LYCOS RETRIEVER 
Electrical Conductivity
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Electrical conductivity in milk is influenced by the udder health status of the cow. Traits reflecting the EC level describe udder health status more accurately than traits reflecting the variation in EC within milking. Inter-quarter ratios of EC performed better than the absolute conductivity level for classification of both clinically and subclinically infected cows. However, some extra information about udder health status was obtained when a combination of the EC traits was utilized. The ability of the EC traits to separate subclinically infected cows from healthy cows in this experiment was not satisfactory. Electrical conductivity of milk may be a potential trait in a breeding program, but further research is needed to estimate genetic parameters for EC and genetic correlation to mastitis.
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Electrical conductivity induced in thin lipid bilayer membranes by pentachlorophenol has been studied. The membranes were formed from phosphatidyl choline, phosphatidyl ethanolamine, or phosphatidyl glycerol and various amounts of cholesterol. The position and the magnitude of the maximum of the conductivity vs. pH curve depend on the type of lipids and cholesterol content. At low pentachlorophenol concentrations and low pH the concentration dependence of conductivity is quadratic and becomes linear at higher pH. Above 10(-5) M of pentachlorophenol the concentration dependence of the membrane conductivity tends to saturate. Presence of pentachlorophenol enhances membrane transport of nonactin-K+ complex. Increase of cholesterol content increases pentachlorophenol induced conductivity in all membranes and shifts the conductivity toward lower pH. For phosphatidyl choline the largest rate of change of membrane conductivity with cholesterol occurs at 1:1 phospholipid to cholesterol molar ratio.
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Electrical conductivity of copper alloys are generally stated in terms of %IACS (International Annealed Copper Standard,) with electrical conductivity of ETP copper slightly greater than 100% IACS. Knowing the resistivity (in units of µcm), the %IACS for an alloy is calculated by:
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Electrical conductivity occurs because of the ease with which electrons can be removed from atoms. All substances consist of atoms. In turn, all atoms consist of two main parts: a positively charged nucleus and one or more negatively charged electrons. An atom of iron, for example, consists of a nucleus with 26 positive charges and 26 negatively charged electrons.
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Electrical conductivity readings are a function of the number of ions present and their mobility. The electrical conductivity of a liquid changes at a rate of approximately 2%/oC for neutral salt and is due to the ion mobility being temperature dependant. The temperature coefficient of conductance (or the K factor) varies for salts and can be in the range of 0.5 to 3.0.
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PhysicsWeb August 20, 2003Single-walled carbon nanotubes have been used to increase the electrical conductivity of alumina by 13 orders of magnitude. Guo-Dong Zhan and colleagues at the University of California at Davis have taken a sample of alumina, which is a ceramic insulator, and turned it into a fracture-resistant composite with a conductivity that is over 735% higher than the previous record for a nanotube-ceramic composite.
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Electrical Conductivity