摘要:

SUMMARYThe accuracy of the technique of using the fine‐structure observed in electron diffraction patterns to determine the periodicity and characteristic direction associated with a periodic strain field is assessed. This is done by applying the technique to dislocation multipoles which have a strain field with only a single periodic component and which can be well characterized by other means. It is shown that, for such a single‐component strain field, precision measurement of the diffraction patterns combined with numerical analysis of the data allows the determination of the direction and spacing characterizing the strain field with an accuracy of about 0.25° to 1.0° in direction (depending upon periodicity) and ± 2% in spacing. This is better than can usually be achieved from measurements of corresponding features in the electron micro

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1981.tb01264.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

SUMMARYThe purpose of this paper is to propose the necessary sampling techniques for estimating a global parameter defined in a solid opaque specimen (e.g. the total volume of mitochondria in a given liver, the total capillary surface area in a given lung, etc.). The geometry of the specimen often suggests amulti‐levelorcascadesampling design at different magnifications, whereby the object phase at one level becomes the reference phase in the next level. The final parameter is then estimated as the product of the intermediate ratios with the volume of the specimen, which is estimated independently. Each level can be regarded as an independent sampling design; a given stereological project may be planned in terms of one or more of these designs.Our development is a blend of practical experience and recent theoretical advances on sampling for stereology with well‐known sampling techniques previously developed with different purposes in m

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1981.tb01265.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

SUMMARYIn vitroandin vivostudies were carried out to assess the feasibility of adapting the cobaltinitrite method for the ultrastructural localization of K+in plant cells. The relatively low mobility of the cobaltinitrite ion and the solubility of the precipitation product resulted in the formation of only a few large deposits in each cell. The addition of Ag+at the time of precipitation was found to increase the number of small deposits retained in sections. However, cobaltinitrite reagents frequently caused plasmolysis and poor cytoplasmic preservation. Precipitation during freeze‐substitution was also attempted. It was concluded that precipitation of K+using cobaltinitrite has only limited use in low magnification electron microscopy in conjunction with light microscop

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1981.tb01266.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

SUMMARYA method is described for measuring the mass/length or mass of molecular assemblies by comparative electron scattering in the STEM. Standard particles whose mass is well established (e.g. TMV or fd bacteriophage) are deposited on the electron microscope grid together with the sample to be measured. Images containing at least one sample and standard and with a clean, contamination‐free background are chosen and stored on computer disc and then directly integrated. Use of a comparative technique does not require accurate determination of scattering parameters or instrumental geometry and requires only that the limits of linearity be established.The results of the mass/length measurements on phage pf 1, pili, muscle thick filaments and actin are in good agreement with existing molecular weight data and generally have a standard deviation of about 10%. The results for the total mass measurement of the multisubunit enzymes glutamate dehydrogenase and glutamine synthetase are also close to the literature values for their molecular weights. The results for the spherical, Semliki forest and tomato bushy stunt viruses are lower than expected, possibly reflecting some dissociation during preparatio

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1981.tb01267.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

SUMMARYTwo simple techniques are described and illustrated. The first is for the study of one specimen by both light microscopy (LM) and scanning electron microscopy (SEM). The second is for the study of one selected specimen by LM, SEM and in ultrathin section by transmission electron microscopy (TEM). Although these techniques were developed for the comparative study of Precambrian organic walled microfossils (OWMs), they could be used for a wide range of other specimens.

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1981.tb01268.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

SUMMARYA simple method of obtaining analogue images from traced models of biological specimens is presented. It consists of the photographic defocusing of traced models and it is illustrated with negatively stained cylindrical forms of the ASFV; the black lines of the trace in the model correspond to the negative stain surrounding the viral morphological subunits as seen in the electron micrograph. The photographic defocusing is the means by which the traced model is filtered and is used to introduce grey levels on an otherwise black and white image. The right amount of defocusing is attained when the width of the trace of the model equals the width of the rim of the negative stain appearing between the morphological subunits in the electron micrograph.

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1981.tb01269.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

SUMMARYPhotoelectron micrographs of gold‐palladium coated mouse 3T3 cells and chick embryo fibroblasts are presented. Since the gold‐palladium suppresses differences in work function, the cell morphology seen in these micrographs is due to relief contrast. The heights of comparable cells were measured from the parallax present in transmission electron micrograph stereo‐pairs of cell surface replicas. The origin of relief contrast and the effect of cell surface relief on the working depth of field in photoelectron images of cells are discussed. The micrographs demonstrate that photoelectron microscopy is very sensitive to fine details of cell surface topography, and that the working depth of field is not a limiting factor in the imaging of well‐spread tissue cultur

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1981.tb01270.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

SUMMARYAn electron energy filter of the Castaing‐Henry type in a high resolution transmission electron microscope was tested for sensitivity and spatial resolution at a specific electron energy loss in energy selected images of a murine leukaemia virus. Electron spectroscopic images of phosphorus within the virus membrane bilayer demonstrated a best spatial resolution between 0·3 and 0·5 nm and a sensitivity of 2 × 10

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1981.tb01271.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

SUMMARYPreviously invisible fossil remains of ancient iron‐bearing microbiota from the carbonate matrix have been detected by staining the petrographic thin sections by weakly acidic solutions of potassium ferricyanide. The chemical staining technique imparts a deep blue colour—Turnbull's blue—in the presence of ferrous iron to these fossil remains, which are considered to be an example of authigenic preservation process, whereby the microbiota are preserved as carbonate molds or casts.The technique was found to be suitable for Proterozoic rocks and has been further extended to Archaean rocks. Hence its univers

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1981.tb01272.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

SUMMARYA polychromatic staining procedure which uses the Giemsa stain and differentiates between several cell and tissue structures with distinct colours has been developed for semi‐thin sections of glutaraldehyde‐fixed, Epon‐embedded animal and plant tissues.The method does not require removal of the plastic and can be applied in a simple and rapid way for routine staining of semi‐thin sections with good

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1981.tb01273.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY