattle suffered from what was termed "bush sickness". It was discovered that the volcanic soils lacked the cobalt salts essential for the cattle food chain. The "coast disease" of sheep in the Ninety Mile Desert of the Southeast of South Australia in the 1930s was found to originate in nutritional deficiencies of trace elements cobalt and copper. The cobalt deficiency
|
{
"page_id": 24580536,
"source": null,
"title": "Cobalt"
}
|
was overcome by the development of "cobalt bullets", dense pellets of cobalt oxide mixed with clay given orally for lodging in the animal's rumen. == Health issues == The LD50 value for soluble cobalt salts has been estimated to be between 150 and 500 mg/kg. In the US, the Occupational Safety and Health Administration (OSHA) has designated a permissible exposure limit (PEL) in the workplace as a time-weighted average (TWA) of 0.1 mg/m3. The National Institute for Occupational Safety and Health (NIOSH) has set a recommended exposure limit (REL) of 0.05 mg/m3, time-weighted average. The IDLH (immediately dangerous to life and health) value is 20 mg/m3. However, chronic cobalt ingestion has caused serious health problems at doses far less than the lethal dose. In 1966, the addition of cobalt compounds to stabilize beer foam in Canada led to a peculiar form of toxin-induced cardiomyopathy, which came to be known as beer drinker's cardiomyopathy. Furthermore, cobalt metal is suspected of causing cancer (i.e., possibly carcinogenic, IARC Group 2B) as per the International Agency for Research on Cancer (IARC) Monographs. It causes respiratory problems when inhaled. It also causes skin problems when touched; after nickel and chromium, cobalt is a major cause of contact dermatitis. == Notes == == References == == Further reading == == External links == "Cobalt" . EncyclopΓ¦dia Britannica. Vol. VI (9th ed.). 1878. pp. 81β83. Cobalt at The Periodic Table of Videos (University of Nottingham) Centers for Disease and Prevention β Cobalt
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{
"page_id": 24580536,
"source": null,
"title": "Cobalt"
}
|
VFDB also known as Virulence Factor Database is a database that provides scientist quick access to virulence factors in bacterial pathogens. It can be navigated and browsed using genus or words. A BLAST tool is provided for search against known virulence factors. VFDB contains a collection of 16 important bacterial pathogens. Perl scripts were used to extract positions and sequences of VF from GenBank. Clusters of Orthologous Groups (COG) was used to update incomplete annotations. More information was obtained by NCBI. VFDB was built on Windows operation systems on DELL PowerEdge 1600SC servers. == See also == Antimicrobial resistance databases == References ==
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{
"page_id": 61149626,
"source": null,
"title": "VFDB"
}
|
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