bluuebunny/crossref_metadata_2025_split huggingface dataset:
Information capacity and bandwidth limitations in the SEM
Authors: Joy D. C. , Bunn R. D. 
Published: June 2020

The information available from an SEM image is limited both by the inherent signal to noise ratio that characterizes the image and as a result of the transformations that it may undergo as it is passed through the amplifying circuits of the instrument. In applications such as Critical Dimension Metrology it is necessary to be able to quantify these limitations in order to be able to assess the likely precision of any measurement made with the microscope.The information capacity of an SEM signal, defined as the minimum number of bits needed to encode the output signal, depends on the signal to noise ratio of the image - which in turn depends on the probe size and source brightness and acquisition time per pixel - and on the efficiency of the specimen in producing the signal that is being observed. A detailed analysis of the secondary electron case shows that the information capacity C (bits/pixel) of the SEM signal channel could be written as :
The JSM-890 ultra high resolution Scanning Electron Microscope
Authors: Kersker M. , Nielsen C. , Otsuji H. , Miyokawa T. , Nakagawa S. 
Published: June 2020

Historically, ultra high spatial resolution electron microscopy has belonged to the transmission electron microscope. Today, however, ultra high resolution scanning electron microscopes are beginning to challenge the transmission microscope for the highest resolution.To accomplish high resolution surface imaging, not only is high resolution required. It is also necessary that the integrity of the specimen be preserved, i.e., that morphological changes to the specimen during observation are prevented. The two major artifacts introduced during observation are contamination and beam damage, both created by the small, high current-density probes necessary for high signal generation in the scanning instrument. The JSM-890 Ultra High Resolution Scanning Microscope provides the highest resolution probe attainable in a dedicated scanning electron microscope and its design also accounts for the problematical artifacts described above.Extensive experience with scanning transmission electron microscopes lead to the design considerations of the ultra high resolution JSM- 890.
The CM20/STEM: A new 200-kV Scanning Transmission Electron Microscope
Authors: Otten Max T. , de Jong Marc J.C 
Published: June 2020

With the rapid advances in new materials and production techniques in fields such as ceramics, semiconductors, metals, polymers and composites, the demands on analytical techniques for studying these materials are ever increasing. The TEM is ideally suited because of its spatial resolution and large number of different signals (bright-field and dark-field imaging, high-resolution imaging, convergent beam diffraction. X-ray and energy-loss analysis, scanning with bright-field, dark-field, backscattered and secondary electrons, etc). Many TEM’s suffer, however, from an unnecessary restrictiveness in the techniques provided, e.g. top-entry TEM’s without X-ray microanalysis or TEM systems without scanning. In order to provide the materials scientist with a powerful solution for current and future demands in materials research, the new Philips CM20 (Fig. 1) has been designed specifically to incorporate as many techniques as possible with the highest possible performance.In addition to its high electron-optical performance, the CM20’s MICROCONTROLLER, a microprocessor control system with ergonomic control-panel lay-out, ensures ease of use, greatly speeding up operation and enhancing the microscopist’s productivity.
Analysis of embryonic cell division patterns using laser scanning confocal microscopy
Authors: Summers Robert G. , Cheng Ping-chin 
Published: June 2020

As embryogenesis in the sea urchin proceeds, cell number increases and overall synchrony of cell division decreases. Beyond 16 cells, it becomes increasingly more difficult to observe individual cells or populations of cells in whole-mounted embryos because of their thickness (up to 150 μm) and superimposition of nuclei. As a consequence, the patterns of cell division (eg. its timing and synchrony within subpopulations of cells, orientation of the mitotic apparatus relative to axes of embryonic symmetry etc.) in sea urchins and other developing systems remain unclear. Confocal microscopy affords the opportunity to analyze intact embryos and to gain an understanding of the role which cell division plays in morphogenesis of the embryo.Sea urchins (Strongylocentrotus purpuratus) were obtained from Northern California and maintained in artificial sea water. Gametes were obtained and cultures of embryos were prepared in the usual fashion and synchronous cultures of embryos were reared at 15°C. Fixation and Feulgen staining were performed per Nislow and Morill.
Three-dimensional images of DAB-labeled neurons by confocal scanning laser microscopy
Authors: Deitch JS , Smith KL , Lee C , Swann JW , Turner JN 
Published: June 2020

The ability to correlate neuronal morphology and physiology has been greatly advanced by intracellular labeling through the recording pipette. However, visualizing the filled neuron required physically sectioning and reconstructing areas of interest, often resulting in figures that are two-dimensional. We have visualized the three-dimensional morphology of filled neurons reacted with nickel-intensified diaminobenzidine (DAB/Ni) using the confocal scanning laser microscope (CSLM).Neurons in slices of rat hippocampus were filled with biocytin, fixed in 4% paraformaldehyde, incubated in avidin-HRP (1:200) in 0.5% Triton X-100, and reacted with DAB in 0.04% nickel ammonium sulfate. Optical sections and three-dimensional images were recorded by using a Bio Rad MRC-500 CSLM with an argon ion laser.Biocytin filled all aspects of the neuron, including fine axons and spines. Fig. 1 is a conventional micrograph of a single neuron labeled with DAB/Ni. Figs. 2a and b are stereo pairs of the apical and basal dendrites of the neuron in Fig. 1.
Fading of the diaminobenzidine reaction product in the confocal scanning laser microscope
Authors: Deitch JS , Smith KL , Swann JW , Turner JN 
Published: June 2020

Neurons labeled with horseradish peroxidase and reacted with diaminobenzidine (DAB) can be imaged using a confocal scanning laser microscope (CSLM) in the reflection mode. In contrast to fluorescent markers, the DAB reaction product is thought to be stable and can be observed by both light and electron microscopy. We have investigated the sensitivity of the DAB reaction product to laser irradiation, and present the spectrophotometric properties of DAB before and after exposure in the CSLM.Pyramidal neurons in slices of rat hippocampus were injected with biocytin (a biotin-lysine complex), fixed overnight in 4% paraformaldehyde, and vibratome sectioned at 75 μm. Biocytin was detected with avidin-HRP (1:200) in 0.5% Triton X-100, incubated in DAB (0.5 mg/ml) with or without 0.04% nickel ammonium sulfate (Ni), dehydrated, and imaged in a Bio Rad MRC-500 CSLM with an argon ion laser (488 and 514 nm). Spectrophotometric measurements of the soma were made on a Zeiss microspectrophotometer, as a function of laser exposure (100-1000 scans) and staining protocol.
Oxidation, reduction, and stability of the BaLa4Cu5O13±δ system
Authors: Davies P. K. , Katzan C. M. 
Published: June 2020

The electronic and structural properties of most of the high temperature superconducting copper oxides are highly dependent upon the oxidation conditions used to prepare the cuprate compounds. Until recently superconductivity had only been observed in highly oxidized compounds, however recent work has shown that under certain circumstances superconducting transitions can also occur in n-doped, reduced cuprates. In an effort to understand some of the chemical factors that lead to the stabilization of both oxidized and reduced cuprates, we have investigated the stability of several cuprates. In this paper we report our results on the metallic, non-superconducting BaLa4Cu5O13±δ (“145”) system.At high temperature most of the highly oxidized cuprates are reduced as oxygen is reversibly removed from the perovskite lattice and the Cu valence is lowered to ≤ 2. However, for compounds with the 145 stoichiometry there is no significant oxygen loss in “non-reactive” gases such as air, O2 or He, and even at 1000°C Cu is apparently stable in a valence state greater than 2.3+.
A study of oxygen and vacancy ordering in YBa2Cu3O7−x
Authors: Lin Y. P. , O’Reilly A. H. , Greedan J. E. , Post M. 
Published: June 2020

In the basal planes of the orthorhombic YBa2Cu3O7-X compound with x=0.07, which has a Tc of around 90K, chains of copper-oxygen are formed along the [010] direction. Previous investigations on the variation of Tc with oxygen content have shown the existence of a plateau at Tc = 60K for x=0.3 to 0.4, suggesting the presence of a separate phase. This phase has also been identified to be orthorhombic, but with a 2x superlattice along [100] of the parent structure, and the superlattice has been attributed to the formation of alternating copper-oxygen and copper-vacancy chains. In our work, we have studied the chain ordering phenomenon by electron microscopy and neutron diffraction on samples with different oxygen contents. We report here some of our electron microscopy findings for samples with x=0.4.Powder samples of YBa2Cu3O7-X were prepared by controlled re-oxidation of previously reduced material. For electron microscopy, the sample was dry ground using a mortar and pestle in a dry nitrogen atmosphere without the use of any solvent and transferred dry onto holey carbon film for examination in a Philips CM12 microscope.
High-resolution STEM study of grain boundaries in high-Tcsuperconducting YBa2Cu3O7-xthin films
Authors: Shin D. H. , Silcox J. , Lathrop D. K. , Russek S. E. , Buhrman R. A. 
Published: June 2020

The grain boundary structures of high Tcsuperconducting YBa2Cu3O7-xthin films grown on yttrium-stabilized zirconia and MgO have been studied using a VG-HB501A STEM operating at 100 keV (bright field, Cs=1.l mm, αobj=12 mrad,θcol=4 mrad). In Fig. 1, lattice images of various types of grain boundaries of a superconducting film grown on MgO by low-temperature (660 °C) in situ sputtering are shown. This sample has a critical current density of ∼5 × 106amp/cm2at 4 K and a somewhat depressed transition temperature near 70 K possibly due to ion bombardment during the sputtering process and oxygen deficiencies. Beyond a few atomic distances most of the grain boundaries are clean and coherent.Since each grain in the film can take any of the possible orientations satisfying substrate-film lattice matching (along [100], [110], and [120] of the substrate, with either c-axis parallel or c-axis perpendicular, in the case of (100) MgO substrate), several different types of grain boundaries occur. Fig. 1(a) shows a grain boundary between two grains with c-axes in the plane of the substrate. Fig. 1(b), (c), and upper left area of (d) show grain boundaries between two grains, one with c-axis in the plane, and the other with c-axis perpendicular to the plane. At these grain boundaries c-axes are rotated through 90°.
Interfaces in high-Tcsuperconducting oxides
Authors: Carter C. Barry , Tietz Lisa A. 
Published: June 2020

Interfaces in high-Tc superconducting oxides are influential during both the processing of bulk materials and the growth of thin epitactically aligned layers. In the first case, the formation of the superconducting phase involves the movement of phase boundaries during the solid-state reaction, while in the second, the phase boundary is formed as the superconducting material grows on the single-crystal substrate. Having formed the superconducting material, the superconducting phase will, in general, contain a large number of grain boundaries varying from the simple twin boundaries which can be produced during the cubic-to-tetragonal transformation, to low-angle grain boundaries, special high-angle grain boundaries, other high-angle grain boundaries and phase boundaries due to incomplete or on-going solid-state reactions. During the course of this presentation, recent results on these topics will be reviewed, paying particular attention to the more widely studied material, YBa2Cu3O6+x.The importance of grain boundaries in high-Tc superconducting oxides has been firmly established by the systematic analysis of Dimos et al who have shown that the misorientation of the grains in layers of YBa2Cu3O6+xwhich had been grown on polycrystalline SrTiO3substrate varies with the relative misorientation between the grains.
Phase transformations and kinetics in small particles
Authors: Ajayan P. M. 
Published: June 2020

Small particles of metals supported on various substrates are important heterogeneous catalysts. The rate of catalysis depends critically on the surface morphology of these catalysts and can vary significantly due to strong metal substrate interactions. On the other hand the structure of an isolated small particle is ill-defined and has been shown to fluctuate between various forms, existing in a quasi-molten state. We present here results which shows the transformation of a small particle sitting in a deep potential well on a substrate with a stable shape, into a free floating state which is structurally unstable.The experimental procedure consisted of dispersing gold clusters produced by the reduction of organometallic compounds, onto magnesium oxide smoke particles which were collected onto a microscope grid placed over burning magnesium in air. The specimens were then imaged in a H- 9000 high resolution electron microscope operating at an accelerating voltage of 300 KV. The distribution of small gold panicles on the low energy (100) face of the MgO cube particles is shown in Fig.1
Electron Microscopy study of metal-support interaction in Rh/CeO2 catalysts
Authors: Pan M. , Garcia R. , Smith David J. , Cowley J.M. , Cifredo G.A. 
Published: June 2020

In the characterization of supported metal catalysts, it is important to understand the influence of the support on the metal particles since many catalytic properties are controlled by their interaction. Previous studies of supported Rh catalysts have shown that the oxide support plays an Important role in the activity and stability of the catalysts: the morphology and dispersion as well as the activity of the supported Rh particles can be affected significantly. High resolution electron microscopy (HREM), scanning transmission electron microscopy (STEM) and microdiffraction represent powerful techniques for studying the microstructure of supported small metal particles (<50 Å) and their structural relationship with the support.In this study, the techniques of HREM and STEM/microdiffraction have been combined to characterize the structures of the Rh particles in Rh/CeO2 and their structural relationship with the cerium oxide support. The microscopes used were JEM-200CX, JEM-4000EX and VG HB-5 STEM. The following catalyst samples with various treatments have been studied:
The structure of rapidly solidified Fe-Ni-Mo-Co-B ribbons
Authors: Vanderwalker D. M. 
Published: June 2020

Fundamental aspects of solidification can be examined by experimentation in rapid solidification processing. The structure produced depends on parameters such as cooling rate, degree of undercooling, heat flow, and growth rate. Rapidly solidified iron base alloys are being developed for structural applications.RSR I Fe-19.7Mo-14.4Ni-7.3Co-1.9Bwt % and RSR II Fe-15.0Ni-11.1Mo-7.4Co-0.84B wt% ribbons were melt spun by a jet casting technique. RSR I ribbons were annealed for one hour at 816°C.Specimens were prepared for transmission electron microscopy by punching 3 mm discs from ribbons and electropolishing in a methanol 5% perchloric acid solution.The TEM was performed on the JEM 200CX electron microscope.As solidified RSR I was found to be canposed of fine (7nm) polycrystalline α-Fe. There is evidence for the presence of Ni Mo and FeB (Fig.1). On annealing, the α-Fe transforms to γ-Fe and FeB2Mo2, with significant grain growth (Fig.2). The as-solidified RSR II contains cellular γ-Fe with fcc-Fe2 3B6 of lattice parameter a=l.067nm at the cell walls (Fig. 3).
TEM images of overlapped precipitates
Authors: Hu C.T. 
Published: June 2020

The Ni3Al precipitates with a cubic shape and densely aligned along the [100] direction are always observed in Ni-Al alloys and nickel base superalloys. It is quite frequently observe the overlap of two or more separate Ni3Al particles, which locate at different depths in a thin foil specimen during a TEM examination. However, no one has paied much attention to the variations of intensity and contrast on the overlapped area of two separated particles in TEM dark field image. Hence, the analyzed results of dark field microscopy may give an unfaithful determination of particle size as well as a miscount of the total particle number. This investigation has been concentrated on the image forming mechanism and the explanation of intensity change on the overlap area of two Ni3Al particles.Fig.1 indicates a unit cell with Ll2 structure in Ni3Al precipitate A, and an identical one in precipitate B.
Apparatus for “on-the-fly” sample preparation of aerosol-grown block copolymer microdroplets
Authors: Bellare Jayesh R. , Thomas Edwin L. 
Published: June 2020

The morphology of phase separated amorphous A/B block copolymers depends not only on the relative volume fraction of the A and B components but also on external shape constraints imposed on the sample. Whereas it is well established that thin planar of microstructured copolymers differ considerably from the bulk materials, the influence of roughness and curvature, which are of practical importance in coating technology, are presently unknown. Because the simplest curved surface is a sphere, the effect of surface curvature on block copolymer microdomains can be conveniently studied by TEM observations of spherical microdroplets prepared with the apparatus described here.Samples for microscopy are prepared by the “gunshot” technique: an atomized solution of the copolymer in a homogeneous solvent is allowed to fall onto carbon coated grids. During fall the solvent evaporates, leaving small spheres of the copolymer that continue falling. By means of a special set of tubes along the fall path, the spheres are annealed (by heating in a nitrogen atmosphere) and stained/fixed (by exposure to osmium tetroxide vapors).
Electron microscopic investigation of the structure and morphology of syndiotactic polypropylene
Authors: Lovinger Andrew J. , Lotz Bernard , Davis Don D. 
Published: June 2020

In contrast to its isotactic isomer, syndiotactic polypropylene has received only little attention. Our main source of understanding of its structure is the X-ray study by Conradini et al., who found the chains to have a (t2g2)2 conformation (corresponding to a 4∗2/1 helix with molecular repeat 0.74 nm), and to be packed in a C-centered unit cell as shown in the left side of Fig. 1. We have recently begun a study of the structure, crystallization, and morphology of syndiotactic polypropylene using electron microscopy and diffraction. Here we concentrate specifically on the electron-diffraction evidence as a function of temperature, in order to obtain an understanding of the evolution and variation of structure in this polymer.Thin films of syndiotactic polypropylene (synthesized by Dr. R. E. Cais as reported previously) were prepared by casting from dilute solution in xylenes at ca. 140°c onto freshly cleaved mica substrates. Following evaporation of the solvent, they were melted and then isothermally crystallized at a variety of temperatures. After shadowing with Pt/C and coating with carbon, they were floated off their substrates for examination by transmission electron microscopy (bright- and dark-field) and selected-area electron diffraction at 100-200 keV.
Analysis of interference patterns in acoustic photomicrographs
Authors: Downs Donna A. , El-Shiekh Aly , Tucker Paul A. , Russ John C. 
Published: June 2020

Images from the Scanning Acoustic Microscope (SAM) have been used previously to study fiber orientations in opaque matrices. SAM images are superficially similar to reflected light images. They also frequently exhibit interference patterns which can be used for quantitative analysis. These patterns arise at discontinuities near or intersecting the specimen surface, and result from interference between acoustic waves reflecting from subsurface boundaries and from the specimen surface. For the case of fibers intersecting a planar surface, the position of the interference fringes gives the orientation of the fiber with respect to the surface, and the shape of the fringes indicates any surface irregularities. Thus, if the fiber shape and orientation are known and if the waves are determined to be longitudinal, then fringe spacings can be used to calculate the velocity and attenuation of the longitudinal acoustic wave in the matrix surrounding the fiber.This technique was applied to graphite-epoxy composites, imaged in the SAM at a frequency of 1.2 GHz. First it was determined that other waves, such as shear waves, surface-skimming longitudinal waves, and surface acoustic waves (Rayleigh waves) were not present in the composite. Their addition to the interference pattern would have disrupted the interpretation of the object’s shape and surface features from the longitudinal fringes and complicated the solutions for wave reflections.
Fiber polymer structures in thermally adaptable fabrics
Authors: Goynes W. R. , Vigo T. L. , Bruno J. S. 
Published: June 2020

Textile fabrics can be given temperature-adjusting properties by finishing them with formulation of polyethylene glycols (PEGs) and dimethyloldihydroxyethylene urea (DMDHEU) applied in a pad-dry-cure process. This treated fabric increases wearer comfort by lowering or raising its temperature as it is heated or cooled. In addition to thermal properties, these finishes produce improved resistance to abrasion, pilling, static charges, and oily soil deposition. Great increases in water absorbency and moisture regain are also achieved.Property changes in chemically finished fibers and fabrics generally correlate with changes in morphological structures related to the finish. Optical, and transmission and scanning electron microscopy were used to study structural changes in the thermally-adaptable fabrics to better understand property changes, and to modify finishing procedures in order to maximize property improvements. Finished cotton, cotton/polyester, and wool fabrics were studied.