bluuebunny/crossref_metadata_2025_split huggingface dataset:
A procedure for increasing the contrast of biological specimens in edge‐projection TEM
Authors: Panitz J. A. , Bear D. G. 
Published: August 2011

SUMMARYRotary shadowing has been used to increase the image contrast of biological specimens during edge‐projection imaging in the transmission electron microscope (TEM). In this imaging mode, biological specimens are adsorbed from aqueous solution onto a highly curved substrate and observed in a direction parallel to its surface. High contrast TEM images are obtained at 200 kV when a 1–3 nm layer of tungsten is thermally evaporated onto the substrate at an angle of about 9°. Individual adsorbates are clearly delineated by the smooth, continuous, and fine‐grained tungsten layer that surrounds them. TEM images obtained with this technique can provide a unique view of biological adsorbates on metal, insulator or semiconductor substrates.
The ‘bi‐corpuscle’ stereological problem: estimation of distributions of distances between paired spheres, from measurements in slabs showing overprojection and truncation, and its application to binucleated cells
Authors: Rigaut Jean Paul 
Published: August 2011

SUMMARYA non‐parametric stereological method for the estimation of distributions of distances (d) between paired spheres of the same size, from the distances between their profiles observed in sections, is presented. The model accounts for sphere overprojection and truncation effects.Using the mean value of d (d̄), it is then possible, with simple formulae, to compute the probabilities of the co‐observation of two profiles from paired spheres with distance d between their centres, when at least one profile is observed.A useful application is the estimation of true binucleated cell frequencies from observations on tissue sections. An example for rat liver diploid cells is shown.The sphere distribution must be studied beforehand and, when the size variation is unacceptably large, implying that the assumption of a constant sphere radius is unreasonable, the main limitation of the model is met.
Correction coefficients for the size distribution of photographically recorded spherical particles
Authors: Horálek Vratislav , Coleman Rodney 
Published: August 2011

SUMMARYSpheres which are part of a spatial process are photographed. The relationship is derived between the sizes of the images and the actual sphere size distribution. Non‐orthogonal projection given by the linear optics of a pinhole camera is assumed. The depth of field is brought into the calculation.
Digital image tiles: a method for the processing of large sections
Authors: Silage Dennis A. , Gil Joan 
Published: August 2011

SUMMARYSegmentation of large areas of light microscopic slides into N by N fields, and each of these fields into M digital image tiles, allows the scanning, storage and digital processing of large images. Any of the original N2 fields or composites of M adjacent tiles can be recalled to the video display for analysis. Developed procedures for use on a microscope equipped with a precision scanning stage allow registration of the image coordinates (X‐Y) for any original or composite field and the alignment of one of these fields along the depth (Z) axis by means of external, machined fiducial marks in serial sections. To facilitate work whenever unavoidable, we have incorporated methods for digital image panning and zooming (changes of magnification) and discuss their use and implications.
New progress in X‐ray microscopy
Authors: Cosslett V. E. 
Published: August 2011

SUMMARYInterest has recently revived in microscopy at X‐ray wavelengths, stimulated in part by work for microelectronic lithography. The use of synchrotron radiation and other intense sources of X‐rays, the development of plastic foils in place of photo‐emulsions for recording and the fabrication of Fresnel zone lenses for focusing X‐ray beams have all played a part. Some progress has already been made in improving the resolution and contrast of this method of microscopy, in the wavelength range 2–4 nm. The limitation imposed by radiation damage in biological specimens still has to be explored.
X‐ray microscopy: experimental results with the Göttingen X‐ray microscope at the electron storage ring BESSY in Berlin
Authors: Schmahl G. , Niemann B. , Rudolph D. , Guttmann P. , Sarafis V. 
Published: August 2011

SUMMARYAn X‐ray microscope and X‐ray microscopy experiments with biological specimens are described. The experiments have been performed with a resolution of about 0.05 μm using the synchrotron radiation of the electron storage ring BESSY.
Soft X‐ray contact microscopy with nanosecond exposure times
Authors: Rosser R. J. , Baldwin K. G. , Feder R. , Bassett D. , Coles A. , Eason R. W. 
Published: August 2011

SUMMARYHigh resolution (better than 20 nm) contact micrographs have been produced with exposure times of about a nanosecond. The illuminating source was a short‐lived carbon plasma produced by focusing a single short (∼1 ns) 100 J pulse from the Vulcan laser at the Rutherford Appleton Laboratory (RAL) to a 300 μm spot on a graphite target. This plasma emits strongly in the soft X‐ray region, particularly at the CVI (3.37 nm) and CV (4.03 nm) lines. The specimens were behind a 100 nm thick Si3N4 window, at atmospheric pressure in an environmental cell. The images of diatoms recorded on X‐ray resist showed features down to the limit of resolution of the SEM used to view the developed resist, which was about 20 nm.
Theoretical calculation of layer geometry in rotary shadowed models of membrane‐associated particles
Authors: Landmann L. , Roth J. 
Published: August 2011

SUMMARYThe geometry of the evaporated metal layer on models of membrane‐associated particles has been calculated theoretically and the respective density profiles have been estimated. The models were a hollow cylinder, a hemisphere and a rotary ellipsoid substituting the freeze‐fracture appearance of gap junction connexons and globular integral membrane proteins respectively. These calculations may be used as a help for choosing an optimal compromise between shadowing angle and layer thickness. They furthermore provide a basis for assaying the extent of shadowing artefacts such as decoration and lead to a more accurate interpretation of rotary shadowed structures.
An improved Senarmont retardation analysis method
Authors: Laughlin R. G. , Marrer A. M. , Marcott C. , Munyon R. L. 
Published: August 2011

SUMMARYThe phase difference between two plane polarized light rays whose electric field vectors (planes of polarization) are at right angles is often determined by Senarmont analysis. In this analysis, a quarter‐wave plate whose vibration axes lie at an azimuth of ±45° to the planes of polarization of the two rays is inserted. The rotation of the analyser that leads to extinction is then determined by manual adjustment. This classical method has been significantly improved by, instead, measuring light intensities at thirty‐two evenly spaced analyser angles which span 180° of analyser rotation. An unbiased estimate of the phase difference may then be extracted with high accuracy by analysis as a designed experiment.Of the several numerical analysis methods investigated, harmonic analysis is particularly attractive for routine use—especially with small computers. Iterative non‐linear least‐squares analysis on a mainframe computer was taken as the standard of numerical accuracy, against which direct algebraic solutions on a personal computer were evaluated. An ‘accuracy’ statistic (which measures the goodness‐of‐fit to the theoretical cosine function) has proven invaluable in assessing the validity of actual data.Data of exceptional quality are produced by the Leitz Jamin–Lebedeff optical system using intensities measured with a photodiode detector placed in the camera tube of the microscope. These data will support analysis to better than 0.0001° of analyser position, or <6×10−7 periods. Since alignment of the optics with comparable accuracy is impossible, a method for accurately quantitating the contribution to the observed retardation that originates from within the optics, by performing the analysis on an air sample, has been devised.
A microscope diffusion chamber for the determination of the equilibrium and non‐equilibrium osmotic response of individual cells
Authors: McGrath J. J. 
Published: August 2011

SUMMARYA microscope diffusion chamber has been developed which allows direct observation of the dynamic osmotic response of individual cells in micro‐volume suspensions. Continuous observation of stationary cells is possible including short experimental times while the extracellular chemical composition is changed. Multiple changes of solute type or concentration are easily imposed upon a single sample volume. Response times are a function of chamber configuration but response times as low as 1–10 s are possible with negligible solute concentration gradients within the sample region. The chamber is simple and economical to construct and use. It is the size of an ordinary glass microslide and it can be adapted easily to any common laboratory microscope. All standard optical techniques may be used with the chamber. Construction details and operating characteristics including important limitations are discussed. Example photomicrographs and osmotic data are included.
A simple method for obtaining and analysing the absorption spectra of microscopic specimens
Authors: Jennings J. B. , Fletcher C. R. 
Published: August 2011

SUMMARYA method is described for obtaining and analysing the absorption spectra of microscopic specimens, using readily available laboratory equipment. Spectra obtained from the primary image with a hand spectroscope are recorded photographically and the negative images subsequently analysed, in terms of optical density relative to a standard spectrum, using a gel scanner densitometer and chart recorder. The system has been used to recognize and characterize the haemoglobin of a symbiotic flatworm, absorption peaks being resolved to within 5.0 nm. Separation of the recording and analytical stages confers flexibility since records can be made, if desired, in the field or by co‐workers elsewhere and analysed later in the base laboratory.
Orthogonal triplet probes: an efficient method for unbiased estimation of length and surface of objects with unknown orientation in space
Authors: Mattfeldt T. , Möbius H.‐J. , Mall G. 
Published: August 2011

SUMMARYIf the axis of anisotropy of oriented, tubular or lamellar objects is unknown, the unbiased stereological estimation of length density and surface density (Lv and Sv) requires counts on sections with isotropic uniform random (IUR) orientation. It is shown theoretically that in homogeneous, anisotropic specimens the precision of Lv and Sv estimation is considerably augmented if IUR‐oriented sets of three mutually perpendicular sections (orthogonal triplet probes=ortrips) are used instead of three directionally independent IUR sections. The mechanism of variance reduction results from a negative covariance between sections within ‘ortrips’ and corresponds to the antithetic variate principle of Monte Carlo work. Heterogeneity decreases the efficiency of the ortrip method, but this effect can often be counteracted by systematic sampling of ortrips within specimens. Practical estimation of length and surface area of the highly anisotropic, tubular myocardial capillaries per tissue volume in the left ventricles of eight normal, adult, male perfusion‐fixed Wistar rats provided estimates of excellent precision with CEs of 3.3% (Lv) and 2.1% (Sv) of the group mean. The method will hopefully allow stereologists dealing with arbitrary anisotropic structures to apply the same simple, efficient, and unbiased sampling designs that have long been used in the study of liver, lung, and kidney tissue.
A method for preparing quick‐frozen, freeze‐substituted cells for transmission electron microscopy and immunocytochemistry
Authors: Nagele R. G. , Kosciuk M. C. , Wang S. M. , Spero D. A. , Lee H. 
Published: August 2011

SUMMARYA quick‐freeze, freeze‐substitution method is described which employs glutaraldehyde as well as osmium tetroxide (OsO4) in a ‘double‐fixation’ protocol comparable to that used for conventional transmission electron microscopy. Cultured cells are quick‐frozen in Freon 22 and freeze‐substituted in an ethanolic solution of glutaraldehyde. Specimens destined for TEM are postfixed in OsO4 in acetone, embedded in Epon‐Araldite, and sectioned. This method yielded ultrastructural preservation which was comparable to that obtained from methods employing OsO4 alone as a freeze‐substitution fixative. However, if glutaraldehyde is used alone as a freeze‐substitution fixative, specimens can be processed for immunocytochemistry without additional treatment with permeabilizing agents.
Annealing of amorphous layer in S+ implanted GaAs by electron beam inside the electron microscope
Authors: Rai A. K. , Bhattacharya R. S. 
Published: August 2011

SUMMARYAnnealing behaviour of amorphous layer in S+ implanted GaAs is studied by employing transmission electron microscopy technique. The amorphous layer is annealed inside the electron microscope by withdrawing the condenser aperture. The transformation of amorphous layer into polycrystalline layer is found to occur in the near surface region. Formation of twins is observed near the interface of amorphous crystalline region. Coarsening of grains occur on further annealing. The findings of the present experiment is compared with the explosive recrystallization behaviour of amorphous Si under laser and electron irradiation (Narayan et al., 1983). It has been concluded that both solid phase and liquid phase epitaxial regrowth of the amorphous GaAs layer have taken place upon electron irradiation.
The problem of ambiguous profiles of microvilli between apposed cell surfaces: a stereological solution
Authors: Mayhew T. M. 
Published: August 2011

SUMMARYWhen interdigitating microvilli projecting from apposed cell surfaces are sectioned randomly, it becomes impossible to specify to which of the two parent surfaces an individual microvillous profile belongs. Because of this image ambiguity, direct estimation of the ratio of microvillous surface areas by intersection counting cannot be performed. A stereological solution to this problem is proposed. It relies on counts of the numbers of bases of microvilli identified on each reference (parent) surface.
Some limitations of the use of tannic acid as a marker of damaged skeletal muscle fibres
Authors: Cottell David C. , Hooper A. C. B. 
Published: August 2011

SUMMARYMouse biceps brachii muscles containing single transverse incisions were treated with low molecular weight tannic acid. In the absence of fibre degeneration, intracellular spread of tannic acid was confined to a short distance along the fibres from the damaged portions of the cell membranes. Beyond this, damaged and undamaged fibres could not be distinguished from one another. Tannic acid is not a reliable marker of localized trauma to skeletal muscle fibres.
Vitrification of pure liquid water
Authors: Mayer Erwin 
Published: August 2011

SUMMARYThe methods for vitrifying pure liquid water are reviewed: jet‐freezing of water/oil emulsions, vitrification of thin water layers on an electron‐microscope specimen grid, high‐pressure jet‐freezing and rapid cooling of aerosol droplets on a cryoplate. The first three need a liquid cryomedium for heat transfer in contrast to the last one. Small sample size in at least one dimension, with a diameter in the μm range or even less, is essential for vitrification. Vitrified liquid water has been characterized by electron and X‐ray diffraction, infrared spectroscopy and by differential thermal analysis warm‐up curves. These properties are compared with those of amorphous solid water prepared by deposition of the vapour.
Low temperature embedding with Lowicryl resins: two new formulations and some applications
Authors: Carlemalm E. , Villiger W. , Hobot J. A. , Acetarin J.‐D. , Kellenberger E. 
Published: August 2011

SUMMARYLowicryl K4M and HM20 are methacrylate/acrylate based low temperature embedding resins for biological material which can be used in conjunction with either the progressive lowering of temperature (PLT) technique or with freeze‐substitution. K4M and HM20 are applicable over a very extended temperature range, approximately 220 K to 340 K. With two new resins, K11M and HM23, one can reach even lower temperatures, c. 200 K. Freeze‐substitution combined with low temperature embedding allows for very mild or no chemical fixation which seems to increase the sensitivity of immunocytochemical localization of antigens on sections.
Cryo‐electron microscopy of helical particles TMV and T4 polyheads
Authors: Lepault J. 
Published: August 2011

SUMMARYVitrified Tobacco Mosaic Virus (TMV) and T4 polyhead suspensions have been studied by cryo‐electron microscopy. The order of TMV particles is preserved to distances better than 0.3 nm when vitrified. In spite of the high beam sensitivity of unstained biological material, the resolution of images extends to 1.15 nm. Radial density distributions calculated from images of TMV and the helical aggregate of TMV protein (TMVP) show that the RNA is likely visualized in the virus. However, due to the imaging conditions of unstained vitrified specimens, the position of the RNA is erroneous. While TMV and TMVP do not show any departure from cylindrical symmetry, T4 polyheads are sensitive to the thickness of the ice layer in which they are embedded. To avoid flattening, T4 polyheads have to be embedded in an ice layer thicker than their diameter.
Light microscopy of ceramics
Authors: Roberts E. W. , Robinson P. C. 
Published: August 2011

SUMMARYTechniques in light microscopy of ceramics are described. The information provided by transmitted light examination of thin sections is discussed with particular emphasis on polarization microscopy. The production of polarization colours and the use of retardation plates are briefly explained with reference to their use in the study of preferred orientation in alumina ceramics. The discussion relating to incident light examination of polished sections is mainly concerned with methods of disclosing microstructural details by various methods including polarization microscopy, interference contrast and etching. The final part of the discussion deals with methods of studying sub‐surface detail in polished sections of transparent ceramics, including the use of incident dark‐field and oil immersion objectives.
The importance of microscopy in studying the wear behaviour of ceramic surfaces
Authors: Czernuszka J. T. , Page T. F. 
Published: August 2011

SUMMARYThis paper demonstrates how careful microscopy of worn ceramic surfaces can be used to provide information on the mechanisms of material removal. This information is necessary as a critical complement to wear‐rate data obtainable from simple wear tests alone (e.g. lapping with diamond grits). Scanning electron microscopy has been extensively used to investigate the changing appearance of worn surfaces as plasticity and fracture processes compete as materials removal and redistribution mechanisms. Examples of the use of secondary electron imaging at different surface tilts, back‐scattered electron imaging and stereo imaging are shown. Further, transmission electron microscopy of samples specially prepared to contain the worn surface layer can reveal the presence of phase changes accompanying wear. Furthermore, observations have been made of instances whereby brittle fracture has unexpectedly occurred as a result of repeated plastic deformation of surfaces at low contact severities.Some conclusions are drawn regarding the influence of specimen microstructure, abrasive grit size and environment of the wear of glass‐bonded (debased) alumina and titania materials.
Transmission electron microscopy of zirconia ceramics
Authors: Butler E. P. 
Published: August 2011

SUMMARYThe relationship between microstructure and the mechanical and electrical properties is outlined for the main types of zirconia ceramic. Microstructural and microchemical characterization of these materials by TEM at 1000 kV and 100 kV accelerating potentials is demonstrated by reference to selected examples representing fully and partially stabilized zirconia and zirconia‐toughened alumina. Grain boundaries and grain boundary phases appear to be particularly important in determining the way in which zirconia ceramic microstructures evolve during sintering and/or ageing.
EXELFS of alumina, ab initio calculations and the measurement of charge transfer
Authors: Bourdillon A. J. , Tebby G. P. 
Published: August 2011

SUMMARYEXELFS were measured for graphite, α‐alumina and a hydrated electrodeposited alumina foil. A theoretical comparison is made between EXELFS and EXAFS, and phase shifts and scattering factors calculated ab initio using curved waves. Good least squares fits to the graphite data demonstrate the applicability of calculated values to light elements in both EXAFS and EXELFS. The ab initio calculations for α‐alumina include ionic effects and a new method was devised for measuring charge transfer. Fourier transforms of the oxygen K‐edge EXELFS showed that the amorphous film, which becomes stable under the electron beam after hydration, but before crystallization, contained at the stage examined a ratio of 50% [AlO6]/[AlO4] cell units.
Microchannel plate detector for low voltage scanning electron microscopes
Authors: Russell P. E. , Mancuso J. F. 
Published: August 2011

SUMMARYA microchannel plate detector has advantages over conventional Everhart‐Thornley detectors for low voltage SEM applications. A microchannel plate can provide symmetric SEM signal detection at the low beam energies needed for non‐destructive examination of integrated circuits. Microchannel plate detectors are effective for both secondary electron and backscattered electron imaging. Their relatively small size and ability to be mounted directly below the final pole piece give them improved performance relative to conventional detectors in applications requiring short working distances. A significant amount of laboratory and applications experience has shown that microchannel plates are reliable and sufficiently resistant to contamination for use in high volume, production environments which require low voltage SEM imaging.
Laser scanning phase modulation microscope
Authors: Hansen E. W. , Allen R. D. , Strohbehn J. W. , Chaffee M. A. , Farrington D. L. , Murray W. F. , Pillsbury T. A. , Riley M. F. 
Published: August 2011

SUMMARYWe describe the concept and first implementation of an innovative new instrument for quantitative light microscopy. Currently, it provides selective imaging of optical path differences due to birefringence; with further development, it is also possible to selectively image several optical properties, including refractive path differences, optical rotation, and linear and circular dichroism, all with diffraction‐limited resolution. An image consists of a 512×512 element array, with each pixel displaying one of 256 grey levels, linearly proportional to the specific optical property being observed. Additionally, conventional brightfield and polarized light microscopy are available, with the accompanying advantages of laser scanning and digital image processing.The microscope consists of three subsystems, representing three distinct technologies. The laser scanning subsystem moves a focused, microspot across the specimen; the output of a photodetector is an electric signal corresponding to a scanned image. The image display subsystem digitizes this signal and displays it as an image on a video monitor. When used in conjunction with a phase modulation feedback loop, the image formed is of the specimen's birefringent retardation or other selected optical property. The digitized images are also available for computer enhancement.