bluuebunny/crossref_metadata_2025_split huggingface dataset:
Quantitative microlocalization of diffusible ions in normal and galactose cataractous rat lens by secondary ion mass spectrometry
Authors: Burns Margaret S. , File David M. 
Published: August 2011

SUMMARYSecondary ion mass spectrometry (SIMS) is a surface analytical technique with high sensitivity for elemental detection and microlocalization capabilities within the micrometre range. Quantitative analysis of epoxy resins and gelatin have been reported (Burns‐Bellhorn & File, 1979).
The application of a microwave technique for the preparation of cell blocks from sputum
Authors: Kok L. P. , Boon M. E. , Ouwerkerk‐Noordam E. , Gerrits P. O. 
Published: August 2011

SUMMARYMicrowaves stimulate diffusion in tissue and affect the proteins and membrane of the cell. These actions can be used to shorten the time required to fix and prepare cell blocks from sputum. The fixative containing ethyl alcohol and polyethylene glycol is particularly suitable for microwave enhanced fixation. Applying a commercially available domestic microwave oven, in which the temperature and power level can be set, cell blocks can be prepared from fresh sputum in 35 min. The microscopical results are of a superior quality because of the microwave‐induced homogeneous distribution of the effects of the applied immersion fluids on the cells. The method is very successful for all specimens containing a large amount of mucous. Health hazards for laboratory personnel are nil in this cell blocking method; in contrast to when fresh sputum containing infectious agents is used for smear preparation.
The use of malachite green during fixation of plant tissues for the preservation of lipids
Authors: Lawton June R. 
Published: August 2011

SUMMARYOsmiophilic droplets are shown in chloroplasts of leaves of ryegrass after the addition of malachite green to glutaraldehyde during primary fixation. Similar droplets are shown in leaves of bean and maize but not in the roots of these plants. These droplets are not shown in tissue fixed in glutaraldehyde in the absence of malachite green. Evidence is presented which indicates that these droplets contain a high proportion of lipids, particularly phospholipids. This evidence includes the use of other fixation methods which retain lipids, e.g. formal calcium, potassium dichromate. The droplets give a positive reaction with the silver hydroxylamine reaction for ester linkages. Tests for aldehydes by treatment with thiocarbohydrazide and silver proteinate, and proteins by digestion with protease were ambiguous. Digestion with solvents before fixation indicate that the droplets are lipids. TLC of chloroform: methanol extracts of fresh and fixed tissue and of the fixative solvents support the idea that malachite green aids retention of lipids during fixation. Phospholipids are also demonstrated by silver hydroxylamine in plant cell nuclei, myelin of rat brain and vesicles in bean root tips.
Selective contrast‐enhancement of the cochlear duct glycocalyx after OsO4/K4Ru(CN)6 post‐fixation
Authors: Groot J. C. M. J. de 
Published: August 2011

SUMMARYFixation‐dependent selective contrast‐enhancement of the cochlear duct (or endolymphatic) glycocalyx was observed in the guinea pig inner ear after post‐fixation with osmium tetroxide‐potassium rutheniumcyanide. Contrast of the perilymphatic glycocalyx, however, was not significantly enhanced. The possible factors underlying this phenomenon are discussed.
Beam induced mass loss in high resolution biological microanalysis
Authors: Cantino M. E. , Wilkinson L. E. , Goddard M. K. , Johnson D. E. 
Published: August 2011

SUMMARYElectron beam induced loss of mass from the organic matrix and from higher Z constituents of biological samples was measured by monitoring bremsstrahlung and peak changes in EDS spectra. When any effects of contamination, extraneous X‐rays, beam current drift, specimen drift, and specimen shrinkage were monitored and corrected for, the three types of samples gave consistent and similar results at 296 K. Bremsstrahlung losses averaged 45%, 46% and 50% respectively for muscle homogenate, salivary gland sections and albumin. Sulphur losses average 74%, 72% and 86% for the same three sample types. No other elements suffered significant losses. Dl/e for bremsstrahlung averaged 0·14 C/cm2. Bremsstrahlung loss at 93 K began approximately one order of magnitude higher in dose, and the extent of loss varied. Sulphur losses, however, were greatly reduced at low temperatures.
Diffraction pattern indexing in lithium niobate
Authors: Twigg M. E. , Nakahara S. , Maher D. M. , Sheng T. T. , Homes R. J. 
Published: August 2011

SUMMARYCrucial to the interpretation of diffraction contrast experiments conducted in the transmission electron microscope is the self consistent indexing of zone‐axis patterns for the crystal under study. Because indexing the diffraction patterns of a crystal as complicated as lithium niobate is not a trivial exercise, computer simulation of diffraction patterns, extinction distance calculations, and consideration of several unit cell representations are used in order to make diffraction pattern interpretation more tractable. It was found that the zone‐axes were most easily indexed by considering the pseudo‐cubic representation of rhombohedral perovskite crystals. The pseudo‐cubic system also facilitates the indexing of Bragg reflections and the visualization of the major features of the reciprocal lattice. Ultimately, however, hexagonal indices must be used to understand a particular lattice defect, since the symmetries associated with the hexagonal lattice are real symmetries, unlike the apparent symmetries that are implied by a pseudo‐cubic crystal. For this reason, we have tabulated the matrices for transforming from the hexagonal system to the pseudo cubic system. For the sake of completeness, transformation matrices relating all four relevant lattice systems (hexagonal, pseudo‐cubic, primitive rhombohedral, and orthohexagonal), as well as the atomic positions in each system, are tabulated.
Particles and pits matched in native membranes
Authors: Ting‐Beall H. P. , Burgess Florence M. , Robertson J. David 
Published: August 2011

SUMMARYWe have obtained high resolution electron microscopic images of complementary membrane surface replicas of purified microsomal vesicles from pig kidney outer medulla containing Na+, K+‐ATPase. Ultra‐rapid freezing of a membrane suspension was followed by fracturing and replicating of the liquid helium cooled specimen under ultra‐high vacuum conditions free of hydrocarbon contaminants. The protoplasmic fracture faces are populated with intra‐membrane particles while the external fracture faces reveal complementary pits. This is the first demonstration of extended precise matching of individual intramembrane particles and their corresponding pits in biological membranes containing transmembrane proteins. The data are also consistent with the theory that the majority of Na+, K+‐ATPase mass is located at the protoplasmic half of the membrane.
Environmental scanning electron microscopy in colour
Authors: Danilatos G. D. 
Published: August 2011

SUMMARYThe environmental SEM has been developed to a stage where colour can be introduced during imaging. A new approach to production of colour micrographs is demonstrated together with some typical uses of the environmental mode of SEM. A combination of the outputs of two backscattered electron (BSE) detectors alone or in combination with the outputs from a gaseous detector device can form images corresponding to particular aspects of a given specimen. Two or more of these images can be superimposed on to the same colour print to produce a colour micrograph.
Characterization of dimensions of ellipsoidal microparticles via electron microscopy
Authors: Keville K. M. , Caruthers J. M. , Franses E. I. 
Published: August 2011

SUMMARYThe analysis and the use of metallic shadow casting and specimen tilting for accurately determining the dimensions of microellipsoids by electron microscopy (EM) are presented. The procedure uses the direct image and two different shadows or two different specimen tilts to unambiguously determine the dimensions of an ellipsoid. A novel computer‐aided matching procedure is used to determine dimensions and orientations. The analysis was applied to a sample of polymer prolate microspheroids, which have recently been synthesized in our laboratory. The shape of the particles was confirmed and their dimensions and orientations were determined. The particles were shown to have a length (twice the principal axis) of 3.30±0.02 μm and a diameter (twice the minor axis) of 1.66±0.04 μm. Thus, both EM techniques were demonstrated to be practical and precise for determining dimensions of individual microellipsoids.
Reconstitution of molecule images analysed by correspondence analysis: A tool for structural interpretation
Authors: Bretaudiere Jean‐Pierre , Frank Joachim 
Published: August 2011

SUMMARYCorrespondence analysis is gaining increasing importance in the analysis of electron micrographs of macromolecules. Partial or complete reconstitution of images from their factorial representations is introduced as a useful tool in interpreting variational patterns and tracing their physical origin. The value of image reconstitution is demonstrated with two examples, one using a set of model images and the other a set of images of a haemocyanin molecule assembly product.
Imaging intracellular elemental distribution and ion fluxes in cultured cells using ion microscopy: a freeze‐fracture methodology
Authors: Chandra Subhash , Morrison George H. , Wolcott Christine C. 
Published: August 2011

SUMMARYA freeze‐fracture methodology was standardized for tissue culture cells to study intracellular distribution of diffusible elements with ion microscopy. Chinese hamster ovary (CHO) and normal rat kidney (NRK) cells grown on a silicon substrate were sandwiched using another smooth surface (silicon, glass, mica) in the presence of spacers and fast frozen in liquid nitrogen slush. The sandwich was fractured by prying the two halves apart under liquid nitrogen. This procedure produced large areas on the silicon substrate containing hundreds of cells grouped together and fractured at the apical cell surface. After freeze‐drying, these cells revealed a subcellular distribution of Na, K, Ca, Mg, P, Cl and S with the ∼0·5 μm lateral resolution of the ion microscope. Between the nuclei and the cytoplasm of cells, no major differences were observed for Na, K, Mg, P, Cl and S intensities. Calcium alone, however, exhibited a remarkable distribution. Calcium accumulated more in the cytoplasm than in the nuclei of cells. Even within the cytoplasm its distribution was heterogeneous, suggesting Ca binding sites. The fractured cells consistently exhibited high K‐low Na intensities. The injured or dead cells were easily recognized among the healthy ones due to their abnormal ion composition. This simple freeze‐fracture methodology allowed fracturing of cells without removing the cells from the substrate. In addition, it eliminated the need for washing the nutrient media away and cryo‐sectioning before ion microanalysis. The methodology was successfully extended to 3T3 mouse fibroblast, PtK2 rat kangaroo and L5 rat myoblast cultures.
Astronomical hypersensitization techniques applied to photomicrography: Kodak Technical Pan Film 2415
Authors: Smith Alex G. 
Published: August 2011

SUMMARYKodak Technical Pan Film 2415 is a valuable recording medium because of its unusually fine grain and high resolution. Hypersensitization techniques developed by astronomers can increase its normally low speed several‐fold in the range of exposures commonly employed in microscopy. The speed gains are even larger for very long exposures such as those encountered in fluorescence work. Troublesome effects from reciprocity failure are virtually eliminated. When active development is added to hypersensitization, well‐exposed negatives can be obtained at ISO indexes as high as 1600. As in astronomy, the same general techniques can be applied to a wide variety of emulsions.
In situ oxidation and reduction of the oxides of cerium, praseodymium and terbium by high‐voltage electron microscopy
Authors: Schweda E. , Kang Z. C. , Eyring L. 
Published: August 2011

SUMMARYIn situ oxidation and reduction of the oxides of cerium, praseodymium and terbium in a controlled atmosphere and temperature have been studied utilizing a high‐voltage electron microscope. Experiments were carried out in the environmental cell of the Berkeley KRATOS EM 1500 HVEM at temperatures between 298 K and 1023 K in an atmosphere of oxygen, hydrogen or vacuum. Electron diffraction patterns revealed the course of small fragments of the crystalline oxides. In nearly all cases, the degree of reduction recorded was greater than expected from equilibrium tensimetric studies in the absence of an electron beam. Furthermore, reoxidation appeared to be more sluggish and to a lesser extent than is observed in specimens outside the microscope.
The relative efficiency of cryogens used for plunge‐cooling biological specimens
Authors: Ryan K. P. , Purse D. H. , Robinson S. G. , Wood J. W. 
Published: August 2011

SUMMARYCoolants used for freezing biological specimens were tested for cooling performance in the continuous plunge mode. Results from bare thermocouples showed that ethane cooled faster than propane or a propane: pentane mixture, even when warmed to 25 K above its freezing point. Propane coolants were more efficient than Freon 22 and the slowest cooling occurred in boiling liquid nitrogen. Hydrated gelatin specimens showed similar results with ethane cooling about 33% faster than propane. Epoxy resin specimens cooled faster than hydrated gelatin specimens of similar size. Hydrated and resin specimens cooled over increasing distances as plunge velocity increased. A bare thermocouple, however, cooled over a constant distance when plunged above a critical velocity. This phenomenon may reflect vapour formation and its suppression at high plunge velocities. The rate of cooling in hydrated specimens is shown to have an absolute limit and cannot be modelled by bare thermocouples or resin specimens.
A simple, practical ‘swiss roll’ method of preparing tissues for paraffin or methacrylate embedding
Authors: Park Carol M. , Reid Philip E. , Walker David C. , MacPherson Brian R. 
Published: August 2011

SUMMARYA simple method of preparing ‘swiss rolls' from strips of tissue up to 500 mm in length is described. This procedure has been applied to a variety of tissues and is suitable for the preparation of both paraffin‐ and methacrylate‐embedded specimens.
The comparison of transition metal concentration ratios determined by EELS and EDX
Authors: Crozier P. A. , Chapman J. N. , Craven A. J. , Titchmarsh J. M. 
Published: August 2011

SUMMARYThe correlation that exists between elemental concentration ratios determined using EDX and EELS is examined. EELS and EDX were recorded simultaneously from the second phase carbides of a ferritic steel and the Cr/Fe and Mn/Fe concentration ratios were determined from each spectrum. For this system, it was found that the Cr/Fe ratios could be determined by EDX to within an accuracy of 4% and these were then used to provide a check on the EELS analysis procedures. The effects of using different partial ionization cross‐section models and methods of applying these models were examined. It was found that an overall agreement of 3% between EDX and EELS was obtained in this particular experiment. Much poorer agreement was found to exist between the two techniques for the Mn/Fe ratios. The discrepancy is attributed mainly to the inadequacies of the procedure used for extracting the Mn characteristic signal in the EELS spectra.
Histochemical implications of the chemical and biological properties of SITS and some related compounds
Authors: Horobin Richard W. , Payne J. Nicholas , Jakobsen Palle 
Published: August 2011

SUMMARYSince commercial samples of the fluorochrome SITS (sodium 4‐acetamido‐4′‐isothiocyanatostilbene‐2,2′disulphonate) are of varied, and often of uncertain, composition, the synthesis of SITS has been repeated. The identities of SITS and certain of its precursors and derivatives have been established using modern spectroscopic methods (IR, 1H and 13C NMR), as well as microanalysis. When pure SITS underwent hydrolysis at room temperature the products were amines, not the expected thioureas. This suggests that SITS, contrary to previous expectations, will not bind covalently to proteins, whether immunoglobulins or membrane constituents. Again contrary to earlier statements, pure SITS is not retrogradely transported in neuronal axons. The transported material is a red‐orange impurity which arises very occasionally during the preparation of SITS. A possible structure for this red‐orange compound is proposed: namely a dimeric azo or azoxy condensation product. Comparison of pure SITS with commercial samples indicated that the latter were extremely varied in composition, with SITS contents varying from high to trivial.
A simple method for quantitative SEM at low magnifications
Authors: Waitz W. , Ennemoser O. 
Published: August 2011

SUMMARYA method for quantitative scanning electron microscopy (SEM) at low magnifications has been developed. Quantitative measurements in SEM are rare and often not accurate, because of a systematical error, i.e. a nominal magnification exists only in one direction of the photograph. Our method is suitable for smooth surfaces as it proves the changes of magnification within the two‐dimensional range. In a first step EM‐grids are used as samples. In a second step it is shown how the method can be applied to biological specimens. We took the microstructure of Helix pomatia shells as example.
A synthetic corundum knife for ultrathin sectioning*
Authors: Hodgson Clague P. , Cunningham William P. 
Published: August 2011

SUMMARYA synthetic corundum (Al2O3, synthetic ruby, synthetic sapphire) knife has been constructed which is suitable for the preparation of thin sections (less than 90 nm) of biological specimens for electron microscopy. The method involved cleavage or fracture of the flame‐fusion crystalline product, followed by mounting in a standard knife holder for ultramicrotomy. The cutting edge appeared flawless under 400 × and produced sections in which subcellular organelles were clearly resolved. Scanning electron microscopy of the knife revealed conchoidal fractures typical for corundum, terminating in apparent cleavage of the crystal along the knife edge. X‐ray microanalysis of the knife edge revealed essentially 100% aluminium, indicating that the aluminium oxide crystal was of a high purity. The superior toughness and low cost of synthetic corundum suggest that it may be a useful alternative to diamond or glass knives.
Three‐dimensional reconstruction from a single‐exposure, random conical tilt series applied to the 50S ribosomal subunit of Escherichia coli
Authors: Radermacher M. , Wagenknecht T. , Verschoor A. , Frank J. 
Published: August 2011

SUMMARYWe present a new reconstruction method that takes advantage of the fact that many biological macromolecular assemblies show a preferred orientation with respect to the plane of the specimen grid in the electron microscopic preparation. From one micrograph taken of such a specimen tilted by a large angle, a conical tilt series with random azimuthal angles can be extracted and used for a three‐dimensional reconstruction. Our technique allows the determination of the molecular structure under low‐dose conditions, which are not achievable with reconstruction methods that use conventional tilt series. The reconstruction method combines a number of existing image processing techniques with a newly developed weighted back‐projection algorithm designed for three‐dimensional reconstruction from projections taken with arbitrary projecting directions. The method is described as it was applied to the three‐dimensional reconstruction of the structure of the 50S ribosomal subunit ofEscherichia coli (E. coli).
Colour‐coded stereo images from the tandem scanning reflected light microscope (TSRLM)
Authors: Boyde A. 
Published: August 2011

SUMMARYA method is described for the production of stereo‐pair images in the tandem scanning reflected light microscope in which depths within the field imaged are coded in colour. The two images are recorded photographically whilst focusing vertically through the layer which is to be imaged. A horizontal component of motion is applied at the same time, but in opposing senses for the two images. Colour coding for depth is obtained by changing colour filters so that reflective features lying within different depth bands are imaged in corresponding colours.
Some characteristics of the buffer vehicle in glutaraldehyde‐based fixatives
Authors: Coetzee J. , van der Merwe C. F. 
Published: August 2011

SUMMARYThe pH of sixteen different buffer vehicles is lowered by the addition of glutaraldehyde. This is the case even if the concentration of the buffer is as high as 0.2 m and that of the glutaraldehyde as low as 2%. Graphs are given which make it possible to determine which buffer has the highest buffering capacity at pH‐values between 6.5 and 8. Graphs illustrating the influence of concentrations of glutaraldehyde between 1% and 5% on the dissociation constant of these buffers make it possible to formulate a glutaraldehyde‐based fixative in which an optimally‐buffered vehicle can contribute to the attainment of an osmotically‐balanced fixative.
Should we be counting immunogold marker particles on cell surfaces with the SEM?
Authors: de Harven E. , Soligo D. , Christensen H. 
Published: August 2011

SUMMARYThe lymphocyte in Fig. 1 was incubated with a 1/10 dilution of a murine monoclonal antibody (Leu‐1) directed against a surface antigen expressed on circulating human T‐cells. It was labelled with a colloidal gold/immunoglobulin conjugate and examined with the scanning electron microscope (SEM) in the backscattered electron imaging (BEI) mode. It was easy to count the number of gold particles seen on this cell; actually, we counted 471 of them. For biologists, is this number relevant? We will discuss the principal factors involved in answering this question.
Determination of areal densities of blood vessel wall components in histological sections by means of image analysis
Authors: Verheyen A. , Minten J. , Cornelissen F. , Rombauts W. , Geest H. De 
Published: August 2011

SUMMARYA technique is described which allows quantification of specifically stained, intermingled vessel wall components in paraffin‐embedded tissue. The dissociation of elastic, muscular and connective tissue and the determination of their areal densities in the superior vena cava and in the ascending aorta of the dog, was performed by automated image analysis. The percentages of elastic+connective tissue, determined by this technique, correlated significantly with the data derived from biochemical measurements. It was further found that the structure of the vena cava wall was a function of the distance from the right atrium.
The projection method: Fourier transforms and projected patterns
Authors: Duneau Michel , Katz André 
Published: August 2011

SUMMARYThe projection method is the current basis of numerous research for structural models of quasicrystals. The method provides structures which are quasiperiodic and present an icosahedral symmetry, and allows a simple computation of their Fourier transforms. The two‐dimensional projections of the structures can also be obtained by the same method and are quasiperiodic and discrete.