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Diluted effect on the charge ordered (CO) structure in dielectric materials LuFeMO4 (M = Cu, Co) were investigated by an energy-filtered transmission electron microscopy (TEM), in combination with a conventional TEM. It is revealed that partial substitution of Cu2 + and Co2 + for Fe2 +in LuFe2O4 destabilized the CO structure. In LuFeCuO4, there exist characteristic zigzag-shaped diffuse streaks and diffuse spots at the h/3-δ h/3-δ 0-type positions (h: integer, δ = 0.06) in reciprocal space, which originate from static cationic ordering of Fe3 + and Cu2 + ions in the triangular lattice. Moreover, real-space images by the energy-filtered TEM revealed that nanometer-sized domain structures with the 5∼10 nm size are formed. In contrast, honeycomb-shaped diffuse streaks were found in LuFeCoO4, in which no domain structures are observed in real-space images. [ABSTRACT FROM AUTHOR]

The piezoelectric properties of a solid solution, x(Bi1/2Na1/2)TiO3-(1-x)(Bi1/2K1/2) TiO3 + La2O3 y wt% [BNKTx + La2O3 y wt%; x = 0.50, 0.70, y = 0-0.6] were investigated, focusing on piezoelectric constant, d33, and depolarization temperature, Td. The dielectric constant increased with increasing La2O3 content (y). The highest electromechanical coupling factor, k33 (0.493) and the highest d33 (153 pC/N) was obtained in BNKT0.70 + La2O3 0.2wt%. The Td of BNKT0.70 + La2O3 y wt% was almost the same with y = 0-0.3 at 210-220°C and decreased with y ≥ q 0.4. BNKT0.70 + La2O3 0.2 wt% (d33 = 153 pC/N and Td = 219°C) is a good candidate for practical use in actuators. [ABSTRACT FROM AUTHOR]

(Bi1 - xLax)FeO3 with x = 0.00, 0.05, 0.10 and 0.20 were synthesized by the solid-state reaction. The reaction parameters such as calcined temperature was optimized in order to obtain single-phase (Bi1 - xLax)FeO3. The magnetic and ferroelectric transition temperatures were evaluated by thermal analysis. Both magnetic and ferroelectric phase-transition temperature of the (Bi1 - xLax)FeO3 samples shifted to lower temperature than that of the pure BiFeO3 as the lanthanum concentration increased, but the temperature shifts were much smaller than those of previous reports. [ABSTRACT FROM AUTHOR]

Using the atmospheric pressure plasma chemical vapour deposition (CVD) technique, hydrogenated amorphous Si1 - xCx(a-Si1 - xCx : H) films were deposited at extremely high deposition rates. The films were prepared on Si(001) wafers at atmospheric pressure in a very high frequency (150 MHz) plasma of gas mixtures containing He, H2, SiH4 and CH4. Film properties (structure, density and composition of a-Si1 - xCx : H) were studied as functions of CH4 concentration and substrate temperature by transmission electron microscopy, Auger electron spectroscopy and infrared (IR) absorption spectroscopy. The relation between IR absorption spectra and chemical resistance of the films to 15% KOH solution was also investigated. The maximum deposition rate was 50 nm s-1, which was more than ten times faster than that achieved by the conventional plasma CVD technique. It was found that when the CH4 concentration was more than ten times higher than SiH4, the interaction of CH4 with SiH4 was saturated, and carbon-rich a-Si1 - xCx : H films were formed. The density of the a-Si1 - xCx : H films was about 1.5 g cm-3, being less than half of the crystalline value of SiC. The a-Si1 - xCx : H film was not etched by a KOH solution, which was supported by IR analysis of the Si–C stretching vibration mode. [ABSTRACT FROM AUTHOR]

Abstract. For a sub-picosecond pump-and-probe-type radiation chemistry work, a new synchronized electron linac and laser system was installed in Nuclear Engineering Research Laboratory (NERL) of University of Tokyo. The new 0.3 TW laser system with a Ti:Sapphire oscillator (795 nm) and amplifiers generate 300 ps pulses at 10 Hz at first. The laser is splitted into the two beams. The first is compressed to 4 ∼ 11 ps so as to drive the RF-Gun and generate a pump-electron-beam. The second is compressed to 100 fs and used for the probe-light. The drive laser is converted to the third harmonics (265 nm, < 250 μJ). Moreover, a new 15 MW klystron was installed for the linac RF system. The RF power is divided to the gun and the accelerating section. Finally the time jitter between the pump-electron-beam and the probe-laser is designed to be 320 fs (rms). By using the new drive laser system, the charge of 7 nC per bunch was observed at the exit of the gun. Improvement of the vacuum in the gun (< 10[sup-9] Torr) is most effective to obtain such a high charge beam. After two and a half years operation of the gun, no degradation of QE has been found for the Cu photo-cathode. [ABSTRACT FROM AUTHOR]

Abstract. Measurements of longitudinal bunch length of picosecond electron bunches have been performed by the femtosecond streak camera, the interferometer and the polychromator and their results were compared with one another. As regards the radiation, transition radiation and diffraction radiation were investigated through the diagnostics. As a result, the fine agreements between them within 200 fs were obtained and the reliability of the interferometer and the polychromator for the diagnostics of less than picosecond electron bunch were verified. Furthermore, nondestructive diagnostics for subpicosecond bunches was performed utilizing coherent diffraction radiation (CDR) interferometry. [ABSTRACT FROM AUTHOR]

Abstract. The generation of an ultrashort relativistic electron bunch from a strong laser-plasma interaction have been studied by particle-in-cell simulations and observed experimentally. The electron beam was generated from the plasma created by focusing 12 TW (tera watt) laser pulse at the edge of helium gas jet expanded into the vacuum from a pulsed supersonic nozzle. The laser pulse duration was 50 fs (femtosecond). In the interaction of 50 fs, 12 TW laser pulse with plasma of density of 5 x 10[sup19]cm[sup-3], the electron generation was observed in the simulation at the very beginning of the interaction region. The plasma electrons were gaining higher energies by the huge longitudinal electric fields (created by the laser pulse) as they move through the rest of the plasma following the laser pulse. In the experiment, the electron beam transverse profile and its total charge have been measured in the forward direction (the same direction of the laser pulse) by using imaging plate and Faraday-cup, respectively. [ABSTRACT FROM AUTHOR]

Background: The effect of aging on the components of the cardiothoracic ratio (CTR) in the chest roentgenogram in women remains obscure. There have been only a few reported studies that have investigated longitudinal changes of the CTR in women.Objective: To determine whether there is an effect of aging on the CTR in women.Methods: The study population consisted of 110 women who attended an annual health screening and underwent chest roentgenography both in 1981 and 1990 in a mountain village in Japan. We used the data obtained from an annual health screening in order to determine thoracic diameter (TD), cardiac diameter (CD), and lung height (LH) and then calculated the CTR. We analyzed CTR, TD, CD, and LH on the basis of the age of the participants.Results: In the cross-sectional analysis of the groups stratified by age in 1981, mean CD and CTR increased, and TD decreased in the advanced-age group. The percentage of radiographic cardiomegaly (CTR >50%) strikingly increased in the advanced-age group. In the longitudinal analysis between 1981 and 1990, the mean CD increased, and the mean TD decreased significantly. The mean CTR increased by 2.0% (95% CI 1. 2-2.8%). The changes of the CTR in 9 years were positively correlated with those of CD and negatively correlated with those of TD and LH. The longitudinal data generally accorded with the cross-sectional data, except LH.Conclusions: The CTR in women increases with aging as a result of the increase in CD, except in the case of advanced old age, and the decrease in TD. LH could be another major factor that has an influence on CTR. Caution should be exercised to avoid overestimating CTR when LH changes. The classical upper limit of 50% for CTR in our adopted method should not be applied to elderly women because of the possibility that changes with normal aging are misclassified as abnormal findings. [ABSTRACT FROM AUTHOR]

Magnetization measurements for Ln0.5Sr0.5CoO3 (Ln=Pr, Nd, Sm and Eu and Gd) show ferromagnetic transitions with Curie temperatures (TC) between 233 and 130 K, accompanied by spin-glass-like behavior. These compounds are metallic below TC, which is an entirely different property from that of the corresponding Ba-systems Ln0.5Ba0.5CoO3. Only Gd0.5Sr0.5CoO3 shows obvious insulating behavior below ∼80 K. [Copyright &y& Elsevier]