Isotopic evolution of the terminal Neoproterozoic and early Cambrian carbon cycle on the northern Yangtze Platform, South China

Profound geotectonic, climatic and biological changes occur during the terminal Neoproterozoic and its transition into the early Cambrian. These are reflected in temporal variations of the chemical and isotopic composition of seawater. We are studying a sequence of sedimentary rocks at the Shatan section, northern Yangtze Platform, Sichuan Province of China. This succession comprises, in ascending stratigraphic order, predominantly calcareous sediments of the Sinian upper Dengying Formation and black shales of the lower Cambrian Guojiaba Formation (time equivalent of Niutitang Fm.). Paleoenvironmental setting represents shallow-water shelf deposits. The objective of our study is to provide temporal records for the isotopic compositions of organic and carbonate carbon throughout this time interval. Organic carbon isotope values display a range between -35.8‰ and -30.1‰ with clear stratigraphic variations. Carbonate carbon isotope data vary between -3.5‰ and +0.5‰. These secular variations are interpreted to reflect perturbations of the global carbon cycle, specifically changes in the fractional burial of organic carbon. However, local conditions have further affected the isotopic signals.     

Structural Changes of Polyethylene Terephthalate Fibers Grafted by Acrylamide

A group of grafted PET fibers with different graft yield are formed by grafting acrylamide onto the PET main chains. The structure of grafted fibers are studied by scanning electronic microscope ( SEM ), infra-red spectrophotometer ( IR ), and differential scanning calorimetry(DSC). At the same time, the moisture regain, dyeability, strength, and elongation at break of the samples are measured and their relations with structural changes are discussed. Compared with ungrafted fiber, shape of the fiber cross-section, IR characteristic absorption peaks, and melting behavior of the grafted fibers have been changed, causing the fiber dyeability and moisture regain to be increased, and mechanical properties to be changed.     

粉状活性炭再生工艺研究

采用回转炉加热再生法 ,对粉状炭进行了再生实验 ,确定了再生工艺条件 :再生温度 85 0°C ,再生时间6 0min ,水蒸汽用量占原料量 30 % ,使废炭吸附能力恢复 10 0 % ,得率 70 %以上。     

不同碳源对红边朱蕉组培苗生长的影响

从碳源角度进行了降低红边朱蕉组培苗生产成本的试验；比较分析了蔗糖、葡萄糖、果糖、食用白糖和红糖等5种碳源对红边朱蕉试管苗增殖速度、根诱导效率、内含物积累的影响，分别以蔗糖、葡萄糖、果糖、白糖、红糖为碳源培养4周，培养物均能很好地生长、生根，同时有利于可溶性糖和蛋白质的积累。结果表明，在组培快繁中。为降低成本，可以食用白糖、红糖等为碳源，替代分析纯蔗糖。     

碳纳米管的催化热裂解法制备与表征

以纳米级NiO／SiO2气凝胶为催化剂，以H2为栽气和还原气，在适当的温度下，裂解甲烷等碳氢气体，得到了管径均匀、长度与直径比为100—1000的碳纳米管。同时用透射电子显微镜(TEM)对催化剂和碳纳米管进行了表征。     

碳钢在液/固双相管流中的磨损腐蚀机理研究

文中利用自行研制的管流动态模拟试验装置 ,研究了碳钢在液/固双相流中的磨损腐蚀。结果表明碳钢在流动 5%河砂的双相 3.5 %NaCl溶液中 ,磨损腐蚀速度随流速的增加而显著地增大 ,没有出现像单相流中磨损腐蚀速度显著降低的流速区段 ,其磨损腐蚀过程仍主要受阴极氧扩散控制。在液/固双相流中 ,碳钢阻抗谱为双容抗半圆弧 ,且都出现低频收缩现象。对碳钢施加阴极电流 ,由于抑制了电化学因素 ,大幅度削弱了与流体力学因素的协同效应 ,使碳钢腐蚀大大减轻。证明了在双相管流中 ,碳钢磨损腐蚀过程仍主要受电化学因素控制。     

基于PLC的变压吸附制高纯氧系统

研究了采用沸石分子筛和碳分子筛吸附床的变压吸附制高纯氧工艺以及采用基于PLC控制系统对流量、压力和电磁阀进行的调节和控制，确立了两级变压吸附制高纯氧的工艺流程和各吸附床的最佳吸附周期，分析了排气量对氧气纯度的影响．实验结果表明氧气的最高纯度可达到99．5％．     

改性腈纶纤维混凝土梁的弯曲疲劳特性

为了获得具有经济性和良好技术性能的混凝土结构,有必要研究改性腈纶纤维(以下简称腈纶纤维)对混凝土弯曲疲劳强度及疲劳极限的增强作用。用四点加载方法研究了腈纶纤维混凝土梁和底层撒布较长钢纤维的腈纶纤维混凝土梁的弯曲疲劳性能。研究结果表明:当腈纶纤维体积分数为0.085%时,腈纶纤维混凝土梁和底层撒布较长钢纤维的腈纶纤维混凝土梁的弯曲疲劳强度比素混凝土分别提高11.7%和15.7%;当应力水平为0.90时,腈纶纤维混凝土梁和底层撒布较长钢纤维的腈纶纤维混凝土梁弯曲寿命分别是素混凝土的22倍和29.01倍。底层撒布较长钢纤维的腈纶纤维混凝土梁的弯曲疲劳性能优于底层只撒布一层钢纤维或只采用腈纶纤维来增强的混凝土梁。复合纤维增强混凝土适用于道路及机场跑道。     

烟碱和一氧化碳对大鼠学习记忆及脑发育的影响

通过观察烟碱和一氧化碳(CO)对大鼠学习记忆和脑发育的影响,利用Y型迷宫测试学习记忆,利用电镜技术观测脑超微结构。得出烟碱可使学习记忆能力下降(P<0.05),使大脑皮层厚度(P<0.05)及突触数密度(P相似文献   

微波辐射处理活性炭—吡啶溶液的实验

以活性炭、吡啶溶液为研究对象。考察了微波辐射时间、微波功率、活性炭用量、吡啶溶液初始溶液浓度、pH值等因素对微波处理活性炭、吡啶溶液的影响。实验结果表明：微波辐射处理后的活性炭对吡啶的吸附具有明显的高效率，3．5min去除率即可达60％以上；而不用微波辐射处理的活性炭对吡啶的吸附，50min后，去除率才达70％。微波辐射使活性炭孔隙结构发生了明显的变化．增强了其对吡啶的吸附能力．