交联β-葡萄糖苷酶聚集体的制备及应用

交联酶聚集体(CLEAs)是一种新型的无载体固定化方法.本研究利用该法对来源于西梅籽的β-葡萄糖苷酶进行了固定化研究.优化了制备交联β-葡萄糖苷酶聚集体的条件,并探讨其在丙基β-D-葡萄糖苷合成中的应用.研究发现,最适的沉降剂及其比例、最适交联剂(戊二醛)浓度以及交联时间分别为正丙醇、2/1(V/V)、10 mmol/...     

A review of interconnect materials used in emerging memory device packaging: first- and second-level interconnect materials

The main motivation of this review is to study the evolution of first and second level of interconnect materials used in memory device semiconductor packaging. Evolutions of bonding wires from gold (Au) to silver (Ag) or copper (Cu) have been reported and studied in previous literatures for low-cost solution, but Au wire still gives highest rating in terms of the performance of temperature humidity test, high temperature storage, and bond-ability, etc. However, a new bonding wire material, Au-coated Ag, is recently developed to be an alternative solution which gives comparable performance, but lower cost compared to Au wire. In the first section of the article, the influence of a variety of factors were reviewed, which includes reliability performance and interfacial reaction that determines the performance of Au-coated Ag to reach for developing high reliability of bonded devices. With respect to second-level interconnects, SAC305 and SAC302 solder alloys give a balance performance between temperature cycling testing and drop testing, which are widely used in many field applications, such as mobile, consumer and computer. SAC405 and LF35 are developed for specific requirements such as SAC405 owns better temperature cycling performance, whereas LF35 gives excellent drop performance compared to SAC305 or SAC302. However, with market demands on automotive electronics get strong in recent years, solder joint reliability is being reviewed and discussed, especially in temperature cycling performance. Typical solder alloys on Ni/Au surface finish were not designed for automotive application to fulfill the requirement of board level reliability. Hence, newly developed solder alloys with Sn/Ag/Cu/Bi/Ni elements and Cu-OSP substrate surface finishes will be reviewed in the second section of the article.

     

Efficient Production of 1,3-Dioleoyl-2-Palmitoylglycerol through Rhodococcus opacus Fermentation

1,3-Dioleoyl-2-palmitoylglycerol (OPO) is the main triacylglycerol species in human milk-fat substitute. The production of OPO is of considerable research interest. In this study, a new strategy for producing OPO by fermentation with R. opacus is proposed. Chemically Interesterified fat (high oleic acid sunflower oil/hydrogenated palm oil 1.73:1 w/w), or a mixture of ethyl oleate/ethyl palmitate 2:1 (w/w) as a starting material. The highest biomass and oil content obtained were 3.3 g L⁻¹ and 40.2% (dry cell weight), respectively. The yield of OPO was 0.62 g L⁻¹. The fatty acid composition of produced OPO was 55.7–59.7% 18:1 and 28.3–29.8% 16:0, and the sn-2 position was predominantly 16:0 (64.7–74.5%). ¹³C-nuclear magnetic resonance analysis showed that the sn-1,3 and sn-2 positions were predominately esterified by 18:1 and 16:0, respectively. OPO (47.1%), OPL (13.9%), PPO (13.1%), and PPoO (16:0–16:1–18:1) (10.3%) were the most abundant triacylglycerol species.     

Improving the efficiencies of simultaneous organic substance and nitrogen removal in a multi-stage loop membrane bioreactor-based PWWTP using an on-line Knowledge-Based Expert System

The results of the use of an expert system (ES) to control a novel multi-stage loop membrane bioreactor (MLMBR) for the simultaneous removal of organic substances and nutrients are reported. The study was conducted at a bench-scale plant for the purpose of meeting new discharge standards (GB21904-2008) for the treatment of chemical synthesis-based pharmaceutical wastewater (1200-9600 mg/L COD, 500-2500 mg/L BOD₅, 50-200 mg/L NH₄⁺-N and 105-400 mg/L TN in the influent water) by developing a distributed control system. The system allows various expert operational approaches to be deployed with the goal of minimizing organic substances and nitrogen levels in the outlet while using the minimum amount of energy. The proposed distributed control system, which is supervised by a Knowledge-Based Expert System (KBES) constructed with G2 (a tool for expert system development) and a back propagation BP artificial neural network, permits the on-line implementation of every operating strategy of the experimental system. A support vector machine (SVM) is applied to achieve pattern recognition. A set of experiments involving variable sludge retention time (SRT), hydraulic retention time (HRT) and dissolved oxygen (DO) was carried out. Using the proposed system, the amounts of COD, TN and NH₄⁺-N in the effluent decreased by 55%, 62% and 38%, respectively, compared to the usual operating conditions. These improvements were achieved with little energy cost because the performance of the treatment plant was optimized using operating rules implemented in real time.     

单自由度磁悬浮微动机器人的模糊控制系统研究

提出利用电磁铁的磁力作为机器人的运动驱动,利用这种电磁力的磁悬浮微动机器人不需要任何关节,结构紧凑,运动精度高。文中介绍了一种基于DSP的单自由度磁悬浮微动机器人的结构和工作原理,研究了磁悬浮机器人的运动控制系统,包括DSP系统、控制算法、软件结构,实验证明该系统能够较好地控制机器人的运动。     

The thermal conductivity mechanism of sewage sludge ash lightweight materials

The foaming reactions and the hydration and Pozzolanic effects of processed sewage sludge ash (SSA) allow it to be used as the main ingredient to make lightweight materials. The thermal conductivity of the SSA lightweight materials (SSALM), the SSA properties and how the mixing ratio of the materials influences the heat insulation properties are investigated. The results show that the thermal conductivity of SSA is low. When at room temperature, the pores in the specimens are filled with air, hence, the thermal conduction modes of these materials will be solid or air conduction. Radiant thermal conduction and natural convection can be ignored. The characteristics of the porosity, irregular particles and lightweight after the foaming reaction lead the thermal conductivity of the SSALM low to be 0.0763-0.2474 W/m K. When the water-to-solid ratio (W/S) and the amount of aluminum powder are increased, open and connected pores are formed, which negatively affects the compressive strength and the thermal conductivity. In addition, the total pore volume and thermal conductivity of SSALM are inversely proportional.     

利用纳米ZnO粉制备厚膜气敏传感器的研究

以ZnO纳米粉(平均粒径30nm)为原料,利用水热热压方法制备了ZnO多孔纳米固体,同时用通常的水热法对ZnO纳米粉进行了预处理(预处理ZnO纳米粉)。然后,分别以ZnO多孔纳米固体和预处理ZnO纳米粉为原料,制备了厚膜气敏传感器。本征电阻的测试结果表明,这两种厚膜气敏传感器的本征电阻比用未经处理的ZnO纳米粉(以下简称“原料ZnO纳米粉”)制备的厚膜气敏传感器大大降低并很快达到稳定状态。有效地改善了器件工作的稳定性。结合对三种传感器的显微结构分析,对出现上述差异的原因进行了讨论。     

一种基于条件随机场的复杂背景图像文本抽取方法

针对复杂背景图像中的文本抽取问题,文中提出一种基于条件随机场的图像文本抽取方法.该方法在将各种特征有效结合起来的同时,考虑到上下文特征,从而能有效地从复杂图像中抽取文本信息.分析比较不同颜色空间、不同特征对文本抽取性能的影响.实验结果表明该方法的有效性.     

Structurally tailored thiophene-based hybrid materials for thin-film and single-crystal transistors: Synthesis,photophysics and carrier-transport properties

The structures, optical properties, thin-film and single-crystal field-effect transistor performance of three thiophene-based hybrid materials, 5-(9-butyl-3-carbazolyl)terthiophene (BCTT), 2,5-bis(9-butyl-3-carbazolyl)thiophene (BBCT) and 2-(9-butyl-3-carbazolyl)-5-(2-dibenzothienyl)thiophene (BCDT), are reported. The structural modifications at one side of thiophene have significant effects on the intermolecular interaction, morphology and carrier-transport properties. The adjacent molecules in the solid state of BCTT adopt H aggregation, while compounds BBCT and BCDT both exhibit the formation of J aggregation. In BCTT, the crystal structure features a herringbone motif. The hole mobility for the single-crystal field-effect transistor based on BCTT reaches 0.094 cm² V^?1 s^?1, which is much higher than those of BBCT and BCDT. This study reveals that the enhanced rigidity in the molecules of BBCT and BCDT is not favorable to carrier transport.     

吗丁啉治疗胃食管反流相关性支气管哮喘疗效观察

目的: 观察吗丁啉对胃、食管反流相关性支气管哮喘的疗效。方法: 对50 例胃、食管反流相关性支气管哮喘患者, 在支气管哮喘急性发作时给予常规对症治疗的同时, 给予口服吗丁啉 20 mg, tid;伴有慢性胃炎者加服雷米替丁 0.3 g 、阿莫西林0.5 g 及灭滴灵 0.2 g, tid;有胃酸过多者夜间加服洛赛克(losec) 20 mg 。4 wk 为一个疗程, 第一个疗程结束后, 停药观察1 ~ 4 wk, 病情复发者继服第二个疗程。结果: 第一个疗程结束后, 有45 例病人停止发病, 观察6 mon 病情未复发。5 例在停药1 ~ 4 wk 病情复发者, 继服第二个疗程后, 有4 例停止发病, 随访6 mon 未复发, 1 例发病次数减少一半。结论: 吗丁啉用以预防和治疗胃、食管反流相关性支气管哮喘具有良好效果。