Ultrahydrophobic PMMA micro- and nano-textured surfaces fabricated by optical lithography and plasma etching for X-ray diffraction studies

Polymeric (PMMA) ultrahydrophobic surfaces with contact angles up to about 170° have been fabricated and used in the context of synchrotron radiation experiments on biological droplets. The different microfabrication processes included either an optical lithography phase followed by a plasma texturing one or a single step deep reactive ion etch attack.The drying of several biological solution droplets has been monitored. Room temperature evaporation experiments (lysozyme, lactalbumin, cytochrome C, doxorubicin and synthesized peptides) finally result in the formation of easily detachable hollow residuals because of the low interaction between the ultrahydrophobic substrate and the aqueous droplet while pilot experiments (bovine insulin) in a sitting-drop environment bring to the formation of well defined crystals. Recent results about in situ X-ray diffraction experiments by SAXS & WAXS (Small and Wide Angle X-ray Scattering) μ-beam techniques confirm that the presence of such surfaces influences the formation of crystal or fibril structures. These substrates represent indeed a suitable support to study biological and inorganic droplets in a near contact-free environment exploiting the homogeneous evaporation rate induced by the ultrahydrophobicity of the system.     

沿海岛屿数据用于蒸发波导分析的低可信度

在我国沿海海域,没有大量的气象浮标,但在岛屿或海边有大量的气象观测站,能否利用这些气象观测站获得的数据进行蒸发波导特性分析,值得深入研究.对比沿海岛屿实测数据与NCEP再分析数据,并将这两种数据输入NPS模型后发现蒸发波导高度的差异较大.但是对比气象浮标数据与NCEP数据,表明NCEP再分析数据用于蒸发波导统计分析是可信的,从而得出结论:沿海岛屿测量数据应用于蒸发波导统计特性研究的可信度较低.理论分析表明:成因是海陆交互作用的影响.但其气象参数的变化趋势与NCEP再分析数据的变化趋势比较一致,对于蒸发波导强弱和变化趋势的判定,仍有一定参考价值.     

超高压力传感器绝缘封装薄膜的工艺研究

为了提高锰铜传感器的测压上限,须用薄膜工艺制备无机绝缘三氧化二铝薄膜来作为传感器的绝缘封装层。采用电子束蒸发法,对影响三氧化二铝薄膜的相关工艺如:蒸发原料的纯度、成膜次数进行了研究。最终得出:由99.99%的三氧化二铝原料制备出的薄膜致密性好、缺陷少,其绝缘电阻率和损耗分别可达1012O·cm和103量级;而采用多次间隙蒸发可明显改善薄膜的附着性和致密性。     

低压高温退火对Ag掺杂ZnO薄膜性质的影响

采用电子束蒸发在n-Si(100)衬底上沉积Ag掺ZnO(ZnO:Ag)薄膜,随后在200 Pa的O<,2>气氛下分别在500、600、700和800℃退火4 h.用X射线衍射(XRD)仪、荧光光谱仪以及Van der Pauw方法测量ZnO:Ag薄膜的结构和光电学性质.结果表明,ZnO:Ag薄膜为多晶结构,且随着退火...     

室内声场建模方法最新发展

室内声场计算机仿真是近年来在声学领域颇受重视的研究方向。近来波导网络法、自适应声束跟踪法和神经网络法开始被引入,并逐渐受到重视。着重介绍这三种新方法的基本思想和优缺点。     

Layer‐by‐Layer Growth of Multicomponent Colloidal Crystals Over Large Areas

Self‐assembly of different sized colloidal particles into multicomponent crystals results in novel material properties compared to the properties of the individual components alone. The formation of binary and, for the first time, ternary colloidal crystals through a simple and inexpensive confined‐area evaporation‐induced layer‐by‐layer (LBL) assembly method is reported. The proposed method produces high quality multicomponent colloidal crystal films over a broad range of particle size‐ratios and large surface areas (cm²) from silica/polystyrene colloidal suspensions of low concentration. By adjusting the size‐ratio and concentration of the colloidal particles, complex crystals of tunable stoichiometries are fabricated and their structural characteristics are further confirmed with reported crystal analogues. In addition, complex structures form as a result of the interplay of the template layer effect, the surface forces exerted by the meniscus of the drying liquid, the space filling principle, and entropic forces. Thus, this LBL approach is a versatile way to grow colloidal crystals with binary, ternary, or more complex structures.     

高效放电加工法及工艺参数优化实验研究

根据放电时产生的加工液沸腾、气化膨胀引起放电通道周围加工液快速流动的原理,提出了一种新的排屑方法,系统地研究了使用该方法的放电加工特性。试验结果表明,该方法可以实现高效率放电加工。当放电电流大、极间距离小、脉冲长、脉冲间隔短时,加工屑能够顺利地被排出极间。     

氧分压对电子束蒸发TiO2薄膜残余应力的影响

采用电子束蒸发法制备了单层TiO2薄膜.控制O2流量从10 mL/min以步长10 mL/min递增至50 ml/min(标况下).利用ZYGO干涉仪测量基片镀膜前后的面型变化;采用Stoney公式计算出残余应力,分析了不同O2压下残余应力的变化.在本实验条件下,TiO2薄膜的应力随O2的增大,张应力先增大后减小;随O2压继续增大,由张应力逐渐过渡到压应力;O2压过大时,压应力减小.因此,可以通过改变O2压来控制薄膜的应力.应力的变化与薄膜的微观结构密切相关,分析了所有样品的X射线衍射(XRD)谱发现,薄膜结构均为非晶态.     

热氧化法制备ZnO纳米棒及其结构表征

在无催化剂条件下,采用热蒸发Zn源,以N2为载气体,在SiO2衬底上反应沉积制备出单晶氧化锌纳米棒。XRD研究表明纳米棒为结晶完好的纤锌矿结构,并且为非定向生长,非定向生长的氧化锌纳米棒减弱了棒之间的屏蔽效应,表现出较好的场发射效果,为未来场发射电子器件的实际应用提供了可靠依据。     

基于抛物方程的海上电波传播研究

抛物方程已经被广泛地应用于电波传播预测模型,并成为解决电磁波传播问题的主要工具。针对目前大多数预测模型处理粗糙海面的不足,引进了一种能包含海面阴影效应的粗糙度修正因子,并由于电波在海面上传播主要受到蒸发波导和粗糙海面的影响,结合抛物方程和蒸发波导理论对海面上的电波传播进行了研究,利用PE模型计算了电波在蒸发波导中不同条件下的传播损耗,并分析了蒸发波导和粗糙海面对电波传播的影响。