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Stable Phosphorus Radicals
Stable and persistent phosphorus radicals are phosphorus-centred radicals that are isolable and can exist for at least short periods of time. Radicals consisting of main group elements are often very reactive and undergo uncontrollable reactions, notably dimerization and polymerization. The common strategies for stabilising these phosphorus radicals usually include the delocalisation of the unpaired electron over a pi system or nearby electronegative atoms, and kinetic stabilisation with bulky ligands. Stable and persistent phosphorus radicals can be classified into three categories: neutral, cationic, and anionic radicals. Each of these classes involve various sub-classes, with neutral phosphorus radicals being the most extensively studied. Phosphorus exists as one isotope 31P (''I'' = 1/2) with large hyperfine couplings relative to other spin active nuclei, making phosphorus radicals particularly attractive for spin-labelling experiments. Neutral phosphorus radicals Neutra ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Antiferromagnetism
In materials that exhibit antiferromagnetism, the magnetic moments of atoms or molecules, usually related to the spins of electrons, align in a regular pattern with neighboring spins (on different sublattices) pointing in opposite directions. This is, like ferromagnetism and ferrimagnetism, a manifestation of ordered magnetism. The phenomenon of antiferromagnetism was first introduced by Lev Landau in 1933. Generally, antiferromagnetic order may exist at sufficiently low temperatures, but vanishes at and above the Néel temperature – named after Louis Néel, who had first identified this type of magnetic ordering. Above the Néel temperature, the material is typically paramagnetic. Measurement When no external field is applied, the antiferromagnetic structure corresponds to a vanishing total magnetization. In an external magnetic field, a kind of ferrimagnetic behavior may be displayed in the antiferromagnetic phase, with the absolute value of one of the sublattice magneti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ferromagnetism
Ferromagnetism is a property of certain materials (such as iron) which results in a large observed magnetic permeability, and in many cases a large magnetic coercivity allowing the material to form a permanent magnet. Ferromagnetic materials are the familiar metals noticeably attracted to a magnet, a consequence of their large magnetic permeability. Magnetic permeability describes the induced magnetization of a material due to the presence of an ''external'' magnetic field, and it is this temporarily induced magnetization inside a steel plate, for instance, which accounts for its attraction to the permanent magnet. Whether or not that steel plate acquires a permanent magnetization itself, depends not only on the strength of the applied field, but on the so-called coercivity of that material, which varies greatly among ferromagnetic materials. In physics, several different types of material magnetism are distinguished. Ferromagnetism (along with the similar effect ferrimagnetis ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Power2001
Power most often refers to: * Power (physics), meaning "rate of doing work" ** Engine power, the power put out by an engine ** Electric power * Power (social and political), the ability to influence people or events ** Abusive power Power may also refer to: Mathematics, science and technology Computing * IBM POWER (software), an IBM operating system enhancement package * IBM POWER architecture, a RISC instruction set architecture * Power ISA, a RISC instruction set architecture derived from PowerPC * IBM Power microprocessors, made by IBM, which implement those RISC architectures * Power.org, a predecessor to the OpenPOWER Foundation * SGI POWER Challenge, a line of SGI supercomputers Mathematics * Exponentiation, "''x'' to the power of ''y''" * Power function * Power of a point * Statistical power Physics * Magnification, the factor by which an optical system enlarges an image * Optical power, the degree to which a lens converges or diverges light Social sciences and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cummins2007
Cummins Inc. is an American multinational corporation that designs, manufactures, and distributes engines, filtration, and power generation products. Cummins also services engines and related equipment, including fuel systems, controls, air handling, filtration, emission control, electrical power generation systems, and trucks. Headquartered in Columbus, Indiana, Cummins sells in approximately 190 countries and territories through a network of more than 600 company-owned and independent distributors and approximately 7,200 dealers. Cummins reported a net income of $2.13 billion on sales of $24.02 billion in 2021. History The Cummins Engine Company was founded in Columbus, Indiana, on February 3, 1919, by mechanic Clessie Cummins and banker William Glanton Irwin. The company focused on developing the diesel engine invented 20 years earlier, but despite several well-publicized endurance trials, it was not until 1933, that their Model H engine, used in small railroad s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ito2006
Ito may refer to: Places * Ito Island, an island of Milne Bay Province, Papua New Guinea * Ito Airport, an airport in the Democratic Republic of the Congo * Ito District, Wakayama, a district located in Wakayama Prefecture, Japan * Itō, Shizuoka People * Itō (surname), for people with the Japanese surname Itō * , Japanese voice actor * Princess Ito (died 861), Japanese imperial princess * Ito Giani (1941–2018), Italian sprinter * Ito (footballer, born 1975), full name Antonio Álvarez Pérez, Spanish footballer * Ito (footballer, born 1992), full name Jorge Delgado Fidalgo, Spanish footballer * Ito (footballer, born 1994), full name Mario Manuel de Oliveira, Angolan footballer * , Japanese fashion model and actress (born 1995), Japanese fashion model and actress *Ito Smith (born 1995), American football player * Ito Curata (1959–2020), Filipino fashion designer * Ito Morabito (born 1977), French designer * Ito Ogawa (born 1973), Japanese novelist, lyricist, and transla ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
X-ray Crystallography
X-ray crystallography is the experimental science determining the atomic and molecular structure of a crystal, in which the crystalline structure causes a beam of incident X-rays to diffract into many specific directions. By measuring the angles and intensities of these diffracted beams, a crystallographer can produce a three-dimensional picture of the density of electrons within the crystal. From this electron density, the mean positions of the atoms in the crystal can be determined, as well as their chemical bonds, their crystallographic disorder, and various other information. Since many materials can form crystals—such as salts, metals, minerals, semiconductors, as well as various inorganic, organic, and biological molecules—X-ray crystallography has been fundamental in the development of many scientific fields. In its first decades of use, this method determined the size of atoms, the lengths and types of chemical bonds, and the atomic-scale differences among various mat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Halogen
The halogens () are a group in the periodic table consisting of five or six chemically related elements: fluorine (F), chlorine (Cl), bromine (Br), iodine (I), astatine (At), and tennessine (Ts). In the modern IUPAC nomenclature, this group is known as group 17. The word "halogen" means "salt former" (or "salt maker"). When halogens react with metals, they produce a wide range of salts, including calcium fluoride, sodium chloride (common table salt), silver bromide and potassium iodide. The group of halogens is the only periodic table group that contains elements in three of the main states of matter at standard temperature and pressure. All of the halogens form acids when bonded to hydrogen. Most halogens are typically produced from minerals or salts. The middle halogens—chlorine, bromine, and iodine—are often used as disinfectants. Organobromides are the most important class of flame retardants, while elemental halogens are dangerous and can be toxic. History The fl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Armstrong2004-corrected
Armstrong may refer to: Places * Armstrong Creek (other), various places Antarctica * Armstrong Reef, Biscoe Islands Argentina * Armstrong, Santa Fe Australia * Armstrong, Victoria Canada * Armstrong, British Columbia * Armstrong, Ontario * Armstrong, Thunder Bay District, Ontario * Armstrong, Ontario (Indian settlement) United States * Armstrong, California * Armstrong, Delaware * Armstrong, Florida * Armstrong, Georgia * Armstrong, Illinois * Armstrong, Indiana * Armstrong, Iowa * Armstrong, Minnesota * Armstrong, Missouri * Armstrong, Oklahoma * Armstrong, Texas * Armstrong, Wisconsin * Armstrong County, Pennsylvania * Armstrong County, Texas * Armstrong Lake (Blue Earth County, Minnesota), a lake in Minnesota * Armstrong Township, Vanderburgh County, Indiana * Armstrong Township, Pennsylvania (other), more than one, including ** Armstrong Township, Indiana County, Pennsylvania ** Armstrong Township, Lycoming County, Pennsylvania * Louis Armst ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Monomer
In chemistry, a monomer ( ; ''mono-'', "one" + '' -mer'', "part") is a molecule that can react together with other monomer molecules to form a larger polymer chain or three-dimensional network in a process called polymerization. Classification Monomers can be classified in many ways. They can be subdivided into two broad classes, depending on the kind of the polymer that they form. Monomers that participate in condensation polymerization have a different stoichiometry than monomers that participate in addition polymerization: : Other classifications include: *natural vs synthetic monomers, e.g. glycine vs caprolactam, respectively *polar vs nonpolar monomers, e.g. vinyl acetate vs ethylene, respectively *cyclic vs linear, e.g. ethylene oxide vs ethylene glycol, respectively The polymerization of one kind of monomer gives a homopolymer. Many polymers are copolymers, meaning that they are derived from two different monomers. In the case of condensation polymerizations, the r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tetrakis(dimethylamino)ethylene
Tetrakis(dimethylamino)ethylene (TDAE) is an organic compound with the formula (NMe2)2sub>2 (where Me = CH3). A colorless liquid, this compound is classified as an enamine. Primary and secondary enamines tend to isomerize, but tertiary enamines are kinetically stable. The unusual feature of TDAE is that it is a tetra-enamine. The pi-donating tendency of the amine groups strongly modifies the properties of the molecule, which does exhibit properties of a typical alkene. Reactions TDAE reacts with oxygen in a chemiluminescent reaction to give tetramethylurea TDAE is an electron donor with E = 1.06 V vs Fc+/0. It forms a charge transfer salt with buckminsterfullerene: :C2(N(CH3)2)4 + C60 → 2(N(CH3)2)4+C60−] Oxidation affords a dication. Structure Crystallographic analysis show that TDAE is a highly distorted alkene, the dihedral angle for the two N2C termini is 28″. The C=C distance is alkene-like, 135 pm. The nearly isostructural tetraisopropylethylene also has ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
