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available, distending their bodies to the point of compromising ability to locomote; they can also survive 5 years without food in captivity. According to Kleiber's law, the larger an animal gets, the more efficient its metabolism becomes; i.e., an animal's basal metabolic rate scales to roughly the ¾ power of its mass. Under conditions of limited food supply, this may provide additional benefit to large size. === Reduced predation pressure === An additional possible influence is reduced predation pressure in deeper waters. A study of brachiopods found that predation was nearly an order of magnitude less frequent at the greatest depths than in shallow waters. === Increased dissolved oxygen === Dissolved oxygen levels are also thought to play a role in deep-sea gigantism. A 1999 study of benthic amphipod crustaceans found that maximum potential organism size directly correlates with the increased levels of dissolved oxygen levels in deeper waters. The solubility of dissolved oxygen in the oceans is known to lower in oxygen-poor intermediary depths (ranging 200-1000 meters) until the increasing pressure, decreasing salinity levels, and colder temperatures of deeper water can contribute increasing solubility once more. However, solubility does not necessarily equate to access as many areas of colder waters have exhibited lower levels of available oxygen. The proposed theory behind this trend is that deep-sea gigantism could be an adaptive trait to combat asphyxiation in frigid, dense ocean waters. Larger organisms are able to intake more dissolved oxygen within the ocean, allowing for sufficient respiration. However, this increased absorption of oxygen runs the risk of toxicity poisoning where an organism can have oxygen levels that are so high that they become harmful and poisonous. == Impact of Climate Change == Warmer global temperatures may have an effect on the deep sea as much as the shallower surface waters
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"page_id": 20975650,
"source": null,
"title": "Deep-sea gigantism"
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of the ocean, as evidence suggests that deep-sea ecosystems can be sensitive to shifts within the climate. Despite appearing relatively unchanging, the dependence of life in the depths on food supply to drift down in the form of marine snow and water currents traveling throughout all depths of the ocean calls into concern the manner in which global climate change may affect these organisms and the biomes they live in. Following trends from the Paleocene-Eocene thermal maximum and related timescales, research suggests that current predictions of continuous greenhouse gas emissions and climate change will lead to higher ocean temperatures and a significant reduction in levels of dissolved oxygen in the deep sea. Should global warming lead to a warmer ocean state, thermohaline circulation would no longer be able to maintain an oxygen-rich deep sea, which would eventually lead to deep water becoming higher in both temperature and salinity. Based upon current theories regarding the existence of deep-sea gigantism, we would expect to see the phenomenon diminish in response to these changes in the environment, as it may become unfavorable or even impossible for these organisms to sustain a larger body form. == Gallery == == See also == Cephalopod size Dwarfing Island gigantism Insular dwarfism Largest organisms Megafauna == References == == External links == Science Daily: Midgets and giants in the deep sea
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{
"page_id": 20975650,
"source": null,
"title": "Deep-sea gigantism"
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Shelter is a survival game developed by Might and Delight. In the game players control a mother badger who must protect and feed her cubs while travelling from their burrow to a new one. During the journey the cubs must be fed and are in danger from threats such as birds of prey and wildfires. It was released for Windows and Mac on 28 August 2013. The game was received positively and got favorable reviews on the graphics and sound, as well as the emotional impact that it evoked. Reviewers gave mixed reactions when it came to the difficulty and length. == Gameplay == In Shelter, players control a mother badger who is escorting her five cubs from their burrow to a new home and must protect them from danger. Along the journey the cubs will gradually get hungry and require food which the player must provide for them by either catching prey, such as foxes, or finding fruit and vegetables. Threats to the cubs come in different forms in each section of the game. In the first and latter sections of the game, there are areas that contain circling birds of prey which can fly down and pick off a cub if it is out in the open for too long. One section of the game takes place at night, giving the player limited vision of their surroundings. In this section, cubs will occasionally be scared by noises and will run away from the player, requiring them to chase the cubs until they are within a safe radius of the mother. In a later section, the player must travel through a wildfire, keeping the cubs safe from the spreading blaze. Another requires the player to escort the cubs up an overflowing river. The goal of the game becomes to
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"source": null,
"title": "Shelter (video game)"
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have as many cubs as possible survive the journey to shelter. == Development == Might and Delight began development on Shelter in January 2013 following the release of Pid. The game was announced and listed on Steam Greenlight in April, accepted in July, and released on 28 August of the same year. In December 2013 Might and Delight released a free add-on for Shelter in which the player must feed their cubs once a day for a month to keep them from dying. iOS and Android versions were released in February 2023. == Reception == Shelter received mostly positive reviews, scoring 68.79% and 69% on review aggregators GameRankings and Metacritic respectively. Reviewers praised the game for its emotion provoking nature, with the death of a cub "causing a genuine feeling of loss" for Ben Textor of Hardcore Gamer and the game's ending leaving Simon Parkin of Eurogamer "reeling with grief and bewilderment." In GameSpot's review Kevin VanOrd said that when a cub dies "there's a gnawing sense of failure, not as a game player, but as a parent with a duty to shield your young." The game's art and audio were generally well received, with Edge describing the game as having "a beautiful, pastel-coloured patchwork" and John Walker commenting that the game was "ludicrously pretty" in Rock, Paper, Shotgun's positive review. GameFront's review was less favourable of the graphics, with Jerry Bonner describing them as having "a distinctly polygonal look, as if this game was developed for the original Playstation." Of the audio, Mike Rose of Gamezebo said it was "just immense, and matches the surroundings perfectly." The lack of direction in the game was given mixed reception; Joystiq's JG Carter described the night time level as "ill-explained", and Edge said that the rules were "occasionally clunky [and] unclear." The
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{
"page_id": 40439843,
"source": null,
"title": "Shelter (video game)"
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length of the game was also criticised for being too short, with Mike Rose stating that he found the game "rather short" and Ben Textor saying the game was "somewhat pricey considering its runtime." == Sequel == On 9 March 2015, a sequel titled Shelter 2 was released via the software client Steam. This game has the player controlling a pregnant female lynx. Players guide the lynx as she finds a den for her coming litter of kittens and raises them, teaching them to survive in the wilderness. Unlike its predecessor, Shelter 2 allows the player to name the kittens. Those that survive a playthrough can also be controlled by the player, carrying on as the next generation of the family tree. == References == == External links == Official website
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{
"page_id": 40439843,
"source": null,
"title": "Shelter (video game)"
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In physics, the impact parameter b is defined as the perpendicular distance between the path of a projectile and the center of a potential field U(r) created by an object that the projectile is approaching (see diagram). It is often referred to in nuclear physics (see Rutherford scattering) and in classical mechanics. The impact parameter is related to the scattering angle θ by θ = π − 2 b ∫ r min ∞ d r r 2 1 − ( b / r ) 2 − 2 U / ( m v ∞ 2 ) , {\displaystyle \theta =\pi -2b\int _{r_{\text{min}}}^{\infty }{\frac {dr}{r^{2}{\sqrt {1-(b/r)^{2}-2U/(mv_{\infty }^{2})}}}},} where v∞ is the velocity of the projectile when it is far from the center, and rmin is its closest distance from the center. == Scattering from a hard sphere == The simplest example illustrating the use of the impact parameter is in the case of scattering from a sphere. Here, the object that the projectile is approaching is a hard sphere with radius R {\displaystyle R} . In the case of a hard sphere, U ( r ) = 0 {\displaystyle U(r)=0} when r > R {\displaystyle r>R} , and U ( r ) = ∞ {\displaystyle U(r)=\infty } for r ≤ R {\displaystyle r\leq R} . When b > R {\displaystyle b>R} , the projectile misses the hard sphere. We immediately see that θ = 0 {\displaystyle \theta =0} . When b ≤ R {\displaystyle b\leq R} , we find that b = R cos θ 2 . {\displaystyle b=R\cos {\tfrac {\theta }{2}}.} == Collision centrality == In high-energy nuclear physics — specifically, in colliding-beam experiments — collisions may be classified according to their impact parameter. Central collisions have b ≈ 0 {\displaystyle b\approx 0} , peripheral collisions have 0 < b
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"page_id": 10686498,
"source": null,
"title": "Impact parameter"
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< 2 R {\displaystyle 0<b<2R} , and ultraperipheral collisions (UPCs) have b > 2 R {\displaystyle b>2R} , where the colliding nuclei are viewed as hard spheres with radius R {\displaystyle R} . Because the color force has an extremely short range, it cannot couple quarks that are separated by much more than one nucleon's radius; hence, strong interactions are suppressed in peripheral and ultraperipheral collisions. This means that final-state particle multiplicity (the total number of particles resulting from the collision), is typically greatest in the most central collisions, due to the partons involved having the greatest probability of interacting in some way. This has led to charged particle multiplicity being used as a common measure of collision centrality, as charged particles are much easier to detect than uncharged particles. Because strong interactions are effectively impossible in ultraperipheral collisions, they may be used to study electromagnetic interactions — i.e. photon–photon, photon–nucleon, or photon–nucleus interactions — with low background contamination. Because UPCs typically produce only two to four final-state particles, they are also relatively "clean" when compared to central collisions, which may produce hundreds of particles per event. == See also == Distance of closest approach Hyperbolic trajectory § Impact parameter Schwarzschild geodesics § Bending of light by gravity Tests of general relativity == References == http://hyperphysics.phy-astr.gsu.edu/hbase/nuclear/rutsca2.html
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"page_id": 10686498,
"source": null,
"title": "Impact parameter"
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Intestines-on-a-chip (gut-on-a-chip, mini-intestine) are microfluidic bioengineered 3D-models of the real organ, which better mimic physiological features than conventional 3D intestinal organoid culture. A variety of different intestine-on-a-chip models systems have been developed and refined, all holding their individual strengths and weaknesses and collectively holding great promise to the ultimate goal of establishing these systems as reliable high-throughput platforms for drug testing and personalised medicine. The intestine is a highly complex organ system performing a diverse set of vital tasks, from nutrient digestion and absorption, hormone secretion, and immunological processes to neuronal activity, which makes it particularly challenging to model in vitro. == Conventional intestine models == Conventional intestinal models, such as traditional 2D cell culture of immortalised cell lines (e.g. CaCo2 or HT29), transwell cultures, Ussing chambers, and everted gut sacs, have been used extensively to understand better (patho-)physiological processes in the intestine. However, many intestinal functions are difficult to recapitulate and study using such simplistic models. Thus, these systems' translational and experimental value is limited. In 2009, the development of intestinal organoids marked a milestone in the in vitro modelling of intestinal tissue. Intestinal organoids mimic the in vivo stem cell niche as intestinal stem cells spontaneously give rise to a closed, cystic mini-tissue with outward-facing buds representing the characteristic crypt-villus architecture of the intestinal epithelium. Intestinal organoids can contain all the different cell types of the intestinal epithelium, e.g. enterocytes, goblet cells, Paneth cells and enteroendocrine cells. Together with the accurate representation of the tissue architecture and cell-type composition, organoids have been shown to also exhibit key functional similarities to the native tissue. Furthermore, their long-term stability in culture, derivation from healthy and diseased origin and genetic manipulation possibilities make intestinal organoids a useful though simplistic model for large spread use as a platform for functional studies and
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"page_id": 69799974,
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"title": "Intestine-on-a-chip"
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disease modelling. Nevertheless, several limitations restrict their usefulness as an intestinal model. First and foremost, the organoids' closed cystic structure makes their inner (apical) surface inaccessible, and separate treatment of apical and basolateral sides — and thus transport studies — highly cumbersome. Moreover, this closed cystic structure implies that intestinal organoids accumulate shed dead cells in their lumen putting spatial strain on the organoids, thus impeding undisturbed organoid culture over longer periods of time without disruption by mechanical disruption and passaging. Furthermore, intestinal organoid cultures suffer from strongly variable sizes, shapes, morphologies and localisations between single organoids in their 3D culture environment. == Intestine-on-a-chip models == Although organoids usually are referred to as miniature organs, they lack vital features to mimic organ-level complexity. For this reason, biofabricated devices have been developed, which surpass organoid limitations. Especially microfluidic devices hold great potential as platforms for in vitro models of organs, as they enable perfusion mimicking the function of blood circulation in tissues. Apart from fluidic flow, other culture parameters are incorporated into intestine-on-a-chip devices, including architectural cues, mechanical stimulation, oxygen gradients and co-cultures with other cell populations and the microbiota, to more accurately display the physiological behaviour of the actual organ. === Microfluidics === Opposite to traditional static cell culture, in microfluidic devices, fluid flows can be created, which closely mimick physiological fluid flow patterns. Fluid flow introduces physiological shear stress to cell surfaces, introduces apical delivery of nutrients and growth factors and enables the establishment of chemical gradients of, e.g. growth factors, which are vital for proper organ development. Overall, microfluidic devices increase the control over the organ-specific microenvironment, which allows for more precise models. Different technologies have been used to introduce microfluidic flows in intestine-on-a-chip devices, including peristaltic pumps, syringe pumps, pressure generators and pumpless systems driven by hydrostatic
|
{
"page_id": 69799974,
"source": null,
"title": "Intestine-on-a-chip"
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pressure and gravity. An example of a gravity-driven microfluidic intestine-on-a-chip device is the OrganoPlate platform by Mimetas, which has been used as a disease model for inflammatory bowel disease by Beaurivage et al. === Mechanical stimulation === Beginning from the early stages of embryonic development up to the post-natal life, the intestine is constantly exposed to a wide range of mechanical forces. Peristalsis, the involuntary and cyclic propulsion of intestinal contents, is an essential part of the digestive process. It facilitates food digestion, nutrient absorption and intestinal emptying on a macro scale and applies shear stress and radial pressure on the intestinal epithelium on a micro-scale. In particular, mechanical factors were shown to influence intestinal development and homeostasis, such as gut looping, villi formation, and crypt localisation. Moreover, the chronic absence of mechanical stimuli in the human intestine has been associated with intestinal morbidity. A prominent example where both mechanical stimulations in the form of peristalsis and microfluidic flow are used in combination is the Emulate intestine-on-a-chip system. The system consists of a two-way central cell culture microchannel, which is separated by a porous, extracellular matrix-coated, PDMS membrane allowing the separate culture of two different cell populations in the upper and lower microchannel. The central chamber is enclosed by two vacuum chambers running in parallel. The application of vacuum allows the cyclic unidirectional expansion of the porous membrane separating the channels to mimic peristaltic motion === Architectural cues === As in traditional organoid culture, introducing a third culture dimension is critical for a better representation of the microanatomy of a tissue. Since 3D cell cultures implement more physiologically relevant biochemical and mechanical cues, 3D cultures generally achieve better cell viability and a more physiological transcriptome and proteome. Moreover, tissue homeostasis processes such as proliferation, differentiation and cell death are represented
|
{
"page_id": 69799974,
"source": null,
"title": "Intestine-on-a-chip"
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in a more physiological manner. The 3D support of cell cultures is commonly based on hydrogels, which mimick the native extracellular matrix. Cells can either be embedded into hydrogels or grown on a predefined micro-engineered hydrogel surface. The most commonly used hydrogel for 3D intestinal systems is Matrigel, a solubilised basement membrane extract from mouse sarcoma. However, Matrigel has significant disadvantages such as a xenogeneic origin, bath-to-batch variability, high cost and a poorly defined composition. As these factors hinder clinical translation, other hydrogels are increasingly used in 3D intestinal models, including fibrin, collagen, hyaluronic acid and PEG-based synthetic hydrogels. In tissue engineering, microfabrication techniques are of critical importance, especially in modelling the tissue microenvironment. Apart from designing and fabricating the microfluidic device itself, microfabrication techniques are also used to create 3D microstructures which allow the patterning of cell culture surfaces closely resembling the native tissue topography, i.e. the crypt-villus-axis. A prominent example of an intestine-on-a-chip system relying on architectural cues is the homeostatic mini-intestines by Nikolaev et al. They use microfabricated intestine-on-a-chip devices with a hydrogel chamber. The collagen-Matrigel-mix hydrogel is laser-ablated to generate a microchannel for a tubular intestinal lumen with crypt structures. The culture of intestinal stem cells in this device results in their self-organisation into a functional epithelium with the physiological spatial arrangement of the crypt-villus domains. These mini-intestines allow for an extended long term culture and give rise to rare intestinal cell types not commonly found in other 3D models. Another example for architecturally driven morphogenesis of intestine-on-a-chip models are the surface patterning techniques published by Gjorevski et al., they developed microfabricated devices to pattern hydrogel surfaces in order to reproducibly direct intestinal organoid geometry, size and cell distributions. These examples show, that intestine-on-a-chip systems with extrinsically guided morphogenesis enable spatial and temporal control of signalling
|
{
"page_id": 69799974,
"source": null,
"title": "Intestine-on-a-chip"
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gradients and may provide a platform to extensively study intestinal morphogenesis, stem cell maintenance, crypt dynamics, and epithelial regeneration. === Co-culturing === The healthy intestine has a wide range of different functions, which requires a vast set of different cell types to fulfil them. The primary intestinal function, the absorption of nutrients, requires close contact between the intestinal epithelium and blood and lymph endothelial cells. Moreover, the intestinal microbiota plays a critical part in the digestion of food, which makes a reliable immune defence indispensable. Furthermore, muscle and nerve cells control peristalsis and satiety. Finally, mesenchymal cells are essential components of the intestinal stem cell niche as they provide physical support and secrete growth factors. Thus, incorporating different cell types in intestine-on-a-chip systems is vital to model different aspects of intestinal functions adequately. First steps were taken in co-culturing the intestinal epithelium and the microbiota in intestine-on-a-chip systems. Examples are the establishment of an in vitro model for intestinal Shigella flexneri infection using the Emulate intestine-on-a-chip system or the recreation of a complex faeces-derived microbiota population with both aerobic and anaerobic species. Similarly, researchers have tried to recreate an immunocompetent intestinal epithelium in intestine-on-a-chip systems, by co-culturing the intestinal epithelium with peripheral blood mononuclear cells, monocytes, macrophages or neutrophils. Moreover, the epithelial-endothelial interface has been modelled in several different systems by culturing endothelial monolayers and the intestinal epithelium on opposite sides of a porous membrane. Apart from co-culturing intestinal cells with other cell types, also the cell population of the intestinal epithelium is of high relevance. While some rather simplistic approaches use immortalised cell lines as cell source for an intestinal epithelium, there is a shift towards the use of organoid-derived intestinal stem cells, which allows the derivation of intestinal epithelia with a more physiological cell type composition. == References
|
{
"page_id": 69799974,
"source": null,
"title": "Intestine-on-a-chip"
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== == External links == MIMETAS OrganoPlate Platform with video: https://www.mimetas.com/en/perfused-tubules/ EMULATE Duodenum Intestine-Chip: https://emulatebio.com/duodenum-intestine-chip/ Homeostatic mini-intestine video: https://www.youtube.com/watch?v=IHKuri9sFEM&list=PLdV2S7pxgq9ZY1IBzIRJxDlq-lNKClsnW
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{
"page_id": 69799974,
"source": null,
"title": "Intestine-on-a-chip"
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The molecular formula C7H8N4O2 (molar mass: 180.16 g/mol) may refer to: Paraxanthine Theobromine Theophylline
|
{
"page_id": 9048103,
"source": null,
"title": "C7H8N4O2"
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The Polenske value (also known as the Polenske number) is a value determined when examining fat. It is an indicator of how much volatile fatty acid can be extracted from fat through saponification. It is equal to the number of milliliters of 0.1 normal alkali solution necessary for the neutralization of the water-insoluble volatile fatty acids distilled and filtered from 5 grams of a given saponified fat. (The hydroxide solution used in such a titration is typically made from sodium hydroxide, potassium hydroxide, or barium hydroxide.) It is measure of the steam volatile and water insoluble fatty acids, chiefly caprylic, capric and lauric acids, present in oil and fat. The value is named for the chemist who developed it, Eduard Polenske. The Reichert value and Kirschner value are related numbers based on similar tests. == References ==
|
{
"page_id": 9965607,
"source": null,
"title": "Polenske value"
}
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The Enhanced NeUtrino BEams from kaon Tagging or ENUBET is an ERC funded project that aims at producing an artificial neutrino beam in which the flavor, flux and energy of the produced neutrinos are known with unprecedented precision. Interest in these types of high precision neutrino beams has grown significantly in the last ten years, especially after the start of the construction of the DUNE and Hyper-Kamiokande detectors. DUNE and Hyper-Kamiokande are aimed at discovering CP violation in neutrinos observing a small difference between the probability of a muon-neutrino to oscillate into an electron-neutrino and the probability of a muon-antineutrino to oscillate into an electron-antineutrino. This effect points toward a difference in the behavior of matter and antimatter. In quantum field theory, this effect is described by a violation of the CP symmetry in particle physics. The experiments that will measure CP violation need a very precise knowledge of the neutrino cross-sections, i.e. the probability for a neutrino to interact in the detector. This probability is measured counting the number of interacting neutrinos divided by the flux of incoming neutrinos. Current neutrino cross-section experiments are limited by large uncertainties in the neutrino flux. A new generation of cross-section experiment is therefore needed to overcome these limitations with new techniques or high precision beams, as ENUBET. In ENUBET, neutrinos are produced by focusing mesons in a narrow band beam towards an instrumented decay tunnel, where charged leptons produced in association with neutrinos by mesons' decay can be monitored at the single particle level. Beams like ENUBET are called monitored neutrino beams. Mesons (essentially pions and kaons) are produced in the interactions of accelerated protons with a Beryllium or Graphite target. The proposed facility is being studied taking into account the energies of currently available proton drivers: 400 GeV (CERN SPS), 120
|
{
"page_id": 62525480,
"source": null,
"title": "ENUBET"
}
|
GeV (FNAL Main Injector), 30 GeV (J-PARC Main Ring). Kaons and pions are momentum and charge selected in a short transfer line by means of dipole and quadrupole magnets and are focused in a collimated beam into an instrumented decay tube. Large angle muons and positrons from kaon decays ( K + → μ + ν μ {\displaystyle K^{+}\rightarrow \mu ^{+}\nu _{\mu }} , K + → μ + π 0 ν μ {\displaystyle K^{+}\rightarrow \mu ^{+}\pi ^{0}\nu _{\mu }} , K + → e + π 0 ν e {\displaystyle K^{+}\rightarrow e^{+}\pi ^{0}\nu _{e}} ) are measured by detectors on the tunnel walls, while muons from pion decays ( π + → μ + ν μ {\displaystyle \pi ^{+}\rightarrow \mu ^{+}\nu _{\mu }} ) are monitored after the hadron dump at the end of the tunnel. The decay region is kept short (40 m) in order to reduce the neutrino contamination from muon decays ( μ + → e + ν e ν ¯ μ {\displaystyle \mu ^{+}\rightarrow e^{+}\nu _{e}{\bar {\nu }}_{\mu }} ). In this way, the neutrino flux is assessed in a direct way with a precision of 1%, without relying on complex simulations of the transfer line and on hadro-production data extrapolation that currently limits the knowledge of the flux to 5-10%. The ENUBET facility can be used to perform precision studies of the neutrino cross section and of sterile neutrinos or Non-Standard Interaction models. This method can also be extended to detect other leptons in order to have a complete monitored neutrino beam. The ENUBET project started in 2016. As of 2024, it involves 17 European institutions in 5 European countries and brings together about 80 scientists. ENUBET studies all technical and physics challenges to demonstrate the feasibility of a monitored neutrino beam: it has
|
{
"page_id": 62525480,
"source": null,
"title": "ENUBET"
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built a full-scale demonstrator of the instrumented decay tunnel (3 m length and partial azimuthal coverage) and assesses costs and physics reach of the proposed facility. The first end-to-end simulation of the ENUBET monitored neutrino beam was published in 2023. The ENUBET ERC project was completed in 2022. Since March 2019, ENUBET has been part of the CERN Neutrino Platform (NP06/ENUBET) for the development of a new generation of neutrino detectors and facilities. == References ==
|
{
"page_id": 62525480,
"source": null,
"title": "ENUBET"
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|
Heinz Maier-Leibnitz (28 March 1911, in Esslingen am Neckar – 16 December 2000, in Allensbach) was a German physicist. He made contributions to nuclear spectroscopy, coincidence measurement techniques, radioactive tracers for biochemistry and medicine, and neutron optics. He was an influential educator and an advisor to the Federal Republic of Germany on nuclear programs. During World War II, Maier-Leibnitz worked at the Institute of Physics of the Kaiser Wilhelm Institute for Medical Research, in Heidelberg. After the war, he spent a year working in North America, after which he returned to the Institute of Physics. In 1952, he assumed the Chair for Technical Physics and directorship of the Laboratory for Technical Physics at the Technische Hochschule München. He became a leader in establishing and building centers which used nuclear reactors as neutron sources for research. The first was the Research Reactor Munich, which was the seed for the entire Garching research campus of the Technische Hochschule München. The second was the German-French project to construct a high-flux neutron source and found the Institut Laue–Langevin in Grenoble, France; he was also its first director. His leadership also helped establish the Physics Department at the Technische Hochschule München. Maier-Leibnitz was the chairman of a special committee for designing the German Nuclear Program, and thus he was the architect of the first full-scale nuclear program of the Federal Republic of Germany. He was a signatory of the Göttingen Manifest. In his honor, the German Research Foundation annually awards six scientists with the Heinz Maier-Leibnitz-Preis. The research reactor Forschungsreaktor München II is officially named Forschungsneutronenquelle Heinz Maier-Leibnitz. == Education == Maier-Leibnitz studied physics at the University of Stuttgart and the University of Göttingen. He received his doctorate in 1935, from the University of Göttingen, under the Nobel Laureate James Franck and Georg Joos –
|
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"page_id": 21499946,
"source": null,
"title": "Heinz Maier-Leibnitz"
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Franck had emigrated from Germany in 1933 and his successor was Joos. Maier-Leibnitz was in the field of atomic physics, and he discovered metastable, negative helium ions, which later had applications in particle accelerators. == Career == Shortly after receipt of his doctorate in 1935, Maier-Leibnitz became an assistant to Walther Bothe, Director of the Institut für Physik (Institute for Physics) of the Kaiser-Wilhelm Institut für medizinische Forschung (KWImF, Kaiser Wilhelm Institute for Medical Research), in Heidelberg. [Note: After World War II, the KWImF was renamed the Max-Planck Institut für medizinische Forschung. In 1958, Bothe's Institut für Physik was spun off and elevated to become the Max-Planck-Institut für Kernphysik (MPIK, Max Planck Institute for Nuclear Physics).] Bothe had first met Maier-Leibnitz while on a recruiting trip to the University of Göttingen during which Robert Pohl and Georg Joos highly recommended Maier-Leibnitz for his intelligence and creativity. Maier-Leibnitz arrived at the Institute for Physics shortly after the arrival of Wolfgang Gentner, who became recognized as Bothe's second in command and took Maier-Leibnitz under his wing to become his mentor, critic, and a close friend. Maier-Leibnitz worked on nuclear spectroscopy, electron-gamma-ray coincidence measurements, radioactive tracers, and energy conservation in Compton scattering. In the early years of World War II, Maier-Leibnitz first served in the German air defense and then as a meteorologist at air bases in France. In 1942, he was recalled from the Eastern front and returned to continue his work with Bothe, who, since 1939, had been a principal in the German nuclear energy project, also known as the Uranverein (Uranium Club). After World War II, due to the ravages of war and the Allied occupation policies, Bothe's Institute for Physics fell on hard times. Maier-Leibnitz, Kurt Starke, and other younger colleagues of Bothe left for employment in North America.
|
{
"page_id": 21499946,
"source": null,
"title": "Heinz Maier-Leibnitz"
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|
Maier-Leibnitz left in the spring of 1947. When his contract expired in the spring of 1948, he returned to again work for Bothe. Maier-Leibnitz continued to work on nuclear spectroscopy and radioactive tracers in biochemistry and medicine. He also took up the study of positron annihilation in solids, which became a new tool for measuring the momentum distribution of bound electrons. In 1952, upon the retirement of Walther Meissner, Maier-Leibnitz assumed the Lehrstuhl für Technische Physik (Chair for Technical Physics) and directorship of the Laboratorium für technische Physik (Laboratory for Technical Physics) at the Technische Hochschule München (in 1970 renamed the Technische Universität München). This became the nucleus of the Maier-Leibnitz school for nuclear solid state physics. The far-sightedness of Maier-Leibnitz led to reorganization and expansion of physics at the Technische Hochschule München and the formation of the Physics Department in 1965. One of his first major expansions was done with the appointment of Nikolaus Riehl, who had returned to Germany in 1955, after having been taken to the Soviet Union in 1945 to work on the Soviet atomic bomb project. Riehl was an authority on the purification of uranium, and he greatly contributed to bringing about the construction of a new research tool at the Technische Hochschule München. Through the initiative and leadership of Maier-Leibnitz, the Forschungsreaktor München (FRM, Research Reactor Munich) was built in Garching bei München; it was the first nuclear reactor built in Germany. This reactor, popularly called the Atomei (atomic egg), based on its characteristic shape, was built in 1956 and became operational in 1957. Rather than being used to study reactor physics and technology, the swimming-pool-type reactor was used as a neutron source, and it became a versatile tool for interdisciplinary research. Furthermore, it was the seed for the entire Garching research campus. A
|
{
"page_id": 21499946,
"source": null,
"title": "Heinz Maier-Leibnitz"
}
|
second reactor built nearby, Forschungsreaktor München II (FRM II, Research Reactor Munich II), went critical for the first time four years after the death of Maier-Leibnitz; it was named the Forschungsneutronenquelle Heinz Maier-Leibnitz in his honor. During 1956 and 1957, Maier-Leibnitz was a member of the Arbeitskreis Kernphysik (Nuclear Physics Working Group) of the Fachkommission II „Forschung und Nachwuchs“ (Commission II “Research and Growth”) of the Deutschen Atomkommission (DAtK, German Atomic Energy Commission). Other members of the Nuclear Physics Working Group in both 1956 and 1957 were: Werner Heisenberg (chairman), Hans Kopfermann (vice-chairman), Fritz Bopp, Walther Bothe, Wolfgang Gentner, Otto Haxel, Willibald Jentschke, Josef Mattauch, Wolfgang Riezler, Wilhelm Walcher and Carl Friedrich von Weizsäcker. Wolfgang Paul was also a member of the group during 1957. Maier-Leibnitz was also a member of the Arbeitskreis Kernreaktoren (Nuclear Reactor Working Group) of the DAtK, and it was considered to be the most active and influential board of the DAtK. Some of the other members of the group were Erich Bagge, Wolfgang Finkelnburg, and Karl Wirtz. For the first decade of nuclear energy development in the Federal Republic of Germany (FRG), it was the center of decision making, and it had representative membership from German industry. Maier-Leibnitz was also the chairman of a special committee for designing the Deutsches Atomprogramm (German Nuclear Program). From this position, he became the architect of the first full-scale nuclear program of the FRG. In 1961, became an ordentlicher Professor (professor ordinarius) of technical physics at the Technische Hochschule München. Also in 1961, Rudolf L. Mößbauer, a former student of Maier-Leibnitz at Technische Hochschule München, received the Nobel Prize in Physics for his discovery of recoil-free emission and absorption of gamma radiation in solids known as the Mößbauer Effect, which led to numerous applications in solid state physics, chemistry,
|
{
"page_id": 21499946,
"source": null,
"title": "Heinz Maier-Leibnitz"
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biophysics, medicine and archeology. Maier-Leibnitz, along with his colleagues Wilhelm Brenig, Nikolaus Riehl and Wolfgang Wild, in a memorandum in 1962, proposed the establishment of a Physics Department at the Technische Hochschule München. This was used as bargaining tool to bring Mößbauer from the California Institute of Technology in Pasadena back to the Technische Hochschule München in 1964. The Physics Department was founded on 1 January 1965, replacing the three former independent institutes, but now with ten full professors, one of which was Maier-Leibnitz; the three institutes replaced were the Physikalisches Institut, the 'Laboratorium für technische Physik, and the Institut für Theoretische Physik. Through his experience and expertise in instrumental techniques, particularly neutron optics, Maier-Leibnitz was one of the first to realize that the neutron flux from the FRM was too low for some interesting experiments. Maier-Leibnitz was instrumental, along with Louis Néel, in bringing about the German-French project to construct a high-flux neutron source and founded the Institut Laue-Langevin in Grenoble in 1967, named in honor of the physicist Max von Laue and Paul Langevin. The reactor had the first source of cold neutrons. From 1967 to 1972, Maier-Leibnitz was the first director of the Institut Laue-Langevin. After the end of his term as director of the Institut Laue-Langevin, Maier-Leibnitz held other positions, including: 1972 – 1973: Member of the Wissenschaftsrat (German Council of Science and Humanities) 1972 – 1975: President of the International Union of Pure and Applied Physics 1973 – 1974: Chairman of the Gesellschaft Deutscher Naturforscher und Ärzte (Association of German Natural Scientists and Physicians) 1973 – 1983: Founding Council of the Carl-Friedrich-von-Siemens Foundation 1974 – 1979: President of the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) After 27 years of service at the Technische Universität München (formerly the Technische Hochschule München), Maier-Leibnitz achieved emeritus status in
|
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"page_id": 21499946,
"source": null,
"title": "Heinz Maier-Leibnitz"
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|
1979. Maier-Leibnitz was a member of the German Academy of Sciences Leopoldina, various academies of sciences and humanities (Heidelberg, Bavaria, Flanders, India, Sweden, Finland, France and Austria), of the Royal Swedish Academy of Sciences. He was co-editor of several journals, among them Nukleonik. Since 1979, the Heinz Maier-Leibnitz-Preis (Heinz Maier-Leibnitz Prize) has been annually given in his honor. The prize is funded by the Bundesministerium für Bildung und Forschung (BMBF, German Ministry of Education and Research), and it is awarded by a selection committee appointed by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) and the BMBF. Maier-Leibnitz was a signatory of the manifesto of the Göttinger Achtzehn (Göttingen Eighteen). Maier-Leibnitz was interested in cooking as a hobby, and he was the author of the cookbook Kochbuch für Füchse. == Honors == Maier-Leibnitz was awarded a number of honors, including: 1965 – Honorary doctorate from the University of Vienna 1966 – Honorary doctorate from the University of Grenoble 1996 – Stern-Gerlach-Medaille of the Deutsche Physikalische Gesellschaft. 1971 – Carus Medal of the German Academy of Sciences Leopoldina 1972 – Grand Cross of the Order of Merit of the Federal Republic of Germany 1973 – Honorary doctorate from the University of Reading. 1973 – Austrian Decoration for Science and Art 1979–1984 – Member and later Chancellor of the Pour le Mérite for Science and Art 1980 – Freiherr vom Stein Prize. 1981 – Bavarian Maximilian Order for Science and Art 1984 – Otto Hahn Prize of the City of Frankfurt am Main 1985 – Wilhelm Exner Medal. 1986 – Otto Hahn Prize for Chemistry and Physics of the German Chemical Society and the German Physical Society 1988 – Lorenz Oken Medal. 1991 – Grand Cross of Merit with Star and Sash of the Federal Republic of Germany 1995 – Order of Merit
|
{
"page_id": 21499946,
"source": null,
"title": "Heinz Maier-Leibnitz"
}
|
of Baden-Württemberg 2000 – Golden Ring of Honor of the Technical University of Munich == Notable Articles by Maier-Leibnitz == Heinz Maier-Leibnitz: Ausbeutemessungen beim Stoß langsamer Elektronen mit Edelgasatomen, Zeitschrift für Physik 95, 499–523 (July, 1935). H. Maier-Leibnitz: Absolute Zählrohrmessungen an γ-Strahlen, Zeitschrift für Naturforschung 1, 243 (1946). H. Maier-Leibnitz, W. Bothe: Experimental Nuclear Physics, Science 126, 246–247 (9 August 1957). H. Maier-Leibnitz and T. Springer: Ein Interferometer für langsame Neutronen, Zeitschrift für Physik 167, 386–402 (August, 1962). H. Maier-Leibnitz and T. Springer: The use of neutron optical devices on beam-hole experiments, J. Nucl. Energy 17, 217–225 (1963). H. Maier-Leibnitz: Grundlagen für die Beurteilung von Intensitäts- und Genauigkeitsfragen bei Neutronenstreumessungen, Nukleonik 8, 61 (1966: Invention of the neutron backscattering spectrometer). Friedrich Hund, Heinz Maier-Leibnitz, and Erich Mollwo: Physics in Göttingen with Franck, Born and Pohl, Eur. J. Phys. 9, 188-194 (1988). == Books by Maier-Leibnitz == Peter Kafka and Heinz Maier-Leibnitz Streitbriefe über Kernenergie. Zwei Physiker über Wissenschaft, Fortschritt und die Folgen (Piper, 1982). Heinz Maier-Leibnitz Lernschock Tschernobyl (Interfrom, 1986). Heinz Maier-Leibnitz Kochbuch für Füchse. Große Küche - schnell und gastlich [mit Hinweisen für d. Mikrowellenherd] (Piper, 1986). Peter Kafka and Heinz Maier-Leibnitz Kernenergie: Ja oder Nein? Eine Auseinandersetzung zwischen zwei Physikern (Piper, 1987). == Bibliography == Eckert, Michael Neutrons and politics: Maier-Leibnitz and the emergence of pile neutron research in the FRG, Historical Studies in the Physical and Biological Sciences Volume 19, Number 1, pp. 81 – 113 (1988). Edingshaus, Anne-Lydia Heinz Maier-Leibnitz: Ein halbes Jahrhundert experimentelle Physik (Piper, 1986). Kienle, Paul Heinz Meier-Leibnitz, Physics Today Volume 54, Number 8, pp. 65 – 66 (2001). Walker, Mark German National Socialism and the Quest for Nuclear Power 1939–1949 (Cambridge, 1993) ISBN 0-521-43804-7. == See also == Angular Correlation of Electron Positron Annihilation Radiation == Notes ==
|
{
"page_id": 21499946,
"source": null,
"title": "Heinz Maier-Leibnitz"
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The molecular formula C17H20N2O5S (molar mass: 364.41 g/mol, exact mass: 364.1093 u) may refer to: Bumetanide Pheneticillin
|
{
"page_id": 24711211,
"source": null,
"title": "C17H20N2O5S"
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Pannus is an abnormal layer of fibrovascular tissue or granulation tissue. Common sites for pannus formation include over the cornea, over a joint surface (as seen in rheumatoid arthritis), or on a prosthetic heart valve. Pannus may grow in a tumor-like fashion, as in joints where it may erode articular cartilage and bone. In common usage, the term pannus is often used to refer to a panniculus (a hanging flap of tissue). == Pannus in rheumatoid arthritis == The term "pannus" is derived from the Latin for "tablecloth". Chronic inflammation and exuberant proliferation of the synovium leads to formation of pannus and destruction of cartilage, bone, tendons, ligaments, and blood vessels. Pannus tissue is composed of aggressive macrophage- and fibroblast-like mesenchymal cells, macrophage-like cells and other inflammatory cells that release collagenolytic enzymes. In people suffering from rheumatoid arthritis, pannus tissue eventually forms in the joint affected by the disease, causing bony erosion and cartilage loss via release of IL-1, prostaglandins, and substance P by macrophages. == Pannus in ophthalmology == In ophthalmology, pannus refers to the growth of blood vessels into the peripheral cornea. In normal individuals, the cornea is avascular. Chronic local hypoxia (such as that occurring with overuse of contact lenses) or inflammation may lead to peripheral corneal vascularization, or pannus. Pannus may also develop in diseases of the corneal stem cells, such as aniridia. It is often resolved by peritomy. == References ==
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{
"page_id": 1904685,
"source": null,
"title": "Pannus"
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Sir Noel Stanley Bayliss (19 December 1906 – 17 February 1996) was an Australian chemist and professor of chemistry at the University of Western Australia. He was a Rhodes Scholar and graduated as dux of the academically renowned Melbourne High School. He then attended the University of Melbourne before going to Lincoln College, Oxford. The mineral baylissite K2Mg(CO3)2•4(H2O) is named for him. == References ==
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{
"page_id": 26021933,
"source": null,
"title": "Noel Bayliss"
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|
The molecular formula C19H18ClN3O5S (molar mass: 435.881 g/mol, exact mass: 435.0656 u) may refer to: Cloxacillin Rivaroxaban
|
{
"page_id": 24711216,
"source": null,
"title": "C19H18ClN3O5S"
}
|
Archibald Lang McLean (1885–13 May 1922) was an Australian bacteriologist known for his role as chief doctor on the Sir Douglas Mawson's Australasian Antarctic Expedition. == Biography == Archie McLean was born in Balmain, New South Wales on 27 March 1885. He was the grandson of Scottish migrants from Balmaha on the east side of Loch Lomond. He attended Five Dock Public School and later Fort Street High School before completing a Bachelor of Arts at the University of Sydney in 1906. He then studied medicine and graduated as a Master of Surgery in 1911. He was selected to join the Australasian Antarctic Expedition in 1911 as chief medical officer. Part of his role on the expedition was to study the effects of the Antarctic environment on other members of the expedition by taking regular blood samples and skin swabs. He took part in the Easter Sledging Journey with Cecil Madigan and Percy Correll, and after their return to main base remained there awaiting the return of Mawson, Xavier Mertz and Lieutenant Belgrave Ninnis. When Mawson returned, McLean treated his injuries and later treated wireless operator Sidney Jeffryes for symptoms of paranoia. McLean Nunataks are named in his honour. He arrived back in Australia in March 1914 and then travelled with Mawson to England. After the outbreak of World War I, he joined the Royal Army Medical Corps and served until 1916 when he was discharged for health reasons and returned to Australia. He completed his doctorate at the University of Sydney before joining the First Australian Imperial Force in the Australian Army Medical Corps in 1917 and returning to Europe. He was awarded the Military Cross for his service. He was discharged due to a bout of tuberculosis. He returned to Australia, where he was appointed Medical Officer at
|
{
"page_id": 5247034,
"source": null,
"title": "Archibald Lang McLean"
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the Red Cross War Chest Farm Colony in Beelbangara, New South Wales, however his condition worsened and he died in 1922. == References == == External links == Mellor, Lise. "McLean, Archibald Lang - Faculty of Medicine Online Museum and Archive". Contributor: Colin Sproule. The University of Sydney School of Medicine. Archived from the original on 26 June 2015. Retrieved 15 November 2020. "Beyond 1914; The University of Sydney and the Great War - Archibald Lang McLean - Timeline, Photographs, War Service Records, letters". The University of Sydney. Retrieved 15 November 2020. University of Sydney (1929). University of Sydney roll of service. Sydney: Publicity Press. p. 317. OCLC 472100411.
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{
"page_id": 5247034,
"source": null,
"title": "Archibald Lang McLean"
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Loab ( LOBE) is a fictional character that artist and writer Steph Maj Swanson has claimed to have discovered with a text-to-image AI model in April 2022. In a viral Twitter thread, Swanson described it as an unexpectedly emergent property of the software, saying they discovered it when asking the model to produce something "as different from the prompt as possible". == History == The Sweden-based artist Steph Maj Swanson said that they first generated these images in April 2022 by using the algorithmic technique of "negative prompt weights" accessing latent space, the initial prompt – 'Brando::-1', requesting the opposite of actor Marlon Brando – generated a "skyline logo" with cryptic lettering. Attempting to generate the opposite of this image using the prompt "DIGITA PNTICS skyline logo::-1" yielded what Swanson described as "off-putting images, all of the same devastated-looking older woman with defined triangles of rosacea(?) on her cheeks". Swanson nicknamed the character "Loab", after one of the generated images resembled an album cover that included the printed word "loab". Swanson says that using the image as a prompt for further images produced increasingly violent and gory results. Swanson speculated that something about the image could be "adjacent to extremely gory and macabre imagery in the distribution of the AI's world knowledge". Swanson says that when they combined images of Loab with other pictures, the subsequent results consistently return an image including Loab, regardless of how much distortion they added to the prompts to try and remove her visage. Swanson speculated that the latent space region of the AI map that Loab is located in, in addition to being near gruesome imagery, must be isolated enough that any combinations with other images could only use Loab from her area and no related images due to its isolation. After enough crossbreeding
|
{
"page_id": 71700540,
"source": null,
"title": "Loab"
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of images and dilution attempts, Swanson was able to eventually generate images without Loab, but found that crossbreeding those diluted images would also eventually lead to a version of Loab to reappear in the resulting images. Swanson has said that "for various reasons" they are declining to disclose the software used to create the images. Loab has been referred to as the "first AI-generated cryptid" and as such has gone viral. Despite hyping up the cryptid nature of the discovery in their wording, Swanson admitted that "Loab isn't really haunted, of course", but noted that the mythos that has sprung up around the AI-generated character has gone beyond their initial involvement. Also, since more images of Loab are being made by other artists now, future AIs will use those images as a part of their latent space maps, making her an innate part of the internet landscape now, with Swanson adding "If we want to get rid of her, it’s already too late." == Response == There has been discussion of whether the Loab series of images are "a legitimate quirk of AI art software, or a cleverly disguised creepypasta." Smithsonian magazine has written that "Loab sparked some lengthy ethical conversations around visual aesthetics, art and technology," and some have criticized the labeling of a woman with rosacea as a horror image, considering this to be "stigmatizing disability". Swanson responded that if the AI map is combining Loab with violent imagery, then that is a "social bias" in the data being used for the image modeling software. The Atlantic writer Stephen Marche described Loab as a "form of expression that has never existed before" whose authorship is unclear and that exists as an "emanation of the collective imagistic heritage, the unconscious visual mind". Laurens Verhagen in de Volkskrant commented that
|
{
"page_id": 71700540,
"source": null,
"title": "Loab"
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rather than showing that there are "dark horror creatures hidden deep within AI", the existence of Loab instead implies that our current "understanding of AI is limited". Mhairi Aitken at the Alan Turing Institute stated that rather than a "creepy" emergent property, output results like Loab are representative of the "limitations of AI image-generator models" and was more concerned about the urban legends that are born from such "boring" innocuous things and how easily "other people take these things seriously". Carly Cassella for ScienceAlert described Loab as a "modern day tronie" that isn't representative of something that is an actual person, but just a concept or idea, similar but distinct from tronies like the Girl With A Pearl Earring. Wired's Joel Warner argued that Loab is only the beginning and that, with AI text generators such as ChatGPT becoming more commonplace, a "linguistic version of Loab" will emerge in that space as well and begin creating ideas through "intentional prompts" or otherwise that will be as disturbing as The 120 Days of Sodom. == See also == Artificial intelligence art Contrastive Language-Image Pre-training (CLIP), an image recognition artificial intelligence system Flashed face distortion effect, another serendipitous visual phenomenon Crungus, another AI-generated cryptid == References == == External links == An interview with Loab's creator Original Twitter thread by Swanson Archived September 7, 2022, at the Wayback Machine
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{
"page_id": 71700540,
"source": null,
"title": "Loab"
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The ethics of uncertain sentience refers to questions surrounding the treatment of and moral obligations towards individuals whose sentience—the capacity to subjectively sense and feel—and resulting ability to experience pain is uncertain; the topic has been particularly discussed within the field of animal ethics, with the precautionary principle frequently invoked in response. == Views == === Animal ethics === David Foster Wallace in his 2005 essay "Consider the Lobster" investigated the potential sentience and capacity of crustaceans to experience pain and the resulting ethical implications of eating them. In 2014, the philosopher Robert C. Jones explored the ethical question that Wallace raised, arguing that "[e]ven if one remains skeptical of crustacean sentience, when it comes to issues of welfare it would be most prudent to employ the precautionary principle regarding our treatment of these animals, erring on the side of caution". Maximilian Padden Elder takes a similar view regarding the capacity for fishes to feel pain, arguing that the "precautionary principle is the moral ethic one ought to adopt in the face of uncertainty". In the 2015 essay "Reconsider the Lobster", Jeff Sebo quotes Wallace's discussion of the difficulty of establishing whether an animal can experience pain. Sebo calls the question of how to treat individuals of uncertain sentience, the "sentience problem" and argues that this problem which "Wallace raises deserves much more philosophical attention than it currently receives." Sebo asserts that there are two motivating assumptions behind the problem: "sentientism about moral status"—the idea that if an individual is sentient, then they deserve moral consideration—and "uncertainty about other minds", which refers to scientific and philosophical uncertainty about which individuals are sentient. In response to the problem, Sebo lays out three different potential approaches: the incautionary principle, which postulates that in cases of uncertainty about sentience it is morally permissible
|
{
"page_id": 64688191,
"source": null,
"title": "Ethics of uncertain sentience"
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to treat individuals as if they are not sentient; the precautionary principle, which suggests that in such cases we have a moral obligation to treat them as if they are sentient; and the expected value principle, which asserts that we are "morally required to multiply our credence that they are by the amount of moral value they would have if they were, and to treat the product of this equation as the amount of moral value that they actually have". Sebo advocates for the latter position. Jonathan Birch, in answer to the question surrounding animal sentience, advocates for a practical framework based on the precautionary principle, arguing that the framework aligns well with conventional practices in animal welfare science. Simon Knutsson and Christian Munthe argue that from the perspective of virtue ethics, that when it comes to animals of uncertain sentience, such as "fish, invertebrates such as crustaceans, snails and insects", that it is a "requirement of a morally decent (or virtuous) person that she at least pays attention to and is cautious regarding the possibly morally relevant aspects of such animals". Shelley A. Adamo argues that although the precautionary principle in relation to potential invertebrate sentience is the safest option, that it's not cost-free, as thoughtless legislation employed following the precautionary principle could be economically costly and that, as a result, we should be cautious about adopting it. === Environmental ethics === Kai Chan advocates for an environmental ethic, which is a form of ethical extensionism applied to all living beings because "there is a non-zero probability of sentience and consciousness" and that "we cannot justify excluding beings from consideration on the basis of uncertainty of their sentience". === Ethics of artificial intelligence === Nick Bostrom and Eliezer Yudkowsky argue that if an artificial intelligence is sentient, then it
|
{
"page_id": 64688191,
"source": null,
"title": "Ethics of uncertain sentience"
}
|
is wrong to inflict it unnecessary pain, in the same way that it is wrong to inflict pain on an animal, unless there are "sufficiently strong morally overriding reasons to do so". They also advocate for the "Principle of Substrate Non-Discrimination", which asserts: "If two beings have the same functionality and the same conscious experience, and differ only in the substrate of their implementation, then they have the same moral status." Soenke Ziesche and Roman Yampolskiy coined the term "AI welfare" and outlined the new field of AI welfare science, which is derived from animal welfare science. === Neuroethics === Adam J. Shriver argues for "precise, precautionary, and probabilistic approaches to sentience" and asserts that the evidence provided by neuroscience has differing relevance to each; he concludes that basic protections for animals should be guided by the precautionary principle and that although neuroscientific evidence in certain instances is not necessary to indicate that individuals of certain species require protections, "ongoing search for the neural correlates of sentience must be pursued in order to avoid harms that occur from mistaken accounts." == See also == == References == == Further reading == Chan, Kai M. A. (2011). "Ethical Extensionism under Uncertainty of Sentience: Duties to Non-Human Organisms without Drawing a Line". Environmental Values. 20 (3): 323–346. doi:10.3197/096327111X13077055165983. hdl:2429/45342. ISSN 0963-2719. JSTOR 23048366. Jakopovich, Daniel (2021). "The UK’s Animal Welfare (Sentience) Bill Excludes the Vast Majority of Animals: Why We Must Expand Our Moral Circle to Include Invertebrates", Animals & Society Research Initiative, University of Victoria, Canada. Birch, Jonathan (19 July 2024). The Edge of Sentience: Risk and Precaution in Humans, Other Animals, and AI. Oxford University Press. Sebo, Jeff (2025-01-28). The Moral Circle: Who Matters, What Matters, and Why (A Norton Short). W. W. Norton & Company. ISBN 978-1-324-06481-7. Clatterbuck, Hayley;
|
{
"page_id": 64688191,
"source": null,
"title": "Ethics of uncertain sentience"
}
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Fischer, Bob (2025-01-01). "Navigating Uncertainty about Sentience". Ethics. 135 (2): 229–258. doi:10.1086/732624. ISSN 0014-1704.
|
{
"page_id": 64688191,
"source": null,
"title": "Ethics of uncertain sentience"
}
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In quantum chemistry, Brillouin's theorem, proposed by the French physicist Léon Brillouin in 1934, relates to Hartree–Fock wavefunctions. Hartree–Fock, or the self-consistent field method, is a non-relativistic method of generating approximate wavefunctions for a many-bodied quantum system, based on the assumption that each electron is exposed to an average of the positions of all other electrons, and that the solution is a linear combination of pre-specified basis functions. The theorem states that given a self-consistent optimized Hartree–Fock wavefunction | ψ 0 ⟩ {\displaystyle |\psi _{0}\rangle } , the matrix element of the Hamiltonian between the ground state and a single excited determinant (i.e. one where an occupied orbital a is replaced by a virtual orbital r) must be zero. ⟨ ψ 0 | H ^ | ψ a r ⟩ = 0 {\displaystyle \langle \psi _{0}|{\hat {H}}|\psi _{a}^{r}\rangle =0} This theorem is important in constructing a configuration interaction method, among other applications. Another interpretation of the theorem is that the ground electronic states solved by one-particle methods (such as HF or DFT) already imply configuration interaction of the ground-state configuration with the singly excited ones. That renders their further inclusion into the CI expansion redundant. == Proof == The electronic Hamiltonian of the system can be divided into two parts. One consists of one-electron operators, describing the kinetic energy of the electron and the Coulomb interaction (that is, electrostatic attraction) with the nucleus. The other is the two-electron operators, describing the Coulomb interaction (electrostatic repulsion) between electrons. One-electron operator h ( 1 ) = − 1 2 ∇ 1 2 − ∑ α Z α r 1 α {\displaystyle h(1)=-{\frac {1}{2}}\nabla _{1}^{2}-\sum _{\alpha }{\frac {Z_{\alpha }}{r_{1\alpha }}}} Two-electron operator ∑ j | r 1 − r j | − 1 {\displaystyle \sum _{j}|r_{1}-r_{j}|^{-1}} In methods of wavefunction-based quantum chemistry which
|
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"page_id": 20320320,
"source": null,
"title": "Brillouin's theorem"
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include the electron correlation into the model, the wavefunction is expressed as a sum of series consisting of different Slater determinants (i.e., a linear combination of such determinants). In the simplest case of configuration interaction (as well as in other single-reference multielectron-basis set methods, like MPn, etc.), all the determinants contain the same one-electron functions, or orbitals, and differ just by occupation of these orbitals by electrons. The source of these orbitals is the converged Hartree–Fock calculation, which gives the so-called reference determinant | ψ 0 ⟩ {\displaystyle \left|\psi _{0}\right\rangle } with all the electrons occupying energetically lowest states among the available. All other determinants are then made by formally "exciting" the reference determinant (one or more electrons are removed from one-electron states occupied in | ψ 0 ⟩ {\displaystyle \left|\psi _{0}\right\rangle } and put into states unoccupied in | ψ 0 ⟩ {\displaystyle \left|\psi _{0}\right\rangle } ). As the orbitals remain the same, we can simply transition from the many-electron state basis ( | ψ 0 ⟩ {\displaystyle \left|\psi _{0}\right\rangle } , | ψ a r ⟩ {\displaystyle \left|\psi _{a}^{r}\right\rangle } , | ψ a b r s ⟩ {\displaystyle \left|\psi _{ab}^{rs}\right\rangle } , ...) to the one-electron state basis (which was used for Hartree–Fock: | a ⟩ {\displaystyle \left|a\right\rangle } , | b ⟩ {\displaystyle \left|b\right\rangle } , | r ⟩ {\displaystyle \left|r\right\rangle } , | s ⟩ {\displaystyle \left|s\right\rangle } , ...), greatly improving the efficiency of calculations. For this transition, we apply the Slater–Condon rules and evaluate ⟨ ψ 0 | H ^ | ψ a r ⟩ = ⟨ a | h | r ⟩ + ∑ b ⟨ a b | | r b ⟩ = ⟨ a | h | r ⟩ + ∑ b ( ⟨ a b | r b ⟩
|
{
"page_id": 20320320,
"source": null,
"title": "Brillouin's theorem"
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− ⟨ a b | b r ⟩ ) = ⟨ a | h | r ⟩ + ∑ b ( ⟨ a | 2 J ^ b − K ^ b | r ⟩ ) {\displaystyle \langle \psi _{0}|{\hat {H}}|\psi _{a}^{r}\rangle =\langle a|h|r\rangle +\sum _{b}\langle ab||rb\rangle =\langle a|h|r\rangle +\sum _{b}\left(\langle ab|rb\rangle -\langle ab|br\rangle \right)=\langle a|h|r\rangle +\sum _{b}\left(\langle a|2{\hat {J}}_{b}-{\hat {K}}_{b}|r\rangle \right)} which we recognize is simply an off-diagonal element of the Fock matrix ⟨ χ a | F ^ | χ r ⟩ {\displaystyle \langle \chi _{a}|{\hat {F}}|\chi _{r}\rangle } . But the reference wave function was obtained by the Hartree–Fock calculation, or the SCF procedure, the whole point of which was to diagonalize the Fock matrix. Hence for an optimized wavefunction this off-diagonal element must be zero. This can be made evident also if we multiply both sides of a Hartree–Fock equation F ^ χ r = ε r χ r {\displaystyle {\hat {F}}\chi _{r}=\varepsilon _{r}\chi _{r}} by χ a ∗ ( r → ) {\displaystyle \chi _{a}^{\ast }({\vec {r}})} and integrate over the electronic coordinate: ∫ − ∞ ∞ χ a ∗ ( r → ) F ^ χ r ( r → ) d 3 r → = ε r ∫ − ∞ ∞ χ a ∗ ( r → ) χ r ( r → ) d 3 r → . {\displaystyle \int _{-\infty }^{\infty }\chi _{a}^{\ast }({\vec {r}}){\hat {F}}\chi _{r}({\vec {r}})d^{3}{\vec {r}}=\varepsilon _{r}\int _{-\infty }^{\infty }\chi _{a}^{\ast }({\vec {r}})\chi _{r}({\vec {r}})d^{3}{\vec {r}}.} As the Fock matrix has already been diagonalized, the states χ r ∗ ( r → ) {\displaystyle \chi _{r}^{\ast }({\vec {r}})} and χ a ( r → ) {\displaystyle \chi _{a}({\vec {r}})} are the eigenstates of the Fock operator, and as such are orthogonal; thus their overlap is zero. It makes
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"page_id": 20320320,
"source": null,
"title": "Brillouin's theorem"
}
|
all the right-hand side of the equation zero: ∫ − ∞ ∞ χ a ∗ ( r → ) F ^ χ r ( r → ) d 3 r → = ⟨ ψ 0 | H ^ | ψ a r ⟩ = 0 , {\displaystyle \int _{-\infty }^{\infty }\chi _{a}^{\ast }({\vec {r}}){\hat {F}}\chi _{r}({\vec {r}})d^{3}{\vec {r}}=\langle \psi _{0}|{\hat {H}}|\psi _{a}^{r}\rangle =0,} which proves the Brillouin's theorem. The theorem have also been proven directly from the variational principle (by Mayer) and is essentially equivalent to the Hartree–Fock equations in general. == References == == Further reading == Cramer, Christopher J. (2002). Essentials of Computational Chemistry. Chichester: John Wiley & Sons, Ltd. pp. 207–211. ISBN 978-0-471-48552-0. Szabo, Attila; Neil S. Ostlund (1996). Modern Quantum Chemistry. Mineola, New York: Dover Publications, Inc. pp. 350–353. ISBN 978-0-486-69186-2.
|
{
"page_id": 20320320,
"source": null,
"title": "Brillouin's theorem"
}
|
Ecological facilitation or probiosis describes species interactions that benefit at least one of the participants and cause harm to neither. Facilitations can be categorized as mutualisms, in which both species benefit, or commensalisms, in which one species benefits and the other is unaffected. This article addresses both the mechanisms of facilitation and the increasing information available concerning the impacts of facilitation on community ecology. == Categories == There are two basic categories of facilitative interactions: Mutualism is an interaction between species that is beneficial to both. A familiar example of a mutualism is the relationship between flowering plants and their pollinators. The plant benefits from the spread of pollen between flowers, while the pollinator receives some form of nourishment, either from nectar or the pollen itself. Commensalism is an interaction in which one species benefits and the other species is unaffected. Epiphytes (plants growing on other plants, usually trees) have a commensal relationship with their host plant because the epiphyte benefits in some way (e.g., by escaping competition with terrestrial plants or by gaining greater access to sunlight) while the host plant is apparently unaffected. Strict categorization, however, is not possible for some complex species interactions. For example, seed germination and survival in harsh environments is often higher under so-called nurse plants than on open ground. A nurse plant is one with an established canopy, beneath which germination and survival are more likely due to increased shade, soil moisture, and nutrients. Thus, the relationship between seedlings and their nurse plants is commensal. However, as the seedlings grow into established plants, they are likely to compete with their former benefactors for resources. == Mechanisms == The beneficial effects of species on one another are realized in various ways, including refuge from physical stress, predation, and competition, improved resource availability, and transport.
|
{
"page_id": 4329538,
"source": null,
"title": "Ecological facilitation"
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|
=== Refuge from physical stress === Facilitation may act by reducing the negative impacts of a stressful environment. As described above, nurse plants facilitate seed germination and survival by alleviating stressful environmental conditions. A similar interaction occurs between the red alga Chondrus crispus and the canopy-forming seaweed Fucus in intertidal sites of southern New England, US. The alga survives higher in the intertidal zone—where temperature and desiccation stresses are greater—only when the seaweed is present because the canopy of the seaweed offers protection from those stresses. The previous examples describe facilitation of individuals or of single species, but there are also instances of a single facilitator species mediating some community-wide stress, such as disturbance. An example of such "whole-community" facilitation is substrate stabilization of cobble beach plant communities in Rhode Island, US, by smooth cordgrass (Spartina alterniflora). Large beds of cordgrass buffer wave action, thus allowing the establishment and persistence of a community of less disturbance-tolerant annual and perennial plants below the high-water mark. In general, facilitation is more likely to occur in physically stressful environments than in favorable environments, where competition may be the most important interaction among species. This can also occur in a single habitat containing a gradient from low to high stress. For example, along a New England, US, salt marsh tidal gradient, a presence of black needle rush (Juncus gerardii) increased the fitness of marsh elder (Iva annua) shrubs in lower elevations, where soil salinity was higher. The rush shaded the soil, which decreased evapotranspiration, and in turn decreased soil salinity. However, at higher elevations where soil salinity was lower, marsh elder fitness was decreased in the presence of the rush, due to increased competition for resources. Thus, the nature of species interactions may shift with environmental conditions. Facilitation has a greater effect on plant
|
{
"page_id": 4329538,
"source": null,
"title": "Ecological facilitation"
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|
interactions under environmental stress than competition. Another example is the positive effects of facilitation on desert plants that face the effects of rising aridification. Shrubs are known to provide favourable abiotic conditions in these dry regions. === Refuge from predation === Another mechanism of facilitation is a reduced risk of being eaten. Nurse plants, for example, not only reduce abiotic stress, but may also physically impede herbivory of seedlings growing under them. In both terrestrial and marine environments, herbivory of palatable species is reduced when they occur with unpalatable species. These "associational refuges" may occur when unpalatable species physically shield the palatable species, or when herbivores are "confused" by the inhibitory cues of the unpalatable species. Herbivory can also reduce predation of the herbivore, as in the case of the red-ridged clinging crab (Mithrax forceps) along the North Carolina, US, coastline. This crab species takes refuge in the branches of the compact ivory bush coral (Oculina arbuscula) and feeds on seaweed in the vicinity of the coral. The reduced competition with seaweed enhances coral growth, which in turn provides more refuge for the crab. A similar case is that of the interaction between swollen-thorn acacia trees (Acacia spp.) and certain ants (Pseudomyrmex spp.) in Central America. The acacia provides nourishment and protection (inside hollow thorns) to the ant in return for defense against herbivores. In contrast, a different type of facilitation between ants and sap-feeding insects may increase plant predation. By consuming sap, plant pests such as aphids produce a sugar-rich waste product called honeydew, which is consumed by ants in exchange for protection of the sap-feeders against predation. === Refuge from competition === Another potential benefit of facilitation is insulation from competitive interactions. Like the now familiar example of nurse plants in harsh environments, nurse logs in a forest
|
{
"page_id": 4329538,
"source": null,
"title": "Ecological facilitation"
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|
are sites of increased seed germination and seedling survival because the raised substrate of a log frees seedlings from competition with plants and mosses on the forest floor. The crab-coral interaction described above is also an example of refuge from competition, since the herbivory of crabs on seaweed reduces competition between coral and seaweed. Similarly, herbivory by sea urchins (Strongylocentrotus droebachiensis) on kelps (Laminaria spp.) can protect mussels (Modiolus modiolus) from overgrowth by kelps competing for space in the subtidal zone of the Gulf of Maine, US. In most cases, facilitation and competition are inversely proportional. Studies suggest that facilitation events in nature are rare compared to competition events and thus, competition is a greater driver for ecological processes. === Improved resource availability === Facilitation can increase access to limiting resources such as light, water, and nutrients for interacting species. For example, epiphytic plants often receive more direct sunlight in the canopies of their host plants than they would on the ground. Also, nurse plants increase the amount of water available to seedlings in dry habitats because of reduced evapotranspiration beneath the shade of nurse plant canopies. A special case concerns human facilitation of sap-feeding birds. Three African bird species (village weaver Ploceus cucullatus, common bulbul Pycnonotus barbatus, and mouse‐brown sunbird Anthreptes gabonicus) regularly feed on the sap flowing from holes made by local wine tappers in oil‐palm trees Elaies guineensis in the Bijagós archipelago, Guinea‐Bissau. However, the most familiar examples of increased access to resources through facilitation are the mutualistic transfers of nutrients between symbiotic organisms. A symbiosis is a prolonged, close association between organisms, and some examples of mutualistic symbioses include: Gut flora Associations between a host species and a microbe living in the host's digestive tract, wherein the host provides habitat and nourishment to the microbe in
|
{
"page_id": 4329538,
"source": null,
"title": "Ecological facilitation"
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|
exchange for digestive services. For example, termites receive nourishment from cellulose digested by microbes inhabiting their gut. Lichens Associations between fungi and algae, wherein the fungus receives nutrients from the alga, and the alga is protected from harsh conditions causing desiccation. Corals Associations between reef-building corals and photosynthetic algae called zooxanthellae, wherein the zooxanthellae provide nutrition to the corals in the form of photosynthate, in exchange for nitrogen in coral waste products. Mycorrhizae Associations between fungi and plant roots, wherein the fungus facilitates nutrient uptake (particularly nitrogen) by the plant in exchange for carbon in the form of sugars from the plant root. There is a parallel example in marine environments of sponges on the roots of mangroves, with a relationship analogous to that of mycorrhizae and terrestrial plants. === Transport === The movement by animals of items involved in plant reproduction is usually a mutualistic association. Pollinators may increase plant reproductive success by reducing pollen waste, increasing dispersal of pollen, and increasing the probability of sexual reproduction at low population density. In return, the pollinator receives nourishment in the form of nectar or pollen. Animals may also disperse the seed or fruit of plants, either by eating it (in which case they receive the benefit of nourishment) or by passive transport, such as seeds sticking to fur or feathers. == Community effects == Although facilitation is often studied at the level of individual species interactions, the effects of facilitation are often observable at the scale of the community, including impacts to spatial structure, diversity, and invasibility. === Spatial structure === Many facilitative interactions directly affect the distribution of species. As discussed above, transport of plant propagules by animal dispersers can increase colonization rates of more distant sites, which may impact the distribution and population dynamics of the plant species.
|
{
"page_id": 4329538,
"source": null,
"title": "Ecological facilitation"
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Facilitation most often affects distribution by simply making it possible for a species to occur in a site where some environmental stress would otherwise prohibit growth of that species. This is apparent in whole-community facilitation by a foundation species, such as sediment stabilization in cobble beach plant communities by smooth cordgrass. A facilitating species may also help drive the progression from one ecosystem type to another, as mesquite apparently does in the grasslands of the Rio Grande Plains. As a nitrogen-fixing tree, mesquite establishes more readily than other species on nutrient-poor soils, and following establishment, mesquite acts as a nurse plant for seedlings of other species. Thus, mesquite facilitates the dynamic spatial shift from grassland to savanna to woodland across the habitat. === Diversity === Facilitation affects community diversity (defined in this context as the number of species in the community) by altering competitive interactions. For example, intertidal mussels increase total community species diversity by displacing competitive large sessile species such as seaweed and barnacles. Although the mussels decrease diversity of primary space holders (i.e., large sessile species), a larger number of invertebrate species are associated with mussel beds than with other primary space holders, so total species diversity is higher when mussels are present. The effect of facilitation on diversity could also be reversed, if the facilitation creates a competitive dominance that excludes more species than it permits. Facilitation, in certain cases, has evolutionary outcomes, increasing diversity in communities. Other mechanisms such as resource partitioning and sampling effect act in tandem with facilitation to increase biodiversity (observable evidence in plant communities). === Invasibility === Facilitation of non-native species, either by native species or other non-native species, may increase the invasibility of a community, or the ease with which non-native species become established in a community. In an examination of
|
{
"page_id": 4329538,
"source": null,
"title": "Ecological facilitation"
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|
254 published studies of introduced species, 22 of 190 interactions studied between introduced species in the studies were facilitative. 128 of the 190 examined interactions were predator–prey relationships of a single plant-eating insect reported in a single study, which may have overemphasized the importance of negative interactions. Introduced plants are also facilitated by native pollinators, dispersers, and mycorrhizae. Thus, positive interactions must be considered in any attempt to understand the invasibility of a community. == See also == Nurse plants Symbiosis Mutualism (biology) Mycorrhizal network == Notes == == References == Shears N.T.; Babcock R.C. (2007) Quantitative description of mainland New Zealand's shallow subtidal reef communities Science for Conservation 280. p 126. Published by Department of Conservation, New Zealand
|
{
"page_id": 4329538,
"source": null,
"title": "Ecological facilitation"
}
|
The substituted benzothiophenes are a class of chemical compounds based on benzothiophene. They are closely related to the substituted benzofurans, substituted tryptamines, and to other chemical groups such as the substituted benzodioxoles (or methylenedioxyphenyl compounds). Substituted benzothiophenes include the (2-aminopropyl)benzo[β]thiophenes (APBTs) 2-APBT, 3-APBT (SKF-6678), 4-APBT, 5-APBT, 5-MAPBT, 6-APBT, 6-MAPBT, and 7-APBT. These drugs have been found to act as serotonin–norepinephrine–dopamine releasing agents (SNDRAs) and, in some cases, as potent serotonin 5-HT2 receptor agonists, analogously to the entactogen MDMA. They do not produce hyperlocomotion in rodents, suggesting that they lack psychostimulant effects. However, those acting as serotonin 5-HT2 receptor agonists have been found to induce the head-twitch response, a behavioral proxy of psychedelic effects, in rodents. These findings suggest that substituted benzothiophenes may have entactogenic and/or psychedelic effects in humans whilst lacking stimulant effects and possibly having reduced misuse potential. The substituted benzothiophenes have been little-encountered as designer drugs as of 2022. Tactogen has patented a number of benzothiophenes as novel entactogens for use as potential medicines. == See also == Substituted methylenedioxyphenethylamine § Related compounds == References ==
|
{
"page_id": 79040584,
"source": null,
"title": "Substituted benzothiophene"
}
|
The Jaffe reaction is a colorimetric method used in clinical chemistry to determine creatinine levels in blood and urine. In 1886, Max Jaffe (1841–1911) wrote about its basic principles in the paper Über den Niederschlag, welchen Pikrinsäure in normalem Harn erzeugt und über eine neue Reaction des Kreatinins in which he described the properties of creatinine and picric acid in an alkaline solution. The color change that occurred was directly proportional to the concentration of creatinine, however he also noted that several other organic compounds induced similar reactions. In the early 20th century, Otto Folin adapted Jaffe's research into a clinical procedure. The Jaffe reaction, despite its nonspecificity for creatinine, is still widely employed as the method of choice for creatinine testing due to its speed, adaptability in automated analysis, and cost-effectiveness, and is the oldest methodology continued to be used in the medical laboratory. It is this nonspecificity that has motivated the development of new reference methods for creatinine analysis into the 21st century. == Max Jaffe == Max Jaffe was a distinguished 19th-century German biochemist, pathologist, pharmacologist, and professor. He was born on July 25, 1841, in what was formerly Grünberg, Silesia and is now Zielona Góra, Poland. While attending medical school at the University of Berlin, he studied under Ludwig Traube and Wilhelm Kühne. Afterward, he worked as an assistant in a medical clinic in Königsberg. There, he co-authored a paper on putrid sputum with Ernst Viktor von Leyden that led to the discovery of certain characteristic putrid processes in the lungs. After earning his degree in internal medicine, he served in the Franco-Prussian War and was decorated with the Iron Cross Second Class. The title of Extraordinary Professor of Medicinal Chemistry was awarded to him in 1872 and the following year he became the first Ordinary
|
{
"page_id": 37425225,
"source": null,
"title": "Jaffe reaction"
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|
Professor of Pharmacology at the University of Königsberg. He was promoted to director of the Laboratory for Medical Chemistry and Experimental Pharmacology in 1878 and became a member of the Deutsche Akademie der Naturforscher Leopoldina in 1882. Aside from studying creatinine, he is also known for discovering urobilin and urobilinogen in urine and found that these compounds originated in bile. He died on October 26, 1911, in Berlin and is buried in the Weißensee Cemetery. === "...eine neue Reaktion des Kreatinins" === Creatinine was first synthesized in vitro by Ivan Horbaczewski in 1885. One year later, Jaffe's research was published in the paper Über den Niederschlag, welchen Pikrinsäre in normalem Harn erzeugt und über eine neue Reaction des Kreatinins. Jaffe had noticed that, when mixed in a sodium hydroxide (NaOH) solution, picric acid and creatinine formed a reddish-orange color and needle-like crystal precipitate. By using zinc chloride in a process known as the Neubauer reaction, and then performing the Weyl's test, a colorimetric reaction using sodium nitroprusside (SNP), he determined that the precipitated compound was a double salt of the solution. Although he found the amount of precipitate directly proportional to the creatinine concentration, he also noted that the reaction was highly nonspecific and could be observed with many other organic compounds. == Clinical applications == Although Jaffe's name is synonymous with clinical creatinine testing, his paper only described the principle behind what would later become the enduring method. It was Otto Folin (1867–1934), a Harvard biochemist, who adapted Jaffe's research—abandoning the standard Neubauer reaction of the time—and published several papers using the Jaffe reaction to analyze creatinine levels in both blood and urine. Folin began using the picric acid procedure in 1901 and included it in his 1916 Lab Manual of Biological Chemistry. During his career, Folin modified and
|
{
"page_id": 37425225,
"source": null,
"title": "Jaffe reaction"
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|
improved several quantitative colorimetric procedures, the first of which was for creatinine. He took advantage of technology available at the time, using a Duboscq colorimeter for measurement precision, and is credited for introducing colorimetry into modern biochemical analysis. Folin's research did not focus on creatinine as a renal function indicator. Since the precursors of creatinine are synthesized in the liver, at this point in history, creatinine was considered indicative of liver function. It was not until 1926 that Poul Kristian Brandt Rehberg suggested creatinine was a significant marker for renal function. === Interfering chromogens === The nonspecificity of Jaffe's reaction causes falsely elevated creatinine results in the presence of protein, glucose, acetoacetate, ascorbic acid, guanidine, acetone, cephalosporins, aminoglycosides (mainly streptomycin), ketone bodies, α-keto acids, and other organic compounds. Ammonium is also an interferent; if the sample is plasma, care needs to be taken that ammonium heparin has not been used as an anticoagulant. Nonspecificity is markedly decreased in urine samples since urine creatinine levels are much higher than blood and it generally does not contain significant levels of interfering chromogens. The Jaffe reaction's nonspecificity remains an important issue. Diabetes patients are a high-risk population to develop chronic kidney disease (CKD) and, therefore, interferences from glucose and acetoacetate are of particular importance. Artifacts such as hemolysis, lipemia, and icteremia can also affect accuracy. Hemolysis releases Jaffe-reacting chromogens and therefore will falsely increase results. Lipemia and icteremia can inhibit optical readings and falsely decrease values. The procedure has been developed over time with the intention to minimize these interferents. === From Neubauer to SRM 967 === Before Jaffe, Neubauer described a similar precipitation reaction by mixing creatinine with zinc chloride (ZnCl2) and performing a Weyl's test—the addition of SNP to NaOH and then incubating with acetic acid (CH3CO2H) to develop a color
|
{
"page_id": 37425225,
"source": null,
"title": "Jaffe reaction"
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|
change. Until Folin developed Jaffe's reaction into a clinical procedure, Neubauer's method was how creatinine was measured. As Folin's method evolved, various techniques were implemented to remove Jaffe-reacting substances, mostly protein, from the sample and increase specificity. By the 1950s, precipitated aluminum silicate, called Lloyd's reagent, was being used to remove protein from serum, further improving accuracy. Fuller's earth was also used for protein-binding, but the reference method until the 1980s was adsorption with Lloyd's reagent. New concerns arose due to non-standardization of procedures; different labs were reading results at different endpoints. This problem was resolved with the advent of automated analyzers in the 1960s and 1970s, which introduced a kinetic reading of results rather than a specific endpoint. Kinetic Jaffe methods involve mixing serum with alkaline picrate and reading the rate of change in absorption spectrophotometrically at 520 nm. This not only standardized the procedure, but also removed the need for sample deproteinization. It also introduced two new problems—analyzers used an algorithmic compensation to correct for pseudochromogens, and calibrations were not yet standardized between instruments. The 1980s saw several new technologies that promised to change the way creatinine testing was done. Enzymatic and ion-exchange methods provided better accuracy but had other drawbacks. Enzymatic methods reduced some interferences but other new ones were discovered. High-performance liquid chromatography, HPLC, was more sensitive and specific, and had become the new reference method endorsed by the American Association for Clinical Chemistry. HPLC addressed the shortcomings of Jaffe-based methods, but was labor-intensive, expensive, and therefore impractical for routine analysis of the most frequently ordered renal analyte in medical labs. Simple, easily automated and cost-effective, Jaffe-based methods have persisted into the 21st century, despite their imperfections. By 2006, isotope dilution mass spectrometry (IDMS) became the reference method. To improve the accuracy in creatinine testing, new
|
{
"page_id": 37425225,
"source": null,
"title": "Jaffe reaction"
}
|
standards were developed by the National Institute of Standards and Technology (NIST). The College of American Pathologists (CAP) and the National Kidney Disease Education Program (NKDEP) collaborated with NIST to develop a new control reference called standard reference material 967 (SRM 967). SRM 967 aims to standardize calibration of creatinine testing, including Jaffe methods. Use of both IDMS and SRM 967 are currently recommended by the National Institutes of Health. == Works == Über den Niederschlag, welchen Pikrinsäre in normalem Harn erzeugt und über eine neue Reaction des Kreatinins by Max Jaffe (1886) == See also == Creatinine — the most commonly ordered clinical test to determine renal function. Otto Folin — developed the Jaffe reaction into its clinical application. == References == == Further reading == A System of Blood Analysis by Folin and Wu (1919) On the determination of creatinine and creatine in urine by Otto Folin (1914) Recommendations for Improving Serum Creatinine Measurement: A Report from the Laboratory Working Group of the National Kidney Disease Education Program by Gary L. Myers et al. (2006) "Max Jaffé (1841–1911)". Nature. 148 (3743): 110. 1941. Bibcode:1941Natur.148T.110.. doi:10.1038/148110d0.
|
{
"page_id": 37425225,
"source": null,
"title": "Jaffe reaction"
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|
Fluorenylmethyloxycarbonyl chloride (Fmoc-Cl) is a chloroformate ester. It is used to introduce the fluorenylmethyloxycarbonyl protecting group as the Fmoc carbamate. == Preparation == This compound may be prepared by reacting 9-fluorenylmethanol with phosgene: == References ==
|
{
"page_id": 14028874,
"source": null,
"title": "Fluorenylmethyloxycarbonyl chloride"
}
|
The Danheiser benzannulation is a chemical reaction used in organic chemistry to generate highly substituted phenols in a single step. It is named after Rick L. Danheiser who developed the reaction. == Annulation == An annulation is defined as a transformation of one or more acyclic precursors resulting in the fusion of a new ring via two newly generated bonds. These strategies can be used to create aromatic systems from acyclic precursors in a single step, with many substituents already in place. A common synthetic annulation reaction is the Robinson annulation. It is a useful reactions for forming six-membered rings and generating polycyclic compounds. It is the combination of the Michael Addition and the Aldol Condensation reaction. == Reaction development == Polysubstituted benzenes were originally synthesized by substitution reactions on aromatic precursors. However, these reactions can have low regioselectivity and are prone to over substitution. Directed ortho metalation requires precursors that are often unstable to metallating reagents. Both these synthetic routes pose issues in total synthesis. In 1984 a new synthetic strategy was developed by Rick Danheiser to address these shortcomings. === Reaction === The Danheiser benzannulation is a regiocontrolled phenol annulation. This annulation provides an efficient route to form an aromatic ring in one step. It is a thermal combination of a substituted cyclobutenones with heterosubstituted acetylenes to produce highly substituted aromatic compounds, specifically phenols or resorcinols (Scheme 1). This benzannulation reaction creates previously unaccessed aromatic substitution patterns. A variety of substituted aromatic rings can be prepared using this method including: phenols, naphthalenes, benzofurans, benzothiophenes, indoles, and carbazoles. The modified Danheiser benzannulation allows the synthesis of polycyclic aromatic and heteroaromatic systems. This also includes naphthalenes, benzofurans and indoles. This second generation aromatic annulation is achieved by irradiation of a solution of acetylene and a vinyl or aryl α-diazo ketone
|
{
"page_id": 44503117,
"source": null,
"title": "Danheiser benzannulation"
}
|
in dichloroethane. This reaction utilizes the photochemical Wolff rearrangement of a diazoketone to generate an aryl or vinylketene. These ketene intermediates cannot be isolated due to their high reactivity to form diketenes. These rearrangements are performed in the presence of unsaturated compounds which undergo [2+2] cycloadditions with the in situ generated ketenes. When ketenes are formed in the presence of alkynes they proceed through pericyclic reactions to generate a substituted aromatic ring (Scheme 2). Avoiding the use of the high energy cyclobutenone starting materials provides access to a wider variety of substituted aromatic compounds. This reaction is quite complementary to the Wulff–Dötz reaction. This is a [2+1] cycloaddition of a carbene to an alkyne or alkene (more specifically in the Dӧtz reaction a carbene coordinated to a metal carbonyl group) to produce substituted aromatic phenols. === Mechanism === The reaction proceeds via a cascade of four subsequent pericyclic reactions (Scheme 3). Heating a cyclobutenone above 80 °C initiates a four-electron electrocyclic cleavage generating a vinyl ketene which reacts with an acetylene in a regiospecific [2+2] cycloaddition (Scheme 4). Reversible electrocyclic cleavage of the 2-vinylcyclobutenone yields a dienylketene. The dienylketene then undergoes a six-electron electrocyclization to give a hexadienone intermediate which rapidly tautomerizes to yield a highly substituted phenol or naphthol structures. In the case of the modified benzannulation reaction (Scheme 5); irradiation of the diazoketones induces the Wolff rearrangement yielding the vinyl ketene intermediate which reacts with the acetylene in a [2+2] cycloaddition then a four-electron cleavage of the resulting 4-substituted cyclobutenone produces a dienylketene which then undergoes a six-electron electrocyclization to give the 2,4-cyclohexanedione which tautomerizes to the final aromatic product. === Reaction conditions === A typical Danheiser benzannulation reaction is run with a 0.4-2.0 M solution of the cyclobutenone in toluene heated at 80-160 °C with a slight
|
{
"page_id": 44503117,
"source": null,
"title": "Danheiser benzannulation"
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|
excess of the cyclobutenone. Upon addition of the alkyne a [2+2] cycloaddition occurs. The crude annulation product is treated with 10% potassium hydroxide in methanol to saponify the ester side product formed from the reaction of the phenolic product with excess vinylketene (Scheme 6). For the second generation reaction starting with the diazoketone, the reaction is performed by irradiation of a 0.7 M solution of the ketone with 1.0-1.2 equivalents of acetylene. A low-pressure mercury-vapor lamp at 254 nm in a photochemical reactor is used for 5–8 hours until all the diazoketone has been consumed as determined by TLC analysis. Dichloromethane, chloroform, and 1,2-dichloroethane, are all appropriate solvents for the annulation reaction. == Reagent Preparations == Cyclobutenone was originally synthesized from the 3-bromocyclobutanone and 3-chlorocyclobutanone precursors which were prepared from an allene and a ketene via two independent routes. Scheme 7 shows the preparation from cyclobutenone from an allene. Activated alkyoxyacetylenes can be synthesized in a single-pot preparation of triisopropylsilyloxyacetylenes from esters. The silyloxyacetylenes are useful substitutes for alkoxyacetylenes in [2 + 2] cycloaddition reactions with ketenes and vinylketenes affording cyclobutenones (Scheme 8). Diazoketones can be synthesized in one-step from readily available ketones or carboxylic acid precursors by the addition of diazomethane to acyl chlorides. A diazo group transfer method can be used to produce α,β-unsaturated ketones. The traditional method of the deformylative diazo transfer approach has been improved upon by substituting the trifluoroacetylation of generated lithium enolates for the Claisen formylation step. The key step in this procedure is activation of the ketone starting material to the corresponding α-trifluoroacetyl derivative using trifluoroethyltrifluoroacetate (TFEA) (Scheme 9). Alkynes or ketenophiles can be synthesized by various methods. Trialkylsilyloxyalkynes have proven to be excellent ketenophiles. These alkynes react in the annulation reaction to form resorcinol monosilyl ethers which can be de-protected under mild
|
{
"page_id": 44503117,
"source": null,
"title": "Danheiser benzannulation"
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reaction conditions. Base-promoted dehydrohalogenation of (Z)-2-halovinyl ethers to form alkoxyacetylenes is one of the most well established routes of alkyne synthesis (Scheme 10). The synthesized alkynes are then heated in benzene or toluene in presence of excess cyclobutenone initiating the benzannulation reaction. Treatment with n-Bu4NF in tetrahydrofuran removes the siloxy groups to form the desired diols. == Scope == Alkynyl ethers and siloxyacetylenes have proven to be the ideal pair for aromatic annulations. The reactions can be run with both activated heterosubstituted alkynes and un-activated acetylenes. Alkynyl thioethers and ynamines have been used as reactants in the annulation reaction. Conjugated enynes have also been used for benzannulation reactions catalyzed by cobalt. This type of benzannulation involves a [4+2] cycloaddition followed by a 1,3-hydrogen shift. In dichloromethane, the symmetrical benzannulation products are yielded but in tetrahydrofuran (THF), unsymmetrical benzannulation products were obtained with good regioselectivity. These reactions utilize 1,3-bis(diphenylphosphino)propane (dppp) substituted cobalt catalyst in the presence of powdered zinc and zinc iodide for a solvent dependent benzannulation reaction (Scheme 11). In dichloromethane the ratio of A:B is 78:22 with an overall combined yield of 90% and in THF the ratio has switched to 7:93 (A:B) with a combined yield of 85%. Palladium-catalyzed benzannulations have been developed using allylic compounds and alkynes. This palladium catalyzed reaction has been performed in both inter- and intramolecular forms. The cationic palladium complex [(η3-C3H5)Pd(CH3CN)2](BF4) reacts with an excess of 4-octyne when heated to 80 °C in the presence of triphenylphosphine forming the aromatic compound 1-methyl-2,3,4,5-tetrapropylbenzene (Scheme 12). It was determined that the presence of exactly one equivalent of palladium catalyst (from which the allyl group adds into the final aromatic structure) is crucial for the catalyzed benzannulation to occur in good yield. This catalyzed reaction was also optimized for allyl substrates with catalytic [Pd2(dba)3]CHCl3 and triphenylphosphine
|
{
"page_id": 44503117,
"source": null,
"title": "Danheiser benzannulation"
}
|
(dba =dibenzylideneacetone) (Scheme 13). == Applications in Total Synthesis == Mycophenolic acid is a Penicillium metabolite that was originally prepared via a key benzannulation step. An alkyne and a cyclobutenone were reacted to form a substituted phenol in a single step in a 73% yield (Scheme 14). Mycophenolic acid was prepared in nine steps in an overall yield of 17-19%. In the synthesis of highly substituted indoles performed by Danheiser, the key step was a benzannulation reaction using cyclobutenone and ynamides to produce highly substituted aniline derivatives. In this case, the ortho position can be functionalized with various substituents. Following the benzannulation reaction with various heterocyclization reactions can provide access to substituted indoles (Scheme 15). Danheiser also used the benzannulation with ynamides for the synthesis of polycyclic benzofused nitrogen heterocycles followed by ring-closing metathesis (Scheme 16) for the total synthesis of (+)-FR900482, an anticancer agent. Kowalski used the benzannulation reaction with siloxyacetylenes for the first time, reacting them with cyclobutenones to synthesize a substituted phenol for the total synthesis of Δ-6-tetrahydrocannabinol (Scheme 17). The benzannulation reaction was used by Smith in the total synthesis of cylindrocyclophanes specifically (−)-Cylindrocyclophane F. He utilized the reaction of a siloxyalkyne and a cyclobutenone to construct the dihydroxyl aromatic intermediate for an olefin metathesis reaction to access the target (Scheme 18). An outstanding application of Danheiser benzannulation in 6-step synthesis of dictyodendrins was demonstrated by Zhang and Ready. They obtained the cyclobutenone substrate using a hetero-[2+2] cycloaddition between aryl ynol ethers (aryl ketene precursors), and the following benzannulation enabled the rapid construction of the carbazole cole of dictyodendrins F, H and I. The successful usage of Danheiser benzannulation allows Zhang and Ready to achieve the so-far shortest synthesis of dictyodendrin natural products. == References ==
|
{
"page_id": 44503117,
"source": null,
"title": "Danheiser benzannulation"
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The resistive ballooning mode (RBM) is an instability occurring in magnetized plasmas, particularly in magnetic confinement devices such as tokamaks, when the pressure gradient is opposite to the effective gravity created by a magnetic field. == Linear growth rate == The linear growth rate γ {\displaystyle \gamma } of the RBM instability is given as γ 2 = − g e f f → ⋅ ∇ p p {\displaystyle \gamma ^{2}=-{\vec {g_{eff}}}\cdot {\frac {\nabla p}{p}}} where | ∇ p | ∼ p L p {\displaystyle |\nabla p|\sim {\frac {p}{L_{p}}}} is the pressure gradient g e f f = c s 2 | ∇ B B | ∼ 1 / R 0 {\displaystyle g_{eff}=c_{s}^{2}|{\frac {\nabla B}{B}}|\sim 1/R_{0}} is the effective gravity produced by a non-homogeneous magnetic field, R0 is the major radius of the device, Lp is a characteristic length of the pressure gradient, and cs is the plasma sound speed. == Similarity with the Rayleigh–Taylor instability == The RBM instability is similar to the Rayleigh–Taylor instability (RT), with Earth gravity g → {\displaystyle {\vec {g}}} replaced by the effective gravity g → e f f {\displaystyle {\vec {g}}_{eff}} , except that for the RT instability, g → {\displaystyle {\vec {g}}} acts on the mass density ρ {\displaystyle \rho } of the fluid, whereas for the RBM instability, g → e f f {\displaystyle {\vec {g}}_{eff}} acts on the pressure p {\displaystyle p} of the plasma.
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{
"page_id": 13307983,
"source": null,
"title": "Resistive ballooning mode"
}
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The word foliaceus is a specific epithet used in the name of several species. Foliaceus is Latin and is used to describe something that is leafy or looks like a leaf. It is applied to plants with large or showy foliage, and to animals with features that resemble leaves (such as the wings of the fly Exilibittacus foliaceus). == Plants == The following list consists of flowering plant species names that include foliaceus. Species are included based on the Royal Botanic Garden Kew's Plants of the World Online. == Marine animals == The following list consists of marine animal species names that include foliaceus. Species are included based on the World Register of Marine Species. == Other animals == The following list consists of animal species names that include foliaceus. Species are included based on the Global Biodiversity Information Facility database. == See also == Foliosa Foliosum Foliosus Foliatus == References ==
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{
"page_id": 76419152,
"source": null,
"title": "Foliaceus"
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Botany, also called plant science, is the branch of natural science and biology studying plants, especially their anatomy, taxonomy, and ecology. A botanist or plant scientist is a scientist who specialises in this field. "Plant" and "botany" may be defined more narrowly to include only land plants and their study, which is also known as phytology. Phytologists or botanists (in the strict sense) study approximately 410,000 species of land plants, including some 391,000 species of vascular plants (of which approximately 369,000 are flowering plants) and approximately 20,000 bryophytes. Botany originated in prehistory as herbalism with the efforts of early humans to identify – and later cultivate – plants that were edible, poisonous, and possibly medicinal, making it one of the first endeavours of human investigation. Medieval physic gardens, often attached to monasteries, contained plants possibly having medicinal benefit. They were forerunners of the first botanical gardens attached to universities, founded from the 1540s onwards. One of the earliest was the Padua botanical garden. These gardens facilitated the academic study of plants. Efforts to catalogue and describe their collections were the beginnings of plant taxonomy and led in 1753 to the binomial system of nomenclature of Carl Linnaeus that remains in use to this day for the naming of all biological species. In the 19th and 20th centuries, new techniques were developed for the study of plants, including methods of optical microscopy and live cell imaging, electron microscopy, analysis of chromosome number, plant chemistry and the structure and function of enzymes and other proteins. In the last two decades of the 20th century, botanists exploited the techniques of molecular genetic analysis, including genomics and proteomics and DNA sequences to classify plants more accurately. Modern botany is a broad subject with contributions and insights from most other areas of science and technology.
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"title": "Botany"
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Research topics include the study of plant structure, growth and differentiation, reproduction, biochemistry and primary metabolism, chemical products, development, diseases, evolutionary relationships, systematics, and plant taxonomy. Dominant themes in 21st-century plant science are molecular genetics and epigenetics, which study the mechanisms and control of gene expression during differentiation of plant cells and tissues. Botanical research has diverse applications in providing staple foods, materials such as timber, oil, rubber, fibre and drugs, in modern horticulture, agriculture and forestry, plant propagation, breeding and genetic modification, in the synthesis of chemicals and raw materials for construction and energy production, in environmental management, and the maintenance of biodiversity. == Etymology == The term "botany" comes from the Ancient Greek word botanē (βοτάνη) meaning "pasture", "herbs" "grass", or "fodder"; Botanē is in turn derived from boskein (Greek: βόσκειν), "to feed" or "to graze". Traditionally, botany has also included the study of fungi and algae by mycologists and phycologists respectively, with the study of these three groups of organisms remaining within the sphere of interest of the International Botanical Congress. == History == === Early botany === Botany originated as herbalism, the study and use of plants for their possible medicinal properties. The early recorded history of botany includes many ancient writings and plant classifications. Examples of early botanical works have been found in ancient texts from India dating back to before 1100 BCE, Ancient Egypt, in archaic Avestan writings, and in works from China purportedly from before 221 BCE. Modern botany traces its roots back to Ancient Greece specifically to Theophrastus (c. 371–287 BCE), a student of Aristotle who invented and described many of its principles and is widely regarded in the scientific community as the "Father of Botany". His major works, Enquiry into Plants and On the Causes of Plants, constitute the most important
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{
"page_id": 4183,
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"title": "Botany"
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contributions to botanical science until the Middle Ages, almost seventeen centuries later. Another work from Ancient Greece that made an early impact on botany is De materia medica, a five-volume encyclopedia about preliminary herbal medicine written in the middle of the first century by Greek physician and pharmacologist Pedanius Dioscorides. De materia medica was widely read for more than 1,500 years. Important contributions from the medieval Muslim world include Ibn Wahshiyya's Nabatean Agriculture, Abū Ḥanīfa Dīnawarī's (828–896) the Book of Plants, and Ibn Bassal's The Classification of Soils. In the early 13th century, Abu al-Abbas al-Nabati, and Ibn al-Baitar (d. 1248) wrote on botany in a systematic and scientific manner. In the mid-16th century, botanical gardens were founded in a number of Italian universities. The Padua botanical garden in 1545 is usually considered to be the first which is still in its original location. These gardens continued the practical value of earlier "physic gardens", often associated with monasteries, in which plants were cultivated for suspected medicinal uses. They supported the growth of botany as an academic subject. Lectures were given about the plants grown in the gardens. Botanical gardens came much later to northern Europe; the first in England was the University of Oxford Botanic Garden in 1621. German physician Leonhart Fuchs (1501–1566) was one of "the three German fathers of botany", along with theologian Otto Brunfels (1489–1534) and physician Hieronymus Bock (1498–1554) (also called Hieronymus Tragus). Fuchs and Brunfels broke away from the tradition of copying earlier works to make original observations of their own. Bock created his own system of plant classification. Physician Valerius Cordus (1515–1544) authored a botanically and pharmacologically important herbal Historia Plantarum in 1544 and a pharmacopoeia of lasting importance, the Dispensatorium in 1546. Naturalist Conrad von Gesner (1516–1565) and herbalist John Gerard (1545 –
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{
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c. 1611) published herbals covering the supposed medicinal uses of plants. Naturalist Ulisse Aldrovandi (1522–1605) was considered the father of natural history, which included the study of plants. In 1665, using an early microscope, Polymath Robert Hooke discovered cells (a term he coined) in cork, and a short time later in living plant tissue. === Early modern botany === During the 18th century, systems of plant identification were developed comparable to dichotomous keys, where unidentified plants are placed into taxonomic groups (e.g. family, genus and species) by making a series of choices between pairs of characters. The choice and sequence of the characters may be artificial in keys designed purely for identification (diagnostic keys) or more closely related to the natural or phyletic order of the taxa in synoptic keys. By the 18th century, new plants for study were arriving in Europe in increasing numbers from newly discovered countries and the European colonies worldwide. In 1753, Carl Linnaeus published his Species Plantarum, a hierarchical classification of plant species that remains the reference point for modern botanical nomenclature. This established a standardised binomial or two-part naming scheme where the first name represented the genus and the second identified the species within the genus. For the purposes of identification, Linnaeus's Systema Sexuale classified plants into 24 groups according to the number of their male sexual organs. The 24th group, Cryptogamia, included all plants with concealed reproductive parts, mosses, liverworts, ferns, algae and fungi. Increasing knowledge of plant anatomy, morphology and life cycles led to the realisation that there were more natural affinities between plants than the artificial sexual system of Linnaeus. Adanson (1763), de Jussieu (1789), and Candolle (1819) all proposed various alternative natural systems of classification that grouped plants using a wider range of shared characters and were widely followed. The
|
{
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Candollean system reflected his ideas of the progression of morphological complexity and the later Bentham & Hooker system, which was influential until the mid-19th century, was influenced by Candolle's approach. Darwin's publication of the Origin of Species in 1859 and his concept of common descent required modifications to the Candollean system to reflect evolutionary relationships as distinct from mere morphological similarity. In the 19th century botany was a socially acceptable hobby for upper-class women. These women would collect and paint flowers and plants from around the world with scientific accuracy. The paintings were used to record many species that could not be transported or maintained in other environments. Marianne North illustrated over 900 species in extreme detail with watercolor and oil paintings. Her work and many other women's botany work was the beginning of popularizing botany to a wider audience. Botany was greatly stimulated by the appearance of the first "modern" textbook, Matthias Schleiden's Grundzüge der Wissenschaftlichen Botanik, published in English in 1849 as Principles of Scientific Botany. Schleiden was a microscopist and an early plant anatomist who co-founded the cell theory with Theodor Schwann and Rudolf Virchow and was among the first to grasp the significance of the cell nucleus that had been described by Robert Brown in 1831. In 1855, Adolf Fick formulated Fick's laws that enabled the calculation of the rates of molecular diffusion in biological systems. === Late modern botany === Building upon the gene-chromosome theory of heredity that originated with Gregor Mendel (1822–1884), August Weismann (1834–1914) proved that inheritance only takes place through gametes. No other cells can pass on inherited characters. The work of Katherine Esau (1898–1997) on plant anatomy is still a major foundation of modern botany. Her books Plant Anatomy and Anatomy of Seed Plants have been key plant structural biology texts
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{
"page_id": 4183,
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for more than half a century. The discipline of plant ecology was pioneered in the late 19th century by botanists such as Eugenius Warming, who produced the hypothesis that plants form communities, and his mentor and successor Christen C. Raunkiær whose system for describing plant life forms is still in use today. The concept that the composition of plant communities such as temperate broadleaf forest changes by a process of ecological succession was developed by Henry Chandler Cowles, Arthur Tansley and Frederic Clements. Clements is credited with the idea of climax vegetation as the most complex vegetation that an environment can support and Tansley introduced the concept of ecosystems to biology. Building on the extensive earlier work of Alphonse de Candolle, Nikolai Vavilov (1887–1943) produced accounts of the biogeography, centres of origin, and evolutionary history of economic plants. Particularly since the mid-1960s there have been advances in understanding of the physics of plant physiological processes such as transpiration (the transport of water within plant tissues), the temperature dependence of rates of water evaporation from the leaf surface and the molecular diffusion of water vapour and carbon dioxide through stomatal apertures. These developments, coupled with new methods for measuring the size of stomatal apertures, and the rate of photosynthesis have enabled precise description of the rates of gas exchange between plants and the atmosphere. Innovations in statistical analysis by Ronald Fisher, Frank Yates and others at Rothamsted Experimental Station facilitated rational experimental design and data analysis in botanical research. The discovery and identification of the auxin plant hormones by Kenneth V. Thimann in 1948 enabled regulation of plant growth by externally applied chemicals. Frederick Campion Steward pioneered techniques of micropropagation and plant tissue culture controlled by plant hormones. The synthetic auxin 2,4-dichlorophenoxyacetic acid or 2,4-D was one of the first commercial
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{
"page_id": 4183,
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"title": "Botany"
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synthetic herbicides. 20th century developments in plant biochemistry have been driven by modern techniques of organic chemical analysis, such as spectroscopy, chromatography and electrophoresis. With the rise of the related molecular-scale biological approaches of molecular biology, genomics, proteomics and metabolomics, the relationship between the plant genome and most aspects of the biochemistry, physiology, morphology and behaviour of plants can be subjected to detailed experimental analysis. The concept originally stated by Gottlieb Haberlandt in 1902 that all plant cells are totipotent and can be grown in vitro ultimately enabled the use of genetic engineering experimentally to knock out a gene or genes responsible for a specific trait, or to add genes such as GFP that report when a gene of interest is being expressed. These technologies enable the biotechnological use of whole plants or plant cell cultures grown in bioreactors to synthesise pesticides, antibiotics or other pharmaceuticals, as well as the practical application of genetically modified crops designed for traits such as improved yield. Modern morphology recognises a continuum between the major morphological categories of root, stem (caulome), leaf (phyllome) and trichome. Furthermore, it emphasises structural dynamics. Modern systematics aims to reflect and discover phylogenetic relationships between plants. Modern molecular phylogenetics largely ignores morphological characters, relying on DNA sequences as data. Molecular analysis of DNA sequences from most families of flowering plants enabled the Angiosperm Phylogeny Group to publish in 1998 a phylogeny of flowering plants, answering many of the questions about relationships among angiosperm families and species. The theoretical possibility of a practical method for identification of plant species and commercial varieties by DNA barcoding is the subject of active current research. == Branches of botany == Botany is divided along several axes. Some subfields of botany relate to particular groups of organisms. Divisions related to the broader historical sense
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{
"page_id": 4183,
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of botany include bacteriology, mycology (or fungology), and phycology – respectively, the study of bacteria, fungi, and algae – with lichenology as a subfield of mycology. The narrower sense of botany as the study of embryophytes (land plants) is called phytology. Bryology is the study of mosses (and in the broader sense also liverworts and hornworts). Pteridology (or filicology) is the study of ferns and allied plants. A number of other taxa of ranks varying from family to subgenus have terms for their study, including agrostology (or graminology) for the study of grasses, synantherology for the study of composites, and batology for the study of brambles. Study can also be divided by guild rather than clade or grade. For example, dendrology is the study of woody plants. Many divisions of biology have botanical subfields. These are commonly denoted by prefixing the word plant (e.g. plant taxonomy, plant ecology, plant anatomy, plant morphology, plant systematics), or prefixing or substituting the prefix phyto- (e.g. phytochemistry, phytogeography). The study of fossil plants is called palaeobotany. Other fields are denoted by adding or substituting the word botany (e.g. systematic botany). Phytosociology is a subfield of plant ecology that classifies and studies communities of plants. The intersection of fields from the above pair of categories gives rise to fields such as bryogeography, the study of the distribution of mosses. Different parts of plants also give rise to their own subfields, including xylology, carpology (or fructology), and palynology, these being the study of wood, fruit and pollen/spores respectively. Botany also overlaps on the one hand with agriculture, horticulture and silviculture, and on the other hand with medicine and pharmacology, giving rise to fields such as agronomy, horticultural botany, phytopathology, and phytopharmacology. == Scope and importance == The study of plants is vital because they underpin almost
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{
"page_id": 4183,
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"title": "Botany"
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all animal life on Earth by generating a large proportion of the oxygen and food that provide humans and other organisms with aerobic respiration with the chemical energy they need to exist. Plants, algae and cyanobacteria are the major groups of organisms that carry out photosynthesis, a process that uses the energy of sunlight to convert water and carbon dioxide into sugars that can be used both as a source of chemical energy and of organic molecules that are used in the structural components of cells. As a by-product of photosynthesis, plants release oxygen into the atmosphere, a gas that is required by nearly all living things to carry out cellular respiration. In addition, they are influential in the global carbon and water cycles and plant roots bind and stabilise soils, preventing soil erosion. Plants are crucial to the future of human society as they provide food, oxygen, biochemicals, and products for people, as well as creating and preserving soil. Historically, all living things were classified as either animals or plants and botany covered the study of all organisms not considered animals. Botanists examine both the internal functions and processes within plant organelles, cells, tissues, whole plants, plant populations and plant communities. At each of these levels, a botanist may be concerned with the classification (taxonomy), phylogeny and evolution, structure (anatomy and morphology), or function (physiology) of plant life. The strictest definition of "plant" includes only the "land plants" or embryophytes, which include seed plants (gymnosperms, including the pines, and flowering plants) and the free-sporing cryptogams including ferns, clubmosses, liverworts, hornworts and mosses. Embryophytes are multicellular eukaryotes descended from an ancestor that obtained its energy from sunlight by photosynthesis. They have life cycles with alternating haploid and diploid phases. The sexual haploid phase of embryophytes, known as the gametophyte, nurtures
|
{
"page_id": 4183,
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the developing diploid embryo sporophyte within its tissues for at least part of its life, even in the seed plants, where the gametophyte itself is nurtured by its parent sporophyte. Other groups of organisms that were previously studied by botanists include bacteria (now studied in bacteriology), fungi (mycology) – including lichen-forming fungi (lichenology), non-chlorophyte algae (phycology), and viruses (virology). However, attention is still given to these groups by botanists, and fungi (including lichens) and photosynthetic protists are usually covered in introductory botany courses. Palaeobotanists study ancient plants in the fossil record to provide information about the evolutionary history of plants. Cyanobacteria, the first oxygen-releasing photosynthetic organisms on Earth, are thought to have given rise to the ancestor of plants by entering into an endosymbiotic relationship with an early eukaryote, ultimately becoming the chloroplasts in plant cells. The new photosynthetic plants (along with their algal relatives) accelerated the rise in atmospheric oxygen started by the cyanobacteria, changing the ancient oxygen-free, reducing, atmosphere to one in which free oxygen has been abundant for more than 2 billion years. Among the important botanical questions of the 21st century are the role of plants as primary producers in the global cycling of life's basic ingredients: energy, carbon, oxygen, nitrogen and water, and ways that our plant stewardship can help address the global environmental issues of resource management, conservation, human food security, biologically invasive organisms, carbon sequestration, climate change, and sustainability. === Human nutrition === Virtually all staple foods come either directly from primary production by plants, or indirectly from animals that eat them. Plants and other photosynthetic organisms are at the base of most food chains because they use the energy from the sun and nutrients from the soil and atmosphere, converting them into a form that can be used by animals. This is
|
{
"page_id": 4183,
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"title": "Botany"
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what ecologists call the first trophic level. The modern forms of the major staple foods, such as hemp, teff, maize, rice, wheat and other cereal grasses, pulses, bananas and plantains, as well as hemp, flax and cotton grown for their fibres, are the outcome of prehistoric selection over thousands of years from among wild ancestral plants with the most desirable characteristics. Botanists study how plants produce food and how to increase yields, for example through plant breeding, making their work important to humanity's ability to feed the world and provide food security for future generations. Botanists also study weeds, which are a considerable problem in agriculture, and the biology and control of plant pathogens in agriculture and natural ecosystems. Ethnobotany is the study of the relationships between plants and people. When applied to the investigation of historical plant–people relationships ethnobotany may be referred to as archaeobotany or palaeoethnobotany. Some of the earliest plant-people relationships arose between the indigenous people of Canada in identifying edible plants from inedible plants. This relationship the indigenous people had with plants was recorded by ethnobotanists. == Plant biochemistry == Plant biochemistry is the study of the chemical processes used by plants. Some of these processes are used in their primary metabolism like the photosynthetic Calvin cycle and crassulacean acid metabolism. Others make specialised materials like the cellulose and lignin used to build their bodies, and secondary products like resins and aroma compounds. Plants and various other groups of photosynthetic eukaryotes collectively known as "algae" have unique organelles known as chloroplasts. Chloroplasts are thought to be descended from cyanobacteria that formed endosymbiotic relationships with ancient plant and algal ancestors. Chloroplasts and cyanobacteria contain the blue-green pigment chlorophyll a. Chlorophyll a (as well as its plant and green algal-specific cousin chlorophyll b) absorbs light in the blue-violet
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{
"page_id": 4183,
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and orange/red parts of the spectrum while reflecting and transmitting the green light that we see as the characteristic colour of these organisms. The energy in the red and blue light that these pigments absorb is used by chloroplasts to make energy-rich carbon compounds from carbon dioxide and water by oxygenic photosynthesis, a process that generates molecular oxygen (O2) as a by-product. The light energy captured by chlorophyll a is initially in the form of electrons (and later a proton gradient) that is used to make molecules of ATP and NADPH which temporarily store and transport energy. Their energy is used in the light-independent reactions of the Calvin cycle by the enzyme rubisco to produce molecules of the 3-carbon sugar glyceraldehyde 3-phosphate (G3P). Glyceraldehyde 3-phosphate is the first product of photosynthesis and the raw material from which glucose and almost all other organic molecules of biological origin are synthesised. Some of the glucose is converted to starch which is stored in the chloroplast. Starch is the characteristic energy store of most land plants and algae, while inulin, a polymer of fructose is used for the same purpose in the sunflower family Asteraceae. Some of the glucose is converted to sucrose (common table sugar) for export to the rest of the plant. Unlike in animals (which lack chloroplasts), plants and their eukaryote relatives have delegated many biochemical roles to their chloroplasts, including synthesising all their fatty acids, and most amino acids. The fatty acids that chloroplasts make are used for many things, such as providing material to build cell membranes out of and making the polymer cutin which is found in the plant cuticle that protects land plants from drying out. Plants synthesise a number of unique polymers like the polysaccharide molecules cellulose, pectin and xyloglucan from which the land plant
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{
"page_id": 4183,
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cell wall is constructed. Vascular land plants make lignin, a polymer used to strengthen the secondary cell walls of xylem tracheids and vessels to keep them from collapsing when a plant sucks water through them under water stress. Lignin is also used in other cell types like sclerenchyma fibres that provide structural support for a plant and is a major constituent of wood. Sporopollenin is a chemically resistant polymer found in the outer cell walls of spores and pollen of land plants responsible for the survival of early land plant spores and the pollen of seed plants in the fossil record. It is widely regarded as a marker for the start of land plant evolution during the Ordovician period. The concentration of carbon dioxide in the atmosphere today is much lower than it was when plants emerged onto land during the Ordovician and Silurian periods. Many monocots like maize and the pineapple and some dicots like the Asteraceae have since independently evolved pathways like Crassulacean acid metabolism and the C4 carbon fixation pathway for photosynthesis which avoid the losses resulting from photorespiration in the more common C3 carbon fixation pathway. These biochemical strategies are unique to land plants. === Medicine and materials === Phytochemistry is a branch of plant biochemistry primarily concerned with the chemical substances produced by plants during secondary metabolism. Some of these compounds are toxins such as the alkaloid coniine from hemlock. Others, such as the essential oils peppermint oil and lemon oil are useful for their aroma, as flavourings and spices (e.g., capsaicin), and in medicine as pharmaceuticals as in opium from opium poppies. Many medicinal and recreational drugs, such as tetrahydrocannabinol (active ingredient in cannabis), caffeine, morphine and nicotine come directly from plants. Others are simple derivatives of botanical natural products. For example, the pain
|
{
"page_id": 4183,
"source": null,
"title": "Botany"
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killer aspirin is the acetyl ester of salicylic acid, originally isolated from the bark of willow trees, and a wide range of opiate painkillers like heroin are obtained by chemical modification of morphine obtained from the opium poppy. Popular stimulants come from plants, such as caffeine from coffee, tea and chocolate, and nicotine from tobacco. Most alcoholic beverages come from fermentation of carbohydrate-rich plant products such as barley (beer), rice (sake) and grapes (wine). Native Americans have used various plants as ways of treating illness or disease for thousands of years. This knowledge Native Americans have on plants has been recorded by enthnobotanists and then in turn has been used by pharmaceutical companies as a way of drug discovery. Plants can synthesise coloured dyes and pigments such as the anthocyanins responsible for the red colour of red wine, yellow weld and blue woad used together to produce Lincoln green, indoxyl, source of the blue dye indigo traditionally used to dye denim and the artist's pigments gamboge and rose madder. Sugar, starch, cotton, linen, hemp, some types of rope, wood and particle boards, papyrus and paper, vegetable oils, wax, and natural rubber are examples of commercially important materials made from plant tissues or their secondary products. Charcoal, a pure form of carbon made by pyrolysis of wood, has a long history as a metal-smelting fuel, as a filter material and adsorbent and as an artist's material and is one of the three ingredients of gunpowder. Cellulose, the world's most abundant organic polymer, can be converted into energy, fuels, materials and chemical feedstock. Products made from cellulose include rayon and cellophane, wallpaper paste, biobutanol and gun cotton. Sugarcane, rapeseed and soy are some of the plants with a highly fermentable sugar or oil content that are used as sources of biofuels, important
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{
"page_id": 4183,
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alternatives to fossil fuels, such as biodiesel. Sweetgrass was used by Native Americans to ward off bugs like mosquitoes. These bug repelling properties of sweetgrass were later found by the American Chemical Society in the molecules phytol and coumarin. == Plant ecology == Plant ecology is the science of the functional relationships between plants and their habitats – the environments where they complete their life cycles. Plant ecologists study the composition of local and regional floras, their biodiversity, genetic diversity and fitness, the adaptation of plants to their environment, and their competitive or mutualistic interactions with other species. Some ecologists even rely on empirical data from indigenous people that is gathered by ethnobotanists. This information can relay a great deal of information on how the land once was thousands of years ago and how it has changed over that time. The goals of plant ecology are to understand the causes of their distribution patterns, productivity, environmental impact, evolution, and responses to environmental change. Plants depend on certain edaphic (soil) and climatic factors in their environment but can modify these factors too. For example, they can change their environment's albedo, increase runoff interception, stabilise mineral soils and develop their organic content, and affect local temperature. Plants compete with other organisms in their ecosystem for resources. They interact with their neighbours at a variety of spatial scales in groups, populations and communities that collectively constitute vegetation. Regions with characteristic vegetation types and dominant plants as well as similar abiotic and biotic factors, climate, and geography make up biomes like tundra or tropical rainforest. Herbivores eat plants, but plants can defend themselves and some species are parasitic or even carnivorous. Other organisms form mutually beneficial relationships with plants. For example, mycorrhizal fungi and rhizobia provide plants with nutrients in exchange for food, ants
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are recruited by ant plants to provide protection, honey bees, bats and other animals pollinate flowers and humans and other animals act as dispersal vectors to spread spores and seeds. === Plants, climate and environmental change === Plant responses to climate and other environmental changes can inform our understanding of how these changes affect ecosystem function and productivity. For example, plant phenology can be a useful proxy for temperature in historical climatology, and the biological impact of climate change and global warming. Palynology, the analysis of fossil pollen deposits in sediments from thousands or millions of years ago allows the reconstruction of past climates. Estimates of atmospheric CO2 concentrations since the Palaeozoic have been obtained from stomatal densities and the leaf shapes and sizes of ancient land plants. Ozone depletion can expose plants to higher levels of ultraviolet radiation-B (UV-B), resulting in lower growth rates. Moreover, information from studies of community ecology, plant systematics, and taxonomy is essential to understanding vegetation change, habitat destruction and species extinction. == Genetics == Inheritance in plants follows the same fundamental principles of genetics as in other multicellular organisms. Gregor Mendel discovered the genetic laws of inheritance by studying inherited traits such as shape in Pisum sativum (peas). What Mendel learned from studying plants has had far-reaching benefits outside of botany. Similarly, "jumping genes" were discovered by Barbara McClintock while she was studying maize. Nevertheless, there are some distinctive genetic differences between plants and other organisms. Species boundaries in plants may be weaker than in animals, and cross species hybrids are often possible. A familiar example is peppermint, Mentha × piperita, a sterile hybrid between Mentha aquatica and spearmint, Mentha spicata. The many cultivated varieties of wheat are the result of multiple inter- and intra-specific crosses between wild species and their hybrids. Angiosperms with
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monoecious flowers often have self-incompatibility mechanisms that operate between the pollen and stigma so that the pollen either fails to reach the stigma or fails to germinate and produce male gametes. This is one of several methods used by plants to promote outcrossing. In many land plants the male and female gametes are produced by separate individuals. These species are said to be dioecious when referring to vascular plant sporophytes and dioicous when referring to bryophyte gametophytes. Charles Darwin in his 1878 book The Effects of Cross and Self-Fertilization in the Vegetable Kingdom at the start of chapter XII noted "The first and most important of the conclusions which may be drawn from the observations given in this volume, is that generally cross-fertilisation is beneficial and self-fertilisation often injurious, at least with the plants on which I experimented." An important adaptive benefit of outcrossing is that it allows the masking of deleterious mutations in the genome of progeny. This beneficial effect is also known as hybrid vigor or heterosis. Once outcrossing is established, subsequent switching to inbreeding becomes disadvantageous since it allows expression of the previously masked deleterious recessive mutations, commonly referred to as inbreeding depression. Unlike in higher animals, where parthenogenesis is rare, asexual reproduction may occur in plants by several different mechanisms. The formation of stem tubers in potato is one example. Particularly in arctic or alpine habitats, where opportunities for fertilisation of flowers by animals are rare, plantlets or bulbs, may develop instead of flowers, replacing sexual reproduction with asexual reproduction and giving rise to clonal populations genetically identical to the parent. This is one of several types of apomixis that occur in plants. Apomixis can also happen in a seed, producing a seed that contains an embryo genetically identical to the parent. Most sexually reproducing organisms
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"page_id": 4183,
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are diploid, with paired chromosomes, but doubling of their chromosome number may occur due to errors in cytokinesis. This can occur early in development to produce an autopolyploid or partly autopolyploid organism, or during normal processes of cellular differentiation to produce some cell types that are polyploid (endopolyploidy), or during gamete formation. An allopolyploid plant may result from a hybridisation event between two different species. Both autopolyploid and allopolyploid plants can often reproduce normally, but may be unable to cross-breed successfully with the parent population because there is a mismatch in chromosome numbers. These plants that are reproductively isolated from the parent species but live within the same geographical area, may be sufficiently successful to form a new species. Some otherwise sterile plant polyploids can still reproduce vegetatively or by seed apomixis, forming clonal populations of identical individuals. Durum wheat is a fertile tetraploid allopolyploid, while bread wheat is a fertile hexaploid. The commercial banana is an example of a sterile, seedless triploid hybrid. Common dandelion is a triploid that produces viable seeds by apomictic seed. As in other eukaryotes, the inheritance of endosymbiotic organelles like mitochondria and chloroplasts in plants is non-Mendelian. Chloroplasts are inherited through the male parent in gymnosperms but often through the female parent in flowering plants. === Molecular genetics === A considerable amount of new knowledge about plant function comes from studies of the molecular genetics of model plants such as the Thale cress, Arabidopsis thaliana, a weedy species in the mustard family (Brassicaceae). The genome or hereditary information contained in the genes of this species is encoded by about 135 million base pairs of DNA, forming one of the smallest genomes among flowering plants. Arabidopsis was the first plant to have its genome sequenced, in 2000. The sequencing of some other relatively small genomes,
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{
"page_id": 4183,
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of rice (Oryza sativa) and Brachypodium distachyon, has made them important model species for understanding the genetics, cellular and molecular biology of cereals, grasses and monocots generally. Model plants such as Arabidopsis thaliana are used for studying the molecular biology of plant cells and the chloroplast. Ideally, these organisms have small genomes that are well known or completely sequenced, small stature and short generation times. Corn has been used to study mechanisms of photosynthesis and phloem loading of sugar in C4 plants. The single celled green alga Chlamydomonas reinhardtii, while not an embryophyte itself, contains a green-pigmented chloroplast related to that of land plants, making it useful for study. A red alga Cyanidioschyzon merolae has also been used to study some basic chloroplast functions. Spinach, peas, soybeans and a moss Physcomitrella patens are commonly used to study plant cell biology. Agrobacterium tumefaciens, a soil rhizosphere bacterium, can attach to plant cells and infect them with a callus-inducing Ti plasmid by horizontal gene transfer, causing a callus infection called crown gall disease. Schell and Van Montagu (1977) hypothesised that the Ti plasmid could be a natural vector for introducing the Nif gene responsible for nitrogen fixation in the root nodules of legumes and other plant species. Today, genetic modification of the Ti plasmid is one of the main techniques for introduction of transgenes to plants and the creation of genetically modified crops. === Epigenetics === Epigenetics is the study of heritable changes in gene function that cannot be explained by changes in the underlying DNA sequence but cause the organism's genes to behave (or "express themselves") differently. One example of epigenetic change is the marking of the genes by DNA methylation which determines whether they will be expressed or not. Gene expression can also be controlled by repressor proteins that attach
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{
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to silencer regions of the DNA and prevent that region of the DNA code from being expressed. Epigenetic marks may be added or removed from the DNA during programmed stages of development of the plant, and are responsible, for example, for the differences between anthers, petals and normal leaves, despite the fact that they all have the same underlying genetic code. Epigenetic changes may be temporary or may remain through successive cell divisions for the remainder of the cell's life. Some epigenetic changes have been shown to be heritable, while others are reset in the germ cells. Epigenetic changes in eukaryotic biology serve to regulate the process of cellular differentiation. During morphogenesis, totipotent stem cells become the various pluripotent cell lines of the embryo, which in turn become fully differentiated cells. A single fertilised egg cell, the zygote, gives rise to the many different plant cell types including parenchyma, xylem vessel elements, phloem sieve tubes, guard cells of the epidermis, etc. as it continues to divide. The process results from the epigenetic activation of some genes and inhibition of others. Unlike animals, many plant cells, particularly those of the parenchyma, do not terminally differentiate, remaining totipotent with the ability to give rise to a new individual plant. Exceptions include highly lignified cells, the sclerenchyma and xylem which are dead at maturity, and the phloem sieve tubes which lack nuclei. While plants use many of the same epigenetic mechanisms as animals, such as chromatin remodelling, an alternative hypothesis is that plants set their gene expression patterns using positional information from the environment and surrounding cells to determine their developmental fate. Epigenetic changes can lead to paramutations, which do not follow the Mendelian heritage rules. These epigenetic marks are carried from one generation to the next, with one allele inducing a change
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on the other. == Plant evolution == The chloroplasts of plants have a number of biochemical, structural and genetic similarities to cyanobacteria, (commonly but incorrectly known as "blue-green algae") and are thought to be derived from an ancient endosymbiotic relationship between an ancestral eukaryotic cell and a cyanobacterial resident. The algae are a polyphyletic group and are placed in various divisions, some more closely related to plants than others. There are many differences between them in features such as cell wall composition, biochemistry, pigmentation, chloroplast structure and nutrient reserves. The algal division Charophyta, sister to the green algal division Chlorophyta, is considered to contain the ancestor of true plants. The Charophyte class Charophyceae and the land plant sub-kingdom Embryophyta together form the monophyletic group or clade Streptophytina. Nonvascular land plants are embryophytes that lack the vascular tissues xylem and phloem. They include mosses, liverworts and hornworts. Pteridophytic vascular plants with true xylem and phloem that reproduced by spores germinating into free-living gametophytes evolved during the Silurian period and diversified into several lineages during the late Silurian and early Devonian. Representatives of the lycopods have survived to the present day. By the end of the Devonian period, several groups, including the lycopods, sphenophylls and progymnosperms, had independently evolved "megaspory" – their spores were of two distinct sizes, larger megaspores and smaller microspores. Their reduced gametophytes developed from megaspores retained within the spore-producing organs (megasporangia) of the sporophyte, a condition known as endospory. Seeds consist of an endosporic megasporangium surrounded by one or two sheathing layers (integuments). The young sporophyte develops within the seed, which on germination splits to release it. The earliest known seed plants date from the latest Devonian Famennian stage. Following the evolution of the seed habit, seed plants diversified, giving rise to a number of now-extinct groups, including
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seed ferns, as well as the modern gymnosperms and angiosperms. Gymnosperms produce "naked seeds" not fully enclosed in an ovary; modern representatives include conifers, cycads, Ginkgo, and Gnetales. Angiosperms produce seeds enclosed in a structure such as a carpel or an ovary. Ongoing research on the molecular phylogenetics of living plants appears to show that the angiosperms are a sister clade to the gymnosperms. == Plant physiology == Plant physiology encompasses all the internal chemical and physical activities of plants associated with life. Chemicals obtained from the air, soil and water form the basis of all plant metabolism. The energy of sunlight, captured by oxygenic photosynthesis and released by cellular respiration, is the basis of almost all life. Photoautotrophs, including all green plants, algae and cyanobacteria gather energy directly from sunlight by photosynthesis. Heterotrophs including all animals, all fungi, all completely parasitic plants, and non-photosynthetic bacteria take in organic molecules produced by photoautotrophs and respire them or use them in the construction of cells and tissues. Respiration is the oxidation of carbon compounds by breaking them down into simpler structures to release the energy they contain, essentially the opposite of photosynthesis. Molecules are moved within plants by transport processes that operate at a variety of spatial scales. Subcellular transport of ions, electrons and molecules such as water and enzymes occurs across cell membranes. Minerals and water are transported from roots to other parts of the plant in the transpiration stream. Diffusion, osmosis, and active transport and mass flow are all different ways transport can occur. Examples of elements that plants need to transport are nitrogen, phosphorus, potassium, calcium, magnesium, and sulfur. In vascular plants, these elements are extracted from the soil as soluble ions by the roots and transported throughout the plant in the xylem. Most of the elements required
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{
"page_id": 4183,
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for plant nutrition come from the chemical breakdown of soil minerals. Sucrose produced by photosynthesis is transported from the leaves to other parts of the plant in the phloem and plant hormones are transported by a variety of processes. === Plant hormones === Plants are not passive, but respond to external signals such as light, touch, and injury by moving or growing towards or away from the stimulus, as appropriate. Tangible evidence of touch sensitivity is the almost instantaneous collapse of leaflets of Mimosa pudica, the insect traps of Venus flytrap and bladderworts, and the pollinia of orchids. The hypothesis that plant growth and development is coordinated by plant hormones or plant growth regulators first emerged in the late 19th century. Darwin experimented on the movements of plant shoots and roots towards light and gravity, and concluded "It is hardly an exaggeration to say that the tip of the radicle . . acts like the brain of one of the lower animals . . directing the several movements". About the same time, the role of auxins (from the Greek auxein, to grow) in control of plant growth was first outlined by the Dutch scientist Frits Went. The first known auxin, indole-3-acetic acid (IAA), which promotes cell growth, was only isolated from plants about 50 years later. This compound mediates the tropic responses of shoots and roots towards light and gravity. The finding in 1939 that plant callus could be maintained in culture containing IAA, followed by the observation in 1947 that it could be induced to form roots and shoots by controlling the concentration of growth hormones were key steps in the development of plant biotechnology and genetic modification. Cytokinins are a class of plant hormones named for their control of cell division (especially cytokinesis). The natural cytokinin zeatin was
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{
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discovered in corn, Zea mays, and is a derivative of the purine adenine. Zeatin is produced in roots and transported to shoots in the xylem where it promotes cell division, bud development, and the greening of chloroplasts. The gibberelins, such as gibberelic acid are diterpenes synthesised from acetyl CoA via the mevalonate pathway. They are involved in the promotion of germination and dormancy-breaking in seeds, in regulation of plant height by controlling stem elongation and the control of flowering. Abscisic acid (ABA) occurs in all land plants except liverworts, and is synthesised from carotenoids in the chloroplasts and other plastids. It inhibits cell division, promotes seed maturation, and dormancy, and promotes stomatal closure. It was so named because it was originally thought to control abscission. Ethylene is a gaseous hormone that is produced in all higher plant tissues from methionine. It is now known to be the hormone that stimulates or regulates fruit ripening and abscission, and it, or the synthetic growth regulator ethephon which is rapidly metabolised to produce ethylene, are used on industrial scale to promote ripening of cotton, pineapples and other climacteric crops. Another class of phytohormones is the jasmonates, first isolated from the oil of Jasminum grandiflorum which regulates wound responses in plants by unblocking the expression of genes required in the systemic acquired resistance response to pathogen attack. In addition to being the primary energy source for plants, light functions as a signalling device, providing information to the plant, such as how much sunlight the plant receives each day. This can result in adaptive changes in a process known as photomorphogenesis. Phytochromes are the photoreceptors in a plant that are sensitive to light. == Plant anatomy and morphology == Plant anatomy is the study of the structure of plant cells and tissues, whereas plant morphology
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{
"page_id": 4183,
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is the study of their external form. All plants are multicellular eukaryotes, their DNA stored in nuclei. The characteristic features of plant cells that distinguish them from those of animals and fungi include a primary cell wall composed of the polysaccharides cellulose, hemicellulose and pectin, larger vacuoles than in animal cells and the presence of plastids with unique photosynthetic and biosynthetic functions as in the chloroplasts. Other plastids contain storage products such as starch (amyloplasts) or lipids (elaioplasts). Uniquely, streptophyte cells and those of the green algal order Trentepohliales divide by construction of a phragmoplast as a template for building a cell plate late in cell division. The bodies of vascular plants including clubmosses, ferns and seed plants (gymnosperms and angiosperms) generally have aerial and subterranean subsystems. The shoots consist of stems bearing green photosynthesising leaves and reproductive structures. The underground vascularised roots bear root hairs at their tips and generally lack chlorophyll. Non-vascular plants, the liverworts, hornworts and mosses do not produce ground-penetrating vascular roots and most of the plant participates in photosynthesis. The sporophyte generation is nonphotosynthetic in liverworts but may be able to contribute part of its energy needs by photosynthesis in mosses and hornworts. The root system and the shoot system are interdependent – the usually nonphotosynthetic root system depends on the shoot system for food, and the usually photosynthetic shoot system depends on water and minerals from the root system. Cells in each system are capable of creating cells of the other and producing adventitious shoots or roots. Stolons and tubers are examples of shoots that can grow roots. Roots that spread out close to the surface, such as those of willows, can produce shoots and ultimately new plants. In the event that one of the systems is lost, the other can often regrow it.
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"page_id": 4183,
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In fact it is possible to grow an entire plant from a single leaf, as is the case with plants in Streptocarpus sect. Saintpaulia, or even a single cell – which can dedifferentiate into a callus (a mass of unspecialised cells) that can grow into a new plant. In vascular plants, the xylem and phloem are the conductive tissues that transport resources between shoots and roots. Roots are often adapted to store food such as sugars or starch, as in sugar beets and carrots. Stems mainly provide support to the leaves and reproductive structures, but can store water in succulent plants such as cacti, food as in potato tubers, or reproduce vegetatively as in the stolons of strawberry plants or in the process of layering. Leaves gather sunlight and carry out photosynthesis. Large, flat, flexible, green leaves are called foliage leaves. Gymnosperms, such as conifers, cycads, Ginkgo, and gnetophytes are seed-producing plants with open seeds. Angiosperms are seed-producing plants that produce flowers and have enclosed seeds. Woody plants, such as azaleas and oaks, undergo a secondary growth phase resulting in two additional types of tissues: wood (secondary xylem) and bark (secondary phloem and cork). All gymnosperms and many angiosperms are woody plants. Some plants reproduce sexually, some asexually, and some via both means. Although reference to major morphological categories such as root, stem, leaf, and trichome are useful, one has to keep in mind that these categories are linked through intermediate forms so that a continuum between the categories results. Furthermore, structures can be seen as processes, that is, process combinations. == Systematic botany == Systematic botany is part of systematic biology, which is concerned with the range and diversity of organisms and their relationships, particularly as determined by their evolutionary history. It involves, or is related to, biological classification,
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{
"page_id": 4183,
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scientific taxonomy and phylogenetics. Biological classification is the method by which botanists group organisms into categories such as genera or species. Biological classification is a form of scientific taxonomy. Modern taxonomy is rooted in the work of Carl Linnaeus, who grouped species according to shared physical characteristics. These groupings have since been revised to align better with the Darwinian principle of common descent – grouping organisms by ancestry rather than superficial characteristics. While scientists do not always agree on how to classify organisms, molecular phylogenetics, which uses DNA sequences as data, has driven many recent revisions along evolutionary lines and is likely to continue to do so. The dominant classification system is called Linnaean taxonomy. It includes ranks and binomial nomenclature. The nomenclature of botanical organisms is codified in the International Code of Nomenclature for algae, fungi, and plants (ICN) and administered by the International Botanical Congress. Kingdom Plantae belongs to Domain Eukaryota and is broken down recursively until each species is separately classified. The order is: Kingdom; Phylum (or Division); Class; Order; Family; Genus (plural genera); Species. The scientific name of a plant represents its genus and its species within the genus, resulting in a single worldwide name for each organism. For example, the tiger lily is Lilium columbianum. Lilium is the genus, and columbianum the specific epithet. The combination is the name of the species. When writing the scientific name of an organism, it is proper to capitalise the first letter in the genus and put all of the specific epithet in lowercase. Additionally, the entire term is ordinarily italicised (or underlined when italics are not available). The evolutionary relationships and heredity of a group of organisms is called its phylogeny. Phylogenetic studies attempt to discover phylogenies. The basic approach is to use similarities based on shared inheritance
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"page_id": 4183,
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to determine relationships. As an example, species of Pereskia are trees or bushes with prominent leaves. They do not obviously resemble a typical leafless cactus such as an Echinocactus. However, both Pereskia and Echinocactus have spines produced from areoles (highly specialised pad-like structures) suggesting that the two genera are indeed related. Judging relationships based on shared characters requires care, since plants may resemble one another through convergent evolution in which characters have arisen independently. Some euphorbias have leafless, rounded bodies adapted to water conservation similar to those of globular cacti, but characters such as the structure of their flowers make it clear that the two groups are not closely related. The cladistic method takes a systematic approach to characters, distinguishing between those that carry no information about shared evolutionary history – such as those evolved separately in different groups (homoplasies) or those left over from ancestors (plesiomorphies) – and derived characters, which have been passed down from innovations in a shared ancestor (apomorphies). Only derived characters, such as the spine-producing areoles of cacti, provide evidence for descent from a common ancestor. The results of cladistic analyses are expressed as cladograms: tree-like diagrams showing the pattern of evolutionary branching and descent. From the 1990s onwards, the predominant approach to constructing phylogenies for living plants has been molecular phylogenetics, which uses molecular characters, particularly DNA sequences, rather than morphological characters like the presence or absence of spines and areoles. The difference is that the genetic code itself is used to decide evolutionary relationships, instead of being used indirectly via the characters it gives rise to. Clive Stace describes this as having "direct access to the genetic basis of evolution." As a simple example, prior to the use of genetic evidence, fungi were thought either to be plants or to be more closely
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{
"page_id": 4183,
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related to plants than animals. Genetic evidence suggests that the true evolutionary relationship of multicelled organisms is as shown in the cladogram below – fungi are more closely related to animals than to plants. In 1998, the Angiosperm Phylogeny Group published a phylogeny for flowering plants based on an analysis of DNA sequences from most families of flowering plants. As a result of this work, many questions, such as which families represent the earliest branches of angiosperms, have now been answered. Investigating how plant species are related to each other allows botanists to better understand the process of evolution in plants. Despite the study of model plants and increasing use of DNA evidence, there is ongoing work and discussion among taxonomists about how best to classify plants into various taxa. Technological developments such as computers and electron microscopes have greatly increased the level of detail studied and speed at which data can be analysed. == Symbols == A few symbols are in current use in botany. A number of others are obsolete; for example, Linnaeus used planetary symbols ⟨♂⟩ (Mars) for biennial plants, ⟨♃⟩ (Jupiter) for herbaceous perennials and ⟨♄⟩ (Saturn) for woody perennials, based on the planets' orbital periods of 2, 12 and 30 years; and Willd used ⟨♄⟩ (Saturn) for neuter in addition to ⟨☿⟩ (Mercury) for hermaphroditic. The following symbols are still used: == See also == == Notes == == References == === Citations === === Sources === == External links == Media related to Botany at Wikimedia Commons
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The molecular formula C14H15NO (molar mass: 213.27 g/mol, exact mass: 213.115364 u) may refer to: 1-Naphthylmethcathinone 2-Naphthylmethcathinone Naphthylmorpholine
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Bohrium is a synthetic chemical element; it has symbol Bh and atomic number 107. It is named after Danish physicist Niels Bohr. As a synthetic element, it can be created in particle accelerators but is not found in nature. All known isotopes of bohrium are highly radioactive; the most stable known isotope is 270Bh with a half-life of approximately 2.4 minutes, though the unconfirmed 278Bh may have a longer half-life of about 11.5 minutes. In the periodic table, it is a d-block transactinide element. It is a member of the 7th period and belongs to the group 7 elements as the fifth member of the 6d series of transition metals. Chemistry experiments have confirmed that bohrium behaves as the heavier homologue to rhenium in group 7. The chemical properties of bohrium are characterized only partly, but they compare well with the chemistry of the other group 7 elements. == Introduction == == History == === Discovery === Two groups claimed discovery of the element. Evidence of bohrium was first reported in 1976 by a Soviet research team led by Yuri Oganessian, in which targets of bismuth-209 and lead-208 were bombarded with accelerated nuclei of chromium-54 and manganese-55, respectively. Two activities, one with a half-life of one to two milliseconds, and the other with an approximately five-second half-life, were seen. Since the ratio of the intensities of these two activities was constant throughout the experiment, it was proposed that the first was from the isotope bohrium-261 and that the second was from its daughter dubnium-257. Later, the dubnium isotope was corrected to dubnium-258, which indeed has a five-second half-life (dubnium-257 has a one-second half-life); however, the half-life observed for its parent is much shorter than the half-lives later observed in the definitive discovery of bohrium at Darmstadt in 1981. The IUPAC/IUPAP
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Transfermium Working Group (TWG) concluded that while dubnium-258 was probably seen in this experiment, the evidence for the production of its parent bohrium-262 was not convincing enough. In 1981, a German research team led by Peter Armbruster and Gottfried Münzenberg at the GSI Helmholtz Centre for Heavy Ion Research (GSI Helmholtzzentrum für Schwerionenforschung) in Darmstadt bombarded a target of bismuth-209 with accelerated nuclei of chromium-54 to produce 5 atoms of the isotope bohrium-262: 20983Bi + 5424Cr → 262107Bh + n This discovery was further substantiated by their detailed measurements of the alpha decay chain of the produced bohrium atoms to previously known isotopes of fermium and californium. The IUPAC/IUPAP Transfermium Working Group (TWG) recognised the GSI collaboration as official discoverers in their 1992 report. === Proposed names === In September 1992, the German group suggested the name nielsbohrium with symbol Ns to honor the Danish physicist Niels Bohr. The Soviet scientists at the Joint Institute for Nuclear Research in Dubna, Russia had suggested this name be given to element 105 (which was finally called dubnium) and the German team wished to recognise both Bohr and the fact that the Dubna team had been the first to propose the cold fusion reaction, and simultaneously help to solve the controversial problem of the naming of element 105. The Dubna team agreed with the German group's naming proposal for element 107. There was an element naming controversy as to what the elements from 104 to 106 were to be called; the IUPAC adopted unnilseptium (symbol Uns) as a temporary, systematic element name for this element. In 1994 a committee of IUPAC recommended that element 107 be named bohrium, not nielsbohrium, since there was no precedent for using a scientist's complete name in the naming of an element. This was opposed by the discoverers
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{
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as there was some concern that the name might be confused with boron and in particular the distinguishing of the names of their respective oxyanions, bohrate and borate. The matter was handed to the Danish branch of IUPAC which, despite this, voted in favour of the name bohrium, and thus the name bohrium for element 107 was recognized internationally in 1997; the names of the respective oxyanions of boron and bohrium remain unchanged despite their homophony. == Isotopes == Bohrium has no stable or naturally occurring isotopes. Several radioactive isotopes have been synthesized in the laboratory, either by fusing two atoms or by observing the decay of heavier elements. Twelve different isotopes of bohrium have been reported with atomic masses 260–262, 264–267, 270–272, 274, and 278, one of which, bohrium-262, has a known metastable state. All of these but the unconfirmed 278Bh decay only through alpha decay, although some unknown bohrium isotopes are predicted to undergo spontaneous fission. The lighter isotopes usually have shorter half-lives; half-lives of under 100 ms for 260Bh, 261Bh, 262Bh, and 262mBh were observed. 264Bh, 265Bh, 266Bh, and 271Bh are more stable at around 1 s, and 267Bh and 272Bh have half-lives of about 10 s. The heaviest isotopes are the most stable, with 270Bh and 274Bh having measured half-lives of about 2.4 min and 40 s respectively, and the even heavier unconfirmed isotope 278Bh appearing to have an even longer half-life of about 11.5 minutes. The most proton-rich isotopes with masses 260, 261, and 262 were directly produced by cold fusion, those with mass 262 and 264 were reported in the decay chains of meitnerium and roentgenium, while the neutron-rich isotopes with masses 265, 266, 267 were created in irradiations of actinide targets. The five most neutron-rich ones with masses 270, 271, 272, 274, and
|
{
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278 (unconfirmed) appear in the decay chains of 282Nh, 287Mc, 288Mc, 294Ts, and 290Fl respectively. The half-lives of bohrium isotopes range from about ten milliseconds for 262mBh to about one minute for 270Bh and 274Bh, extending to about 11.5 minutes for the unconfirmed 278Bh, which may have one of the longest half-lives among reported superheavy nuclides. == Predicted properties == Very few properties of bohrium or its compounds have been measured; this is due to its extremely limited and expensive production and the fact that bohrium (and its parents) decays very quickly. A few singular chemistry-related properties have been measured, but properties of bohrium metal remain unknown and only predictions are available. === Chemical === Bohrium is the fifth member of the 6d series of transition metals and the heaviest member of group 7 in the periodic table, below manganese, technetium and rhenium. All the members of the group readily portray their group oxidation state of +7 and the state becomes more stable as the group is descended. Thus bohrium is expected to form a stable +7 state. Technetium also shows a stable +4 state whilst rhenium exhibits stable +4 and +3 states. Bohrium may therefore show these lower states as well. The higher +7 oxidation state is more likely to exist in oxyanions, such as perbohrate, BhO−4, analogous to the lighter permanganate, pertechnetate, and perrhenate. Nevertheless, bohrium(VII) is likely to be unstable in aqueous solution, and would probably be easily reduced to the more stable bohrium(IV). The lighter group 7 elements are known to form volatile heptoxides M2O7 (M = Mn, Tc, Re), so bohrium should also form the volatile oxide Bh2O7. The oxide should dissolve in water to form perbohric acid, HBhO4. Rhenium and technetium form a range of oxyhalides from the halogenation of the oxide. The chlorination
|
{
"page_id": 4194,
"source": null,
"title": "Bohrium"
}
|
of the oxide forms the oxychlorides MO3Cl, so BhO3Cl should be formed in this reaction. Fluorination results in MO3F and MO2F3 for the heavier elements in addition to the rhenium compounds ReOF5 and ReF7. Therefore, oxyfluoride formation for bohrium may help to indicate eka-rhenium properties. Since the oxychlorides are asymmetrical, and they should have increasingly large dipole moments going down the group, they should become less volatile in the order TcO3Cl > ReO3Cl > BhO3Cl: this was experimentally confirmed in 2000 by measuring the enthalpies of adsorption of these three compounds. The values are for TcO3Cl and ReO3Cl are −51 kJ/mol and −61 kJ/mol respectively; the experimental value for BhO3Cl is −77.8 kJ/mol, very close to the theoretically expected value of −78.5 kJ/mol. === Physical and atomic === Bohrium is expected to be a solid under normal conditions and assume a hexagonal close-packed crystal structure (c/a = 1.62), similar to its lighter congener rhenium. Early predictions by Fricke estimated its density at 37.1 g/cm3, but newer calculations predict a somewhat lower value of 26–27 g/cm3. The atomic radius of bohrium is expected to be around 128 pm. Due to the relativistic stabilization of the 7s orbital and destabilization of the 6d orbital, the Bh+ ion is predicted to have an electron configuration of [Rn] 5f14 6d4 7s2, giving up a 6d electron instead of a 7s electron, which is the opposite of the behavior of its lighter homologues manganese and technetium. Rhenium, on the other hand, follows its heavier congener bohrium in giving up a 5d electron before a 6s electron, as relativistic effects have become significant by the sixth period, where they cause among other things the yellow color of gold and the low melting point of mercury. The Bh2+ ion is expected to have an electron configuration of
|
{
"page_id": 4194,
"source": null,
"title": "Bohrium"
}
|
[Rn] 5f14 6d3 7s2; in contrast, the Re2+ ion is expected to have a [Xe] 4f14 5d5 configuration, this time analogous to manganese and technetium. The ionic radius of hexacoordinate heptavalent bohrium is expected to be 58 pm (heptavalent manganese, technetium, and rhenium having values of 46, 57, and 53 pm respectively). Pentavalent bohrium should have a larger ionic radius of 83 pm. == Experimental chemistry == In 1995, the first report on attempted isolation of the element was unsuccessful, prompting new theoretical studies to investigate how best to investigate bohrium (using its lighter homologs technetium and rhenium for comparison) and removing unwanted contaminating elements such as the trivalent actinides, the group 5 elements, and polonium. In 2000, it was confirmed that although relativistic effects are important, bohrium behaves like a typical group 7 element. A team at the Paul Scherrer Institute (PSI) conducted a chemistry reaction using six atoms of 267Bh produced in the reaction between 249Bk and 22Ne ions. The resulting atoms were thermalised and reacted with a HCl/O2 mixture to form a volatile oxychloride. The reaction also produced isotopes of its lighter homologues, technetium (as 108Tc) and rhenium (as 169Re). The isothermal adsorption curves were measured and gave strong evidence for the formation of a volatile oxychloride with properties similar to that of rhenium oxychloride. This placed bohrium as a typical member of group 7. The adsorption enthalpies of the oxychlorides of technetium, rhenium, and bohrium were measured in this experiment, agreeing very well with the theoretical predictions and implying a sequence of decreasing oxychloride volatility down group 7 of TcO3Cl > ReO3Cl > BhO3Cl. 2 Bh + 3 O2 + 2 HCl → 2 BhO3Cl + H2 The longer-lived heavy isotopes of bohrium, produced as the daughters of heavier elements, offer advantages for future radiochemical experiments.
|
{
"page_id": 4194,
"source": null,
"title": "Bohrium"
}
|
Although the heavy isotope 274Bh requires a rare and highly radioactive berkelium target for its production, the isotopes 272Bh, 271Bh, and 270Bh can be readily produced as daughters of more easily produced moscovium and nihonium isotopes. == Notes == == References == == Bibliography == Audi, G.; Kondev, F. G.; Wang, M.; et al. (2017). "The NUBASE2016 evaluation of nuclear properties". Chinese Physics C. 41 (3): 030001. Bibcode:2017ChPhC..41c0001A. doi:10.1088/1674-1137/41/3/030001. Beiser, A. (2003). Concepts of modern physics (6th ed.). McGraw-Hill. ISBN 978-0-07-244848-1. OCLC 48965418. Hoffman, D. C.; Ghiorso, A.; Seaborg, G. T. (2000). The Transuranium People: The Inside Story. World Scientific. ISBN 978-1-78-326244-1. Kragh, H. (2018). From Transuranic to Superheavy Elements: A Story of Dispute and Creation. Springer. ISBN 978-3-319-75813-8. Zagrebaev, V.; Karpov, A.; Greiner, W. (2013). "Future of superheavy element research: Which nuclei could be synthesized within the next few years?". Journal of Physics: Conference Series. 420 (1): 012001. arXiv:1207.5700. Bibcode:2013JPhCS.420a2001Z. doi:10.1088/1742-6596/420/1/012001. ISSN 1742-6588. S2CID 55434734. == External links == Media related to Bohrium at Wikimedia Commons Bohrium at The Periodic Table of Videos (University of Nottingham)
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{
"page_id": 4194,
"source": null,
"title": "Bohrium"
}
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