bluuebunny/crossref_metadata_2025 huggingface dataset:
The grid‐cell‐culture technique: the direct examination of virus‐infected cells and progeny viruses
Authors: Hyatt A. D. , Eaton B. T. , Lunt R.
Published: August 2011

We describe a method for the structural analysis and identification of viruses, without purification or concentration steps which could alter virus morphology. Virus‐infected cells grown on carbon‐Parlodion‐coated electron microscope grids release large numbers of progeny viruses which adsorb to the surface of the grid and are revealed by negative staining. The technique is rapid, sensitive and can be used at three levels. (1) Negative staining of whole cell preparations revealed both extracellular and intracellular viruses or nucleocapsids beneath the plasma membrane; (2) non‐ionic detergent extraction of cells infected with certain viruses reveals cytoskeleton‐associated, virus‐specific structures normally only observed after thin sectioning; (3) cultures prepared by either procedure are suitable for colloidal gold immunological studies. Extracellular and cytoskeletal‐associated viruses were heavily and specifically labelled with gold. The results indicate that the technique may be used to rapidly identify unknown viruses on the basis of size, topography, morphology and mode of maturation from the infected cell, as well as the presence of characteristic intracellular cytoskeletal‐associated structures. The technique also has potential use in the sero‐grouping and sero‐typing of viruses with specific monoclonal antibodies.
Floating on a water bath and mounting glycol methacrylate and hydroxypropyl methacrylate sections influence final dimensions
Authors: Gerrits P. O. , van Leeuwen M. B. M. , Boon M. E. , Kok L. P.
Published: August 2011

This paper reports the dimensional changes occurring in the different steps of the histoprocessing of tissues for light microscopy. Two water‐miscible methacrylates used for embedding, namely 2‐hydroxyethyl methacrylate and 2‐hydroxypropyl methacrylate, were investigated. It was found that during stretching on the water bath and in the mounting step considerable size changes occur, which are of the same magnitude as during the dehydration step of histoprocessing. The final dimensions of the sections and of microscopic images are dependent on the response to surface tension at the water surface and mounting of the glycol and hydroxypropyl methacrylate sections, respectively. Between the two resins under study, significant differences in the size of the resin sections, with and without embedded liver tissue, were found. It is shown that the temperature at which the sections are mounted is of great importance. These observations indicate the importance of standardizing histotechniques if morphometry is to be applied.
Reflection electron microscopy methods for the study of surface structure
Authors: Hsu Tung , Cowley J. M. , Peng L.‐M. , Ou H.‐J.
Published: August 2011

The techniques of reflection electron microscopy (REM) using TEM instruments and scanning reflection electron microscopy (SREM) using STEM instruments have been explored as means for the observation of surface structure with high spatial resolution, better than 1 nm in each case. Under the ordinary environment of a commercial TEM instrument, we have studied the contrast in REM images of atomic steps and made comparison with the calculated results from the multi‐slice dynamical diffraction theory. Comparison has also been made between the REM images of defects and the calculated images based on the column approximation. The influence of surface resonances on the contrast has been investigated. By SREM performed in a modified HB5 STEM with attached high vacuum preparation chamber, we have observed the formation of periodically distributed Pd particles on the surface of cleaved MgO.
A rapid methyl salicylate clearing technique for routine phase‐contrast observations on female meiosis in Solanum
Authors: Jongedijk E.
Published: August 2011

A rapid clearing technique, involving methyl salicylate clearing and phase‐contrast microscopy, that enables large‐scale observations on meiosis and embryo sac development in intact ovules of potato, was developed. With high resolution phase‐contrast optics the details observed in cleared ovules were as well defined as in microtome sections and ‘abnormalities' associated with desynapsis and 2n‐megaspore formation were readily detected.

In potato this ovule clearing technique offers certain advantages over earlier clearing and staining‐clearing techniques and permits bulk preparation of ethanol (70%) stored ovaries shortly (1·5–2 h) before observation.
Two‐dimensional top hat filter for extracting spots and spheres from digital images
Authors: Bright David S. , Steel Eric B.
Published: August 2011

The top hat filter is a computer algorithm that extracts small, compact or rounded objects from digital images. Examples show application of the filter to micrographs and electron diffraction patterns.
Computer automated cell size and shape analysis in cryomicroscopy
Authors: Diller Kenneth R. , Aggarwal Shanti J.
Published: August 2011

Computer vision techniques have been developed for quantitative analysis of size and shape changes in cells frozen on a cryomicroscope. The analysis is based on implementation of standard serial edge detection algorithms in conjunction with a shape transform to isolate individual cells in complex scenes which may include adjacent and overlying ice crystals. In the present study the sensitivity of the automated analysis procedure is evaluated for images obtained by various microscope optical systems for progressive degrees of subject blurring by defocusing. Size measurements in calibration trials for freezing latex spheres with extracellular ice in the field of view were least sensitive for bright field images, although the most consistent data was obtained by differential interference contrast microscopy. In all cases phase contrast images produced the least accurate data. An example analysis is presented for the freezing of pancreas β‐cells.
The inhomogeneity of the icosahedral phase in Al‐Mn and Al‐V
Authors: Knowles K. M. , Stobbs W. M.
Published: August 2011

The inherent differences between the various current structural models for the determination of the scattering behaviour of icosahedral materials are reviewed with the conclusion that the nature of their apparently characteristic inhomogeneity needs further clarification. Here it is shown that the dark field reflection and deviation parameter dependence of transmission electron microscope (TEM) contrast variations can be used to provide useful qualitative evidence for the nature of quasicrystal inhomogeneities. Results obtained using the technique are discussed for the icosahedral phases i‐(AlMn) and i‐(AlV).
A model for calculating secondary and backscattered electron yields
Authors: Joy David C.
Published: August 2011

Images in the scanning electron microscope (SEM) are formed from both low‐energy secondary, and high‐energy backscattered, electrons. The quantitative interpretation of SEM images therefore requires a model which can predict the magnitude of both of these signal components for a specimen whose geometry and chemistry is known. It is shown that the combination of a simple electron diffusion model with a Monte Carlo trajectory simulation allows both yields to be calculated, simultaneously, with good accuracy. Data, such as the magnitude and energy of the maximum secondary yield, the secondary variation with tilt, and the contribution of backscattered electrons to the secondary yield coefficient, computed from this model are in excellent agreement with experimental data.
Studies of supported metal catalysts using high resolution secondary electron imaging in a STEM
Authors: Imeson D.
Published: August 2011

An additional technique for use in the characterization of catalysts by electron microscopy is presented. High resolution secondary electron images obtained in a VG HB501 scanning transmission electron microscope have been used to study the surface topography of catalysts consisting of small metal particles on high surface area carbon supports. Surface features down to nanometre dimensions can be seen, allowing the examination of micropores in the support as well as larger pore structures. The results are compared with pore size distributions determined by gas adsorption methods, and are shown to yield valuable additional information. In addition, the method in principle allows examination of the locations of small metal catalyst particles on the support.
Computer‐assisted three‐dimensional reconstruction technology in plant cell image analysis: applications of interactive computer graphics
Authors: Tuohy M. , McConchie C. , Knox R. B. , Szarski L. , Arkin A.
Published: August 2011

Sequences of more than 100 serial thin sections were cut of entire generative cells of pollen of Brassica campestris. Using transmission electron micrographs, outlines of the cell nucleus, vacuoles and mitochondria were digitized and stored on disc using the Carl Zeiss‐Kontron Videoplan Image Analysis System. The data collected concerned the geometry of cuts and logical collection of cuts into structures, both internal and external. A data translation and surface generation system was established to transfer these data to a VAX‐751 computer to establish an interface to the Intergraph's Interactive Graphics Design System (IGDS). Definition of the surfaces is based on the translated boundaries and structural configuration, enabling three‐dimensional visualization of: (a) the wireframe model; (b) the overall model with removed hidden lines, including colour or monochrome shading; and (c) the shaded image of the internal structures with superimposed wireframe representation of the external structures.
The construction and operation of a simple inexpensive slam freezing device for electron microscopy
Authors: Allison David P. , Daw C. Stuart , Rorvik Marie C.
Published: August 2011

A simple and inexpensive slam freezing device has been constructed that allows consistently good rapid freezing of uncryoprotected tissue. The device employs a dry liquid‐nitrogen‐cooled copper surface and a slamming plunger designed to provide rapid and uniform tissue to metal contact.
A new technique for obtaining large platinum‐carbon replicas
Authors: Adachi Eijiro , Nakatani Toshio , Hashimoto Paulo H.
Published: August 2011

A problem often encountered in freeze‐fracturing is that platinum‐carbon replicas roll up or are broken into fragments during tissue digestion and replica washing. In replicas damaged in these ways, tissue orientation and cell identification are difficult. In order to prevent such damage, methods have been introduced of replica strengthening by coating them with plastic films (Steere, 1957; Willison & Rowe, 1980; Stolinski et al., 1983), or with an additional layer of silver or gold (Robards & Umrath, 1978; Robards & Sleytr, 1985). A disadvantage of these methods, however, is that the additional layer must be removed before the replicas can be examined under the electron microscope. Removal of the additional layer results in loss of image quality. A reinforcing plastic film may not be completely digested by the tissue solvent and will then contaminate the replica, while the silver technique requires a silver evaporation source to be present in the vacuum chamber. Instead of replica strengthening methods, some authors recommend putting replicas carrying tissues, which have been partially digested by bleach (Pearce, 1983) or chromic acid (Fetter & Costello, 1986), onto carbon‐coated gold grids and then floating them on chromic acid. However, neither this method nor the replica strengthening method assure the production of large unrolled replicas. Moreover, gold grids are rather expensive.
Automatic focusing by correlative methods
Authors: Vollath D.
Published: August 2011

The possibility of focusing images by the autocorrelation function is explained. It can be shown that these techniques are less sensitive to disturbances by noise than others. Furthermore, focusing criteria derived from autocorrelation functions have different responses to image contrast.

It has been shown that these focusing criteria can be determined using binary images and applying the laws of stochastic ergodic metrology. This leads to a large reduction in computing time.

Moreover, an attempt was made to focus by means of binary images determined by simple segmentation. The experimental results show that such a focus criterion operates quite well. The criterion offers the advantage that brightness levels in the image can be chosen selectively for focusing.
A consistent definition of probe size and spatial resolution in the analytical electron microscope
Authors: Michael J. R. , Williams D. B.
Published: August 2011

A technique for measuring the extremely small (<2 nm) probe sizes generated in a field emission gun analytical electron microscope is described. The technique involves scanning the fine probe across the edge of small oriented MgO cubes. A mathematical description of the intensity profiles is developed and it is shown how this relates to various definitions of the probe size. The experimentally measured probe sizes are then combined in a consistent manner with both beam broadening calculations and experimental measurements. This approach results in the first self‐consistent definition of the spatial resolution of X‐ray microanalysis in thin foils.
Ultrastructure and histochemistry of blue‐green algae freeze‐substituted at 190 K by Nanoplast MUV 116
Authors: Bachhuber Karlheinz , Böhme Herbert , Westphal Christel , Frösch Dieter
Published: August 2011

A method is presented for the infiltration and embedding of frozen micro‐organisms at a temperature of 190 K by Nanoplast MUV 116, a new UV‐polymerizable embedding medium for electron microscopy. The hardness achieved by UV irradiation in the cold is about 80% of the hardness needed for ultramicrotomy. Final hardening requires a post‐curing step at 333 K for 24 h.

Applying this procedure to cyanobacteria, an improved ultrastructural preservation is demonstrated as compared to samples that were embedded in the water‐soluble medium Nanoplast FB 101 at ambient temperatures. Sections of materials treated in this way are suitable for histochemical techniques, such as Thiéry's silver staining method for glycogen.
Staining methods for the detection of laticifers in plant tissue
Authors: Inamdar J. A. , Murugan V. , Subramanian R. B.
Published: August 2011

Simple, easy and inexpensive methods have been evolved to detect laticifers in plants with the help of bright‐field and fluorescence microscopy using Oil Red O, dansyl chloride, neutral red, Rhodamine B and Ponceau S stains.
Laser scanning microscope: Differential phase images
Authors: Horikawa Yoshiaki , Yamamoto Mitsunori , Dosaka Shinichi
Published: August 2011

A beam‐deflection type laser scanning microscope for differential phase contrast images using the split‐detector technique is developed and the images are obtained in real time (30 images/s).

The special optical design allows transfer of the pupil information necessary to the imaging of the differential phase contrast images during beam deflection and the use of acousto‐optic deflectors with the associated correction system enables real time imaging.

Differential phase images of surface details of crystals are simply obtained without silver coating or etching, which are indispensable in a normal DIC. Biological specimens are also observed.
Single‐ring polanret phase‐contrast system
Authors: Pluta M.
Published: August 2011

An extremely simple, modified polanret phase‐contrast system has been developed. It uses only a single polarizing ring, instead of three zonal polarizers as required in Osterberg's original polanret system (manufactured by the American Optical Corporation). The modified system is much more easily manufactured and its economy of light is twice as good. However, it does require an easily accessible microscope objective exit pupil, where the polarizing ring must be located.
Application of acoustic microscopy to the measurement of some physical parameters of ceramics
Authors: Grosmaire J. , Nongaillard B. , Rouvaen J. M. , Saisse H. , Fevrier H. , Joseph S.
Published: August 2011

The scanning acoustic microscope is a valuable tool for the ultrasonic non‐destructive testing of ceramic materials or sintered metals, like titanium compounds. Bulk defects, responsible for the mechanical aging and breakdown of parts, are easily detected and imaged. Moreover, diffuse structures are evidenced in these images, forming a continuous background. In this paper, we present a method which enables the determination of physical parameters, like the density and the bulk grain size of the materials, from this background. This information is extracted, using a statistical approach, from the histograms pertaining to materials with a spectrum of different microstructures, based on a principal component analysis (PCA). It may be noted that the size of the microstructure elements accessible by this method can be lower than the spatial resolution of the microscope.
A LISP‐based image analysis system with applications to microscopy
Authors: Bright David S.
Published: August 2011

LISPIX is an image processing and analysis system consisting of a sub‐system of image processing commands implemented in FORTRAN and a collection of analysis algorithms implemented in LISP. Examples are given of using the system for microanalysis applications. The processing commands are useful alone for simple tasks. For analysis applications, the LISP programming environment, for which the processing commands are designed, allows rapid development of algorithms and a convenient way to use them. Appendices contain definitions of the most useful commands as well as examples of the LISP algorithms.
A new method for the preparation of ‘double‐fixed’, quick‐frozen, freeze‐substituted cells for whole‐cell transmission electron microscopy
Authors: Nagele R. G. , Lee H.
Published: August 2011

A method is described in which quick‐frozen, freeze‐substituted, cultured cells can be prepared for whole‐cell transmission electron microscopy (WCTEM). This method is simple and reliable and can be carried out in most laboratories without special equipment. Cells grown on Formvar‐carbon‐coated nickel grids are quick‐frozen in Freon 22, freeze‐substituted in an ethanolic solution of glutaraldehyde, post‐fixed in osmium tetroxide and critical‐point‐dried. The quality of ultrastructural preservation using this ‘double fixation’ protocol is comparable to that of conventional WCTEM. However, the combination of quick‐freezing and WCTEM has the decided advantage over conventional WCTEM in that cellular activities are arrested almost instantaneously. Thus, this new method could potentially yield a more faithful representation of cytoarchitecture and is especially useful for studies on the structural basis of rapid cytoplasmic events which may remain undetected when using conventional fixation methods.
Fasga: A new polychromatic method for simultaneous and differential staining of plant tissues
Authors: Tolivia D. , Tolivia J.
Published: August 2011

A new method based on the simultaneous action of Safranin and Alcian Blue (or green) is reported. The main advantages of this method are its simplicity and the absence of differentiation processes. Free‐hand, frozen and paraffin sections can be stained with this technique. Sections are placed in 10% sodium hypochlorite for 1–5 min, rinsed in 5% acetic acid and stained for 10 min. Sections are then washed in distilled water for 1 min, rinsed in distilled water for 5 min and mounted.
A compact parallel‐recording detector for EELS
Authors: Egerton R. F. , Crozier P. A.
Published: August 2011

We designed and constructed the prototype of a parallel‐recording system for a Gatan 607 electron energy‐loss spectrometer attached to a conventional transmission electron microscope. Quadrupole lenses were used to project a magnified energy‐loss spectrum onto a 65 μm thick screen of single‐crystal yttrium aluminium garnet (YAG), where the electrons are converted to photons which are transferred by coherent fibre optics to a 1024‐channel photodiode array. When used in conjunction with a tungsten‐filament electron source, the system achieves an energy resolution close to 2eV and can record inner‐shell ionization edges with good signal/noise ratio in exposure times not exceeding 5 s.
Minima equalization: A useful strategy in automatic processing of microscopic images
Authors: McMillan Paul J. , Yakush Andrew , Frykman Gary , Nava P. Ben , Ras Vicky R.
Published: August 2011

Specifically stained features in microscopic images rarely have a unique range of grey levels which would permit selection of the features by simple thresholding. The spaces between features and immediately surrounding them are often as dark or darker than the more lightly stained features. An algorithm for minima equalization which facilitates the extraction and segmentation of such features was designed and is explained in intuitive terms. It is applied to the analysis of cross‐sections of peripheral myelinated nerve fibres. It is shown that the binary image obtained can be combined with a gradient image to give a binary image which accurately reflects the thickness of the myelin in the original image. Using silver‐impregnated nerve endings and bile canaliculi stained for thiamine pyrophosphatase, binary images like those prepared manually from thick specimens using a camera lucida can be obtained using the minima equalization procedure. The image processor is used to develop a composite image by combining images at various focal planes through the thick specimen. This image is then processed to obtain the binary image.
Improvements in the fabrication of thin foil apertures for electron microscopy
Authors: Fabergé A. C.
Published: August 2011

Schabtach (1974) developed a process for making ‘thin’ (i.e. self‐cleaning) apertures for electron microscopes. Several improvements in this process are described, the most important of which is the deposition of a heavy metal by DC sputtering rather than by evaporation, making the process much easier.
Voltage dependence of the tunnelling current: an exact expression
Authors: Noguera Claudine
Published: August 2011

An exact expression for the tunnelling current measured with a scanning tunnelling microscope (STM) is obtained. It clarifies the information deducible from the ‘spectroscopic mode’ of the STM and raises the question of the observability of surface states. The connection with the Transfer Hamiltonian approach is made, and the conditions of validity of the latter are analysed.
The heat transfer between a heated tip and a substrate: fast thermal microscopy
Authors: Dransfeld K. , Xu J.
Published: August 2011

Here we describe a new mechanism of heat transfer between two solids separated by a distance. This mechanism does not involve the ambient air or adsorbed vapour films, and is therefore expected to remain active under perfect vacuum conditions. As will be described in detail, thermal charge fluctuations of one solid substrate kept at finite temperatures create an electromagnetic field—at infrared frequencies and of a short coherence length—which extends across the gap and effectively transports heat to the other solid. In our view this mechanism is responsible for the effective heat transfer observed recently by C. C. Williams and H. K. Wickramasinghe between a heated tip and a substrate.
Imaging of granular high‐Tc thin films using a scanning tunnelling microscope with large scan range
Authors: Niedermann Ph. , Fischer Ø.
Published: August 2011

STM images are presented in the micron scale, taken in UHV with a single‐tube scanner STM with SEM control of the tip position. For calibration, a carbon grid was used from which the coupling of x and y scan axes has been determined as well as the piezo‐sensitivity factors. Images taken of a YBa2Cu3O7‐δ, film display the granular structure of the crystallites formed during the post‐evaporation annealing. A direct comparison of STM scans with SEM micrographs was made which demonstrates the complementary information obtained by the two methods. The obtained resolution is compared to the tip shape which becomes crucial for the imaging of corrugated surfaces on the micron scale. With a simple geometric model, an attempt has been made to reconstruct the surface topography from STM scans based on the knowledge of the tip shape.
Tip‐bias induced surface modification on gold surfaces
Authors: Nagahara L. , Lindsay S. M. , Thundat T. , Knipping U.
Published: August 2011

We have observed drastic modification of gold surfaces at tip biases above a threshold value. These modifications were observed only on surfaces which are not atomically flat and only with negative tip bias. We tentatively attribute these surface modifications to formation of Taylor cones.
Scanning tunnelling microscopy studies of heteroepitaxy: CaF2 on Si(111)
Authors: Wolkow R. , Avouris Ph.
Published: August 2011

We apply scanning tunnelling microscopy and tunnelling spectroscopy to study the initial stages of CaF2 epitaxy on Si(111)‐(7×7) for a range of deposition temperatures. We find that deposition at surface temperatures <700°C leads to CaF2 clustering. At temperatures between 750 and 800°C two new structures, a 2×3 and a (√3 X √3***)R30°, are observed. Tunnelling spectra and topographs obtained at different energies allow us to measure interface band gaps, and determine the valence state of Ca bonded directly to silicon and the valence state of Ca in the second layer. More importantly, we demonstrate that STM can be used to image thick insulating layers of CaF2 by tunnelling into the conduction band of the films.

One of our goals in this study has been to test the ability of STM to image insulating multilayers. It is generally believed that STM cannot be applied to insulators. We find, however, that despite the large band gap of ∼12 eV, the CaF2 conduction band is accessible, and that insulating films can be imaged by STM.
Imaging an optical disc by the combined use of scanning tunnelling microscopy and scanning electron microscopy
Authors: Bartolomé A. , García R. , Vázquez L. , Baró A. M.
Published: August 2011

We present the data obtained by scanning tunnelling microscopy combined with scanning electron microscopy of the digitally encoded structure on a stamper used to fabricate optical discs. The combination allows us to focus the STM tip on a preselected spot with a precision of ≅0·3 μm. The data show the superiority of STM for a more detailed characterization of shape, width, length, height and fine structure appearing on the sample. We also show the influence of tip shape on STM resolution. Simultaneous use of both microscopes is possible but high electron doses produce an insulating layer of contaminants thick enough to make STM operation impossible.
Force sensing in scanning tunnelling microscopy: observation of adhesion forces on clean metal surfaces
Authors: Dürig U. , Züger O. , Pohl D. W.
Published: August 2011

Tip sample interaction forces were investigated during normal tunnelling operation of the STM using an Ir tip and a polycrystalline Ir sample. Metallic adhesion interaction was observed for tunnel conductivity ranging from 10−6 to 19−9 Ω‐1 implying that the actual gap width was of the order of 1–4 Å. Similar experiments performed on a polycrystalline Al sample exposed to 1 Langmuir O2 showed that tip sample interaction changed from attractive to repulsive on well‐defined areas extending over ∼100 Å2 which we identified with the oxidized Al surface.
The STM learning curve and where it may take us*
Authors: Demuth J. E. , Koehler U. , Hamers R. J.
Published: August 2011

The scanning tunnelling microscope (STM) has proved to be an extraordinary method to investigate surfaces in vacuum, air and liquid environments. Several issues regarding the use of the STM for atomic resolution studies are discussed. These include electronic contributions to STM images, the role of the tip in resolution and spectroscopy, as well as the need for complementary information about chemical composition or sub‐surface structure.
A frictional force microscope controlled with an electromagnet
Authors: Kaneko R.
Published: August 2011

Frictional forces are usually measured by detecting spring displacement. To obtain high‐resolution measurements of frictional force distributions, a sharp tip and a light load are required. In measuring frictional force on relatively rough surfaces, using very sharp tips (submicron radii), significant stick‐slip motions are observed, and continuously varying dynamic frictional forces can not be measured.

To measure continuous friction distributions between sharp tips and surfaces with light loads, a new frictional force microscope (FFM) is developed. This FFM has an electromagnet to maintain the tip suspension spring in a non‐deflected position. The frictional force is then measured from the magnet current. Using this FFM, continuous friction distributions between 0·1 μm radius diamond tips and magnetic disk surfaces with light loads (less than 10 μN) are obtained.
Study of Au surfaces by scanning tunnelling microscopy
Authors: Kuk Y. , Silverman P. J. , Chua F. M.
Published: August 2011

The reconstructions of Au surfaces have been studied by scanning tunnelling microscopy. Topographs of Au(110)‐(1×2) as a function of annealing temperature show changes in the long range order, in good agreement with diffraction measurements and theoretical studies. Some insight into the nucleation and growth of the (1×2) reconstruction was obtained by imaging the surface after deposition of Cs or O. A new structural model for Au(100)‐(5×20) is proposed with a high resolution topograph. Adsorption of Si clusters on Au(100) will be described.
In situ, atomic scale observation of electrode topography and reactions
Authors: Twomey T. , Wiechers J. , Kolb D.M. , Behm R. J.
Published: August 2011

The topographical changes occurring on a Au(111) electrode during simple electrochemical reactions have been followed with an STM capable of operating in situ, i.e. in the electrochemical environment, and of yielding atomic scale resolution. Changes in the surface structure induced by adsorption and desorption of Cl− ions could be observed and the effects of subjecting the sample to an oxidation‐reduction cycle could be monitored.
Measurements of polyphosphoric acid on HOPG
Authors: Mizutani Wataru , Shigeno Masatsugu , Saito Kazuhiro , Morita Naotake , Yoshioka Toru , Ono Masatoshi , Kajimura Koji
Published: August 2011

As a sample for initial study on biological materials by using scanning tunnelling microscope (STM), we selected phosphoric acid consisting of phosphorous atoms which play biologically an important role. We measured polyphosphoric acid coated on HOPG by STM and scanning tunnelling spectroscopy (STS) in air. In order to identify molecules on STM images, local I‐V curves were taken simultaneously. The averaged I‐V curves and the normalized conductance spectra of graphite coated with the acid show characteristics different from those of clean graphite surface. Around a step of the substrate, we found domains where normalized conductance spectra were different from those of clean graphite surface and ascribable to that of the adsorbed molecules.
Differential scanning tunnelling microscopy
Authors: Abraham David W. , Williams C. C. , Wickramasinghe H. K.
Published: August 2011

We review the principle of differential imaging and its application to scanning tunnelling microscopy (STM). It is shown that placing a lateral dither on an STM tip at high frequency provides the means for transfering topographic information to a frequency range where noise is small. Differential STM imaging on graphite and gold is demonstrated. A simple relation between the differential image and the conventional topographic image is described.
Spatially resolved ballistic electron spectroscopy of subsurface interfaces
Authors: Bell L. D. , Kaiser W. J.
Published: August 2011

Buried interfaces have traditionally been inaccessible to direct investigation by surface‐sensitive techniques. A unique and novel electronic probe, which is sensitive to subsurface electronic structure, has been utilized to probe Schottky barrier interfaces. The method, ballistic electron emission microscopy (BEEM), is based on scanning tunnelling microscopy (STM) techniques. A theoretical treatment has been developed to describe the ballistic electron spectra obtained by BEEM and this treatment is applied to data obtained on the Au‐Si Schottky barrier interface system. Excellent agreement between experiment and theory is obtained. In addition, the treatment pradicts nanometre spatial resolution for interface imaging by BEEM.
The STM as an information storage device
Authors: Thomson D. J.
Published: August 2011

The high spatial resolution of the scanning tunnelling microscope (STM) makes its use as an information storage device very attractive. However, even without specifying the means of information storage, several limits can be placed on the characteristics of these devices. One would expect that a bit of information could not be stored in a dimension smaller than an atom. This limits the storage density to 1015 bits/cm2. Present‐day STM have fields of view that range up to 2times10−6cm2 yielding a total potential capacity of 2times109 bits. This capacity would be expected to grow as STM design becomes more refined. At 1 nA, shot noise will limit the read rate to 20 Mbits/s. This limit can only be overcome by using larger currents. The write rate may also be limited by this phenomenon if the writing mechanism demands that a certain charge threshold be reached to write a bit. For a particular device structure, operating conditions will be identified where the above limitations will become important. The above analysis leads to the conclusion that an STM storage device with reasonable read/write rates and a large storage capacity should be possible.
The STM system constructed for analytical application
Authors: Okumura Akihiko , Miyamura Kazuo , Gohshi Yohichi
Published: August 2011

An STM equipment capable of measuring I‐V characteristics of a sample surface has been constructed, and some preliminary measurements have been made. Carbon atoms in graphite were resolved. Reproducible and low noise I‐V characteristics were obtained, which allowed to observe dI/dV and d2I/dV2.
Imaging of tip‐sample compliance in STM
Authors: Anders M. , Heiden C.
Published: August 2011

An STM was built, in which the substrate is mounted on a piezoelectric bimorph. The compliance of the tip‐surface contact region is measured by modulating the vertical position of the tip and detecting the induced deflection of the bimorph. Tip‐surface compliances between 5 and 200 N/m were measured during STM operation. It is possible to use the compliance signal for operating the microscope's feedback loop. Stable feedback loop operation can be achieved for tip‐surface distances up to about 200 nm. By operating the microscope in this constant compliance mode, surfaces of arbitrary conductance can be imaged. For conductive surfaces the tunnelling current can be recorded simultaneously. On a Nb3Sn film conducting and isolating patches were detected using this method.
The effect of a vacancy on the STM image of graphite
Authors: Soto M. R.
Published: August 2011

Theoretical studies have been done on graphite with a vacancy using the extended Huckel tight‐binding (EHTB) method. The results of the singly‐ and doubly‐layered samples show that there is an unexpected distance dependence of the charge density directly over the vacancy. Furthermore, the vacancy acts as a perturbation to distinguish two sublattices which exist in pristine graphite and it creates a charge enhancement in the atoms directly surrounding it.
Scanning tunnelling and atomic force microscopy performed with the same probe in one unit
Authors: Bryant P. J. , Miller R. G. , Deeken R. , Yang R. , Zheng Y. C.
Published: August 2011

The technique demonstrated here provides features of both scanning tunnelling microscopy (STM) and atomic force microscopy (AFM). The metallic probe acts to record current variations and sense forces from the same sample area simultaneously. Thus, separate images may be recorded, in registry. The collected data allows real space correlations between some electrical properties and the geometric structure of a sample surface. The same tip is used since the geometry and condition of the tip can effect the data recordings. Platinum alloys, tungsten and graphite tips have been employed successfully. An AFM lever can respond to surface contact forces, within the elastic limits of the sample, while electric current is sensed by the tip of the lever. The usefulness of this experimental procedure is tested here by an application to semiconducting samples of Ag‐doped CdTe in air and in paraffin oil media.
Contrast in confocal scanning microscopy with a finite detector
Authors: Shuman H.
Published: August 2011

The optical properties of a general scanning microscope are determined within the framework of Fourier imaging theory. For a simple model optical system, with Gaussian lens and detector apertures, the contrast transfer function can be expressed in terms of elementary functions. The theory predicts that spatial resolution and depth discrimination vary continuously with detector aperture and that defocus phase contrast is present in transmission images obtained with a symmetric objective, collector lens confocal microscope.
A simple, direct method for the collection of particles from air samples for transmission electron microscopy and digital image analysis
Authors: Farrants George , Reith Albrecht , Schüler Barbara , Feren Kari
Published: August 2011

A method is presented for the collection of small (< 1 μm) particles from air samples. Examples of its application are the monitoring of environmental pollutants in the working environment, personal monitoring of exposure to such pollutants and the characterization of particular environments such as clean rooms in the semiconductor industry. Electron microscope grids are attached to Nuclepore filters with carbon cement, the filter mounted in a standard disposable holder and air drawn through the filter with a pump. The method is simple, reproducible, allows a wide range of experimenter control, and provides specimens suitable for electron microscopy, followed by automatic image analysis.
Microscopic tomography by laser scanning microscopy and its three‐dimensional reconstruction
Authors: Takamatsu Tetsurou , Fujita Setsuya
Published: August 2011

We have developed a new confocal laser scanning microscope equipped with two galvanometer mirrors which swing the laser beam. With this set up we can observe large and fragile specimens. Using a focused laser beam as light source to minimize ‘flare’ and a pinhole in front of a photodetector to eliminate out‐of‐focus data, we could obtain a depth‐discriminated fluorescence image. The scanning apparatus of our system can eliminate mechanical vibration and sweep widely, to obtain images at a low magnification. A thinly sectioned image with high resolution and high contrast could be obtained optically from an in situ thick specimen. We have called this technique ‘microscopic tomography’. Combining the laser scanning microscope with the colour image analyser generated semi‐automatically a three‐dimensional picture of the biological material with information on its interior.
Automated image segmentation by mathematical morphology and fractal geometry
Authors: Rigaut Jean Paul
Published: August 2011

A new method for automated image segmentation is presented. It makes use of a combination of principles derived from mathematical morphology and fractal geometry.

The method consists of searching for regions in which the grey‐tone function defining the black‐and‐white image can be represented, inside a certain range of resolutions, by a fractal surface with a given fractal dimension.

The probability for a planar, circular structuring element, randomly positioned on a grey‐level plane inside a region of the digitized image, to intersect the surface which represents the grey‐tone function, is derived by two methods, fractal geometry and mathematical morphology.

A fundamental equation is finally derived, relating, in a fractal region of the grey‐tone surface, the sum of discrete (pixel) grey‐level differences between the images obtained by ***multi‐grey‐level dilation and erosion of the original image, respectively, to the size of the structuring element and the fractal dimension.

This equation represents the basis of the method. The automated image analysis program, written for the IBAS (Kontron), works on several memorized images, each produced by a subtraction between the images obtained by dilation and erosion of the original image, using several sizes for the structuring element.

Although minimal computations are made, the algorithms are too slow for practical applications and will require massive parallel processing for future use.

The method relies on the assumption that regions of an image having a particular structure will usually produce a fractal grey‐tone surface, with a particular value of the fractal dimension. The feasibility of such an approach is demonstrated with segmentations obtaining the isolation of various objects on different biological images. The natural structures we have studied indeed show a fractal grey‐tone surface, at least within a certain range of (low) resolutions.

Our studies also allow us to consider whether human vision uses a combination of image transformations and principles of self‐similarity to segment images.
Measurements of the thickness of a carbon film evaporated on to biological samples
Authors: Fakhouri H. G. , Dyson N. A.
Published: August 2011

The energy loss in elastically scattered α‐particles is used to measure the thickness of carbon films used for coating biological samples to prevent surface charging. The lighter mass film on the substrate acts as an absorber which imposes an energy shift on the substrate signal. A relation is achieved between the energy shift and the thickness of the film. The calculation has been tested by measuring the energy shift for a series of films the thickness of which was determined directly by weighing. Good agreement was found, with small deviations at greater thicknesses.
Application of the Cavalieri principle and vertical sections method to lung: estimation of volume and pleural surface area
Authors: Michel René P. , Cruz‐Orive Luis M.
Published: August 2011

A practical methodology is proposed for the stereological analysis of lung and other organs using recently developed unbiased procedures. This study concentrates on the unbiased estimation of lung volume using Cavalieri's principle compared with the fluid displacement method and measurement of pleural surface area using vertical sections. Furthermore, the proposed design, in addition to the sampling of extensive slices for the initial steps, also allows sampling of vertical sections for light and electron‐microscopical stereology.

The procedures are described in detail by reference to biological data from the right lungs of four rabbits. We found excellent agreement between estimates of lung volume measured with Cavalieri's principle and those measured by fluid displacement. Pertinent details of the statistical analysis of the sources of variation (namely biological, systematic sectioning and point‐counting variation) are given in an appendix.
Improved algorithms for automatic bone histomorphometry on a numerized image analysis system
Authors: Beigbeder M. , Chappard D. , Alexandre C. , Vico L. , Palle S. , Riffat G.
Published: August 2011

Quantitative histological methods have proved to be the most effective methods in bone disease research. Faster and more accurate techniques are currently needed. We have developed a simple digitized image analysis system which allows accurate measurements of trabecular bone mass. The algorithm is based on the 'four‐connected sets' mathematical theory. Given a numerized image displayed by a CCD camera, the algorithm recognizes all possible four‐connected sets and provides area measurements. The first procedure automatically eliminates small, irrelevant profiles (wrinkles, cell nuclei, etc.) while larger profiles are erased interactively. The second procedure similarly erases the artefactual defects within the trabecule (artefactual cracks or empty osteocytic lacunae). The method was shown to be very accurate and time‐saving.
Automated extraction of regular spot arrays from electron diffraction images*
Authors: Bright D. S. , Steel E. B.
Published: August 2011

In order to analyse agglomerate particles, we have developed a computer method that automates the analysis of spots in electron diffraction patterns. The method isolates the zone axis diffraction pattern in a polycrystalline diffraction image by isolating the spots from other features of the image and then by selecting the spots that belong to a regular array. The method gives the basis vectors for the array which can then be used to identify the particle by comparison with standard diffraction data.
Random approximation of convex sets*
Authors: Schneider Rolf
Published: August 2011

We consider convex hulls of independent, identically distributed random points, the distribution of which depends in some way on a given convex body. In the first part, we study an i. i. d. sequence of points on the boundary of a smooth convex body K in the plane and assume that their distribution has a positive continuous density with respect to arc length. The rate of the almost sure convergence of the area, perimeter and Hausdorff distance from K of the successive convex hulls of the random points towards the corresponding values of K is investigated. Also random polygons generated by intersecting random supporting halfplanes of K are considered.

The second part gives a survey of convex hulls of random points in d‐dimensional convex bodies, with special emphasis on the asymptotic behaviour of the expectations of some geometrically interesting functionals.
The expected volume of a random polytope in a ball*
Authors: Affentranger Fernando
Published: August 2011

For any convex body K in d‐dimensional Euclidean space Ed(d≥2) and for integers n and i, n ≥ d + 1,1 ≤ i ≤ n, let V(d)n‐ii(K) be the expected volume of the convex hull Hn‐i, i of n independent random points, of which n‐i are uniformly distributed in the interior, the other i on the boundary of K. We develop an integral formula for V(d)n‐i, i(K) for the case that K is a d‐dimensional unit ball by considering an adequate decomposition of V(d)n‐i, i into d‐dimensional simplices. To solve the important case i = 0, that is the case in which all points are chosen at random from the interior of Bd, we require in addition Crofton's theorem on mean values. We illustrate the usefulness of our results by treating some special cases and by giving numerical values for the planar and the three‐dimensional cases.
Characteristic X‐ray production cross‐sections for standardless elemental analysis in EDX
Authors: Paterson J. H. , Chapman J. N. , Nicholson W. A. P. , Titchmarsh J. M.
Published: August 2011

Measurements have been made of cross‐sections for the production of X‐rays following ionization of the K‐shell by fast electrons for a range of elements and incident electron energies. These data have been fitted to a simple functional expression for the ionization cross‐section. This model, the Bethe model, includes two empirical fitting parameters. We found that a single universal pair of parameters may be used to allow the model to predict cross‐sections with a mean error of ∼ 7% and a maximum error of ∼ 20% over the range of conditions considered. A relativistic form of the Bethe model yields a small improvement in accuracy for higher incident electron energies.

Measurements have also been made of L‐shell production cross‐sections. It is expected that the Bethe model will apply also to the L‐shell. Comparison of experimental and calculated K/L‐shell cross‐section ratios generally supports this, but uncertainties in the values in the literature for L‐shell fluorescence yields precludes the drawing of any firm conclusions here.