银带熔体冲孔模设计

介绍了银带熔体冲孔模和手工送料机构,分析了模具关键零件的设计和制造,提高了生产效率。     

碳热还原协同溶胶-凝胶法合成纳米ZrB2粉末

利用ZrO2-B2O3-C反应体系碳热还原的基本原理,分别使用正丙醇锆(Zr(OC3H7)4)、硼酸(H3BO3)和蔗糖(C12H22O11)为原料,采用溶胶-凝胶-碳热还原法合成了二硼化锆(ZrB2)纳米粉末。我们首先使用络合剂醋酸(AcOH)修饰Zr(OC3H7)4,以防止Zr(OC3H7)4的快速水解;其次,选用蔗糖作为碳源,是考虑到蔗糖热解时可以完全分解为碳,这样可以准确计算热解过程碳的生成量。此外,研究了凝胶温度对ZrB2纳米粉末形貌的影响。结果表明:当起始原料B/Zr(mol.)=2.3、热解温度为1 550℃时,通过碳热还原协同溶胶-凝胶法成功合成了单相ZrB2纳米粉末;当凝胶温度分别为65、75和85℃时,ZrB2纳米粉末形貌从球状演变为链状,最后生长为棒状,生长机理为定向吸附。     

复合纳米材料对混凝土动态力学性能的影响

制备了掺量为0.2%(以水泥质量为基准)的纳米Fe₂O₃(NF)、复掺纳米Fe₂O₃和纳米CaCO₃ 2种纳米材料(NFC)以及复掺纳米Fe₂O₃、纳米CaCO₃和纳米SiO₂ 3种纳米材料(NFCS)的混凝土,之后采用直径100 mm分离式霍普金森压杆(SHPB)试验装置测试了养护龄期为28 d的3种混凝土在不同平均应变率等级下的动力特性并与普通混凝土(PC)进行对比研究。结果表明:准静态载荷下,复合纳米材料的掺入可有效调高混凝土的抗压强度;冲击载荷作用下,中低水平平均应变率时, NFC动态抗压强度最高, 80 s-1时NFC比PC高31.6%,高水平平均应变率下NF动态抗压强度具有优势,在125 s-1时, NF比PC高16%;NF在冲击载荷作用下峰值应变具有显著优势,具有良好的变形性能;以比能量吸收作为韧性评价指标,在平均应变率为75 s-1和125 s-1时, NF比PC增幅达到66.6%和75.7%。通过SEM照片分析,纳米Fe₂O₃颗粒增大了水泥石密实度,进而改善了NF的强度和韧性;由压汞试验分析,纳米CaCO₃颗粒在混凝土中,改善了水泥石孔隙结构。      

Water‐Dispersible,pH‐Stable and Highly‐Luminescent Organic Dye Nanoparticles with Amplified Emissions for In Vitro and In Vivo Bioimaging

A new strategy is presented for using doped small‐molecule organic nanoparticles (NPs) to achieve high‐performance fluorescent probes with strong brightness, large Stokes shifts and tunable emissions for in vitro and in vivo imaging. The host organic NPs are used not only as carriers to encapsulate different doped dyes, but also as fluorescence resonance energy transfer donors to couple with the doped dyes (as acceptors) to achieve multicolor luminescence with amplified emissions (AE). The resulting optimum green emitting NPs show high brightness with quantum yield (QY) of up to 45% and AE of 12 times; and the red emitting NPs show QY of 14% and AE of 10 times. These highly‐luminescent doped NPs can be further surface modified with poly(maleic anhydride‐alt‐1‐octadecene)‐polyethylene glycol (C18PMH‐PEG), endowing them with excellent water dispersibility and robust stability in various bio‐environments covering wide pH values from 2 to 10. In this study, cytotoxicity studies and folic acid targeted cellular imaging of these multicolor probes are carried out to demonstrate their potential for in vitro imaging. On this basis, applications of the NP probes in in vivo and ex vivo imaging are also investigated. Intense fluorescent signals of the doped NPs are distinctly, selectively and spatially resolved in tumor sites with high sensitivity, due to the preferential accumulation of the NPs in tumor sites through the passive enhanced permeability and retention effect. The results clearly indicate that these doped NPs are promising fluorescent probes for biomedical applications.     

爆轰法合成纳米TiO_2及其光催化性能

采用黑索金为可爆药剂,用爆轰法制备出了类球形混晶纳米TiO2粉体,并对合成的纳米TiO2粉末进行了表征。以甲基橙为研究对象,紫外灯为光源,研究了甲基橙初始浓度、纳米TiO2用量、甲基橙溶液初始pH值、超声分散和光照时间对甲基橙降解率的影响。研究表明,所制备的纳米TiO2为锐钛矿、板钛矿和金红石组成的混晶体,平均粒度约为18nm。在氧化钛浓度固定的条件下,甲基橙溶液初始浓度越高降解率越低。随着氧化钛加入量的增加,甲基橙溶液的降解率先增大后减小,而氧化钛的加入量超过40.0mg/L后,甲基橙溶液的降解率又呈升高的趋势。超声波分散的纳米氧化钛的表观反应速率明显高于未经超声波分散的氧化钛的表观反应速率。随着光催化时间的延长,光转化率逐渐升高。     

纳米银粒子/有机溶剂的界面作用、分散性及光学性能

用微乳液法制备了不同粒径的表面改性的纳米银粒子,并用ＥＳＲ、ＴＥＭ和紫外／可见吸收光谱研究了改性纳米银粒子／有机溶剂体系的界面作用、分散性和光学性能。结果表明：改性的纳米银粒子有一系列表面顺磁局域态,其ＥＳＲ谱参数与粒径的关系不符合Ｋａｗａｂａｔａ理论预测：氯仿与粒子有强烈的相互作用,粒子越小作用越强,且越易分散;氯仿作为粒子的良分散剂和高分子的良溶剂,可用于溶液共混工艺制备纳米银／高聚物复合材料。     

无机非金属纳米微粒的制备方法

本文简要介绍了固相法、液相法及气相法制备无机非金属纳米微粒的方法原理、研究现状及发展前景     

Ultrasound‒Mediated Synthesis of High‒Molecular Weight Polystyrene‒Grafted Silver Nanoparticles by Facile Ligand Exchange Reactions in Suspension

Ultrasound mediated facile ligand exchange method in suspension for the formation of polystyrene?grafted silver nanoparticles is reported. Amazingly, this method allows even grafting of very high molecular weight polystyrenes (up to 217 200 g mol^?1) having a single terminal thiol group at the chain end. Detailed studies are carried out to gain insights in the role of molecular weight of the ligands and the mechanism of the ligand exchange reactions. Key factors are determined to be the droplet formation by ultrasonification and low silver content, which enhances the availability of the terminal thiol end group significantly. The extraordinary compatibility of the ligand exchange method in particular regarding high molecular weights is attributed to hydrophilic orientation of the terminal thiol groups at the liquid?liquid interphase. This is proved conclusively by using an in situ method as a reference approach in which agglomeration occurs at considerably lower molecular weights due to the absence of preferred end group orientation within the polymer coil. In homogeneous phase only the chain length is found to be the crucial factor in stabilization of silver nanoparticles.