复合分子筛催化剂的苯酚异丙醇烷基化反应性能

本文采用水热后合成法得到β-MCM-41复合分子筛,并用其做为催化剂催化苯酚异丙醇烷基化反应。利用NH3-TPD和XRD的表征方法对复合分子筛进行了表征,结果证实了β-MCM-41是具有弱酸和强酸双重酸性和微孔和介孔双重结构的复合分子筛,并且其酸性强酸量多适宜酸催化的苯酚异丙醇烷基化反应。实验表明:复合分子筛β-MCM-41良好的结构不但提高了苯酚的转化率,同时还提高了对异丙基苯酚的选择性。     

粗糙龙胆龙胆苦苷含量的标准化测定与提取方法

应用高相液相色谱法测定粗糙龙胆根的龙胆苦苷含量,探讨更准确、简便和经济的标准化测量和提取方法。测定紫外检测波长270nm。龙胆标准曲线回归方程为:Y=7.20e+006X-1.96e+003,r=0.99967。龙胆苦苷平均回收率为98.19%,RSD=4.2%。稳定实验中含量的保留时间的RSD=0.3%,峰面积的RSD=4.1%,含量的RSD=3.9%,12小时内稳定。精密度实验中的峰面积积分值的RSD=1.3%。标准方法为以甲醇—水(25∶75)为流动相,流速:1.0 m L/min,紫外检测波长270 nm。此方法能准确,快捷的测定粗糙龙胆根中龙胆苦苷的含量,可作为粗糙龙胆根龙胆苦苷的测定方法。     

Preparation of copper containing methacrylic polymers and their application for the copper patterns

Copper containing methacrylic polymers were prepared by the polymerization of a copper methacrylate complex (Cu[CH₂C(CH₃)COO](COD), where COD = 1,5-cyclooctadiene) with different methylmethacrylate and methacrylic acid compositions. These polymers were found to be soluble in many organic solvents including THF and chloroform. Copper nano-networks or aggregated nanoparticles were obtained when a THF solution of the polymers was reduced using an aqueous sodium borohydride solution. When a thin film of the polymers coated on a silicon wafer was irradiated with an electron beam, nanoparticles were produced on the irradiated area, while the non-irradiated areas could be washed away with a weak base developer, such as a tetramethylammoniumhydroxyde (TMAH) aqueous solution, to produce a copper pattern through an electron beam lithography process.     

Cathode materials based on carbon nanotubes for high-energy-density lithium–sulfur batteries

The rational integration of conductive nanocarbon scaffolds and insulative sulfur is an efficient method to build composite cathodes for high-energy-density lithium–sulfur batteries. The full demonstration of the high-energy-density electrodes is a key issue towards full utilization of sulfur in a lithium–sulfur cell. Herein, carbon nanotubes (CNTs) that possess robust mechanical properties, excellent electrical conductivities, and hierarchical porous structures were employed to fabricate carbon/sulfur composite cathode. A family of electrodes with areal sulfur loading densities ranging from 0.32 to 4.77 mg cm⁻² were fabricated to reveal the relationship between sulfur loading density and their electrochemical behavior. At a low sulfur loading amount of 0.32 mg cm⁻², a high sulfur utilization of 77% can be achieved for the initial discharge capacity of 1288 mAh g_S⁻¹, while the specific capacity based on the whole electrode was quite low as 84 mAh g_{C/S+binder+Al}⁻¹ at 0.2 C. Moderate increase in the areal sulfur loading to 2.02 mg cm⁻² greatly improved the initial discharge capacity based on the whole electrode (280 mAh g_{C/S+binder+Al}⁻¹) without the sacrifice of sulfur utilization. When sulfur loading amount further increased to 3.77 mg cm⁻², a high initial areal discharge capacity of 3.21 mAh cm⁻² (864 mAh g_S⁻¹) was achieved on the composite cathode.     

环境友好型尖晶石类光催化材料的性能

综述了近几年来尖晶石型光催化材料最新研究进展。主要介绍了尖晶石的构型、光催化机理及光催化性能。重点讨论了其在常见的几种染料(甲基橙、罗丹明)、苯酚、甲苯催化降解、甲烷燃烧及光催化制备氢等方面的光催化性能。     

Room-temperature creep behavior on crack tip of commercially pure titanium

The room-temperature creep behavior on crack tip of compact tensile (CT) specimen for commercially pure titanium (CP-Ti) was studied by experiment and finite element (FE) simulation in this paper. The experimental results indicated that the time-dependent deformation was observed on the crack tip of CP-Ti CT specimen at room temperature, which agreed with the primary creep, and crack propagation was not observed. In order to consider the creep behavior on crack tip, time-dependent J-integral was used to characterize the stress fields near crack tip. The room-temperature creep behavior on crack tip was analyzed by FE simulation, which was verified by experimental results. Then, the strain fields under different stress states were analyzed by FE simulation. The influences of the locations to crack tip and load on the room-temperature creep were analyzed, which shows that the creep significance on crack tip is enhanced with increasing of load and decreasing of distance to crack tip. The estimation formula of creep strain value along ligament direction of CP-Ti CT specimen was established and verified by FE simulation results.     

基于非线性复扩散耦合冲激滤波器的图像放大算法研究简

为了提高放大算法的适应性,采用改进的非线性复扩散和自适应冲激滤波器,提出了一种图像放大方法。根据像素局部方差进行自适应改变扩散门限,扩散图像的虚部除以扩散时间以消除扩散时间的影响,特别是初期扩散近似线性扩散的特性,得到改进的复扩散模型耦合冲激滤波器进行无噪图像放大。对于噪声图像放大,根据像素局部方差进行自适应非线性复扩散,耦合局部方差约束的冲激滤波器增强模糊的图像边缘和细节。自适应非线性复扩散通过局部方差和图像二阶导数相结合分辨边缘和噪声,对噪声进行平滑的同时保持边缘,克服了复扩散不能分辨噪声和边缘的缺陷,同时保持复扩散保护斜坡结构,免除阶梯效应的优点。仿真实验验证了所提算法不仅对无噪图像有较好的放大效果,而且对一定范围的噪声图像也有较好的放大效果。