bluuebunny/crossref_metadata_2025_split huggingface dataset:
Improved tables for the evaluation of sphere size distributions including the effect of section thickness
Authors: Rose P. E. 
Published: August 2011

SUMMARYThe problem of determining the size distribution and population density of a population of spherical particles randomly distributed throughout a transparent matrix from data obtained by transmission microscopy on parallel plane‐faced sections of known field area and thickness may be readily solved by the use of matrix algebra. The solution presented in this paper may be used to construct conversion matrices whereby the particle size distribution and the numerical density can be calculated directly from the frequency distribution of the observed diameters; the only mathematical processes necessary being multiplication and addition.Specimen conversion matrices valid for a wide range of conditions are presented in the appended tables.
Effects of glutaraldehyde and glycerol on freeze‐fractured Escherichia coli
Authors: Arancia G. , Valente F. Rosati , Crateri P. Trovalusci 
Published: August 2011

SUMMARYGlutaraldehyde and glycerol are widely used in the freeze‐fracture technique as sample pretreatments before rapid freezing. However, they can both introduce relevant structural changes and influence the visualization of the fracture faces and surfaces of membranes. A comparison of the results obtained on E. coli cells differently pretreated with glutaraldehyde and glycerol is presented. In particular the effect on the distribution and density of the intramembranous particles (IMP) is pointed out. Glycerol treatment at 310 K introduces an IMP redistribution, outlined by the appearance of several smooth areas on the fracture faces of the cytoplasmic membrane, which is prevented by glutaraldehyde prefixation at the same temperature. On the other hand, glutaraldehyde treatment at 310 K following glycerol incubation results in the disappearance of the smooth areas, suggesting a substantial change in the IMP distribution caused by the fixative. Cells shifted down to 277 K and treated with glycerol at this temperature before quick‐freezing, present on the convex fracture face of the cytoplasmic membrane large smooth areas resulting from a lipid transition while the smaller areas observed at 310 K are not detectable. Glutaraldehyde treatment at 277 K seems also to be responsible for a redistribution of IMP since poorly delimited large smooth areas, containing several IMP, can be observed. In this paper the results of a statistical analysis are also reported, showing that the IMP density can be strongly influenced by pretreatments.
Stereometry as an aid to stereological analysis
Authors: Howell P. G. T. 
Published: August 2011

SUMMARYAccurate measurements for the stereological analysis of rough or curved surfaces are not always possible with single images from the light microscope or the scanning electron microscope (SEM). A second image recorded to form a stereo pair provides the information about the topographic nature of the surface. This paper presents two methods by which stereo pair scanning electron micrographs can be measured to give area fractions or other geometric parameters of rough surfaces.
A quantitative study of the preparation of rabbit aortic endothelial cells for scanning electron microscopy
Authors: Mcgarvey Kathleen A. , Reidy Michael A. , Roach Margot R. 
Published: August 2011

SUMMARYQuantitative studies were done with the scanning electron microscope (SEM) on aortic endothelial cells from ten rabbits. Of these, five were plastic casts and five were dehydrated with three different, but standard, techniques. The results indicated that all forms of dehydration caused significant shrinkage artefacts and that these were different in different directions in both the thoracic and abdominal aorta. The greatest shrinkage was found with the critical point drying technique, 45% in the abdominal aorta and 31% in the thoracic aorta. In the abdominal aorta this shrinkage was mainly due to a shrinkage in length (36%) rather than a shrinkage in width (15%). In comparison, in the thoracic aorta critical point drying resulted in a 15% shrinkage in length and a 19% shrinkage in width. Air drying and alcohol dehydration caused considerable shrinkage (29% and 18% respectively in the thoracic aorta, 29% and 36% respectively in the abdominal aorta). Directional differences were also found with these techniques, for instance alcohol dehydration in the thoracic aorta resulted in 0% shrinkage in length and 18% shrinkage in width.
Time resolved cathodoluminescence in the scanning electron microscope by use of the streak technique
Authors: Hastenrath M. , Balk L. J. , Löhnert K. , Kubalek E. 
Published: August 2011

SUMMARYMinority carrier lifetime is one of the basic material properties in optoelectronic devices and material. Both the micrometer range dimensions of the devices and lifetime variations around defects in materials require a lifetime measurement technique with both high spatial and high temporal resolution. In order to meet these requirements a highly efficient cathodoluminescence (CL) measurement system has been developed consisting of a commercial scanning electron microscope extended for integral and spectral CL‐measurements and a streak camera with subnanosecond time resolution as time resolving detector. The lifetime is determined by evaluation of CL‐decay time after excitation of the specimen by an electron beam pulse, which is blanked in less than 50 ps by an adjustable plate capacitor. The CL‐light is collected by an adjustable, ellipsoidal mirror and can be dispersed in a vacuum monochromator. The monochromator exit slit is imaged on to the photocathode of the streak camera, which transforms the temporal distribution of the photon intensity into a lateral distribution on the camera phosphor screen after amplification by an integrated microchannel plate. By this technique it is possible to record the complete CL‐decay simultaneously, thus avoiding all measurement falsifications by system instabilities. The resulting intensity distribution is read out by a SIT vidicon camera with subsequent multichannel analyser, providing an intensity plot versus streak time in less then 1 min for each beam spot location. The technique is therefore well suited for lifetime mapping experiments. The best time resolution of the complete system achieved today is about 100 ps. Its performance is here demonstrated by measurements of the temperature dependence of the CL‐decay in a highly Se‐doped GaAs specimen in the temperature range from 90 K to 300 K.
SEM—EBIC studies of boron implanted silicon
Authors: Ioannou D. E. , Davidson S. M. 
Published: August 2011

SUMMARYKnown SEM‐EBIC techniques based on Schottky diode and p‐n junction charge collectors are modified or further developed in order to study the radiation damage and the minority carrier diffusion length and lifetime in boron implanted silicon, and their annealing behaviour.
The characterization of distortions in heteroepitaxial structures by X‐ray multiple diffraction
Authors: Brown B. R. , Halliwell M. A. G. , Isherwood B. J. 
Published: August 2011

SUMMARYX‐ray multiple diffraction can be used to characterize distortion in heteroepitaxial layers non‐destructively. The basic technique and its application to gallium aluminium arsenide layers on gallium arsenide is described. The lattice parameters of the layers can be found and hence their composition. The diffraction patterns obtained confirm that layers grown on off‐axis substrates grow tilted with respect to the substrate.
Size determination of sonicated vesicles by freeze‐fracture electron microscopy, using the spray‐freezing method
Authors: Van Venetië R. , Leunissen‐Bijvelt J. , Verkleij A. J. , Ververgaert P. H. J. Th. 
Published: August 2011

SUMMARYThe usefulness of spray‐freezing for determining the sizes of sonicated vesicles of egg lecithin with various cholesterol concentrations has been demonstrated. It is found that vesicles of egg lecithin increase in average size with increasing cholesterol concentrations, in agreement with measurements obtained with other techniques.
Phosphorus standards for the electron probe X‐ray microanalysis of ultrathin tissue sections
Authors: Weakley Brenda S. , Weakley Timothy J. R. , James John L. 
Published: August 2011

SUMMARYPhosphorus‐containing standards for use during quantitative electron probe X‐ray microanalysis of ultrathin tissue sections can be quickly and simply prepared using organo‐phosphorus compounds which are soluble in Spurr's epoxy resin mixture. Trials of five such compounds (one solid, the rest liquid) are described.
Electron phase microscopy at 1 MeV with graphite crystal supports
Authors: Hines R. L. 
Published: August 2011

SUMMARYThin phase objects can be seen with good contrast with 1 MeV electrons if they are supported on a graphite crystal approximately half an extinction distance thick and viewed near 101 or 112 bend contours. The shape of unstained tobacco mosaic virus is easily seen with crystal phase contrast although it is almost invisible in a normal bright field micrograph taken with 1 MeV electrons. Phase contrast images of both TMV and 109 nm diameter latex spheres are observed to be bright against a grey background on one side of a 101 or 112 bend contour and dark against a grey background on the other side of the bend contour. For strong contrast the crystal diffraction vector g must have a component parallel to the beam. Contours such as 100 and 110 do not give strong phase contrast. The phase contrast images for biological material gradually increase in contrast as the specimens are irradiated by the electron beam. An electron exposure of about 104 electrons nm−2 is required to obtain maximum contrast.
Dye binding mechanisms in G‐banding of chromosomes
Authors: Sumner A. T. 
Published: August 2011

SUMMARYThe mechanisms whereby Giemsa is bound to chromosomes to produce G‐banding patterns have been studied. The magenta colour produced in chromosomes by Giemsa staining appears to be due to the same 2:1 thiazine‐eosin compound that precipitates from Giemsa solutions. This precipitate is formed in chromosomes in regions in which DNA phosphates occur at the correct distance apart to bind two thiazine molecules, which are subsequently able to bind to the same eosin molecule. Banding appears to be produced as a result of this precipitation occurring preferentially in hydrophobic regions of chromosomes.
Principles of TEM contrast simulations of inclined interfaces in homogeneous crystals
Authors: Gratias D. , Portier R. 
Published: August 2011

SUMMARYThe scattering matrix formalism used for the cases of translation and inversion boundaries is generalized to any type of interface in homogeneous crystals. The present method needs no arbitrary decompositions of the diffracting sets in the lower crystal. It leads to conditions of stacking‐fault‐like contrast, different from those proposed by Sutton & Pond, in agreement with experiments.
Description of a coverslip holder for, and observations on, the critical point drying of cell cultures
Authors: Evers P. , Robinson K. , Maistry L. , Higginson E. 
Published: August 2011

SUMMARYThe elimination of artefact during the preparation of cell cultures for scanning electron microscopy is difficult. Collapse of cellular projections, cytoplasmic cracks, perforations and fracturing of cell‐cell processes and cell‐substrate attachments occur during fixation, dehydration and critical point drying. Coating and storage may cause further artefact. A specimen holder which serves to minimize turbulence in the critical point dryer and which allows for the simultaneous processing of up to five coverslips, as well as a reproducible technique for the preparation of cell cultures are described.
A digital computer technique for orientation analysis of micrographs of soil fabric
Authors: Tovey N. K. 
Published: August 2011

SUMMARYSeveral methods exist for quantifying soil fabric information from electron micrographs, but hitherto little interest has been shown in digital computer techniques. This paper describes such a method for the quantitative analysis of the orientation of clay particles in electron micrographs. The intensity distributions across several micrographs have been digitized at up to two million picture points and the data stored on magnetic tape. By examining the gradient of the intensity variations in two orthogonal directions, the resulting intensity gradient vector at each point can be determined. The information from all points in a micrograph can then be plotted as a rosette diagram, or used in a regression analysis to determine the equation of the ellipse which most closely approximates the actual rosette distribution. Finally an index of anisotropy can be estimated from the major and minor axes of the ellipse.
The use of high resolution microscope photometry in the discrimination of chromosome bands
Authors: Wayne A. W. , Sharp J. C. 
Published: August 2011

SUMMARYHigh resolution microscope photometry was used to discriminate between regions of differing density along the length of a banded metaphase chromosome. It has been demonstrated that photometry can be performed on such material to give a higher level of effective resolution than has hitherto been obtained. Using conventional visible light microscope photometry it is possible to obtain useful comparative densitometric information from measurements performed at a point separation equivalent to 0.05 μm in the object plane. The practical details of the equipment employed and the theoretical basis of the study are discussed.
Stereological formulae based upon planar curve sections of surfaces in space
Authors: Miles R. E. 
Published: August 2011

SUMMARYAttention is paid to the random curve (or curves) of intersection of a fixed surface in a spatial specimen by a random plane through that specimen. A formula is given for the expectation of the integral of a general function of curvature along that curve. This in turn yields a large family of formulae for stereological ratios.
On the use of the geodesic metric in image analysis
Authors: Lantuejoul C. , Beucher S. 
Published: August 2011

SUMMARYLet X be a phase in a specimen. Given two arbitrary points x and y of X, let us define the number dx(x, y) as follows: dx(x, y) is the greatest lower bound of the lengths of the arcs in X ending at points x and y, if such arcs exist, and + ∞ if not. The function dX is a distance function, called ‘geodesic distance’. Note that if x and y belong to two disjoint connected components of X, dx(x, y) = + ∞. In other words, dx seems to be an appropriate distance function to deal with connectivity problems.In the metric space (X, dx), all the classical morphological transformations (dilation, erosion, skeletonizations, etc.) can be defined. The geodesic distance dx also provides rigourous definitions of topological transformations, which can be performed by automatic image analysers with the help of iterative algorithms.All these notions are illustrated with several examples (definition of the length of a fibre; automatic detection of cells having at least one nucleus, or having exactly a single nucleus; definitions of the geodesic centre and of the ends of a particle without holes, etc.). As an application, a general problem of segmentation is treated (automatic separation of balls in a polished section).
Resolution effect on the stereological estimation of surface and volume and its interpretation in terms of fractal dimensions
Authors: Paumgartner D. , Losa G. , Weibel E. R. 
Published: August 2011

SUMMARYEstimating surface and volume density of subcellular membrane systems at different magnifications yield different results. As the magnification is increased from × 18,000 to × 130,000 the estimates of surface density of endoplasmic reticulum and inner mitochondrial membranes increase by a factor of 3, whereas that for outer mitochondrial membranes increases only by 20%. The estimate of volume density of endoplasmic reticulum also increases by a factor of 3. No further increase is observed at magnifications above × 130,000 which is therefore called critical magnification. The findings are interpreted on the basis of the concept of fractals proposed by Mandelbrot, and the fractal dimensions of the membrane systems considered are estimated. This can lead to the derivation of resolution correction factors which permit measurements obtained at any magnification to be converted to estimates at critical magnification. These findings may explain, at least in part, the large discrepancy in the estimates of the surface of cytomembranes found in the literature.
Optimizing sampling efficiency of stereological studies in biology: or ‘Do more less well!‘
Authors: Gundersen H. J. G. , ØSterby R. 
Published: August 2011

SUMMARYThe aim of the sampling design for stereology is to obtain the maximal amount of quantitative structural information at a given total cost or effort. Principles of such optimal designs are discussed and methods for generating them are illustrated by a biological example. In general, the variation between different individuals—the biological variation—is the major determinant of overall efficiency, whereas the variation between single microscopic features is unimportant. It follows that the expenditure of time and/or money in order to increase the precision of the individual measurements is irrational in almost all studies where the emphasis is on the biological results.
Morphological analysis of sintering
Authors: Chermant Jean‐Louis , Coster Michel , Jernot Jean‐Paul , Dupain Jean‐Louis 
Published: August 2011

SUMMARYIn this paper mathematical morphology is applied to describe the microstructural changes of metal powders during sintering. We show which morphological parameters are accessible to rapid and automatic methods. Of these parameters the change in the connectivity number and the concavity number enable the various stages of sintering to be distinguished. Moreover the growth of the necks between powder particles can be followed using a morphological method of analysis to reveal them. This method can be applied to the investigation of the microstructure of any material consisting of convex grains.
Automated pattern analysis of growing rat lung
Authors: Keller Hj. , Burri P. H. 
Published: August 2011

SUMMARYThis study discusses the use of automatic image analysis equipment in quantifying the structural changes during growth of rat pulmonary parenchyma. At birth the latter consists of primary septa delineating a coarse structure of alveolar sacs which are then subdivided into alveoli by outgrowth of secondary septa from day 4 onwards. This process is followed by internal restructuring of the septa in the third week which further increases the surface area by formation of small irregularities.A partial quantification of these processes was obtained by measuring the full set of parameters available with the Quantimet 720 using light microscopy on rat lung sections at the ages of 4, 10 and 21 days. This yielded basic data, e.g. volume and surface densities of air space and tissue. Using closure and opening as preprocessing operations made it possible to split up such parameters into contributions from different ranges of detail resolution.The mass of eighty‐four variables obtained could be reduced to six independent factors by Factor Analysis techniques. Interpretation through their correlation with the original variables yielded septal surface, septal volume, minor and major axes of the large air spaces, and surface detail as important structural descriptors explaining 70% of total variance. The remainder is attributed to between‐field variations.
Microemulsions and electron microscopy
Authors: Biais J. , Mercier M. , Bothorel P. , Clin B. , Lalanne P. , Lemanceau B. 
Published: August 2011

SUMMARYThe replicas obtained from various microemulsions prepared under different freezing conditions were observed by electron microscopy. The difficulties encountered in obtaining proper freezing may be related to the peculiar properties of such systems. A proposal is made for using systems with particular physical characteristics, which preserve the micellar structure during freezing, instead of looking for perfect freezing conditions. This proposal proved to be successful.
Adhesion of particulate specimens to support films for electron microscopy: a model system for assessing the surface properties of support films, and its application to chromatin particles
Authors: Woodcock C. L. F. , Frado L‐L. Y. , Green G. R. , Einck L. 
Published: August 2011

SUMMARYSilica microspheres bearing a known surface charge were used to test the adhesive properties of support films and support film treatments commonly used in the electron microscopy of particulate specimens. Adhesion was strongly correlated with surface charge, negatively charged microspheres binding well only to positively charged support films and vice versa in solutions of low ionic strength. This charge dependency could be overcome by increasing the ionic strength to about 100 mmol with monovalent cations; under these conditions, it was not necessary to provide an oppositely charged film surface to obtain adhesion. Chromatin particles (nucleosomes) which have a net negative charge, behaved very much like the negatively charged silica with respect to adhesion, confirming that the microspheres provided an accurate indication of support film surface properties. The chromatin particles showed dramatic structural changes under conditions when adhesion was either poor, or very strong, indicating the need for careful selection of binding conditions for delicate biological specimens. A new and simple method for pretreating carbon films to improve adhesion was developed, and a preliminary account of this technique is presented.
The examination of fresh or living plant material in an environmental scanning electron microscope
Authors: Danilatos G. D. 
Published: August 2011

SUMMARYAn environmental scanning electron microscope (ESEM) has been developed which allows the examination of specimens at pressures up to 6 kPa. This new technique has been applied to the examination of live and wet plant specimens. The results are compared with those obtained using similar material that has been dehydrated or prepared by conventional techniques. The plant materials can survive the hypobaric pressure and beam irradiation, especially if the latter is carefully controlled.
A method for determining the three‐dimensional form of active flagella, using two‐colour darkground illumination
Authors: Woolley D. M. 
Published: August 2011

SUMMARYUsing darkground illumination, and placing colour filters over half the field, one can make a single, highly resolved, colour micrograph of a filamentous object (such as a mammalian sperm tail) from which it is possible to get a complete and unambiguous three‐dimensional reconstruction.
A simple method for the use of gallocyanin‐chrome alum as an electron stain*
Authors: Sandritter W. , Riede U. , Kiefer G. 
Published: August 2011

SUMMARYA method has been elaborated for the demonstration of DNA in the electron microscope. The method uses glutaraldehyde fixed tissue pieces from which RNA has been removed by incubation with RNase. DNA is stained by gallocyanin‐chrome alum in the tissue block. Embedding and cutting is done in the usual manner. The method is based on histochemical observations at the light microscope level which show sufficient specificity and a good stoichiometry of the staining reaction.