金刚石压腔蛇纹石原位拉曼光谱研究

在金刚石压腔中,运用激光拉曼光谱技术对高压下蛇纹石矿物结构及其稳定性进行了原位观测与研究。实验获得蛇纹石在常温下从0.1～5 140MPa的拉曼光谱数据。研究发现,蛇纹石低频拉曼谱峰388,471,692和705cm-1随压力增加有规律地向高频偏移;层内羟基3 664cm-1峰和层间羟基3 696cm-1峰与压力呈明显的正相关性。层内羟基3 664cm-1峰随压力变化的斜率为3.3cm-1.GPa-1,层间羟基3 696cm-1峰在2.0GPa时斜率由8.3cm-1.GPa-1变为1.1cm-1.GPa cm-1。在实验温压条件下,蛇纹石未发生脱水作用。     

硅酸盐型红土镍矿石的红外光谱研究:印尼与中国不同产地矿石样品的对比

选择印尼苏拉威西岛Kolonodale和中国云南元江两处红土型镍矿床中的硅酸盐型镍矿石作为研究对象,利用X射线衍射和傅里叶红外吸收光谱分析技术,系统对比研究了不同产地红土型镍矿石的矿物学属性。研究结果表明,不同类型的硅酸盐型红土镍矿石各自显示出独特的红外光谱特征,这有助于指导对该类型矿石进行分类。其中,印尼Kolonodale矿床的硅酸盐型红土镍矿石可细分为蛇纹石类、蒙脱石+蛇纹石类和硅镁镍矿类等三种不同类型,中国元江矿床的硅酸盐型红土镍矿石可细分为蛇纹石类和滑石+蛇纹石类等两种类型,且元江镍矿石中矿物结晶度普遍优于印尼镍矿石。利用红外吸收光谱在区分矿物多型方面的优势,明确了利蛇纹石是两个矿床中蛇纹石类红土镍矿石的主要矿物类型,而未发现纤蛇纹石和叶蛇纹石存在的明显证据。红外吸收光谱特征还指示,矿石中蛇纹石类载镍矿物在OH摆动带的频率发生变化能指示Ni(Fe)对Mg的类质同象置换。随着Ni(Fe)对Mg置换比例的增大,蛇纹石矿物中的OH摆动带向高频移动。     

Noninvasive methods for the investigation of ancient Chinese jades: an integrated analytical approach

This paper reports on an integrated analytical approach for the noninvasive characterization of Chinese nephrite samples, encompassing both geological reference specimens and museum objects. Natural variations induced by cationic substitutions, as well as human-induced alterations such as heating, which both affect color, are the focus of this contribution. Totally noninvasive methods of analysis were used, including X-ray fluorescence spectroscopy, Raman microspectroscopy, visible reflectance spectroscopy and X-ray diffraction; moreover, the feasibility of using a portable Raman spectrometer for the in-field identification of jades has been demonstrated. Fe/Fe+Mg (% p.f.u.) ratios of the jades have been calculated based on hydroxyl stretching Raman bands, which will provide an important addition to similar data that are being collected at major museums in the Western and Eastern hemispheres.      

基于蛇形光路的PET探测器作用深度提取方法

为实现正电子发射断层成像(Positron Emission Tomography,PET)探测器的作用深度(Depth Of Interaction,DOI)信息获取,本文提出一种基于分光技术的探测器设计方案.探测器采用晶体单元与硅光电倍增管(Silicon Photomultiplier,SiPM)一对一耦合、蛇形光路的设计和单端Anger加权读出方法进行DOI解码.基于GATE软件进行蒙特卡罗模拟,建立8×1的LSO晶体阵列(单根晶体尺寸3.1×3.1×20mm3);模拟泛场照射获取位置查找表;并进行不同深度的模拟,获得各晶体在各深度的空间分辨率.结果显示所模拟的探测器模块DOI分辨率在1.0~6.7mm之间,平均值为3.2mm.本文提出的基于蛇形光路的PET探测器方案能在维持系统成本和复杂度的前提下实现DOI解码,提升PET系统的成像性能.     

钙长石质玉中钙铬榴石的谱学研究

所研究钙长石质玉中的绿色矿物是以钙铬榴石为主的石榴石,钙铬榴石在天然条件下非常稀有,颜色为翠绿色,品质高的钙铬榴石可与翡翠、祖母绿相媲美。前人对石榴石系列的其他端元矿物具有较为充分的研究,但对钙铬榴石的研究较少,且未见对钙长石质玉中钙铬榴石光谱特征的相关报道。使用JXA-8230电子探针确定样品石榴石平均组分为Uvt_49.66Grs_36.04Adr_13.58Pr_p0.67Sps_0.06,为以钙铬榴石为主的钙系石榴石。经Bruker Senterra R200L拉曼光谱仪测定样品拉曼位移为1 000,890,879,830,618,589,530,508,399,370,270,240和176 cm-1,受不同三价阳离子Cr3+,Al3+和Fe3+替代的相互影响而发生相应的偏移;用Bruker Vertex80红外光谱仪测定样品红外振动频率为1 019,951,908,844,826,721,669,608,538,496,462,430和413 cm-1,受不同组分晶胞体积及三价阳离子的质量分数影响,发生规律性振动偏移;通过Jasco MSV-5200显微紫外-可见光谱仪及近红外分光光度计测定样品,可见区Cr3+宽吸收带为439和613nm,存在453和685 nm吸收肩峰,同时可见Fe3+ 371 nm吸收肩峰,钙铬榴石主要致色离子为Cr3+。钙长石质玉中钙铬榴石的详细谱学研究为稀有钙铬榴石矿物的鉴定提供了丰富的谱学数据,为相似品独山玉进行区分奠定基础。     

浙江三个新石器时代遗址出土玉玦科技分析

玉玦是我国新石器时代广泛出现的一类重要玉器。环太湖流域新石器时代遗址中出土的大量玉玦,具有鲜明时代和地域特征,为探索中国玉文化起源和传播提供了重要实物。为获取环太湖流域新石器时代玉玦的基础材料学信息(如主要矿物组成、硬度等),以及探索玉料随时间演变规律和可能的原料来源,本文以浙江省境内3个代表性新石器时代遗址--田螺山、仙坛庙和江家山遗址出土的玉玦为研究对象,采用X射线衍射(XRD)和质子激发X射线荧光(PIXE)分析技术对其进行了无损分析检测。研究结果表明： 从河姆渡文化至崧泽文化晚期,所分析玉玦的主要组成矿物为萤石、迪开石、石英、白云母、透闪石和蛇纹石等,以萤石、玉髓和迪开石为主,且时代早于透闪石和蛇纹石。结合已有的研究成果,探讨了相关遗址出土玉玦的原料随时间变化特征、原料来源,以及玉玦的材料学特征与加工工艺之间的内在联系。     

Stretchability and compliance of freestanding serpentine-shaped ribbons

High-performance stretchable electronics have to utilize high-quality inorganic electronic materials such as silicon, oxide or nitride dielectrics, and metals. These inorganic materials usually crack or yield at very small intrinsic strains, for example, 1%, whereas bio-integrated electronics are expected to at least match the stretchability of bio-tissues (20%) and deployable structure health monitoring networks are expected to expand from wafer scale (several centimeters) to cover macroscopic structures (several meters). To minimize strains in inorganic materials under large deformation, metallic and ceramic films can be patterned into serpentine-shaped ribbons. When the ribbon is stretched, some sections of the ribbon can rotate and/or buckle to accommodate the applied displacement, leaving much smaller intrinsic strain in the materials compared to the applied strain. The choice of the shape of the serpentine depends on systematic studies of the geometric variables. This paper investigates the effect of serpentine shapes on their stretchability and compliance through theoretical, numerical, and experimental means. Our closed-form curved beam solutions, FEM results, and experimental measurements have found good agreement with one another. Our results conclude that in general, the narrower ribbon, the larger arc radius and arc angle, and the longer arm length will yield lower intrinsic strain and effective stiffness. When the arm length approaches infinite, the stretchability can be enhanced by several orders. A few unexpected behaviors are found at arc angles that are close to straight bars. With additional practical constraints such as minimum ribbon width and finite overall breadth, the optimal serpentine shape can be accurately determined using our closed-form analytical solution.     

Investigation of the Reaction of Roasted Serpentine Ore with Some Ammonium Salts

The reaction between roasted serpentine ore and ammonium sulfate was studied at the range of temperature 250–1000°C using different molar ratios to determine the maximum extraction of magnesia and also to characterize the different reaction products. The maximum extraction of MgO from the roasted ore reached 92.4% at 400°C. It was found from XRD that ammonium magnesium sulfate [(NH₄)₂Mg₂(SO₄)₃] was produced as the main product at 400°C, which decomposes to magnesium sulfate at 500–600°C. The last compound decomposes to magnesium oxide at 900–1000°C. Thermal analysis of the reaction mixture confirmed the results obtained by XRD. Extraction of magnesia by ammonium chloride at 300–400°C showed low percentage of extraction (7.8%). Comparison was made between using ammonium chloride instead of sulfate taking into consideration the thermal decomposition products of both ammonium salts. Extraction of magnesia from the roasted ore by aqueous ammonium sulfate or ammonium chloride showed good results.     

Microchip electrophoresis of N-glycans on serpentine separation channels with asymmetrically tapered turns

We designed and fabricated microfluidic devices with serpentine separation channels and asymmetrically tapered turns, thus allowing high efficiency separations and minimizing band broadening associated with the “racetrack” effect. We evaluated the performance of these devices by measuring the variation in separation efficiency with separation length, electric field strength, taper ratio of the turns, and number of turns. N‐Glycans derived from ribonuclease B and labeled with 8‐aminopyrene‐1,3,6‐trisulfonic acid were electrophoretically separated on serpentine channels with separation lengths of 11, 18, 22, and 36 cm at electric field strengths from 750 to 1750 V/cm. Separations on the 36‐cm channel produced plate numbers up to 940 000 with an analysis time under 3.1 min, whereas separations on the 22‐cm channel had a shorter analysis time (less than 1.25 min), still with respectable efficiencies (up to 600 000 plates). Turn‐induced dispersion was minimized with taper ratios 2 and 3, whereas having two or four 180° turns along with the separation length did not impact the overall efficiency. The developed device was used to analyze native and desialylated N‐glycans derived from the blood serum of an ovarian cancer patient and a disease‐free individual. Separation efficiencies similar to that achieved with the model glycans from ribonuclease B were attained for these biological samples.