连退镀锡板的抗时效生产技术

阐述了抗时效镀锡产品的几种连续退火生产工艺,通过采用连续退火R-OA、无间隙原子化处理以及材料晶粒尺寸控制的方法之一可以有效地减缓或消除材料时效的发生,从而可能避免材料的起棱或滑移线现象的产生。     

Enhancing piezoelectricity of PLZT ceramics by bismuth stearate coating via water-soluble defatted powder injection molding

Lead zirconate titanate-based piezoelectric ceramics (Pb_0·91La_0·06(Zr_0·58Ti_0.42)_0.975Nb_0·02O₃, PLZT) were prepared by water-soluble defatted powder injection molding using bismuth stearate as surfactant. The effects of bismuth stearate surfactant amount on the feed viscosity, water degreasing rate and electrical properties were studied. The results showed that the bismuth stearate coating reduces agglomeration between the PLZT powders and decreases the viscosity of the feed. During sintering, bismuth stearate is decomposed into bismuth oxide, which acts as sintering aid to increase the density of the sintered bismuth stearate-coated PLZT ceramics. Bi³⁺ dissolves into the perovskite crystal lattice, which increases the tetragonality factor and the content of tetragonal phase, and improves the dielectric, ferroelectric and piezoelectric properties of the bismuth stearate-coated PLZT ceramics. This study provides a novel modification method for the production of injection molded ceramics using a water-soluble binder system.     

药用卤化丁基胶塞溶血试验

目的：研究药用丁基胶塞的溶血性能。方法：采用紫外分光光度法测定溶血率。结果溶血率均低于5%。结论：药用丁基胶塞在急性溶血方面,具有良好的生物安全性。     

镧掺杂PMN-PT陶瓷在准同型相界处的相组成调控

采用两步预烧工艺制备Pb_{0.962 5}La_0.025(Mg_1/3Nb_2/3)_1-zTi_zO₃(z=0.28、0.29、0.30、0.31)陶瓷,其准同型相界(MPB)的化学组成位于PbTiO₃含量为0.29 mol和0.30 mol附近。选取准同型相界两侧的化学组成,制备四方晶相Pb(Mg_1/3Nb_2/3)_0.66Ti_0.34O₃和三方晶相Pb_1-1.5xLa_x(Mg_1/3Nb_2/3)_1-yTi_yO₃(x=0.083 3~0.041 7,y=0.206 7~0.273 3)陶瓷粉体。将两种晶相粉体按照设计比例(三方晶相摩尔分数w=0.3、0.4、0.5、0.6)混合,干压成型,烧结成化学组成相同、晶相占比不同的Pb_{0.962 5}La_0.025(Mg_1/3Nb_2/3)_0.70Ti_0.30O₃陶瓷。研究了晶相组成对陶瓷压电性能、介电性能、铁电性能的影响。结果表明,高温烧结后,陶瓷中的三方晶相和四方晶相占比与配料比基本一致。当w=0.5时,1 250 ℃烧结陶瓷中三方晶相与四方晶相含量占比分别为0.47、0.53,晶粒平均尺寸为(5.24±0.23) μm,相对密度为96.76%。陶瓷的压电应变常数d₃₃、径向机电转换系数k_p、厚度机电转换系数k_t、相对介电常数ε_r、剩余极化强度P_r和场致应变系数S(1 Hz、3.5 kV/mm)分别为1 014 pC/N、0.67、0.64、10 955、24 μC/cm²和0.21%。该方法可人为调控化学组成位于准同型相界的陶瓷的晶相占比。     

广州电网复杂故障阻隔策略研究

广州电网作为特大型中心城市电网对供电可靠性要求很高。梳理了可能导致广州电网大面积停电的三类风险并提出了应对策略。针对多回直流同时闭锁失步解列装置拒动导致系统失步的风险,提出了主动解列片区电网的措施;针对500 k V变电站全停故障下孤网频率失稳风险提出了联切负荷策略。针对线路三相短路主保护拒动局部电网失稳的风险提出了解列机组的措施。基于实际电网的算例验证了所提策略的有效性。     

螺杆压缩机进排气消声装置设计

重点介绍螺杆压缩机进排气消声装置的设计,针对某化工装置用螺杆压缩机的特点,设计了一套进排气消声装置,包括进气消声器、稳流器、出口膨胀节和排气消声器,其中进气消声器安装在压缩机进口,用于降低压缩机的进气噪声,压缩机排气口分别连接稳流器、出口膨胀节和排气消声器,用于降低压缩机出口的气流脉动和排气噪声,同时隔离压缩机的振动传递。进排气消声装置的设计不仅要满足声学功能,还要按照压力容器的要求进行设计,文章采用有限元方法对进排气消声器进行了消声性能仿真分析,从仿真结果来看,该消声装置能够有效地降低压缩机的进排气噪声。     

综合电压频率动态交互影响的自动减负荷控制新方法

基于单一的频率量测或单一的电压量测而独立动作的传统低频低压减负荷控制装置,未计及受扰系统电压与频率之间的实时动态交互,难以完全适应系统初始工况、负荷特性或扰动形式的变化,某些情况下可能出现严重的欠控制或过控制。文中提出一种在装置的实时控制算法中计及电压与频率动态交互影响的自动减负荷控制方法,其核心是测量装置安装节点的电压、频率以及负荷有功功率,并计及与当前系统初始工况、负荷特性或所发生扰动形式相对应的频率电压相关系数,实时计算综合状态量以触发自动减负荷控制装置的分轮次动作。对实际电网的时域仿真结果表明,该方法可较好地适应系统初始工况、负荷特性或扰动形式的变化。     

Flavonols of lotus (<Emphasis Type="Italic">Nelumbo nucifera,</Emphasis> Gaertn.) seed epicarp and their antioxidant potential

Large amounts of fresh seed epicarp of Nelumbo nucifera Gaertn. (FSENN) are discarded in China without any utilization. The aim of this study was to identify the flavonols found in a fraction of an extract of FSENN, and to measure their levels and investigate antioxidant properties. Glycosylated flavonols in fraction 2 (Fr2) from the extract of FSENN and their aglycones were identified by HPLC-ESI–MS² (negative mode), and six glycosylated and one aglycone flavonols in Fr2 were found. We also quantified flavonol aglycones (myricetin, quercetin, kaempferol and isorhamnetin) using HPLC method. The result showed that the quercetin content (10.2 mg/g of dry fraction) was higher than that of other aglycones. Antioxidant properties of Fr2 were evaluated in vitro by a number of methods including 2, 2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging, the β-carotene bleaching method, and hydroxyl radical and hydrogen peroxide scavenging ability using the chemiluminescence method. This antioxidant potential in terms of IC₅₀ values was 5.48, 40 ± 0.14 and 0.62 ± 0.05 μg (dry Fr2)/mL on DPPH radicals, hydroxyl radicals and hydrogen peroxide, respectively. The Fr2 also exhibited antioxidant property in the β-carotene bleaching assay. In total, it possesses high levels of flavonol compounds with high antioxidant potential, and it is beneficial for the treatment or prevention of a variety of diseases and has nutraceutical potential.     

5000 t/d窑尾PA总线仪表与FW239-DP模块通讯的应用

1窑尾仪表及其通讯介绍 随着水泥工业自动化水平的不断提高。PA总线仪表由于计量精确,抗干扰能力强,输出信息量大,安装维护简单．能在中控工程师站上直接调校．便于故障分析及设备的管理等特点,得到了越来越广泛的应用。山东东华水泥二期工程5000t／d熟料生产线首次在水泥行业实现了PA总线仪表通过DP—PA总线方式与国产FW239-DP模块通讯。为国产化PA总线设备的应用取得了有益的经验。     

Physicochemical properties and structure of starches from Chinese rice cultivars

Starches from 10 different non-waxy rice cultivars in China were isolated and investigated for their physicochemical properties including the swelling power, solubility, syneresis, thermal, rheological and textural properties, and structure. The range of amylose content in 10 rice starches was between 18.1 and 31.6%. The branch chain length distribution of amylopectin revealed that the proportions of short (DP6–11), medium (DP12–17), and longer chains (DP18–23) were 4.6–11.1%, 47.0–51.6% and 25.3–31.8%, respectively. The relationships between different properties of rice starches were determined using Pearson correlation analysis. Amylose content was negatively correlated to swelling power (r = ?0.632, p ≤ 0.05) and positively correlated to gel hardness (r = 0.776, p ≤ 0.01). The percentage of short chains (DP6–11) was negatively related to the transition temperatures (T_o, T_p and T_c), T_oG′ and T_G′max, while the percentage of medium chains (DP12–23) was positively related. Various branch chain length amylopectins played different roles in rheological behavior of starch dispersions. The percentage of short chains (DP6–11) was positively correlated to G′ and G″(r = 0.832 and r = 0.775, respectively, p ≤ 0.01), and negatively correlated to tanδ peak (r = ?0.717, p ≤ 0.05). However, the percentage of longer chains (DP18–23) showed a negative relation with G′ and G″ (r = ?0.794, p ≤ 0.01; r = ?0.741, p ≤ 0.05), and a positive relation with tanδ peak (r = 0.668, p ≤ 0.05).