bluuebunny/crossref_metadata_2025 huggingface dataset:
Estimation of the average section thickness in ribbons of ultra‐thin sections
Authors: Gunning B. E. S. , Hardham A. R.
Published: August 2011

A simple procedure for estimating the depth to which a ribbon of ultra‐thin sections cuts into a block is described. The average section increment is obtained by dividing the depth by the number of sections in the ribbon. Comparison with measurements of individual sections made using interference microscopy suggests: (a) that loss of resin brought about by the cutting process is insignificant, i.e. that the average section increment equals the average section thickness, and (b) that there can be considerable variation in section thickness along a ribbon. Provided that such variation is taken into account, the method based on measurements of the block face is simple, avoids time‐consuming alternative procedures, and is appropriate when seeking to determine the depth dimension to be used in making three‐dimensional reconstructions from long sequences of sections.
Microanalysis of Grain Boundary Segregation in Embrittled Iron‐3wt% Nickel Alloys Using STEM
Authors: Doig P. , Flewitt P. E. J.
Published: August 2011

The segregation of minor embrittling additions of tin and phosphorus to the grain boundaries of an Fe‐3wt%Ni alloy after ageing at 823 K has been measured on thin foils using a Scanning Transmission Electron Microscope (STEM) interfaced with an energy dispersive X‐ray spectrometer. The microanalysis technique is discussed and shown to be useful for measuring grain boundary solute segregations.
Fixation of Senescing Plant Tissues: Sclerenchymatous Fibre Cells From the Flowering Stem of A Grass
Authors: Lawton June R. , Harris P. J.
Published: August 2011

The quality of fixation for transmission electron microscopy of young and older sclerenchymatous fibre cells from the flowering stem of a grass, Lolium temulentum L., was judged by their ultrastructure. In preliminary studies using glutaraldehyde buffered with sodium phosphate as the primary fixative the tonoplast was not complete even in many of the young fibre cells. This was thought to be an artefact of fixation and not due to natural senescence. Much improved fixation was obtained using NaOH‐PIPES to buffer the glutaraldehyde; the tonoplast was complete and there was a sharp demarcation between the cytoplasm and the central vacuole even in older cells with thick lignified cell walls. At all stages of development of fibre cells the tonoplast appears to be extremely fragile and sensitive to fixation conditions and can thus form a useful criterion for evaluating the quality of fixation.

The use of permanganate as a fixative led to improvement in the retention of the tonoplast and other membrane systems. Some improvement in fixation was obtained by the addition of formaldehyde to the sodium phosphate buffered glutaraldehyde and also when the glutaraldehyde was buffered with sodium cacodylate. More consistent results were obtained using glutaraldehyde purified by vacuum distillation.
Distribution of Membrane Thickness Determined By Lineal Analysis
Authors: Gundersen H. J. G. , Jensen T. B. , Østerby R.
Published: August 2011

The expected statistical distributions of intercept length are derived in terms of geometrical probability density functions pertaining to plates with known thickness penetrated by lines with random orientation. These expressions provide arithmetic and graphical solutions for obtaining distributions of membrane thickness and reciprocal membrane thickness from empirical distributions of intercept lengths. Furthermore, general relationships between probability density functions of distributions of intercept length and membrane thickness are derived as well as those between their moments.

Examples of the application of the method to biological samples are given, and estimated distributions of glomerular basement membrane thickness are compared to those obtained by an independent, direct method.

Various sources of bias, which in practice may occur due to departures from the sample model, are discussed and the influence of some of them is estimated. The knowledge of the probability density function of reciprocal intercepts makes it possible to perform a correction of the distributions of measured intercept length, which to some extent eliminates bias.
High Resolution Scanning Electron Microscopy in Biology: Artefacts Caused By the Nature and Mode of Application of the Coating Material
Authors: Bråten Trond
Published: August 2011

Results of high resolution secondary electron observations of the haemocyanin molecule from the marine whelk Buccinum undatum are given.

The choice of metal used for surface coating of the sample (gold, gold‐palladium or carbon/gold‐palladium) and the mode of application of this metal (thermal vacuum evaporation or diode sputtering) were both found to be of utmost importance when working at high magnifications in the scanning electron microscope.

Sputter coating with gold gives poor results because of a granular and cracked appearance of the surface film. The haemocyanin molecules were difficult to recognize in these preparations. Best results were obtained by a thermal vacuum evaporation of gold‐palladium.

It is suggested that the inferior results seen after sputter coating may be due to the high temperatures which the specimen experiences during the sputtering, even when cooling of the specimen stage is carried out.

Other specimens (diatom valves and latex spheres) were also studied at high magnification giving the same results as the haemocyanin molecules.
Critical point drying for scanning electron microscopy: a semi‐automatic method of preparing biological specimens
Authors: Hall D. J. , Skerrett E. J. , Thomas W. D. E.
Published: August 2011

Slow, controlled, rates of critical point bomb heating and of gas venting have been shown to improve the preservation of biological specimens in critical point drying. A procedure that represents a balance between avoidance of specimen damage and speed of operation has been developed for use with CO2 as the transitional fluid. Bomb heating is automated and controlled electronically, and manual venting of the gaseous CO2 is monitored using a gas flow meter.
A simple technique for the direct SEM observation of the interior of a small capsular organ
Authors: Cross R. H. M.
Published: August 2011

The direct SEM observation of the interior of closed or semi‐closed capsular organs has presented difficulties in cases where the organ is small and not suitable for accurate dissection. Descriptions of such organs have usually been based upon reconstruction from serial sections cut for optical microscopy or TEM. A method is described whereby the established techniques of epoxy removal from embedded material are used to permit direct SEM observation of the interior of a small capsular organ.
Observations of silicon carbide by high resolution transmission electron microscopy
Authors: Smith David J. , Jepps N. W. , Page T. F.
Published: August 2011

High resolution transmission electron microscopy techniques, principally involving direct lattice imaging, have been used as part of a study of the crystallography and phase transformation mechanics of silicon carbide polytypes. In particular, the 3C (cubic) and 6H (hexagonal) polytypes have been examined together with partially transformed structural mixtures. Although direct observation of two‐dimensional atomic structures was not possible at an operating voltage of 100 kV, considerable microstructural information has been obtained by careful choice of the experimental conditions. In particular, tilted beam observations of the 0·25 nm lattice fringes have been made in the 3C polytype for two different {111} plane arrays in order to study the dimensions and coherency of finely‐twinned regions together with {0006} and lattice images in the 6H polytype which allow the detailed stacking operations to be resolved. Lower resolution lattice images formed with axial illumination have also been used to study the nature of the 3C → 6H transformation and results are presented showing that the transformation interface may originate with fine twinning of the 3C structure followed by growth of the resultant 6H regions. Observations have been made of the detailed stepped structure of this interface together with the stacking fault distribution in the resultant 6H material. The images obtained suggest that tilted beam techniques will be useful for studying the one‐dimensional disorder in other SiC polytypes and related ceramic materials. Some of the possible advantages of future observations with high voltage, high resolution instruments are considered.
Monitoring of the course of fixation of plant cells
Authors: Mersey Brent , Mccully M. E.
Published: August 2011

The fixation of cells of petiolar hairs of tomato was monitored by phase contrast and Nomarski interference contrast microscopy. Because the cuticle covering these hairs is relatively impermeable some fixatives enter only the base of the hair so that a ‘fixation front’ can be followed through a single cell. The basal end of such a cell may be immobilized by the fixative while the apical end is still streaming. A variety of fixatives were tested at room temperature and at 273–278 K. All procedures tested failed to stabilize a pleomorphic canalicular system that is a dominant feature of these cells so that no clue to the presence of this system can be seen in sectioned material. It is therefore very desirable that images of fixed cells be compared to the structure of similar cells which are still alive.
Extraction of glycoproteins during tissue preparation for electron microscopy
Authors: Sturgess J. M. , Mitranic M. M. , Moscarello M. A.
Published: August 2011

The extraction of glycoproteins labelled with 3H or 14C precursors: fucose and glucosamine, has been compared during processing of rat liver for transmission electron microscopy.

Using 14C labelled fucose, approximately 6% of labelled macromolecules were extracted during processing including 3% during glutaraldehyde fixation, 1% during post‐fixation and 2% during dehydration. Greater extraction (8%) occurs with glucosamine as a precursor, which may be attributed to hydrolysis of the more labile sialic acid residues of the glycoprotein molecules.

Tritium labelled glycoproteins were more susceptible to extraction than 14C‐labelled glycoproteins. The extraction of 3H‐labelled glycoproteins as measured by liquid scintillation counting may prove difficult to interpret owing to the quenching from processing solutions.
A photoelastic substrate technique for dynamic measurements of forces exerted by moving organisms
Authors: Harris Jack K.
Published: August 2011

The forces produced by small moving organisms have been quantitatively measured by having the organisms move on a polymeric substrate which transduces the applied stress into an optical birefringence signal (photoelastic effect). The optical signal can be rigorously interpreted to give static force measurements, and by calibrating the substrate empirically, dynamic measurements are obtained. The technique measures stresses, forces applied to an area, so it is not possible to determine ultimate sensitivity of the technique for measurements of forces without regard to area. The technique is especially useful when small forces are exerted over very small areas as, for example, may be the situation with moving tissue cells. The technique is noninvasive, requires minimal equipment, and is easily performed on microscopes adapted for polarized light measurements. Gelatin has the highest sensitivity and adaptability as a photoelastic substrate.
The rôle of optical microscopy in refractories development within the iron and steel industry*
Authors: Warman M. O.
Published: August 2011

Until comparatively recently the optical microscope was used infrequently in many refractories laboratories. It was regarded by many as a device which provided interesting information but had little application in solving real refractories problems. A number of distinguished people in the industry realized that this attitude was wrong and actively promoted the use of the microscope as a tool of practical importance. Since then the microscope has become indispensable in refractories research and plant investigations. The paper describes a number of the many investigations carried out by one laboratory over the last 10 years. They illustrate the importance of the microscope in problem solving and in understanding the wear mechanisms of refractories, so that furnace and vessel lining configurations can be modified to give optimum performance.
Radiation damage relative to transmission electron microscopy of biological specimens at low temperature: a review
Authors: Glaeser Robert M. , Taylor Kenneth A.
Published: August 2011

When biological specimens are irradiated by the electron beam in the electron microscope, the specimen structure is damaged as a result of molecular excitation, ionization, and subsequent chemical reactions. The radiation damage that occurs in the normal process of electron microscopy is known to present severe limitations for imaging high resolution detail in biological specimens. The question of radiation damage at low temperatures has therefore been investigated with the view in mind of reducing somewhat the rate at which damage occurs. The radiation damage protection found for small molecule (anhydrous) organic compounds is generally rather limited or even non‐existent. However, large molecule, hydrated materials show as much as a 10‐fold reduction at low temperature in the rate at which radiation damage occurs, relative to the damage rate at room temperature. In the case of hydrated specimens, therefore, low temperature electron microscopy offers an important advantage as part of the overall effort required in obtaining high resolution images of complex biological structures.
Radiation damage in the high resolution electron microscopy of biological materials: A review*
Authors: Cosslett V. E.
Published: August 2011

Radiation damage to a biological specimen arises from a variety of interactions between the illuminating electrons and the atoms in it. The relative probabilities of these events, and the amount of energy transferred, can be calculated from basic physical theory. The microscopic damage caused in a particular specimen in given operating conditions is more difficult to predict, but it can be measured by a number of macroscopic indicators, the chief of which are loss of mass and changes in the energy loss spectrum (or electron diffraction pattern, if any). For most biological material the observed rate of damage is such as to set a limit to the intensity of illumination, the maximum magnification and the minimum size of detail that can be made visible. Several techniques have been devised and tested for reducing the radiation sensitivity of a specimen, of which cooling to a very low temperature and encasing it in an inert medium are the most effective. If the various protective measures act cooperatively, they could increase the effective resolution of sensitive material by an order of magnitude, making possible electron microscopy of the atomic structure of, for instance, the nucleic acid bases and other macromolecules. The prospects for observing living cells at a resolution better than that of the best optical microscopes would remain very small.
An image reversal process for electron microscope film
Authors: Brandt Curtis R. , Davis Ronald
Published: August 2011

An improved technique has been developed to produce a positive image directly on some standard electron microscope films (Kodak 4489, SO 163, and Ilford Electron Microscope Film). This technique has been useful for processing micrographs of freeze‐etched and shadowed specimens, and eliminates the need for producing positive image transparencies before printing.
Calibration of a commercial electron microscope with a grating replica to an accuracy of better than 1%
Authors: Brown Lucy M.
Published: August 2011

The 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

This 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

Several 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

A 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

Previous 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

A 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 method for marking and relocating identified cells in whole tissue for electron microscopy
Authors: Hopkins W. G.
Published: August 2011

Deposits of silver chloride made on the surface of animal tissue are visible by reflected light after osmication. When the tissue is flat embedded, the deposits permit precise relocation and thin sectioning of specific identified cells.
A new inexpensive specimen carrier for freeze‐fracturing
Authors: Müller Werner , Pscheid Peter
Published: August 2011

This 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

The 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

The 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

In 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

A 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

Kidney 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

A 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

Preliminary 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

A 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.
Image Analysis In Electron Microscopy
Authors: Frank Joachim
Published: August 2011

The review covers methods for electron‐image analysis, with an emphasis on averaging techniques designed to minimize the electron dose. The problem of resolution assessment of single particle averages is discussed as a special topic.
Prospects For Extending The Resolution Limit Of The Electron Microscope
Authors: Glaeser Robert M.
Published: August 2011

The 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

By 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

A 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

The 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

The 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

The 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

Modifications 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

A 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

The 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.
Improved tables for the evaluation of sphere size distributions including the effect of section thickness
Authors: Rose P. E.
Published: August 2011

The problem of determining the size distribution and population density of a population of spherical particles randomly distributed throughout a transparent matrix from data obtained by transmission microscopy on parallel plane‐faced sections of known field area and thickness may be readily solved by the use of matrix algebra. The solution presented in this paper may be used to construct conversion matrices whereby the particle size distribution and the numerical density can be calculated directly from the frequency distribution of the observed diameters; the only mathematical processes necessary being multiplication and addition.

Specimen conversion matrices valid for a wide range of conditions are presented in the appended tables.
Effects of glutaraldehyde and glycerol on freeze‐fractured Escherichia coli
Authors: Arancia G. , Valente F. Rosati , Crateri P. Trovalusci
Published: August 2011

Glutaraldehyde and glycerol are widely used in the freeze‐fracture technique as sample pretreatments before rapid freezing. However, they can both introduce relevant structural changes and influence the visualization of the fracture faces and surfaces of membranes. A comparison of the results obtained on E. coli cells differently pretreated with glutaraldehyde and glycerol is presented. In particular the effect on the distribution and density of the intramembranous particles (IMP) is pointed out. Glycerol treatment at 310 K introduces an IMP redistribution, outlined by the appearance of several smooth areas on the fracture faces of the cytoplasmic membrane, which is prevented by glutaraldehyde prefixation at the same temperature. On the other hand, glutaraldehyde treatment at 310 K following glycerol incubation results in the disappearance of the smooth areas, suggesting a substantial change in the IMP distribution caused by the fixative. Cells shifted down to 277 K and treated with glycerol at this temperature before quick‐freezing, present on the convex fracture face of the cytoplasmic membrane large smooth areas resulting from a lipid transition while the smaller areas observed at 310 K are not detectable. Glutaraldehyde treatment at 277 K seems also to be responsible for a redistribution of IMP since poorly delimited large smooth areas, containing several IMP, can be observed. In this paper the results of a statistical analysis are also reported, showing that the IMP density can be strongly influenced by pretreatments.
Stereometry as an aid to stereological analysis
Authors: Howell P. G. T.
Published: August 2011

Accurate measurements for the stereological analysis of rough or curved surfaces are not always possible with single images from the light microscope or the scanning electron microscope (SEM). A second image recorded to form a stereo pair provides the information about the topographic nature of the surface. This paper presents two methods by which stereo pair scanning electron micrographs can be measured to give area fractions or other geometric parameters of rough surfaces.
A quantitative study of the preparation of rabbit aortic endothelial cells for scanning electron microscopy
Authors: Mcgarvey Kathleen A. , Reidy Michael A. , Roach Margot R.
Published: August 2011

Quantitative studies were done with the scanning electron microscope (SEM) on aortic endothelial cells from ten rabbits. Of these, five were plastic casts and five were dehydrated with three different, but standard, techniques. The results indicated that all forms of dehydration caused significant shrinkage artefacts and that these were different in different directions in both the thoracic and abdominal aorta. The greatest shrinkage was found with the critical point drying technique, 45% in the abdominal aorta and 31% in the thoracic aorta. In the abdominal aorta this shrinkage was mainly due to a shrinkage in length (36%) rather than a shrinkage in width (15%). In comparison, in the thoracic aorta critical point drying resulted in a 15% shrinkage in length and a 19% shrinkage in width. Air drying and alcohol dehydration caused considerable shrinkage (29% and 18% respectively in the thoracic aorta, 29% and 36% respectively in the abdominal aorta). Directional differences were also found with these techniques, for instance alcohol dehydration in the thoracic aorta resulted in 0% shrinkage in length and 18% shrinkage in width.
Time resolved cathodoluminescence in the scanning electron microscope by use of the streak technique
Authors: Hastenrath M. , Balk L. J. , Löhnert K. , Kubalek E.
Published: August 2011

Minority carrier lifetime is one of the basic material properties in optoelectronic devices and material. Both the micrometer range dimensions of the devices and lifetime variations around defects in materials require a lifetime measurement technique with both high spatial and high temporal resolution. In order to meet these requirements a highly efficient cathodoluminescence (CL) measurement system has been developed consisting of a commercial scanning electron microscope extended for integral and spectral CL‐measurements and a streak camera with subnanosecond time resolution as time resolving detector. The lifetime is determined by evaluation of CL‐decay time after excitation of the specimen by an electron beam pulse, which is blanked in less than 50 ps by an adjustable plate capacitor. The CL‐light is collected by an adjustable, ellipsoidal mirror and can be dispersed in a vacuum monochromator. The monochromator exit slit is imaged on to the photocathode of the streak camera, which transforms the temporal distribution of the photon intensity into a lateral distribution on the camera phosphor screen after amplification by an integrated microchannel plate. By this technique it is possible to record the complete CL‐decay simultaneously, thus avoiding all measurement falsifications by system instabilities. The resulting intensity distribution is read out by a SIT vidicon camera with subsequent multichannel analyser, providing an intensity plot versus streak time in less then 1 min for each beam spot location. The technique is therefore well suited for lifetime mapping experiments. The best time resolution of the complete system achieved today is about 100 ps. Its performance is here demonstrated by measurements of the temperature dependence of the CL‐decay in a highly Se‐doped GaAs specimen in the temperature range from 90 K to 300 K.
SEM—EBIC studies of boron implanted silicon
Authors: Ioannou D. E. , Davidson S. M.
Published: August 2011

Known SEM‐EBIC techniques based on Schottky diode and p‐n junction charge collectors are modified or further developed in order to study the radiation damage and the minority carrier diffusion length and lifetime in boron implanted silicon, and their annealing behaviour.
The characterization of distortions in heteroepitaxial structures by X‐ray multiple diffraction
Authors: Brown B. R. , Halliwell M. A. G. , Isherwood B. J.
Published: August 2011

X‐ray multiple diffraction can be used to characterize distortion in heteroepitaxial layers non‐destructively. The basic technique and its application to gallium aluminium arsenide layers on gallium arsenide is described. The lattice parameters of the layers can be found and hence their composition. The diffraction patterns obtained confirm that layers grown on off‐axis substrates grow tilted with respect to the substrate.
Size determination of sonicated vesicles by freeze‐fracture electron microscopy, using the spray‐freezing method
Authors: Van Venetië R. , Leunissen‐Bijvelt J. , Verkleij A. J. , Ververgaert P. H. J. Th.
Published: August 2011

The usefulness of spray‐freezing for determining the sizes of sonicated vesicles of egg lecithin with various cholesterol concentrations has been demonstrated. It is found that vesicles of egg lecithin increase in average size with increasing cholesterol concentrations, in agreement with measurements obtained with other techniques.
Phosphorus standards for the electron probe X‐ray microanalysis of ultrathin tissue sections
Authors: Weakley Brenda S. , Weakley Timothy J. R. , James John L.
Published: August 2011

Phosphorus‐containing standards for use during quantitative electron probe X‐ray microanalysis of ultrathin tissue sections can be quickly and simply prepared using organo‐phosphorus compounds which are soluble in Spurr's epoxy resin mixture. Trials of five such compounds (one solid, the rest liquid) are described.