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Abstract Lunar meteorites are fragments of the Moon that escaped the gravity of the Moon following high-energy impacts by asteroids,subsequently fell to Earth.An inventory of 165 lunar meteorites has been developed since the discovery and identification of the first lunar meteorite,ALHA 81005,in 1979.Although the Apollo samples are much heavier in mass than lunar meteorites,the meteorites are still an important sample supplement for scientific research on the composition and history of the Moon.Apart from a small amount of unbrecciated crystalline rocks,the majority of lunar meteorites are breccias that can be classified into three groups:highland feldspathic breccia,mare basaltic breccia,and mingled (including fledspathic and basaltic clasts) breccia.The petrography of lunar rocks suggests that there are a series of rock types of anorthosite,basalt,gabbro, troctolite,norite and KREEP in the Moon.Although KREEP is rare in lunar rocks,KREEP components have been found in the increasing number of lunar meteorites.KREEP provides important information on lunar magmatic evolution,e.g.,the VHK KREEP clasts in SaU 169 may represent the pristine lunar magma (urKREEP).Six launching pairs of lunar meteorites have been proposed now,along with ten possible lunar launching sites.In addition,symplectite is often found in lunar basalts,which is a significant record of shock metamorphism on the lunar surface.Furthermore,isotopic ages and noble gases not only provide information on crystallization processes in lunar rocks and the formation of lunar crust,but also provide insight into shock events on the lunar surface.
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Abstract The Sôya Coast in East Antarctica has several ice-free areas where many small (<1 km2) and shallow (<50 m depth) glacial lakes display various limnological features.Geological,biological,and ecological studies conducted by the Japanese Antarctic Research Expeditions since 1957 are reviewed herein.Most of the lakes along the coast are oligotrophic;however,water quality is highly variable depending on differences in lake morphology and history.Geophysical and paleolimnological studies suggest that most of the lakes appeared after the Last Glacial Maximum (LGM) and have since maintained a lacustrine condition.The ubiquitous occurrence of benthic microbial assemblages with low phytoplankton biomasses is a common feature of other Antarctic lakes.However,diverse benthic assemblages such as moss pillars and large pinnacle microbial structures are found in the lake basins.Frequent and continuous limnological studies have revealed three typical water circulation patterns,underwater light climate features (too much light,which includes UV radiation during the ice free season),and the structure of benthic assemblages based on their photosynthetic physiology.The phenomenon of mass floatation of benthic assemblages was observed in a lake during the ice-covered season;this was explained by seasonal environmental conditions.Thus,a hypothesis was formulated based on ecological matter cycling,eutrophication,and lake succession processes.
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A gram-positive,rod-shaped,aerobic,thermo-acidophilic bacterium CC2(optimal temperature 55℃ and pH 4.0),belonging to the genus
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Molecular genetic techniques have proven very useful for initial analysis of the extent of genetic variation and dispersal in several Antarctic moss species.In the present study,the small subunit ribosomal RNA (SSU rDNA) and internal transcribed spacers of the nuclear ribosomal DNA (ITS rDNA) were sequenced in nine individuals of different mosses from the Fildes Peninsula of Antarctica.Sequence alignment showed that the extreme environment tended to increase the genetic diversity of Antarctic mosses.In addition,in our phylogenetic analysis,one previously unidentified Antarctic moss species was characterized by comparison with SSU and ITS rDNA sequences of known moss species.Moreover,the optimal culture medium and conditions for surface explant sterilization and protonemata induction in tissue culture of Pohlia nutans were investigated.The successful establishment of a tissue culture protocol together with the phylogenetic analysis of Antarctic mosses will provide technological support to establish an effective resource regeneration method for discovering new functional genes and gaining novel insights into the mechanisms of stress acclimation.
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Pollen morphology of eight species of Saxifraga,
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Atmospheric and oceanic drag are the main environmental forces controlling sea ice drift. Oceanic drag includes the form drag generated by water pressure gradients on the side of ice floes or on ice ridges, and the skin friction generated by viscous flow on the bottom of ice floes. In this study, we carried out a two-dimensional numerical simulation using FLUENT software to investigate the characteristics of dynamic flow under ice with a smooth undersurface. We studied water drag and flow field distribution below the ice under different conditions of ice draft and flow velocity, and the results agreed well with data from laboratory-based physical modeling tests, demonstrating the ability of the numerical model to reproduce the dynamic interactions between sea ice and the flow field. The degree of distortion in the flow field caused by ice increased as the ice draft increased. Vortexes occurred in the wake field of the floe, and the centers of the vortexes moved away from the ice with increasing ice draft. The simulated drag of water on ice showed a clear linear relationship with the square of the flow velocity.
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The first Southern Ocean Observing System (SOOS) Asian Workshop was successfully held in Shanghai, China in May 2013, attracting over 40 participants from six Asian nations and widening exposure to the objectives and plans of SOOS. The workshop was organized to clarify Asian research activities currently taking place in the Southern Ocean and to discuss, amongst other items, the potential for collaborative efforts with and between Asian countries in SOOS-related activities. The workshop was an important mechanism to initiate discussion, understanding and collaborative avenues in the Asian domain of SOOS beyond current established efforts. Here we present some of the major outcomes of the workshop covering the principle themes of SOOS and attempt to provide a way forward to achieve a more integrated research community, enhance data collection and quality, and guide scientific strategy in the Southern Ocean.
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