[en] A smoke detector is disclosed which comprises an inner electrode, an intermediate electrode with a hole for passing radioactive rays therethrough, an outer electrode having openings for allowing smoke to flow therethrough, and one radioactive source, the inner and intermediate electrodes forming an inner ionization chamber, the intermediate and outer electrodes forming an outer ionization chamber, the radioactive source being disposed in the inner ionization chamber. A proper quantity of radioactive rays from the radioactive source is applied into the outer ionization chamber through the hole provided in the intermediate electrode

[en] A single crystal of Pr_0.5Sr_0.5MnO₃, which exhibits a collossal magnetoresistance phenomenon in its A-type antiferromagnetic state, was investigated by a neutron diffraction study. This material exhibits a stripe-type charge ordering with a wave vector q∼(0,0,0.3), which controls the electron conductivity. This charge ordering is fundamentally different from a widely observed checkerboard (CE-type) charge ordering, and is specific to the conductive A-type AFM state

[en] Long-lived radioactive nuclides contained in high-level waste (HLW) pose the difficulty in disposing of HLW. Partitioning and transmutation (P/T) is considered to be effective in easing conditions of the disposal. In this study, a model simulating the whole nuclear cycle including P/T processes was structured. Effects of introducing P/T on the amount of radioactive nuclides, total volume of radioactive nuclides, and total volume of radioactive wastes were evaluated. (author)

[en] A bellows is installed at the outer side of the secondary sodium entrance nozzle of MONJU IHX as the absorber for the difference of thermal expansion between the pressure equipment and the piping. A research and development program on IHX bellows was performed in the field of experiment and analysis for establishing the feasibility of IHX bellows under high temperature conditions. This report consists of three sections, namely design profile, experimental tests and analysis of IHX bellows. In the design profile a calculation of temperature distribution of bellows and stress analysis using a half convolution model are included. Basic tests such as non-destructive tests on the raw metal sheet and selection tests of welding conditions were performed. Some results of these basic tests, fatigue tests and sodium exposure tests are described in the research and development section of this report. Furthermore, analytical calculations led the correlations on a maximum stress between axial and some other loads. (author)

[en] The impurity (Cr³⁺)-doping effect on the stability of charge and orbital ordering has been systematically investigated for Nd_1/2Ca_1/2Mn_1-yCr_yO₃ crystals by measurements of magnetotransport and x-ray diffraction. The random field in terms of e_g orbital deficiencies on the Cr sites drives the charge and orbital correlations to dynamical and short range, which is most relevant to the high-resistive state exhibiting colossal magnetoresistance. In the Cr-doped manganite, we can observe the coexistence of ferromagnetic - metallic and charge - orbital ordered phases, their spatial distributions, diffuse x-ray scattering, magnetic-field annealing, and the aging effect on the magnetic and electric properties, etc. These phenomena are reminiscent of those of relaxor ferroelectrics composed of ferroelectric clusters embedded in a paraelectric matrix. We propose that the mixed-valent manganite can be viewed as a 'magneto- and electrorelaxor.' [copyright] 2001 American Institute of Physics

[en] Raman scattering has been investigated for a single crystal of Sm_1-xSr_xMnO₃ (x=0.45), which shows prototypical colossal magnetoresistance (CMR), and related crystals. The emergence of broad phonon bands indicates dynamical charge/orbital correlation above the Curie temperature. Such a feature is systematically enhanced with a decrease of one-electron band width toward the orbital order-disorder phase boundary, being concomitant with the enhancement of CMR. The charge/orbital correlation affected by charge/orbital ordering instability is likely to be responsible for the steep insulator-metal transition and CMR

[en] Inelastic neutron scattering was used to study the temperature (T) dependence of the lattice excitations in La_0.7Ca _0.3MnO ₃ . An optical Jahn-Teller phonon exhibits continuous but anomalous damping with increasing temperature in the ferromagnetic-metallic phase and collapses above the Curie temperature T_C (240K). We attribute this anomaly to the growing dynamic phase segregation as T→T_C , thus providing evidence of local fluctuations associated with the short-range polaron or charge/orbital ordering in the ferromagnetic-metallic state

[en] Electronic properties including magnetoresistance have been investigated for polycrystals of ordered double perovskite alloy, Sr₂Fe(W_1-xMo_x)O₆. In this system, the ground state changes from an antiferromagnetic insulator to a ferromagnetic metal with increasing x. The magnetization in Sr₂Fe(W_1-xMo_x)O₆ develops by the minimal substitution of W by Mo, and then the conductivity as well as the density of states at the Fermi level grows rapidly with x above 0.25. The present alloy also shows a variety of magnetoresistance behaviors. For example, Sr₂Fe(W_0.4Mo_0.6)O₆ (x=0.6) exhibits a magnetoresistance (MR) at 4.2 and 300 K as large as 69 and 10%, respectively. Furthermore, Sr₂Fe(W_0.85Mo_0.15)O₆ (x=0.15), located near the insulator-metal phase boundary, shows an extremely large magnetoresistance as large as 195% at 16 K. The low-field MR can be ascribed to a field suppression of the spin-dependent scattering at the grain or domain boundaries

[en] Spin wave excitations were measured in the ferromagnetic phase of Nd_1/2Sr_1/2MnO₃ by neutron scattering. This compound is located in proximity to the A-type antiferromagnetic state, and it shows a clear anisotropy and anomalous softening of the spin wave excitations. The softening in the ferromagnetic phase is induced by the orbital ordering

[en] The mechanical strength of bones lies in their trabecular architecture. The direction, thickness and number of internal trabeculae are determined by the mechanical stress exerted on them [1]. Changes in the trabeculae due to growth , use and aging were observed using soft radiograms of the distal part of the third metacarpus (Mc III) of newborn to adult horses