[en] Elastic measurements on La-based and Y-based bulk oxide superconductive materials in the temperature range 4.2--350 K are reviewed. Emphasis is placed on the elastic behavior near the superconducting transition temperature T_c and at higher temperatures where phase transitions or structural instabilities may occur. Possible mechanisms responsible for the observed elastic anomalies are discussed

[en] In this letter, the radiation-induced interface state generation ΔD_it in MOS devices with reoxidised nitrided gate oxides has been studied. The reoxidised nitrided oxides were fabricated by rapid thermal reoxidation (RTO) of rapidly thermal nitrided (RTN) SiO₂. The devices were irradiated by exposure to X-rays at doses of 0.5-5.0 Mrad (Si). It is found that the RTO process improves the radiation hardness of RTN oxides in terms of interface state generation. The enhanced interface ''hardness'' of reoxidised nitrided oxides is attributed to the strainless interfacial oxide regrowth or reduction of hydrogen concentration during RTO of RTN oxides. (author)

[en] Full text: Effect of rare earth ion Ce³⁺ on the lactate dehydrogenase (LDH) isozyme patterns of six organs of mouse (heart, liver, kidney, muscle, stomach) were investigated by utilizing polyacrylamide gel electrophoresis (PAGE) methods. The results indicated: Ce³⁺ not only can make some LDH bands disappear but also can induce some new bands. Under the action of Ce³⁺ , the shades of some LDH bands were changed and the shade variations were different from organ to organ. In the muscle, it appeared the shade of LDH bands was related to the rare earth concentration in the feed. Rare earth can affect the muscle LDH patterns widely and apparently

[en] Recently, superconductive Nd₁Ba₂Cu₃O_y (Nd123) thin films with high superconducting transition temperature (T_c) have been successfully fabricated at the authors institute employing the standard laser ablation method. In this paper, they report parts of the results of surface characterization of the Nd123 thin films using an ultrahigh vacuum scanning tunneling microscope/spectroscopy (UHV-STM/STS) and an atomic force microscope (AFM) system operated in air. Clear spiral pattern is observed on the surfaces of Nd123 thin films by STM and AFM, suggesting that films are formed by two-dimensional island growth mode at the final growing stage. Contour plots of the spirals show that the step heights of the spirals are not always the integer or half integer numbers of the c-axis parameter of the structure. This implies that the surface natural termination layer of the films may not be unique. Surface atomic images of the as-prepared Nd123 thin films are obtained employing both STM and AFM. STS measurements show that most of the surfaces are semiconductive, or sometimes even metallic. The results of STS measurements together with the fact that they are able to see the surface atomic images using scanning probe microscopes suggest that exposure to air does not cause serious degradation to the as-prepared surfaces of Nd123 thin films

[en] The authors discuss the first measurements of elastic properties performed on a single crystal La_2-xSr_xCuO_4-y high-T_c superconductor recently reported in collaboration with Brookhaven and NTT, Japan. Ultrasonic measurements of longitudinal sound velocity were performed at 13 MHz. The strong anomalies in the elastic properties are ascribed to a tetragonal to orthorhombic phase transition at T₀ ∼ 255 K. Some theoretical discussion is also given

[en] We report on the temperature and field dependences of the resistance of single-crystal Nd_1+xBa_2-xCu₃O_7-δ (NdBCO) in a fields up to 7 T. The dissipation is found to be of the thermal activation type in the presence of defects due to Nd-Ba substitution sites. Transport measurements using the six-terminal configuration together with out-of-plane voltage reveal the vortex velocity correlation along the c-direction. Such a correlation in the vortex state is generally explained as due to the twin planes acting as correlated disorder. The voltage-current behaviour predicts nearly a vortex-glass phase at low temperature. The irreversibility field in J_c was found to be higher in the twinned crystal in comparison with the detwinned one. A small amount of vortex channelling was observed in the angle-dependent magnetization when the field was applied parallel to the c-axis of the crystal. Our magnetic relaxation both in fields and in remnant magnetization shows three distinct regions and a dominant plateau in region II from 30 to 60 K. The existence of this plateau can be explained well using collective pinning theory. The relaxation process is found to be influenced by the shape of the hysteresis loop. The results have been analysed taking into account other relevant theories of the time decay of nonequilibrium magnetization. The magnetic phase diagram from ac susceptibility experiments suggests the validity of the vortex-glass phase transition from the field-temperature scaling. The pinning centres having a size of several nm to several tens of nm are viewed by STM and are primarily responsible for high-field pinning. The pinning ability of Nd-Ba substitution sites is significantly enhanced by the presence of twin boundaries, especially at high field. (author)

[en] Highly flat, clean, and stable surfaces of as-prepared Nd₁Ba₂Cu₃O_y (Nd123) single crystals have been studied using an ultrahigh vacuum scanning tunneling microscope/spectroscopy (UHV-STM/STS) system. The results of large area STM scans together with the results of STS measurements, magnetization loops measured at several temperatures below T_c, and critical current density measurements reveal the presence of a new magnetic flux pinning center in Nd123 single crystals prepared in a reduced oxygen partial pressure. This pinning center is more conductive on the surface than the matrix and has a size ranging from several to several tens of nanometers as seen by STM. Similar pinning center may be introduced to other high temperature superconductors to increase their critical current densities in an applied magnetic field. copyright 1997 American Institute of Physics

[en] A single dose of 8 or 20 Gy ⁶⁰Co γ-rays was given to C3H male mice at 4 months of age. Degenerative changes in the cardiac muscle due to brain irradiation were observed first at 6 months after irradiation, and became progressively more severe at 12-24 months. The changes seen at the ultrastructural level included myofibrillolysis, the presence of lysosomal-like bodies and interstitial fibrosis. (author)

[en] A NIMT optical frequency comb was compare with an Er-fiber laser comb with repetition frequency of 250 MHz made by the Center for Measurement Standards (CMS), Taiwan by simultaneously measuring the frequency of a 633 nm He-Ne laser. The difference of average frequency measurement is 283 Hz and corresponds to a relative difference of 6.0x10^-13. (paper)

[en] The authors report elastic measurements on a single crystal La_2-xSr_xCuO_4-y high-T_c superconductor. Ultrasonic measurements of longitudinal sound velocity and attenuation were performed at 13 MHz. The strong anomalies in the elastic properties are ascribed to a tetragonal to orthorhombic phase transition at T₀ ≅ 255 K