Differential nonlinearity - Revision history

en>Jodosma: spelling: convertor→converter

2014-09-22T08:43:41Z

spelling: convertor→converter

← Older revision		Revision as of 10:43, 22 September 2014
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	~~{{One source\|date=March 2011}}~~
	~~[[File:Linear Potential Sweep.JPG\|right\|400px\|thumb\|'''Linear potential sweep''']]~~
	'''Linear sweep voltammetry''' is a [[Voltammetry\|voltammetric method]] where the current at a [[working electrode]] is measured while the potential between the working electrode and a [[reference electrode]] is swept linearly in time. Oxidation or reduction of species is registered as a peak or trough in the current signal at the potential at which the species begins to be oxidized or reduced.

	~~== Experimental method ==~~
	The experimental setup for linear sweep voltammetry utilizes a potentiostat and a three-electrode setup to deliver a potential to a solution and monitor its change in current. The three-electrode setup consists of a working electrode, an auxiliary electrode, and a reference electrode. The potentiostat delivers the potentials through the three-electrode setup. A potential, E, is delivered through the working electrode. The slope of the potential vs. time graph is called the scan rate and can range from mV/s to 1,000,000 V/s.<ref>{{cite web\|last=Tissue\|first=Brian M.\|title=Linear Sweep Voltammetry\|website=CHP\|url=http://www.files.chem.vt.edu/chem-ed/echem/linsweep.html}}</ref> At higher scan rates the current is found to increase which improves the signal to noise ratio. Therefore higher scan rates lead to better signal to noise ratios.

	~~The working electrode is where~~ the ~~oxidation/reduction reactions occur. The equation below gives an example of an oxidation occurring~~ at ~~the surface~~ of the ~~working electrode~~. ~~ES is the standard reduction potential~~ of A. ~~As E approaches ES the current on the surface increases and when E=ES then the concentration of~~ [~~A] = [A-] at the surface~~.~~<ref>{{cite web\|last~~=~~\|first=\|title=Voltammetry\|website=CHP\|url~~=http://~~mail~~.~~chiangmai~~.~~ac.th/~scijjkmn~~/~~voltammetry~~.~~htm}}</ref> As the molecules on the surface of the working electrode~~ or ~~oxidized/reduced they move away from the surface and new molecules come into contact with the surface of the working electrode~~. ~~This flow of molecules to and from the working electrode causes the current~~.		You can appear for the perfect company present at any of the shops. There are even specialised company present stores that provide suitable products. A individual can choose from an extensive range of suppliers to fit any specifications. Company houses searching for [http://mondediplo.com/spip.php?page=recherche&recherche=souvenirs souvenirs] on a [http://www.encyclopedia.com/searchresults.aspx?q=bigger+scale bigger scale] can check in such shops or appear online. Buying on a large scale assists you get provides at a cheaper rate too.<br><br>Make an define of the factors you want to include before you begin recording audio for your video clip. The last factor you want to do is be a stammering idiot. If you pay attention to your video and you discover the phrase that is spoken the most frequently is 'um' you truly should go back and re-do it.<br><br><br><br>For me, it is not about waiting till tomorrow or when much more money comes. It is about residing for today and finding the easy pleasures that encompass me each and every day.<br><br>Gadgets - If your brother is a gadget freak, present him a gadget of his choice. There are numerous gadgets that can be perfect gift for brother. If he loves music you can present him an iPod or a MP3 player. Other than that electronic digital camera, cell telephones or handycams can also be presents that can be offered to brothers on any occasions.<br><br>So if the watch did break for a lot of odd reason, just like you forgot to consider them back again whilst you wearing it, getting your truck out of the mud, as you were 4 wheeling your suv. Than the would be a ideal view, since you are an outside guy, you're not worried about how costly the wrist view is. You are pleased that it tells the time and also the energy if not going out anytime quickly!<br><br>You can select from either advertising products or advertising products. You can also get promotional business gifts and advertising corporate presents. A lot of thought goes into while choosing a current.<br><br>When you elect to buy pre-owned [https://www.youtube.com/watch?v=1g610i44dKI relogio da red bull] NYC, you should appear into the clock mileage. Real luxury watches have serial numbers. The vendor should disclose these numbers. You can verify whether or not there is truly that kind of design throughout that year. If the seller is dependable, disclosing this type of information ought to not be a issue. If the dealer is hesitant to provide the serial quantity and related info, it ought to currently give you a warning.<br><br>Hong Kong lures tourists from all over the globe and it is considered to be one of the most secured metropolitan areas in the world. There is no question in stating that it will be hard to discover a location as exciting as Hong Kong because of its combined culture. The metropolis preserves the traces of British culture along with conventional customs of Confucianism. In this article, we will talk about about touristic points of interest.

	<~~math~~>~~A+e^-=A^-~~<~~/math~~> ~~E_s=0.00V~~

	~~Oxidation of molecule A at the surface~~ of the ~~working electrode~~

	~~The auxiliary and reference electrode work in unison~~ to ~~balance out the charge added or removed by the working electrode~~. The ~~auxiliary electrode balances the working electrode, but in order~~ to ~~know how much potential it has to add or remove it relies on the reference electrode. The reference electrode has~~ a ~~known reduction potential~~. ~~The auxiliary electrode tries~~ to ~~keep~~ the ~~reference electrode at a certain reduction potential~~ and to do ~~this~~ it ~~has to balance the working electrode~~.<~~ref~~>~~{{cite book\|last=Kounaves\|first=Samuel P~~.~~\|title=Voltammetric Techniques~~. ~~Handbook of Instrumental Techniques for Analytical Chemistry\|pages=709–725}}~~<~~/ref~~>

	~~== Characterization ==~~
	~~Linear sweep voltammetry can identify unknown species and determine the concentration~~ of ~~solutions~~. ~~E1/2~~ can be ~~used to identify the unknown species while the height of the limiting current~~ can ~~determine the concentration~~. ~~The sensitivity of current changes vs. voltage~~ can be ~~increased by increasing~~ the ~~scan rate. Higher potentials per second result in more oxidation/reduction~~ of ~~a species at the surface~~ of the ~~working electrode~~.

	~~== Variations ==~~
	~~For reversible reactions cyclic voltammetry can~~ be ~~used to find information~~ about the ~~forward reaction and~~ the ~~reverse reaction. Like linear sweep voltammetry, cyclic voltammetry applies a linear potential over~~ time and ~~at a certain potential~~ the ~~potentiostat will reverse the potential applied and sweep back to the beginning point~~. ~~Cyclic voltammetry provides information about the oxidation~~ and ~~reduction reactions~~.

	~~== Applications ==~~
	While cyclic voltammetry is applicable to most cases where linear sweep voltammetry is used, there are some instances where linear sweep voltammetry is more useful. In cases where the reaction is irreversible cyclic voltammetry will not give any additional data that linear sweep voltammetry would give us.<~~ref~~>~~{{cite web\|title=Instrumentation, Pine Research. Linear Sweep Voltammetry\|year=2008\|website=CHP\|url=http~~://www.~~voltammetry~~.~~net~~/~~pine/aftermath/echem/linear_sweep_voltammetry.}}</ref>~~
	~~In one example~~,~~<ref>{{cite paper\|last=Cheng\|first=Shaoan\|last=Xing\|first=Defeng\|last=Call\|first=Douglas F\|last=Logan\|first=Bruce E.\|title=Direct Biological Conversion of Electrical Current~~ into ~~Methane by Electromethanogenesis\|year=2009\|journal=Environ~~. ~~Sci~~. ~~Technol~~.~~\|pages=3953–3958~~.~~}}</ref> linear voltammetry was used~~ to ~~examine direct methane production via~~ a ~~biocathode~~. ~~Since~~ the ~~production of methane from CO2~~ is ~~an irreversible reaction~~, ~~cyclic voltammetry did not present any distinct advantage~~ over ~~linear sweep voltammetry. This group found that~~ the ~~biocathode produced higher current densities than a plain carbon cathode~~ and that ~~methane can~~ be ~~produced from~~ a ~~direct electrical current without the need~~ of ~~hydrogen gas.~~

	~~==See also==~~
	* [[Cyclic voltammetry]]
	* [[Electroanalytical Methods]]
	* Linear Sweep Voltammetry/Cyclic Voltammetry. ~~[Online] http://www.basinc.com/mans/EC_epsilon/Techniques/CycVolt/cv.html.~~
	* webmaster@ceb.cam.ac.uk. Linear Sweep and Cyclic Voltametry: The ~~Principles~~. ~~Department of Chemical Engineering and Biotechnology~~, ~~University~~ of ~~Cambridge~~. ~~[Online] http://www.ceb.cam.ac.uk/pages/linear-sweep-and-cyclic-voltametry-the-principles.html.~~

	~~==References==~~
	~~{{Reflist}}~~

	~~{{Electroanalytical}}~~

	~~[[Category:Electroanalytical methods]]~~

131.169.212.195: /* Formula */

2014-01-31T10:26:57Z

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← Older revision		Revision as of 12:26, 31 January 2014
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	~~Hello~~. ~~Let me introduce~~ the ~~author~~. ~~Her name~~ is ~~Janel but she never really liked that name~~. ~~To bungee jump~~ is the ~~only hobby her husband doesn't~~ [http://~~Search~~.un.~~org~~/~~search?ie~~=~~utf8&site~~=~~un_org&output~~=~~xml_no_dtd&client~~=~~UN_Website_en&num~~=~~10&lr~~=~~lang_en&proxystylesheet~~=~~UN_Website_en&oe~~=~~utf8&q~~=~~approve&Submit~~=~~Go approve]~~ of. ~~Her family lives~~ in ~~South Dakota~~ and ~~her parents live nearby~~. ~~Invoicing~~ is ~~what she does~~. ~~Check out~~ the ~~latest news on her~~ website: http://www.~~esnet~~.es/~~calzoncillos~~/~~calvin-klein-ropa-interior-mujer-00770066~~.~~htm~~<br><br>~~Also visit my weblog -~~ [http://www.~~esnet~~.es/~~calzoncillos~~/~~calvin~~-~~klein~~-~~ropa~~-~~interior~~-~~mujer~~-~~00770066~~.~~htm calvin klein ropa interior mujer~~]		{{One source\|date=March 2011}}
			[[File:Linear Potential Sweep.JPG\|right\|400px\|thumb\|'''Linear potential sweep''']]
			'''Linear sweep voltammetry''' is a [[Voltammetry\|voltammetric method]] where the current at a [[working electrode]] is measured while the potential between the working electrode and a [[reference electrode]] is swept linearly in time. Oxidation or reduction of species is registered as a peak or trough in the current signal at the potential at which the species begins to be oxidized or reduced.

			== Experimental method ==
			The experimental setup for linear sweep voltammetry utilizes a potentiostat and a three-electrode setup to deliver a potential to a solution and monitor its change in current. The three-electrode setup consists of a working electrode, an auxiliary electrode, and a reference electrode. The potentiostat delivers the potentials through the three-electrode setup. A potential, E, is delivered through the working electrode. The slope of the potential vs. time graph is called the scan rate and can range from mV/s to 1,000,000 V/s.<ref>{{cite web\|last=Tissue\|first=Brian M.\|title=Linear Sweep Voltammetry\|website=CHP\|url=http://www.files.chem.vt.edu/chem-ed/echem/linsweep.html}}</ref> At higher scan rates the current is found to increase which improves the signal to noise ratio. Therefore higher scan rates lead to better signal to noise ratios.

			The working electrode is where the oxidation/reduction reactions occur. The equation below gives an example of an oxidation occurring at the surface of the working electrode. ES is the standard reduction potential of A. As E approaches ES the current on the surface increases and when E=ES then the concentration of [A] = [A-] at the surface.<ref>{{cite web\|last=\|first=\|title=Voltammetry\|website=CHP\|url=http://mail.chiangmai.ac.th/~scijjkmn/voltammetry.htm}}</ref> As the molecules on the surface of the working electrode or oxidized/reduced they move away from the surface and new molecules come into contact with the surface of the working electrode. This flow of molecules to and from the working electrode causes the current.

			<math>A+e^-=A^-</math> E_s=0.00V

			Oxidation of molecule A at the surface of the working electrode

			The auxiliary and reference electrode work in unison to balance out the charge added or removed by the working electrode. The auxiliary electrode balances the working electrode, but in order to know how much potential it has to add or remove it relies on the reference electrode. The reference electrode has a known reduction potential. The auxiliary electrode tries to keep the reference electrode at a certain reduction potential and to do this it has to balance the working electrode.<ref>{{cite book\|last=Kounaves\|first=Samuel P.\|title=Voltammetric Techniques. Handbook of Instrumental Techniques for Analytical Chemistry\|pages=709–725}}</ref>

			== Characterization ==
			Linear sweep voltammetry can identify unknown species and determine the concentration of solutions. E1/2 can be used to identify the unknown species while the height of the limiting current can determine the concentration. The sensitivity of current changes vs. voltage can be increased by increasing the scan rate. Higher potentials per second result in more oxidation/reduction of a species at the surface of the working electrode.

			== Variations ==
			For reversible reactions cyclic voltammetry can be used to find information about the forward reaction and the reverse reaction. Like linear sweep voltammetry, cyclic voltammetry applies a linear potential over time and at a certain potential the potentiostat will reverse the potential applied and sweep back to the beginning point. Cyclic voltammetry provides information about the oxidation and reduction reactions.

			== Applications ==
			While cyclic voltammetry is applicable to most cases where linear sweep voltammetry is used, there are some instances where linear sweep voltammetry is more useful. In cases where the reaction is irreversible cyclic voltammetry will not give any additional data that linear sweep voltammetry would give us.<ref>{{cite web\|title=Instrumentation, Pine Research. Linear Sweep Voltammetry\|year=2008\|website=CHP\|url=http://www.voltammetry.net/pine/aftermath/echem/linear_sweep_voltammetry.}}</ref>
			In one example,<ref>{{cite paper\|last=Cheng\|first=Shaoan\|last=Xing\|first=Defeng\|last=Call\|first=Douglas F\|last=Logan\|first=Bruce E.\|title=Direct Biological Conversion of Electrical Current into Methane by Electromethanogenesis\|year=2009\|journal=Environ. Sci. Technol.\|pages=3953–3958.}}</ref> linear voltammetry was used to examine direct methane production via a biocathode. Since the production of methane from CO2 is an irreversible reaction, cyclic voltammetry did not present any distinct advantage over linear sweep voltammetry. This group found that the biocathode produced higher current densities than a plain carbon cathode and that methane can be produced from a direct electrical current without the need of hydrogen gas.

			==See also==
			* [[Cyclic voltammetry]]
			* [[Electroanalytical Methods]]
			* Linear Sweep Voltammetry/Cyclic Voltammetry. [Online] http://www.basinc.com/mans/EC_epsilon/Techniques/CycVolt/cv.html.
			* webmaster@ceb.cam.ac.uk. Linear Sweep and Cyclic Voltametry: The Principles. Department of Chemical Engineering and Biotechnology, University of Cambridge. [Online] http://www.ceb.cam.ac.uk/pages/linear-sweep-and-cyclic-voltametry-the-principles.html.

			==References==
			{{Reflist}}

			{{Electroanalytical}}

			[[Category:Electroanalytical methods]]

en>Badpazzword: /* Formula */ Uh... Formatting.

2012-06-13T09:11:55Z

Formula: Uh... Formatting.

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