bluuebunny/crossref_metadata_2025_split huggingface dataset:
Optical microscopy of carbonaceous solid residues from coal hydrogenation: a classification
Authors: Ng Nancy 
Published: August 2011

SUMMARYA classification for the carbonaceous solid residues from coal hydrogenation is proposed, based on that introduced by Mitchell et al. (1977). A more precise and restricted definition is applied to the proposed terminology. This systematic classification may lead to a better understanding of the dissolution and thermal alteration of macerals in a closed system and should also ensure meaningful comparisons between quantitative point count data.
Mapping of polished coal surfaces by automated reflectance microscopy
Authors: Davis Alan , Kuehn K. W. , Maylotte D. H. , Peters R. L. St. 
Published: August 2011

SUMMARYThe capabilities of Rapid Scan, a system of automated reflectance microscopy, has been extended to the actual mapping of petrographic variation across polished coal surfaces. This is accomplished through computer control of a microscope stepping stage and the storage of binary reflectance data on disc in a matrix form which permits the proper spatial arrangement of values to be re‐created. The maps depict lithotype variation, and the distribution of mineral occurrences, cracks and cleat. An image processor can be employed in further map analysis such as the compilation of reflectance profiles from selected areas.
Tandem scanning reflected light microscopy of internal features in whole bone and tooth samples
Authors: Boyde A. , Petran M. , Hadravsky M. 
Published: August 2011

SUMMARYAn improved version of the tandem‐scanning reflected‐light microscope (Petran et al., 1968) has been studied with respect to its applicability to the study of mammalian mineralized tissues. It was found to have important advantages compared with other light microscopic methods, since it allowed microscopic structures to be seen at considerable depths within intact specimens. It has a small depth of focus and gives high contrast for features such as osteocyte lacunae and canaliculi in bone, and prism boundaries in dental enamel.
A microinterferometric method for analysis of rotation‐symmetric refractive‐index gradients in intact objects
Authors: Nilsson D.‐E. , Andersson M. , Hallberg E. , McIntyre P. 
Published: August 2011

SUMMARYA new method for measuring refractive‐index gradients in rotation‐symmetric objects is described. Interference micrographs of intact objects, with the symmetry axis perpendicular to the optical axis of the microscope, are used to obtain a phase‐shift profile, which is converted into a refractive‐index profile by a computer program. The conversion calculations are based on iterative approximations of the gradient slope in a number of presumed shells in the object. The method is fast, convenient and yields highly accurate results even when only a small number of phase shift values can be obtained. The new method is especially advantageous for analysing many invertebrate eyes but it can also be used for measuring manufactured graded‐index optical fibres.
Mica: A convenient support for biological SEM specimens in a TEMSCAN microscope
Authors: Johansen B. V. , Namork Ellen , Bukholm Geir 
Published: August 2011

SUMMARYMica is proposed as a convenient substrate for SEM specimens. Mechanically, mica is rigid and can be cut, punched and cleaved into suitable sizes. Compared to glass substrates, mica seems to be more charge ‘resistant’ when irradiated with the same beam density in the microscope.
Automated focusing of an optical microscope
Authors: Kenny L. C. 
Published: August 2011

SUMMARYAutomated microscope focusing can be seen as a special pattern recognition problem. Current focusing techniques, which identify the optimum focus by its characteristic increase in contrast, have limitations, and the use of texture analysis is suggested as an alternative.Both approaches were tested on two samples of fine particles with very different characteristic images, and several texture parameters were found to indicate optimum focus. Focusing methods suitable for routine use in the analysis of these samples were developed and tested. The spatial content of the texture measurements was found to contribute significantly to the accurate prediction of the optimum focus position, particularly in images lacking contrast.
A safe and effective mixer for high viscosity embedding media for electron microscopy
Authors: Helmer K. , Nielsen J. , Schmalbruch H. 
Published: August 2011

SUMMARYThe design of an efficient mechanical mixer for embedding media for electron microscopy is described. The resins are mixed within a closed bottle mounted on the plate of a commercial vibration sander. The primary aim of the construction was to reduce the exposure to potentially toxic substances; in addition it has proven to be more convenient to use the apparatus than to mix the resins by hand.
A comparison of two models for the characteristic X‐ray fluorescence correction in thin foil analysis
Authors: Twigg M. E. , Fraser H. L. 
Published: August 2011

SUMMARYIt is shown that Philibert & Tixier's calculation for the contribution of characteristic fluorescence in thin foil X‐ray microanalysis is in error. The calculation of Nockolds et al. for this contribution is shown to be correct.
A method for the preparation of cerebral blood vessels
Authors: Grocki Kurt , Dermietzel Rolf 
Published: August 2011

SUMMARYElements of the cerebral vascular system of the rat have been prepared by simultaneous perfusion with fibrinogen and thrombin. The resulting fibrin fills and serves to support the vessels which can then easily be excised from the brain and prepared for light and electron microscopy. The structure and ultrastructure of cerebral blood vessels is well preserved by this technique.
Conventional transmission electron microscopy (CTEM) of unstained, melamine‐embedded frog photoreceptor membranes
Authors: Westphal C. , Bachhuber K. , Frösch D. 
Published: August 2011

SUMMARYMelamine‐formaldehyde, a universally used technical aminoplast, was recently introduced as a water‐soluble embedding‐medium for electron microscopy (Bachhuber & Frösch, 1983). When processed with this new technique, the membranes of aldehyde‐fixed, unstained frog photoreceptor outer segments show remarkable contrast and detail in conventional TEM bright field imaging. Through‐focus‐series, showing true contrast reversal, indicate that images from defocused, unstained melamine sections are generated primarily by phase contrast.
An autoradiographic method for determining nutrient competition between leaf epiphytes and plant pathogens
Authors: Edwards M. C. , Blakeman J. P. 
Published: August 2011

SUMMARYA method is described for the study of nutrient competition between leaf surface microorganisms and plant pathogenic fungi. Autoradiography was used to investigate the uptake of water‐soluble 14C‐labelled nutrients by applying a dry pre‐formed layer of emulsion to the specimen. The method was adapted for use on both leaf and artificial surfaces. A photometric method was used for rapid examination of autoradiographs.
Statistical significance of molecule projections by single particle averaging
Authors: Haenicke W. , Frank J. , Zingsheim H. P. 
Published: August 2011

SUMMARYA statistical test based on a multiple comparison of Friedman's rank sums has been developed to determine the statistical significance of molecule projections obtained by non‐crystallographic averaging techniques. The test, applied to electron microscope images of the acetylcholine receptor molecule, confirms the significance and quoted resolution of averages by Zingsheim et al. (1980, 1982a, b).
Mass thickness determination by electron energy loss for quantitative X‐ray microanalysis in biology
Authors: Leapman R. D. , Fiori C. E. , Swyt C. R. 
Published: August 2011

SUMMARYAs is well known, electron energy loss spectroscopy can be used to determine the relative sample thickness in the electron microscope. This paper considers how such measurements can be applied to biological samples in order to obtain the mass thickness for quantitative X‐ray microanalysis. The important quantity in estimating the mass thickness from an unknown sample is the total inelastic cross section per unit mass. Models for the cross section suggest that this quantity is constant to within ±20% for most biological compounds. This is comparable with the approximation made in the continuum method for measuring mass thickness. The linearity of the energy loss technique is established by some measurements on evaporated films and quantitation is demonstrated by measurements on thin calcium standards. A significant advantage of the method is that the energy loss spectrum can be recorded at very low dose, so that mass thickness determination can be made before even the most sensitive samples suffer damage resulting in mass loss. The energy loss measurements avoid the necessity to correct the continuum measurement for stray radiation produced in the vicinity of the sample holder. Unlike the continuum method the energy loss technique requires uniform mass thickness across the probe area, but this is not usually a problem when small probes (<100 nm diameter) are used.
Experimental and theoretical determination of kAFe factors for quantitative X‐ray microanalysis in the analytical electron microscope
Authors: Wood J. E. , Williams D. B. , Goldstein J. I. 
Published: August 2011

SUMMARYQuantitative X‐ray microanalysis in the analytical electron microscope involves the use of Cliff‐Lorimer kAB factors to relate measured X‐ray intensities from elements A and B to their composition. This study has generated a wide range of these factors for both K and L X‐ray lines. The values of the k factor for each element is ratioed to Fe, rather than to Si as has been common practice to date. The use of kAFe rather than kASi factors reduces the uncertainty in the values due to variations in the efficiency of individual energy dispersive spectrometers, thus making the values more universally applicable.New calculations of the value of kAFe have been made from first principles, encompassing all of the most recent values of the cross‐section for X‐ray ionization. Comparison of the experimental results with both the calculations and existing k factor data has been made. Close attention has been paid to minimizing the errors in both the experimental and theoretical calculations to reduce the overall error in quantification of X‐ray energy dispersive spectra in the analytical electron microscope.
Determination of Cliff‐Lorimer k factors by analysis of crystallized microdroplets
Authors: Graham R. J. , Steeds J. W. 
Published: August 2011

SUMMARYThe Cliff‐Lorimer ratio technique for thin foils was used to determine a set of k factors at 120 kV for calibration of the energy dispersive X‐ray analyser on a Philips EM400 analytical electron microscope. The standards used were the crystallized forms of microdroplets of solutions of inorganic salts. These experimental data were compared with other experimental work and found to agree within the experimental error with theoretical k factors.
Surface reflection interference microscopy:* A new method for visualizing cytoskeletal components by light microscopy
Authors: Opas Michal , Kalnins Vitauts I. 
Published: August 2011

SUMMARYSurface reflection interference microscopy of detergent resistant residues of cultured cells stained with protein dyes can be used to obtain high resolution images of the cytoskeleton. We have compared the images obtained using different dyes and have examined the effect of four of these dyes on the visualization of different parts of the cytoskeleton in detail. The dependence of contrast of the images obtained on the illuminating numerical aperture and the wavelength of incident light was determined. Staining with Acid Yellow 36, Guinea Green B and Naphtol Blue Black produces images from the entire cytoskeleton and contrast in these images is relatively insensitive to changes in the incident wavelength. Coomassie Brilliant Blue R250 images, on the other hand, result primarily from reflection from the lower surface of the cytoskeleton and the contrast of these images is sensitive to changes in incident wavelength dropping abruptly in the region of the transmission peak of the stain. From the different spectral sensitivities of the reflection images obtained and from differential interference effects at low and high illuminating numerical apertures, we conclude that the reflection images obtained using the first three stains result from modulation of the reflection by interference effects. In contrast, in the case of Coomassie Brilliant Blue R250 the resulting image originates mainly from selective reflection of wavelength near the absorption range of the dye.
Sublimation rates of ice in a cryo‐ultramicrotome
Authors: Zingsheim H. P. 
Published: August 2011

SUMMARYSublimation rates of ice in the nitrogen‐filled cryochamber of an ultramicrotome have been measured. The values are four to five orders of magnitude smaller than vacuum sublimation rates at the same temperatures. This is a consequence of the much shorter mean free path length of water molecules in nitrogen at atmospheric pressure, as compared to freeze drying under vacuum. The partial pressure at the phase boundary and gas diffusion and convection determine the rate of freeze drying. This has implications for section handling and the design of transfer equipment. Generally, it means that the danger of even partial dehydration of semi‐thick (0·5–1 μm) sections used mainly for X‐ray microanalysis is less serious than commonly assumed.
A simply constructed extreme‐tilt holder for the Philips eucentric goniometer stage
Authors: Chalcroft J. P. , Davey C. L. 
Published: August 2011

SUMMARYA simple single‐tilt holder has been constructed for the eucentric goniometer stage of the Philips EM 400. This holder is also compatible with the EM 300 series stages. The main improvements are as follows: unlimited tilt range using ‘25°’ polepiece configuration; secure gripping of all types of specimen grids by an easily operated micro‐clamp; elimination of shading effects by the holder at high tilt angles; and reduction of potential sources of astigmatism at high tilt angles.
A comparison of techniques for the removal of plural scattering in energy loss spectroscopy
Authors: Schattschneider P. , Sölkner G. 
Published: August 2011

SUMMARYInversion procedures for the recovery of inelastic single scattering probabilities from energy loss spectra are reviewed. It is shown that all three procedures in question (termed Fourier, convolution and matrix approach, respectively) yield unique solutions. Conditions of convergence are compared. From numerical and experimental considerations it is concluded that the matrix approach is to be preferred in general. Computer simulations, including effects of noise, confirm the excellent performance of the method.
Improvement of quantitation of biological X‐ray microanalysis
Authors: Harvey Diana M. R. , Flowers T. J. , Kent B. 
Published: August 2011

SUMMARYAbsolute measurements of elemental concentrations within thin biological samples are often made by reference to a series of standards which resemble the samples in chemical and physical properties and the linear relationship between (p‐b)/c and concentration. This principle requires that the chemical and physical properties of the matrix remain constant throughout a series of standards with different elemental contents and throughout different regions of the samples. Some of the changes undergone by specimens during X‐ray microanalysis, e.g. loss of elements or organic mass loss, are also influenced by the composition of the matrix. A simple empirical modification to the linear (p‐b)/c versus concentration relationship is presented to account for some of these effects and therefore improve quantitation of analyses.
Investigation of wear phenomena by microscopy
Authors: Buckley Donald H. 
Published: August 2011

SUMMARYThis paper discusses the various wear mechanisms involved in the loss of material from metallic and nonmetallic surfaces. The results presented indicate how various microscopy techniques used in conjunction with other analytical tools can assist in the elucidation of a wear mechanism. Microscopy is the single most important tool for the study of the wear of surfaces, to assess address inherent mechanisms of the material removal process.
The Ralph knife in practice
Authors: Helander Kerstin G. 
Published: August 2011

SUMMARYLong edge glass knives, ‘Ralph knives’, were produced in an LKB Histo KnifeMaker. The edge angles were measured by light microscopy; depending on the breaking conditions the angles varied between 12° and 58°, as measured close to the edge in the mid‐portion of the knives. Hackle marks were more common in the left portion of the edge than in the middle and right portions.Some of the knives were used for cutting sections from urinary bladder tumours embedded in paraffin or in glycol methacrylate. Following microtomy the sections were allowed to stretch on a water surface; this procedure resulted in an increased width of the plastic sections, whereas the paraffin sections were not affected. The compression of the whole sections averaged 15% in the paraffin sections and 11% in the plastic sections; in both cases the compression factors were positively correlated to the angle of the knife edge. Smaller compression factors were found for the cell nuclei in the embedded tissue.
Estimation of length and surface of anisotropic capillaries
Authors: Mattfeldt T. , Mall G. 
Published: August 2011

SUMMARYSurface density (SV) and length density (LV) of myocardial capillaries have hitherto been estimated from their profile boundary length (BA) and their numerical density (QA) on transverse sections by the simplifying assumptions of the Krogh model (perfectly anisotropic, straight, unbranched capillaries with constant cross‐sectional area). As the capillaries actually are partially anisotropic, curved, branching cylinders with variable cross‐sectional area, a geometrical bias arises from the model‐reality discrepancies. We have applied and compared two methods to overcome these inconsistencies: (1) estimation of LV and SV by a more realistic model (the Dimroth‐Watson distribution); (2) estimation of LV and SV from isotropic uniform random (IUR) sections. Twelve male Wistar rats were fixed by retrograde vascular perfusion. One pair of longitudinal and transverse sections, and six IUR sections per animal were selected at random from the left ventricular papillary muscles. Ultrathin sections were silver‐impregnated and studied by light microscopic morphometry. Nearly identical estimates of LV and SV were found by both methods. The model‐based estimation provides biologically meaningful anisotropy constants, but it presupposes knowledge of the anisotropy axis. The IUR method provides no measure of anisotropy, but it can be applied in tissues where the anisotropy axis is not known. Both methods are equally efficient and practically unbiased in SV estimation, but the model‐based estimation is far more efficient in LV estimation.
Problem oriented transmission electron microscopy
Authors: Stobbs W. M. 
Published: August 2011

SUMMARYThe relative advantages and disadvantages of the variety of transmission electron microscopical techniques which can be applied to materials science problems are argued by the examination of problems from a range of different fields. The further developments which will be needed before the full potential of some of the more modern approaches can be achieved are also discussed, as are the increasing uses of ‘edge‐on’ specimen preparation methods.
Photoelectron emission: images and spectra
Authors: Turner D. W. , Plummer I. R. , Porter H. Q. 
Published: August 2011

SUMMARYWe give an account of the development of electron emission imaging and the photoelectron emission process. We then describe a particular combination of photoelectron emission microscopy and photoelectron spectroscopy which we call photoelectron spectromicroscopy. This is achieved using a very strong, divergent magnetic field to define electron trajectories without the use of electron optical focusing. It is thus possible to produce electron images of the surfaces of three‐dimensional objects using low energy photoelectrons in which the image contrast is dependent upon, among other things, the yield and energy distribution functions. The various image contrast mechanisms which apply are outlined with illustrative examples. Techniques for energy analysis of the photoelectron image are described and examples of the photoelectron spectra of different regions of the surface of an object presented. Electron images produced by metastable atoms and slow ions are also discussed. The use of the magnetic field introduces the opportunity for a number of novel techniques which will be described.
Surface structure imaging by electron microscopy
Authors: Takayanagi K. 
Published: August 2011

SUMMARYReconstructed structures at monolayer level on ‘clean and well‐defined’ surfaces can be imaged by transmission electron microscopy in fixed beam illumination mode. The specimens are cleaned in‐situ in the electron microscope in ultra high vacuum. Transmission electron diffraction pattern intensities can give useful information for determining the surface unit cell size of the structure, and the atom positions (geometric arrangement of atoms in the unit cell) especially those with a large unit cell, since the diffraction intensities are interpreted kinematically. High resolution surface imaging which gives directly the atom positions is tested here for a single monolayer terrace on Ag (111) surface. The result shows the value of HREM for studies of surface crystallography.
Moment correction coefficients in the analysis of a photographically recorded distribution of spherical particles
Authors: Horálek Vratislav 
Published: August 2011

SUMMARYA model is proposed for determining the relationship between the spatial distribution of actual diameters of spherical particles and of the distribution of diameters of these particles recorded onto a photograph. In this case, in general, the observed diameter is not identical with the actual one, as in orthogonal projection, but is reduced in accordance with geometricoptical theory. The corresponding moment correction coefficients are derived.
Simulation of atomic image profiles in dark field electron microscopy
Authors: Korn Alex P. 
Published: August 2011

SUMMARYOne‐dimensional atomic image profiles have been calculated for the fixed beam dark field mode of electron microscopy. They were generated by applying the lens‐related phase shifts to the complex electron‐atom scattering amplitude function for mercury. The dark field geometries simulated were beam stop, aperture shift, beam tilt and combination beam tilt‐aperture shift. It was shown that the correct defocus is 20–30 nm. However, using an aperture incompatible with the resolution limit dictated by the lens related phase shift function leads to an apparent optimum defocus that, while yielding maximum intensity and sharpness, increases the chance of interference artefacts. Provided that a compatible aperture is used, dark field in a beam tilt geometry does not create severe asymmetries in the profile nor a change in the resolution as compared to the beam stop method.
A centrifugation method for standardized sedimentation of mononuclear human blood cells on glass for scanning electron microscopy
Authors: Wouters C. H. , Hesseling S. , Daems W. Th. , Ploem J. S. 
Published: August 2011

SUMMARYA centrifugation method for depositing cells on cover‐glasses for scanning electron microscopy (SEM) is described. This centrifugation procedure provides a defined and standardized morphology of mononuclear cells from human blood. The method circumvents the highly variable flattening of some blood cells such as monocytes, observed with some methods. The SEM images show fine morphological surface details indicating a well‐preserved cell morphology. The cell recovery of the method is sufficiently high and the lymphocyte‐monocyte ratio in centrifugation preparations was found identical to the ratio in control smear preparations.