bluuebunny/crossref_metadata_2025_split huggingface dataset:
Evidence for very high order laue zone (VHOLZ) lines in CBED patterns
Authors: Sung C. M. 
Published: June 2020

It is well known that High Order Laue Zone (HOLZ) line analysis is a powerful tool to study lattice parameter changes due to local chemical composition and microstrain, in addition to determining crystal symmetry. One of the first approaches described by Ecob et al for indexing the HOLZ reflections does not simulate all the observed HOLZ lines. Therefore a more complete computer program for indexing all the observed HOLZ reflections based on kinematical conditions has been developed using the visibility criterion originally developed for Kossel lines. This approach is easy and more accurate. With this technique we have been able to identify very high order Laue zone lines (>3rd order) in low symmetry orientations and index them.Figs, la and lb are computer simulations which show the indexed HOLZ reflections for the second order (SOLZ) and fourth order Laue zone (FOROLZ) in the <116> zone axis. The corresponding defect HOLZ lines in the transmitted disk from pure Al are shown along with computer-simulated patterns for both the SOLZ and FOROLZ in Figs. 2a and 2b respectively.
Study of segregation in La1.8Sr0.2CuO4 superconductor by STEM-EDS microanalysis
Authors: Kelly T. F. , Lee P. J. , Hellstrom E. E. , Larbalestier D. C. 
Published: June 2020

Recently there has been much excitement over a new class of high Tc (>30 K) ceramic superconductors of the form A1-xBxCuO4-x, where A is a rare earth and B is from Group II. Unfortunately these materials have only been able to support small transport current densities 1-10 A/cm2. It is very desirable to increase these values by 2 to 3 orders of magnitude for useful high field applications. The reason for these small transport currents is as yet unknown. Evidence has, however, been presented for superconducting clusters on a 50-100 nm scale and on a 1-3 μm scale. We therefore planned a detailed TEM and STEM microanalysis study in order to see whether any evidence for the clusters could be seen.A La1.8Sr0.2Cu04 pellet was cut into 1 mm thick slices from which 3 mm discs were cut. The discs were subsequently mechanically ground to 100 μm total thickness and dimpled to 20 μm thickness at the center.
Developments in the processing of electron energy-loss spectra
Authors: Egerton R.F. 
Published: June 2020

Because the total-inelastic mean free path is generally comparable to the specimen thickness, energy-loss spectra recorded in a TEM contain appreciable contributions from plural (or multiple) scattering, which imparts no additional information but may distort or submerge characteristic features. Happily, the single-scattering spectrum S(E) can be derived from a recorded spectrum by the method of Fourier-log deconvolution; if j(f) and z(f) are the Fourier transforms of the recorded data J(E) and of the zero-loss peak Z(E), the Fourier transform s(f) of the single-scattering distribution S(E) is given by:s(f) = r(f) loge [j(f)/z(f)] (1)Here, r(f) is the Fourier transform of a bell-shaped reconvolution function R(E); if r(f) were omitted from Eq.(l), s(f) would correspond to an ‘ideal’ single-scattering distribution, unbroadened by the instrumental resolution △E.
Studies of the scanning ion beam sputter-cleaned MgO crystal surface by scanning reflection electron microscopy
Authors: Ou H.-J. , Cowley J. M. , Higgs A. A. 
Published: June 2020

A scanning ion gun system has been installed on the specimen preparation chamber (pressure ∼5xl0-8 torr) of the VG-HB5 STEM microscope. By using the specimen current imaging technique, it is possible to use an ion beam to sputter-clean the preferred surface region on a bulk sample. As shown in figure 1, the X-Y raster-gate control of the scanning unit for the Krato Mini-Beam I is used to minimize the beam raster area down to a 800μm x800μm square region. With beam energy of 2.5KeV, the MgO cleavage surface has been ion sputter-cleaned for less than 1 minute. The carbon film or other contaminant, introduced during the cleavage process in air, is mostly removed from the MgO crystal surfaces.The immediate SREM inspection of this as-cleaned MgO surface, within the adjacent STEM microscope, has revealed the detailed surface structures of atomic steps, which were difficult to observe on the as-cleaved MgO surfaces in the previous studies.
Identification of a new phase in the Ai-C-B ternary by high-resolution transmission electron microscopy
Authors: Sarikaya M. , Laoui T. , Milius D. L. , Aksay I. A. 
Published: June 2020

The purpose of this note is to report the identification of a ternary (XI) phase which has been observed as a reaction product during the processing of B4C-Al composites. These ceramic-metal composites (cermets) have the unique potential for structural applications because of their low density (> 2.6 g/cc) and a desirable combination of mechanical properties. Guidelines for the processing of B4C-Al have been successfully established; and now it is possible to produce tailored microstructures with varying amounts of constituent phases.The samples for the analysis were prepared by the following procedure. First, it was necessary to heat the B4C powder compacts in excess of 2000°C to attain an interconnected B4C skeletal structure. Liquid aluminum was then infiltrated into this B4C network at 1170°C.
“Stm” Scanning Tunneling Microscopy
Authors: Kubby J. A. 
Published: June 2020

Scanning Tunneling Microscopy is a recently developed technique within the area of Scanned Image Microscopy that is based on tunneling between two conducting electrodes. This method offers, for the first time, the possibility of direct, real space determination of surface atomic and electronic structure in three dimensions on an atomic length scale, including nonperiodic structures.In this technique a sharp metal tip, mounted on a piezoelectric tripod that forms an orthogonal coordinate system, is brought to within a few Angstroms of the sample surface without “touching” the region to be scanned. A tunneling current I, on the order of 0.1 to 1 nA, is established by applying a bias between the tip and sample. The tunneling current is given to first order by;
Analytical Electron Microscopy of Automotive Catalysts
Authors: Chen Y. L. , Powell B. R. 
Published: June 2020

The automotive industry uses catalytic converters to reduce the amounts of regulated emissions that are released to the atmosphere from engine exhaust gases. However, given the presence of catalyst poisons in the exhaust gases and operating temperatures in the converter that frequently exceed 700 °C, durability is a major concern for the catalyst. A detailed understanding of the catalyst deactivation mechanisms (poisoning and particle growth of noble metal particles) is essential to the development of more durable catalysts.Most studies of catalyst deactivation have relied on bulk analytical characterization techniques such as chemisorption, chemical analysis, and x-ray diffraction. Unfortunately, these conventional techniques yield ambiguous and incomplete information about the catalyst because they fail to give a description of the catalyst at the microscopic level where catalysis occurs.
Microstructures of Ni3Al alloyed with iron
Authors: Horton J.A. , Liu C.T. , Santella M.L. 
Published: June 2020

The nickel aluminide, Ni3Al, is an ordered intermetallic alloy that exhibits an increase in yield stress with an increase in temperature. Recent efforts have alleviated the inherent grain boundary brittleness by microalloying with boron. Alloying additions such as iron can be used to further increase the high temperature yield stress.Microstructures and phase relationships in the aluminides were studied by transmission electron microscopy. A Ni3Al alloy with 10 at.% iron was single phase with the ordered Ll2 structure. Two alloys with 15% iron were found to contain a two-phase, γ + γ', cellular structure that consisted of small islands of crystallographically aligned ordered γ', surrounded by a “web” of disordered γ, Fig. 1. At 20% iron, the cellular structure encompasses nearly the entire specimen. Figure 2, a bright-field, dark-field pair of micrographs, shows the dislocation-cell structures (2a) and the ordered cellular structure (2b) present after tensile deformation at 600°C.
A combined Tem/Apfim study of precipitation in ion-nitrided ultra-low carbon bainitic steel
Authors: Burke M.G. , Palmiere E.J. , DeArdo A.J. 
Published: June 2020

Ion-nitriding represents an attractive and cost-effective process for improving the surface properties (hardness, wear resistance) and fatigue behavior of ultra-low carbon bainitic (ULCB) steels (1). Although the improvements in mechanical properties of nitrided steels are well-documented, precipitation in these steels during the nitriding process has not been studied extensively. The precipitation in ULCB steels is complex due to the presence of Mo, Mn, and Ni. Therefore, to investigate nitride precipitation in these steels, we have employed both TEM and APFIM in order to characterize the ultra-fine precipitates.The material employed in this study was a fully bainitic ULCB steel (0.021C- lMn- 1.4Ni- 1.5Mo- 0.016Ti- 0.05 2Nb -0.001B). Ion-nitriding was performed at 466°C for 14 hours using a mixture of 75% H2 - 25% N2 at a pressure of 2500 millitorr.
Application of Analytical Electron Microscopy to design of creep-resistant advanced austenitic stainless steels
Authors: Maziasz P.J. 
Published: June 2020

Analytical electron microscopy (AEM) has been used for the last ten years to study precipitation produced in reactor-irradiated austenitic stainless steels, such as AISI type 316. These studies have provided the insight to design irradiation resistant steels based on control of precipitiation. More recently, similar insight into precipitation effects in steels allowed the design of advanced austenitics that also exhibit outstanding thermal creep resistance at 700°C. These steels have direct application for superheater/ reheater tubing materials that will withstand higher temperatures and stresses in advanced steam cycle fossil power plants.Fine particles (<10 nm in diam) on extraction replicas have been studied by AEM using a high brightness electron source to provide sufficient probe currents for reliable analyses. These studies allowed alloy compositional modifications to be selected that produced stable, fine precipitates for creep strength.
Electron microscopy of TMT Al-Li-Cu alloys
Authors: Radmilovic V. , Nelson C. , Thomas G. 
Published: June 2020

The Al-Li series of alloys are now receiving broad and intensive research attention due to their attractive strength-weight and elastic modulus properties. Their disadvantages center around inadequate fracture toughness and corrosion properties unless complex thermal mechanical treatments (TMS) are employed so as to make the microstructures more uniform. In this regard there are similarities to the Al-Zn-Mg alloys for which also special TMT treatments have been successful.Thus the present research work is concerned with characterizing the microstructure following various TMT procedures of an A1-2.35%Li-2.49%Cu- 0.13 %Zr alloy prepared by Alcoa as part of a broad research program on these alloys. The specific treatment to be reported on here is as follows:- (i) Solution treat 550°C 2 hrs. ice brine quench, (ii) Aged 175°C for 1 hr. (iii) 10% cold rolling, (iv) Re-age 175°C for 15 hrs.
Defect structure and mechanical twinning in rolled and annealed tantalum
Authors: Chatterjee T. K. , Feng C. 
Published: June 2020

Twinning, in association with martensitic shear has been extensively discussed in the literature for high carbon steel. This paper describes similar twinning operations observed in as rolled and annealed tantalum plate. The study was performed at 12øKV in a Philips electron microscope. As rolled and rolled/annealed tantalum plate, 8mm thick were first cut into 25ø um thin sections using a slow speed diamond saw, then ion milled to a thickness of 5ø-1øø um and electropolished in a 90 H2Sø4:1øHF solution.High density dislocation tangles forming the cell wall of the subgrain can be seen in the representative area of the rolled tantalum specimen shown in figure 1. The dislocation density within the matrix of the subgrain is about 1ø11/cm2. Dislocation loops, identified by the letter A, are present within the subgrains. Similar dislocation arrays have been reported in other b.c.c. metals.
Nanometer-scale structures produced in oxide films
Authors: Hollenbeck J. L. , Buchanan R. C. 
Published: June 2020

Rapid material removal has been found to occur in a number of metal halide and oxide films at the point of exposure to a high intensity electron beam. As a result, 3-dimensional, nanometer scale (1-100 nm) structures have been produced in these materials. Possible applications of these systems include substrates for high density E-beam data storage and E-beam resist materials for mask fabrication. Other potential applications would include processes where controlled patterning on a nanometer scale is desirable. In this study amorphous thin films of ZrO2, Y2O3 and AI2O3 were deposited onto coated Cu-grid substrates and the mechanism whereby E-beam interaction promoted rapid material removal on a nanometer scale was explored.Films less than 200 nm in thickness were prepared in a Perkin-Elmer Randex 3140-6J sputtering system. Deposition of films directly onto 20 mesh formvar coated TEM grids facilitated handling and allowed immediate analysis by EM techniques.
Polymer decoration : Principle and uses in surface science
Authors: Lotz B. , Wittmann J. C. 
Published: June 2020

The vaporization and condensation of gold particles introduced by G. A. Basset has become a classical method in surface investigation by electron microscopy. The “gold decoration” of small drops reveals steps of atomic diameter on the surface of alkali halides.Recently, an original decoration technique has been introduced, which is similar in its principle and experimental set up to gold decoration, but uses polymer molecules rather than gold as the marker. The vaporized polymer (typically polyethylene) has a molecular weight of ∼ 1300, i.e. is an elongated cylinder about 100 Å long and 5 Å diameter; this shape makes it a directional marker, in sharp constrast to gold atoms. The molecules build up small rods (in essence, polymer lamellae seen edge on) visible by conventional electron microscopy. The pattern of these rods (the “polymer decoration“) reveals some of the substrate structural features and can be used to analyze polymer-substrate interactions.
The structure of sunlight-degraded polypropylene textile fibers
Authors: Barish Leo 
Published: June 2020

Most investigations relating to the miorostructure of light-degraded polypropylene have been made on film or bulk polymer. Some studies have been made in monofilaments but little on fine textile-grade fiber.Sunlight-degraded polypropylene fibers were obtained from the top surface of an automobile seat cover that had been in service for about five years. The degraded fibers were taken from an area at the top of the back cushion beneath the non-tinted rear window; an area not subject to abrasion but very susceptible to direct sunlight. The origin of these fibers is unknown as is the possible presence of photoinhibitors. From a shaded, undamaged part of the seat cover, undegraded fibers were obtained and examined; they appeared to be round, slightly crimped, bright with little pigmentation, and measured 31.8 μm in diameter, which corresponds to a nominal 0.72 tex or 6.5 denier.
TEM analysis of core/shell latex morphology
Authors: Shaffer O.L. , El-Aasser M.S. , Vanderhoff J.W. 
Published: June 2020

Transmission electron microscopy is an excellent method to study particle size and particle morphology of latexes. Special sample techniques are utilized in the study of latexes and often more than one technique is needed to answer questions concerning the structure of the particle. If the latex is of a core/shell type the study becomes more complex. Sample preparation for studying latexes include staining with osmium tetroxide to crosslink and stain unsaturated polymers, cold stage if the latex is too soft to examine at room temperature, negative staining to increase contrast shadowing to determine the sag of the particle at room temperature, ultramicrotoming, cryoultramicrotoming or a combination of techniques such as staining and cold stage.The latex investigated was the first stage seed latex of poly (butylacrylate - butadiene) and the final latex a core-shell of poly(butylacrylate - butadiene)/poly(methyl methacrylate). Because of its unsaturation, poly(butadiene) can be preferentially stained with osmium tetroxide.
Extracellular matrix morphogenesis: HVEM analysis
Authors: Birk David E. , Trelstad Robert L. 
Published: June 2020

Matrix morphogenesis requires the synthesis, assembly and deposition of collagen molecules in a tissue specific manner. Collagen fibrillogenesis is a multistep process involving both intracellular and extracellular assembly reactions. Collagen synthesis, molecular assembly and formation of supramolecular aggregates occurs within a series of well defined cytoplasmic compartments while the assembly and deposition of the newly synthesized collagen fibrils, fibril bundles and tissue specific collagen macroaggregates occurs within a series of extracellular compartments defined by the fibroblast.In the studies described here we will focus our attention on the cellular influences involved in the assembly of collagen molecules into fibrils, fibril bundles and tissue specific macroaggregates. The chick tendon and corneal fibroblasts partition the extracellular space during morphogenesis, forming at least three compartments. These extracytoplasmic compartments have been described using high voltage electron microscopy of thick sections and serial thick sections as well as by conventional transmission electron microscopy.
Cell morphology, volume, and surface area determinations from multilevel contouring within HVEM micrographs of serial sections and whole-cell mounts
Authors: Marko M. , Leith A. , Parsons D. 
Published: June 2020

The use of serial sections and computer-based 3-D reconstruction techniques affords an opportunity not only to visualize the shape and distribution of the structures being studied, but also to determine their volumes and surface areas. Up until now, this has been done using serial ultrathin sections.The serial-section approach differs from the stereo logical methods of Weibel in that it is based on the Information from a set of single, complete cells (or organelles) rather than on a random 2-dimensional sampling of a population of cells. Because of this, it can more easily provide absolute values of volume and surface area, especially for highly-complex structures. It also allows study of individual variation among the cells, and study of structures which occur only infrequently.We have developed a system for 3-D reconstruction of objects from stereo-pair electron micrographs of thick specimens.
Electron microscopy of endomyocardial biopsies: Diagnostic and research applications
Authors: Ferrans V. J. 
Published: June 2020

The development of safe techniques for obtaining right and left ventricular endomyocardial biopsy specimens with a bioptome catheter has provided the opportunity to examine the ultrastructural changes that occur in myocardium in a variety of disease states, particularly in the cardiomyopathies.The most prominent microscopic abnormalities in hypertrophic cardiomyopathy are: a marked degree of myocyte enlargement, extensive foci of disarray of the myocytes (involving more than 5% of the cells), variable degrees of interstitial fibrosis, and fibromuscular intimal and medial thickening of small intramural coronary arteries. The myocytes have enlarged nuclei, increased numbers of mitochondria, which often accumulate in the perinuclear regions, and irregularly located intercellular junctions, which make extensive contacts not only at the ends of the cells but also along their sides. The disarray of the myocytes is accompanied by disarray of the myofibrils and myofilaments, which often form crisscrossing patterns.
Immunoelectron microscopy in normal and diseased elastic tissues
Authors: Fanning J. C. , White J. F. , Kumaratilake J. , Gibson M. A. , Cleary E. G. 
Published: June 2020

Elastic tissue is recognised to be composed of a major amorphous component (consisting of the protein elastin) and a lesser microfibrillar component (complex structures containing at least two glycoproteins). The study of the components of elastic fibers in developing tissues has been hampered by the difficulty of establishing that the amorphous component is distinguishable from other amorphous structures. This is particularly a problem when the elastic material is deranged, so that the amorphous component is atypical in appearance. We have developed, in rabbits, and then affinity-purified, polyclonal antibodies to each of elastin (the amorphous component), “reductive guanidine extracts” of fetal bovine nuchal ligament and to a microfibril-associated glycoprotein (MAGP) isolated from these extracts.Samples of fetal and adult bovine tissues, including aorta, skin and nuchal ligament; and human tissues; including skin, aorta and breast cancers, were fixed for 4 h in 4% paraformaldehyde and 0.2% glutaraldehyde in phosphate buffered saline, pH 7.4, containing 4% sucrose and 5% polyvinyl pyrolidine;
Ultrastructural investigation of an adenoma of the pituitary post mortem
Authors: Siew Shirley , deMendonca W. C. 
Published: June 2020

The deleterious effect of post mortem degeneration results in a progressive loss of ultrastructural detail. This had led to reluctance (if not refusal) to examine autopsy material by means of transmission electron microscopy. Nevertheless, Johannesen has drawn attention to the fact that a sufficient amount of significant features may be preserved in order to enable the establishment of a definitive diagnosis, even on “graveyard” tissue.Routine histopathology of the autopsy organs of a woman of 78 showed the presence of a well circumscribed adenoma in the anterior lobe of the pituitary. The lesion came into close apposition to the pars intermedia. Its architecture was more compact and less vascular than that of the anterior lobe. However, there was some grouping of the cells in relation to blood vessels. The cells tended to be smaller, with a higher nucleocytoplasmic ratio. The cytoplasm showed a paucity of granules. In some of the cells, it was eosinophilic.
Visualization of the polymerization dynamics of individual 25nm-diameter microtubules in real time
Authors: Salmon E. D. , Walker R. A. , O'Brien E. T. , Pryer N. K. , Voter W. A. , Erickson H. P. 
Published: June 2020

Microtubules (Mts) of the interphase cytoplasmic Mt complex (CMTC) and the mitotic spindle are dynamic polymers assembled from a cellular pool of tubulin by end-dependent association-dissociation reactions (1,2). Mts have an intrinsic structural polarity, which orients the direction of cell motility. Mts also play a major role in the active translocation of vesicles and chromosomes. Quantitative fluorescence microscopy studies using fluorescently labeled tubulin microinjected into living cells have shown that the great majority of Mts in the CMTC and the spindle exchange rapidly with tubulins in the cellular pool (2,3). Dynamic instability, as proposed by Mitchison and Kirschner, provides the best explanation for this rapid turnover of microtubules (1,2).Three major temporal phases of Mt polymerization and three major abrupt transitions between these phases characterize the dynamic instability behavior of pure tubulin (Fig. 1).