In analysis of transverse relaxation time (7"2) curves in a Carr-Purcell-Meiboom-Gill (CPMG) experiment in a multicomponent system originating from measurements of oil and water in rock cores, where internal magnetic field gradients broaden the line widths significantly, there is very little direct information to be extracted of the different components contributing to the total T 2 relaxation time curve. From the study of rock cores saturated with different amounts of crude oil and water, we show that witli an optimised experimental setup ir is possible to extract information from the nuclear magnetic resonance response that is not resolved by any other methods. This setup combines pulsed field gradient methods with the CPMG experiment utilizing data from both rock cores and bulk oiI and water. Then it becomes feasible to separate the signats from oil and water where the two-dimensional inverse Laplace transform ordinarily seems to rail.
In recent years the method of immobilization of living cells in Ca-alginate beads has gained a wide range of applications. In all cases high chemical stability of the immobilization material and mild conditions for the cells are prerequisites. However, in long-term experiments that may last for several days Ca-alginate may dissolve due to an exchange of Ca2+ with Na+, forming fluid Na-alginate. As well as Ca-alginate, the more chemically stable Sr-alginate and Ba-alginate are materials that have been used for the immobilization of living cells. In this study, the effects of Ca2+, Sr2+ and Ba2+ on growth, viability and intracellular free calcium concentration in a human leukemic T cell line (Jurkat) were investigated. The findings in this study, and the fact that Sr-alginate has a considerably higher chemical stability than Ca-alginate, led to the conclusion that Sr-alginate is a more suitable material for use in the entrapment of living cells in long-term studies.
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