脉冲电化学法制备“海绵状”聚苯胺

采用脉冲电化学法,以盐酸为掺杂剂,在ITO导电玻璃上电沉积制备"海绵状"疏松结构的聚苯胺(PANI)材料,通过SEM、FTIR以及UV-vis对合成的产物进行表征.结果表明:该疏松结构的材料主要是由直径60 nm左右的PANI纳米纤维组成,其表面有很多50~200 nm的PANI纳米颗粒,最后得到的产物是掺杂态EB结构的PANI.文中对这种结构产物的形成机理进行了初步探讨.     

Preparation and Characterization of Carbon Coated Silicon Nanoparticle as Anode Material for Li-ion Batteries

Silicon has been regarded as one of the most promising anode materials for Li-ion batteries. Its theoretical capacity （4 000 mAh/g） is much higher than that of the commercialized graphite （372 mAh/g）. However, the cycle performance of silicon is poor due to the severe volume expansion and shrinkage during Li^＋ insertion/extraction which results in pulverization of Si particles, eventually losing its Li^＋ storage ability. To solve this problem, nanosized Si particles were utilized and achieved a partial improvement by reducing the absolute volume change. Nevertheless, a new problem was encountered with nanosized material that small Si particles were aggregated to be larger one during Li^＋ insertion/extraction, and then pulverized again. In this work, we have succeeded to improve the cycle performance of nanosized Si particles by synthesis of carbon coated silicon nanopartiele.     

纳米银颗粒增强聚合酶链式反应长片段DNA反复扩增的特异性

基因操作者经常需要把数量稀少的DNA样品进行反复扩增以供进一步研究之用.在反复扩增过程中,上一次扩增产物当作下一次扩增的模板使用.对于较短的DNA片段(几百个碱基),一般反复扩增不会遇到特别的困难;但是较长DNA片段(几千到几万个碱基)的反复扩增一般会极大地降低聚合酶链式反应(PCR)的特异性.实验中发现,当扩增较长片段基因时,在常规PCR热循环体系中添加粒径平均为70 nm的银颗粒,使反应体系纳米银颗粒浓度达到0.1～1.2μg/μL,可以在一定程度上保持PCR反复扩增反应的特异性.其机理之一可能是常规PCR反应体系在添加了纳米银颗粒后改善了溶液的导热性能.     

淀粉保护的银纳米粒子的合成及表征

用液相过程制备纳米银粒子.制备过程中淀粉作保护剂、柠檬酸钠作还原剂,得到了Ag纳米粒子.利用透射电子显微镜（TEM）和紫外-可见吸收（UV-Vis）光谱,对Ag纳米粒子的形貌、粒度及其分布进行了性能表征,结果表明：在所选择的实验条件下制备了形貌呈球形,颗粒分散较为均匀,粒度分布集中,且粒径大约在20 nm左右的银纳米粒子;并讨论了淀粉在一定的浓度范围内能有效地防止纳米银颗粒的团聚,其保护作用显著.     

反相乳液聚合制备多柔比星纳米粒

以抗癌药物多柔比星为模型药物,通过反相乳液聚合法制备了以聚乙烯吡咯烷酮为载体的多柔比星纳米颗粒,并用扫描电镜、激光粒度仪、红外光谱对其进行表征.激光粒度仪测试表明:在最佳制备条件下,纳米颗粒的平均粒径为18.8 nm,粒径分布为15~32 nm,与扫描电镜的结果基本吻合;红外光谱测试表明,制备的纳米颗粒由多柔比星和聚乙烯吡咯烷酮共同组成;体外释放研究表明,纳米粒子在体外释药缓慢.     

苯热法合成环境催化材料纳米氮化铁

采用苯热法合成环境催化材料纳米氮化铁。在高压反应釜内，无水FeCl3与Li3N在通氮气的苯溶液和450-500℃条件下反应30h，XRD结果表明主要产物为Fe4N，晶体的平均直径约为10nm。该反应条件容易控制。     

Influence of nanometric CeO2 coating on high temperature oxidation of Cr

Isothermal and cyclic oxidation behavior of chromium and its superficially applied nanometric CeO₂ samples were studied at 900℃ in air. Scanning electronic microscopy (SEM), transmission electronic microscopy (TEM) and high resolution electronic microscopy (HREM) were used to examine the morphology and micro-structure of oxide films. It was found that ceria addition greatly improved the anti-oxidation ability of Cr both in isothermal and cyclic oxidizing experiments. Acoustic emission (AE) technique was used in situ to monitor the cracking and spalling of oxide films, and AE signals were analyzed in time-domain and number-domain according to the related oxide fracture model. Laser Raman spectrometer was also used to study the stress status of oxide films formed on Cr with and without ceria. The main reason for the improvement in anti-oxidation of chromium was that ceria greatly reduced the growing speed and grain size of Cr₂O₃. This fine-grained Cr₂O₃ oxide film might have better high temperature plasticity and could relieve parts of compressive stress by means of creeping, and maintained the ridge character and relatively low internal stress level. Meanwhile, ceria application reduced the size and the number of interfacial defects, while remarkably enhanced the adhesive property of Cr₂O₃ oxide scale formed on Cr substrate.     

单分子层正癸酸包覆Fe_3O_4纳米粒子的研究

应用微乳液与 Fe2 + 和 Fe3 + 化学共沉淀的方法制备了正癸酸包覆的 Fe3 O4纳米粒子水基磁流体 .用光子相关光谱仪 ( PCS)、透射电镜 ( TEM)和 JDM- 3型振动样品磁强计对制得的水基磁流体进行了表征 .制备了单分子层正癸酸包覆的 Fe3 O4纳米粒子的固态样品 ,并利用 IR,TG,DTG与DSC考查了该固态样品的组成与性质 .发现用一步表面活性剂处理可以直接制得双层表面活性剂包覆的 Fe3 O4纳米粒子水基磁流体 .     

A fractal model for the effective thermal conductivity of nanoparticle suspensions

Extending the effective medium approximation with the fractal theory for describing nanoparticle clusters and their radius distribution, a predictive model is proposed for the effective thermal conductivity of nanoparticle suspension, combined with the consideration of size effect and surface adsorption effect of nanoparticles.The predicted effective thermal conductivity of nanoparticle suspension is consistent with experimental data in the dilute limit.