Membrane separation for helium extraction from natural gas gained increased interest recently. Several vendors offer membrane elements for helium extraction, although data on their performance and operating experience are unpublished. The aim of this work was to obtain and study the separation performance of asymmetric hollow-fiber membrane element from commercial polyamide-imide Torlon®, in conditions close to the industrial process of helium extraction from natural gas. A membrane element with an active area of 0.177 m2, a helium permeance of 100 l(STP)/(m2·h·bar), and a selectivity α(He/CH4) = 340 was produced. This corresponds to a selective layer thickness of 82.3 nm, which was confirmed by SEM and resistance model calculations. The obtained membrane element was employed to decrease the concentration of helium in its binary mixture with methane from 0.4% to 0.05%. A relationship of separation characteristics from transmembrane pressure is also presented. At 70 bar and a stage cut of 2.7%, the feed flow rate was 0.16 m3(STP)/h, which yielded a helium permeate concentration of 14.7%. At 80 bar, a decrease in permeance to 60 l(STP)/(m2·h·bar) and in selectivity to 240 was observed. It was shown that the main reason for aging was the increased support resistance, due to a partial compaction of pores with a radius of less than 15 nm.

A c. 9720-year historyof a mountain lake-mire complex on the Shufan Plateau (southern Primorye, Russian Far East) is based on a multi-proxy study of peat deposits. The chronology is based on eight radiocarbon dates in addition to two dated tephra horizons. The sediment contains eight cryptotephra layers attributable to Baitoushan, a volcano on the Korea/China border. Pollen, diatom and botanical macrofossil analyses indicate climate fluctuations during the Holocene and a compositional response of biodiverse mountain forests to changes in temperature and humidity. Widespread, diverse broadleaf-dominated forest marked awarm Early Holocene (~9500-9280 cal. a BP). Korean pine (Pinus koraiensis) rose to dominance in the Middle Holocene (afterc. 7630 cal. a BP). Evergreen conifers, fir (Abies) in particular, became widespread after 2.9 ka BP and show a positive response to the Little Ice Age cooling. Over the c. 10 000-year record, moisture appears largely controlled by gradually declining intensity of the summer monsoon, trending from moist conditions in the Early Holocene to cooler and drier conditions in the Late Holocene with shorterterm hydrological changes superimposed. Peat composition indicates significant changes in mire vegetation, and diatom assemblages indicate four stages of inundation and three dry stages in the basin, probably controlled by precipitation changes. The initial importance of atmospheric precipitation shifted over time to a greater input from groundwater. During a long episode in the Late Holocene the basin may have dried out. Forest fires occurred during much of the Middle and Late Holocene, and their prominence, as marked by macro-charcoal, is related to changes in humidity. Human activities mark the past few centuries. Medieval fires were probably anthropogenic, and there is evidence of agricultural impact on the landscape during the Jin Empire settlement period 900-700 years ago and of more recent forest exploitation, particularly a reduction in conifer taxa.

In this work, polysulfone hollow fibers with oxygen permeance 70 L (STP)/(m2·h·bar) and selectivity α(O2/N2) = 6 were obtained. A decrease in the dope solution temperature allowed to diminish macrovoids due to the increase of the dope viscosity from 15.5 Pa·s at 62 °C to 35 Pa·s at 25 °C. To reduce the fiber diameter, thereby increasing the packing density, they were spun at high linear velocities. A hollow fiber membrane element was produced with effective membrane area 2.75 m2 and packing density 53%. Its air separation performance was evaluated to bridge laboratory studies and practical application.

This work was focused on the study of hypochlorite treatment on the pore size distribution of membranes. To this end, ultrafiltration membranes from a polysulfone/polyvinylpyrrolidone blend with a sponge-like structure were fabricated and exposed to hypochlorite solutions with different active chlorine concentrations for 4 h at ambient temperature. Liquid–liquid displacement and scanning electron microscopy were employed to study the limiting and surface pores, respectively. After treatment with 50 ppm hypochlorite solution at pH = 7.2, a five-fold increase in water permeance up to 1400 L/(m2·h·bar) was observed, accompanied by a 40% increase in the limiting pore sizes and almost a three-fold increase in the porosity. After 5000 ppm treatment at pH = 11.5, a 40% rise in the maximum limiting pore size and almost a two-fold increase in the porosity and permeance was observed, whereas the mean pore size was constant. Apparently, changes in the membrane structure at pH = 11.5 were connected with polyvinylpyrrolidone (PVP) degradation and wash-out, whereas at lower pH and despite lower active chlorine concentration, this process was coupled with polysulfone (PSf) destruction and removal.

Much attention is paid to studies of the processes occurring in heterogeneous catalysis with the use of nanomaterials, in particular, photocatalysis. Titanium dioxide and zinc oxide are among the most widespread photocatalysts due to their high chemical stability, suitable band gap, and rather high lifetime of nonequilibrium electron-hole pairs. In order to increase the photocatalytic activity (PCA) of these materials, including the case of a visible light action, various approaches are applied, in particular, the development of a composition material with a metal-semiconductor or semiconductor-semiconductor contact. We have chosen semiconductors of n-type (WO 3 ) and p-type (CuO) as components of such composites because of their potential positive influence on the PCA of titanium dioxide at the expense of spatial separation of nonequilibrium charge carriers and, respectively, increase in their lifetime. In order for the obtained composites to be commercially valuable, we have chosen a method of synthesis by modifying the ready TiO 2 preparations, including those that are commercially available (Degussa P25). It has been shown that the modification with CuO lowers PCA of titanium dioxide, while the modification with WO 3 enhances it by 25%. It has been demonstrated that WO 3 /TiO 2 composite manifests PCA under visible light illumination.

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