bluuebunny/crossref_metadata_2025 huggingface dataset:
Nature and origin of particles in condensation fume: a review*
Authors: Buckle E. R.
Published: August 2011

Precipitate from the fume generated in steelmaking contains chiefly iron in the form of metallic and oxide particles. Significant amounts of zinc and lead may also be present when, as in the U.K., there is substantial recycling of ferrous scrap. Conflicting explanations have been suggested for the sudden release of oxide (‘brown fume’) to form airborne aggregates of ultramicroscopic particles. The presence of free metal, usually as spheres of much larger size than those of the oxide, is attributed to the condensation of vapour to droplets which somehow escape oxidation.

Recently, several studies have been reported on the particles in smokes generated by heating metals in an inert gas. This work has been concerned more with the physical properties of the particles than with the mechanisms of condensation and growth. These mechanisms are main objectives in the work of this laboratory.

To obtain the fullest microscopical information about the structure of the particles, careful purification of the supporting gas is necessary and the precipitate must be guarded from the air by a protective coat of gold or gold‐palladium deposited by sputtering under argon or by vacuum evaporation. With the aid of morphological data on a number of volatile metals and thermally stable salts it has been possible to draw some conclusions about the relationship of the particle size and form to the conditions of aerosol generation. Close control of these conditions is especially difficult to achieve with involatile materials, including iron, although it seems likely that the use of lasers could greatly enlarge the scope of these studies in the future.
A programmed controlled temperature microscope stage
Authors: Reid D. S.
Published: August 2011

The construction, and testing, of a programmed controlled temperature stage for optical microscopy is described. The stage is shown to be capable of attaining temperatures between 160 K and 373 K, and of providing repeatable heating and cooling rates up to, and in excess of 100 K min−1. It is also capable of providing stable temperature holds.
The estimation of distances between parallel membranes on thick sections
Authors: Casley‐Smith J. R. , Davy Pamela
Published: August 2011

Since sections intersect membranes at random angles, the mean distances measured between two such membranes are greater than the perpendicular distances between them. Errors of 10–20% will be usual. Equations are derived relating the true lengths with the various observed ones, and the accuracy of the various methods are indicated. These differ for block‐stained and section‐stained material.

In the Appendix it is shown that in section‐stained material, while it is the stain near the surface which is of overwhelming importance for the production of contrast, much of this stain lies in the section itself, rather than actually on the surface. This stained depth is shown to be ∼4 nm deep, but this depth may include surface aggregates (∼ 1 nm) as well.
An economical, semi‐automatic system for measuring cellular tree structures in three dimensions, with special emphasis on Golgi‐impregnated neurons
Authors: Overdijk J. , Uylings H. B. M. , Kuypers K. , Kamstra A. W.
Published: August 2011

The hardware and software of a semi‐automatic system are described for the measurement of cellular tree structures in thick microscopical sections such as the processes of Golgi‐impregnated neurons. With this system, the morphologist— viewing the neuron directly through the microscope— measures the tree structures using three cartesian coordinates of characteristic points, e.g. centre of cell, origin of processes, bifurcation points, end points, deflection points, etc. The system requires an on‐line computer, but does not demand a dedicated computer since a joystick generator usually drives the microscopical stage during cell tracking. A digital computer is utilized for acquisition of data and, when needed, to return the stage to a required position. The microscope stage is coupled to three stepping motors with 0·5 (μm as the smallest step. The stepping motor for movement of the stage parallel to the optical axis (z‐direction) is coupled directly to a spindle mechanism, replacing the original cog wheel mechanism. This construction shows no measurable backlash. The practical advantages of this new measuring system in relation to the existing digital systems currently in use, its accuracy and its costs, are discussed.
Orientation of medial smooth muscle in the wall of systemic muscular arteries
Authors: Canham Peter B. , Mullin Kerry
Published: August 2011

The study was undertaken to determine the pattern of alignment of muscle cells in the tunica media of muscular arteries. Brachial and femoral arteries from two small Rhesus monkeys and renal arteries from two rabbits were fixed under pressure with formalin, or glutaraldehyde followed by formalin. Sections were cut at 7 μm thickness at specific angles varying from zero to 30°, and then stained with haematoxylin and eosin. The end coordinates of the medial muscle nuclei (appearing dark with the H & E stain) were recorded using a digitizer. Analysis was done as suggested by a previous modelling study by one of the authors; lengths of the individual nuclei as they appeared on the section were plotted as a function of the distance around the perimeter of the vessel. The distribution of lengths was consistent with a truly circumferential pattern of alignment for the muscle nuclei in the wall of muscular arteries. The standard deviation about the average circumferential pattern was ± 13° in the plane of the histological sections cut in cross section. The number density Nv of 4·4 × 105 mm−3 was higher than determined previously for human brain arteries and the nuclear length was 20% shorter (30 μm).
Sizing of phosphatidylcholine vesicles by transmission electron microscopy
Authors: Larrabee A. L. , Babiarz J. , Laughlin R. G. , Geddes A. D.
Published: August 2011

Coating of support films for transmission electron microscopy with silica by evaporation of ‘silicon monoxide’ provides a surface which is easily wetted by aqueous systems. Dispersed colloidal particles spread on this surface without the use of added soluble wetting agents. Such coated supports are found to be particularly useful for the quantitative characterization of the size distribution of vesicles prepared from saturated phosphatidylcholine. The weight average vesicle sizes determined for several samples from measurements of negatively stained electron micrographs are in good agreement with values measured by light scattering and ultracentrifugation.
An automatic counter for autoradiographed cells in Petri dishes
Authors: Schmialek Peter , Zapf Burger , Baisch Friedhelm , Geyer Astrid , Miosga Verena , Nündel Michael
Published: August 2011

A simple automatic counting device for cells on Petri dishes is described. The device is tested up to 1 × 104 cells (0·01 m)−2 and counts linearly without coincidence error. The counting time for each dish is c. 3– 4 min including the time required to place the dish in the apparatus.
A device for the rapid freezing of biological specimens under precisely controlled and reproducible conditions
Authors: Bald W. B. , Robards A. W.
Published: August 2011

The construction and preliminary testing of a device is described which can be used to freeze biological specimens in any cryogenic liquid at temperatures down to the nitrogen freezing point (63 K) and which can operate in the pressure range 1.3 kNm−2 to 1 MNm−2.

Ultra‐rapid freezing can be carried out in a subcooled cryogenic liquid either hyperbarically or at atmospheric pressure. Slow freezing rates can be achieved by cooling the specimens in a controlled manner in the vapour phase above the liquid bath.
Stabilizing ultrathin cryo‐sections by freeze‐drying
Authors: Geymayer W. , Grasenick F. , Hödl Y.
Published: August 2011

Cryo‐sectioning of specimens with high water content often proves to be especially difficult, as the sections of freeze‐shocked samples with their minimal thermal capacity warm up easily. The resultant recrystallization of the included water causes considerable damage in the structure of the frozen specimens. The method described in this paper enables cryo‐sections to be transferred from the microtome to a precooled high vacuum plant without contamination and at a temperature below the recrystallization point of ice. In this device the cold sections can be stabilized by freeze‐drying, sandwiching or electron‐bombardment for subsequent observation in the transmission electron microscope.
Instrumentation and specimen preparation for electron beam X‐ray microanalysis of frozen hydrated bulk specimens
Authors: Fuchs Wolfgang , Lindemann Bernd , Brombach Jobst D. , Trösch Walter
Published: August 2011

A cooling chain for the handling of frozen hydrated bulk specimens is described. Use of this method permits the specimen to be kept fully hydrated. After quench freezing, the specimen is transferred to a freeze etch apparatus, freeze fractured, carbon coated and transferred onto the precooled cold stage of the SEM by means of an airlock. The specimen is examined in the secondary electron mode and analysed using an energy dispersive X‐ray analyser. The midgut of Chironomus thummi larvae and frog skin epithelium were used to test the performance.
The use of low temperature X‐ray diffraction to evaluate freezing methods used in freeze‐fracture electron microscopy
Authors: Gulik‐Krzywicki T. , Costello M. J.
Published: August 2011

Two methods of freezing samples for freeze‐fracture electron microscopy have been compared using X‐ray diffraction and freeze‐fracture results from lipid‐water model systems. Perturbations of the molecular organization of hydrocarbon chains and the extent of ice crystal formation have been evaluated for lamellar phases of egg lecithin containing 16% water and egg lecithin‐phosphatidylinositol containing 55% water, both freeze‐quenched in liquid Freon‐22 near its melting temperature (113 K). Very thin samples sandwiched between copper sheets separated by an electron microscope grid show much less freezing induced structural rearrangement than small samples contained on conventional Balzers‐type gold planchettes. These results show that the rate of freezing in the very thin preparations is greater than in the conventional ones, which is probably due in part to the improved dissipation of heat from a poorly conductive sample through highly conductive copper sheets.
Cryofracture of paraffin‐embedded heart muscle cells
Authors: Dalen Helge , Myklebust Reidar , Saetersdal Thv. Selmer
Published: August 2011

A comparative study of internal cellular structures of the sheep ventricular myocardium has been conducted by scanning electron microscopy (SEM) and by transmission electron microscopy (TEM).

Access to the cell interior for three‐dimensional studies was obtained by cryo‐fracturing paraffin‐embedded tissue frozen in liquid nitrogen. For accurate localization of structures of special interest thick paraffin sections were examined in the light microscope (LM). Based on the information gained, it was possible to fracture the block in a desired plane. The fracturing was carried out by a light blow to a precooled scalpel held against the surface of the block, which was immersed in liquid nitrogen. After thawing and deparaffinizing at room temperature in several baths of xylene, the tissue pieces were critical point dried using CO2. As xylene was found to be miscible with CO2, it also served as an intermediate fluid. This method resulted in good preservation of the myofibrils, mitochondria, sarcoplasmic reticulum and transverse tubules (T‐tubules), which was confirmed by TEM studies of conventionally prepared tissue and of tissue originally prepared for SEM.
A chamber attached to the SEM for fracturing and coating frozen biological samples
Authors: Pawley James B. , Norton John T.
Published: August 2011

A chamber for introducing, fracturing and coating frozen biological samples has been developed as an attachment to the specimen chamber of a scanning electron microscope. Together with a eucentric‐tilt cold‐stage, this chamber constitutes a complete system for viewing fractured biological surfaces of the type normally only seen by replica techniques. An air‐lock on the chamber accepts a transfer module to allow insertion of the frozen sample without frost build‐up. Fracturing is carried out with a precisely adjustable cooled knife under a 10–100 × binocular microscope. The sample can tilt and rotate while being coated with carbon or metals evaporated from rechargeable sources introduced through the air‐lock. Cooling in the chamber is provided by a cylindrical copper tank filled with liquid nitrogen. The chamber has its own LN2 trapped high vacuum system. After preparation the sample can be placed directly into the SEM through an isolation valve. The cold‐stage utilizes a Joule‐Thomson refrigerator. The sample can be kept below 103 K at all times though there are provisions for heating it in the fracturing and cold‐stage positions. A system of controls, sensors and interlocks simplifies the operation of the system.
The dispersion of some optical properties of vitrinite
Authors: Jakeman B. L. , Cook A. C.
Published: August 2011

The dispersion characteristics of some optical properties of vitrinites from a number of coals of differing coal rank and type were investigated using a microscope photometer. The properties studied were air and oil reflectances, refractive index and absorption index.

The technique employed involved the measurement of air and oil reflectances at a number of wavelengths in the visible spectrum for selected points on the coal, as opposed to averaging the reflectances obtained in each immersion medium for each wavelength. The values of air and oil reflectances were then used to calculate the corresponding values of refractive index (n) and absorption index (κ) using a rearrangement of Beer's equation. Smooth dispersion curves were obtained for each selected field of vitrinite using this procedure. This method was preferred to the more widely used method of calculating n and κ from the average air and oil reflectances at each wavelength, because refractive and absorption indices are non‐linear functions of reflectance, which makes the arithmetic mean of the reflectances unsuitable for the calculation of n and κ.

The values of all parameters for the vitrinites were found to increase towards the blue region of the visible spectrum and to increase at all wavelengths with increasing coal rank. Some negative values of κ2 were obtained and the significance of these values is discussed.
Application of low temperature microscopy to food systems
Authors: Davis E. A. , Gordon J.
Published: August 2011

Low temperature scanning electron microscopy (SEM) and X‐ray fluorescent microanalysis were applied to bulk potato tissue samples. Morphological changes and relative distributions for K, P, S and CI were evaluated at various stages of starch gelatinization. Mineral movements into the starch granules were observed as gelatinization took place. Commercially extracted potato starch granules were observed and analysed at low temperatures. Also, these granules were cracked by raising the stage temperature to 153 K. Ice crystal growth appears to induce cracks in a radial and tangential manner along sites of weakness in a pattern that is supportive of the theory of complex starch granule formation.
Electron microscope fluoro‐autoradiography: improvement of efficiency
Authors: Buchel L. A. , Delain E. , Bouteille M.
Published: August 2011

The fluorographic process for enhancement of the autoradiographic detection of β‐ray emitted by tritium has been successfully adapted to electron microscope autoradiography. An original scintillator plastic film helped to increase the detection yield of electrons up to 80% without alteration of the morphological aspect of the autoradiograms, and without increasing background fog or causing apparent loss of resolution.
A scanning electron microscope modification for simultaneous numeration of exposures
Authors: Goss W. P. , Gillett R. , Hart J. S.
Published: August 2011

Neither the standard photographic facilities nor the Record Console of the Cambridge 600 Scanning Electron Microscope have provision for numbering films at the time of exposure. This omission is inconvenient and admits confusion at the later stages of printing. An earlier modification to the viewing screen of the basic instrument has later been transferred to the Record Console. Both are described, providing a convenient numbering facility using cheap proprietary electronic calculators, but leaving the calculating facility available. The system described gives a display of up to seven digits recorded by the camera at the time of exposure, without interfering with either image size or quality.
A simple and inexpensive culture device for cell growth, quantitative microscopy and autoradiography
Authors: Fox Cecil H. , Auer Gert , Zetterberg A. , Cottler‐Fox M.
Published: August 2011

An inexpensive culture chamber suitable for subsequent preparations for cyto‐chemical or radiographic work is demonstrated. The chamber consists of two glass microscope slides suitably prepared for cell growth and a gasket of silicone rubber. The slides and gasket are sealed and held together with two ordinary spring letter clips or clothes‐pins. Cells may be inoculated by piercing the gasket with a hypodermic needle, or by removing the top slide and adding cells directly. Long‐term cultivation with medium replacement is easy and efficient and addition of isotopes or other materials may be done aseptically.
A simple freeze‐drying technique for preparing biological tissue without chemical fixation for electron microscopy
Authors: Edelmann Ludwig
Published: August 2011

A simple technique for freeze‐drying and embedding of small pieces of biological tissue at low temperature is described, utilizing exclusively cryosorption pumping. Good preservation of chemically unfixed tissue is observed.
Two rapid and simple methods used for the removal of resins from 1.0 μm thick epoxy sections
Authors: Maxwell M. H.
Published: August 2011

Ultrathin epoxy sections are commonly used in electron microscopy. More useful information can often be obtained by examining thicker (0.5–3.0 μm) resin sections under the light microscope. However, there are some histological stains that are unable to penetrate these resins.

This short note describes the easy and rapid preparation of two resin‐removal solutions which allow subsequent staining of 1.0 μm thick sections without obvious tissue damage and with excellent results using standard histological dyes.
Identification of Gomori‐positive glia in autoradiographs
Authors: Goldgefter L.
Published: August 2011

Unstained Gomori or paraldehyde fuchsin or chrome‐haematoxylin‐alum positive granules in the perikaria of so‐called Gomori‐positive glia of the periventricular zone of the rat hypothalamus, fixed with Bouin's or Carnoy's fluids, have been found to produce a positive chemographic (blackening) effect on autoradiographic emulsion. Similar action was produced by some granules in ependymal cells localized in the ventral part of the third ventricle between optical chiasma and median eminence. It is suggested that this positive chemographic effect can be employed for the identification and characterization of Gomori‐positive glia in autoradiographic studies.
Sephadex globules placed as landmarks in combined stereo microscopy, scanning and transmission electron microscopy
Authors: Thorball Niels
Published: August 2011

Regions of specific interest in tissue blocks were localized in a stereo microscope and landmarked with Sephadex spheres (10–40 μm in diameter). This procedure made it possible to recognize these regions easily and quickly in the scanning electron microscope. When the tissue was later embedded in Epon the spheres facilitated orientation when sectioning. Thus it was possible with great certainty to determine the level at which ultrathin sections should be cut for transmission electron microscopy to attain an exact correspondence between scanning and transmission electron microscopic observations. The procedure is described and an example of its application is shown in a study of experimental hypertensive endothelial changes.
Scanning Electron Microscopy Of Uncoated Human Metaphase Chromosomes
Authors: Sweney L. R. , Lam L. F.‐H. , Shapiro B. L.
Published: August 2011

Human metaphase chromosomes were processed with a 3% glutaraldehyde‐tannic acid technique and examined in a scanning electron microscope at 20 kV either without added metal coating or with 2 nm of sputtered gold coating. Several substrates—aluminium foil, silver mirror deposit and sputtered gold—provided good conductive backgrounds for chromosomal spreads. Silver mirror deposit was the best conductive substrate tested. This method should prove to be a useful tool for monitoring the three‐dimensional morphology of mitotic chromosomes with the possibility of studying various banding techniques, chromosomal uncoiling and secondary constrictions currently being examined in chromosomal studies.
Differential Staining Of Cobalt‐ And Nickel‐Filled Neurones Using Rubeanic Acid
Authors: Quicke D. L. J. , Brace R. C.
Published: August 2011

A staining procedure is described which differentiates with distinct colours, cobalt and nickel ions introduced into neurones. Densely coloured precipitates are produced with these ions when rubeanic acid, a spot‐test reagent, is added. Formation of the coloured complexes takes place within a few minutes, and may be followed under the dissecting microscope. This technique permits observation of the relative positions, within ganglia, of somata related to two emergent nerves following multiple axonal‐backfilling. It also appears to be of value in tracing neurone branching after the intracellular injection of ions.
Electron Microscope Autoradiography Of A Diffusible Intracellular Constituent, Using Freeze‐Dried Frozen Sections Of Mammalian Intestinal Epithelium
Authors: Johnson I. T. , Bronk J. R.
Published: August 2011

Autoradiograms were prepared from freeze‐dried frozen sections of rat intestinal epithelium, previously incubated in vitro with 3H‐galactose. Although the sections snowed evidence of disruption by ice‐crystal growth during freezing, they retained sufficient recognizable ultrastructure to facilitate the identification of several subcellular compartments. Statistical analysis of the grain distribution indicated that a significant non‐uniform distribution of the labelled galactose occurs in the absorptive cells during transport, and is maintained in the sections throughout the various stages of autoradiography.
Topography And Thickness Of Air‐Dried Human Platelets Measured By Correlative Transmission And Scanning Electron Microscopy
Authors: Hui S. W. , Costa J. L.
Published: August 2011

Human platelets rapidly air‐dried on carbon‐coated grids were examined by transmission and scanning electron microscopy. Whole cell mounts were photographed in a transmission electron microscope (TEM), coated with gold, and then examined in a scanning electron microscope (SEM). The thickness of the cytoplasm towards the centre of the cells was estimated to be 20–40 nm, and the rim of dense material surrounding the cells was 40 nm thick. Some dense bodies stood out as much as 100 nm above the dried cytoplasm. These measurements are important for evaluating cytoplasmic volume during microprobe analyses of air‐dried platelet preparations.
A Technique For Illuminating Early Chick Embryos In Ovo With A Glass Rod As A Light Guide
Authors: Dryden R. J.
Published: August 2011

A glass rod mounted on a microscope condenser acts as a light guide through the yolk of a fertile hen's egg. Two apertures must first be made in the shell: the one below covered with plastic film which seals around the rod; the one above covered with a glass coverslip to allow microscopic observation of the embryo.
Resolution Of M23C6/Austenite Phase Boundary Defect Structures By Weak Beam Microscopy
Authors: Nilsson J.‐O. , Dunlop G. L.
Published: August 2011

The weak beam dark field imaging technique has been successfully applied to the problem of imaging misfit dislocations at the interface between M23C6 precipitates and an austenite matrix. The technique eliminates Moiré fringe contrast which otherwise obliterates the contrast from interfacial dislocations. Three sets of parallel dislocations were observed with spacings and line vectors consistent with them being edge dislocations with Burgers vectors of a/3<111>.
Progression Of Fusion During Rapid Freezing For Electron Microscopy
Authors: Van Harreveld A. , Trubatch Janett
Published: August 2011

The method used to determine the rate of fusion was based on the large difference in the dielectric constants of water and ice. A thin (50–60 μm) slice of a gelatin gel was used as the dielectric in a plate condenser. The slice was placed on a metal electrode built in a specimen carrier which was dropped on a silver freezing surface kept at below 70 K, forming the other plate of the condenser. Freezing of the gelatin causes a marked decrease in a 20,000 cycle current passing through the condenser. Since the thickness of the layer of frozen material was shown to be a function of the reciprocal of the current, it was possible to determine the course of fusion of the section. Freezing started at a high rate which declined during the first 5 ms but then increased again and usually became quite high at the end of fusion.
Intercellular Junctions In Fanft‐Induced Carcinomas Of Rat Urinary Bladder In Tissue Culture: In Situ Thin‐Section, Freeze‐Fracture, And Scanning Electron Microscopy Studies
Authors: Pauli Bendicht U. , Kuettner Klaus E. , Weinstein Ronald S.
Published: August 2011

This paper describes a set of simple methods for comparative light and electron microscopy studies on tissue cultured tumour cells derived from both noninvasive and invasive carcinogen‐induced rat urinary bladder carcinomas. Cells are grown on Thermanox plastic coverslips and fixed in situ. Each plastic coverslip is then divided with scissors into four parts: the first is processed for light microscopy, the second for thin‐section electron microscopy, the third for freeze‐fracture electron microscopy, and the fourth for scanning electron microscopy. In some experiments, portions of the culture which have first been examined by light microscopy are subsequently prepared for electron microscopy. In this way, the culture conditions are kept constant and a comparison of structural features (i.e. intercellular junctions) by several preparative techniques is possible.

Noninvasive and invasive rat bladder tumour cells, characterized by numerous pleomorphic microvilli, have normal zonulae occludentes at the apices of lateral surfaces of tumour cells in all cultures. In some areas of invasive tumour cells, occludens junctions are focally attenuated, consisting of only one or two strands, and occasionally the strands are discontinuous. Gap junctions, type PF‐1, as well as numerous desmosomes are present in all cell lines. Thus, intercellular junctions in noninvasive and invasive rate bladder epithelial cell lines bear a striking resemblance to those previously described in the comparable solid primary tumours. These culture systems may be useful for studying factors which influence the formation of intercellular junctions during malignant transformation.
Electron Microscopical Techniques For The Observation Of Cavities
Authors: Stobbs W. M.
Published: August 2011

The full range of methods by means of which cavities can be examined using a transmission electron microscope are reviewed. Different techniques are required in different circumstances and the extent to which a quantitative interpretation can be given is discussed for a number of examples. These range from the use of structure factor contrast for relatively large pores through the use of Fresnel contrast for intermediate sized pores with a dimension in the 0·4–20 nm range to elastic side band imaging and atomic resolution techniques for pores with sizes less than about 0·6 nm.
An Introduction To The Development And Effects Of Voids In Sintered Materials
Authors: Exner H. E.
Published: August 2011

Sintered materials usually show residual porosity which influences their properties. The present views on the development of the structure during processing (pressing, sintering) and some correlations between void structure and properties are reviewed. The important rôle of microscopy in the qualitative and quantitative evaluation of void structures is emphasized.
Microscopy Of Voiding During Creep Of Alpha‐Brass
Authors: Elliott I. C. , Wilshire B.
Published: August 2011

Metallographic and fractographic methods have been used to study void formation during high‐temperature creep of alpha‐brass. The appearances of the creep fracture surfaces were found to differ markedly at high and low stress levels. Cavity development was therefore monitored using samples tested to various fractions of their creep lives which were then fractured in an intergranular manner by stress‐corrosion at room temperature. The different modes of void formation observed can be rationalized in terms of a model for cavity growth based on the movement of lattice dislocations in the plane of the grain boundary.
Depth Distribution Of Swelling In Ion‐Bombarded Stainless Steels
Authors: Lauritzen T. , Konze G. M. , Bell W. L. , Appleby W. K.
Published: August 2011

Nickel ion bombardment has been extensively used to simulate and study swelling caused by neutron irradiation induced void formation in stainless steels. We have developed techniques to utilize the variations in displacement damage with depth from the ion‐bombarded surface to obtain swelling measurements for differing total displacement doses and dose rates from a single specimen. These techniques are not only cost effective, but have the advantage of conserving scarce material in those experiments involving specimens bombarded after prior reactor irradiation.

Nickel ions accelerated to 5 MeV have a range of about 1400 nm in stainless steel with the peak displacement damage occurring at a depth from the surface of approximately 900 nm. Thus, TEM examination of the microstructure at successive depths to 900 nm allows measurement of void swelling at various displacement doses. We accomplish this by stepped removal of the material in the plane normal to the incident ion beam. The ion entry surface is successively partially masked with lacquer and then ion milled to various depths. The foils are then perforated at the various depths by backthinning electrochemically. Results are presented which show the dose dependence of swelling obtained in this way for AISI 316 stainless steel bombarded to 115 dpa with up to 35% swelling. The results are compared and contrasted with dose dependencies of swelling obtained from examination of specimens separately bombarded to different peak doses up to 115 dpa.
An Atomistic Study Of The Structure Of Grain Boundary Dislocations
Authors: Sutton A. P. , Smith D. A. , Vitek V.
Published: August 2011

Computer atomistic calculations of the structure of edge grain boundary dislocations in coincidence boundaries have been carried out using a central force pairwise potential to describe the atomic interaction. The calculations show that close packed configurations of atoms exist in the cores of the dislocations. They also suggest that under certain specified conditions the structures of some grain boundary dislocations with Burgers vectors having the same magnitude but opposite signs on the same boundary facet can have different atomic structures. This is found to depend on the symmetry of the boundary plane, the driving force for dissociation into symmetry relating partials, the kinetics of the dissociation reaction, and the source of the dislocations.
The Structure Of Interphase Boundaries In Solids
Authors: Laird Campbell , Sankaran Ramanathan
Published: August 2011

Although, in principle, the structure of solid interphase interfaces should be no different from those of regular grain boundaries in homophase materials, it is shown that special boundaries characterized by a high degree of order occur much more frequently in interphase boundaries than in homophase boundaries. This is mainly caused by the fact that complex phases are usually produced at the end of the processing history of a material. Thus precipitates, eutectics, the products of spinodal decomposition, martensites, surface precipitates, epitaxially‐deposited heterojunctions and similar materials all tend to have special boundaries. On the other hand, multiphase materials subject to the same kinds of thermo‐mechanical processing as homophase materials, e.g. duplex steels, alloys with grain boundary precipitates, and superplastically deformed materials, possess interphase boundaries closely akin to those of homophase materials. The origins and structural details of the different kinds of boundaries are explored.
Electron Microscopy Of Interfaces Between Transforming Polytypes In Silicon Carbide
Authors: Jepps N. W. , Page T. F.
Published: August 2011

High resolution transmission electron microscopy, utilizing tilted illumination lattice imaging techniques, has been used to examine the structure of interfaces between transforming polytypes in cubic silicon carbide samples subsequent to annealing heat treatments. Though structure projection images have not been possible, detailed observation of the twinned cubic, 3C/6H and 3C/4H interfaces have been made including stacking sequence information observed with ∼ 0·25 nm lattice fringes. In contrast to the apparently strain‐free coherent conditions found at twinned cubic and 3C/6H interfaces, 3C/4H interfaces were observed to be coherent but with a short‐range strain field periodic over every twelve layers of the cubic structure. The 3C/6H transformation has been clearly observed to initiate at twin interfaces and to proceed by the propagation of steps of unit‐cell height along the coherent interface. The implications of these observations for phase transformations in silicon carbide, together with the necessary associated structural rearrangements, are discussed. Finally, some preliminary observations (utilizing impurity‐sensitive SEM contrast, together with the optical examination of thin foils in polarized light) concerning possible impurity redistributions and anomalous grain growth effects during polytypic phase transformations are presented.
Computer‐Controlled Double‐Beam Scanning Microspectrophotometry For Rapid Microscopic Image Reconstructions
Authors: Kuc̆era P. , de Ribaupierre Y. , de Ribaupierre F.
Published: August 2011

A method for automated collection of various specific data from an entire microscopical preparation and their quantitative evaluation is described. Its application to the study of neuronal connections is discussed in some detail.

Brain sections are scanned using a computer‐controlled microscope for reflectance, fluorescences or absorbance signals. Two illuminating beams are used, one of them being amplitude modulated. By means of a synchronous detection the two signals are recorded simultaneously: for example, in an autoradiograph, the reflectance (measuring the density of the silver grains in the emulsion) and the absorbance (allowing to localize the underlying counterstained cells). The data are stored in a computer.

Various off‐line processing schemes allow the reconstruction of the data with respect to the corresponding spatial coordinates. Thus pseudo‐three‐dimensional, analogue or digital, graphic displays may be obtained in which the patterns of neuronal connections can be recognized and interpreted. A method for the detection of weakly labelled nerve fibres based on digital filtering is presented.

The whole processing for a frontal section of the mouse brain (7 × 10 mm area) takes less than 1 h.

In addition to the evaluation of microscopically labelled material (grains of auto‐radiographs, horseradish peroxidase, nucleic acids) the technique described has been successfully used for the study of naturally fluorescent intracellular components in living tissue cultures.
The Use Of The Texture Analyser To Study Sinter Structure: Application To The Morphology Of Calcium Ferrites Encountered In Basic Sinters Of Rich Iron Ores
Authors: Greco A. , Jeulin D. , Serra J.
Published: August 2011

Quantitative image analysis applied to iron ore sinters gives complementary information to chemical analysis such as quantitative mineralogical analysis, and also quantitative geometric properties of crystals and of porous networks (size distribution, repartition). Spatial disposition of sinter components produced during crystallization builds different textures which are well known to mineralogists. The types of textures encountered can be related to initial composition, cooling conditions and to physical properties of the sinter (mechanical strength, reducibility). In order to estimate the relative importance of each texture in a sinter, measurements made using a pattern recognition procedure are required.

Algorithms for automatic pattern recognition were established for calcium ferrites texture encountered in rich iron ore basic sinters. They depend on a specific treatment of morphological parameters estimated inside fields of measurement of the texture analyser. Furthermore, mathematical models of multicomponent structures based on mathematical morphology, are used for different calcium ferrites textures. The parameters of these models are estimated from experimental measurements made with a texture analyser.

The present study is a part of a research programme made by IRSID (Institute of Research of French Steel Industry) on the structure of iron ore sinters in order to explain variations of their physical properties related to their behaviour in the blast furnace.
Guinea‐Pig Keratinocytes And Melanocytes In Tissue Culture: Scanning, Transmission And High Voltage Electron Microscope Observations
Authors: Merriman J. A. , Nieland M. L. , Wedmore R. J.
Published: August 2011

Keratinocytes and melanocytes cultured from guinea‐pig epidermis were studied with scanning, transmission and high voltage electron microscopy to characterize the surface and internal morphology. Keratinocytes exhibited contact‐inhibition and a range of surface structures consistent with cell‐cycle dependent changes. Stereoscopic analysis of high voltage electron micrographs indicated regular oval nuclei with nucleoli at different depths, while thin sections revealed local channels in the nuclei. Secondary cultures differed from primary cultures in the disorder of the microfilaments, in the failure to form desmosomes, and in the failure of melanocytes to persist in culture. The beaded surface of melanocytes was indicative of underlying melanosomes that were seen in high voltage micrographs. Melanocytes were rounded with moderate ruffles or were dendritic with ruffles on the termini. These findings are discussed in relation to the observational techniques and in relation to modes of locomotion of and pigment transfer to epidermal cells.
A Device For The Reproducible Spreading Of Cryoultramicrotome Sections
Authors: Williamson Francis A.
Published: August 2011

A device has been designed and constructed to electrically heat frozen sucrose solution droplets within the cryochamber of a cryomicrotome. This ensures that the solution liquefies to spread the sections before they melt and collapse, and allows many more sections to be cut continuously.
A Simple Vacuum Pipette For Processing Groups Of Specimens For Electron Microscopy
Authors: Ellis D. S. , Stamford Susan
Published: August 2011

A standard sink filter pump attached to a special glass adaptor, holding pipettes, enables groups of specimens to be fixed and dehydrated for electron microscopy with speed and safety.
The Evaluation Of Cell Nuclei Staining Parameters Regarding The Reproducibility Of Fluorescence Measurements
Authors: Matzke K. H. , Thiessen G. , Tiffe H. W.
Published: August 2011

The present methodological study is an attempt to optimize the staining parameters for a quantitative DNA determination of fluorescent cells. The application of pure dyes and a precise control of the staining procedure are preliminary conditions which have to be fulfilled, because the reproducibility of measurements is in this connection the most important criterion for a quantitative DNA related analysis of cell population.

Chicken erythrocytes and isolated nuclei were applied as biological test objects. The staining procedure with acridine derivatives (acriflavine, proflavine, rivanol) was performed in accordance with the fluorescence‐Feulgen reaction. The influence of staining parameters, such as (1) pH and (2) dye concentration of the staining solution, were evaluated regarding the spectral behaviour, the total fluorescence intensity, and the reproducibility of results.
Recent Advances Of High Voltage Electron Microscopy In Biology
Authors: Glauert Audrey M.
Published: August 2011

Recent advances in the understanding of the structure of biological material made possible by the high voltage electron microscope are reviewed by briefly summarizing some of the more important results obtained in the past few years. The examination of thick sections of selectively stained specimens has continued to be the most widely used approach and has yielded information on the three‐dimensional organization of a range of organelles, including the Golgi apparatus, neurofibrils and the transverse tubular system of striated muscle. The alternative method of studying intact cells prepared by critical‐point drying is becoming increasingly popular, and has already made a significant contribution in demonstrating the microtrabecular systems within the cytoplasm of cultured cells.
An Historical Account Of The Development And Applications Of The Negative Staining Technique To The Electron Microscopy Of Viruses
Authors: Horne R. W. , Wildy P.
Published: August 2011

A brief historical account of the development and applications of the negative staining techniques to the study of the structure of viruses and their components as observed in the electron microscope is presented.

Although the basic method of surrounding or embedding specimens in opaque dyes was used in light microscopy dating from about 1884, the equivalent preparative techniques applied to electron microscopy were comparatively recent. The combination of experiments on a sophisticated bacterial virus and the installation of a high resolution electron microscope in the Cavendish Laboratory, Cambridge, during 1954, subsequently led to the analysis of several important morphological features of animal, plant and bacterial viruses. The implications of the results from these early experiments on viruses and recent developments in negative staining methods for high resolution image analysis of electron micrographs are also discussed.
Total quantitative recording of elemental maps and spectra with a scanning microprobe
Authors: Legge G. J. F. , Hammond I.
Published: August 2011

A system of data recording and analysis has been developed by means of which simultaneously all data from a scanning instrument such as a microprobe can be quantitatively recorded and permanently stored, including spectral outputs from several detectors. Only one scanning operation is required on the specimen. Analysis is then performed on the stored data, which contain quantitative information on distributions of all elements and spectra of all regions.
Complementary freeze‐fracture, freeze‐etch specimens
Authors: Steere Russell L. , Erbe Eric F.
Published: August 2011

A procedure is described for the preparation and comparison of complementary freeze‐fracture‐freeze‐etch specimens. These complementary replicas reveal the value of etching some specimens even when the cryoprotectant concentration amounts to as much as 25% glycerol and 25% sucrose. As expected, the peplomers on the outer surface of the surrounding membrane of potato yellow dwarf virus are clearly revealed on the etched specimens but nearly invisible in the complementary freeze‐fracture specimen. Unexpected differences in the internal structure of vesicles within a freeze‐etched chloroplast have been revealed. The cross‐fractured surfaces of some other vesicles have a rough structure, whereas the complementary freeze‐etch surfaces, also shadowed at 123 K, are extremely smooth, suggesting that the contents must have been liquid at 175 K. Large ice crystals form within tobacco mosaic virus (TMV) crystals in infected cells frozen rapidly without cryoprotectant. Cryoprotectant consisting of 25% glycerol and 25% sucrose prevents formation of ice crystals when these specimens are frozen under the same conditions. When cryoprotectant concentrations are decreased from the above level, ice crystals within the TMV crystals are often clearly demonstrated in the freeze‐etch specimen but not in the complementary freeze‐fracture specimen. These results suggest that the complementary freeze‐fracture‐freeze‐etch procedure and the extremely fragile TMV crystalline inclusions are ideal for examining the value of various cryoprotectants and the effect of freezing rates, etching temperatures, and etching times on the final image.
Imaging modes in confocal scanning light microscopy (CSLM)
Authors: Brakenhoff G. J.
Published: August 2011

The optical arrangement for confocal scanning light microscopy can be incorporated in various imaging modes. Light microscopical specimens can be imaged with contrast enhanced, under γ‐control, inverted, etc. In interference, conditions can be set such that either pure phase or pure amplitude images result. Stereoscopic images at arbitrary aspect ratios can be realized in CSLM by electronic processing of the data obtained when the specimen is sampled with more than one confocal point concurrently. Also forms of differential imaging either amplitude or phase are possible. The coupling of these imaging modes with the improved resolving powers of CSLM results in some unique imaging opportunities, especially of value for high resolution light microscopy of living specimens.
Loss of silver grains from completed autoradiographs
Authors: Robertson G. B. , Rogers A. W.
Published: August 2011

The rapid loss of silver grains from processed autoradiographs has been traced to the use of unsatisfactory dehydrating reagents and mounting media.
Determination of defocus values using ‘Fourier images’ for high resolution electron microscopy
Authors: Iijima Sumio , O'Keefe M. A.
Published: August 2011

The phenomenon of Fourier images is used to calibrate defocus steps of a high resolution transmission electron microscope. Results compare well with measurements from an optical diffractogram.
Ultrastructure of red cells frozen with hydroxyethyl starch
Authors: Allen Edward D. , Weatherbee Lee
Published: August 2011

The freeze fracture appearance of red cells frozen in the presence of varying concentrations of hydroxyethyl starch (HES) is described. A technique is used which allows examination of a small portion of cells from a larger unit. The frozen cells appear distorted probably as a result of osmotic dehydration but indicate no evidence of intracellular ice. The frozen mixture with HES has three phases—a particulate phase consisting of the concentrated HES (and other salts), a sculptured ice phase and the red cells. When the concentration of HES is increased, the particulate phase becomes more prominent and at 14% HES appears to surround nearly all cells. In cells frozen in saline alone and 4% HES, the cytoplasm in a majority of cells has numerous cavities and depressions. Since such units haemolyse badly when thawed, it is possible that these regions indicate structural damage. In contrast, those units frozen with 14% HES (in which nearly 85% of the cells survive freeze‐thaw) possess cells which only infrequently have such regions in the cytoplasm.