微结构疏水表面对界面流动的影响

<正>通过MicroPIV/PTV系统测量带有微结构的PDMS微流道(22μm×6μm,长8mm)内的速度分布。流道侧壁的PDMS微结构是通过软光刻微加工工艺制成,其特征宽度在1～10μm范围。为了研究微结构尺寸的影响,我们测量了3种不同尺度微结构对速度分布的影响。示踪粒子为200nm聚苯乙烯荧光粒子。实验管道Re约0.01。

西安附近丰水年秋季苹果林地土壤水分恢复研究

IEECAS SKLLQG

昆仑山北坡鸭子泉河阶地发育及其构造-气候意义

IEECAS SKLLQG

多藻浅水体中pH值和溶解氧协同周期性变化初探

在多藻浅水体中 ,每日 9:0 0～ 15 :0 0的pH值和溶解氧都呈上升趋势 ,两者呈协同周期性变化。经相关性回归分析 ,pH值的变化规律与溶解氧呈非常显著正相关 ,多藻浅水区pH值和溶解氧的回归关系相关系数r =0 912 9>r0 0 1(70 ) (r0 0 1(70 )=0 3 0 2 )。这可能与水体中氧化还原电位和水生植物光合作用伴随的代谢活动有关。这种相关性和协同周期性变化具有一定的生态学意义 ,并会对水体净化产生影响。

硝化抑制作用机理研究进展

总结了氨氧化细菌(AOB)和氨单加氧酶(AMO)的特性及氨(NH3)的催化氧化过程,综述了烷烃、烯烃、炔烃、芳烃、含硫(S)化合物、氮(N)杂环化合物和双氰胺(DCD)的硝化抑制作用机理。

间同1,2-聚丁二烯的结构和结晶动力学研究

间同1,2-聚丁二烯(s-PB)由丁二烯用Fe(2-EHA)3/Al(i-Bu)3/DEP作催化剂,在己烷溶剂中50℃下聚合制备.用13C NMR谱方法测定的1,2-结构含量为89.3%,间同结构为86.5%;X射线测得聚合物的结晶度约为68%.非等温结晶动力学研究采用DSC方法,改进的Avrami方程可以很好地分析s-PB非等温结晶过程的主期结晶,表明其结晶过程是自成核,三维球形生长.Ozawa方程不适合分析s-PB非等温结晶动力学;Avrami和Ozawa方程结合的方法可以很好地描述s-PB非等温结晶过程,指数a为1.138,F(θ)随着结晶度的提高而增大;并计算了s-PB的结晶活化能.

芳香环状低聚物组分分布与单体结构关系的研究

根据Jacoson-Stockmayer(J-S)环化理论,应用基质辅助激光解吸离子化飞行时间质谱(MAIDL-TOFMS),对一系列芳香环状低聚物组分分布进行分析,研究了芳香环状低聚物的组分分布与单体结构的关系,结果表明,在芳香聚酯、聚膦酸酯及芳香聚醚环状低聚物系列中,Inc_n与Inn呈良好的线性关系,符合J-S理论分布,在环状聚酯及聚膦酸酯系列中,低聚物的组分分布受双酚单体的中心键角影响,单体的中心键角在100°～120°之间,其中心键角愈小,γ值愈大,而在聚醚系列中,在固定一种单体的前提下,环化物的组分分布受另一单体键角的影响与环状聚酯和聚膦酸酯相一致。

The reduction of RE3+ in SrB6O10 prepared in air and the luminescence of SrB6O10 : RE2+ (RE=Eu, Sm, Tm)

The reduction of RE3+ to RE2+ (RE=Eu, Sm and Tm) in SrB6O10 prepared in air by high-temperature solid state reaction was observed. The luminescent properties of Eu2+ and Tm2+ show f-d transition and Sm2+ shows f-f transition at room temperature. Three crystallographic sites for Sm2+ in matrix are available. Vibronic transition of D-5(0)-F-7(0) of Sm2+ was studied. The coupled phonon energy about 108 cm(-1), was determined: from the vibronic transition. Due to the thermal population from D-5(0) level, (D1-FJ)-D-5-F-7 (J=0, 1, 2) transitions of Sm2+ were observed at room temperature. A charge compensation mechanism is proposed as a possible explanation.

Physical aging and crystallization of amorphous poly(aryl ether ether ketone ketone)

Physical aging of poly(aryl ether ether ketone ketone) (PEEKK) was investigated. Heat flow responses were measured after annealing the amorphous samples that were obtained by quenching the melt into an ice-water bath at just below the glass transition temperature. Isothermal cold crystallization of the aged samples was carried out. The Avrami equation was used to determine the kinetic parameters, and the Avrami constant it is about 2. An Arrhenius form was used to evaluate the relaxation activation energy of physical aging and the transport activation energy of isothermal crystallization. The activation energy of physical aging was similar in magnitude to that observed for the temperature dependence of crystallization under conditions of transportation control. Results obtained were interpreted as purely kinetic effects associated with the glass formation process. (C) 1998 John Wiley & Sons, Inc.

Synthesis and molecular structures of di- and trinuclear molybdenum complexes containing pyridine-2-thiolato (pyS) ligand

Dinuclear complexes [Mo-2(mu-pyS)(2)(CO)(4)(PPh(3))(2)] (1), [Mo-2(mu-pyS)(2)(CO)(5)(PPh(3))] (2) and a trace quality of trinuclear complex [Mo-3(mu-pyS)(2)(mu(3)-pyS)(2)(CO)(6)] (3) were obtained from the reaction of [Mo(CO)(3)(MeCN)(3)] with pyridine-2-thione (pySH) and PPh(3) in THF. The crystal structures of 1.2C(7)H(8) and 3.7 C7H8 have been determined by X-ray diffraction studies. Crystals of 1.2C(7)H(8) are monoclinic, space group C2/c and Z = 4, with a = 18.797(3), b = 11.143(4), c = 28.157(7) Angstrom, beta = 101.23(2)degrees. The structure was refined to R = 0.050 and Rw = 0.057 for 3146 observed reflections, Crystals of 3.7 C7H8 are monoclinic, space group P2(1)/a and Z = 4, with a = 13.912(2), b = 17.161(2), c = 15.577(3) Angstrom, beta = 101.17(1)degrees. The structure was refined to R = 0.046 and Rw = 0.051 for 4357 observed reflections. The molecule of 1 consists of two Mo(CO)(2)(PPh(3)) fragments linked by an Mo-Mo bond (2.974(2)Angstrom) and by two doubly-bridging pyS ligands. The compound 3 contains a bent open geometry of three molybdenum atoms (Mo(1)-Mo(2)-Mo(3) angle 122.99(3)degrees) linked by two Mo-Mo bonds (2.943(1) and 2.950(1) Angstrom) and by two doubly- and two triply-bridging pyS ligands.

海洋结构用钢在海洋大气中的氢脆机制研究

氢致开裂以及氢脆现象一直是困扰着石油生产及石油化工的一个重要问题。钢材的氢脆易造成巨大的腐蚀灾难。目前，随着石油开采钻井的深度的加深，石油开采中钢材所处的环境越来越恶劣。硫化氢，二氧化碳以及盐水等腐蚀介质可导致普通腐蚀，硫化物腐蚀，二氧化碳腐蚀，氢的渗透等腐蚀现象。这些腐蚀现象的存在，大大限制了石油工业的发展。硫化氢的存在可引起钢材的氢脆现象，给安全生产带来极大的隐患。然而，研究者对于氢脆现象的研究大部分是在本体溶液中的，对于在大气腐蚀中的氢脆现象的研究并不多见，并且对于动载条件下的氢渗透研究更为鲜见。 本文通过电化学研究方法及慢应变速率拉伸试验（SSRT）研究了从实验室模拟到实际海洋大气环境中，海洋大气对材料渗氢性能的影响及对材料应力腐蚀敏感性的影响，特别是在硫化氢及二氧化硫存在的条件下的影响。结果表明，从实验室模拟到实际海洋大气环境，材料都存在氢渗透现象，硫化氢及二氧化硫的存在可加速材料氢渗透现象，材料应力腐蚀敏感性也随其浓度的增大而增大。结合SEM实验结果，随硫化氢及二氧化硫浓度增大，金属材料由韧性断裂向脆性断裂转变。腐蚀失重实验表明，腐蚀失重与材料氢渗透量之间存在着线性关系。据此研制腐蚀失重传感器，实验结果表明，传感器结果与实际腐蚀失重结果一致，并且该传感器使用方便，可原位、随时、便捷地调查材料腐蚀失重，具有高适应性、高灵敏度的特点。 本文还研究了动载条件下，海洋大气环境中形变对材料氢渗透现象的影响。结果表明，弹性变形阶段，氢渗透电流变化不大，当试样屈服后，氢渗透电流突然下降，然后又回复到一个稳定值，这与氢陷阱的形成有关。

青海湖布哈河下游地区植物群落多样性研究

根据野外样方调查资料，对青海湖西部布哈河下游地区8种植物群落进行了研究。结果表明：群落的多样性随丰富度的降低而呈下降趋势，均匀度的变化受物种丰富度的影响不大，群落的物种多样性指数与丰富度指数和均匀度指数均表现出极显著的正相关性（P〈0．01），相关系数分别为0．912和0．684；群落的均匀度与丰富度相关性不显著，说明物种多样性主要为物种丰富度所推动。