聚丙烯成核剂研究进展

聚丙烯材料被越来越多的应用于汽车领域、工程塑料等,聚丙烯性能的优化也成为工业界和学术界研究的热点问题。聚丙烯因其良好的机械性能、加工性能、价格低廉而备受关注,但其低温脆性大、热变形温度低、易收缩等缺点也制约了该类材料的发展和在某些领域的应用。对聚丙烯的改性关键是对其分子链规整度、球晶尺寸的调控,成核剂改性是聚丙烯改性中相对简单易行的方法。聚丙烯成核剂种类繁多,各俱特色,本文在综述了聚丙烯成核剂的基础上提出了新型聚丙烯改性成核剂,即大分子成核剂,并展望了大分子成核剂的发展前景。     

高质量NaNdF4六方棱柱纳米棒的水热形貌控制合成及发光性质

采用水热法在温和的条件下合成了具有规则外形的六方棱柱状NaNdF₄纳米棒。X射线衍射（XRD）分析表明：产物为纯六方相NaNdF₄,场发射扫描电镜（SEM）分析表明产物形貌为棱柱状纳米棒,长约为550nm,棒的端部呈规则六边形,边长约为85nm。高分辨透射电子显微镜（HRTEM）和选区电子衍射（SD）显示所得样品为良好的单晶。NaNdF₄晶体的生长动力学过程表明：螯合剂（EDTA-Na₂）与稀土金属离子间的螯合作用受pH值影响,导致成核速度变化,进而影响NaNdF₄纳米晶的最终尺寸和形貌。室温下的NaNdF₄纳米棒的发光峰位于红外光范围（λ=892,1058,和1342nm）,其最强发射峰位于1058nm,对应于Nd³⁺的⁴F_3/2→⁴I_11/2f-f跃迁。     

In vitro Degradation and Biocompatibility of Ca-P Coated Magnesium Alloy

Calcium-phosphate compounds(Ca-P) coating was prepared on an Mg-Al alloy(AZ60). Biodegradation of Ca-P coated magnesium alloy was evaluated in simulated body fluid(SBF) by examining the changes in magnesium ion concentration and pH value, which indicated that the Ca-P coating on magnesium alloy strongly affected the corrosion of magnesium alloy. Osteoblast MC3T3-E1 cells were utilized to investigate the cellular cytocompatibility. The cytocompatibility was measured by carrying out a series of tests, such as cholecystokinin-octapeptide(CCK-8) test, alkaline phosphatase activity(ALP) test, cellular morphology of hematoxylin-eosin(HE) staining and the induction of apoptosis. It was found that the cell function showed better in the Ca-P coated Mg-alloy extract than in the uncoated magnesium alloy extract. In summary, the results indicate that the Ca-P coating can improve the corrosion resistance of magnesium alloy and elevate cellular proliferation and differentiation of osteoblast MC3T3-E1 cells.     

Ⅱ型TiO2/g-C3N4异质结的构筑促进高效光催化U(Ⅵ)还原

采用水热法将TiO₂纳米片修饰在中空管状g-C₃N₄上制备了TiO₂/g-C₃N₄(T-CN)复合催化剂。利用扫描电子显微镜(SEM)、X射线光电子能谱(XPS)、紫外可见漫反射光谱(UV-Vis DRS)和光电流响应等对其形貌、结构和光物理性能进行了表征。结果表明,TiO₂纳米片均匀地分散在中空管状g-C₃N₄表面,两者紧密结合形成异质结。TiO₂与g-C₃N₄的质量比为20%时制得的T-CN-20复合催化剂在60 min内对U (Ⅵ)的去除率为85.64%,是纯相g-C₃N₄的6.7倍。在10倍高浓度阳离子共存条件下的去除率仍大于69.8%,且具有优良的结构稳定性。对光催化产物分析可知,T-CN将U (Ⅵ)还原为难溶的U (Ⅳ)(63.68%)以去除铀,可有效解决含铀核废水中的U (Ⅵ)污染问题。根据能带理论分析,提出了复合催化剂异质结的Ⅱ型光催化机理。     

新型7-乙基-10-羟基喜树碱衍生物的合成及其体外抗肿瘤活性

以乙二醇为起始原料,依次经亲核取代和点击反应合成了一种7-乙基-10-羟基喜树碱(SN38)的新型葡萄糖残基衍生物(FSY02),其结构经¹H NMR, ¹³C NMR和HR-MS(ESI)表征。采用四甲基偶氮唑盐比色法（MTT法）研究了FSY02对人非小细胞肺癌细胞(A549)、人肝癌细胞(HepG2)、人结直肠癌细胞(SW-480)、人宫颈癌细胞(Hela)和人乳腺癌细胞(MDA-MB-231)的生长抑制作用。并采用Hoechst 33258染色和Western blot技术对给药后的结肠癌细胞凋亡情况和相关凋亡信号通路Caspase 3、 Bax和Bcl-2蛋白的表达情况进行了检测。结果表明：FSY02具有广谱抗癌活性,IC₅₀=0.118~4.295 μmol·L^-1,优于对照组伊立替康(IC⁵⁰=14.330~65.353 μmol·L^-1)。 Hoechst 33258染色及Western blot检测结果显示：FSY02通过上调Caspase 3和Bax的表达,下调凋亡抑制蛋白Bcl-2的表达诱导细胞凋亡。     

Ca0.8-2x(YbxTb0.1Na0.1+x)2xWO4近红外下转换荧光粉水热合成及发光性质

一种在近红外光谱(NIR)区域高效的量子剪裁现象已在Ca0.8-2x(Ybx Tb0.1Na0.1+x)2x WO4(x=0～0.2)荧光粉中得到证实,该量子剪裁通过吸收紫外线光子发射近红外光子,能量传递包括两个协同过程,分别是WO42-基团到Yb3+离子和WO42-基团到Tb3+离子再到Yb3+离子,Yb3+离子的掺杂浓度对荧光粉在可见光和近红外光谱的发光,荧光寿命和量子效率的影响已进行了详细的研究。经计算,量子效率最大达到135.7%。铽与镱共掺钨酸钙的近红外量子剪裁,通过吸收太阳光谱的1个紫外光子到2个1 000 nm光子(2倍光子数增加)的下转化机制实现高效率硅太阳能电池的途径。     

高分辨热裂解气相色谱/质谱法快速定性检测农产品中的单增李斯特菌

要在高分辨率热裂解气相色谱/质谱(HRPGC/MS)系统中采用选择离子检测法(SIM),建立了准确可靠、灵敏度高、快速简便的检测农产品中单增李斯特菌的方法.裂解条件:起始温度50℃;升温速率20℃/min,裂解室温度230℃;裂解温度650℃;裂解时间为10 s.气相色谱条件:载气为氦气;恒定流速0.9 mL/min;DB-WAXTER毛细管色谱柱;起始温度45℃;保持4min,以6℃/min的速率上升到100℃,然后以10℃/min上升到200℃,接着以12℃/min上升至250℃,并保持25 min.分流比为50∶1.EI离子源.选择色谱保留时间19.056 min,鉴别离子m/z 54,98,用于SIM检测.通过对单增李斯特菌、2种空白农产品和2种不同农产品污染单增李斯特菌的样品检测结果表明,HRPGC/MS方法检测不同黄瓜、牛肉农产品中单增李斯特菌,均能得到很好的反映.本方法分析时间缩短,用保留时间、质谱同时定性,消除了不同种类农产品杂质的干扰,结果准确可靠,选择性和重复性好,适于快速检测农产品中的单增李斯特菌.     

近红外光谱法用于纯化过程中鞣花酸含量的监控

采用近红外光谱技术结合遗传算法优化的小波神经网络,对大孔树脂纯化过程中橄榄果中的鞣花酸含量进行监控。通过小波变换对光谱进行去噪、压缩,作为人工神经网络的输入,同时以遗传算法优化神经网络的权值与阈值,并与常用的偏最小二乘(PLS)线性模型的建模效果进行比较。实验结果表明,两者都能够较准确的预测鞣花酸的含量,相对而言,人工神经网络(ANN)效果较好。     

Reaction Ergodography and Transition State Analyses of the Addition of AIH_3 to Acetylene

The present paper covers the reaction ergodography for the addition of AlH3 to acetylene investigated by ab initio calculation with RHF/3-21G basis set. The changes in some physical properties along the reaction path (IRC) are presented. The formations of FMOs of the transition state have been analyzed according to the Fukui' s method. On the basis of the perturbation theory and Wolfsborg Helmholtz formula, we calculated the FMO' s energy orders of TS and its formation that shows the HOMO of TS consists of LUMO, HOMO of AlH3 and HOMO of HCCH.     

Transpiration-inspired Capillary for Synchronous Synthesis and Patterning of Silver Nanoparticles

Traditional synthesis strategy of nanomaterials with complicated process and high cost limits their applications. Here, we propose a facile process for the synchronous synthesis and patterning of silver nanoparticles(Ag NPs) through the self-driven microchannel reactor with the capillary effect inspired by transpiration. The evaporation contributes to capillary and accumulation effects in the microchannels. The silver reactant-containing droplets can be spontaneously divided and distributed in multiple microchannels during the whole fabrication process by the capillary effect. The newly formed Ag NPs at the gas-liquid interface can be assembled on both sides of the microchannels by the accumulation effect. The capillary effect decreases the disturbances, which ensures the uniformity of the patterning. By the combination of microchannels with different widths, various Ag NPs-assembled patterns with stable electrical properties are achieved. This efficient strategy with a simple fabrication procedure is towards the technological engineering of nanoscale architected materials.