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Analytical Ultracentrifugation
Analytical ultracentrifugation is an analytical technique which combines an ultracentrifuge with optical monitoring systems. In an analytical ultracentrifuge (commonly abbreviated as AUC), a sample’s sedimentation profile is monitored in real time by an optical detection system. The sample is detected via ultraviolet light absorption and/or interference optical refractive index sensitive system, monitored by light-sensitive diode array or by film in the older machines. The operator can thus observe the change of sample concentration versus the axis of the rotation profile with time as a result of the applied centrifugal field. With modern instrumentation, these observations are electronically digitized and stored for further mathematical analysis. The information that can be obtained from an analytical ultracentrifuge includes the gross shape of macromolecules, conformational changes in macromolecules, and size distributions of macromolecules. With AUC it is possible to gain infor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Analytical Centrifugation
Analytic or analytical may refer to: Chemistry * Analytical chemistry, the analysis of material samples to learn their chemical composition and structure * Analytical technique, a method that is used to determine the concentration of a chemical compound or chemical element * Analytical concentration Mathematics * Abstract analytic number theory, the application of ideas and techniques from analytic number theory to other mathematical fields * Analytic combinatorics, a branch of combinatorics that describes combinatorial classes using generating functions * Analytic element method, a numerical method used to solve partial differential equations * Analytic expression or analytic solution, a mathematical expression using well-known operations that lend themselves readily to calculation * Analytic geometry, the study of geometry based on numerical coordinates rather than axioms * Analytic number theory, a branch of number theory that uses methods from mathematical analysis Mathemati ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Laboratory Techniques
A laboratory (; ; colloquially lab) is a facility that provides controlled conditions in which scientific or technological research, experiments, and measurement may be performed. Laboratories are found in a variety of settings such as schools, universities, privately owned research institutions, corporate research and testing facilities, government regulatory and forensic investigation centers, physicians' offices, clinics, hospitals, regional and national referral centers, and even occasionally personal residences. Overview The organisation and contents of laboratories are determined by the differing requirements of the specialists working within. A physics laboratory might contain a particle accelerator or vacuum chamber, while a metallurgy laboratory could have apparatus for casting or refining metals or for testing their strength. A chemist or biologist might use a wet laboratory, while a psychologist's laboratory might be a room with one-way mirrors and hidden cameras in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Analytical Chemistry
Analytical skill, Analytical chemistry studies and uses instruments and methods to Separation process, separate, identify, and Quantification (science), quantify matter. In practice, separation, identification or quantification may constitute the entire analysis or be combined with another method. Separation isolates analytes. Qualitative inorganic analysis, Qualitative analysis identifies analytes, while Quantitative analysis (chemistry), quantitative analysis determines the numerical amount or concentration. Analytical chemistry consists of classical, wet chemistry, wet chemical methods and modern analytical techniques. Classical qualitative methods use separations such as Precipitation (chemistry), precipitation, Extraction (chemistry), extraction, and distillation. Identification may be based on differences in color, odor, melting point, boiling point, solubility, radioactivity or reactivity. Classical quantitative analysis uses mass or volume changes to quantify amount. Ins ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Centrifuges
A centrifuge is a device that uses centrifugal force to subject a specimen to a specified constant force - for example, to separate various components of a fluid. This is achieved by spinning the fluid at high speed within a container, thereby separating fluids of different densities (e.g. cream from milk) or liquids from solids. It works by causing denser substances and particles to move outward in the radial direction. At the same time, objects that are less dense are displaced and moved to the centre. In a laboratory centrifuge that uses sample tubes, the radial acceleration causes denser particles to settle to the bottom of the tube, while low-density substances rise to the top. A centrifuge can be a very effective filter that separates contaminants from the main body of fluid. Industrial scale centrifuges are commonly used in manufacturing and waste processing to sediment suspended solids, or to separate immiscible liquids. An example is the cream separator found in dairie ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Zippe-type Centrifuge
The Zippe-type centrifuge is a gas centrifuge designed to enrich the rare fissile isotope uranium-235 (235U) from the mixture of isotopes found in naturally occurring uranium compounds. The Isotope separation, isotopic separation is based on the slight difference in mass of the isotopes. The Zippe design was originally developed in the Soviet Union by a team led by 60 Austrian and German scientists and engineers captured after World War II, working in detention. In the West (and now generally) the type is known by the name of the man who recreated the technology after his return to the West in 1956, based on his recollection of his work in (and contributions to) the Soviet program, Gernot Zippe. To the extent that it might be referred to in Soviet/Russian usage by any one person's name, it was known (at least at a somewhat earlier stage of development) as a Kamenev centrifuge (after Evgeni Kamenev).Oleg Bukharin, OlegRussia’s Gaseous Centrifuge Technology and Uranium Enrichment Co ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Buoyant Density Ultracentrifugation
Buoyant density centrifugation (also isopycnic centrifugation or equilibrium density-gradient centrifugation) uses the concept of buoyancy to separate molecules in solution by their differences in density. Implementation Historically a cesium chloride (CsCl) solution was often used, but more commonly used density gradients are sucrose or Percoll. This application requires a solution with high density and yet relatively low viscosity, and CsCl suits it because of its high solubility in water, high density owing to the large mass of Cs, as well as low viscosity and high stability of CsCl solutions. The sample is put on top of the solution, and then the tube is spun at a very high speed for an extended time, at times lasting days. The CsCl molecules become densely packed toward the bottom, so a continuous gradient of layers of different densities (and CsCl concentrations) form. Since the original solution was approximately the same density, they go to a level where their density and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Differential Centrifugation
In biochemistry and cell biology, differential centrifugation (also known as differential velocity centrifugation) is a common procedure used to separate organelles and other sub-cellular particles based on their sedimentation rate. Although often applied in biological analysis, differential centrifugation is a general technique also suitable for crude purification of non-living suspended particles (e.g. nanoparticles, colloidal particles, viruses). In a typical case where differential centrifugation is used to analyze cell-biological phenomena (e.g. organelle distribution), a tissue sample is first lysed to break the cell membranes and release the organelles and cytosol. The lysate is then subjected to repeated centrifugations, where particles that sediment sufficiently quickly at a given centrifugal force for a given time form a compact "pellet" at the bottom of the centrifugation tube. After each centrifugation, the ''supernatant'' (non-pelleted solution) is removed from t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Theodor Svedberg
Theodor Svedberg (30 August 1884 – 25 February 1971; also known as The Svedberg) was a Swedish chemist and Nobel laureate for his research on colloids and proteins using the ultracentrifuge. Svedberg was active at Uppsala University from the mid-1900s to late 1940s. While at Uppsala, Svedberg started as a docent before becoming the university's physical chemistry head in 1912. After leaving Uppsala in 1949, Svedberg was in charge of the Gustaf Werner Institute until 1967. Apart from his 1926 Nobel Prize, Svedberg was named a Foreign Member of the Royal Society in 1944 and became part of the National Academy of Sciences in 1945. Early life and education Svedberg was born in Valbo, Sweden on 30 August 1884. He was the son of Augusta Alstermark and Elias Svedberg. Growing up, Svedberg enjoyed botany and other branches of science. While in grammar school, Svedberg conducted individual laboratorial research and performed scientific demonstrations. For his post-secondary educati ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gas Centrifuge
A gas centrifuge is a device that performs isotope separation of gases. A centrifuge relies on the principles of centrifugal force accelerating molecules so that particles of different masses are physically separated in a gradient along the radius of a rotating container. A prominent use of gas centrifuges is for the separation of uranium-235 (235U) from uranium-238 (238U). The gas centrifuge was developed to replace the gaseous diffusion method of 235U extraction. High degrees of separation of these isotopes relies on using many individual centrifuges arranged in series that achieve successively higher concentrations. This process yields higher concentrations of 235U while using significantly less energy compared to the gaseous diffusion process. History Suggested in 1919, the centrifugal process was first successfully performed in 1934. American scientist Jesse Beams and his team at the University of Virginia developed the process by separating two isotopes of chlorine, chlori ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ultracentrifuge
An ultracentrifuge is a centrifuge optimized for spinning a rotor at very high speeds, capable of generating acceleration as high as (approx. ). There are two kinds of ultracentrifuges, the preparative and the analytical ultracentrifuge. Both classes of instruments find important uses in molecular biology, biochemistry, and polymer science.Susan R. Mikkelsen & Eduardo Cortón. Bioanalytical Chemistry, Ch. 13. Centrifugation Methods. John Wiley & Sons, Mar 4, 2004, pp. 247-267. History In 1924 Theodor Svedberg built a centrifuge capable of generating 7,000 g (at 12,000 rpm), and called it the ultracentrifuge, to juxtapose it with the Ultramicroscope that had been developed previously. In 1925-1926 Svedberg constructed a new ultracentrifuge that permitted fields up to 100,000 g (42,000 rpm). Modern ultracentrifuges are typically classified as allowing greater than 100,000 g. Svedberg won the Nobel Prize in Chemistry in 1926 for his research on colloids and proteins using the ultrac ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Atomic Mass Unit
The dalton or unified atomic mass unit (symbols: Da or u, respectively) is a unit of mass defined as of the mass of an unbound neutral atom of carbon-12 in its nuclear and electronic ground state and at rest. It is a non-SI unit accepted for use with SI. The word "unified" emphasizes that the definition was accepted by both IUPAP and IUPAC. The atomic mass constant, denoted , is defined identically. Expressed in terms of , the atomic mass of carbon-12: . Its value in SI units is an experimentally determined quantity. The 2022 CODATA recommended value of the atomic mass constant expressed in the SI base unit kilogram is:This value serves as a conversion factor of mass from daltons to kilograms, which can easily be converted to grams and other metric units of mass. The 2019 revision of the SI redefined the kilogram by fixing the value of the Planck constant (), improving the precision of the atomic mass constant expressed in SI units by anchoring it to fixed physica ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
