憎水性纳米银粒的反相微乳液法制备与自组装

利用十八胺/正丁醇/正庚烷/甲酰胺/A gNO3(aq)构成的W/O型微乳液体系,在回流状态下由甲酰胺还原银离子制得了十八胺稳定的憎水性银纳米粒子,并通过UV-V is、TEM和XRD等手段对样品进行了表征.所制十八胺包裹的银纳米颗粒粒径分布较宽,且粒子形成了大、小尺寸的两个集团,在自组装试验中大、小粒子分别位于单层膜的中心和边缘地带.     

MWNTs/PET纳米复合材料的研究

通过原位聚合的方法制备出纯PET和PET/MWNTs-COOH纳米复合材料.用透射电镜分析了MWNTs在乙二醇中的分散情况.用邵氏硬度计分析仪研究了MWNTs对PET硬度的影响,结果表明MWNTs提高了PET的邵氏硬度.用红外和透射电镜结合对复合材料的结构进行了分析.结果表明,MWNTs与PET分子发生了反应,很好地分散在PET的基体中,增强了PET的硬度.     

聚焦离子束在精细加工中引起损伤的分析

微分析技术已经成为微电子产业发展的重要技术支撑,FIB(focusedion beam)结合了精细加工技术和微分析技术,具有在亚微米线度上的微细加工和高分辨率成像的能力,成为强有力的TEM(transmission electron microscope)制样工具以及电路修补的有力工具.同时,FIB辐照对样品结构的损伤以及器件性能的影响受到广泛的关注.为使实际FIB的工作更优化,更有针对性,从而确保不同器件在FIB加工后的可靠性,从研究FIB辐射对材料结构的损伤入手,针对两种不同类型的晶体管(常规工艺NMOS晶体管和埋沟工艺PMOS晶体管),进行了FIB辐照下的电学性能对比.较常规工艺的NMOS晶体管,埋沟工艺的PMOS晶体管在跨导和迁移率等参数的变化情况与前者相似,但是在阈值电压变化,辐照损伤修复方面,后者显示出独特的性能.     

TEM observation on nucleation of Ca α-Sialon

Ca α -Sialon compacts pressurelessly-sintered to the intermediate temperature (1 450℃) were investigated with TEM for an overall composition Ca_1.8Si_6.6Al_5.4O_1.8N_14.2. It was found that in most cases, the newly-formed α -Sialon grains had no epitaxial orientation relationship with the Si₃N₄ particles; only occasionally heteroepitaxial nucleation of α -Sialon on α -Si₃N₄ was detected. Further EDAX analysis revealed a much higher Ca concentration in the non-epi- taxially nucleated α -Sialon than in the heteroepitaxially nucleated α -Sialon. Thus a possible correlation between the concentration of metal cations in the α -Sialon structure and the nucleation mechanism has been proposed, i.e. α -Sialon compositions with higher Ca concentration show a stronger trend of non-epitaxial nucleation.     

颗粒活性炭对SBR反应器中好氧颗粒污泥培养的影响研究

好氧颗粒污泥培养耗时长已经成为限制其广泛应用的重要因素之一,依据"晶核假说"原理,在反应器中投加惰性核可以加快污泥好氧颗粒化进程.为了研究颗粒活性炭对于污泥好氧颗粒化进程的影响,在SBR反应器启动初期投加颗粒活性炭(SBR有效体积的1%,平均粒径为0.1—0.3mm)作为诱导核,采用扫描电镜和细菌凋亡荧光染色来表征好氧颗粒污泥.结果表明,颗粒活性炭有利于好氧颗粒污泥的形成,运行20d即获得了成熟的好氧颗粒污泥.扫描电镜结果显示,成熟的好氧颗粒污泥结构密实,微生物种类较为丰富.好氧颗粒污泥细菌凋亡荧光染色结果表明死细菌分布较为均匀,但活细菌多位于外层;胞外多聚物多重荧光染色表明蛋白质和多糖(α-吡喃葡萄糖、α-甘露糖和β-D-吡喃葡萄糖)等物质在好氧颗粒污泥内部分布较为均匀,虽然含量接近,但β-D-吡喃葡萄糖含量最多.本研究表明,在反应器中投加颗粒活性炭可以促进好氧颗粒污泥的形成.     

细菌芽孢染色方法比较的研究

芽孢是微生物的重要结构,对于微生物的分类有着十分重要的作用。目前,在芽孢染色上虽有不少方法,但仍存在染色效果不明显的缺点。对三种芽孢染色法进行了比较研究,结果发现：方法三着色强,观察清晰,染色效果更理想,而且该方法快速、有效、简便易行,更适于在实验教学中应用。     

Bias polarity-sensitive electrical failure characteristics of ZnSe nanowire in metal–semiconductor–metal nanostructure

The effect of bias polarity on the electrical breakdown behavior of the single ZnSe nanowire(NW) in the metal–semiconductor–metal(M–S–M)nanostructure under high current density and high bias conditions has been studied in the present paper. The experimental results show that the failure of the ZnSe NW in M–S–M nanostructure was sensitive to bias polarity since the NW commonly collapsed at the negatively biased Au metal electrode due to high Joule heat produced in NW at the reversely biased Schottky barrier. Thus, the electrical breakdown behavior of the ZnSe NW was highly dominated by the cathode-controlled mode due to the high resistance of the depletion region of ZnSe NW at the reversely biased Schottky contact.     

地方高校英语专业学生元认知策略使用调查——以韶关学院为例

对韶关学院133名英语专业本科生元认知策略使用情况的调查结果表明,学生不经常使用元认知策略;建立学习重点、安排和计划学习、评价学习这三类元认知策略都与英语专业四级成绩具有相关性;成绩合格组和不合格组在建立学习重点及安排和计划学习两类策略的使用上存在显著差异。     

基底对类金刚石薄膜摩擦学性能的影响

为了研究不同基底对类金刚石薄膜摩擦磨损性能的影响,采用等离子体增强化学气相沉积方法在高速钢、SiC和304不锈钢基底上成功制备了类金刚石薄膜。采用SEM,TEM,Raman测试手段对膜层的微结构进行了表征:SEM表征结果显示膜层总厚度约为6.5μm,而且层与层之间有明显的界面;TEM表征结果显示沉积的膜层为无定型结构;Raman光谱分析显示沉积的薄膜存在明显的G峰和D峰,可以确定沉积的薄膜为类金刚石薄膜。摩擦测试结果显示,基底对类金刚石薄膜摩擦磨损性能具有显著影响,对于不同基底,钢球对偶上均存在明显的转移膜,高速钢基底的磨痕宽度最小,而且沉积在高速钢基底上的类金刚石薄膜具有最低的磨损率,摩擦系数约为0.1。采用Raman光谱对不同基底磨痕表面微结构进行了分析,认为高速钢基底具有最低磨损率可归因于其磨痕的石墨化程度低。研究可为制备具有优异摩擦磨损性能的类金钢石薄膜提供参考。     

Transmission electron microscopy and atomic force microscopy characterization of nickel deposition on bacterial cells

Recently bacterial cells have become attractive biological templates for the fabrication of metal nano- structures or nanomaterials due to their inherent small size, various standard geometrical shapes and abundant source. In this paper, nickel-coated bacterial cells (gram-negative bacteria of Escherichia coli) were fabricated via electroless chemical plating. Atomic force microscopy (AFM) and transmission electron microscopy (TEM) characterization results reveal evident morphological difference between bacterial cells before and after deposition with nickel. The bare cells with smooth surface presented transverse outspreading effect at mica surface. Great changes took place in surface roughness for those bacterial cells after metallization. A large number of nickel nanoparticles were observed to be equably distributed at bacterial surface after activation and subsequent metallization. Furthermore, ultra thin section analytic results validated the presence and uniformity of thin nickel coating at bacte- rial surface after metallization.