青藏高原地气温差与印度洋海气温差的相互影响

青藏高原和印度洋均对我国气候有重要影响,研究高原和印度洋的热力状况及其耦合关系对全面了解我国的天气现象具有重要意义.利用1981-2010年（30 a）欧洲中心ERA-interim的青藏高原和印度洋温度资料,以及NCEP/NCAR的垂直速度和风速资料,分析了青藏高原地气温差和印度洋海气温差的特征及其相互影响.结果表明,高原冬、夏季地气温差有所区别：冬季地气温差呈东北-西南向的带状分布,在高原中部、西南边界喜马拉雅山脉地区和东南边界出现了较大的负值中心,其他地区均为正值;夏季地气温差均为正值,远大于冬季.在印度洋,海气温差冬、夏均为正值,EOF1空间分布均出现正负交替的现象,但冬季为东西向带状分布,夏季为西北-东南向分布.高原和印度洋相互影响且互相制约：在冬季,印度洋对高原地气温差有正反馈,高原对印度洋则有负反馈,夏季相反.本结果可为进一步研究青藏高原和印度洋对亚洲气候的共同作用提供参考.     

晋西黄土洞穴成因研究

在野外调查、室内实验基础上,对晋西黄土洞穴的成因进行了分析,研究表明:晋西黄土洞穴的形成是多种内外因素综合作用的结果,主要因素包括黄土的土性、微观结构、节理裂隙、地层结构厚度、水文气候、地形地貌等,其中黄土土性和微观结构是黄土洞穴形成的内因,节理裂隙和地层分布状况为洞穴发育提供了空间和物质基础,水成为黄土洞穴形成的源动力,地形地貌则控制着黄土洞穴的分布。     

37Ar测量系统的研制与能谱测量方法研究

建立了移动式³⁷Ar测量系统.采用1 L的正比计数探测器和能谱分析方法对³⁷Ar的测量进行了研究.分析了计数管的坪长、坪斜和本底等特点.结果表明,相比传统的计数方法,采用电子能谱法测量³⁷Ar具有直观、坪长长、坪斜小等优点.相比传统的总计数方法,采用峰本底的方法可以将本底降低约一个量级,从而降低³⁷Ar的探测下限.并研究了工作气体中不同甲烷含量对³⁷Ar的测量能谱和计数管工作电压的影响,结果表明,     

Moduli of model elastomeric networks prepared from polymer chains having a high plateau modulus,and their interpretation in terms of the constrained-chain model

High-molecular weight polybutadiene chains having approximately 47% cis-1,4 units and 45% trans-1,4 units were crosslinked through their carbon-carbon double bonds using p-bis(dimethylsilyl) benzene as crosslinking agent and chloroplatinic acid as catalyst. This particular polymer was chosen because the high plateau modulus it exhibits in the un-crosslinked state is taken to indicate large numbers of chain entanglements, and stress–strain measurements on such networks have frequently been interpreted with the assumption that the trapping of such entanglements during crosslinking should contribute significantly to their modull. It is shown in the present investigation that such results are equally well interpreted in terms of the new constrained-chain theory of rubbery elasticity. © 1993 John Wiley & Sons, Inc.     

Pure and mixed monolayers of poly-L-methionine and poly-γy-methyl-L-glutamate with 1,2 dioleyl-L-α-phosphatidylcholine at air-water interface

Monolayers of poly-L-methionine (PM) and poly--methyl-L-glutamate (PMG), spread at an air-water interface, exhibit a high compressibility plateau region at 10 dyn/cm and 18 dyn/cm in their respective-A curves. This behaviour is related to a-helical conformation of the polypeptide molecules in the said interface.Comparative studies of the areas per residue observed in the spreading isotherms, with the areas calculated from molecular models, indicate that the polypeptide molecules should be associated in parallel, forming islets of at least 5-helix chains.Mixed monolayers corresponding to the poly-L-methionine (PM)-1,2 dioleyl-L--phosphatidylcholine (DOPC) and poly--methyl-L-glutamate (PMG)-1,2 dioleyl-L--phosphatidylcholine (DOPC) systems, follow, in every case, the additivity rule for monolayer composition, any indicating that its components are insoluble in the surface mixture. In the case of mixed monolayers of PM-DOPC, a certain degree of compatibility is possible among its components, as a modulation of the plateau region is observed in the spreading isotherms, while for the PMG-DOPC system the plateau region appears at the same surface pressure value as the isotherm corresponding to pure PMG polypeptide.Instituto de Química-Física Rocasolano, C.S.I.C. Madrid -6, España     

Origin of the irreversible plateau (4.5 V) of Li[Li0.182Ni0.182Co0.091Mn0.545]O2 layered material

Layered LiNi_0.4Co_0.2Mn_0.4O₂, Li[Li_0.182Ni_0.182Co_0.091Mn_0.545]O₂, Li[Li_1/3Mn_2/3]O₂ powder materials were prepared by rheological phase method. XRD characterization shows that these samples all have analogous structure to LiCoO₂. Li[Li_0.182Ni_0.182Co_0.091Mn_0.545]O₂ can be considered to be the solid solution of LiNi_0.4Co_0.2Mn_0.4O₂ and Li[Li_1/3Mn_2/3]O₂. Detailed information from XRD, ex situ XPS measurement and electrochemical analysis of these three materials reveals the origin of the irreversible plateau (4.5 V) of Li[Li_0.182Ni_0.182Co_0.091Mn_0.545]O₂ electrode. The irreversible oxidation reaction occurred in the first charging above 4.5 V is ascribed to the contribution of Li[Li_1/3Mn_2/3]O₂ component, which maybe extract Li⁺ from the transition layer in Li[Li_1/3Mn_2/3]O₂ or Li[Li_0.182Ni_0.182Co_0.091Mn_0.545]O₂ through oxygen release. This step also activates Mn⁴⁺ of Li[Li_1/3Mn_2/3]O₂ or Li[Li_0.182Ni_0.182Co_0.091Mn_0.545]O₂, it can be reversibly reduced/oxidized between Mn⁴⁺ and Mn³⁺ in the subsequent cycles.     

青海高原道地药材羌活和铁棒锤微量元素含量比较研究

为研究青海高原道地药材羌活和铁棒锤的特性,采用电热板消解法处理样品,原子吸收分光光度法测定了两种药材中Ca、Mg、Cu、Zn、Fe、Mn 6种金属元素的含量。结果表明,Ca、Mg、Cu、Zn、Fe、Mn 6种微量元素含量在两种道地药材中,含量最高的是Ca,平均值分别为(55.78±12.10)mg/g和(26.48±5.79)mg/g;含量最低的元素为Cu,其值分别为(0.28±0.28)mg/g和(0.09±0.06)mg/g;其它元素含量从高到低依次为Mg,Fe,Zn,Mn。可见不同地区的羌活其微量元素的含量有明显的差异,且羌活微量元素含量也存在种间差异,细叶羌活的Ca、Mg元素含量比宽叶羌活的要低,相反,Fe,Cu,Zn 3种元素含量细叶羌活的比宽叶的要高。     

Crystal Growth,Structure, and Magnetic Properties of a Two‐dimensional Triangular Lattice Magnet,Cu2(OH)3HCO2

We prepared single crystals of basic copper formate Cu₂(OH)₃HCO₂ ( 1) by hydrolysis of formate anions in an aqueous solution of copper formate. X‐ray structure analysis showed that this material has a two‐dimensional triangular lattice network with S=1/2. The temperature dependence of magnetic susceptibility revealed antiferromagnetic ordering at 5.4 K. A spin‐flop transition was observed at about 20 kOe at 2 K, thereby indicating metamagnetic‐like behavior. The saturation magnetization was almost one‐half of the theoretical value at 2 K under 70 kOe. The magnetic behaviors of 1 were also discussed with regard to its crystal structure. The preparation method presented herein is convenient and available for single crystal growth of metal hydroxide derivatives with various anions.     

Low-temperature metastable states in a stacked triangular Ising antiferromagnet

We study low-temperature magnetization processes in a stacked triangular Ising antiferromagnet by Monte Carlo simulations. In increasing and decreasing magnetic fields we observe multiple steps and hysteresis corresponding to formation of different metastable states. Besides the equidistant threefold splitting of the 1/3 ferrimagnetic plateau, we additionally confirm a fourth plateau in the field-increasing branch and a sizable remanence when the field is decreased to zero. The newly observed plateau only appears at sufficiently low temperature and sufficiently large exchange interaction in the stacking direction. These observations reasonably reproduce low-temperatures measurements on the spin-chain compound Ca₃Co₂O₆.