I think you mean POROSITY, the fraction of a mineral which is little holes of empty space. Crystals and most igneous rocks have zero or near-zero porosity. Sandstone, chalk, limestone, and similar sedimentary rocks have varying amounts of porosity according to how they were formed.
Porosity is difficult to measure accurately. The difference in weight when a dry specimen becomes water-saturated should tell us, but the water may take a long time to reach the central parts.
Permeability is the property from which we compute how rapidly any particular fluid will be pushed through the specimen by a pressure difference. It is even harder to measure than the porosity, and I think that commercial meters use helium, which has a low viscosity to give a decently high flow rate. From this measurement, there is an equation to calculate the flow rate of any other fluid according to its viscosity.
Multi-phase permeability is a more advanced concept, but of great concern in petroleum production. When unmixable oil, water and gas may all be trying to push through the same porosity channels, the rate of each depends on the amount of the others. There are lots of horrendous equations to express what happens and how to maximise the oil recovery.
2007-02-14 23:07:22
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answer #1
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answered by Anonymous
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Porosity is the amount of pore space in a (sedimentary) rock. Permeability is the connectivity of those pores.
2007-02-15 15:07:04
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answer #2
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answered by Amphibolite 7
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Prosperity:
Connections, Attention, and Talent: Assessing Long-Term Value of Public Investment in Science and Technology Research
Almost every state hopes to capitalize on the tremendous wealth and job creation that can be generated by high tech science research-and billions of public dollars are being spent. But everyone is just speculating about the lasting value of these investments. While traditional assessments of return on public investment in science and technology tend to track short-term impacts, such as salaries, patents, and licensing revenues, the main foundations for long-term development of a knowledge economy appear to rely on a number of less tangible accomplishments. For example: Connections - the networks that develop between researchers, entrepreneurs, and venture capitalists; Attention - the publicity generated by the research and its networks that attract businesses and talent to locate in a region; and Talent - the highly skilled workers that such research attracts and trains. These three indicators of economic success-henceforth called the CAT measures-have yet to be quantified and applied in a useful manner. That is the purpose of this study. It will be conducted in three parts, each with a culminating report. The first part will analyze the FY03 science and technology research activities and results for ASU's Proposition 301 initiatives. The second will develop a methodology for quantifying and utilizing the Institute's CAT measures. The third will field test the CAT methodology on a selected aspect of ASU's Proposition 301-funded research, and analyze results to provide Arizona decision-makers with recommendations to guide future
policy.http://www.asu.edu/copp/morrison/seedsofprosperity.htm
Permeablility:
People should avoid alcoholic drinks before working with toxic compounds, new research suggests. At least in laboratory rats, drinking ethanol compromises the skin's barrier to chemicals.
Researchers at Northwestern University's Feinberg School of Medicine in Evanston, Ill., fed alcohol to rats in amounts ranging from the equivalent of half a drink taken by a person to more than enough to make a person legally drunk. Beginning 2 hours later, team members took a patch of skin from each animal, applied a chemical to it, and measured how much passed through.
Almost all the alcohol doses increased skin permeability, reports Rhonda M. Brand, and the effect usually lasted at least 24 hours. In general, the greater the alcohol intake, the leakier an animal's skin became. Two to three times as much paraquat, an herbicide, or DEET, a mosquito repellent, passed through the skin of rats that had received the highest alcohol doses as passed through the skin of the teetotaler rats.
Two years ago, Brand's team reported similar findings for herbicide-exposed rats that were continually and heavily consuming alcohol. Skin from chronically drunk rodents transmitted two to five times as much paraquat, atrazine, and 2,4-dichlorophenoxyacetic acid (2,4-D) as did the skin of sober animals.
http://www.findarticles.com/p/articles/mi_m1200/is_12_169/ai_n16129978
2007-02-15 06:14:42
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answer #3
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answered by Duke 2
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