Scanning electron microscopy subsequent to a combined treatment of NaOCl and EDTA in some non-collagenous calcified matrixes

Using backscattered electron (BSE) imaging and scanning electron microscopy, subsequent to a combined treatment of sodium hypochlorite (NaOCl) and ethylenediamine tetra-acetic acid (EDTA) or only with EDTA etching, we observed some structures of non-collagenous calcified matrixes with the aim of revealing the correlation of deposition between calcification degree and organic amount. In human tooth enamel, the NaOCl-EDTA method eroded more intensively the hypocalcified prisms of enamel tufts containing a relatively large amount of EDTA-insoluble organic matter than the hypercalcified normal prismatic enamel containing a small amount of the organic matter. Afibrillar cementum, one of the non-collagenous calcified tissues similar to the enamel, has been reported to consist of organic-rich and poor incremental lamellae. The BSE imaging showed an alternation pattern of hypocalcification and hypercalcification. The hypocalcified lamellae were retained by EDTA etching, while the hypercalcified lamellae showed a resistance against the NaOCl-EDTA method. In the non-collagenous calcareous concretions of human pineal body, organic-rich and poor, and hyper- and hypocalcified incremental lamellae have been reported. The deposition pattern of calcification degree and organic amount was similar to that in afibrillar cementum, and the hypercalcified lamellae showed a resistance against the NaOCl-EDTA method. In conclusion, the high and the lower calcified regions of non-collagenous calcified matrixes contained smaller and larger amounts of EDTA-insoluble organic matter respectively. Moreover, scanning electron microscopy subsequent to the NaOCl-EDTA method corresponding to the BSE imaging clearly showed fine calcified structures compared with the BSE imaging.     

Scanning transmission electron microscopy and its application to the study of nanoparticles and nanoparticle systems

Scanning transmission electron microscopy (STEM) techniques can provide imaging, diffraction and spectroscopic information, either simultaneously or in a serial manner, of the specimen with an atomic or a sub-nanometer spatial resolution. High-resolution STEM imaging, when combined with nanodiffraction, atomic resolution electron energy-loss spectroscopy and nanometer resolution X-ray energy dispersive spectroscopy techniques, is critical to the fundamental studies of importance to nanoscience and nanotechnology. The availability of sub-nanometer or sub-angstrom electron probes in a STEM instrument, due to the use of a field emission gun and aberration correctors, ensures the greatest capabilities for studies of sizes, shapes, defects, crystal and surface structures, and compositions and electronic states of nanometer-size regions of thin films, nanoparticles and nanoparticle systems. The various imaging, diffraction and spectroscopy modes available in a dedicated STEM or a field emission TEM/STEM instrument are reviewed and the application of these techniques to the study of nanoparticles and nanostructured catalysts is used as an example to illustrate the critical role of the various STEM techniques in nanotechnology and nanoscience research.     

Scanning electron microscopy used to measure the feature dimensions of a nanoscale test pattern on a silicon surface

A method is proposed for nanoscale dimensional metrology with the scanning electron microscope in the case of an array of trapezoidal ridges on a silicon surface, the minimum feature size being comparable with the effective beam diameter. The method is tested by measuring the top width of an individual ridge, which lies between 14 and 24 nm. The method works at accelerating voltages higher than 15 kV.     

酵母常规透射电镜样品制备方法的比较与改进

透射电镜技术中前期样品制备是获得最接近样品真实结构信息的关键。本文选择酵母为观察对象,运用常规样品制备技术,观察不同缓冲液、不同脱水时间和脱水温度对酵母超微结构的影响,优化了酵母常规透射电镜前期制样方案。     

Scanning electron microscopy and energy-dispersive X-ray microanalysis studies of afibrillar cementum and cementicle-like structures in human teeth

We examined afibrillar cementum (AFC) and cementicle-like structures (CLS) in human teeth by scanning electron microscopy and energy-dispersive X-ray microanalysis. The AFC showed a spur- or island-, plate- and mass-like structure with appositional laminations, while large masses in the enamel fissures enclosed CLS showing concentric appositional rings. Such AFC was observed in enamel fissures, an abnormal enamel pit, dens invaginatus and root furcations with enamel droplets, as well as on the cervical enamel surfaces, where ameloblasts are differentiated at the later or last stage of enamel formation. Cementicle-like structures were occasionally found independent from AFC and some CLS contained epithelial cell-like or ameloblast-like remnants in the core, surrounded by a few or many concentric rings. In addition, cementicles (CEC) in the root furcations also contained the remnants of Malassez's epithelial-rest cells surrounded by a few concentric rings. In some areas, AFC was mixed with enamel structures. These results show that the organic material in some parts of AFC and CLS may be derived from epithelial cells similar to that of CEC. Calcification values of AFC and CLS were significantly higher than that of fibrillar cementum, and the minute crystals are probably apatite.     

Scanning electron microscopy and cathodoluminescence study of the epitaxial lateral overgrowth (ELO) process for gallium nitride

Traditional epitaxial growth of GaN by metalorganic vapor phase epitaxy (MOVPE) on mismatched substrates such as sapphire or SiC produces a columnar material consisting of many hexagonal grains ∼0.2–1.0 μm in diameter. The epitaxial-lateral-overgrowth (ELO) process for GaN creates a new material: single-crystal GaN. We have studied the ELO process for GaN grown by MOVPE in a vertical flow rotating substrate reactor. Characterization consisted of plan-view SEM and vertical-cross-section TEM studies, which revealed a large reduction in dislocation density in the overgrown regions of the GaN. Panchromatic and monochromatic cathodoluminescence images and spectra were used to study the spatial variation of the optical properties within the GaN ELO samples. The effects of growth temperature and stripe material on the overgrown layers were examined. Through the use of a higher substrate temperature during growth and the use of a SiN_x stripe material, the overgrown crystal shape has a smooth 2D top surface with vertical sidewalls. Applying a second ELO step, rotated by 60°, over a fully coalesced ELO layer yields a further reduction of defects in GaN overgrown surfaces.     

Observation of dislocations in a silicon phototransistor by scanning electron microscopy using the barrier electron voltaic effect

Silicon planar phototransistors crossed by slip planes were examined both by X-ray topography and by conductive mode scanning electron microscopy using the barrier electron voltaic effect current as video signal. Only a few of the dislocations visible in the topographs gave rise to contrast in the scanning electron micrographs. This observation of single dislocations by means of the barrier electron voltaic effect is particularly valuable for the study of the role of defects in device failure and production yields as it renders visible only the electrically effective defects. Quantitative analysis of the barrier electron voltaic effect short circuit current obtained on scanning across an electrically effective dislocation provides a new means for measuring the electrical properties of dislocations. Repeated scanning produced lines of enhanced contrast across the surfaces of the devices. These lines were visible in surface X-ray topographs. This observation is believed to be due to beam induced damage in the oxide and interface region.     

Scanning electron microscopy study of the cross section of intermetallic compound in the solder ball on the plastic ball grid array package following reliability tests

The 63Sn-37Pb solder ball (φ=300 μm) was attached to gold-nickel-plated plastic ball grid array (PBGA) substrates, with gold and nickel thicknesses of 0.6 μm and 7 μm, respectively. The thickness of the intermetallic compound (IMC) in solder balls was measured following each instance of infrared (IR) reflow (90 sec at 230 °C), level II preconditioning, a pressure cooking test (for 96 h or 168 h), and a temperature cycle test (with 500 or 1,000 cycles). Scanning electron microscopy (SEM) was used to identify the cross-section sites of the solder balls following testing. Following all the reliability tests, the IMC demonstrated that an IMC thickness exceeding 5 μm will reduce the solder ball shear strength owing to diffusion of Ni into the solder balls.     

电镜及能谱在失效分析中的应用

本文对乌石化化肥厂动力车间 0 2P1 1泵出口管线爆管失效分析的过程进行了全面分析。乌石化化肥厂动力车间的 0 2P1 1泵出口管线于 2 0 0 4年 2月 16日发生爆管。经查该管的规格为 :16 8mm×18mm ;材质为 :STPT38;所输送介质为 :热水、温度为14 0℃、压力为 :13.4MPa ,该管运行至今已经 19年。为查明该管线的失效原因 ,对爆口内表面的凹坑、斜棱及爆口处做了以电镜、能谱、宏观、测厚、化分、力学性能及金相等的一系列检验手段。对送检的爆管进行宏观检验。观察到该爆口位于化肥厂动力车间 0 10 2P1 1泵出口大小头后弯头附近的直管上…     

Efficient and accurate analysis of mitochondrial morphology in a whole cell with a high-voltage electron microscopy

Mitochondria in all eukaryotes are essential organelles responsible for adenosine triphosphate synthesis, calcium homeostasis and steroidogenesis. Because the structure and distribution of mitochondria are highly diverse depending on their function and cellular conditions, it is important to develop a rapid and accurate method to assess their morphology. In this study, we visualize whole mitochondria in cultured cells using high-voltage electron microscopy (HVEM). Compared with conventional transmission electron microscopic approaches, the present method does not require thin sectioning and thus requires less time for image acquisition and processing. Furthermore, compared with fluorescence-based light microscopic approaches, our method provides more accurate size information. Thus, we propose that HVEM is a useful tool for rapid and accurate analysis of mitochondrial morphology and distribution in a cell.     

Development of a magnetizing stage for in situ observations with electron holography and Lorentz microscopy

A magnetizing stage, by which approximately horizontal magnetic fields can be applied to thin-foiled specimens, has been developed so that magnetization process can be observed in situ with electron holography and Lorentz microscopy. It is possible to apply magnetic field up to 200 Oe without serious image distortion by utilizing the magnetizing stage, beam-deflection-back coils and a magnetically shielded objective lens. The devised system can be used to studies of magnetization processes in many soft magnets.     

扫描电镜在无源外科植入物检测中的应用综述

超微结构技术与无源外科植入等生物医学的交叉融合,使得相关研究的尺度向更直观和更微观的方向延伸.无源外科植入物的安全性能及与人体接触部分的生物相容性和生物稳定性受其原料和结构组成特点的影响.扫描电子显微技术将植入物的超微界面体系可视化,是当今无源外科植入等生命科学研究的前沿方向之一.本文介绍了扫描电子显微技术结合能谱分析...     

Scanning tunneling potentiometry study of electron reflectivity of a single grain boundary in thin gold films

Spatial variations of the local electric field in current-carrying thin gold films were studied with a scanning tunneling microscope on a nanometer scale. With a refined scanning tunneling potentiometry technique, it was possible to determine the local electric fields within single grains. At grain boundaries, we observe potential drops on length scales of less than 1 nm which exceed the potential difference within a grain greatly. We interpret our findings by applying a theory that models grain boundaries as barriers with a reflectivity R for the conduction electrons. With the assumption of isotropic background scattering within each grain, we determine the local current-density j(x,y) that passes a grain boundary. From that, we obtain the reflectivity of individual grain boundaries and find values ofR = 0.7toR = 0.9 which is much higher than expected from macroscopic experiments.     

Scanning capacitance microscopy and the role of localized charges in dielectric films: Infering or challenging?

Scanning capacitance microscopy (SCM) is considered a suitable technique to examine dopant profiles and to provide images of the charge carrier distribution in real device structures. A drawback of the application is the sensitivity of the method to different kinds of charges in the surface passivation layer. For a systematic study silicon structures with stripe patterns of different doping concentrations, covered either by a native oxide or by a thermally grown silicondioxide layer, were examined. The dependence of the dC/dV characteristic on the sweep rate of the tip bias and on the bias sweep direction was analyzed. Local charge trapping in the passivation layer was estimated from shifts of the peak position of the dC/dV versus V curves. It is demonstrated as to how features related to the charge trapping in the passivation layer and induced by a certain dc bias at the tip superimpose the dopant related features in the SCM image.     

Visualization of the interaction between blood vessels and podocytes in the mouse embryonic glomerulus using a barium-infusion method for scanning electron microscopy

The present study revealed three dimensionally the formation of epithelial cells and vascular capillaries in glomeruli of the kidney of the mouse embryo. Barium sulphate was infused through the umbilical vessel of 16.5-17.5-day embryos and the backscattered electron (BSE) image and the secondary electron (SE) image of the identical area of glomeruli were obtained by scanning electron microscopy (SEM). The BSE images directly showed the vascular structure of the glomerulus, while the SE images showed a developmental process of podocytes from epithelial cells. Podocytes were more closely located to the vascular capillary than other epithelial cells. These findings were compared with those obtained in the resin cast model of glomeruli. Thus, the metal infusion-SEM method described here can trace the process of formation of urine filtration barrier in the mouse embryonic glomerulus.     

A review of focused ion beam technology and its applications in transmission electron microscopy

The role of focused ion beam (FIB) fabrication in the development of sample preparation techniques for transmission electron microscopy (TEM) has been described in this paper. Since the repeatability of FIB sampling and TEM observations has become important, the microsampling and in situ lift-out methods are currently in wide use. Furthermore, artifacts induced during FIB milling and the consequent difficulties with energy dispersive X-ray spectroscopy are detailed. The remarkably increased capability of scanning ion microscopy and its applications are also discussed.