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Jan Van Deemter
Jan Jozef van Deemter (31 March 1918 – 10 October 2004) was a Dutch physicist and engineer known for the Van Deemter equation in chromatography. He obtained his doctorate in physics from the University of Amsterdam in June of 1950. Starting in 1947 he began work for Royal Dutch Shell as a researcher and it was there that he developed and published his article in 1956. Van Deemter equation The van Deemter equation relates the resolving power of a chromatographic column to the various flow and kinetic parameters which cause peak broadening through : HETP = A + \frac + (C_s +C_m)\cdot u Where HETP is the height equivalent theoretical plate, A is the eddy-diffusion parameter, B is the longitudinal diffusion coefficient of the eluting material in the longitudinal direction, C is the resistance to mass transfer coefficient of the analyte between mobile and stationary phase, and ''u'' is the linear velocity Velocity is the directional speed of an object in motion as an i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Royal Dutch Shell
Shell plc is a British multinational oil and gas company headquartered in London, England. Shell is a public limited company with a primary listing on the London Stock Exchange (LSE) and secondary listings on Euronext Amsterdam and the New York Stock Exchange. It is one of the oil and gas " supermajors" and by revenue and profits is consistently one of the largest companies in the world. Measured by both its own emissions, and the emissions of all the fossil fuels it sells, Shell was the ninth-largest corporate producer of greenhouse gas emissions in the period 1988–2015. Shell was formed in 1907 through the merger of Royal Dutch Petroleum Company of the Netherlands and The "Shell" Transport and Trading Company of the United Kingdom. The combined company rapidly became the leading competitor of the American Standard Oil and by 1920 Shell was the largest producer of oil in the world. Shell first entered the chemicals industry in 1929. Shell was one of the " Seven Sisters" w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Diffusion Coefficient
Diffusivity, mass diffusivity or diffusion coefficient is a proportionality constant between the molar flux due to molecular diffusion and the gradient in the concentration of the species (or the driving force for diffusion). Diffusivity is encountered in Fick's law and numerous other equations of physical chemistry. The diffusivity is generally prescribed for a given pair of species and pairwise for a multi-species system. The higher the diffusivity (of one substance with respect to another), the faster they diffuse into each other. Typically, a compound's diffusion coefficient is ~10,000× as great in air as in water. Carbon dioxide in air has a diffusion coefficient of 16 mm2/s, and in water its diffusion coefficient is 0.0016 mm2/s. Diffusivity has dimensions of length2 / time, or m2/s in SI units and cm2/s in CGS units. Temperature dependence of the diffusion coefficient Solids The diffusion coefficient in solids at different temperatures is generally found ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
People From Kleve
A person ( : people) is a being that has certain capacities or attributes such as reason, morality, consciousness or self-consciousness, and being a part of a culturally established form of social relations such as kinship, ownership of property, or legal responsibility. The defining features of personhood and, consequently, what makes a person count as a person, differ widely among cultures and contexts. In addition to the question of personhood, of what makes a being count as a person to begin with, there are further questions about personal identity and self: both about what makes any particular person that particular person instead of another, and about what makes a person at one time the same person as they were or will be at another time despite any intervening changes. The plural form "people" is often used to refer to an entire nation or ethnic group (as in "a people"), and this was the original meaning of the word; it subsequently acquired its use as a plural form of p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
2004 Deaths
This is a list of deaths of notable people, organised by year. New deaths articles are added to their respective month (e.g., Deaths in ) and then linked here. 2022 2021 2020 2019 2018 2017 2016 2015 2014 2013 2012 2011 2010 2009 2008 2007 2006 2005 2004 2003 2002 2001 2000 1999 1998 1997 1996 1995 1994 1993 1992 1991 1990 1989 1988 1987 See also * Lists of deaths by day * Deaths by year {{DEFAULTSORT:deaths by year ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
1918 Births
This year is noted for the end of the First World War, on the eleventh hour of the eleventh day of the eleventh month, as well as for the Spanish flu pandemic that killed 50–100 million people worldwide. Events Below, the events of World War I have the "WWI" prefix. January * January – 1918 flu pandemic: The "Spanish flu" (influenza) is first observed in Haskell County, Kansas. * January 4 – The Finnish Declaration of Independence is recognized by Soviet Russia, Sweden, Germany and France. * January 9 – Battle of Bear Valley: U.S. troops engage Yaqui Native American warriors in a minor skirmish in Arizona, and one of the last battles of the American Indian Wars between the United States and Native Americans. * January 15 ** The keel of is laid in Britain, the first purpose-designed aircraft carrier to be laid down. ** The Red Army (The Workers and Peasants Red Army) is formed in the Russian SFSR and Soviet Union. * January 18 - The Historic Concert for ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Linear Velocity
Velocity is the directional speed of an object in motion as an indication of its rate of change in position as observed from a particular frame of reference and as measured by a particular standard of time (e.g. northbound). Velocity is a fundamental concept in kinematics, the branch of classical mechanics that describes the motion of bodies. Velocity is a physical vector quantity; both magnitude and direction are needed to define it. The scalar absolute value (magnitude) of velocity is called , being a coherent derived unit whose quantity is measured in the SI (metric system) as metres per second (m/s or m⋅s−1). For example, "5 metres per second" is a scalar, whereas "5 metres per second east" is a vector. If there is a change in speed, direction or both, then the object is said to be undergoing an ''acceleration''. Constant velocity vs acceleration To have a ''constant velocity'', an object must have a constant speed in a constant direction. Constant direction con ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mass Transfer Coefficient
In engineering, the mass transfer coefficient is a diffusion rate constant that relates the mass transfer rate, mass transfer area, and concentration change as driving force: k_c = \frac Where: *k_c is the mass transfer coefficient ol/(s·m2)/(mol/m3) or m/s *\dot_A is the mass transfer rate ol/s*A is the effective mass transfer area 2*\Delta c_A is the driving force concentration difference ol/m3 This can be used to quantify the mass transfer between phases, immiscible and partially miscible fluid mixtures (or between a fluid and a porous solide.g.: during adsorption process.). Quantifying mass transfer allows for design and manufacture of separation process equipment that can meet specified requirements, estimate what will happen in real life situations (chemical spill), etc. Mass transfer coefficients can be estimated from many different theoretical equations, correlations, and analogies that are functions of material properties, intensive properties and flow regime ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eddy-diffusion
Eddy diffusion, eddy dispersion, or turbulent diffusion is a process by which substances are mixed in the atmosphere, the ocean or in any fluid system due to eddy motion. In other words, it is mixing that is caused by eddies that can vary in size from subtropical ocean gyres down to the small Kolmogorov microscales. The concept of turbulence or turbulent flow causes eddy diffusion to occur. The theory of eddy diffusion was first developed by Sir Geoffrey Ingram Taylor. In laminar flows, material properties (salt, heat, humidity, aerosols etc.) are mixed by random motion of individual molecules (see molecular diffusion). By a purely probabilistic argument, the net flux of molecules from high concentration area to low concentration area is higher than the flux in the opposite direction. This down-gradient flux equilibrates the concentration profile over time. This phenomenon is called molecular diffusion, and its mathematical aspect is captured by the diffusion equation. In tu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
University Of Groningen
The University of Groningen (abbreviated as UG; nl, Rijksuniversiteit Groningen, abbreviated as RUG) is a public research university of more than 30,000 students in the city of Groningen in the Netherlands. Founded in 1614, the university is the second oldest in the country (after Leiden) and one of the most traditional and prestigious universities in the Netherlands. The institution has been consistently ranked among the top 100 universities in the world, according to leading ranking tables. In the 2022 Aggregate Ranking of Top Universities, RUG is ranked fourth in the Netherlands. The University of Groningen has eleven faculties, nine graduate schools, 27 research centres and institutes, and more than 175-degree programmes. The university's alumni and faculty include Johann Bernoulli, Aletta Jacobs, four Nobel Prize winners, nine Spinoza Prize winners, one Stevin Prize winner, various members of the Dutch royal family, several politicians, the first president of the Europea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Height Equivalent Theoretical Plate
A theoretical plate in many separation processes is a hypothetical zone or stage in which two phases, such as the liquid and vapor phases of a substance, establish an Vapor–liquid equilibrium, equilibrium with each other. Such equilibrium stages may also be referred to as an equilibrium stage, ideal stage, or a theoretical tray. The performance of many separation processes depends on having series of equilibrium stages and is enhanced by providing more such stages. In other words, having more theoretical plates increases the efficiency of the separation process be it either a distillation, absorption (chemistry), absorption, chromatography, chromatographic, adsorption or similar process. Applications The concept of theoretical plates and trays or equilibrium stages is used in the design of many different types of separation. Distillation columns The concept of theoretical plates in designing distillation processes has been discussed in many reference texts. Any physical device t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chem
Chem may refer to: * Chemistry practical waali mam * Chemistry *Chemical * ''Chem'' (journal), a scientific journal published by Cell Press *Post apocalyptic slang for "drugs", medicinal or otherwise in the Fallout video game series. In Ancient Egyptian usage: * ''Khem'' (also spelt ''Chem''), the Egyptian word for "black" *Min (god), in the past erroneously named ''Khem'' CHEM may refer to : *A metabolic panel: for instance, CHEM-7, which is the basic metabolic panel * CHEM-DT, a Canadian television channel See also *Chemo (other) Chemo is a prefix meaning ''chemical'' and commonly used as an abbreviation for chemotherapy. Chemo may also refer to: People * Chemo (musician), an English musician now known as Forest DLG * Chemo Soto, a Puerto Rican politician * José del Sol ... * Kemi, a place in Finland {{disambig ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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