bluuebunny/crossref_metadata_2025_split huggingface dataset:
Fluorescence, Confocal, and Intermediate Voltage Electron Microscopy of Centractin Localization in Transfected PtK2 Cells
Authors: Holleran Elizabeth A. , Gray-Board Gladys , Holzbaur Erika L.F. , Peachey Lee D. 
Published: June 2020

Centractin (Arp 1) is an actin-related protein that shares 53% sequence identity with conventional actin and is predicted to have a similar core structure for nucleotide binding. Biochemical studies of centractin, named for its apparent localization to the centrosome, reveal that it is a member of a stable macromolecular complex, dynactin. The dynactin complex consists of at least 9 polypeptides and has been implicated in activating dynein mediated vesicle transport along microtubules. Ultra-structural analysis, by rotary shadowing electron microscopy with antibody decoration, reveals that within the context of the dynactin complex, centractin forms a 37 nm filament resembling the structure of an actin filament with capping protein and p62 localizing to opposite ends.We have used transient transfection assays to investigate the effects of overexpression of centractin in cells. Mammalian PtK2 cells were transiently transfected with centractin cloned in the pcDNA3 vector under the control of a CMV promoter. The cells were transfected for 24 hours using Ca2+/DNA co-precipitates. The transfection efficiency was as high as 41 % as determined by direct counting of immunostained cells. Cells were fixed at time points ranging from 18 to 24 hours post washing using 1% formaldehyde plus 1% Triton X-100 (5 min), 0.05% glutaraldehyde (5 min), 1 % formaldehyde (5 min), and 0.05% sodium borohydride to block free aldehyde groups (3×5 min). Immunofluorescence employed an affinity-purified, rabbit polyclonal antibody to centractin followed by a Texas Red-labeled secondary antibody. Epifluorescence microscopy revealed that all of the cells overexpressing centractin contained centractin structures with novel morphology. Two distinct patterns were observed consistently: filamentous centractin localized throughout the cytoplasm (Figure la) and perinuclear centractin accumulations (Figure lb). The perinuclear accumulations appear to be highly three dimensional and curved in structure (confirmed by confocal microscopy), and often have associated filamentous structures (Figure lb). The addition of 33 micromolar nocodozole (30 min. at 4°C) to the transfected cells results in thinner centractin filaments (Figure lc).
The structure of frozen-hydrated membrane skeletons of human red blood cells
Authors: Yang Li , Josephs Robert 
Published: June 2020

The red cell membrane skeleton is a two-dimensional network of structural proteins attached to the cytoplasmic surface of the erythrocyte membrane. The major components of the skeletal network are spectrin, actin and band 4.1. Reversible shape changes in the red cell are believed to be mediated by changes in the conformation of spectrin. In this study cryo electron microscopy was used to examine membrane skeletons that were embedded in a thin layer of vitreous ice supported by a fenestrated carbon film. This avoids drying and flattening effects and the attendant changes in salt concentrations and pH associated with negative staining.Ghosts derived from normal human red cells were incubated with 4 volumes of 2.5% Triton X-100 in 5 mM sodium phosphate (pH 7.6) for 1 hour at 4°C. Membrane skeletons were isolated on a discontinuous density gradient of 10% and 60% sucrose and dialyzed against 1 mM sodium phosphate buffer (pH 8) containing 0.1 mM DTT for 4-6 hours. Skeletons were applied to carboncoated fenestrated films that had been treated with 1% Alcian blue and rinsed thoroughly with distilled H2O and frozen in liquid ethane. The specimens were examined at -172°C in a Philips CM10 microscope.
Pinning of 90° domain boundaries at interface dislocations in BaTiO3/LaAIO3 {100}
Authors: Dai Z.-R. , Wang Z.L. , Duan X.F. , Zhang J. 
Published: June 2020

Epitaxially grown BaTiO3 thin films have potential applications in microelectronics and integrated photonics. The ferroelectric property of this material is largely determined by the domain structure. It is believed that the structure of the substrate would have profound effect on the quality of BaTiO3 epitaxial thin films. This paper reports our studies on the pinning of 90° domain boundaries at interface dislocations.Epitaxial BaTiO3 thin films were deposited on single crystalline LaAIO3 (100) substrates at 800°C by metal-organic chemical vapor deposition (MOCVD). Cross-section specimens of the films were studied at 200 kV using an JEOL 2010 high-resolution transmission electron microscope (HRTEM).
Computer simulations for the TEM bend contour technique
Authors: Kolosov Vladimir Yu. , Thölén Anders R. 
Published: June 2020

In this paper we give a short overview of two TEM applications utilizing the extinction bend contour technique (BC) giving the advantages and disadvantages; especially we consider two areas in which the BC technique remains unique. Special attention is given to an approach including computer simulations of TEM micrographs.BC patterns are often observed in TEM studies but are rarely exploited in a serious way. However, this type of diffraction contrast was one of the first to be used for analysis of imperfections in crystalline foils, but since then only some groups have utilized the BC technique. The most extensive studies were performed by Steeds, Eades and colleagues. They were the first to demonstrate the unique possibilities of the BC method and named it real space crystallography, which developed later into the somewhat similar but more powerful convergent beam method. Maybe, due to the difficulties in analysis, BCs have seldom been used in TEM, and then mainly to visualize different imperfections and transformations.
Electronic structure studies of conducting polymers by electron energy-loss spectroscopy
Authors: Fink J. 
Published: June 2020

Conducting polymers comprises a new class of materials achieving electrical conductivities which rival those of the best metals. The parent compounds (conjugated polymers) are quasi-one-dimensional semiconductors. These polymers can be doped by electron acceptors or electron donors. The prototype of these materials is polyacetylene (PA). There are various other conjugated polymers such as polyparaphenylene, polyphenylenevinylene, polypoyrrole or polythiophene. The doped systems, i.e. the conducting polymers, have intersting potential technological applications such as replacement of conventional metals in electronic shielding and antistatic equipment, rechargable batteries, and flexible light emitting diodes.Although these systems have been investigated almost 20 years, the electronic structure of the doped metallic systems is not clear and even the reason for the gap in undoped semiconducting systems is under discussion.
Quantitative high-resolution electron microscopy (HREM) of defects in ordered polymers
Authors: Wilson Patricia M. , Martin David C. 
Published: June 2020

Efforts in our laboratory and elsewhere have established the utility of low dose high resolution electron microscopy (HREM) for imaging the microstructure of crystalline and liquid crystalline polymers. In a number of polymer systems, direct imaging of the lattice spacings by HREM has provided information about the size, shape, and relative orientation of ordered domains in these materials. However, because of the extent of disorder typical in many polymer microstructures, and because of the sensitivity of most polymer materials to electron beam damage, there have been few studies where the contrast observed in HREM images has been analyzed in a quantitative fashion.Here, we discuss two instances where quantitative information about HREM images has been used to provide new insight about the organization of crystalline polymers in the solid-state. In the first, we study the distortion of the polymer lattice planes near the core of an edge dislocation and compare these results to theories of dislocations in anisotropic and liquid crystalline solids. In the second, we investigate the variations in HREM contrast near the edge of wedge-shaped samples. The polymer used in this study was the diacetylene DCHD, which is stable to electron beam damage (Jc = 20 C/cm2) and highly crystalline. The instrument used in this work was a JEOL 4000 EX HRTEM with a beam blanidng device. More recently, the 4000 EX has been installed with instrumentation for dynamically recording scattered electron beam currents.
In-Situ measurements of plane spacing during electromigration in a passivated AI line
Authors: Wang P.-C. , Noyan I. C. , Liniger E. G. , Hu C.-K. , Cargill G. S. 
Published: June 2020

To determine the effect of confinement on the material transport that occurs during electromigration, in-situ x-ray strain measurements were conducted along the length of a passivated Al line that was first heated (in two steps) to 267°C and then subjected to current flow.The specimen geometry used in the experiment is shown in Figure 1. Further details can be obtained from references 1,2. The Al in the line and the contact pads had a grain size of the order of the film thickness (0.5 μm) and exhibited strong 111 texture with a range of ±5 degrees. The W pads also exhibited strong 110 texture and had much finer grain size. The x-ray measurements were carried out on the NSLS X-26C beamline using a focussing tapered capillary for collimating the beam. The irradiated area on the line was a 10μmx10μm square. The Al 111 plane spacing (d111) was measured using white beam (Laue) diffraction with a solid-state detector. This plane spacing was measured at different locations along the line.
Principal Component Analysis as a Strategy for Multispectral Acquisition of Images
Authors: Ingram P. , Kopf D. A. , LeFurgey A. 
Published: June 2020

Principal Component Analysis (PCA) has been used by many authors to improve the statistical accuracy and interpretation of multispectral images in a variety of settings from the analysis of satellite radar images to mapping of biological cells and tissues. In this work we describe a strategy to characterize analytical data from biological cryosections by objectively using a scatterplot routine from PCA images to generate masks on the original STEM image; in this way control of the acquisition of spectral data can be performed in a statistically optimal manner.If a set of images are obtained, the corresponding set of Principal Component (PC) images are easily generated. Mathematically, the PC images are the projection of the original images onto a set of orthogonal, complete axes that are the eigenvectors of the symmetric variance-covariance matrix obtained by summing the product of corresponding pixels in each element pair across the entire image (or selected region thereof). The corresponding eigenvalues are the variance contribution of each eigenimage to the total variance of the original set of images. When sorted into order of decreasing variance, the first PC axis represents the greatest covariance that can be found among all the elements; the second represents the largest remaining covariance orthogonal to the first axis and so on. The computation time required for such a calculation is about 10 seconds for eight 128x128 images for a 35 MHz 68040 processor.
Determining Deformation, Recovery and Recrystallization Fractions from Orientation Imaging Microscopy (OIM) Data
Authors: Wright S. I. , Dingley D. J. , Field D. P. 
Published: June 2020

While orientation imaging microscopy (OIM) via automatic analysis of electron backscatter diffraction patterns (EBSPs) has become routine, methods for analyzing results obtained by OIM are still maturing. Interrogating the OIM data to distinguish between deformed, recovered and recrystallized material in a polycrystalline sample is one example. An advantage for using OIM data in such a case is that the corresponding textures can also be determined providing more information regarding these processes. This work reports on two different approaches for distinguishing between these structures from OIM data on a sample of partially recrystallized low-alloy steel.The first approach is, in a sense, patterned after that used in optical microscopy; where, deformed material can be identified because it is more deeply etched than recrystallized material. A similar approach Can be used in OIM by considering the quality of EBSPs. EBSPs from deformed material are more diffuse than patterns obtained from recovered or recrystallized material. At each measurement point in an OIM scan an image quality (IQ) parameter is determined for the corresponding EBSP. The IQ is mapped onto a gray scale and an image is formed from the OIM data as shown in Fig. 1. In this image the measurement points are shaded so that points with associated EBSPs of high IQ receive a lighter shade of gray than points with a lower IQ. The deformed regions can then be identified by the darker regions in the OIM map. However, this method has some drawbacks. The first is that the IQ parameter is not sensitive enough to distinguish recovered material from recrystallized material.
SEM-ECP Analysis of Grain-Boundary Character Distribution in Polycrystalline Materials
Authors: Watanabe Tadao 
Published: June 2020

As demonstrated early 1980’s (1), the scanning electron rnicrocopy-electron channelling pattern (SEM-ECP) technique is very powerful in determination of orientation of individual grains and the character of grain boundaries in polycrystalline materials. Figure 1(a) and (b) show SEM and ECP images of a grain boundary in polycrystal line iron-6.5 mass % silicon ribbon produced by rapid solidification and subsequent annealing. We can intuitively recognize from the SEM-ECP image that the character of the boundary is of <100> tilt type with about 7° misorientation angle. This kind of direct observation is very useful for a study of grain boundary migration and grain growth.This paper discusses advantages of the SEM-ECP technique for the precise determination of the character of grain boundary and for statistical analysis of grain boundaries to bridge roles of individual grain boundaries and bulk properties in a polycrystal. The new microstructural parameter associated with grin boundary termed “grain boundary character distribution (GBCD)” which was introduced by the present author (2,3) and has been utilized in designing and engineering grain boundaries in order to produce desirable and/or high bulk performance in polycrystalline materials (4,5). GBCD describes the type and the frequency of different types of grain boundaries, ie. random general boundaries and special boundaries like low-angle boundaries and low Σ coincidence boundaries.
Microstructure of artificial 45° [001] tilt grain boundaries in YBCO films grown on (001) MgO
Authors: Huang Y. , Vuchic B.V. , Buchholz D.B. , Merkle K.L. , Chang R.P.H. 
Published: June 2020

It is well known that high-angle grain boundaries in YBa2Cu3O7−x (YBCO) show weak-link effects and behave as Josephson junctions. This kind of grain boundary junction (GBJ) has potential applications in magnetic field measurement and electronic devices. This work studies the microstructure of artificially made GBJs in YBCO films on (001) MgO and the mechanism of the boundary formation, with the goal to improve the GBJ quality and obtain a better understanding of the junctions’ transport properties.Ion-sputter-induced epitaxy is used to form YBCO films with isolated 45° [001] tilt grain boundaries. Prior to YBCO film growth the (001) MgO substrate is selectively sputtered by a low energy Ar ion beam. A portion of the substrate remains non-sputtered by protecting the surface with a patterned photoresist mask. After removing the mask, a YBCO film is grown on the substrate using pulsed organometallic molecular beam epitaxy (POMBE). Under suitable conditions single crystal YBCO c-axis films can be reproducibly obtained in both the sputtered and non-sputtered regions. The orientation between the films and the substrate has been examined by both x-ray diffraction and electron diffraction. The in-plane orientation relation is [110]YBCO//[100]MgO on the non-sputtered epitaxially polished MgO and [100]YBCO//[100]MgO on the sputtered MgO. Thus, 45° tilt boundaries are formed in the film at the boundary between the sputtered and non-sputtered substrate regions.
Generation, Processing, and Transferring of CCD Camera Images in Electron Crystallography
Authors: Li Z. G. , Liang L. , Harlow R. L. , Lehman K.E. , Herron N. 
Published: June 2020

Recently, CCD camera has been more and more used in the electron microscopy particularly for electron crystallography [1]. Use of CCD camera in this field as a recording medium possesses many significant advantages over conventional photographic films. A CCD camera has a very high dynamic range (reliable) and produces images directly in digital form which can be conveniently processed and transferred. We have initiated a program to obtain crystal structural information of plate-like materials by processing electron diffraction data from a CCD detector. As part of our program, we have developed a complete and routine procedure to convert images to diffraction data (h, k, l’s and intensities).Figure 1 is a schematic representation of the procedure. Images are initially obtained using a 1024×1024 Gatan CCD camera (model 794) which was attached to JEM-2000EX electron microscope. The collection of the images is controlled by a MAC computer which also stores the data and allows the data to be viewed. Then, the digitized electron diffraction patterns are transferred to a Sun station computer where, using Khoros software, the CCD images are processed. The Khoros system is a very complete image analysis and image processing software developed by University of New Mexico [2].
Development Of a Semi-In-Lens Digital FE-SEM
Authors: Yamamoto Y , Yamada A. , Negishi T. , Kobayashi T. , Watanabe N. , Miyokawa T. , Tamura N. , Nielsen C. 
Published: June 2020

Observation of new materials such as semiconductor, polymer and compounds, with a Field Emission Scanning Microscope (FE-SEM) has been increasingly important in recent years. As the integration scale of semiconductor device as well as nanometer fabrication scale of the new materials are increasing, a high resolution FE-SEM became indispensable for research and development.Since these new materials are often non-conducting and charging, metal coating, minimum electron dose technique or rapid scanning must be used to observe the surface morphology. Furthermore, all the operational sequences have been required to be drastically simplified.We have developed a semi-in-lens fully digital FE-SEM which can obtain high resolution secondary electron images (SEI) with minimum influence of charging at the specimen. An outline of this new FE-SEM is shown in Fig. 1. The electron optical system (EOS) is based on the conventional FESEM (H. Kazumori et al, 1994) with a cold field emission gun (C-FEG), giving a guaranteed resolution of 2.5 nm at an accelerating voltage of lkV. It is possible to select ten scan speeds from 0.28s to 121s in the vertical direction with 1280 × 1024 pixels and average and integrate the SEI signals at the ambient scan speed.
Low-voltage EDS of magnesium ferrite Dendrites in a FEG-SEM
Authors: Johnson Matthew T. , Anderson Ian M. , Bentley Jim , Carter C. Barry 
Published: June 2020

Energy-dispersive X-ray spectrometry (EDS) performed at low (≤ 5 kV) accelerating voltages in the SEM has the potential for providing quantitative microanalytical information with a spatial resolution of ∼100 nm. In the present work, EDS analyses were performed on magnesium ferrite spinel [(MgxFe1−x)Fe2O4] dendrites embedded in a MgO matrix, as shown in Fig. 1. spatial resolution of X-ray microanalysis at conventional accelerating voltages is insufficient for the quantitative analysis of these dendrites, which have widths of the order of a few hundred nanometers, without deconvolution of contributions from the MgO matrix. However, Monte Carlo simulations indicate that the interaction volume for MgFe2O4 is ∼150 nm at 3 kV accelerating voltage and therefore sufficient to analyze the dendrites without matrix contributions.Single-crystal {001}-oriented MgO was reacted with hematite (Fe2O3) powder for 6 h at 1450°C in air and furnace cooled. The specimen was then cleaved to expose a clean cross-section suitable for microanalysis.
SEM/EDS Analysis of Boron in Waste Glasses with Ultrathin Window Detector and Digital Pulse Processor
Authors: Luo J.S. , Wolf S.F. , Ebert W.L. , Bates J.K. 
Published: June 2020

Borosilicate glass has been selected for immobilizing radioactive wastes because of its chemical durability and ability to incorporate many different elements.Boron is an important component in the borosilicate waste glass: its addition facilitates the processibility of glass by lowering its viscosity. In addition, the release of boron is used to measure the corrosion progress during laboratory tests that determine the durability of a glass. Analysis of boron that is present in waste glasses and in the reaction products that form during the reaction of glass is important for understanding the reaction kinetics and mechanism of glass corrosion.Waste glasses have been previously analyzed for B in our laboratory by wavelength-dispersive spectrometry (WDS) in SEM. As can be deduced from Fig. 1, WDS analysis of waste glasses with B concentrations up to 4 wt% yields a line with a slope of 0.4 counts/s/wt%, with a resolution of ˜0.5 wt%. However, EDS is analytically more convenient and advantageous because its high detection efficiency and its ability to simultaneously acquire an entire spectrum. The innovation of the ultra-thin
window has made it possible for an EDS to detect soft x-rays, which are absorbed by a normal Be window.
Beyond fingerprinting: simple but quantitative models of EELS fine structure and the cohesion of interfaces
Authors: Muller D. A. , Singh D.J. , Subramanian S. , Sass S.L. , Silcox J. , Batson P.E. 
Published: June 2020

Spatially resolved EELS in a STEM provides unique opportunities to examine how local structural and electronic properties can affect macroscopic properties of a solid. Perhaps nowhere else are these connections as pronounced as at interfaces. For instance, H embrittles and B strengthens the grain boundaries in Ni3Al, a prototypical high-temperature intermetallic. EELS measurements of these boundaries have revealed the changes in electronic structure that correlate with the altered mechanical properties of the material.The interfacial states, which rarely extend more than an atomic layer or so from the boundary, can only be observed with great care. Not only is a stable microscope and very efficient detector required, but also a good understanding of how the probe interacts with the specimen. Artifacts due to radiation damage are a real possibility. If the boundary is examined in a strongly diffracting orientation (as is often the case with special boundaries) probe dechanneling can profoundly alter the measured spectra. This can be avoided by tilting the boundary a few mrad away from the zone axis, which limits the spatial resolution to being sub-nanometer, but not atomic.