No abstract

No abstract

An effect of substitution of deuterium for protium in molecules of 17 solvents on 129 Xe NMR shifts was studied. The variation range of solvent-induced isotope xenon shifts 5 exceeds 5 ppm and lies in the range from -1.18 ppm (in CH 2 OD solution) to 3.92 ppm (in D 2 0) at 28°C. Experimental results agree with the concept that interaction of xenon atoms with solvent molecules is determined predominantly by dispersion forces. Correlations of Ss with the isotope effect on polarizability, boiling point, and vapor pressure of solvents were established. Anomalous manifestation of properties of aqueous solution was detected.

The high sensitivity of the 129Xe nuclear magnetic resonance (NMR) chemical shift to the environment was used for characterization of biological tissues and plants. The xenon gas was dissolved under moderate pressure by means of a special device in small pieces of human and animal tissues (heart, muscle, lung, kidney, liver, spleen, brain, sinew, cartilage and hypodermic fat) or plants (leaves, stems, grains, fruits) and the NMR parameters were measured in vitro. The observed line with the chemical shift '-180 ppm was attributed to the xenon located in various cellular structures such as lipid shells, intracellular formations. A xenon spectrum in the lungs obtained in vitro coincides with that in the lungs of a mouse measured in vivo by other investigators. The NMR parameters were found to reveal noticeable distinctions between normal and tumour-affected tissues. The analysis of the 129Xe NMR spectra of the sinew and the cartilage revealed the dependence of the magnetic parameters on the age of the substance. This fact could be accounted for by the changes of the absorption ability of a biological system due to age transformations. The results obtained in comparison with biochemical data reveal the promissory outlook of 129Xe NMR for the investigation of the state of biological tissues and for medical diagnostics.

No abstract