摘要:

SummaryHigh‐resolution surface imaging by atomic force microscopy (AFM) of particulate materials is often problematic, principally as a result of the large height (z) variations in sample topography that either prevent the probe scanning over the particle or cause probe self‐imaging. This paper reports a novel method of embedding thermally sensitive particulate and fibrous materials which overcomes many of these problems and facilitates AFM imaging of these difficult materials. The process involves partial embedding of the sample in a cyanoacrylate film polymerized at room temperature. The sample heating required in currently used methods of particulate embedding is avoided and the method is therefore suitable for thermolabile materials. The cyanoacrylate film provides a flat hard surface which is ideal for AFM imaging, and the method has allowed successful imaging of relatively large particulate and fibrous samples such as starch granules and cellulose fibres. The cyanoacrylate has the added benefit that shrinkage holes in the film allow easy visual identification of areas where the film may have partially covered the sam

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1996.tb00001.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

SummaryThe processing of yeast cells for scanning electron microscopy by conventional sequential fixation with glutaralde‐hyde and osmium tetroxide and subsequent dehydration and critical point‐drying caused pronounced deformation and visible shrinkage in all basidiomycetous and ascomy‐cetous yeast strains studied. The mean cell diameter decreased to nearly 60 and 70%, respectively. After an additional sequential fixation with 1% tannic acid and 0–5% uranyl acetate the cell shrinkage was significantly reduced, but the most important result was a considerable reduction of wrinkling and deformation of the yeas

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1996.tb00002.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

SummaryWe found that the high‐voltage electron microscope (HVEM) operating at 1–5 MeV was able to transilluminate and form a focused transmission image of whole‐mounts of alveolar walls from human lung, a tissue sufficiently thin to require no embedment and sectioning. Resultant micrographs resembled a composite of scanning and transmission electron microscope images: surface and internal structure of the alveolar wall were visualized in a single micrograph.Although the scanning electron microscope extracts some subsurface information in the secondary electron mode, the HVEM produced better images of both surface and subsurface features.Lungs were fixed, dehydrated, critical point dried, and metal coated as for conventional scanning electron microscopy, then individual alveolar walls were excised by hand and mounted on transmission electron microscope grids. Regions of the alveolar wall up to 10 μm thick were delineated with the high‐voltage electron microscope.Cell surface characteristics were correlated with cell type as identified by underlying cell internal structure. Whole white blood cells within capillaries of the alveolar wall were identified by the configuration of their nuclei. Features of the nucleus and surface of alveolar type II cells were recorded simultaneously. Whole red blood cells were imaged within intact capillaries that branched and wove from one alveolar surface to the other.HVEM analysis of excised alveolar septa allows definitive correlation of surface and underlying structures in single micrographs of broad portions of the alveolar wall and is an alternative to embedment, microtomy and serial section reconstruction for this uniquely thi

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1996.tb00003.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

SummaryDirect‐view microscopes use multiple‐aperture arrays in the source and detector planes. We develop a theory for brightfleld and fluorescence direct‐view microscopy which allows us to determine the optical sectioning strength for finite‐sized, multiple‐pinhole arrays with an arbitrary distribution of apertures. We specialize to the cases of square, hexagonal and interleaving Archimedean spiral arrays and consider the implications of the array configuration on both the optical sectioning strength and the lig

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1996.tb00004.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

SummaryA novel method for the measurement of the section thickness of LM‐plastic embedded specimen has been developed. This method makes use of the fluorescence that comes from standard routine stainings such as haematoxylin and eosin and periodic acid‐Schiff. Anx‐zprofile of the specimen is first scanned using a confocal scanning laser microscope. The full‐width half‐maximum, FWHM, of the profile is computed and used as a measure of the specimen thickness. This method has proven to be simple and quick: a slide with five sections takes less than 1 min to measure. A theoretical treatment is presented which shows that the FWHM of the axial fluorescent profile is a good estimate of the actual thickness when the sample thickness is greater than 20 (when thickness is expressed in generalized longitudinal optical coordinates). This corresponds to a thickness of about 1μm when using an NA=1.3 oil‐immersion objective and 488‐nm excitation. The relative error in thickness is then less than 10%. Simulations and experiments have been carried out to examine how problems such as bleaching, sample tilt and curvature of field influence the FWHM. The results show that the method is robust and insensitive to

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1996.tb00005.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

SummaryAn unbiased estimator of the Euler‐Poincaré characteristic (Euler number) of an arbitrary object or a random structure, respectively, is given. The estimator is based on joint observations of pairs of parallel section profiles. Thus the present paper extends the use of Sterio's disector from counting particles to determining the Euler number for a wide class of probes. The correctness of the given formulae is proved with mathematical strictness. Furthermore, the feasibility of the method is illustrated by an example from materials scienc

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1996.tb00006.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

SummaryIn this paper, an iterative cell image segmentation algorithm using short‐time Fourier transform magnitude vectors as class features is presented. The cluster centroids of the magnitude vectors are obtained by the K‐means clustering method and used as representative class features. The initial image segmentation classifies only those image pixels whose surrounding closely matches a class centroid. The subsequent procedure iteratively classifies the remaining image pixels by combining their spatial distance from the regions already segmented and the similarities between their corresponding magnitude vectors and the cluster centroids. Experimental results of the proposed algorithm for segmenting real cell images are provi

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1996.tb00007.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

SummaryAn algorithm to produce a uniformly focused image in digital acquisition of high magnification light microscopy images is presented. In very high magnification microscopic imaging the specimen surface cannot be considered ideally flat so that capturing a single image frame is usually not sufficient to capture an image that is focused everywhere. An image formation model for light microscopic images is presented, and based on this model an algorithm to construct a uniformly focused image is presented. The algorithm requires that multiple frames of the image at different focal planes be processed to combine their information to obtain an estimated of the desired image which is more completely focused than any of the individual frames. Experimental results show that the proposed algorithm is very effective in approximating the desired image in high magnification microscopic imaging and highly robust comparing to the gradient method.

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1996.tb00008.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY