bluuebunny/crossref_metadata_2025_split huggingface dataset:
A mirror electron microscope for surface analysis
Authors: Foster M. S. , Campuzano J. C. , Willis R. F. , Dupuy J. C. 
Published: August 2011

SUMMARYThe principle of mirror microscopy has been adapted to provide a relatively low resolution surface microscope (<1000 ×), a large transfer width low energy electron diffractometer and a photoelectron analyser in k|| space. A focused electron beam of ≃ 10 kV is decelerated through a Johansson lens, reflected in front of the sample and reaccelerated back through the lens to produce an electron image over a field of view of a few microns. The image can be interpreted as a micrograph of work function variations on the surface if other effects (geometry, magnetic field) are uniform. In the LEED mode, diffracted beams virtually retain their positions on the screen over the whole impact energy range used (0.160 V). Secondary electrons are preferentially focused around the lens‐gun electro‐optic axis, thus effectively filtering them out from the diffraction pattern. The design has an inherently large coherence length, of up to 104 Å. Photoelectrons can similarly be imaged in k|| space on the detector plane. The addition of energy filtering at the screen allows the two‐dimensional Fermi surface to be imaged.
A double tilting cartridge for transmission electron microscopes with maximum solid angle of exit at the specimen
Authors: Everatt P. G. , Valdrè U. 
Published: August 2011

SUMMARYA new type of double tilting cartridge for transmission electron microscopes (CTEMs and STEMs) is described, which has been designed with the following applications and requirements in mind: (i) observation of large specimens, in particular semiconductor devices carrying electrical leads for signal exploitation; (ii) maximum (2π) solid angle of beam exit subtended by the specimen; (iii) location of the specimen as low as possible in the pole piece gap of the objective lens.The working principle is based on the kinematics of a hemisphere resting on the end of a cylindrical tube, and can be applied to any type of electron microscope specimen holder of the top entry type.
Measurement of characteristic wavelengths in modulated microstructures by field‐ion microscopy
Authors: Miller M. K. , Burke M. G. , Brenner S. S. 
Published: August 2011

SUMMARYA procedure to determine the characteristic wavelength of a modulated microstructure from field‐ion micrographs is described. The procedure accounts for the effects of the orientation of the modulations in the specimen and the projection of the curved FIM specimen surface by correlating the measurements from the micrograph with computer simulated micrographs generated with the same orientation. The results exhibit excellent agreement with measurements determined from the spacing of sidebands in electron diffraction patterns.
Automatic analysis of the motion of microorganisms
Authors: Gualtieri P. , Colombetti G. , Lenci F. 
Published: August 2011

SUMMARYAn automatic, interpretative, off‐line computer‐television‐microscope system for studying the behaviour of microorganisms is presented. The equipment should be available even in relatively modestly equipped laboratories.The movement of microorganisms freely swimming in the chamber of a depression slide is recorded on a video tape with the aid of a microscope and an infrared TV camera. The images are acquired by means of a frame grabber in an image controller and elaborated by a PDP 11/23 computer.The procedures used for data processing are discussed in detail. Trajectories reconstructed by the computer are shown to be exactly superimposed to the real ones, and the motion parameters can be easily determined.
Two‐dimensional crystallization experiments*
Authors: van Bruggen E. F. J. , van Breemen J. F. L. , Keegstra W. , Boekema J. , van Heel M. G. 
Published: August 2011

SUMMARYOur experience in the growth of two‐dimensional crystals of different proteins is presented. Polyethylene glycol was used to produce two‐dimensional arrays of haemocyanin from O. vulgaris and of cholera toxin. The arrays showed a hexagonal close‐packed structure of only randomly oriented molecules. The increase in protein concentration probably occurred too quickly to allow complete crystallization. Different two‐dimensional arrays of hexameric haemocyanin molecules (from P. interruptus) were obtained by microdialysis through the specimen supporting film. A comparison was made with X‐ray data. Two‐dimensional tetrameric arrays of molecules, possibly rhodopsin, were seen in samples of bovine retinal rod outer segments in the presence of ammonium sulphate. Two‐dimensional crystals of complex I (from bovine mitochondria) were prepared by dialysis in the presence of ammonium sulphate. A three‐dimensional reconstruction was made from two tilt‐series by computer filtration using the direct SIRT procedure. Finally, the possibility of computer crystallization using correlation techniques in combination with correspondence analysis is discussed.
Study of the direct Fourier method for the three‐dimensional reconstruction of objects in the case of a missing angular data range
Authors: Carazo Jose María , Santisteban Antonio , Carrascosa José L. 
Published: August 2011

SUMMARYSome practical and theoretical considerations on the three‐dimensional reconstruction of an object from its two‐dimensional projections by the direct Fourier method have been obtained using computer generated images. The procedure applied has been designed to study the specific problems derived from the collection of images in transmission electron microscopes (TEM), making special emphasis on images of biological objects. The study of the calculated point spread function (PSF) of the experimental system and the mean and variance profiles of the reconstructions have provided useful criteria to assess the quality and the interpretability of three‐dimensional reconstructions of real data.
Microscopic observation and video recording of cellular response to sudden changes in environment
Authors: Eskelinen Sinikka , Coakley W. Terence 
Published: August 2011

SUMMARYA method to record responses of single cells to rapid changes in their environment is described. A rectangular glass microcapillary is filled with the cell suspension under investigation and placed under a light microscope. With the aid of a micromanipulator a smaller microcapillary with a narrowed tip, which was still over 10 times wider than the cell diameter, is driven into the larger, cell containing, microcapillary. The environment of the cells is changed by injecting a new medium via the smaller capillary and the cell responses are recorded using a video recording system. The usefulness of the system has been examined by studying the time course of the osmotic swelling of erythrocytes after water injection and the shape transformations caused by lysophosphatidylcholine.
Computer‐aided integrating microdensitometry and specimen imaging with the Vickers M85A
Authors: Goldstein D. J. , Lovering R. , Hartmann‐Goldstein I. J. 
Published: August 2011

SUMMARYA Vickers M85A flying‐spot microdensitometer has been linked to a standard BBC model B microcomputer with a commercially available interface, and programs developed in which the computer controls step‐wise scanning of the specimen. At each image point thirty‐two absorbance readings are made and the average value is stored in the computer memory at 8‐bit resolution; a complete 48×48 raster takes less than 5 s. An image of the specimen displayed on the monitor uses eight different pseudo‐grey‐level characters, and the manner in which the 256 possible absorbance values are represented on the screen can be altered by the user. A mask of arbitrary shape and size, drawn on the screen under key‐board control, makes it possible to measure the integrated absorbance of even small, irregular and closely packed specimens such as individual bands in Drosophila polytene chromosomes. The coefficient of variation of repeated measurements of a Feulgen‐stained frog nucleus is typically better than 1%. Displayed images can be printed on a dot‐matrix printer, and data stored on disc for subsequent analysis. The techniques can readily be modified and adapted for other purposes, some of which are briefly discussed.
Freeze‐fracturing at defined temperatures provides information on temperature rise during fracture, and on membrane complementarity
Authors: Gruijters W. T. M. , Bullivant S. 
Published: August 2011

SUMMARYAn apparatus is described which allows freeze‐fracturing at defined temperatures, followed by immediate immersion of the specimen in liquid nitrogen. Replication is carried out in a Bullivant & Ames (1966) freeze‐fracture device.Using yeast as a test specimen, the following results were obtained with the apparatus: (a) It was confirmed that fracturing at temperatures between 243 K and 223 K gave undeformed volcanoes on the PF of the plasma membrane, as shown originally by Steere et al. (1980). (b) Considerable energy is released by the fracturing process, both as shown by thermocouple readings and by the fact that at relatively high fracture temperatures portions of the specimen surface were melted. A temperature rise of 50–70 K was indicated, (c) Under standard conditions, there is a lack of complementarity between the yeast plasma membrane fracture faces, trigonal point particles not being present opposite the corresponding depressions in the array. Fracturing yeast suspended in salt solutions at 203 K demonstrates these particles. Their absence in normal fractures can be explained by ‘secondary fracture’, a concept based on polymer fracture studies.
Effect of specimen preparation and section transfer techniques on the preservation of ultrastructure, lipids and elements in cryosections
Authors: Hagler H. K. , Buja L. M. 
Published: August 2011

SUMMARYCryofixation, cryoultramicrotomy, and proper transfer of the cryosections into the electron microscope are important for the preservation of good ultrastructure and the measurement of subcellular elemental distributions. These techniques are applicable to tissue systems which can be rapidly frozen so that minimal to no ice damage occurs during the cryofixation step. For the transfer step we have compared the cryotransfer of hydrated sections and subsequent freeze‐drying in the electron microscope with the transfer of sections into an external freeze‐dryer, followed by exposure to room temperature and humidity before introduction into the electron microscope. The use of a cryotransfer stage for section transfer from the cryoultramicrotome to the electron microscope and low temperature observation of the thin sections avoids the potential problem of rehydration damage to freeze‐dried sections as well as provides protection from the possibility of melting of the lipids in the sections. Both of these problems may lead to loss of in situ elemental distribution and morphology. In this report, observations are presented which show the damaging effects of temperatures above 273 K on ultrastructure due to lipid melting in tissues with high lipid content and the redistribution of elements which can be encountered when thin sections become inadvertantly rehydrated.
Soft X‐ray contact microscopy, using synchrotron radiation, of thin‐sectioned, lead‐contaminated chloragogenous tissue of the earthworm Dendrobaena rubida
Authors: Richards K. Sylvia , Rush A. D. , Clarke D. T. , Myring W. J. 
Published: August 2011

SUMMARYSoft X‐ray (2.05–4.4nm) contact microscopy, using synchrotron radiation, of ultrasections of lead‐polluted chloragogenous tissue of the earthworm Dendrobaena rubida has been achieved. The positive resist, after etching to leave areas corresponding to high absorbance in the tissue, is viewed by SEM and the imaging compared with the same section viewed, after irradiation, by TEM. No radiation damage as evident and the lead deposits associated with the chloragosomes and within the debris vesicles imaged clearly. The characteristics of the broad beam have thus produced a lead ‘map’. Resolution is in the order of 70 nm. The results are compared with the markedly different imaging of control tissue containing insignificant lead levels.
Differential staining of dead and dying embryonic cells with a simple new technique
Authors: Martín‐Partido G. , Alvarez I. S. , Rodríguez‐Gallardo L. , Navascués J. 
Published: August 2011

SUMMARYA new staining technique with toluidine blue and safranin is described which yields satisfactory results in histological sections of chick embryo tissue fixed in a mixture of glutaraldehyde and formaldehyde and embedded in Spurr's resin. In zones of embryonic cell death, this technique allows the blue‐staining of dying cell pyknotic nuclei to be clearly distinguished from red‐staining healthy cells. The possible factors underlying this differential staining of pyknotic nuclei are discussed.
A simple method for correlative light, scanning electron microscopic and X‐ray microanalytical examination of the same section
Authors: Siklós L. , Rózsa M. , Zombori J. 
Published: August 2011

SUMMARYThin paraffin sections, mounted on scanning specimen holders previously coated with polyester film tape (Minnesota Mining and MFG Co., Scotch film tape No. 850 gold), were processed for light microscopy (LM) in the conventional way, then covered with celloxin shellac and examined in the LM by using the upper illuminating source. After removal of the shellac from the surface of the sample by immersion in acetone, the sections were air‐dried, coated with a copper layer in a vacuum evaporator and examined in a scanning electron microscope (SEM).The method allows: (i) high‐quality LM possibilities for establishment of the diagnosis in pathological cases; (ii) SEM examination of the same area as observed in LM; and (iii) EPMA measurements of insoluble precipitates embedded in the tissue.The usefulness of the proposed method is obvious in cases where the composition of a precipitate on LM scale is to be compared with the LM appearance of the surrounding tissue.
Fine structure of the images of atoms in 011‐gold crystals in various Bragg reflecting conditions
Authors: Hashimoto H. , Takai Y. 
Published: August 2011

SUMMARYFine structures with petal and horseshoe shape contrast have been observed in the high resolution electron microscope images of atoms in a 011 gold crystal in deviated Bragg reflecting conditions. The images with such fine structures have been recorded by using only the beams of 000, four 111 and two 200 reflections with axial illumination. The contrast of the images has been discussed by the many beam dynamical theory of electron diffraction and the image formation theory considering the spatial and temporal coherence of the electron waves. It has been noted that the temporal coherence has much more effect on the change of image contrast than the spatial coherence. The imaging conditions have been analysed in terms of Fourier images and the aberration free focus conditions.
High resolution transmission electron microscopy of Sm‐Co based permanent magnets
Authors: Hiraga K. , Hirabayashi M. , Ishigaki N. 
Published: August 2011

SUMMARYInterface microstructures between rhombohedral Sm2Co17 and hexagonal SmCo5 phases in a sintered permanent magnet of Sm(Co0.675Fe0.175Ni0.05Cu0.1)7 have been investigated by edge‐on observations with the many‐beam imaging technique. In the specimen annealed at 800°C for 4 h which shows a maximum magnetic coercivity, the interface boundaries were coherent accompanying the lattice distortion; the habit planes were parallel to the {101}2:17 and {111}1:5 planes with the orientation relationship of (0001)2:17//(0001)1:5 and [1010]2:17//[1120]1:5. In the specimen annealed for 150 h which shows a lower coercivity, the interface boundaries were characterized with regular alignments of interfacial edge dislocations. The observed interface structures were discussed in connection with the change in magnetic properties.
Post‐embedding cytochemistry with gold‐labelled reagents: a review
Authors: Roth J. 
Published: August 2011

SUMMARYThe detection of antigens and glycoconjugates with the protein A–gold and the lectin–gold techniques, respectively, is reviewed. Special attention is directed to the necessary conditions for fixation and embedding as well as to the staining procedures of tissue sections for light and electron microscopy.
Light microscopical detection of single 5 and 20 nm gold particles used for immunolabelling of plasma membrane antigens with silver enhancement and reflection contrast
Authors: Hoefsmit E. C. M. , Korn C. , Blijleven N. , Ploem J. S. 
Published: August 2011

SUMMARYTo detect plasma membrane antigens, cytocentrifuge preparations of the macrophage‐like cell line P388D1 were incubated with monoclonal antibodies and labelled with 5 and 20 nm gold particles conjugated to immunoglobulins or protein A. The 20 nm, but not the 5 nm, particles could be observed by reflection‐contrast light microscopy. Single 5 nm particles, however, were clearly demonstrable with silver contrast enhancement, both in absorption contrast and in reflection contrast. The method proved to be compatible with cytochemical methods such as acid phosphatase.
An extrapolation method for the determination of Cliff‐Lorimer kAB factors at zero foil thickness
Authors: Horita Zenji , Sano Takeshi , Nemoto Minoru 
Published: August 2011

SUMMARYAn extrapolation method is proposed to be useful for the determination of the Cliff‐Lorimer kAB factor at zero foil thickness. The method consists of measuring kAB factors as a function of the measured foil thickness, tM, and extrapolating the relationship toward tM=0. The intersection between the extrapolated line and the ordinate of tM=0 gives (kAB)0 which is free from the effect of absorption. The straight line extrapolation that can be achieved by a linear‐least squares method is particularly developed to eliminate arbitrariness introduced in the extrapolation process.The extrapolation method is applied to data available in the literature. It is shown that the method yields the (kAB)0 factors compatible with those predicted from the theoretical calculation. It is also shown that this method can circumvent several problems which make it complex and difficult to determine accurate values of the absorption‐free kAB factors.Using the straight line extrapolatioin, it is possible to estimate the degree of the thickness overestimation which arises when the foil thickness is measured by the contamination spot separation (CSS) method. Validity of the straight line extrapolation is further discussed.
The interpretation of EBIC images using Monte Carlo simulations
Authors: Joy David C. 
Published: August 2011

summaryCharge collection microscopy, usually known by the acronym EBIC (Electron Beam Induced Current) imaging, is a powerful technique for the observation and characterization of semiconductor materials and devices in the scanning electron microscope. Quantitative interpretation of EBIC images is often difficult because of the problem of accurately representing the electron‐beam interaction with the semiconductor. This paper uses a Monte Carlo technique to simulate the electron‐beam interaction, and it is shown that this permits simple analytical point‐source solutions to be generalized to fully represent the experimental situation of an extended, non‐uniform, carrier source. The model is demonstrated by application to EBIC imaging in the Schottky barrier geometry.
Simple SEM stereophotogrammetric method for three‐dimensional evaluation of features on flat substrates
Authors: Boyde A. , Howell P. G. T. , Franc F. 
Published: August 2011

summaryA semi‐automated method was developed for the measurement of the volume of a calcified tissue substrate which can be resorbed by single, isolated resorptive cells (osteoclasts). The procedure would, however, be applicable to the study of any pit in, or projection from, a flat surfaced specimen. Stereo‐pair images are recorded with an SEM. 3‐D co‐ordinates of relevant surface features are derived using a stereo‐comparator which outputs data directly to a microcomputer. Algorithms adopted have been chosen to give the best compromise between accuracy and speed of data acquisition.
Study of the conditions necessary for propane‐jet freezing of fresh biological tissues without detectable ice formation
Authors: Haggis G. H. 
Published: August 2011

summaryThe performance of a commercial double‐propane‐jet freezer (Balzers QFD 101) has been assessed, for rapid freezing of fresh tissues in freeze‐etch work. Samples of diaphragm muscle and intestinal villi were frozen between copper sheets, with a spacer to give 20–30μm thickness of tissue. Fracture cuts were made with the Balzers BAF 400 freeze‐etch microtome within 5–10μm of a freezing face (i.e. a tissue face in contact with the copper sheets of the frozen sandwich). After some modifications to the QFD 101, replicas showing no evidence of ice were obtained of muscle cells, although for intestinal epithelial cells some evidence of ice formation was found. Infiltration with 5% glycerol or dimethylsulphoxide improves the depth of good freezing. Results and problems arising from such infiltration are briefly discussed.
Visualization of biological specimens by cryoHVEM
Authors: Fotino Mircea 
Published: August 2011

summaryThis article describes the operation and the characteristics of cryoHVEM imaging of biological specimens using a top‐entry cryostage. The procedure for inserting frozen specimens into the microscope column is also presented. Whole mounts were thus observed under optimal imaging conditions by combining: (i) fixation by fast freezing for structure preservation without exposure to chemicals, (ii) observation in the hydrated (frozen) state or in the dried state without exposure to the atmosphere after the initial fixation by freezing, and (iii) ultrastructural visualization with the key imaging factors of resolution, penetration and beam‐induced damage at their best by high‐voltage electron microscopy.
Temperature control in Lowicryl K4M and glycol methacrylate during polymerization: is there a low‐temperature embedding method?
Authors: Ashford A. E. , Allaway W. G. , Gubler F. , Lennon A. , Sleegers J. 
Published: August 2011

SUMMARYAn apparatus for embedding tissues at resin temperatures down to 228 K is described. By placing thermocouples in the resin the temperature has been monitored during embedding at low temperature with glycol methacrylate (GMA) and Lowicryl K4M. Even in this apparatus with a liquid cooling bath the heat of polymerization is not dissipated and the resin temperature rises. This rise is directly proportional to the resin temperature at the onset of polymerization and is higher in Lowicryl K4M than GMA. The initial resin temperature also affects the time taken for polymerization. The time to the onset of the peak and its duration are both increased as the temperature is lowered. This effect is more pronounced with GMA than Lowicryl K4M and polymerization of GMA is inhibited at the lowest temperature used. When Lowicryl K4M, polymerized at low temperature, is warmed up to ambient a further exothermic reaction occurs, which causes the resin temperature to rise well above ambient. Both this temperature peak and that during polymerization are reduced, but not totally eliminated, by reducing the resin volume. Aircooled systems are inefficient compared with the low‐temperature apparatus used here and the resin temperature rise is consequently greater and, even with small resin volumes, it can be very high. It is therefore unlikely for published methods that the temperature specified has been maintained in the resin during polymerization. The implications of these findings are discussed in relation to enzyme and antigen survival. Recommendations include use of very small volumes of resin, refrigerated liquid‐bath rather than air‐cooled systems and contact with a heat sink when specimens are warmed up to ambient temperature. Examples of enzyme reaction, antigen survival and structural preservation obtained with the method are presented.