Hydro-mechanical coupling experiments on suffusion in sandy gravel foundations containing a partially penetrating cut-off wall

The influence of the stress state on the evolution of suffusion failure is often neglected in the design of sandy gravel foundations containing a partially penetrating cut-off wall. A series of hydro-mechanical coupling experiments on such structures was carried out to investigate the influence using a newly designed apparatus. The results indicate that: (1) The stress state has a significant influence on the evolution of suffusion, which increases the critical suffusion hydraulic gradient dramatically. (2) The critical suffusion hydraulic gradient is linearly related to the confining pressure and to the penetration ratio, and a simple interpolation function for the critical hydraulic gradient was fitted based on the experimental results. (3) The eroded mass in the development of suffusion is nonuniform and intermittent. The evolution of suffusion is a complicated and iterative process involving fine particle migration, pores being clogged, flushing out of the clogged pores, and fine particle remigration. (4) Flow along the interface of sandy gravel and cut-off wall conforms to the piecewise-linear Darcy flow rule. The results will enhance the understanding of the influence of the stress state on the suffusion failure in sandy gravel foundations containing partially penetrating cut-off walls.     

Scientists Discuss the Genetic Relationship between Qinghai–Tibet Plateau and Indian Monsoon

The Qinghai-Tibet Plateau,the third pole towering high in the world,has always been the object of extreme climate research.This is the most extensive high altitude area in the world,with an average altitude of 4000 meters.Such a wide mountainous area absorbs more solar energy than one at sea level,so the winter here is cold and summer is broiling hot.In the 1950s,the Chinese atmospheric scientist Ye Duzheng and German meteorologist Hermann Flohn both suggested that the air layer of the summer plateau was warmer than the sea and the air layer with the same altitude over land located at sea level,so that the temperature difference generated winds,which blow moist air from the ocean into the interior of the subcontinent of India,becoming a driving engine of the rainy season,the Monsoon.     

Iron-Molybdenum Isotopes and the Chemical Evolution of Ancient-Oceans

Iron(Fe) is abundant in nature while molybdenum(Mo) is the most abundant transition metal in seawater. Due to their high sensitivity to the redox state of the environment, the isotopic compositions of Fe and Mo as well as variations have been widely used to probe the redox conditions and the evolution of ancient ocean chemistry in favor of improved analytical techniques. Here, we summarized isotopic fractionation mechanisms and natural distribution of both iron and molybdenum isotopes, and further we summarized and partially reinterpreted the redox evolution of ancient oceans through time based on available Fe-Mo data compiled in this study. The process that causes the largest iron isotope fractionation is redox reaction and the iron in oxidation state is generally enriched in ⁵⁶Fe. Biotic and abiotic pyrite formations also produce a large Fe isotope fractionations. Isotopic fractionation of molybdenum in seawater is mainly caused by the adsorption process of dissolved Mo onto ferromanganese oxides or hydroxides in sediments. Fe-Mn (hydro)oxides tend to adsorb isotopically light molybdenum resulting in the isotopic composition of Mo in seawater heavier. However, the Mo sinks in euxinic settings cause almost no molybdenum isotope fractionation. The Fe Mo isotope isotopic records through geological timegenerally suggest similar ocean redox evolution: Oceans older than 2.3 Ga was mainly dominated by ferruginous condition, and there was a slight increase in oxygen content between 2.6 and 2.5 Ga. Earth’s surface was initially oxidized during 2.3 to 1.8 Ga, during which euxinic deposition of sulfide was elevated. Euxinic waters may have expanded greatly between 1.8 and 0.8 Ga, and after that, Earth’s surface had being gradually oxidized and the euxinic waters shrank substantially.Finally, suggestions are proposed for further work on the Fe-Mo isotope research in the context of ancient ocean chemistry.     

Chinese Geological Prospecting Gets Good Harvest, and Mineral Resources and Reserves Increase Gratifying in 2012

On March 27,2013,the Ministry of Land and Resources held a news conference to announce a significant achievement in Chinese geological prospecting work in 2012. According to government/industry statistics,proved reserves of oil and natural gas have increase substantially in 2012.Newly proven national petroleum geological reserves are 15.2 million tons,a year-on-year growth of 13％,which is the tenth time of more than 1 billion tons since the founding of People's Republic of China;newly proven technically recoverable reserves are 270 million tons,a year-on-year growth of 7％.The 2012 national newly proved reserves from natural gas exploration are 961.22 billion cubic meters,a year-on-year growth of 33％,which is the highest level in our history;the new proven technically recoverable reserves are 500.8 billion cubic meters,a year-on-year growth of 36％.National natural gas production was 106.76 billion cubic meters,a year-on-year growth of 5.4％.The Ordos,Tarim and Sichuan basins are still the main producing areas of natural gas in China.In 2012,national oil production was 205 million tons,a year-on-year growth of 1％,which made a steady increase.The national coal-bed methane production was 2.57billion cubic meters,a vear-on-vear growth of 24％.     

A note on the dynamics around the Lagrange collinear points of the Earth–Moon system in a complete Solar System model

In this paper we study the dynamics of a massless particle around the L _1,2 libration points of the Earth–Moon system in a full Solar System gravitational model. The study is based on the analysis of the quasi-periodic solutions around the two collinear equilibrium points. For the analysis and computation of the quasi-periodic orbits, a new iterative algorithm is introduced which is a combination of a multiple shooting method with a refined Fourier analysis of the orbits computed with the multiple shooting. Using as initial seeds for the algorithm the libration point orbits of Circular Restricted Three Body Problem, determined by Lindstedt-Poincaré methods, the procedure is able to refine them in the Solar System force-field model for large time-spans, that cover most of the relevant Sun–Earth–Moon periods.     

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运输方式对马氏珠母贝(Pinctada fucata)稚贝存活率、生长、消化及抗氧化性能的影响探究

为优化马氏珠母贝苗种运输技术,提高运输效率,以马氏珠母贝(Pinctada fucata)稚贝为研究对象,分别以有水和无水两种运输方式汽运8 h条件下开展实验,比较分析其在运输前后、运输后恢复阶段的生长、消化和抗氧化性能。结果显示:有水运输后存活率达98%,无水运输97%;在恢复期第14 d,有水运输和无水运输存活率分别达97%、96%;有水运输皮质醇含量由(2 607.61±15.27)μg/L显著降低至(1 412.98±5.09)μg/L,无水运输后显著降低至(2 287.36±10.18)μg/L;在恢复期第7 d和14 d皮质醇含量均呈逐渐上升趋势;有水和无水运输后和恢复期淀粉酶活性不断上升,且有水运输酶活性高于无水运输(P<0.05),最高值为(1.43±0.05) U/mg prot;有水和无水运输后及恢复期超氧化物歧化酶酶活性在不断下降,最低下降至(16.00±0.14) U/mg prot,有水运输超氧化物歧化酶活性均高于无水运输(P<0.05);有水运输碱性磷酸酶、谷草转氨酶和谷丙转氨酶活性均上升,无水运输均下降;在恢复阶段,碱性磷酸酶活性在不断下降,谷草转氨酶和谷丙转氨酶活性在不断上升。有水和无水运输会对马氏珠母贝稚贝产生不同的影响,有水运输方式相对无水运输方式可使马氏珠母贝稚贝在后期阶段具有更好的存活效果和生长状态。