bluuebunny/crossref_metadata_2025_split huggingface dataset:
Observation of grain boundaries
Authors: Goux C. 
Published: August 2011

SUMMARYThe observation of grain boundaries using the optical microscope, the electron microscope and the field‐ion microscope has considerably aided our understanding of grain boundary structure. The study of etch pits in the optical microscope has proved that low angle boundaries are composed of dislocations.A large number of grain boundary observations have been made by transmission electron microscopy. Here, various classes of boundary structural features have been characterized in grain boundaries; they can be classified into three categories: (1) features which are essentially independent of the true structure of the boundary (thickness fringes, moiré fringes); (2) accidental features which result from a perturbation of the boundary by phenomena originating in the adjacent grains (dislocations, ledges); (3) features of the true structure of the grain boundary (features of the equilibrium structure‐features of the perturbed structure). It must be appreciated that certain features of the structure are not resolved because of their poor contrast in the electron microscope image.The field‐ion microscope has been used for a relatively short time in studies of grain boundaries. Nevertheless it has yielded very interesting results. Unfortunately, at the present time, it seems that the positions of the atoms may not be determined sufficiently accurately in this instrument to allow a precise determination of the structure. Only in a limited number of cases has it been possible to account for the observed features on the basis of theoretical considerations.
The theory of two‐phase interfacial structure
Authors: van der Merwe J. H. 
Published: August 2011

SUMMARYThe theory of interfaces between crystals of different structure and/or composition is briefly reviewed. The review is limited to planar semi‐coherent interfaces with an abrupt transition from one crystal to the other. Equilibrium, obeying minimum (free) energy requirements, is introduced as a governing principle. Thus the energy dependence on misfit, strain, atomic bonding, crystal thickness and other parameters is needed for minimization.The following approaches to this problem are dealt with briefly. The coincidence lattice and ball‐and‐wire models, introduced to describe systems with isotropic and covalent bonding respectively, simply correlate low energy with good matching across the interface. The variational approach uses pairwise interface forces and adjusts the positions of atoms adjoining the interface to minimize the energy. The Volterra approach introduces dislocations explicitly for misfit accommodation and to facilitate energy considerations. The Frank‐van der Merwe model recognizes the lattice periodicity by employing an interfacial periodic interaction potential. In this model the resolution of the interface into a sequence of misfit dislocations is a natural consequence of the analysis. It is believed that the latter model has the widest predictive power, while the variational method has greatest potential for accuracy.Possibly the most prominent prediction is the joint accommodation of misfit by overall strain and misfit dislocations. However, the equilibrium theory failed to predict the correct dependence of the contributions of dislocations and strain to misfit accommodation on increasing film thickness. This is now accounted for in terms of the imperfection and difficulty of acquiring misfit dislocations.Some of the consequences of the interface structure of small epitaxial islands are briefly mentioned.
The Denver Universal Microspectroradiometer (DUM)
Authors: David G. B. , Galbraith W. 
Published: August 2011

SUMMARYThis paper discusses the design and describes the construction of an accurate digital microspectrophotometer, microspectrofluorimeter and microrefractometer known as the ‘Denver Universal Microspectroradiometer’ (DUM).The instrument operates in the spectral range of between 428.3 and 1303.4 THz (700–230 nm). Microscopic objects are scanned digitally in two dimensions and absolute digital spectra of various kinds are obtained automatically. Optical path differences can be measured automatically in the same microdomains in which absorbance, fluorescence and bioluminescence are studied. Measurements on solutions in standard cuvettes, and other macroscopic objects, can be made without altering the alignment of the optical components used in microanalysis. The multi‐detector radiometric system is based on the principle of synchronous single photoelectron counting. The operation of the entire system is controlled by an integral computer which is also used for on‐line data‐processing, reduction and analysis. Automatic multiparametric and multicomponent analyses can be carried out with relative ease.The quality of the images obtained is largely diffraction‐limited, and the instrumental uncertainty of measurement is essentially that imposed by the quantum statistics of the radiation captured by the detectors. The linear dynamic range is about 108. The limit of detectability of absorbance is of the order of 0.0001. The system is sensitive enough to measure paucimolecular photoemissive events, such as cellular bioluminescence, yielding about 0.1s−1 photoelectrons (equivalent photocathode current ≃3 times 10−22 A).The absolute accuracy of the system is limited principally by uncertainties inherent in currently available methods of calibrating the spectral response of detectors.
Stabilization and clarification of sections mounted on Formvar‐coated slot grids by deliberate irradiation in the electron beam
Authors: Yang Grace C. H. , Morrison Ashton B. 
Published: August 2011

SUMMARYEpon‐Araldite sections supported on Formvar‐coated slot grids can be stabilized by exposing the area of interest in the column of the electron microscope to irradiation of 0.5 C/cm2. With this procedure one can obtain electron micrographs of high quality, without drift or distortion, from any part of the open slot area. After treatment the support film is not only stable and transparent but robust enough to permit repeated removal and replacement of the specimen in the microscope column. We illustrate the method with a series of electron micrographs with initial magnifications ranging from × 300 to × 500,000 to show the quality of image that can be achieved. The effect of the irradiation on tissue architecture is checked by resectioning the irradiated sections. We recommend this method of local irradiation of sections for investigations using low or intermediate magnifications for the wide field it permits, for the durability it confers on the specimen and for its convenience.
An autoradiographic study of the binding of 3H‐chlorambucil to cells of a drug‐sensitive and drug‐resistant strain of the Yoshida ascites sarcoma
Authors: Birbeck M. S. C. , Robertson D. , Hill B. T. 
Published: August 2011

SUMMARYThe binding of chlorambucil to drug‐sensitive and drug‐resistant Yoshida sarcoma cells has been investigated by an autoradiographic technique. The cells were treated with the drug at various concentrations both in vitro and in vivo. Using both light and electron microscope techniques, and by counting grains on various areas of the cell, the following conclusions were reached.(1) At all drug concentrations there was general cytoplasmic and nuclear uptake by both cell lines. There was no evidence of a specific localization in one site only or for specific exclusion of any one site.(2) At high dose levels (∼2 mM) the binding was approximately equal in both cell lines, although a few damaged cells bound much greater amounts of drug.(3) At low dose levels (∼3 μM) there was a higher uptake by the nucleus of the sensitive cells compared with the nucleus of the resistant cells; the cytoplasmic binding was similar.
High resolution scanning electron microscopy at the subcellular level*
Authors: Lin Shau‐Da , Lamvik M. K. 
Published: August 2011

SUMMARYRecently developed scanning electron microscopes provide sufficient resolution to allow useful observation of subcellular biological objects. Preparation methods for such objects need not be limited to the traditional coating and mounting procedures. Many methods developed for transmission electron microscopy are immediately adaptable to scanning electron microscopy. We show that a number of techniques are available to the microscopist which yield adequate contrast and high resolution. As examples we show skeletal muscle myofibrils dispersed to reveal thick filaments, uncoated on a thin carbon film; a tropomyosin tactoid, negatively stained with uranyl acetate; oncornavirus, conventionally coated; and T4 bacteriophage on an aluminium substrate.
A robust micromanipulator for the scanning electron microscope
Authors: Pawley J. B. , Boyde A. 
Published: August 2011

SUMMARYA simple device for holding and moving mechanical tools in the region of a sample being viewed in the scanning electron microscope is described. The unit has a 20:1 mechanical reduction and when fitted with a tungsten carbide dental chisel, it is sufficiently rigid to cut biological hard tissues. Alternately, when fitted with an electro‐etched tungsten needle, it can be used, in conjunction with specimen stage controls, to remove individual cells from the surface of soft tissues. Examples of these applications are illustrated.
A new universal and variable flash device for visual examination and photomicrography: VISUFLASH
Authors: VAN Maaren P. W. , Hamann D. J. 
Published: August 2011

SUMMARYA recently developed illumination device for microscopes, VISUFLASH, is a universal and variable flash steering device for visual examination, photomicrography and cinematomicrography. The spectral energy distribution of light from the flashtube is suitable for UV‐ visible‐ and IR‐light examination. Furthermore it is, with the aid of the customary filters, possible with this light source to carry out microscopic examinations with transmitted and incident light, and make observations when use is made of dark‐field illumination, phase contrast (+ and ‐), interference contrast, INTERPHACO®, fluorescence contrast and polarized light. Problems in connection with ultra‐short‐time‐effect and the Schwarzschild effect do not occur. In comparison to existing gas discharge light sources VISUFLASH is economical.
A microscope cold stage
Authors: Gallup A. L. , Greenwood B. , Wilson J. F. 
Published: August 2011

SUMMARYThis inexpensive cold stage consists of a perspex box through which cooled nitrogen gas continuously passes. The nitrogen is cooled by being piped, after drying, through liquid nitrogen. Misting is prevented by continuous gas flow, and strategically placed low‐output heating wires.The two foremost problems in the use of a cold stage are to produce adequate and rapid cooling, and to prevent misting of surfaces in the optical pathway if effective cooling is achieved. These problems have been solved in at least one commercial cold stage known to us, but at considerable expense.The stage now described solves both these problems, producing cooling of the specimen down to about — 40°C within a few minutes, and completely obviating misting. It is inexpensive, and can be made without any specialized workshop skills.
Inorganic ion‐doped glass fibres as microspectrofluorimetric standards
Authors: Velapoldi R. A. , Travis J. C. , Cassatt W. A. , Yap W. T. 
Published: August 2011

SUMMARYUranyl and europium ion‐doped fibres of 5–45 μm diameter were prepared which emit in the green and red spectral regions, respectively. Measurements were made of fluorescence flux as a function of fibre length, dopant concentration, slit shape and fibre diameter. The flux was found to be proportional to fibre length and fluorophor concentration and proportional to the square of the fibre radius. In addition, the fluorescence flux as a function of aperture size and shape and fibre position has been measured experimentally and compared to computer generated fluorescence flux envelopes. It is suggested that inorganic ion‐doped fibres are suitable for use as microspectrofluorimetric standards.
A combined freeze chamber and low temperature stage for an electron microscope
Authors: Valdrè U. , Horne R. W. 
Published: August 2011

SUMMARYA low‐temperature freeze‐drying or freezing preparation chamber and specimen stage has been designed and constructed for use with an electron microscope. The system allows biological specimens to be prepared under conditions of temperature and pressure and their subsequent direct transfer to a cold stage maintained at — 175°C within the microscope. Attachment of both the chamber and stage is a simple procedure and does not interfere with the normal electrical and mechanical operation of the microscope.The stage is cooled with the aid of a liquid nitrogen reservoir system and can be maintained at — 175°C for about 80 min without the use of any continuous cooling system. Test specimens have shown that a resolution of about 1.0–1.5 nm can be maintained at — 175°C for 80 min once thermal equilibrium has been established.
An approximate variance for line intersection counts
Authors: Scheaffer Richard L. 
Published: August 2011

SUMMARYLet λ denote a rectifiable line in a plane for which the length per unit area is to be estimated by counting the intersections with random test lines dropped on the plane. The asymptotic distribution and variance of the number of intersections with a single test line is derived for a model which assumes λ to be the boundary of particles or random area. Numerical examples illustrate the applicability of the derived variance expression.
Wood anatomy of Crypteroniaceae sensu lato*
Authors: Vliet G. J. C. M. van 
Published: August 2011

SUMMARYThe wood anatomy of Alzatea from South America, Axinandra, Crypteronia and Dactylocladus from South East Asia, and Rhynchocalyx from South Africa is described in detail. Special attention has been given to the ultrastructure of vestured pits in the five genera. The grouping of these genera into one family as suggested recently is not supported by wood anatomy. Alzatea andRhynchocalyx differ widely from the three other genera and appear to share many characters with both Lythraceae and Melastomataceae; the latter family shows a wide wood anatomical range. The wood anatomical affinities of Axinandra, Crypteronia and Dactylocladus are with Melastomataceae. Comparisons with some other Myrtalean families, notably Oliniaceae and Sonneratiaceae, indicate intimate relationships between Melastomataceae, Lythraceae, Oliniaceae, Sonneratiaceae and Crypteroniaceae s.l. because of overlapping of the wood anatomical range among these families.
Immersion fixation of rapidly frozen, untreated tissues and suspensions of cells including spermatozoa
Authors: Cummins J. M. , Loper M. N. 
Published: August 2011

SUMMARYSmall pieces of tissue, and cell suspensions in plastic artificial insemination (AI) ‘straws’, were frozen rapidly in Freon‐12 at — 155°C, without pre‐treatment. Peripheral fragments were thawed directly in 2% glutaraldehyde at 0°C, and processed for transmission electron microscopy (TEM) studies. Preservation of ultrastructure was satisfactory, and freezing artifacts were minimal.
The ‘through focus plate’: a simple method for obtaining images through focus on a single photographic plate in the electron microscope using a tilting stage
Authors: Rowlatt C. 
Published: August 2011

SUMMARYTilting the specimen in an electron microscope by a relatively small angle can provide a continuous through focal series on a single plate, as the displacement of the object at the edge of the field can be adjusted to be of the same order of magnitude as the alteration of focal point by the fine lens controls. This simple rapid manoeuvre could have applications in the microscopy of uniform preparations, particularly if the specimen is subject to beam damage, and in assessing microscope performance rapidly.
Quantitative evaluation of autoradiographs by X‐ray spectroscopy
Authors: Hodges Gisele M. , Muir Marjorie D. 
Published: August 2011

SUMMARYMeasurements of mass of developed silver in autoradiograms have been made using X‐ray microanalysis. This procedure has been applied to a scanning electron microscopic study of protease‐induced cell stimulation in 3H‐thymidine‐labelled bladder tissues in vitro. Differences in silver concentrations over individual nuclei were demonstrated by X‐ray analysis and quantitative data was obtained showing an increased rate of 3H‐thymidine incorporation in protease‐treated cultures. The initial evidence indicates that X‐ray microanalysis could provide a potentially useful quantitative procedure for autoradiography.
New techniques for the preparation of uniform layers of nuclear emulsions for use in micro‐autoradiography
Authors: Sanderson J. 
Published: August 2011

SUMMARYA procedure is described whereby liquid emulsion can be used to coat glass coverslips to produce films of emulsion suitable for quantitative evaluation of grain density in micro‐autoradiographs.Any thickness of emulsion layer can be produced from 3 μm upwards, depending on the volume and dilution of the emulsion dispensed.The uniformity and reproducibility of the films have been tested by observing light transmission of undeveloped preparations using a microscope photometer.
Microscopic tracing of deuterium
Authors: Kisieleski Walter , Ringo Roy 
Published: August 2011

SUMMARYThe development of the ion microprobe analyser has made it possible to follow stable isotopes with microscopic resolution in biological and other materials. An ion microprobe using an oxygen primary beam has been found to produce relatively few mass 2 ions (+ or ‐) on organic samples. This technique should permit the use of deuterium as a practical tracer with a resolution of about 1μm in the plane of the section and 2 nm in the depth dimension with available instruments.
Removal of glass coverslips from cultures flat embedded in epoxy resins using hydrofluoric acid
Authors: Moore M. J. 
Published: August 2011

SUMMARYA technique is described by which the glass coverslip of a culture, flat embedded in epoxy resins can be removed easily using hydrofluoric acid. Removal by this method leaves the surface of the resin quite smooth and suitable for subsequent thin or ultrathin sectioning for electron microscopy.
Changes of particle frequency in freeze‐etched erythrocyte membranes after fixation
Authors: Parish G. R. 
Published: August 2011

SUMMARYThe frequency of particles on the membrane fracture faces of freeze‐etched human erythrocytes was measured, and the effect of fixation procedures on the particle frequencies was studied. Fresh blood, buffer washed cells and cells fixed in one of the following ways were examined: glutaraldehyde, glutaraldehyde followed by osmium tetroxide, osmium tetroxide alone. Quantitative analyses showed that some treatments produced a significant reduction in the number of particles on the fracture faces as compared with the fresh cells. After both osmium tetroxide fixations, the loss of particles was greater from the outer fracture face (OFF) than the inner fracture face (IFF), whilst after the other treatments approximately the same number of particles were lost from both fracture faces. The results are discussed with respect to some current concepts of the molecular architecture of the erythrocyte membrane and the action of fixatives. The reduction of particle frequencies is thought to be due to both leaching of membrane proteins, and deviations of the usual fracture plane within the membrane. Glutaraldehyde alone was shown to have less effect on particle frequency than the other fixatives and it is therefore a suitable fixative for the preparation of freeze‐etch specimens.
A simple technique for examining frozen hydrated specimens in the scanning electron microscope
Authors: Robinson V. N. E. 
Published: August 2011

SUMMARYThe use of a wide angle backscattered electron detector in a scanning electron microscope, which has the capability of the specimen chamber pressure being controlled independently of the column pressure, provides a simple technique for examining frozen hydrated specimens. Large specimens have been examined within 1 min of being placed on the stub and have been examined for many hours without charging artefacts or distortion due to dehydration.
A container for processing small volumes of cell suspensions for critical point drying
Authors: Newell D. G. , Roath S. 
Published: August 2011

SUMMARYThe attachment of lymphocytes to glass or filters, in order to facilitate handling for processing prior to scanning electron microscopy, may introduce artefacts in surface topography. A container has therefore been adapted, from an embedding capsule, for the preparation of small volumes of cell suspensions.
A technique for obtaining scanning electron micrographs in colour
Authors: Swift J. A. , Brown A. C. 
Published: August 2011

SUMMARYA digital electronic unit is described which, by modifying the video signal of the scanning electron microscope (SEM), permits the selection of images in separate tonal or grey‐scale levels. By the sequential exposure of these grey levels onto colour film with the intervention of colour filters, coloured scanning electron micrographs have been obtained. Full details of the procedure are given. The process is applicable to any normal image capable of being displayed at the scanning electron microscope.
Determination of the principal distance and the location of the perspective centre in low magnification SEM photogrammetry
Authors: Boyde A. 
Published: August 2011

SUMMARYThe principal distance, D, from the centre of perspective in the SEM optical projection to the tilt axis of the specimen stage must be accurately determined before photogrammetric evaluation of stereoscopic pairs of micrographs can proceed. A precise procedure for measuring D is described in which the specimen stage X micrometer is used to measure the width of the field scanned for a particular width of the CRT, when the specimen stage is moved along the electron beam axis by amounts measured with the stage Z micrometer. The Z micrometer is calibrated with an external dial gauge. A plot of field width against Z extrapolated to zero gives the location of the perspective centre.In SEM photogrammetry, it is usual to leave the lens currents unchanged whilst recording the stereo‐pairs. The values of D measured with a constant final lens current show that the perspective centre is located close to the final aperture in its conventional position. Previous determinations of D for Stereoscans have used a changing lens current to keep the specimen in focus at varying Z, and found a virtual centre several millimetres above the final aperture. The value of D so obtained should only be used if the micrographs were recorded with dynamic or automatic focusing systems.
A simple method for exposing plastic embedded structures for scanning electron microscopy
Authors: Jarvis L. R. 
Published: August 2011

SUMMARYSurfaces of structures which may be identified in sections of plastic embedded tissue can be exposed for examination using scanning electron microscopy by removal of the embedding medium from the sectioned block with sodium methoxide. Correlation of the information provided by sections and scanning electron microscopy is therefore possible. This technique has been used in examining the developing peristome teeth of the moss Funaria hygrometrica.