Scanning Nanowelding Lithography for Rewritable One‐Step Patterning of Sub‐50 nm High‐Aspect‐Ratio Metal Nanostructures

The development of a new nanolithographic strategy, named scanning nanowelding lithography (SNWL), for the one‐step fabrication of arbitrary high‐aspect‐ratio nanostructures of metal is reported in this study. Different from conventional pattern transfer and additive printing strategies which require subtraction or addition of materials, SNWL makes use of a sharp scanning tip to reshape metal thin films or existing nanostructures into desirable high‐aspect‐ratio patterns, through a cold‐welding effect of metal at the nanoscale. As a consequence, SNWL can easily fabricate, in one step and at ambient conditions, sub‐50 nm metal nanowalls with remarkable aspect ratio >5, which are found to be strong waveguide of light. More importantly, SNWL outweighs the existing strategies in terms of the unique ability to erase the as‐made nanostructures and rewrite them into other shapes and orientations on‐demand. Taking advantages of the serial and rewriting capabilities of SNWL, the smart information storage–erasure of Morse codes is demonstrated. SNWL is a promising method to construct arbitrary high‐aspect‐ratio nanostructure arrays that are highly desirable for biological, medical, optical, electronic, and information applications.     

纳米羟基磷灰石/聚酰胺66复合材料在模拟体液(SBF)中的表面生物活性研究

通过纳米羟基磷灰石／聚酰胺66(n—HA／PA66)复合材料体外模拟体液(SBF)浸泡实验，以聚酰胺66(PA66)为对照，用IR、XRD、SEM和ICP等手段对材料的表面组成和形貌变化进行了分析，比较了PA66和n-HA／PA66复合材料的表面生物活性。结果表明，n-HA／PA66复合材料在SBF中其表面形成的HA沉积物为部分碳酸基团取代的磷灰石，而PA66在浸泡过程中Ca、P不在聚合物表面沉积；n-HA／PA66复合材料具有良好的生物活性，作为骨组织修复或替代材料具有较高的研究和应用价值。     

高流动性星型尼龙12的合成与表征

在均苯三甲酸的存在下,进行十二内酰胺的水解聚合,合成了四种不同臂长的三臂星型尼龙12,对产物的分子量进行了测定,并对其力学性能和流变行为进行了研究。结果表明,星型尼龙12的分子量随着均苯三甲酸含量的提高而降低,与相应分子量的线型尼龙12相比,星型尼龙12的拉伸强度和弯曲强度基本保持,冲击强度保持率在80%以上,断裂伸长...     

A2N反硝化除磷脱氮系统处理生活污水研究

研究了生活污水COD／TN比值变化对A2N反硝化除磷脱氮新工艺去除氮、磷的影响情况。同时利用间歇试验着重探讨了DNPAOs污泥在不同硝态氮浓度、不同电子受体时的摄磷和放磷状况。A2N连续流工艺长期的运行结果表明：双泥系统的建立(生物膜硝化池独立于除磷污泥)可以降低碳源的好氧消耗,较大程度地减少聚磷菌和反硝化菌之间对碳源的竞争,同时保证了生长速率较小的硝化菌可以在稳定状态中生长,利于增强系统脱氮除磷的稳定性。     

水稻基因组MSAP指纹图谱构建及DNA甲基化修饰位点分离与鉴定

采用EcoR I和Hpa II/Msp I双酶切建立了适合于水稻基因组的甲基化敏感扩增多态性(MSAP)分析体系,在全基因组水平检测了水稻DNA甲基化修饰位点.以12对MSAP引物进行选择性扩增,共检测到甲基化修饰位点120个,"CCGG/GGCC"位点甲基化修饰比例为20.17%.对部分水稻基因组甲基化修饰位点进行回收,最终分离了55条存在甲基化位点变异的DNA序列,通过BLAST比对分析将其联配到水稻基因组序列上.分析表明,这些甲基化修饰位点主要集中于基因启动子区(47%)和第一外显子区(22%),在其侧翼序列中存在类似"CpG island" 典型序列特征的"CpG"二核苷酸成簇富集区.在此基础上,对应用MSAP技术分离水稻基因组DNA甲基化修饰位点的有效性以及水稻基因组序列中"CpG island"类似序列分布特征和生物意义进行了讨论.     

乐甫波器件的幅频特性研究

乐甫波器件的设计制作过程中,幅频特性是其关键性能指标.本文基于部分波理论和表面有效介电常数方法建立乐甫波谐振频率的理论分析模型,计算乐甫波的传播速度、谐振频率及机电耦合系数;在此基础上通过在梅森等效电路中加入波导元件,得到乐甫波器件的等效电路模型,仿真出器件的幅频特性曲线;通过实际器件测试结果与数值仿真对比,验证了理论模型的有效性.仿真分析薄膜厚度变化对乐甫波器件幅频特性的影响,指导器件的设计制作和测试系统的搭建.     

高性能制动系统用炭纤维增强炭和SiC双基体(C/C-SiC)复合材料

C/C-SiC制动材料具有密度低、耐高温、制动平稳、摩擦因数高、磨损少和环境适应性强等优点,是一种能满足高速高能载制动的高性能轻质材料。本文以针刺炭纤维整体毡为预制体,采用化学气相渗透法制备C/C多孔体,然后熔融渗硅制得C/C-SiC材料;研究了C/C-SiC材料的组织结构、力学性能及其失效模式、摩擦磨损性能及机理,同时介绍了中南大学研制的C/C-SiC制动材料的应用现状。     

Optimal storage rack design for a multi-deep compact AS/RS considering the acceleration/deceleration of the storage and retrieval machine

This paper explores the optimal storage rack design for a multi-deep compact Automated Storage and Retrieval System (AS/RS) considering the acceleration and deceleration of storage and retrieval (S/R) machine. The expected travel time under the single-command cycle and dual-command cycle for a random storage strategy is derived. Based on the travel time, the general models we propose calculate the optimal ratio between three dimensions that minimises the travel time under different speed profile scenarios. From the result, it is proven that the optimal storage rack design model in the constant speed situation can be treated as a special case of the model considering the acceleration and deceleration of S/R machine. Finally, this study investigates the effect of speed profile of S/R machine and fixing dimensions by various numerical experiments.     

单晶硅预制初裂纹扩展行为的分子动力学研究

采用基于Stillinger-Weber作用势的分子动力学方法研究了单晶硅预制初裂纹前缘方向分别为[100]、[110]、[111]晶向的裂纹扩展行为.模拟结果表明:低温时裂纹尖端形成新的环状结构,温度逐渐升高后,出现母-子裂纹传播机制,裂纹前缘方向为[111]晶向的初裂纹扩展呈现出明显的取向效应.