bluuebunny/crossref_metadata_2025_split huggingface dataset:
Calibration of a commercial electron microscope with a grating replica to an accuracy of better than 1%
Authors: Brown Lucy M. 
Published: August 2011

SUMMARYThe method of calibration described in this paper depends on (1) bringing every specimen to the ‘eucentric point’ of a side‐entry goniometer stage to achieve a constant objective magnification, and (2) monitoring changes in the magnification of the projector lenses with a selected area (SA) aperture in the objective image plane. Under a wide range of operating conditions the aperture gives a sharp image whose diameter is proportional to magnification, so that the calibration is independent of changes in HT, lens currents and remanent magnetism. The method has been validated using Jeol 100C and 100S electron microscopes.The spacing of the standard cross‐hatched grating replica was determined by comparing a low magnification electron micrograph, in which it could be measured, with a calibrated phase contrast optical micrograph of the same area. Elliptical distortion (which ultimately limits the accuracy of calibration) was assessed by rotating the specimen through 90°.
Calculation of surface area and volume of human erythrocytes from scanning electron micrographs
Authors: Leblond P. F. , Shoucri R. 
Published: August 2011

SUMMARYThis article demonstrates that surface and volume measurements of individual human erythrocytes with varying shapes can be obtained from scanning electron micrographic stereopairs using an approach based on established principles of photogrammetry.Instead of calculating the coordinates of several hundred points plotted for each cell, a procedure that proves tedious and time‐consuming, we show that a reasonable approximation of cell surface and volume can be achieved from simple geometrical models constructed with a small number of carefully measured points and angles, using a stereocomparator.The values obtained for two normal erythrocytes and for two distorted red cells from a patient with congenital pyruvate kinase deficiency haemolytic anaemia are consistent with available information on the geometry of these cells.Because scanning electron microscopy requires extensive manipulation of the cells, the values obtained cannot be applied to fresh living material, but appear fairly accurate for the purpose of comparison between cells prepared in the same manner.
Morphology and cytochemistry of acinar secretory granules in normal and isoproterenol‐treated rat submandibular glands
Authors: Simson J. A. V. , Dom R. M. , Sannes P. L. , Spicer S. S. 
Published: August 2011

SUMMARYSeveral fixation procedures have been utilized in a fine‐structural study of rat submandibular glands with the aim of correlating the morphology of granule substructure with its composition. Procedures included fixation with aldehyde in a variety of buffers, with or without fixation additives such as tannic acid or calcium chloride. Both immersion and perfusion fixation studies were performed. Osmium tetroxide postfixed tissue was compared with non‐postfixed tissue. Thin sections were stained for carbohydrate‐containing constituents by either periodic acid‐thiocarbohydrazide‐silver proteinate or tannic acid‐ferric chloride sequences. The morphology and cytochemistry of acinar secretory granules were highly dependent upon the fixation procedure utilized. In postfixed tissue, fine filaments and vesicles were the major granule constituents. Filaments often aggregated into fibrils in fixatives containing phosphate buffer or calcium, whereas vesicles were prominent with fixatives containing collidine buffer. Tannic acid, as a fixation additive, imparted enhanced density to the peripheral rim of aggregated filaments. If post fixation was eliminated, an amorphous meshlike material was the major granule component. This stained readily with methods for carbohydrate whereas the granules of post‐osmicated tissue did not.Following chronic isoproterenol treatment the degree of filament aggregation in postfixed tissue was augmented, and this corresponded to an increase in amount of material stainable for carbohydrate in non‐post‐osmicated tissue.
Application of cluster analysis for characterization of spatial distribution of particles by stereological methods
Authors: Baudhuin Pierre , Leroy‐Houyet Marie‐Anne , Quintart Joël , Berthet Paul 
Published: August 2011

SUMMARYA method for the detection and characterization of clusters of particles observed in section with the electron microscope is presented. Cluster analysis is performed by the division method described by Berthet et al. (1976). Starting from a single cluster, profiles from each electron micrograph are successively classified in sets containing an increasing number of clusters. The decrease in the mean free distance, Λ, between profiles in the clusters, is used for terminating the subdivision procedure. The function relating the mean free distance with the number of clusters is evaluated in each subdivision set. The actual number of clusters is selected on the basis of the slope of that function, at a point where Λ has a value close to the average profile diameter. The method assumes a convex shape for the clusters; the salient feature is that it provides a physical delineation of clusters in the section. Hence, an evaluation of some characteristics of clusters in the three‐dimensional sample may be obtained by using standard stereological procedures. Characterization of the volume to which the individual particles of a population are eventually restricted can as a result be performed.Practical problems in the acquisition of the data needed for cluster analysis are discussed and a system using for that purpose a Quantimet 720 image analyser in a basic configuration, connected on line with a PDP 11/10 minicomputer, is presented. Application of the method is illustrated by the analysis of lysosomes in cultured hepatoma (HTC) cells, at the end of mitosis and during the S phase. Cluster analysis shows that in mitotic cells, lysosomes are confined within 3·7% of the total cellular volume, while in cells actively synthesizing DNA they are grouped in clusters representing 5·7% of the cellular volume. Moreover, the average number of particles per cluster falls from a minimum of thirteen at mitosis to only six at the S phase.
Direct evidence of radial and tangential morphology of high‐modulus aromatic polyamide fibres
Authors: Hagege R. , Jarrin M. , Sotton M. 
Published: August 2011

SUMMARYPrevious work, at foreign laboratories, essentially based on electron microscopy of longitudinal sections, has suggested a radial morphology for the aromatic poly‐amide high modulus fibres; the present paper gives direct evidence of such a morphology, thanks to a special preparation technique which allows a great improvement in the quality of the cross‐sections of these fibres.This is demonstrated for both a commercial ‘Du Pont de Nemours’ yarn sample ‘Kevlar 29’, and an experimental high modulus aramid RPT (Rhǒne Poulenc Textile) yarn. In the first case, Ag2S insertion technique was used and permitted one to see, on the cross‐sections, an alternation of dark and clear radial bands, again with a tendency towards tangential splitting. In the second case the fibres were included into an amorphous polymer, a sample preparation technique which greatly enhances the quality of the cross‐sections; optical microscopy showed the radial morphology fairly well; dark‐field transmission electron microscopy—using the equatorial doublet of the electron diffraction pattern—allowed satisfactory resolution: both the radial, and occasionally the tangential, splitting, and the size of the cross‐sectioned crystallites were easily revealed: these crystallites appear as isodiametric bright particles c. 15 nm in lateral size.
Multiple marking of cell surface receptors by gold granules: simultaneous localization of three lectin receptors on human erythrocytes
Authors: Horisberger Marc , Vonlanthen Monique 
Published: August 2011

SUMMARYA method is described for transmission electron microscopy which allows high resolution mapping of three lectin receptors on the same cell. As a model, receptors for Concanavalin A, soya bean and wheat germ agglutinins have been simultaneously localized on human erythrocytes using lectin‐labelled gold markers of different sizes (5, 17 and 26 nm, respectively). Quantitative binding data and examination of stereoscopic micrographs of thin sections of marked erythrocytes indicated that the greatest part of these lectin markers was bound by receptors spatially separated. As gold granules are electron dense and uniform in size, they are well suited for multiple marking of cell surface components. The method is simple and leads to a better understanding of the topography of cell membranes.
A new inexpensive specimen carrier for freeze‐fracturing
Authors: Müller Werner , Pscheid Peter 
Published: August 2011

SUMMARYThis paper describes the production and use of a new specimen carrier for the Balzers freeze‐fracturing unit. The carriers are inexpensive, easily produced and have excellent mechanical and thermal properties. The rectangular form of the carriers provides easy handling and unequivocal orientation of anisotropic specimens.
Three‐Dimensional Reconstructions Of A Cavity Using Plastic Sheet And Modelling Clay
Authors: Stephens P. R. 
Published: August 2011

SUMMARYThe squid statocyst had proved difficult to interpret from histological sections and whole mounts. It consists of an enclosed cavity with inward projections. In order to understand the internal structure of this cavity three‐dimensional models were made. Histological sections were specially prepared and the cavity outline and reference marks drawn on to clear plastic sheets. These were cut out and the inner and outer pieces assembled in series to make two sets of shapes. One could be viewed directly, while from the other set plaster casts were made to demonstrate the cavity.
Three‐Dimensional View Of The Chromatin In Freeze‐Fractured Chicken Erythrocyte Nuclei
Authors: Haggis G. H. , Bond E. F. 
Published: August 2011

SUMMARYThe freeze‐fracture thaw‐fix (FfTF) technique described in earlier papers is applied in the present work to more detailed study of the chicken erythrocyte, by transmission replicas and high resolution scanning electron microscopy (3 nm scan beam size). The three‐dimensional structure of the chromatin, and possibly the non‐histone protein matrix, of fractured nuclei is to a large extent retained in this method of preparation and seen in stereomicrographs. In these micrographs the helical sub‐structure of the 25 nm chromatin strands can be seen at about the same resolution as that of previously published micrographs in which extracted chromatin is viewed by negative contrast or after metal shadowing. The useful resolution of the secondary electron micrographs, for a suitably mounted specimen, is shown to be as good as that of transmission micrographs of platinum‐carbon replicas of the same material.
Contrast In Transmission Electron Micrographs Of Void Arrays In Crystals
Authors: Johnson E. , Kynde E. , Chadderton L. T. 
Published: August 2011

SUMMARYIn order to understand the detailed features in electron micrographs from radiation induced void lattices in crystals, an attempt has been made to determine the contrast from columns of regularly spaced strain‐free spherical voids using calculations based on the two‐beam approximation. Analytical expressions have been obtained for the wave amplitudes at the exit surface of a model crystal using matrix algebra. Line profiles for the contrast across a void column have been computed and two‐dimensional images simulated on a line printer. The contrast behaviour has been analysed in terms of deviation from the Bragg condition for varying void column parameter: void distance/void radius. For dynamical, as well as for kinematical diffraction conditions the influence on the image of defocusing phase contrast has been investigated by addition of extra phase contributions to the diffracted beam amplitudes. Defocusing in most cases induces an enhanced contrast from the void column.
Microspectrofluorometric Studies On The Formaldehyde‐Induced Reaction Product Of 5‐Hydroxytryptamine
Authors: Schofield G. C. , Wreford N. G. M. 
Published: August 2011

SUMMARYA new model incorporating Sephadex G‐25 as an inert carrier has been developed for studying the reaction between biogenic amines and formaldehyde vapour. Both the fluorescence yield and the spectral characteristics of the 5‐HT formaldehyde reaction product are influenced appreciably by the relative humidity at which paraformaldehyde is equilibrated, the duration of the reaction, the glycine concentration and pH of the suspending solution and the duration of exposure to ultraviolet light. It is concluded that care should be exercised in attempting to identify or quantify 5‐HT on the basis of microspectrofluorometric analysis.
Ultrastructure Of Cell Organelles By Scanning Electron Microscopy Of Thick Sections Surface‐Etched By An Oxygen Plasma
Authors: Humphreys Walter J. , Henk William G. 
Published: August 2011

SUMMARYKidney tissue double fixed in glutaraldehyde and osmium tetroxide and embedded in epoxy resin by standard techniques used for transmission electron microscopy was cut into sections 1 μm or more thick and surface‐etched by an oxygen plasma. Etching caused ash residues (possibly composed partly or organo‐metallic complexes) of membranes and other etch resistant cell components to emerge as recognizable structures projecting upward from the surrounding embedment which was combusted and removed as volatile products. Using the secondary electron mode for image formation, structural features of cells which could be imaged with clarity with the scanning electron microscope included: profiles of peripheral and infolded plasma membranes, the nuclear envelope and profiles of cut mitochondrial matrix granules, cristae and the outer limiting membranes. Resolution was better than that obtainable from most other methods of specimen preparation currently being used in scanning electron microscopy for viewing the internal structures of cells and organelles in bulk samples of tissue.
A Method For Preparing And Handling Cross‐Sections From Early Chick Embryos For Scanning Electron Microscopy
Authors: Nagele R. G. , Goldstein M. M. , Lee H. 
Published: August 2011

SUMMARYA method is described for processing multiple cross‐sections from early chick embryos for scanning electron microscopy. Embryos are cut through the desired regions. Sections are affixed to a coverslip with Duco cement and critical point dried by Freon 13 or liquid CO2. This method provides a reliable means for preparing multiple cross‐sections from single embryos and eliminates the need for direct handling of brittle tissues after drying.
Petrographic Characterization Of Coal Using Automatic Image Analysis
Authors: England B. M. , Mikka R. A. , Bagnall E. J. 
Published: August 2011

SUMMARYPreliminary evaluation of a new method for quantitative characterization of the petrographic constituents of coal is described. Although the technique is still in the development stage it does demonstrate the potential use of image analysers in coal petrography. The method involves the use of an image analysing computer to produce a‘fingerprint’ representing both the maceral composition and rank of the coal.This technique enables the quantitative measurement of coal structural parameters, previously unobtainable by normal routine analysis procedures. These parameters include intersected size distribution and shape factor of inert components. Maceral and reflectance distributions equivalent to those produced by presently available analysis procedures can also be determined.The development of this technique should eliminate the subjective nature of maceral and reflectance analyses and it also has the advantages normally associated with automation, such as increased speed of analysis and reproducibility of results.
Image Contrast And Localized Signal Selection Techniques
Authors: Howie A. 
Published: August 2011

SUMMARYA survey is made of a number of the localized signal selection methods and related techniques which may be used to improve the electron microscope image contrast from small regions of material and thereby bring the specimen resolution actually achieved somewhat closer to the electron‐optical resolution of present‐day instruments. Geometrical and stereo methods are discussed, as well as weak‐beam and other coherent elastic scattering methods. Localization effects in inelastic scattering and the image contrast in energy loss electrons are examined in greater detail.
Prospects For Extending The Resolution Limit Of The Electron Microscope
Authors: Glaeser Robert M. 
Published: August 2011

SUMMARYThe factors that limit the performance of present‐day high‐resolution electron microscopes include the source brightness, the temporal coherence of the illumination, and phase contrast ‘artefacts’ due to spherical aberration and defocus. Further advancement of the instrumental performance might be accomplished in different ways, including the use of high coherence conditions combined with image restoration; the use of higher accelerating voltages; the use of aberration correctors; or the use of conditions for incoherent image formation. Current efforts in each of these directions are reviewed, from which it is evident that the combined use of higher voltages and improved coherence is the direction that is presently leading to the greatest degree of progress.
Biological X‐Ray Microanalysis
Authors: Hall T. A. 
Published: August 2011

SUMMARYBy means of X‐ray microanalysis it is now practical to detect approximately 10−19 g of an element in a static‐probe analysis within an ultrathin section, with analytical spatial resolution in the range 20–30 nm. The main difficulties for biological microanalysis are connected not with sensitivity but with specimen preparation and beam damage.Careful cryopreparation, beginning with the quench‐freezing of a small block of tissue, is essential even for determining the storage sites, or sites of binding in vivo, of physiologically active elements.In frozen‐dried or frozen‐hydrated sections of quench‐frozen tissue, it is now possible to measure local mass fractions of diffusible as well as of bound elements.
Local Characterization Of Solids By Electron Energy Loss Spectrometry
Authors: Wittry David B. 
Published: August 2011

SUMMARYA survey of instrumentation for electron energy loss spectrometry and applications of this technique to the local characterization of solids is presented. The use of plasmon losses and core excitation losses are compared. The statistics that determine elemental detection limits for core losses are discussed and areas for future developments in the use of electron energy loss spectrometry are emphasized.
Confocal scanning light microscopy with high aperture immersion lenses
Authors: Brakenhoff G. J. , Blom P. , Barends P. 
Published: August 2011

SUMMARYThe imaging characteristics of a confocal scanning light microscope (CSLM) with high aperture, immersion type, lenses (N.A. = 1·3) are investigated. In the confocal arrangement the images of the illumination and detector pinholes are made to coincide in a common point, through which the object is scanned mechanically. Results show that for point objects the theoretically expected improved response by a factor of 1·4 in comparison with standard microscopy can indeed be realized. Low side lobe intensity and absence of glare permits the imaging at high resolution of weak details close to strong features. A further improvement by a factor of 1·25 in point resolution in CSLM is found after apodization with an annular aperture. Due to the scanning approach all possibilities of electronic image processing become available in light microscopy.
Mass loss and etching of frozen hydrated specimens
Authors: Talmon Yeshayahu , Davis H. Ted , Scriven L. E. , Thomas Edwin L. 
Published: August 2011

SUMMARYThe effects of high dose electron irradiation on frozen hydrated specimens have been studied. Samples which when dry are very stable to the electron beam are found to be severely etched in the presence of ice. Mass loss of ice greatly exceeds the rate expected from sublimation, and is caused by radiolysis. The active molecular species that are formed in this process attack material in contact with ice.
Estimation of tubule or cylinder LV, SV and VV on thick sections
Authors: Jørgen Hans , Gundersen G. 
Published: August 2011

SUMMARYThe estimators of tubule or cylinder LV=2NA, SV=2IL, and VV=PP are considered in terms of bias due to section thickness, diameter, overlap, and grazing or fuzzy profiles. The superiority in a number of cases of the indirect estimation of SV and VV as functions of LV and profile diameter is discussed. Statistical aspects are dealt with in a practical example.
Modification of the Reichert FC‐2 cryoattachment to improve ultrathin sectioning reproducibility
Authors: Leunissen J. L. M. , Pluygers H. W. , Elbers P. F. 
Published: August 2011

SUMMARYModifications of the Reichert FC‐2 cryomicrotome attachment which facilitate sectioning of frozen material are described. Most valuable was the construction of a specimen holder chuck made of brass and connected to the specimen arm with a glass rod. Other changes include improved shielding from heat influx, a constant nitrogen pressure cooling system and a stable cryochamber mount. These modifications considerably improve reproducibility.
An objective method for measuring fluorescence of individual sperm cells labelled with 1‐anilino‐naphthalene‐8‐sulphonate (ANS) by means of photomicrography and densitometry
Authors: Watson P. F. 
Published: August 2011

SUMMARYA method is presented for measuring the degree of fluorescence of sperm cells labelled with 1‐anilinonaphthalene‐8‐sulphonate (ANS). Labelled spermatozoa were subjected to incident‐light u.v. illumination and the fluorescent image was photographed. Densitometry of the photographic film yielded values for individual sperm heads, and the mean value for ten cells formed the unit of data for parametric statistical analysis. The method is both objective and precise, and was used to distinguish between treatments applied to the spermatozoa. It is believed that the method has a wide application as an inexpensive means of fluorimetry.
Tem Study Of Silicon Laser Annealed After The Implantation Of Low Solubility Dopants
Authors: Cullis A. G. , Webber H. C. , Poate J. M. , Chew N. G. 
Published: August 2011

SUMMARYThe transmission electron microscope (TEM) has been used to study the structure of Si implanted with low solubility dopants and annealed using pulsed radiation from a Q‐switched ruby laser. Annealing took place by transient surface melting and, for Fe+ ion and Cu+ ion implants, most of the impurity was zone refined out to the sample surface where silicide phases were formed. The occurrence of constitutional supercooling in the resolidifying melt led to a non‐uniform distribution of these silicides. Nevertheless, the Si matrix recrystallized in a highly perfect manner, as was also the case for annealed Ar+ ion implants. However, the latter also gave rise to the formation of bubbles which yielded information about the final buried Ar distribution. Silicon layers implanted with very high doses of nitrogen also apparently retained some of the impurity after annealing, although studies of the physical state of this nitrogen are still in progress.