Снежники Лагонакского нагорья (Западный Кавказ)

The article presents results of investigation of snowfields on the Lagonaky plateau: conditions of their formation, distribution and dynamics. Snow patches are the most characteristic elements of the high-mountain landscapes of the Lagonaky plateau. In warm seasons, they are widely distributed on local flat-topped ridges of the Lagonaky: Abadzeshsh Murzikao, Kamennoe and others, as well as on the mountain masses Fisht, Pshehasu, Oshten, and Nagoychuk. Morphological and climatic conditions of the Lagonaky Highlands are unique and favorable for formation of snow patches and long preservation of them during the spring-summer periods. These conditions are high mountain ridges with flat tops, negative karst forms of the relief as well as a favorable wind regime with long winter snow storms and heavy snowfalls. Snow patches result from snow transport and accumulation after strong snow-drift on the leeward slopes. The avalanche snow patches arise when avalanches release from steep and long slopes of the above mountain ranges. Permanent snow patches are usually formed at the same places, and duration of their existence depends on sizes and a degree of shading. At the same time, even relatively small snow patches (100–200 thousand m3) can be preserved if they are located in narrow fissures (for example, the area of the Maly Fisht Glacier). In the last 3–5 years, the permanent snow patches melt completely, which is probably a result of small amount of solid precipitation during the cold season and the relatively high air temperatures in the warm time (standard deviation is 0.8–1.0 °C above the normal).Представлены новые данные о снежниках Лагонакского нагорья. Проанализировано их распределение в пределах нагорья с учётом особенностей рельефа и ветрового режима. Отмечено значительное сокращение числа снежников и их размеров за последние годы, что обусловлено общей климатической тенденцией потепления

Snow patches of the Lagonaky highlands (Western Caucasus)

The article presents results of investigation of snowfields on the Lagonaky plateau: conditions of their formation, distribution and dynamics. Snow patches are the most characteristic elements of the high-mountain landscapes of the Lagonaky plateau. In warm seasons, they are widely distributed on local flat-topped ridges of the Lagonaky: Abadzeshsh Murzikao, Kamennoe and others, as well as on the mountain masses Fisht, Pshehasu, Oshten, and Nagoychuk. Morphological and climatic conditions of the Lagonaky Highlands are unique and favorable for formation of snow patches and long preservation of them during the spring-summer periods. These conditions are high mountain ridges with flat tops, negative karst forms of the relief as well as a favorable wind regime with long winter snow storms and heavy snowfalls. Snow patches result from snow transport and accumulation after strong snow-drift on the leeward slopes. The avalanche snow patches arise when avalanches release from steep and long slopes of the above mountain ranges. Permanent snow patches are usually formed at the same places, and duration of their existence depends on sizes and a degree of shading. At the same time, even relatively small snow patches (100–200 thousand m3) can be preserved if they are located in narrow fissures (for example, the area of the Maly Fisht Glacier). In the last 3–5 years, the permanent snow patches melt completely, which is probably a result of small amount of solid precipitation during the cold season and the relatively high air temperatures in the warm time (standard deviation is 0.8–1.0 °C above the normal)

Freely suspended perforated polymer nanomembranes for protein separations

Abstract Selective removal of nanometer-sized compounds such as proteins from fluids is an often challenging task in many scientific and industrial areas. Addressing such tasks with highly efficient and selective membranes is desirable since commonly used chromatographic approaches are expensive and difficult to scale up. Nanomembranes, molecularly thin separation layers, have been predicted and shown to possess outstanding properties but in spite ultra-fast diffusion times and high-resolution separation, to date they generally lack either of two crucial characteristics: compatibility with biological fluids and low-cost production. Here we report the fast and easy fabrication of highly crosslinked polymer membranes based on a thermoset resin (poly[(o-cresyl glycidyl ether)-co-formaldehyde (PCGF) cured with branched polyethyleneimine (PEI)) with nanoscale perforations of 25 nm diameter. During spin casting, microphase separation of a polylactide-co-glycolide induces the formation of nanometer sized domains that serve as templates for perforations which penetrate the 80 nm thick membranes. Ultrathin perforated nanomembranes can be freely suspended on the cm scale, exhibit high mechanical strength, low surface energies and a sharp permeability cutoff at a hydrodynamic diameter of 10 nm suitable for protein separations