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How are multiple satellites seen from the ground? Relative apparent motion and formation stabilization

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Astrodynamics 2024年第1期8卷 121-134页

作者： kenta Nakajima Yasuhiro Yoshimura Hongru Chen Toshiya Hanada Department of Aeronautics and Astronautics Kyushu University744 Motooka Nishi-kuFukuoka819-0395Japan

This paper answers how multiple satellites are seen from the ground. This question is inspired by space-advertising, a public exhibition in the night sky using a dot matrix of satellites that are bright enough to be seen by the naked eye. Thus, it is important for space advertisement that the specific dot matrix is seen. Moreover, the stability of the dot matrix during a visible span is very valuable. To stabilize the dot matrix, this study formulates an apparent position of a dot from a representative dot seen from the ground. The formulation, linear functions of a set of relative orbital elements, reveals the appearance of the dot matrix. The proposed relative variable in the formulation drives the instability of the dot matrix, thereby revealing an initial stable configuration of deputies from a chief. The arbitrary dot matrix designed using the configuration is stable even at low elevations without orbital control during the visible span.

关键词： formation flying relative motion stabilization astrodynamics multi-apparent motions space advertisement

The neutrophil–osteogenic cell axis promotes bone destruction in periodontitis

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International Journal of Oral Science 2024年第1期16卷 154-162页

作者： Yutaro Ando Masayuki Tsukasaki Nam Cong-Nhat Huynh Shizao Zang Minglu Yan Ryunosuke Muro Kazutaka Nakamura Masatsugu Komagamine Noriko Komatsu Kazuo Okamoto kenta Nakano Tadashi Okamura Akira Yamaguchi Kazuyuki Ishihara Hiroshi Takayanagi Department of Immunology Graduate School of Medicine and Faculty of MedicineThe University of Tokyo7-3-1HongoBunkyo-kuTokyoJapan Department of Microbiology Tokyo Dental College2-1-14 Kanda-Misaki-choChiyoda-kuTokyoJapan Oral Health Science Center Tokyo Dental College2-9-18Kanda-Misaki-choChiyodakuTokyoJapan Department of Osteoimmunology Graduate School of Medicine and Faculty of MedicineThe University of Tokyo7-3-1HongoBunkyo-kuTokyoJapan Unit of Prosthodontics Laboratory of Oral-Maxillofacial Biology Faculty of Odonto-StomatologyUniversity of Medicine and Pharmacy at Ho Chi Minh CityHo Chi Minh CityVietnam Department of Oral and Maxillofacial Surgery Department of Sensory and Motor System MedicineGraduate School of MedicineThe University of TokyoTokyoJapan Division of Rheumatology Department of Internal MedicineKeio University School of MedicineTokyoJapan Department of Laboratory Animal Medicine Research InstituteNational Center for Global Health and MedicineTokyoJapan

The immune-stromal cell interactions play a key role in health and diseases. In periodontitis, the most prevalent infectious disease in humans, immune cells accumulate in the oral mucosa and promote bone destruction by inducing receptor activator of nuclear factor-κB ligand (RANKL) expression in osteogenic cells such as osteoblasts and periodontal ligament cells. However, the detailed mechanism underlying immune–bone cell interactions in periodontitis is not fully understood. Here, we performed single-cell RNAsequencing analysis on mouse periodontal lesions and showed that neutrophil–osteogenic cell crosstalk is involved in periodontitis-induced bone loss. The periodontal lesions displayed marked infiltration of neutrophils, and in silico analyses suggested that the neutrophils interacted with osteogenic cells through cytokine production. Among the cytokines expressed in the periodontal neutrophils, oncostatin M (OSM) potently induced RANKL expression in the primary osteoblasts, and deletion of the OSM receptor in osteogenic cells significantly ameliorated periodontitis-induced bone loss. Epigenomic data analyses identified the OSM-regulated RANKL enhancer region in osteogenic cells, and mice lacking this enhancer showed decreased periodontal bone loss while maintaining physiological bone metabolism. These findings shed light on the role of neutrophils in bone regulation during bacterial infection, highlighting the novel mechanism underlying osteoimmune crosstalk.

关键词： period neutrophil destruction

Emotion Measurement Using Biometric Signal

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Health 2024年第5期16卷 395-404页

作者： Yukina Miyagi Saori Gocho Yuka Miyachi Chika Nakayama Shoshiro Okada kenta Maruyama Taeyuki Oshima College of Pharmacy Kinjo Gakuin University Nagoya Japan Graduate School of Medicine Aichi Medical University Nagakute Japan Department of Pharmacy Nagoya Ekisaikai Hospital Nagoya Japan Department of Pharmacy Gifu University of Medical Science Kani Japan

In recent years, research on the estimation of human emotions has been active, and its application is expected in various fields. Biological reactions, such as electroencephalography (EEG) and root mean square successive difference (RMSSD), are indicators that are less influenced by individual arbitrariness. The present study used EEG and RMSSD signals to assess the emotions aroused by emotion-stimulating images in order to investigate whether various emotions are associated with characteristic biometric signal fluctuations. The participants underwent EEG and RMSSD while viewing emotionally stimulating images and answering the questionnaires. The emotions aroused by emotionally stimulating images were assessed by measuring the EEG signals and RMSSD values to determine whether different emotions are associated with characteristic biometric signal variations. Real-time emotion analysis software was used to identify the evoked emotions by describing them in the Circumplex Model of Affect based on the EEG signals and RMSSD values. Emotions other than happiness did not follow the Circumplex Model of Affect in this study. However, ventral attentional activity may have increased the RMSSD value for disgust as the β/θ value increased in right-sided brain waves. Therefore, the right-sided brain wave results are necessary when measuring disgust. Happiness can be assessed easily using the Circumplex Model of Affect for positive scene analysis. Improving the current analysis methods may facilitate the investigation of face-to-face communication in the future using biometric signals.

关键词： Biometric Signals Electroencephalogram Electrocardiogram Emotion Communication

Novel synthesis of single-crystalline TbCu_(7)-type Sm-Fe powder by low-temperature reduction-diffusion process using molten salt

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Journal of Rare Earths 2022年第7期40卷 1126-1133页

作者： Shusuke Okada kenta Takagi Magnetic Powder Metallurgy Research Center National Institute of Advanced Industrial Science and Technology(AIST)2266-98 AnagahoraShimoshidami MoriyamaNagoya463-8560Japan

In this study,molten salt was used as a solvent for calcium(Ca)to let a reduction-diffusion(R-D)reaction occur below the melting point of Ca(1115 K),which is the lower limit temperature of the co nventional RD process.When the R-D reaction is conducted below 923 K with LiCl molten salt,submicron-sized TbCu_(7)-type Sm-Fe powder is formed.The c/a ratio of the powder estimated by a synchrotron X-ray diffraction pattern is 0.8456,which is consistent with the Sm_(0.67)Fe_(5.667)(SmFe_(8.5))phase.An electron backscatter diffraction analysis reveals that single-crystalline TbCu_(7)-type SmFe_(8.5) powder was synthesized for the first time.

关键词： Reduction-diffusion TbCu_(7) Molten salt Permanent magnet Rare earths

Low-temperature synthesis of Sm-Fe binary compounds by reduction-diffusion process using an eutectic salt solvent

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Rare Metals 2023年第5期42卷 1724-1731页

作者： Jungryang Kim Shusuke Okada kenta Takagi Magnetic Powder Metallurgy Research Center National Institute of Advanced Industrial Science and Technology(AIST)NagoyaAichi463-8560Japan

In this study,the temperature of the low-temperature reduction-diffusion(LTRD)process was successfully decreased to below 600℃by introducing LiClKCl eutectic molten salt with a low eutectic point(352℃)as a solvent for Ca reductant.Therefore,the Sm-Fe binary compounds,which were synthesizable at previously-unexplored low temperatures by the LTRD process using LiCl-KCl eutectic molten salt,were investigated,including whether a new metastable or ThMn_(12)-type Sm-Fe binary phase was formed.The Sm-Fe phase transitions of the SmFe binary compounds at a low temperature were identified,and it was found that MgCu_(2)-type Sm-Fe,PuNi_(3)-type SmFe and TbCu_(7)-type Sm-Fe phases were synthesized and stable at 400,500 and 550℃respectively.Although no new metastable Sm-Fe and ThMn_(12)-type Sm-Fe compounds were discovered in this study,this work can demonstrate that it is possible to synthesize the Sm-Fe phase at very low temperatures by the LTRD process for the first time.

关键词： Low-temperature synthesis Reductiondiffusion process Molten salts Hard magnet Sm-Fe compounds

Local oxynitriding of AZ31 magnesium alloy by atmospheric-pressure plasma treatment at room temperature

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Journal of Magnesium and Alloys 2022年第7期10卷 1878-1886页

作者： kenta Nakazawa Tatsuki Ohashi Shotaro Saiki Shoichi Kikuchi Department of Mechanical Engineering Faculty of EngineeringShizuoka University3-5-1JohokuNaka-kuHamamatsu432-8561Japan Graduate School of Integrated Science and Technology Shizuoka University3-5-1 JohokuNaka-kuHamamatsu432-8561Japan

A surface-hardening treatment for AZ31 magnesium alloy using an atmospheric-pressure plasma jet(APPJ)at room temperature was developed.Magnesium is a potential engineering material because it is lightweight;however,magnesium alloys are difficult to heat-treat because of their low flaming temperature.Magnesium alloy specimens were irradiated with a localized atmospheric-pressure plasma jet generated by dielectric-barrier discharge for 180 s in air.The APPJ excited oxygen and nitrogen molecules in the ambient air,resulting in the formation of an oxynitrided layer;oxygen and nitrogen diffusion layer,on the surface of the magnesium alloy.The hardness and elemental distribution for the treated surface were examined.The top surface of the APPJ-treated magnesium alloy achieved a maximum hardness of 108 HV,which was~1.7 times greater than that of the untreated surface.Elemental analysis using an electron-probe microanalyzer revealed strong oxygen and nitrogen signals corresponding to the hardened region of the magnesium alloy,meaning that the hardness increased as a result of the formation of the oxynitrided layer.The proposed APPJ treatment is a promising approach for locally hardening magnesium alloys without using a heat treatment.

关键词： Magnesium alloy Oxynitriding Atmospheric-pressure plasma jet Hardness Surface modification Diffusion

Effect of mechanical ball milling on the electrical and powder bed properties of gas-atomized Ti-48Al-2Cr-2Nb and elucidation of the smoke mechanism in the powder bed fusion electron b eam melting process

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Journal of Materials Science & Technology 2023年第6期137卷 36-55页

作者： Seungkyun Yim kenta Aoyagi Keiji Yanagihara Huakang Bian Akihiko Chiba Institute for Materials Research Tohoku University2-1-1 KatahiraSendaiMiyagi 980-8577Japan

Smoke is unexpected powder-splashing caused by electrostatic force and is one of the main problems hindering the process stability and applicability of the powder bed fusion electron beam(PBF-EB)tech-nology.In this study,mechanical stimulation was suggested to suppress smoke of gas-atomized(GA)Ti-48Al-2Cr-2Nb powder using Al_(2)O_(3) and WC ball milling.The deformation mechanism of the GA powder depending on the ball milling media was discussed based on the developed particle morphology distribu-tion map and contact mechanics simulation.It was revealed that the rapid decrement of flowability and packing density after WC ball milling owing to the formation of angular fragments by the brittle fracture.The variation of surface and electrical properties by mechanical stimulation was investigated via XPS,TEM,and Impedance analysis.The electrical resistivity of the ball-milled powders gradually decreased with increasing milling duration,despite the increased oxide film thickness,and the capacitive response disappeared in Al-60 and WC-30 via metal-insulator transition.This could be due to the accumulation of strain and defects on the oxide film via mechanical stimulation.The smoke mechanism of ball-milled powders was discussed based on the percolation theory.In the smoke experiment,smoke was more suppressed for WC-10 and WC-20 than that for Al-40 and Al-50,respectively,despite the longer charge dissipation time.This could be due to the high probability of contact with conductive particles.For the Al-60 and WC-30 powders,smoke was further restricted by the formation of a percolation cluster with metal-like electrical conductivity.We believe that this study will contribute to a better understanding of the smoke mechanism and process optimization of the PBF-EB.

关键词： Metal-insulator transition Electron beam melting additive manufacturing Packing density Flowability Smoke mechanism Percolation theory

Increased utilization and mass activity of PtRu on reduced graphene oxide by heat treatment of its aerogel followed by composite with nanomaterials

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Carbon Resources Conversion 2023年第3期6卷 205-214页

作者： kenta Dejima Hirokazu Ishitobi He Gao Mai Saito Nobuyoshi Nakagawa Graduate School of Science and Technology Gunma University1-5-1Tenjin-choKiryuGunma 376-8515Japan Division of Environmental Engineering Science Gunma University1-5-1Tenjin-choKiryuGunma 376-8515Japan Faculty of Science and Technology Gunma University1-5-1Tenjin-choKiryuGunma 376-8515Japan

The method to increase PtRu utilization and its catalytic activity of PtRu nanoparticles supported on reduced graphene oxide(RGO)by avoiding its restacking was proposed with the aim of developing an active catalyst for a direct methanol fuel cell.The heat treatment at 200◦C of the GO aerogel(GOA)prepared by freeze drying of GO ice was introduced to weaken the attractive force of the hydrogen bonding between the GO sheets followed by the composite with the nanoparticles,i.e.,ketjenblack(KB),TiO_(2)and Ti_(4)O_(7),at different weight ratios.The catalyst supported on the heat-treated GOA(RGOA),PtRu/RGOA,improved the PtRu utilization to some extent and also increased the ECSA and mass activity compared to that of PtRu/RGO.RGOA had fewer oxygen functional groups,especially the epoxy groups.Due to the treatment and composite,the PtRu utilization was increased from 66.5%for PtRu/RGO to 128.6%for PtRu/RGOA+Ti_(4)O_(7)(4:1)and the mass activity was improved from 50.7 A/g-PtRu for PtRu/RGO to 130.5 A/g-PtRu for PtRu/RGOA+Ti_(4)O_(7)(1:1).The Ti_(4)O_(7)nanoparticles showed the best catalytic performance for the composite suggesting that the strong interaction between Ti_(4)O_(7)and the Pt nanoparticles was effective due to its high electronic conductivity.

关键词： Reduced graphene oxide Restacking Catalyst utilization Mass activity Composite catalyst Methanol oxidation Ti4O7

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吃喝之第一八佰伴

上海调味品 2008年第6期 32-35页

作者：汤汤 kenta

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关键词：八佰伴美食城浦东南路