bluuebunny/crossref_metadata_2025 huggingface dataset:
Experiments on the characterization of metamorphic textures from a micrograph of an amphibolite
Authors: Fabbri Andrea G. , Masounave Jaques
Published: August 2011

Picture processing using generalized instrumentation with specially developed software, and image analysis by means of a Quantimet 720 image analyser with a linear correlator, were employed in the study of rock textures. The boundaries of all individual grains from a portion of a thin section of a rock were distinguished and hand‐drafted for digitization and analysis. From the grey level image of boundaries of the profiles of the grains, obtained by hexagonal scanning of line drawings, binary images were produced for each phase and used for textural measurements. Ink drawings extracted from the boundary pattern were also used for the image analyser experiments.

In picture processing experiments, programmed structuring elements of different shapes and two‐dimensional autocorrelation functions were used to characterize morphology and spatial distribution of the different phases. Transformations of binary images were programmed at the bit level to reduce storage requirements and computing time. In Quantimet 720 experiments, linear erosion and histogram of sizes were used for computing the mean dimensions of the grains. Periodical arrangements were studied by means of the covariance function.

This contribution uses simple texture measures derived from mathematical morphology and picture processing methods, in order to assess the feasibility of two different technical approaches in the analysis of the same material. The extraction of image information from the material analysed, which was not attempted before, is cumbersome and technically complex. This difficulty is partly responsible of why little is known on the quantitative characterization of metamorphic textures from thin sections.
Cryofixation of monolayer cell cultures for freeze‐fracturing without chemical pre‐treatments
Authors: Pscheid P. , Schudt C. , Plattner H.
Published: August 2011

A cryofixation method is presented which gives excellent ultrastructural preservation of monolayer cell cultures without any chemical pretreatments. Rat hepatocytes in primary culture were used in this study. The equipment needed is inexpensive and easy to manufacture. Cells are grown on a usual tissue culture support material (Thermanox plastic sheets). For cryofixation, samples are prepared essentially by a combined sandwich‐cryogen‐jet technique. 3 mm large discs are punched out and sandwiched with Cu‐ or Au‐object holders of little mass; a 15 μm spacer is put in between. The viability of the cells is not impaired by the manipulations before freezing. The sandwich sample is quickly frozen by shooting a propane jet from a simple pressure chamber on to the metal object holder. The relevant parameters were optimized by parallel freeze‐fracture analyses of 5% glycerol as a model system and by thermocouple measurements. Sandwich samples are then mounted in an appropriate double replication specimen table for further analysis by freeze‐fracturing. It is possible to obtain a certain selectivity of the fracture plane with regard to apical, lateral or basal aspects of the cell layer. Alternatively, disc samples can be processed by chemical fixation methods (including freeze substitution to determine the freeze‐fracture plane), since the support material Thermanox is insensitive to organic solvents and easy to cut. In each case the cells remain attached to their substratum throughout the whole procedure. Thus, the ultrastructural data can be directly correlated with parallel functional analyses obtained from the same cell cultures.
Sodium localization in Suaeda maritima leaf cells using zinc uranyl acetate precipitation
Authors: Harvey Diana M. R. , Kent B.
Published: August 2011

The use of zinc uranyl acetate as a sodium precipitant was investigated during conventional fixation and freeze‐substitution preparations; it was superior to antimonate reagents insofar as it only precipitated Na+ and K+ (Ca2+ and Mg2+ were not detected) and could be used in conjunction with freeze‐substitution in acetone.
The use of a simple method to avoid cell shrinkage during SEM preparation
Authors: Wollweber Leo , Stracke Roland , Gothe Uwe
Published: August 2011

In the course of preparing specimens for scanning electron microscopy, both glutaraldehyde and OsO4‐fixed cells exhibit a considerable shrinkage with a reduction of the mean cellular diameter of about 45% after critical point drying. However, if cells are successively treated with glutaraldehyde, OsO4, tannic acid and uranyl acetate solutions, cellular shrinkage of only 5% is observed.
Spatially filtered images of B. subtilisα‐amylase crystals
Authors: Shelley Kirk , McPherson Alexander
Published: August 2011

Microcrystals of B. subtilis α‐amylase have been negatively stained and examined by electron microscopy. The micrographs were then subjected to spatial filtering and averaging using a Fourier transform procedure programmed for a mini computer. From these ‘enhanced’ images refined crystallographic parameters were obtained and a model for the packing of the asymmetric units within the crystal was derived. In addition, these parameters obtained from electron microscopy are compared with those derived from limited X‐ray diffraction data on macrocrystals of the same form.
Checking of linearity of the photoelectric system of a microscope photometer
Authors: Piller Horst
Published: August 2011

For accurate photometric measurements linearity between the measured property of the object, e.g. transmittance, reflectance, fluorescence intensity, and the measuring signal plays an important role. Although modern photoelectric equipment is designed to provide practically perfect linearity there may be factors by which linearity is disturbed, e.g. ageing, heating, improper operation of equipment, defects in electric circuits, etc. The three‐polar method described in this paper involves the most convenient and objective testing of linearity by the operator.
The suitability of various adhesives as mounting media for scanning electron microscopy: I. Epoxies, sprays and tapes
Authors: Witcomb M. J.
Published: August 2011

Fifty‐six relatively commonly used epoxies, sprays and tapes have been tested with respect to properties that are, or may be, important if they were to be used as scanning electron microscopy sample mounting adhesives. Recommendations are made as to the most appropriate adhesive for each type of mounting media.
An apparatus for freeze‐fracturing specimens of dermal collagen in preparation for scanning electron microscopy
Authors: Lamberty B. G. H. , Ellis C. B.
Published: August 2011

A new apparatus is described which facilitates the freeze fracturing of specimens under liquid nitrogen in preparation for scanning electron microscopy. The apparatus is simple and can be made by any competent engineering department.
Recording of chromosome banding with the Vickers M85/M86 scanning microdensitometer
Authors: Robinson K. , Hartmann‐Goldstein I. J. , Goldstein D. J.
Published: August 2011

An electronic interface is described which permits the Vickers M85/M86 microdensitometer to be used with a chart recorder to plot linear distance along a chromosome against (1) the absorbance, (2) the product of the chromosome width and the mean absorbance transverse to the long axis of the chromosome, or (3) the integrated absorbance accumulating during a two‐dimensional scan of the specimen.
Resolution in light microscope autoradiography using a carbon‐14 labelled line source
Authors: Vanroelen Ch. , Harrisson F. , Andries L. , Vakaet L.
Published: August 2011

Light microscope autoradiographs were prepared from a 14C line source. Two factors that affect resolution were studied: emulsion thickness and section thickness. The distribution around the line source was determined using the half‐distance (HD) value to quantify the resolution. An increase in HD value was observed with thicker sections or emulsion layers. The shape of the curve reflecting the grain density distributions around these line sources was very similar. After normalization in HD and relative grain density units, an average distribution was calculated and compared with the shape of normalized density distributions obtained from electron microscope autoradiographs. Other than a discrepancy near the source, an acceptable correlation was observed.
A new approach to the study of the E. coli nucleoid
Authors: Haggis G. H. , Bond E. F.
Published: August 2011

E. coli were examined by the freeze‐fracture thaw‐fix technique, embedded in thin fibrin gels. After glutaraldehyde fixation the bacterial nucleoid was found spread out over the surrounding fibrin. Addition of calcium and uranyl acetate to the fixative preserved the nucleoid in compact form. The spread nucleoid was then examined against a smooth mica background after freeze‐thaw and osmotic lysis. These spreads were critical‐point dried, rotary shadowed with platinum–carbon and viewed as stereo‐pair micrographs. Structures seen are tentatively interpreted as clusters of polyribosomes, extended DNA, and supercoiled DNA complexed with proteins or polyamines. After osmotic lysis, glutaraldehyde alone preserves the nucleoid in compact form. Only where strands are broken, in freeze‐fracture or freeze‐thaw lysis, must uranyl acetate be added to the fixative to preserve a compact structure.
The application of a normalized correlation function in image analysis
Authors: Vollath D.
Published: August 2011

This paper describes the use of normalized correlation functions, such as auto‐ and cross‐correlation functions for the analysis of images. The normalization is introduced to avoid problems of interpretation of the resulting correlation functions caused by the finite dimension of the image used for calculation.

Due to a reduction of noise in the correlation function it is possible to detect periodic structures, which are hidden by noise in the original image. Besides the normalization of the correlation functions, a modification of the correlation function by periodic continuation of the image is proposed. This leads in all cases where the structure allows this to a further drastic reduction of noise.

Besides the two‐dimensional correlation functions one‐dimensional correlation functions are proposed. It is shown that there are cases where it is difficult to find an adequate interpretation of these one‐dimensional functions.
The use of various buffers in the preparation of human lymphocytes for SEM observation
Authors: Abugaber Antoine A. , Lalague Elisabeth D. , Roy Adolphe , Champagne Marc R. , Cousineau Gilles H.
Published: August 2011

A study is presented of various buffers utilized in the preparation of human lymphocytes for scanning electron microscopy. Of nineteen different buffers tested, Hanks' balanced salt solution +0·04 mol sucrose appeared most adequate for satisfactory preservation of lymphocyte surface architecture.
Freeze‐drying shrinkage of glutaraldehyde fixed liver
Authors: Boyde Alan , Franc Frantisek
Published: August 2011

Dimensional changes were recorded during the freeze drying (FD) of 1 mm cubes of glutaraldehyde (GA) fixed adult mouse liver. The areas of the front faces of these blocks was measured using a Quantimet 720 image analysing computer system. Interpolating the first straight line portion of the graphs of size versus time backwards to the origin allowed the determination of the original size even if the specimen was covered with some surface‐water ice at the beginning of the experiment.

GA fixed mouse liver shrinks 7·3% linearly during freeze drying. This gross shrinkage is not increased if the cold stage temperature is raised to ∼263 K from ∼223 K, but the rate of drying as monitored by the rate of shrinkage is greatly increased. If morphological specimens are to be prepared for scanning electron microscopy (SEM), freeze drying can be completed rapidly after an initial period at ∼223 K, since ice recrystallization leading to increased ice crystal artefact will occur in the deep layers which will not be visible in the SEM.

Shrinkage of single cells followed during freeze drying in the SEM showed similar gross dimensional changes of about 7·5% linear shrinkage to occur at and below 198 K.
The design of terrestrial and aquatic micro‐environmental chambers for use in low powered video, cine and photomicrography
Authors: Lawrence Michael J.
Published: August 2011

The observation, recording and control of active biological specimens is time consuming and not easily achieved in low powered microscopy. To overcome this, perspex micro‐environmental chambers have been designed to enable the control of temperature, air and water flow, illumination and image format to suit individual species and specimens. When the chambers are in use, they are ‘closed’ systems and can be maintained for long periods; up to several days if required.

Two separate systems have been developed (aquatic and terrestrial) and both allow the use of integrated illuminated systems. The chambers are made from perspex and the viewing area, the ‘windows’, are made from high quality optical glass.

These chambers have been designed to match television format (3:4) and retain the specimen and ensure it remains in the field of view during a video, cine or photomicrographic recording session. The chambers can be used in vertical or horizontal observation systems and are attached to the microscope focusing substage. It also allows the use of incident and transmitted illumination systems including bright field, with or without polarized light observations, and dark field. The assembly of the chambers appears complex but is easily achieved.
The construction of invariant random paths through three‐dimensional specimens
Authors: Coleman Rodney
Published: August 2011

A quick way of constructing invariant random (IR) paths (sometimes called IUR or μ‐random) through three‐dimensional specimens is described. It uses the result that the secant joining two points chosen uniformly and independently on the surface of a sphere is IR.

An application of this result to the stereology of multiple phase spheres is briefly introduced.
High voltage electron microscopy of cell nucleus fractions: feasibility studies
Authors: Bourgeois C. A. , Zalta J. , Lacaze J. C. , Zanchi G. , Kihn Y. , Bouteille M. , Jouffrey B. , Zalta J. P.
Published: August 2011

Cell nucleus fractions were analysed in high voltage electron microscopes equipped with a hydration chamber and an energy filter, and the different filtering modes were tested. The best results were obtained when the energy filter was used as an analyser of atomic tracers specifically combined with RNA. Although the resolution thus obtained was relatively poor, the prospects of being able to observe hydrated organelles are encouraging.
An X‐ray microanalytical examination of precipitation methods for the ultrastructural localization of potassium in plant tissue: I. Cobaltinitrite
Authors: van Steveninck Margaret E. , van Steveninck R. F. M. , Mittelheuser Cathryn J.
Published: August 2011

In vitro and in vivo studies were carried out to assess the feasibility of adapting the cobaltinitrite method for the ultrastructural localization of K+ in plant cells. The relatively low mobility of the cobaltinitrite ion and the solubility of the precipitation product resulted in the formation of only a few large deposits in each cell. The addition of Ag+ at the time of precipitation was found to increase the number of small deposits retained in sections. However, cobaltinitrite reagents frequently caused plasmolysis and poor cytoplasmic preservation. Precipitation during freeze‐substitution was also attempted. It was concluded that precipitation of K+ using cobaltinitrite has only limited use in low magnification electron microscopy in conjunction with light microscopy.
Comparative mass measurement of biological macromolecules by scanning transmission electron microscopy
Authors: Freeman R. , Leonard K. R.
Published: August 2011

A method is described for measuring the mass/length or mass of molecular assemblies by comparative electron scattering in the STEM. Standard particles whose mass is well established (e.g. TMV or fd bacteriophage) are deposited on the electron microscope grid together with the sample to be measured. Images containing at least one sample and standard and with a clean, contamination‐free background are chosen and stored on computer disc and then directly integrated. Use of a comparative technique does not require accurate determination of scattering parameters or instrumental geometry and requires only that the limits of linearity be established.

The results of the mass/length measurements on phage pf 1, pili, muscle thick filaments and actin are in good agreement with existing molecular weight data and generally have a standard deviation of about 10%. The results for the total mass measurement of the multisubunit enzymes glutamate dehydrogenase and glutamine synthetase are also close to the literature values for their molecular weights. The results for the spherical, Semliki forest and tomato bushy stunt viruses are lower than expected, possibly reflecting some dissociation during preparation.
Comparative light microscopy, scanning electron microscopy and transmission electron microscopy of selected organic walled microfossils
Authors: Peat C. J.
Published: August 2011

Two simple techniques are described and illustrated. The first is for the study of one specimen by both light microscopy (LM) and scanning electron microscopy (SEM). The second is for the study of one selected specimen by LM, SEM and in ultrathin section by transmission electron microscopy (TEM). Although these techniques were developed for the comparative study of Precambrian organic walled microfossils (OWMs), they could be used for a wide range of other specimens.
Photoelectron microscopy of cell surface topography
Authors: Nadakavukaren Karen K. , Rempfer Gertrude F. , Griffith O. Hayes
Published: August 2011

Photoelectron micrographs of gold‐palladium coated mouse 3T3 cells and chick embryo fibroblasts are presented. Since the gold‐palladium suppresses differences in work function, the cell morphology seen in these micrographs is due to relief contrast. The heights of comparable cells were measured from the parallax present in transmission electron micrograph stereo‐pairs of cell surface replicas. The origin of relief contrast and the effect of cell surface relief on the working depth of field in photoelectron images of cells are discussed. The micrographs demonstrate that photoelectron microscopy is very sensitive to fine details of cell surface topography, and that the working depth of field is not a limiting factor in the imaging of well‐spread tissue culture cells.
A rapid method for identification of S‐phase cells in transmission electron microscopy of monolayer cultures
Authors: Alvey Peter L.
Published: August 2011

A rapid technique has been developed for identifying cells in S‐phase in transmission electron microscopy of monolayer cultures. Autoradiography is performed on the embedded monolayer which is then re‐embedded. The cells and the adjacent layer of developed emulsion are sectioned together, and when subsequently viewed in the electron microscope the cells in S‐phase appear with a zone of silver grains in the emulsion which is opposite their nuclei. They are thus readily identified and can be selected for detailed study. The advantages of this technique over conventional TEM autoradiography are the very much shorter exposure times and a reduced workload when preparing serial sections.
Modifications to the paper ‘On defining the thermal history of cells during the freezing of biological materials’
Authors: Bald W. B. , Crowley A. B.
Published: August 2011

Some of the figures published in the original paper Bald & Crowley (1979) have been modified to include a corrected value for the thermal conductivity of ice.
Ion beam sputtering: an improved method of metal coating SEM samples and shadowing CTEM samples
Authors: Clay Christopher S. , Peace Geoffrey W.
Published: August 2011

An apparatus to ion beam sputter‐coat SEM samples has recently become available. The equipment uses a small saddle‐field ion source to sputter deposit metals on to samples. This eliminates the surface artefacts seen at high magnifications on samples coated by diode sputtering. Ion beam sputtering has also been used to shadow samples for CTEM and has been found to result in a grain size of 1.2 nm.

This technique isolates the specimens from the high‐energy plasma and thus little or no heating of the sample occurs. The removal of the SEM samples from the high‐energy plasma and the use of diffusion pump vacuum conditions to prevent contamination are suggested as reasons for the improved coating quality over diode sputtering.
Comparison of two subsampling methods for electron microscopic morphometry*
Authors: Müller A. E. , Cruz‐Orive L. M. , Gehr P. , Weibel E. R.
Published: August 2011

The purpose of the present paper is twofold. Firstly, to compare the accuracy per unit cost achieved by two different methods of subsampling micrographs from sections of a material for stereology when the sections cannot be analysed as a whole at the required magnification. Secondly, to illustrate, by means of real data, the application of some of the methods and formulae proposed in the companion paper (Cruz‐Orive & Weibel, 1981) for estimating ratios at the electron microscopic level.

The final estimates of a same ratio obtained by either subsampling method (namely systematic (SQ) and systematic area‐weighted quadrats (SAWQ)) agreed in the mean and they were about equally precise. The former fact indicates that the new SAWQ method is at least as reliable as the SQ method as far as bias is concerned. The latter result is a consequence of the well‐known fact that subsampling is relatively unimportant in two‐stage sampling. Yet, SAWQ subsampling enjoys definite practical advantages over other subsampling methods in certain situations.
A new en bloc stain for cell membranes: tannic methylamine tungstate
Authors: Skaer R. J.
Published: August 2011

A new stain is described that combines the mordanting and preservative effects of tannic acid with very strong staining, particularly of plasma membranes. The staining is sufficiently intense in some cell types to reveal frequent links between the outer and the inner leaflet of the plasma membrane.
A modification of the oil emulsion freezing technique for freeze‐etching studies of hydrogels
Authors: Buchheim Wolfgang , Hermansson Anne‐Marie
Published: August 2011

A preparation technique is described which is especially applicable to hydrous gels and allows an improved cryofixation of such systems for freeze‐etching. The method is a modification of the oil emulsion freezing technique where the gelling system is dispersed in liquid paraffin before sol‐gel transformation. Gel formation within the microscopically small sol droplets is then induced, e.g. by suitable thermal treatment. The effectiveness of this technique has been demonstrated with heat‐induced soy protein gels.
The fixation, dehydration, drying and coating of cultured cells for SEM
Authors: Brunk Ulf , Collins V. Peter , Arro Erik
Published: August 2011

Cultivated cells form a valuable model system for studies on the effects of various preparative protocols for scanning electron microscopy (SEM). The various effects of each preparative step can be followed in detail in the light microscope and no diffusion gradients complicate the fixation and other procedures as in the case of solid tissues.

Studies on cultivated cells indicate that the glutaraldehyde component of a glutaraldehyde‐based fixative does not contribute to the effective osmotic pressure of the fixative and thus the osmolarity of the buffer, and other components, must be equalized to that of the medium in which the cells grow. Even small deviations from this ideal effective osmotic pressure will result in osmotically induced artefacts.

Disturbances of pH and temperature of the cultures prior to and during fixation will result in changes in the appearance of many cellular structures such as microspikes and ruffles.

We find that osmium fixation is advisable in most instances for best possible membrane preservation and that even long periods of glutaraldehyde fixation do not compensate for osmium fixation.

Dehydration always results in shrinkage. Freeze drying (FD) and critical point drying (CPD) also give rise to shrinkage, the former to a lesser degree than the latter.

A gold‐palladium alloy gives a less granular coating that does gold alone. When cultured cells are studied, a metal thickness of between 5 and 15 nm is usually sufficient to give rise to an adequate secondary electron production and to avoid charging even at accelerating voltages of 30–40 kV. Without treatment with OsO4 a thicker metal coating is required.
Applications of the SEM to the analysis of morphogenetic events
Authors: England Marjorie A.
Published: August 2011

Scanning electron microscopy (SEM) is a valuable tool for the analysis of morphogenetic events. The role of extracellular materials in primary neural induction in the early stage 5 chick embryo may be analysed by SEM as well as by histochemical techniques.

During primary neural induction, extracellular materials in the early stage 5 chick embryo form a fan‐shaped region on the ectoderm anterior to Hensen's node. Fibronectin and sulphated glycosaminoglycans are present anterior to Hensen's node on the ventral ectoderm layer. It is proposed that the fanshape of extracellular materials has a dual function; as a chemical substrate to form close contacts between the inducing cells and the target ectoderm cells, and to serve as a contact guidance system for the pre‐notochordal cells.
Scanning electron microscopy in biomedical research and routine pathology
Authors: Carr K. E. , Toner P. G.
Published: August 2011

After 15 years of development, scanning electron microscopy now plays a major role in biomedical science. This brief review highlights some aspects of the contribution of SEM to the teaching of morphology, to experimental scientific research and to pathological diagnosis.
Cell surface labelling with gold colloid particulates: the use of avidin and staphylococcal protein A‐coated gold in conjunction with biotin and fc‐bearing ligands
Authors: Tolson N. D. , Boothroyd B. , Hopkins C. R.
Published: August 2011

Procedures for preparing gold colloid particles stabilized with either avidin or protein A are described. Methods of using these general utility tracers for localizing biotinylated and fc bearing immunoglobulins are outlined and, as examples of the way in which these methods can be applied, procedures for identifying epidermal growth factor receptors and surface fibronectin on ovarian granulosa cells are described.
Some aspects of quantitative STEM X‐ray microanalysis*
Authors: Jones I. P. , Loretto M. H.
Published: August 2011

Those aspects of quantitative X‐ray microanalysis of thin films which either differ from, or do not exist in, bulk specimen analysis are reviewed. Special emphasis is placed on electron trajectory‐linked effects, and on surface polishing films.
The quantitation of electron energy loss spectra
Authors: Joy David C. , Maher Dennis M.
Published: August 2011

An interactive computer program which allows the quantitation of electron energy loss spectra is described. The program performs a standardless analysis using hydrogenic cross‐section models. The accuracy of the results obtained for a wide range of experimental conditions is typically within 20% of expected values for well characterized samples. The lack of agreed thin film standards is a limit to the improvement of the cross‐section models, but under most practical operating conditions the largest errors arise from instrumental factors such as the effect of finite beam convergence and chromatic errors in the coupling optics.
An application of EELS in the examination of inclusions and grain boundaries of a SiC ceramic
Authors: Bourdillon A. J. , Jepps N. W. , Stobbs W. M. , Krivanek O. L.
Published: August 2011

Electron energy loss spectroscopy (EELS) has been used in conjunction with high resolution microscopy (HREM) to identify second phase regions in polycrystalline SiC ceramic compacts. Most inclusions were graphitic and contained no boron, though some borides were also identified. Boron could not be detected at grain boundaries, so its role in sintering remains unclear.
A microcomputer‐based system for stereogrammetric analysis
Authors: Roberts S. G. , Page T. F.
Published: August 2011

A system for the quantitative analysis of stereo‐pairs of photomicrographs has been devised using a Commodore ‘PET’ microcomputer coupled to a digitizing pad, plotter and printer. The system need not use any form of stereo‐viewer and does not require any particular alignment of the photographs. Height differences, derived from parallax measurements, can be obtained quickly even by operators who might normally experience difficulties with stereoscope‐based systems due to either poor stereo vision or inexperience. Three‐dimensional coordinates, input from point‐pairs, are stored inside the computer and may be sorted to draw line profiles along any operator‐selected line. Such profiles may be referred to either the projection of the median plane of the two images or rotated (‘levelled’) to the 0° tilt plane.

The operation of the system is described and illustrated using both specially‐constructed left‐ and right‐hand ‘images’ from test contours and also real SEM stereo pairs. Finally, both the potential and limitations of such a system for development and application are discussed.
Evaporation behaviour of metallic aerosol condensates
Authors: Buckle E. R. , Tsakiropoulos P.
Published: August 2011

The particles in sediment from condensation aerosols of zinc and cadmium were exposed to hot, inert gas or radiant heat to investigate the structure revealed by evaporation. The smallest prisms retained their shape but the larger ones evaporated back to the dendritic form characteristic of an earlier stage in their development. It is concluded that large prisms grow with a flawed structure because of strain present in the dendritic skeleton.

On spheres, the curved surface surrounding the basal flat tends to become smoother on evaporation of the vapour‐grown layer texture although deep pits develop eventually. The texture opposite the flat, where the growth helix emerges from the solidifying melt, is more persistent. The basal flat remains flat, indicating that the high degree of crystalline perfection achieved in the slowly‐growing basal raft is retained after solidification.
Lichen weathering of rock‐forming minerals: application of scanning electron microscopy and microprobe analysis
Authors: Jones D. , Wilson M. J. , McHardy W. J.
Published: August 2011

Using the scanning electron microscope with microprobe analysis, observations have been made on the weathering of rock‐forming minerals—feldspars, ferromagnesian minerals, quartz and serpentine—principally by crustose lichens. A variety of phenomena can be recognized, namely, etching patterns, decomposition features and secondary products which can be related to differences in mineral structure and composition. Such weathering has been proved to involve the chelating effects of oxalic acid in certain lichens, although lichen acids could also be implicated.
A STEM/X‐ray microanalytical study of the equilibrium segregation of bismuth in copper
Authors: Baumann S. F. , Williams D. B.
Published: August 2011

Combined scanning transmission electron microscopy (STEM) and X‐ray microanalysis have been used to detect the equilibrium segregation of bismuth to grain boundaries in copper. Quantification of the X‐ray data gives grain boundary bismuth concentrations close to those reported previously by Auger electron spectroscopy (AES). Samples tempered at low temperatures (773,873 K) had detectable bismuth concentrations at more boundaries than those samples tempered at high temperature (1073 K). There is evidence that the degree of segregation varies strongly from boundary to boundary.
The use of propane/isopentane mixtures for rapid freezing of biological specimens
Authors: Jehl B. , Bauer R. , Dörge A. , Rick R.
Published: August 2011

The use of propane/isopentane mixtures as cooling media is proposed since they remain fluid at liquid nitrogen temperature. The attainable cooling rates are virtually identical to those obtained in liquid propane.
Electron probe analysis of microdroplets: Factors affecting the proportionality between measured X‐ray intensity and concentration
Authors: Roinel Nicole
Published: August 2011

Factors liable to limit the validity of liquid sample analysis by electron microprobe are investigated. For lyophilized samples composed of large 2–6 μm crystals, linear calibration curves may still be obtained for Na, Mg, P, Cl, K and Ca by raising the accelerating voltage to 18 kV, provided the X‐ray take‐off angle of the electron microprobe is 40°. Routinely prepared lyophilized samples are composed of discrete crystals. Their size is reproducible, depending on the composition of the dried deposit, and ranges from 0.1 to 0.5 μm for deposits mainly composed of NaCl. Within this range, the proportionality of X‐ray intensity to concentration is not affected by particle size. The concentration range for which X‐ray intensities remain proportional to concentrations is experimentally determined for the six elements above as a function of sample mass thickness and accelerating voltage. For certain elements, the proportionality constant is shown to vary with the composition of the solution. As regards chlorine concentration determinations, analysis of plasma ultrafiltrate and recovery experiments suggest that the proportionality constant is definitely 10% higher for this ultrafiltrate than for standard solutions.
A pipetting device for staining electron microscopic grids
Authors: Goodman Steven L.
Published: August 2011

A simple device for staining EM grids in small batches is described. The device easily produces high quality well‐stained grids and is adaptable to most stain techniques.

The most common method for staining EM grids is certainly the droplet technique (Kay, 1965) in which grids are individually floated, section‐side down, on droplets of stain. Since this requires repeated handling, electron microscopists have devised various methods for batch staining. These generally fall into two categories: partitioned grid boxes which are either immersed in, or filled with stain (Sjostrom et al., 1973; Polysciences Inc., EM Multiple Grid Staining Unit*), and clamp arrangements which grip a number of grids while they are placed in various baths (Baratz, 1976; Fisher, 1972; Gorycki, 1966; Hiraoka, 1972; Robertson & Roberts, 1972; Springer, 1974). These types of devices increase contrast and detail, over the droplet technique, by staining both section surfaces (Shalla et al., 1964). However, these require large and/or open baths of stain which are wasteful and prone to contamination. Contamination is especially critical with lead stains which precipitate lead carbonate on exposure to air (Peachy, 1959).

Recently, Forsdyke (1979) described a flow‐through tube for staining. The device consists of an S‐tube with an internal grid holder. Stains are introduced into the tube by siphon. This arrangement greatly reduces the amount of stain required as well as the air‐stain interface. This paper details an adaptation of Forsdyke's device designed for easier handling, flexibility in use, and further improved staining quality.

The device described herein is used to draw a few millilitres of stain directly from their containers, thus reducing contamination, air exposure, and waste. The device is used as the first receptacle for freshly cut sections on grids. The grids remain in the closed device until all sectioning and staining is completed. Since the device is closed all the sections remain damp, including those first prepared, until stained. In our laboratory we have observed that epoxy embedded tissue sections stain more evenly and intensely with uranyl acetate and lead citrate when kept moist prior to staining. Shalla et al. (1964) also reported improved staining of moist sections for another stain and different embedding plastics.
Values of K‐shell partial cross‐section for electron energy‐loss spectrometry
Authors: Egerton R. F.
Published: August 2011

Making use of a hydrogenic approximation, partial cross‐sections for K‐shell ionization are calculated for the elements beryllium to fluorine. The cross‐sections are presented graphically as a function of collection angle, for 60, 80 and 100 keV incident electrons and for energy windows of 50, 70 and 100 eV.
Automation of a microprocessor electronic flash for photomicrography
Authors: Batson B. S. , Lloyd P. C.
Published: August 2011

A method is described for the adaptation of a commercially‐available photomicroscope in order that the automatic facility of a microprocessor electronic flash may be used.
Electron microscopy of PbO2 deposited on a titanium substrate
Authors: Stevens R. , Gilroy D.
Published: August 2011

The nucleation and growth of lead dioxide on titanium substrate has been observed using scanning electron microscopy. The size and morphology of the PbO2 nodules have been measured in an attempt to elucidate the nucleation and growth mechanism. The effects of temperature, current density and fluorine ion addition have been qualitatively determined.

The structure of a film of PbO2 formed on the titanium has been examined using TEM and found to be heavily strained and to contain lattice defects such as dislocations and stacking faults.
The microstructure of non‐ohmic zinc oxide ceramics
Authors: Trontelj Marija , Kolar D. , Kraŝevec V.
Published: August 2011

The microstructure and the nature of some crystal phases in non‐ohmic ZnO ceramics containing 0·5 Bi2O3, 0·5 CoO, 0·5 MnO and 0·5 TiO2 mol% were investigated by using various analytical techniques. The ceramics consist primarily of ZnO grains, and in addition, two titanium containing phases were found, a needle‐like Zn2TiO4 spinel phase doped with bismuth and cobalt, and a cubic‐Zn2Ti3O8 phase with some cobalt and manganese. The Bi2O3 phase among the grains was found to be TiO2 stabilized γ* Bi2O3.
Polarizing light microscopy of intestine and its relationship to mechanical behaviour
Authors: Fackler K. , Klein L. , Hiltner A.
Published: August 2011

The polarizing optical microscope has been used to observe morphologically the effect of stress on rat and bovine intestine. Collagen fibres about 6 μm in diameter were found to be biaxially oriented at approximately +30° and −30° to the longitudinal direction. The fibres are arranged in layers with the fibres in each layer densely packed in parallel undulating arrays. The undulations give rise to the extinction pattern observed in the polarizing optical microscope. The initial response to stress is straightening of the fibres. Gradual straightening of the fibres is related to the increasing stiffness of the tissue observed in the stress‐strain relationship. Once the fibres are straightened, the biaxial orientation of the fibres produces higher strength in the longitudinal direction than in the transverse direction. This organization of intestinal collagen fibres has not been reported previously and is not observed in other biaxial tissues such as skin and aorta. Thus, intestine is a unique tissue for studying the relationships of mechanical behaviour to structure and organization of collagen.
Cutting wood specimens for observation in the scanning electron microscope
Authors: Kuĉera Ladislav J.
Published: August 2011

This report deals with the cutting of wood specimens for observation in the scanning electron microscope. Several cutting devices and types of knives are described and critically evaluated.
Shadow photography: An aid to microscopy
Authors: Edgerton Harold E.
Published: August 2011

The use of a small‐size electronic flash lamp, as a point source, makes possible a useful system for recording silhouette photographs of many subjects, such as plankton. Limitations of conventional microscopy methods, such as (1) small areas covered, (2) depth of field, and (3) subject motion, are partly overcome for some examples.
Optimizing thin film X‐ray spectra for quantitative analysis
Authors: Nicholson W. A. P. , Gray C. C. , Chapman J. N. , Robertson B. W.
Published: August 2011

Energy dispersive X‐ray detectors are frequently attached to electron microscopes to enable microanalysis to be performed, but because such detectors accept X‐rays generated within an appreciable solid angle, the recorded spectra usually include some spurious contributions from the instrument. This paper describes instrumental modifications firstly to reduce and secondly to permit the subtraction of the residual extraneous contributions. The probable accuracy of this subtraction procedure is examined.

Results are presented showing the effects of various instrumental modifications on spectra from thin specimens and demonstrate that by careful attention to experimental details it is possible to separate the spectrum due to the thin specimen alone from all other extraneous signals.

Two test specimens and a number of test procedures for investigating the analytical performance of (scanning) transmission electron microscopes are presented.

Sources of error and the method of their correction when the thin specimen Bremsstrahlung is used for quantitative analysis are discussed.
Multiplexed time‐lapse photomicrography of cultured cells
Authors: Heye R. R. , Kiebler E. W. , Arnzen R. J. , Tolmach L. J.
Published: August 2011

A system of cinemicrography has been developed in which a single microscope and 16 mm camera are multiplexed to produce a time‐lapse photographic record of many fields simultaneously. The field coordinates and focus are selected via a control console and entered into the memory of a dedicated microcomputer; they are then automatically recalled in sequence, thus permitting the photographing of additional fields in the interval between exposures of any given field. Sequential exposures of each field are isolated in separate sections of the film by means of a specially designed random‐access camera that is also controlled by the microcomputer. The need to unscramble frames is thereby avoided, and the developed film can be directly analysed.
Effects of glutaraldehyde fixative osmolarities on smooth muscle cell volume, and osmotic reactivity of the cells after fixation
Authors: Lee R. M. K. W. , McKenzie R. , Kobayashi K. , Garfield R. E. , Forrest J. B. , Daniel E. E.
Published: August 2011

The contribution of glutaraldehyde (GA) to the effective osmolarity of GA fixatives, the osmotic reactivity of the cells after fixation in GA, and also the duration of fixation in GA on cell volume, were investigated using cultured smooth muscle cells (SMC) and spiral aortic strips. Four fixation procedures were studied. We found that GA contributes to the total effective osmolarity of the fixatives, and that the type of buffers used for the fixatives can also affect the cell volume differently during GA fixation. After GA fixation, the cells were still osmotically reactive, regardless of the buffer types for making up the GA fixatives, so that the osmolarity of the wash buffer after GA fixation is important. However, OsO4 eliminates osmotic responses, thus the osmolarity of OsO4 fixative and wash buffer have negligible influence on the cell volume. Longer fixation time up to 4 h had no effect on the cell volume.
Simple procedures for evaluating the cryofixation of biological samples
Authors: Costello M. J. , Fetter R. , Höchli M.
Published: August 2011

Ultra‐rapid cooling of biological material can be achieved in the absence of cryoprotectants by using thin samples. Three methods now employed to prepare thin samples for freeze‐fracture electron microscopy are compared: contacting the sample against a liquid helium‐cooled copper surface (Heuser et al., 1979), spraying the sample with a jet of propane (Mueller et al., 1980), and plunging a streamlined copper ‘sandwich’ into liquid propane (Costello, 1980). In the first method a thin surface layer of the sample is ultra‐rapidly cooled while in the other methods the entire sample sandwiched between sheets of conducting metals is cooled. The morphology of fracture‐faces of dilauryllecithin‐water systems is used to evaluate the effectiveness of cooling methods. At optimum cooling rates the initial disordered arrangement of lipid in the lamellar (Lα) phase is preserved, giving smooth fracture faces. At slower cooling rates a worm‐like texture appears which signals the formation of molecular ordering characteristic of the Pβ, phase. All three methods are capable of cooling these lipid‐water phases as well as other more dilute aqueous suspensions without evidence of ice crystal growth or damage. Measurement of cooling rates employing miniature thermocouples embedded in samples indicates that rates for all three methods are in excess of 10,000 K/s. The propane jet (32 times 103 K/s, slope at 273 K) exposes the sample to coolant more rapidly than the sandwich plunging method (10 times 103 K/s, slope at 273 K) and therefore produces slightly higher cooling rates for samples of equivalent mass and thickness. Each method has its advantages. The contact method is well suited for tissues; the sandwich method is simple and inexpensive; the jet method can potentially produce the highest cooling rates. The last two methods yield complementary replicas.
Chemical cryoprotection for structural studies
Authors: Skaer Helen
Published: August 2011

With the ascendency of techniques for ultrarapid cooling and the successful control of ice crystal damage by purely physical means, it has become necessary to make a case for the continued use of chemical antifreeze agents in any circumstances. These circumstances include the need to explore tissues deeper than those superficial layers, whose morphology can be preserved by ultrarapid cooling, the avoidance of superficial areas of damage inflicted by dissection and tissue slicing, and situations where the growth of ice crystals must be controlled throughout the specimen, as for example for the cutting of frozen sections.

The control of ice crystal damage would ideally be by the avoidance of any freezing at all but in practice can be seen in terms of the control of ice crystal size, which in turn depends on the density of nuclei that develop in the specimen and the rate of accretion of water molecules to the crystallites that form on these nuclei. Chemical antifreeze agents act in a variety of ways to increase the density of nuclei and/or to reduce the rate of growth of ice crystals: by promoting nucleation, by enhancing subcooling and by increasing the viscosity of the extracellular medium. In this way, large numbers of small ice crystals are produced. The different types of cryofixative agent each have their own advocates, advantages, special applications and drawbacks and these must be taken into account when considering the range of methods available for the analysis of cryofixed material.
Cryoultramicrotomy: evidence against melting and the use of a low temperature cement for specimen orientation
Authors: Karp R. D. , Silcox J. C. , Somlyo A. V.
Published: August 2011

A technique is presented showing the use of toluene as a low temperature cement to attach portions of frozen tissues in the desired orientation on to the cryoultramicrotome chuck. Examples of transverse sections of skeletal and vascular smooth muscle are illustrated. Electron probe analysis of these sections indicates that the distribution of elements is maintained.

Evidence is presented against through section melting based on sectioning toluene at a temperature just below its melting point (178 K). Toluene was sectioned (about 100 nm thickness) successfully at three block temperatures (177, 163 and 113 K) when the knife temperature was by 1 degree or more colder than the m.p. of toluene. In all cases the toluene sections melted when the knife temperature reached 178 K. We conclude that sufficient heat is not generated and/or transferred to the toluene sections during cryosectioning under our conditions to raise the temperature of a 100 nm section by 1 K or more.