bluuebunny/crossref_metadata_2025_split huggingface dataset:
Measurements of the thickness of a carbon film evaporated on to biological samples
Authors: Fakhouri H. G. , Dyson N. A. 
Published: August 2011

SUMMARYThe energy loss in elastically scattered α‐particles is used to measure the thickness of carbon films used for coating biological samples to prevent surface charging. The lighter mass film on the substrate acts as an absorber which imposes an energy shift on the substrate signal. A relation is achieved between the energy shift and the thickness of the film. The calculation has been tested by measuring the energy shift for a series of films the thickness of which was determined directly by weighing. Good agreement was found, with small deviations at greater thicknesses.
Application of the Cavalieri principle and vertical sections method to lung: estimation of volume and pleural surface area
Authors: Michel René P. , Cruz‐Orive Luis M. 
Published: August 2011

SUMMARYA practical methodology is proposed for the stereological analysis of lung and other organs using recently developed unbiased procedures. This study concentrates on the unbiased estimation of lung volume using Cavalieri's principle compared with the fluid displacement method and measurement of pleural surface area using vertical sections. Furthermore, the proposed design, in addition to the sampling of extensive slices for the initial steps, also allows sampling of vertical sections for light and electron‐microscopical stereology.The procedures are described in detail by reference to biological data from the right lungs of four rabbits. We found excellent agreement between estimates of lung volume measured with Cavalieri's principle and those measured by fluid displacement. Pertinent details of the statistical analysis of the sources of variation (namely biological, systematic sectioning and point‐counting variation) are given in an appendix.
Improved algorithms for automatic bone histomorphometry on a numerized image analysis system
Authors: Beigbeder M. , Chappard D. , Alexandre C. , Vico L. , Palle S. , Riffat G. 
Published: August 2011

SUMMARYQuantitative histological methods have proved to be the most effective methods in bone disease research. Faster and more accurate techniques are currently needed. We have developed a simple digitized image analysis system which allows accurate measurements of trabecular bone mass. The algorithm is based on the 'four‐connected sets' mathematical theory. Given a numerized image displayed by a CCD camera, the algorithm recognizes all possible four‐connected sets and provides area measurements. The first procedure automatically eliminates small, irrelevant profiles (wrinkles, cell nuclei, etc.) while larger profiles are erased interactively. The second procedure similarly erases the artefactual defects within the trabecule (artefactual cracks or empty osteocytic lacunae). The method was shown to be very accurate and time‐saving.
Automated extraction of regular spot arrays from electron diffraction images*
Authors: Bright D. S. , Steel E. B. 
Published: August 2011

SUMMARYIn order to analyse agglomerate particles, we have developed a computer method that automates the analysis of spots in electron diffraction patterns. The method isolates the zone axis diffraction pattern in a polycrystalline diffraction image by isolating the spots from other features of the image and then by selecting the spots that belong to a regular array. The method gives the basis vectors for the array which can then be used to identify the particle by comparison with standard diffraction data.
Random approximation of convex sets*
Authors: Schneider Rolf 
Published: August 2011

SUMMARYWe consider convex hulls of independent, identically distributed random points, the distribution of which depends in some way on a given convex body. In the first part, we study an i. i. d. sequence of points on the boundary of a smooth convex body K in the plane and assume that their distribution has a positive continuous density with respect to arc length. The rate of the almost sure convergence of the area, perimeter and Hausdorff distance from K of the successive convex hulls of the random points towards the corresponding values of K is investigated. Also random polygons generated by intersecting random supporting halfplanes of K are considered.The second part gives a survey of convex hulls of random points in d‐dimensional convex bodies, with special emphasis on the asymptotic behaviour of the expectations of some geometrically interesting functionals.
The expected volume of a random polytope in a ball*
Authors: Affentranger Fernando 
Published: August 2011

SUMMARYFor any convex body K in d‐dimensional Euclidean space Ed(d≥2) and for integers n and i, n ≥ d + 1,1 ≤ i ≤ n, let V(d)n‐ii(K) be the expected volume of the convex hull Hn‐i, i of n independent random points, of which n‐i are uniformly distributed in the interior, the other i on the boundary of K. We develop an integral formula for V(d)n‐i, i(K) for the case that K is a d‐dimensional unit ball by considering an adequate decomposition of V(d)n‐i, i into d‐dimensional simplices. To solve the important case i = 0, that is the case in which all points are chosen at random from the interior of Bd, we require in addition Crofton's theorem on mean values. We illustrate the usefulness of our results by treating some special cases and by giving numerical values for the planar and the three‐dimensional cases.
Characteristic X‐ray production cross‐sections for standardless elemental analysis in EDX
Authors: Paterson J. H. , Chapman J. N. , Nicholson W. A. P. , Titchmarsh J. M. 
Published: August 2011

SUMMARYMeasurements have been made of cross‐sections for the production of X‐rays following ionization of the K‐shell by fast electrons for a range of elements and incident electron energies. These data have been fitted to a simple functional expression for the ionization cross‐section. This model, the Bethe model, includes two empirical fitting parameters. We found that a single universal pair of parameters may be used to allow the model to predict cross‐sections with a mean error of ∼ 7% and a maximum error of ∼ 20% over the range of conditions considered. A relativistic form of the Bethe model yields a small improvement in accuracy for higher incident electron energies.Measurements have also been made of L‐shell production cross‐sections. It is expected that the Bethe model will apply also to the L‐shell. Comparison of experimental and calculated K/L‐shell cross‐section ratios generally supports this, but uncertainties in the values in the literature for L‐shell fluorescence yields precludes the drawing of any firm conclusions here.
Quantitative study of spurious X‐ray production in thin film microanalysis
Authors: Glas Frank 
Published: August 2011

SUMMARYWhen X‐ray microanalysis is performed in a TEM on a thin area of a specimen, some a priori indistinguishable spurious photons produced in other zones of this specimen are always recorded. Several mechanisms contribute to this production. For instance, some Bremsstrahlung and characteristic photons are generated by secondary and Auger electrons; a conservative upper bound to this particular contribution is calculated for several materials, and the present approach is compared to the Monte Carlo simulation. It is then shown that, in special test‐specimens, the total extraneous contribution of the thick parts of the specimen to the spectra recorded in a thin zone can be measured; different instruments may now be compared in this respect. In the HB5 STEM, this total contribution remains low; its main cause is beam scattering in the specimen, not before it. Finally, an experimental procedure for estimating this bulk contribution in any specimen of interest is proposed. Calculations and experiments are illustrated for the case of gallium arsenide.
Processing of secondary ion microscope images: an example of application to the thyroid
Authors: Cavellier J. F. , Berry J. P. , Escaig F. , Boumati P. , Gaume P. 
Published: August 2011

SUMMARYIon microscopy is a microanalytical method by which one can obtain distribution images of any chemical element with isotope discrimination even at very low local concentrations, in successive slices of the specimen. These images are obtained at the price of progressive erosion of the specimen, so that the analysis may not be replayed and it is necessary to record the maximum amount of information during specimen erosion.We present an improvement of this method using a highly sensitive camera connected to a video analog‐digital converter. The images are acquired and digitized on line and may be processed by an image computer.We illustrate the technique described with an application of ion microscopy that is made possible by digital recording and processing of images. This application concerns the precise comparison of iodine isotopes and phosphorus distributions in sections of the thyroid gland of rats which were submitted to an iodine‐deficient diet followed by an injection of 129 I.
Digital image analysis of two‐dimensional Na,K‐ATPase crystals: dissimilarity between pump units
Authors: Beall Harry C. , Hastings David F. , Ting‐Beall H. P. 
Published: August 2011

SUMMARYTwo‐dimensional crystals of purified Na,K‐ATPase were induced by treatment with phospholipase‐A2 and vanadate. The negatively stained crystals were imaged by electron microscopy and analysed by digital image processing. Two‐dimensional averaged projections of the crystals were calculated by the technique of correlation analysis, utilizing SPIDER (System for Processing of Image Data in Electron microscopy and Related fields) image processing software. The calculated dimensions of the unit cell were found to be 13.3 × 4.59 nm with included angle of 98°, comparable to those reported by others. However, the two protomers of the unit cell were found always to be dissimilar in shape and in orientation. All protomers of one side of the dimer ribbon had a triangular outline, and all protomers of the opposing side had a comma shape. This dissimilarity could be explained by two orientations of identical protomers: one orientation for one side of the dimer ribbon, and another orientation for the protomers of the opposing side of the ribbon. An alternative explanation is that the protomers of one side of the dimer ribbon are actually in a conformation different from that of the protomers of the opposing side of the ribbon.
Theoretical study of the ultimate resolution of SEM
Authors: Ze‐Jun Ding , Shimizu Ryuichi 
Published: August 2011

SUMMARYThis work aims to clarify the problem of why the ultimate resolution assessed experimentally from the observation of 0.8 nm separation of Au‐Pd fine particles is beyond the theoretical resolution limit of scanning electron microscopy (SEM). The correlation between the spatial distribution of secondary electrons on a sample surface and the resolution estimated by edge‐to‐edge separation in SEM was studied by a Monte Carlo simulation with secondary electron generation included. The result clearly indicates that the edge‐to‐edge separation can extend beyond the theoretical ultimate resolution, particularly by image processing for contrast expansion and by improving the signal to noise ratio (S/N).
Materials analysis with a position‐sensitive atom probe
Authors: Cerezo A. , Godfrey T. J. , Grovenor C. R. M. , Hetherington M. G. , Hoyley R. M. , Jakubovics J. P. , Liddle J. A. , Smith G. D. W. , Worrall G. M. 
Published: August 2011

SUMMARYA position‐sensitive detector has been combined with time‐of‐flight mass spectrometry in the atom probe field‐ion microscope to yield a system in which both chemical identity and spatial information are obtained for individual ions field‐evaporated from the specimen surface. This allows the variations in composition originally present in the sample to be reconstructed in 3‐D with sub‐nanometre resolution. The prototype position‐sensitive atom probe is being used to study phase chemistry in a number of metallurgical alloys, including accurate composition determination of 1–2 nm Cu‐rich precipitates formed in Fe–1.3% Cu–1.4%Ni aged to peak hardness. Other applications of the position‐sensitive atom probe (POSAP) include the analysis of surface layers on superconductors and atom probe studies of semiconductor multiple quantum wells. These initial applications of the instrument are reported, and the limitations and intended improvements to the instrument are discussed.
Tomographic reconstruction from energy‐filtered images of thick biological sections
Authors: Olins Ada L. , Olins Donald E. , Levy Henri A. , Margle Stephen M. , Tinnel Ed P. , Durfee Richard C. 
Published: August 2011

SUMMARYEnergy filtration makes it possible to image a ∼0.5 μm biological section at 80 kV in the electron microscope. Based on spectra taken at different tilt angles, we chose the most probable energy loss, ΔEp ± 10 eV for each tilt angle, as the imaging energy window. A complete tilt series from + 60° to −60° at 2.5° intervals was collected on the Zeiss EM902 and used in a tomographic reconstruction of transcriptionally active chromatin in the Balbiani ring of Chironomus tentans.
A hot stage SEM for gas‐solid reaction studies
Authors: Brown A. M. , Hill M. P. 
Published: August 2011

An ultra‐high vacuum, field emission source, scanning electron microscope (SEM) equipped with a gas cell to permit the in situ study of high temperature gas‐solid reactions is described.High resolution SEM (50 Å) and scanning Auger microscopy (300 Å resolution) can be carried out at specimen temperatures up to 1000°C. Reaction products and processes can be imaged continuously in the SEM at pressures up to ∼0.2 Torr. Gas pressures up to 50 Torr are possible but with some limitations.Methods of specimen mounting, problems of temperature measurement, and the microscope performance at high specimen temperatures and gas pressures are discussed. Examples of metal surface preparation and impurity segregation under high temperature annealing and gas exposure are reported.
A dynamic SEM study of solution‐precipitation processes in carbon deposition
Authors: Brown A. M. , Hill M. P. 
Published: August 2011

In situ high resolution scanning electron microscopy (SEM) has been used to study carbon deposition processes occurring in the Fe/CH4 reaction at temperatures of 620–850°C.The morphology of deposits formed by carbon dissolution and precipitation processes has been investigated. The development of particulate‐type deposits has been examined. These are associated with the enhancement of catalytic activity of transition metals and the break‐up of the metal structure as the deposition reaction progresses. A mobile Fe‐C phase has been observed that can explain how complex carbon morphologies develop.
Contrast in the electron spectroscopic imaging mode of a TEM. I. Influence of zero‐loss filtering on scattering contrast
Authors: Reimer L. , Ross‐Messemer M. 
Published: August 2011

SUMMARYMeasured values of the transmission of amorphous films as a function of the objective aperture and film thickness can be described by a single‐scattering theory for unfiltered and zero‐loss filtered images in the electron spectroscopic imaging mode of a transmission electron microscope. The theory can be applied to estimate the gain of contrast by zero‐loss filtering for specimen structures larger and smaller than the chromatic aberration disc.
Defocus modelling correction for wavelength dispersive digital compositional mapping with the electron microprobe
Authors: Marinenko R. B. , Myklebust R. L. , Bright D. S. , Newbury D. E. 
Published: August 2011

SUMMARYA new, simplified procedure for correcting the defocusing observed in low‐magnification digital maps obtained with the electron microprobe using wavelength spectrometers is described. This procedure uses a wavelength scan of the analysed element and the geometric relationship between the specimen and the diffracting crystal to calculate a model of a standard map, which is subsequently used in the quantification of each pixel of the unknown map. The results of this new procedure are compared with the earlier method of using an experimentally obtained standard map.
Patronage and publishing: Journals of microscopy 1839–1989
Authors: Brock W. H. 
Published: August 2011

SUMMARYThe development of microscopical journals in the United Kingdom, America and in France and Germany since the 1840s is reviewed. Particular attention is paid to the periodicals issued by the Royal Microscopical Society, the Quekett Club and the Postal Microscopical Club. Conclusions are drawn concerning the roles of societies and commercial publishers as patrons of scientific research.
The social history of the microscope
Authors: Bennett J. A. 
Published: August 2011

SUMMARYThe motivation for elevating the microscope from an optical toy to an optical instrument derived from the mid‐seventeenth‐century belief in the subliminal, mechanical organization of the natural world. The microscope failed to reveal this corpuscular realm, but its success in popular instruction and entertainment secured its place in the growing amateur pursuit of natural philosophy in the eighteenth century. In the early nineteenth century the development of the achromatic objective gave the microscope a new technical potential, a potential exploited to its full extent by the members of the Microscopical Society of London. The British makers were very successfully engaged with advanced technical development in the mid‐century, but saw their dominance of the market decline with the growing demand for large numbers of instruments aimed at professional applications.
Landmarks in biological light microscopy
Authors: Bradbury S. 
Published: August 2011

SUMMARYThe pioneering seventeenth‐century work of Hooke (using the compound microscope) and Leeuwenhoek (using the simple microscope) was followed in the eighteenth century by a period of comparative stagnation until the early nineteenth‐century work of Lister (who evolved the principle of aplanatic focal points in lens design). The founding of the Microscopical Society of London in 1839 reflected the increasing importance of the microscope as a scientific instrument and its involvement in specimen preparation techniques, cell theory and bacteriology is described.The pursuit of increased resolving power—in particular the development of apochromatic lenses by Abbe and Zeiss and enhanced contrast techniques—polarized fight, u.v. microscopy, u.v. absorption and fluorescence, phase contrast and the differential interference contrast techniques, etc., are discussed. The story of microscopy in the twentieth century is one of interlocking discoveries and advances and the techniques of epi‐illumination in scanning fluorescence microscopy, video acquisition and analyses of images in digital form and confocal scanning microscopy are surveyed. It is concluded that these techniques have opened up whole new areas for the future development of light microscopy.
SEM—past, present and future
Authors: McMullan D. 
Published: August 2011

SUMMARYThe development of the technology of the scanning electron microscope (SEM) is traced from the early pioneering work in the 1930s to the present day. Recent trends are described and, based on these, some speculative forecasts are made of possible future developments. It is suggested that these will include better vacuum conditions in conventional SEM to permit more accurate surface characterization, and improved electron optics for higher resolution, particularly with low‐voltage operation.
Catalyst particle sizes from Rutherford scattered intensities
Authors: Treacy M. M. J. , Rice S. B. 
Published: August 2011

SUMMARYWe show that the number of atoms in a small supported catalyst cluster can be estimated from the strength of electron scattering into a high angle annular detector in the STEM. The technique is related to the Z contrast methods developed by Crewe, Wall, Langmore and Isaacson. It works best for high atomic number catalyst particles when supported on low atomic number supports, such as Pt on γ‐aluminium oxide. The method is particularly useful for detecting and measuring particles in the sub‐nanometre size range where bright field images are unreliable. Unlike the Z contrast methods, a high angle annular detector is used, which avoids intensity modulations arising from Bragg reflections. The signal is mostly high angle diffuse scattering, which is predominantly Rutherford scattering, and is proportional to the number of atoms probed by the beam, weighted by their individual scattering cross‐sections.Scattering strengths of individual clusters are computed from digitized high angle annular detector images. Data for Pt on γ‐aluminium oxide, when plotted as imaged area1/2 against intensity1/3, define a straight line. Such plots provide calibration of the intensity increment per atom without the need of external calibration, although assumptions about particle morphology must be made. Reliable results require high signal‐to‐noise and optimum sampling of the specimen. For an STEM probe size of 0.35 nm, Pt clusters containing as few as three atoms can be detected when supported on typical, 20 nm thick, γ‐aluminium oxide supports.
Microspectroscopy on single domains of phase‐separated monolayers
Authors: Meller P. 
Published: August 2011

SUMMARYA versatile and inexpensive, but fully equipped apparatus is presented, which enables detailed optical studies on amphiphilic molecules at the liquid‐gas interface. Structural and spectroscopic information, particularly in small areas of single domains of phase‐separated monolayers, can be achieved by combination of this miniaturized Langmuir trough and spectralphotometer microscope. The potential of this apparatus is demonstrated with some measurements on a diyne‐substituted polymerizable lipid analogue at the air‐water interface.
Scanning tunnelling microscopy measurements of carbon deposited on to graphite
Authors: Nakagiri Nobuyuki , Kaizuka Hiroshi 
Published: August 2011

SUMMARYTopographic STM images were taken of carbon deposited onto cleaved Kishgraphite. Hillocks were seen at places in the STM images for 1‐ and 2‐nm depositions. The hillocks covered the entire surface with depositions in the range 3–8 nm and the r.m.s. roughness did not change with deposition in this region. The Fourier spectra for 3–8‐nm depositions show peaks at around 5 and 8 nm. The peak‐to‐valley distance was proportional to roughness with a coefficient of 7.8.
A rotary multiple‐specimen holder for scanning electron microscopy
Authors: Watt Peter Ridgway , Warrack John 
Published: August 2011

SUMMARYFor many applications it is a considerable benefit to be able to compare readily several samples within a set while avoiding the inconvenience of opening the microscope chamber to exchange individual specimens. For complex specimens full specimen manipulation is also required. This paper describes the design and construction of a specimen holder which carries six specimens, is rapidly exchangeable with alternative holders, and retains the full range of movements of the original eucentric single‐specimen holder of a Philips PSEM 501.
EELS quantification of the elements Ba to Tm by means of N45 edges
Authors: Hofer Ferdinand 
Published: August 2011

SUMMARYThe quantification of electron energy‐loss spectra requires determination of the partial scattering cross‐sections. For N45 edges these data are unknown. Therefore, we have determined a set of cross‐section ratios (k‐factors) of N45 and oxygen K energy‐loss edges for a number of elements between the atomic numbers 56 and 70 using thin‐film standards (oxide compounds), which will enable quantification of these rare earth elements.