bluuebunny/crossref_metadata_2025 huggingface dataset:
Prospects for improvement in EDX microanalysis
Authors: Statham P. J.
Published: August 2011

There is still considerable room for improvement in the EDX technique, particularly for the analysis of thin samples in transmission electron microscopes. Further research is required to characterize changes which are introduced during specimen preparation and a technique for mass thickness determination has to be established which is both accurate and convenient to implement. Since detector efficiency is difficult to predict at low energies, a suitable standard sample needs to be found which produces X‐ray peaks suitable for establishing fixed points on the detector efficiency curve. With current technology, there are several instrumental improvements which can be realized, most of which centre around the use of time‐variant pulse‐processing circuitry and reduction of electronic noise. Problems of overload with high‐voltage microscopes can be minimized, resolution improved and pile‐up rejection made more effective so that higher data rates can be accommodated. With the beryllium vacuum window removed, detection of boron is possible provided the influence of electronic noise is minimized but further investigation is still required into the physics of interactions in the first 100 nm layer of the detector.
Procedures for focusing, stigmating and alignment in high resolution electron microscopy
Authors: Saxton W. O. , Smith David J. , Erasmus S. J.
Published: August 2011

Several different approaches to the alignment, stigmating and focusing of a high resolution electron microscope are evaluated theoretically and experimentally. Ambiguities in the interpretation of diffractograms are pointed out which make it necessary to explore a range of incident beam directions before the correct alignment can be established. The variation of image contrast with the imaging conditions is examined in detail, and its global minimization is shown to be a reliable criteria for adjustment of all parameters. Recommendations are made as to the best procedures to adopt in various circumstances, and a computer‐controlled procedure based on the image contrast is described which sets all parameters automatically in less than a minute.
A high‐resolution electron microscopic study of defects in sodium β′″‐alumina
Authors: Hull R. , Smith David J. , Humphreys C. J.
Published: August 2011

A high‐resolution electron‐microscopic study of sodium β′″‐alumina, a polytype of the more‐widely‐studied sodium β‐ and β″‐alumina, has been undertaken using the 600 kV instrument at Cambridge University. Images revealed the loss of sodium‐containing planes, which had caused crystals to collapse and shear into defect layers. A model for the structure of these defects is proposed, based on the use of computed images and by comparison with high‐resolution images of silver β″‐alumina.
The relative accuracy of axial and non‐axial methods for the measurement of lattice spacings
Authors: Hall D. J. , Self P. G. , Stobbs W. M.
Published: August 2011

The various different transmission electron microscopical techniques available for the measurement of lattice spacings are discussed, and the limited situations under which lattice fringe spacing measurement is the most appropriate approach are considered. The relative accuracy of measurements on images obtained under axial and non‐axial conditions is further considered, and the generally greater accuracy of the latter technique demonstrated. Further results on the use of the method for the measurement of the carbon content of retained austenite in a dual phase steel are included.
Optimizing the cooling block for the quick freeze method
Authors: Bald W. B.
Published: August 2011

It is important for future ultrastructural preservation studies to freeze biological specimens as rapidly as possible. Finite element numerical techniques have been used to compare different cooling block materials used in the quick freeze ‘slamming’ method. It is concluded that a pure silver block at an optimum initial temperature of about 15.6 K will produce the quickest cooling and will give rates approximately 50% higher than if the block were initially cooled to 4.2 K.

A copper block will produce the fastest cooling rates when the block is initially at liquid nitrogen temperature of 77.3 K provided the section being studied is taken no more than about 30 μm from the specimen‐block interface.

Composite metal blocks can further reduce the total specimen cooling time compared to a mono‐block at the same initial temperature but the cooling rate near the interface will be slower.

Future methods for specifying cooling rates within thin biological samples should be standardized and must be based on a combination of finite element numerical analysis and the measured temperature at the rear surface of the sample. Thermal contact resistance between cooling block and specimen and between specimen and the rear face temperature sensor must be minimal.
On the preparation of specimens from multifilamentary Nb3Sn superconducting wires for transmission electron microscopy
Authors: Hascicek Y. S. , Nourbakhsh S. , Goringe M. J.
Published: August 2011

A set of techniques for preparing transmission electron microscope specimens from sections of thin (≤ 1 mm overall diam.) multifilamentary wires (filaments being approximately 5 μm diam.) are described. Results illustrating the successful uniform thinning of the several phases present in ‘bronze‐route’ Nb3Sn are shown.
Radiation damage to lyophilized mineral solutions during electron probe analysis: quantitative study of chlorine loss as a function of beam current‐density and sample mass‐thickness
Authors: Roy Andre F. Le , Roinel Nicole
Published: August 2011

The quantitative effects of beam current‐density and sample mass‐thickness on the loss of chlorine which occurs from lyophilized solutes of micro‐droplets of mineral salt solutions irradiated in an electron probe analyser were studied. Results are reported for chlorine loss from lyophilized deposits with mass‐thickness varying between 5 and 50 mg mm−2 for NaCl salts and 5 and 80 mg mm−2 for KCl salts. Electron accelerating voltage was kept constant at 15 kV. The range of beam current‐density (I/S, current/sample surface area) was from 0.1 to 1.5 A mm−2. Samples were irradiated for 1200 s. The results show that under some conditions there is a period of stable chlorine signal before chlorine loss occurs. This is observed between 0.1 and 1 A mm−2, for a period which can last several hundred seconds depending on beam current‐density and sample mass‐thickness. For each value of I/S, however, no stable chlorine signal can be observed for samples whose mass‐thickness exceeds a value negatively correlated with I/S. The curves of decrease of characteristic chlorine X‐ray signal (expressed as per cent of count rate in the initial counting interval) versus irradiation time can be fitted by the sum of two exponentials with half lives T1 and T2. In NaCl, T1 and T2 values are highly correlated with I/S but not with mass‐thickness. In KCl, T1 is correlated only with mass‐thickness and T2 only with I/S. Mixing plasma with mineral solutions prevents chlorine loss.
Staining plastic sections
Authors: Horobin Richard W.
Published: August 2011

Many of the difficulties of staining plastic embedded tissues for light and electron microscopy derive from physical exclusion of hydrophilic staining reagents by hydrophobic embedding media. Structures which stain most intensely with hydrophilic reagents usually contain less hydrophobic plastic than do non‐staining structures. Such incomplete infiltration is apparently caused by exclusion of viscous, hydrophobic monomers by physically dense and/or well hydrated tissue elements. In keeping with this, generalized staining of tissues embedded in hydrophobic media does occur when hydrophobic reagents are used. Staining of plastic‐free structures with single hydrophilic reagents or with sequences of such reagents, is, however, largely rate‐controlled.

The surprising similarity of hydrophilic and hydrophobic plastic embedding media is discussed.

Limits of this simple model are explored, with a consideration of the roles of fixative and of monomer‐tissue reactions.
Exocrine glands and protein secretion: a stereological viewpoint
Authors: Cope G. H.
Published: August 2011

The exocrine pancreas and the parotid salivary gland have been widely used as models for studying the synthesis, intracellular transport and discharge of exportable proteins. This article briefly reviews quantitative morphological (stereological) studies which have been made of these glands and assesses their contribution to our understanding of the secretory process. A general stereological profile of these glands is presented and the way in which their morphology changes during development is outlined. Detailed consideration is given to the granule population of the cells, particularly the way in which granules are formed and discharged as a result of secretory stimuli. The membrane content of secretory cells and membrane dynamics during the secretory cycle are also examined. Throughout, the emphasis is placed on the interpretation of stereological data rather than on the methods themselves.
The microvascular cast as a three‐dimensional tissue skeleton: visualization of rapid morphological changes in tissues of the rat uterus
Authors: Rogers P. A. W. , Gannon B. J.
Published: August 2011

A new interpretation of microvascular corrosion casting is described using examples from casts of the rat uterus taken during the oestrous cycle and early pregnancy. The casts are considered as representing a three‐dimensional model of the tissue vascular space; this characteristic model or tissue skeleton is used to demonstrate transient morphological changes that may be difficult to visualize by other techniques, that may be obscured by other structures, or destroyed by conventional aldehyde fixation procedures. This new application, when supplemented by conventional histology to determine vessel distribution within the tissue and to confirm observations first made by casting, provides a technique for visualizing three‐dimensional morphological changes in tissues that is accurate, relatively simple and far more rapid than the laborious method of histological serial sectioning and three‐dimensional tissue reconstruction.
Quantitative serial sectioning analysis: preview
Authors: DeHoff R. T.
Published: August 2011

Quantitative serial sectioning analysis provides all of the geometric information that is available from ordinary stereological analysis. In addition, it circumvents the weaknesses inherent in geometric models that are used to estimate distribution functions and topological properties. It further makes accessible some geometric aspects of microstructures that are not available stereologically, even with model assumptions. At the present state of the art it requires a prodigious effort to prepare and analyse a single sample from a single specimen. However, the current generation of image analysing computers already has the capability for automating data collection and analysis, and there is reasonable potential for automating the sample preparation procedure. Quantitative serial sectioning analysis would render obsolete all of the elegant geometrical probability arguments of stereology. Is it the wave of the future?
Distribution‐free estimation of sphere size distributions from slabs showing overprojection and truncation, with a review of previous methods
Authors: Cruz‐Orive L. M.
Published: August 2011

A distribution‐free method is presented for unfolding the size distribution of an aggregate of disjoint opaque spherical particles in a translucent medium, from the circular profiles observed in the orthogonal projection of sections of a certain thickness through the medium. This situation pertains especially to light and transmission electron microscopy.

The model accounts for overprojection (or ‘Holmes effect’) due to section thickness, and for two forms of truncation (or ‘missing profiles’ mechanisms), simultaneously. The profile data may be grouped into an arbitrary class system, chosen by the user, and the procedure can be programmed in a medium‐size desk calculator.

In order to incorporate the above features, however, we had to choose a finite‐difference unfolding algorithm, the advantages and disadvantages of which are discussed early in the paper in the context of the main alternative unfolding procedures hitherto available.

The performance of the method is tested against three sets of real data previously analysed by a maximum likelihood method (Keidinget al., 1972).
Unbiased linear property estimation for spheres, from sections exhibiting overprojection and truncation
Authors: Clarke K. R. , Moore M. N.
Published: August 2011

In the biological sciences, stereological techniques are frequently used to infer changes in structural parameters (volume fraction, for example) between samples from different populations or subject to differing treatment regimes. Non‐homogeneity of these parameters is virtually guaranteed, both between experimental animals and within the organ under consideration. A two‐stage strategy is then desirable, the first stage involving unbiased estimation of the required parameter, separately for each experimental unit, the latter being defined as a subset of the organ for which homogeneity can reasonably be assumed. In the second stage, these point estimates are used as data inputs to a hierarchical analysis of variance, to distinguish treatment effects from variability between animals, for example.

Techniques are therefore required for unbiased estimation of parameters from potentially small numbers of sample profiles. This paper derives unbiased estimates of linear properties in one special case—the sampling of spherical particles by transmission microscopy, when the section thickness is not negligible and the resulting circular profiles are subject to lower truncation. The derivation uses the general integral equation formulation of Nicholson (1970); the resulting formulae are simplified, algebraically, and their efficient computation discussed. Bias arising from variability in slice thickness is shown to be negligible in typical cases.

The strategy is illustrated for data examining the effects, on the secondary lysosomes in the digestive cells, of exposure of the common mussel to hydrocarbons. Prolonged exposure, at 30 μg 1−1 total oil‐derived hydrocarbons, is seen to increase the average volume of a lysosome, and the volume fraction that lysosomes occupy, but to reduce their number.
Morphometric study of the development of Purkinje cell dendritic trees in the mouse using vertex analysis
Authors: Sadler Martin , Berry Martin
Published: August 2011

Vertices are the points in an arborescence which interconnect segments and comprise terminal or pendant vertices (Vp), nodal or branching points and the root point. Branching points may be dichotomous (Vd) or trichomtomous (Vt), etc., and are subdivided into distinct two‐dimensional topological entities according to the number of terminal vertices they drain, i.e. Vds comprise primary vertices (Va), connecting two Vps; secondary vertices (Vb), connecting one Vp and one Vd or one Vt; and tertiary vertices (Vc), connecting either two Vds, two Vts or one Vt and one Vd. The four types of Vt (Va‘, Vb’, Vc‘, Vd’) similarly connect three, two, one and zero Vps respectively. Each Vt may be transformed into two Vds thus, Va' = Va + Vb; Vb’ = Va/3 + 4Vb/3 + Vc/3; Vc' = Vb + Vc and Vd’ = 2Vc. Analysis proceeds by transforming mixed trees containing varying proportions of Vds and Vts into entirely dichotomous branching structures. The topology is then defined by the Va Vb ratio which has a unique value according to the mode of growth and the frequency of Vts.

Vertices are ordered by a centrifugal technique. The frequency distribution of vertices of different order allow the changes in growth characteristics and in remodelling to be detected within particular regions of the tree. Metrical parameters are readily incorporated into the analysis since all vertices are interconnected by segments of finite length and are given the same order magnitude as the vertex they drain.

The analytical capabilities of the method are exemplified by its application to the study of growth and plasticity in the dendritic trees of Purkinje cells in the mouse. Growth is defined in metrical and topological terms and sites of reorganization within the mature tree are identified.
Vascular smooth muscle orientation in curved branches and bifurcations of human cerebral arteries
Authors: Walmsley James G.
Published: August 2011

Two approaches were developed for determining reference axes and positions associated with bending tubular arteries and bifurcations from the human middle cerebral branching system. In the region of the bifurcation the orientation of groups of two‐dimensional nuclear vectors was determined by the method of roses and average alignment. The reference axes and positions for these groups were determined from physical reconstructions of two bifurcations. The overall pattern in the bifurcation region was found to be random but there were significant differences between group orientations. The three‐dimensional arterial direction vectors for three sections, from the bending arteries of one bifurcation, were determined. By taking the dot product of the three‐dimensional nuclear vectors and these direction vectors, the pitch of individual nuclei was determined. The average pitch was 2.45° ± 3.20 (SD for N = 8) with the largest mean pitch (6.14°) in the branch with the greatest curvature. Possible use of the three‐dimensional approach for determination of smooth muscle orientation at bifurcations is discussed in general terms.
Introduction to the microscopy of erosion
Authors: Hutchings M.
Published: August 2011

Erosion of materials by the impact of small solid particles, by the impact of liquid drops and by cavitation in a liquid is discussed. Erosion arising from these three sources is described, terminology is defined, and the methods available for erosion testing in the laboratory are reviewed. A brief discussion is presented of the microscopical techniques which have been used to study erosion, and some of their advantages and drawbacks are outlined.
Microstructural studies of the temperature‐dependence of deformation structures around hardness indentations in ceramics
Authors: Naylor M. G. S. , Page T. F.
Published: August 2011

Various light microscopy and SEM techniques have been used to study the temperature dependence of deformation structures around hardness indentations in highly brittle ceramics (including single crystals of silicon and silicon carbide and polycrystalline forms cf SiC, Si3N4 and B4C). Nomarski differential interferometry has enabled slip steps to be resolved around high‐temperature indentations, allowing identification of the dominant slip systems and measurement of the extent of surface plasticity as a function of temperature. The occurrence of indentation fracture as a function of both temperature and specimen microstructure was studied by SEM methods (including stereo imaging), Nomarski differential interferometry and polarized reflection light microscopy. Generally, radial and lateral crack sizes increased with increasing temperature, due to increasing residual stresses around indentations caused by increasing indentation plasticity. Examples of microstructural control of crack paths are given for various single crystal and polycrystalline materials.
Current uses of fluorescence microscopy in coal petrology
Authors: Crelling John C.
Published: August 2011

Fluorescence analysis of the liptinite maceral content of various U.S. coal seams has shown that these macerals are consistently under‐counted in conventional white‐light analysis. Fluorescence analysis revealed a greater variety of liptinite macerals as well as a large amount of fluorescing vitrinite in all of the coals studied. However, pseudovitrinite was not observed to fluoresce. Textures and structures not visible in normal viewing are also seen in fluorescence analysis. Quantitative spectral analysis of single coals has shown that most liptinite macerals can be both petrographically and statistically separated on the basis of fluorescence parameters, with the wavelength at maximum intensity and the red/green quotient being the most significant. In coals of the Illinois Basin, one or more forms of fluorinite, resinite, sporinite and cutinite can be distinguished.

As the rank of the coal increases, the fluorescence intensity decreases and the spectral maxima shift toward longer wavelengths. In some Rocky Mountain coals these effects occur at a much lower rank (<0.85% reflectance) than in the coals of the Appalachian Basin. Similar changes in fluorescence properties have also been found in naturally weathered coals. Fluorescence analysis of resinite‐rich Rocky Mountain coals has shown that two major forms of resinite are present; one is the ‘normal’ resinite, and the other is a much more abundant fissure‐filling resinite that carries coal xenoliths, shows flow structure, and has a spectral maximum well below that of the ‘normal’ resinite.
Optical microscopy of carbonaceous solid residues from coal hydrogenation: a classification
Authors: Ng Nancy
Published: August 2011

A 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

The 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

An 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

A 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.
High‐speed computation techniques for the simulation of high resolution electron micrographs
Authors: Dyck D. Van
Published: August 2011

A survey will be given of the theoretical and practical progress that has been made thus far in the field of high‐resolution image computations especially with respect to computational speed and memory requirements. Attention is paid to some problems that have not completely been solved yet and some future prospects are outlined.
Mica: A convenient support for biological SEM specimens in a TEMSCAN microscope
Authors: Johansen B. V. , Namork Ellen , Bukholm Geir
Published: August 2011

Mica 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

Automated 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

The 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

It 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

Elements 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

Melamine‐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.
Residual gas analysis in a SEM
Authors: Marshall A. T.
Published: August 2011

It is shown that a clean (hydrocarbon partial pressure 0·1 times 10−6 Pa) high vacuum (total pressure 5 times 10−5 Pa) is obtainable in the specimen chamber of a scanning electron microscope by relatively inexpensive means.
An autoradiographic method for determining nutrient competition between leaf epiphytes and plant pathogens
Authors: Edwards M. C. , Blakeman J. P.
Published: August 2011

A 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

A 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

As 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

Quantitative 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

The 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

Surface 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

Sublimation 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

A 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

Inversion 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

Absolute 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

This 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

Long 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

Surface 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

The 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

We 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

Reconstructed 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

A 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

One‐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

A 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.
Profile boundary length can be overestimated by as much as 41% when using a digitizer tablet
Authors: Cornelisse J. T. W. A. , van den Berg T. J. T. P.
Published: August 2011

In length measurements on digitizer systems a considerable overestimation of the actual value can occur due to improper algorithms by as much as 41%. The effect of cursor speed on this phenomenon is discussed. Possible algorithms are presented to diminish the problem. We used a two‐way filtering algorithm with a practical error of between 0.1% and 0.4%.
A design‐based proof of Wicksell's integral equation
Authors: Jensen E. B.
Published: August 2011

Wicksell's integral equation (1925) describes, for an aggregate of spherical particles, the relation between the distribution of sphere diameters and the distribution of diameters of circular profiles observed on a planar section. Usually, this integral equation is proved under the assumption that the particle aggregate is a realization of a stationary stochastic process while the position of the planar probe is allowed to be arbitrary. In this note, it is shown that, under the alternative assumption that diameters of circular profiles are sampled by means of a planar FUR (fixed orientation uniform random) probe, Wicksell's equation holds for a deterministic aggregate of spherical particles with arbitrary positions and sizes. Since the proof is based on the randomness generated by the sampling (the design), the proof may be characterized as design‐based. It can thus be concluded that Wicksell's equation may be applied to any aggregate of spherical particles if diameters are sampled by means of random (FUR) planar probes.