51 research outputs found
Ferroelectric property of an epitaxial lead zirconate titanate thin film deposited by a hydrothermal method
Deposition of thin films via hydrothermal method has various advantages: low deposition temperature, high purity, deposition on a three-dimensional structure,and a large thickness. Although an epitaxial lead zirconate titanate (PZT) thin-film deposition has been reported, the ferroelectric measurement has not been conducted due to the peel-off morphology of the film. The current paper investigates the improvement of an epitaxial PZT thin film deposited via a hydrothermal method. By adjusting the position at which the substrate was suspended in the solution, smooth morphology surface was successfully obtained. As a bottom electrode, a 200-nm SrRuO3 thin film was deposited on SrTiO3 single crystals, and the PZT thin film was deposited on SrRuO3. The remanent polarization 2Pr and coercive electric field for PZT on SrRuO3/SrTiO3 (001) were 17.1 μC/cm2 and 36 kV/cm, respectively, and those of PZT on SrRuO3/SrTiO3 (111) were 32.7 μC/cm2 and 59 kV/cm, respectively. The reason for large imprint electrical field, 91 kV/cm and 40 kV/cm for each film, was unclear at this stage, although it is associated with self-alignment poling direction. This self-alignment poling direction was confirmed via scanning nonlinear dielectric microscopy and is thought to have been related to the deposition mechanism
Anatomic double-bundle anterior cruciate ligament reconstruction, using CT-based navigation and fiducial markers
Accurate placement of separate anteromedial and posterolateral bundle bone tunnels is crucial for anatomic, double-bundle anterior cruciate ligament (ACL) reconstruction. However, identifying the anatomic footprint at which to make the tibial and femoral bone tunnels is not a straightforward procedure. To overcome this problem, we used a CT-based navigation technique with a registration procedure based on fiducial markers (FMs). Preoperatively, 10 FM points were placed on skin around knee joint and scanned with CT. Imaging data of the knee were recorded on the computer system for preoperative registration and surgical planning. Intraoperatively, with a reference frame fixed to the distal medial aspect of femur and tibia, paired-point matching registration was performed with the use of points marked on skin through FM center holes. During tibial tunnel guide wire placement, tibial aiming guide with tracking device fed back the position of tip and direction of the guide wire on the three-dimensional (3D) tibia bone surface image and multiple image planes in real time. For the femoral side, the navigation pointer was placed at the footprint center with visual guidance of 3D image of lateral wall sagittal view on navigation monitor and marked with navigation awl. The average registration accuracy of 22 consecutive patients was 0.7 +/- A 0.2 mm and 0.6 +/- A 0.2 mm for femoral and tibial bone, respectively. Most of the bone tunnel positions evaluated with 3D-CT image were confirmed to be accurately placed in reference to the preoperative plan. There was no damage to femoral condyle cartilage and no other complication. This new CT-based computer navigation system opens the possibility for surgeons to plan bone tunnel positioning preoperatively and control it during technically demanding anatomic double-bundle ACL reconstruction.ArticleKNEE SURGERY SPORTS TRAUMATOLOGY ARTHROSCOPY. 19(3):378-383 (2011)journal articl
Kinematic Structure of Molecular Gas around High-mass Star YSO, Papillon Nebula, in N159 East in the Large Magellanic Cloud
We present the ALMA Band 3 and Band 6 results of 12CO(2-1), 13$CO(2-1),
H30alpha recombination line, free-free emission around 98 GHz, and the dust
thermal emission around 230 GHz toward the N159 East Giant Molecular Cloud
(N159E) in the Large Magellanic Cloud (LMC). LMC is the nearest active
high-mass star forming face-on galaxy at a distance of 50 kpc and is the best
target for studing high-mass star formation. ALMA observations show that N159E
is the complex of filamentary clouds with the width and length of ~1 pc and 5
pc - 10 pc, respectively. The total molecular mass is 0.92 x 10^5 Msun from the
13CO(2-1) intensity. N159E harbors the well-known Papillon Nebula, a compact
high-excitation HII region. We found that a YSO associated with the Papillon
Nebula has the mass of 35 Msun and is located at the intersection of three
filamentary clouds. It indicates that the formation of the high-mass YSO was
induced by the collision of filamentary clouds. Fukui et al. 2015 reported a
similar kinematic structure toward a YSO in the N159 West region which is
another YSO that has the mass larger than 35 Msun in these two regions. This
suggests that the collision of filamentary clouds is a primary mechanism of
high-mass star formation. We found a small molecular hole around the YSO in
Papillon Nebula with sub-pc scale. It is filled by free-free and H30alpha
emission. Temperature of the molecular gas around the hole reaches ~ 80 K. It
indicates that this YSO has just started the distruction of parental molecular
cloud.Comment: 28 pages, 7 figures. Submitted to Ap
High-mass star formation triggered by collision between CO filaments in N159 West in the Large Magellanic Cloud
We have carried out 13CO(J=2-1) observations of the active star-forming
region N159 West in the LMC with ALMA. We have found that the CO distribution
at a sub-pc scale is highly elongated with a small width. These elongated
clouds called "filaments" show straight or curved distributions with a typical
width of 0.5-1.0pc and a length of 5-10pc. All the known infrared YSOs are
located toward the filaments. We have found broad CO wings of two molecular
outflows toward young high-mass stars in N159W-N and N159W-S, whose dynamical
timescale is ~10^4 yrs. This is the first discovery of protostellar outflow in
external galaxies. For N159W-S which is located toward an intersection of two
filaments we set up a hypothesis that the two filaments collided with each
other ~10^5 yrs ago and triggered formation of the high-mass star having ~37
Mo. The colliding clouds show significant enhancement in linewidth in the
intersection, suggesting excitation of turbulence in the shocked interface
layer between them as is consistent with the magneto-hydro-dynamical numerical
simulations (Inoue & Fukui 2013). This turbulence increases the mass accretion
rate to ~6x10^-4 Mo yr^-1, which is required to overcome the stellar feedback
to form the high-mass star.Comment: 20 pages, 3 figures, accepted for publication in ApJ
DECIGO pathfinder
DECIGO pathfinder (DPF) is a milestone satellite mission for DECIGO (DECi-hertz Interferometer Gravitational wave Observatory) which is a future space gravitational wave antenna. DECIGO is expected to provide us fruitful insights into the universe, in particular about dark energy, a formation mechanism of supermassive black holes, and the inflation of the universe. Since DECIGO will be an extremely large mission which will formed by three drag-free spacecraft with 1000m separation, it is significant to gain the technical feasibility of DECIGO before its planned launch in 2024. Thus, we are planning to launch two milestone missions: DPF and pre-DECIGO. The conceptual design and current status of the first milestone mission, DPF, are reviewed in this article
The status of DECIGO
DECIGO (DECi-hertz Interferometer Gravitational wave Observatory) is the planned Japanese space gravitational wave antenna, aiming to detect gravitational waves from astrophysically and cosmologically significant sources mainly between 0.1 Hz and 10 Hz and thus to open a new window for gravitational wave astronomy and for the universe. DECIGO will consists of three drag-free spacecraft arranged in an equilateral triangle with 1000 km arm lengths whose relative displacements are measured by a differential Fabry-Perot interferometer, and four units of triangular Fabry-Perot interferometers are arranged on heliocentric orbit around the sun. DECIGO is vary ambitious mission, we plan to launch DECIGO in era of 2030s after precursor satellite mission, B-DECIGO. B-DECIGO is essentially smaller version of DECIGO: B-DECIGO consists of three spacecraft arranged in an triangle with 100 km arm lengths orbiting 2000 km above the surface of the earth. It is hoped that the launch date will be late 2020s for the present
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