摘要:

AbstractThe volume of thin foil specimens, which contain precipitate or other particles, viewed in the TEM is needed to determine particle density and spacing. It can be determined from the locations of the particles, measured using stereo pairs. A calculation that determines the volume between planes (not necessarily parallel or horizontal) that enclose the points is described. These planes will systematically underestimate the actual surface spacing and hence the volume, but a simple correction factor based on the number of points used in the fit can be used to estimate the actual volume. The method is tested, and its accuracy is evaluated using simulated data and applied to precipitate particles in creep‐tested silicon carbid

ISSN:0741-0581    

DOI:10.1002/jemt.1060100102

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

摘要:

AbstractHigh‐resolution electron microscopy has been used to characterize the platinum particles supported on TiO2or ZnO. After reduction at elevated temperatures, the metallic particles display a regular, faceted shape, and several superstructures, Pt3Ti(C), Pt3Ti(H), PtTi, and PtZn, have been found. These results, which may involve strong metal‐support interaction, have been confirmed by optical diffraction and image simulat

ISSN:0741-0581    

DOI:10.1002/jemt.1060100103

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

摘要:

AbstractWe have refined the technique of vascular corrosion casting with methacrylate to permit the reproduction of physiological states of vascular tone and to produce sturdy castings of ocular microvasculature. The method entails careful maintenance of homeostasis up to the moment of plastic perfusion, avoidance of vascular rinsing or fixation with the attendant anoxia, reduction of the viscosity of the casting resin without impairing the properties of the resultant polymer, addition of a cross‐linking agent to increase the strength of the plastic, and injection at physiological temperature and pressure. This casting regimen reproduces the normal anatomical conditions of blood vessels and can be used to demonstrate altered conditions of vascular tone. In all instances, the second, untouched eye serves as a control for unilateral manipulations. Special problems of replicating the ocular vasculature are related to the intraocular pressure, which opposes the vascular perfusion pressure and constitutes an impediment to perfusio

ISSN:0741-0581    

DOI:10.1002/jemt.1060100104

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

摘要:

AbstractThe geometric registration of two electron microscopic images generally is performed by maximizing the cross‐correlation coefficient between them. We show that a new similarity measure (the number of sign changes) is useful for performing simultaneously geometric and gray‐level registration. This method is robust, which means that it provides a good estimation of the parameters even in the presence of outliers that cannot be described by the registration mo

ISSN:0741-0581    

DOI:10.1002/jemt.1060100105

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

摘要:

AbstractReflection electron microscopy (REM), reflection high energy electron diffraction (RHEED), reflection electron energy‐loss spectroscopy (REELS), and energy dispersion x‐ray spectroscopy (EDX) have been comprehensively used as a technique, termed reflection high resolution analytical electron microscopy (RHRAEM), for studying the structures of the bulk crystal GaAs (110) surfaces by transmission electron microscopy (TEM). The simultaneous observations of surface topography imaging, the surface diffraction mechanism with RHEED, surface atomic inner‐shell excitations with REELS, and surface chemical compositions with EDX provide a systematic description of the atomic structure and chemical structure of the surface. The surface channelling effect has been observed in GaAs (110) with REELS, which may provide a basis for localizing surface foreign atoms with ALCHEMI. The theoretically predicted surface‐resonance wave has been observed directly in the RHEED pattern; the surface‐captured Bragg reflection wave have been identified. It is shown that surface chemical compositions can be determined by analyzing the EDX spectra obtained in the REM case. Finally, the surface monolayer resonance characteristic of the RHRAEM has been confirmed by calculations with dynamical RHE

ISSN:0741-0581    

DOI:10.1002/jemt.1060100106

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

摘要:

AbstractIn the Balzers rotary cold table, the recording thermocouple is located 45 mm below the specimen stage. As a result, there is inconsistency between the temperature indicated by the thermocouple gauge and the actual temperature of the specimen carrier. This inconsistency is most notable and can lead to problems when the cold table temperature is changed, such as during the procedure when fracturing at one temperature is followed by etching at a higher temperature.In this article, we describe modifications to the Balzers rotary cold table that permit the constant measurement of actual specimen temperature in the stationary, off, and rotating positions. The changes involve the use of a miniature temperature‐sensing diode (TFD‐Omega), mounted on the cradle that accepts standard counterflow, rapid‐loading specimen s

ISSN:0741-0581    

DOI:10.1002/jemt.1060100107

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

摘要:

AbstractConventionally, all specimen vial and block labels are handwritten or typed, a labor‐intensive process open to human error, particularly in a lab that processes large numbers of samples. The computer program described in this report was developed to reduce or elimiate this problem. The program is menu‐driven, asking specific information from the user, and runs on an IBM PC (or compatible). It is designed to accurately produce specimen collection vial labels, resin block labels, and data sheets for inclusion in a research notebook. A task that in the past may have required much time at the typewriter can now be accomplished without error in a few minutes. Although designed to fit the needs of a pathology laboratory, the program (written in BASIC) can be easily modified to fit other applicati

ISSN:0741-0581    

DOI:10.1002/jemt.1060100108

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

摘要:

AbstractThin sections of nervous tissue were viewed at different tilt angles using a transmission electron microscope equipped with a eucentric goniometer stage. In a comparison study of various degrees of tilt, one can observe additional morphological features within synaptic profiles, define subsynaptic structures such as Taxi‐bodies, and clearly see the crystalline formation of cytochemical tracers. This study demonstrates the value of tilting thin‐sections in the analysis of synapses and other biological material at the ultrastructural le

ISSN:0741-0581    

DOI:10.1002/jemt.1060100109

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

摘要:

AbstractCommon methods for the preparation of cultured cells for concurrent light microscopy (LM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) are not completely satisfactory. This article describes how we grow mammalian cells on plastic disks made from Aclar film. Aclar is a transparent fluorinated‐chlorinated thermoplastic that contains no volatile components and is, for all practical purposes, chemically inert. Cells adhere to it readily and remain attached after fixation, dehydration, and critical‐point drying or embedding. The film also accepts heavy metal coating by ionic bombardment and is extremely stable in the vacuum of the SEM. LM observations are unhindered by Aclar, since the film is as transparent as glass. Fluorescence microscopy is possible with this film, since it exhibits no detectable autofluorescence. During SEM observation, the film has great dimensional stability, and the cells and heavy metal coating remain attached to the Aclar even under high‐resolution operating conditions. TEM processing of specimens grown on Aclar is simplified by the fact that Aclar does not stick to the epoxy resins used in EM. Furthermore, Aclar is easily sectioned and does not damage knives used in ultramicrotomy. The use of Aclar film considerably simplifies the preparation of cultured cells for all types of microscopy. This method is particularly useful in correlating surface features between SEM and TEM observa

ISSN:0741-0581    

DOI:10.1002/jemt.1060100110

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

摘要:

AbstractThe controlled environment vitrification system (CEVS) permits cryofixation of hydrated biological and colloidal dispersions and aggregates from a temperature‐ and saturation‐controlled environment. Otherwise, specimens prepared in an uncontrolled laboratory atmosphere are subject to evaporation and heat transfer, which may introduce artifacts caused by concentration, pH, ionic strength, and temperature changes. Moreover, it is difficult to fix and examine the microstructure of systems at temperatures other than ambient (e.g., biological systems at in vivo conditions and colloidal systems above room temperature). A system has been developed that ensures that a liquid or partially liquid specimen is maintained in its original state while it is being prepared before vitrification and, once prepared, is vitrified with little alteration of its microstructure. A controlled environment is provided within a chamber where temperature and chemical activity of volatile components can be controlled while the specimen is being prepared. The specimen grid is mounted on a plunger, and a synchronous shutter is opened almost simultaneously with the release of the plunger, so that the specimen is propelled abruptly through the shutter opening into a cryogenic bath. We describe the system and its use and illustrate the value of the technique with TEM micrographs of surfactant microstructures in which specimen preparation artifacts were avoided. We also discuss applications to other instruments like SEM, to other techniques like freeze‐fracture, and to novel “on the grid” experiments that make it possible to freeze successive instants of dynamic processes such as membrane fusion, chemical reactions, and phase tr

ISSN:0741-0581    

DOI:10.1002/jemt.1060100111

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY