bluuebunny/crossref_metadata_2025 huggingface dataset:
The transmission electron microscopy of oxide scale formation on Fe‐Ni‐Cr alloys
Authors: Newcomb S. B. , Stobbs W. M.
Published: August 2011

The oxidation behaviour of 10Cr and 20Cr iron alloys, with nickel contents from 0 to 34 wt% both in air and in CO/CO2, is summarized with particular emphasis on the form and chemistry of the different scales as they were observed using transmission electron microscopy. The various modes of inward oxidation are for example characterized with ‘internal’ and ‘inner’ oxidation taking place under different circumstances. The role of carbon during oxidation in a CO/CO2 atmosphere is also discussed as is the way in which a given alloy can show either chemical or mechanical passivation failure in different environments.
Cryoultramicrotomy versus plastic embedding: comparative immunocytochemistry of rat anterior pituitary cells
Authors: Hemming F. J. , Mesguich P. , Morel G. , Dubois P. M.
Published: August 2011

The anterior pituitary of the rat is used as a model for the study of the effects of freezing or plastic embedding on the maintenance of antigenicity. Rat anterior pituitaries are fixed in 2.5% glutaraldehyde in 0.1 m phosphate buffer pH 7.4. Some of the blocks are post‐fixed before being divided into two lots. One batch is frozen, while the other is dehydrated and embedded. The indirect antibody enzyme method is applied to ultrathin sections obtained by cryoultramicrotomy after freezing or by sectioning after embedding. All six pituitary hormones are detected by both methods. Comparison shows that the morphological characteristics are identical for both techniques, though ultrastructural preservation is better after embedding. Immunoreactivity is found in secretory granules and sometimes in the endoplasmic reticulum. Osmium postfixation may reduce or even abolish antigenicity in plastic‐embedded tissue. After cryoultramicrotomy, however, even after osmium fixation, antibody may be used 1000 times more diluted than after plastic embedding. Embedding preserves ultrastructure and limited antigenicity while the use of cryoultramicrotomy is a far more sensitive technique.
An ultrastructural study of cryofractured myocardial cells with special attention to the relationship between mitochondria and sarcoplasmic reticulum
Authors: Dalen Helge , Scheie Paul , Myklebust Reidar , Sætersdal Thorvald
Published: August 2011

A comparative study of various cryofracturing techniques has been conducted on the mammallian myocardial cell. Quench freezing of fresh or fixed tissue in melting Freon 22 resulted in severe cellular damage due to ice crystallization. Fixation with Karnovsky's fixative prior to quenching had no modifying effect on the size and distribution of the ice crystals. The crystals were orientated primarily in the direction of the long axis of the myofibrils, manifested as empty tube‐like structures in the scanning electron microscope (SEM). Regular cross‐bridging often seen at the Z‐band levels indicated that ice crystals, at least in some portions of the cells, were confined within the sarcomere. Within the same cell the size of the ice crystals could vary considerably.

Treatment of the tissue with polyvinylpyrrolidone (PVP) prior to rapid freezing had no noticeable cryoprotective effect. The surface of the thin layer of PVP surrounding the freeze dried tissue appeared amorphous in the SEM. However, the first evidence of ice crystallization was found a few micrometres under the surface.

The freezing artefacts were completely circumvented if the cryofracturing was carried out on ethanol‐impregnated or on critical point dried material. While the first method resulted in a smooth fracture plane passing through the cell structures, the intracellular fracture plane of the critical point dried material followed the surface of the cell organelles.

Separation of the cell organelles caused by freezing or by critical point drying revealed thread‐like structures extending from the mitochondrial surface. Re‐examination of SEM‐processed material in the transmission electron microscope (TEM) revealed that these structures were part of the sarcoplasmic reticulum (SR), and that a close contact between the SR and the outer mitochondrial membrane existed. TEM of conventional prepared material revealed that strands of electron‐dense material, here named ‘mito‐reticular junctional fibres’, bridged the narrow gap between the mitochondrial surface and the SR. It is suggested that these fibres have a specific anchoring function.
The effects of embedding in water‐soluble plastics on the final dimensions of liver sections
Authors: Hanstede J. G. , Gerrits P. O.
Published: August 2011

This paper describes the morphometric changes liver samples undergo in the course of fixation, dehydration, infiltration and embedding in different mixtures of water‐soluble plastics. The plastics used were: three different mixtures of glycolmethacrylate (GMA) and the commercially available material JB4.

Buffered formaldehyde fixation did not produce significant morphometric changes in the liver specimens. Dehydration obviously affects the volume of the liver specimen (linear shrinkage about 9.3%). The dehydration is followed by an infiltration phase. During this phase a slight swelling (linear, 2–5%) occurs. The final polymerization of the plastic resulted in a further linear shrinkage of 1–2%.

The influence of different technical factors on the stretching of sections of pure plastic and of plastic embedded liver appeared to be considerable. The difference in stretching between 2 and 3 μm sections has been studied. A significant influence of temperature upon section stretching was noted. Sections of all plastic mixtures stretched at a temperature of 293 K showed 3% more linear stretch than at a temperature of 333 K. Differences between the four plastic mixtures are discussed.

Correction factors must be used in morphometrical and stereological investigations (see for review: Weibel, 1979). It was concluded that in the application of water‐soluble plastics as embedding media it is essential to apply a standardized procedure, particularly in the cutting and stretching phase.
Quantitative determination of elements by energy dispersive X‐ray microanalysis and atomic absorption spectrometry in egg cells of Lymnaea stagnalis
Authors: Elbers P. F.
Published: August 2011

Magnesium, phosphorus, potassium, calcium and iron in Lymnaea stagnalis egg cells at the four cell embryonic stage were quantitatively analysed by energy dispersive X‐ray analysis. The accuracy of the results was confirmed by atomic absorption spectroscopy using the graphite tube atomizer. It is shown that at 20 kV acceleration voltage the Hall equation can be applied in X‐ray microanalysis of air‐dried biological specimens of up to 8 μm thickness when calibration standards of nearly the same thickness and elemental composition are used.

In the past few years considerable effort has been devoted to the X‐ray microanalysis of cells and subcellular structures in tissues. Special interest went to the determination of local concentrations of low atomic weight elements in the cells (Gupta et al., 1978). These elements partly occur in the form of mobile ions and their concentration distribution is easily disturbed by preparative procedures. Only cryogenic methods, like freeze‐sectioning (Echlin & Moreton, 1974) and freeze‐fracturing (Zs‐Nagy et al., 1977) are able to meet these problems of preparation.

With single cells, e.g. invertebrate egg cells or amoebae, the situation is somewhat less complicated because these cells can be handled individually. A number of problems in cell biology, e.g. ion movement during the cell cycle, may be solved by analysis of the ion content of whole cells. Dried down Lymnaea egg cells at SEM accelerating voltages can be considered as semi‐thick specimens in which the local mass per unit area will show some variation. In order to convert X‐ray data from these specimens to concentrations, semi‐thick calibration standards should be prepared with essentially the same matrix composition as the biological material. Under such circumstances the equation
Polylysine as an adhesive for the attachment of nanoplankton to substrates for electron microscopy
Authors: Marchant Harvey J. , Thomas David P.
Published: August 2011

Nanoplankton can be readily attached to polylysine‐coated substrates for examination by transmission and scanning electron microscopy. This simple technique gives high yields of organisms which are consistently better preserved and less obscured by detritus than samples dried directly on to substrates.
Estimating length density and quantifying anisotropy in skeletal muscle capillaries
Authors: Mathieu Odile , Cruz‐Orive Luis‐M. , Hoppeler Hans , Weibel Ewald R.
Published: August 2011

The accurate estimation of stereological parameters defined on anisotropic structures is a long‐standing problem. In this paper we seek to estimate the capillary length density Jv in skeletal muscle tissue. A well‐known model for directional anisotropy in space, namely the ‘spherical normal’ or ‘Fisher axial distribution’ model, is found to fit the relevant data satisfactorily. Based on this model, a short‐cut estimation method is proposed and illustrated with a numerical example. This method essentially consists in taking the ratio of mean capillary profile counts, as obtained from transversal and longitudinal sections of the muscle tissue, and making use of a table or a graph given in the paper to estimate Jv. The conditions under which the methods are applicable and practicable are discussed in detail. Apart from an accurate estimation of Jv, an important feature of our method is the possibility of quantifying the degree of anisotropy by a coefficient K (called the concentration parameter of the Fisher axial distribution), which enjoys both a biological significance and a sound statistical basis.
Inter‐animal variation and its influence on the overall precision of morphometric estimates based on nested sampling designs
Authors: Gupta Madhu , Mayhew T. M. , Bedi K. S. , Sharma A. K. , White F. H.
Published: August 2011

This paper provides additional experimental evidence that biological variation between individuals is likely to be the major factor influencing the overall precision and efficiency of nested sampling schemes for morphometric analysis of thin sections.

Four distinct experimental systems (two based on nervous tissue and two on epithelia) have been investigated. Morphometric estimates were obtained from measurements made on micrographs generated by sampling tissues at several levels. Sources of sampling variation were isolated so that the contributions to overall variance made by inter‐animal differences could be evaluated.

In each case, biological variation was the cardinal component of total observed variance between animals. Relative contributions ranged from 53% to 78%. Examining more animals would be the most efficient way of reducing the variance of the group mean in these sampling designs.
Refractometry of fungi
Authors: Joseph S.
Published: August 2011

Immersion refractometry is based on matching the refractive index of the medium to that of the cytoplasm of the cell, in which case the latter will have minimum contrast in the phase contrast microscope and will practically disappear. The cytoplasm is then said to be at the match point with the medium. Since the refractive index of a solution is related to its concentration by the formula n ‐ no =αC, the values for the refractive indices can be expressed in terms of the concentration of solids (g/100 ml) which in fact has been done throughout this work. The properties of a suitable immersion medium, its preparation and interpretation of numerical results have been discussed. Refractometric measurements were carried out on fungal hyphae and spores. The solid concentration in hyphae varies according to their age, physiological state and function. In general the highest values are found at sites of physiological activity, such as growth and reproduction, and may range from 11% to 30% of solid concentration. The solid concentration of mature, resting spores was found to be in the range of 45–54%, with the exception of a powdery mildew spores in which the concentration of solids was 30–32%.

The germination of spores is preceded by a fall in the concentration of solids, and subsequent swelling before the emergence of the germ tube. When the solid concentration in pregerminating spore has fallen to about 20–30%, metabolic activity can take place and germination can occur.
Experimental lymphatic metastasis
Authors: Carr Ian
Published: August 2011

A model of lymphatic metastasis of cancer has been established by injecting tumour cells into the rat footpad and examining the draining popliteal lymph node. The node can probably destroy only a few tumour cells; thereafter metastasis is progressive and lethal. The tumour cells penetrate the lymphatic endothelium, in the footpad either by moving singly between intact endothelial cells, by destroying the endothelium, or by passing in clumps between the endothelial cells. Tumour cells may then be obtained from the lymph by cannulation of the lymphatic trunk. These experiments pose the question: is local lymphatic chemotherapy useful in treating lymphatic metastasis?
A high‐resolution staining method for examination of mammalian cell surfaces in the light microscope
Authors: Junker Steffen
Published: August 2011

A simple light‐microscopic method for the examination of fine details on cell surfaces is described. When cell specimens on platinum‐coated glass or plastic surfaces are stained with 3,3′‐diaminobenzidine tetrahydrochloride and hydrogen peroxide, fine cytoplasmic processes that cannot be detected using conventional staining techniques for the light microscope are revealed. It is suggested the new technique be applied instead of the scanning electron microscope when the limited resolution of the light microscope is sufficient.
A statistical method for the analysis of quantitative thin‐film X‐ray microanalytical data
Authors: Blake D. F. , Isaacs A. M. , Kushler R. H.
Published: August 2011

A series of equations is presented through which thin‐film X‐ray microanalytical data may be characterized statistically. Test statistics based on the Gaussian distribution are then presented, together with examples of the use and evaluation of an empirically derived Mg/Ca working curve.
Particle sizes and their distributions estimated from line‐ and point‐sampled intercepts. Including graphical unfolding
Authors: Gundersen H. J. G. , Jensen E. B.
Published: August 2011

Information about particle size is currently obtained almost exclusively by the use of stereological methods which lead to estimates of the number distribution of linear particle size. The main point of this presentation is to stress the freedom to choose more appropriate parameters for size among a host of options, including particle surface area and volume. Moreover, particle size information may often be considered advantageously in terms of particle distributions based on structural characteristics rather than number distributions. Some of these other distribution types are correctly represented in samples of intercept lengths obtained by line‐ and point‐sampling, respectively. The known and quite simple theory of sampling intercepts is summarized and developed further in several different directions, including a derivation of the distribution of intercept length in ellipsoids, graphical unfolding procedures, and mean size estimators. The potential of the approach is illustrated—but not exhausted—by the existence of a general mean size estimator based on minimal assumptions regarding particle shape.
Stereology of tubular structures
Authors: Baddeley A. , Averback P.
Published: August 2011

The morphology of a tubular structure can be characterized, in at least some of its important respects, through stereological methods. We study the geometric meaning of standard stereological quantities when applied to tubular structures, with particular regard to their curvature or tortuosity. Measures defined specifically in relation to tubular structures are also introduced for practical use. The ideal smooth bent cylinder, used here, is not realistic but provides general principles from which a more specialized investigation should be developed. The emphasis is placed on simple counting methods of measurement, specifically the tangent counts introduced by DeHoff, and counts of section profiles exhibiting a particular character (such as ‘figure‐eights’). These measures convey information about the tortuosity of tubular structures, whereas the standard indices Vv, Sv, Mv give no information about tortuosity. Some data from human testicular tubules are discussed.
Dislocation structures in fatigued polycrystalline stainless steel
Authors: Fielding S. E. , Stobbs W. M.
Published: August 2011

The dislocation structures produced in polycrystalline Fe‐25Cr as a result of push‐pull fatigue are described with reference to the Schmid factors of the active slip systems in different grains. The activity of the structures is discussed in relation to an etch which is indicative of localized shear activity. The ladder and labyrinth structures seen are compared with those which form in f.c.c. material.
The metallographic characteristics of fatigue cracks in the titanium alloy IMI829 at 400°C and 600°C
Authors: Hamdy M. M. , Noble B. , Waterhouse R. B.
Published: August 2011

High temperature fatigue tests under fluctuating axial tension were carried out on the alloy in the fully heat treated condition, the microstructure consisting of a β matrix containing colonies of aligned α‐platelets. Fatigue cracks were initiated by fretting at temperatures of 400°C and 600°C. A detailed metallographic examination has been made of the fretted region and the resulting fatigue crack and these characteristics have been related to the microstructure of the alloy. At test temperatures of 400°C the fatigue cracks initially propagated at right angles to the α‐platelets but where their orientation was unfavourable, propagation also occurred parallel to the α‐platelets. At test temperatures of 600°C the initial direction of crack propagation was independent of the microstructure.
Digital image processing of combined SEM and EDX signals
Authors: Bauer B. , Schwarz H. , van Thanh Nguyen
Published: August 2011

Due to the complexity of biological tissue and man‐made materials, the limits of light microscopy in quantitative image analysis are often reached. The scanning electron microscope provides a much higher resolution in such situations, especially when using the low noise secondary electrons signal. However, secondary electrons are sensitive to topography rather than to the elements constituting the specimen. This effect usually makes discrimination of distinct phases or objects by simple grey value thresholding difficult or even impossible.

The additional information given by an energy dispersive X‐ray system is the step to overcome this problem. The combination of both signals—grey level and energy dispersive information—leads to a masking procedure which eliminates image sections, not belonging to the phase under investigation, from the evaluation.
A method for mapping localized displacement fields in boundaries
Authors: Donovan P. E. , Stobbs W. M.
Published: August 2011

A new method is described for the initial characterization of the displacement fields of defects on boundaries. This approach can be applied to defects and boundaries which cannot easily be modelled, since it involves the comparison of known with unknown fields. An application of the technique to the study of a bcc/fcc phase boundary in a steel is also described.
Structures of insoluble carbon in tars and pitches
Authors: Kremer Henry A. , Cukier Samuel
Published: August 2011

Primary or True QIs, and also the so‐called ‘dirt’ were separated from seven tar sources available in Canada from four different steel companies, by filtering hot tar solution of quinoline and other good solvents. After washing with quinoline and acetone and drying, the filter cake was examined under scanning electron microscope (SEM) and analysed for inorganic impurities by wave length and energy dispersive X‐ray spectrometers. A limited amount of work was carried out on a production pitch blend, utilizing optical microscopy.

After the filtration process, the filtrates which represented the QI free tars were subjected to distillation at atmospheric pressure and various pitches were prepared with a softening point range of 70–100°C. The pitches were dissolved in quinoline and analysed for QIs. The small amount of QI from each pitch was extracted and dispersed with solvent onto a microscope slide. The samples then were subjected to SEM and in one case to optical microscope studies; the sizes and shapes of the QIs were determined and compared with the QIs originally found in the individual tars. Photographs have been taken during the scanning work to record findings which have been considered typical and demonstrative of the findings.

In order to gather further information on the role of QI in tars and pitches, particle size distribution was determined of QI extracted from a tar and a production pitch by a Coulter Counter.
The microscopy of mesophase formation and of anisotropic cokes produced from solvent‐refined coals
Authors: Davis Alan , Hoover David S. , Wakeley Lillian D. , Mitchell Gareth D.
Published: August 2011

Thermal processing of coal and coal products can lead to the formation of ordered carbons through the mesophase mechanism. The performance characteristics of metallurgical coke may be improved by the extent of this ordering; however, in the direct hydroliquefaction of coals the objective is to make species of low molecular weight, and coking is an undesirable retrograde reaction. This study is concerned with fundamental mechanisms of coke formation and their roles in these two processes.

Most studies of mesophase formation have involved the heat treating of samples followed by quenching and examination at room temperature. This project has used hot‐stage microscopy and the production of a 16‐mm colour film to study the dynamics of mesophase growth and coalescence.

Various solvent‐refined coal (SRC) and SRC fractions were carbonized in gold tubes at 450°C and 34.5 MPa, and the pyridine‐insoluble fractions (semi‐coke) examined microscopically. Greater molecular mobility, manifested by lower proportions of anisotropic carbon and larger domain sizes, was evident for SRCs which had undergone more extensive hydrogenation at the pilot plant, and for SRC fractions of lower functionality.

The performance of metallurgical coke in the blast furnace can be related to its inherent carbonaceous structure. Coals which give cokes of marginal quality include low‐rank bituminous coals which form an optically isotropic coke. One method of improving the carbon ordering in these cokes is the use of a carbonizing additive. In this study SRC was used as the additive, giving improvements in the coke structure and microstructure.
Microscopy of porosity in metallurgical cokes
Authors: Patrick J. W.
Published: August 2011

The importance of the porous structure of coke in industrial usage has been recognized for many years but the difficulties involved in determining by manual microscopic methods, quantitative details of the structure precluded comprehensive and detailed studies. With the advent of computerized image analysis systems it has become possible to overcome many of the practical difficulties associated with the determination of structural data for a material as heterogeneous as metallurgical coke. Techniques based on reflected light microscopy and automatic image analysis have been developed to the extent that representative and reliable structural characterization of coke can be achieved. The data so obtained have been used to derive strength/structure relationships which enable coke strength to be predicted with a standard error comparable with that of the experimental determination and the structural characterization now offers an additional means of defining coke quality with potentially significant industrial applications.
Evaluation and interpretation of grain density autoradiographs by reflectance photometry
Authors: Mai J. K. , Krauthausen I. , Jennissen J.‐J.
Published: August 2011

The tritium content of nervous tissue sections is calculated from grain‐density of autoradiographs without loss in anatomical information. The calculation is not based on determination of (expected) grain numbers but on photometric measurements (SKphot), interpreted as the result of the function of exposure time (T) and incorporated activity (β): SKphot = f (T, β).

As experimental radiation standards homologous material (optic nerve preparations) with different activities determined by liquid scintillation counting has been used. Exposure times between 12 h and 28 weeks for these preparations with known radioactivities yielded a set of curves (nomogram) relating photometric values to exposure times. At any given exposure time the knowledge of photometric readings and related radioactivities within that set of curves enabled the development of a function covering all photometer readings within the range of the nomogram. Thus, any photometric reading could be correlated to the corresponding radioactivity.

Such a function has been applied for the transformation of photometric values obtained from particular brain‐section areas exposed for 16 weeks. Since the results are given in Bq, they may be related and, if necessary, corrected to results obtained by other tritium detection methods.

Terminology used in the text: experimental radiation source = experimental standards prepared from optic nerve sections; standard radiation source = polymer reference source.
Sampling problems in an heterogeneous organ: Quantitation of relative and total volume of pancreatic islets by light microscopy
Authors: Kroustrup J. P. , Gundersen H. J. G.
Published: August 2011

In stereological studies analysis of sampling variances is used for optimizing the sampling design. In organs with a heterogeneous distribution of the phase of interest the analysis of sampling variances can be undertaken only if the observed variance between sections is distributed into the fraction which is due to random variation and the fraction which is due to the heterogeneity. In the present example (pancreatic islet volume estimated by light microscopic point‐counting) the density of islets showed a linear increase along the axis of the organ. By analysis of sampling variances it was calculated that the most efficient number of sections (cut perpendicular to the organ) was considerably lower when the isolated contribution from the random variation was considered.

The total islet volume was obtained by the product of the fractional islet volume and the pancreatic weight. Analysis of sampling variances of the total islet volume was performed by including the variance contribution from the individual pancreatic weights to the variance of the group mean total islet volume. Due to a negative correlation between the fractional volume and organ weight the total islet volume in the group of animals was more precisely estimated than the fractional islet volume.

The methods used for dealing with the heterogeneity of the organ and for estimating sampling variances of total structural quantities generalize to a large number of stereological studies in biology.
A new method for unfolding sphere size distributions
Authors: Taylor C. C.
Published: August 2011

Spherical particles are embedded in an opaque matrix. Circular profiles with radii X1,…, Xn are then observed from a cross‐section. To estimate the distribution of the particle sizes a two‐stage method is proposed. The probability density of the profile radii is statistically estimated by a smooth, piecewise quartic polynomial, and then an inversion formula is used. The method has some advantages over existing techniques in that the estimate is continuous, is quite straightforward computationally and it involves a less subjective choice of statistical parameters. In the case of several types of distributions, the procedure performed well for simulated data.
Specimen holder improvements for the study of amphibian skin pigmentation
Authors: Hedin C. Anders
Published: August 2011

A skin specimen holder was constructed permitting nearly identical experimental conditions during in vitro spectrophotometry and photomicrography of amphibian skin melanocytes. The specimen holder was made of non‐corrosive steel thread and made to fit a spectrophotometer cuvette and the light microscope stage. The improvements were compared to earlier constructions.
The current status of fixation for electron microscopy: A review
Authors: Bullock Gillian R.
Published: August 2011

Chemical fixation of cells has been used extensively in different fields of electron microscopy. The type of fixation can be selected to maximize retention of different cell constituents where morphology is of prime interest. For techniques such as immunocytochemistry and autoradiography, a compromise between morphology and retention of antigenicity or radiolabel has to be reached. By careful choice of fixative, buffer and other physical parameters, optimum results can be obtained for both animal and plant tissues. Emphasis has been put on more recent developments in technique.
The use of high‐voltage electron microscopy and semi‐thick sections for examination of cyanobacterial thylakoid membrane arrangements
Authors: Nierzwicki‐Bauer S. A. , Balkwill D. L. , Stevens S. E.
Published: August 2011

High‐voltage electron microscopy (HVEM) of semi‐thick sections was evaluated as a technique for studying thylakoid membrane arrangements in cyanobacterial cells. Semi‐thick sections (0·25 μm) provided important information that was relatively difficult or impractical to obtain by viewing either randomly or serially cut thin sections. Specifically, the semi‐thick sections were better suited for visualizing (i) overall thylakoid arrangements and (ii) interconnections between the thylakoids and the cytoplasmic membrane. By comparison, randomly cut thin sections frequently yielded deceptively incomplete or inconsistent data in regard to these specific features. Tilting of thick sections about two perpendicular axes served to improve the clarity of complex membranous intersections and other cell features.
A method differentiating between bacterial adhesiveness and invasiveness in cell culture monolayer
Authors: Bukholm Geir , Johansen B. V. , Namork Ellen
Published: August 2011

In order to differentiate between bacterial adhesiveness and invasiveness in cell culture monolayers, a method is reported which enables the same specimen to be examined by both scanning electron microscopy and Nomarski interference contrast microscopy. The source of error made by statistical variation when the two microscopical techniques are used individually is thus avoided.
An acidic silver staining method for synaptonemal complexes under light microscopy
Authors: Fernandez‐Piqueras José , Castaño Carlos Sentis , Garcia E. Rojo , Campos A. Rodriguez
Published: August 2011

A simple method is presented by which synaptonemal complexes (SCs) can be visualized under bright field microscopy. Staining was accomplished with a silver nitrate solution adjusted to pH 3–3·5 with formic acid, after an acidic fixation. This method is suitable for the demonstration of SCs, centromeres and NOR regions in both mammalian (Rattus norvegicus, ‘Wistar’) and orthopteran spermatocytes (Steropleurus martorelli complex). Results suggest that pretreatment with solutions of alkaline pH are not needed for demonstrating SCs, and that the silver impregnation may also operate when the proteinaceous lateral elements of the SC are subjected to low pH conditions. Differential staining of the X chromosome during meiosis in Orthoptera, and a core‐like structure in the chromosomes during the more condensed stages of meiosis and mitosis can also be shown.
Acoustic beam position monitor for microanalysis of particles in the 10 nm range in a TEM‐SCAN system
Authors: Sørensen Ole , Andersen Jesper Refslund
Published: August 2011

This paper describes the principle and use of a simple equipment which makes it possible to keep the electron beam in the centre of a small particle analysed by X‐ray microanalysis in a STEM system. A deviation from the correct beam position introduced by drift or other deficiencies is monitored by an audible change in a sound frequency and corrected for by a convenient manual operation.
An interference technique for measuring the thickness of semi‐thin and thick sections
Authors: Robertson W. M. , Storey B. , Griffiths B. S.
Published: August 2011

An interference method is described for measuring section thickness in the range 0·3–45 μm. An incident illumination objective incorporating a beam splitter and adjustable reference mirror is used to generate interference fringes by reflection from the upper surfaces of sections on glass slides. Sections do not require a reflective coating. The lateral displacement of the zero‐order fringe generated using white light is measured in terms of sodium light fringes and photographic enlargement of the fringes allows measurement to ± 30 nm. The method is simple in operation and allows rapid assessment of any local distortions over the entire section area.
Caveat on the use of alloys for surface replication
Authors: Williamson Francis A. , Pillinger Raymond N.
Published: August 2011

Some replicas of plant cell surfaces produced by platinum/palladium evaporation were of very poor quality. Scanning electron microscope X‐ray microanalysis showed that only Pd was evaporated from the Pt/Pd alloy, leaving the Pt on, or alloyed with, the tungsten filament used for evaporation.
Alteration of cartilage matrix morphology with histological processing
Authors: Cole Madison B.
Published: August 2011

An interlacunar network in the extracellular matrix of femoral head articular cartilage of neontal rats was seen by light microscopy to: (1) consist of elements, 0·5 μm thick, which occurred as individual elements, as bundles of elements, and as fused elements, (2) stain intensely with toluidine blue, methylene blue, and safranin O, and (3) connect chondrocytes by inserting on the chondrocyte capsules which were composed of morphologically and cytochemically similar material. By electron microscopy, the single elements were seen to be composed of thicker, denser staining areas of the honeycomb appearing matrix and the fused elements appeared as non‐membrane bound channels containing granular material.

Articular cartilage was processed using combinations of fixatives, dehydrating agents, and embedding media. Regardless of fixation, demineralization, or embedding, the network was not seen after dehydration of the cartilage with methanol, ethanol, acetone or tert‐butanol but was seen after dehydration with aqueous solutions of glycol methacrylate, propylene oxide, 2‐propanol or 2,2‐dimethoxypropane. Network visualization following a variety of methods demonstrated that no single fixative, dehydrating agent, or embedding medium caused its formation. The presence of the network in different cartilage zones, its consistent morphology by light and electron microscopy, the uniformity of the elements in their connection with the chondrocytes, and presence in fresh‐frozen sections suggest the network may be real, but rigorous evidence for its existence in vivo is still required.

Since cartilage morphology was altered by histological methods, especially dehydration, common methods used in studying connective tissue matrix should be evaluated to determine their effect on matrix morphology.
Scanning optical fluorescence microscopy
Authors: Cox I. J.
Published: August 2011

A scanning optical fluorescence microscope is described which possesses several advantages over a conventional fluorescence microscope. These include improved resolution, a reduction in background‐ and auto‐fluorescence, an increase in the available fluorescence spectrum and simple modification for automated fluorescence studies. Experimental results are included.
The application of scanning transmission electron microscopy (STEM) to the study of thin anodic films on nickel and nickel‐molybdenum alloys
Authors: Moriya M. , Ives M. B.
Published: August 2011

Anodized thin‐film samples of nickel, molybedenum and a nickel‐13 w/o molybdenum alloy have been analysed by scanning transmission electron microscopy, using selected area diffraction, microdiffraction and X‐ray micro‐analysis.

Thin‐film samples were obtained by ion thinning with argon and by electropolishing in acetic acid‐perchloric acid. Electropolishing is the preferred technique for these studies, producing a surface with roughness on a scale of 1 nm.

The anodized films on nickel and nickel 13 w/o molybdenum alloy exhibit a rugosity with a ‘particle’ size of 3 nm. The crystal structure of the films is similar to f.c.c. nickel oxide.

Molybdenum enrichment was detected in the anodized alloy surfaces but there is no electron diffraction evidence for a crystalline molybdenum oxide. The electron diffraction pattern from anodized pure molybdenum suggests that the surface film is amorphous.
A method for exposing the internal anatomy of small and delicate tissues for correlated SEM/TEM studies using polyethylene glycol embedding
Authors: Nagele R. G. , Doane K. J. , Lee H. , Wilson F. J. , Roisen F. J.
Published: August 2011

A method for preparing and handling large, clean, distortion‐free cut surfaces through small and delicate tissues for correlated SEM/TEM examination is described. In this method, tissues are fixed according to conventional protocols; however, instead of critical‐point‐drying after fixation, tissues are first embedded in polyethylene glycol (PEG), a water‐soluble waxy solid. Tissue blocks are easily oriented and sectioned to the desired regions, immersed in a solvent to remove PEG, critical‐point‐dried, and examined with an SEM. The same tissue blocks can be reworked for TEM by immersing in propylene oxide and embedding in an epoxy resin.
Some recent experience with the scanning electron microscope in corrosion research
Authors: Stott F. H.
Published: August 2011

Corrosion and oxidation are the results of chemical reaction between a solid surface (such as of a metal or alloy) and its environment, to form a corrosion product. The product may adhere to the surface, thereby usually providing some protection from further attack, or may be removed from it (e.g. by volatilization or by dissolution in the environment). In either case this leads to changes in topography, morphology and, often, composition of the surface. Study of such changes can provide considerable information and assistance in the determination of the mechanisms of degradation. Scanning electron microscopy with associated microanalysis has thus enabled significant advances to be made in understanding many corrosion and oxidation processes. The progress attained in several areas where the technique has played a major part but has been extended to its maximum capabilities is discussed and related to the particular advantages and limitations of scanning electron microscopy in this field. One such area is the study of high‐temperature corrosion processes. Here, the high resolution and depth of focus of the instrument have provided detailed information on the microstructure of high‐temperature oxide and other corrosion‐product scales and underlying alloy. For instance, the sizes and distributions of pores in the scales give important insight into the possibility of growth mechanisms involving gas‐phase transport within the scales themselves. Associated microanalysis can assist in identification of rate‐determining layers and of other localized diffusion paths which can short‐circuit bulk lattice diffusion.
A preparation method for observing intracellular structures by scanning electron microscopy
Authors: Tanaka Keiichi , Mitsushima Akira
Published: August 2011

In order to observe intracellular structures by scanning electron microscopy, excess cytoplasmic matrix must be removed from the fractured surface of cells. Previously we reported an Osmium‐DMSO‐Osmium method devised for this purpose. This method is very effective in revealing intracellular structures, but requires osmium tetroxide for initial fixation with some consequent disadvantages. In the present study, a revised Osmium‐DMSO‐Osmium method is reported, in which an aldehyde mixture is used as the initial fixative instead of osmium tetroxide. As fixation is carried out by perfusion in this revised method, better preservation of fine structures is achieved than by the original method, especially in the central nervous tissue which tends to suffer from post‐mortem degeneration. Moreover this method can be applied to cytochemical studies of intracellular structures with a scanning electron microscope (SEM). In this study, acid phosphatase of lysosomes is demonstrated in a coloured SEM micrograph.
A simple apparatus for radioautographic coating
Authors: Markov Dimiter V.
Published: August 2011

The apparatus described is designed for monolayer emulsion coating in electron microscope radioautography. The slides with the sections are not withdrawn from the emulsion, but it is allowed to flow out of the dipping jar thus coating them.
A section press and low elemental support for enhanced preparation of freeze‐dried cryosections
Authors: Tvedt K. E. , Kopstad G. , Haugen O. A.
Published: August 2011

A press‐ and specimen holder system is described, whereby thin, freeze‐dried cryosections can be obtained more conveniently and with greater protection against contamination and harmful temperature fluctuations. The use of a grid and retainer assembly as the basic working unit, greatly facilitates low temperature work particularly when delicate grids are preferable from an analytical point of view. A new press has been constructed in order to keep the sections permanently pressed during freeze‐drying and rewarming. The press also protects the sections during transfer to an external freeze‐dryer.
Methylamine tungstate and tannic acid in fixation for high contrast and preservation of fine structure: application to myxomycete plasmodia
Authors: Chestnut Matthew H. , Cohen Arthur L.
Published: August 2011

The effects of several fixation methods for electron microscopy were compared, using macro‐plasmodia of Badhamia utricularis (myxomycete) as test objects. A brief osmium tetroxide (Os) exposure followed by a mixture of glutaraldehyde (GA) and tannic acid (TA) with subsequent treatment with methylamine tungstate (MAT) overcame most commonly encountered difficulties in fixing these structures. Lead staining of the sections was necessary to bring out the range of densities inherent in the delicate detail of ground cytoplasm, membranes, and organelle structure retained by Os/GA‐TA/MAT. Microfilaments were well preserved with good contrast and little evidence of breakage. Although GA as the initial fixative gave good organelle preservation, Os pretreatment was required to prevent artefactual changes in plasmodial strand morphology. The several fixation procedures tested gave pronounced differences in mitochondrial appearance, in some cases giving a negative stained appearance to the cristae. Some advantages in interpretation may result from such reversed contrast. The high contrast and range of densities achieved following the Os/GA‐TA/MAT schedule permitted routine use of thin (silver‐grey) sections, thereby potentially increasing the resolution.
Automatic analysis of G‐banded human chromosomes by fast scanning microscope photometry. I. Basic principles and computer control
Authors: Wall W. J. , Butler L. J.
Published: August 2011

A high resolution scanning microscope photometry system has been developed for use with standard G‐banded chromosome preparations. Various alternative scanning methods and their limitations are reviewed.

The computer algorithms which we use are described for the manipulation of the digitized image as produced by the microscope photometer; these include noise reduction and contrast enhancement as well as altering the orientation of the chromosome.
Testing of detector strategies in scanning electron microscopy by isodensities
Authors: Lange M. , Reimer L. , Tollkamp C.
Published: August 2011

The dependence of the video signal of secondary electrons (SE) and backscattered electrons (BSE) on the local tilt angle φ and azimuth angle χ is important for the interpretation of micrographs and for comparing different detector strategies. The conventional Everhart‐Thornley detector (scintillator‐photomultiplier combination) has the disadvantage of collecting the SE with an efficiency which depends on too many geometric parameters of the specimen chamber.

A more quantitative recording of SE and BSE can be realized by a multi‐detector system. For example, the signals A and B of two opposite detectors can be used to record the image with the difference signal A‐B or the sum signal A+B.

Testing of these techniques requires a simple method of recording and comparing the dependence of the video signal on φ and χ for different detection modes and in different microscopes. This was tried by recording lines of equal video signal (isodensities) with a sphere as a test specimen.
A review of crystallographic calculational methods used in the RAD group of computer programs for analytical electron microscopy
Authors: Carr Martin J. , Chambers William F.
Published: August 2011

RAD is a set of computer programs which has been developed to assist a microscopist who is doing electron diffraction analysis. The programs are designed to run on the computer which is normally supplied with a modern analytical electron microscope for X‐ray analysis. Matrix algebra methods are used to perform the crystallographic calculations; however, input and output are expressed in the familiar notational convention based on the Miller index system for directions and planes. Since all calculations are formulated for the most general crystal system (triclinic), they are applicable to all crystal types. Aspects of the Miller index system, vector analysis, and matrix algebra that pertain to the crystallographic calculations made by programs in the ‘RAD’ group are reviewed. Examples used to illustrate typical operations that can be easily accomplished by these methods include the calculation and plotting of stereographic projections and of electron diffraction patterns from single crystals, twinned crystals, and crystals containing oriented second phases.
Ultrastructural comparison of ion beam and radiofrequency plasma etching effects on biological tissue sections
Authors: Linton R. W. , Farmer M. E. , Ingram P. , Sommer J. R. , Shelburne J. D.
Published: August 2011

Three dry etching techniques (Ar+ ion beam, O2+ ion beam, O2 radiofrequency electrodeless discharge) were compared with respect to preferential etching and damage to the ultrastructure of glutaraldehyde‐fixed Epon‐embedded frog skeletal muscle sections. SEM and TEM studies were performed on both unstained and stained (osmium tetroxide, uranyl acetate) sections. Etching effects were observed to differ for the various ion beam or plasma etching techniques. Whereas selective retention of electron dense structures (e.g. Z lines, nuclear heterochromatin) was observed for oxygen plasma etching, preferential etching of these components was observed using O2+ ion beam bombardment. Selectively etched Z lines and etch‐resistant nucleoli were observed for both reactive (O2+) and inert (Ar+) ion beam sputtering after sufficiently high ion doses. The above suggest that selective etching under keV ion beam irradiation is related more to physical sputtering processes (momentum transfer) than to the chemical reactivity of the incident ion. Heavy metal post‐fixation and staining had no qualitative effect on the nature of the selective etching phenomena. The above findings are significant in that they potentially influence both electron and ion microprobe measurements of etched biological specimens.