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Yttria-stabilized zirconia (YSZ) is a material that is being considered for use as an inert matrix fuel in nuclear reactors, but a complete characterization of these materials is required for them to be licensed for use. A series of [Nd.sub.x][Y.sub.0.25-x][Zr.sub.0.75][O.sub.1.88] materials have been synthesized using a co-precipitation method, and the thermal stability of these materials has been studied by annealing them at 1400 and 1500°C. (Nd was used as surrogate for Am.) The long-range and local structures of the materials were characterized via powder X-ray diffraction, scanning electron microscopy, wavelength dispersive spectroscopy, and X-ray absorption spectroscopy at the Zr K- and Y K-edges. These results were compared with the previous characterization of Nd-YSZ materials synthesized using a ceramic method. The results indicated that the ordering in the local metal-oxygen polyhedral remains relatively unaffected by the synthetic method, but there was increased long-range disorder in the materials prepared by the co-precipitation method. Further, it was found that the materials produced by the co-precipitation method were unexpectedly unstable when annealed at high temperature. This study highlights the importance of determining the effect of synthetic method on material properties and demonstrates how the co-precipitation route could be used to produce inert matrix fuels. Key words: XAS, ceramics, stabilized zirconia, nuclear energy, XRD. La zircone stabilisee par oxyde d'yttrium (YSZ) constitue un materiau dont l'utilisation est envisagee comme combustible a matrice inerte dans les reacteurs nucleaires, mais une caracterisation complete de tels materiaux est necessaire pour que leur utilisation puisse etre autorisee. Nous avons synthetise une serie de materiaux de formule [Nd.sub.x][Y.sub.0.25- x][Zr.sub.0.75][O.sub.1.88] par une methode de coprecipitation et etudie la stabilite thermique de ces materiaux en les soumettant aun recuit a1400 et 1500°C. (Le Nd a ete employe comme substitut de l'Am.) Par la suite, nous avons caracterise les materiaux en effectuant des analyses structurales d'ordre a longue et a courte distance au moyen de techniques de diffraction des rayons X sur poudre, de microscopie electronique a balayage, de spectroscopie de dispersion des longueurs d'onde et de spectroscopie d'absorption des rayons X au seuil K du Zr et de l'Y. Nous avons compare ces resultats avec les analyses anterieures de caracterisation de materiaux de Nd-YSZ prepares a l'aide d'une methode de synthese de ceramiques. Les resultats ont montre que la methode de synthese a relativement peu d'influence sur l'ordre a courte distance dans le polyedre metal-oxygene, tandis qu'une augmentation du desordre a longue distance a ete observee dans les materiaux synthetises par la methode de coprecipitation. De plus, nous avons observe que les materiaux produits par la methode de coprecipitation presentaient une instabilite imprevue lorsqu'ils etaient soumis au recuit a haute temperature. La presente etude souligne l'importance de determiner l'effet de la methode de synthese sur les proprietes des materiaux et demontre comment la voie de la coprecipitation pourrait etre employee pour produire des combustibles a matrice inerte. [Traduit par la Redaction] Mots-cles: XAS, ceramiques, zircone stabilisee, energie nucleaire, XRD., Introduction World energy demands continue to increase as the world becomes more industrialized, while climate change is dictating that this energy be produced with relatively low carbon emissions. (1-3) Nuclear [...]

ANALYZING ELECTRON MICROSCOPY WITH DEEP LEARNING A significantly faster way to find defects in electron microscopy images is now possible. The Multinode Evolutionary Neural Networks for Deep Learning (MENNDL) creates [...]

Electrical and structural changes in GaAs are monitored using electron beam induced current (EBIC) and transmission electron microscopy (TEM) measurements after irradiation by protons and silicon ions. It has been determined that higher energy protons (E [greater than or equal to] 10 MeV) and silicon ions disordered regions that are electrically and structurally different than those produced by lower energy protons. The data suggest that these disordered regions are responsible for causing the deviations between experimental data and NIEL. From analyses of the recoil spectra, high energy recoils appear to be responsible for the formation of these disordered regions. Index Terms--Defect formation, disordered regions, displacement damage, EBIC, GaAs, heavy ion, irradiation, NIEL, recoil spectrum, recombination centers, TEM.

Ru underlayer effects on the thermal stability of the magnetic properties in Co-Sm amorphous films have been investigated in terms of its robustness for the thermal-process in the fabrication of GHz band micro-magnetic devices. The anisotropy magnetic field [H.sub.k] of the Co-Sm film was tending to decrease with an increase in the annealing temperature, but the reduction in [H.sub.k] due to thermal-process became small by introducing the Ru underlayer. The high-resolution transmission electron microscopy (HR-TEM) observations revealed the presence of nanosized crystalline Sm segregation at the interface between the Co-Sm film and Si[O.sub.2]/Si substrate in the films without Ru underlayer, while there is no Sm segregation in the film with Ru underlayer. Sm segregation and the subsequent thermally induced phase-separation are one of the factors for the reduction in [H.sub.k]. Ru underlayer effectively prevents the segregation of crystalline Sm and the resulting reduction in [H.sub.k]. High-frequency magnetic property of Co-Sm film with Ru underlayer was superior to that without Ru underlayer for same annealing condition. Index Terms--Anisotropy magnetic field, Co-Sm, permeability, thermal stability, underlayer.

Each relative density of carbon overcoat and upper magnetic layer of perpendicular magnetic disks with different corrosion and scratch resistance was measured by transmission electron microscopy electron energy loss spectroscopy (TEM EELS). Corrosion resistance depends on the relative density of both layers, the carbon overcoat and the upper magnetic layer with higher density showed larger corrosion resistance. Scratch resistance did not depend on the density of carbon overcoat, but depended on the density of the upper magnetic layer. Higher density showed higher scratch resistance. This relationship between the relative density of upper magnetic layer and the scratch resistance suggests the deformation of upper magnetic layer affects to scratch damage. As the result of this study, the density evaluation by TEM EELS is useful to estimate the corrosion/scratch resistance tendency of perpendicular magnetic disks, and the higher density of upper magnetic layer is needed to improve the scratch robustness of perpendicular magnetic disks. Index Terms--Magnetic disk, magnetic disk recording, perpendicular magnetic recording, transmission electron microscopy (TEM).

The mechanism of scratch-induced demagnetization was studied in perpendicular magnetic recording (PMR) disks. These scratches, which may occur on the disk's surface during head/disk contact, cause demagnetization that results in read/write errors. The scratch-induced demagnetization is thus investigated by the scratch test, observation of atomic force microscopy and magnetic force microscopy, and analysis of transmission electronic microscopy. It was found that the angle of the grain in the recording layer, which is vertically orientated on a PMR disk, was tilted under the scratch. These analyses revealed that scratch-induced demagnetization is caused mainly by plastic deformation which results in grain tilt in the recording layer, rather than by stress. Therefore, a dense and not-easily rifled grain structure in the recording layer is needed to produce a reliable hard disk drive (HDD). Index Terms--Demagnetization, head-disk interface (HDI), perpendicular magnetic recording (PMR), scratch.

We studied planarization of carbon overcoat by gas cluster ion beam (GCIB) for discrete track magnetic disks. We fabricated discrete tracks with variant pitches by focused ion beam on a 0-am-thick carbon overcoat deposited on magnetic disks, and we planarized them with an Ar GCIB using lateral sputtering effect. It was found that planarization by GCIB was more effective for lower wavelengths than for those with a few hundreds nanometers. On the discrete tracks with 100-nm pitch and 20-nm depth, the initial peaks and valleys were removed by GCIB; however, on the ones with over 200-nm pitch, the initial peaks and valleys remained though the heights were drastically decreased. These results indicate the capability of GCIB planarization as a process for the discrete track media. Furthermore, cross sections were observed by transmission electron microscopy. The GCIB with relatively low dose could also planarize the 120-nm-pitch carbon tracks without etching the magnetic layer. Index Terms--Carbon overcoat, discrete track magnetic disks, gas cluster ion beam, planarization.

Magnetic multilayered thin films with perpendicular anisotropy have been patterned into nanoscale islands by ion-milling with an oxygen-plasma patterned carbon hard mask. The islands have been studied by scanning electron microscopy (SEM) and magnetic force microscopy (MFM) to determine the switching field distribution and its origin. Larger islands exhibit coercivities of ~ 450 kA/m (5.6 kOe), but coercivity falls rapidly when island diameter falls below 40 nm. The switching field distribution becomes larger in absolute terms and as a fraction of the coercivity as island diameter falls. The origin of these effects is thought to be edge damage during ion milling and intrinsic defects (grain boundaries or dislocations) in the original magnetic thin film. Index Terms--Bit patterned media, magnetic recording magnetic thin films, nanostructures, switching field distributions, temperature.

We report on the effect of in situ focused ion beam (FIB) trimming on the spin configurations of the hexagonal-shaped elements, characterized by scanning electron microscopy with polarization analysis (SEMPA) imaging. The use of SEMPA and successive in situ FIB trimming makes it possible to study the effect of thickness on the spin configuration of a same hexagonal dot array, eliminating the effect of irregularity in edges caused by the fabrication processes. The results obtained indicate that there exists a transition of a single vortex state to a stable double vortex state when the thickness is reduced to below 8 nm. Micromagnetic modeling has been performed to investigate the effect of reductions in both the thickness and saturation magnetization due to FIB trimming. Index Terms--Focused ion beam (FIB), magnetic nanostructures, scanning electron microscopy with polarization analysis (SEMPA), vortex.

To achieve a regular quadratic particle arrangement, gas phase prepared FePt nanoparticles which were annealed in flight in order to obtain the highly anisotropic tetragonal [L1.sub.0] structure are deposited onto the regular 2-D bacterial surface-protein layer (S layer) of Bacillus sphaericus NCTC 9602 which exhibits a four-fold lattice symmetry with a lattice constant of 12.5 nm. The degree of regularity is studied by the statistical evaluation of the particles positions observed by transmission electron microscopy. Although the obtained regularity for the annealed hard magnetic particles is less than for previously studied disordered fcc FePt nanoparticles, a template-directed transfer of both lattice symmetry and periodicity from the 2-D protein crystal to the particle arrangement is observed. In addition, particle agglomeration which has been shown to have a strong effect on the arrangement's regularity, is clearly reduced for the annealed particles because of the mutual magnetic repulsion of adjacent particles. Index Terms--Arrays, biomembranes, FePt, nanoparticles, self organization.

Epitaxial Fe/MgO/Fe magnetic tunnel junctions (MTJs) were grown on MgO(001) substrates by molecular beam epitaxy. The epitaxial structure has been characterized using in-situ reflection high energy diffraction, ex-situ X-ray diffraction, and high-resolution transmission electron microscopy. The magnetic and transport properties have been investigated using vibrating sample magnetometry and physical properties measurement system. The temperature dependence of the TMR ratio, whose value rises from 170% at room temperature to 318% at 10 K, is found to be nonlinear and is fitted using a model based on the effect of magnetic disorder of the electrodes on the spin polarized tunneling. Index Terms--Magnetic disorder, Magnetic Tunnel Junctions (MTJs), Molecular Beam Epitaxy (MBE).

A fast algorithm for the computation of the maximum likelihood three-dimensional (3-D) reconstruction of one or more 3-D objects is presented. Findings reveal a dramatic reduction in computation with the increase in the number of degrees of freedom in the 3-D reconstruction.

Carbon nanofibers (CNFs) have been successfully synthesized by an ac glow-arc discharge in a He--C[H.sub.4] mixture gas with 34% at .Ni/10.32% at .Y as catalyst under high frequency (42 kHz) and low power supply (360 W). This method profits the particle agglomeration in the gap under the influence of high-frequency electrical field. The power density in the plasma region is inferior to 0.1 W/[cm.sup.3] and the processes time duration is lower than 5 min. Results obtained from scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and Raman scattering show that CNF are relatively free of amorphous-carbon coating. Surface and structural analysis indicate that the CNFs have an average diameter of 80 nm. Index Terms--Carbon nanofibers (CNFs), glow-arc discharge, modular plasma reactor, resonant converter.

The enzyme complex oligosaccharyl transferase (OT) catalyzes N-glycosylation in the lumen of the endoplasmic reticulum. The yeast OT complex is composed of nine subunits, all of which are transmembrane proteins. Several lines of evidence, including our previous split-ubiquitin studies, have suggested an oligomeric organization of the OT complex, but the exact oligomeric nature has been unclear. By FLAG epitope tagging the Ost4p subunit of the OT complex, we purified the OT enzyme complex by using the nondenaturing detergent digitonin and a one-step immunoaffinity technique. The digitonin-solubilized OT complex was catalytically active, and all nine subunits were present in the enzyme complex. The purified OT complex had an apparent mass of [approximately equal to] 500 kDa, suggesting a dimeric configuration, which was confirmed by biochemical studies. EM showed homogenous individual particles and revealed a dimeric structure of the OT complexes that was consistent with our biochemical studies. A 3D structure of the dimeric OT complex at 25-[Angstrom] resolution was reconstructed from EM images. We suggest that the dimeric structure of OT might be required for effective association with the translocon dimer and for its allosteric regulation during cotranslational glycosylation. electron microscopy | membrane protein purification | protein N-glycosylation