bluuebunny/crossref_metadata_2025_split huggingface dataset:
The compatibility of TiB2 protective coatings with SiC fibre and Ti‐6Al‐4V
Authors: CHOY K. L. , DERBY B. 
Published: August 2011

SUMMARYTiB2 coatings have been studied as prospective protective layers to inhibit the interfacial reaction between SiC fibres and Ti‐alloy matrices. This protective coating has been deposited onto SiC monofilament fibres using a chemical vapour deposition (CVD) technique. The fibre‐matrix compatibility of these TiB2‐coated SiC fibres in Ti‐6Al‐4V composites was evaluated by incorporating the coated fibres into Ti‐6Al‐4V using a diffusion bonding technique. The interfaces of this composite were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and electron probe microanalysis, to evaluate the interfacial microstructures, chemical stability and the efficiency of TiB2 as a protective coating for SiC fibres in Ti‐alloy matrices, and to study the effects of deposition temperature on the interface of the coated fibre. Results show that stoichiometric TiB2 coatings are stable chemically to both SiC fibres and Ti‐6Al‐4V and hinder the deleterious fibre‐matrix reactions effectively. Boron‐rich TiB2 coatings should be avoided, as they lead to the formation of a needle‐like TiB phase at the fibre–matrix interface. These findings provide promising evidence for the value of further exploration of the use of stoichiometric TiB2 as a protective coating for SiC fibre in Ti‐based composites.
Fabrication of macroscopic solid models of three‐dimensional microscopic data by selective laser sintering
Authors: BARTELS K. A. , CRAWFORD R. H. , DAS S. , GUDURI S. , BOVIK A. C. , DILLER K. R. , AGGARWAL S. J. 
Published: August 2011

SUMMARYWe discuss and give examples of the use of selective laser sintering to fabricate solid macroscopic models of microscopic specimens that have been imaged with a confocal microscope. The digital image processing necessary to create structurally sound models of both translucent and opaque specimens is presented. The fabricated models offer the ultimate in data visualization since they can be physically handled and manipulated to investigate the shape and features of the specimen. Such a powerful visualization tool is useful in both research and educational environments.
Vertical LM sectioning and parallel CT scanning designs for stereology: application to human lung
Authors: PACHE J.‐C. , ROBERTS N. , VOCK P. , ZIMMERMANN A. , CRUZ‐ORIVE L. M. 
Published: August 2011

SUMMARYPractical, unbiased stereological methods are described to estimate lung volume and external surface area, and total volume and surface area of relatively large and anisotropic structures (bronchi and arteries) inside the lung.The volume of each of five lung strata was estimated first by fluid displacement and then by computed tomography (CT) using Cavalieri's method; the reliability of CT was assessed through a calibration procedure, and image thresholding criteria for an accurate volume estimation using CT were established. The parallel, perfectly registered CT section images were also used to estimate the external surface area of each stratum by the spatial grid method.Unbiased estimation of internal surface areas in lung is a long‐standing problem: since the structures are large and essentially void, large sections are needed; to facilitate identification, thin sections have to be used for light microscopy, and since such structures are anisotropic, the sections should be vertical. A practical stereological design is demonstrated here on an infant lung, which fulfils all these requirements.This study illustrates the potential of using unbiased stereology to characterize infant pulmonary hypoplasia.
The rotator
Authors: JENSEN E. B. VEDEL , GUNDERSEN H. J. G. 
Published: August 2011

SUMMARYThe mean particle volume can be stereologically estimated using the nucleator principle. In the present paper, we discuss another principle for estimating mean particle volume, namely the rotator. The vertical rotator has already been previously described and is supplemented in the present paper by the isotropic rotator. For a collection of particle profiles, simulations show that the variance of the rotator is smaller than that of the nucleator.
Quantitative parallel electron energy‐loss spectrometry of Cu—Be alloys
Authors: STRUTT A. J. , WILLIAMS D. B. 
Published: August 2011

SummaryA technique is described for the quantitative microanalysis of a Cu‐Be alloy using parallel electron energy‐loss spectrometry. Spectrum acquisition and processing variables were optimized specifically for Cu—Be alloy spectra in an attempt to ensure that signal collection was equally efficient for both Be and Cu edges and that reliable, consistent results could be obtained from the subsequent quantification procedure. Analyses of the Cu Be γ–phase showed that the nominal composition of 50 at.% Be is not constant, and that Cu solubility increases slightly with increasing ageing temperature.
Measurements of wet metaphase chromosomes in the scanning transmission X‐ray microscope
Authors: WILLIAMS S. , ZHANG X. , JACOBSEN C. , KIRZ J. , LINDAAS S. , VAN'T HOF J. , LAMM S. S. 
Published: August 2011

SummaryRadiation damage to Vicia faba chromosome structure, as measured by the mass loss, was determined in the scanning transmission X‐ray microscope for unstained specimens in both the wet and dry states. Dried specimens remain undamaged after either single or multiple images at doses up to 2400 Mrad at wavelengths of 3·15 or 3·64nm. In contrast, wet specimens are damaged irrespective of the imaging protocol. The damage induced by multiple exposures is greater than that seen in a single exposure of the same total dose. Thus, the rate of data collection is greater than or equal to the rate of damage. The damage during multiple exposures of wet chromosomes is influenced by several factors. First, the fixative used influences the extent of radiation damage. Wet chromosomes fixed with glutaraldehyde are more resistant than those fixed with formaldehyde or osmium tetroxide. A second factor is ionic strength. Damage to wet chromosomes increases if the ionic strength decreases below that at which chromatin undergoes a conformational transition. The mass of wet and dry chromosomes is the same, and consequently quantitative measurements can be made on wet specimens. Such measurements give a DNA mass fraction of 39 ± 8% for V. faba chromosomes.
Surface studies in UHV SEM and STEM
Authors: MILNE R. H. , HEMBREE G. G. , DRUCKER J. S. , HARLAND C. J. , VENABLES J. A. 
Published: August 2011

SummarySome recent advances in surface analyses with scanning electron microscopy techniques are reviewed. It is shown that secondary electron microscopy can image monatomic steps, emergent dislocations and the early growth of thin films and oxide nuclei. The chemical composition of inhomogeneous surfaces can, in some cases, be determined with nanometre resolution with Auger signals. Overlayer coverages can occasionally be monitored with the secondary electron signal if the change of work function with coverage has been determined previously. The interpretation of these secondary and Auger signals is discussed. The combination of angular electron spectroscopy with electron microscopy is potentially a powerful technique for determining atomic positions of surface atoms and one method for obtaining the experimental data is described. Several substrate/overlayer systems are used to illustrate the amount of information that can be obtained about surface processes with scanning electron microscopy.
Three‐dimensional imaging of corneal cells using in vivo confocal microscopy
Authors: PETROLL W. M. , CAVANAGH H. D. , JESTER J. V. 
Published: August 2011

SummaryConfocal microscopy is a unique and powerful imaging paradigm which allows optical sectioning through intact tissue. Real‐time tandem scanning confocal microscopy has previously been used to generate high‐magnification two‐dimensional (2‐D) images of cells in living organ systems. Inherent problems with movement, however, have prevented the in vivo acquisition of complete 3‐D datasets. The development of a new objective lens, used in combination with specialized real‐time image acquisition procedures, has allowed sequential serial sections to be obtained in vivo from the rabbit cornea for the first time. These sections can be digitially registered and stacked on the computer to provide a 3‐D reconstruction of the corneal cells. This technique should serve as a useful method for studying 3‐D structures and analysing 4‐D phenomena at the cellular level in living animals. Three‐dimensional images of a stromal nerve in normal rabbit cornea and of fibroblasts within a rabbit corneal wound are presented as examples of current capabilities.
A scanning tunnelling microscopy study of the formation and chemical activation of step defects on the basal plane of pyrolytic graphite
Authors: MOROZOV V. N. , SHERMAN J. , KALLENBACH N. R. , DU SHOU MING , SEEMAN N. C. 
Published: August 2011

SummaryScanning tunnelling microscopy is used to monitor etching of the basal plane of highly orientated pyrolytic graphite by ozone, oxygen and nitric acid. These treatments are seen to produce numerous single and multilayer step defects. Subsequent modification of the graphite sheet edges flanking these cavities by cyanuric chloride, TiCl4 and other reagents is shown to activate the edges, thereby making them capable of covalently binding various molecules.
The number of glomerular capillaries estimated by an unbiased and efficient stereological method
Authors: NYENGAARD J. R. , MARCUSSEN N. 
Published: August 2011

SummaryA method for unbiased capillary number estimation based on the estimation of the Euler–Poincaré characteristic or Euler number with the disector is evaluated. The generation of a new capillary creates a new loop in the capillary network corresponding to a change of exactly one unit in the Euler number of the network. In this way the Euler number has a one‐to‐one relationship to the number of capillaries in a network. In this report rat glomerular capillaries are counted.Three tissue blocks from each of 14 perfusion‐fixed rat kidneys, aged between 5 days and 18 months, were uniformly sampled and embedded in Epon. Two complete glomerular profiles were sampled per block. Three consecutive sections were studied per glomerulus using the middle one to evaluate the topological events of the capillaries in the sampled glomerulus. The use of complete glomerular profiles eliminated problems with the edges, whereas the disector ensured unbiased sampling in the third dimension. Estimates per animal were weighted averages over blocks, the weights being half the number of glomerular profiles in a section from a block. The number of capillaries in a glomerulus is the mean Euler number per disector volume multiplied by the mean volume of glomeruli obtained by the fractionator.The observed coefficient of variation between animals was 18.3% for the estimated number of capillaries per glomerulus, and the observed coefficient of error at the level of blocks within animals was 14.7%. The exact capillary number from the node‐branch network of two reconstructed glomeruli equalled the capillary number obtained by the total Euler number from the same glomeruli. This shows in an applied example, as would be expected, that the estimation of capillary number using the Euler number is unbiased and independent of the direction of sectioning.
Measurements of fibre direction in reinforced polymer composites
Authors: CLARKE A. , DAVIDSON N. , ARCHENHOLD G. 
Published: August 2011

SummaryHigh‐quality data on the three‐dimensional (3‐D) spatial distributions of glass and carbon fibres in fibre‐reinforced polymer composites are important for both process control and the modelling of the mechanical and thermal properties of these composites. The advent of economical, high‐speed, image analyser systems has enabled numerous research groups to measure directional distributions of fibre samples. Specimens are microtomed and polished and, using optical reflection microscopy, thousands of elliptical fibre images may be analysed within a short period of time. From the eccentricity of the fibre images, estimation of the angles (θ, φ) of each fibre relative to the vertical axis and within the measurement plane is deduced. However, this measurement is subject to considerable error. The confocal scanning laser microscope (CSLM), operating in fluorescence mode or reflection mode, is capable of improving the angular resolution (δθ, δφ) for all fibre directions. The ability of the CSLM to optically section glass and carbon fibre‐reinforced polymer composites down to depths of 20 or 30 μm allows the user to determine accurate fibre directions from the apparent movement of fibre profiles. The CSLM has the potential for standardizing measurements of 3‐D fibre directions in polymer composites and providing the quality directional data which are required for the theoretical modelling of composite processing and composite strength.
Near‐field optical microscopy in transmission and reflection modes in combination with force microscopy
Authors: VAN HULST N. F. , MOERS M. H. P. , BÖLGER B. 
Published: August 2011

SummaryNear‐field optical microscopy is the optical alternative of the various types of scanning probe microscopes. The technique overcomes the classical diffraction limit in conventional optical microscopy. In this paper the concepts of near‐field optics (NFO) are introduced, followed by a short review of current trends in NFO microscopy. Specifically, developments concerning the efficiency and versatility of both aperture and dielectric probe types are discussed. We present our advances in NFO microscopy, using both fibres and integrated silicon nitride (SiN) structures as dielectric probes. The use of an SiN probe as a combined optical and force sensor is shown to be advantageous, as it provides a feedback mechanism and allows direct comparison between topography and dielectric effects. Images of technical and biological samples are presented with a lateral resolution down to 20 nm, depending on the microscopical arrangement used.
Silver‐enhanced colloidal‐gold labelling of rabbit kidney collecting‐duct cell surfaces imaged by scanning electron microscopy
Authors: HERTER P. , LAUBE G. , GRONCZEWSKI J. , MINUTH W. W. 
Published: August 2011

SummaryThe luminal cell surfaces of rabbit kidney cortical collecting‐duct cells were labelled with peanut lectin (PNA) and investigated by scanning electron microscopy. Labelling was performed either on 20‐μm‐thick cryostat sections from prefixed and cryoprotected rabbit kidney tissue or on cultured collecting‐duct epithelium using biotinylated PNA and a 6‐nm colloidal‐gold‐coupled antibody against biotin. Colloidal‐gold labels were detected at low magnification (2000–4000 x) using silver enhancement. Coating with chromium allowed simultaneous imaging of both cell‐surface morphology and labelling topography in the backscattered electron imaging mode. Our results show that PNA binding is specific for a subtype of intercalated cells equipped with microvilli on the luminal surface. The presented method promises to be useful for the identification of specific cell types in heterogeneous tissues.
Variation in maceral chemistry within and between coals of varying rank: An electron microprobe and micro‐Fourier transform infra‐red investigation
Authors: MASTALERZ M. , BUSTIN R. M. 
Published: August 2011

SummaryElectron microprobe and reflectance micro‐Fourier infra‐red techniques have been used to document the evolution of maceral chemistry from lignite to anthracite as well as to determine chemical variations between macerals and within macerals in iso‐rank coals. This study shows that the evolution of elemental composition and functional groups in vitrinite differs from those of liptinite. In vitrinite, there is a decrease in the absorbance of both aliphatic stretching bands (2800–3000 cm—1) and the aromatic band (1600 cm—1) with an increase in rank from high‐volatile bituminous to anthracitic coals. The change in functional groups is associated with an increase in C content from about 86 up to 94% and a decrease in O content from 7 to 1%. In sporinite, carboxyl/carbonyl bands (1710 cm—1), distinct in sub‐bituminous and high‐volatile bituminous ranks, disappear at higher rank. The 1600 cm—1 band is relatively weak in liptinite and increases dramatically when liptinite and vitrinite coalification paths merge. These changes in sporinite functional groups are accompanied by an increase in C content from 73 to 88–89%, decrease in O from 14 to 4% and decrease in H from more than 9 to less than 4%.Variations in chemistry between macerals and within macerals depend on coal rank. Up to high‐volatile bituminous rank, liptinite macerals have higher absorbances of aliphatic stretching bands and lower absorbances of the aromatic 1600 cm—1 band than any other macerals. At medium‐volatile bituminous rank, aliphatic stretching bands are distinct in vitrinite and semifusinite and very weak to absent in other inertinite macerals. At anthracitic rank, variations both in elemental composition and in functional groups between maceral groups are of the same magnitude as within maceral groups.
Scanning tunnelling microscopy of conjugated polymers
Authors: BOND S. F. , FRIEND R. H. , HOWIE A. 
Published: August 2011

SummaryImages of the conjugated polymers poly(p‐phenylene vinylene) and poly(3‐hexylthienylene) deposited on gold, silver and graphite have been obtained using a Nanoscope II STM in air at room temperature. Areas of semi‐crystalline structure have been observed, with local alignment of chains on the surface.
Euler‐Poincaré characteristic of a randomly filled three‐dimensional network
Authors: JERNOT J. P. , JOUANNOT P. 
Published: August 2011

SummaryThe random filling of a three‐dimensional face‐centred cubic network is simulated on a computer at increasing densities between 0 and 1. The Euler‐Poincaré characteristic (for the spaces ℝ0, ℝ1, ℝ2 and ℝ3) is then measured on all the simulated structures. A quantitative description of this simple densification process is obtained and the maxima observed correspond to the highest values practically attainable for the stereological parameters.
The cryopuncher: A pneumatic cryofixation device for X‐ray microanalysis of tissue specimens
Authors: ZIEROLD K. 
Published: August 2011

SummaryA cryopunching device is described which allows cryofixation of tissue specimens by quick contact with a precooled copper surface during excision. The advantage of the cryopuncher for analytical electron microscopy of cells and tissues in defined functional states is illustrated by electron probe X‐ray microanalysis of freeze‐dried cryosections from rat liver and dogfish kidney. In comparison with results obtained from specimens plunged into liquid propane, cryopunching in situ results in similar preservation of morphology and remarkably improved intracellular K/Na ratio.
Random models for morphological analysis of powders
Authors: JEULIN D. 
Published: August 2011

SummaryModels to estimate powder size distributions or fractions of components in a mixture of powders were developed and tested for various specimens. The models derived from the Boolean model and from the dead leaves models can be implemented on rough secondary electron scanning electron microscope images, obtained after minimal sample preparation. With the dead leaves tessellation, the size distributions of spherical particles or short fibres can be estimated either from the size distribution of intact grains, or from the area fraction measurement after binary erosions. With the dead leaves random function, there is no need for image segmentation. It provides data on the size and shape of a population of particles from an estimation of the distribution of grey‐level images after erosions by convex structuring elements of increasing size. A version of these models for long fibres is developed for estimating their diameter distribution. Allowing for superposition of particles, the proposed methods enable an unbiased estimation of the size distribution and characterization of the shape of complex particles. The approach is illustrated by applications to spherical particles obtained by simulations and from scanning electron microscope micrographs.
Vitrification depth can be increased more than 10‐fold by high‐pressure freezing
Authors: SARTORI N. , RICHTER K. , DUBOCHET J. 
Published: August 2011

SummaryBiological specimens prepared for cryoelectron microscopy seem to suffer less damage when they are frozen under 2 kbar pressure rather than under normal conditions. The volume that can be well preserved is larger. This fact has been illustrated in a number of publications on a number of different samples. However, there is a lack of quantitative data concerning the depth of this good specimen preservation.Catalase crystals in various sugar solutions have been used as test objects and vitrification, as determined by electron diffraction, has been used as the criterion for good freezing. Keeping all other conditions equal, the depth of vitrification is approximately 10 times larger with freezing at high, rather than normal, pressure. The high‐pressure vitrification depth in a 15–20% sugar solution averages 200 μm. Fully vitrified specimens up to 700 μm in thickness are obtained. When crystalline water is observed it is frequently in the form of high‐density ice II, III or IX.These results are probably also relevant for typical biological specimens. The advantage of high‐pressure freezing must be balanced by the possible consequences of a considerably increased cooling time and by the damage that may be induced by the pressure.
High‐spatial‐resolution maps of sulphur from human hair sections: An EELS study
Authors: HALLEGOT P. , CORCUFF P. 
Published: August 2011

SummaryHigh‐resolution sulphur maps have been acquired from human hair using a Zeiss CEM 902A transmission electron microscope equipped with an energy filter. Analysis by electron energy‐loss spectroscopy (EELS) was performed on ultrathin sections of hair shafts embedded in three different types of resin: Nanoplast (water‐soluble), Spurr (epoxy) and Lowicryl (low‐temperature resin). Good‐quality energy‐loss images have been obtained with the three resins, although it was found that Nanoplast gave the best image contrast. For the first time, the results obtained for the detection of sulphur by silver staining of hair sections, which until now has been the only way to map sulphur at the electron microscopic level, have been confirmed. The results are compared with local sulphur concentrations from bulk analysis.
Remapping disparate images for coincidence
Authors: GALBRAITH W. , FARKAS D. L. 
Published: August 2011

SummaryWith the development of complex multimode computerized microscope systems, it is possible and necessary to obtain images of the same area of the microscopical preparation by several methods of microscopy, such as differential interference contrast, reflection interference microscopy, several wavelengths of fluorescence microscopy, laser scanning and confocal modes. Thus, varied information may be obtained about a single field, in the form of a set of images, taken at different ports of the microscope, using different digitizing cameras, each appropriate to certain tasks. For comparative purposes, the images should be superimposable, pixel by pixel, but in general they are not — they differ in image shape and size, magnification, distortion, centration and orientation. This paper shows how the problem may be approached, using an extension of the remapping procedures described in a previous paper, in which images of a separate grid reference slide are used to detect, quantify and correct the image errors. Affine remapping, without the use of grid images, is also described.