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。     

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.     

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.     

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.     

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.     

基于p-FTIR和p-XRF测试组合的大汶口文化蛇纹石质玉器无损检测及产地溯源分析

出土玉器溯源是探索华夏玉器文明起源与演化的关键所在,无损测试技术的进步推动了学术界对出土玉器产地溯源的研究,但至今为止,无损技术仍然是制约出土玉器溯源研究的瓶颈所在。利用便携红外光谱（portable Fourier transform infrared spectroscopy,p-FTIR, 带漫反射附件）+ 便携X射线荧光光谱（portable X-ray flourescence, p-XRF）技术组合对山东省文物与考古研究院发掘的大汶口文化出土蛇纹石质玉器的物相和化学组成进行了无损测试以及出土玉器产地溯源的探索。测试结果显示,大汶口文化的蛇纹石玉存在两种成因类型,其中7件玉器（M1005:3,M1006:4,M1013:12,M20:30,M11,T333:2B①：2,M49:04）属于超基性岩型,Fe,Cr和Ni含量较高,含较多磁铁矿包体,磁性较强,Cr/Ni值小于1且多数小于0.7,与现代泰山玉的产地特征基本一致,最大可能就地取材于附近的泰山山麓,为泰山玉的使用时间提前到5500年前的大汶口文化时期提供了重要的科学依据。另外4件玉器（M2004:1、B型环、M25：26、M26）具有低Fe,Cr和Ni含量,为富镁碳酸盐接触交代变质类型,其来源有待进一步研究确认。上述研究结果确认p-FTIR和p-XRF结合能够实现对考古现场及馆藏多数未知玉器材料的快速鉴定,具有无需制样、矿物类型和元素组成可相互验证、无荧光干扰等优点,对部分特定类型的蛇纹石质出土玉器/材料可进行产地来源分析,是一种有优势的出土玉器无损测试技术组合。     

Sliding friction and wear behaviors of surface-coated natural serpentine mineral powders as lubricant additive

This work aims to investigate the friction and wear properties of surface-coated natural serpentine powders (SP) suspended in diesel engine oil using an Optimal SRV oscillating friction and wear tester. The worn surface was characterized by X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) equipped with energy dispersive spectroscopy (EDS). Results indicated that the additives can improve the wear resistance and decrease friction coefficient of carbon steel friction couples. The 0.5 wt% content of serpentine powders is found most efficient in reducing friction and wear at the load of 50 N. The SEM and XPS analysis results demonstrate that a tribofilm forms on the worn surface, which is responsible for the decrease in friction and wear, mainly with iron oxides, silicon oxides, graphite and organic compounds.     

红外光谱在仿古玉石鉴定中的应用

采用常规宝石学研究方法和红外吸收光谱技术,对市场上常见的仿古玉石进行了研究。红外吸收光谱测试结果表明:市场上常见的仿古玉石,主要为软玉(和田玉)、岫玉和石英质玉石组成。不同种类的仿古玉石,其红外吸收光谱特征存在着明显的差异:软玉在996、463cm-1附近;岫玉在1047、471cm-1附近,并在3665cm-1附近有明显的水的吸收峰;石英质玉石在1106、481cm-1附近。通过红外吸收光谱的测定和分析,可以准确鉴定仿古玉石的玉石品种。     

Curvature induced flow pattern transitions in serpentine mini-channels

Experimental investigation of the phase interactions in two-phase mini-channel serpentine systems is performed with a focus on determining the effect of radius of curvature of the serpentine on two-phase flow pattern transitions. The initial formation of two-phase flow patterns in T-junction contactors and the resulting effect on the flow through serpentine geometries are studied to predict the initiation of bubble breakup and/or coalescence in planar serpentine arrangements. Bubble breakup maps are developed for each of the serpentine geometries, identifying curvature-induced shifts in the transitions between flow patterns.