Search query: miyasaka and kojima

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abstract: Two organolead halide perovskite nanocrystals, CH(3)NH(3)PbBr(3) and CH(3)NH(3)PbI(3) were found to efficiently sensitize TiO(2) for visible light conversion in photoelectrochemical cells. When self assembled on mesoporous TiO(2) films, the nanocrystalline perovskites exhibit strong band gap absorptions as semiconductors. The CH(3)NH(3)PbI(3) based photocell with spectral sensitivity of up to 800 nm yielded a solar energy conversion efficiency of 3.8% The CH(3)NH(3)PbBr(3) based cell showed a high photovoltage of 0.96 V with an external quantum conversion efficiency of 65%
author_names: Akihiro Kojima

Kenjiro Teshima

Yasuo Shirai

Tsutomu Miyasaka
title: Organometal halide perovskites as visible light sensitizers for photovoltaic cells.
venue: Journal of the American Chemical Society
year: 2009

abstract: Nanocrystalline lead bromide perovskite was synthesized by rapid self organization on a mesoporous aluminum oxide film. With UV excitation, the film exhibited an intense green emission with a narro.
author_names: Akihiro Kojima

Masashi Ikegami

Kenjiro Teshima

Tsutomu Miyasaka
title: Highly Luminescent Lead Bromide Perovskite Nanoparticles Synthesized with Porous Alumina Media
year: 2012

abstract: Abstract Objectives: To elucidate the epidemiological characteristics of patients with rheumatoid arthritis (RA) in Japan using data from the Comprehensive Survey of Living Conditions, a nationwide questionnaire survey conducted in 2016. Methods: In total, 222,365 men and 245,251 women aged =16 years were included in the study. RA patients were defined as those who reported 'currently receiving treatment for RA at hospitals, clinics, or a facility for Japanese traditional massage, acupuncture, moxibustion, or judo orthopedics. The number of RA patients was estimated from the age specific prevalence and total Japanese population in 2016. Further, the prevalence of individuals experiencing difficulties in activities of daily living due to health problems and those with mental distress as evaluated by K6 Scale was examined. Results: The estimated number and prevalence of RA in Japan with 95% confidence interval was 822 (768 880) thousand and 0.75% (0.70 0.80% The population peaked in the late 60s, and the prevalence continued increasing until the early 80s, regardless of sex. Compared with non RA participants, RA patients were more likely to experience difficulties in activities and to be distressed. Conclusion: High prevalence of RA in older age and mental and physical burden among RA patients were confirmed.
author_names: Masayo Kojima

Takeo Nakayama

Kiichiro Tsutani

Ataru Igarashi

Toshihisa Kojima

Sadao Suzuki

Nobuyuki Miyasaka

Hisashi Yamanaka
title: Epidemiological characteristics of rheumatoid arthritis in Japan: Prevalence estimates using a nationwide population based questionnaire survey
venue: Modern rheumatology
year: 2019

abstract: PURPOSE The beam model in radiation treatment planning systems (RTPSs) plays a crucial role in determining the accuracy of calculated dose distributions. The purpose of this study was to ascertain differences in beam models and their dosimetric influences when a golden beam dataset (GBD) and multi institution measured beam datasets (MBDs) are used for beam modeling in RTPSs. METHODS The MBDs collected from 15 institutions, and the MBDs' beam models, were compared with a GBD, and the GBD's beam model, for Varian TrueBeam linear accelerator. The calculated dose distributions of the MBDs' beam models were compared with those of the GBD's beam model for simple geometries in a water phantom. Calculated dose distributions were similarly evaluated in volumetric modulated arc therapy (VMAT) plans for TG 119 C shape and TG 244 head and neck, at several dose constraints of the planning target volumes (PTVs) and organs at risk. RESULTS The agreements of the MBDs with the GBD were almost all within 1% The calculated dose distributions for simple geometries in a water phantom also closely corresponded between the beam models of GBD and MBDs. Nevertheless, there were considerable differences between the beam models. The maximum differences between the mean energy of the energy spectra of GBD and MBDs were 0.12 MeV 10.5% in AcurosXB (AXB, Eclipse) and 0.11 MeV (7.7% in collapsed cone convolution (CCC, RayStation) The differences in the VMAT calculated dose distributions varied for each dose region, plan, X ray energy, and dose calculation algorithm. The ranges of the differences in the dose constraints were 5.6% to 3.0% for AXB and 24.1% to 2.8% for CCC. In several VMAT plans, the calculated dose distributions of GBD's beam model tended to be lower in high dose regions and higher in low dose regions than those of the MBDs' beam models. CONCLUSIONS We found that small differences in beam data have large impacts on the beam models, and on calculated dose distributions in clinical VMAT plan, even if beam data correspond within 1% GBD's beam model was not a representative beam model. The beam models of GBD and MBDs and their calculated dose distributions under clinical conditions were significantly different. These differences are most likely due to the extensive variation in the beam models, reflecting the characteristics of beam data. The energy spectrum and radial energy in the beam model varied in a wide range, even if the differences in the beam data were less than 1% To minimize the uncertainty of the calculated dose distributions in clinical plans, it was best to use the institutional MBD for beam modeling, or the beam model that ensures the accuracy of calculated dose distributions.
author_names: Kensuke Tani

Akihisa Wakita

Naoki Tohyama

Yukio Fujita

Satoshi Kito

Ryo Miyasaka

Norifumi Mizuno

Ryuzo Uehara

Toru Takakura

Shunsuke Miyake

Kazuya Shinoda

Yoshitaka Oka

Yasunori Saito

H Kojima

Naoki Hayashi
title: Evaluation of differences and dosimetric influences of beam models using golden and multi institutional measured beam datasets in radiation treatment planning systems.
venue: Medical physics
year: 2020

abstract: Abstract Objectives To evaluate the efficacy and safety of tacrolimus in adult patients with rheumatoid arthritis (RA) by using the GRADE approach. Methods We searched PubMed, Japana Centra Revuo Medicina Web (Ichu shi web) and the Cochrane Database of Systematic Reviews. Articles fulfilling the predefined inclusion criteria were appraised and used for meta analysis. The primary outcomes were American College of Rheumatology 20 (ACR20) and serum creatinine elevation. Other outcomes included ACR50, ACR70, changes in C reactive protein, modified Health Assessment Questionnaire Disability Index, gastrointestinal disorders, metabolic and nutritional disorders, and infections and infestations. Results We identified five randomized controlled studies, four of which compared tacrolimus to placebo and were included in the meta analysis. The risk ratio of ACR20 achievement was 1.71 (95% confidence interval [CI] 1.20 2.42) for 1 2 mg/day and 2.30 (95% CI 1.79 2.96) for 3 mg/day. The risk ratio of creatinine elevation was 1.95 (95% CI 1.18 3.23) for 1 2 mg/day and 3.81 (95% CI 2.43 5.99) for 3 mg/day. Conclusion Tacrolimus is effective with acceptable safety in the management of RA.
author_names: Yuko Kaneko

Yutaka Kawahito

Masayo Kojima

Takeo Nakayama

Shintaro Hirata

Mitsumasa Kishimoto

Hirahito Endo

Yohei Seto

Hiromu Ito

Keiichiro Nishida

Isao Matsushita

Toshihisa Kojima

Naoyuki Kamatani

Kiichiro Tsutani

Ataru Igarashi

Mieko Hasegawa

Nobuyuki Miyasaka

Hisashi Yamanaka
title: Efficacy and safety of tacrolimus in patients with rheumatoid arthritis A systematic review and meta analysis
venue: Modern rheumatology
year: 2020

abstract: Carrier lifetime in low carrier concentration 4H SiC epitaxial layers grown on the C face was enhanced by using carbon implantation and post annealing. The measured carrier lifetime increased with the thickness of the epitaxial layer and was 11.4 us for the 150 um thick epitaxial layer. The internal carrier lifetime was estimated as 21 us from the dependence of the measured carrier lifetime on the epitaxial layer thickness. This value is almost comparable to the reported values of the internal carrier lifetime for the layers grown on the Si face.
author_names: Mitsuhiro Kushibe

Johji Nishio

Ryosuke Iijima

Akira Miyasaka

Hirokuni Asamizu

Hidenori Kitai

R Kosugi

Shinsuke Harada

Kazutoshi Kojima
title: Carrier Lifetimes in 4H SiC Epitaxial Layers on the C Face Enhanced by Carbon Implantation
year: 2018

abstract: To achieve low on state and switching losses simultaneously in SiC bipolar devices, the depth distribution of the carrier lifetime within the voltage blocking layer and the techniques used for observing the carrier lifetime distribution are important considerations. We developed a measurement system of the time resolved free carrier absorption with intersectional lights (IL TRFCA) for the nondestructive measurements of the depth distribution of the carrier lifetime in 4H SiC thick epilayers. To confirm the reliability of the measurement results, we also performed TRFCA measurements to the cross section of the samples. As a result, although the lifetimes are underestimated owing to an inevitable diffusion of the carriers from the measurement region, the system was able to observe a carrier lifetime distribution up to a depth of 250 mm. Our IL TRFCA system demonstrated a depth resolution of ~10 mm, which is the best resolution among previously reported nondestructive measurement techniques. We consider the proposed system to be useful for the development of SiC bipolar devices.
author_names: Takashi Hirayama

Keisuke Nagaya

Akira Miyasaka

Kazutoshi Kojima

Tomohisa Kato

Hajime Okumura

Masashi Kato
title: Nondestructive measurements of depth distribution of carrier lifetimes in 4H SiC thick epitaxial layers using time resolved free carrier absorption with intersectional lights.
venue: The Review of scientific instruments
year: 2020

abstract: The carrier lifetime is an important parameter for high voltage SiC bipolar devices because its distribution in drift layers affects the device performance. Observation techniques for carrier lifetime, along with the development of carrier lifetime control processes, are important to control carrier lifetime distribution. In this study, we developed a microscopic time resolved free carrier absorption system that has a variable spot size of excitation light and two different probe light wavelengths (405 and 637 nm) By selecting a relatively small spot size of excitation light and the probe light of shorter wavelength (405 nm) the distribution of carrier lifetime was observed with a high spatial resolution of ~3 mm. Additionally, by using a relatively large spot size of excitation light and the probe light that leads to stronger free carrier absorption (637 nm) an accurate measurement of carrier lifetime was obtained. The developed system enables the design and development of bipolar SiC devices with carrier lifetime distribution control.
author_names: Keisuke Nagaya

Takashi Hirayama

Takeshi Tawara

K Murata

Hidekazu Tsuchida

Akira Miyasaka

Hajime Okumura
title: Observation of carrier lifetime distribution in 4H SiC thick epilayers using microscopic time resolved free carrier absorption system
year: 2020

abstract: We fabricated 4H SiC N i P (N intrinsic P) diodes using newly developed low resistivity p type substrates with higher acceptor concentrations than conventional substrate. N i P diodes with 10 mm thick n drift layers were fabricated on both a low resistivity p type substrate and a conventional one to investigate the difference in substrate resistance and bipolar degradation with a heavily doped p type buffer layer. The differential on resistance of N i P diode, using low resistivity p type substrates was decreased to one third compared to the conventional case, and the difference was similar to the p type substrates resistivity. No stacking faults expansion was observed up to 1100 A cm 2. N i P diodes with 233 mm thick n drift layers were fabricated to demonstrate forward characteristics instead of an ultra high voltage n channel IGBTs. The forward characteristics of the N i P diodes with 233 mm thick n drift layers at 200 degC showed low on voltage 6.9 V and low differential on resistance 32.2 mO cm2.
author_names: Akihiro Koyama

Mitsuru Sometani

Kensuke Takenaka

Koji Nakayama

Akira Miyasaka

Kazutoshi Kojima

Kazuma Eto

Tomohisa Kato

Junji Senzaki

Yoshiyuki Yonezawa

Hajime Okumura
title: Low V F 4H SiC N i P diodes using newly developed low resistivity p type substrates
year: 2020

abstract: Purpose Strip meniscometry quantitatively measures the volume of tears in the tear meniscus and has been reported to diagnose dry eyes in clinical settings conveniently, easily, and rapidly. In this study, we used a modified strip meniscometry to assess the applicability of measuring the tear volume in mice in experimental settings. Methods Dry eye was induced in 11 9 week old C57BL/6J wild type male mice (11 right eyes) by exposing them to an air fan inside a small compartment for 5 hours for 2 consecutive days. Tear function tests, including the SMTube for mice (SMTM) for tear volume evaluation, break up time, fluorescein staining score, and lissamine green staining score, were performed. The correlation between SMTM and other tear function parameters was assessed. Results The mean SMTM value was 3.89 0.603 mm before and 3.09 0.625 mm after dry environment exposure (P 0.0078* The Spearman's correlation by rank test showed a strong positive correlation between SMTM and tear film break up time and a strong linear negative correlation with fluorescein and lissamine green values. Conclusions The SMTM was capable of rapidly measuring the minimum tear volume in mice and correlated well with tear function parameters and appears to be a promising new modality in the evaluation of dry eyes in mice.
author_names: Megumi Shinzawa

Murat Dogru

Keiichi Miyasaka

Takashi Kojima

Kazuo Tsubota
title: The Application of Strip Meniscometry to the Evaluation of Tear Volume in Mice.
venue: Investigative ophthalmology visual science
year: 2019