本征态的局域化与增益介质中局域态的放大

用时域有限差分方法(FDTD)模拟了二维增益、非增益随机介质中的光学现象。在非增益介质中，观察到了局域态空间分布及其频率特征。在增益介质中，观察到局域态的放大过程。模拟结果显示非增益介质中的局域态相当于传统激光腔的腔模，随机激光是由局域态谐振产生的。     

杂多酸在活性炭上的固载化：IV.活性炭在酸性介质中对硅钼（S…

在氢离子浓度均在３ｍｏｌ／Ｌ的硫酸，盐酸，磷酸，醋酸水溶液中和冰醋酸中研究了具有Ｋｅｇｇｉｎ结构的硅钼（ＳｉＭｏ１２）和磷钼（ＰＭｏ１２）杂多酸在不同来源活性炭上的吸附作用，在酸性介质中，其吸附量均比在水溶液中有所增加，但如果考虑吸附量与体系磷酸强度之间的关系，实验结果表明，ＳｉＭｏ１２和ＰＭｏ１２之间存在着不同的规律。     

Large Bandwidth Optical Limiting by Kerr Medium Doped One-Dimensional Coupled Cavity Optical Waveguides

We present a new method to realize large bandwidth optical limiting using Kerr nonlinearity doped one-dimensional coupled cavity optical waveguides (CCOWs). When the incident intensity is weak, the structure is a perfect CCOW that supports a high transmission band. When the intensity is increased, the Kerr effects change the refractive index of the Kerr cavity which results in a large decrease of transmission coefficients in the whole band. We numerically analyse the limiter using the nonlinear transfer matrix method and nonlinear finite difference in time domain method. Optical limiting effects are observed in the whole transmission band, and optimization methods are also discussed.     

轻烃中碳、氢同位素组成特征

本文收集了我国10个含油气区46个凝析油、轻质油样品,进行了全烃和部分饱和烃的碳、氢同位素分析,结合各地区地质背景,讨论了成气母质和沉积环境。从全油和饱和烃碳、氢同位素组成特征看,与煤系有关的凝析油常富集~(13)C,与Ⅰ,Ⅱ型母质(生油岩系)相关的凝析油则富集~(13)C。总体而言,碳同位素组成主要与母质的同位素继承效应相关,而氢同位素组成的变化则主要反映与沉积环境及水介质盐度的相关性。基于现有资料,提出δD值小于-150‰者为淡水-微咸水;大于-150‰者为半咸水-海水环境。研究表明,沉积相控制了有机母质,而不同有机母质又显示出稳定同位素组成的差异。     

稀土对铬锰氮不锈钢在稀硫酸介质中腐蚀磨损性能的影响

研究了稀土对铬锰氮不锈钢的腐蚀性能及腐蚀磨损性能的影响，稀土使各锰氮不锈钢的腐蚀电位正移、维钝电流降低、热力学稳定性提高，故其耐蚀性提高，抗磨性改善，铬锰氮不钢的最佳稀土含量为０．０２－０．０６％，为生产提供了必要的工艺参数。     

Synthesis and Characterization of Novel Layered Lithium Sodium Silicate （Silinaite） and the Mesoporous Materials from Silinaite

Novel layered silinaite has been synthesized using an aqueous mixture of water glass, LiOH and NaOH under hydrothermal crystallization. Subsequently transformation of silinaite into mesoporous materials (SDM) was achieved at mild condition using cetyltrimethylammonium bromide as structure-directing agents. The resulting samples were characterized by XRD, SEM, FTIR nitrogen adsorption-desorption isotherms and catalytic performance in bulky molecular involved reaction. The results revealed that synthesized mesoporous materials derived from the silinaite exhibited an ordered hexagonal crystal structure with average pore diameter 2.7 nm and BET surface area 817m2/g. The SDM-supported ZnCl2 catalyst, prepared by impregnation-evaporation method, retained the mesoporous structure and showed high selectivity in alkylation of benzene with benzyl chloride.     

Ni和P微量掺杂的Pd基催化剂对碱性介质中乙醇电氧化性能的增强效应研究

保证催化剂质量活性（通常以贵金属质量为计量）的基础上,减小催化剂中助催化剂的用量可有效降低燃料电池膜电极组（MEA）催化剂层的厚度,从而提高贵金属利用率和增大放电电压.于此,本文以微量NaH₂PO₂作为还原剂,适当调节合成溶液的碱度,成功制备了助催化剂Ni和P的掺杂量分别低至0.2%（w）和0.05%（w）的三元碳载Pd-Ni-P纳米合金催化剂.所得催化剂在0.5 mol/L CH₃CH₂OH＋1 mol/L NaOH溶液中的循环伏安表征显示,质量活性最高可达到2466 mA•mg^-1 Pd,是商业化Pd/C催化剂的2.7倍;同时,计时电流法测试表明,该催化剂的稳定性相对于商业化催化剂提升了2.8倍.这说明所得低掺杂型Pd-Ni-P催化剂达到了上述设计要求.本工作可能为燃料电池高效低成本阳极催化剂设计制备提供新的思路.     

多孔介质热弥散系数的分形模型北大核心CSCD

热弥散系数是与流体的物性和多孔介质结构有关的,表征多孔介质传热传质强弱的重要参数.该文建立了分形多孔介质的孔喉结构模型,研究了在孔喉结构处流体由湍流状态变为层流状态的局部水头损失和速度弥散效应,在考虑微观孔喉结构和速度弥散效应的影响下,推导了热弥散系数关系式.研究表明,热弥散系数与孔喉比、孔喉结构个数和迂曲分形维数成正比,与孔隙率和面积分形维数成反比.进一步研究发现,孔喉比在1~150范围内对速度弥散效应有显著影响,流体在孔喉结构处存在局部水头损失,导致速度弥散效应增强,热弥散系数增大.     

N—正辛基己内酰胺从硝酸介质中萃取铀（Ⅵ）的动力学研究

采用上升单液滴法研究了Ｎ－正辛基己内酰胺从硝酸介质中萃取铀（Ⅵ）的动力学，得出Ｕ（Ⅵ）的萃取速率与水相中铀浓度的１次方成正比，与温度（１０－４５℃）无关；萃合物向有机相的扩散为萃取过程的速控步骤。     

有机溶液中电化学制备纳米MgTiO3

In a cell without separating the cathode and anode spaces, the precursor MgTi(OCH₂CH₃)_(6-y)(acac)_y of the mixed oxide MgTiO₃ was directly synthesized by electrochemical dissolution of titanium for 4 hours and then of magnesium for 1 hour 40 minutes at the current of 0.2 A in ethanol and acetyl-acetone solution. The nano- MgTiO₃ powder was prepared by a direct sol-gel process of the electrolyte solution under pH≈8.5 followed by washing, drying in vacuum for 24 h, and calcination at 500 ℃ for 2 h. IR and Raman spectroscopy, XRD, and TEM were used to investigate the structure of nano-MgTiO₃ and its precursor. The result suggested that it was more appropriate to control the temperature between 35～40 ℃ and the concentration of conductive additive (Bu₄N)Br at 0.04 mol·L^-1. The xerogel with an average particle size of 12 nm and the nano-MgTiO₃ of 20 nm was thus obtained in a high purity.