Study of fossil tracks due to 50 < or = Z < or = 92 galactic cosmic ray nuclei in meteoritic crystals: results and perspectives.

A new approach to the problem of investigation of charge and energy spectra of ultra heavy Galactic cosmic ray nuclei, based on fossil track study of extraterrestrial olivine crystals has been developed. The results of an investigation of ultra heavy Galactic cosmic ray nuclei (Z=50-92) in meteoritic olivine crystals are presented. The technique was based on calibration of olivine crystals with accelerated Xe, Au, Pb and U ions and well-controlled partial annealing of "fresh" and "fossil" tracks. It allows us to determine the charge spectra and abundances of cosmic ray nuclei based on fossil track length study in meteoritic and Moon crystals. The comparative studies of the spectra of "fossil' tracks and tracks due to 208Pb and 238U nuclei have shown that the group of 210 micrometers "fossil" tracks, first observed in 1980 at JINR is due to Th-U nuclei-products of recent r-process nucleosynthesis in our Galaxy. The method in principle allows one to resolve Pt-Pb peaks in fossil tracks, to establish the upper limit of the abundance of Z>110 nuclei in the Galactic cosmic rays at the level < or = 10(-3) to the abundance of actinide nuclei and to get information on the history of Z>50 cosmic ray nuclei in time interval up to 220 M.Y.

Thermal control of drug release by a responsive ion track membrane observed by radio tracer flow dialysis.

The combination of a responsive hydrogel with a rigid porous supporting structure yield a membrane with high mechanical strength and high on-off-permeability ratio. A membrane consisting of an ion track filter with a thermally responsive lining was prepared by penetrating a 19 micron thick foil of poly(ethylene terephthalate) (PET) with swift heavy ions at a fluence of 5 x 10(5) ions/cm2, followed by etching of the ion tracks to generate an ion track filter with 2.9 micron pore diameter, onto which a thin layer of poly(N-isopropylacrylamide) (NIPAAm) hydrogel was grafted. It was revealed that the mass flow of various molecules (water, chloride-, choline+, insulin, and albumin) through the membrane could be thermally controlled. The on-off-permeability ratio ranged between 3 and 10 increasing with molecular weight. Over a storage time of 5 months the permeabilities varied up to a factor of 2.6, while the on-off-permeability ratio and temperature sensitivity remained practically constant.

Anisotropic diffusion in etched particle tracks studied by field gradient NMR.

Etched particle tracks produced after heavy ion irradiation of polymer foils are used as model systems to test the performance of NMR in a newly developed ultrahigh magnetic field gradient system. The stimulated NMR echo decay of molecules diffusing in the channels, formulated in terms of the self part of the intermediate scattering function, is anisotropic and yields the form factor of the channels.

Indomethacin pretreatment in continuous positive-pressure ventilation.

The purpose of the study was to investigate the possible involvement of prostaglandins (PG) and thromboxanes (TX) in the cardiovascular and pulmonary changes associated with the use of continuous positive-pressure ventilation (CPPV). Indomethacin (IND), an inhibitor of PG cyclo-oxygenase, was used to block the synthesis and release of PG and TX in the lung after alveolar stretch with CPPV. Groups of dogs received CPPV (buffer group) or CPPV + IND 5 mg/kh iv (CPPV + IND). Pulmonary edema or alveolar hemorrhage was evident in 5 of 6 buffer animals. This damage was also manifested by a 50% decrease in lung compliance. However, IND appeared to block development of lung tissue damage in 5 of 6 CPPV + IND dogs and compliance remained normal. A 52% lowering of cardiac index (CI) in the buffer group paralleled a 71% reduction of left ventricular dP/dt max (first derivative of left ventricular pressure). Peak transmural right heart filling pressure decreased only 15%. in contrast, the 38% decrement of CI in the CPPV + IND animals was coupled with a 98% reduction in filling pressure, but only a 25% decrease in dP/dt max. CPPV-induced changes may have been related, in part, to the release of cytotoxic negative inotrope(s) from damaged alveolar membranes because IND pretreatment blocked this damage.

Production of single pore membranes for the measurement of red blood cell deformability.

For the determination of the deformability of individual red blood cells, a measuring device was developed, simulating the passage of individual red blood cells in capillaries of the nutritive microcirculatiuon. The kernel of this device, described here, is a single pore membrane 4--6 microns in diameter and 10 to 50 microns in length. The combination of a heavy ion accelerator (containing a faster shutter system) with nuclear tract technology makes possibly the manufacture of a large number of single pore membranes necessary for clinical and pharmaceutical tests.