Glass transition and the rigid amorphous phase in semicrystalline blends of bacterial polyhydroxybutyrate PHB with low molecular mass atactic R, S-PHB-diol

The glass transition and the crystallinity of blends of isotactic bacterial PHB and low molecular mass atactic R, S-PHB-diols was investigated by means of differential scanning calorimetry (DSC), temperature-modulated DSC and dielectric spectroscopy. It was found that (i) T_g of crystallized blends is much lower than T_g of quenched blends, (ii) the semi-crystalline blends can only be described with a three-phase model. From the experimental results the amount of the oligomer component in the mobile amorphous as well as in the rigid amorphous phase was determined. It could be shown that the low molecular mass atactic R, S-PHB-diol is enriched in the mobile amorphous phase of the semi-crystalline blends, but 5-15% oligomer remains, however, in the rigid amorphous phase.     

锂系溶聚装置产品发展分析

阐述了国内外以锂系化合物为催化剂的溶聚装置主要产品的现状、技术及需求情况，并对锂系产品进行了成长性分析。对其发展趋势进行了预测。     

CO hydrogenation over potassium-promoted Fe/carbon catalysts

The effects of potassium on the catalytic behavior in CO hydrogenation over K-promoted Fe/carbon catalysts having low K/Fe ratios were investigated. Even though the doses of potassium were low the promotional effects were pronounced, especially on the olefin-to-paraffin ratio, and theC ₃ toC ₄ olefin selectivities of the K-promoted catalysts were as high as 51 to 66 mol%. Over the catalysts having no or low potassium content the olefin-to-paraffin ratio and the ratio of the CO₂ formation rate to the rate of CO conversion to hydrocarbons remained roughly the same regardless of temperature, while over the K-promoted catalysts having higher potassium content they increased with temperature. Formation of significant amounts of filamentous carbon was observed in the K-promoted catalysts; however, the carbon deposition did not appear to affect the inherent activity and selectivity of the K-promoted catalysts.     

Stabilized heteropolyacid/Nafion composite membranes for elevated temperature/low relative humidity PEFC operation

Organic/inorganic composite membranes with different inorganic heteropolyacid (HPA) additives maintain sufficient proton conductivities for atmospheric pressure elevated temperature (>100 °C) polymer electrolyte fuel cell (PEFC) operation. However, membrane and membrane electrode assembly (MEA) processing is severely curtailed because of the solubility of the HPA additives in aqueous media. Composite membranes with the HPA (phosphotungstic acid; PTA) additive rendered insoluble by ion exchanging protons with larger cations such as Cs⁺, NH₄⁺, Rb⁺ and Tl⁺ were fabricated. The additive loss in aqueous media was lowered from nearly 100% (unmodified HPA) to about 5% (modified HPA). The membranes were robust, and demonstrated low H₂ crossover currents of around 2 mA/cm² for a 28 μm thick membrane. All membranes were evaluated at high temperatures and low relative humidities in an operating fuel cell. The conductivities of the composite membranes at 120 °C and 35% relative humidity were on the order of 1.6 × 10⁻² S/cm.     

一种基于条带划分的低延迟帧内编码方法

现有编解码系统所产生的固有延迟比较大,例如对于标清视频,系统延迟要大于260ms,因此难以用于对延迟有严格要求的系统中。为此,研究了一种新的低延迟帧内编解码结构,在该结构中,将输入的视频划分成若干个条带,在采集端以条带为单位进行采集,以有效降低采集延迟;同时,给出了以条带为基本单位的I帧编码方法,对每一编码条带下采样,将其分成4个子图,以子图为单位进行预测,以提高预测的精度,进而降低编码延时。实验表明,新的编码结构在采集和编码过程中能有效降低帧内编码延迟,在保证恢复图像质量的同时,可以将延迟降低到150ms。     

面向低功耗共享Cache路适应划分算法研究

如何提高多核处理器的性能和降低多核处理器中Cache的功耗已经成为下一代多核处理器的研究热点。为了降低片上多核处理器的功耗,基于路适应算法可以采用一种新的动态划分机制,该机制主要由路分配模块和动态功耗控制模块组成。路分配模块在程序运行过程中根据处理器核所运行线程的工作集的大小调整处理器核所分配的Cache路。动态功耗控制模块利用程序运行的局部性原理,将处理器核所运行线程的工作空间控制在少数Cache路中。关闭剩余的Cache路,从而达到降低Cache功耗的目的。该机制使用Simics全系统模拟平台模拟多核处理器,并用SpecOMP测试集测试了系统的性能和功耗。与传统的Cache(Conventional L2Cache,C-L2)相比,其IPC提高了9.27%,功耗降低了10.95%。     

低熔封接微晶玻璃无铅化的最新研究进展及其发展趋势

低熔封接微晶玻璃是一种先进的焊接材料，由于其具有低的熔化温度和封接温度，优良的机械强度和化学稳定性，而在很多领域中得到广泛的应用，实现了玻璃、陶瓷、金属、半导体间的相互封接。综述了无铅低熔封接微晶玻璃的研究现状，展望了无铅低熔封接微晶玻璃今后的研究发展方向。     

煤焦小型氮肥厂采用离心压缩机联产4万吨/年低压甲醇设计

小氮肥厂采用离心压缩机对合成氨进行技术改造,联产4万吨/年低压法经济型甲醇,是煤化工C_1化学产品的发展方向。     

铝锆炭滑板在浇铸钙处理钢时的化学侵蚀

利用扫描电镜对抗钙处理钢液侵蚀试验后的铝锆炭残样进行了显微结构观察 ,并分析了铝锆炭滑板在钙处理钢液中的化学侵蚀机理。结果表明 :高温下 ,钙处理钢液中的Ca及CaO会与滑板中的Al2 O3 、SiO2 发生反应 ,生成低熔点的 12CaO·7SiO2 (1392℃ )和 2CaO·SiO2 ·Al2 O3 (15 39℃ )等物质 ,这些低熔物被钢水冲刷掉 ,使得滑板表层的Al2O3 和SiO2 含量迅速降低 ,从而导致了滑板的损毁。     

一种实用直流放大器的设计

本文设计的直流放大器由直流放大模块和测试模块两部分组成。在直流放大模块中设计了稳压电源和混有200mV串模工频干扰的直流信号发生器;测试模块用来检测直流放大器的直流电压增益、输入阻抗、共模抑制比等参数。实验数据表明各性能参数都满足要求。