脉冲注入法和单端故障行波法相结合的直流输电系统接地极线路故障测距

分析了直流输电系统在单极运行方式下,接地极线路故障暂态行波和外部注入脉冲信号在接地极线路上的传播过程。以此为基础,提出一种将脉冲注入法和单端故障行波法相结合的接地极线路故障测距方案。首先通过在换流站直流中性母线处监测接地极线路故障暂态行波识别线路是否发生故障,在线路故障暂态过程结束后从中性母线向线路注入脉冲信号。根据脉冲注入法得到初步测距结果,并以此确定故障区段。然后,根据确定的故障区段,进一步用单端故障行波法再次获得测距结果。最后,对两次测距结果取平均值,作为最终测距结果。以PSCAD/EMTDC为仿真平台,搭建了直流输电系统在单极运行方式下的接地极线路故障测距仿真模型。并借助Matlab对仿真波形数据进行分析,表明所提出的接地极线路故障测距方案是可行的。     

地黄饮超声提取工艺的研究

目的 优选地黄饮最优超声法提取(Ultrasonic extraction)工艺.方法 以地黄饮干固物及松果菊苷、毛蕊花糖苷和马钱苷的含量为考察指标,以乙醇为提取溶剂,以Ultrasonic extraction中的乙醇浓度、物料溶液比、提取时间、提取温度为因素,采用正交实验通过直观分析确定最优工艺.结果 影响地黄饮U...     

Polydopamine hydrophilic modification of polypropylene separator for lithium ion battery

The modified polypropylene (PP) separators with self‐polymerization of dopamine on the surfaces are prepared by a simple solution‐immersion method to improve the interfacial hydrophilic and discharge performance. The contact angle test and the liquid electrolyte uptake capacity test results show that the wettability and the electrolyte‐retention ability of polydopamine‐modified separator are improved significantly. The robust and thin polydopamine layer on the surface also enhances thermal performance and tensile strength of the modified PP separator certified by DSC and tensile strength tests. The ionic conductivity of the modified PP separator is up to 3.08 mS·cm^?1, ～2.5 times of the bare separator. Good discharge capacity retention and C‐rate discharge performance are demonstrated by a 2025 coin half‐cell with the liquid electrolyte‐soaked polydopamine modified PP separator sandwiched between lithium metal anode and LiFePO₄ cathode. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40543.     

探究PVC/PNBR共混胶力学性能的影响因素

采用简单机械共混法,初步探究了影响聚氯乙烯(PVC)/粉末丁腈胶(PNBR)共混胶力学性能的主要因素,包括塑化温度、塑化时间、增塑剂品种及用量、PNBR用量等。结果表明,塑化温度170±3℃、混炼5min时拉伸强度最大,拉断永久变形最小;随着增塑剂用量的增加,拉伸强度下降,拉断永久变形先降低后增加,选用80份DBP作为增塑剂时效果最好;PNBR的用量为30份时,PVC/PNBR共混胶的拉伸强度和拉断永久变形的综合性能较好。     

PVC基阻尼涂料的制备及其流变性能

以聚氯乙烯（PVC）为基体，对苯二甲酸二辛酯（DOTP）为增塑剂，与无机填料CaCO3、钙锌热稳定剂、乳化剂OP-10、润滑剂液体石蜡等复合改性制备PVC基阻尼材料，采用动态流变仪DHR、动态热机械分析仪DMA、扫描电镜SEM等对试样的性能和形态进行表征。运用正交设计探究各组分对性能的影响规律，结果表明，填料CaCO3和增塑剂DOTP比例对其阻尼性能影响最显著；当PVC: CaCO3: DOTP: OP-10比重为45: 33: 22: 2时，25℃时频率0.01～150 Hz范围内，tan δ最大值从0.497提高到0.604；剪切速率0.1 s-1时表观黏度为3738 Pa·s，剪切速率150 s-1时表观黏度为2.19 Pa·s，具有优异的抗流挂性与稳定性。通过LASD形态分析构建微观聚集态模型，提出刚性填料团聚-解团聚和聚合物微球变形对流变性能的作用机理，为LASD的持续研究提供技术思路和理论基础。     

Hydroxyl Groups Promoted Ag Dispersion and Excellent Performance of Ag/Al2O3 Catalyst for HCHO Oxidation

Catalysis Letters - Hydroxyl groups are considered as anchoring sites for active components on catalysts. Guided by this viewpoint, 4 wt. % Ag/Al2O3 catalyst derived from Boehmite (AlOOH) was...     

Mangiferin Facilitates Islet Regeneration and β-Cell Proliferation through Upregulation of Cell Cycle and β-Cell Regeneration Regulators

Mangiferin, a xanthonoid found in plants including mangoes and iris unguicularis, was suggested in previous studies to have anti-hyperglycemic function, though the underlying mechanisms are largely unknown. This study was designed to determine the therapeutic effect of mangiferin by the regeneration of β-cells in mice following 70% partial pancreatectomy (PPx), and to explore the mechanisms of mangiferin-induced β-cell proliferation. For this purpose, adult C57BL/6J mice after 7–14 days post-PPx, or a sham operation were subjected to mangiferin (30 and 90 mg/kg body weight) or control solvent injection. Mangiferin-treated mice exhibited an improved glycemia and glucose tolerance, increased serum insulin levels, enhanced β-cell hyperplasia, elevated β-cell proliferation and reduced β-cell apoptosis. Further dissection at the molecular level showed several key regulators of cell cycle, such as cyclin D1, D2 and cyclin-dependent kinase 4 (Cdk4) were significantly up-regulated in mangiferin-treated mice. In addition, critical genes related to β-cell regeneration, such as pancreatic and duodenal homeobox 1 (PDX-1), neurogenin 3 (Ngn3), glucose transporter 2 (GLUT-2), Forkhead box protein O1 (Foxo-1), and glucokinase (GCK), were found to be promoted by mangiferin at both the mRNA and protein expression level. Thus, mangiferin administration markedly facilitates β-cell proliferation and islet regeneration, likely by regulating essential genes in the cell cycle and the process of islet regeneration. These effects therefore suggest that mangiferin bears a therapeutic potential in preventing and/or treating the diabetes.     

Rapid and large‐scale separation of magnetic nanoparticles by low‐field permanent magnet with gas assistance

Bubbles can be used to greatly improve the speed of magnetic separation (MS) and overcome the limitation of magnetic force on the capture distance, making low‐field MS highly efficient and easily scalable. This novel method leads to the development of a medium‐free continuous gas‐assisted magnetic separator on small pilot scale using low‐field permanent magnet. This separator is demonstrated highly efficient for recovery of proteins‐loaded magnetic nanoparticles from large volume biosuspension. © 2014 American Institute of Chemical Engineers AIChE J, 60: 3101–3106, 2014     

影响双螺杆冰机稳定运行的原因分析及解决办法

阐述了双螺杆式制冷机的工作原理,对其主要工作部件进行了研究,分析了影响冰机稳定运行的原因.结果表明：检查清理热力膨胀阀,防止膨胀阀堵塞;定期清理换热器（冷凝器、油冷却器）,优化换热效果;更换干燥器,清除系统内进入空气和少量的水.通过以上措施可有效地降低双螺杆式制冷机的故障.     

Preparation of a hydrophobically enhanced antifouling isotactic polypropylene/silicone dioxide flat‐sheet membrane via thermally induced phase separation for vacuum membrane distillation

Isotactic polypropylene (iPP) hydrophobic flat‐sheet membranes were fabricated for use in vacuum membrane distillation (VMD) through a thermally induced phase‐separation process with dispersing hydrophobically modified SiO₂ nanoparticles in the casting solution to achieve a higher hydrophobicity and to sustain a stable flux in VMD. The contact angle (CA) measurements indicated that the incorporation of nano‐SiO₂ into a casting solution mixture containing 20 wt % iPP had a 20.9% higher CA relative to that of SiO₂‐free membranes. The addition of nano‐SiO₂ also induced morphological changes in the membrane structure, including changes in the pore size distribution, porosity, and suppression of macrovoids. The pore size distribution of the iPP–SiO₂ membranes became narrower compared with that of the SiO₂‐free membranes, and the porosity also improved from 35.45 to 59.75% with SiO₂ addition. The average pore size and maximum pore size of the iPP–SiO₂ membranes both decreased. The ability of the membranes to concentrate an astragalus aqueous solution (a type of traditional Chinese medicine) with VMD was investigated. The surface hydrophobicity and antifouling performance of the iPP–SiO₂ membranes improved with nano‐SiO₂ addition to the membrane casting solution. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42615.