bluuebunny/crossref_metadata_2025_split huggingface dataset:
A new, less toxic polymerization system for the embedding of soft tissues in glycol methacrylate and subsequent preparing of serial sections
Authors: Gerrits P. O. , Smid L. 
Published: August 2011

SUMMARYThe paper describes a new polymerization system for embedding soft tissues in glycol methacrylate (GMA). The polymerization of GMA is initiated by means of a barbituric acid derivative in combination with chloride ions and dibenzoyl peroxide. The catalyst system contains no aromatic amines which constitutes a toxicological advantage over the commonly employed system of peroxide/aromatic amine. Clear blocks are obtained from which 1–2 μm sections are easy to cut. In combination with an appropriate softener, polyethylene glycol 400, serial sectioning may be practised.
Microtopographical analysis of surface structures in a scanning electron microscope
Authors: Knoesen D. , Kritzinger S. 
Published: August 2011

SUMMARYA stereographic‐based method, utilizing both tilt and rotation, is demonstrated, whereby the underlying crystallography of three‐dimensional planes and directions on fine grained and highly deformed metallic specimens can be determined in a scanning electron microscope (SEM). It requires the recording of two micrographs of the same area (or three‐dimensional object) at different orientations, obtained by tilting and rotating the specimen holder. By measuring the projected lengths and angles of lines with respect to the tilt axis on both micrographs, the interangles between directions can be found, and eventually the crystallographic planes and directions can be identified.
Simple procedure for the production of carbon‐polymer support grids for use in X‐ray microanalysis
Authors: Smits H. T. J. , Linders P. W. J. , Stols A. L. H. , Stadhouders A. M. 
Published: August 2011

SUMMARYA simple and rapid procedure for the production of low‐cost carbon‐polymer support grids is described. These grids are particularly useful for X‐ray microanalysis of thin specimens because of their low X‐ray background properties. The grids can be prepared for immediate use, which guarantees constant quality.
Precise and reproducible deposition of thin and ultrathin carbon films by flash evaporation of carbon yarn in high vacuum
Authors: Peters Klaus‐Rüdiger 
Published: August 2011

SUMMARYA simple, small device and its use for reproducible flash evaporation of carbon yarn in high vacuum are characterized. Using this flash evaporator, carbon films of any thickness up to 20 nm can be deposited without spark generation under minimized photon radiation, and with an accuracy better than ±0·2 nm. The films have less background structure (imaged in phase contrast) than conventionally rod evaporated films and are therefore suitable for many kinds of thin and ultrathin carbon film applications in electron microscopy, e.g. as backing for formvar films or sections, as isolating carbon layers for autoradiography, as ultrathin films (floated from mica) for support of macromolecules to be metal shadowed and as support and cover for negative staining of various specimens by the sandwich technique.
Differential phase contrast in scanning optical microscopy
Authors: Hamilton D. K. , Sheppard C. J. R. 
Published: August 2011

SUMMARYHigh‐quality high‐resolution transmission and reflection images produced using a scanning optical microscope and the split‐detector technique are presented. These images exhibit differential phase contrast, the method avoiding some drawbacks of the usual Nomarski DIC arrangement. Imaging is treated theoretically and compared with the Nomarski method.
An empirical formulation relating boundary lengths to resolution in specimens showing ‘non‐ideally fractal’ dimensions
Authors: Rigaut J. P. 
Published: August 2011

SUMMARYThe concept of fractal dimension offers an elegant basis for the understanding of changes in boundary lengths due to different resolutions. However, in many cases, the usual log‐log ‘fractal plot’ does not quite fit the observed data, with most biological structures for instance.An automated boundary following algorithm has been used with an IBAS image analyser on various objects, to evaluate boundary lengths at different magnifications and with a wide range of discrete divider stride lengths on each digitized image. A formula which relates the boundary length to the divider stride length and fits very closely the experimental data has been empirically obtained.Examples are shown with various object boundaries observed by TV‐camera, macroscopically or with a light microscope. At different magnifications, the same constants are obtained for a given object, notably a theoretical maximum boundary length (Bm) when the divider stride tends towards zero. The formula allows to calculate a variation of the log‐log plot slope which fits very closely the upper convex plots observed when the boundaries do not display an ideally fractal behaviour. Plots derived from the Lineweaver‐Burk and Hill ones (used in enzymology) allow a relatively easy graphic determination of the parameters of the proposed formula, which may offer useful criteria for object shape classification, as demonstrated by a biological example.Instead of a true (constant) fractal dimension, it seems that, in many situations, exists a ‘continuous fractal dimensional transition’, inside which an apparently linear segment in a given range of resolution of the usual log‐log plot could be explained by asymptotic limits at higher and lower resolutions. The ideal situation with a constant fractal dimension over all resolution ranges could be considered as a limit, achieved when the maximum boundary length (Bm) tends towards infinity.
Stereoscopic representation of complex overlapping elemental maps in electron spectroscopic images
Authors: Arsenault A. L. , Ottensmeyer F. P. 
Published: August 2011

SUMMARYA stereoscopic method is described enabling the direct visualization of the spatial relationships of elemental maps generated by electron spectroscopic imaging. The cartilage growth plate in early stages of mineralization was used to illustrate elemental maps of calcium, phosphorus, and sulphur. Stereopsis is achieved by creating a stereo‐pair which in one image of the pair the elemental maps are superpositioned as they occur naturally while in the second image the maps are laterally shifted. In a stereo perspective the maps appear superpositioned in distinct planes.
Improved staining of microfilament bundles in plant cells for high voltage electron microscopy
Authors: Pesacreta T. C. , Parthasarathy M. V. 
Published: August 2011

SUMMARYA post‐polymerization en bloc staining method for high voltage electron microscopy is described. Embedded specimens were initially trimmed to an area close to the point of interest. Trimmed blocks were stained in 5% uranyl acetate/75% ethanol solutions for 36 h at 333 K. This procedure allowed specimens to be stained without the necessity of exposing Formvar films to damaging solutions. After such staining, both the contrast and fine detail of structures such as microfilament bundles were superior to that seen in material stained with aqueous solutions of uranyl salts.
Sputtered platinum films on colloidal gold particles: a calibration specimen for quartz film thickness monitors
Authors: Johansen B. V. , Namork Ellen 
Published: August 2011

SUMMARYA method for calibrating quartz crystal thickness monitors is described, which makes use of 20 nm platinum sputtered colloidal gold particles. The actual thickness is measured on transmission electron micrographs of gold particles protruding from the edge of fractured, rolled up, carbon films. In the range up to ∼10 nm, the measured thickness for platinum films is ∼17% larger than the figures calculated from mass thickness equations.
Electron microscopy of melamine‐embedded frog retina: evidence for the overall crystalline organization of photoreceptor outer segments
Authors: Bachhuber Karlheinz , Frösch Dieter 
Published: August 2011

SUMMARYMelamine‐formaldehyde, a widely used technical aminoplast, was recently introduced as a water‐soluble embedding‐medium for electron microscopy (Bachhuber & Frösch, 1983).When processed, using this new technique, the membranes and associated cytoplasmic structures of rod and cone discs show a high degree of structural organization. The membranes are symmetrical and composed of arrays of a 2–2·5 nm particle with a very regular spacing of 3 nm. A network of delicate filaments of less than 2 nm is superimposed on to this framework of membranes, running perpendicularly between the discs and across the disc membranes.The outer segment as a whole shows a crystal‐like organization.
Epifluorescence microscopy with a pulsed nitrogen tunable dye laser source
Authors: van Geel F. , Smith B. W. , Nicolaissen B. , Winefordner J. D. 
Published: August 2011

SUMMARYThis paper describes an epifluorescence system that uses a pulsed laser source as an excitation source for quantitative fluorescence measurements. A 1 μm diameter portion of the sample can be illuminated with high intensity, short light pulses and the fluorescence can be measured with a fast detection system. Selective excitation is possible at 337 nm and from 357 to 710 nm by using different dyes in the laser system.The spectral bandwidth is 0·1–3 nm. Several advantages over the commonly used systems with continuum spectral sources are indicated, especially when measured intensities are low, as in the case of intrinsic fluorescence of the sample, and where reflection of unwanted excitation light may cause appreciable errors when using conventional light sources.
A combined light and electron microscopic method for the visualization of the same in vitro neuron by radioautography and serial sections
Authors: Vuillet J. , Montety M.‐C. Daguet‐de , Autillo‐Touati A. , Glowinski J. , Prochiantz A. , Seïte R. 
Published: August 2011

SUMMARYWe report here on a technical improvement which makes it possible to study, at the ultrastructural level, a dopaminergic neuron which has been previously identified by light microscopy. Primary cultures of virtually pure mesencephalic neurons from mouse embryos were obtained. These cultures were kept for 6 days, then incubated with tritiated dopamine. fixed and embedded in Epon. The dopaminergic neurons were firstly visualized by radioautography directly through Epon blocks in toto by light microscopy. In a second step, ultrathin sections of the identified dopaminergic cells were prepared and the neurons observed at the electron microscopy level. The dopaminergic nature of these neurons was regularly checked by radioautographic control on some selected ultrathin sections.
An anti‐roll plate system for Ralph knives
Authors: Richards Peter R. 
Published: August 2011

SUMMARYAt thicknesses above 4 μm, an anti‐roll plate is necessary when cutting frozen sections for light microscopy with long‐edged glass (Ralph) knives. The structure of the plate and a system which allows the use of such plates without dismantling or interfering with present systems for steel knives is described.
A computerized microspectrophotometer using fibre optics for transmission and detection of light
Authors: Neely John E. , Townend William J. , Combs John W. 
Published: August 2011

SUMMARYA computerized microspectrophotometer was developed to provide rapid and accurate sequential measurements on cells, including nuclear DNA content, by fluorescence staining, photometric grain counting from autoradiographs, and nuclear size estimated by measurement aperture area. To alleviate bulk and vibrations caused by additional stepper motors, the excitation light and filters as well as the emission filters and photomultipliers were detached from the main microscope frame. The light was directed to and from the microscope through fibre optic bundles. This configuration provided an excellent light gathering faculty and made optical alignment easier. The machine provided highly accurate sequential measurements on a relatively large number of cells by static photometry.
Chromoxane cyanine R. I. Physical and chemical properties of the dye and of some of its iron complexes
Authors: Kiernan J. A. 
Published: August 2011

SUMMARYChromoxane cyanine R (Colour Index No. 43820, Mordant blue 3; also known as eriochrome cyanine R and solochrome cyanine R) is a valuable biological stain. The dyestuff is supplied as a powder containing a little less than 50% by weight of the monosodium salt of the dye, mixed with colourless crystalline and amorphous fillers. The tetrabasic colour acid was prepared and purified for study of the chemical and spectral properties of the dye. Chromoxane cyanine R is an acid‐base indicator, with five different colours corresponding to the colour acid and the four anions. The most conspicuous colour change, from yellow to blue, occurs with ionization of the phenolic hydroxyl group at pH 11–12. The dye is assayed by measuring the absorbance of a strongly alkaline solution at 585 nm, with reference to a standard solution prepared from the purified colour acid.Spectrophotometric evidence has been found for the existence of three dye‐metal complexes in solutions of the dye containing added ferric chloride at pH 1·5 (the pH of iron‐dye solutions most useful in histological staining). These have the postulated compositions [Fe2H(dye)]‐(red), [FeH2(dye)]‐ (red), and [Fe2(dye)]2‐ (blue). The first two are probably simple carboxylate complexes of low stability. Increase in pH or molar iron:dye ratio promotes formation of the more stable blue complex, which is a metal chelate. Other blue complexes have been described by other investigators in solutions less acid than those that are useful in microtechnique. The production of blue and various shades of red in tissues stained by solutions containing iron(III) and chromoxane cyanine R probably involves reactions of both the red and the blue complexes of the dye.
Chromoxane cyanine R. II. Staining of animal tissues by the dye and its iron complexes
Authors: Kiernan J. A. 
Published: August 2011

SUMMARYThe staining properties of chromoxane cyanine R (Colour Index No. 43820, Mordant blue 3; also known as eriochrome cyanine R and solochrome cyanine R) have been studied. Used alone, the dye imparted its red colour to nuclei, cytoplasm and collagen. The dye was extracted by mild alkali but not by acids. Stainability required ionized amino groups in the tissue, and there was also evidence for non‐ionic binding of the dye.The colours obtained by staining with mixtures of chromoxane cyanine R and ferric chloride varied with the molar iron: dye ratio and with the pH. Useful staining was seen only between pH 1 and 2. The tissues were coloured either all blue (when Fe: dye was high), or both red and blue (when Fe: dye was low). Lower pH favoured the deposition of red, higher pH the deposition of blue colour. The red was mainly in cytoplasm, blue in nuclei and myelin. Collagen fibres were red or purple, depending on pH and iron: dye ratio. Red colours were differentiated by acid and changed to blue, but not extracted, by mild alkali. The red substance in the stained sections was clearly not the free dye, so it was probably an iron‐dye complex. From the effects of various differentiating agents, it was deduced that the red and blue dye‐metal complex molecules were bound to the tissue by the dye moiety, not by interposition of iron atoms. Staining by the complexes of iron(III) with chromoxane cyanine R did not involve nucleic acids or other polyanions or the amino groups of proteins. There was evidence for only non‐ionic binding of both red and blue complexes. It is suggested that the red colour in sections stained by solutions with low iron: dye ratio is due to a simple carboxylate complex, [Fe2H(dye)]−. The blue colour would then result from withdrawal of a proton from the red complex to give [Fe2(dye)]2‐. The bases that remove the protons may be arginine‐rich nucleoproteins of nuclei and phospholipid bases of myelin.Techniques are described for informative simultaneous staining in two colours, and for the selective staining of either nuclei or myelin.
Incident light microscopy of surfaces of plastic embedded hard tissues
Authors: Bab I. , Ashton B. A. , Owen M. E. , Boyde A. 
Published: August 2011

SUMMARYTo eliminate sectioning artefacts, we devised a method for the preparation of surfaces of plastic embedded hard tissues and their examination by incident light fluorescence microscopy. Flat surfaces produced by cutting on a microtome or using a low‐speed saw were stained with dyes in aqueous solutions. Best results were obtained in tissues embedded in glycol‐methacrylate. This polymer allowed good penetration of the dyes and its optical properties render cutting defects invisible with the present method. The relationship between hard and soft tissues was well preserved and the integrity of the mineralized component maintained. Cellular details and the distinction between osteoid and bone could be clearly demonstrated. The procedure is simple, rapid and produces good results even in instances when histological sectioning is unsatisfactory.
A parametric partial cross section for ELS
Authors: Joy David C. 
Published: August 2011

SUMMARYA parametric expression has been developed which permits the rapid calculation of partial ionization cross sections, for most of the elements and experimental conditions encountered in electron energy loss spectroscopy, without the need for a computer. Since the results are in good agreement with those obtained using the full hydrogenic model, this approximation should be useful for such requirements as rapid microanalysis, or in calculations such as those of detection sensitivity where an analytical approximation to the cross section is needed.
A device for area measurement by TV
Authors: Millington P. F. , Floyd S. 
Published: August 2011

SUMMARYThis paper describes a low‐cost area measurement device constructed from readily available components to provide a direct numerical output related to area. It can be used simply as an area measurement system calibration or, if linked to other devices, can be adapted to act as a source of data in more elaborate experiments. One example of its use is given.
Extraction of substances during glutaraldehyde fixation of plant cells
Authors: Coetzee J. , van der Merwe C. F. 
Published: August 2011

SUMMARYExtraction of Ca, Mg, reducing sugars, amino acids and protein was monitored during fixation of bean leaves. Fixatives included 0.5–5% glutaraldehyde in water at pH 3.4 and at pH 7.2 and phosphate, citrate, Na‐cacodylate, tris, glycyleglycine, collidine and four ‘Good’ buffers, all with 2.5% glutaraldehyde. Least extraction was found in phosphate buffered glutaraldehyde. The optimal glutaraldehyde concentration is 2–3%. This causes least extraction of substances.
Quantitative X‐ray microanalysis of uranium alloys with the analytical electron microscope
Authors: Romig A. D. 
Published: August 2011

SUMMARYX‐ray microanalysis in the analytical electron microscope (AEM) is a powerful tool for studying elemental segregation on a submicrometre scale. This technique has been applied to uranium and its alloys. Materials such as uranium are strong electron scatterers due to their high density and high atomic numbers. Hence, when performing AEM X‐ray microanalysis on such materials special attention must be given to effects such as electron scattering and X‐ray absorption. The objective of this paper is to describe the techniques which are required to perform quantitative X‐ray microanalysis in these heavy metal alloys (U‐Nb, U‐Mo and U‐Ti). Cliff‐Lorimer k‐factors determined experimentally and theoretically are in good agreement. Electron scattering has been studied experimentally and the results are compared to those obtained by Monte Carlo calculations and the single scattering model. X‐ray spatial resolutions of better than 100 nm are attainable. With the proper selection of characteristic X‐ray lines, X‐ray absorption can be avoided in most cases to the limit of electron transparency, ∼ 100 nm.
Gallium: a new supporting medium for specimen preparation
Authors: Warner Ronald R. 
Published: August 2011

SUMMARYGallium offers a useful alternative to conventional plastic and paraffin embedding media. Samples can be inserted into or removed from gallium cleanly and intact in minutes. Gallium can be polished, has good sectioning properties, is electrically conductive, tolerates high beam currents, is usually not a detectable sample component, and probably would not be a solvent for sample constituents. Samples can be immobilized in gallium within a few degrees of room temperature. Gallium has low toxicity, can be obtained in ultrapure form, is not expensive, and is reusable. Gallium has been used to prepare thin and thick sections and to expose bulk sample cross sections for STEM, SEM, microprobe and light microscope analysis. Gallium does not infiltrate; consequently it is not likely to be useful for soft biological samples.
Understanding thin film X‐ray spectra
Authors: Chapman J. N. , Nicholson W. A. P. , Crozier P. A. 
Published: August 2011

SUMMARYFormulae suitable for predicting X‐ray production cross‐sections in thin foils are described. A modified Bethe‐Heitler equation seems well suited to describe the production of bremsstrahlung photons and, for fixed experimental conditions, may be expressed in a simple parametric form. Simple equations for calculating characteristic photon production are less satisfactory and the predictions of different formulae differ markedly. For microanalytical purposes, however, where relative rather than absolute cross‐sections are required, the differences become less pronounced. Finally, some uses for the cross‐sections in X‐ray microanalysis are considered.
Electron energy loss spectra and reflection images from surfaces
Authors: Howie A. , Milne R. H. 
Published: August 2011

SUMMARYThere is renewed interest in the interaction of high energy electron beams with surfaces at glancing angles of incidence, due partially to recent improvements in, and consequential resurgence of, reflection electron microscopy. In this paper electron energy loss of beams running parallel to a surface or at glancing incidence to it are studied and compared with predictions arising from the classical theory of dielectric excitation by a moving charge. There is good agreement for both the Cu and MgO surfaces studied here. It is pointed out that small angle energy loss from high energy electrons is insensitive to surface reconstructions or surface steps. Reflection energy filtered micrographs of the Cu surface are shown and the similarity between the zero and various energy loss images shows the preservation of contrast mechanisms for elastic and inelastic electrons.
The role of carbamino compounds in histological staining
Authors: Cook D. J. 
Published: August 2011

SUMMARYThe effects of high CO2 concentration on tissue staining with buffered eosin, methylene blue and azure A were investigated to determine if carbamino compound formation could alter dye binding. Only in the case of eosin staining were the differences in results with high and low CO2 concentrations compatible with the formation of carbamino compounds. The differences observed with basic dyes were statistically significant but could not be accounted for by carbamino compound formation.
Impregnation of biological material by ZnI2‐OsO4, KI‐OsO4 and NaI‐OsO4 mixtures for electron microscopic observations: Chemical interpretation of the reaction
Authors: Carrapiço F. , Madalena‐Costa F. , Pais Maria Salomé S. 
Published: August 2011

SUMMARYAlkaline iodide‐osmium tetroxide mixtures were used in an electron microscopic study of plant cells and gave better results in the preservation of the cell structure in contrast to the cell structure observed when ZnI2‐OSO4 mixtures are used.The electron density observed in the reactive sites of the cell by OsO4‐iodide mixtures is controlled by the presence and oxidation state of iodine that acts as a regulator of the potential redox of the reaction of OsO4 with the biological material.