Heterogeneous body properties

Chemical combination or chemical composition is the union of several heterogeneous bodies from which results a new mixt body which has properties different from and intermediate between the substances which served to form it it is what Becher and Stahl have denominated mix tion, and what we call chemical combination or chemical composition ... 

Presolar stardust discovered to date in meteorites constitute no more than 0.5%o of the total mass of the samples, and one common chemical property is that they are acid resistant. Isotopic heterogeneity could also be present in less refractory phases like silicates, provided parent body metamorphism did not erase the differences. Noble gases are not discussed here because they are depleted by many orders of magnitude relative to the Sun and can be dominated by trace exotic minerals. Nitrogen is not discussed for the same reason. The... 

Bench-scale testing of the biooxidation of minerals is a major exercise in view of the number of parameters that have to be evaluated, including pH, temperature, nutrient and oxygen supply, particle size of the ore, and pulp density (percentage solids). It is complicated further because of the heterogeneity of the ore sample. Samples from the same ore body can display considerable variation in properties. It is also important to check the ion-exchange properties of the mineral. 

The simplest static property is the mean coordination number, , which is loosely defined as the average number of pore throats per pore body (Dullien, 1991). For spatially periodic systems, such as cubic packing of uniform spheres, it is relatively easy to determine . Methods of estimating for more heterogeneous porous media are reviewed by Sahimi (1995). 

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