核融合用炭化珪素繊維強化金属複合材料に関する研究

京都大学新制・課程博士博士(エネルギー科学)甲第24718号エネ博第461号新制||エネ||86(附属図書館)京都大学大学院エネルギー科学研究科エネルギー応用科学専攻(主査)教授 宮内 雄平, 教授 大垣 英明, 准教授 中嶋 隆, 特定教授 檜木 達也学位規則第4条第1項該当Doctor of Energy ScienceKyoto UniversityDFA

Effect of tungsten matrix on the mechanical property of SiC fiber reinforced tungsten composites with foils fabricated at 1700 °C

The SiC fiber reinforced tungsten (W) composites were prepared by hot press process at 1700 °C for 1 h under a pressure of 20 MPa with W foils as matrix. The effect of thickness of W foils on the phases, microstructure, and mechanical properties of the composites were investigated in this work. In addition, the recrystallization temperature of W foil used in this work was confirmed. The results demonstrated that the composites with 0.08 mm foil exhibited better mechanical property with 197 MPa and high pseudo ductility than those of the 0.05 mm foil composites of 129 MPa. In addition, the used foils after sintering have recrystallized, and W can be identified by XRD. Therefore, SiC fiber can be an effective reinforcement to toughen W and dense foils as matrix can prevent the reaction partially

Läänemere idaosa litoraali kalakoosluste varieeruvus ja selle põhjused

Väitekirja elektrooniline versioon ei sisalda publikatsiooneLitoraalialad on vee-elustikule oluliseks sigimis-, kasvu- ja toitumisalaks. Muutlike abiootiliste ja biootiliste keskkonnategurite koosmõjul varieerub litoraalialade kalakoosluste liigiline koosseis väga suurel määral nii ajas kui ka ruumis. Käesoleva töö eesmärkideks oli välja selgitada: 1) Läänemere litoraali asustavate kalaliikide ööpäevaringseid ja aastasiseseid käitumismustreid; 2) litoraali kalastiku sesoonse toitumisökoloogia eripärad meritindi näitel; 3) anadroomsete kalade (lõhe ja meriforell) noorjärkude alternatiivseid rändestrateegiaid jõgede ja Läänemere litoraalialade vahel. Selgus, et: 1) Läänemere litoraali asustavate kalaliikide ööpäevaringne käitumine on seni kirjeldatust oluliselt mitmetahulisem. Seega, mingi konkreetse litoraali piirkonna ööpäevas muutuva liigilise koosseisu täielikuks kirjeldamiseks on vajalik proovipüükide tegemine nii hommikul, keskpäeval, õhtul kui ka öösel; 2) Läänemere idaosa litoraaliala asustava meritindi toitumiskäitumine erineb avamere elupaikades kirjeldatust; 3) Läänemere riimveelised litoraalialad võivad olla seni arvatust olulisemaks kasvualaks alternatiivseid rändestrateegiaid kasutavatele lõhilaste noorjärkudele; 4) läbi riimvee vooluveekogu vahetavad noorkalad võivad osaliselt olla ka anadroomsete lõhilaste populatsioonides esinevate „eksijate“ varem kirjeldamata tekkemehhanismiks; 5) Läänemere litoraali asustavatel kalaliikidel võib esineda nii piirkonnaspetsiifilisi ööpäevaringseid toitumisrändeid (meritint) kui ka elukäigumustreid (lõhe, meriforell).The shallow littoral is an important reproduction, nursery, and foraging area to coastal marine biota. Due to variability in abiotic and biotic environmental parameters, near-shore fish communities of the Baltic Sea are highly variable. Thus, the occurrence and abundance of fish species may be spatially and temporally highly variable. The objectives of the present thesis were to: 1) assess diel variations in the composition of the fish assemblage in the surf-zone of the non-tidal Baltic Sea; 2) estimate the predatory role of European smelt in a littoral habitat by describing seasonal variation of prey composition; 3) investigate whether littoral zone of the Baltic Sea also function as a habitat for early out-migrating Atlantic salmon and anadromous brown trout (ABT) fry and parr. The main results and conclusions are the following: 1) fine-scale variations in littoral fish assemblages are more complex and may take place within shorter time frame than previously known; 2) European smelt inhabiting littoral areas of the Baltic Sea occupy different ecological niche than smelt in offshore areas; 3) alternative migrations of juvenile salmonids between freshwater and brackish environments indicate that the shallow littoral zone of the Baltic Sea may play a significant role as a permanent or provisional nursery area to these species; 4) the phenomenon of stream shifting through the marine environment may constitute at least one possible mechanism behind the straying behaviour documented during the spawning runs of Atlantic salmon and ABT in the Baltic Sea basin; 5) some coastal fish species inhabiting the Baltic Sea might show sub-basin specific behaviour in terms of their regular diel movements and alternative life history pattern

Comparison of five single-file systems in the preparation of severely curved root canals: an ex vivo study

Abstract Background The ex vivo study is to compare the root canal preparation outcomes achieved by five nickel–titanium single-file instrumentation systems (M3-L, Reciproc Blue, V-Taper 2H, WaveOne Gold, XP-endo Shaper) in severely curved molar root canals. Methods A total of 60 root canals were selected from extracted human molar teeth with curvatures ranging from 25° to 50° and divided into five groups based on the instrumentation system employed (n = 12). Before and after root canal preparation, a Micro-CT scan was taken, and pre- and post-operative data were analyzed to evaluate the following parameters: volume increment of root canals (VI), untouched root canal areas (UTA), and canal transportation (CT). Apically extruded debris (AD) was collected during preparation. After that, all samples were separated into two parts and examined respectively by scanning electron microscope (SEM) to assess cleaning ability. Data were statistically analyzed with ANOVA (UTA, AD, VI) or Kruskal–Wallis test (CT, SEM-score), the level of significance was set at α = 0.05. Results There were no significant differences between the five systems regarding the AD, VI, and UTA parameters (P > 0.05). In terms of CT, no significant difference was noted at the straight section of canal and apical levels, while XP-endo Shaper showed less canal transportation than M3-L at the level of curved vertex (P < 0.05), and the centering ability of V-Taper 2H was significantly better than WaveOne Gold at the initial point of bending (P < 0.05). Debris and smear layers were present on the canal walls of all specimens, the apical thirds of the canal presented higher SEM scores than the coronal thirds in all groups (P < 0.05). Reciproc Blue and XP-endo Shaper showed fewer smear scores than WaveOne Gold in the apical thirds (P < 0.01 and P < 0.05, respectively), and no statistical difference was found between other groups in the middle and coronal thirds. Conclusion The five single-file systems evaluated performed equally in apically debris extrusion, dentin removal, and untouched root canal areas, while XP-endo Shaper and V-Taper 2H resulted in less canal transportation compared to M3-L and WaveOne Gold. Regarding cleaning ability, Reciproc Blue and XP-endo Shaper were associated with less smear layer than WaveOne Gold in the apical thirds

Linear and non-linear dynamics of ecosystem services supply, demand, and mismatches across a rapidly urbanizing region

Achieving the sustainability of coupled human-nature systems requires matching the ecosystem services (ES) provided by nature to the needs of society. However, most of the current studies on ES supply–demand relationships focus on spatial mismatches and rarely consider their temporal dynamics. In this study, the year-by-year dynamics (2001–2020) of 12 ESs at multiple spatial scales were investigated by using space–time interaction (STI) analysis, fuzzy C-mean clustering, and emerging hotspot analysis. We found that (1) three forms of temporal dynamics of ES indicators can be identified, including linear dynamics, fluctuating dynamics, and regime shift dynamics. (2) Temporal dynamic patterns of the same ES were not consistent across all counties, showing great spatial heterogeneity. The temporal dynamics of each ES type at each county were spatially explicitly clustered into linear dynamics, fluctuating dynamics, and regime shift dynamics with different means. (3) The ES supply–demand relationships can shift between supply–demand balance, excess supply, and excess demand when the temporal dynamics of ES supply do not match with that of ES demand. Our results suggest that temporal dynamic analysis in ecological restoration effectiveness assessment can help to avoid erroneous results compared to considering only pre- and post-policy ES changes. The identified emerging hotspots of excess supply and excess demand can help decision-makers more accurately identify priority locations for management

Endocrinology

Inflammation is a key event in hypertensive organ damage, and TNF-alpha and IL-1 beta are elevated in hypertension. In this study, we evaluated the effects of TNF-alpha and IL-1 beta elevation on hypertensive cardiac damage by treatment with a bifunctional inflammatory inhibitor, TNF receptor 2-fragment crystalization-IL-1 receptor antagonist (TFI), which can neutralize these 2 cytokines simultaneously. A mouse hypertension model of angiotensin II (Ang II) infusion (1500 ng/kg.min for 7 d) was induced in wild-type mice. TNF-alpha and IL-1 beta were inhibited by TFI administration (5 mg/kg, every other day), the effects of inhibition on cardiac damage were examined, and its mechanism on inflammatory infiltration was further studied in vivo and in vitro. Ang II infusion induced cardiac injury, including increased macrophage infiltration, expression of inflammatory cytokines (IL-12, IL-6, etc), and cardiac fibrosis, such as elevated alpha-smooth muscle actin, collagen I, and TGF-beta expression. Importantly, the Ang II-induced cardiac injury was suppressed by TFI treatment. Moreover, TFI reduced the expression of adhesion molecules (intercellular adhesion molecule-1 and vascular cell adhesion molecule-1) and monocyte chemotactic protein-1 expression in Ang II-treated hearts. Additionally, blockade of TNF-alpha and IL-1 beta by TFI reduced monocyte adherence to endothelia cell and macrophage migration. This study demonstrates that blocking TNF-alpha and IL-1 beta by TFI prevents cardiac damage in response to Ang II, and targeting these 2 cytokines simultaneously might be a novel tool to treat hypertensive heart injury.Inflammation is a key event in hypertensive organ damage, and TNF-alpha and IL-1 beta are elevated in hypertension. In this study, we evaluated the effects of TNF-alpha and IL-1 beta elevation on hypertensive cardiac damage by treatment with a bifunctional inflammatory inhibitor, TNF receptor 2-fragment crystalization-IL-1 receptor antagonist (TFI), which can neutralize these 2 cytokines simultaneously. A mouse hypertension model of angiotensin II (Ang II) infusion (1500 ng/kg.min for 7 d) was induced in wild-type mice. TNF-alpha and IL-1 beta were inhibited by TFI administration (5 mg/kg, every other day), the effects of inhibition on cardiac damage were examined, and its mechanism on inflammatory infiltration was further studied in vivo and in vitro. Ang II infusion induced cardiac injury, including increased macrophage infiltration, expression of inflammatory cytokines (IL-12, IL-6, etc), and cardiac fibrosis, such as elevated alpha-smooth muscle actin, collagen I, and TGF-beta expression. Importantly, the Ang II-induced cardiac injury was suppressed by TFI treatment. Moreover, TFI reduced the expression of adhesion molecules (intercellular adhesion molecule-1 and vascular cell adhesion molecule-1) and monocyte chemotactic protein-1 expression in Ang II-treated hearts. Additionally, blockade of TNF-alpha and IL-1 beta by TFI reduced monocyte adherence to endothelia cell and macrophage migration. This study demonstrates that blocking TNF-alpha and IL-1 beta by TFI prevents cardiac damage in response to Ang II, and targeting these 2 cytokines simultaneously might be a novel tool to treat hypertensive heart injury

Highly efficient hydrogen evolution catalysis based on MoS2/CdS/TiO2 porous composites

Efficient production of hydrogen through visible-light-driven water splitting mechanism using semiconductor-based composites has been identified as a promising strategy for converting light into clean H2 fuel. However, researchers are facing lots of challenges such as light absorption and electron-hole pair recombination and so on. Here, new sheet-shaped MoS2 and pyramid-shaped CdS in-situ co-grown on porous TiO2 photocatalysts (MoS2–CdS–TiO2) are successfully obtained via mild sulfuration of MoO3 and CdO coexisted inside porous TiO2 monolith by a hydrothermal route. The scanning electron microscopy and transmission electron microscopy results exhibit that the MoS2–CdS–TiO2 composites have average pore size about 500 nm. The 3%MoS2–10%CdS–TiO2 demonstrated excellent photocatalytic activity and high stability for a hydrogen production with a high H2-generation rate of 4146 μmol h−1 g−1 under visible light irradiation even without noble-metal co-catalysts. The super photocatalytic performance of the visible-light-driven hydrogen evolution is predominantly attributed to the synergistic effect. The conduction band of MoS2 facilitates in transporting excited electrons from visible-light on CdS to the porous TiO2 for catalytic hydrogen production, and holes to MoS2 for inhibiting the photocorrosion of CdS, respectively, leading to enhancing the efficient separation of electrons and holes. © 2018 Hydrogen Energy Publications LL © 2018 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved2