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

Indicators of Pasture Digression in Steppe Ecosystems of Mongolia

The research shows that widely used key measures of vegetation structure (species diversity, projected cover and above-ground phytomass) are not always suitable as indicators of pasture degradation. Based on an analysis above-ground phytomass composition, new quantitative indices are offered that give a more realistic picture of rangeland condition in Mongolia

Restoration of the Soil and Vegetation in Sandy Land with Different Stages of Deflation

The aim of this work is to reveal the features of fallow sandy lands with different stages of deflation. The virgin soil-vegetation cover was the reference point: plots with light and strong deflation were compared with it. The soil deflation stages were determined by the presence or absence of layers characteristic of the backgroundsoils of the territory. The restoration of vegetation depends on the activity of wind erosion, the properties of the soils and substrata emerging on the soil surface. Studies have shown that the soil properties of deflated plots contradict the background and classical schemes of fallow land recovery. Keywords: Trasbaikalia, Barguzin Depression, sandy lands, plant-soil cover, soil deflation, vegetation restoratio

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

Climate drove the fire cycle and humans influenced fire occurrence in the East European boreal forest

Understanding long-term forest fire histories of boreal landscapes is instrumental for parameterizing climate-fire interactions and the role of humans affecting natural fire regimes. The eastern sections of the European boreal zone currently lack a network of annually resolved and centuries-long forest fire histories. To fill in this knowledge gap, we dendrochronologically reconstructed the 600-year fire history of a middle boreal pine-dominated landscape of the southern part of the Republic of Komi, Russia. We combined the reconstruction of fire cycle (FC) and fire occurrence with the data on the village establishment and climate proxies and discussed the relative contribution of climate versus human land use in shaping historic fire regimes. Over the 1340-1610 ce period, the territory had a FC of 66 years (with the 90% confidence envelope of 56.8 and 78.6 years). Fire activity increased during the 1620-1730 ce period, with the FC reaching 32 years (31.0-34.7 years). Between 1740-1950, the FC increased to 47 years (41.9-52.0). The most recent period, 1960-2010, marks FC's historic maximum, with the mean of 153 years (102.5-270.3). Establishment of the villages, often as small harbors on the Pechora River, was associated with a non-significant increase in fire occurrence in the sites nearest the villages (p = 0.07-0.20). We, however, observed a temporal association between village establishment and fire occurrence at the scale of the whole studied landscape. There was no positive association between the former and the FC. In fact, we documented a decline in the area burned, following the wave of village establishment during the second half of the 1600s and the first half of the 1700s. The lack of association between the dynamics of FC and the dates of village establishments, and the significant association between large fire years and the early and latewood pine chronologies, used as historic drought proxy, indirectly suggests that the climate was the primary control of the landscape-level FCs in the studied forests. Pine-dominated forests of the Komi Republic may hold a unique position as the ecosystem with the shortest history of human-related shifts in fire cycles across the European boreal region

Microstructure and mechanical properties of V-4Ti-4Cr alloy as a function of the chemical heat treatment regimes

The regularities of the formation of a heterophase structure and mechanical properties of V–4Ti–4Cr alloy as a function of thermomechanical and chemical heat treatments are studied. The regimes of thermomechanical treatment which provide the formation of a heterophase structure with a homogeneous volume distribution of oxycarbonitride nanoparticles with a size of about 10 nm and an increase in the volume content and thermal stability of this phase and which provide an increase in the temperature of alloy recrystallization are developed. The formation of the heterophase structure results in a substantial (up to 70%) increase in the short-term high-temperature strength of the alloy at T = 800°C. The increase in the strength is achieved while keeping a rather high level of plasticity

Гемодинамическая оценка устройства генерации пульсирующего потока в системах обхода левого желудочка сердца

Objective: to investigate the efficiency of a device that generates pulsatile flow during constant-speed axial-flow pump operation for use in left ventricular assist devices.Materials and methods. The pulsatile flow-generating device, hereinafter referred to as «pulsator», consists of a variable hydraulic resistance made in the form of a hull. A tube of elastic biocompatible material featuring an inner diameter of 11 mm is installed inside it. In the systolic phase of the left ventricle, due to systolic pressure, the elastic tube is fully opened, minimizing resistance to blood ejection. In the diastolic phase, due to suction action of the flow pump operating in constant revolutions, the elastic tube partially closes, creating additional hydraulic resistance to blood flow, which leads to reduced diastolic aortic pressure. Comparative assessment of axial-flow pump operation in pulsating and non-pulsating modes was carried out on a hydrodynamic stand that simulated the cardiovascular system. The following indices were calculated: arterial pressure pulsation (Ip), in-pump flow pulsation (AQ), energy equivalent pressure (EEP) and surplus hemodynamic energy (SHE).Results. When comparing axial-flow pump operation in pulsatile and continuous mode, arterial pressure pulsation index, in-pump pulsation index, and SHE index increased by 2.13 ± 0.2, 3.2 ± 0.2, and 2.7 ± 0.15 times, respectively, while EER index remained unchanged.Цель работы: исследование эффективности устройства генерации пульсирующего потока крови при работе осевого насоса с постоянной скоростью вращения для использования в системе обхода левого желудочка сердца.Материалы и методы. Устройство генерации пульсирующего потока, именуемое в дальнейшем «пульсатор», состоит из переменного гидравлического сопротивления, выполненного в виде корпуса с установленной внутри него трубкой из эластичного биосовместимого материала с внутренним диаметром 11 мм. В систолической фазе левого желудочка сердца за счет систолического давления эластичная трубка полностью раскрывается, минимизируя сопротивление выброса крови. В диастолической фазе за счет присасывающего действия насоса, работающего в режиме постоянных оборотов, эластичная трубка частично смыкается, создавая потоку крови дополнительное гидравлическое сопротивление, что приводит к уменьшению диастолического аортального давления. Сравнительная оценка работы осевого насоса в пульсирующем и непульсирующем режиме проводилась на гидродинамическом стенде, имитирующем сердечно-сосудистую систему с расчетом индексов: пульсации артериального давления (Ip), внутринасосной пульсации потока (AQ), энергии эквивалентного давления (ЕЕР) и избыточной гемодинамической энергии (SHE).Результаты. При сравнении работы осевого насоса в пульсирующем и непрерывном режиме индекс пульсации артериального давления увеличивался в 2,13 ± 0,2 раза, индекс внутринасосной пульсации увеличивался в 3,2 ± 0,2 раза, индекс SHE увеличивался в 2,7 ± 0,15 раза, индекс ЕЕР оставался без изменения

The effect of thermomechanical treatment regimes on microstructure and mechanical properties of V-Me(Cr, W)-Zr-C alloys

The regularities of the formation of a heterophase structure in dispersion-strengthened vanadium V–Me(Cr, W)–Zr–C alloys are studied as a function of the regimes of their thermomechanical treatment. The regimes of treatment providing a substantial increase in the dispersity and homogeneity of spatial distribution of ZrC particles, temperature of recrystallization, and high-temperature (at T = 800°C) short-time strength are found in comparison to conventional treatment regimes