摘要:

SUMMARYA sequential and integrated metallographic procedure has been developed and successfully employed to differentiate between carbide, sigma, chi, Laves and ferrite phases which are commonly encountered in type 316 austenitic steel. The experimental techniques of optical and electron microscopy to identify these phases have been outlined and provide a rapid and convenient method of characterizing the microstructure of the steel. The techniques sequence involves selective metallographic etching, Nomarski interference microscopy, scanning electron microscopy, energy dispersive microanalysis, transmission electron microscopy and electron diffraction.

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1981.tb01251.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

SUMMARYThe usual stereological formulae yield mean values or one‐dimensional distributions. However, for the description of correlations in particle systems, second‐order characteristics are useful, for example the radial distribution function or the second‐order product density of the point process of particle centres. For the case of spherical particles some exact and approximate stereological formulae are given. These connect the spatial second‐order quantities with quantities available from planar or linear inters

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1981.tb01252.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

SUMMARYTwo related problems are explored. Firstly, a single opaque solid Ω1of arbitrary size and shape, containing an arbitrarily shaped phase Ω2, is considered. The problem is to estimate the minimum number of systematic sectionsm, necessary to estimate the volume ratiov=V(Ω2)/V(Ω1) with acoefficient of errorof at mostγ0with a probability 1 ‐ α. Secondly, we consider a population of such specimens. The second problem is to estimate the optimum numbernof specimens to be sampled and the numbermof systematic sections per specimen in order to estimate the mean volume ratioof the population with arelative errorof at most ∍0with a probability 1 ‐ α.General guidelines for solving the two problems are presented. Practical results applicable to two populations of mouse and guinea‐pig lymph nodes, exhibiting a wide variation in size and shape

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1981.tb01253.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

Freeze‐etch electron micrographs of haemolysing erythrocytes and isolated erythrocyte membranes frozen using a liquid propane jet‐freezer reveal fracture faces very different from those seen after conventional freezing by dipping the specimens into partly solidified Freon 22. Instead of the rather smooth extracellular fracture faces found after conventional specimen freezing, extracellular fracture faces exhibiting large amounts of fibre‐like structures are seen after liquid propane jet‐freezing of these specimens. No such structures were found in normal red blood cells. When isolated erythrocyte membranes are frozen under conditions favouring spectrin‐actin release, freeze‐etch micrographs reveal an apparent continuity between the fibrelike structures on the extracellular fracture face and the long fibre‐like structures which extend from the protoplasmic surface of the erythrocyte membrane. These results suggest that liquid propane jet‐freezing is capable of revealing a structural difference between the membrane of haemolysing and nonhaemolysed red blood cells, and that this difference is related to the fibrous, peripheral proteins

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1981.tb01254.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

SUMMARYWe outline the results of a computer program which calculates frequency distributions of functions of cross‐sectional regions of convex planar‐faced polyhedra, ‘sphero‐polyhedra’, and populations of perturbed polyhedra. This is done by ‘cutting’ a computer representation of the figure by a large number of random planes. The procedure is applied to cubes, dodecahedra, truncated octahedra, and approximate β‐tetrakaidecahedra. Certain aspects of the shape of the object, e.g. sharpness of corners, angularity, compactness, and degree of symmetry are related to aspects of the shape of the distribution curves, e.g. beginning and ending points of the curves, rate of rise of the peak, relative location of the peak, and height and w

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1981.tb01255.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

SUMMARYCell nucleus fractions were analysed in high voltage electron microscopes equipped with a hydration chamber and an energy filter, and the different filtering modes were tested. The best results were obtained when the energy filter was used as an analyser of atomic tracers specifically combined with RNA. Although the resolution thus obtained was relatively poor, the prospects of being able to observe hydrated organelles are encouraging.

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1981.tb01256.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

SUMMARYUniform P‐47 powder scintillators can be prepared with reproducible mass thicknesses by sedimenting the powder in an 0·01% solution of formvar in chloroform. A reflecting coating can be glued by floating a 60 nm aluminium film on the scintillation layer in an 0·1% solution of gelatine in water. The optimum thickness of P‐47 for 20–100 keV electrons increases slower than the electron range due to the absorption and scattering of light with increasing thickness. An aluminium coating increases the light output by a factor 1·85 for 20 keV and 1·4 for 100 keV electrons. The noise of the emitted light quanta and the photomultiplier detection system shows a minimum for the optimum thickness of largest light output and is only a factor 1·3–1·6 larger than the calculated shot noise of the incident

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1981.tb01257.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

SUMMARYThe distance from the observer's eye at which the image appears to be focused was measured with monocular, convergent and parallel eyepiece bodies, interchangeable on a Spencer microscope, with a camera lucida prism and a calibrated optometer. Five optometric tests for binocular vision and one for stereopsis made on thirty‐four observers revealed no significant correlation with the positions of the images. The apparent image position from the eye using the parallel binocular eyepieces averaged 671 mm, with the convergent eyepiece body at 587 mm, and 469 mm with monocular observation. The relations of these image positions with possible rest equilibrium positions of the accommodative mechanism of the eye and optical design of binocular instruments are discusse

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1981.tb01258.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

Biological structures not seen by conventional light microscopy, such as longitudinal striations in polytene chromosomes, and, at the limit of sensitivity, virions of adenovirus 2, have been detected via DNA‐associated fluorescence excited under the scanning electron microscope. The maximum sensitivity realized, about 1 detected photon per 700 base pairs, falls short by about an order of magnitude of that required to achieve, in unreplicated specimens, the 2 nm intrinsic resolution of the method. A combination of D2O‐H2O substitution with freeze‐drying provides the best unquenching procedure found forin situDNA.DNA‐associated fluorescence for light microscopy can be created by moderate exposure of the specimen in the electron mic

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1981.tb01259.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

SUMMARYA simple method is described, using polystyrene microcarrier beads, that allows cell monolayers to be prepared without distortion for transmission electron microscopy.Cells cultured on polystyrene beads (Biosilon R, Nunc, Kamstrup, Denmark) are held in an agar matrix. Before embedding, the beads are dissolved in 1, 2‐epoxypropane.The technique increases the number of observable cells, when compared to preparations of planar monolayers, and there is good preservation of morphological detai

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1981.tb01260.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY