Wetting and wetting transitions on copper-based super-hydrophobic surfaces

Rough and patterned copper surfaces were produced using etching and, separately, using electrodeposition. In both of these approaches the roughness can be varied in a controlled manner and, when hydrophobized, these surfaces show contact angles that increase with increasing roughness to above 160 degrees . We show transitions from a Wenzel mode, whereby the liquid follows the contours of the copper surface, to a Cassie-Baxter mode, whereby the liquid bridges between features on the surface. Measured contact angles on etched samples could be modeled quantitatively to within a few degrees by the Wenzel and Cassie-Baxter equations. The contact angle hysteresis on these surfaces initially increased and then decreased as the contact angle increased. The maximum occurred at a surface area where the equilibrium contact angle would suggest that a substantial proportion of the surface area was bridged.     

Substituent effects on O–H and S–H bond dissociation enthalpies of disubstituted phenols and thiophenols

The O–H and S–H homolytic bond dissociation enthalpies of a set of disubstituted phenols and thiophenols (NH₂, OH, CH₃, Cl, CF₃, and NO₂) have been computed by a density functional theory procedure with the 6‐311++G(d,p) basis set. A very good agreement between our results and available experimental ones is observed. The effect of substituents on structure, charges and BDEs are investigated and their correlation with Hammett parameters is studied. © 2007 Wiley Periodicals, Inc. Int J Quantum Chem, 2008     

一类具时滞耗散型Duffing方程的周期解

利用Mawhin重合度理论研究了一类耗散型时滞Duffing方程ax″+f[x′(t-τ1(t))]+cx+g(x(t-τ2(t)))=p(t)周期解的存在性,得到了该方程2π周期解存在的充分性定理.     

Beam‐size‐related phenomena and effective normalization in energy‐dispersive EXAFS for the study of heterogeneous catalysts,powder materials and the processes they mediate: observations and (some) solutions

The effects of focal spot size and the nature of powder samples (such as heterogeneous catalysts) on the quality of data obtainable from a dispersive EXAFS experiment are characterized at ID24 of the ESRF. Using examples of supported Pd catalysts, it is shown that, for a given photon flux, massive improvements in data quality can be achieved by increasing the size of the dispersive beam in the vertical, whilst concurrently applying a methodology to account for scattering effects emanating from the samples under study. These improvements are demonstrated using progressively practical and demanding examples. Questions regarding optimal beam dimensions for the study of such materials, how to counter undesirable effects that arise from the coherence of the source, how to obtain similar results consistently across the 5–30 keV bandwidth of ID24, and whether a methodology for simultaneous normalization in dispersive EXAFS is of significant utility in such circumstances are discussed.     

吡罗昔康凝胶有效成分的紫外分光光度法测定

吡罗昔康凝胶是吡罗昔康加适量的基质的透明的透皮吸收制剂。本文提出了对其有效成分吡罗昔康进行紫外光光度测定的方法，该方法简便、快速，能用于纯度较高的样品分析，可作为吡罗昔康凝胶药品质量标准控制方法。     

长径比可控的CdS纳米棒制备及光催化性能研究

采用溶剂热法制备了长径比可控的纤锌矿CdS纳米棒;以3CdSO4·8H2O、CH4 N2S为原料在180℃、24 h溶剂热反应条件下,通过改变Cd/S物质的量比和保温时间等因素来调节CdS纳米棒的长径比.利用扫描电镜(SEM)、X射线衍射(XRD)、紫外可见吸收光谱(UV-Vis)、光催化分别对其形貌、结构和光催化性能进行了表征和分析.结果表明:Cd/S摩尔比对CdS棒的生长起到关键作用,随着镉硫比的减小,CdS纳米棒的长径比逐渐增大.当Cd/S摩尔比为1∶6时,制备的CdS为长径比较大且表面光滑的纳米棒,纳米棒的尺寸大约为长800 nm、直径70nm.通过降解亚甲基蓝溶液测试了CdS纳米材料的可见光照射下的光催化性能,结果表明具有大长径比的CdS纳米棒表现出优异的光催化活性.     

一种监控膜厚的新算法

光学薄膜的光学特性与其每一膜层的厚度密切相关,为了制备出符合要求的光学薄膜产品,在制备过程中必须监控膜厚。光学薄膜实时监控精度决定了所镀制的光学薄膜的厚度精度。针对光电极值法极值点附近监控精度低、无法精确监控非规整膜系的缺陷,提出了新的光学薄膜膜厚监控算法。该算法通过数学运算,使得光学薄膜的光学厚度与透射率呈线性关系,并且有效地消除光源波动、传输噪声等共模干扰的影响,算法精度可控制在2%以内。     

新疆伊犁小于赞金矿床中FeS2的矿物学研究

小于赞金矿床赋存于下石炭统大哈拉军山组上亚组中酸性火山岩及火山碎屑岩中,为浅成低温热液型金矿。文章通过对小于赞矿区金矿床中FeS2的矿物学研究,对摸清金矿的机理具有现实意义,对指导该区进一步找矿具有重要意义。