Dynamic characteristics of light emission accompanying cryocondensation of nitrous oxide and ethanol

We report new results in the study of cryoradiation accompanying the condensation of some gas. The main objectives of this research are: (i) check a broader range of substances for their ability to cryoradiation; (ii) the study of the nature of radiation and its relaxation characteristics; (iii) the study of thermally stimulated processes in condensed samples. Of the compounds tested only nitrous oxide and ethanol exhibited the ability to generate cryoradiation during condensation from the gas phase. Separate flashes detected by a photomultiplier represent a superposition of a series of successive relaxation processes of individual regions, somehow related to each other. It is possible that such areas are crystallites containing a set of molecules of nitrous oxide/ethanol, which are in metastable states with different activation energies. Radiation by these molecules during the transition into the ground state induces successive relaxation processes of molecular groups according to their activation energy distributions. Nonequilibrium radiative states forming in the process of cryocondensation of nitrous oxide and ethanol may have different nature of the activation energy distribution and this could explain the difference in the character of the radiation relaxation in these substances

Analysis of mating system in two Pinus cembra L. populations of the Ukrainian Carpathians

In natural pine populations, a mixed mating system is typical,characterized by the proportions of selfed and outcrossed seeds. Swiss stone pine(Pinus cembra L.) is one of the least studied European conifers in this respect. The mating system of six polymorphic allozyme loci were studied in haploid megagametophytes and diploid open-pollinated embryos in two stands located in theEast Carpathians. In the 'Gorgany' population (24 trees, 198 seeds) the mean singlelocus estimated outcrossing rate (ts) was 0.731, and the multilocus estimate (tm) was 0.773. In the 'Yayko' population the outcrossing rate was lower (27 trees, 213 seeds, ts=0.645, tm=0.700), suggesting 23-30% of seeds are self-pollinated. Correlation ofoutcrossing rate estimates among loci was less than 1, (0.300 in 'Gorgany' and 0.469 in 'Yayko') indicating biparental inbreeding occurred. Differences between tm and ts (0.042 in 'Gorgany' and 0.056 in 'Yayko') can also be influenced by consanguineous mating, indicated by the presence of spatial and genetic family structure. In small isolated populations of Pinus cembra, which are typical for the Carpathian part of the species' range, inbreeding depression may negatively affect seed quality. The high proportion of selfed seeds observed here can be expected in any seedlot of this species and should be taken into account while planning gene conservation orreforestation measures. Maternal trees in these populations showed no heterozygote deficiency at these allozyme loci, and instead showed increased proportions of heterozygotes (inbreeding coefficient FIS = -0.200 in 'Gorgany' and -0.142 in 'Yayko'). Balancing selection may explain heterozygosity levels up to and above equilibrium proportions

Structure and phase transition peculiarities in solid nitrous oxide and attempts at their explaination

Cryogenic vacuum deposited films of nitrous oxide were studied at the following conditions: a mirror-like silver-coated copper substrate; deposition temperature 16 K; gas phase pressure during deposition 10⁻³ Pa. Anal-ysis of the IR-spectrometric and thermodesorption data leads to the following conclusion. The transition from the amorphous to crystalline state in the vicinity of 40 K proceeds in several steps which reflect relaxation processes related to different molecular vibrations. The differences in the temperature intervals of the transitions are de-termined by the activation energies of relevant vibrations. It was shown that cryocondensation at 16 K is accom-panied by appearance of flashes on the condensate surface. Based on the uniform nature of the observed processes, a model based on several possible isomorphic molecular states of nitrous oxide is suggested

Physical modeling of the formation of clathrate hydrates of methane

Nowadays natural gas hydrates attract special attention as a possible source of fossil fuel. According to various estimates, the reserves of hydrocarbons in hydrates exceed considerably explored reserves of natural gas. Due to the clathrate structure the unit volume of the gas hydrate can contain up to 160–180 volumes of pure gas. In recent years interest to a problem of gas hydrates has considerably increased. Such changes are connected with the progress in searches of the alternative sources of hydrocarbonic raw materials in countries that do not possess the resources of energy carriers. Thus gas hydrates are nonconventional sources of the hydrocarbonic raw materials which can be developed in the near future. At the same time, mechanisms of methane clathrate hydrates formations have not reached an advanced level, their thermophysical and mechanical properties have not been investigated profoundly. Thereby our experimental modeling of the processes of formation of methane clathrate hydrates in water cryomatrix prepared by co-condensation from the gas phase onto a cooled substrate was carried out over the range of condensation temperatures 12–60 K and pressures 10⁻⁴ –10⁻⁶ Torr. In our experiments the concentration of methane in water varied in the range of 5–90%. The thickness deposited films was 30–60 μm. The vibrational spectra of two-component thin films of CH₄+H₂O condensates were measured and analyze