bluuebunny/crossref_metadata_2025_split huggingface dataset:
Intensity analysis of boron and nitrogen K‐edge spectra for hexagonal boron nitride by EELS
Authors: Saito S. , Higeta K. , Ichinokawa T. 
Published: August 2011

SUMMARYBoron and nitrogen K‐edge spectra for hexagonal boron nitride (h‐BN) were measured by electron energy loss spectroscopy (EELS) at orientations of a momentum transfer q parallel and perpendicular to the c‐axis in order to investigate anisotropic unoccupied states π* and σ*, separately. Differences between intensity profiles for BK and NK spectra are attributed to different transition probabilities at BK and NK edges from Is states to the π* and σ* states. The intensity of the first peak at q∥c in the BK spectrum, which is ascribed to the transition from B‐1s to the Q—2 state in the π* band, is 10 times as large as that in the NK spectrum. Quantitative calculation of transition probabilities for BK and NK spectra at q∥c shows that the contribution of B‐2pz orbital to the Q—2 state is 1–7 times as large as that of N‐2pz. This value suggests that the enhanced peak in the BK spectrum is explained by means of single electron excitations, disregarding the electron‐electron interactions for the exciton reported by several workers. The contributions of 2px and 2py orbitals of B and N atoms to σ* states are also estimated by intensity analysis of BK and NK spectra at q⊥c.
Measurement of translation component at ordered interfaces by weak‐beam α‐fringe electron microscopy
Authors: Miyazawa Kun‐ichi , Ishida Yoichi 
Published: August 2011

SUMMARYLattice translations at a stacking fault and a twin boundary were measured from fringe shifts at a set of common weak‐beam diffraction conditions (weak‐beam α‐fringe imaging) in stainless steel SUS316. It is suggested that the present technique is applicable in determining the translation component between neighbouring crystals with coincidence related boundaries.
High resolution electron microscopy of grain boundaries in Nb3Ge‐films
Authors: Nissen H.‐U. , Kitano Y. , Wessicken R. 
Published: August 2011

SUMMARYNb3Ge‐films synthesized on Mo‐substrates by the co‐evaporation method show a characteristic fabric with a quasi‐twelvefold symmetry around the [001]‐axis of the A15‐type cubic structure. Among approximate +30°‐ and ±60°‐rotation boundaries, grain boundaries having rotation angles between 28° and 29° are observed most frequently in the Nb3Ge‐films. Using the high resolution electron micrographs, a Σ17‐boundary having an ideal rotation angle of 28.07° is analysed and plausible boundary models on the atomic level are proposed.
Some aspects of liquid metal ion sources
Authors: Mair G. L. R. , Mulvey T. 
Published: August 2011

SUMMARYLiquid metal ion sources (LMIS), in view of their very high brightness, have opened new horizons in the field of ion beam technology and microscopy. In this paper some basic ion‐optical problems of LMIS‐based systems are discussed, and also some of the fundamental mechanisms concerning the operation of LMIS. While a type of field‐evaporation is a strong candidate for the main ion emission mechanism, a space‐charge based theoretical treatment successfully predicts the current‐voltage curves of LMIS of low liquid flow impedance. These conclusions are based on the most detailed measurements to date of the ‘peak energy deficit' of the ion energy distribution, and on the comparison with theory of the current‐voltage curves of a variety of LMIS. Finally, from data on gallium LMIS it is shown that an optimum operating current exists around 2 μA.
Structure and composition analysis of silicon aluminium oxynitride polytypes by combined use of structure imaging and microanalysis
Authors: Bando Y. , Mitomo M. , Kitami Y. , Izumi F. 
Published: August 2011

SUMMARYThe relationship between the chemical composition and the crystal structure of the 12H and the 15R polytypes of silicon aluminium oxynitride (sialon) is studied by combined techniques of crystal structure imaging and spectroscopic microanalysis using a new 400 kV high‐resolution analytical electron microscope. The chemical compositions of 12H and 15R are determined to be SiAl5O2N5 and SiAl4O2N4, respectively, from quantitative analysis with energy dispersive X‐ray spectroscopy and electron energy loss spectroscopy. The space groups are determined uniquely to be non‐centrosymmetric P63mc and R3m for the 12H and the 15R, respectively, by observing symmetries appearing in both convergent beam electron diffraction patterns and structure images. The structure images observed are interpreted on the basis of calculated images for proposed structure models, in which the structures consist of stacking sequences of the octahedral and the tetrahedral layers. The structure models are confirmed by calculation of the X‐ray diffraction pattern.
On crystal size and cooling rate
Authors: Bald W. B. 
Published: August 2011

SUMMARYA theoretical model is proposed which is used to derive a quantitative relationship between the critical cooling rate and average crystal size at any location within a biological specimen of given shape subject to rapid freezing. The model is applicable to the slamming, plunging or spraying methods of cryofixation provided the ice crystal size is at least 5 times greater than the size of the critical nucleus.Complete vitrification of pure water or aqueous solutions is shown to take place at cooling rates in excess of about 3 × 106 K/s.
Specimen preparation technique for high resolution transmission electron microscopy studies on model supported metal catalysts
Authors: Jacobs J. W. M. , Verhoeven J. F. C. M. 
Published: August 2011

SUMMARYA new technique is described which can be used for preparing transmission electron microscopy (TEM) specimens suitable for high resolution studies on supported metal catalysts. By conventional silicon processing techniques 200 × 200 μm2 Si3N4 membranes on Si wafers are produced. These membranes are extremely flat and have a uniform thickness of 13 nm. They can be used as a support in various kinds of thin film deposition. A TiO2 film, optimally structured with respect to the requirements for high resolution TEM work in TiO2–metal cluster systems, is deposited on the Si3N4 layer. It consists of one monolayer of 10–25 nm TiO2 crystallites. TiO2 lattice images show that a line resolution down to 0.19 nm is possible. Examples of TiO2–Pd and TiO2–Rh are given using respectively photodeposition and impregnation reduction to produce l.5–4 nm metal clusters.
Immunogold‐silver staining of lymphocyte surface antigens on cells in suspension and in lymph node cryostat sections
Authors: De Waele M. , De Mey J. , Renmans W. , Labeur C. , Reynaert Ph. , Van Camp B. 
Published: August 2011

SUMMARYAn immunogold–silver staining (IGSS) technique for the light microscopical detection of leucocyte cell surface antigens in cell suspensions and cryostat sections is described. The specimens were first incubated with monoclonal mouse antibodies and then with colloidal gold‐labelled goat anti‐mouse antibodies. They were then immersed in a physical developer, counterstained and mounted. In light microscopy, the tissue architecture and the cellular morphology were well preserved. Positive cells showed dark granules on their surface membranes. Optimal labelling conditions were determined. This method proved to be a reliable tool for the enumeration of T‐cells and their subsets in peripheral blood. The dense labelling permitted the use of panoptic counterstains like May‐Grünwald‐Giemsa or Wright's stain. This IGSS technique was used to determine the distribution of the T‐ and B‐cell subsets in cryostat sections of reactive lymph nodes. The sensitivity of the method was comparable with that of immunofluorescence microscopy for cell suspensions and that of the biotin–avidin–peroxidase technique for tissue sections. Immunogold–silver staining was combined with enzyme cytochemistry. In dark‐field or epipolarization microscopy the labelling appeared as bright granules on a dark background. With its dense granular membrane labelling and its good morphology IGSS is an ideal method for the study of particular cell types in mixed cell suspensions. In addition, it could be a general method for the detection of cell surface antigens in all kinds of cells and tissues.
Problems in the production and use of 5 nm avidin‐gold colloids
Authors: Morris Randal E. , Saelinger Catharine B. 
Published: August 2011

SUMMARYOver the past 5 years we have encountered several problems in the production and use of 5 nm avidin‐gold colloids for markers in electron microscopy. These problems include flocculation of colloids during reduction of chloroauric acid, insoluble gold pellets following ultracentrifugation, and non‐specific binding of avidin‐gold colloids to biological membranes. We are able to avoid these problems by: (1) avoiding the use of crystalline chloroauric acid; (2) succinoylating egg white avidin prior to adsorption on the gold sols; (3) resuspending the pellets following ultracentrifugation in 5 mM phosphate buffer, pH 7.5; and (4) using the avidin‐gold colloids within 4 weeks of production.
Simultaneous immunoenzyme double labelling using two different enzymes linked directly to monoclonal antibodies or with biotin‐avidin
Authors: Boorsma D. M. , VanBommel J. , VanderRaaij‐Helmer E. M. H. 
Published: August 2011

SUMMARYA novel and rapid method for immunoenzyme double staining with monoclonal antibodies (McAb) is described. The principles of this method are the simultaneous application of primary antibodies and the unrelatedness of the two detection systems. One McAb is directly labelled with horseradish peroxidase and the other McAb is labelled with biotin. This second McAb is thereafter detected using an avidin‐alkaline phosphatase conjugate. This conjugate was prepared by a new method using a heterobifunctional reagent. Double staining of cell surface membranes of human tonsil was studied in cryosections using various combinations of McAbs to lymphoid cell markers. As expected, suppressor T cells were found to be contained within the pan T cell population on the basis of the distinguishable intermediate colour produced. Similarly, it was shown that most of the suppressor T cells were not HLA‐DR activated in this tonsil. In cryostat sections of human skin T6 positive Langerhans cells in the epidermis were shown to carry the HLA‐DR antigen.
Immuno‐ and enzyme‐histo/cytochemical analysis of resin sections and cell suspensions: a comprehensive diagnosis of bone marrow on a single aspiration sample
Authors: van de Sandt M. M. , Herman C. J. , Lindeman J. 
Published: August 2011

SUMMARYA protocol is described in which a single bone marrow aspiration specimen is used to prepare resin sections and cell suspensions. Using this protocol, a full battery of morphological, enzyme‐histochemical, immuno‐histochemical and cyto‐pathological techniques can be applied. This allows a definitive bone marrow diagnosis to be established without resorting to bone marrow biopsy in the majority of patients.
Inhomogeneity in epoxy resin standards for quantitative biological X‐ray microanalysis
Authors: Condron R. J. , Marshall A. T. 
Published: August 2011

summaryIt is shown by X‐ray point analyses and line scans that the concentrations of sodium and potassium, as crown ether complexes, in epoxy resin may not be of uniform distribution. The concentrations may be substantially higher in a thin layer at the base of the block. It is recommended that chemical analysis of a selected central region of a block, not the intact block, be carried out to establish the true concentration. This may be substantially lower than the nominal concentration. This problem appears to be less acute with cryptate complexes of sodium and potassium but a similar trend is nevertheless apparent.
Automatic description of microstructures
Authors: Gallerneault C. E. , Kulick J. , Powley G. 
Published: August 2011

SUMMARYThis is the third in a series of three papers concerned with developing automatic analysis and classification techniques for metallographic images (specifically binary eutectic alloys of aluminium). The goal of the developmental work was to capture and describe image structure, in the descriptive terminology of a metallographer, and to permit quantification of formerly descriptive parameters. The first paper dealt with the preprocessing stage of image analysis and entailed a study of two segmentation techniques. The second paper reported on work demonstrating the use of texture analysis to characterize structural aspects in images of metallic microstructures. In this paper the textural primatives, or phase particles, are subjected to shape analysis and a novel mechanism for within class characterization. The study of the distribution of these shapes may provide a new means of following the effects of mechanical processing.
Elemental concentrations in isolated rat thymocytes prepared for cryofixation in the presence of different media
Authors: Warley Alice 
Published: August 2011

SUMMARYRat thymocytes were isolated in suspension and the effect of preparing the cells for cryofixation in the presence of different media on the elemental content was investigated using the technique of X‐ray microanalysis. Cells prepared in the different media showed variation in the concentrations of Na, K and Cl. The isolated cells were incubated at 310 K for 1 h to allow recovery from isolation. There was a decrease in Na and Cl content after incubation. The thymocyte population was disturbed by suspension in medium containing dextran, and this resulted in a number of cells with high concentrations of Na and low concentrations of K. These cells did not take up vital dye. Thymocytes were also prepared for freezing by using high‐speed centrifugation to concentrate the cells. Thymocytes prepared by this method showed values for concentrations of Na, K and Cl similar to published values for these cells using other methods of estimation. There were, however, consistent differences in Na content between the cells prepared in Hanks' balanced salt solution and those prepared in serum. Factors which affect the apparent concentration of Na and Cl in isolated cells are discussed.
A rapid method of preparing perforated supporting foils for the thin carbon films used in high resolution transmission electron microscopy
Authors: Lünsdorf H. , Spiess E. 
Published: August 2011

SUMMARYA simple and highly reproducible working technique is described for preparing holey foils as supports for the carbon films used in high resolution electron microscopy. By this method perforation of the Collodion film is accomplished resulting in a net. The diameters of single holes range from 1·8 to 7·9 μm with an average of 4·5 μm.
The application of X‐ray microscopy in materials science
Authors: Cunningham T. G. , Davies R. Ll. , Graham S. C. 
Published: August 2011

SUMMARYX‐ray microscopy is a form of high resolution radiography that uses low‐energy X‐rays (≤10 keV) to enhance the contrast between light elements such as hydrogen, carbon, nitrogen and oxygen. As performed on compact laboratory equipment the technique can achieve spatial resolutions of roughly 1 μm in virtually any material given that the specimen is sufficiently thin (typically 0·2–2 mm) to be adequately transparent to low‐energy X‐rays. Notwithstanding that the technique has lately found favour in biomedical radiology, its considerable potential in other fields, notably the materials sciences, remains largely unexploited.The scope and potential of laboratory X‐ray microscopy in the materials sciences is demonstrated here by its application to ceramics, elastomers, coal‐chars and reinforced composites. In all cases the technique provided valuable microstructural characterization often unobtainable by any other non‐destructive method. These examples demonstrate that laboratory X‐ray microscopy offers much to the materials sciences and deserves a wider application than is current.
Quantitative image analysis of finite porous media
Authors: Macdonald I. F. , Kaufmann P. , Dullien F. A. L. 
Published: August 2011

SUMMARYReconstruction, from serial sections, of a branch‐node chart containing the connection pattern of the pore channels in small sandstone samples, and computation of genus are described.Seventy‐eight serial sections were obtained by serially grinding off layers of about 10 μm thickness from a 1 × 1 mm sample, whose pores had been filled with Wood's metal, and taking photomicrographs of the polished sections. Edge effects and rock enclosed by pore space were accounted for in the construction of the branch‐node chart. The importance of boundary effects was reflected by the difference between the minimum and maximum estimates of genus, Gmin and Gmax, respectively.The Berea sample (with porosity of 23% and average grain size of about 200 μm) was found to have essentially one main network containing over 87% of all pore space features, plus a number of very much smaller boundary networks representing ‘dents' on the sample sides. The number of anomalies from missed connections was found to be small and unlikely to cause significant error in the genus calculations. Both Gmin and Gmax for the sample were found to be essentially those of the one continuous main network.
Analog enhancement of videomicroscope images
Authors: Burton J. L. , Bank H. L. 
Published: August 2011

SUMMARYA simple, inexpensive technique for enhancing the contrast and resolution of videomicroscope images has been developed. The system has manual controls for gain and pedestal (black level) which permit expansion of low contrast images to the full white‐to‐black video range. Analog delay‐line based circuits are used to sharpen the edges and enhance fine details in the image. These circuits also produce an effective increase in the information content of the image by selectively amplifying low amplitude, high frequency components of the video signal. When live, unstained cells were examined at high magnifications, cytoplasmic structures which were only faintly visible in the unenhanced image became clear. The images of fluorescent objects appear in pseudo‐relief, which improves visibility even in the presence of background fluorescence. The system enhances images by performing signal processing functions that otherwise require expensive digital image processing equipment.
Why low temperature embedding for X‐ray microanalytical investigations?
Authors: Wróblewski Joanna , Wróblewski Romuald 
Published: August 2011

SUMMARYFreeze‐drying followed by infiltration with resin and polymerization by UV light at low temperatures and under constant vacuum conditions is an alternative tissue preparation technique for microprobe analysis. Embedding is carried out with the nonpolar low‐temperature embedding resin (Lowicryl HM20) which allows infiltration and polymerization at temperatures down to −50°C. Sections of low temperature embedded material can be cut dry at −60°C or at room temperature. Sectioning at low temperatures is an alternative for preparations that are difficult to cut at room temperature.The morphological preservation is adequate for the identification of structures such as mitochondria, lysosomes and different types of endoplasmic reticulum in liver cells. Some physical properties of Lowicryl resins, such as mass loss under the electron beam and high contrast, are positive characteristics for the analysis of semi‐thick sections. No significant differences in the elemental composition could be detected between tissue which was freeze‐dried or freeze‐substituted prior to embedding. Freeze‐drying is less time consuming. By avoiding contact with organic solvents the risks of ion loss and redistribution are diminished. In contrast to freeze‐dried thin cryosections, low temperature embedded material can be sectioned for light microscopy and areas of interest chosen for further thin sectioning. This is of great importance in work with tissues with complicated morphology and heterogeneous cell populations. The initial preparative step—the cryofixation— determines to a high degree the morphological preservation of freeze‐dried and embedded tissue.
Water content from analysis of freeze‐dried thin sections
Authors: Warner Ronald R. 
Published: August 2011

SUMMARYThe analytical electron microscope and related electron beam instruments are uniquely able to measure the water content of biological tissue at a subcellular level. An analysis of the Rick procedure for quantifying this water content (Dörge et al., 1978; Rick et al., 1979) reveals a hidden assumption; namely, that the sample and standard densities, in the hydrated state, must be equal. In general this will not be valid. Equations are derived that do not invoke this hidden assumption. These equations show that errors in using the Rick technique for measuring water content should be small, a few per cent, unless the sample contains a very heterogeneous distribution of mass or the water content of the standard is a poor representation of the sample. For freeze‐dried samples with extensive mass heterogeneity, such as skin, the equations for calculating water content presented in this paper should be used.
Quantitative electron microscope autoradiography: application of multiple linear regression analysis
Authors: Markov Dimiter V. 
Published: August 2011

SUMMARYA new method for the analysis of high resolution EM autoradiographs is described. It identifies labelled cell organelle profiles in sections on a strictly statistical basis and provides accurate estimates for their radioactivity without the need to make any assumptions about their size, shape and spatial arrangement. The radioactivity in interfacial membranes and transitional junctional regions between pairs of adjoining cell structures can be determined without any additional measurements. The uniformity of internal labelling of large cell organelles can be also assessed. Correcting for cross‐fire does not need any predictive information from a frequency distribution function describing the image spread about a radioactive point source. Instead, the section area is subdivided into regions in such a way that each region with cross‐fired silver grains over it includes also the sites of the radioactive disintegrations that have produced them. The method is based on the quantitative regression relationship between the number of developed silver grains overlying any given region and the size of the cell organelle profiles included. A transparent overlay screen bearing a regular array of circles and a point‐counting procedure are applied to divide the section area into regions and to measure their area and the size of the cell organelle profiles. The least squares method is used for the simple and rapid calculation of specific activity estimates and exact standard errors to be attached to them. A modest computing facility and a standard library program are required. Simulation modelling and analysis of residuals were used to lend support to the validity of the method.
Direct imaging of paracrystalline phospholipid structure in the electron microscope
Authors: Fryer J. R. , Dorset D. L. 
Published: August 2011

SUMMARYA long chain amphiphilic molecule—the phospholipid 1,2‐dihexadecyl sn glycerophosphoethanolamine—has been crystallized epitaxially so that the interlamellar molecular periodicity is parallel to the substrate and hence normal to the electron beam in the electron microscope. This has permitted the direct resolution of the 55·6 Å lamellae in unstained crystals at room temperature.The lattice images have shown the presence of line dislocations and lenticular cracks in the crystals. Of significance to their biological properties is that the lattice is undulating with a periodicity of 0·1–0·5 μm. This would also account for the difficulties encountered by X‐ray and electron diffraction techniques when examining these crystals.