摘要:

SUMMARYThis article gives a survey of the actual experience with the relatively new technique of photo‐emission electron microscopy. After describing the principal technique and the features of a modern high resolution instrument, the questions of image generation, contrast formation and resolution are considered. In particular the influence of the depth of information on resolution for flat polished sections is studied and some comparisons with the scanning electron microscope (SEM) are made.* The different fields of application of the photo‐EEM are shown by examp

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1972.tb03739.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

SUMMARYA general nonparametric approach to estimating the true distribution of particle sizes from either light or electron micrographs of particles of known shape is described. This method can deal with any arbitrary shape and fixed or random orientations, it assumes that the observed distribution is obtained by recording the maximum observed diameters of the particles under study. As examples, the method is applied to the distributions of both cubic particles observed in an optical metallographic specimen and spherical particles observed in a transmission electron microscope specimen.

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1972.tb03740.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

SUMMARYGranules in electron micrographs of normal rat peritoneal macrophages were analysed using a number of stereological procedures currently available for estimating the numbers of discrete particles from measurements made on random sections. The distinction between the various procedures was dependent upon the nature of the parameters derived from micrograph samples, and upon the degree to which particle shape and size distribution coefficients were incorporated within the mathematical derivations. Whilst all methods were found to produce similar estimates of granule number per unit volume of macrophage cytoplasm, two procedures demonstrated a greater degree of flexibility of application. It is concluded that these two methods may possess important advantages when quantitating experimental systems exhibiting alterations in particle morphology.

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1972.tb03741.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

SUMMARYIn 1968 Puszkin and co‐workers isolated from brain an actomyosin‐like protein which was not derived from the vascular system. Since corresponding myofibrils had not been described in histology, the tannic acid‐phosphomolybdic acid‐Levanol Fast Cyanine 5RN stain for myosin and related proteins was applied to methacarn‐fixed paraffin sections of human central nervous system (CNS) and peripheral nerve. Extensive meshworks of myoid fibres were found in the marginal layer and in white matter. Spider‐like cells containing myoid fibres were found in some areas of grey matter. Many axons of peripheral nerves were surrounded by myoid material, but myelin sheaths in CNS were apparently extracted by the fixative.Correlation of these observations with histochemical, electron microscopic and X‐ray diffraction data indicated similarity of the distribution of myoid fibres and fibrous astrocytes; the astrocyte fibres show the X‐ray diffraction pattern of a‐helical proteins. The myoid material in peripheral nerve is apparently associated with the myelin sheath. This pilot study suggests that the actomyosin‐like protein isolated from brain is probably derived from glia fibres which show the staining and X‐ray diffraction properties of proteins of th

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1972.tb03742.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

SUMMARYA quasi‐classical formulation of field‐ion imaging theory is defined and discussed. Concepts and terminology are defined, and a formula is established for the ion current generated above a single surface s

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1972.tb03743.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

SUMMARYExperimental evidence demonstrates the incompleteness of the usual rate constant explanation of field‐ion image appearance, and suggests that gas distribution effects may be the dominant influence on image contrast, certainly in some circumstances. Further evidence shows that gas concentration variations across the surface would not be given by any simple formal rule. However, significant features of image behaviour in the helium‐on‐tungsten system can be rationalized by closer examination of gas behaviour during and after accommodation. For the normal imaging range a provisional working rule is suggested, that regional contrast may be primarily determined by supply‐and‐capture effects, but local contrast by a tendency for local gas equilibria to be es

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1972.tb03744.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

SUMMARYThe technique of vibratory polishing has been successfully applied to the controlled removal of surfaces for examination of ion‐irradiation damage structure in nickel, a nickel‐based alloy, and stainless steel. The application of this technique to the study of voids formed in localized layers in nickel and stainless steel during high dose 20 MeV carbon ion irradiation is described. Transmission electron microscopy observations of the vibratory polished surfaces reveal mechanical damage in the form of linear tracks (∼ 100 nm wide) which are produced by the abrasive Al2O3particles used for polishing. These tracks do not prevent observation of irradiation damage structure. An example is shown of a thin (∼ 100 nm edge thickness) foil produced entirely by this mechanical polishing process. It is proposed that this technique will be equally applicable to the preparation of transmission electron microscope specimens from a wide range of metals, from alloys containing second‐phase particles and from ceramics, glasses and oxides which are not amenable to preparation by chemical or electro

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1972.tb03745.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

SUMMARYIn order to ensure reproducibility of magnification and to determine the accuracy of figures taken from the magnification meter on the side of a Siemens electron microscope, a sensitive voltmeter with a digital read‐out was put in the intermediate as well as the objective and projector lens circuits. The microscope was calibrated on different days and the results of the magnification measurements taken from the scale were compared with the results obtained using the read‐out system. The conclusions underline the necessity for exercising caution in interpreting magnification figures and suggest a relatively inexpensive method of improving reproducibil

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1972.tb03746.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

SUMMARYImage analysis, in the context of this paper, comprises the extraction of quantitative geometric and densitometric data from images produced by optical and electron microscopes or any other imaging system. Typical measurements include area percentages, intersect counts, feature counts, size distributions and integrated density determinations. Much of the stereological work is still performed by manual methods, but technological progress in recent years has considerably promoted the use of automatic image analysing devices. This paper describes recent developments in scanner performance and the correction of shading errors which allow reliable densitometric measurement. In addition, the previous geometric capabilities have been extended to include feature selection by pattern recognition criteria.

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1972.tb03747.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

SUMMARYAn apparatus for time‐lapse cinemicrography of living cells is described. It has an advantage over earlier apparatus in that it makes use of a microscope light source which can operate in both steady running and flash conditions. This enables setting up of the microscope and subsequent photography to be carried out with one light source, with consequent optimum illumination during photography. The light source is attached to a modified, inverted, phase‐contrast microscope, and the camera used is a modified 16 mm cine cam

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1972.tb03748.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY