Akiko Watanabe

Characterization of a Non-Superconducting Cuprate, Bi2Sr2YCu2O8.5

A new Bi-containing cuprate, Bi2Sr2YCu2O8.5, was found in the course of substitution study for high Tc compounds Bi2Sr2CaCu2O8+y. Bi2Sr2YCu2O8.5 is a semiconductor and undergoes an antiferromagnetic transition at about 13 K which is considered to originate from the ordering of Cu in the CuO2 planes. An electron diffraction study revealed the existence of a superstructure. The unit cell taking account of the superstructure is 1×8×1 of the original unit cell (5.47×5.43×30.18 A3). Analogy of three kinds of oxide systems, (La1-xSrx)2CuO4, YBa2Cu3O6+x, and Bi2Sr2CaxY1-xCu2O8+y, is discussed.

Structures and Upper Critical Fields of High Tc Superconductors (RE)Ba2Cu3Ox

A systematic study of structure and superconductivity of (RE)Ba2Cu3Ox (RE: rare earch) is carried out. All superconducting (RE)Ba2Cu3Ox have oxygen deficient perovskite structure. As the ion radius of the RE ion increases, lattice parameters increase and the orthorhombic distortion becomes smaller. Superconducting transition temperature is lower for (RE)Ba2Cu3Ox with smaller RE ion radius. Upper critical fields (Hc2) are measured resistively up to 90 kOe. All superconducting (RE)Ba2Cu3Ox have similar values of dHc2/dT|Tc to that of YBa2Cu3Ox. The estimated Hc2 at absolute zero ranges from 1250 kOe to 1850 kOe.

Dissipation in the mixed state of conventional and high temperature superconductors

Abstract A comparative study of the dissipation process in the mixed state of conventional and high temperature superconductors is carried out using thin film samples of YBa 2 Cu 3 O 7− y , Bi 2 Sr 2 CaCu 2 O 8+ y and amorphous MoGe alloy. Amorphous MoGe sho ws a nearly ideal flux flow behavior, in which the difference in the resistivity between H ⊥ J and H ‖ J amounts to many orders of magnitude, as expected from the Lorentz force effect. Dissipation in Bi 2 Sr 2 CaCu 2 O 8+ y is very anomalous in that it is completely independent of the macroscopic Lorentz force. The behavior of YBa 2 Cu 3 O 7− y is intermediate, i.e. a Lorentz-force-effect component, which obeys a sin 2 ω dependence, coexists with the angular-independent dissipation. The origin of the anomalous angular-independent dissipation in the high temperature superconductors is discussed in the light of flux dynamics in highly anisotropic layered superconductors.

Spatial human interface in working environment - spatial-knowledge-tags to access memory of activity

The spatial human interface (SHI) is a relatively new system that enables us to facilitate human activity in a working environment. The SHI stores human activity data as knowledge and activity history of human into the spatial memory in a working environment as three-dimensional space where one acts, and loads them with the spatial-knowledge-tags (SKT) by supporting the enhancement of human activity. To realize this, the SHI purpose is to construct a new relationship among human and distributed networks computers and sensors that is based on intuitive and simultaneous interactions. In this paper, the specified functions of SKT and the realization method of SKT are explained. The experimental results using SKT are shown.

High-Tc superconductivity in (RE)Ba2Cu3Ox-structure, transport and magnetism

Abstract (RE)Ba2Cu3Ox compounds were studied by structural, transport and magnetic measurements. (RE)Ba2Cu3Ox compounds with orthorhombic oxygen deficient perovskite structure are high-Tc superconductors, while those with tetragonal phase are semiconductors. Clear correlation is found between the superconducting transition temperature and the lattice parameters. (RE)Ba2Cu3Ox compounds with smaller lattice parameters have lower Tc except for La. Upper critical fields Hc2 were measured resistively up to 90 kOe. The initial slope |dHc2/dT|Tc have enormous values of about 20 ≈ 29 kOe/K. Magnetic susceptibility measurements revealed that the RE ions are in their trivalent states for both the orthorhombic and the tetragonal phases. Antiferromagnetic orderings of RE ions were found in GdBa2Cu3Ox and DyBa2Cu3Ox at about 2 K and 0.9 K, respectively. Magnetoresistance measurements on tetragonal GdBa2Cu3Ox showed cusp-like anomalies below about 2 K.

Pressure Study and the Critical Current of High-Tc Superconductors YBa2Cu3O7-y and GdBa2Cu3O7-y

The pressure dependences of the superconducting transitions of the title materials have been studied under hydrostatic pressure up to Gpa. The midpoints of the resistive transitions were 92.2 K and 93.2 K for YBa2Cu3O7-y and GdBa2Cu3O7-y, respectively, and increased with increasing pressure at a rate of (5–6)×10-3 GPa-1. The critical current of GdBa2Cu3O7-y was two to three times as large as that of YBa2Cu3O7-y; both were enhanced by the application of pressure.

Ultrasound exposure conditions for suppressing survival of human glioblastoma U-87MG cells

Recently, transcranial magnetic resonance-guided focused ultrasound surgery (tcMRgFUS) for brain tumor has been investigated and applied clinically. However, this therapy may result in an inflammatory reaction caused by necrosis or damage of the normal cells surrounding the targeted tumor cells. Even in the case of treatment with tcMRgFUS, there is a possibility of damaging the surrounding normal cells, which will lead to failure of brain function, in the same manner as the removal of brain tumor cells by surgery, if we overdo the treatment. However, if you do not treat the tumor cells infiltrating the surrounding normal cells, survived tumor cells will proliferate and brain tumor will recur. Therefore, after the treatment of rough parts without the tumor cells infiltrating the surrounding normal cells by tcMRgFUS or surgery, we suggest the use of an additional treatment technique developed by inducing apoptosis to the brain tumor cells infiltrating the surrounding normal cells by irradiation with ultrasound of moderate intensity that does not adversely affect the surrounding normal cells. In this study, we investigated the ultrasound exposure conditions for suppressing survival of human glioblastoma U-87MG cells as an example of brain tumor cells. U-87MG cells cultured in a small cell culture flask were sonicated with a standing wave ultrasound exposure system at a frequency of 150 kHz. To measure the number of viable cells after exposure, a trypan-blue dye exclusion test was performed every 2 h after sonication. The most important observation in this study is the decrease in the survival rate of sonicated U-87MG cells from 4 to 6 h after sonication at a frequency of 150 kHz and at a voltage of over 100 Vp?p applied to a Langevin transducer (tentative peak-rarefactional acoustic pressure of over 120 kPa) for 5 min. In association with this observation, we observed cells stained with trypan blue, which indicates cell death, by using a phase-contrast microscope. However, when the voltage applied to the Langevin transducer is less than 80 Vp?p (tentative peak-rarefactional acoustic pressure is less than 100 kPa), the decreasing tendency of cell survival rate could not observed.

An approach toward unification of architectural design and habitability based on network sensing

Recently, the mass customizations become a common idea for manufacturing products, and people seem like being able to get any products that they want. A house or a building is one of the last products to compromise with fulfilling the individual requirements. This paper describes our approach to realize a next generation living complex being able to align lifestyle changes of residents, or user requirements through lifetime periods of the complex. Establishing a platform structure unaffected by major technological changes is important to give a flexible and an upgradeable feature to a complex. Network sensing is a key idea to obtain information regarding human behaviors with appropriate reliability. Since there is no limitation of user-backgrounds in habitation environments, human interfaces are much more important than any other cases.