“三明治式”多层Au/Pt复合薄膜的制备及其对甲醇的电氧化

采用界面组装、欠电位沉积和氧化还原置换反应组合方法制备了单层Pt/Au复合薄膜, 并且不需要任何有机偶联剂; 组装单层Pt/Au复合薄膜为三类多层Pt/Au复合薄膜: (Pt/Au)_n、Pt_m/Au和(Pt₃/Au)_k (n、m和k分别为Pt/Au、Pt和Pt₃/Au的层数). 采用电子显微镜研究了Au纳米粒子单层膜和Pt/Au复合多层膜的形貌. 对于所有的多层膜电极而言, 其电化学活性面积随着层数的增加而增加. 通过研究甲醇在每一类Pt/Au复合薄膜上的氧化电流密度, 考察了其对甲醇的电催化和抗毒化性能. 对于同一类复合薄膜而言, 甲醇分别在(Pt/Au)₃、Pt₃/Au和(Pt₃/Au)₂电极上均具有最大的氧化电流密度, 且优于本体Pt电极. 在这三种电极中, (Pt/Au)₃电极无论从电流密度上还是从抗毒化能力上讲, 其性能是最好的, 而且其抗毒化能力也优于商业Pt/C催化剂. 这种良好的催化性能源于Au和Pt之间最大化的协同效应, 这取决于Pt和Au原子比率以及Pt纳米层和Au纳米层之间的排布方式.     

Layer-by-layer assembled multilayer films of methoxypoly(ethylene glycol)-block-poly(α,l-glutamic acid) and chitosan with reduced cell adhesion

A methoxypoly(ethylene glycol)-block-poly(α,L-glutamic acid) (mPEGGA) diblock copolymer is synthesized. Using QCM measurements, it is shown that (CS/mPEGGA)(n) film construction takes place over two build-up stages (exponential-to-linear). UV-vis spectra reveal the regular increase of the multilayer film growth at different molecular weights of mPEGGA. Contact angle and surface morphology investigation prove that the hydrophilicity of CS/mPEGGA multilayer film-modified substrate becomes better and the surface becomes rough. Significantly reduced cell adhesion is observed on the CS/mPEGGA multilayer film coated surface.     

改进的Whipple防护结构与相关数值模拟方法研究进展

基于弹丸在超高速撞击薄板时破碎形成碎片云的机理,Whipple防护结构能够对航天器所面临的空间碎片及微流星体等威胁形成有效防护。通过回顾Whipple防护结构的研究和发展历程,对多层板结构、填充式防护结构、夹芯板结构等进行对比,分析其力学效应和防护性能;总结可应用于含泡沫、蜂窝、梯度和编织等材料的防护结构超高速撞击的数值模拟方法及其改进方法;结合相关材料的超高速撞击试验及数值模拟结果,为防护结构未来的研究方向提出建议。     

Physicochemical Studies of the Sea-Surface Microlayer

In physicochemical studies on the sea-surface microlayer (SML) in seawater, the main researches conducted were as follows: (1) It was found that there is an objective layer of sudden change in physical and chemical properties between the SML and the subsurface layer in seawater. (2) The SML thickness was determined and should be about 50±10 μm. (3) The Gibbs model of the SML was extended, and the multilayer model of the SML was advanced. (4) The original-location method, which corresponds with the traditional removal-location method, was founded and used to determine the SML thickness. The results obtained from the two methods were almost identical. (5) An abnormal phenomenon was found when the Gibbs solution adsorption was applied to the seawater system, the reason for which was discussed preliminarily.     

类Ne钛X射线激光输出特性实验

 在星光激光装置上, 使用X射线多层膜反射镜、铝滤片及X射线CCD探测器组成高灵敏度空间分辨探测系统, 对用预脉冲技术产生的类Ne钛单线 (J=0-1, 3p-3s跃迁)软X射线激光输出特性进行了测量。由实验得到了类Ne钛X 射线激光束近场与距靶端32mm处(准远场)强度的空间分布, 给出了该激光束在近场强度最大区域的空间尺度(FWHM)约为72μm×31μm, 以及在垂直靶面与平行靶面方向的束发散角分别约为4mrad与9mrad。     

Rheological properties and interfacial slip of a multilayer structure under dynamic shear

Interfacial slip between polymer melt under steady shear has been studied using a simplified multilayer structure. In this investigation, interfacial slip under dynamic shear was studied by calculating the angular displacements of the multilayer structure and its component layers. On the basis of the angular displacements, a slip index was defined to quantify the degree of interfacial slip. A relationship governing the rheological behavior of the multilayer structure under slip and nonslip condition was established. These results were correlated with equations derived from consideration of energy equilibrium in the multilayer structure. Polymer multilayer structures of high‐density polyethylene/polystyrene and liquid crystal polymer(LCP)/poly ethylene naphthalate(PEN) were investigated. Of all the polymers investigated, large interfacial slip was found at LCP/PEN interface under dynamic shear. The high rigidity and alignment along the interface of LCP molecules was believed to prevent chain entanglement in the interfacial layer and therefore promote interfacial slip at the interface. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 2683–2693, 2005     

北京同步辐射软X光反射率计装置及其物理工作

介绍了安装在北京同步辐射装置上专门用于软X光多层膜研究的反射率计系统,给出了在该装置上测量得到的Al滤光片的软X光透射谱和Nb/Si多层膜的高角反射谱,用磁控溅射方法自制的Nb/Si多层膜样品在17.59um附近得到的反射率为32%.     

电磁波在多层介质内的透射

导了多层介质中透射电磁波的电场振幅与介质表面入射电磁波场电场振幅之间的关系式，引入了一个母函数，通过微分可以生成介质各层中的透射波。     

Combined EPMA and AES depth profiling of a multilayer Ti-Al-O-N coating

In order to compare thin-film electron probe microanalysis (EPMA) and Auger electron spectroscopy (AES) regarding reliability in quantifying chemical compositions of Ti-Al-O-N coatings with depth, a multilayer was prepared on a silicon wafer by using reactive ionized cluster beam deposition technique. Within a total thickness of about 25 nm the composition of the multilayer varied step by step from Ti-Al-O-N at the bottom to Al-O at the top. AES and, as an innovation, EPMA crater edge profiling was applied to measure the composition with depth. For quantification special thin-film EPMA techniques based on Monte Carlo simulations were applied. The chemical binding states of Al and Ti with depth were analysed using a high resolution energy analyser (MAC 3) for the AES investigations working in the direct mode. According to the deposition procedure the concentration profiles of the components varied with depth for both AES and EPMA measurements. AES provided a better depth resolution than EPMA. To get a true calibration of the depth scale an in-situ measurement method like an optical interferometry will be required. Assuming that the relative sensitivity factors are available AES depth profiling delivers concentration profiles with good accuracy. The new EPMA application provided quantitative depth profiles concerning concentration and coverage. For EPMA crater edge profiling the coating needs to be deposited on a foreign substrate because depth distributions of elements being present in both the layer and the substrate cannot be resolved.The combination of AES-depth profiling with EPMA crater edge profiling techniques is a powerful tool to analyse heterostructures quantitatively.     

NONLINEAR THEORY OF MULTILAYER SANDWICH SHELLS AND ITS APPLICATION(III)──LARGE DEFLECTION AND POSTBUCKLING OF SHALLOW SHELLS

Exactsolutionsoflargedeflectionandpostbucklingofrectangularplatesaredifficultproblems.Usually,appropriateseriesofsolutionsbasedonspecificboundaryareassumedtosolvetheproblems['].LiuandChengl'lsolvedthenonlinearbendingproblemofsimplysuPPortedrectangularsand…