bluuebunny/crossref_metadata_2025_split huggingface dataset:
Investigation of mercury adsorption on gold films by STM
Authors: George M. A. , Glaunsinger W. S. , Thundat T. , Lindsay S. M. 
Published: August 2011

SUMMARYScanning tunnelling microscopy, combined with complementary electrical and analytical measurements, provides a powerful method for examining the behaviour of mercury on gold‐film sensors under actual sensor operating conditions. The films exhibit a linear increase in resistance upon adsorption of mercury, and this resistive change is accompanied by a decrease in measured barrier height at submonolayer coverages of mercury. STM studies of changes in the effective barrier height upon mercury adsorption provide evidence that mercury migrates to grain boundaries for films exposed at submonolayer coverages. Coverages in excess of a monolayer result in a nearly constant, reduced effective barrier height across the entire surface, which is indicative of a more uniform distribution of mercury over the surface. This behaviour is interpreted in terms of the adsorption of mercury onto defective, contaminated gold surfaces.
Voltage‐dependent imaging of antimony on the GaAs(110) surface
Authors: Mårtensson P. , Feenstra R. M. 
Published: August 2011

SUMMARYUsing a scanning tunnelling microscope, voltage‐dependent imaging of antimony on the GaAs(110) surface has been performed. For negative sample voltages, the images reflect surface dangling bonds. Depending on the magnitude of the voltage, either one or both of the Sb atoms in the surface unit cell are seen. At positive voltage the density of surface‐states is observed to be greatly reduced compared to negative voltages. The results are analysed within the context of a simple tight‐binding model for a one‐dimensional biatomic chain.
A graphite study with a new air operating scanning tunnelling microscope
Authors: Cricenti A. , Selci S. , Generosi R. , Gori E. , Chiarotti G. 
Published: August 2011

SUMMARYA scanning tunnelling microscope working in air with good atomic resolution is described. Atomic corrugation of graphite samples cleaved in air has been observed with a lateral resolution considerably less than 1 Å. The height of the potential barrier is measured as a function of the time the system tip‐sample is exposed to air. An explanation for the observed giant corrugation is given.
Scanning tunnelling microscopic images of amino acids
Authors: Feng L. , Hu C. Z. , Andrade J. D. 
Published: August 2011

SUMMARYWe present images of amino acids adsorbed on highly orientated pyrolytic graphite (HOPG) obtained with the scanning tunnelling microscope (STM) in air. Individual molecules can be observed although the majority of adsorbates appear to form clusters. In the case of leucine, methionine, and tryptophan, two molecules often associate together to form a dimer. Single or dimer glycine molecules were not seen, but a cluster of a number of them was observed. The various adsorbed states may be related to the different interactions between the amino acids and the graphite surface. The mechanism of image formation of the amino acids is probably related to charge transfer mechanisms.
Atomic force microscopy of purple membranes
Authors: Worcester D. L. , Miller R.G. , Bryant P. J. 
Published: August 2011

SUMMARYThe surface structure of purple membranes was imaged using an atomic force probe mounted in a scanning tunnelling microscope. One of the two different membrane surfaces showed protruding, disc‐shaped features forming an hexagonal lattice with about 6 nm centre to centre spacing. These are identified as the cytoplasmic surfaces of trimers of bacteriorhodopsin molecules and are correlated with the structural information on bacteriorhodopsin obtained from numerous earlier electron microscope and diffraction studies.
Scanning near‐field optical microscopy (SNOM)
Authors: Pohl D. W. , Fischer U. Ch. , Dürig U. T. 
Published: August 2011

SUMMARYSNOM is a non‐contact stylus microscopy analogous to STM. Optical near‐field interaction is used to sense approach and optical properties on the nanometre scale (≅1 nm normal, 20–50 nm lateral). SNOM was demonstrated in transmission and reflection, in a topographic mode, and with amplitude as well as phase objects. The excitation of plasmons in the SNOM ‘tip’, a very recent development, greatly enhances sensitivity and permits intriguing new optical experiments. Overcoming the limit of diffraction, SNOM turns a long‐held dream of optical microscopists into reality.
Quantitative analysis of intramembranous particles in rapidly frozen 10T1/2 cell monolayers
Authors: Fassel Theresa A. , Hui Sek‐Wen 
Published: August 2011

SUMMARYA simple method for ultrarapid freezing of cell cultures in monolayers was developed. Unfixed and unglycerinated cells were grown on glass substrates. No special treatments of the glass or cells were necessary to facilitate freeze‐fracture along the upper plasma membranes.A reliable nonbiased method was developed to detect intramembranous particles (IMP) from the background by totally automatic means using the Cambridge Instruments Quantimet 920 Image Analysis system. Size and density data of IMP from a large number of electron micrographs can be rapidly and objectively quantitated. The automatic determination of locational coordinates for each IMP enables subtle determination of spatial distributional differences by the nearest neighbour function and the differential density distribution function, which are measurements of randomness. Quantitative analysis of the IMP distribution on the fracture face of C3H/10T1/2 mouse embryo fibroblasts upon various drug treatments was demonstrated.
Distortion of orientation data introduced by digitizing procedures
Authors: Heilbronner Renée Panozzo 
Published: August 2011

SUMMARYFor a given set of lines or outlines, the orientation distribution function, h(α), i.e. the line length per angle of orientation, is a useful measure of anisotropy. In order to obtain this function, it is most convenient to digitize the original, continuously curved lines, that is to replace them by an approximate set of straight line segments. h(α) is then given by the total length of line segment per angular interval. It is generally assumed that the orientation distribution function of the digitized lines approaches that of the original lines if the line segments are sufficiently small. However, in as much as the point density of a square lattice is not constant for all directions, the digitized lines, whose end points are lattice points of the digitizing grid, cannot represent all directions equally well. In this paper, the nature of the distortions introduced by the digitizing procedure and their dependence on sampling length and angular sampling interval are explored, and conditions for minimal distortions are discussed. For computer applications, it is recommended to perform a two‐dimensional smoothing spline operation on the digitized input. In doing so the distortion problem is altogether avoided.
Variable wavelength microinterferometry of textile fibres
Authors: Pluta M. 
Published: August 2011

SUMMARYA specific microinterferometric method, referred to as variable wavelength interferometry (VAWI), and its object‐adapted version (AVAWI) are proposed for measuring the spectral dispersion of birefringence and/or spectral dispersion of the refractive indices n and n⊥ of textile fibres. The method uses monochromatic light with variable wavelength (Λ). The only parameters that are directly measured are the inter‐fringe spacings (b) and the fibre thickness (or diameter), while other quantities are observed, read from the calibration graph b(Λ), and derived from quite simple formulae. A double‐refracting interference microscope fitted with a tungsten‐halogen lamp (12 V/100 W) and a wedge interference filter are used. No liquid immersion is required, and the fibre under study can simply be surrounded by an air medium. Results of measurements made on PPT and PA‐6 fibres are given as an example.
The influence of the aperture of illumination on the accuracy of microscope‐photometric measurements of internal transmittance
Authors: Boguth W. , Piller H. 
Published: August 2011

SUMMARYThe conical shape of the bundle of illuminating rays in the microscope causes a systematic error of transmittance measured with a microscope photometer in comparison with the (true) transmittance measured with a macrophotometer in which the ray bundle is cylindrical. The error is evaluated by the ratio of transmittance measured with the microscope photometer to the true transmittance. It is calculated for the following model objects: parallel‐sided plates, wedges, spheres and circular cylinders. The results of calculations show that the error increases with decreasing transmittance, increasing angle of the cone of rays (evaluated by the effective numerical aperture of illumination), and increasing relative size of photometric field. On the whole, the error can be neglected if the true internal transmittance is greater than 0.1 (10%), the numerical aperture is less than 0.45 and the radius of the photometric field (in the object plane) is less than one‐fifth of the thickness of the object.
Real‐time graphics display of mass variation or elemental concentration during electron beam microanalysis using a general purpose computer
Authors: Davilla S. D. , Ingram P. , LeFurgey A. , Lamvik M. K. 
Published: August 2011

SUMMARYA method is described for using a general purpose multi‐process minicomputer for the real‐time display of graphic summaries of a variety of spectroscopic results while the spectrum acquisition is simultaneously underway.
Three‐dimensional reconstruction of semi‐gross biostructures using ‘macroserials’—1‐mm‐thick serial organ slices
Authors: Suzuki Masanori , Takahashi Tohru , Ohuchi Kiyoaki 
Published: August 2011

SUMMARYA method for reconstructing a gross or semi‐gross organ structure was developed in a pathological analysis of liver lobes surgically excised from patients with bile duct carcinoma, where the extent of the tumour was to be demonstrated three‐dimensionally. Fixed material was serially sliced with a ham‐slicer, producing flawless slices as thin as 1 mm. Prior to slicing, the material was temporarily ‘embedded’ in gelatine to hold it in shape throughout slicing. These slices (‘macroserials’) could be directly brought into macroscopic 3‐D reconstruction, but in the case of bile duct carcinoma, microscopic examination of the slices was indispensable in determining the extent of carcinoma and precarcinomatous (dysplastic) changes. Slices 1 mm thick were embedded in paraffin using a special holder made of plywood plates which kept a slice in a flat, extended state through the dehydration process. This method of preparing thin slices not only allows the reconstruction of a gross organ structure with less effort than before, but also ensures a certain amount of accuracy in the reproduction of submacroscopic structures.
The relative sensitivities of autoradiographic emulsions to negative chemography
Authors: Rogers Andrew W. , Watanabe Masahito 
Published: August 2011

SUMMARYNuclear emulsions from Ilford, Kodak (U.K.), Eastman Kodak and Sakura have been exposed under comparable conditions to sections known to cause negative chemography. Kodak AR‐10 and Eastman Kodak NTB‐2 and NTB‐3 emulsions did not show negative chemography. Ilford K5, K2 and L4 and Sakura NR‐M2 showed varying degrees of chemography. The results suggest a correlation between mean crystal diameter and susceptibility to this artefact.
Total number of neurons and glial cells in human brain nuclei estimated by the disector and the fractionator
Authors: Pakkenberg B. , Gundersen H. J. G. 
Published: August 2011

SUMMARYUnbiased estimates of the total number of neurons and glial cells from central regions of grey matter in human brains are obtained using the disector principle in modifications which are unaffected by the histological processing of paraffin‐embedded tissue. Section thickness does not enter into the estimator and need not be known. An analysis of the contributions from all sampling levels to the variance of the estimator of total cell number has been used to design an optimimal sampling scheme. Using this method, a precise and unbiased estimate of the total number of neurons in a defined brain region can be obtained in less than 1 h.
The preparation of plan‐view TEM samples of ZnSe epilayers on GaAs (100) substrates by selective photoelectrochemical etching
Authors: Ng T. L. , Pemble M. F. , Williams J. O. , Wright A. C. , Zainal Z. 
Published: August 2011

SUMMARYSelective photoelectrochemical etching has been employed in order to thin samples of ZnSe epilayers grown on GaAs (100) substrates by metal organic vapour phase epitaxy (MOVPE). The difference in band‐gap between the epilayer and substrate was exploited such that only the substrate material was subject to the etching procedure. Samples prepared in this way have been studied by transmission electron microscopy (TEM) and the results of these studies are compared to results obtained by alternative cross‐sectional analysis.
Microcomputer video image analysis
Authors: Jarvis L. R. 
Published: August 2011

SUMMARYA review of aspects relating to microcomputer video image analysis is presented. The technical limitations of early systems have been surpassed by high performance video digitizers and microcomputers which are now widely marketed. Commercial systems based on these devices are increasingly available. Also, with the programming skills in most laboratories today, software development for specific applications is a practical proposition provided that sufficient expertise in video and computer technology is available. Considerations necessary for effective hardware selection and software design are discussed by example of the application to light microscope densitometry. Attention is drawn to errors which can arise when employing conventional video systems for analytical purposes.
A new heat transfer model to predict cooling rates for rapid freezing fixation
Authors: Zasadzinski Joseph A. N. 
Published: August 2011

SUMMARYA simple heat transfer model is presented to show that convection from the cryogen to the specimen is the limiting step in rapid freezing of small samples for electron microscopy when the Biot modulus, which measures the ratio of convective to conductive heat transfer, (hd/k) < 1. In comparison to the commonly accepted conduction‐limited model, the convection‐limited model predicts that cooling rates are proportional to the surface area/volume ratio, independent of the sample thermal conductivity, and inversely proportional to the product of sample density and heat capacity. Literature values of experimentally measured cooling rates fit the convection limited model. Simple analogies to predict the heat transfer coefficient as a function of cryogen properties, specimen geometry and cryogen velocity are presented.
Comparison of methods for the estimation of the thickness of ultrathin tissue sections
Authors: Groot Didima M.D. De 
Published: August 2011

SUMMARYFor a number of quantitative electron microscopical techniques it is relevant to obtain an estimate of the thickness t‘ of the section which, in general, will differ from the actual distance t between the two cuts that generate the section. To estimate t’ of ultrathin sections, several techniques have been adopted in the past, both with and without the aid of the electron microscope and additional equipment, which are summarized in an appendix. In the present study five methods have been evaluated experimentally using sections of ten different interference colours: (a) the ‘small‐fold’ technique, (b) the ‘electron scattering’ method, (c) interference microscopy with (A) the Vicker's M86® scanning microinterferometer and (B) the Jenoptik Amplival Interphako® interference microscope and (d) the ‘re‐embedding’ method. Reliable, reproducible and comparable results were obtained with the small‐fold technique, with the Vickers M86® scanning microinterferometer and with the electron scattering method. For the last method, standard test lines for the different settings of the electron microscope were developed. The results obtained with the Jenoptik Amplival Interphako® interference microscope are reproducible, but show a constant difference, i.e. a factor of 1 “36, in thickness compared with the other three techniques. The possible cause of this ‘systematic error’ is discussed. The re‐embedding method proved to be more laborious and slightly less reliable than the other techniques.The variation in t' between sections of a particular interference colour (inter‐section variation) was found to be larger than the variation in t' within a section (intra‐section variation).
A videomicrographic low‐frequency movement analyser (VLMA) and perifusion chamber for recording and analysis of the physical behaviour of seminiferous tubules and other contractile tissues in vitro
Authors: Worley R. T. S. , Leendertz J. A. 
Published: August 2011

SUMMARYA method has been developed for the recording and analysis of low frequency movements such as those of the surfaces of live seminiferous tubules. The method involves time‐lapse videomicrographic recording of the tubules followed by frame‐by‐frame measurement of the position of the edge of the tubule image in the video field. These measurements, which describe the movement of the tubule, may be analysed into a series of power spectra relating to sequential time periods through the recording. The group of spectrum plots for each tubule preparation can be plotted as isometric, pseudo three‐dimensional figures, with time represented on the s‐axis. The shapes of the spectra represent the contractile activity of the seminiferous tubules. Alterations in the level of activity and/or in the position of the frequency peaks, between control and experimentally treated preparations, are readily apparent. We also describe the construction and features of the perifusion chamber used with the VLMA.
A method for quick‐freezing live muscles at known instants during contraction with simultaneous recording of mechanical tension
Authors: Padrón Raúl , Alamo Lorenzo , Craig Roger , Caputo Carlo 
Published: August 2011

SUMMARYWe have developed a quick‐freezing method, using a copper block cooled with liquid helium or nitrogen, which permits us to freeze muscles without any cryoprotectant at predetermined, precisely measured points in the recorded tension time‐course of a single twitch or tetanus. Our aim is to arrest structural intermediates of the cross‐bridge cycle for observation in the electron microscope. Chemically stimulated, demembranated muscles as well as electrically stimulated, live muscles can be frozen on the same apparatus. Good freezing of relaxed and contracting muscles has been obtained to a depth of 10–20 μm, with excellent structural preservation after freeze‐substitution.
Infinite thickness in autoradiographs of iodine‐125
Authors: Williams M.A. 
Published: August 2011

SUMMARYInfinite thickness for iodine‐125 in autoradiographs was measured by autoradiography using four types of nuclear emulsion. Using Ilford K5, Kodak AR 10 and Hyperfilm‐3H, a value of 20 μm was obtained. Using Hyperfilm Betamax, infinite thickness was greater than 60 μm. The results are discussed in relation to the types of radiation emitted as a result of iodine‐125 decay and in relation to published image spread data for this radioisotope.
The influence of the scene parameters and of noise on the behaviour of automatic focusing algorithms
Authors: Vollath D. 
Published: August 2011

ABSTRACTA systematic study is presented of the properties of autofocus criteria. Special importance is attributed to their behaviour with respect to noise, working range and image sharpness, whose reproducibility has been investigated. It can be demonstrated that autofocus algorithms have either a large working range and do not focus in an unambiguous way or vice versa. From considerations of the properties of autofocus algorithms two novel algorithms have been developed which are insensitive to noise. One of these algorithms is characterized by a particularly large working range, whereas the other is capable of achieving maximum sharpness in a reproducible manner.
High resolution electron microscope observations of microstructures in A15 type Nb3X superconductors
Authors: Takeda M. , Yoshida H. , Endoh H. , Hashimoto H. 
Published: August 2011

SUMMARYMicrostructures of superconducting Nb3X(A15) compounds are studied by means of high resolution electron microscopy. Structure images are obtained with the 400kV high resolution electron microscope for both the annealed and ion‐irradiated crystals. The images obtained from the annealed crystals show bright contrast patterns similar to the projections of Nb and X atoms comprising the A15 structure. Defects observed in the annealed crystal irradiated with 40 kV Nb+ ions show characteristic features in contrast. The dependence of image contrast on the element X and the atomic structures of the defects are discussed by comparison with the calculated images.
Various TEM methods for the study of metal matrix composites
Authors: Withers P. J. , Stobbs W.M , Bourdillon A. J. 
Published: August 2011

SUMMARYWe have investigated the applicability of a number of TEM techniques for the study of the metal/ceramic interface in a short fibre metal matrix composite (SFMMC). In particular, we found that dark field techniques were best suited to the study of any possible (0.4‐2 nm) amorphous layer. High resolution imaging was found to be difficult to use because of the absence of well defined ‘edge‐on’ interfaces, but EELS with parallel recording was found to be very useful for finding and identifying segregated particles at the fibre/matrix interface. It was also shown that micro‐mechanisms of fracture such as voiding and fibre breakage could be readily examined by TEM using a foil preparation method which resulted in an ‘edge‐on’ fracture surface and an observation region extending about 0.8 mm below it.
Granular porometry and fibrous structures
Authors: Calonnier M. , Laget B. 
Published: August 2011

SUMMARYThe purpose of this paper is to set up a new theoretical model of a fibrous structure in its filtering function. After the segmentation, using morphological transforms, of an image of a longitudinal cross‐section two models of penetration in the structure are proposed. They are developed from results of integral geometry like the Blaschke formula. These two approaches use different propagation laws: (1) gravitational transition; (2) turbulent flow transition. Finally, two sequences of coefficients are obtained characterizing a new vertical tortuosity law.
Two‐phase flow in porous media: obtaining sharp digitized images of serial sections for subsequent quantitative analysis
Authors: Macdonald I. F. , Yadav G. D. , Chatzis I. , Dullien F. A. L. 
Published: August 2011

SUMMARYMicroscopic studies of the distributions of oil and aqueous phases within the pore space of reservoir rocks, at various relative saturations, are of fundamental importance in understanding migration, distribution, mobilization and recovery of oil in the context of a particular (enhanced) oil recovery method. The most effective approach to use for these studies is three‐dimensional computer reconstruction with the data for the three‐phase system (rock, oil, aqueous phase) entered by video digitization of a set of serial sections.A novel technique for creating accurate three‐phase digitized images from the serial section data is described. By use of appropriate pore cast materials and lighting conditions, three different two‐phase video images are created and digitized. In each image, a different one of the three phases in the pore cast is one of the two distinguishable phases. The two best two‐phase digitized images are combined to give the three‐phase digitized image.