A note on immersion minors and planarity

Graph minors play an important role in graph theory. The focus of this paper is on immersion minors and their relationship to planarity. In general, planar graphs can have non-planar immersion minors. This paper shows that by placing a simple restriction on the immersion-minor operations, all immersion minors of a planar graph are planar. This then allows one to easily obtain a characterization of planar graphs using immersion minors. A dual form of this characterization, as well as an extension to binary matroids, are also considered.     

非平坦的Randers空间中的极小旋转超曲面

本文的研究分为两部分.第一部分是在特殊的Randers空间中得到了等距浸入的HT-极小旋转超曲面,这些特殊的Rander空间是非Minkowski的,但是它们的旗曲率为零.第二部分刻画了Funk空间中的各向异性极小旋转超曲面.     

等离子体浸没离子注入制备黑硅抗反射层及其光学特性研究

表面织构是一种有效降低表面反射率、提高硅基太阳能电池效率的方法. 采用等离子体浸没离子注入的方法制备了黑硅抗反射层.分别通过原子力显微镜和紫外-可见-近红外分光光度计对黑硅样品表面形貌和反射率进行分析, 结果发现黑硅样品表面布满了高度为0—550 nm的山峰状结构, 结构层中硅体积分数和折射率随抗反射层厚度增加而连续降低. 在300—1000 nm波段范围内,黑硅样品的加权平均反射率低至6.0%. 通过传递矩阵方法对黑硅样品反射谱进行模拟,得到的反射谱与实测反射谱非常符合.     

增强辉光放电等离子体离子注入的三维PIC／MC模拟

采用三维粒子模拟／蒙特卡洛模型自洽地模拟了增强辉光放电等离子体离子注入过程中离子产生和注入,获得了放电空间的离子总数、电势分布、等离子体密度分布和离子入射剂量等信息．模拟结果表明,5μs时鞘层达到稳定扩展,15μs时离子的产生与注入达到平衡,证实了增强辉光放电等离子体离子注入能在一定条件下实现白持的辉光放电．注入过程中,在点状阳极正下方存在一个高密度的等离子体区域,证实了电子聚焦效应．除靶台边缘外,离子的注入速率稳定且入射剂量均匀．脉冲负偏压提高时注入速率增加但入射剂量的均匀性变差．     

基于PIII技术的高真空洁净环境中润滑问题

针对高洁净的真空环境下终端光学组件内运动机构的润滑问题,采用等离子体浸没离子注入（PIII）技术对复杂形状的零件进行表面改性,通过轴承内外圈表面改性前后的对比实验分析,结果表明,通过对注入元素、剂量和能量的选择,可以大幅度提高材料表面的硬度及耐磨性,并且零件的尺寸精度及表面粗糙度保持性好,充分证明了PIII技术可以在满足颗粒洁净度和有机物洁净度的双重要求条件下,提高运动部件抗摩擦磨损性能,延长微驱动机构的运动精度寿命,是解决终端光学组件中润滑问题的有效途径。     

Porous poly(vinylidene fluoride) membrane modified with hyperbranched poly(amine‐ester)

Poly(vinylidene fluoride) (PVDF) membranes were hydrophilic modified with hydroxyl group terminated hyperbranched poly(amine‐ester) (HPAE). Fourier transform infrared spectroscopy (FT‐IR) was used to study the chemical change of PVDF membranes. X‐ray photoelectron spectroscopy (XPS) indicated that some HPAE molecules were retained in PVDF membrane through polymer chain coiling. The presence of HPAE would improve the hydrophilicity of PVDF membrane. Scanning electron microscopy (SEM) was employed to characterize the morphology of different membranes. The thermodynamic stability for PVDF/DMAc/HPAE/Water system was characterized by the determination of the gelation values. Precipitation kinetics for PVDF/DMAc/HPAE/Water system was studied by precipitation time measurement. The water contact angle indicated that the hydrophilicity and the biocompatibility corresponding to protein adsorption of PVDF membrane were improved significantly after blending with hydrophilic HPAE molecules. Copyright © 2011 John Wiley & Sons, Ltd.     

Immersion by rotation‐based application of the matrix for fast and reproducible sample preparations and robust results in mass spectrometry imaging

Automated matrix deposition for matrix‐assisted laser desorption/ionization (MALDI) mass spectrometry imaging (MSI) is crucial for producing reproducible analyte ion signals. Here we report an innovative method employing an automated immersion apparatus, which enables a robust matrix deposition within 5 minutes and with scalable throughput by using MAPS matrix and non‐polar solvents. MSI results received from mouse heart and rat brain tissues were qualitatively similar to those from nozzle sprayed samples with respect to peak number and quality of the ion images. Overall, the immersion‐method enables a fast and careful matrix deposition and has the future potential for implementation in clinical tissue diagnostics.     

An undercutting model of atomic oxygen for multilayer silica/alumina films fabricated by plasma immersion implantation and deposition on polyimide

Multilayer silica/alumina films were created by plasma immersion implantation and deposition to protect against atomic oxygen (AO) in low earth orbit environment. The AO erosion mechanism of polyimide under multilayer silica/alumina films has been investigated using a ground-based AO simulator and Monte Carlo model. The results demonstrate that protective films are detached and plumped due to AO undercutting, and the exterior silica film is partly detached proven by chemical composition depth profile and erosion patterns. The undercutting model involving collision, diffusion, reaction, gas releasing, and retroaction on films is proposed. Based on the model, scattered impingement has serious erosion, although AO does not directly attack interior polymer. AO erosion predictions at two neighborhood cracks are first studied by Monte Carlo model for various incidence angles of AO. The protective film between cracks hinders the escape of AO, and accelerates the erosion.     

Improving the resolution of a solid immersion lens optical system using a multiphase Fresnel zone plate

We propose a method to improve the resolution of near-field optical system with a solid immersion lens by using a multiphase level Fresnel zone plate. The analyses are based on scalar angular spectrum theory. The results show that the multiphase Fresnel zone plate can not only decrease the spot size but also decrease the sidelobe intensity and enhance greatly the diffractive efficiency compared with annular amplitude filter or binary 2-, 3-, 4-zone phase filter.     

Construction of pseudorandom binary sequences by using the multiplicative inverse

Summary By using the multiplicative inverse modulo p, a large family of finite binary sequences is constructed with strong pseudorandom properties. The crucial tool in the proofs is an (additive) character sum estimate of Eichenauer--Hermann and Niederreiter.