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Topic: Critical temperature

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Critical pressure

Critical point

Critical variables

Temperature

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Carbon dioxide

Van der Waals equation

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	Critical point (thermodynamics) - Wikipedia, the free encyclopedia
		The critical point in a phase diagram is at the high-temperature extreme of the liquid-gas phase boundary.
		Critical variables are useful for rewriting a varied equation of state into one that applies to all materials.
		However, in some non-equilibrium systems the critical point is an attractor of the dynamics in a manner that is robust with respect to system parameters, a phenomenon referred to as self-organized criticality.
	en.wikipedia.org /wiki/Critical_point_(chemistry) (369 words)

	Critical magnetic fields for superconductors
		This critical magnetic field is strongly correlated with the critical temperature for the superconductor, which is in turn correlated with the bandgap.
		This critical magnetic field is tabulated for 0K and decreases from that magnitude with increasing temperature, reaching zero at the critical temperature for superconductivity.
		The critical magnetic field required to destroy the superconducting state is strongly correlated with the critical temperature for the superconductor.
	hyperphysics.phy-astr.gsu.edu /hbase/solids/scbc.html (413 words)

	Critical temperature - Wikipedia, the free encyclopedia
		Critical properties vary from material to material, just as is the case for the melting point and boiling point.
		For pure substances, there is an inflection point in the critical isotherm on a PV diagram.
		Critical Temperature refers to the temperature above which structural Steel loses its strength and is no longer fully capable of loadbearing support.
	en.wikipedia.org /wiki/Critical_temperature (391 words)

	Superconductivity
		A new era in the study of superconductivity began in 1986 with the discovery of high critical temperature superconductors.
		The critical temperature for superconductors is the temperature at which the electrical resistivity of a metal drops to zero.
		The highest critical temperature was about 23 K until the discovery in 1986 of some high temperature superconductors.
	hyperphysics.phy-astr.gsu.edu /hbase/solids/scond.html (619 words)

	C - Glossary of chemical terms
		In general, critical point is the point on the phase diagram of a two-phase system at which the two coexisting phases have identical properties and therefore represent a single phase.
		Critical temperature is the temperature of the liquid-vapour critical point, that is, the temperature above which a gas cannot be liquefied by an increase of pressure.
		Critical volume is the volume of a fixed mass of a fluid at critical temperature and pressure.
	www.ktf-split.hr /periodni/en/abc/c.html (1906 words)

	FAWN: Critical Temperature Guidance
		Citrus trees acclimated to cold temperatures have survive temperatures as low as 14°F. Acclimation is affected by exposure temperatures, scion cultivar, rootstock cultivar, rootstock/scion combination, tree nutritional status, crop load and water stress.
		The critical temperature for vegetables to turn on frost protection irrigation would likely be from 32F to 34F depending on whether fruit was present or not on the plants.
		Temperatures below 30F at the level of the plants can kill soft growth and predispose the plants to death at any time during the next 3 years as a result of infection of freeze-damaged stems by the blueberry stem blight pathogen, Botryosphaeria dothidia.
	fawn.ifas.ufl.edu /scripts/crit_temp_select_guide.asp (2607 words)

	Magnetics Group: Standards for Superconductor and Magnetic Measurements (Site not responding. Last check: 2007-11-02)
		The project is currently focusing on measurements of variable-temperature critical current, residual resistivity ratio, magnetic hysteresis loss, critical current of marginally stable superconductors, and the irreversible effects of changes in magnetic field and temperature on critical current.
		Temperature is an important variable, and the local temperature of the conductor depends on the mass-flow rate of the coolant and the distribution of the heat load along the CICC.
		Critical current depends on temperature, magnetic field, and the angle of the magnetic field with respect to the conductor.
	www.boulder.nist.gov /div818/81803/StandardsForSuperconCharacter (1589 words)

	UM Physics Demonstration
		Turn on the temperature controler connected to the hot plate/beaker/water pump system (or the steam generator) and allow the temperature for the initial run to go until the cell passes through the critical point, which is 112.7 degrees F (or about 88 degrees C for the Freon).
		The water temperature controller should be set at about 116 degrees F to allow for losses in the system.
		The lecturer may go back and forth through the critical point quickly by simply cycling the circulating pump on and off, as once the cell and the water (or the steam generator) are up to temperature the cycling is fairly rapid.
	www.physics.lsa.umich.edu /demolab/demo.asp?id=185 (287 words)

	[No title] (Site not responding. Last check: 2007-11-02)
		This is accomplished by splicing or joining at least two high temperature superconducting components in a manner that results in articles having critical currents that are close to the critical currents of each of the high temperature superconducting components.
		The high temperature superconducting components are connected by means of a solder layer, and a further protective layer is attached to the components.
		The connected portions of the components form an overlap segment; when the critical current is measured over an article length at least 100 times the length of the overlap segment, the critical current is at least 80% of the lesser of the critical currents of the individual components.
	www.wipo.int /cgi-pct/guest/getbykey5?KEY=00/74151.001207&ELEMENT_SET=DECL (4591 words)

	Critical Temperature and Pressure (Site not responding. Last check: 2007-11-02)
		The critical temperature of a substance is the temperature at and above which vapor of the substance cannot be liquefied, no matter how much pressure is applied.
		C (the critical temperature for water), only water vapor exists in the tube.
		The critical pressure of a substance is the pressure required to liquefy a gas at its critical temperature.
	www.chem.purdue.edu /gchelp/liquids/critical.html (96 words)

	Highlights of the Zeno Results from the USMP-2 Mission
		For smaller temperature changes, we were able to make "fast steps" where the set points of the control shells were temporarily moved well beyond the target temperature and then returned just as the sample cell reached the desired temperature.
		When the temperature of the sample cell was changed, thermal expansion or contraction of its components altered the window spacing and produced a measurable change in the turbidity signal, independent of the turbidity of the xenon itself.
		Note that the temperature is measured at the cell wall, approximately 1.5 cm from the region of fluid probed by the laser, confirming the long-range action of the adiabatic effect.
	www.zeno.umd.edu /report/report.html (6203 words)

	Critical Point of Benzene
		As the critical temperature is approached, the meniscus flattens.
		A gas above the critical temperature cannot be condensed into a liquid, since the molecular attractive forces are dominated by the rapid molecular motion.
		The critical temperature is the temperature above which the distinction between liquid and gas no longer applies, so as the benzene is heated above its critical temperature the difference between gas and liquid disappears and the benzene becomes one fluid (usually called gas), and conversely as the benzene is cooled.
	jchemed.chem.wisc.edu /JCESoft/CCA/CCA2/MAIN/BENZENE/CD2R1.HTM (406 words)

	Critical Fluid Thermal Equilibrium Experiment (Site not responding. Last check: 2007-11-02)
		The feverish activity of the 1970's in fluid critical phenomena slowed to a near standstill, partly because of gravitational limitations on the acquisition of further experimental data closer to the critical temperature.
		a constatn volume sample loaded on to he critical density can not maintain a large portion of the sample at the critical point, because the weight of the fluid is enough to compress half of the sample to a density abouve the critical density.
		Because temperature is such a key parameter in critical-point studies, the CPF was designed to provide thermal control of the test fluid with an accuracy of one thousandth of a degree (0.001 degree C).
	zeta.lerc.nasa.gov /expr2/cft.htm (987 words)

	Critical Phenomena
		Water, for example, has a critical temperature of 647.1 K, much higher than the 298.15 K standard room temperature.
		Temperatures are relative to the critical temperature so that a temperature of 1.0 is the critical temperature, a temperature of 1.1 is above the critical temperature, and so on.
		The isotherms below the critical temperature, for example, temperature equals 0.9, are peculiar to the van der Waals equation of state and are not physically realistic.
	www.chem.arizona.edu /~salzmanr/480a/480ants/CRITICAL/critical.html (789 words)

	Oral Measurement of Temperature in Orally Intubated Critical Care Patients: State-of-the-Science Review
		Temperature in the PA is measured with a thermistor-tipped thermodilution catheter.
		They fear that the temperature of the contents of orogastric or endotracheal tubes might influence oral temperature and that the patient might not be able to fully close his or her mouth around these tubes.
		Oral temperatures were higher with the endotracheal tube in place and were not significantly affected by the temperature of the contents of the endotracheal tube, ambient temperature, state of dentition, or mouth position.
	www.aacn.org /AACN/jrnlajcc.nsf/bd5ca01ff707c8948825653f000cd2b6/5b1b4fdc5317597e88256951007894f3?OpenDocument (5276 words)

	Classical Kinetic Theory of Gases: A Crash Review
		"Critical pressure" is the limit of the vapor pressure of the liquid as the liquid's temperature approaches the critical temperature from below.
		Linus Pauling reports that, in practice, the critical temperature and critical pressure are much closer to the theoretical values than the critical volume, and that the pragmatic approximation to critical volume is usually close to 2.25bn.
		That means it is possible to estimate a and b from the critical temperature and critical pressure (a minor algebra exercise).
	www.zaimoni.com /ClassicalGas.htm (2240 words)

	Investigation of Internal Waves In a Viscometer near the Critical Point
		The critical point is characterized by a unique temperature, pressure, and density; roughly speaking, at temperatures below the critical temperature, two-phase equilibria between the liquid and vapor phases are possible, and above the critical temperature the distinction between liquid and vapor is lost and only one phase occurs.
		A complication with terrestrial measurements of critical fluids is the density stratification that occurs in the presence of a gravitational field.
		In experimental work by Robert Berg (838) to measure fluid viscosity near the critical point, a rectangular paddle whose surface consists of a fine-wire mesh that is permeable to the fluid is driven sinusoidally in the fluid with a given frequency.
	math.nist.gov /mcsd/Reports/95/yearly/node29.html (708 words)

	NIST - Fluid Metrology Group - Selected Abstracts (Critical Phenomena in Fluids)
		Critical exponent for the viscosity of carbon dioxide and xenon
		We used interferometry to measure the density changes associated with the late stage of thermal equilibration near the liquid-vapor critical point of SF This experiment was performed on board the Space Shuttle in the absence of the considerable obscuring effects of gravity.
		Critical viscosity of the ionic mixture triethyl n-hexyl ammonium triethyl n-hexyl borate in diphenyl ether
	properties.nist.gov /fluidsci/crit.html (3017 words)

	Solid State Simulations - "ising" (Site not responding. Last check: 2007-11-02)
		The magnetic field and temperature are given and the spin orientations of a 30x30 array of Ising spins are displayed as the system evolves in time after changes in the applied field and/or temperature.
		The size of the clusters increases as the critical temperature is approached.
		Near the critical temperature (on the right) the magnitude of the magnetization fluctuations is much larger than at the high temperature (critical fluctuations); and the fluctuations take a much longer time to die away (critical slowing down) when the temperature is near the critical temperature.
	www.physics.cornell.edu /sss/ising/ising.html (566 words)

	Highest Critical Temperature Superconductor
		The element that has the highest superconducting critical temperature of 9.3 K was niobium.
		This superconductor is a type of ceramic copper oxide and its critical temperature was determined in 1995 by Chakoumakos, Dai, Wong, Sun, Lu, and Xin.
		Apparently, metal-copper oxide ceramic superconductors have high critical temperatures, which might unlock the key of synthesizing a high temperature superconductor that is superconductive under room temperature conditions.
	hypertextbook.com /facts/2002/MichaelNg.shtml (383 words)

	Dolan-Jackiw paper
		They gave qualitative arguments to support this contention in a theory with global symmetry (not a gauge theory) and obtained an order-of-magnitude expression for the critical temperature in terms of the parameters of the theory.
		The restoration of a spontaneously broken symmetry above a critical temperature is a phenomenon whose aspects in field theory have been exhibited in this investigation.
		We have computed the critical temperature in terms of the renormalized parameters of the theory for a variety of models.
	www.physics.ucla.edu /~cwp/articles/Dolan-Jackiw/conclusion.html (596 words)

	Equations of State
		where reduced pressure and temperature are the unitless quantities obtained by dividing the value by the critical value.
		In the case of reduced volume, molar volume is divided by critical molar volume.
		Critical Opalescence - Critical behavior is generally described using real gas equations which have constants defined in a way which ensures that the slope of reduced pressure vs. reduced volume is zero at the critical point.
	www.ccl.net /cca/documents/dyoung/topics-orig/eq_state.html (2066 words)

	Lessons In Electric Circuits -- Volume I (DC) - Chapter 12
		For some metal alloys, the temperature coefficient of resistance is very close to zero, meaning that the resistance hardly changes at all with variations in temperature (a good property if you want to build a precision resistor out of metal wire!).
		The threshold temperature for a superconductor to switch from normal conduction to superconductivity is called the transition temperature.
		Transition temperatures for "classic" superconductors are in the cryogenic range (near absolute zero), but much progress has been made in developing "high-temperature" superconductors which superconduct at warmer temperatures.
	www.ibiblio.org /obp/electricCircuits/DC/DC_12.html (7934 words)

	Application notes - Critical Pitting Temperature
		This test involves determining the temperature at which initiation of localised corrosion occurs.
		The temperature is then increased in steps by the Gill AC until the current recorded by the Gill AC reaches a set current this temperature being the critical pitting temperature.
		A typical temperature current graph from the equipment above is shown in the diagram below.
	www.acminstruments.com /apn-cptt.shtml (137 words)

	Critical Temperature (Site not responding. Last check: 2007-11-02)
		Description: A pressure chamber containing liquid sulfur hexafluoride, SF, is warmed to the critical temperature of the SF Light is projected through a window in the chamber so that the disappearance of the line of separation between liquid and gas can be seen on a screen when the SF reaches its critical temperature.
		Concept: There is a temperature at which the liquid phase of a substance can no longer exist regardless of the pressure.
		To improve the heat contact between the temperature probe and the chamber, put a little glycerine in the hole on top of the chamber before inserting the temperature probe (see diagram in notes to identify this hole).
	chemlearn.chem.indiana.edu /demos/crittemp.htm (849 words)

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