Scanning electrochemical microscopy SECM is a specific technique within the broader class of scanning probe microscopy SPM that is used to measure the local electrochemical behavior of liquid solid, liquid ... first Patrick coauthors Barker, Gonsalves, Macpherson, Slevin title Scanning electrochemical microscopy ... between two immiscible electrolyte solutions using scanning electrochemical microscopy SECM Theory ... title Scanning electrochemical microscopy in the 21st century journal Physical Chemistry Chemical ... first Gunther title Imaging Localized Reactivities of Surfaces by Scanning Electrochemical Microscopy ... Electrochemical Microscopy. An Introduction and Principles journal Analytical Chemistry year 1989 volume ... electrochemical signals can be acquired by measuring the current at an ultramicroelectrode UME ..., 2001, Book cite book last Bard first Allen title Scanning Electrochemical Microscopy year 2001 publisher ... Surface Plasmon Resonance Imaging with Scanning Electrochemical Microscopy SECM journal Langmuir year 2004 volume 20 pages 9236 9241 ref Electrochemical scanning tunneling microscope Electrochemical ... first Gunther coauthors Thomas H. Treutler title Combination of an electrochemical tunneling microscope ECSTM and a scanning electrochemical microscope SECM application for tip induced modi cation of self ..., Yan Shen title Scanning Electrochemical Microscopy for Direct Imaging of Reaction Rates journal ... enabled the study of quick or localized electrochemical reactions. The first SECM like experiment ... ref Simultaneous experiments by Allen J. Bard using an Electrochemical Scanning Tunneling Microscope ... of electrochemical microscopy. ref name Bard 1986 cite journal last Bard first Allen coauthors Hsue Yang Liu, Fu Ren F. Fan, Charles W. Lin title Scanning Electrochemical and Tunneling Ultramicroelectrode ... ref The theoretical basis was presented in 1989 by Bard, where he also coined the term Scanning Electrochemical ... title Scanning electrochemical microscopy in the 21st century journal Physical Chemistry Chemical ... more details
involved in generating the resting potential below , that is, there is no actual measurable charge excess in either side. That occurs because the effect of charge on electrochemicalpotential is hugely ...The relatively static membrane potential of quiescent cells is called the resting membrane potential or resting voltage , as opposed to the specific dynamic electrochemical phenomena called action potential and graded membrane potential . Apart from the latter two, which occur in Membrane potential excitable ... potential and dynamic voltage changes like action potential from biophysical point of view all ... ion channel s, ion transporter s, and exchangers. Conventionally, resting membrane potential can ... Any voltage is a difference in electric potential between two points for example, the separation .... The typical resting membrane potential of a cell arises from the separation of potassium ions ... relative permeability for potassium, the resulting membrane potential is almost always close to the potassium reversal potential . But in order for this process to occur, a concentration gradient ... membrane potential across an animal cell s cell membrane plasma membrane , potassium and sodium ... potential may be established by acidification of the inside of a membranous compartment such as the proton pump that generates membrane potential across synaptic vesicle membranes . Citation needed date January 2009 Electroneutrality In most quantitative treatments of membrane potential, such as the derivation ... charge excess in any side of the membrane. So, although there is an electric potential across ... change on electric potential. Generation of the resting potential Cell membranes are typically permeable ..., and others. To simplify the description of the ionic basis of the resting membrane potential, it is most ... to start. Image Membrane potential development.jpg thumb 400px A diagram showing the progression in the development of a membrane potential from a concentration gradient for potassium . span ... more details
File Diagram of zeta potential and slipping planeV2.svg thumb 300px Diagram showing the ionic concentration and potential difference as a function of distance from the charged surface of a particle suspended in a dispersion medium. Zeta potential is a scientific term for electrokinetic potential ref Definition of http goldbook.iupac.org E01968.html electrokinetic potential in IUPAC. Compendium of Chemical ... denoted using the Greek letter zeta , hence potential . From a theoretical viewpoint, zeta potential is electric potential in the interfacial double layer interfacial double layer DL at the location ... potential is the potential difference between the dispersion medium and the stationary layer of fluid ... potential is that its value can be related to the stability of colloidal dispersions e.g., a multivitamin syrup . The zeta potential indicates the degree of repulsion between adjacent, similarly ..., a high zeta potential will confer stability, i.e., the solution or dispersion will resist aggregation. When the potential is low, attraction exceeds repulsion and the dispersion will break and flocculate. So, colloids with high zeta potential negative or positive are electrically stabilized while colloids .... citation needed date November 2011 class wikitable Zeta potential mV Stability behavior of the colloid ... Moderate stability from 40 to 60 Good stability more than 61 Excellent stability Zeta potential ..., zeta potential is not equal to the Stern potential or electric surface potential in the double .... Nevertheless, zeta potential is often the only available path for characterization of double layer properties. Zeta potential should not be confused with electrode potential or electrochemicalpotential because electrochemical reactions are generally not involved in the development of zeta potential . Measurement of zeta potential Zeta potential is not measurable directly but it can be calculated ... for calculation of zeta potential. Electrokinetic phenomena main Electrokinetic phenomena Electrophoresis ... more details
vector potential . Chemistry main Electrode potentials In an Electrochemistry Electrochemical ...In physics , chemistry and biology , a potential gradient is the local derivative rate of change of the potential with respect to displacement, i.e. spatial derivative, or gradient. This quantity frequently occurs in equations of physical processes because it leads to some form of flux . In electrical engineering it refers specifically to electric potential gradient, which is equal to the electric field . Definition Elementary algebra calculus Fundamentally the expression for a potential gradient F in one dimension takes the form ref Essential Principles of Physics, P.M. Whelan, M.J. Hodgeson, 2nd ... is some type of potential , and x is displacement not distance , in the x direction. In the limit of infinitesimal ... differentials math F frac rm d phi rm d x , math In three dimensions, the resultant potential gradient is the sum of the potential gradients in each direction, in Cartesian coordinates math bold F bold ... , math bold F nabla phi , math Vector calculus The mathematical nature of a potential gradient arises ... problems, the scalar field is the potential, and the vector field is a force field, or flux current ... can be shown to be conservative, it is equal to the gradient in gravitational potential math mathbf g nabla Phi , math Notice the opposite signs between gravitational field and potential because as the potential gradient and field are opposite in direction, as the potential gradient increases, the gravitational ... field has identical properties to the gravitational field it is the gradient of the electric potential ... to the gradient in electric potential, a time dependent term must be added ref Introduction to Electrodynamics ... , the Standard conditions for temperature and pressure standard electric potential difference is ref ... standard conditions . The potential gradient is relatively abrupt, since there is an almost definite boundary between the metal and solution, hence the term interface. Biology In biology , potential ... more details
to chemical energy through electrochemical reactions. The similar term chemical potential ...about a form of energy in physics the statistical method Potential energy statistics Classical mechanics Refimprove date June 2010 In physics , potential energy is the energy of a body or a system due ... potential energy was coined by the 19th century Scottish engineer and physicist William Rankine ... ref Overview Potential energy exists when a force acts upon an object that tends to restore it to a lower ... disappear. Instead, it is stored as potential energy. If the spring is released or the mass is dropped ... coaster. When the coaster climbs a hill it has potential energy. At the very top of the hill is its maximum potential energy. When the coaster speeds down the hill potential energy turns into kinetic. Kinetic energy is greatest at the bottom. The more formal definition is that potential energy ... position. There are various types of potential energy, each associated with a particular type of force. More specifically, every conservative force gives rise to potential energy. For example, the work of an Elasticity physics elastic force is called elastic potential energy work of the gravitational force is called gravitational potential energy work of the Coulomb force is called electric potential energy work of the strong nuclear force or weak nuclear force acting on the baryon charge physics charge is called nuclear potential energy work of intermolecular forces is called intermolecular potential energy. Chemical potential energy, such as the energy stored in fossil fuels , is the work ... of particles and the potential energy of their mutual positions. As a general rule, the work done by a conservative force F will be math ,W Delta U math where math Delta U math is the change in the potential energy associated with that particular force. Common notations for potential energy are U , V , and E sub p sub . Reference level The potential energy is a function of the state a system is in, and is defined ... more details
Electrochemical energy conversion is a field of energy technology concerned with electrochemical methods of energy conversion and storage like batteries, fuel cells, supercapacitor s and photoelectrochemical energy conversion devices. It is increasingly important in context of automotive propulsion systems. ref http oai.dtic.mil oai oai?verb getRecord&metadataPrefix html&identifier AD0863071 Washington University ref Notes references See also Electromethanogenesis Electrochemical cell Bioelectrochemical reactor Enzymatic biofuel cell Electrofuels Electrohydrogenesis Electrochemical reduction of carbon dioxide Electrochemical engineering Chemotronics Photoelectrochemical reduction of CO2 External links http onlinelibrary.wiley.com doi 10.1002 er.1280 abstract International Journal of Energy Research http www.ece.umd.edu MEMS projects battery.html MSAL http www.nist.gov cnst erg nano eecs.cfm NIST http www.uctm.edu journal j2008 1 2 Budevski 11 18.pdf scientific journal article http smartech.gatech.edu jspui handle 1853 34910 Georgia tech Category Electrochemistry Category Electrochemical engineering Category Energy engineering Category Energy conversion ro Conversia electrochimic a energiei ... more details
In chemistry, an electrochemical reaction mechanism is the step by step sequence of elementary step s, involving at least one outer sphere electron transfer , by which an overall chemical change occurs ref name electromethods Cite book last1 Bard first1 Allen J. author1 link Allen J. Bard last2 Faulkner first2 Larry R. date January 2001 title Electrochemical methods fundamentals and applications publisher John Wiley & Sons Wiley publication place New York isbn 978 0 471 04372 0 url http www.amazon.co.uk gp reader 0471043729 ref sib dp pt reader link accessdate 27 February 2009 ref ref Cite journal doi 10.1021 om700558k volume 26 issue 24 pages 5738 5765 last Geiger first William E. title Organometallic Electrochemistry Origins, Development, and Future journal Organometallics date 2007 11 01 ref . Overview Elementary steps like proton coupled electron transfer and the movement of electrons between an electrode and substrate are special to electrochemical processes. Electrochemical mechanisms are important to all redox chemistry including corrosion , redox active photochemistry including photosynthesis , other biological systems often involving electron transport chain s and other forms of homogeneous and heterogeneous electron transfer. Such reactions are most often studied with standard three electrode techniques such as cyclic voltammetry CV , chronoamperometry , and bulk electrolysis ... is common. Formalism When describing electrochemical reactions an E and C formalism is often employed ... sup sup to ML sub n 1 sub sup sup often prevents the observation of reversible behavior during electrochemical ... of the chemical reaction. It has become a common practice to model such plots with electrochemical ... process involving oxidation or reduction through the direct transfer of electrons . The electrochemical ... and the rate limiting step. Following physical transformations During potential variant experiments ... during a potential sweep then on the return return sweep a stripping wave is usually observed. ML sub ... more details
force Electrochemicalpotential Standard electrode potential Table of standard electrode potentials ...one source date October 2011 Reduction potential also known as redox potential , oxidation reduction potential , ORP or math E h math is a measure of the tendency of a chemical species to acquire electron s and thereby be redox reduced . Reduction potential is measured in volt s V , or millivolts mV . Each species has its own intrinsic reduction potential the more positive the potential, the greater ... solution s, the reduction potential is a measure of the tendency of the solution to either gain ... more positive reduction potential than the new species will have a tendency to gain electrons ... more negative reduction potential will have a tendency to lose electrons to the new species i.e. to be oxidized ... the reduction potential of an aqueous solution. Like pH, the reduction potential represents ... the Absolute electrode potential absolute potentials are difficult to accurately measure, reduction ... are determined by measuring the potential difference between an inert sensing electrode in contact ... standard of known potential. The standard hydrogen electrode SHE is the reference from which all standard redox potentials are determined and has been assigned an arbitrary half cell potential ... measurement of the reduction potential in aqueous solutions is relatively straightforward, many factors ... seldom correlate with calculated values. Nevertheless, reduction potential measurement has ... value e.g. process control and titration s . Standard reduction potential, math E 0 math see also Standard hydrogen electrode The standard reduction potential math E 0 math is measured under ... gas that is part of the reaction, and metal s in their pure state. The standard reduction potential ... given a potential of 0.00 volts. Historically, many countries, including the United States and Canada ... potential is quoted as measured against a different reference electrode than the one desired and it becomes ... more details
transport passive diffusion . See also Bioelectrochemistry Electrochemicalpotential Goldman ... force calculator.html Electrochemical Driving Force Calculator DEFAULTSORT Membrane Potential Category ... sides of a plasma membrane cellular membrane lead to a voltage called the membrane potential. Many ... regions. These concentration gradients provide the potential energy to drive the formation of the membrane potential. This voltage is established when the membrane has permeability to one or more ... potential. Note that the bulk solutions of either side of the membrane are electo neutral ... and attract each other across membrane. Thus, the membrane potential is physically located only ... of the ionic contributions to the membrane potential. Other ions including sodium, chloride, calcium ... channel and the direction of net potassium movement. Membrane potential also transmembrane potential or membrane voltage is the difference in electrical potential between the interior and the exterior ... of a lipid bilayer with a variety of types of proteins embedded in it. The membrane potential arises ... potential resting membrane potential of a cell, is potassium, although other ions do contribute in more minor ways. By convention, the sign of the membrane potential is designated as the voltage inside ... transmembrane potential, usually with a negative voltage in the cell interior as compared to the cell exterior. The membrane potential has two basic functions. First, it allows a cell to function ... potential that causes electric current to flow rapidly to other points in the membrane. In non ... potential is held at a relatively stable value, called the resting potential . For neurons, typical values of the resting potential range from 70 to 80 millivolts that is, the interior of a cell ... of ion channels can induce a departure from the resting potential. This is called a depolarization if the interior ... cells, a sufficiently large depolarization can evoke an action potential , in which the membrane ... more details
An electrochemical hydrogen compressor is a hydrogen compressor where hydrogen is supplied to the anode, and compressed hydrogen is collected at the cathode ref http perso.ensem.inpl nancy.fr Olivier.Lottin FDFC08 CD Contributions Grigoriev res130 .pdf Characterization of pem electrochemical hydrogen compressors ref with an exergy efficiency of 70 to 80 for pressures up to 10,000 psi or 700 bars. ref http www.nrc cnrc.gc.ca eng licensing ifci electrochemical hydrogen compressor.html Electrochemical hydrogen compressor ref Principle Image Electrochemical hydrogen compressor.jpg right A multi stage electrochemical hydrogen compressor incorporates Membrane electrode assembly membrane electrode assemblies MEAs separated by proton exchange membrane s PEMs in series to reach higher pressures, when a current is passed through the MEA protons and electrons are generated at the anode. The protons are electrochemically driven across the membrane to the cathode, after which they combine with the rerouted electrons to form hydrogen, which is fed to the hydrogen compressor to be oxidized at the anode of each cell to form protons and electrons. This type of compressor has no moving parts and is compact. With electrochemical compression of hydrogen a pressure of 5000 psi is achieved. Pressure is believed to go beyond 10,000 psi to the structural limits of the design. ref http www.hydrogen.energy.gov pdfs review08 pdp 29 lipp.pdf Electrochemical hydrogen compressor ref Water vapor partial pressure , current density , operating temperature and hydrogen back diffusion due to the pressure gradient have an effect on the maximum output pressure. Applications Electrochemical hydrogen compressors have been proposed for use in hydrogen refueling stations to pressurize hydrogen gas for storage. They have also been applied into novel refrigeration systems to pressurize hydrogen for absorption into metal ... Xergy Inc. ref as demonstrated by winners of the global GE s Ecomagination awards for 2011. These electrochemical ... more details
Wiktionary potentialPotential may mean In mathematics and physics a Potential Scalar potential Vector potentialPotential function disambiguation In physics and engineering Potential energy Magnetic potential Electric potential Electromagnetic four potential Coulomb potential van der Waals potential Lennard Jones potential Yukawa potential In linguistics Irrealis mood PotentialPotential mood In biology Action potential Membrane potential Water potential In Television Potential Buffy episode Potential Buffy episode , an episode of Buffy the Vampire Slayer Potential and new Slayers , characters in Buffy the Vampire Slayer In philosophy Potentiality and actuality , a possibility that a thing can be said to have. Disambig ca Potencial cs Potenci l de Potential es Potencial fr Potentiel it Potenziale he ka lt Potencialas pl Potencja ujednoznacznienie ru simple Potential sv Potential ... more details
The term potential function may refer to A mathematical function mathematics function whose values are a physical potential . The class of functions known as harmonic function s, which are the topic of study in potential theory . The potential function of a potential game . A function used in the potential method of amortized analysis to describe an investment of resources by past operations that can be used by future operations. mathdab ... more details
are actively researching electrochemical reduction of CO sub 2 sub . For instance, Nobel prize ... Kaneco, the electrochemical reduction of CO sub 2 sub in the methanol based electrolyte with various ... the Joint Center for Artificial Photosynthesis, which will research electrochemical means of carbon dioxide conversion. ref name D http solarfuelshub.org ref Companies Companies researching electrochemical ... worldwide, under the PCT Patent Application WO2007 041872 Continuous co current electrochemical reduction .... Other potential applications, such as chemical processing or treatment by algae are in the Research ... Biobattery Electrofuels Lemon battery Photoelectrochemical reduction of CO2 Electrochemical energy ... more details
, returning the electrochemical gradient to the resting state. After an action potential has occurred ...pp move vandalism small yes In physiology , an action potential is a short lasting event in which the electrical membrane potential of a Cell biology cell rapidly rises and falls, following a consistent trajectory. Action potentials occur in several types of animal cell s, called Membrane potential excitable ..., an action potential is the first step in the chain of events leading to contraction. In beta cell s of the pancreas ... its spike train . A neuron that emits an action potential is often said to fire . Action potentials ... . ref name pmid17515599 cite journal author Barnett MW, Larkman PM title The action potential journal ... content 7 3 192.short issn ref These channels are shut when the membrane potential is near the resting potential of the cell, but they rapidly begin to open if the membrane potential increases ... ions, which changes the electrochemical gradient, which in turn produces a further rise in the membrane potential. This then causes more channels to open, producing a greater electric current, and so ... upswing in the membrane potential. The rapid influx of sodium ions causes the polarity of the plasma ... to additional potassium currents. This is the mechanism that prevents an action potential from traveling ... of cells, the membrane potential voltage changes very little over time. There are some ... neuron Image Action potential vert.png thumb 300px Figure 1. A. view of an idealized action potential shows its various phases as the action potential passes a point on a cell membrane . B. Recordings ... potential measured in mV versus time ms . Top idealized plot where the membrane potential starts out at 70 mV at time zero. A stimulus is applied at time 1 ms, which raises the membrane potential above 55 mV the threshold potential . After the stimulus is applied, the membrane potential rapidly rises to a peak potential of 40 mV at time 2 ms. Just as quickly, the potential then drops and overshoots ... more details
Contact potential may refer to Contact electrification Electromotive force Contact potentials Galvani potential difference in electrochemistry, at a junction of two metals Volta potential difference in electrochemistry, between two points in vacuum near surfaces of two metals in contact Disambig ... more details
In physics , a pair potential is a function that describes the potential energy of two interacting objects. Examples of pair potentials include the Coulomb s law in Classical electromagnetism electrodynamics , Newton s law of universal gravitation in mechanics , the Lennard Jones potential and the Morse potential . Pair potentials are very common in physics exceptions are very rare. An example of a potential energy function that is not a pair potential is the three body Axilrod Teller potential . Another example is the Stillinger Weber potential for silicon which includes the angle in a triangle of silicon atoms as a parameter. Category Mechanics physics stub ... more details
Cleanup date February 2008 Refimprove date February 2008 Biotic potential is the maximum reproductive capacity of a population if resources are unlimited. Full expression of the biotic potential of an organism is restricted by environmental resistance , any condition that inhibits the increase in number of the population. It is generally only reached when environmental conditions are very favorable. A species reaching its biotic potential would exhibit exponential population growth and be said to have a high fertility , that is, how many offspring are produced per mother. Chapman relates to a vital index Vital Index number of births number of deaths 100 Biotic potential is the highest possible vital index of a species therefore, when the species has its highest birthrate and lowest mortality rate. Components of Biotic Potential prose date February 2012 Reproductive potentialpotential natality It is the upper limit to biotic potential in the absence of mortality Survival potential Because reproductive potential does not account for the number of gametes surviving, survival potential is a necessary component of biotic potential it is the reciprocal of Death mortality in the absence of mortality, biotic potential reproductive potential Chapman identified two components nutritive potential the ability to acquire and utilize food for growth and energy protective potentialpotential ability of the organism to protect itself against the dynamic forces of the environment assuring successful fertilization mating care of young References references DEFAULTSORT Biotic Potential Category Reproduction Category Reproductive ecology pl Potencja biotyczny pt Potencial bi tico sl Biotski potencial uk ... more details
multiple issues confusing June 2010 unreferenced June 2010 The endocochlear potential is the main resting potential in the cochlea . It is a positive direct current of 80mV which can be recorded from the endolymph with electrodes. When a sound is presented, the endocochlear potential changes either positive or negative in the endolymph , depending on the stimulus. The change in the potential is called the summating potential . With the movement of the basilar membrane , a shear force is created and a small potential is generated due to a difference in potential between the endolymph scala media 80 mV and the perilymph vestibular and tympanic ducts 70 mV . An acoustic stimulus produces a simultaneous change in conductance at the membrane of the receptor cell. Because there is a steep gradient 150 mV, changes in membrane conductance are accompanied by rapid influx and efflux of ions which in turn produce the receptor potential. This is known as the Battery Hypothesis. The receptor potential for each hair cell causes a release of neurotransmitter at its basal pole, which elicits excitation of the afferent nerve fibres. Category Anatomy ... more details
Definition The potential of something to grow. Overview In the case of a company, it is its potential to grow larger in terms of market capitalization , Production, costs, and pricing production , sales , revenue , employment , or management . In the case of living creatures, they initially have more growth potential than later on. Category Business terms business stub ... more details
Unreferenced date December 2006 A synaptic potential also known as a postsynaptic potential is an alteration in the membrane potential of a cell resulting from activation of a chemical synapse synaptic input . All animal cells maintain a voltage difference between the intracellular and extracellular regions, holding the intracellular region at a negative voltage that in a baseline state is usually in the range 30 to 70 millivolts. Synaptic inputs from neuron s can alter this voltage difference. If the intracellular voltage rises, the signal is called an excitatory postsynaptic potential EPSP if it falls the signal is called an inhibitory postsynaptic potential IPSP . If the cell is electrically excitable, a sufficiently large EPSP may cause it to generate an action potential . Category Cell biology Neuroscience stub Medicine stub ... more details
Receptor potential , a type of graded potential, is the transmembrane potential difference of a sensory receptor . ref Cite book ref harv first Bertil last Hille authorlink Bertil Hille title Ion Channels of Excitable Membranes edition 3rd year 2001 publisher Sinauer location Sunderland, Massachusetts chapter Chapter 8. Sensory transduction and excitable cells. pages 237&ndash 268 isbn 0878933212 ref A receptor potential is often produced by sensory transduction . It is generally a depolarization depolarizing event resulting from inward current electricity current flow. The influx of current will often bring the membrane potential of the sensory receptor towards the threshold for triggering an action potential . A receptor potential is a form of graded potential. An example of this is in a taste bud , where taste is converted into an electrical signal sent to the brain. When stimulated, the taste bud triggers the release of neurotransmitter through exocytosis of synaptic vesicles from the presynaptic membrane. The neurotransmitter molecules diffuse across the synaptic cleft to the postsynaptic membrane. Graded potentials vary in size. They arise from the summation of the individual actions of ligand gated ion channel proteins, and decrease over time and space. They are distinct from Voltage gated ion channel voltage gated sodium and potassium channels . ref Harvnb Hille 2001 pp 169&ndash 200 . Chapter 6. Ligand gated channels of fast chemical synapses. ref References reflist DEFAULTSORT Receptor Potential Category Receptors Category Electrophysiology de Rezeptorpotential id Potensial reseptor ... more details
In mathematics , the Bessel potential is a potential theory potential named after Friedrich Wilhelm Bessel similar to the Riesz potential but with better decay properties at infinity. If s is a complex number with positive real part then the Bessel potential of order s is the operator math I Delta s 2 math where is the Laplace operator and the fractional calculus fractional power is defined using Fourier transforms. See also Riesz potential Fractional integration Sobolev space Fractional Schr dinger equation References eom id B b110420 title Bessel potential operator first R. last Duduchava Citation last1 Grafakos first1 Loukas title Modern Fourier analysis publisher Springer Verlag location Berlin, New York edition 2nd series Graduate Texts in Mathematics isbn 978 0 387 09433 5 doi 10.1007 978 0 387 09434 2 mr 2463316 year 2009 volume 250 eom id B b120170 title Bessel potential space first L.I. last Hedberg eom id B b015870 first E.D. last Solomentsev citation first Elias last Stein authorlink Elias Stein title Singular integrals and differentiability properties of functions publisher Princeton University Press location Princeton, NJ year 1970 isbn 0 691 08079 8 Category Fractional calculus Category Partial differential equations Category Potential theory Category Singular integrals ... more details
Image Action potential vert.png thumb 350px A. A schematic view of an idealized action potential illustrates its various phases as the action potential passes a point on a cell membrane . B. Actual recordings of action potentials are often distorted compared to the schematic view because of variations in electrophysiology electrophysiological techniques used to make the recording. The threshold potential is the membrane potential to which a membrane must be depolarization depolarized to initiate an action potential . It often can be between 40 and 55 volt mV , but it can vary based upon several factors. If ion channel s are available, that will move the potential in the direction of the equilibrium potential for that ion sodium ion channel Na sup sup is approximately 55mV potassium channel K sup sup is approximately 95mV chloride channel Cl sup sup is approximately 90mV Therefore, resting ion channel for sodium will depolarization depolarize and thus excite, while channels for potassium or chloride will hyperpolarization biology hyperpolarize and thus inhibit. External links eMedicineDictionary threshold stimulus GeorgiaPhysiology 1 1ch4 s1ch4 8 http www.cameron.edu gabrielr PHYCH4 sld013.htm Description at cameron.edu http www.ncbi.nlm.nih.gov books bv.fcgi?rid mcb.figgrp.6213 Diagram at nih.gov neuro stub Category Electrophysiology de Schwellenpotential pl Potencja progowy ... more details
Unreferenced date March 2009 A velocity potential is used in fluid dynamics , when a fluid occupies a simply connected region and is irrotational . In such a case, math nabla times mathbf u 0, math where math mathbf u math denotes the flow velocity of the fluid. As a result, math mathbf u math can be represented as the gradient of a scalar field scalar function math Phi math math mathbf u nabla Phi math , math Phi math is known as a velocity potential for math mathbf u math . A velocity potential is not unique. If math a math is a constant then math Phi a math is also a velocity potential for math mathbf u math . Conversely, if math Psi math is a velocity potential for math mathbf u math then math Psi Phi b math for some constant math b math . In other words, velocity potentials are unique up to a constant.If value of satisfies Laplace equation ,it indicates case of fluid flow. Unlike a stream function , a velocity potential can exist in three dimensional flow. See also Hamiltonian fluid mechanics Potential flow DEFAULTSORT Velocity Potential Category Fluid dynamics Category Equations of fluid dynamics Fluiddynamics stub zh ... more details
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