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Zircon within chromitite requires revision of the tectonic history of the Eoarchean Itsaq Gneiss complex,Greenland

Geoscience Frontiers 2023年第6期14卷 273-285页

作者： Hik.ru Sawada Tomoak. Morishita Adrien Vezinet Richard Stern k.nichiro Tani Ik.ya Nishio k.nta takahashi D.Graham Pearson k.istoffer Szilas Department of Earth System Science University of ToyamaToyamaJapan X-Star Japan Agency for Marine-Earth Science and Technology(JAMSTEC)KanagawaJapan Faculty of Geosciences and Civil Engineering Kanazawa UniversityKanazawaJapan Lamont-Doherty Earth Observatory Columbia UniversityPalisadesUSA Volcanoes and Earth’s Interior Research Center JAMSTECKanagawaJapan Department of Earth and Atmospheric Sciences University of AlbertaEdmontonCanada Canadian Centre for Isotopic Microanalysis University of AlbertaEdmontonCanada National Museum of Nature and Science TsukubaJapan Department of Geosciences and Natural Resource Management University of CopenhagenCopenhagenDenmark

The Ujaragssuit Nunat layered(UNL)unit in the Itsaq Gneiss Complex,west Greenland,has been consid-ered to contain one of the oldest chromitites on Earth based on~ca.4.1 Ga Hadean whole rock.Pt-Os model ages and ca.3.81 Ga zircon U-Pb age of the surrounding *** study obtained zircon from the chromitite within this unit as well as granitoid sheets that intruded into the UNL ***-situ U-Pb-Hf-O isotope measurements were made on the *** from both the chromitite and the intrusive granitoids show concordant U-Pb ages of ca.2.97-2.95 *** contrast,Hf and 0 isotopic anal-yses indicate that zircons in the chromitites have a different origin from those in the intrusive *** from granitoids yielded Th/U ratios higher than 0.2,initial Hf isotope ratios of 0.2805-0.2807(i.e,initial:Hf value of-11 to-5),andδ^(18)O values of mostly 6.0‰-7.0‰,which are typical for felsic igneous rock. in Archean continental *** least altered zircons from a chromitite exhibited initial Hf isotope ratios of 0.28078-0.28084(i.e.,initial:Hf value of-1.1 to-0.4),close the chondritic value at ca.3.0 Ga and the depleted mantle at ca.3.2 *** zircons also haveδ^(18)O values of 4.2‰6.1‰which correspond to typical mantle *** other chromitite zircons yielded Th/U ratios lower than 0.1,and Hf and 0 isotopic compositions ranging between the least altered zircons and the intrusive granitoid *** results indicate that the zircons in the chromitites crystallized before or during the 2.97-2.95 Ga granitoid intrusion and most of the zircons were altered by subsequent ***,the present results suggest that zircons in the chromitites originally had depleted Hf iso-topic compositions at ca.3.2-3.0 *** can be explained by two different models of the evolution of the UNL *** is that if the UNL unit was formed at>3.81 Ga as previously thought,with the zircons in the chromitites subsequently being precipitated by ca.3.2-2.95 G

关键词： Archean Itsaq gneiss complex Ultramafic rock Metasomatism

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Factors Affecting Thermal Shrink.ge of Mouthguard Sheet during Thermoforming: Model Shape and Sheet Material Thick.ess

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Materials Sciences and Applications 2022年第4期13卷 133-143页

作者： Mutsumi takahashi Yogetsu Bando Department of Physiology The Nippon Dental University School of Life Dentistry at Niigata Niigata Japan BANDO Dental Clinic Ishikawa Japan

The effectiveness and safety of the mouthguard depend on the sheet material thick.ess. The thick.ess of the thermoformed mouthguard is affected by the model undercut and the thermal shrink.ge that occurs when the extruded-molded sheet is reheated. The aim of this study was to clarify the influence of the undercut amount of the model and the thick.ess of the sheet material on the thermal shrink.ge of the extruded sheet. The mouthguard sheet used ethylene-vinyl acetate resin with a thick.ess of 4.0 mm (4M) and 3.0 mm (3M) and was manufactured by extrusion molding. The work.ng models were three hard gypsum models with the undercut amount on the labial side trimmed to 0? (U0), 10? (U10), and 20? (U20). Mouthguard thick.ess after vacuum formation was compared between the conditions formed so that the extrusion direction was vertical (condition V) or parallel (condition P) to the model midline. Differences in the reduction rate of the mouthguard thick.esses of the labial and buccal side depending on the sheet extrusion direction, model angle, and sheet material thick.ess were analyzed by three-way ANOVA and Bonferroni method. The reduction rate of the thick.ess in condition P was significantly greater than in condition V under all conditions except U0-4M on the labial side and U0-4M and U10-4M on the buccal side. In all models, the reduction rate of the thick.esses was significantly greater in 3M than in 4M in the same extrusion direction. In both 4M and 3M, the reduction rate of the thick.esses tended to increase as the amount of undercut increased in each extrusion direction. This study suggested that a model with a large amount of undercut on the labial side or a thin sheet had a significant effect on the thermal shrink.ge of the mouthguard sheet during thermoforming, which leads to the thinning of the mouthguard.

关键词： Mouthguard Thermoforming Thermal Shrink.ge Model Shape Thick.ess

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Effect of Molding Technique That Move Model Position Just before Formation in Production of Laminated Mouthguard

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Materials Sciences and Applications 2023年第6期14卷 325-335页

作者： Mutsumi takahashi Yogetsu Bando Department of Physiology The Nippon Dental University School of Life Dentistry at Niigata Niigata Japan BANDO Dental Clinic Ishikawa Japan

Many molding techniques have been researched to ensure the thick.ess of custom mouthguards. The aim of this study was to clarify the effect on the thick.ess of a laminated mouthguard of a molding technique in which the model position is moved forward just before molding. Mouthguards were molded using a 3.0-mm-thick.ethylene vinyl acetate mouthguard sheet and a pressure molding machine. The molding method was the normal molding method (condition C) and the molding technique (condition MP) in which the model position was moved 20 mm forward just before molding. Regarding the molding of the first layer (F) and the second layer (S), the following four molding methods based on the combination of conditions C and MP were compared;FC-SC, FC-SMP, FMP-SC, and FMP-SMP. Differences in mouthguard thick.ess due to molding conditions for the first and second layers were analyzed by two-way ANOVA and Bonferroni’s multiple comparison test. Significant differences were observed among all molding conditions on the labial surface, and the thick.esses were in the order FC-SC k. which was 1.39 mm thick.r than FC-SC. FC-SC was the thinnest at the cusp, and a significant difference was observed between other molding conditions. On the buccal side, significant differences were observed between all conditions except FC-SMP and FMP-SC, and the thick.esses were in the order FC-SC k.r when a molding technique that moves the model position just before formation was used for the first and second layers. The reduction in thick.ess was suppressed by approximately 23.2% and approximately 10.7% on the labial and buccal sides, respectively, compared with the normal molding method.

关键词： Laminated Mouthguard Thermoforming Molding Technique Thick.ess

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Effect of Various Factors for the Electrochemical Adsorption of Polydopamine on TiO₂ Film

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Journal of Materials Science and Chemical Engineering 2022年第3期10卷 15-29页

作者： Naomu takahashi Mik.to k.tayama Department of Life Environment and Applied Chemistry Fukuoka Institute of Technology Fukuoka Japan

To fabricate polydopamine-sensitized solar cells with improved solar power conversion efficiency, the effects of pH, buffer, adsorption time and electrode potential for the electrochemical oxidation and polymerization of dopamine on TiO2 film were investigated. The optimum pH was around 7. It was found that the use of a buffer, especially 2-(N-morpholino)ethanesulfonic acid, significantly deteriorated the electrochemical adsorption of polydopamine, and the highest solar power conversion efficiency was obtained without buffer. With increasing adsorption time, the amount of adsorbed polydopamine increased but the solar power conversion efficiency decreased, suggesting the increased resistivity of polydopamine with a larger degree of polymerization. It was suggested that the reversal of electrode potential from positive to negative would be essential for the electrochemical adsorption of polydopamine.

关键词： Dye-Sensitized Solar Cell Dopamine Polydopamine Electrochemical Adsorption Buffer

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Effect of weld faying part groove shape on reduction of inner flash in steel pipe joints fabricated by friction welding

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Advances in Manufacturing 2019年第4期7卷 411-422页

作者： M.k.mura S.Iwamoto M.k.sak. k.k.izu Y.Nak.tani M.takahashi Department of Mechanical Engineering Graduate School of EngineeringUniversity of Hyogo2167 ShoshaHimejiHyogo 671-2280Japan Toshiba Energy Systems&Solutions Corporation 2-4 Suehiro-choTsurumi-kuYokohamaKanagawa 230-0045Japan Department of Mechanical Engineering Faculty of EngineeringNishinippon Institute of Technology1-11 NiitsuKanda-machiMiyako-gunFukuoka 800-0394Japan

The groove shape of the weld faying part was investigated to obtain an ideal pipe frictiowelded joint that had a fracture in the base metal and no inner flash of *** steel pipe had inner and outer diameters of 8.0 mm and 13.5 mm,respectively,and the weld faying surface was of a basic flat shape(butt)***,stepped and tapered groove shapes were *** groove shapes were welded with a friction speed of 27.5 s_1 and a friction load of 2.79 *** phenomena during the welding process were observed,and the tensile strength of joints was *** joints,that fabricated with flat or step groove shapes,made with a friction time at which the friction torque reached the initial peak.did not have the tensile strength of the base metal nor a fracture in the base ***,the joints fabricated with a friction time that reached past the initial peak.had a large flash,and they contained a fracture in the base *** contrast,when joints were made with a gently tapered groove shape with a friction time reaching the time of the initial peak.they achieved a fracture in the base metal,despite having an extremely small inner ***,the shape at the weld faying part was capable of reducing the flash exhausted from the weld interface.

关键词： Friction welding Steel pipe Inner flash Groove shape Taper Joint strength Fracture

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Pediatric nonalcoholic fatty liver disease:Overview with emphasis on histology

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World Journal of Gastroenterology 2010年第42期16卷 5280-5285页

作者： Yoshihisa takahashi Toshio Fuk.sato Department of Pathology Teikyo University School of Medicine2-11-1 KagaItabashi-kuTokyo 173-8605Japan

Nonalcoholic fatty liver disease(NAFLD) is a disease in which excessive fat accumulates in the liver of a patient without a history of alcohol *** disease includes simple steatosis and nonalcoholic steatohepatitis(NASH).NAFLD/NASH is recognized as a hepatic manifestation of metabolic *** recent years,pediatric NAFLD has increased in line with the increased prevalence of pediatric *** estimated prevalence of pediatric NAFLD is 2.6%-9.6%,and it is associated with sex,age,and *** regard to the pathogenesis of NAFLD,the "two-hit" hypothesis is widely accepted and oxidative stress is thought to play an important role in the second *** clinical symptoms,laboratory data,and imaging findings are important,liver biopsy is regarded as the gold standard for the diagnosis of NAFLD/*** addition,liver biopsy is essential for assessing the degree of necro-inflammatory change and fibrosis in *** different types of steatohepatitis(type 1 and type 2 NASH) have been reported,with type 2 NASH being present in as many as 51% of pediatric NAFLD ***,we and others have observed that type 1 and 2 patterns commonly *** pharmacotherapy has been studied in clinical trials,lifestyle modification by diet and exercise remains the mainstay of treatment for NAFLD/NASH.

关键词： Children Histology Nonalcoholic fatty liver disease Nonalcoholic steatohepatitis Obesity

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On a New Geometric Constant Related to the Modulus of Smoothness of a Banach Space

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Acta Mathematica Sinica,English Series 2014年第9期30卷 1526-1538页

作者： Yasuji takahashi Mik.o k.TO Department of System Engineering Okayama Prefectural University Department of Mathematics Faculty of EngineeringShinshu University

We shall introduce a new geometric constant A（X） of a Banach space X, which is closely related to the modulus of smoothness px （T）, and investigate it in relation with the constant As （X） by Baronti et al., the von Neumann-Jordan constant CNj（X） and the James constant J（X）. A sequence of recent results on these constants as well as some other geometric constants will be strengthened and improved.

关键词： Constant A(X) von Neumann-Jordan constant James constant modulus of smoothness modulus of convexity uniform non-squareness

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Discrete dislocation plasticity analysis of dispersion strengthening in oxide dispersion strengthened(ODS) steels

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Journal of Central South University 2014年第4期21卷 1249-1255页

作者： Ak.yuk. takahashi Shota Sato Department of Mechanical Engineering Faculty of Science and TechnologyTokyo University of Science

A discrete dislocation plasticity analysis of dispersion strengthening in oxide dispersion strengthened(ODS) steels was described. Parametric dislocation dynamics(PDD) simulation of the interaction between an edge dislocation and randomly distributed spherical dispersoids(Y2O3) in bcc iron was performed for measuring the influence of the dispersoid distribution on the critical resolved shear stress(CRSS). The dispersoid distribution was made using a method mimick.ng the Ostwald growth mechanism. Then, an edge dislocation was introduced, and was moved under a constant shear stress condition. The CRSS was extracted from the result of dislocation velocity under constant shear stress using the mobility(linear) relationship between the shear stress and the dislocation velocity. The results suggest that the dispersoid distribution gives a significant influence to the CRSS, and the influence of dislocation dipole, which forms just before finishing up the Orowan looping mechanism, is substantial in determining the CRSS, especially for the interaction with small dispersoids. Therefore, the well-k.own Orowan equation for determining the CRSS cannot give an accurate estimation, because the influence of the dislocation dipole in the process of the Orowan looping mechanism is not accounted for in the equation.

关键词：弥散强化刃型位错塑性分析 ODS 氧化物离散剪切应力钢

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Unsteady peristaltic transport of Maxwell fluid through finite length tube:application to oesophageal swallowing

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Applied Mathematics and Mechanics(English Edition) 2012年第1期33卷 15-24页

作者： S. k. PANDEY D. TRIPATHI Department of Applied Mathematics Institute of Technology Banaras Hindu University Department of Mathematics Indian Institute of Technology Ropar

This paper analytically investigates the unsteady peristaltic transport of the Maxwell fluid in a finite tube. The walls of the tube are subjected to the contraction waves that do not cross the stationary boundaries. The analysis is carried out by a long wavelength approximation in the non-dimensional form. The expressions for the axial and radial velocities are derived. The pressures across the wavelength and the tubelength are also estimated. The reflux phenomenon is discussed, which culminates into the determination of the reflux limit. Mathematical formulations are physically interpreted for the flow of masticated food materials such as bread and white eggs in the oesophagus. It is revealed that the Maxwell fluids are favorable to flow in the oesophagus as compared with the Newtonian fluids. This endorses the experimental finding of takahashi et al. （takahashi, T., Ogoshi, H., Miyamoto, k., and Yao, M. L. Viscoelastic properties of commercial plain yoghurts and trial foods for swallowing disorders. Rheology, 27, 169- 172 （1999））. It is further revealed that the relaxation time does not affect the shear stress and the reflux limit. It is found that the pressure peak. are identical in the integral case while different in the non-integral case.

关键词： peristaltic transport Maxwell fluid oesophagus axisymmetric flow reflux

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Charge and Heat Transport in Polycrystalline Metallic Nanostructures

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Chinese Physics Letters 2008年第9期25卷 3360-3363页

作者：张兴 takahashi k.ji FUJII Motoo k.y Laboratory for Thermal Science and Power Engineering of Ministry of Education Department of Engineering Mechanics Tsinghua University Beijing 100084 Graduate School of Engineering Kyushu University Fukuoka 819-0395 Japan Research Center for Hydrogen Industrial Use and Storage AIST Fhkuoka 819-0395 Japan

Metals are typically good conductors in which the abilities to transport charge and to transport heat can be related through the Wiedemann-Franz law. Here we report on an abnormal charge and heat transport in polycrystalline metallic nanostructures in which the ability to transport charge is weak.ned more obviously than that to transport heat. We attribute it to the influence of the internal grain boundaries and have formulated a novel relation to predict the thermal conductivity. The Wiedemann-Franz law is then modified to account for the influence of the grain boundaries on the charge and heat transport with the predictions now agreeing well with the measured results.

关键词： the power-law exponents precipitation durative abrupt precipitation change

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