Metasomatic alteration associated with the formation of subvolcanic rocks of the Abagatuysky complex (Nerchinsk ore region, Eastern Transbaikalia)

Within the northeastern edge of the Borschovochny pluton, located in Eastern Transbaikalia, a complex of small intrusions is localized, represented by the subvolcanic bodies of the Early Cretaceous Abagatuysky andesite-dacite complex. These intrusions, along with significant dynamometamorphic (tectonic) transformations, produced the development of metasomatic alteration, united in three large rock associations — propylites, beresites, and argillisites. These metasomatic associations successively replace each other as they move away from the center of heat exposure of intrusions. In addition, each of these groups of metasomatites has its own unique internal mineral zonality, and the most productive of them, on the subject of gold ore mineralization, is the beresite association

Composition and conditions of the late Mesozoic volcanism occurrence of the northern part of the Borschovochny ridge (Eastern Transbaikalia)

On the basis of geochemical study results composition heterogeneity and formation conditions of late Mesozoic subvolcanic rocks from northern part of Borschovochny ridge by an example of shadoronsky and abgatuysky complexes are discussed. Obtained results show that volcanic rocks of both complexes have heterogeneous composition and differ from each other in level and other features of alkalinity. Rare and trace elements geochemistry study results show that there is a significant enrichment with LILE (Cs, Rb, Ba) and some depletion with HFSE (Nb, Ta), meanwhile the correlation between Th and Yb indicates conditions of active continental margin. Gd/Yb and La/Sm ratios allow to conclude that shadoronsky complex rocks originated from garnet-stable mantle source (partial melting of 5% of garnet peridotite), while abagatuysky complex rocks originated from transitional garnet-spinel mantle

PSA-stage Features of the Hybrid Membrane-sorption Oxygen Concentrator

The paper considers the principle of the organization of the hybrid membranesorption oxygen concentrator and the work of the PSA stage of the hybrid system. The use of hybrid membrane-sorption gas separation systems can significantly reduce the energy consumption of plants, as well as to neutralize such disadvantages as contamination of the product flow by the products of abrasion of sorbents, through the use of highly selective polymer membrane, and the restriction on the oxygen concentration when using a single membrane stage, through its use after the PSA stage. In this paper, we propose an arrangement for the operation of the PSA stage of a hybrid system consisting of three adsorbers and providing a constant product flow of the PSA stage necessary to ensure continuous feed flow to the membrane stage of the system. Each of the adsorbers in this system passes through three main stages: filling, displacement (adsorption), and discharge (desorption). Moreover, the filling is not from the compressor, but part of the product flow of the displaced adsorber. The results of the operation of the system organized by the proposed method are compared with the results of the operation of modern gas separation systems on the market.     Keywords: Sorption, air separation, pressure-swing adsorption, PSA, hybrid technologies, oxygen concentrator, recycling, oxyge

Cooling and heating by adiabatic magnetization in the Ni50_{50}Mn34_{34}In16_{16} magnetic shape memory alloy

We report on measurements of the adiabatic temperature change in the inverse magnetocaloric Ni$_{50}$Mn$_{34}$In$_{16}$ alloy. It is shown that this alloy heats up with the application of a magnetic field around the Curie point due to the conventional magnetocaloric effect. In contrast, the inverse magnetocaloric effect associated with the martensitic transition results in the unusual decrease of temperature by adiabatic magnetization. We also provide magnetization and specific heat data which enable to compare the measured temperature changes to the values indirectly computed from thermodynamic relationships. Good agreement is obtained for the conventional effect at the second-order paramagnetic-ferromagnetic phase transition. However, at the first order structural transition the measured values at high fields are lower than the computed ones. Irreversible thermodynamics arguments are given to show that such a discrepancy is due to the irreversibility of the first-order martensitic transition.Comment: 5 pages, 4 figures. Accepted for publication in the Physical Review

Geological structure and prospects of noble metal ore mineralization of the Khayrkhan gabbroid massif (Western Mongolia)

An analysis of the distribution of noble metals in zones of sulfide mineralization makes it possible to justify the isolation of four ore-bearing horizons with a specific geochemical zonation. A rise in the gold content relative to palladium and platinum is observed from the bottom upwards along the section of the stratified series of gabbroids. The study of the mineral phases of sulphides and the noble minerals itself indicates the evolution of hydrothermal solutions, which determines the different activity and mobility of the fluid (mercury, tellurium, sulfur) and ore (copper, nickel, iron, platinum, gold and silver) components

Role of Fe substitution on the anomalous magnetocaloric and magnetoresistance behavior in Tb(Ni1-xFex)2 compounds

We report the magnetic, magnetocaloric and magnetoresistance results obtained in Tb(Ni1-xFex)2 compounds with x=0, 0.025 and 0.05. Fe substitution leads to an increase in the ordering temperature from 36 K for x=0 to 124 K for x=0.05. Contrary to a single sharp MCE peak seen in TbNi2, the MCE peaks of the Fe substituted compounds are quite broad. We attribute the anomalous MCE behavior to the randomization of the Tb moments brought about by the Fe substitution. Magnetic and magnetoresistance results seem to corroborate this proposition. The present study also shows that the anomalous magnetocaloric and magnetoresistance behavior seen in the present compounds is similar to that of Ho(Ni,Fe)2 compounds

Anisotropic magnetic properties and giant magnetocaloric effect in antiferromagnetic RRMnO3_3 crystals (RR=Dy, Tb, Ho and Yb)

We have systematically investigated the magnetic properties and magnetocaloric effect (MCE) in $R$MnO$_3$ ($R$$=$Dy, Tb, Ho and Yb) single crystals. Above a critical value of applied field ($H_c$), $R$MnO$_3$ undergo a first-order antiferromagnetic (AFM) to ferromagnetic (FM) transition below the ordering temperature ($T_{N}^{R}$) of $R^{3+}$ moment and a second-order FM to paramagnetic (PM) transition above $T_{N}^{R}$. Both $H$ and $T$ dependence of $M$ shows that the system is highly anisotropic in the FM as well as PM states and, as a result, the magnetic entropy change ($\Delta S_{M}$) is extremely sensitive to the direction of applied field and can be negative (normal MCE) or positive (inverse MCE). For hexagonal HoMnO$_3$ and YbMnO$_3$ systems, a very small inverse MCE is observed only for $H$ parallel to c axis and it decreases with increasing $H$ and crosses over to normal one above $H_c$. On the other hand, for orthorhombic DyMnO$_3$ and TbMnO$_3$, though the inverse MCE disappears above $H_c$ along easy-axis of magnetization, it increases rapidly with $H$ along hard-axis of magnetization for $T$$\ll$$T_{N}^{R}$. Except for YbMnO$_3$, the values of $\Delta S_{M}$, relative cooling power and adiabatic temperature change along easy-axis of magnetization are quite large in the field-induced FM state for a moderate field strength. The large values of these parameters, together with negligible hysteresis, suggest that the multiferroic manganites could be potential materials for magnetic refrigeration in the low-temperature region.Comment: 10 pages, 11 figure