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[en] The megaspore morphology of 15 species of the genus Selaginella P. Beauv. (Selaginellaceae Willk.) using scanning electron microscopy was carried out. Of the 15 species, megaspore morphology S. arbuscula and S. drepanophylla are reported for the first time. On the basis of megaspore surface ornamentations five major megaspore types are recognized: granulate, tuberculate, verrucate, verrucate-rugulate and reticulate. The morphological characteristics of megaspores are useful in the subgeneric classification. However, the classification using megaspore morphological characteristics showed disagreement with the classifications reported in the literature. Therefore, the subgeneric relationships of the genus Selaginella need to be further studied. (author)
[en] A dynamic transmission electron microscope (DTEM) has been designed and implemented to study structural dynamics in condensed matter systems. The DTEM is a conventional in situ transmission electron microscope (TEM) modified to drive material processes with a nanosecond laser, 'pump' pulse and measure it shortly afterward with a 30-ns-long probe pulse of ∼107 electrons. An image with a resolution of <20 nm may be obtained with a single pulse, largely eliminating the need to average multiple measurements and enabling the study of unique, irreversible events with nanosecond- and nanometer-scale resolution. Space charge effects, while unavoidable at such a high current, may be kept to reasonable levels by appropriate choices of operating parameters. Applications include the study of phase transformations and defect dynamics at length and time scales difficult to access with any other technique. This single-shot approach is complementary to stroboscopic TEM, which is capable of much higher temporal resolution but is restricted to the study of processes with a very high degree of repeatability
[en] Energy dissipation associated with assisted tunneling processes in scanning tunneling microscopy is analyzed and compared with the normal tunnel current. We find that, for high voltages, greater than one volt, the tunneling processes associated with electron-hole pair excitation control the increase in temperature at the microscope's interface
[en] Highlights: ► The damage development process of glass–epoxy laminated composite pinned-joints is experimentally investigated. ► The bearing strengths of pin-loaded glass–epoxy laminate composite with [0°/902°/0°]s and [0°/90°]2s stacking sequences are compared. ► The influences of geometric parameters on failure load and bearing strength of joint are investigated. ► Damage progression is examined by using scanning electron microscopy. -- Abstract: In this paper, the damage development process of glass–epoxy laminated composite pinned-joints is investigated. To determine the effects of joint geometry and stacking sequence on the bearing strength and damage mode, experimental studies were carried out. Two different geometrical parameters which are the edge distance-to-hole diameter ratio (E/D) and plate width-to hole diameter ratio (W/D) were considered. Hence, E/D and W/D ratios were selected from 1 to 5 and 2 to 5, respectively. By observing the effect of material parameters on damage development, composite laminated plates were stacked as two different orientations, [0°/902°/0°]s and [0°/90°]2s. A total of 144 specimens with nine different geometries were tested to obtain the experimental strength and failure mode. Damage progression was examined by using scanning electron microscopy on specimens loaded to ultimate failure and to percentages of their ultimate failure load.
[en] Highlights: → A nano-picker is developed for single cell adhesion force measurement. → The adhesion of picker-cell has no influence to the cell-cell measurement result. → Cell-cell adhesion force has a rise at the first few minutes and then becomes constant. -- Abstract: Cell's adhesion is important to cell's interaction and activates. In this paper, a novel method for cell-cell adhesion force measurement was proposed by using a nano-picker. The effect of the contact time on the cell-cell adhesion force was studied. The nano-picker was fabricated from an atomic force microscopy (AFM) cantilever by nano fabrication technique. The cell-cell adhesion force was measured based on the deflection of the nano-picker beam. The result suggests that the adhesion force between cells increased with the increasing of contact time at the first few minutes. After that, the force became constant. This measurement methodology was based on the nanorobotic manipulation system inside an environmental scanning electron microscope. It can realize both the observation and manipulation of a single cell at nanoscale. The quantitative and precise cell-cell adhesion force result can be obtained by this method. It would help us to understand the single cell interaction with time and would benefit the research in medical and biological fields potentially.
[en] The article reviews the principle of electron microscopy which is used in scanning electron microscope (SEM) and transmission electron microscope (TEM). These instruments are important for the examination and analysis of the microstructural properties of solid objects. Relevance physical concept lies behind the devices are given. The main components of each device are also discussed
[en] The operating conditions of a Scanning Electron Microscope (SEM) i.e., magnification, accelerating voltage, micron mark and film identification labeling, are very important for the accurate interpretation of a micrograph picture. In the old model SEM, the built-in data printing system for film identification can be inputted only the numerical number. This will be made a confusing problems when various operating conditions were applied in routine work. An economical interfacing circuit, therefore, was developed to upgrade the data printing system for capable of alphanumerical labeling. The developed circuit was tested on both data printing systems of JSM-T220 and JSM-T330 (JEOL SEM). It was found that the interfacing function worked properly and easily installed
[en] The status of our project on single-electron tunneling is, again, excellent. As outlined in our original proposal, a key goal for this project has been the development of a scanning tunneling instrument for the purpose of imaging individual particles and tunneling into these particles at high magnetic fields. Further progress is discussed in this report
[en] The evolution of a magnetic domain pattern with an applied field in two perpendicular directions was studied in a Ni-Mn-Ga magnetic shape memory alloy by means of optical and scanning electron microscopy (SEM). The optical contrast of magnetic domains arises from surface undulation. This surface relief is coherent at the (1 0 1) twin boundary. However, the surface relief causes the trace of the (0 1 1) twin boundary to follow a zigzag pattern. These optical observations were confirmed by SEM Type II magnetic contrast