bluuebunny/crossref_metadata_2025_split huggingface dataset:
Enhanced oxygen diffusion and precipitation in silicon
Authors: Bergholz W. , Hutchison J. L. , Pirouz P. 
Published: August 2011

SUMMARYProlonged annealing of Cz‐silicon at 758 K results in the formation of ribbon‐like oxygen precipitates on {311} planes interpreted as the coesite phase. From this an enhancement of the oxygen diffusion coefficient by more than three orders of magnitude is inferred. Excess selfinterstitials are accommodated in extrinsic dislocation loops on {111} planes (‘loopites’) and probably also in ‘blob’‐like defects visible in high resolution micrographs with little detectable lattice strain. Evidence is presented that coesite ribbons can nucleate on {311} steps on loopites and vice versa.
Friable rock embedding in methyl methacrylate for thin‐sectioning in geological preparations
Authors: Palle Sabine , Chappard Daniel , Alexandre Christian , Orsini Jean‐Baptiste 
Published: August 2011

SUMMARYIn most cases, technical problems prevent the production of good geological thin‐slabs from friable rocks such as muds, sands or decomposed granites. Usual impregnation methods using Araldite or epoxies lead to incompletely impregnated blocks. Furthermore the excessive heat occurring during polymerization alters the micromorphology of heat sensitive minerals. Methyl methacrylate (MMA) is a widely used plastic for bone embedding. We have developed a new procedure using vacuum infiltration with MMA in a cold environment. Wafers from friable rocks are easily obtained and can be processed in the same way as those of firm and coherent rocks, without grain loss nor mineral heat alterations.
Metastable water at subzero temperatures
Authors: Franks Felix 
Published: August 2011

SUMMARYThe origins of physical and chemical metastability in aqueous systems are discussed with particular reference to supersaturated solutions, i.e. those where eutectic phase separation does not normally occur. Such solutions are characterized by high viscosities, and under conditions of rapid cooling to the glass temperature, freezing can be partly or completely inhibited. In such systems water acts as a plasticizer to the solute matrix but is not bound, in the correct sense of the word. At a glass temperature of 228 K, diffusion and evaporation rates of water from the amorphous solid are of the order of 1 nm/day, compared to 104 nm/s for the sublimation of ice at same temperature, despite the fact that ice has a substantially lower vapour pressure.
Low temperature light microscopy and its application to study freezing in aqueous solutions and biological cell suspensions
Authors: Körber Ch. , Englich S. , Schwindke P. , Scheiwe M. W. , Rau G. , Hubel A. , Cravalho E. G. 
Published: August 2011

SUMMARYThe freezing of biological cell suspensions can be understood in terms of ice formation in the external suspension medium and the cellular reactions to the changing environment. Cryomicroscopy allows a quantitative analysis of both categories of phenomena. Besides freezing stages of appropriate thermal design, the components used for that purpose include a microcomputer (PSI 80) based control system, an image analysis system (Intellect 100) and a spectrophotometer (MPV compact). The investigation of extracellular ice formation is focused on the following effects: The redistribution of solutes in the residual liquid and the resulting concentration profiles are determined photometrically or densitometrically. The transitions between various morphologies of the ice–liquid phase boundary (planar–cellular–dendritic) can be related to interface instability theories. With respect to solute segregation, the studies also involve the formation of bubbles from supersaturated gaseous solutes and freezing potentials resulting from the differential incorporation of cations and anions into the solid phase. The interaction between particles or cells and the advancing ice front is determined from critical interface velocities marking the transition between repulsion and entrapment. The effects of freezing on biological cells are studied mainly with blood cells, especially lymphocytes. The water efflux due to osmotical gradients across the membrane yields volume shrinkage curves which are recorded and analysed from video images for various cooling rates. Beyond a certain threshold cooling rate, intracellular ice starts to form, and different crystallization morphologies can be detected. The intracellular crystallization temperatures depend on cooling and warming rates as well as on the presence of penetrating cryoadditives. A fluorescence viability is used to determine the percentage of damaged cells immediately after thawing.
High resolution imaging of the CdTe/(100)InSb interface: A lattice‐matched hetero‐epitaxial structure
Authors: Hutchison J. L. , Waddington W. G. , Cullis A. G. , Chew N. G. 
Published: August 2011

SUMMARYThis paper reviews techniques available for obtaining images which can distinguish the two components in lattice‐matched, hetero‐epitaxial structures. From series of computer simulations it is shown that in the case of CdTe/(100)InSb the usual criteria for ‘good’ high resolution imaging (i.e. thin crystal, Scherzer focus) do not give images which differentiate the two materials. Conditions which do show different contrast features for both CdTe and InSb are found; under these conditions images are obtained which reveal the interfacial structure clearly, and show it to be essentially flat, and free of defects within the regions examined. Prospects for obtaining true ‘atomic’ images using a new 400 kV HREM are outlined.
Observation of lattice fringes of the Si(111)–7×7 structure by reflection electron microscopy*
Authors: Tanishiro Y. , Takayanagi K. , Yagi K. 
Published: August 2011

SUMMARYLattice fringes of Si(111)–7×7 reconstructed surface structure in reflection electron microscopy (REM) are observed for the first time, and their characteristic features are presented. Due to a glancing reflection condition in REM, the fringes with a spacing of 2.3 nm of the 7×7 surface structure lattice are seen in a region of a certain defocus range (about 6–8 μm) in a foreshortened image. The glancing reflection geometry also results in a complicated dependence of fringe directions on imaging conditions (beam alignment, crystal orientation). A shift of the fringes across the surface atomic steps and out of phase boundaries is observed.
High‐resolution electron microscopy of BaxK2–xFexTi6–xO13 crystals in polar‐glass state
Authors: Shiojiri M. , Maeda T. , Hirota Y. , Isshiki T. , Sekimoto S. , Iwauchi K. , Keda Y. I. 
Published: August 2011

SUMMARYAs a trial to detect the local atomic configuration in a cellular random system, BaxK2‐xFexTi6‐xO13 crystals, in which Ba2+ and K+ or Fe3+ and Ti4+ ions are randomly distributed on different (4i) sites of the C2/m unit cell, have been observed by high‐resolution transmission electron microscopy. Contrast differences appear among the image spots reflecting the atomic columns in the Ba2Fe2Ti4O13 crystal. With the aid of image simulation, it is revealed that the differences may be ascribed to the fluctuation in the distribution of TiO6‐octahedra and FeO6‐octahedra. A series of TiO6‐octahedra cut by FeO6‐octahedra can be regarded as a region of coherent polarization or a cluster of polarized lattice ions. Similar contrast differences have been observed in the images of crystals for x=0.4 and 1.6, and the relation between the composition and the intensity of the spots is discussed.
Electron microscopic study of 5SrRNA crystals from Thermus thermophilus HB8
Authors: Morikawa K. , Fujiyoshi Y. , Ishizuka K. , Sugiyama J. , Kawakami M. , Takemura S. 
Published: August 2011

SUMMARYSeveral types of crystals were grown from 5SrRNA, which was purified from the highly thermophilic bacterium, Thermus thermophilus HB8. Crystal lattice parameters were determined by X‐ray and electron diffraction. One type of crystal was suitable for electron microscopy after staining with uranyl acetate. Two projections derived from micrographs taken at different tilt angles were processed for image analysis. This result enabled us to deduce the arrangement of molecules within the crystal lattice.
Stereology of arbitrary particles*
Authors: Gundersen H. J. G. 
Published: August 2011

SUMMARYThis paper deals with isolated, countable items, often termed particles, in three‐dimensional space. Its substance is the unbiased stereological estimation of the number, height, surface and volume of such particles without any assumptions about their shape. The full range of estimators is described, some of them for the first time, some in an improved form, several in more than one version, and all of them under the single, absolute requirement that one can in fact identify what one is quantifying on sections. In terms of the minimal number of sections for the analysis, the estimators may be classified as follows:On a single section it is possible to estimate v̄V, the mean volume of particles in the volume‐weighted or ‘sieving’‐distribution.On two parallel sections, separated by a known distance, estimators exist of particle number and of all mean sizes (height, surface and volume) in the ordinary number distribution, as well as of SDN(v), the standard deviation in the number distribution of particle volumes. If the containing space is relatively transparent the sections may be two optical sections within one thick physical section.On a stack of parallel sections, at least as high as the largest particle, and separated by known distances, one can get twelve mean sizes and twelve distributions of individual sizes: all combinations of three sizes: height, surface and volume in four different types of distributions: number, height, surface and volume. Fulfilling the sampling requirements of the above two estimation principles it has been shown very recently that by combining them one may even estimate mean sizes and number of arbitrary particles in a stack of sections with constant but unknown separation.Finally, a unique, unbiased estimator of the total number of items in a specimen is described for the use of which one need not measure the distance between sections, nor their thickness, nor the volume of the specimen, nor assume anything about shrinkage/swelling, sectioning compression or lost caps. It is the fractionator.
Stereology for anisotropic cells: Application to growth cartilage*
Authors: Cruz‐Orive Luis‐M. , Hunziker Ernst B. 
Published: August 2011

SUMMARYA number of either new or recently available stereological methods are described for estimating volume, surface area and number of anisotropic cells. The methods are illustrated with direct reference to the epiphyseal growth plate. Different estimates of a given quantity are obtained by applying alternative methods to the same set of sections, in order to compare the relative merits of the methods. For instance, the surface area of the cells is estimated via the Dimroth–Watson model (which gives a measure of the degree of anisotropy in addition to the surface area estimate) and from vertical sections using cycloid test systems. Cell number is estimated by traditional unfolding methods and by the new disector method. Also, volume‐weighted mean cell volume is estimated from vertical sections via point‐sampled intercepts using two different kinds of rulers to classify intercept lengths. Finally, nested design statistics is applied to a set of data from twelve animals in order to compare the relative impacts of biological and stereological (sampling) variations on the observed coefficient of error of a group mean estimate. The preferred methods are listed in the final section.
Developments of new Lowicryl® resins for embedding biological specimens at even lower temperatures
Authors: Acetarin Jean‐Dominique , Carlemalm Eric , Villiger Werner 
Published: August 2011

SUMMARYTwo new Lowicryl resins have been developed for embedding biological materials at temperatures down to 210K (hydrophilic K11M) and to 190K (hydrophobic HM23). They have similar properties to Lowicryl K4M and HM20. The new resins were first tested for low temperature applications by the ‘progressive lowering of temperature’ procedure and this shows that the low viscosity of K11M and HM23 is favourable for the infiltration of biological specimens. Hardening is achieved through photo‐polymerization at these lower temperatures. These properties make K11M and HM23 suitable for cryosubstitution of rapidly frozen material and it is speculated that the preservation of antigenicity may be further improved.
The comparison of paired compartments by autoradiography: a methodological note
Authors: Reddingius J. , Vries O. M. H. de 
Published: August 2011

summaryBiochemical activities in adjacent cells, or nuclei, or other ‘compartments’, are sometimes compared on the basis of the number of silver grains visible on autoradiographs. In this report, the problem of how to test statistically the null hypothesis that the differences between the numbers of grains in two adjacent compartments are due to chance only, if one has available a sample of absolute values of such differences is discussed. The Kolmogorov test for discrete distributions is difficult to apply. More simple tests using approximations by means of the normal and chi square distributions are described. These tests are valid if, and only if, it may be assumed that the numbers of grains in the compartments are independent random variables with Poisson distributions. In autoradiographic data on RNA synthesis rates of the partner nuclei in dikaryotic cells of Schizophyllum commune, the differences appeared in general to be much smaller than expected on the basis of this assumption and the null hypothesis. This suggests that the numbers of grains in these autoradiographs follow a regular distribution rather than a Poisson one; however, it is shown that this is not necessarily true. Theoretically, the autoradiographic process might lead to regular as well as to clustered distributions. It is concluded that assuming Poisson distributions, although reasonable at first sight, may be wrong. The theoretical basis for a statistical analysis of grain counts, therefore, is insufficient.
The use of lead methacrylate 2‐ethylhexanoate to create a radio‐opaque resin suitable for microvascular corrosion casting
Authors: Burton G. J. , Ingram S. C. , Palmer M. E. 
Published: August 2011

summaryA radio‐opaque methacrylate‐based resin suitable for microvascular corrosion casting can be prepared by substituting lead methacrylate 2‐ethylhexanoate for a proportion of the methyl methacrylate monomer normally used. Best results are achieved when conventional methacrylate resin is injected first to fill the vascular tree, and this is chased with the radio‐opaque resin. The pattern of arterial and arteriolar distribution can then subsequently be followed by means of a radiographic survey of the cast, and this is of value prior to sampling from vascular systems which show functional subdivisions that cannot be correlated with any surface features. The radio‐opacity of the resin and the quantity injected can be varied easily to suit individual requirements.
Automatic description of microstructures
Authors: Powley G. , Kulick J. , Gallerneault C. E. 
Published: August 2011

SUMMARYPresent automatic image analysis techniques quantify a materials morphology in terms of the standard stereological parameters such as constituent size and distribution. While useful this information lacks the ‘depth’ available from qualitative examination. In this first of three papers it is suggested that automatic methods can be developed to capture and describe image structure in the descriptive terminology of a metallographer. The goal of such work is to permit quantification of formerly descriptive parameters. A preliminary stage in image analysis is the segmentation of an image into homogeneous regions in preparation for further processing. It is demonstrated that metallographic images (in this case binary eutectic alloys of aluminium) can be segmented using measures of the spatial organization, or texture, present in an image. A weighted average of the Hadamard transform of an image is shown to give a local measure of the texture suitable for segmentation of the images into homogeneous regions of microstructure.
Automatic description of microstructures
Authors: Gallerneault C. E. , Kulick J. , Powley G. 
Published: August 2011

SUMMARYThis is the second in a series of three papers concerned with developing automatic analysis and classification techniques for metallographic images (specifically binary eutectic alloys of aluminium). The goal of the developmental work was to capture and describe image structure, in the descriptive terminology of a metallographer, and to permit quantification of formerly descriptive parameters. The first paper dealt with the preprocessing stage of image analysis and entailed a study of two segmentation techniques. This second paper reports on work demonstrating the use of texture analysis to characterize structural aspects of metallic microstructures. It is shown that the morphological classes can be related to textural features present in digitized images.
Cryo‐transfer revised
Authors: Frederik P. M. , Busing W. M. 
Published: August 2011

SUMMARYVapour deposition of water is a major problem in cryo‐tranfer and cryo‐observation of frozen specimens. The use of (sliding) shields to protect the specimen during transfer has been evaluated and was found to be a fail‐safe procedure. Shielding the specimen with solidified coolant is proposed as an alternative or additional protection. The protective layer (ethane, Freon 22) can be evaporated in the high vacuum of the microscope. The evaporating coolant will carry away water films deposited on top. The temperature of coolant evaporation is low enough to prevent possible devitrification of water in the specimen itself.
Elemental mapping with elastically scattered electrons
Authors: Pennycook S. J. , Berger S. D. , Culbertson R. J. 
Published: August 2011

SUMMARYWe describe a technique for efficient, quantitative, standardless elemental mapping using a high‐angle annular detector in a scanning transmission electron microscope (STEM) to collect elastically scattered electrons. With a single crystal specimen, contrast due to thickness variations, diffraction, and channelling effects can be avoided, so that the resulting image contrast quantitatively reflects variations in impurity concentration. We compare a number of simple analytical approximations to the elastic scattering cross sections and show that a standardless analysis is possible over a wide range of atomic number and inner detector angle to an absolute accuracy of better than 20%.
A combined electron microscope and optical metallographic study of microstructures in high‐strength, low‐alloy (HSLA) steels after welding
Authors: Handeland T. , Erkkilä E. , Gjønnes J. 
Published: August 2011

SUMMARYA combined TEM and optical metallographic technique has been applied to microstructures in the heat affected zone in two high‐strength, low‐alloy steels with carbon equivalent 0·37 and microalloyed with Nb (0·024%), Ti (0·015%) and Nb (0·025%), V (0·05%) respectively. Volume fraction, size distribution and composition of the carbonitrides of microalloying elements were determined as function of distance from the fusion line and compared with other microstructural features, such as primary austenite grain size. Differences in microstructure are attributed to the higher stability of the Ti, Nb particles during the weld thermal cycle.
Quantitative image analysis of finite porous media
Authors: Macdonald I. F. , Kaufmann P. , Dullien F. A. L. 
Published: August 2011

SUMMARYSoftware for the reconstruction of branch‐node charts from serial sections is tested with a simple cubic lattice, and is applied to determine the genus per unit volume (specific genus) of a Berea sandstone sample from seventy‐eight serial sections.The genus is found analytically for the cubic lattice as a function of depth, cross‐section and volume. These results enable us to draw conclusions about the relative importance of depth and cross‐section and provide useful information on how to treat finite sample data to obtain the specific genus of an infinite homogeneous porous medium. It is shown that it is more important to have a deep sample (many serial sections) than a sample of large cross‐section.For samples which are too small in the direction of sectioning, the genus and the rate of change of genus with volume are too low because some of the large loops are not completed within the sample boundaries. For the Berea sample, this ‘shallow‐sample depth’ is about 2·2 grain diameters (forty‐five serial sections). Only data points at depths in excess of this value are used in determining the genus per unit volume. The slope of the genus versus volume curve is the better predictor of the genus per unit volume of the unbounded medium, of which the sample is a small part, than the value of genus/volume of the sample.For samples of finite cross‐section, the Gmin and Gmax versus volume curves are divergent and they only become essentially parallel when the dimensions in the plane of sectioning are large multiples of the grain size. It is shown that it is reasonable to assume that the arithmetic mean slope found for a small cross‐sectional area is a good estimate of the common slope that would be attained at high cross‐sectional areas. Therefore, samples of small cross‐section can be used, resulting in a reduction in the amount of data to be processed and an enhancement of the resolution of small features.The Berea sample data, beyond the ‘shallow‐sample’ region, show the same qualitative features as predicted analytically for the cubic lattice. The ratio of the slopes of the Gmax and Gmin curves is 1·22 and the genus per unit volume from the mean slope is 52·6 × 10−8 μm−3.
Estimation of surface area from vertical sections
Authors: Baddeley A. J. , Gundersen H. J. G. , Cruz‐Orive L. M. 
Published: August 2011

SUMMARY‘Vertical’ sections are plane sections longitudinal to a fixed (but arbitrary) axial direction. Examples are sections of a cylinder parallel to the central axis; and sections of a flat slab normal to the plane of the slab. Vertical sections of any object can be generated by placing the object on a table and taking sections perpendicular to the plane of the table.The standard methods of stereology assume isotropic random sections, and are not applicable to this kind of biased sampling. However, by using specially designed test systems, one can obtain an unbiased estimate of surface area.General principles of stereology for vertical sections are outlined. No assumptions are necessary about the shape or orientation distribution of the structure. Vertical section stereology is valid on the same terms as standard stereological methods for isotropic random sections. The range of structural quantities that can be estimated from vertical sections includes Vv, Nv, Sv and the volume‐weighted mean particle volume v̄v, but not Lv.There is complete freedom to choose the vertical axis direction, which makes the sampling procedure simple and ‘natural’. Practical sampling procedures for implementation of the ideas are described, and illustrated by examples.