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Cyclotella
''Cyclotella'' is a genus of diatoms often found in oligotrophic environments, both marine and fresh water. It is in the family Stephanodiscaceae and the order Thalassiosirales. The genus was first discovered in the mid-1800s and since then has become an umbrella genus for over 100 different species, the most well-studied and the best known being '' Cyclotella meneghiniana''. Despite being among the most dominant genera in low-productivity environments, it is relatively understudied.Saros, J.E., Anderson, N.J. (2015). The ecology of the planktonic diatom Cyclotella and its implications for global environmental change studies. Biol Rev Camb Philos Soc. 90(2). 522-41. ''Cyclotella'' habitat has traditionally been described as low-productivity mesotrophic or oligotrophic freshwater environments. However, it is unclear whether there is an archetypal aquatic setting for this genus as some species are more cosmopolitan, such as ''C. meneghiniana,'' which occurs in warm, nutrient-rich ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cyclotella Meneghiniana
''Cyclotella'' is a genus of diatoms often found in oligotrophic environments, both marine and fresh water. It is in the family Stephanodiscaceae and the order Thalassiosirales. The genus was first discovered in the mid-1800s and since then has become an umbrella genus for over 100 different species, the most well-studied and the best known being '' Cyclotella meneghiniana''. Despite being among the most dominant genera in low-productivity environments, it is relatively understudied.Saros, J.E., Anderson, N.J. (2015). The ecology of the planktonic diatom Cyclotella and its implications for global environmental change studies. Biol Rev Camb Philos Soc. 90(2). 522-41. ''Cyclotella'' habitat has traditionally been described as low-productivity mesotrophic or oligotrophic freshwater environments. However, it is unclear whether there is an archetypal aquatic setting for this genus as some species are more cosmopolitan, such as ''C. meneghiniana,'' which occurs in warm, nutrient-rich e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Friedrich Traugott Kützing
Friedrich Traugott Kützing (8 December 1807 in Ritteburg – 9 September 1893) was a German pharmacist, botanist and phycologist. Despite his limited background in regard to higher education, Kützing made significant scientific contributions. In 1833, he demonstrated differences between diatoms and desmids, thus separating the two groups into families of their own. Also, independent of Charles Cagniard-Latour (1777–1859) and Theodor Schwann (1810–1882), he was among the first to provide comprehensive answers in regard to yeast and the role it played in fermentation. In 1849, he published ''Species Algarum'', a large work that provided descriptions for 6000 species of algae. He is the taxonomic authority of the genera '' Syringodium'' (family Cymodoceaceae) and ''Phlebothamnion'' (family Ceramiaceae). Early life As a young man, he worked in several pharmacies in Germany, also serving as assistant for a few semesters at the chemical-pharmaceutical institute of Fran ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Subantarctic
The sub-Antarctic zone is a physiographic region in the Southern Hemisphere, located immediately north of the Antarctic region. This translates roughly to a latitude of between 46th parallel south, 46° and 60th parallel south, 60° south of the Equator. The subantarctic region includes many List of Antarctic and subantarctic islands, islands in the southern parts of the Atlantic Ocean, Atlantic, Indian Ocean, Indian, and Pacific Ocean, Pacific oceans, especially those situated north of the Antarctic Convergence. Subantarctic glaciers are, by definition, located on islands within the subantarctic region. All glaciers located on the continent of Antarctica are by definition considered to be list of glaciers in the Antarctic, Antarctic glaciers. Geography The subantarctic region comprises two geographic zones and three distinct weather front, fronts. The northernmost boundary of the subantarctic region is the rather ill-defined subtropical front, Subtropical Front (STF), also r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Solvent
A solvent (from the Latin language, Latin ''wikt:solvo#Latin, solvō'', "loosen, untie, solve") is a substance that dissolves a solute, resulting in a Solution (chemistry), solution. A solvent is usually a liquid but can also be a solid, a gas, or a supercritical fluid. Water is a solvent for Chemical polarity#Polarity of molecules, polar molecules, and the most common solvent used by living things; all the ions and proteins in a Cell (biology), cell are dissolved in water within the cell. Major uses of solvents are in paints, paint removers, inks, and dry cleaning. Specific uses for Organic compound, organic solvents are in dry cleaning (e.g. tetrachloroethylene); as paint thinners (toluene, turpentine); as nail polish removers and solvents of glue (acetone, methyl acetate, ethyl acetate); in spot removers (hexane, petrol ether); in detergents (D-limonene, citrus terpenes); and in perfumes (ethanol). Solvents find various applications in chemical, pharmaceutical, oil, and gas ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Paracrystalline
In materials science, paracrystalline materials are defined as having short- and medium-range ordering in their lattice (similar to the liquid crystal phases) but lacking crystal-like long-range ordering at least in one direction. Origin and definition The words "paracrystallinity" and "paracrystal" were coined by the late Friedrich Rinne in the year 1933. Their German equivalents, e.g. "Parakristall", appeared in print one year earlier. A general theory of paracrystals has been formulated in a basic textbook, and then further developed/refined by various authors. Rolf Hosemann's definition of an ideal paracrystal is: "The electron density distribution of any material is equivalent to that of a paracrystal when there is for every building block one ideal point so that the distance statistics to other ideal points are identical for all of these points. The electron configuration of each building block around its ideal point is statistically independent of its counterpart in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hydrogen Bond
In chemistry, a hydrogen bond (H-bond) is a specific type of molecular interaction that exhibits partial covalent character and cannot be described as a purely electrostatic force. It occurs when a hydrogen (H) atom, Covalent bond, covalently bonded to a more Electronegativity, electronegative donor atom or group (Dn), interacts with another electronegative atom bearing a lone pair of electrons—the hydrogen bond acceptor (Ac). Unlike simple Dipole–dipole attraction, dipole–dipole interactions, hydrogen bonding arises from charge transfer (nB → σ*AH), Atomic orbital, orbital interactions, and quantum mechanical Delocalized electron, delocalization, making it a resonance-assisted interaction rather than a mere electrostatic attraction. The general notation for hydrogen bonding is Dn−H···Ac, where the solid line represents a polar covalent bond, and the dotted or dashed line indicates the hydrogen bond. The most frequent donor and acceptor atoms are nitrogen (N), oxyg ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Glucosamine
Glucosamine (C6H13NO5) is an amino sugar and a prominent precursor in the biochemical synthesis of glycosylated proteins and lipids. Glucosamine is part of the structure of two polysaccharides, chitosan and chitin. Glucosamine is one of the most abundant monosaccharides. Produced commercially by the hydrolysis of shellfish exoskeletons or, less commonly, by fermentation of a grain such as corn or wheat, glucosamine has many names depending on country. Although a common dietary supplement, there is little evidence that it is effective for relief of arthritis or pain, and is not an approved prescription drug in the United States. Dietary supplement Oral glucosamine is a dietary supplement and is not a prescription drug in the United States. Glucosamine is marketed as a supplement to support the structure and function of joints, and the marketing is targeted to people with osteoarthritis. Commonly sold forms of glucosamine are glucosamine sulfate, glucosamine chondroitin, glu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thalassiosira
''Thalassiosira'' is a genus of centric diatoms, comprising over 100 marine and freshwater species. It is a diverse group of photosynthetic eukaryotes that make up a vital part of marine and freshwater ecosystems, in which they are key primary producers and essential for carbon cycling Dreux Chappell, P., Whitney, L. A. P., Haddock, T. L., Susanne Menden-Deuer, Menden-Deuer, S., Roy, E. G., Wells, M. L., & Jenkins, B. D. (2013). Thalassiosira spp. community composition shifts in response to chemical and physical forcing in the northeast Pacific Ocean. Frontiers in Microbiology, 4(SEP), 273. https://doi.org/10.3389/fmicb.2013.00273 ''Thalassiosira'' is a diverse genus, however one species within the genus, ''T. pseudonana'', has gained particular significance as the first marine phytoplankton to have its genome sequenced. ''T. pseudonana'' has since become a key model organism for studying diatom physiology. The ''T. pseudonana'' genome revealed novel genes for intracellular traffi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Allomorph
In linguistics, an allomorph is a variant phonetic form of a morpheme, or in other words, a unit of meaning that varies in sound and spelling without changing the meaning. The term ''allomorph'' describes the realization of phonological variations for a specific morpheme. The different allomorphs that a morpheme can become are governed by morphophonemic rules. These phonological rules determine what phonetic form, or specific pronunciation, a morpheme will take based on the phonological or morphological context in which it appears. Allomorphy in English involves the variation of morphemes in their phonetic form based on specific linguistic contexts, a phenomenon governed by morphophonemic rules. For instance, the past tense morpheme "-ed" can manifest in different forms—[-əd], [-t], or [-d]—depending on the final sound of the verb stem. This variability is not random but follows predictable patterns, such as the insertion of a schwa [ə] or assimilation to the voicing of the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chitin
Chitin (carbon, C8hydrogen, H13oxygen, O5nitrogen, N)n ( ) is a long-chain polymer of N-Acetylglucosamine, ''N''-acetylglucosamine, an amide derivative of glucose. Chitin is the second most abundant polysaccharide in nature (behind only cellulose); an estimated 1 billion tons of chitin are produced each year in the biosphere. It is a primary component of cell walls in fungi (especially filamentous and mushroom-forming fungi), the exoskeletons of arthropods such as crustaceans and insects, the radulae, cephalopod beaks and Gladius (cephalopod), gladii of molluscs and in some nematodes and diatoms. It is also synthesised by at least some fish and lissamphibians. Commercially, chitin is extracted from the shells of crabs, shrimps, shellfish and lobsters, which are major by-products of the seafood industry. The structure of chitin is comparable to cellulose, forming crystalline nanofibrils or whiskers. It is functionally comparable to the protein keratin. Chitin has proved useful ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oxide
An oxide () is a chemical compound containing at least one oxygen atom and one other element in its chemical formula. "Oxide" itself is the dianion (anion bearing a net charge of −2) of oxygen, an O2− ion with oxygen in the oxidation state of −2. Most of the Earth's crust consists of oxides. Even materials considered pure elements often develop an oxide coating. For example, aluminium foil develops a thin skin of (called a passivation layer) that protects the foil from further oxidation.Greenwood, N. N.; & Earnshaw, A. (1997). Chemistry of the Elements (2nd Edn.), Oxford:Butterworth-Heinemann. . Stoichiometry Oxides are extraordinarily diverse in terms of stoichiometries (the measurable relationship between reactants and chemical equations of an equation or reaction) and in terms of the structures of each stoichiometry. Most elements form oxides of more than one stoichiometry. A well known example is carbon monoxide and carbon dioxide.Greenwood, N. N.; & Earnsh ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carbon
Carbon () is a chemical element; it has chemical symbol, symbol C and atomic number 6. It is nonmetallic and tetravalence, tetravalent—meaning that its atoms are able to form up to four covalent bonds due to its valence shell exhibiting 4 electrons. It belongs to group 14 of the periodic table. Carbon makes up about 0.025 percent of Earth's crust. Three Isotopes of carbon, isotopes occur naturally, carbon-12, C and carbon-13, C being stable, while carbon-14, C is a radionuclide, decaying with a half-life of 5,700 years. Carbon is one of the timeline of chemical element discoveries#Pre-modern and early modern discoveries, few elements known since antiquity. Carbon is the 15th abundance of elements in Earth's crust, most abundant element in the Earth's crust, and the abundance of the chemical elements, fourth most abundant element in the universe by mass after hydrogen, helium, and oxygen. Carbon's abundance, its unique diversity of organic compounds, and its unusual abi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
