铍材应力常数的X射线法测试

在X2001应力分析仪上采用悬臂梁加载法测试了可以用于铍的X射线应力测试的5个衍射晶面的应力常数。结果表明,铍的5个衍射晶面的应力常数差异较大，在进行X射线应力分析时．应采用相应衍射晶面的应力常数，才能获得准确的应力分析结果。由于X射线对铍有较大的穿透深度，必须考虑X射线穿透深度对应力常数标定的影响。     

Edge diffraction correction for 3D scattering center modeling based on the shooting and bouncing ray technique

In the traditional scattering center extraction method based on the shooting and bouncing ray(SBR) technique,only the physical optics contribution of the target is considered.However,the physical optics method is unable to describe the contribution of the actual edge diffraction.By comprehensively considering the specular reflection and edge diffraction contribution of the target,an edge diffraction correction method for 3D scattering center modeling based on the SBR technique is proposed.Using the SBR technique and combining the image domain ray tube integration and equivalent edge currents method,the edge diffraction correcting formula for the 3D inverse synthetic aperture radar image is derived.Simulation results show that the proposed method is able to effectively improve the modeling accuracy of the 3D scattering center.     

X射线透射成像技术原位追踪混凝土吸水过程

为了表征二维混凝土的传输过程,制备厚度为1 mm的混凝土薄片. 采用X射线透射成像（TXR）技术,联合扫描电镜、背散射和能谱分析技术（SEM/BSE/EDS）原位追踪水在2维混凝土薄片中的毛细自吸过程. 测试不同质量分数CsCl溶液对X射线透射图像的增强效果. 结果表明,CsCl能够提高吸水过程中混凝土薄片的TXR图像对比度,使得水在混凝土中的渗流路径更清晰、可辨. 水泥浆体在吸收CsCl后,扫描电子背散射图像的对比度显著增强. 不同位置铯原子的EDS能谱结果验证了TXR技术确定吸水前锋位置的准确性.     

X射线衍射-拉伸法测薄膜应力

薄膜应力的测量一直是一个困难的问题。本文尝试用一种新的方法——X射线衍射-拉伸法,对薄膜的应力进行检测,与侧倾法实验结果相比较,X射线衍射-拉伸法更为准确与可靠。     

Activation of hydrogen storage materials in the Li–Mg–N–H system: Effect on storage properties

We investigate the thermodynamics, kinetics, and capacity of the hydrogen storage reaction: Li₂Mg(NH)₂ + 2H₂  Mg(NH₂)₂ + 2LiH. Starting with LiNH₂ and MgH₂, two distinct procedures have been previously proposed for activating samples to induce the reversible storage reaction. We clarify here the impact of these two activation procedures on the resulting capacity for the Li–Mg–N–H reaction. Additionally, we measure the temperature-dependent kinetic absorption data for this hydrogen storage system. Finally, our experiments confirm the previously reported formation enthalpy (ΔH), hydrogen capacity, and pressure–composition–isotherm (PCI) data, and suggest that this system represents a kinetically (but not thermodynamically) limited system for vehicular on-board storage applications.     

X-ray Fluorescence Uptake Measurement of Functionalized Gold Nanoparticles in Tumor Cell Microsamples

Quantitative cellular in vitro nanoparticle uptake measurements are possible with a large number of different techniques, however, all have their respective restrictions. Here, we demonstrate the application of synchrotron-based X-ray fluorescence imaging (XFI) on prostate tumor cells, which have internalized differently functionalized gold nanoparticles. Total nanoparticle uptake on the order of a few hundred picograms could be conveniently observed with microsamples consisting of only a few hundreds of cells. A comparison with mass spectroscopy quantification is provided, experimental results are both supported and sensitivity limits of this XFI approach extrapolated by Monte-Carlo simulations, yielding a minimum detectable nanoparticle mass of just 5 pg. This study demonstrates the high sensitivity level of XFI, allowing non-destructive uptake measurements with very small microsamples within just seconds of irradiation time.     

Influence of molybdenum on passivation of polarised stainless steels in a chloride environment

Polarised specimens of AISI 304L and 316L stainless steels (SS) were studied using X-ray photoelectron spectroscopy in conjunction with Ar⁺-ion sputtering. A 5% NaCl test solution was used at room temperature. The polarised passive films formed consist mainly of chromium oxide and hydroxide and a small proportion of iron oxides. The composition of the films depend strongly on the potential. Chloride and molybdenum ions appear when the AISI 316L SS alloy is polarised at a potential close to pitting potential.     

Synthesis and characterization of poly acrylic acid/graphite oxide nanocomposite

1　INTRODUCTIONOrganic intercalatedlayeredsolidshavebeenstudiedbyscientistsindifferentfieldsformanyyearsbecauseoftheirnew physicalandchemicalpropertiessuchaselectricalproperties[1] ,mechanicalproper ties ,thermalbehavior[2 ] ,surfaceandinterfacialproperties[3] .Graphiteoxide (GO)hasbeenstudiedformany years ,itsstructuralmodel[4 6 ] ,formationprocessandkinetics[7,8] havebeenstudiedindetail.IthasbeenreportedthatGOpossessesC OHande poxidefunctionalgroups[9] whichmakegraphiteox ideeasilyabs…     

Q390高强抗震钢板残余应力检测方法对比及分析

利用盲孔法、X-Ray法、中子衍射法和超声法对Q390高强抗震板及U形弯曲件进行残余应力检测,并对这4种方法测试得到的应力结果进行分析研究。结果表明,以上4种检测方法均要考虑其特定的检测应用范围,X-Ray法针对钢板表面下微米级深度的微米级晶格尺度范围局部点应力进行检测,中子衍射法可在毫米级尺度局部区域进行应力检测,盲孔法反映的是因毫米尺度钻孔导致的钢板表面孔周边的应力变化,超声法则可以通过连续扫描检测整个钢板残余应力的宏观分布变化。因此,对于工业钢板,超声法测试残余应力更加科学、合理、准确。同时,通过U形试样建立稳定的应力应变场,利用超声设备使用不同参考态对Q390高强抗震板弯曲件及退火弯曲件进行测试,结果表明,测试参考态的选取对应力测试结果影响很大,材料各向异性的影响对应力测试结果不可忽视。     

高压粉末制样-X射线荧光光谱法测定海洋沉积物中28种组分

常规粉末压片制样是一种简单、高效的绿色环保制样技术,但是应用于某些沉积物样品制备存在样片表面粗糙和粉末容易脱落的问题。实验采用高于常规的压力进行样品制备,建立了X射线荧光光谱法(XRF)分析海洋沉积物样品中包括硫、氧化钠、氧化镁、三氧化二铝、二氧化硅、五氧化二磷、氧化钾、氧化钙、二氧化钛、氧化锰、三氧化二铁、钴、镍、铜、锌、钒、铬、镓、铌、锆、钇、锶、铷、铅、钡、镧、钕和铪在内的28种主、微量组分的方法。探讨了压力为300 kN和1 600 kN时的制样效果,并尝试引入BP神经网络模型利用其非线性拟合能力校正主量组分的基体效应。结果表明,采用1 600 kN压力制备的样片,表面致密、光滑、不龟裂和不掉粉,制样重复性和测试精密度也有较大提高。以55个有证标准物质中17种组分的数据集为训练样本,建立了海洋沉积物样品中主、微量组分的遗传算法-BP神经网络预测模型。按照实验方法对各组分含量相对较低的实际样品连续测试12次,计算得方法的检出限在 0.63～634 μg/g之间;精密度试验结果表明,各组分测定值的相对标准偏差(RSD, n=7)为0.16%～25.1%。方法用于海洋沉积物实际样品分析,其分析结果与国标法的测定结果吻合,能够满足海洋沉积物样品中多种组分准确分析的要求。