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Soret Effect
Thermophoresis (also thermomigration, thermodiffusion, the Soret effect, or the Ludwig–Soret effect) is a phenomenon observed in mixtures of mobile particles where the different particle types exhibit different responses to the force of a temperature gradient. This phenomenon tends to move light molecules to hot regions and heavy molecules to cold regions. The term ''thermophoresis'' most often applies to aerosol mixtures whose mean free path \lambda is comparable to its characteristic length scale L, but may also commonly refer to the phenomenon in all phases of matter. The term ''Soret effect'' normally applies to liquid mixtures, which behave according to different, less well-understood mechanisms than gaseous mixtures. Thermophoresis may not apply to thermomigration in solids, especially multi-phase alloys. Thermophoretic force The phenomenon is observed at the scale of one millimeter or less. An example that may be observed by the naked eye with good lighting is when the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Temperature Gradient
A temperature gradient is a physical quantity that describes in which direction and at what rate the temperature changes the most rapidly around a particular location. The temperature gradient is a dimensional quantity expressed in units of degrees (on a particular temperature scale) per unit length. The SI unit is kelvin per meter (K/m). Temperature gradients in the atmosphere are important in the atmospheric sciences (meteorology, climatology and related fields). Mathematical description Assuming that the temperature ''T'' is an intensive quantity, i.e., a single-valued, continuous and differentiable function of three-dimensional space (often called a scalar field), i.e., that :T=T(x,y,z) where ''x'', ''y'' and ''z'' are the coordinates of the location of interest, then the temperature gradient is the vector quantity defined as :\nabla T = \begin , , \end Physical processes Climatology On a global and annual basis, the dynamics of the atmosphere (and the oceans) ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Field Flow Fractionation
Field-flow fractionation, abbreviated FFF, is a separation technique which does not have a stationary phase. It is similar to liquid chromatography as it works on dilute solutions or suspensions of the solute. Separation is achieved by applying a field (hydraulic, centrifugal, thermal, electric, magnetic, gravitational, ...) perpendicular to the direction of transport of the sample which is pumped through a long and narrow channel. The field exerts a force on the sample components concentrating them towards one of the channel walls, which is called accumulation wall. The force interacts with a property of the sample on which then the separation occurs, in other words on their differing "mobilities" under the force exerted by the field. As an example, for the hydraulic, or cross-flow FFF method, the property driving separation is the translational diffusion coefficient or the hydrodynamic size. For a thermal field (heating one wall and cooling the other), it is the ratio of the t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Maxwell–Stefan Diffusion
The Maxwell–Stefan diffusion (or Stefan–Maxwell diffusion) is a model for describing diffusion in multicomponent systems. The equations that describe these transport processes have been developed independently and in parallel by James Clerk MaxwellJ. C. Maxwell: ''On the dynamical theory of gases'', The Scientific Papers of J. C. Maxwell, 1965, 2, 26–78. for dilute gases and Josef StefanJ. Stefan: ''Über das Gleichgewicht und Bewegung, insbesondere die Diffusion von Gemischen'', Sitzungsberichte der Kaiserlichen Akademie der Wissenschaften Wien, 2te Abteilung a, 1871, 63, 63-124. for liquids. The Maxwell–Stefan equation is \frac = \nabla \ln a_i = \sum_^ = \sum_^ * ∇: vector differential operator * χ: Mole fraction * μ: Chemical potential * a: Activity * i, j: Indexes for component i and j * n: Number of components * \mathfrak_: Maxwell–Stefan-diffusion coefficient * \vec v_i: Diffusion velocity of component i * c_i: Molar concentration of component i * c: Total ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dufour Effect
The Dufour effect is the energy flux due to a mass concentration gradient occurring as a coupled effect of irreversible processes, named after L. Dufour. It is the reciprocal phenomenon to the Soret effect Thermophoresis (also thermomigration, thermodiffusion, the Soret effect, or the Ludwig–Soret effect) is a phenomenon observed in mixtures of mobile particles where the different particle types exhibit different responses to the force of a temper .... The concentration gradient results in a temperature change. For binary liquid mixtures, the Dufour effect is usually considered negligible, whereas in binary gas mixtures the effect can be significant. References Thermodynamics {{thermodynamics-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Deposition (aerosol Physics)
In the physics of aerosols, deposition is the process by which aerosol particles collect or deposit themselves on solid surfaces, decreasing the concentration of the particles in the air. It can be divided into two sub-processes: ''dry'' and ''wet'' deposition. The rate of deposition, or the deposition velocity, is slowest for particles of an intermediate size. Mechanisms for deposition are most effective for either very small or very large particles. Very large particles will settle out quickly through sedimentation (settling) or impaction processes, while Brownian diffusion has the greatest influence on small particles. This is because very small particles coagulate in few hours until they achieve a diameter of 0.5 micrometres. At this size they no longer coagulate. This has a great influence in the amount of PM-2.5 present in the air. ''Deposition velocity'' is defined from , where is flux density, is deposition velocity and is concentration. In gravitational depositi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Microscale Thermophoresis
Microscale thermophoresis (MST) is a technology for the Biophysics, biophysical analysis of interactions between biomolecules. Microscale thermophoresis is based on the detection of a temperature-induced change in fluorescence of a target as a function of the concentration of a non-fluorescent ligand. The observed change in fluorescence is based on two distinct effects. On the one hand it is based on a temperature related intensity change (TRIC) of the fluorescent probe, which can be affected by binding events. On the other hand, it is based on thermophoresis, the directed movement of particles in a microscopic temperature gradient. Any change of the chemical microenvironment of the fluorescent probe, as well as changes in the solvation shell#Hydration shells of proteins, hydration shell of biomolecules result in a relative change of the fluorescence detected when a temperature gradient is applied and can be used to determine dissociation constant, binding affinities. MST allows me ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sydney Chapman (mathematician)
Sydney Chapman (29 January 1888 – 16 June 1970) was a British mathematician and geophysicist. His work on the kinetic theory of gases, solar-terrestrial physics, and the Earth's ozone layer has inspired a broad range of research over many decades. Education and early life Chapman was born in Eccles, near Salford in England and began his advanced studies at a technical institute, now the University of Salford, in 1902. In 1904 at age 16, Chapman entered the University of Manchester. He competed for a scholarship to the university offered by his home county, and was the last student selected. Chapman later reflected, "I sometimes wonder what would have happened if I'd hit one place lower." He initially studied engineering in the department headed by Osborne Reynolds. Chapman was taught mathematics by Horace Lamb, the Beyer professor of mathematics, and J. E. Littlewood, who came from Cambridge in Chapman's final year at Manchester. Although he graduated with an engineerin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nature (magazine)
''Nature'' is a British weekly scientific journal founded and based in London, England. As a multidisciplinary publication, ''Nature'' features peer-reviewed research from a variety of academic disciplines, mainly in science and technology. It has core editorial offices across the United States, continental Europe, and Asia under the international scientific publishing company Springer Nature. ''Nature'' was one of the world's most cited scientific journals by the Science Edition of the 2019 ''Journal Citation Reports'' (with an ascribed impact factor of 42.778), making it one of the world's most-read and most prestigious academic journals. , it claimed an online readership of about three million unique readers per month. Founded in autumn 1869, ''Nature'' was first circulated by Norman Lockyer and Alexander Macmillan as a public forum for scientific innovations. The mid-20th century facilitated an editorial expansion for the journal; ''Nature'' redoubled its efforts in explan ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aerosol
An aerosol is a suspension (chemistry), suspension of fine solid particles or liquid Drop (liquid), droplets in air or another gas. Aerosols can be natural or Human impact on the environment, anthropogenic. Examples of natural aerosols are fog or mist, dust, forest exudates, and geyser steam. Examples of anthropogenic aerosols include particulate air pollutants, mist from the discharge at Hydroelectric dam, hydroelectric dams, Irrigation, irrigation mist, Perfume, perfume from atomizers, smoke, steam from a kettle, Pesticide, sprayed pesticides, and medical treatments for respiratory illnesses. When a person inhales the contents of a vape pen or e-cigarette, they are inhaling an Human impact on the environment, anthropogenic aerosol. The liquid or solid particles in an aerosol have diameters typically less than micrometre, 1 μm (larger particles with a significant settling speed make the mixture a Suspension (chemistry), suspension, but the distinction is not clear-cut) ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
James Clerk Maxwell
James Clerk Maxwell (13 June 1831 – 5 November 1879) was a Scottish mathematician and scientist responsible for the classical theory of electromagnetic radiation, which was the first theory to describe electricity, magnetism and light as different manifestations of the same phenomenon. Maxwell's equations for electromagnetism have been called the " second great unification in physics" where the first one had been realised by Isaac Newton. With the publication of "A Dynamical Theory of the Electromagnetic Field" in 1865, Maxwell demonstrated that electric and magnetic fields travel through space as waves moving at the speed of light. He proposed that light is an undulation in the same medium that is the cause of electric and magnetic phenomena. (This article accompanied an 8 December 1864 presentation by Maxwell to the Royal Society. His statement that "light and magnetism are affections of the same substance" is at page 499.) The unification of light and electrical ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Charles Soret
Charles Soret (born 23 September 1854, Geneva, Switzerland; died 4 April 1904) was a Swiss physicist and chemist. He is known for his work on thermodiffusion (the so-called ''Soret effect''). Life Charles Soret was the son of Jacques-Louis Soret, professor of physical medicine at University of Geneva, and Clémentine Odier. In 1872, Charles graduated from an art college in Geneva and, two years later, he added a degree in mathematics. In addition, he also attended lectures in physics and other sciences. He continued studies in mathematics at the Sorbonne, where he received his MA in 1876. He believed that a good physicist is first of all a good mathematician; therefore, only afterwards he focused on physics in which he obtained a master's degree two years later. Soon, he was offered a place in the Department of crystallography and mineralogy at the University of Geneva. There, in 1879, he became a lecturer and a full professor in 1881. In 1879, he published his first discussi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carl Ludwig
Carl Friedrich Wilhelm Ludwig (; 29 December 1816 – 23 April 1895) was a German physician and physiologist. His work as both a researcher and teacher had a major influence on the understanding, methods and apparatus used in almost all branches of physiology. In 1842, Ludwig became a professor of physiology and in 1846 of comparative anatomy. From professorships in Zurich and Vienna he went in 1865 to the University of Leipzig and developed there the Physiological Institute, designated today after him: Carl Ludwig Institute of Physiology.Current website of the Carl-Ludwig-Institute of Physiology http://cliphys.uniklinikum-leipzig.de/ Ludwig researched several topics such as the physiology of blood pressure, urinary excretion, and anesthesia. He received the Copley Medal in 1884 for his research. In 1869, he was elected a foreign member of the Royal Swedish Academy of Sciences. He is credited for inventing the stromuhr. Since 1932, the Carl Ludwig Honorary Medal is awarded b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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