[en] Experimental data for the effect on the unit-transfer height of the NaX zeolite grain size and the flow rate of a gaseous H₂-HT mixture in a sorption column during the separation in it of H isotopes are analyzed in order to determine the previously unpublished diffusion coefficients of HT in gaseous H₂ and crystals of this zeolite. The results are compared with the analogous coefficients for deuterium (D₂). At 77 K and 0.1 MPa, the diffusion coefficients of HT and D₂ in gaseous H₂ are approximately 0.155 cm²/sec and 0.116 cm²/sec, respectively. The diffusion coefficients of these same isotopes at 77 K in NaX zeolite crystals are approximately 1.42·10^-10 cm²/sec and 0.67·10^-10 cm²/sec

[en] After some generalities on the tritium utilization, this isotope specificities and the interest of the solid storage, this presentation detailed the different materials used: the hydrides. They have the advantage of delivering high purity tritium ³He free, but the ³He trapped in the metal induces large structural and microstructural changes in the host lattice leading to modifications of tritium storage properties with aging time which can be seen on Pressure-composition isotherms. In this paper the P-c isotherms evolution are followed and the created defects are characterized by X diffraction and transmission electronic microscopy. (A.L.B.)

[en] Prophase chromosomes presenting the loops/scaffold configuration were obtained in spreads of peripheral blood cells from normal and affected subjects. A distinct class of loops condensed in a chromatin body of variable diameter was observed. These loops are highly folded, have altered beads, present lateral fibrils, and their fragment forming rings. These fibrils incorporate 5-³H uridine as demonstrated by high resolution autoradiography. The nucleosomal alterations were explained as a result of the low ionic strength medium used, with the rings being indicative of repetitive DNA sequences. (Author)

[en] Elemental tritium HT is found to undergo practically complete conversion to tritiated water, HTO, in the upmost centimeters of the soil specimens. HTO is rapidly diluted by the total water content of the soil. HT penetration into deeper soil layers is hampered with increasing water content of the soil. This is why the deposition rate V_d is primarily a function of water content of upper soil layers of a given soil type (here: ploughed field on para-brown earth, regionally common type of cultivation). The water content of open land especially depends on the ambient air temperature, and the deposition rate is affected by the weather and the soil cultivation. Thus the annual variations of temperature determine the time-related curve of the deposition rate, which reaches its maximum in the summer season. (orig./PW)

[en] The frequency of DNA-sinthetizing cells in the basal layer of the gingival epithelium of the first lower molar region of young and adult mice of both sexes was studied using ³H-thymidine and radioautography. (M.A.C.)

[en] The relative abundance of tritiated-airborne species was studied for the air of the beam-line tunnel at high-energy accelerators as well as atmospheric air. The tritium produced via nuclear spallation reactions in the accelerator-tunnel air exists in the chemical forms of HTO and HT. The HT-to-HTO ratio was about 2 x 10^-2 on the average, being appreciably smaller than that in atmospheric air. The reaction mechanisms of accelerator-produced tritiums were discussed on the basis of the similarity to the reactions by cosmic-generated tritium. HT is likely to be formed directly through the reaction of a recoiling tritium with H₂O. On the other hand, the HT-to-HTO ratio for the present atmospheric air indicates that tritium distributions have been largely modified by the release of man-made tritium into the air. (author)

[en] A mathematical model was developed to simulate the metabolism of HT gas in humans. The rate constants of the model were estimated by fitting the calculated curves to the experimental data by Pinson and Langham in 1957. The calculations suggest that the oxidation of HT gas (which probably occurs as a result of the enzymatic action of hydrogenase present in bacteria of human gut) occurs at a relatively low rate with a half-time of 10-12 hours. The inclusion of the dose due to the production of the HT oxidation product (HTO) in the soft tissues lowers the value of derived air concentration by about 50%. Furthermore the relationship between the concentration of HTO in urine and the dose to the lung from HT in the air in lungs is linear after short HT exposures, and hence HTO concentrations in urine can be used to estimate the upper limits on the lung dose from HT exposures. (author)

[en] Abstract only

No abstract available

[en] Abstract only