The exact solutions for the isotopic compositions and the concentrations of the two-reservoir model for mantle-crust evolution are given for arbitrary rates of crustal growth and of back flow to the mantle. The critical parameters are the chemical fractionation factors for crustal growth and refluxing and the integrated fractional mass-removal rates from the crust and the mantle. For the case w...

the present study was conducted to investigate the effects of ensiling pistachio by-product (pbp) on nutrient value, some physical and chemical parameters. fresh pbp was ensiled into a trench silo for three months and simultaneously amount of pbp was dried in front of the sun. chemical composition, buffering capacity, water holding capacity, protein fractionation according to cornell net carboh...

he efficiency of photosynthesis continues to interest biochemists, biologists, and plant physiologists. Scientists interested in CO2 uptake are concerned about the extent to which the uptake rate is limited by such factors as stomatal diffusion and the chemistry of the CO2 absorption process. The fractionation of carbon isotopes that occurs during photosynthesis is one of the most useful techni...

Understanding deuterium fractionation is currently one of the greatest challenges in astrochemistry. In this contribution deuteration experiments of the series CHn , n = 2–5, in a low temperature 22-pole ion trap are used to systematically test a simple chemical rule predicting which molecular ion undergoes deuterium exchange in collisions with HD. CH+4 turns out to be a problem case, where pre...

The slope of the three-isotope plot for the isotopomer fractionation by direct or nearly direct photodissociation is obtained using a perturbation theoretical analysis. This result, correct to first order in the mass difference, is the same as that for equilibrium chemical exchange reactions, a similarity unexpected a priori. A comparison is made with computational results for N2O photodissocia...

heparin was isolated from whole clam tissue marcia opima . purification of multimilligram quantities of heparin from this tissue sample permitted a thorough examination of its anticoagulant activity characterization, which was partially purified by fractionation by anion exchange chromatography using deae cellulose column. the isolated crude and partially purified fractionated sample showed met...

soil organic matter is an indicator of soil, agriculture and environmental quality, playing important roles in soil strength and sound environmental functions. size and chemical fractionation of soil organic matter are long-standing approaches in clarifying their key role in soil processes. twenty seven surface samples (0-20 cm) and 6 pedons from different landform units were sampled and descri...