改性淀粉用作混凝土减水剂的研究进展

综述了混凝土减水剂的发展状况和目前存在的问题,介绍了淀粉的结构、改性淀粉如羧甲基淀粉、磺化淀粉和淀粉丁二酸单酯等的合成方法,以及改性淀粉用作混凝土减水剂的分散机理。     

我国乙丙橡胶的供需现状及发展前景

<正>乙丙橡胶(EPR)是由乙烯和丙烯为主要单体共聚而得的聚合物,依据分子链中单体组成的不同,有二元乙丙橡胶(EPM)和三元乙丙橡胶(EPDM)之分,后者是由乙烯、丙烯与少量非共扼二烯烃单体共聚而得到的三元共聚物。由于乙丙橡胶分子链具有高度的饱和性,使得其具有优异的耐臭氧性、耐老化     

低氢酯比条件下苯甲酸甲酯加氢制苯甲醛动力学

以4%Li3%Cr修饰的25%ZnO/MnO/βAl_2O_3为催化剂,采用固定床反应器,在消除内外扩散的情况下,考察了反应温度和氢酯比对苯甲酸甲酯(MB)加氢制备苯甲醛的影响,并建立苯甲酸甲酯加氢反应的本征动力学模型。以MB转化率和苯甲醛选择性的模型计算值与实验值的残差平方和最小为目标函数,采用Matlab软件中的非线性最小二乘法对实验数据进行拟合,估算出该模型的参数,并对模型的显著性进行了检验。结果表明,动力学模型具有合理性,能较好地描述苯甲酸甲酯加氢反应。     

聚丙烯/亚麻纤维复合材料的成型工艺及力学性能研究

选取聚丙烯(PP)纤维为基体材料,亚麻纤维为增强材料。运用正交设计法,探讨了PP/亚麻纤维复合材料的模压成型工艺。研究分析了两种纤维的质量比、模压温度、热压保温时间对复合材料力学性能的影响。结果表明,两种纤维的质量比为50:50、模压温度为180℃、热压保温时间为60min时,PP/亚麻纤维复合材料的力学性能最佳。     

Ultrafine particles from diesel vehicle emissions at different driving cycles induce differential vascular pro-inflammatory responses: Implication of chemical components and NF-κB signaling

Background

Nanometer silicon dioxide (nano-SiO₂) has a wide variety of applications in material sciences, engineering and medicine; however, the potential cell biological and proteomic effects of nano-SiO₂ exposure and the toxic mechanisms remain far from clear.

Results

Here, we evaluated the effects of amorphous nano-SiO₂ (15-nm, 30-nm SiO₂). on cellular viability, cell cycle, apoptosis and protein expression in HaCaT cells by using biochemical and morphological analysis, two-dimensional differential gel electrophoresis (2D-DIGE) as well as mass spectrometry (MS). We found that the cellular viability of HaCaT cells was significantly decreased in a dose-dependent manner after the treatment of nano-SiO₂ and micro-sized SiO₂ particles. The IC₅₀ value (50% concentration of inhibition) was associated with the size of SiO₂ particles. Exposure to nano-SiO₂ and micro-sized SiO₂ particles also induced apoptosis in HaCaT cells in a dose-dependent manner. Furthermore, the smaller SiO₂ particle size was, the higher apoptotic rate the cells underwent. The proteomic analysis revealed that 16 differentially expressed proteins were induced by SiO₂ exposure, and that the expression levels of the differentially expressed proteins were associated with the particle size. The 16 proteins were identified by MALDI-TOF-TOF-MS analysis and could be classified into 5 categories according to their functions. They include oxidative stress-associated proteins; cytoskeleton-associated proteins; molecular chaperones; energy metabolism-associated proteins; apoptosis and tumor-associated proteins.

Conclusions

These results showed that nano-SiO₂ exposure exerted toxic effects and altered protein expression in HaCaT cells. The data indicated the alterations of the proteins, such as the proteins associated with oxidative stress and apoptosis, could be involved in the toxic mechanisms of nano-SiO₂ exposure.     

废钌/氧化铝催化剂中钌的回收研究

采用"碱熔—氧化蒸馏"的方法对钌/氧化铝催化剂中钌的回收进行研究。分别讨论了碱熔剂、碱熔温度、碱熔时间及氧化蒸馏时间等对钌氧化铝催化剂中钌回收率的影响。实验表明,以KOH/KNO3作碱熔剂,650℃下反应2.5 h,NaC lO+H2SO4作氧化剂,80℃减压蒸馏1.5 h,得到三氯化钌盐酸溶液,经减压蒸馏至干涸得到β-RuC l3.3H2O晶体。钌/氧化铝催化剂中钌回收率可达到93%。     

低温快烧色料的研制

系统地阐述了用于生产建筑彩砂的低温快烧色料,简单介绍了彩砂的制备及特点,并对研制的系列色料的特点、性能作了简要阐述。     

针刺用炭布／网胎复合织物单层增厚及变形性分析

炭布／网胎复合织物是C／C复合材料针刺预制体的一种重要原料。本文研究了针刺后不同种类炭布／网胎复合织物的单层增厚及针刺变形性。单层增厚与针刺后复合织物的结构、织物的厚度均匀性和针刺密度有关。针刺后复合织物的结构为“销钉”结构,织物的厚度均匀性影响Z向纤维的引入量,针刺密度是影响单层增厚最为显著的因素。针刺密度为20针／cm^2时,预氧丝网胎复合织物的单层增厚小于0．2mm,增厚百分比在4％～25％之间;针刺密度为32针／cm^2时,炭纤维网胎复合织物的单层增厚在0．14mm-0．23mm之间,增厚百分比在16％～34％之间。不同种类炭布／网胎复合织物的整体变形性较为相似,针刺变形性与炭布的结构有关。     

13X沸石颗粒吸附剂制备及钙吸附的性能研究

向粉末状13X沸石中添加黏结剂、增孔剂、水等辅助物料,再经干燥、高温煅烧成型、破碎、筛分制得颗粒状吸附剂,并用于吸附溶液中的钙离子。对黏结剂进行筛选,研究了原料配比、煅烧温度、粒径、吸附时间等因素对颗粒状吸附剂在水溶液中的损失率和对钙离子吸附效果的影响。实验结果表明:以坡缕石黏土矿作黏结剂,在13X沸石、黏土、精煤粉的质量比为15∶4∶1、煅烧温度为650℃的条件下制得的颗粒状吸附剂性能最优,钙离子吸附量达到25.31 mg/g,损失率为1.98%。减小颗粒吸附剂粒径时吸附速率显著增大,延长吸附时间则吸附量增大,吸附120 min基本达到饱和。静态等温吸附过程与Langm iur吸附等温方程式相符。     

白炭黑湿法改性研究

采用3种硅烷偶联剂(KH-550,A-151,Si69)对白炭黑进行湿法表面改性,将改性后的白炭黑用于补强丁苯橡胶,测试补强胶料的力学性能,用于验证硅烷偶联剂对白炭黑的改性效果。实验结果证明,3种偶联剂均可实现对白炭黑的改性。得出了3种硅烷偶联剂对白炭黑进行湿法表面改性的最佳条件:1)以KH-550为改性剂,将其预先水解,改性剂用量为白炭黑质量的1%,改性温度为35℃,改性时间为25 min;2)以A-151为改性剂,将其预先水解,改性剂用量为白炭黑质量的1.5%,改性温度为65℃,改性时间为35 min;3)以Si69为改性剂,将其预先乳化,改性剂用量为白炭黑质量的1%,改性温度为55℃,改性时间为45 min。