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Effect of the processing route on the microstructure and mechanical behavior of superlight Mg-9Li-1Zn alloy via friction stir processing

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Journal of Magnesium and Alloys 2022年第11期10卷 3064-3081页

作者： Mengran Zhou Zhuoran Zeng Chun Cheng Yoshiaki Morisada Qingyu Shi Jian-Yih Wang Hidetoshi fujii Joining and Welding Research Institute(JWRI) Osaka UniversityOsakaJapan Department of Mechanical Engineering Tsinghua UniversityBeijing 100084China State Key Laboratory of Tribology Tsinghua UniversityBeijingChina Key Laboratory for Advanced Materials Processing Technology Ministry of Education of China Tsinghua UniversityBeijing 100084China College of Engineering and Computer Science Australian National UniversityACT 2601Australia Department of Materials Science and Engineering National Dong-Hwa UniversityHwa-LianTaiwanChina

In this study, the effect of the processing route using a friction stir processing(FSP) method on the microstructure and mechanical behavior of a Mg-9Li-1Zn alloy was systematically investigated. In the FSP method, the odd-numbered(1st and 3rd) process directions and even-numbered(2nd and 4th) passes were alternated to distribute the strain throughout the whole processed zone uniformly. Consequently, the processed zone had a much more uniform microstructure and hardness distribution than the processed zone obtained using the conventional FSP method. Using this method, the grain size of a Mg-9Li-1Zn sheet alloy was refined from ~31 μm to ~0.21 μm with uniformly distributedα and β phases. The processed alloy exhibited a high strength-ductility synergy with an ultimate tensile strength(UTS) of 220.1 MPa and total elongation of 70.0% at a strain rate of 10^(-3)s^(-1), overwhelmingly higher than those of the base metal, 155.6 MPa in UTS and 36.0%in elongation. The in-situ SEM-DIC analysis and TEM observation demonstrated that such an outstanding ductility with moderate strength is caused by grain boundary sliding, the dominant deformation mechanism of the ultra-fine-grained sample after FSP. The processing route with reverse processing direction was proven to be efficient in producing the ultrafine grain size microstructure and improving the mechanical properties of superlight Mg-9Li-1Zn alloy.

关键词： Mg-Li-Zn alloy Friction stir processing Microstructure In-situ SEM-DIC Mechanical properties

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Flat friction spot joining of aluminum alloy to carbon fiber reinforced polymer sheets:Experiment and simulation

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Journal of Materials Science & Technology 2022年第12期107卷 266-289页

作者： Peihao Geng Ninshu Ma Hong Ma Yunwu Ma Kazuki Murakami Huihong Liu Yasuhiro Aoki Hidetoshi fujii Joining and Welding Research Institute Osaka University11-1 MihogaokaOsaka 567-0047IbarakiJapan MOE Key Lab for Liquid-Solid Structure Evolution and Material Processing Institute of Materials JoiningShandong UniversityJinan 250061China

The Al alloy and carbon fiber reinforced polymer(CFRP)hybrid structures,incorporating the performance advantages of the two materials,have been attracting more attention in high-end manufacturing *** the current investigation,the flat friction spot joining(FSJ)was employed in joining the AA6061-T6 alloy and CFRP *** significance of temperature distribution in influencing joint quality was highlighted through analyzing interface microstructural features,weld defect formation as well as *** understand the role of thermal energy generation and conduction in the process comprehensively,a 3D thermal-mechanical coupling finite element model was *** interfacial temperature was characterized by an uneven distribution behavior due to the inhomogeneous heat *** peak temperatures on the top surface and Al alloy to CFRP interface at 1500 rpm rotational speed with 0.1 mm/s plunging speed were 498℃and 489°C,*** peak interface temperature was reduced to286℃at 250 rpm,which produced an extremely small melted *** with the plunging speed,rotational speed was found to be the predominant parameter for determining the joint property,which could be optimized to simultaneously realize the avoidance of thermal decomposition of CFRP,the sufficient melting duration time,and the wide enough melted *** thermal histories and melted area profiles were in agreement with experimental *** findings could be utilized to provide some feasible guidance for process optimization of dissimilar FSJ of metals and composites.

关键词： Friction spot joining Numerical simulation CFRP/Al alloy Interface microstructure Thermal conduction

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Fluorescence‑Based Calibration Model for In‑Situ Measurement of Micro‑scaled Lubricant Thickness Distribution at Indentation Interface

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Nanomanufacturing and Metrology 2024年第2期7卷 76-88页

作者： Motoya Yoshikawa Saeko fujii Shotaro Kadoya Tatsuya Sugihara Masaki Michihata Satoru Takahashi Department of Precision Engineering The University of TokyoHongo 7‑3‑1BunkyoTokyo 113‑8656Japan Department of Mechanical Engineering Osaka UniversityYamadaoka 2‑1SuitaOsaka 565‑0871Japan

This study proposes a model for the measurement of microscale liquid film thickness distribution using fluorescence *** interfacial conditions between the tool and the workpiece in mechanical machining are important for understanding these phenomena and *** this study,indentation tests with transparent tools were used to observe interfaces;however,it was challenging to obtain the signal from a thin fluorescent liquid film on smooth and steeply inclined ***,fluorescence-based measurement,such as laser-induced fluorescence,was *** measure the absolute thickness of the thin fluorescent film,calibration of the measurement system is ***,a theoretical model was proposed considering the multiple reflections of excitation light and fluorescence at the inclined surface between the indenter and *** measuring the profile of the surface topography of the indented workpiece and comparing the results with those measured by a surface profiler,the validity of the proposed calibration method and the performance of this measurement system were *** measured surface profiles,including scratches of 2–4μm,were in good agreement,demonstrating the validity of the proposed method.

关键词： Laser-induced fluorescence(LIF) Thickness distribution In-situ measurement Lubricant Mechanical machining

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Worsening of coronary spasm during the perioperative period:A case report

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World Journal of Cardiology 2014年第7期6卷 685-688页

作者： hiroki Teragawa Kenji Nishioka Yuichi fujii Naomi Idei Takaki Hata Shuji Kurushima Tomoki Shokawa Yasuki Kihara Department of Cardiovascular Medicine Hiroshima University Hospital

We present the case of a 65-year-old male with vasospastic angina(VSA)whose condition worsened during the perioperative *** had been diagnosed with VSA 10 years *** was treated with two types of vasodilators and had not experienced any chest symptoms for 5 *** this juncture,he underwent surgery for relapsed maxillary sublingual *** had taken two vasodilators one day prior to *** infusion of nitroglycerin(NTG)was initiated immediately before the surgery and continued the following *** of stopping NTG,a dermal isosorbide dinitrate tape was applied on post-operative day *** days later,a complete atrioventricular block with pulseless electrical activity *** cardiopulmonary resuscitation,emergent coronary angiography showed severe coronary spasm in both the left and right coronary *** infusion of nitroglycerin and epinephrine with percutaneous cardiopulmonary support relieved the coronary *** the perioperative period,several factors can trigger coronary vasospasm,including the discontinuation of ***,surgeons,anesthetists,and cardiologists should watch for coronary vasospasm during this period and for worsening coronary spasm when discontinuing vasodilators in patients at risk for VSA.

关键词： Coronary vasospasm Perioperative period Discontinuation of vasodilator

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Rupture locations of friction stir welded joints of AA2017-T351 and AA6061-T6 aluminum alloys

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中国有色金属学会会刊：英文版 2005年第3期15卷 515-518页

作者：刘会杰冯吉才 H.fujii M.Maeda K.Nogi State Key Laboratory of Advanced Welding Production Technology Harbin Institute of Technology Harbin 150001 China Joining and Welding Research Institute Osaka University Osaka 567-0047 Japan

The tensile rupture locations of friction stir welded joints of AA2017-T351 and AA6061-T6 aluminum alloys were examined. The experiments show that the rupture locations of the joints are different for the two aluminum alloys, which are influenced by the welding parameters. When the joints are free of welding defects, the AA2017-T351 joints are ruptured in the weld nugget adjacent to the thermo-mechanically affected zone on the advancing side and the rupture surfaces appear as oval contours of the weld nugget, while the AA6061-T6 joints are ruptured in the heat affected zone on the retreating side and the rupture surfaces are inclined at a certain degree to the bottom surfaces of the joints. When welding defects are present in the joints, the AA2017-T351 joints are ruptured in the weld center, while the AA6061-T6 joints are ruptured on the retreating side near the weld center. The rupture locations of the joints are dependent on the internal structures of the joints and can be explained through them.

关键词：铝合金摩擦搅拌焊接韧性测试技术参数局部破裂

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Evaluation of dynamic development of grain structure during friction stir welding of pure copper using a quasi in situ method

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Journal of Materials Science & Technology 2019年第7期35卷 1412-1421页

作者： X.C.Liu Y.F.Sun T.Nagira K.Ushioda H.fujii Joining and Welding Research Institute Osaka University11-1 MihogaokaIbarakiOsaka567-0047Japan School of Materials Science and Engineering Northwestern Polytechnical UniversityXi'an710072China School of Materials Science and Engineering Zhengzhou UniversityZhengzhou450001China

By employing a quasi in situ method, we investigated the dynamic evolution of the grain structure con-sidering the material flow, strain, and strain rate in the friction stir welding of pure copper. The tool' stop action' and rapid cooling were employed and a brass foil was used as a marker to show the material flow path. The grain structure along the material flow path was characterised using electron backscatter diffraction. Static recrystallization occurs for the work-hardened base material in the preheating stage in front of the tool In the acceleration flow stage, grains are significantly refined by plastic deforma-tion, discontinuous dynamic recrystallization, annealing twinning during the strain-induced boundary migration and slight continuous dynamic recrystallization. In the deceleration flow stage, due to a strain reversal, the grain first coarsens, and is thereafter refined again. Finally, the hot-deformed material in the shoulder-affected zone is ‘frozen’ directly whereas that in the probe-affected zone undergoes signif-icant annealing;thus, the recrystallized microstructure and 45°-rotated cube texture are obtained in the probe-affected zone.

关键词： Friction stir welding Grain structure Material flow Pure copper EBSD

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Electric Field Enhancement of Nano Gap of Silver Prisms

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Chinese Physics Letters 2007年第10期24卷 2934-2937页

作者： KENZO Yamaguchi TOMOHIRO Inoue MASAMITSU fujii MASANOBU Haraguchi TOSHIHIRO Okamoto MASUO Fukui SHU Seki SEIICHI Tagawa Department of Optical Science and Engineering Faculty and School of Engineering The University of Tokushima 2-1 Minamijosanjima-cho Tokushima-city Tokushima 770-8506 Japan Department of Electronics and Mechanics Toba National College of Maritime Technology 1-1 Ikegami-cho Toba-city Mie 517-8501 Japan Institute of Scientific and Industrial Research Osaka University 8-1 Mihogaoka Ibaraki Osaka 567-0047 Japan

Using numerical calculation, we examine the effects of gap distance of a pair of nano gap silver prisms with rounded corners on the local light intensity enhancement. Two peaks due to localized surface plasmon （LSP） excitation are observed in a wavelength range from 900nm to 300nm. The results demonstrate that peaks at a longer and a shorter wavelength corresponded to dipole-like and quadrupole-like LSP resonances, respectively. It is found that a gap distance up to 20 nm provides larger light intensity enhancement than that of a single silver nano prism with rounded corners. Furthermore, nano gap silver prisms are fabricated by direct focused ion beam processing, and we measure the scattering light spectrum of a pair of nano prisms by a confocal optical system. However, the two LSP peaks are not observed in visible range because the sizes of the nano gap and prisms are too large.

关键词： SURFACE-PLASMON RESONANCE AG NANOPARTICLES NEAR-FIELD NANOANTENNAS SCATTERING

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Gene expression of CCL8 and CXCL10 in peripheral blood leukocytes during early pregnancy in cows

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Journal of Animal Science and Biotechnology 2018年第4期9卷 813-823页

作者： Ryosuke Sakumoto Kosuke Iga Ken-Go Hayashi Shiori fujii Hiroko Kanahara Misa Hosoe Tadashi Furusawa Division of Animal Breeding and Reproduction Research Institute of Livestock and Grassland Science National Agriculture and Food Research Organization (NARO) Division of Livestock and Forage Research Tohoku Agricultural Research CenterNARO Division of Animal Sciences Institute of Agrobiological SciencesNARO

Background: The aim of the present study was to evaluate CCL8 and CXCL10 expression and its regulatory mechanism in peripheral blood leukocytes(PBLs) at the time of maternal recognition in cows. Blood samples were collected on 14, 15, 16, 17 and 18 d after artificial insemination(AI). Based on the day of return of estrus, cows were divided into three groups, pregnant(n = 5), early embryonic mortality(EEM; n = 5) and late embryonic mortality(LEM; n = 5). The gene expression levels in PBLs were assessed with quantitative real-time reverse transcription ***: The expression of CCL8 and CXCL10 mRNA in PBLs gradually increased from 14 to 18 d of pregnant cows and significant differences were observed on 18 d(P < 0.05), whereas no significant changes were observed both in EEM and LEM cows. Interferon-stimulated protein 15 k Da(ISG15), myxovirus-resistance gene(MX) 1 and MX2 mRNA expression in PBLs increased from 14 to 18 d which was significant on 18 d of pregnant cows as well as in LEM cows(P < 0.05), but no changes were observed in EEM cows. To determine whether the expression of CCL8 and CXCL10 in PBLs was regulated by pregnancy-related substances or not, expression level was assessed after exposure to interferon-τ(IFNT) and CCL16. Monocytes, granulocytes and lymphocytes were obtained using density-gradient centrifugation and flow cytometry. The addition of IFNT(100 ng/mL) and CCL16(100 ng/mL) to cultured PBLs increased the expression of CCL8 and CXCL10 mRNA(P < 0.05). The expression of ISG15, MX1 and MX2 mRNA in PBLs was also stimulated by IFNT and CCL16(P < 0.05).Conclusions: The expression of CCL8 and CXCL10 genes increased in PBLs during early pregnancy. Since IFNT stimulated CCL8 and CXCL10 expression in cultured PBLs, the increase of CCL8 and CXCL10 might be pregnancy-dependent *** expression of both CCL8 and CXCL10 in PBLs was stimulated by CCL16 as wel as IFNT, suggesting a chemokine interaction that at least includes CCL8, CXCL10 and CCL16, and m

关键词： CCL8 Cow CXCL10 Leukocytes Pregnancy

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Treatment of Elderly Bedridden Patients with Removable Dentures to Promote Their Daily Physical Activities: A Case-Control Study

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Advances in Aging Research 2020年第6期9卷 116-125页

作者： Yoshiro fujii Shin-Kobe Dental Clinic Kobe Japan

Bedridden patients remain in bed for various reasons, such as chronic illness, old age, and disability, and they cannot perform self-care activities completely or partially. The provision of care for bedridden patients is a major issue in the aging population. Effective rehabilitation is associated with several factors such as cooperation between the patient and the medical staff, selection of effective facilities, and the financial burden. The objective of this study was to evaluate the effect on the activities of daily living (ADL) of occlusion restoration using removable dentures in bedridden older people. This case-control study comprised 32 bedridden older patients who were divided into two groups as follows: denture (n = 18) and no-denture (n = 14). No rehabilitation was provided to any of the patients. The patients were evaluated 3 months after placing the denture, and the ADLs were compared between the two groups. Of the 18 bedridden patients who received removable dentures, 55.6% demonstrated improvements in the ADLs, and the effects persisted for at least 3 months. No improvement in the ADL was observed in the no-denture group. The results of this study suggested that adequate occlusal support can improve the ADL of the elderly. Thus, it is important to take care of oral health early in life in order to maintain oral health, which could help prevent the decrease in the ADL during the later stages of life.

关键词： Bedridden Patient Activities of Daily Living (ADL) Older Patient Occlusal Treatment Denture

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Two Cases of Severe Dementia Showing Dramatic Improvement after Denture Placement

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Advances in Alzheimer's Disease 2016年第2期5卷 46-52页

作者： Yoshiro fujii Shin Kobe Dental Clinic Kobe City Japan

Severe dementia, including Alzheimer’s disease, is intractable and progressive. The purpose of this study was to document the improvement observed in two cases of severe dementia after denture placement. The subjects, two women in their 70s with severe dementia, were diagnosed with Alzheimer’s disease by the medical doctors in charge of their cases. In the first case, the subject’s symptoms included severe disorientation, impaired communication, and a tendency to wander. Two weeks after a lower complete denture placement, she was able to greet others. Five weeks later, she was able to communicate and precisely read an analog clock. Her condition continued to improve for at least 3 months. In the second case, the subject’s mouth was always open. She was bedridden in a vegetative state and hardly moved, talked, or laughed;it was impossible to communicate with her. Only a few seconds after an upper complete denture placement, she started to talk, albeit unintelligibly. Two weeks after a lower complete denture placement, she could communicate normally, laugh, and walk without help. Although the underlying mechanism has not yet been clarified, the author hypothesizes that positive signals from the oral area are transferred to the brain as positive stimulation via the trigeminal nerve, the largest cranial nerve.

关键词： Dementia Alzheimer’s Disease Complete Denture Dental Treatment Trigeminal Nerve

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