bluuebunny/crossref_metadata_2025_split huggingface dataset:
An energy filter for biological electron microscopy
Authors: Henkelman R. M. , Ottensmeyer F. P. 
Published: August 2011

SUMMARYA prism‐mirror‐prism electron energy filter has been inserted into a fixed beam transmission electron microscope. The insertion of the filter has not degraded the spatial resolution of the microscope, while providing an energy resolution of 2.5 eV. The filter greatly reduces the chromatic aberration of the images, increasing resolution in dark field and contrast in bright field. Images of bacteriophage T4 and of polyoma virus indicate that thick unstained and unshadowed biological specimens can now be observed at high resolution in dark field. In addition, the increased contrast and definition observed in bright‐field images of conventional liver sections suggest that it should be possible to obtain sufficient contrast from stains containing atoms of lower atomic numbers than those employed at present.
Local beam heating in metallic electron microscope specimens
Authors: Kritzinger S. , Ronander E. 
Published: August 2011

SummaryA very sensitive method is described to measure the local rise in the temperature of a metal specimen during investigation in the electron microscope. The method is based on the known temperature dependence of the climb rate of Frank dislocation loops in materials with relatively high stacking fault energy. The climb rate of loops subject to the influence of the condensed electron beam is compared to the corresponding rate for loops in an area of the same specimen which is remote from the observation spot. From the difference in the logarithms of these rates the amount of local beam heating is determined. For a typical Al‐1.5 wt% Mg specimen under typical normal working conditions an average local rise in temperature of approximately 6°C was determined.
Scanning electron microscopy of injection replicas of the chick embryo circulatory system
Authors: Dollinger Russell K. , Armstrong Peter B. 
Published: August 2011

SummaryThe injection replication procedure has been modified for study of the thin and very delicate blood vessels of young embryos. Batson's corrosion compound (a polyester resin) modified for rapid polymerization (20:3.0:0.25, monomer: catalyst: promoter) was effective in replicating even very small blood vessels without excessive distension. Since injection of plastic induced violent heart spasms with eventual expulsion of plastic from the ventricular lumen, contractility of the heart was inhibited by injection of a 2% (w/v) aqueous solution of KNO3 prior to injection with polyester resin. Following polymerization of the injected resin, the tissues were macerated and removed, leaving a solid three‐dimensional cast of the lumen of the circulatory system. The casts were photographed with the scanning electron microscope to produce accurate micrographs for study of the developmental anatomy of the circulatory system.
Caveat on the use of the Delesse principle of areal analysis for estimating component volume densities
Authors: Mayhew T. M. , Orive L.‐M. Cruz 
Published: August 2011

SummaryIn stereological work, component volume densities are estimated routinely by invoking the Delesse principle of areal analysis. This is true whether the morpho‐metric methods are based on the measurement of transectional areas, linear intercepts or point densities. Following our earlier consideration of the special case of a spherical component in a spherical containing volume, we here present a warning on the use of this fundamental principle. This report demonstrates that estimates of volume densities may be derived by application of two main formulations which are based on the areal analysis of ‘cubical’ and ‘spherical’ mathematical models. It is emphasized that these formulations of the Delesse relationship are not mathematically equivalent in all practical instances; failure to appreciate the correct practical circumstances in which each should be applied may lead therefore to the introduction of a statistical bias into the volume density data which are obtained. The conditions under which the formulations should be applied are stressed and clarified and some biological examples are provided. Whilst the problems are presented in a form which is aimed primarily at the biologist, they are also pertinent to the earth and materials scientists and to morphometrists in general.
Simple mechanical device for orienting tissue blocks on the ultramicrotome*
Authors: Isler H. 
Published: August 2011

SummaryA simple and inexpensive modification of the specimen holder of the Porter‐Blum model MT‐1 has been devised, which allows fine adjustments of tissue block orientation in both horizontal and vertical planes. It consists of an additional ring mounted on the existing locking ring and fitted with four radial screws which push the shaft of the chuck.
Observations on interphase boundary structure
Authors: Aaronson H. I. 
Published: August 2011

SUMMARYA review is presented of experimental observations reported on the structure of interphase boundaries since 1968. Nearly all observed boundaries are of the partially or fully coherent type, and hence the principal structural features examined were misfit dislocations and ledges. Observations were drawn from studies of precipitation, spinodal decomposition, oriented overgrowths and eutectics. Interphase boundary structures were found to be little affected in the main by the type of reaction through which they were developed and were consistent with Van der Merwe theory and a theory of precipitate morphology. Observations of these structures have been considerably facilitated by the efforts of Weatherly and co‐workers to define the visibility and the optimum TEM viewing conditions of misfit dislocations and ledges. Important new observations on misfit dislocations made since 1968 include: misfit dislocation spacing in the Cr(Mo)/NiAl eutectic in good agreement with theoretical expectation because misfit dislocations are also glide dislocations and the interface plane is also the glide plane; misfit dislocations on θ′ Al‐Cu and η Al‐Au plates with a Burgers vector (a/2<100>) stable only at an interphase boundary; reduction of the interfacial energy of partially coherent boundaries on the same precipitates by dislocation interactions and rearrangements; reduction of interfacial energy of interfaces developed during spinodal decomposition through rotation of the interface itself from {100} to {110}; and misfit dislocation boundaries between f.c.c. (Cu‐rich) and b.c.c. (Cr) crystals made possible with the assistance of ‘structural ledges’. Growth ledges have now been observed in a number of alloy systems which have undergone precipitation from solid solution or eutectic solidification; they appear to be confirmed as a customary feature of migrating partially or fully coherent interphase boundaries. Much new experimental information has been obtained on the sources (exceedingly diverse), heights (usually appreciably higher than monatomic), spacings (irregular) and migration kinetics (diffusion‐controlled if their edges are disordered) of ledges. New observations continue to confirm the complexity of the processes through which misfit dislocations are acquired. The Ashby‐Johnson and the Brown‐Woolhouse theories of misfit dislocation nucleation or acquisition by spherical precipitates are in encouraging agreement with experiment.
Special grain boundaries in random polycrystalline aggregates
Authors: Warrington D. H. 
Published: August 2011

SUMMARYThe observation of different types of order present in grain boundaries is discussed. It is shown that, while the majority of boundaries in a cubic random polycrystalline aggregate may possess order characteristics of a ‘plane matching’ or CAD situation, very few boundaries will possess order characteristic of a CSL. Frequent observations of CSL or CAD order in the electron microscope indicate a non random polycrystalline aggregate.
Apparatus for annealing of electron microscope specimens under controlled atmospheres
Authors: Kritzinger S. , Monaci T. , Ronander E. 
Published: August 2011

SUMMARYA detailed description is given of an annealing system in which transmission electron microscope specimens can be heat‐treated for known effective annealing times at accurately known constant temperatures. The apparatus includes facilities for annealing under corrosive atmospheres (such as chlorine) or vapours (such as bromine) at known pressures, and works in conjunction with an oil bath of which the temperature can be controlled to ±0.01°C. The thermal response of the specimen chamber at different annealing temperatures was determined by cine techniques. Typical results obtained with the system are presented.
Contrast enhancement in biological electron microscopy using two micrographs
Authors: Misell D. L. , Burge R. E. 
Published: August 2011

SUMMARYA method is given for either dark‐ or bright‐field electron microscopy of thin biological specimens (e.g. thin sections) for enhancing the image arising from elastic scattering, relative to the composite image formed by inelastic scattering. The method requires two micrographs of a given field taken at two particular conditions of image defocus.
Scanning electron microscopy of rust haustoria
Authors: Pring R. J. 
Published: August 2011

SUMMARYThe three‐dimensional structure of rust haustoria has been studied by scanning electron microscopy (SEM). Rust infected leaves were fixed and embedded in Spurr's resin as for transmission electron microscopy (TEM). The cut surface of blocks containing embedded material was etched with sodium ethoxide and examined in the SEM.
The effect of intestinal distension and of section thickness on counts of epithelial nuclei in the rat small intestine
Authors: Clarke Rufus M. 
Published: August 2011

SUMMARY

A method is described for counting nuclei in wax‐embedded histological sections of epithelium. The counts are independent of section thickness over a wide range (4–10 μm).
Counts of nuclei were made in villi and crypts of rat small intestine fixed either collapsed or distended by a hydrostatic pressure equivalent to 350 mm of water. There was no significant difference between the counts of nuclei in collapsed or distended gut.
Distension reduced the absolute height of villi, and increased their absolute width at the base.
The implications of these findings for studies of the morphological basis of intestinal adaptation are discussed.
Estimation of section thickness, etc. by quantitative electron microscopy
Authors: Casley‐Smith J. R. , Crocker K. W. J. 
Published: August 2011

SUMMARYMethods have been developed for the estimation of section thickness, and of the mass‐thicknesses, and hence the masses, of material embedded in sections. They are based on the current densities measured with a Faraday‐cage or on a new approximation for the relationship between exposure and optical density (OD) of the electron microscopical plate, which is valid for OD < 5. This relationship is quite distinct from the response to light, and also from an approximation for electrons which was only valid for OD < 1.2, and which was the basis for an earlier method.The old methods and the two groups of new ones were tested, and also compared with the interference microscope. It was found that all but one of the new methods, in both groups, were homogeneous; the older methods and the interference microscope differed very significantly between themselves and with the homogeneous methods. The errors in the interference microscopical estimations were almost certainly due to the presence of embedded material in the sections, which could not be detected with the interference microscope because of its low resolution and the poor contrast in the thin sections. (A second set of experiments using only pure resin gave a good agreement between the homogeneous methods and the interference microscope.)The orders of accuracy of the methods are quite high. A measurement repeated twelve to thirty‐five times will yield a value which has a 95% chance of being within 5% of the true value, while a single observation has a 95% chance of being within ∼ 25% of the true value with most methods, while some place it within ∼ 10%. Simplified, but less accurate, applications of the methods are also suggested.
The precise measurement of the thickness of ultrathin sections by a ‘re‐sectioned’ section technique
Authors: Yang Grace C. H. , Shea Stephen M. 
Published: August 2011

SUMMARYThe thickness of ultrathin tissue sections embedded in Epon‐Araldite and cut with a diamond knife was measured by re‐sectioning and electron microscopic examination of the section profiles. A secondary section mounted on a Formvar‐coated slot grid provided enough normally cut segments (seven to seventeen) for measurements giving a precise estimate of mean thickness, comparable to that obtainable by interference microscopy (±2.3% or less for grey to dark gold sections). The standard deviation of section thickness within sections was never more than 5 nm, corresponding to a coefficient of variation of 6.5% or less for sections more than 48 nm thick. This suggests that variation in section thickness, within sections, may be less than has been supposed, so that quantitative work may be based on thickness measurements made over a limited representative area. A silver interference colour was associated with sections 49–60 nm thick.
The changing pattern of research in wood anatomy
Authors: Brazier J. D. 
Published: August 2011

SUMMARYResearch activity in wood anatomy since 1900 is reviewed with special reference to the pattern of development in (1) descriptive and comparative anatomy, (2) structure in relation to wood properties and (3) the influence of growth on wood structure. In the early decades of the century there was an emphasis on comparative anatomy, often as a contribution to developing the use of the tropical forest resource. At the same time, there was an increasing awareness that an understanding of the behaviour of wood was to be obtained from the study of its physical structure and chemical composition; particular attention has been given to elucidating the structure of the cell wall, at first by conventional optical microscopy and physical techniques and more recently by electron‐ and scanning electron‐microscopy. Studies of the interaction between growth and wood structure have attracted special interest in the post Second World War period and have been prompted by an awareness in many countries for a need to depend increasingly on managed forests as a source of timber and to produce such timbers at minimum cost compatible with acceptable technical performance.Finally, in considering the future of wood anatomy, the view is expressed that if a continuing and more effective use is to be made of wood, then wood anatomy must have a future as it has a fundamental role in developing and applying the technology of wood. Particularly important is its role in contributing to the use of the world's timber resource, especially the many under‐utilized timbers in the developing countries, and the efficient production of plantation timber.
Interference microscopic studies on wood plastic and cell wall—liquid interactions in beech
Authors: Baas P. 
Published: August 2011

SUMMARYA method is described to measure the content of methylmethacrylate‐polymer (poly‐MMA) in wood‐plastic composites and the influence of MMA on water and ethanol accessibility of beech wood fibre walls using interference microscopy. Although the S2‐layer of the fibre wall is capable of containing about 12% volume of plastic, the effect of treatment on ultimate water absorption of the cell wall is negligible. The ultimate absorption of ethanol is, however, completely reduced to zero. Increased dimensional stability of wood‐poly‐MMA composites is probably due to hindrance by the plastic in the lumina of the wood elements. The interference microscopic method is also shown to be suitable for determination of the fibre saturation point of cell wall areas.
Electron microscopy of critical point dried whole cultured cells
Authors: Buckley Ian K. , Porter Keith R. 
Published: August 2011

SUMMARYTo determine the overall fine structure of whole, unsectioned cells, cells from rat embryos were cultured on Formvar, glutaraldehyde/osmium‐fixed, transferred to grids, dehydrated, critical point dried, then examined by transmission electron microscopy at either 80 or 1000 kV. In contrast to air‐dried material, critical point dried cells revealed each component clearly and with excellent contrast. All normal cytoplasmic structures (including coated vesicles, polyribosomes, microtubules and other fine components) were readily identifiable. Extensive structures such as microtubules and the endoplasmic reticulum (which appear fragmented in sections) were well displayed. At 1000 kV the beam readily penetrated even the thick nuclear and perinuclear cell regions and produced exceptionally crisp images. The methods described provide a simplified approach to the study of overall cell fine structure.
Field ion microscopy of biomolecules
Authors: Machlin E. S. , Freilich A. , Agrawal D. C. , Burton J. J. , Briant C. L. 
Published: August 2011

SUMMARYA new type of image, existing only at field strengths below the denaturation field strengths of molecules, has been discovered. This type of image has structure, is not symmetrical and thus differs from previously reported low field strength images. The possibility that macromolecules adsorbed on tip surfaces produce such structured images has been exhaustively investigated. The result is that no observation has been found which disproves this hypothesis and many tests conducted in such attempts yielded correlations consistent with this hypothesis. It is therefore concluded that it is highly probable that biomolecules produce structured images and that it is highly improbable that these correlations represent a chance event. On the other hand, these correlations may be due to some cause unknown to the authors; but we consider this possibility to be unlikely.Some micrographs have been obtained which provide a reasonable basis for the hope that tertiary structure information may be derived from low field strength imaging of partially embedded biomolecules or of biomolecules that are resistant to field denaturation during imaging. Information may presently be obtained from analysis of low field strength ion micrographs about the size and shape of some biomolecules.
The effects of hypobaric atmospheres on living cells in layers of thin media and implications for electron microscopy
Authors: Lyon Norman C. , Kirsh Richard L. , Parsons Donald F. 
Published: August 2011

SUMMARYAt present, the only possibility for improved resolution of intracellular movement appears to be electron microscopy using a hydration chamber (EMC) at reduced gas pressures with thinned medium around the cells. The environmental constraints of examining cells under such conditions were examined in the absence of ionizing radiation by using an EMC‐analogue fitted to a light microscope. White blood cells and baby hamster kidney cells were examined. A 50% survival pressure value, for hypobaric atmospheres, was determined for these cells. Morphological changes of the hypobarically‐exposed cells are described.
A transmission electron microscope study of the effects of ion etching on cells
Authors: Frisch B. , Lewis S. M. , Stuart P. R. , Osborn J. S. 
Published: August 2011

SUMMARYThe effects of ion etching on blood cells have previously been studied by scanning electron microscopy. This present study by transmission electron microscopy was undertaken to evaluate the effects of the etching process on the cells. Critical point dried preparations were made, etched and subsequently processed and embedded in Araldite. Examination of thin sections of erythrocytes revealed disintegration of the plasma membrane; the residual membrane destruction products formed the tips of cones produced by long etching times. The effect of etching varied in erythrocytes in the same preparation. Nucleated cells showed a similar disintegration of the plasma membrane, but membranes of mitochondria, granules, vesicles and vacuoles did not exhibit effects of etching comparable to those of the plasma membranes. After treatment with a number of different fixatives, erythrocytes on carbon‐coated copper grids were also etched and examined directly in a high voltage electron microscope at 1 MV. The effects were comparable to those seen in thin sections. To study the etch rates of biological materials, the resonant frequencies of quartz crystals were measured after application of thin films of albumen and cholesterol and again after these had been etched. The ratio of the frequency changes indicated that the etch rate of albumen was approximately 2.5 times that of cholesterol.The results are discussed in the light of theories of the mechanisms involved in ion etching.
Graphite crystal film preparation by cleavage
Authors: Hines R. L. 
Published: August 2011

SUMMARYGraphite films which are free of adhesive contamination are prepared by glueing a crystal to an adhesive coated grid and then cleaving away the top graphite layers with adhesive tape. The final graphite films in the centres of the grid openings do not come into contact with the adhesive at any time during the preparation process. Graphite crystal films a few tens of nanometres or less in thickness with large areas of uniform thickness are easily produced.
Analysis of droplets from iso‐atomic solutions as a means of calibrating a transmission electron analytical microscope (TEAM)
Authors: Morgan A. J. , Davies T. W. , Erasmus D. A. 
Published: August 2011

SUMMARYThis paper describes a spraying method of producing iso‐atomic droplets (≅3 μm diameter) of uniform size, distribution and chemical composition. These droplets were used to calibrate a TEAM system operated under given conditions, so that the relative sensitivity of the instrumentation for the elements Na, Mg, P, S, (Cl), K, Ca and Co (‘overall sensitivity factors’) could be determined. These factors (15, 40, 83, 90, (43), 104, 109, 100% respectively) were used to convert observed X‐ray intensity ratios from standard droplets to relative amounts of elements with a fair degree of accuracy (error generally less than ± 10%). It was proposed that the sampling and quantification methods could be applied for the absolute quantitative bulk‐analysis of fluids and tissues (after solubilization) with an introduced reference element, e.g. cobalt, and potentially to the study of relative elemental ratios in fluid microvolumes and in biological thin sections.
Thin polymer films as non‐charging surfaces for scanning electron microscopy
Authors: Pease R. W. , Bailey J. F. 
Published: August 2011

SUMMARYFilms of formvar, 1.2–20.0 nm in thickness, collodion and a 60/40 styrene‐vinylpyridine copolymer (precipitated from solution) have been found to provide a noncharging layer on the surface of several types of specimens, including loose, or fibrous specimens. No electron build up was observed in most of the specimens when examined with a scanning beam of up to 30 kv for unlimited periods of time.
The avian erythrocyte: a study of fixation for electron microscopy
Authors: Brown J. N. 
Published: August 2011

SUMMARYThe quality of ultrastructural preservation of the avian erythrocyte achieved using various fixation techniques is evaluated. Different combinations of initial fixatives, buffers and post‐fixation procedures were tested as well as variations in fixative osmolarity, pH and temperature. Of the commonly used initial fixatives (glutaraldehyde, acrolein and formaldehyde), 2% glutaraldehyde, alone in a slightly hypertonic buffer containing divalent ions, produced optimum erythrocyte preservation. The osmolarity was balanced using a non‐electrolyte such as sucrose. The addition of 12% hexylene glycol to the buffer solutions also improves erythrocyte preservation, as evidenced by the increased stability of the marginal microtubules, microfilaments and proteinaceous material.The use of Spurr low‐viscosity epoxy resin enables the cells to be collected using low gravitational centrifugation.