Energy-dispersive X-ray Spectroscopy for the Quantitative Analysis of Pyrite Thin Specimens

To explore ways to improve the accuracy of quantitative analysis of samples in the micrometer to nanometer range of magnitudes,we adopted analytical transmission electron microscopy(AEM/EDS)for qualitative and quantitative analysis of pyrite materials.Additionally,the k factor of pyrite is calculated experimentally.To develop an appropriate non-standard quantitative analysis model for pyrite materials,the experimentally calculated k factor is compared with that estimated from the non-standard quantitative analytical model of the instrument software.The experimental findings demonstrate that the EDS attached to a TEM can be employed for precise quantitative analysis of micro-and nanoscale regions of pyrite materials.Furthermore,it serves as a reference for improving the results of the EDS quantitative analysis of other sulfides.

Determination of Element Levels of Lagoon from Townships near Cocody City Abidjan Côte D’Ivoire Using Energy Dispersive X-Ray Fluorescence

Eight water bottles from Ebrie lagoon with pollution potency were studied using nuclear chemistry technique and Energy dispersive X-ray fluorescence. This pollution is characterized by pH and conductivity parameters, concentrations average in mg/L of metals such Fe (0.731), Mn (0.345), Cr (0.070), Cu (0.014) and concentrations of nutrients known to be pollutants and toxic for living or-ganisms. These heavy metals are dangerous to the lives, the local inhabitants and also a threat to aquatic life since this water is essential for the economical town, Abidjan. According to the Manganese concentration average (0.345 mg) values that higher than WHO (0.05 mg) value, the main likely source of pollu-tants is anthropogenic, industrial and agricultural. This study also shows the use of materials and lubricants near the lagoon that pollute this water.

Alpha-actinin expression at different differentiating time points from temporal lobe cerebral cortex neural stem cells to neuron-like cells using energy dispersive X-ray analysis

BACKGROUND： Alpha-actinin （ a -actinin） plays a key role in neuronal growth cone migration during directional differentiation from neural stem cells （NSCs） to neurons. OBJECTIVE： To detect in situ microdistribution and quantitative expression of a -actinin during directional differentiation of NSCs to neurons in the temporal lobe cerebral cortex of neonatal rats. DESIGN, TIME AND SETTING： Between January 2006 and December 2008, culture and directional differentiation of NSCs were performed at Department of Histology and Embryology, Preclinical Medical College, China Medical University. Immune electron microscopy was performed at Department of Histology and Embryology and Department of Electron Micrology, Preclinical Medical College, China Medical University. Spectrum analysis was performed at Laboratory of Electron Microscopy, Mental Research Institute, Chinese Academy of Sciences. MATERIALS： Basic fibroblast growth factor, epidermal growth factor, brain-derived nerve growth factor, type-1 insulin like growth factor, and a -actinin antibody were provided by Gibco BRL, USA; rabbit-anti-rat nestin monoclonal antibody, rabbit-anti-rat neuron specific enolase polyclonal antibody, and EDAX-9100 energy dispersive X-ray analysis were provided by PHILIPS Company, Netherlands. METHODS： NSCs, following primary and passage culture, were differentiated with serum culture medium （DMEM/F12 ＋ 10% fetal bovine serum ＋ 2 ng/mL brain-derived nerve growth factor ＋ 2 ng/mL type-1 insulin like growth factor）. MAIN OUTCOME MEASURES： Expression of a -actinin in neuron-like cells was quantitatively and qualitatively detected with immunocytochemistry using energy dispersive X-ray analysis. RESULTS： Immunocytochemistry, combined with electron microscopy, indicated that positive α -actinin expression was like a spheroid particle with high electron density. In addition, the expression was gradually concentrated from the nuclear edge to the cytoplasm and expanded into developing neurites, during differentiation of neural stem cells to neurons. Conversely, energy dispersive X-ray analysis indicated that the more mature the neural differentiation was, and the greater the expression of α -actinin. CONCLUSION： The gradual increase of α -actinin expression is related to growth, development, and maturity of differentiated neuron-like cells, in neonatal rat frontal lobe cortex, at different differentiating time points of NSCs to neurons.

A Hybrid Angular/Energy Dispersive Method to Improve Some Characteristics of Laboratory X-Ray Diffraction

The Energy Dispersive X-ray Diffraction, generally referred as EDXD, has shown to be a valid alternative to the conventional Angular Dispersive X-ray Diffraction, the ADXD. EDXD exhibits several advantages to its AD counterpart, mainly related to the properties of the polychromatic X-ray beam utilized for diffracting, such as higher signal intensities, a wider accessible region of the reciprocal space, a greater transparency of samples, and a parallel data collection of the q-points in the diffraction pattern acquisition. However, the main drawback of poly-chromaticity lays in the fact that the quantities that modulate the scattered intensity in a diffraction measurement depend on the energy. These quantities are the primary X-ray beam spectrum, polarization, and X-ray absorption, the last producing by far the most critical effect because it rapidly changes as a function of energy. Therefore, a detailed knowledge of the energy dependence of all these quantities is required in EDXD in order to process the data correctly and prevent systematic errors. The difficulty in handling the energy-dependent factors complicates the experimental procedure and may make the measurements unreliable. In the present paper, a hybrid method between the ED and AD X-ray Diffraction is proposed to maintain the advantages of the polychromatic nature of the radiation utilized in EDXD, while preventing the problems produced by the energy-dependent quantities.

Energy Dispersive X-Ray Spectroscopy of the Sohnari Member of Laki Formation from Southern Indus Basin of Pakistan

This study determines the geochemical and depositional environment analysis of the sediments of the Sohnari Member of the Laki Formation, Northern Kirthar Fold Belt of Pakistan. The Energy-Dispersive-X-Ray Spectroscopy (EDS) technique is used for the detection of major elements and the effects of shifting depositional climatic conditions of six representative samples which were acquired from the Sohnari Member of the Laki Formation at Lakhra area, Sindh, Pakistan. The sedimentological studies clarify that the sediments the Sonahri Member are relatively immature and most migrated in clastic mode. The availability of Silica shows that the Member was formed due to biochemical precipitation and detrital mode and was deposited at a fast rate of sediment deposition under the fluvio-deltaic depositional system. This is also deduced that the rapid rate of sediment deposition might be created a reducing atmosphere and allowing for the mineralization of sulphur.

The development,performances and applications of the monochromatic X-rays facilities in(0.218–301)keV at NIM,China

Space scientific exploration is rapidly becoming the primary battlefield for humankind to explore the universe.Countries worldwide have launched numerous space exploration satellites.Accurate calibration of the detectors on the ground is a crucial element for space science satellites to obtain observational results.For the purpose of providing calibration for various satellite-borne detectors,multiple monochromatic X-rays facilities have been built at the National Institute of Metrology,P.R.China(NIM).These facilities mainly pertain to grating diffraction and Bragg diffraction,and the energy range of the produced monochromatic X-rays is 0.218–301 ke V.These facilities have a high performance in terms of energy stability,monochromaticity,and flux stability.The monochromaticity was greater than 3.0%.The energy stability of the facility is 0.02%at 25 ke V over 8 h,and the flux stability was within 1.0%at 25 ke V over 8 h.Calibration experiments on the properties of satellite-borne detectors,such as energy linearity,energy resolution,detection efficiency,and temperature response,can be conducted at the facilities.Thus far,the calibration of two satellites has been completed by the authors,and the work on three other satellites is in progress.This study will contribute to the advancement of X-ray astronomy the development of Chinese space science.

Establishment of Energy Dispersive X-ray Diffraction Experimental System With Synchrotron Radiation Under High Pressure

Because the interactions between molecules and atoms in mediums can be dramatically changed by compression, high pressure studies on materials can provide much information on fundamental properties including phase transition and

Elemental Analysis of Soil Phosphorus Neighborhoods Using SEM, Spectral Mapping and GIS

The utility of GIS （geographic information system） methods and spatial statistical analysis on spectral maps of sediment samples were examined. Detailed elemental maps are often constructed using energy dispersive X-ray techniques and SEM （scanning electron microscopy）. The elemental neighborhood associations of a single element, P （phosphorus）, were quantified at a magnification of 3,000 ×. For each of the 170,000 pixels on the images which displayed a strong P concentration, neighborhoods from 0.1μm^2 to 12 μm^2 were examined for associated elemental concentrations. PCA （principal component analysis） revealed two significant neighborhood types associated with P in samples of pH 4, and three neighborhood types at pH 8. These neighborhoods corresponded to Mg-P associations commonly found to be chemically prevalent in river sediments impacted by agricultural operations. Discriminant analysis showed that the greatest accuracy in predicting sample pH could be achieved by using a neighborhood size of 12 ~m2. Potassium at relatively large neighborhood sizes was the element most significant in predicting pH. While many of the chemical associations in close proximity to P could be predicted and explained through mineral solubility, spatial analysis provided some interesting insights into the structure of the samples. Results also indicted differences in the spatial scale associated with different processes.

X-Ray and Mössbauer Study of Magnetic Black Sand from Mayotte Island

Natural magnetic black sands are known from several sites often located in areas of volcanic origin. Their elemental and mineral composition provides information on the geology of their territory and depends on several factors occurred during their formation. A sample of black sand was collected on the seashore of the island of Mayotte in the Indian Ocean and its magnetic part was investigated by means of energy dispersive X-ray spectroscopy (EDS), powder X-ray diffraction (XRD), and MÖssbauer spectroscopy at room temperature. The mineral composition is dominantly magnetite, in good agreement with samples collected in other sites of volcanic origin. Contrary to pure magnetite, a relevant fraction of Ti was detected by EDS. The 16% Ti and 1% Mn content increase the magnetite lattice parameter to 8.4312 (25) Å. The broadening of XRD lines pointed towards a significant degree of disorder. This was confirmed by MÖssbauer spectroscopy and is attributed to the presence of Ti replacing Fe in the magnetite lattice. The presence of Ti modifies the local magnetic field on the Fe sites, leading to a broader and more complex MÖssbauer transmission spectrum with respect to the one of pure magnetite. To study the effect of temperature, samples were heated for 12 hours to 600°C and 800°C in argon and to 1000°C in air. Annealing in argon did not improve the crystallinity while annealing in air caused a complete decomposition of magnetite into hematite and pseudobrookite.

Mossbauer,X-Ray and Magnetic Studies of Black Sand from the Italian Mediterranean Sea

The study of natural magnetic sands is instrumental to investigate the geological aspects of their formation and of the origin of their territory. In particular, Mossbauer spectroscopy provides unique information on their iron content and on the oxidation state of iron in their mineral composition. The Italian coast on the Mediterranean Sea near Rome is known for the presence of highly magnetic black sands of volcanic origin. A study of the room temperature Mossbauer spectrum, powder X-ray diffraction, energy dispersive X-ray spectroscopy, and magnetic measurements of a sample of black magnetic sand collected on the seashore of the town of Ladispoli is performed. This study reveals magnetite as main constituent with iron in both tetrahedral and octahedral sites. Minor constituents are the iron minerals hematite and ilmenite, the iron containing minerals diopsite, gossular, and allanite, as well as ubiquitous sanidine, quartz, and calcite.

Possible Relevance of the Allende Meteorite Conditions in Prebiotic Chemistry: An Insight into the Chondrules and Organic Compounds

The study of the mineral and organic content of the Allende meteorite is important for our understanding of the molecular evolution of the universe as well as the ancient Earth. Previous studies have characterized the magnetic minerals present in ordinary and carbonaceous chondrites, providing information on the evolution of magnetic fields. The interaction of organic compounds with magnetic minerals is a possible source of chemical diversity, which is crucial for molecular evolution. Carbon compounds in meteorites are of great scientific interest for a variety of reasons, such as their relevance to the origins of chirality in living organisms. This study presents the characterization of organic and mineral compounds in the Allende meteorite. The structural and physicochemical characterization of the Allende meteorite was accomplished through light microscopy, powder X-ray diffraction with complementary Rietveld refinement, Raman and infrared spectroscopy, mass spectrometry, scanning electron microscopy, and atomic force microscopy using magnetic signal methods to determine the complex structure and the interaction of organic compounds with magnetic Ni-Fe minerals. The presence of Liesegang-like patterns of chondrules in fragments of the Allende structure may also be relevant to understanding how the meteorite was formed. Other observations include the presence of magnetic materials and nanorod-like solids with relatively similar sizes as well as the heterogeneous distribution of carbon in chondrules. Signals observed in the Raman and infrared spectra resemble organic compounds such as carbon nanotubes and peptide-like molecules that have been previously reported in other meteorites, making the Mexican Allende meteorite a feasible sample for the study of the early Earth and exoplanetary bodies.

Rapid Biosynthesis of Silver Nanoparticles Using Cymbopogan Citratus (Lemongrass) and its Antimicrobial Activity

The present study deals with the rapid green synthesis of silver nanoparticles using fresh leaves of Cymbopogan Citratus(Lemongrass). Silver nanoparticles were formed within 8～10 minutes by microwave irradiation using aqueous solution of Ag NO3(1 m M) with fresh leaves extract of Cymbopogan Citratus. The synthesized silver nanoparticles were characterized by using UV-visible spectrophotometer analysis, nanoparticle tracking analyzer, transmission electron microscope and energy dispersive X-ray spectra. The antibacterial activity of these nanoparticles was studied against multiple drug resistant hospital isolates of E.coli, S.aureus,P.mirabilis and hospital isolates of S. typhi, K.pnuemoniae. Also, the antifungal activity of these nanoparticles was studied against C.albicans(hospital isolate) and A.niger(NCIM 616). The synergistic effect of silver nanoparticles along with antibiotics was also studied against multiple drug resistant hospital isolates and found to be effective. The extracellular synthesis of Silver nanoparticles using leaves of Cymbopogan Citratus appears to be rapid and eco-friendly.

小波变换法在X射线能谱去噪声中的应用

阐述了二进小波变换法的去噪声原理和方法 ,并将其应用于 X射线能谱分析中噪声的去除。实验结果表明 ,该去噪方法能够解决传统平滑方法的不足 ,改善 X射线能谱的定性。

一种新的X射线能谱背景扣除方法

阐述了小波级数和多分辨率分析的基本思想 ,并将之应用于X射线能谱定量分析中的背景扣除 ,取得了良好的效果。实验结果表明 ,该扣除背景的方法不仅计算速度快 ,而且和其它的背景扣除方法相比 。

能量色散X射线荧光分析中改进型基本参数法研究

能量色散X射线荧光分析方法是目前常用的一种多元素分析方法,但该方法检出限和分析精度,受到分析基体的影响。基本参数法是目前一种常用的分析方法,但在使用过程必须获取净峰面积和基体所有成分,而在实际使用时,尤其在分析低含量样品时,净峰面积计算、基体中"暗物质"影响了测量精度,制约了基本参数法的应用。针对基本参数法的不足,将谱线解析方法与基本参数法融合,将重叠峰剥离过程嵌入基本参数法迭代过程中。在含量计算过程中,采用分析样品特征X射线分支比的理论系数,对重叠峰进行剥离,解决能量色散X射线荧光测量中净峰面积计算和定量分析问题;在计算过程中,对"暗物质"进行均一化处理。通过对标准物质测量分析,结果表明对于Ni,Cu,Zn三个元素改进型基本参数法(改进型FP)测量结果准确度高于影响系数法。

能量色散X射线荧光光谱仪研究现状

归纳了能量色散X射线荧光(EDXRF)光谱仪的主要部件及能谱处理算法的研究进展及现状,通过分别对比不同类型高压电源、X射线激发源和探测器在光谱仪上的使用,总结了X射线激发电压、X射线强度和探测器分辨率等对仪器灵敏度和分辨率等指标的影响。通过分别对比不同算法在能谱去噪、本底扣除、谱峰分解及荧光强度提取等方面的应用,分析了各种算法的适用范围,并比较了小波变换、人工神经网络和偏最小二乘法等在能谱分析中的独特优势。阐述了为提高仪器性能亟待解决的问题,并指出了EDXRF仪器的发展趋势及进一步研究该课题的必要性。

基于多分辨率分析的X荧光能谱的除噪与弱峰检测

在对X荧光谱噪声的分析基础上,阐述了多分辨率分析的基本思想,并将之应用于X射线能谱定量分析中的噪声的消除,取得了良好的效果。利用噪声和信号小波变换的性质随尺度的加大而显著不同的特点,运用小波多分辨率分析进行信号噪声的消除,可提高弱峰的检测能力,实验结果表明,该降噪的方法不仅计算速度快,而且和其它的方法相比,对低含量元素形成的弱峰的定量分析结果也更加理想。

燃料电池用磺化聚苯乙烯膜降解机理及其复合膜的初步研究

对用磺化聚苯乙烯 (PSSA)膜组装的质子交换膜燃料电池 (PEMFC)进行寿命实验 ,通过高效液相色谱分析 PSSA膜电池寿命实验期间阴极和阳极侧的排水量 ,能谱分析电池寿命实验前后 PSSA膜断面 S元素含量的分布 ,红外光谱分析 PSSA膜结构的变化 ,根据分析结果推断出 PSSA膜的降解机理 .O2 在阴极还原时产生 H2 O2 中间产物 ,H2 O2 又与电池中微量的金属离子反应产生 HO· 和 HO2 · 等氧化性自由基 ,这些自由基进攻 PSSA膜 α碳上的叔氢而导致膜降解 .膜降解主要发生在电池阴极侧 ,降解过程中苯环和磺酸根同时从 PSSA膜上脱离 .根据 PSSA膜的降解机理设计了 PSSA-Nafion复合膜作为 PEMFC电解质 ,2 5μm厚的 Nafion1 0 1膜位于电池阴极侧 ,该复合膜组装的 PEMFC稳定操作 80 0

基于NMF-PLS对含水量影响下土壤重金属含量反演模型研究

土壤中过高的重金属含量危害巨大,不仅造成了严重的环境污染,而且通过食物链进入人体对人体健康造成严重威胁,所以对重金属检测十分重要。X射线荧光光谱法具有检测时间短、无损检测、检测成本低等特点被广泛使用,然而检测的光谱数据因受到土壤含水量因素的严重干扰,导致直接对土壤重金属含量估算精度较低。以河北省保定市满城区土样为研究对象,对采集的土样进行除杂、过筛、烘干后加入一定量重金属溶液制备不同含水量不同重金属的样本进行检测。对实验中异常数据计算了马氏距离和进行NJW聚类予以剔除,分析了土壤含水量对土壤重金属光谱的影响,结果表明不同含水量间光谱重复性差,随着土壤含水量的增加光谱强度呈非线性降低。采用Savitzky-Golay卷积平滑去噪法和线性本底法对光谱进行预处理,以解决因环境、仪器本身带来的噪声和基线漂移等问题。然后针对于土壤含水量这一主要干扰,采用非负矩阵分解算法进行处理,并使用峰值信噪比这一评价模型确定端元数目,结果表明当端元数目增至10时峰值信噪比趋于稳定波动很小,非负矩阵分解处理后相同重金属含量不同含水量间光谱重复性好、相似性好,并计算了光谱间的相关系数进一步证明了光谱间的相似性。去除含水量对于光谱干扰后建立了偏最小二乘法预测模型,为了验证预测模型的精度,建立了未去除含水量的偏最小二乘法预测模型和使用外部参数正交化法去除含水量建立的偏最小二乘法预测模型,并使用评价参数决定系数(R^2)、交叉验证均方根误差(RMSECV)、平均绝对误差(MAE)和相对分析误差(RPD)进行评价。验证结果表明,相比较未去除含水量建立的模型,使用非负矩阵分解去除含水量建立的偏最小二乘法模型R^2和RPD分别提高了0.0197和1.0292,RMSECV和MAE分别降低了2.3863和1.4396;相对于外部参数正交化法建立的偏最小二乘法模型,R^2和RPD分别提高了0.0099和0.1081,RMSECV和MAE分别降低了0.2447和0.3566,说明了经过非负矩阵分解去噪后建立的模型有效提高了预测的精度和鲁棒性。非负矩阵分解可以有效消除土壤含水量对光谱的影响,在此基础上建立的偏最小二乘法模型实现了土壤重金属含量的反演,为重金属定量检测提供了一定的技术支持。

白云鄂博独居石的振动光谱研究

利用 X射线能谱、红外光谱和拉曼光谱研究了白云鄂博矿区独居石的化学组分和振动特征。结果表明 ,白云鄂博独居石矿物具有复杂的化学成分 ,稀土成分主要是 L a、Ce、Pr和 Nd等轻稀土元素 ,质量分数为 Ce>L a>Nd >Pr。独居石具有十分特征的拉曼和红外光谱 ,特别是 PO3 -4在拉曼光谱中的υ1、υ3 谱带和在红外光谱中的υ1、υ4 谱带是独居石区别其它磷酸盐矿物的重要标志。从