bluuebunny/crossref_metadata_2025_split huggingface dataset:
A perspicuous technique for directly visualizing radiation‐damage artefacts in biological electron microscopy
Authors: King Murray Vernon , Parsons Donald F. 
Published: August 2011

SUMMARYLevels of impairment of electron‐microscopic images of biological specimens stemming from radiation damage are assessed in a rapid visual procedure that involves taking a pair of low‐fluence micrographs of a specimen area before and after a fraction of the picture area has been more seriously damaged by applying a measured electron fluence. The pair of micrographs is treated as a mock‐stereo pair and is given contrasting colours. Lateral displacements of specimen details appear as false relief and changes in electron lucency as false colour.
Area changes in slices of rat brain during preparation for histology or electron microscopy
Authors: Hillman H. , Deutsch K. 
Published: August 2011

SUMMARYCerebral slices cut from rat brain, either 2–3 mm or 0·27 mm thick, were used to study the effect of embedding and freezing. Paraffin wax sections 6 μm thick were mounted and stained with haematoxylin and eosin or Marsland et al.'s (1954) silver stain, and their areas were examined at each step.Embedding in paraffin wax of slices 2–3 mm thick, or in Epon of slices 0·27 mm thick, caused a diminution of their areas by 20–30%. Staining of paraffin wax sections did not alter their areas. Glycerol alone at 15% concentration had no effect on the areas, but at 30% concentration they were diminished by approximately 20%. Diminution of the areas of glycerol treated slices 0·27 mm thick also occurred when they were transferred to liquid N2 or to isopentane, but the areas increased after glycerol was replaced by Freon 12.It was concluded that embedding or freezing cerebral slices caused changes in their areas, but that staining of sections after they had been embedded, sectioned and mounted did not.
Ponceau 2R staining of proteins and periodic acid bleaching of osmicated subcellular structures on semi‐thin sections of tissues processed for electron microscopy: a simplified procedure
Authors: Gori Paolo 
Published: August 2011

SUMMARYAn aqueous solution (pH 1·5) of 0·5% Ponceau 2R (C.I. 16150) and 2% periodic acid was used at 318 K to stain proteins (brilliant red) and simultaneously to bleach the osmicated non‐proteinaceous cell structures on 1–2 μm thick sections of tissues fixed in glutaraldehyde‐osmium tetroxide and embedded in epoxy resins. This H5IO6 bleaching‐Ponceau 2R staining procedure only stains the proteins so that black‐and‐white films can be used.
An iterative approach to the analysis of EM autoradiographs
Authors: Downs Angela , Williams M. A. 
Published: August 2011

SUMMARYAn iterative scheme is described for determining the most appropriate ‘model’ for dividing micrographs of EM autoradiographs into identified items of known relative specific activities in such a way that the dispersion of silver grains over the autoradiographs is fully and satisfactorily explained.A trial model is first set up for which, using a square matrix of estimates of notional cross‐fire between the chosen items, a ‘solution’ is obtained. The quality of the model is then tested using extended cross‐fire data contained in a rectangular matrix. If the model is shown to be unsatisfactory, an improved model (of tissue subdivision) is postulated and the whole process repeated until the model is deemed to be satisfactory. The computations are such that the data can be processed rapidly on the laboratory bench using a small machine. The logical estimation of errors is facilitated by this approach.
The theory of scanning microscopes with Gaussian pupil functions
Authors: Sheppard C. J. R. , Wilson T. 
Published: August 2011

SUMMARYThe theory of imaging in scanning microscopes with lenses, source and detector all having Gaussian pupil function is developed. This assumption is useful as the expressions may be evaluated analytically. It is shown that Type 2 microscopes exhibit superior performance to those of Type 1. Effects of defocus are considered. It is found that defocus can be used in a Type 2 microscope to observe phase information without the limitation in resolution associated with stopping down the collector of a conventional microscope. It is also found that a Type 2 microscope discriminates against light scattered by parts of the object outside of the focal plane, allowing observation of detail within a thick object.
Refractive index and absorption coefficient as measures of structural organization in carbonized bitumen
Authors: Khavari‐Khorasani G. , Blayden H. E. , Murchison D. G. 
Published: August 2011

SUMMARYMicroscope photometry has been used to determine reflectances, measured in air and in stable immersion oil, of the carbonized products of the asphaltite bitumen, gilsonite. Comparison of values for parameters (n' and k'), analogous to refractive index and absorption coefficient which are derived from the reflectances, with several X‐ray parameters of the carbonized samples suggests that microscope photometry offers a sensitive alternative method for following changes that take place in the molecular‐structural organization of organic materials during coalification and carbonization processes. Although direct measurement of lattice dimensions is not possible, the optical method is more rapid than X‐ray procedures, is less expensive in terms of capital equipment, while the reflectance measurements can be made on extremely small, discrete and categorically identified field areas, not on the finely ground bulk samples required for X‐ray procedures. Wider application of the microscope photometric method to other carbonized materials and the possibility of absolute correlations between optical and X‐ray data must await more detailed study. The preliminary data are sufficiently encouraging to warrant further extended investigations.
Nature and origin of particles in condensation fume: a review*
Authors: Buckle E. R. 
Published: August 2011

SUMMARYPrecipitate from the fume generated in steelmaking contains chiefly iron in the form of metallic and oxide particles. Significant amounts of zinc and lead may also be present when, as in the U.K., there is substantial recycling of ferrous scrap. Conflicting explanations have been suggested for the sudden release of oxide (‘brown fume’) to form airborne aggregates of ultramicroscopic particles. The presence of free metal, usually as spheres of much larger size than those of the oxide, is attributed to the condensation of vapour to droplets which somehow escape oxidation.Recently, several studies have been reported on the particles in smokes generated by heating metals in an inert gas. This work has been concerned more with the physical properties of the particles than with the mechanisms of condensation and growth. These mechanisms are main objectives in the work of this laboratory.To obtain the fullest microscopical information about the structure of the particles, careful purification of the supporting gas is necessary and the precipitate must be guarded from the air by a protective coat of gold or gold‐palladium deposited by sputtering under argon or by vacuum evaporation. With the aid of morphological data on a number of volatile metals and thermally stable salts it has been possible to draw some conclusions about the relationship of the particle size and form to the conditions of aerosol generation. Close control of these conditions is especially difficult to achieve with involatile materials, including iron, although it seems likely that the use of lasers could greatly enlarge the scope of these studies in the future.
A programmed controlled temperature microscope stage
Authors: Reid D. S. 
Published: August 2011

SUMMARYThe construction, and testing, of a programmed controlled temperature stage for optical microscopy is described. The stage is shown to be capable of attaining temperatures between 160 K and 373 K, and of providing repeatable heating and cooling rates up to, and in excess of 100 K min−1. It is also capable of providing stable temperature holds.
The estimation of distances between parallel membranes on thick sections
Authors: Casley‐Smith J. R. , Davy Pamela 
Published: August 2011

SUMMARYSince sections intersect membranes at random angles, the mean distances measured between two such membranes are greater than the perpendicular distances between them. Errors of 10–20% will be usual. Equations are derived relating the true lengths with the various observed ones, and the accuracy of the various methods are indicated. These differ for block‐stained and section‐stained material.In the Appendix it is shown that in section‐stained material, while it is the stain near the surface which is of overwhelming importance for the production of contrast, much of this stain lies in the section itself, rather than actually on the surface. This stained depth is shown to be ∼4 nm deep, but this depth may include surface aggregates (∼ 1 nm) as well.
An economical, semi‐automatic system for measuring cellular tree structures in three dimensions, with special emphasis on Golgi‐impregnated neurons
Authors: Overdijk J. , Uylings H. B. M. , Kuypers K. , Kamstra A. W. 
Published: August 2011

SUMMARYThe hardware and software of a semi‐automatic system are described for the measurement of cellular tree structures in thick microscopical sections such as the processes of Golgi‐impregnated neurons. With this system, the morphologist— viewing the neuron directly through the microscope— measures the tree structures using three cartesian coordinates of characteristic points, e.g. centre of cell, origin of processes, bifurcation points, end points, deflection points, etc. The system requires an on‐line computer, but does not demand a dedicated computer since a joystick generator usually drives the microscopical stage during cell tracking. A digital computer is utilized for acquisition of data and, when needed, to return the stage to a required position. The microscope stage is coupled to three stepping motors with 0·5 (μm as the smallest step. The stepping motor for movement of the stage parallel to the optical axis (z‐direction) is coupled directly to a spindle mechanism, replacing the original cog wheel mechanism. This construction shows no measurable backlash. The practical advantages of this new measuring system in relation to the existing digital systems currently in use, its accuracy and its costs, are discussed.
Orientation of medial smooth muscle in the wall of systemic muscular arteries
Authors: Canham Peter B. , Mullin Kerry 
Published: August 2011

SUMMARYThe study was undertaken to determine the pattern of alignment of muscle cells in the tunica media of muscular arteries. Brachial and femoral arteries from two small Rhesus monkeys and renal arteries from two rabbits were fixed under pressure with formalin, or glutaraldehyde followed by formalin. Sections were cut at 7 μm thickness at specific angles varying from zero to 30°, and then stained with haematoxylin and eosin. The end coordinates of the medial muscle nuclei (appearing dark with the H & E stain) were recorded using a digitizer. Analysis was done as suggested by a previous modelling study by one of the authors; lengths of the individual nuclei as they appeared on the section were plotted as a function of the distance around the perimeter of the vessel. The distribution of lengths was consistent with a truly circumferential pattern of alignment for the muscle nuclei in the wall of muscular arteries. The standard deviation about the average circumferential pattern was ± 13° in the plane of the histological sections cut in cross section. The number density Nv of 4·4 × 105 mm−3 was higher than determined previously for human brain arteries and the nuclear length was 20% shorter (30 μm).
Sizing of phosphatidylcholine vesicles by transmission electron microscopy
Authors: Larrabee A. L. , Babiarz J. , Laughlin R. G. , Geddes A. D. 
Published: August 2011

SUMMARYCoating of support films for transmission electron microscopy with silica by evaporation of ‘silicon monoxide’ provides a surface which is easily wetted by aqueous systems. Dispersed colloidal particles spread on this surface without the use of added soluble wetting agents. Such coated supports are found to be particularly useful for the quantitative characterization of the size distribution of vesicles prepared from saturated phosphatidylcholine. The weight average vesicle sizes determined for several samples from measurements of negatively stained electron micrographs are in good agreement with values measured by light scattering and ultracentrifugation.
An automatic counter for autoradiographed cells in Petri dishes
Authors: Schmialek Peter , Zapf Burger , Baisch Friedhelm , Geyer Astrid , Miosga Verena , Nündel Michael 
Published: August 2011

SUMMARYA simple automatic counting device for cells on Petri dishes is described. The device is tested up to 1 × 104 cells (0·01 m)−2 and counts linearly without coincidence error. The counting time for each dish is c. 3– 4 min including the time required to place the dish in the apparatus.
A device for the rapid freezing of biological specimens under precisely controlled and reproducible conditions
Authors: Bald W. B. , Robards A. W. 
Published: August 2011

SUMMARYThe construction and preliminary testing of a device is described which can be used to freeze biological specimens in any cryogenic liquid at temperatures down to the nitrogen freezing point (63 K) and which can operate in the pressure range 1.3 kNm−2 to 1 MNm−2.Ultra‐rapid freezing can be carried out in a subcooled cryogenic liquid either hyperbarically or at atmospheric pressure. Slow freezing rates can be achieved by cooling the specimens in a controlled manner in the vapour phase above the liquid bath.
Stabilizing ultrathin cryo‐sections by freeze‐drying
Authors: Geymayer W. , Grasenick F. , Hödl Y. 
Published: August 2011

SUMMARYCryo‐sectioning of specimens with high water content often proves to be especially difficult, as the sections of freeze‐shocked samples with their minimal thermal capacity warm up easily. The resultant recrystallization of the included water causes considerable damage in the structure of the frozen specimens. The method described in this paper enables cryo‐sections to be transferred from the microtome to a precooled high vacuum plant without contamination and at a temperature below the recrystallization point of ice. In this device the cold sections can be stabilized by freeze‐drying, sandwiching or electron‐bombardment for subsequent observation in the transmission electron microscope.
Instrumentation and specimen preparation for electron beam X‐ray microanalysis of frozen hydrated bulk specimens
Authors: Fuchs Wolfgang , Lindemann Bernd , Brombach Jobst D. , Trösch Walter 
Published: August 2011

SUMMARYA cooling chain for the handling of frozen hydrated bulk specimens is described. Use of this method permits the specimen to be kept fully hydrated. After quench freezing, the specimen is transferred to a freeze etch apparatus, freeze fractured, carbon coated and transferred onto the precooled cold stage of the SEM by means of an airlock. The specimen is examined in the secondary electron mode and analysed using an energy dispersive X‐ray analyser. The midgut of Chironomus thummi larvae and frog skin epithelium were used to test the performance.
The use of low temperature X‐ray diffraction to evaluate freezing methods used in freeze‐fracture electron microscopy
Authors: Gulik‐Krzywicki T. , Costello M. J. 
Published: August 2011

SUMMARYTwo methods of freezing samples for freeze‐fracture electron microscopy have been compared using X‐ray diffraction and freeze‐fracture results from lipid‐water model systems. Perturbations of the molecular organization of hydrocarbon chains and the extent of ice crystal formation have been evaluated for lamellar phases of egg lecithin containing 16% water and egg lecithin‐phosphatidylinositol containing 55% water, both freeze‐quenched in liquid Freon‐22 near its melting temperature (113 K). Very thin samples sandwiched between copper sheets separated by an electron microscope grid show much less freezing induced structural rearrangement than small samples contained on conventional Balzers‐type gold planchettes. These results show that the rate of freezing in the very thin preparations is greater than in the conventional ones, which is probably due in part to the improved dissipation of heat from a poorly conductive sample through highly conductive copper sheets.
Cryofracture of paraffin‐embedded heart muscle cells
Authors: Dalen Helge , Myklebust Reidar , Saetersdal Thv. Selmer 
Published: August 2011

SUMMARYA comparative study of internal cellular structures of the sheep ventricular myocardium has been conducted by scanning electron microscopy (SEM) and by transmission electron microscopy (TEM).Access to the cell interior for three‐dimensional studies was obtained by cryo‐fracturing paraffin‐embedded tissue frozen in liquid nitrogen. For accurate localization of structures of special interest thick paraffin sections were examined in the light microscope (LM). Based on the information gained, it was possible to fracture the block in a desired plane. The fracturing was carried out by a light blow to a precooled scalpel held against the surface of the block, which was immersed in liquid nitrogen. After thawing and deparaffinizing at room temperature in several baths of xylene, the tissue pieces were critical point dried using CO2. As xylene was found to be miscible with CO2, it also served as an intermediate fluid. This method resulted in good preservation of the myofibrils, mitochondria, sarcoplasmic reticulum and transverse tubules (T‐tubules), which was confirmed by TEM studies of conventionally prepared tissue and of tissue originally prepared for SEM.
A chamber attached to the SEM for fracturing and coating frozen biological samples
Authors: Pawley James B. , Norton John T. 
Published: August 2011

SUMMARYA chamber for introducing, fracturing and coating frozen biological samples has been developed as an attachment to the specimen chamber of a scanning electron microscope. Together with a eucentric‐tilt cold‐stage, this chamber constitutes a complete system for viewing fractured biological surfaces of the type normally only seen by replica techniques. An air‐lock on the chamber accepts a transfer module to allow insertion of the frozen sample without frost build‐up. Fracturing is carried out with a precisely adjustable cooled knife under a 10–100 × binocular microscope. The sample can tilt and rotate while being coated with carbon or metals evaporated from rechargeable sources introduced through the air‐lock. Cooling in the chamber is provided by a cylindrical copper tank filled with liquid nitrogen. The chamber has its own LN2 trapped high vacuum system. After preparation the sample can be placed directly into the SEM through an isolation valve. The cold‐stage utilizes a Joule‐Thomson refrigerator. The sample can be kept below 103 K at all times though there are provisions for heating it in the fracturing and cold‐stage positions. A system of controls, sensors and interlocks simplifies the operation of the system.
The dispersion of some optical properties of vitrinite
Authors: Jakeman B. L. , Cook A. C. 
Published: August 2011

SUMMARYThe dispersion characteristics of some optical properties of vitrinites from a number of coals of differing coal rank and type were investigated using a microscope photometer. The properties studied were air and oil reflectances, refractive index and absorption index.The technique employed involved the measurement of air and oil reflectances at a number of wavelengths in the visible spectrum for selected points on the coal, as opposed to averaging the reflectances obtained in each immersion medium for each wavelength. The values of air and oil reflectances were then used to calculate the corresponding values of refractive index (n) and absorption index (κ) using a rearrangement of Beer's equation. Smooth dispersion curves were obtained for each selected field of vitrinite using this procedure. This method was preferred to the more widely used method of calculating n and κ from the average air and oil reflectances at each wavelength, because refractive and absorption indices are non‐linear functions of reflectance, which makes the arithmetic mean of the reflectances unsuitable for the calculation of n and κ.The values of all parameters for the vitrinites were found to increase towards the blue region of the visible spectrum and to increase at all wavelengths with increasing coal rank. Some negative values of κ2 were obtained and the significance of these values is discussed.
Application of low temperature microscopy to food systems
Authors: Davis E. A. , Gordon J. 
Published: August 2011

SUMMARYLow temperature scanning electron microscopy (SEM) and X‐ray fluorescent microanalysis were applied to bulk potato tissue samples. Morphological changes and relative distributions for K, P, S and CI were evaluated at various stages of starch gelatinization. Mineral movements into the starch granules were observed as gelatinization took place. Commercially extracted potato starch granules were observed and analysed at low temperatures. Also, these granules were cracked by raising the stage temperature to 153 K. Ice crystal growth appears to induce cracks in a radial and tangential manner along sites of weakness in a pattern that is supportive of the theory of complex starch granule formation.
Electron microscope fluoro‐autoradiography: improvement of efficiency
Authors: Buchel L. A. , Delain E. , Bouteille M. 
Published: August 2011

SUMMARYThe fluorographic process for enhancement of the autoradiographic detection of β‐ray emitted by tritium has been successfully adapted to electron microscope autoradiography. An original scintillator plastic film helped to increase the detection yield of electrons up to 80% without alteration of the morphological aspect of the autoradiograms, and without increasing background fog or causing apparent loss of resolution.
A scanning electron microscope modification for simultaneous numeration of exposures
Authors: Goss W. P. , Gillett R. , Hart J. S. 
Published: August 2011

SUMMARYNeither the standard photographic facilities nor the Record Console of the Cambridge 600 Scanning Electron Microscope have provision for numbering films at the time of exposure. This omission is inconvenient and admits confusion at the later stages of printing. An earlier modification to the viewing screen of the basic instrument has later been transferred to the Record Console. Both are described, providing a convenient numbering facility using cheap proprietary electronic calculators, but leaving the calculating facility available. The system described gives a display of up to seven digits recorded by the camera at the time of exposure, without interfering with either image size or quality.
A simple and inexpensive culture device for cell growth, quantitative microscopy and autoradiography
Authors: Fox Cecil H. , Auer Gert , Zetterberg A. , Cottler‐Fox M. 
Published: August 2011

SUMMARYAn inexpensive culture chamber suitable for subsequent preparations for cyto‐chemical or radiographic work is demonstrated. The chamber consists of two glass microscope slides suitably prepared for cell growth and a gasket of silicone rubber. The slides and gasket are sealed and held together with two ordinary spring letter clips or clothes‐pins. Cells may be inoculated by piercing the gasket with a hypodermic needle, or by removing the top slide and adding cells directly. Long‐term cultivation with medium replacement is easy and efficient and addition of isotopes or other materials may be done aseptically.