Snowball Earth prevention by dissolved organic carbon remineralization

The 'snowball Earth' hypothesis posits the occurrence of a sequence of glaciations in the Earth's history sufficiently deep that photosynthetic activity was essentially arrested. Because the time interval during which these events are believed to have occurred immediately preceded the Cambrian explosion of life, the issue as to whether such snowball states actually developed has important implications for our understanding of evolutionary biology. Here we couple an explicit model of the Neoproterozoic carbon cycle to a model of the physical climate system. We show that the drawdown of atmospheric oxygen into the ocean, as surface temperatures decline, operates so as to increase the rate of remineralization of a massive pool of dissolved organic carbon. This leads directly to an increase of atmospheric carbon dioxide, enhanced greenhouse warming of the surface of the Earth, and the prevention of a snowball state.     

青藏铁路保温板热棒复合结构路基保护冻土效果数值分析

根据带相变热传导有限元方法,对普通路基、含保温板路基、热棒路基和保温板热棒复合结构路基在未来50年青藏铁路沿线气温上升2.0℃情况下的温度场进行了预报分析和比较.计算结果表明,在年平均气温为-3.5℃或地表年平均温度为-1℃的地区,在青藏铁路50年的使用期内,普通路基、含保温板路基和热棒路基在气温升高条件下路基下伏、冻土都将发生融化,路基将会产生较大融沉变形,不能保证青藏铁路路基的稳定性.而保温板热棒复式结构充分利用了保温板和热棒两种措施的优点,可以更好的提高保护冻土的效率.     

Ionospheric structure in the region of East-Asian equatorial anomaly reconstructed by tomography

A chain of low latitudinal ionospheric tomography along 120°E meridian has been operating since 1993. This chain is composed of six stations from Shanghai to Manila receiving signals from the transit NNSS satellites. In this paper several reconstruction examples are presented, which give the 2-D imaging of electron density distribution obtained from the observed TEC data by means of computerized tomography technique. In reconstruction process a multi-station method was used to determine the unknown phase offset. To overcome the limitation of incomplete projection data, a technique of backprojection in combination with a normalized ionospheric model was introduced to obtain the initial guess of electron density distribution. The results demonstrate that ionospheric tomographic technology is very useful and effective to investigate the equatorial and low-latitudinal ionospheric structures and dynamics. Supported by the National Natural Science Foundation, of China & the Science Fourdation of State Education Committee of China Xu Jisheng: born in Nov. 1946, Professor     

Activation of old carbon by erosion of coastal and subsea permafrost in Arctic Siberia

The future trajectory of greenhouse gas concentrations depends on interactions between climate and the biogeosphere. Thawing of Arctic permafrost could release significant amounts of carbon into the atmosphere in this century. Ancient Ice Complex deposits outcropping along the ~7,000-kilometre-long coastline of the East Siberian Arctic Shelf (ESAS), and associated shallow subsea permafrost, are two large pools of permafrost carbon, yet their vulnerabilities towards thawing and decomposition are largely unknown. Recent Arctic warming is stronger than has been predicted by several degrees, and is particularly pronounced over the coastal ESAS region. There is thus a pressing need to improve our understanding of the links between permafrost carbon and climate in this relatively inaccessible region. Here we show that extensive release of carbon from these Ice Complex deposits dominates (57?±?2 per cent) the sedimentary carbon budget of the ESAS, the world’s largest continental shelf, overwhelming the marine and topsoil terrestrial components. Inverse modelling of the dual-carbon isotope composition of organic carbon accumulating in ESAS surface sediments, using Monte Carlo simulations to account for uncertainties, suggests that 44?±?10 teragrams of old carbon is activated annually from Ice Complex permafrost, an order of magnitude more than has been suggested by previous studies. We estimate that about two-thirds (66?±?16 per cent) of this old carbon escapes to the atmosphere as carbon dioxide, with the remainder being re-buried in shelf sediments. Thermal collapse and erosion of these carbon-rich Pleistocene coastline and seafloor deposits may accelerate with Arctic amplification of climate warming.     

Mediation of the solar wind termination shock by non-thermal ions

Broad regions on both sides of the solar wind termination shock are populated by high intensities of non-thermal ions and electrons. The pre-shock particles in the solar wind have been measured by the spacecraft Voyager 1 (refs 1-5) and Voyager 2 (refs 3, 6). The post-shock particles in the heliosheath have also been measured by Voyager 1 (refs 3-5). It was not clear, however, what effect these particles might have on the physics of the shock transition until Voyager 2 crossed the shock on 31 August-1 September 2007 (refs 7-9). Unlike Voyager 1, Voyager 2 is making plasma measurements. Data from the plasma and magnetic field instruments on Voyager 2 indicate that non-thermal ion distributions probably have key roles in mediating dynamical processes at the termination shock and in the heliosheath. Here we report that intensities of low-energy ions measured by Voyager 2 produce non-thermal partial ion pressures in the heliosheath that are comparable to (or exceed) both the thermal plasma pressures and the scalar magnetic field pressures. We conclude that these ions are the >0.028 MeV portion of the non-thermal ion distribution that determines the termination shock structure and the acceleration of which extracts a large fraction of bulk-flow kinetic energy from the incident solar wind.     

各向异性损伤对土压力强度的影响分析

应用耦合损伤滑移线法，求解平面应变条件下的极限荷载问题，出考虑各向异性损伤的平面应变问题应力场的滑移线解，求出刚性挡土壤的主动土压力和被动土压力强度，并分析各向异性损伤对土压力的影响，计算得知，各向异性损伤对主动土压力系数Naq和被动土压力系数Npq值有影响，在水平方向损伤变量D1一定时，Naq值随着垂直方向损伤变量D2的增加而增加，Npq值却随着D2的增加而降低；D2一定时，Naq值随D1的增加而减小，而Npq值随D1的增加而增加。     

蔺草染土固色技术及工艺研究

蔺草即蓆草，由它编织而成的榻榻米蓆是日本国的传统生活用品．本文研究了一种适合我国引种的日本蔺草染土固色配方，使用A、B、C三种添加剂，建立一套合理的操作工艺，使出口产品的质量达到一等或二等产品的要求，该技术所需经费不多，经济效益却十分显著．     

烟雾箱内甲烷气体的腔增强吸收光谱

用DFB半导体激光器作光源的腔增强吸收光谱(CEAS)技术测量了烟雾箱中甲烷气体在近红外波段的光谱吸收,获得了烟雾箱内甲烷气体在1 315 nm附近的吸收光谱;将测得的光谱数据与Hitran 2004数据库给出的光谱参数做了比较,发现了几条尚未被Hitran 2004数据库收入的甲烷分子的新谱线;同时对CEAS技术定量测量烟雾箱内甲烷气体的能力和稳定性做了研究.结果表明,CEAS技术完全可以用来测量烟雾箱内甲烷气体的吸收光谱,可以作为烟雾箱检测方法的一种补充.     

小行星碰撞地球对地球自转的影响

以小行星有可能碰撞地球为依据,分别在地球作近似定轴转动和定点转动的两种情况下,讨论了在碰撞的时候地球自转运动可能发生的变化.文章建立了与此相应的Euler方程,得到了该方程的解析解.由这些公式文章说明了SL9彗星的撞击,对木星的自转速率是没有影响的.基于Chicxulub陨石坑的一个模拟碰撞的数值计算中,文章获得结论:小行星对地球的大型碰撞有可能影响地球的自转运动.     

Separation of Worm Earth Enzyme by High Performance Capillary Electrophoresis

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Stimulation by ammonium-based fertilizers of methane oxidation in soil around rice roots

Methane is involved in a number of chemical and physical processes in the Earth's atmosphere, including global warming. Atmospheric methane originates mainly from biogenic sources, such as rice paddies and natural wetlands; the former account for at least 30% of the global annual emission of methane to the atmosphere. As an increase of rice production by 60% is the most appropriate way to sustain the estimated increase of the human population during the next three decades, intensified global fertilizer application will be necessary: but it is known that an increase of the commonly used ammonium-based fertilizers can enhance methane emission from rice agriculture. Approximately 10-30% of the methane produced by methanogens in rice paddies is consumed by methane-oxidizing bacteria associated with the roots of rice; these bacteria are generally thought to be inhibited by ammonium-based fertilizers, as was demonstrated for soils and sediments. In contrast, we show here that the activity and growth of such bacteria in the root zone of rice plants are stimulated after fertilization. Using a combination of radioactive fingerprinting and molecular biology techniques, we identify the bacteria responsible for this effect. We expect that our results will make necessary a re-evaluation of the link between fertilizer use and methane emissions, with effects on global warming studies.     

Influence of sintering temperature on the thermoelectric properties of Ba8Ga16Si30 clathrate treated by spark plasma sintering

A series of Ba8Ga16Si30 clathrate samples were prepared by arc melting, ball milling, acid washing, and spark plasma sintering (SPS). X-ray diffraction analysis revealed that the lattice of the Ba8Ga16Si30 samples expanded as the SPS temperature was increased from 400 to 750°C. Lattice contraction recurred when the SPS temperature was further increased in the range of 750–1000°C. This phenomenon can be explained by the variation of Ga content in the lattice. The thermoelectric figure of the merit ZT value of clathrates increased with the increase in SPS temperature and reached a maximum when the sample was subjected to SPS at 800°C. A further increase in SPS temperature did not contribute to the improvement of ZT. The variation of the lattice parameter a vs. SPS temperature T was similar to the variation ob-served in the ZT–T curve.     

钯-铜-稀土催化一氧化碳和苯乙烯交替共聚反应

利用乙酸钯、乙酸钕和对甲苯磺酸铜组成的催化体系催化一氧化碳和苯乙烯共聚，合成聚1-氧代-2-苯基丙撑（STCO）．用红外光谱、元素分析和X射线光电子能谱对共聚物进行表征、结果表明，产物为一氧化碳和苯乙烯的交替共聚物．同时研究了催化体系的配比、2，2’-联吡啶和对甲苯磺酸铜的用量以及不同的稀土盐和单体对体系催化活性的影响．此外，对催化剂的复配进行了对比实验．实验结果表明，以钯为主催化剂，并加入适量稀土盐与对甲苯磺酸铜，同时优化催化体系各组分的配比，可以有效地提高催化活性，降低STCO的成本．     

Annihilation of ecosystems by large asteroid impacts on the early Earth

Large asteroid impacts produced globally lethal conditions by evaporating large volumes of ocean water on the early Earth. The Earth may have been continuously habitable by ecosystems that did not depend on photosynthesis as early as 4.44 Gyr BP (before present). Only a brief interval after 3.8 Gyr exists between the time when obligate photosynthetic organisms could continuously evolve and the time when the palaeontological record indicates highly evolved photosynthetic ecosystems.     

三氯偶氮胂直接光度法测定金属材料中铈组稀土元素

研究了三氯偶氮胂在盐酸－草酸介质中与钢铁及合金材料中铈组稀土元素的显色反应。试验表明，在盐酸（２Ｍ）－草酸（０．０８Ｍ）介质中，铈组稀土元素与三氯偶氮胂形成稳定的络合物。其最大吸收波长λｍａｘ＝６３０ｎｍ，表现摩尔吸光系数ε＝１．１×１０４Ｌ／ｍｏｌ·ｃｍ，铈组稀土元素与三氯偶氮胂的络合比为１：２。用本法测定了球墨铸铁、合金钢、铝合金、镁合金和钴合金等金属材料中的铈组稀土元素，其结果令人满意。     

以地球自转为成因的涡流的特征数量级

以大型人造水体中的涡流为对象，以涡动力学理论为根据，在分析试验资料的基础上，给出了大型人造水体中不同尺度涡流的特征数量级的估算值，并分析了它们的变化趋势。     

薄层层析法分离重稀土元素

本文研究的薄层层析法分离重稀土元素的固定相为硅胶H/硝酸铵/CMC/H_2O(W/W33∶4∶1∶110),展开剂为:1.二-2-乙基己基磷酸-异丙醚-乙醚-硝酸,2.单-2-乙基己基磷酸-异丙醚-乙醚-硝酸。本文测定了各重稀土元素的R_f值,研究了改变展开剂中各组分比例对各稀土元素色谱行为及分离效果的影响。当二-2-乙基己基磷酸-异丙醚-乙醚-硝酸体积比为1∶10∶6:∶.1,单-2-乙基己基磷酸-异丙醚-乙醚-硝酸体积比为1∶8∶8∶1.1时,各相邻重稀土元素间均能表现出较明显的R_f值差异。分离上述稀土标准混合液,各元素的分离情况可达到定量测定要求,结果令人满意。     

新风用地能降温除湿试验

分析了夏热冬冷地区居住建筑室外的气象条件和室内的通风要求,在夏季用地能对新风进行了降温除湿试验,试验结果表明,新风经地能降温除湿后其温湿度基本满足该地区居住建筑室内通风的要求,且系统运行稳定,效果良好。     

燃烧法制备磷灰石型碱土掺杂硅酸镧电解质（英文）

采用尿素-硝酸盐燃烧法,在较低温度下制备较高纯度无杂质相的碱土掺杂磷灰石型La_(9.33)M_x(SiO_4)_6O_(2+δ)电解质.通过XRD、SEM、交流阻抗测试,对样品的结构、形貌及电导性能进行研究.结果表明,燃烧合成的无定形电解质粉体,在800℃煅烧12h后,具有P63/m磷灰石型晶体结构;掺杂对LSO烧结体微观产生一定的影响,烧结体的结构和形貌随x值的变化而变化.此外,LSO烧结体具有良好的电阻可逆性和稳定性.适量的掺杂可有效提高LSO的离子电导率,过量的掺杂反而会降低离子电导率,最佳掺杂摩尔分数为0.2.而随着碱土金属阳离子半径增大,掺杂效果也越来越好.