10 results on '"Tsubasa Imai"'
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2. Multiple-Perspective Caption Generation with Initial Attention Weights.
- Author
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Hidekazu Yanagimoto and Tsubasa Imai
- Published
- 2022
- Full Text
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3. Multiple Cellular Transport and Binding Processes of Unesterified Docosahexaenoic Acid in Outer Blood–Retinal Barrier Retinal Pigment Epithelial Cells
- Author
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Takenori Tomohiro, Tsubasa Imai, Shin Ichi Akanuma, Masanori Tachikawa, Ken Ichi Hosoya, Shun Okayasu, and Yasumaru Hatanaka
- Subjects
0301 basic medicine ,Docosahexaenoic Acids ,genetic structures ,Swine ,Linoleic acid ,Blood–retinal barrier ,Pharmaceutical Science ,Retinal Pigment Epithelium ,Cell Line ,Xenopus laevis ,03 medical and health sciences ,chemistry.chemical_compound ,Blood-Retinal Barrier ,medicine ,Animals ,Humans ,Pharmacology ,chemistry.chemical_classification ,Fatty Acid Transport Proteins ,food and beverages ,Fatty acid ,Biological Transport ,Epithelial Cells ,General Medicine ,Eicosapentaenoic acid ,Transport protein ,030104 developmental biology ,medicine.anatomical_structure ,chemistry ,Biochemistry ,Docosahexaenoic acid ,Oocytes ,lipids (amino acids, peptides, and proteins) ,Arachidonic acid - Abstract
Docosahexaenoic acid (DHA, 22 : 6) is an essential omega-3 long-chain polyunsaturated fatty acid that plays a pivotal role in vision. The purpose of this study was to clarify the cellular uptake and binding processes of free and protein-bound unesterified DHA in retinal pigment epithelial cell (RPE) line ARPE-19 as a model of the human outer blood-retinal barrier and isolated porcine RPE cell fractions. Uptake of free [14C]DHA by ARPE-19 cells was saturable with a Michaelis-Menten constant of 283 µM, and was significantly inhibited by eicosapentaenoic acid, arachidonic acid, and linoleic acid, but not by oleic acid. Further, the uptakes of [14C]DHA associated with retinol-binding protein ([14C]DHA-RBP), [14C]DHA associated with low-density lipoprotein ([14C]DHA-LDL) and [14C]DHA associated with bovine serum albumin ([14C]DHA-BSA) in ARPE-19 cells increased time-dependently at 37°C, and were significantly reduced at 4°C, suggesting the involvement of energy-dependent transport processes. [14C]DHA-LDL uptake by ARPE-19 cells was significantly inhibited by excess unlabeled LDL, but not by an inhibitor of scavenger receptor B type I. Fatty acid transport protein (FATP) 2 and 4 mRNAs were expressed in ARPE-19 cells, and [14C]DHA uptake was observed in FATP2- and FATP4-expressing Xenopus oocytes. Photo-reactive crosslinking and mass spectrometry analyses identified 65-kDa retinal pigment epithelium-specific protein (RPE65) as a DHA-binding protein in porcine RPE cell membrane fractions. Thus, RPE cells possess multiple cellular transport/binding processes for unesterified DHA, involving at least partly FATP2, FATP4, LDL, RBP, and RPE65.
- Published
- 2018
4. Pt Nanoparticles Supported on Mesoporous CeO2 Nanostructures Obtained through Green Approach for Efficient Catalytic Performance toward Ethanol Electro-oxidation
- Author
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Hideki Abe, Sri Ramkumar Vijayan, Gopalakrishnan Kumar, Arivalagan Pugazhendhi, Paskalis Sahaya Murphin Kumar, Siva Kumar Krishnan, Tsubasa Imai, Sivakumar Thiripuranthagan, and Rodrigo Esparza
- Subjects
Cerium oxide ,Materials science ,Renewable Energy, Sustainability and the Environment ,General Chemical Engineering ,Nanotechnology ,02 engineering and technology ,General Chemistry ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Platinum nanoparticles ,Electrocatalyst ,01 natural sciences ,0104 chemical sciences ,Catalysis ,symbols.namesake ,Mesoporous organosilica ,X-ray photoelectron spectroscopy ,symbols ,Environmental Chemistry ,0210 nano-technology ,Mesoporous material ,Raman spectroscopy - Abstract
In this report, an easy and green approach to the synthesis of mesoporous cerium oxide (CeO2) nanostructures and followed by supporting platinum nanoparticles (NPs) on CeO2 nanostructures (Pt/CeO2) and their application as versatile electrocatalysts for ethanol electrooxidation has been established. The synthesis of mesoporous Pt/CeO2 nanostructures involves two steps. First, mesoporous CeO2 nanostructures were synthesized via macroalgae polymer mediated approach and followed by supporting of PtNPs of ca. 5–10 nm over the mesoporous CeO2 nanostructures using seed-mediated chemical reduction process. The structural and spectroscopic characterization techniques such as transmission electron microscopy (TEM), X-ray diffraction (XRD), Raman, X-ray photoelectron spectroscopy (XPS), and small-angle X-ray scattering (SAXS) studies confirm the strong coupling between PtNPs and the mesoporous CeO2 support resulting in the generation of more oxygen vacancies, which can facilitate the enhanced charge transport at th...
- Published
- 2017
5. Mesoporous metallic rhodium nanoparticles
- Author
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Cuiling Li, Joel Henzie, Yusuke Yamauchi, Ömer Dag, Md. Tofazzal Islam, Toshiaki Takei, Hideki Abe, Tsubasa Imai, Kathleen Wood, Bo Jiang, and Md. Shahriar A. Hossain
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Poly(methyl methacrylate) ,Reduction (chemistry) ,Surface area ,General Physics and Astronomy ,Nanoparticle ,02 engineering and technology ,01 natural sciences ,Synthesis ,Rrhodium ,Chemical analysis ,Multidisciplinary ,Porous medium ,021001 nanoscience & nanotechnology ,Mesoporous organosilica ,visual_art ,visual_art.visual_art_medium ,Noble metal ,0210 nano-technology ,Materials science ,Science ,chemistry.chemical_element ,engineering.material ,010402 general chemistry ,Article ,Catalysis ,General Biochemistry, Genetics and Molecular Biology ,Rhodium ,Metal ,Oxidation ,Thermal stability ,Reduction ,Methanol ,Crystal structure ,Nitric oxide ,General Chemistry ,Concentration (composition) ,0104 chemical sciences ,Oxygen ,Macrogol ,Chemical engineering ,chemistry ,Concentration (parameters) ,engineering ,Catalyst ,Thermostability ,Mesoporous material ,Controlled study - Abstract
Mesoporous noble metals are an emerging class of cutting-edge nanostructured catalysts due to their abundant exposed active sites and highly accessible surfaces. Although various noble metal (e.g. Pt, Pd and Au) structures have been synthesized by hard- and soft-templating methods, mesoporous rhodium (Rh) nanoparticles have never been generated via chemical reduction, in part due to the relatively high surface energy of rhodium (Rh) metal. Here we describe a simple, scalable route to generate mesoporous Rh by chemical reduction on polymeric micelle templates [poly(ethylene oxide)-b-poly(methyl methacrylate) (PEO-b-PMMA)]. The mesoporous Rh nanoparticles exhibited a ∼2.6 times enhancement for the electrocatalytic oxidation of methanol compared to commercially available Rh catalyst. Surprisingly, the high surface area mesoporous structure of the Rh catalyst was thermally stable up to 400 °C. The combination of high surface area and thermal stability also enables superior catalytic activity for the remediation of nitric oxide (NO) in lean-burn exhaust containing high concentrations of O2., Mesoporous noble metal nanostructures offer great promise in catalytic applications. Here, Yamauchi and co-workers synthesize mesoporous rhodium nanoparticles using polymeric micelle templates, and report appreciable activities for methanol oxidation and NO remediation.
- Published
- 2017
6. Nanophase-separated Ni3Nb as an automobile exhaust catalyst
- Author
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Yuta Yamamoto, Toyokazu Tanabe, Satoshi Nagao, Takeshi Fujita, Shigeo Arai, Shigenori Ueda, Gubbala V. Ramesh, Tomoharu Tokunaga, Shin Ichi Matsumoto, Hirohito Hirata, Hideki Abe, and Tsubasa Imai
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Materials science ,Inorganic chemistry ,Niobium ,Oxide ,Intermetallic ,chemistry.chemical_element ,02 engineering and technology ,General Chemistry ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,Catalysis ,Metal ,chemistry.chemical_compound ,chemistry ,visual_art ,visual_art.visual_art_medium ,Niobium oxide ,0210 nano-technology ,Platinum ,Carbon monoxide - Abstract
Catalytic remediation of automobile exhaust has relied on precious metals (PMs) including platinum (Pt). Herein, we report that an intermetallic phase of Ni and niobium (Nb) (i.e., Ni3Nb) exhibits a significantly higher activity than that of Pt for the remediation of the most toxic gas in exhaust (i.e., nitrogen monoxide (NO)) in the presence of carbon monoxide (CO). When subjected to the exhaust-remediation atmosphere, Ni3Nb spontaneously evolves into a catalytically active nanophase-separated structure consisting of filamentous Ni networks (thickness < 10 nm) that are incorporated in a niobium oxide matrix (i.e., NbOx (x < 5/2)). The exposure of the filamentous Ni promotes NO dissociation, CO oxidation and N2 generation, and the NbOx matrix absorbs excessive nitrogen adatoms to retain the active Ni0 sites at the metal/oxide interface. Furthermore, the NbOx matrix immobilizes the filamentous Ni at elevated temperatures to produce long-term and stable catalytic performance over hundreds of hours.
- Published
- 2017
7. N2O-emission-free exhaust remediation by Rh-NbOx nanocomposites developed from Rh3Nb alloy precursor
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Koolath Ramakrishnan Deepthi, Shigenori Ueda, Satoshi Nagao, Tsubasa Imai, Hirohito Hirata, and Hideki Abe
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Materials science ,Nanocomposite ,General Chemical Engineering ,Alloy ,Inorganic chemistry ,chemistry.chemical_element ,Nanoparticle ,02 engineering and technology ,General Chemistry ,engineering.material ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Dissociation (chemistry) ,0104 chemical sciences ,Catalysis ,Rhodium ,chemistry.chemical_compound ,chemistry ,engineering ,Nitrogen oxide ,0210 nano-technology ,Carbon monoxide - Abstract
Metal-oxide nanocomposites comprising rhodium (Rh) nanoparticles (
- Published
- 2017
8. Topologically immobilized catalysis centre for long-term stable carbon dioxide reforming of methane
- Author
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Takeshi Fujita, Ayako Hashimoto, Tomoharu Tokunaga, Shigenori Ueda, Masahiro Miyauchi, Hideki Abe, Kimitaka Higuchi, Noritatsu Tsubaki, Shusaku Shoji, Yuta Yamamoto, Xiaobo Peng, Paskalis Sahaya Murphin Kumar, Tsubasa Imai, and Shigeo Arai
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Carbon dioxide reforming ,Methane reformer ,010405 organic chemistry ,Nanoparticle ,chemistry.chemical_element ,General Chemistry ,010402 general chemistry ,01 natural sciences ,Methane ,0104 chemical sciences ,Catalysis ,Metal ,chemistry.chemical_compound ,Chemistry ,chemistry ,Chemical engineering ,visual_art ,visual_art.visual_art_medium ,Carbon ,Syngas - Abstract
A rooted catalyst, Ni#Y2O3, successfully inhibits the growth of carbon nanotubes in DRM., Methane reforming at low temperatures is of growing importance to mitigate the environmental impact of the production of synthesis gas, but it suffers from short catalyst lifetimes due to the severe deposition of carbon byproducts. Herein, we introduce a new class of topology-tailored catalyst in which tens-of-nanometer-thick fibrous networks of Ni metal and oxygen-deficient Y2O3 are entangled with each other to form a rooted structure, i.e., Ni#Y2O3. We demonstrate that the rooted Ni#Y2O3 catalyst stably promotes the carbon-dioxide reforming of methane at 723 K for over 1000 h, where the performance of traditional supported catalysts such as Ni/Y2O3 diminishes within 100 h due to the precluded mass transport by accumulated carbon byproducts. In situ TEM demonstrates that the supported Ni nanoparticles are readily detached from the support surface in the reaction atmosphere, and migrate around to result in widespread accumulation of the carbon byproducts. The long-term stable methane reforming over the rooted catalyst is ultimately attributed to the topologically immobilized Ni catalysis centre and the synergistic function of the oxygen-deficient Y2O3 matrix, which successfully inhibits the accumulation of byproducts.
- Published
- 2018
9. Sintering-Resistant Nanoparticles in Wide-Mouthed Compartments for Sustained Catalytic Performance
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Katsuhiko Ariga, Tsubasa Imai, Qingmin Ji, Jia Liu, and Hideki Abe
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Multidisciplinary ,Materials science ,Industrial catalysts ,Nanoparticle ,Sintering ,Nanotechnology ,02 engineering and technology ,Mesoporous silica ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Article ,0104 chemical sciences ,Catalysis ,law.invention ,law ,Particle ,Calcination ,Particle size ,0210 nano-technology - Abstract
Particle sintering is one of the most significant impediments to functional nanoparticles in many valuable applications especially catalysis. Herein, we report that sintering-resistant nanoparticle systems can be realized through a simple materials-design which maximizes the particle-to-particle traveling distance of neighbouring nanoparticles. As a demonstration, Pt nanoparticles were placed apart from each other in wide-mouthed compartments tailored on the surface of self-assembled silica nanosheets. These Pt nanoparticles retained their particle size after calcination at elevated temperatures because the compartment wall elongates the particle-to-particle traveling distance to preclude the possibility of sintering. Moreover, these Pt nanoparticles in wide-mouthed compartments were fully accessible to the environment and exhibited much higher catalytic activity for CO oxidation than the nanoparticles confined in the nanochannels of mesoporous silica. The proposed materials-design strategy is applicable not only to industrial catalysts operating in harsh conditions, but also opens up possibilities in developing advanced nanoparticle-based materials with sustained performance.
- Published
- 2017
10. Influence of Dietary Protein Levels on the Fate of Inorganic Mercury in Mice
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Tatsumi Adachi, Masaaki Nagano, Tsukasa Ebihara, Masatake Fujimura, Tsubasa Imai, and Yasunobu Suketa
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Single administration ,medicine.medical_specialty ,Kidney ,Chemistry ,Health, Toxicology and Mutagenesis ,Liver and kidney ,chemistry.chemical_element ,Toxicology ,Inorganic mercury ,Mercury (element) ,Dietary protein ,Endocrinology ,medicine.anatomical_structure ,Biochemistry ,Internal medicine ,medicine ,Metallothionein - Abstract
Influence of dietary protein levels on mercury (Hg) fate and on tissue metallothionein (MT) levels was investigated in mice. Twenty-four hr after single administration of mercuric chloride (2.5mg Hg/kg, subcutaneous), the hepatic Hg concentration was enhanced by dietary protein deficiency, whereas the levels in other tissues and excrements were not affected. At that time, MT inductions by mercuric chloride in liver and kidney were suppressed by dietary protein deficiency, despite no observable differences in basal levels. Thus, Hg levels in the liver and kidney showed little correlation with MT levels. A further experiment demonstrated an enhancement of Hg concentration in the liver by dietary protein deficiency at 3a nd 12hr but not at 1hr, and the Hg concentration in the kidney was transiently enhanced at 3hr. Accordingly, the differences in Hg fate would arise considerably earlier, probably before MT induction. The present results suggest that dietary protein status modifies the fate of inorganic Hg, especially in the liver, probably independent of the differences in dietary protein level-dependent varying levels of MT.
- Published
- 2008
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