bluuebunny/crossref_metadata_2025_split huggingface dataset:
T-Max and TRI-X: Comparisons of Sheet Film Emulsions for Use in SEM Photography
Authors: Long J.C. 
Published: June 2020

The potential benefits of Kodak's Tabular Grain Emulsion Films (brand name: T-MAX) has resulted in our lab considering a switch from Kodak TRI-X 4×5 sheet film to Kodak T-MAX 4x5 sheet film for use in SEM photography. The current regime is TRI-X sheet film developed in D-19 diluted 1:2. Processing is at 20°C in large (4l) tanks with N2 burst agitation. The procedure used for this study was T-MAX and TRI-X sheet film processed in T-MAX RS developer; using the same large tank, and No burst system, but at temperatures ranging from 20° -24°C. The potential benefits are: 1) Improved image quality; tabular grain emulsions are purported to have improved sharpness, a finer grain at a given film speed, and better tonal separation than previous emulsions. 2) Ease of use; T-MAX RS is a highly miscible liquid concentrate which can be used at 20°-24°C. The primary temperature recommendation is 24°C; this would reduce the need for chilled water at our facility.The initial comparison was made using Kodak TRI-X and Kodak T-MAX 400 sheet film. Exposures were made using a JEOL T330A equipped with a high resolution photo CRT and waveform monitor (WFM). Brightness settings were determined using the WFM in the procedure described by Holm. Four sets of eight exposures each were made for both T-MAX 400 and TRI-X. A set consisted of one sheet of film exposed at each of the zones represented by the lines of the WFM. One set of each type of film was processed at each of the four specified temperatures,(20°, 21° 22°,24°, using T-MAX RS developer, at the time recommended by Kodak. Negative density was determined using a Zeiss Axiophot equipped with a MPM 20 Photometer. The percent value of transmitted light (%T) was converted to diffuse density (D) using the formula D=Log 1/T. The calculated diffuse density was plotted against the brightness line position on the WFM. Granularity was examined by visual comparison using 12x enlargements from T-MAX and TRI-X negatives of similar density.
Correlation of Pore Structure and Permeability by SEM-Image Analysis
Authors: Callender C. A. , Dawson Wm. C. , Funk J. J. 
Published: June 2020

The geometric structure of pore space in some carbonate rocks can be correlated with petrophysical measurements by quantitatively analyzing binaries generated from SEM images. Reservoirs with similar porosities can have markedly different permeabilities. Image analysis identifies which characteristics of a rock are responsible for the permeability differences. Imaging data can explain unusual fluid flow patterns which, in turn, can improve production simulation models.Analytical SchemeOur sample suite consists of 30 Middle East carbonates having porosities ranging from 21 to 28% and permeabilities from 92 to 2153 md. Engineering tests reveal the lack of a consistent (predictable) relationship between porosity and permeability (Fig. 1). Finely polished thin sections were studied petrographically to determine rock texture. The studied thin sections represent four petrographically distinct carbonate rock types ranging from compacted, poorly-sorted, dolomitized, intraclastic grainstones to well-sorted, foraminiferal,ooid, peloidal grainstones. The samples were analyzed for pore structure by a Tracor Northern 5500 IPP 5B/80 image analyzer and a 80386 microprocessor-based imaging system. Between 30 and 50 SEM-generated backscattered electron images (frames) were collected per thin section. Binaries were created from the gray level that represents the pore space. Calculated values were averaged and the data analyzed to determine which geological pore structure characteristics actually affect permeability.
Optimization of LaB6 Cathode Tip Shape for Maximum Brightness Over Lifetime
Authors: Christman Locke 
Published: June 2020

LaB6 cathodes are widely used as high brightness cathodes in electron microscopy and are capable of providing about five times the brightness of a tungsten hairpin filament. It is desirable to optimize the shape of the LaB6 tip to provide the highest possible brightness and to insure that this high level of brightness is maintained over the life of the cathode.It is well known that a high brightness electron beam is important in obtaining ultimate resolution in electron microscopy. Brightness is defined as the current density per unit solid angle, or amperes per square centimeter per steradian, in the electron beam. In electron microscopy, one would like to obtain the maximum possible brightness for the particular electron gun. Brightness is a conserved quantity, meaning that as the beam traverses the column, brightness can not be gained, only lost. Therefore, one must begin with the brightest possible cathode in order to obtain the best possible electron beam brightness.Much work has been done to determine the optimum LaB6 cathode tip shape and crystallographic orientation which will provide the highest brightness over cathode lifetime. The purpose of this is to review some of the previous results, present further data, and draw conclusions as to the optimum LaB6 cathode tip shape for high sustained brightness over cathode life. Nearly all commercially available LaB6 cathodes for electron microscopy employ an axially oriented LaB6 <100> crystal with a conical tip. Most are made with a full cone angle of 2α=90° (Figure 1). Some have a small radius, hemispherical point at the apex of the cone, while others simply have a small diameter truncation (flat) on top of the cone. The geometrical parameters affecting cathode brightness which will be considered here are hemispherical tip radius (R) and flat diameter (ϕ). Of primary interest is the dependence of brightness over lifetime with the variation of these parameters, and the comparison between the hemispherical and the flat tips.
Performance and Capabilities of a New, Integrated SEM Image Store
Authors: Gross U. , Mulder J.C. 
Published: June 2020

Loosely-coupled, add-on image stores have been used in electron microscopy for some years. Only recently have they been more closely integrated into the system architecture. With the introduction of the new XL series of scanning electron microscopes Philips goes one step further by making the image store the central image information switchboard with one common user interface for all microscope functions (Fig. 1).Fig. 2 shows the functional structure of the XL image store.Each of the dual-port, dual-speed memory boards (MEM) stores two 8 bit planes of 680 lines (of which 525 are used complying with the US TV standard) containing 768 pixels each. Up to four boards can be used. It is possible to couple four image planes to form one high definition display area of 1050 lines and 1572 pixels which can be fully used for image acquisition and for hardcopy. The monitor then shows either a full image in normal definition or a quarter of an image in high definition, which can be positioned at will within the image area.Signal transfer is performed by three 16 bits wide image data buses, one of which (MAIN DISPLAY BUS) is always driven at TV rate, whereas the other two (SIGNAL PROCESSOR and AUX DISPLAY BUS) follow the speed of the input signal. This extremely flexible bus concept not only allows normal recursive averaging and integration as described by O'Keefe et.al., but also two-dimensional convolutions on acquired images within only a few TV cycles. Different processing schemes can be chosen inside and outside the selected area.
Low - Voltage Scanning Electron Microscopy Imaging, Secondary and Backscatter, With Microchannel Plate Detector
Authors: Powers Galen , Cochran Ray 
Published: June 2020

The capability to obtain symmetrical images at voltages as low as 200 eV and beam currents less than 9 pico amps is believed to be advantageous for metrology and study of dielectric or biological samples. Symmetrical images should allow more precise and accurate line width measurements than currently achievable by traditional secondary electron detectors. The low voltage and current capability should allow imaging of samples which traditionally have been difficult because of charging or electron beam damage.The detector system consists of a lens mounted dual anode MicroChannel Plate (MCP) detector, vacuum interface, power supplies, and signal conditioning to interface directly to the video card of the SEM. The detector has been miniaturized so that it does not interfere with normal operation of the SEM sample handling and alternate detector operation. Biasing of the detector collection face will either add secondaries to the backscatter signal or reject secondaries yielding only a backscatter image. The dual anode design allows A−B signal processing to provide topological information as well as symmetrical A+B images.Photomicrographs will show some of the system capabilities. Resolution will be documented with gold on carbon. Variation of voltage, beam current, and working distance on dielectric samples such as glass and photoresist will demonstrate effects of common parameter changes.
Scanning Transmission and Computer-Aided Volumic Electron Microscopy: 3D Modeling of Entire Cells by Electronic Imaging
Authors: Bron Cph. , Gremillet Ph. , Launay D. , Jourliny M. , Gautschi HP. , Bächi Th. , Schüpbach J. 
Published: June 2020

The digital processing of electron microscopic images from serial sections containing laser-induced topographical references allows a 3-D reconstruction at a depth resolution of 30 to 40 nm of entire cells by the use of image analysis methods, as already demonstrated for Transmission Electron Microscopy (TEM) coupled with a video camera. (Cf ref)We decided to use a Scanning Transmission Electron Microscope (STEM) to get higher contrast and better resolution at medium magnification. The scanning of our specimens at video frequencies is an attractive and easy way to link a STEM with an image processing system (see Fig 1) but the hysteresis of the electronic spools responsible for the magnetic deviation of the scanning electron beam induces deformations of images which have to be modelized and corrected before registration. Computer algorithms developed for image analysis and treatment correct the artifacts caused by the use of STEM and by serial sectioning to automatically reconstruct the third dimension of the cells.(see Figs 2 and 3) They permit the normalization of the images through logarithmic processing of the original grey level information. The automatic extraction of cell limits allows to link the image analysis and treatments with image synthesis methods by minimal human intervention. The surface representation and the registered images provide an ultrastructural data base from which quantitative 3-D morphological parameters, as well as otherwise impossible visualizations, can be computed.
Application of Cross Entropy and Factorial Analysis to Image Processing
Authors: Trebbia P. 
Published: June 2020

Most of the time, the problem that image analysis has to face is the following : from a given data set obtained with independant measurements, how to extract the signal (the “useful information”) which is mixed with a background (coming from the object itself or from the detector) and statistical noise? If a pre-knowledge of the specimen (or of the experimental procedure) gives some reasonable hypothesis about an empirical mathematical description of the background and of the noise, then, one can try some “fitting” method (maximum likelihood for example) in order to solve the problem. But if no a-priori model is available, one is reduced to try to understand the “meaning” of the images through an analysis of the information content of the data set. Two main statistical approaches can be of some help in that process:
) first, one can measure from the histogram of the data set some characteristic statistical parameters (mean and variance) and compare it with a gaussian histogram of same mean and variance which would be obtained under the same experimental conditions (same number of detected electrons for example) in a pure random process, that is with a “neutral” specimen showing absolutely no contrast. Then from these two histograms, one may estimate the relative cross entropy, that is the information value added by the real presence of a given object in the specimen chamber. Moreover, one can make a 2D-plot of this information in order to localize the pixels, in the data set, whose intensities significantly differ from a pure random process.) the second possibility is to make a variance analysis of the data set : if we have a pre-knowledge that some of the images in this set do not contain the “contrast information” we are looking for, then, there must be some quantitative difference between these images and the other ones. Among the various algorithms available from multivariate statistics, the factorial analysis has been proved to be suited to this kind of analysis.
Beam-Induced Indeterminacies In The Ivem
Authors: Hobbs Linn W. 
Published: June 2020

Intermediate-voltage electron microscopes accelerate electrons to energies U between 200 keV and 600 keV to take advantage of a U-3/8 improvement in resolving power which enables sub-0.2nm atomic structure projections to be routinely imaged. This exciting prospect is, however, purchased at the price of uncertainties in the integrity of the images obtained, because the investigating probe unavoidably perturbs the structure which is being imaged. Such perturbations have been relegated historically to the anecdotal realm of “radiation effects” but are really a perverse manifestation of the Uncertainty Principle. That electron microscopists are able to resolve the structure of solids at all is a tribute to the strength and mutliplicity of atomic bonds in solids and the large “recoiless fraction” (in the parlance of nuclear spectroscopies like the Mossbauer effect) for which the whole solid, and not an individual atom, recoils from the impact of the investigating probe.Atomic structure is sensitive to the impact of incident IVEM electrons because they lose energy (at a rate of order 1 GeV/m) in traversing a solid, a small portion of which is available as kinetic energy to restructure atomic positions. About 98% of the energy loss goes into electronic excitations which can in certain materials (notably organic materials, halides, silicates and almost anything explosive) destabilize atomic positions within the specimen interior with unnervingly high efficiency by radiolytic processes. Analogous radiolytic loss or restructuring of surface atoms, whose bonding constraints are fewer than for atoms in the interior, has been coined “desorption induced by electronic transitions” (DIET). Of the remaining 2% of the energy loss, which is transferred instead to atomic nuclei, most goes into the generation of heat (the eventual fate of most non-radiative electronic transitions as well), but about 1 part in 105 (or 1 part in 107 overall) is available to generate atomic displacements ballistically, by direct knockon: at the surface for almost all solids examined by IVEM (leading to sputtering) and in the interior for many medium atomic-weight solids.
The Structure of The 70S E. Coli Rtoosome In Ice
Authors: Penczek Pawel , Srivastava Suman , Frank Joachim 
Published: June 2020

We have obtained two reconstructions of the 70S ribosomal subunit embedded in ice using the random-conical method on particles showing two distinctive views.Ribosomes were applied to grids covered with thick holey carbon film whose holes were in turn covered with a second, thin carbon film. The frozen-hydrated preparation was done as described previously using GATAN cryo-transfer equipment and specimen holder on a Philips EM420. The images were taken in pairs at 2μm defocus and a dose of less than 10 e-1/Å2. The first was taken with the specimen tilted to 50°, the second untilted. A total of 838 particles from two micrograph pairs were selected for image analysis.A new reference-free alignment algorithm was used to align the 0°-images. In the subsequent multivariate statistical analysis and factor-space based hierarchical classification, several distinct groups were found, two of which (averages, Fig. 1) with memberships above 10% were selected for two separate 3D reconstructions. The averages were found to have a resolution of 3.3 nm as established by phase residual analysis. For computing the reconstruction, we used an iterative scheme that is based on a Chi-square minimization. In this way, we were able to reduce distortions caused by the missing cone as well as by large gaps in angular spacing.
Video Graphics and High-Voltage Electron Microscopy For Analysis of Microtubule Distributions In Fixed Cells
Authors: Mcintosh Richard , Mastronarde David , McDonald Kent , Ding Rubai 
Published: June 2020

Microtubules (MTs) are cytoplasmic polymers whose dynamics have an influence on cell shape and motility. MTs influence cell behavior both through their growth and disassembly and through the binding of enzymes to their surfaces. In either case, the positions of the MTs change over time as cells grow and develop. We are working on methods to determine where MTs are at different times during either the cell cycle or a morphogenetic event, using thin and thick sections for electron microscopy and computer graphics to model MT distributions.One approach is to track MTs through serial thin sections cut transverse to the MT axis. This work uses a video camera to digitize electron micrographs of cross sections through a MT system and create image files in computer memory. These are aligned and corrected for relative distortions by using the positions of 8 - 10 MTs on adjacent sections to define a general linear transformation that will align and warp adjacent images to an optimum fit. Two hundred MT images are then used to calculate an “average MT”, and this is cross-correlated with each micrograph in the serial set to locate points likely to correspond to MT centers. This set of points is refined through a discriminate analysis that explores each cross correlogram in the neighborhood of every point with a high correlation score.
A program for simulation of changes in diffraction patterns with crystal rotations
Authors: Mijlhoff F.C. , Zandbergenl H.W. 
Published: June 2020

Orientation of crystals for HREM is done in diffraction mode. To do this efficiently thorough knowledge of the electron microscope and the reciprocal lattice of the investigated material is essential. With respect to the electron microscope extensive training is required to obtain the ability to tilt a crystal in the desired orientation. Familiarity with the reciprocal lattice of the investigated materials has to be obtained by tilt experiments on a relatively large number of crystals in the electron microscope. Even for experienced electron microscopists this can be very time consuming.In order to be able to practice tilt experiments without using the electron microscope, a program to simulate the electron microscope in diffraction mode was developed. The inexperienced electron microscopist may use the program to practice tilting of crystals. The experienced microscopist can use the program to familiarize with the reciprocal lattice of materials, which have not been studied by him before.
Measurement of feature clustering in images
Authors: Russ John C. 
Published: June 2020

The spatial distribution of features in an image is often interesting, but not simple to characterize. Mapping of the image into a different space (e.g., Fourier or Hough) offers direct information on various regularities in feature spacing or alignment, but does not deal directly with the individual features. Two other approaches are available; each has advantages and drawbacks, which are discussed here.Schwarz & Exner determine the spatial coordinates of the centroids of features, and sort them to locate the nearest neighbor for each feature present, constructing a distribution plot of the frequency of nearest neighbor distances. Figures 1 and 2 show an example. The three fields in Figure 1 contain, respectively, features which are well-spaced from each other, randomly arranged on the plane, and clustered together. For the random distribution of points, the histogram of nearest neighbor distances is a Poisson distribution, and the mean value is 0.5/NA1/2, where NA is the number of features divided by the area of the image.
Quantitative Scanning Electron Microscopy of the Cellular Structure of Wood
Authors: Reine Barbara A. , Fowler Norman J. , Fisher R. M. 
Published: June 2020

The physical properties of wood, such as density, moisture content, tensile, compression and shear strength, elastic modulus and anisotropy all vary considerably between different species of wood. These variations are reflected in the long standing differentiations into hard and soft woods that have been established as well as quality classifications or commercial grades such as clear grain, select, structural etc. that are commonly used. These variations in properties arise from differences in the size, shape and distribution of the cells, as well as in the thickness of the cellulose-lignin walls that enclose them.Scanning electron micrographs that are representative of the variations in cellular structure that exist between woods are shown in Figure 1 for ultrasoft hard maple and ultrasoft cork oak. These higher magnification images illustrate the duplex cell configuration that is required to sustain the growth of trees and support their height. Although the differences in cell structure are quite apparent in the micrographs, any quantitative interpretation of the various properties mentioned above requires detailed measurements of specific microstructural components to obtain statistically significant measurements of the relevant structural components.
The Scanning Photoelectron Microscope : A Novel Tool in Surface Science
Authors: von Oertzen A. , Rotermund H.H. , Jakubith S. , Kubala S. , Ertl G. 
Published: June 2020

Photoelectron microscopes using electron optics had been built long before. Until recently these microscopes were not widely used in surface science due to unsufficient vacuum conditions as well as weak image intensifying devices. In this paper we will present a new approach to photoelectron microscopy, the Scanning Photoelectron Microscope (SPM).Photoelectron emission will occur as soon as the photon energy is higher than the work function on the illuminated area. Since work functions never exceed 6.5 eV, ultraviolet (UV) light with λ ≥ 190 nm will be appropriate. This kind of radiation is a very gentle probe, even for sensitive adlayers.The experimental setup is shown schematicaly in Fig. 1. A UV light optics outside the ultra high vacuum (UHV) system focusses the actual 30 W Deuterium discharge lamp through a grid monochromator onto a small aperture (50 to 400 microns). The aperture hole is projected with a reflecting microscope objective (Schwarzschild type) onto the surface of the sample yielding a lateral resolution of about 3 microns.