The standardization and certification procedures of cryogenic equipment in Kazakhstan

The complex of procedures on stepwise carrying out actions of standardization and certification of liquid nitrogen, argon and oxygen gasificator G-200 is considered. In the process of organization of standardization and certification procedures the set of regulatory documents was developed that allow starting small-scale production of gasificators in Kazakhstan. Thus the emphasis on the potential incorporation of the requirements of such documents is placed from the Eurasian Economic Union

Marginal imprint of human land use upon fire history in a mire-dominated boreal landscape of the Veps Highland, North-West Russia

Dendrochronological reconstructions inform us about historical climate-fire-human interactions, providing a means to calibrate projections of future fire hazard. Most of these reconstructions, however, have been developed in landscapes with a considerable proportion of xeric sites that could potentially inflate our estimates of the historic levels of fire activity. We provide a 420-year long reconstruction of fires in a mire-dominated landscape of the Veps Nature Park, North-West Russia. The area has mostly escaped large-scale forestry operations in the past and is an example of pristine mid-boreal vegetation with a high (approximately 30% for the area studied) proportion of waterlogged areas with ombrotropic mires. The historical fire cycle was 91.4 years (90% confidence intervals, CI 66.2-137.6 years) over the 1580-1720 period, decreasing to 35.9 (CI 28.1-47.6 years) between 1730 and 1770, and then increasing again to 122.7 years (CI 91.0-178.0 years) over the 1780-2000 period. Early season fires dominated over late season fires during the reconstruction period. We documented a higher fire activity period between 1730 and 1780, resulting from the increase in early season fires. This period coincided with one of the largest multi-decadal declines in the reconstructed spring precipitation since 1600 CE, although we found no significant relationship between fire and precipitation over the whole reconstructed period. The nine largest fire years were associated with negative summer precipitation and positive summer temperature anomalies over the study region. Land-use history of the area did not appear to have an effect on historical fire dynamics. Modern (1996-2016) fire records indicate a regional fire cycle of ~ 1300 years, featuring a pronounced pattern with early (April-May) and late (July-September) season fires. The uniform fire cycle in the area since 1780, occurrence of nine largest fire years during years with spring-summer droughts, and low ignition frequencies over the last 420 years (0.005 to 0.037 ignitions per year and km2) suggest that the fire regime of the Veps Highland remained largely natural until the onset of the 20th century

Environmental controls of the northern distribution limit of yellow birch in eastern Canada

To evaluate environmental controls of yellow birch (Betula alleghaniensis Britton) distribution at its northern distribution limit in eastern Canada, we analyzed abundance, age structure, biomass accumulation rate, and growth sensitivity to climate of this species at 14 sites along a 200 km latitudinal gradient spanning three bioclimatic domains and reaching frontier populations of this species in western Quebec. We observed a large variability in seedling density across domains and presence of sites with abundant yellow birch regeneration within all three bioclimatic domains. Seedling density was positively correlated to mean age and abundance of yellow birch trees in the canopy, while sapling density was positively associated with dryer habitats. Growth patterns of canopy trees showed no effect of declining temperatures along the south-north gradient. Environmental controls of birch distribution at its northern limit were realized through factors affecting birch regeneration and not growth of canopy trees. At the stand scale, regeneration density was strongly controlled by local site conditions and not by differences in climate among sites. At the regional scale, climate variability could be an indirect driver of yellow birch distribution, affecting disturbance rates and, subsequently, availability of suitable sites for regeneration

Molecular dynamics simulation of thermodynamic and transport properties of H-bonded low-temperature substances

The results of modeling of isotopic water mixture clusters in nitrogen and argon cryomatrices are presented. Earlier, our experimental studies of water mixture in cryomatrix have shown that changes in the concentration of analyte in matrix leads to a splitting of the absorption bands characteristic frequencies of the molecules in the IR spectrum. Moreover the multiplicity of characteristic absorption bands in the IR spectrum remained unchanged during heating of the samples from the condensation temperature to the sublimation temperature of the matrix element. In order to find out what structure of clusters is responsible for the immutability of the absorption bands in the vibrational spectrum during thermal cycling of the samples, computer research of water molecules enclosed in nitrogen and argon cryomatrices by the molecular dynamics simulation was conducted. For this purpose, theoretical studies were carried out using computer software packages, that implement used by us semi empirical and ab initio molecular dynamics methods. As a result of the research, the data must be obtained are of theoretical interest for summarizing the physical and chemical properties of systems, consisting of water molecules, and their combination with inert gases for studying the properties of molecular crystals composed of small molecules