能散X射线能谱数据分析中的基体修正系数最佳化

描述由标样中每个感兴趣元素的相互独立的基体修正系数导出相互关联的最佳基体修正系数的数学物理方法及其运算公式。最佳基体修正系数应用于能散Ｘ射线能谱分析可提高样品中每个感兴趣元素的分析精确度，特别对样品中低于或等于０．３％浓度感兴趣元素的分析，相对误差由２３％下降到１５％。

Scanning electron microscopy coupled with energydispersive X-ray spectrometry for quick detection of sulfuroxidizing bacteria in environmental water samples

Detection of sulfur-oxidizing bacteria has largely been dependent on targeted gene sequencing technology or traditional cell cultivation, which usually takes from days to months to carry out. This clearly does not meet the requirements of analysis for time-sensitive samples and/or complicated environmental samples. Since energy-dispersive X-ray spectrometry(EDS) can be used to simultaneously detect multiple elements in a sample, including sulfur, with minimal sample treatment, this technology was applied to detect sulfur-oxidizing bacteria using their high sulfur content within the cell. This article describes the application of scanning electron microscopy imaging coupled with EDS mapping for quick detection of sulfur oxidizers in contaminated environmental water samples, with minimal sample handling. Scanning electron microscopy imaging revealed the existence of dense granules within the bacterial cells, while EDS identified large amounts of sulfur within them. EDS mapping localized the sulfur to these granules. Subsequent 16S rRNA gene sequencing showed that the bacteria detected in our samples belonged to the genus Chromatium, which are sulfur oxidizers. Thus, EDS mapping made it possible to identify sulfur oxidizers in environmental samples based on localized sulfur within their cells, within a short time(within 24 h of sampling). This technique has wide ranging applications for detection of sulfur bacteria in environmental water samples.

层状钙钛矿结构锰氧化物Ca_3Mn_2O_7的压致结构相变

采用金刚石压砧高压装置 (DAC) ,对层状钙钛矿结构锰氧化物Ca3Mn2 O7的粉末样品进行了高压能散X射线衍射实验。实验结果表明 ,在 0～ 35GPa压力范围内 ,Ca3Mn2 O7晶体结构发生了两次相变。在 1 3GPa左右 ,由原来的四方相转变为正交相 ;在 9 5GPa左右 ,又由正交相向新的四方相转变。

云南红宝石暗色条带改善研究

热处理可以有效地消除云南红宝石中的暗色条带,降低杂色影响,红宝石的红色调明显得以改善。通过能散X射线荧光测得,从红宝石内部析出的元素主要为Fe。吸收光谱测试结果显示,热处理后红宝石的吸收峰强度增强并发生蓝移现象,红色调加强,饱和度提高。

Performance of engineered cementitious composite containing stone slurry powder waste

Most of the materials used in engineered cementitious composite are fine in size to achieve ductile nature.Stone slurry powder(SSP)is an inert material obtained from stone industries as by-product which may cause hazardous impact on environment.In this research work,partial replacement of silica sand(SS)and fine sand(FS)by SSP with different contents(25%and 50%each)for making engineered cementitious composite has been explored.The performance was evaluated on the basis of strength,tensile strain,mid span deflection capacity,ultra-sonic pulse velocity and microstructure.Mechanical strength was found to be increased at 25%SSP in both replacements;whereas,strength decreased slightly at 50%replacement.Tensile strain,mid span deflection and quality of concrete were enhanced with increase in SSP content.Using SSP formed denser cementitious composite can help to save the natural resources and contribute in making green cementitious composite.

Preparation of calcium phosphate coatings on Mg-1.0Ca alloy

The calcium phosphate coatings were prepared by virtue of electrochemical deposition in order to improve the corrosion resistance of Mg-1.0Ca alloys in simulated body fluids.The chemical compositions,structures and morphologies of the coatings were investigated by energy dispersive spectroscopy(EDS),X-ray diffractometry(XRD)and scanning electron microscopy(SEM), respectively.The potentiodynamic electrochemical technique was employed to investigate the bio-degradation behavior of Mg-1.0Ca alloys with Ca-P coatings in Hank's solutions.The experimental results show that the deposited coatings predominately consist of flake-shape brushite(DCPD,CaHPO4·2H2O)crystallites.The corrosion resistance of the substrates with coatings is improved in Hank's solutions significantly.

Ignition-proof mechanism of ZM5 magnesium alloy added with rare earth

The ignition-proof mechanism of ZM5 magnesium alloy added with 0.1% （mass fraction） rare earth （RE） was investigated. The oxide scales and substrates were characterized by scanning electronic microscope （SEM）, X-ray diffraction （XRD）, energy dispersive spectrometer （EDS） and tensile test. And an oxidation model of ZM5 alloy with RE was established. The results show that the ignition temperature of ZM5 alloy is particularly elevated from 654 to 823 ℃, the microstructure is refined, and the tensile strength is slightly improved from 168.2 to 174.6 MPa by adding 0.1% RE. A double-layer oxidation film formed on the alloy surface under high temperature mainly consists of MgO, RE203 and A1203, which is 2.5-3.5 μm in thickness. It is found that the forming of protective oxidation film on the thermodynamics is attributed to RE elements congregating on the surface of molten Mg alloy.

高压下层状钙钛矿结构锰氧化物Ca_3Mn_2O_7的结构相变

采用金刚石压砧高压装置(DAC),对Ca3Mn2O7的粉末样品进行了高压能散X射线衍射实验. 实验结果表明,由于延盐层易被压缩,在压力作用下层状钙钛矿结构锰氧化物Ca3Mn2O7的结构不稳定. 在0～35 Gpa压力范围内,Ca3Mn2O7晶体结构发生了两次相变. 在1.3 Gpa左右,由原来的四方相变为正交相,在9.5 Gpa左右,又由正交相向新的四方相转变.