Transmission electron microscope components

Because of the possible effects of active and carrier-mediated processes and metabolic biotransformation, the issue of tissue viability is important for in vitro buccal mucosal experiments. The barrier nature of the buccal mucosa resides in the upper layers of the epithelium, where unlike in the stratum corneum, the cells contain a variety of functional organelles [119, 122, 125, 150], and so tissue viability may be an important component of the barrier function of the tissue. Various methods have been employed to assess the viability of excised buccal mucosa, including measurement of biochemical markers, microscopic methods, and linearity of transport data [42], While biochemical methods, including measurement of adenosine 5 -triphosphate (ATP) levels and utilization of glucose, provide information on the metabolic activity of the tissue, this does not necessarily relate to the barrier function of the tissue. In excised rabbit buccal mucosa, levels of ATP were measured and found to decline by 40% in 6 h, and this correlated well with transmission electron microscopic evaluation of the tissue (intact superficial cells) [32], In addition, the permeability of a model peptide was unaltered up to 6 h postmortem, but at 8 h, a significant change in permeability was observed [32], These investigators therefore claimed that excised rabbit buccal mucosa could be used for diffusion studies for 6 h. 

It was reported that the K/Cu-Zn-Fe oxides catalyst efficiently converted a mixture of COj and H2 into ethanol by Mitsubishi Gas Chemical and National Institute of Material and Chemical Research [1]. However, the catalyst was deactivated quickly during the reaction. To improve the catalytic life, an addition of various kinds of components was tried. It was found that the addition of Cr component to the catalyst prevented the deactivation of catalyst [2]. In this paper, we describe the effect of the addition of Cr component to the catalyst from the results of XRD analysis, transmission electron microscope observation (TEM), and energy-dispersive X-ray microanalysis (EDS) of the catalysts before and after the reaction. 

The exhaust gas of diesel engines has a complex composition as gaseous components are present together with liquid and even with solid components (Table 23). The solid exhaust gas components are denoted particulate matter, and defined as any matter that can be collected on a teflon-coated filter paper from diluted exhaust gas at a temperature below 325 K. Scanning and transmission electron microscopic pictures of such particulates are shown in Fig. 95. 

High resolution transmission electron microscopy (TEM) (Jeol lOOCX) was employed to determine the size of the metal particles on the surface of the catalyst support, and the composition of individual metal particles was ascertained (for thin sections cut with an ultramicrotome) using a field-emission scaiming transmission electron microscope (STEM) (VG HB 501) (at 1.5 mm resolution) and an energy dispersive X-ray (EDX) analyser. The metal loading of catalysts was determined by ICP-AES (Spectro D), following dissolution in concentrated hydrochloric and sulphuric acids. Direct analysis of aqueous samples taken from the reaction medium, using the same analytical technique, allowed the corrosion of metallic components from the catalyst surface to be studied. 

Figure 45. Scanning transmission electron microscopy Top Schematic representation of the essential components of a scanning transmission electron microscope (ADF annular dark field BF bright field FEG field image gun)...

In recent years, electron diffraction has been used to characterize fuel cell catalysts, as information about the crystal symmetry of active components can be obtained from electron diffraction. Most of the electron diffraction for fuel cell catalysts is performed in a Transmission Electron Microscope (TEM), where the electrons pass through a thin film of the samples being studied. The resulting diffraction pattern is then observed on a fluorescent screen and recorded on photographic film or with a CCD camera. 

Phase contrast also appears in electron microscopy. The passage of the wavefront through a specimen causes a phase shift which can be converted into image intensity by interference between the retarded wave with another wave. Components which cause phase contrast have been tried in the transmission electron microscope and do work, but they are impractical. 

Hobbs et al. [18] studied the morphology of different polymer blends using a transmission electronic microscope (TEM), and showed that the morphology, or the distribution pattern, of a polymer blend of three polymeric components depended on the thermodynamic properties of the polymer components under processing conditions. A thermodynamic parameter called the spreading coefficient of the polymer in the lowest amount was suggested to characterize the thermodynamic behavior of such a system, which can be calculated using the values of surface tension of the components. 

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