Meisei University

Surface activated bonding (SAB) is a room temperature wafer-level bonding technique widely used in the packaging and fabrication of electronic devices. The standard SAB process for Si involves the removal of surface oxides and contamination layers via fast atom bombardment, which generates dangling bonds on the outermost Si surface. However, adsorbed water on wafer surfaces hinders this activation process, leading to degraded bonding quality. In this study, we investigate prebonding baking as a method to eliminate adsorbed water before the SAB step. Experimental results demonstrate that pre-bonding baking significantly enhances bond strength for Si, sapphire, and SiO2 by effectively desorbing water from the wafer surfaces. Additionally, annealing Si wafers prior to SAB reduces residual oxides at the bonding interface, indicating improved activation efficiency. These findings highlight the potential of pre-bonding baking as an effective approach to enhance room-temperature wafer bonding quality using the SAB methodology.

本研究では，デジタル画像の重要性が相対的に低下していると考えられる現代において，デジタル画像に新たな体験価値や鑑賞方法を付与することを目的とし，プロセスアートの概念に基づいた描画システム「Mixing Dropper」を提案・実装する．本システムでは，任意のデジタル画像から抽出した色彩情報を用いて，デジタル画像を絵画として生まれ変わらせる．また，その過程をプロセスアートとして表現し，描画物と鑑賞体験の両視点から，デジタル画像に新たな価値を与える．これを具現化するために，RGB値からCMYK値への変換を基にした自動調色機能，液体の滴下過程を可視化する描画フロー，そして液体特性と支持体特性を利用した偶発性のある表現を統合している．評価実験の結果から，調色手法や調色フロー，描画手法に関する展望が考えられた一方，デジタル画像に対して新たな価値を付与できた．本研究は，従来のデジタル画像技術やプリント技術を補完する新たな視点を提供するとともに，情報技術による芸術表現におけるプロセスアートの応用可能性を拡張するものである．

This paper presents DOLCE (Demonstrational Laser Communication Terminal for Future Experiments), a reconfigurable ground testbed for validating acquisition and tracking control technologies in space optical communication systems. DOLCE integrates both optical and communication components, employing single-mode fiber-based free-space optical communication at 1550 nm wavelength with a target tracking accuracy of 10 μrad. The system features two key characteristics: hardware reconfigurability through a post-based optical breadboard design, and software reconfigurability through distributed IP core architecture on FPGA. Two distinct testing configurations are supported: a tabletop test for quantitative tracking performance evaluation under controlled disturbances, and an equatorial mount test at 100–200 m distance for validating the complete acquisition-to-tracking sequence. For the equatorial mount test, we introduce a beam reducer to expand the beam divergence angle from 0.001 deg to 0.4 deg, enabling proper detection of optical axis misalignment by ensuring sufficient wavefront inclination. Additionally, we demonstrate a method for simulating satellite attitude and gimbal disturbances using the transmitter FPM, based on system identification and power spectral density synthesis. DOLCE provides a flexible validation platform for iterative development of next-generation laser communication terminals.

Abstract Square contingency tables are traditionally analyzed with a focus on the symmetric structure of the corresponding probability tables. We view probability tables as elements of a simplex equipped with the Aitchison geometry. This perspective allows us to present a novel approach to analyzing symmetric structure using a compositionally coherent framework. We present a geometric interpretation of quasi-symmetry as an e-flat subspace and introduce a new concept called geometric marginal homogeneity, which is also characterized as an e-flat structure. We prove that both quasi-symmetric tables and geometric marginal homogeneous tables form subspaces in the simplex, and show that the measure of skew-symmetry in Aitchison geometry can be orthogonally decomposed into measures of departure from quasi-symmetry and geometric marginal homogeneity. We illustrate the application and effectiveness of our proposed methodology using data on unaided distance vision from a sample of women.

Understanding and accurately predicting the thermal behavior of fiber-reinforced polymer (FRP) composites is critical for their reliable application in structural systems. This study focuses on predicting temperature distributions within hybrid FRP sandwich panels composed of a pultruded glass fiber–reinforced polymer box, a closed-cell polyurethane foam core, and a steel fiber–reinforced self-compacting concrete topping layer. An extensive experimental program was conducted under both controlled and external environmental conditions. The controlled phase involved thermal cycling and exposure to a high-pressure sodium lamp to simulate radiant heating effects, while the outdoor phase captured real-world thermal fluctuations. Temperature was monitored using embedded PT100 sensors, and additional equipment was used to record ambient conditions, including solar radiation. Through meticulous experimental analyses and numerical simulations, this research evaluates the boundary conditions and thermal loads affecting the specimens, enabling the development and validation of numerical models. These models were designed to replicate transient heat transfer within the panels, accounting for convective heat exchange, direct and reflected radiation, and the influence of surface moisture during and after rainfall. The models achieved over 92% accuracy compared to experimental data, based on the mean absolute percentage error. Key findings show that disregarding reflected solar radiation from surrounding surfaces resulted in peak temperature underestimations of up to 13.9°C, while neglecting evaporative cooling reduced the overall accuracy by approximately 6%. These results highlight the importance of calibrated numerical models for thermal analysis, ensuring the reliability of FRP-based structures under operational conditions. Furthermore, this research offers valuable insights for defining temperature distribution assessment methodologies regarding FRP composite structures in real-world applications.

In light of globalization, the demands for multicultural coexistence within Japan’s public education system have become increasingly prominent. Drawing on the teacher’s profound insights derived from her distinct roles as an educator, former learner, and parent, this study transcends a conventional case study by revealing how these unique perspectives enrich and redefine teacher agency. Utilizing Bronfenbrenner’s ecological systems theory as a theoretical framework, the study analyzes the dynamic interplay between individual efforts and institutional support across micro, meso, and macro levels. The findings reveal that the teacher’s reflective practices and proactive curriculum and language support initiatives significantly contribute to fostering multicultural coexistence and improving the learning environment within the international class. Furthermore, the study underscores the capacity of educators to leverage their diverse experiences to implement flexible and effective teaching practices, even amid inadequate institutional frameworks. By highlighting these insights, the research offers valuable implications for future educational policies to accommodate cultural and linguistic diversity and promote intercultural competence in Japan’s evolving public education landscape.

Abstract We present a detailed analysis of the kinematics of SiO maser stars around the center of the Milky Way, Sagittarius A$^\ast$ (Sgr A$^\ast$). We used the archive data in the SiO $v=1$, J = 2–1 emission line obtained by the Atacama Large Millimeter/Submillimeter Array (ALMA) in 2017 and 2021 (#2016.1.00940.S, PI J. Darling and #2019.1.00292.S, PI J. Paine). We detected 37 SiO maser stars in the channel maps and derived their angular offsets relative to Sgr A$^\ast$ and LSR radial velocities. We derived the proper motions of 35 stars by comparing their angular offsets in the two epochs. The proper motions of Wolf–Rayet and O star in the nuclear star cluster are reported to be rather random, except for the co-moving clusters IRS13E and IRS13N (Tsuboi et al. 2022, PASJ, 74, 738). However, the derived proper motions of SiO maser stars do not look completely random. The proper motions of the SiO maser stars show a tendency to lie along the Galactic plane. The proper motion amplitudes of SiO maser stars are larger than the local standard of rest (LSR) velocity amplitudes. We estimated the 3D motions from the proper motions and LSR velocities. Many 3D velocities are near to or larger than the upper limit velocities for Kepler orbits around Sgr A$^\ast$, whose mass is assumed to be $4\times 10^6$ M$_{\odot }$. These indicate that the SiO maser stars around Sgr A$^\ast$ are members of the nuclear stellar disk rather than the nuclear star cluster.

Natural products such as polyketides often possess spin systems consisting of a methine group directly bonded to a methyl group (e.g. –CHa(OH)–CHb(CH3)–CHc(OH)–). The methine proton Hb splits into a broadened multiplet by coupling with several vicinal protons, such as Ha and Hc, rendering the analysis of nJ C–H and nJ H–H with respect to Hb difficult using conventional NMR techniques. In this case, the stereochemical analysis of the aforementioned chain structure is generally hard due to the limited information of nJ C–H and nJ H–H. In order to obtain a more accurate analysis, we applied a novel NOE quantification, in which the NOE signal between Hb and CH3 in the aforesaid spin system is used as a reference in a 1D double pulsed field gradient spin echo (DPFGSE)-NOESY spectra. The combinational analysis of the proposed NOE quantification together with nJ C–H and nJ H–H provided a reliable determination of stereochemistry of the sidechain in portmicin.

This introduction to the special section on COOL Chips discusses the state-of-the-art low-power, high-speed chips and the challenges facing researchers. It introduces three articles that explore different solutions to reducing power consumption and enhancing chip performance.