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Based on data of measurements in deep ice boreholes, as well as of radar and space geodetic observations in Antarctica and Greenland, a number of new features of the ice mass transport had been revealed. Note that these features do not correspond to the traditional but still hypothetical notions (ideas) of the monotonous and uniform spatial changes in the ice sheet dynamics. Using results of the long-term monitoring of the borehole coordinate axes at the Vostok station (down to 1920 m), east profile Vostok – Vostok 1 – Pionerskaya – Mirny (1409 km, down to the depth of 450 m), and analysis of radar sections, Russian specialists revealed the following: a) the Antarctic ice sheet has stratified changes in speed and a fan-like change in the flow direction along the depth; b) plastic firn layer has individual parameters of dynamics and actually flows down from more monolithic body of the ice sheet (the flow directions differ by 30–80°); c) in some places inside the sheet, the underlying ice masses flow faster than the upper ones. Researchers from the United States and Denmark registered on the radar sections of the lowest third of the ice domes in the central regions of the Antarctica (AGAP) and Greenland (NEEM) some folded structures, which were not typical of ice sheets (vertical amplitude of the folds is about 400 m, inclination of the wings is about 45 degrees or more). The tectonic analysis we have performed allows making a conclusion that a genesis of these ice structures is identical to the diapir folds and to diapirs which are formed at a displacement of lower plastic ice masses by the upper monolithic ones, or to echelon folds of crumpling of lower ice layers at their faster flow along original bed as compared with the overlying ice mass. This makes possible to suggest that a turbulent ice flow can occur in the spacious near-bottom and the most plastic area, and a model of the ice sheet dynamics is considered as extruding of underlying masses by the overlying ones. Specialists of the United States analyzed results of the radar interferometry obtained from satellites of Canada, the US, Europe, and Japan (RADARSAT-1, 2; Envisat ASAR; ERS-1/2; ALOS PALSAR) and determined a velocity of the flow of the day surface of the Antarctic ice sheet. They constructed a map of the 3D-structure of the ice flows and had revealed that the dominating ice diffluence from the central area down to the coastal zone is in a complicated way composed by many local streams. We conducted the morphological analysis and made the conclusion that these flows interact to one another under conditions of the strong differentiation of a surface inclination of the ice flow moving down along the mountain relief of original bedrock, and this process is similar to a merging of glaciers with individual characteristics due to different ice-catchments.

Nucleation of ice crystals in atmosphere is a result of condensation of water vapor on aerosol particle surface and heterogenic crystallization of the overcooled water micro-aggregations on surface irregularities. Crystal habit of ice nucleus and very small crystals (102 nm) corresponds to Gibbs–Wolf theorem and Thomson-Gibbs equation. Consequent growth of nucleated crystal is possible under condition of exceeding of water vapor concentration in atmosphere over the equilibrium vapor concentration over ice crystal. This equilibrium concentration for each crystal facet can be characterized by Clausius–Clapeyron relation with regard to its surface energy. The diagram of atmospheric ice crystals morphology in dependence from absolute and relative vapor supersaturation of atmosphere is developed. It is determined that the relation of height H and diameter D of atmospheric crystals increases at a growth of relative supersaturation, Δci/ci, but increases at a growth of absolute supersaturation, Δci = ci – ca. The alteration of H/D occurs gradually, which explains conditional character of delimitation on types on the base of this index. The field of absolute and relative supersaturation it is possible to subdivide relatively index H/D value in two parts: columnar forms area, where index H/D > 0.89 and lamellar forms area, where H/D < 0.89. Columnar and needle forms it is possible to characterize as low temperature forms, but lamellar, short-columnar and irregular forms – as high temperature forms. The variety of atmospheric crystal forms is subdivided on four basic groups: solid lamellar, solid columnar, dendrite lamellar and hollow columnar.

Based on the study of local volumes of minerals using the classical methods of isotope dilution and thermal ionization mass spectrometry (U–Pb ID TIMS), an isotopic study of pitchblende and galena is carried out at the Natali uranium ore occurrence (Northern Transbaikalia). For the first time, it was shown that the pitchblende mineralization at the ore occurrence has a Late Silurian (422 ± 4 Ma) age. Its formation is related to the Early–Middle Paleozoic collisional tectogenesis in the area of the Tonod uplift, accompanied by increased fluid activity. The Pb isotopic composition analysis in galena associated with pitchblende show that galena is enriched in radiogenic isotopes 206Pb and 207Pb, a source of which was ancient (Precambrian) concentrations of uranium. [ABSTRACT FROM AUTHOR]

Copyright of Caspian Journal of Environmental Sciences is the property of University of Guilan & Association of Universities of the Caspian Region States and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

When working with rare plant species, applying morphometric techniques is one of the main ways to obtain a representative data set on plant individuals and the state of particular populations growing in different ecological conditions and experiencing different degrees of anthropogenic load. Zygophyllum pinnatum, an understudied species growing on the territory of the Republic of Bashkortostan, the Orenburg region, and the Republic of Kazakhstan, is referred as a rare species. The purpose of the work is to study morphometric parameters and reveal the vitality structure of the Z. pinnatum coenopopulations in two regions of the Russian Federation (the Republic of Bashkortostan and Orenburg region) and in the north-west of the Republic of Kazakhstan (the Aktobe Region). Applying standard morphometric techniques, we analyzed the state of 16 coenopopulations of the species. Judging by most morphometric parameters, the leadership belongs to the individuals from the "Troitsk Cretaceous Mountains" coenopopulation located in the Sol-Iletsky District of Orenburg oblast, where, apparently, the most optimal plant conditions are formed (the absence of human impact and low projective cover of the grass stand to have a favorable effect). The minimum values for most parameters are recorded in the coenopopulations located on the territory of the Republic of Kazakhstan, resulting from arid growing conditions. The variability of most characters is within the normal range of the species response (Cv--5.0-44.6%). The discriminant function analysis revealed the morphostructural similarity of individuals from most coenopopulations. Regarding vitality, eight coenopopulations are prosperous, and another eight are depressed. The condition of the species coenopopulations is stable; however, the species is not provided with proper protection measures. Therefore, further monitoring of its habitats and improvement of environmental measures are necessary. [ABSTRACT FROM AUTHOR]

Three groups of industrial uranium deposits that differ in the distribution of lanthanides in U oxides have been recognized. A dependence of the REE distribution type on the Yttrium content and Yttrium index YI = (La + Ce)/Y that controls the formation of REE phases capable of selective accumulation of lanthanides has been discovered. This indicates the important role of crystal-chemical fractionation in the distribution of lanthanides. Preferable accumulation of Sm-Gd by U oxides has been found to occur at relatively low contents of Y. In Proterozoic uranium deposits, the yttrium specialization of oxides predominates, while in most Phanerozoic deposits the lanthanum-cerium specialization is typical. These results extend the possibilities of using REEs in ores for purposes of study of the genesis of various uranium deposits. [ABSTRACT FROM AUTHOR]

Fused yttrium-alumoborate glasses doped with ytterbium, silicon, chromium, and sodium were synthesized. The influence of the matrix on the "spectroscopic behavior" of chromium ions and the efficiency of their sensitization of Yb3+ luminescence was established by spectral-luminescence and EPR studies. It was found that (1) chromium in alkali-free glasses is mainly in the oxidation degree Cr(III) with an appreciable admixture of Cr(IV) and Cr(V), (2) the partial replacement of Al2O3 or B2O3 by SiO2 and Y2O3 by Yb2O3 affects to a different extent the relative concentration of optical centers of chromium ions, (3) the addition of alkali results in the formation of Cr(VI) centers as a result of oxidation of less charged chromium ions and predominantly tetracoordinated Cr4+ and Cr5+, (4) Cr3+ ions make the main contribution to the luminescence sensitization of Yb3+ ions, while Cr4+ ions and to a lesser extent Cr5+ play the role of luminescence quencher and internal filter. Sensitization of Yb3+ luminescence through the charge transfer band in Cr(VI) was found. An alkaline glass doped with Cr and Yb upon excitation through the sensitizer produced a luminescence quantum yield of 32% and the conditions for its enhancement were considered. It is shown that the temperature quenching of luminescence of Cr–Yb-containing glasses is significantly lower than that of Cr-containing glasses. [ABSTRACT FROM AUTHOR]

Wall pressure fluctuations in a turbulent flow are a source of noise and vibrations in elastic structures immersed in a flow. This paper presents the results of an experimental study on the effect produced by the height of a step on the spatiotemporal structure of wall pressure fluctuations in the vicinity of its side edge in the turbulent boundary layer. Measurements were performed in a subsonic low-noise wind tunnel of the Moscow Complex of the Zhukovsky Central Aerohydrodynamic Institute. The height of a step was varied from 3 to 17% of the incident-boundary-layer thickness. It has been shown that the area of the most intensive pressure fluctuations is located near the frontal side corner of the step. The characteristic Strouhal number determining the spectra of pressure fluctuations behind the leading edge of the step was established. An essential effect of the step height on the spatiotemporal structure of the pressure field in the vicinity of the side edge was shown. The obtained results evidence the existence of a strong correlation with the field of pressure fluctuations in the incident turbulent boundary layer in the case of steps with a small height. [ABSTRACT FROM AUTHOR]

The phenological responses of plants to changing weather conditions are very strong and can serve as an indicator of global climate change. If we understand how individual species respond to changing conditions, we can represent how ecosystems will change. The aim of this study was to analyze the exposure of climatic factors (air temperature and precipitation) on the flowering duration of the wild vascular plant species in the Karadag Nature Reserve (Crimea). In general, 152 species were taken into account with a number of phenological observations from 5 to 8 years. Correlation analysis between the flowering duration and the climatic parameters revealed a significant response in 89 (58.6%) species. Moreover, the climatic factors of the current vegetative season impacted 71 species flowering, previous vegetative season impacted four species flowering, and both vegetative seasons impacted 14 species flowering. Air temperature and precipitation equally impacted the flowering duration: air temperature impacted 35 (41.2%) species flowering; precipitation impacted 32 (37.7%) species flowering; both factors impacted 18 (21.1%) species flowering. The flowering duration was mostly negatively correlated with air temperature values and positively with precipitation amount. Mesophytes and the forest community species were the most sensitive to the climatic factors; euxerophytes and the steppe community species were the least sensitive to the climatic factors. [ABSTRACT FROM AUTHOR]

The uneven character of the distribution of O/O and U/U values was established in the vertical cross section of the productive sequence of the Dybryn uranium deposit (Vitim uranium-ore region, Buryatia). Both a deficiency and an excess of U in relation to the equilibrium U/U ratio in the vertical sequence may provide evidence for the extremely low rate of the infiltration water flow. The behavior of oxygen isotope characteristics for different size fractions of terrigenous rocks provides evidence for active uranium redistribution and openness of the isotope system of this element during interaction of terrigenous-sedimentary rocks with infiltration waters. [ABSTRACT FROM AUTHOR]

Considered is the process of ice nucleation in the atmosphere as a result of heterogeneous condensation of water vapor in surface inhomogeneities of aerosol particles and of subsequent heterogeneous crystallization of supercooled water accumulation. It is revealed that the size, structure, and composition of aerosol particles determine the thermal regime of crystallization. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Russian Studies (JORUS) / Rusya Araştırmaları Dergisi is the property of Rusya Arastirmalari Dergisi (RUSAD) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The variations in U/U values accompanying mobilization of U by fracture waters from uranium-bearing rocks, in which U occurs as a fine impregnation of oxides and silicates, were studied by the high-precision (±0.07‰) MC-ICP-MS method. Transition of U into the aqueous phase in the oxidized state U(VI) is accompanied by its isotope fractionation with enrichment of dissolved U(VI) in the heavy isotope U up to 0.32‰ in relation to the composition of the solid phases. According to the sign, this effect is consistent with the tendency of the behavior of U and U upon interaction of river waters with rocks of the catchment areas [11] and with the effect observed during oxidation of uraninite by the oxygen-bearing NaHCO solution [12]. [ABSTRACT FROM AUTHOR]

This paper presents the results of geochemical and isotope-geochemical (Sm–Nd) studies of the Upper Riphean (?) (in the Stratigraphic Scale of Russia) sedimentary rocks of the Urulungui and Dyrbylkei formations of the Daur Series in the Argun continental massif, as well as U–Th–Pb and Lu–Hf isotope studies of detrital zircons from these formations. Rocks of the Urulungui and Dyrbylkei formations differ significantly in their mineral composition and major-element composition, which is probably related to the degree of chemical weathering of source rocks. Analysis of the trace-element concentrations in the sedimentary rocks of the Urulungui and Dyrbylkei formations enabled us to establish that they were formed in a subduction-related setting. The presence of conglobreccias, conglomerates, gravelstones, fragments of igneous and volcanic rocks, the low level of roundness of clastic material, as well as the abundant Neoproterozoic detrital zircons in the formations, are evidence for tectonic and igneous activities in the region during sedimentation. Sedimentary rocks of the Urulungui and Dyrbylkei formations have two-stage Nd model ages of TNd(DM2) = 2.0–2.1 Ga and 1.6–1.8 Ga, respectively. The abundant Neoproterozoic zircons in sandstones of the Urulungui and Dyrbylkei formations suggest that Neoproterozoic igneous rocks that were widely developed within the western Argun continental massif were the main source of clastic materials. At the same time, the presence of Early Precambrian detrital zircons indicates that Early Precambrian rocks were also present in the source area. However, reliably dated Early Precambrian igneous and metamorphic rock associations have not yet been found within the Argun continental massif. Thus, it is possible that the rocks of the Daur Series form an "exotic block" involved in the Argun massif. [ABSTRACT FROM AUTHOR]

In recent years, the use of nanotechnology in human and veterinary medicine has made great progress, which could be a major breakthrough in addressing certain problems, including in the field of animal reproduction. Examples of potential applications make it possible to introduce nanotechnological methods of regulating reproductive function into practice more widely to promote livestock development. Studying the action of nanoparticles of dioxide silicon allows to optimize the methods of cryopreservation of sperm, promotes understanding of the mechanisms of functioning of germ cells, ovarian follicles and embryos. Prospective biocidal nanopreparations have been developed, the use of which provides for the increases of animal fertilization, immunobiological resistance, prevention of infertility and obtaining a healthy offspring. Nanoacquahelates have a modifying effect on physiological processes in animals, which is reflected in the activation of biosynthetic and energy processes in the body, stimulation of the cellular level of immunity. Use of them for both the treatment of animals suffering from mastitis and the stimulation of their reproductive function is suggested. In order to increase the therapeutic efficacy of the vitamin and hormone preparations, the addition of cerium-dioxide nanoparticles and rare-earth elements is used. Their application allows optimizing individual indicators of homeostasis and prooxidant-antioxidant system, to normalize the structure and function of the fetoplacental complex of pregnant animals and to increase the potential of newborn development, the effectiveness of therapy of females with mastodystrophy and gonadopathies, and males with andrological pathology. However, the precise mechanisms of the influence of nanoparticles on the body is still unknown; moreover, there are publications on the potential toxicity of nanoparticles that necessitates specific hypotheses and understanding of certain aspects of research. Thus, as nanotechnologies are in the early stages of development, it may take some time to produce meaningful results to perform the necessary research and clinical trials. This tool, which will evolve over the next few decades, will have major implications in veterinary science and reproduction inclusive. [ABSTRACT FROM AUTHOR]

In this work, using β-Ca3(PO4)2 as a structural model, a series of [Ca9Na3xY1−x(PO4)7 (CNYPO-I, 0 ≤ x ≤ 1/2) ← Ca3(PO4)2 → Ca9+yNa3/2−y/2Y(1−y)/2(PO4)7 (CNYPO-II, 0 ≤ y ≤ 1)] phosphors were prepared using a cationic heterovalent substitution approach. The substitution of Y3+ and Na+ for Ca2+ led to a redistribution of Eu2+ within the lattice and was accompanied by changes to the corresponding luminescence behavior. As the x and y values increased, the vacancies in the structure were gradually occupied by Na+ to form Na(4) sites that are conducive to Eu2+ occupation. When y = 1, the vacancies were completely occupied, and the Eu2+ emission peaks from Ca(1/2) and Ca(3) sites showed a significant blue shift. The underlying mechanism of that shift is discussed. The CNYPO-I (x = 0) sample displayed the best thermal stability; the effects of vacancies, thermal ionization and cross-over mechanism on thermal quenching are also discussed. As x and y increase, the thermal stability of the samples gradually decreased. Eu2+ and Mn2+ co-doped CNYPO-I (0 ≤ x ≤ 1/2) and CNYPO-II (0 ≤ y ≤ 1) phosphors achieved full coverage of the visible light region (400–800 nm). These white LEDs have relatively high color-rendering indexes (>80) and adjustable color temperatures from 2854–7000 K. This work provides an effective strategy for designing novel luminescent materials and realizing multi-site adjustment of activator ions. [ABSTRACT FROM AUTHOR]

There has been extensive research on the effects of evaporation on the isotopic ratio of lacustrine and marine water bodies; however, there are limited data on how ablation or sublimation from lake or sea ice influences the isotopic ratio of the residual water body. This is a challenging problem because there remains uncertainty on the magnitude of fractionation during sublimation and because ablation can involve mixed-phase processes associated with simultaneous sublimation, melting, evaporation, and refreezing. This uncertainty limits the ability to draw quantitative inferences on changing hydrological budgets from stable isotope records in arctic, Antarctic, and alpine lakes. Here, we use in situ measurements of the isotopic ratio of water vapor along with the gradient diffusion method to constrain the isotopic ratio of the ablating ice from two lakes in the McMurdo Dry Valleys, Antarctica. We find that during austral summer, the isotopic fractionation of ablation was insignificant during periods of boundary layer instability that are typical during midday when latent heat is highest. This implies that the loss of mass during these periods did not yield any isotopic enrichment to the residual lake mass. However, fractionation increased after midday when the boundary layer stabilized and the latent heat flux was small. This diurnal pattern was mirrored on synoptic timescales, when following warm and stable conditions latent heat flux was low and dominated by higher fractionation for a few days. We hypothesize that the shifting from negligible to large isotopic fractionation reflects the development and subsequent exhaustion of liquid water on the surface. The results illustrate the complex and nonlinear controls on isotopic fractionation from icy lakes, which implies that the isotopic enrichment from ablation could vary significantly over timescales relevant for changing lake volumes. Future work using water isotope fluxes for longer periods of time and over additional perennial and seasonal ice-covered lake systems is critical for developing models of the isotopic mass balance of arctic and Antarctic lake systems. [ABSTRACT FROM AUTHOR]

Rhamnogalacturonan I (RG-I) pectin is composed of backbone of repeating disaccharide units →2)-α-L-Rhap-(1→4)-α-D-GalpA-(1→ and neutral sugar side-chains mainly consisting of arabinose and galactose having variable types of linkages. However, since traditional pectin extraction methods damages the RG-I structure, the characteristics and health effects of RG-I remains unclear. Recently, many studies have focused on RG-I, which is often more active than the homogalacturonan (HG) portion of pectic polysaccharides. In food products, RG-I is common to fruits and vegetables and possesses many health benefits. This timely and comprehensive review describes the many different facets of RG-I, including its dietary sources, history, metabolism and potential functionalities, all of which have been compiled to establish a platform for taking full advantage of the functional value of RG-I pectin. [ABSTRACT FROM AUTHOR]

Single crystals of SmAl3(BO3)4 were synthesized by the group growth on seeds method. The crystal structure was solved using a single‐crystal experiment and the purity of the bulk material was proved by the Rietveld method. This borate crystallizes in the monoclinic C2/c space group with unit‐cell parameters a = 7.2386 (3), b = 9.3412 (5), c = 11.1013 (4) Å and β = 103.2240 (10)°. IR and Raman spectroscopic analyses confirmed the monoclinic structure of SmAl3(BO3)4. Under 532.1 nm excitation, luminescence spectra exhibit bands assignable to the transitions from 4G5/2 to 6H5/2, 6H7/2, 6H9/2 and 6H11/2. The similarity of the luminescence spectra of the trigonal and monoclinic polymorphs is explained by the minor role of Sm—O bond distortion and the primary role of rotational distortion of SmO6 octahedra. The smaller covalency of the Sm—O bond in alumoborates is deduced in comparison with galloborates. Calorimetric measurements did not reveal high‐temperature structural phase transitions up to a temperature of 720 K. [ABSTRACT FROM AUTHOR]