氮化硅窗口在大气环境软X射线接触成像中的应用研究

成功地研制了将软X射线引入大气中的氮化硅窗口。根据具体数据。对大气环境下软X射线接触成像的水窗软X射线衰减进行了估算;给出成像实验结果并观察到氮化硅膜上的微粒图像叠加在样品图像上的现象。所得结果与理论估算相一致。即使用3.2nm的软X射线时,同一样品在大气环境中所需的曝光量约为真空中的两倍。这些结果将十分有益于大气环境下的软X射线接触显微术及软X射线扫描透射显微术的研究。     

用于软X射线显微术的氮化硅窗口的研制

氮化硅膜具有对软X射线吸收较小、成膜光滑、强度大和致密性好等优点，因而常选作为窗口材料。本文主要介绍了用于软X射线显微术的氮化硅窗口的制备工艺，给出在国家同步辐射实验室软X射线显微术实验站使用的实验结果。     

用于软X射线显微术的氮化硅窗口的研制

氮化硅膜具有对软Ｘ射线吸收较小，成膜光滑，强度大和致密性好等优点，因而常选作为窗口材料。本文主要介绍了用于软Ｘ射线显微术的氮化硅窗口的制备工艺，给出在国家同步辐射实验室软Ｘ射线显微术实验站使用的实验结果。     

X射线束点尺寸对X射线相位衬度成像的影响

X射线相位衬度成像利用X射线穿过样品后的相位变化,通过衍射信息来获得样品的结构特征。X射线相位衬度成像在生物影像、显微成像以及材料科学研究中有重要的应用。如果X射线成像样品物质密度比较低,它对X射线的吸收很小,所以常规的吸收衬度成像质量较差,不易分辨样品的结构细节。理论分析和实验研究都表明当X射线束点尺寸减小到一定尺度后,X射线源的空间相干性增强,采用相位衬度成像可以提高低密度样品的成像质量。X射线相位衬度成像质量与X射线束点尺寸,样品到影像记录平面之间距离直接相关。本文研究了X射线束点尺寸与低密度样品影像边沿轮廓宽度和对比度之间的影响关系。研究结果表明,根据低密度样品的介电常数、X射线源到样品距离,以及样品到影像记录平面距离,存在最优化的X射线束点尺寸。在该最优化配置条件下,低密度样品的X射线成像可以获得最好的图像质量。     

X射线显微镜

主要介绍X射线显微镜的显微成像原理和几种类型X射线显微镜的基本构造、特点和应用实例。成像衬度可以是吸收衬度,也可以是相位衬度;显微镜可以是透射式的,也可以是扫描式的;还有一类将一些X射线光谱技术与显微镜结合的光谱显微镜,介绍了X射线吸收近边光谱、X射线磁圆二色谱和光电子发射谱与X射线显微镜的结合;另外,简要叙述X射线全息显微术。     

18.2nm正入射显微成像系统滤光片的研究

18．2nm正人射显微成像系统用多层膜可极大地提高18．2nm的反射率，但它对紫外、可见和红外光也产生很高的反射。显微成像系统用的激光等离子体光源会在红外到敦X射线产生大量的辐射，18．2nm正入射显微系统用的胶片对所有光谱都十分敏感。因此，182nm正人射显微成像系统需要用滤光片滤除不需要的光辐射并对18．2nm的软X射线有较大的透射比，这样才能获得18．2nm的软X射线像。本文讨论了18．2nm正入射显微成像系统用滤光片的设计、制作及其特性。为了去除滤光片膜中的应力，用交替蒸镀Al和C多层膜的方法来制备法光片，铝和碳膜是用磁控溅射法制备的。针孔透过率和成像实验表明，所制备的滤光片满足了18．2nm正入射显微成像系统对滤光片的要求，并且为进一步制备其他薄膜滤光片打下了基础。     

SPS制备氮化硅/锌铝基复合材料的组织和性能研究

通过放电等离子烧结工艺制备了氮化硅/锌铝基复合材料,重点探讨了氮化硅添加量对氮化硅/锌铝基复合材料致密度、硬度和摩擦性能的影响.采用扫描电子显微镜(SEM)及电子探针X射线显微分析仪(EPMA)对样品的微观组织进行了分析,并使用显微硬度仪、旋转摩擦试验仪对其性能进行了研究.结果表明:氮化硅在样品中分散均匀,且氮化硅的加入能够明显提高样品的致密度和硬度.当在锌铝合金中加入质量分数为20％氮化硅时,氮化硅/锌铝基复合材料致密度达到95.53％,同时与高锌铝合金烧结试样相比,其硬度提高了 58.5％,达到162.56HV.氮化硅/锌铝基复合材料的耐磨性随着氮化硅的添加呈现先增加后下降的趋势,添加量为20％时摩擦系数达到最佳为0.210 3,磨损量为0.003 37 mm3.     

计算机断层成像（CT）辐射剂量、患者安全和诊断成像的质量保证

一、概述 计算机断层成像（CT）是一种将从不同角度获取的一系列X射线图像融合,生成数字化人体断面图像的技术,这样生成图像的整体质量比传统的X射线成像更高。CT诊断技术已经成为众多疾病诊断和治疗计划中的重要环节。     

基于X射线像增强器成像的相衬滤波模型

对铝、黄铜、不锈钢3种金属材料制作的光栅在不同射线剂量和厚度差异的条件下进行图像采集,结合系统级的联合调制评价模型研究不同材料对X射线的调制作用,结果表明:在相同的射线剂量下,无论哪种材料的光栅,厚度差异越大成像反差越大;在厚度差异相同的情况下,随着射线剂量变化,不同材料对射线的调制能力变化趋势相差甚远。对光学调制传递函数、射线剂量和光栅厚度差异值进行三维曲线拟合,建立物质对X射线的调制模型和采集模型。在像增强器成像模型的基础上提出X射线相衬增强滤波模型,通过对薄膜基准目标源进行图像采集,在噪声环境下对其进行积分滤波处理和相衬增强处理,结果压低了图像噪声的同时也强化了目标轮廓信息,并大幅地增强X射线的成像反差。     

X射线同轴相衬成像实验

X射线相衬成像技术对软组织成像时比基于衰减的传统X射线成像技术优势明显,现在亟待发展一套广泛适用的相衬成像理论来指导其发展和临床应用．首先介绍了同轴相衬成像及相位成像的原理,随后根据菲涅耳．基尔霍夫衍射理论,利用数值模拟的方法研究微焦点源的尺寸对图像可见度的影响,最后在数值模拟结果指导下通过实验室直径为50μm的微焦点源X射线成像系统获得了厚度为150μm左右塑料气泡膜的相衬图像．     

PECVD法氮化硅薄膜的研究

本文采用射频等离子体增强化学气相生长法（ＰＥＣＶＤ），在单晶硅衬底上生长氮化硅薄膜，经Ｘ射线衍射测试发现，在（１００）晶向硅片上生长的氮化硅薄膜为（１０１）晶向的外延生长膜。还用红外吸收光谱拉曼光谱和Ｘ射线光电子能谱测试了β－Ｓｉ３Ｎ４的特性，讨论了它在微电子学中的应用。     

The environmental effect on cyclic fatigue behaviour in ceramic materials

In order to understand the environmental effects on cyclic fatigue, static and cyclic fatigue behaviour was investigated in air and in vacuum for normally sintered silicon nitride and alumina. The cyclic fatigue lifetime in vacuum is considerably longer than that in air, indicating a remarkable stress corrosion cracking effect in the latter, especially in alumina. In addition, the cyclic loading effect in vacuum is almost the same in silicon nitride relatively insensitive to environmental effects and alumina susceptible environmental effects. From such results, it has been found that cyclic fatigue in air is approximately expressed as the superposition of pure cyclic loading effect, which is defined as cyclic loading effect in vacuum, and environmental effect. This relation was applied to some kinds of ceramics with different values of fracture toughness or different microstructures and the results obtained were discussed.     

离子束表面改性氮化硅与钢的焊接研究

氮化硅表面用Ti，Cu，Mo等金属离子处理后，与45号钢在真空中进行焊接。样品分析结果表明，接缝强度与表面处理条件、焊接温度及真空度密切相关。在控制条件下，其剪切强度达220MPa。     

N-羟乙基丙烯酰胺交联改性核壳苯丙乳液的制备及涂膜性能

采用半连续种子乳液聚合法合成稳定的自交联核壳型苯丙乳液。考察了软硬单体配比、N-羟乙基丙烯酰胺(HEMAA)用量对乳液及涂膜性能的影响,初步探讨了HEMAA的改性机理。结果发现,当软硬单体配比m(St)∶m(BA)=2∶1,HEMAA添加量占主单体1%时,合成乳液聚合稳定性高,涂膜耐水性和热稳定性良好。傅里叶变换红外光谱、扫描电镜及透射电镜分析表明,HEMAA接枝到共聚物分子上且有明显的核壳结构;涂膜接触角及热重分析表明,涂膜的疏水性及热稳定性增强,水在涂膜上的接触角较改性前提高了5.26°,苯丙乳胶膜在实验条件下失重5%时,分解温度提高了58.03℃。     

ECR等离子体对硅表面的低温大面积氮化

利用电子回旋共振微波放电氮等离子体对单晶硅表面进行了低温大面积氮化的探索 ,通过样品表征和等离子体成分探测 ,分析讨论了氮化机理。结果表明 ,这种方法可以用于硅表面的低温氮化处理 ,获得大面积的均匀氮化硅表层。     

Defect characterization in the short-wavelength regime

The scattering of acoustic waves by different types of spherical defects in a silicon nitride matrix is calculated by using Ying and Truell's scattering theory. The theoretical scattering results are interpreted using a ray tracing approach. Experiments were carried out at a high frequency (150–450 MHz) to characterize defects in silicon nitride. Time and space averaging, Wiener filtering, diffraction, and propagation loss corrections were used to remove the effect of the transducer response and propagation loss in the material from the scattered signal. Our experimental results indicate the presence of a new type of defect in silicon nitride. They give the type and size of voids, cracks, and Si inclusions in good agreement with measurements obtained after sectioning.     

One-step production of superhydrophobic coatings on flat substrates via atmospheric Rf plasma process using non-fluorinated hydrocarbons

This paper describes the direct deposition of hydrocarbon coatings with a static water contact angle higher than 150 using simple C6 hydrocarbons as a reactive gas in helium plasma generated in ambient air without any preroughening of the silicon (100) substrate. The film morphology and hydrophobicity are found to strongly depend on the structure of the reagent hydrocarbon. The films deposited with n-hexane and cyclohexane exhibited relatively smooth morphology and the water contact angle was only ～95°, similar to polypropylene. When benzene was used as a main reactive gas, the deposited film surface showed nanoscale textured morphology and superhydrophobicity with a water contact angle as high as 167°. Because the plasma is generated in air, all films show some degree of oxygen incorporation. These results imply that the incorporation of a small amount of oxygenated species in hydrocarbon films due to excitation of ambient air is not detrimental for superhydrophobicity, which allows the atmospheric rf plasma with the benzene precursor to produce rough surface topography needed for superhydrophobicity.     

Comparative investigation of the biocompatibility of various silicon nitride ceramic qualities in vitro

There is a controversy about the biocompatibility of silicon nitride ceramics contained in the literature, which appears to be related to a factor of the individual chemical composition of different qualities of silicon nitride ceramics and of the different surface properties. This study attempts to investigate the cytotoxicity of different qualities of industrial silicon nitride ceramics applying an L929-cell culture model in a direct contact assay combined with a cell viability assessment. Five different qualities of industrial standard silicon nitride ceramics were chosen for in vitro testing. The chemical composition was determined by EDS analysis. Different biomedically approved aluminium oxide qualities, a titanium alloy, glass and polyvinylchloride (PVC) served as control materials. L929 mice fibroblasts were incubated directly on the materials for 24 h, stained with bisbenzimide and propidium iodine for double fluorochromasia viability testing, and evaluated by inversion-fluorescence microscopy to control cell morphology, viability and cell counts compared to empty well values. Scanning electron microscopy was applied to additionally investigate cell morphology. There was no observation of cytotoxic effects on the silicon nitride ceramic samples; moreover cell morphology remained the same as on aluminium oxide and titanium. Viability testing revealed the presence of avital cells exclusively on PVC, which served as a negative control. Cell counts on all polished surfaces showed significantly higher numbers, whereas some rough surface samples showed significantly lower numbers. We conclude that silicon nitride ceramics show no cytotoxic effects and should be considered for biomedical application owing to its favourable physiochemical properties, especially its superior resistance to mechanical stress, which would be useful for compression loaded conditions. Polished surfaces would appear to promote advanced biocompatibility.     

Si3N4薄膜的表面微观特性

利用偏心静电单探针诊断了反应室内的等离子体密度的空间分布;在不同的工艺条件下制备了Si3N4薄膜,由STM和Telystep-Hobbso轮廓仪研究了ECR－PECVD制备的Si3N4薄膜的表面微观特性,分析了沉积温度对ECR－PECVD制备的Si3N4薄膜表面平整度特性影响的物理机理;结果表明ECR－PECVD制备的薄膜是一种表面均匀致密的纳米Si3N4薄膜。