高取代度氰乙基纤维素与二醋酸纤维素共混中空纤维纳滤膜的研制

采用高取代度氰乙基纤维素与二醋酸纤维素共混为膜材料,丙酮、二氧六环混合溶剂,以有机醇为主、加入适量其他添加剂为致孔剂,通过冰水凝胶浴干湿法纺丝,制得性能良好的中空纤维纳滤膜,该膜在给水质量浓度1 800 mg/L、操作压力为0.6 MPa、水温25℃条件下,对二价盐CaCl2、一价盐NaCl的水溶液的脱盐率分别大于90%和小于60%,水通量均大于3.5 mL/(cm2.h).还讨论了膜液的组成和纺丝条件对膜性能的影响.     

采煤机破碎机构的设计

结合采煤机破碎机构的传动装置,简要地阐述了应用数学规划理论进行采煤机破碎机构的设计原理,以更好地发挥采煤机的功效。     

单模光纤环轴向磁场问题的理论研究

去偏光纤陀螺的非理想单模光纤,在垂直于光纤环面的轴向磁场作用下,由于Faraday 效应,在其中传播的正反两束光会产生一个与磁场有关的非互易相位差.本文基于单色光对在轴向磁场作用下的单模光纤环进行理论推导、分析,给出仿真结果和实验结果,并提出减小轴向磁场作用下的Faraday非互易相位差的方法.     

AFM氮化硅纳米探针研制

在〈100〉晶向硅片上通过各向异性腐蚀形成作为模板的倒金字塔形尖坑, 用LPCVD和PECVD法淀积一层约 1 μm厚的氮化硅膜, 通过等离子刻蚀形成悬臂梁图形,再把抛光玻璃片静电键合到氮化硅膜上, 最后把衬底硅片腐蚀掉,带有金字塔形针尖的悬臂梁就暴露出来,从而构成可用于原子力显微镜(AFM)描绘纳米图像的氮化硅纳米探针.对针尖的尖度和氮化硅膜悬臂梁的热应力补偿进行了深入研讨, 并报道一种特殊而有效的悬臂梁掩模板图形的新设计.制成的氮化硅纳米探针在原子力显微镜上成功地描绘出了纳米图像, 经检测, 其 Z向偏转检测精度优于10-9量级.     

Interpretation of Absolute Laser Reflectance During Optical Monitoring of Polycrystalline GaAs Deposition on Quartz Using Metalorganic Chemical Vapor Deposition

Gallium arsenide (GaAs) was deposited by metalorganic chemical vapor deposition in a horizontal quartz reactor tube using trimethylgallium and arsine at 400°C to 500°C. Nucleation time and deposition rate were monitored using in situ laser reflectometry. This allowed differentiation between film and parasitic growth, which was not possible with other optical techniques. An absolute reflectance model was developed using measurements prior to GaAs deposition, and then employed to calculate values for GaAs on quartz. Detected reflectance intensities during experimental GaAs deposition were low compared with the model due to three-dimensional island growth, causing scattering of the incident laser radiation.     

Removal of sulphate from mine water with barium sulphide

The Barium Sulphide Process removes sulphates from mine water by precipitating BaSO₄ with BaS. Barium sulphide is regenerated thermally by reducing the BaSO₄ with coal at 1000–1100°C for about 15 minutes. The process produces elemental sulphur and CaCO₃ as by-products. Laboratory studies achieve typical sulphate reductions of about 95%. Metals such as Fe, Ni, Co and Mn are also removed and pH can be increased from 1,4 to 8,3. The process has a water recovery of about 70%. For a 25 Ml/d plant (2g/l SO₄ ^2?), the capital cost is estimated at US$ 0,48m/Ml/d, while the detailed running costs amount to a net value of 27 c/m³. This compares well with that of other processes for desalination and is less than the fresh water price for new mines in South Africa, viz. 30c/m³.     

Increased conversion efficiency in cadmium telluride photovoltaics by luminescent downshifting with quantum dot/poly(methyl methacrylate) films

Commercially available quantum dots have been encapsulated in a poly(methyl methacrylate) film and used as a luminescent downshifting layer on cadmium sulfide/cadmium telluride photovoltaic devices. Application of these films has resulted in a relative improvement to the short‐circuit current of over 4% by I–V measurement, with a significant increase in the contribution of short‐wavelength light resulting in 25% of the current available in this part of the spectrum being captured. The films have been shown to be highly scattering and the associated difficulties this provides to external quantum efficiency measurements have been discussed. A range of optical characterisation techniques, particularly laser beam induced current, have been used to probe the effect the films have on a cadmium sulfide/cadmium telluride device. An alternate methodology for performing external quantum efficiency measurements with the quantum dot films has been proposed. Copyright © 2013 John Wiley & Sons, Ltd.     

Mutational analysis of the gene for Schizosaccharomyces pombe RNase MRP RNA,mrp1, using plasmid shuffle by counterselection on canavanine

Reverse genetics in fission yeast is hindered by the lack of a versatile established plasmid shuffle system. In order to screen efficiently and accurately through plasmid-borne mutations in the essential gene for the RNA component of RNase MRP, mrp1, we have developed a system for plasmid shuffling in fission yeast using counterselection on canavanine. The system takes advantage of the ability of the Saccharomyces cerevisiae CAN1 gene to complement a Schizosaccharomyces pombe can1-1 mutation. Two general use plasmids were constructed that allow directional cloning and initial selection for histidine before counterselection by canavanine. The strain constructed for plasmid shuffling carries auxotrophic markers for ade6, leu1, ura4 and his3 along with the can1-1 mutation. Using this system we examined several partial deletions and point mutations in conserved nucleotides of Schizosaccharomyces pombe RNase MRP RNA for their ability to complement a chromosomal deletion of the mrp1 gene. The degree of background canavanine resistance as well as plasmid–plasmid recombination encountered in these experiments was sufficiently low to suggest that the system we have set up for counterselection by canavanine in fission yeast using multicopy plasmids will be widely useful.     

新疆东天山灵北地区康南岩体岩石学#br# 特征及其构造意义

研究区位于新疆东天山觉罗塔格造山带吐哈盆地以南百灵山以北,多年来对于研究区古生代构造背景的认识受前人热议,存在争议。通过对研究区新发现基性岩体的岩石、地球化学特征与构造背景进行探讨,以期为大区域构造背景的研究提供一定的数据支持。主量元素研究表明,康南岩体具有高Mg、Fe,低Al的特征,说明研究区基性侵入岩为碱性岩石系列。微量元素测试结果表明具有同源演化的特征,Rb、Hf元素亏损较为严重。K、Ba、P、Sm富集明显,Tb、Nb、Ti表现为弱异常,在稀土元素球粒陨石标准化配分模式图中Eu的负异常不明显,表现为弱的正异常, Yb+Nb-Rb构造环境判别图解中样品落在“后碰撞”环境内,以上特征说明具有岛弧花岗岩的基本特征。岩性为深灰绿色弱蚀变细粒橄榄辉绿岩。