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Laser-assisted direct roller imprinting of large-area microstructured optical surfaces

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Microsystems & Nanoengineering 2024年第1期10卷 257-266页

作者： Keisuke Nagato Ken Takahashi Yuki Yajima Masayuki Nakao Department of Mechanical Engineering Graduate School of EngineeringThe University of Tokyo7-3-1 HongoBunkyo-kuTokyo 113-8656Japan

In this study,a high-throughput fabrication method called laser-assisted direct roller imprinting(LADRI)was developed to lower the cost of nanoimprinting large-area polymer films and to address problems associated with nanoimprinting,namely,microstructural damage and precision in flatness of entire film.With LADRI,the laser directly heats the microstructured surface of the roller mold,which heats and melts the surface of a polymethyl methacrylate(PMMA)film to replicate the microstructures on the mold rapidly.In this study,the effects of laser power density,scanning speed,size of the microstructures,and contact pressure on the replication speed were investigated experimentally.The replication speed increased as the power and scanning speed increased.However,because the film required heating until it filled the entire depth of the microstructure,an appropriate replication speed was necessary.This result was supported by simulation of the temperature distribution inside the mold and the PMMA using transient heat conduction analyses.To demonstrate the applications of LADRI,two different optical surfaces were replicated:an antireflection(AR)structure with conical structures sized several hundred nanometers and a lightextraction structure with a microlens array(MLA)comprising 10μm lenses,for display and illumination,respectively.The replication degree of the MLA was governed by the contact pressure.Polymer flow simulation indicated that the heat conduction and flow speeds of the melted PMMA surface were comparable within several tens of micrometers.In addition,the reflectivity of the AR structure decreased from 4 to 0.5%,and the light intensity of the light-extraction structure increased by a factor of 1.47.

关键词： microstructure roller conduction

Quasi-periodic orbits of small solar sails with time-varying attitude around Earth–Moon libration points

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Astrodynamics 2024年第1期8卷 161-174页

作者： Toshihiro Chujo Department of Mechanical Engineering School of EngineeringTokyo Institute of TechnologyTokyo152-8550Japan

This paper proposes new quasi-periodic orbits around Earth–Moon collinear libration points using solar sails.By including the time-varying sail orientation in the linearized equations of motion for the circular restricted three-body problem(CR3BP),four types of quasi-periodic orbits(two types around L1 and two types around L2)were formulated.Among them,one type of orbit around L2 realizes a considerably small geometry variation while ensuring visibility from the Earth if(and only if)the sail acceleration due to solar radiation pressure is approximately of a certain magnitude,which is much smaller than that assumed in several previous studies.This means that only small solar sails can remain in the vicinity of L2 for a long time without propellant consumption.The orbits designed in the linearized CR3BP can be translated into nonlinear CR3BP and high-fidelity ephemeris models without losing geometrical characteristics.In this study,new quasi-periodic orbits are formulated,and their characteristics are discussed.Furthermore,their extendibility to higher-fidelity dynamic models was verified using numerical examples.

关键词： solar sail libration point orbit Earth-Moon system circular restricted three-body problem(CR3BP)

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

A plant growth chamber system equipped with aerosol generators for studying aerosol-vegetation interactions

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Particuology 2024年第2期85卷 122-132页

作者： Masao Gen Seiji Ikawa Masahiro Yamaguchi Fong Zyin Lim Takeshi Izuta I.Wuled Lenggoro Graduate School of Bio-Applications and Systems Engineering Tokyo University of Agriculture and TechnologyKoganeiTokyo184-8588Japan Institute of Multidisciplinary Research for Advanced Materials Tohoku UniversitySendai980-8577Japan Faculty of Agriculture Tokyo University of Agriculture and TechnologyFuchuTokyo183-8509Japan Graduate School of Fisheries and Environmental Sciences Nagasaki UniversityNagasaki852-8521Japan Institute of Agriculture Tokyo University of Agriculture and TechnologyFuchuTokyo183-8509 Japan Department of Applied Physics and Chemical Engineering Tokyo University of Agriculture and TechnologyKoganeiTokyo184-8588Japan Institute of Global Innovation Research Tokyo University of Agriculture and TechnologyFuchuTokyo183-8509Japan

Understanding aerosol-vegetation interactions is vital in ecosystems.However,the interactions remain elusive partly due to the lack of suitable plant growth chamber systems.Particularly,deposition of submicron particles on leaf surfaces is challenging due to its low deposition velocities compared to larger particles.In this work,we present a plant-growth chamber that was used to study the effect of sub-micron black carbon(BC)particles on the growth and photosynthesis of plants.The chamber system simultaneously enables the growth of multiple plants in pots and the deposition of submicron particles onto them.Two spraying methods assisted by ultrasonic and electrostatic forces were employed as aerosol generators to realize the particle deposition.The flow regime inside the chamber was numeri-cally calculated to predict the transportation of aerosol particles,suggesting the optimal operating conditions of the chamber.The gas-phase particle size distribution measurements showed that gener-ated BC particles were suspended in submicron diameter ranges.The aerosol generators were examined in the chamber using three conductor and insulator substrates as a model of plant leaves.Microscope observations and spectroscopic analysis ascertained that submicron BC particles generated from our generators were deposited on all substrate surfaces.Using the developed chamber system,systematic studies can be performed to advance the fundamental understanding of aerosol-vegetation interactions.

关键词： Aerosol Exposure chamber Spray drying Black carbon

Investigation of Inside-Out Tracking Methods for Six Degrees of Freedom Pose Estimation of a Smartphone in Augmented Reality

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Computers, Materials & Continua 2024年第5期79卷 3047-3065页

作者： Chanho Park Takefumi Ogawa Graduate School of Engineering The University of TokyoTokyo113-0033Japan Information Technology Center The University of TokyoChiba277-0882Japan

Six degrees of freedom(6DoF)input interfaces are essential formanipulating virtual objects through translation or rotation in three-dimensional(3D)space.A traditional outside-in tracking controller requires the installation of expensive hardware in advance.While inside-out tracking controllers have been proposed,they often suffer from limitations such as interaction limited to the tracking range of the sensor(e.g.,a sensor on the head-mounted display(HMD))or the need for pose value modification to function as an input interface(e.g.,a sensor on the controller).This study investigates 6DoF pose estimation methods without restricting the tracking range,using a smartphone as a controller in augmented reality(AR)environments.Our approach involves proposing methods for estimating the initial pose of the controller and correcting the pose using an inside-out tracking approach.In addition,seven pose estimation algorithms were presented as candidates depending on the tracking range of the device sensor,the tracking method(e.g.,marker recognition,visual-inertial odometry(VIO)),and whether modification of the initial pose is necessary.Through two experiments(discrete and continuous data),the performance of the algorithms was evaluated.The results demonstrate enhanced final pose accuracy achieved by correcting the initial pose.Furthermore,the importance of selecting the tracking algorithm based on the tracking range of the devices and the actual input value of the 3D interaction was emphasized.

关键词： Smartphone inside-out tracking 6DoF pose 3D interaction augmented reality

Experimental investigation on effective aerosol scavenging using different spray configurations with pre-injection of water mist for Fukushima Daiichi decommissioning

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Nuclear Science and Techniques 2024年第5期35卷 154-172页

作者： Rui-Cong Xu Avadhesh Kumar Sharma Erdal Ozdemir Shuichiro Miwa Shunichi Suzuki Department of Nuclear Engineering and Management The University of Tokyo7‑3‑1 HongoBunkyo‑KuTokyo 113‑8656Japan Nuclear Professional School The University of Tokyo2‑2

During the decommissioning of the Fukushima Daiichi nuclear power plant,it is important to consider the retrieval of resolidified debris both in air and underwater configurations.For the subsequent retrieval of debris from the reactor building,the resolidified debris must be cut into smaller pieces using various cutting methods.During the cutting process,aerosol particles are expected to be generated at the submicron scale.It has been noted that such aerosols sizing within the Greenfield gap(0.1-1μm)are difficult to remove effectively using traditional spraying methods.Therefore,to improve the aerosol removal efficiency of the spray system,a new aerosol agglomeration method was recently proposed,which involves injecting water mist to enlarge the sizes of the aerosol particles before removing them using water sprays.In this study,a series of experiments were performed to clarify the proper spray configurations for effective aerosol scavenging and to improve the performance of the water mist.The experimental results showed that the spray flow rate and droplet characteristics are important factors for the aerosol-scavenging efficiency and performance of the water mist.The results obtained from this study will be helpful for the optimization of the spray system design for effective aerosol scavenging during the decommissioning of the Fukushima Daiichi plant.

关键词： Fukushima Daiichi decommissioning Aerosol scavenging Multiphase flow Spray system Aerosol-mist agglomeration

Thermal stability of the Cr-coated zirconium alloy microstructure prepared by pulsed laser deposition

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Tungsten 2024年第2期6卷 333-341页

作者： Bo Li Hui-Long Yang Reuben Holmes Li-Juan Cui Sho Kano Hiroaki Abe Department of Nuclear Engineering and Management The University of TokyoTokyo 113-8656Japan School of Nuclear Science and Engineering Shanghai Jiao Tong UniversityShanghai 200240China Nuclear Professional School The University of TokyoIbaraki 319-1188Japan

Cr-coated zirconium alloy was prepared by pulsed laser deposition(PLD)for the application of accident-tolerant fuel cladding in light water reactors.The microstructural characteristics of the Cr coating and its evolution with temperature were investigated using grazing incidence X-ray diff raction and in situ heating transmission electron microscopy(TEM).Results show that the microstructure of the laser-deposited Cr coatings consists mainly of fine and non-specific shaped nano-crystals in the inner layer and columnar crystals in the outer layer.The recrystallization of the Cr-coating layer starts at 300–400℃ to release the high strain introduced by PLD,and the grain coalescence starts at temperatures>400°C.Upon annealing,the(110)-texture gradually intensifi es because of its high reticular density and low close-packed energy.Additionally,in situ heating TEM observation shows the presence of cavities on the Cr–Zr interface,which may result from the interdiff usion and/or the transformation from amorphous to crystalline.

关键词： Accident tolerant fuel Crcoating Interface Microstructure Pulsed laser deposition

The evolution of cancer genomic medicine in Japan and the role of the National Cancer Center Japan

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Cancer Biology & Medicine 2024年第1期21卷 29-44页

作者： Teruhiko Yoshida Yasushi Yatabe Ken Kato Genichiro Ishii Akinobu Hamada Hiroyuki Mano Kuniko Sunami Noboru Yamamoto Takashi Kohno Department of Genetic Medicine and Services National Cancer Center HospitalTokyo 104-0045Japan Department of Diagnostic Pathology National Cancer Center HospitalTokyo 104-0045Japan Clinical Research Support Offce Clinical Research Coordinating SectionBiobank Translational Research Support SectionNational Cancer Center HospitalTokyo 104-0045Japan Department of Pathology and Clinical Laboratories National Cancer Center Hospital EastChiba 277-8577Japan Division of Molecular Pharmacology National Cancer Center Research InstituteTokyo 104-0045Japan National Cancer Center Research Institute Tokyo 104-0045Japan Department of Laboratory Medicine National Cancer Center HospitalTokyo 104-0045Japan Department of Experimental Therapeutics National Cancer Center HospitalTokyo 104-0045Japan Division of Genome Biology National Cancer Center Research InstituteTokyo 104-0045Japan

The journey to implement cancer genomic medicine(CGM)in oncology practice began in the 1980s,which is considered the dawn of genetic and genomic cancer research.At the time,a variety of activating oncogenic alterations and their functional significance were unveiled in cancer cells,which led to the development of molecular targeted therapies in the 2000s and beyond.Although CGM is still a relatively new discipline and it is difficult to predict to what extent CGM will benefit the diverse pool of cancer patients,the National Cancer Center(NCC)of Japan has already contributed considerably to CGM advancement for the conquest of cancer.Looking back at these past achievements of the NCC,we predict that the future of CGM will involve the following:1)A biobank of paired cancerous and non-cancerous tissues and cells from various cancer types and stages will be developed.The quantity and quality of these samples will be compatible with omics analyses.All biobank samples will be linked to longitudinal clinical information.2)New technologies,such as whole-genome sequencing and artificial intelligence,will be introduced and new bioresources for functional and pharmacologic analyses(e.g.,a patient-derived xenograft library)will be systematically deployed.3)Fast and bidirectional translational research(bench-to-bedside and bedside-to-bench)performed by basic researchers and clinical investigators,preferably working alongside each other at the same institution,will be implemented;4)Close collaborations between academia,industry,regulatory bodies,and funding agencies will be established.5)There will be an investment in the other branch of CGM,personalized preventive medicine,based on the individual's genetic predisposition to cancer.

关键词： Cancer genomic medicine biobank patient-derived xenograft multi-gene panel test whole genome sequencing

Optimization of body configuration and joint-driven attitude stabilization for transformable spacecraft under solar radiation pressure

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Astrodynamics 2024年第1期8卷 47-60页

作者： Yuki Kubo Toshihiro Chujo Institute of Space and Astronautical Science Japan Aerospace Exploration AgencyKanagawa252-5210Japan Department of Mechanical Engineering Tokyo Institute of TechnologyTokyo152-8550Japan

The solar sail is one of the most promising space exploration systems due to its theoretically infinite specific impulse achieved through solar radiation pressure(SRP).Recently,researchers have proposed“transformable spacecraft”capable of actively reconfiguring their body configurations using actuatable joints.Transformable spacecraft,if used similarly to solar sails,are expected to significantly enhance orbit and attitude control capabilities owing to their high redundancy in control degrees of freedom.However,controlling them becomes challenging due to their large number of inputs,leading previous researchers to impose strong constraints to limit their potential control capabilities.This study focuses on novel attitude control techniques for transformable spacecraft under SRP.We developed two methods,namely,joint angle optimization to obtain arbitrary SRP force and torque,and momentum damping control driven by joint angle actuation.Our proposed methods are formulated in a general manner and can be applied to any transformable spacecraft comprising front faces that can predominantly receive the SRP on each body.The validity of our proposed method is confirmed through numerical simulations.Our study contributes to making most of the high control redundancy of transformable spacecraft without the need for expendable propellants,thus significantly enhancing the orbit and attitude control capabilities.

关键词： solar sail transformable spacecraft attitude-joint coupled motion attitudestabilization