16 results on '"Yasuhiro Yamada"'
Search Results
2. Comparison of toxicities between ultrahypofractionated radiotherapy versus brachytherapy with or without external beam radiotherapy for clinically localized prostate cancer
- Author
-
Hideya Yamazaki, Koji Masui, Gen Suzuki, Norihiro Aibe, Daisuke Shimizu, Takuya Kimoto, Kei Yamada, Akihisa Ueno, Toru Matsugasumi, Yasuhiro Yamada, Takumi Shiraishi, Atsuko Fujihara, Ken Yoshida, and Satoaki Nakamura
- Subjects
Medicine ,Science - Abstract
Abstract To compare gastrointestinal (GI) and genitourinary (GU) toxicities in patients with localized prostate cancer treated with ultrahypofractionated radiotherapy (UHF) or brachytherapy [BT; low dose rate, LDR or high dose rate (HDR) with or without external beam radiotherapy (EBRT)]. We compared 253 UHF and 1664 BT ± EBRT groups. The main outcomes were the incidence and severity of acute and late GU and GI toxicities. The secondary endpoint was biochemical control rate. Cumulative late actuarial GU toxicity did not differ for grade ≥ 2 (8.6% at 5-years in UHF and 13.3% in BT ± EBRT, hazard ratio [HR], 0.7066; 95% CI, 0.4093–1.22, p = 0.2127). Actuarial grade ≥ 2 late GI toxicity was higher in UHF (5.8% at 5-years, HR: 3.619; 95% CI, 1.774–7.383, p
- Published
- 2022
- Full Text
- View/download PDF
3. Décollement geometry controls on shallow very low frequency earthquakes
- Author
-
Yoshitaka Hashimoto, Shigeyuki Sato, Gaku Kimura, Masataka Kinoshita, Ayumu Miyakawa, Gregory F. Moore, Masaru Nakano, Kazuya Shiraishi, and Yasuhiro Yamada
- Subjects
Medicine ,Science - Abstract
Abstract Recent studies have documented the occurrence of shallow very low frequency earthquakes (VLFE) in subduction zones. The heterogeneity of the materials or stresses that act on the plate interface results in the variable slip rate. Stress on the décollement can be controlled by the décollement geometry and the regional stress, which is also able to control the material properties. We determined the distribution of stress along the shallow portion of the décollement in the Nankai Trough using a three-dimensional (3D) seismic survey and regional stress analysis to construct maps of normalized slip tendency (T s ′) and dilation tendency (T d ). Alignments of VLFEs trend parallel to the trends of $${T}_{s}^{^{\prime}}$$ T s ′ and $${T}_{d}$$ T d . On the other hand, very low $${T}_{s}^{^{\prime}}$$ T s ′ and $${T}_{d}$$ T d areas probably act as barriers that limit the number of VLFEs that can migrate towards the trench. Because the $${T}_{s}^{^{\prime}}$$ T s ′ and $${T}_{d}$$ T d distributions are derived only from the décollement geometry and the regional stress without incorporating any data on sediment properties, the consistency between the trends suggests that the décollement geometry is the primary control on VLFE activity.
- Published
- 2022
- Full Text
- View/download PDF
4. Abiraterone acetate versus bicalutamide in combination with gonadotropin releasing hormone antagonist therapy for high risk metastatic hormone sensitive prostate cancer
- Author
-
Takashi Ueda, Takumi Shiraishi, Saya Ito, Munehiro Ohashi, Toru Matsugasumi, Yasuhiro Yamada, Atsuko Fujihara, Fumiya Hongo, Koji Okihara, and Osamu Ukimura
- Subjects
Medicine ,Science - Abstract
Abstract The objective of this study was to compare the efficacy of abiraterone acetate with that of bicalutamide in combination with gonadotropin-releasing hormone (GnRH) antagonist treatment for patients with high-risk metastatic hormone-sensitive prostate cancer (mHSPC). A total of 149 patients with mHSPC who underwent treatment at our hospital and affiliated hospitals between December 2013 and July 2020 were retrospectively identified. Fifty patients were administered abiraterone acetate (1000 mg/day) plus prednisolone (5 mg/day) with a GnRH antagonist (degarelix) (group A), and 99 patients were administered bicalutamide (80 mg/day) with a GnRH antagonist (group B). The prostate-specific antigen (PSA) progression-free survival (PSA-PFS) was significantly longer in group A than in group B. Abiraterone acetate therapy and Gleason score were significant independent factors of PSA-PFS. Using propensity score matching, 56 matched patients were obtained. The PSA-PFS (p
- Published
- 2021
- Full Text
- View/download PDF
5. Subseafloor sulphide deposit formed by pumice replacement mineralisation
- Author
-
Tatsuo Nozaki, Toshiro Nagase, Yutaro Takaya, Toru Yamasaki, Tsubasa Otake, Kotaro Yonezu, Kei Ikehata, Shuhei Totsuka, Kazuya Kitada, Yoshinori Sanada, Yasuhiro Yamada, Jun-ichiro Ishibashi, Hidenori Kumagai, Lena Maeda, and the D/V Chikyu Expedition 909 Scientists
- Subjects
Medicine ,Science - Abstract
Abstract Seafloor massive sulphide (SMS) deposits, modern analogues of volcanogenic massive sulphide (VMS) deposits on land, represent future resources of base and precious metals. Studies of VMS deposits have proposed two emplacement mechanisms for SMS deposits: exhalative deposition on the seafloor and mineral and void space replacement beneath the seafloor. The details of the latter mechanism are poorly characterised in detail, despite its potentially significant role in global metal cycling throughout Earth’s history, because in-situ studies require costly drilling campaigns to sample SMS deposits. Here, we interpret petrographic, geochemical and geophysical data from drill holes in a modern SMS deposit and demonstrate that it formed via subseafloor replacement of pumice. Samples from the sulphide body and overlying sediment at the Hakurei Site, Izena Hole, middle Okinawa Trough indicate that sulphides initially formed as aggregates of framboidal pyrite and matured into colloform and euhedral pyrite, which were replaced by chalcopyrite, sphalerite and galena. The initial framboidal pyrite is closely associated with altered material derived from pumice, and alternating layers of pumiceous and hemipelagic sediments functioned as a factory of sulphide mineralisation. We infer that anhydrite-rich layers within the hemipelagic sediment forced hydrothermal fluids to flow laterally, controlling precipitation of a sulphide body extending hundreds of meters.
- Published
- 2021
- Full Text
- View/download PDF
6. High-dose-rate brachytherapy with external beam radiotherapy versus low-dose-rate brachytherapy with or without external beam radiotherapy for clinically localized prostate cancer
- Author
-
Hideya Yamazaki, Koji Masui, Gen Suzuki, Norihiro Aibe, Daisuke Shimizu, Takuya Kimoto, Kei Yamada, Akihisa Ueno, Toru Matsugasumi, Yasuhiro Yamada, Takumi Shiraishi, Atsuko Fujihara, Koji Okihara, Ken Yoshida, and Satoaki Nakamura
- Subjects
Medicine ,Science - Abstract
Abstract To compare the outcomes of localized prostate cancer treatment with high-dose-rate brachytherapy (HDR-BT) and low-dose-rate brachytherapy (LDR-BT), we examined 924 patients treated with HDR-BT + external beam radiotherapy (EBRT) and 500 patients treated with LDR-BT ± EBRT using multi-institutional retrospective data. The HDR-BT treated advanced disease with more hormonal therapy than LDR-BT. To reduce background selection bias, we performed inverse probability of treatment weighting (IPTW) analysis using propensity scores and excluded patients with T3b-4 disease/ initial prostate-specific antigen (PSA) levels > 50 ng/ml. The actuarial 5-year biochemical control rates (5y-bNED) were 96.3% and 95.7% in the HDR-BT and LDR-BT groups, respectively. The corresponding values were 100% and 96.5% in the low-risk group; 97.4% and 97.1% in the intermediate-risk group (97.2% and 97% in the higher titer group and 97.5% and 94.6% in the lower titer group, respectively); and 95.7% and 94.9% in the selected high-risk group, respectively. IPTW correction indicated no significant difference among the groups. The 5y-bNED in the HDR-BT + EBRT, LDR-BT + EBRT, and LDR-BT alone groups were 96.3%, 95.5%, and 97%, respectively (P = 0.3011). The corresponding values were 97.4%, 94.7%, and 96.6% (P = 0.1004) in the intermediate-risk group (97.5%, 100%, and 94.5% in the lower titer group [P = 0.122] and 97.2%, 96.2%, and 100% [P = 0.664] in the higher titer group, respectively) and 95.7%, 95.5%, and 100% (P = 0.859) in the high-risk group, respectively. The HDR-BT group showed a lower incidence of acute grade ≥ 2 genitourinary toxicities; the incidence of other early and late grade ≥ 2 toxicities were similar between the HDR-BT and LDR-BT groups. Acute genitourinary toxicity predicted the occurrence of late genitourinary toxicity. EBRT increased the risk of grade ≥ 2 gastrointestinal toxicity. HDR-BT + EBRT is a good alternative to LDR-BT ± EBRT for low-, intermediate-, and selected high-risk patients.
- Published
- 2021
- Full Text
- View/download PDF
7. High-dose-rate brachytherapy with external beam radiotherapy versus low-dose-rate brachytherapy with or without external beam radiotherapy for clinically localized prostate cancer
- Author
-
Kei Yamada, Toru Matsugasumi, Gen Suzuki, Takumi Shiraishi, Satoaki Nakamura, Koji Okihara, Daisuke Shimizu, Norihiro Aibe, Ken Yoshida, Koji Masui, Akihisa Ueno, Hideya Yamazaki, Takuya Kimoto, Yasuhiro Yamada, and Atsuko Fujihara
- Subjects
Male ,medicine.medical_specialty ,Science ,medicine.medical_treatment ,Urology ,Brachytherapy ,Article ,030218 nuclear medicine & medical imaging ,03 medical and health sciences ,Prostate cancer ,0302 clinical medicine ,parasitic diseases ,medicine ,Humans ,External beam radiotherapy ,Aged ,Retrospective Studies ,Aged, 80 and over ,Multidisciplinary ,Genitourinary system ,business.industry ,Prostatic Neoplasms ,Radiotherapy Dosage ,Middle Aged ,medicine.disease ,High-Dose Rate Brachytherapy ,Low-Dose Rate Brachytherapy ,Radiation therapy ,Titer ,Oncology ,030220 oncology & carcinogenesis ,Medicine ,business - Abstract
To compare the outcomes of localized prostate cancer treatment with high-dose-rate brachytherapy (HDR-BT) and low-dose-rate brachytherapy (LDR-BT), we examined 924 patients treated with HDR-BT + external beam radiotherapy (EBRT) and 500 patients treated with LDR-BT ± EBRT using multi-institutional retrospective data. The HDR-BT treated advanced disease with more hormonal therapy than LDR-BT. To reduce background selection bias, we performed inverse probability of treatment weighting (IPTW) analysis using propensity scores and excluded patients with T3b-4 disease/ initial prostate-specific antigen (PSA) levels > 50 ng/ml. The actuarial 5-year biochemical control rates (5y-bNED) were 96.3% and 95.7% in the HDR-BT and LDR-BT groups, respectively. The corresponding values were 100% and 96.5% in the low-risk group; 97.4% and 97.1% in the intermediate-risk group (97.2% and 97% in the higher titer group and 97.5% and 94.6% in the lower titer group, respectively); and 95.7% and 94.9% in the selected high-risk group, respectively. IPTW correction indicated no significant difference among the groups. The 5y-bNED in the HDR-BT + EBRT, LDR-BT + EBRT, and LDR-BT alone groups were 96.3%, 95.5%, and 97%, respectively (P = 0.3011). The corresponding values were 97.4%, 94.7%, and 96.6% (P = 0.1004) in the intermediate-risk group (97.5%, 100%, and 94.5% in the lower titer group [P = 0.122] and 97.2%, 96.2%, and 100% [P = 0.664] in the higher titer group, respectively) and 95.7%, 95.5%, and 100% (P = 0.859) in the high-risk group, respectively. The HDR-BT group showed a lower incidence of acute grade ≥ 2 genitourinary toxicities; the incidence of other early and late grade ≥ 2 toxicities were similar between the HDR-BT and LDR-BT groups. Acute genitourinary toxicity predicted the occurrence of late genitourinary toxicity. EBRT increased the risk of grade ≥ 2 gastrointestinal toxicity. HDR-BT + EBRT is a good alternative to LDR-BT ± EBRT for low-, intermediate-, and selected high-risk patients.
- Published
- 2021
8. Usefulness of a novel device to divide core needle biopsy specimens in a spatially matched fashion
- Author
-
Akihisa Ueno, Keisuke Tsuji, Takashi Ueda, Takumi Shiraishi, Yumiko Saito, Osamu Ukimura, Hidefumi Taniguchi, Yasuhiro Yamada, Takeshi Yamada, Masatomo Kaneko, Yuta Inoue, Fumiya Hongo, Atsuko Fujihara, Saya Ueda, Tsuyoshi Iwata, Toru Matsugasumi, Hideto Taga, and Shogo Inui
- Subjects
Core needle ,Pathology ,medicine.medical_specialty ,lcsh:Medicine ,Diseases ,Mice, SCID ,Real-Time Polymerase Chain Reaction ,Article ,Specimen Handling ,Mice ,Mouse xenograft ,Cell Line, Tumor ,Biopsy ,medicine ,Animals ,Humans ,New device ,Genetic Testing ,lcsh:Science ,Experimental surgery ,Tumor xenograft ,Cancer ,Multidisciplinary ,medicine.diagnostic_test ,business.industry ,Biopsy, Needle ,lcsh:R ,Neoplasms, Experimental ,Needle biopsy ,Feasibility Studies ,lcsh:Q ,business ,Biomedical engineering ,Neoplasm Transplantation - Abstract
We developed a novel dividing device that can split needle biopsy tissues along longitude axis aiming to achieve definitive molecular-biological and genetical analysis with reference of pathological diagnosis of the side-by-side divided tissue as spatially matched information. The aim of this study was to evaluate the feasibility and potential usefulness of the novel dividing device to provide the appropriate materials for molecular diagnosis. The new device was examined using mouse xenograft tumors. Real-time quantitative PCR and genetic test were performed to evaluate the feasibility and usefulness of the device. All the samples from needle biopsy were successfully divided into two pieces. Quality and quantity from divided samples harbor high enough to perform gene expression analysis (real-time PCR) and genetic test. Using two divided samples obtained from xenograft tumor model by needle biopsy, the % length of xenograft tumor (human origin) was significantly correlated with the % human genomic DNA (p = 0.00000608, r = 0.987), indicating that these divided samples were spatially matched. The novel longitudinally dividing device of a needle biopsy tissue was useful to provide the appropriate materials for molecular-biological and genetical analysis with reference of pathological diagnosis as spatially matched information.
- Published
- 2020
- Full Text
- View/download PDF
9. Induced pluripotent stem cell-derived tenocyte-like cells promote the regeneration of injured tendons in mice
- Author
-
Haruhiko Akiyama, Hirofumi Shibata, Atsushi Goto, Hitomi Aoki, Kenji Ito, Shingo Komura, Yasuhiro Yamada, Takashi Satake, and Akihiro Hirakawa
- Subjects
Transgene ,Induced Pluripotent Stem Cells ,lcsh:Medicine ,Mice, Transgenic ,Biology ,Article ,Tendons ,Mice ,Paracrine signalling ,Pluripotent stem cells ,Tendon Injuries ,medicine ,Regeneration ,Animals ,lcsh:Science ,Induced pluripotent stem cell ,Multidisciplinary ,Regeneration (biology) ,lcsh:R ,Scleraxis ,musculoskeletal system ,Antigens, Differentiation ,Tendon ,Tenomodulin ,Cell biology ,Tenocytes ,Transplantation ,medicine.anatomical_structure ,Gene Expression Regulation ,lcsh:Q - Abstract
Tendons are dense fibrous structures that attach muscles to bones. Healing of tendon injuries is a clinical challenge owing to poor regenerative potential and scarring. Here, we created reporter mice that express EGFP, driven by the promoter of the tendon-specific Scleraxis (Scx) transcription-factor gene; we then generated induced pluripotent stem cells (iPSCs) from these mice. Utilising these fluorescently labelled iPSCs, we developed a tenogenic differentiation protocol. The iPSC-derived EGFP-positive cells exhibited elevated expression of tendon-specific genes, including Scx, Mohawk, Tenomodulin, and Fibromodulin, indicating that they have tenocyte-like properties. Finally, we demonstrated that these cells promoted tendon regeneration in mice after transplantation into injured tendons reducing scar formation via paracrine effect. Our data demonstrate that the tenogenic differentiation protocol successfully provided functional cells from iPSCs. We propose that pluripotent stem cell-based therapy using this protocol will provide an effective therapeutic approach for tendon injuries.
- Published
- 2020
- Full Text
- View/download PDF
10. Continuous depth profile of the rock strength in the Nankai accretionary prism based on drilling performance parameters
- Author
-
Takamitsu Sugihara, Kyaw Moe, M. Kitamura, Yohei Hamada, Yoshinori Sanada, Takehiro Hirose, Saneatsu Saito, and Yasuhiro Yamada
- Subjects
Multidisciplinary ,Accretionary wedge ,010504 meteorology & atmospheric sciences ,lcsh:R ,Drilling ,lcsh:Medicine ,010502 geochemistry & geophysics ,Mbsf ,01 natural sciences ,Prism (geology) ,Drill string ,Article ,Tectonics ,lcsh:Q ,Compression (geology) ,Petrology ,lcsh:Science ,Forearc ,Geology ,0105 earth and related environmental sciences - Abstract
A new method for evaluating the in situ rock strength beneath the seafloor is proposed and applied to the Nankai Trough accretionary prism. The depth-continuous in situ rock strength is a critical parameter for numerous studies in earth science, particularly for seismology and tectonics at plate convergence zones; yet, measurements are limited owing to a lack of drilled cores. Here, we propose a new indicator of strength, the equivalent strength (EST), which is determined only by drilling performance parameters such as drill string rotational torque, bit depth, and string rotational speed. A continuous depth profile of EST was drawn from 0 to 3000 m below the seafloor (mbsf) across the forearc basin and accretionary prism in the Nankai Trough. The EST did not show a significant increase around the forearc basin–accretionary prism boundary, but it did show a clear increase within the prism, ca. below 1500 mbsf. This result may indicate that even the shallow accretionary prism has been strengthened by horizontal compression derived from plate subduction. The EST is a potential parameter to continuously evaluate the in situ rock strength during drilling, and its accuracy of the absolute value can be improved by combining with laboratory drilling experiments.
- Published
- 2018
- Full Text
- View/download PDF
11. A mathematical model to estimate the seasonal change in apparent longevity of bee colony
- Author
-
Kazuko Yamada, Yasuhiro Yamada, and Toshiro Yamada
- Subjects
0301 basic medicine ,media_common.quotation_subject ,Longevity ,Zoology ,lcsh:Medicine ,Field tests ,Insect ,Biology ,Article ,03 medical and health sciences ,Honey Bees ,0302 clinical medicine ,Animals ,lcsh:Science ,Overwintering ,media_common ,Multidisciplinary ,lcsh:R ,Bees ,Models, Theoretical ,Brood ,030104 developmental biology ,lcsh:Q ,Seasons ,030217 neurology & neurosurgery - Abstract
The longevity of a honeybee colony is far more significant than the lifespan of an individual honeybee, a social insect. The longevity of a honeybee colony is integral to the fate of the colony. We have proposed a new mathematical model to estimate the apparent longevity defined in the upper limit of an integral equation. The apparent longevity can be determined only from the numbers of adult bees and capped brood. By applying the mathematical model to a honeybee colony in Japan, seasonal changes in apparent longevity were estimated in three long-term field experiments. Three apparent longevities showed very similar season-changes to one another, increasing from early autumn, reaching a maximum at the end of overwintering and falling approximately plumb down after overwintering. The influence of measurement errors in the numbers of adult bees and capped brood on the apparent longevity was investigated.
- Published
- 2019
12. Identification of MMP1 as a novel risk factor for intracranial aneurysms in ADPKD using iPSC models
- Author
-
Kenji Osafune, Yasunori Sato, Fumiyo Kitaoka, Sumiko Inoue, Kazuwa Nakao, Yasuhiro Yamada, Hatasu Kobayashi, Satoshi Matsui, Taro Toyoda, Takuya Yamamoto, Norio Matsuura, Masakatsu Sone, Akira Watanabe, Shin Ichi Mae, Toshikazu Araoka, Tatsutoshi Nakahata, Kazutoshi Takahashi, Eri Muso, Naoki Amano, Akio Koizumi, Shinya Yamanaka, Tetsuhiko Yasuno, Atsushi Fukatsu, Tomohiro Numata, Yasuo Mori, Naoya Kondo, Sayaka Arai, Yoshifumi Ubara, Daisuke Taura, Tomonaga Ameku, Isao Asaka, Fumihiko Shiota, Tomoko Ichisaka, and Masahiro Nakamura
- Subjects
0301 basic medicine ,Male ,Pathology ,medicine.medical_specialty ,Subarachnoid hemorrhage ,TRPP Cation Channels ,MMP1 ,Induced Pluripotent Stem Cells ,030232 urology & nephrology ,Autosomal dominant polycystic kidney disease ,Disease ,Mice, SCID ,urologic and male genital diseases ,Article ,03 medical and health sciences ,Mice ,0302 clinical medicine ,Aneurysm ,Mice, Inbred NOD ,Risk Factors ,medicine ,Animals ,Humans ,Risk factor ,Induced pluripotent stem cell ,Cells, Cultured ,Cause of death ,Aged ,Multidisciplinary ,business.industry ,urogenital system ,Cell Differentiation ,Intracranial Aneurysm ,DNA Methylation ,Middle Aged ,Subarachnoid Hemorrhage ,medicine.disease ,Polycystic Kidney, Autosomal Dominant ,female genital diseases and pregnancy complications ,030104 developmental biology ,Female ,Matrix Metalloproteinase 1 ,business ,Biomarkers - Abstract
Cardiovascular complications are the leading cause of death in autosomal dominant polycystic kidney disease (ADPKD), and intracranial aneurysm (ICA) causing subarachnoid hemorrhage is among the most serious complications. The diagnostic and therapeutic strategies for ICAs in ADPKD have not been fully established. We here generated induced pluripotent stem cells (iPSCs) from seven ADPKD patients, including four with ICAs. The vascular cells differentiated from ADPKD-iPSCs showed altered Ca2+ entry and gene expression profiles compared with those of iPSCs from non-ADPKD subjects. We found that the expression level of a metalloenzyme gene, matrix metalloproteinase (MMP) 1, was specifically elevated in iPSC-derived endothelia from ADPKD patients with ICAs. Furthermore, we confirmed the correlation between the serum MMP1 levels and the development of ICAs in 354 ADPKD patients, indicating that high serum MMP1 levels may be a novel risk factor. These results suggest that cellular disease models with ADPKD-specific iPSCs can be used to study the disease mechanisms and to identify novel disease-related molecules or risk factors.
- Published
- 2016
13. Photoluminescence of monovalent indium centres in phosphate glass
- Author
-
Yasuhiro Yamada, Yoshihiko Kanemitsu, Yutaka Fujimoto, Shun Okumura, Toshiaki Ina, Takayuki Yanagida, and Hirokazu Masai
- Subjects
Multidisciplinary ,Valence (chemistry) ,Materials science ,Photoluminescence ,chemistry.chemical_element ,Photochemistry ,Article ,Indium tin oxide ,Amorphous solid ,X-ray absorption fine structure ,Condensed Matter::Materials Science ,chemistry ,Excited state ,Singlet state ,Indium - Abstract
Valence control of polyvalent cations is important for functionalization of various kinds of materials. Indium oxides have been used in various applications, such as indium tin oxide in transparent electrical conduction films. However, although metastable In+ (5 s2 configuration) species exhibit photoluminescence (PL), they have attracted little attention. Valence control of In+ cations in these materials will be important for further functionalization. Here, we describe In+ species using PL and X-ray absorption fine structure (XAFS) analysis. Three absorption bands in the UV region are attributed to the In+ centre: two weak forbidden bands (1S0 → 3P1,1S0 → 3P2) and a strong allowed band (1S0 → 1P1). The strongest PL excitation band cannot be attributed to the conventional allowed transition to the singlet excited state. Emission decay of the order of microseconds suggests that radiative relaxation occurs from the triplet excitation state. The XAFS analysis suggests that these In+ species have shorter In–O distances with lower coordination numbers than in In2O3. These results clearly demonstrate that In+ exists in a metastable amorphous network, which is the origin of the observed luminescent properties.
- Published
- 2015
14. Tin-Doped Inorganic Amorphous Films for Use as Transparent Monolithic Phosphors
- Author
-
Hiroki Miyata, Takayuki Yanagida, Shun Okumura, Yasuhiro Yamada, Hirokazu Masai, and Yoshihiko Kanemitsu
- Subjects
Multidisciplinary ,Chemical substance ,Materials science ,business.industry ,Doping ,chemistry.chemical_element ,Phosphor ,Article ,Amorphous solid ,chemistry ,Emissivity ,Optoelectronics ,Quantum efficiency ,business ,Tin ,Science, technology and society - Abstract
Although inorganic crystalline phosphors can exhibit high quantum efficiency, their use in phosphor films has been limited by a reliance on organic binders that have poor durability when exposed to high-power and/or high excitation energy light sources. To address this problem, Sn2+ -doped transparent phosphate films measuring several micrometers in thickness have been successfully prepared through heat treatment and a subsequent single dip-coating process. The resulting monolithic inorganic amorphous film exhibited an internal quantum efficiency of over 60% and can potentially utilize transmitted light. Analysis of the film’s emissivity revealed that its color can be tuned by changing the amount of Mn and Sn added to influence the energy transfer from Sn2+ to Mn2+. It is therefore concluded that amorphous films containing such emission centers can provide a novel and viable alternative to conventional amorphous films containing crystalline phosphors in light-emitting devices.
- Published
- 2015
15. Narrow Energy Gap between Triplet and Singlet Excited States of Sn2+ in Borate Glass
- Author
-
Kentaro Teramura, Yoshihiko Kanemitsu, Yasuhiro Yamada, Hirokazu Masai, Toshinobu Yoko, and Yuto Suzuki
- Subjects
Multidisciplinary ,Materials science ,Photoluminescence ,Band gap ,Excited state ,Borate glass ,Quantum efficiency ,Phosphor ,Singlet state ,Emission spectrum ,Molecular physics ,Article - Abstract
Transparent inorganic luminescent materials have attracted considerable scientific and industrial attention recently because of their high chemical durability and formability. However, photoluminescence dynamics of ns(2)-type ions in oxide glasses has not been well examined, even though they can exhibit high quantum efficiency. We report on the emission property of Sn(2+)-doped strontium borate glasses. Photoluminescence dynamics studies show that the peak energy of the emission spectrum changes with time because of site distribution of emission centre in glass. It is also found that the emission decay of the present glass consists of two processes: a faster S1-S0 transition and a slower T1-S0 relaxation, and also that the energy difference between T1 and S1 states was found to be much smaller than that of (Sn, Sr)B6O10 crystals. We emphasize that the narrow energy gap between the S1 and T1 states provides the glass phosphor a high quantum efficiency, comparable to commercial crystalline phosphors.
- Published
- 2013
- Full Text
- View/download PDF
16. Narrow Energy Gap between Triplet and Singlet Excited States of Sn2+ in Borate Glass.
- Author
-
Hirokazu Masai, Yasuhiro Yamada, Yuto Suzuki, Kentaro Teramura, Yoshihiko Kanemitsu, and Toshinobu Yoko
- Subjects
OPTICAL properties of borate glass ,ENERGY-band theory of solids ,PROPERTIES of matter ,PHOTOLUMINESCENCE ,ALKALINE earth metals ,QUANTUM optics ,QUANTUM theory - Abstract
Transparent inorganic luminescent materials have attracted considerable scientific and industrial attention recently because of their high chemical durability and form ability. However, photoluminescence dynamics of ns
2 -type ions in oxide glasses has not been well examined, even though they can exhibit high quantum efficiency. We report on the emission property of Sn2+ -doped strontium borate glasses. Photoluminescence dynamics studies show that the peak energy of the emission spectrum changes with time because of site distribution of emission centre in glass. It is also found that the emission decay of the present glass consists of two processes: a faster S1 -S0 transition and a slower T1 -S0 relaxation, and also that the energy difference between T1 and S1 states was found to be much smaller than that of (Sn, Sr)B6O10 crystals. We emphasize that the narrow energy gap between the S1 and T1 states provides the glass phosphor a high quantum efficiency, comparable to commercial crystalline phosphors. [ABSTRACT FROM AUTHOR]- Published
- 2013
- Full Text
- View/download PDF
Catalog
Discovery Service for Jio Institute Digital Library
For full access to our library's resources, please sign in.