Synthesis and properties of acrylonitrile-CR-methyl methacrylate graft copolymer

Graft copolymerization of acrylonitrile (AN) and methyl methacrylate (MMA) onto polychloroprene (CR) was carried out using benzoyl peroxide as initiator. The effects of mole ratio of AN to MMA, reaction temperature, reaction time, solvent, and initiator concentration on the graft copolymerization were examined. It was found that the thermal stability and weatherability of the AN—CR—MMA graft copolymer (ACM) were considerably better than those of CR.     

Copolymerizations of ethylene with 1–decene over various ansa–metallocene complexes combined with Al( i-Bu) 3/ [CPh 3] [B(C 6F 5) 4] cocatalyst

Copolymerizations of ethylene with 1-decene were carried out with a series of stereospecific metallocene compounds, rac–(EBI)Zr(NMe₂)₂ [ 1, EBI = ethylene–1,2–bis( 1–indenyl)], rac–(EBI)Hf(NMe₂ (2), rac–Me₂Si( 1–C₅H₂–2–Me–4– ^t Bu)₂Zr(NMe₂)₂ (3), ethylidene(cyclopentadienyl)(9-fluorenyl)ZrMe2 [4, Et(Flu)(Cp)ZrMe2] and isopropylidene(cyclopentadienyl)(9–fluorenyl)ZrMe₂ [5, iPr(Flu)(Cp)ZrMe₂], combined with Al(i–Bu)₃/[CPh₃] [B(C₆F₅)₄] cocatalyst. All catalyst systems showed very high copolymerization rates and the 1–decene reactivity decreased in the order of 2 > 5 > 1 4 > 3. The reactivity product of ethylene and 1–decene (r _E x r _D) was below 1 except 3 catalyst, corresponding to random copolymer structures with an alternating character. The melting point (T_m), crystallinity (X_C), intrinsic viscosity ([] and density of the 1–decene/ethylene copolymers decreased markedly with an increase in the 1–decene content, regardless of the type of catalytic system.     

Advanced underfill for high thermal reliability

The key to the success of flip‐chip technology lies in the availability of sucessful underfill materials. However, the reliability of flip‐chip technology using current underfill materials is generally found to be lower than that of conventional wire‐bond connection packaging materials such as epoxy molding compound (EMC) because of the high coefficients of thermal expansion (CTE) and moisture absorption of cured underfill material. In this study desbimide (DBMI), which has a low melting point (about 80°C), was used in the underfill materials as a cohardener. As a result, DBMI‐added underfill can show excellent thermal reliability, which is due to the superior properties of the CTE, the elastic modulus, and water resistance. When the properties of a 2 wt % DBMI‐added underfill were compared with those of a typical underfill (epoxy/anhydride), the CTE value was reduced to less than one‐half at the solder reflow temperature (about 200°C), the elastic modulus was reduced to less than one‐half in the temperature region below the glass‐transition temperature, and the water resistance was improved twofold. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2617–2624, 2002     

模型驱动的装备保障优化决策支持系统

以数据、模型、用户界面等要素为基础,提出了以优化模型为驱动的装备保障优化决策支持系统设计思路,拓展设计了系统总体功能结构.构建了包含算法库、模型库和应用库的模型库,引入了脚本模型,以顺序、选择或循环结构程序组合优化模型,实现复杂装备保障决策问题的求解和决策.实例应用表明系统极大地提高了部队装备精确保障能力.     

无线环境下基于多流优先级的并行多路传输

在无线异构网络环境下提出一种基于多流优先级的并行多路传输方案。该方案基于并行多路传输协议CMT-SCTP,并利用了SCTP的多流特性和部分可靠特性。针对数据的重要性和时间敏感度,设计优先级数据调度算法;同时提出基于路径质量的数据分发机制,进一步保证数据的有效传输。在NS-2中的仿真结果表明,该方案能够有效提高数据传输的吞吐量,减少时延,保证较好的数据传输性能。     

Effect of scraped-surface tube cooler temperatures on the physical properties of palm oil margarine

The effects of scraped-surface tube cooler temperatures on the isothermal solid fat content (SFC) of palm oil margarine during processing and on margarine consistency (yield value, g/cm²), SFC, and polymorphic changes in storage were studied. SFC was measured in the mixing tank after leaving the tube cooler and the pin worker. The SFC at the tube cooler exit was proportional to the amount of cooling; a higher SFC was produced by more extreme cooling treatment. The SFC of all margarines were reduced in the pin worker, and the reduction was related to the initial SFC profile of palm oil. Margarine samples were stored at 28°C for 28 d and tested daily. Margarine processed at 25°C in the tube cooler had the highest consistency and the least change in SFC, but by the second week crystals had transformed into the β form. Uniform product consistency and SFC were observed in margarines processed at 20 and 15°C. These margarines retained the β′ crystal form for 3 and 4 wk, respectively. The best palm oil margarine was obtained with a tube cooler temperature of 15°C and a residence time of 1.8 min.     

Molecular species of 1-O-alk-1′-enyl-2-acyl-, 1-O-alkyl-2-acyl- and 1,2-diacyl glycerophospholipids in Japanese oysterCrassostrea gigas (Thunberg)

Molecular species of 1-O-alk-1′-enyl-2-acyl-, 1-O-alkyl-2-acyl-, and 1,2-diacyl-sn-glycero-3-phosphoethanolamine (EPL) andsn-glycero-3-phosphocholine (CPL) of Japanese oysterCrassostrea gigas were analyzed by selectedion monitoring gas chromatography/mass spectrometry using electron impact ionization. The characteristic fragment ions, [RCH=CH+56]⁺ due to the alkenyl residue in thesn-1 position and [RCO+74]⁺ due to the acyl residue in thesn-2 position of alkenylacylglycerols, [R+130]⁺ due to the alkyl residue in thesn-1 position and [RCO+74]⁺ due to the acyl residue in thesn-2 position of alkylacylglycerols, [RCO+74]⁺ due to the acyl residues in thesn-1 and/orsn-2 positions of diacylglycerols, and [M−57]⁺ being indicative of the corresponding molecular weight, were used for structural assignments. For alkenylacyl EPL and CPL, 19 and 16 molecular species were determined, respectively. Two molecular species, 18∶0alkenyl-22∶6n−3 and 18∶0-alkenyl-22∶2-non-methylene interrupted diene (NMID), amounted to 53.2% and 47.9%, respectively. The alkylacyl EPL and CPL consisted of 16 and 20 molecular species, respectively, and the prominent components were 18∶0alkyl-22∶2NMID, 20∶1alkyl-20∶1n−11 (27.4%) and 20∶1alkyl-20∶2NMID (16.3%) in the former, and 16∶0alkyl-20∶5n−3 (23.0%) and 16∶0alkyl-22∶6n−3 (21.6%) in the latter. For the diacyl EPL and CPL, 14 and 51 molecular species were determined, respectively. The major molecular species were 18∶0–20∶5n−3 (37.4%), 16∶0–20∶5n−3 (14.2%) and 18∶1n−7–22∶2NMID (13.2%) in the former, and 16∶0–20∶5n−3 (33.4%) and 16∶0–22∶6n−3 (22.3%) in the latter. It was found that there were significant differences in the molecular species between the alkylacyl and diacyl EPL and the alkylacyl and diacyl CPL; the number of molecular species was larger in CPL than in EPL, while the number of total carbons and double bonds of the major molecular species were larger in the EPL than in the CPL. Alkenylacyl EPL were similar to alkenylacyl CPL in molecular species composition.     

嗜酸氧化亚铁硫杆菌驯化条件的研究

随着办研究氧化亚铁硫杆菌结果表明,最佳培养温度为30℃左右,最佳生长pH为2.0～2.5,最佳生长初始Fe2＋浓为0115mol/L左右,在进行细菌培养时接种量取10%比较恰当。低pH值和高浓度Fe2＋驯化后,在培养温度30℃、初始pH值1.5、初始Fe2＋浓度25g/L条件下,氧化亚铁硫杆菌仍能保持一定的Fe2＋氧化活性,6天Fe2＋氧化率可达82.28%,Fe2＋平均氧化速率达3.43g/L/d,pH值的变化是先上升后下降,最后稳定在1.81。     

Temperature distribution and dynamic control of secondary cooling in slab continuous casting

To predict and optimize the temperature distribution of slab continuous casting in steady operational state, a three-dimensional model (named offline model) based on the heat transfer and solidification theories was developed. Both heat transfer and flux distribution characteristics of the nozzle sprays on the slab were considered, and the complicated boundary condi-tions, such as spray cooling, natural convection, thermal radiation as well as contact cooling of individual rolls were involved in the model. ...     

Power management unit chip design for automobile active-matrix organic light-emitting diode display module

A power management unit (PMU) chip supplying dual panel supply voltage, which has a low electro-magnetic interference (EMI) characteristic and is favorable for miniaturization, is designed. A two-phase charge pump circuit using external pumping capacitor increases its pumping current and works out the charge-loss problem by using bulk-potential biasing circuit. A low-power start-up circuit is also proposed to reduce the power consumption of the band-gap reference voltage generator. And the ring oscillator used in the ELVSS power circuit is designed with logic devices by supplying the logic power supply to reduce the layout area. The PMU chip is designed with MagnaChip’s 0.25 μm high-voltage process. The driving currents of ELVDD and ELVSS are more than 50 mA when a SPICE simulation is done.