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Avoided crossing So for these two levels to cross we simultaneously require Now if the perturbation formula_49 has formula_50 parameters formula_51 we may in general vary these numbers to satisfy these two equations. If we choose the values of formula_54 to formula_55 then both of the equations above have one single fr... | https://en.wikipedia.org/wiki?curid=2174011 |
Avoided crossing If the original Hamiltonian has asymmetric states, formula_70, the off-diagonal terms vanish automatically to ensure hermiticity. This allows us to get rid of the equation formula_71. Now from similar arguments as posed above, it is straightforward that for an asymmetrical Hamiltonian, the intersection... | https://en.wikipedia.org/wiki?curid=2174011 |
Lotus effect The lotus effect refers to self-cleaning properties that are a result of ultrahydrophobicity as exhibited by the leaves of "Nelumbo" or "lotus flower". Dirt particles are picked up by water droplets due to the micro- and nanoscopic architecture on the surface, which minimizes the droplet's adhesion to that... | https://en.wikipedia.org/wiki?curid=2174453 |
Lotus effect Either complete or incomplete wetting may occur depending on the structure of the surface and the fluid tension of the droplet. The cause of self-cleaning properties is the hydrophobic water-repellent double structure of the surface. This enables the contact area and the adhesion force between surface and ... | https://en.wikipedia.org/wiki?curid=2174453 |
Lotus effect Dirt particles with an extremely reduced contact area are picked up by water droplets and are thus easily cleaned off the surface. If a water droplet rolls across such a contaminated surface the adhesion between the dirt particle, irrespective of its chemistry, and the droplet is higher than between the pa... | https://en.wikipedia.org/wiki?curid=2174453 |
Lotus effect Some nanotechnologists have developed treatments, coatings, paints, roof tiles, fabrics and other surfaces that can stay dry and clean themselves by replicating in a technical manner the self-cleaning properties of plants, such as the lotus plant. This can usually be achieved using special fluorochemical o... | https://en.wikipedia.org/wiki?curid=2174453 |
Lotus effect Another possible application is thus with self-cleaning awnings, tarpaulins and sails, which otherwise quickly become dirty and difficult to clean. Superhydrophobic coatings applied to microwave antennas can significantly reduce rain fade and the buildup of ice and snow. "Easy to clean" products in ads are... | https://en.wikipedia.org/wiki?curid=2174453 |
Lotus effect The measured contact angle on this leaf in this study is around 148 degrees. | https://en.wikipedia.org/wiki?curid=2174453 |
Mixed potential theory is a theory used in electrochemistry that relates the potentials and currents from differing constituents to come up with a 'weighted' potential at zero net current. In other words, it is an electrode potential resulting from a simultaneous action of more than a single redox couple, while the net... | https://en.wikipedia.org/wiki?curid=2175615 |
Cosmic dust Cosmic dust, also called extraterrestrial dust or space dust, is dust which exists in outer space, or has fallen on Earth. Most cosmic dust particles measure between a few molecules and 0.1 µm. can be further distinguished by its astronomical location: intergalactic dust, interstellar dust, interplanetary d... | https://en.wikipedia.org/wiki?curid=2178570 |
Cosmic dust Their analysis can reveal information about phenomena like the formation of the Solar System. For example, cosmic dust can drive the mass loss when a star is nearing the end of its life, play a part in the early stages of star formation, and form planets. In the Solar System, dust plays a major role in the ... | https://en.wikipedia.org/wiki?curid=2178570 |
Cosmic dust The astronomers accumulate observational ‘snapshots’ of dust at different stages of its life and, over time, form a more complete movie of the Universe's complicated recycling steps. Parameters such as the particle's initial motion, material properties, intervening plasma and magnetic field determined the d... | https://en.wikipedia.org/wiki?curid=2178570 |
Cosmic dust They are recognized by their extreme isotopic compositions, which can only be isotopic compositions within evolved stars, prior to any mixing with the interstellar medium. These grains condensed from the stellar matter as it cooled while leaving the star. In interplanetary space, dust detectors on planetary... | https://en.wikipedia.org/wiki?curid=2178570 |
Cosmic dust Presently dust detectors are flying on the "Ulysses", Proba, "Rosetta", "Stardust", and the "New Horizons" spacecraft. The collected dust at Earth or collected further in space and returned by sample-return space missions is then analyzed by dust scientists in their respective laboratories all over the worl... | https://en.wikipedia.org/wiki?curid=2178570 |
Cosmic dust In 2019, researchers found interstellar dust in Antarctica which they relate to the Local Interstellar Cloud. The detection of interstellar dust in Antarctica was done by the measurement of the radionuclides Fe-60 and Mn-53 by highly sensitive Accelerator mass spectrometry. A dust particle interacts with el... | https://en.wikipedia.org/wiki?curid=2178570 |
Cosmic dust The scattering of light from dust grains in long exposure visible photographs is quite noticeable in reflection nebulae, and gives clues about the individual particle's light-scattering properties. In X-ray wavelengths, many scientists are investigating the scattering of X-rays by interstellar dust, and som... | https://en.wikipedia.org/wiki?curid=2178570 |
Cosmic dust These refractory mineral grains may earlier have been coated with volatile compounds, but those are lost in the dissolving of meteorite matter in acids, leaving only insoluble refractory minerals. Finding the grain cores without dissolving most of the meteorite has been possible, but difficult and labor-int... | https://en.wikipedia.org/wiki?curid=2178570 |
Cosmic dust For example, the heavy elements within the silicon carbide (SiC) grains are almost pure S-process isotopes, fitting their condensation within AGB star red giant winds inasmuch as the AGB stars are the main source of S-process nucleosynthesis and have atmospheres observed by astronomers to be highly enriched... | https://en.wikipedia.org/wiki?curid=2178570 |
Cosmic dust The high interest in stardust derives from new information that it has brought to the sciences of stellar evolution and nucleosynthesis. Laboratories have studied solids that existed before the Earth was formed. This was once thought impossible, especially in the 1970s when cosmochemists were confident that... | https://en.wikipedia.org/wiki?curid=2178570 |
Cosmic dust The total influx rate of meteoritic sities of most IDPs captured in the Earth's stratosphere range between 1 and 3 g/cm³, with an average density at about 2.0 g/cm³. Other specific dust properties: in "circumstellar dust", astronomers have found molecular signatures of CO, silicon carbide, amorphous silicat... | https://en.wikipedia.org/wiki?curid=2178570 |
Cosmic dust Those refractory cores are also called stardust (section above), which is a scientific term for the small fraction of cosmic dust that condensed thermally within stellar gases as they were ejected from the stars. Several percent of refractory grain cores have condensed within expanding interiors of supernov... | https://en.wikipedia.org/wiki?curid=2178570 |
Cosmic dust 5 micrometres indicates the presence of silicon carbide dust in cool evolved carbon-rich giant stars. These help provide evidence that the small silicate particles in space came from the ejected outer envelopes of these stars. Conditions in interstellar space are generally not suitable for the formation of ... | https://en.wikipedia.org/wiki?curid=2178570 |
Cosmic dust Some molecules such as CO, N, NH, and free oxygen, existed in a gas phase. Some molecules, for example, graphite (C) and SiC would condense into solid grains in the planetary disk; but carbon and SiC grains found in meteorites are presolar based on their isotopic compositions, rather than from the planetary... | https://en.wikipedia.org/wiki?curid=2178570 |
Cosmic dust The materials in a single interplanetary dust particle often show that the grain elements formed in different locations and at different times in the solar nebula. Most of the matter present in the original solar nebula has since disappeared; drawn into the Sun, expelled into interstellar space, or reproces... | https://en.wikipedia.org/wiki?curid=2178570 |
Cosmic dust From the carbonaceous chondrites, we follow the trail to the most primitive materials. They are almost completely oxidized and contain the lowest condensation temperature elements ("volatile" elements) and the largest amount of organic compounds. Therefore, dust particles with these elements are thought to ... | https://en.wikipedia.org/wiki?curid=2178570 |
Cosmic dust Based on 2012 computer model studies, the complex organic molecules necessary for life (Extraterrestrial organic molecules) may have formed in the protoplanetary disk of dust grains surrounding the Sun before the formation of the Earth. According to the computer studies, this same process may also occur aro... | https://en.wikipedia.org/wiki?curid=2178570 |
Cosmic dust In March 2015, NASA scientists reported that, for the first time, complex DNA and RNA organic compounds of life, including uracil, cytosine and thymine, have been formed in the laboratory under outer space conditions, using starting chemicals, such as pyrimidine, found in meteorites. Pyrimidine, like polycy... | https://en.wikipedia.org/wiki?curid=2178570 |
Cosmic dust Some larger dust catalogs are Sharpless (1959) A Catalogue of HII Regions, Lynds (1965) Catalogue of Bright Nebulae, Lynds (1962) Catalogue of Dark Nebulae, van den Bergh (1966) Catalogue of Reflection Nebulae, Green (1988) Rev. Reference Cat. of Galactic SNRs, The National Space Sciences Data Center (NSSDC... | https://en.wikipedia.org/wiki?curid=2178570 |
Koopmans' theorem states that in closed-shell Hartree–Fock theory (HF), the first ionization energy of a molecular system is equal to the negative of the orbital energy of the highest occupied molecular orbital (HOMO). This theorem is named after Tjalling Koopmans, who published this result in 1934. is exact in the con... | https://en.wikipedia.org/wiki?curid=2178720 |
Koopmans' theorem A similar theorem exists in density functional theory (DFT) for relating the exact first vertical ionization energy and electron affinity to the HOMO and LUMO energies, although both the derivation and the precise statement differ from that of Koopmans' theorem. Ionization energies calculated from DFT... | https://en.wikipedia.org/wiki?curid=2178720 |
Koopmans' theorem The other states are excited electronic states. For example, the electronic configuration of the HO molecule is (1a) (2a) (1b) (3a) (1b), where the symbols a, b and b are orbital labels based on molecular symmetry. From Koopmans’ theorem the energy of the 1b HOMO corresponds to the ionization energy t... | https://en.wikipedia.org/wiki?curid=2178720 |
Koopmans' theorem It is sometimes claimed that also allows the calculation of electron affinities as the energy of the lowest unoccupied molecular orbitals (LUMO) of the respective systems. However, Koopmans' original paper makes no claim with regard to the significance of eigenvalues of the Fock operator other than th... | https://en.wikipedia.org/wiki?curid=2178720 |
Koopmans' theorem Kohn–Sham (KS) density functional theory (KS-DFT) admits its own version of (sometimes called the DFT-Koopmans' theorem) very similar in spirit to that of Hartree-Fock theory. The theorem equates the first (vertical) ionization energy formula_1 of a system of formula_2 electrons to the negative of the... | https://en.wikipedia.org/wiki?curid=2178720 |
Koopmans' theorem Finally, since the KS potential is zero at infinity, the ionization energy of the KS system is, by definition, the negative of its HOMO energy and thus finally: formula_11. While these are exact statements in the formalism of DFT, the use of approximate exchange-correlation potentials makes the calcul... | https://en.wikipedia.org/wiki?curid=2178720 |
Diabatic In quantum chemistry, the potential energy surfaces are obtained within the adiabatic or Born–Oppenheimer approximation. This corresponds to a representation of the molecular wave function where the variables corresponding to the molecular geometry and the electronic degrees of freedom are separated. The non s... | https://en.wikipedia.org/wiki?curid=2178880 |
Diabatic The motivation to calculate diabatic potentials often occurs when the Born–Oppenheimer approximation does not hold, or is not justified for the molecular system under study. For these systems, it is necessary to go "beyond" the Born–Oppenheimer approximation. This is often the terminology used to refer to the ... | https://en.wikipedia.org/wiki?curid=2178880 |
Diabatic In the absence of magnetic interactions these electronic states, which depend parametrically on the nuclear coordinates, may be taken to be real-valued functions. The nuclear kinetic energy is a sum over nuclei "A" with mass "M", (Atomic units are used here). By applying the Leibniz rule for differentiation, t... | https://en.wikipedia.org/wiki?curid=2178880 |
Diabatic (Smith was the first to define this concept; earlier the term "diabatic" was used somewhat loosely by Lichten ). By a small change of notation these differential equations for formula_16 can be rewritten in the following more familiar form: It is well known that the differential equations have a solution (i.e.... | https://en.wikipedia.org/wiki?curid=2178880 |
Diabatic Once formula_16 has been found and the coupled equations have been solved, the final vibronic wave function in the diabatic approximation is Here, in contrast to previous treatments, the non-Abelian case is considered. Felix Smith in his article considers the adiabatic-to-diabatic transformation (ADT) for a mu... | https://en.wikipedia.org/wiki?curid=2178880 |
Diabatic To derive the matrix formula_56 one has to solve the above given first order differential equation along a specified contour formula_57. This solution is then applied to form the diabatic potential matrix formula_58: where formula_60 ; "j" = 1, "M" are the Born–Oppenheimer adiabatic potentials. In order for fo... | https://en.wikipedia.org/wiki?curid=2178880 |
Diabatic Thus, assuming: formula_81 the two coupled equations for formula_82 and formula_83 are: whereas the third equation (for formula_86) becomes an ordinary (line) integral: expressed solely in terms of formula_88 and formula_89. Similarly, in case of a four-state system formula_47 is presented as a product of six ... | https://en.wikipedia.org/wiki?curid=2178880 |
Conical intersection In quantum chemistry, a conical intersection of two or more potential energy surfaces is the set of molecular geometry points where the potential energy surfaces are degenerate (intersect) and the non-adiabatic couplings between these states are non-vanishing. In the vicinity of conical intersectio... | https://en.wikipedia.org/wiki?curid=2178942 |
Conical intersection At this point the very large vibronic coupling induces a non-radiative transition (surface-hopping) which leads the molecule back to its electronic ground state. Degenerate points between potential energy surfaces lie in what is called the intersection or seam space with a dimensionality of 3N-8 (w... | https://en.wikipedia.org/wiki?curid=2178942 |
Conical intersection Without the necessary two dimensions required to form the cone shape, conical intersections cannot exist in these molecules. Instead, the potential energy curves experience avoided crossings. In molecules with three or more atoms, the number of degrees of freedom for molecular vibrations is at leas... | https://en.wikipedia.org/wiki?curid=2178942 |
Conical intersection The degeneracy is preserved through first order by differential displacements that are perpendicular to the branching space. The space of non-degeneracy-lifting displacements, which is the orthogonal complement of the branching space, is termed the seam space. Movement within the seam space will ta... | https://en.wikipedia.org/wiki?curid=2178942 |
Conical intersection It is named symmetry-required because these electronic states will always be degenerate as long as the symmetry is present. Symmetry-required intersections are often associated with Jahn-Teller effect. An accidental symmetry-allowed conical intersection is an intersection between two electronic sta... | https://en.wikipedia.org/wiki?curid=2178942 |
Conical intersection While this type of intersection was traditionally more difficult to locate, a number of efficient searching algorithms and methods to compute non-adiabatic couplings have emerged in the past decade. It is now understood that same-symmetry intersections play as important a role in non-adiabatic proc... | https://en.wikipedia.org/wiki?curid=2178942 |
X-ray microtomography X-ray microtomography, like tomography and X-ray computed tomography, uses X-rays to create cross-sections of a physical object that can be used to recreate a virtual model (3D model) without destroying the original object. The prefix "micro-" (symbol: µ) is used to indicate that the pixel sizes o... | https://en.wikipedia.org/wiki?curid=2181790 |
X-ray microtomography The fan-beam system is based on a one-dimensional (1D) X-ray detector and an electronic X-ray source, creating 2D cross-sections of the object. Typically used in human computed tomography systems. The cone-beam system is based on a 2D X-ray detector (camera) and an electronic X-ray source, creatin... | https://en.wikipedia.org/wiki?curid=2181790 |
X-ray microtomography Because microtomography scanners offer isotropic, or near isotropic, resolution, display of images does not need to be restricted to the conventional axial images. Instead, it is possible for a software program to build a volume by 'stacking' the individual slices one on top of the other. The prog... | https://en.wikipedia.org/wiki?curid=2181790 |
X-ray microtomography Where different structures have similar threshold density, it can become impossible to separate them simply by adjusting volume rendering parameters. The solution is called segmentation, a manual or automatic procedure that can remove the unwanted structures from the image. Developmental biology I... | https://en.wikipedia.org/wiki?curid=2181790 |
Humphry Bowen Humphry John Moule Bowen (22 June 1929 – 9 August 2001) was a British botanist and chemist. Bowen was born in Oxford, son of the chemist Edmund Bowen. He attended the Dragon School, gaining a scholarship to Rugby School and then a demyship to Magdalen College, Oxford. He won the "Gibbs Prize" in 1949 and ... | https://en.wikipedia.org/wiki?curid=2182309 |
Humphry Bowen In 1964, he was appointed as a lecturer in the chemistry department at the University of Reading. Later he was promoted to Reader in analytical chemistry in 1974. At Reading, Bowen undertook consultancy for Dunlop, investigating potential uses for their products. When the "Torrey Canyon" oil disaster occu... | https://en.wikipedia.org/wiki?curid=2182309 |
Humphry Bowen He established the Bowen Cup at the University of Reading in 1988, an annual prize for the student in the Department of Chemistry at the University who achieves the top marks in Part II Analytical Chemistry. | https://en.wikipedia.org/wiki?curid=2182309 |
Formic acid (data page) This page provides supplementary chemical data on formic acid. The handling of this chemical may incur notable safety precautions. It is highly recommend that you seek the Material Safety Datasheet (MSDS) for this chemical from a reliable source and follow its directions. Table data obtained fro... | https://en.wikipedia.org/wiki?curid=2182370 |
Periodinane Periodinanes also known as λ-iodanes are organoiodine compounds with iodine in the +5 oxidation state. These compounds are hypervalent because the iodine atoms in them formally contain more than 8 valence electrons. The λ-iodanes such as the Dess-Martin periodinane have square pyramidal geometries with 4 he... | https://en.wikipedia.org/wiki?curid=2182805 |
Aluminide An aluminide is a compound that has aluminium with more electropositive elements. Since aluminium is near the nonmetals on the periodic table, it can bond with metals differently from other metals. The properties of an aluminide would be intermediate between a metal alloy and an ionic compound. See for a list... | https://en.wikipedia.org/wiki?curid=2183025 |
4-Dimethylaminopyridine (DMAP) is a derivative of pyridine with the chemical formula (CH)NCHN. This colourless solid is of interest because it is more basic than pyridine, owing to the resonance stabilisation from the NMe substituent. Because of its basicity, DMAP is a useful nucleophilic catalyst for a variety of reac... | https://en.wikipedia.org/wiki?curid=2183056 |
4-Dimethylaminopyridine In the last step of the catalytic cycle the auxiliary base (usually triethylamine or pyridine) deprotonates the protonated DMAP, reforming the catalyst. The reaction runs through the described nucleophilic reaction pathway irrespective of the anhydride used, but the mechanism changes with the pK... | https://en.wikipedia.org/wiki?curid=2183056 |
Boiling-point elevation describes the phenomenon that the boiling point of a liquid (a solvent) will be higher when another compound is added, meaning that a solution has a higher boiling point than a pure solvent. This happens whenever a non-volatile solute, such as a salt, is added to a pure solvent, such as water. T... | https://en.wikipedia.org/wiki?curid=2184383 |
Boiling-point elevation A nonvolatile solute has a vapor pressure of zero, so the vapor pressure of the solution is less than the vapor pressure of the solvent. Thus, a higher temperature is needed for the vapor pressure to reach the surrounding pressure, and the boiling point is elevated. Put in chemical potential ter... | https://en.wikipedia.org/wiki?curid=2184383 |
Boiling-point elevation The extent of boiling-point elevation can be calculated by applying Clausius–Clapeyron relation and Raoult's law together with the assumption of the non-volatility of the solute. The result is that in dilute ideal solutions, the extent of boiling-point elevation is directly proportional to the m... | https://en.wikipedia.org/wiki?curid=2184383 |
Boiling-point elevation This kind of measurement is called ebullioscopy (Greek "boiling-viewing"). However, since superheating is difficult to avoid, precise "ΔT" measurements are difficult to carry out, which was partly overcome by the invention of the Beckmann thermometer. Furthermore, the cryoscopic constant that de... | https://en.wikipedia.org/wiki?curid=2184383 |
Multi-configuration time-dependent Hartree (MCTDH) is a general algorithm to solve the time-dependent Schrödinger equation for multidimensional dynamical systems consisting of distinguishable particles. MCTDH can thus determine the quantal motion of the nuclei of a molecular system evolving on one or several coupled el... | https://en.wikipedia.org/wiki?curid=2185680 |
Bioprocessor A bioprocessor is a miniaturized bioreactor capable of culturing mammalian, insect and microbial cells. Bioprocessors are capable of mimicking performance of large-scale bioreactors, hence making them ideal for laboratory scale experimentation of cell culture processes. Bioprocessors are also used for conc... | https://en.wikipedia.org/wiki?curid=2186993 |
DEA list of chemicals The United States Drug Enforcement Administration (DEA) maintains lists regarding the classification of illicit drugs (see DEA Schedules). It also maintains List I of chemicals and List II of chemicals, which contain chemicals that are used to manufacture the controlled substances/illicit drugs. T... | https://en.wikipedia.org/wiki?curid=2188477 |
DEA list of chemicals Some Special Surveillance List chemicals do not have an exclusive manufacturing use for a specific illicit drug but rather have a broad range of uses in both legitimate and illicit manufacturing operations. The equipment list: | https://en.wikipedia.org/wiki?curid=2188477 |
Obsidian hydration dating (OHD) is a geochemical method of determining age in either absolute or relative terms of an artifact made of obsidian. Obsidian is a volcanic glass that was used by prehistoric people as a raw material in the manufacture of stone tools such as projectile points, knives, or other cutting tools ... | https://en.wikipedia.org/wiki?curid=2188925 |
Obsidian hydration dating Today the technique is applied extensively by archaeologists to date prehistoric sites and sites from prehistory in California and the Great Basin of North America. It has also been applied in South America, the Middle East, the Pacific Islands, including New Zealand and Mediterranean Basin. T... | https://en.wikipedia.org/wiki?curid=2188925 |
Obsidian hydration dating Although relatively infrequent the use of SIMS on obsidian surface investigations has produced great progress in OHD dating. SIMS in general refers to four instrumental categories according to their operation; static, dynamic, quadrupole, and time-of-flight, TOF. In essence it is a technique w... | https://en.wikipedia.org/wiki?curid=2188925 |
Obsidian hydration dating In Rhodes, Greece, under the direction and invention of Ioannis Liritzis, the dating approach is based on modeling the S-like hydrogen profile by SIMS, following Fick's diffusion law, and an understanding of the surface saturation layer (see Figure). In fact, the saturation layer on the surfac... | https://en.wikipedia.org/wiki?curid=2188925 |
Obsidian hydration dating Thus, artifacts exposed to higher temperatures, for example by being at lower elevation, seem to hydrate faster. As well, obsidian chemistry, including the intrinsic water content, seems to affect the rate of hydration. Once an archeologist can control for the geochemical signature of the obsi... | https://en.wikipedia.org/wiki?curid=2188925 |
Obsidian hydration dating 1 Fitting polynomial of the SIMS profile formula_2<br>Eq.2 The SIMS-SS age equation in years before present Where, Ci is the intrinsic concentration of water, Cs is the saturation concentration, dC/dx is the diffusion coefficient for depth x=0, k is derived from a family of Crank's theoretical... | https://en.wikipedia.org/wiki?curid=2188925 |
Phosphorus tribromide (data page) This page provides supplementary chemical data on phosphorus tribromide. External MSDS sheets: Except where noted otherwise, data relate to standard ambient temperature and pressure. | https://en.wikipedia.org/wiki?curid=2189362 |
Drinking bird Drinking birds, also known as insatiable birdies, dunking birds, drinky birds, water birds or dipping birds, are toy heat engines that mimic the motions of a bird drinking from a water source. They are sometimes incorrectly considered examples of a perpetual motion device. A drinking bird consists of two ... | https://en.wikipedia.org/wiki?curid=2189384 |
Drinking bird It may be dangerous to people with pre-existing heart, liver, or nervous system conditions and is a suspected carcinogen. The drinking bird is a heat engine that exploits a temperature difference to convert heat energy to a pressure difference within the device, and performs mechanical work. Like all heat... | https://en.wikipedia.org/wiki?curid=2189384 |
Drinking bird These include: By considering the difference between the wet and dry bulb temperatures, it is possible to develop a mathematical expression to calculate the maximum work that can be produced from a given amount of water "drunk". Such analysis is based on the definition of the Carnot heat engine efficiency... | https://en.wikipedia.org/wiki?curid=2189384 |
Drinking bird The book explained the "insatiable" mechanism: "Since the headtube's temperature becomes lower than that of the tail reservoir, this causes a drop in the pressure of the saturated vapours in the head-tube ..." It was said in Shanghai, China, that when Albert Einstein and his wife, Elsa, arrived in Shangha... | https://en.wikipedia.org/wiki?curid=2189384 |
Drinking bird They have also had minor appearances in several movies and TV shows, including the Woody Allen movie "Sleeper", the 1979 science fiction film "Alien" (also referenced in "Alien 3 and "), the 1989 comedy "When Harry Met Sally...", the 2008 film "Max Payne", the 2010 film "Megamind", and episodes of the Ame... | https://en.wikipedia.org/wiki?curid=2189384 |
Drinking bird They are referred to as "dippy birds" and are perhaps used to symbolize such a thing due to Romeril's opinion of drinking birds being that they are insane for their uselessness and repeatability. In 2003 an alternative mechanism was devised by Nadine Abraham and Peter Palffy-Muhoray of Ohio, USA, that uti... | https://en.wikipedia.org/wiki?curid=2189384 |
Drinking bird Although a small drop in temperature may occur due to evaporative cooling, this does not contribute to the motion of the bird. The device operates relatively slowly with 7 hours 22 minutes being the average cycle time measured. | https://en.wikipedia.org/wiki?curid=2189384 |
Microstructure is the very small scale structure of a material analogy to a subsection of the big picture, defined as the structure of a prepared surface of material as revealed by an optical microscope above 25× magnification. The microstructure of a material (such as metals, polymers, ceramics or composites) can stro... | https://en.wikipedia.org/wiki?curid=2189901 |
Microstructure Examples include metallic bonds, covalent bonds, ionic bonds, and weak bonds. Among the weak bonds, there is a distinction between polar bonds or hydrophilic bonds (hydrogen bonds and van der Waals bonds) and nonpolar or hydrophobic bonds. From these properties will come the spatial form of the associate... | https://en.wikipedia.org/wiki?curid=2189901 |
Microstructure They act over long distances but with less intensity than strong bonds. Among them, for example, are van der Waals bonds between molecules and hydrogen bonds between water molecules in liquid water and ice. These bonds are found in all biological materials, certain hydrated minerals, polymers, and some m... | https://en.wikipedia.org/wiki?curid=2189901 |
Microstructure Zinc and lead are two common metals which form large crystals (grains) visible to the naked eye. The atoms in each grain are organized into one of seven 3d stacking arrangements or crystal lattices (cubic, tetrahedral, hexagonal, monoclinic, triclinic, rhombohedral and orthorhombic). The direction of ali... | https://en.wikipedia.org/wiki?curid=2189901 |
Microstructure However, nanoindentation can be used for determination of local microstructural properties of homogeneous as well as heterogeneous materials. Microstructures can also be characterized using high-order statistical models through which a set of complicated statistical properties are extracted from the imag... | https://en.wikipedia.org/wiki?curid=2189901 |
Microstructure Pores with large coordination number (surrounded by many particles) tend to grow during the thermal process. This is caused by the thermal energy being converted to a driving force for the growth of the particles which will induce the growth of the pore as the high coordination number prohibits the growt... | https://en.wikipedia.org/wiki?curid=2189901 |
Microstructure Hot isostatic pressing (HIP) is a manufacturing process, used to reduce the porosity of metals and increase the density of many ceramic materials. This improves the material's mechanical properties and workability. The HIP process exposes the desired material to an isostatic gas pressure as well as high ... | https://en.wikipedia.org/wiki?curid=2189901 |
Matrix-assisted laser desorption/ionization In mass spectrometry, matrix-assisted laser desorption/ionization (MALDI) is an ionization technique that uses a laser energy absorbing matrix to create ions from large molecules with minimal fragmentation. It has been applied to the analysis of biomolecules (biopolymers such... | https://en.wikipedia.org/wiki?curid=2190535 |
Matrix-assisted laser desorption/ionization The tryptophan was absorbing the laser energy and helping to ionize the non-absorbing alanine. Peptides up to the 2843 Da peptide melittin could be ionized when mixed with this kind of "matrix". The breakthrough for large molecule laser desorption ionization came in 1987 when... | https://en.wikipedia.org/wiki?curid=2190535 |
Matrix-assisted laser desorption/ionization The matrix consists of crystallized molecules, of which the three most commonly used are 3,5-dimethoxy-4-hydroxycinnamic acid (sinapinic acid), α-cyano-4-hydroxycinnamic acid (α-CHCA, alpha-cyano or alpha-matrix) and 2,5-dihydroxybenzoic acid (DHB). A solution of one of these... | https://en.wikipedia.org/wiki?curid=2190535 |
Matrix-assisted laser desorption/ionization The matrix solution is mixed with the analyte (e.g. protein-sample). A mixture of water and organic solvent allows both hydrophobic and water-soluble (hydrophilic) molecules to dissolve into the solution. This solution is spotted onto a MALDI plate (usually a metal plate desi... | https://en.wikipedia.org/wiki?curid=2190535 |
Matrix-assisted laser desorption/ionization As mentioned above, acid-base like reactions are often utilized to ionize the sample, however, molecules with conjugated pi systems, such as naphthalene like compounds, can also serve as an electron acceptor and thus a matrix for MALDI/TOF. This is particularly useful in stud... | https://en.wikipedia.org/wiki?curid=2190535 |
Matrix-assisted laser desorption/ionization MALDI techniques typically employ the use of UV lasers such as nitrogen lasers (337 nm) and frequency-tripled and quadrupled (355 nm and 266 nm respectively). Infrared laser wavelengths used for infrared MALDI include the 2.94 μm , mid-IR optical parametric oscillator, and 10... | https://en.wikipedia.org/wiki?curid=2190535 |
Matrix-assisted laser desorption/ionization MALDI-FT-ICR MS has been demonstrated to be a useful technique where high resolution MALDI-MS measurements are desired. Atmospheric pressure (AP) matrix-assisted laser desorption/ionization (MALDI) is an ionization technique (ion source) that in contrast to vacuum MALDI opera... | https://en.wikipedia.org/wiki?curid=2190535 |
Matrix-assisted laser desorption/ionization These systems are called single particle mass spectrometers (SPMS). The sample may optionally be mixed with a MALDI matrix prior to aerosolization. The laser is fired at the matrix crystals in the dried-droplet spot. The matrix absorbs the laser energy and it is thought that ... | https://en.wikipedia.org/wiki?curid=2190535 |
Matrix-assisted laser desorption/ionization The gas phase proton transfer model, implemented as the coupled physical and chemical dynamics (CPCD) model, of UV laser MALDI postulates primary and secondary processes leading to ionization. Primary processes involve initial charge separation through absorption of photons b... | https://en.wikipedia.org/wiki?curid=2190535 |
Matrix-assisted laser desorption/ionization The model quantitatively predicts the increase in total ion intensity as a function of the concentration and proton affinity of the analytes, and the ion-to-neutral ratio as a function of the laser fluences. This model also suggests that metal ion adducts (e.g., [M+Na] or [M+... | https://en.wikipedia.org/wiki?curid=2190535 |
Matrix-assisted laser desorption/ionization Using sinapinic acid, 4-HCCA and DHB as matrices, S. Martin studied loss of sialic acid in glycosylated peptides by metastable decay in MALDI/TOF in linear mode and reflector mode. A group at Shimadzu Corporation derivatized the sialic acid by an amidation reaction as a way t... | https://en.wikipedia.org/wiki?curid=2190535 |
Matrix-assisted laser desorption/ionization Polymers with polydispersity greater than 1.2 are difficult to characterize with MALDI due to the signal intensity discrimination against higher mass oligomers. A good matrix for polymers is dithranol or AgTFA. The sample must first be mixed with dithranol and the AgTFA added... | https://en.wikipedia.org/wiki?curid=2190535 |
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