Investigation of bubbles escape behavior from low basicity mold flux for high-Mn high-Al steels using 3D X-ray microscope

During the continuous casting process of high-Mn high-Al steels,various types of gases such as Ar need to escape through the top of the mold.In which,the behavior of bubbles traversing the liquid slag serves as a restrictive link,closely associated with viscosity and the thickness of liquid slag.In contrast to two-dimensional surface observation,three-dimensional(3D)analysis method can offer a more intuitive,accurate,and comprehensive information.Therefore,this study employs a 3D X-ray microscope(3D-XRM)to obtained spatial distribution and 3D morphological characteristics of residual bubbles in mold flux under different basicity of liquid slag,different temperatures,and different holding times.The results indicate that as basicity of slag increases from 0.52 to 1.03,temperature increases from 1423 to 1573 K,the viscosity of slag decreases,the floating rate of bubbles increases.In addition,when holding time increases from 10 to 30 s,the bubbles floating distance increases,and the volume fraction and average equivalent sphere diameter of the bubbles solidified in the mold flux gradually decreases.In one word,increasing the basicity,temperature,and holding time leading to an increase in the removal rate of bubbles especially for the large.These findings of bubbles escape behavior provide valuable insights into optimizing low basicity mold flux for high-Mn high-Al steels.

Atmospheric transmission algorithm for pulsed X-rays from high-altitude nuclear detonations based on scattering correction

In high-altitude nuclear detonations,the proportion of pulsed X-ray energy can exceed 70%,making it a specific monitoring signal for such events.These pulsed X-rays can be captured using a satellite-borne X-ray detector following atmospheric transmission.To quantitatively analyze the effects of different satellite detection altitudes,burst heights,and transmission angles on the physical processes of X-ray transport and energy fluence,we developed an atmospheric transmission algorithm for pulsed X-rays from high-altitude nuclear detonations based on scattering correction.The proposed method is an improvement over the traditional analytical method that only computes direct-transmission X-rays.The traditional analytical method exhibits a maximum relative error of 67.79% compared with the Monte Carlo method.Our improved method reduces this error to within 10% under the same conditions,even reaching 1% in certain scenarios.Moreover,its computation time is 48,000 times faster than that of the Monte Carlo method.These results have important theoretical significance and engineering application value for designing satellite-borne nuclear detonation pulsed X-ray detectors,inverting nuclear detonation source terms,and assessing ionospheric effects.

OBSERVATION OF THE EFFECT OF S－（－）USNIC ACID SODIUM ON TRICHOMONAS VAGINALIS BY TRANSMISSION ELECTRON MICROSCOPE

This paper reports the ultrastructural changes of trichomonas vaginaiis (T. vag. ) under the action of s-(-)usnic acid sodium in vitro. These changes can be shown by the following results:At first, the degranulation of the rough endoplasmic reticulum (RER) took place, the polyribosomes disaggregated. And then, the Golgi complex and the endoplasmic reticulum dilated. The cytoplasmic matrix presented and inhomogeneous apperance. Finally, the biomembrane loosed and fractured.The cell nuclei presented the karyorrhexis.

Characterization of Li-rich layered oxides by using transmission electron microscope

Lithium-rich layered oxides(LrLOs) deliver extremely high specific capacities and are considered to be promising candidates for electric vehicle and smart grid applications. However, the application of LrLOs needs further understanding of the structural complexity and dynamic evolution of monoclinic and rhombohedral phases, in order to overcome the issues including voltage decay, poor rate capability, initial irreversible capacity loss and etc. The development of aberration correction for the transmission electron microscope and concurrent progress in electron spectroscopy, have fueled rapid progress in the understanding of the mechanism of such issues. New techniques based on the transmission electron microscope are first surveyed, and the applications of these techniques for the study of the structure, migration of transition metal, and the activation of oxygen of LrLOs are then explored in detail, with a particular focus on the mechanism of voltage decay.

Lorentz transmission electron microscopy for magnetic skyrmions imaging

Magnetic skyrmions have interesting properties,including their small size,topological stability,and extremely low threshold current for current-driven motion.Therefore,they are regarded as promising candidates for next-generation magnetic memory devices.Lorentz transmission electron microscopy(TEM)has an ultrahigh magnetic domain resolution(~2 nm),it is thus an ideal method for direct real-space imaging of fine magnetic configurations of ultra-small skyrmions.In this paper,we describe the basic principles of Lorentz-TEM and off-axis electron holography and review recent experimental developments in magnetic skyrmion imaging using these two methods.

Ultrastructural view of colon anastomosis under propolis effect by transmission electron microscopy

AIM： To evaluate the effect of propolis administration on the healing of colon anastomosis with light and transmission electron microscopes. METHODS： Forty-eight Wistar-AIbino female rats were divided into two groups and had colon resection and anastomosis. In group Ⅰ, rats were fed with standard rat chow pre- and postoperatively. The rats in group Ⅱ were fed with standard rat chow and began receiving oral supplementation of propolis 100 mg/kg per day beginning 7 d before the operation and continued until they were sacrificed. Rats were sacrificed 1, 3, 7 and 14 d after operation, and anastomotic bursting pressures measured. After the resection of anastomotic segments, histopathological examination was performed with light and transmission electron microscopes by two blinded histologists and photographed. RESULTS： The colonic bursting pressures of the propolis group were statistically significantly better than the control group. UItrastructural histopathological analysis of the colon anastomosis revealed that propotis accelerated the phases of the healing process and stimulated mature granulation tissue formation and collagen synthesis of fibroblasts. CONCLUSION： Bursting pressure measurements and ultra structural histopathological evaluation showed that administration of propolis accelerated the healing of colon anastomosis following surgical excision.

Thermal Diffusion of Si Atoms at the Interface of Mo/Si Bilayers Studied with a Soft X-ray Emission Microscope

Thermal diffusion of Si atoms at the interface in Mo/Si multilayers was observed with an imaging type soft X ray emission microscope developed by us. It was possible to observe the diffusion with 0.2nm depth resolution in the direction normal to the interface by comparing the emission intensity for exactly the same position. The diffusion coefficient of Si atoms in Mo at 600℃ was roughly estimated to be 6.0×10 17 cm 2/s.

Design of Time-Resolved Shifted Dual Transmission Grating Spectrometer for the X-Ray Spectrum Diagnostics

A new time-resolved shifted dual transmission grating spectrometer （SDTGS） is designed and fabricated in this work. This SDTGS uses a new shifted dual transmission grating （SDTG） as its dispersive component, which has two sub transmission gratings with different line densities, of 2000 lines/mm and 5000 lines/mm. The axes of the two sub transmission gratings in SDTG are horizontally and vertically shifted a certain distance to measure a broad range of 0.1-5 keV time-resolved X-ray spectra. The SDTG has been calibrated with a soft X-ray beam of the synchrotron radiation facility and its diffraction efficiency is also measured. The designed SDTGS can take full use of the space on a record panel and improve the precision for measuring spatial and temporal spectrum simultaneously. It will be a promising application for accurate diagnosis of the soft X-ray spectrum in inertial confinement fusion.

Specimen preparation of aluminum alloy powders for transmission electron microscopy

By nickel electroplating at room temperature, the specimen preparation of ultra sonic gas atomized aluminum alloy powders for observation in transmission electron microscope was carried out. The advantages of this technique are simple technologically and convenient practically. The nickel and the powders combine well in the plated sheet which can be thinned by ion milling. The powders in the thinned sheet possess large thinned area and can be examined in common TEM for the studies of their microstructure.

X-ray phase-sensitive microscope imaging with a grating interferometer:Theory and simulation

A general theoretical framework is presented to explain the formation of the phase signal in an x-ray microscope integrated with a grating interferometer,which simultaneously enables the high spatial resolution imaging and the improved image contrast.By using this theory,several key parameters of phase contrast imaging can be predicted,for instance,the fringe visibility and period,and the conversion condition from the differential phase imaging(DPI)to the phase difference imaging(PDI).Additionally,numerical simulations are performed with certain x-ray optical components and imaging geometry.Comparison with the available experimental measurement[Appl.Phys.Lett.113063105(2018)]demonstrates the accuracy of this developed quantitative analysis method of x-ray phase-sensitive microscope imaging.

A rapid and convenient experimental method of absolutely calibrating transmission of x-ray flat-response filter

We develop a rapid and convenient experimental method of absolutely calibrating the transmission of an x-ray flatresponse filter. The calibration experiment is performed on a small laser-target facility, and a set of high resolution holographic flat-field grating spectrometers is used as a discrimination system of the laser-produced x-ray source. Given that the holographic flat-field grating has a relatively large width, the grating is divided into two regions for use in that direction,where one region has the filter added and the other region does not. The filter transmission is determined by dividing the x-ray signal counts detected when the filter is in the line of sight by those detected when the filter is out of the line of sight.We find that the calibration results of this experiment agree with the calibration results using a synchrotron radiation source,as well as simulation results. Our method is not only highly reliable but also rapid and convenient.

The Method of Testing for Asbestos in Electronic and Electric Products through Polarizing Microscope and X-Ray Diffraction

Asbestos is widely applied in such sectors as manufacturing automobiles, tractors, chemical industrial equipment, and electric equipment. Asbestos fiber is harmful to human health. Therefore, the technology of testing for asbestos in products is especially important. At present, in our country’s national specifications, there is no determination method or specification that is applicable to the asbestos in electronic and electric products. In this article, the components of asbestos in electronic and electric products are identified using the method of combining polarizing microscope with X-ray diffractometer. This method is simple, fast, highly reliable, and suitable to be widely adopted.

Thermal and Transmission Properties of UV Nonlinear Optical Material——ZnCd(SCN)_4 Crystal

zinc cadmium thiocyanate (ZCTC), ZnCd(SCN)_4, has been discoveredas a UV second-order nonlinear optical coordination crystal. Titsthermal and transmission Properties are reported. The thermaldecomposition is characterized by using the X-ray Powder diffraction(XRPD) and infrared (IR) spectroscopy at room temperature. TheAbsorptions of intrinsic ions and ZCTC in a solution state arediscussed as well as Transmission properties of the ZCTC crystal. Aneffective method of reducing the surface Reflection loss of ZCTCcrystal is introduced.

Assessing high-energy x-ray and proton irradiation effects on electrical properties of P-GaN and N-GaN thin films

The effects of ionizing and displacement irradiation of high-energy x-ray and 2-MeV proton on GaN thin films were investigated and compared in this study.The electrical properties of both P-GaN and N-GaN,separated from power devices,were gauged for fundamental analysis.It was found that the electrical properties of P-GaN were improved as a consequence of the disruption of the Mg-H bond induced by high-dose x-ray irradiation,as indicated by the Hall and circular transmission line model.Specifically,under a 100-Mrad(Si)x-ray dose,the specific contact resistance pc of P-GaN decreased by 30%,and the hole carrier concentration increased significantly.Additionally,the atom displacement damage effect of a 2-MeV proton of 1×10^(13)p/cm^(2)led to a significant degradation of the electrical properties of P-GaN,while those of N-GaN remained unchanged.P-GaN was found to be more sensitive to irradiation than N-GaN thin film.The effectiveness of x-ray irradiation in enhancing the electrical properties of P-GaN thin films was demonstrated in this study.

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.

洛伦兹电镜在本科教学中的应用

磁畴是磁性材料中的基础结构,它决定了材料的磁学性质。通过深入研究磁畴,我们可以深入理解磁性材料的特性,优化其性能,进而推动相关应用的进步。洛伦兹电镜,作为一种基于透射电镜的设备,能够观察和分析磁性材料的磁畴结构。其工作原理是利用洛伦兹力使电子束发生偏转,形成明暗相间的图案,从而反映出面内磁矩的不同取向。洛伦兹电镜具有超高的探测灵敏度,其分辨率能够达到纳米量级,因此被广泛应用于磁性材料的研究。将洛伦兹电镜引入本科教学是非常有意义的。通过实际操作,学生可以更好地掌握科学研究的实践技能和方法。同时,学生还能够培养科研素养和科研能力,为他们未来的科研工作打下坚实的基础。因此,将洛伦兹电镜应用于本科教学不仅是可行的,而且是必要的。

ZnO/ZnSe复合材料的制备、 表征及催化特性

对传统的两步水合热法进行改进,采用更加经济、安全、简便的方法在室温下合成ZnO/ZnSe核壳结构。调节原料比例,实验温度,优化了制备ZnO/ZnSe核壳结构的最佳生长与修饰条件,使其具有良好的分散性,时间稳定性,良好的发光特性。研究采用醋酸锌作为锌源,硒粉作为硒源,通过调整原料比例以及实验温度制备出球形核壳结构的ZnO/ZnSe复合材料,用透射电子显微镜(TEM),X射线粉末衍射仪(XRD),紫外可见分光光度计(UV-Vis),光致发光光谱(PL),X射线光电子能谱(XPS)对晶体结构进行了表征,同时对光催化性能进行了研究。结果表明,改变实验条件,原料比例为Zn∶Se=1.6∶1,温度为80℃时生成的ZnO/ZnSe核壳结构对甲基橙溶液有较好的吸光效果。ZnSe过厚的壳层生长会阻碍复合材料对甲基橙的降解效率。实验数据结合理论分析得到了实验最佳条件。

透射电镜表征晶体结构的程序设计原理

表征晶体结构是透射电镜(TEM)的常规分析工作.文章介绍了在透射电子衍射方法下任意单晶体结构与衍射花样之间的关系.为了简化仪器操作和透射电子衍射数据分析,根据前述晶体结构与衍射花样的关系运用Python计算机语言设计智能化采集单晶透射电子衍射数据的操作系统和衍射数据分析程序.介绍了分析程序的主要功能,软件根据输入实际的TEM衍射花样计算出晶体结构、晶胞参数及衍射晶面指数.另外,软件还可以计算出任意晶体在某一取向下的衍射花样特征,例如计算了立方、四方、正交、六方和菱方晶系单晶在基本晶带轴下衍射花样特征.结果为材料研究者表征单晶结构提供了参考或有用的工具.

无相互作用自由空间电子光学与量子电子显微镜

本文围绕着生物等敏感样品的高分辨透射电子显微成像展开,从电子显微成像等方面论述了透射电子显微镜在敏感样品领域的发展,重点介绍了基于无相互作用测量(IFM)的量子电子相干成像机理,分析了自由空间电子光学中电子IFM对耦合相干电子源和耦合电子传输的要求,量子机制和电子显微镜相结合建立的量子电子显微镜能够从本质上解决高能电子辐照对生物等敏感样品的损伤,将成为敏感样品高分辨无损检测发展史上的里程碑。

二硫化钼在电子束辐照下的缺陷结构演变及其物理机制研究进展

二硫化钼(MoS_(2))丰富的多原子结构赋予了它优异的电学、光学、催化等性能,这引起了人们的极大兴趣。而MoS_(2)中存在的缺陷结构往往会对其性能产生显著的影响,通常认为这种影响是负面的,因此以往的研究几乎都是在尽量避免缺陷结构的产生。但是最近也有一些研究表明MoS_(2)缺陷的存在对其应用起到了积极作用。为了能够更好地利用MoS_(2)的缺陷结构,使其产生积极影响,首先需要了解这些缺陷结构,弄清楚它们的演变方式和相关物理机制,并用来指导MoS_(2)的可控纳米加工和实际应用。本文总结了MoS_(2)不同类型的缺陷结构以及在电子束辐照下MoS_(2)的结构演变行为,从中探究电子束与MoS_(2)缺陷结构交互作用的机理。通过分析传统物理机制的不足,提出了两个全新的概念——纳米曲率效应和电子束非热激活效应,分别从纳米空间限制角度和超快时间限制角度来挖掘这些实验现象背后的深层物理机制。最后,本文还提出了对MoS_(2)缺陷结构调制与纳米可控加工的看法和展望。